Laser diode technology for coherent communications

NASA Technical Reports Server (NTRS)

Channin, D. J.; Palfrey, S. L.; Toda, M.

1989-01-01

The effect of diode laser characteristics on the overall performance capabilities of coherent communication systems is discussed. In particular, attention is given to optical performance issues for diode lasers in coherent systems, measurements of key performance parameters, and optical requirements for coherent single-channel and multichannel communication systems. The discussion also covers limitations imposed by diode laser optical performance on multichannel system capabilities and implications for future developments.

Diode laser (980nm) cartilage reshaping

NASA Astrophysics Data System (ADS)

El Kharbotly, A.; El Tayeb, T.; Mostafa, Y.; Hesham, I.

2011-03-01

Loss of facial or ear cartilage due to trauma or surgery is a major challenge to the otolaryngologists and plastic surgeons as the complicated geometric contours are difficult to be animated. Diode laser (980 nm) has been proven effective in reshaping and maintaining the new geometric shape achieved by laser. This study focused on determining the optimum laser parameters needed for cartilage reshaping with a controlled water cooling system. Harvested animal cartilages were angulated with different degrees and irradiated with different diode laser powers (980nm, 4x8mm spot size). The cartilage specimens were maintained in a deformation angle for two hours after irradiation then released for another two hours. They were serially measured and photographed. High-power Diode laser irradiation with water cooling is a cheep and effective method for reshaping the cartilage needed for reconstruction of difficult situations in otorhinolaryngologic surgery. Key words: cartilage,diode laser (980nm), reshaping.

Comparative Study of Diode Laser Versus Neodymium-Yttrium Aluminum: Garnet Laser Versus Intense Pulsed Light for the Treatment of Hirsutism.

PubMed

Puri, Neerja

2015-01-01

Lasers are widely used for the treatment of hirsutism. But the choice of the right laser for the right skin type is very important. Before starting with laser therapy, it is important to assess the skin type, the fluence, the pulse duration and the type of laser to be used. To compare the efficacy and side effects of Diode laser, Neodymium-yttrium aluminum - garnet (Nd: YAG) laser and intense pulsed light (IPL) on 30 female patients of hirsutism. Thirty female patients with hirsutism were selected for a randomised controlled study. The patients were divided into three groups of 10 patients each. In group I patients diode laser was used, in group II patients long pulsed Nd: YAG laser was used and in group III, IPL was used. The patients were evaluated and result graded according to a 4-point scale as excellent, >75% reduction; good, 50-75% reduction; fair; 25-50% reduction; and poor, <25% reduction in hair density. It was seen that the percentage of hair reduction after two sessions of treatment was maximum (40%) in the diode laser group, followed by 35% hair reduction in the Nd: Yag laser group and 10% hair reduction in the IPL group. The percentage of hair reduction after four sessions of treatment was maximum (64%) in the diode laser group, followed by 62% hair reduction in the Nd: Yag laser group and 48% hair reduction in the IPL group. The percentage of hair reduction after eight sessions of treatment was maximum (92%) in the diode laser group, followed by 90% hair reduction in the Nd: YAG group and 70% hair reduction in the IPL group. To conclude for the Indian skin with dark hairs, the diode laser still stands the test of time. But, since the diode laser has a narrow margin of safety, proper pre and post-procedure cooling is recommended. Although, the side effects of Nd: YAG laser are less as compared to the diode laser, it is less efficacious as compared to the diode laser.

Comparative Study of Diode Laser Versus Neodymium-Yttrium Aluminum: Garnet Laser Versus Intense Pulsed Light for the Treatment of Hirsutism

PubMed Central

Puri, Neerja

2015-01-01

Introduction: Lasers are widely used for the treatment of hirsutism. But the choice of the right laser for the right skin type is very important. Before starting with laser therapy, it is important to assess the skin type, the fluence, the pulse duration and the type of laser to be used. Aims: To compare the efficacy and side effects of Diode laser, Neodymium-yttrium aluminum — garnet (Nd: YAG) laser and intense pulsed light (IPL) on 30 female patients of hirsutism. Materials and Methods: Thirty female patients with hirsutism were selected for a randomised controlled study. The patients were divided into three groups of 10 patients each. In group I patients diode laser was used, in group II patients long pulsed Nd: YAG laser was used and in group III, IPL was used. The patients were evaluated and result graded according to a 4-point scale as excellent, >75% reduction; good, 50-75% reduction; fair; 25-50% reduction; and poor, <25% reduction in hair density. Results: It was seen that the percentage of hair reduction after two sessions of treatment was maximum (40%) in the diode laser group, followed by 35% hair reduction in the Nd: Yag laser group and 10% hair reduction in the IPL group. The percentage of hair reduction after four sessions of treatment was maximum (64%) in the diode laser group, followed by 62% hair reduction in the Nd: Yag laser group and 48% hair reduction in the IPL group. The percentage of hair reduction after eight sessions of treatment was maximum (92%) in the diode laser group, followed by 90% hair reduction in the Nd: YAG group and 70% hair reduction in the IPL group. Conclusions: To conclude for the Indian skin with dark hairs, the diode laser still stands the test of time. But, since the diode laser has a narrow margin of safety, proper pre and post-procedure cooling is recommended. Although, the side effects of Nd: YAG laser are less as compared to the diode laser, it is less efficacious as compared to the diode laser. PMID:26157309

A 1,470 nm diode laser in stapedotomy: Mechanical, thermal, and acoustic effects.

PubMed

Koenraads, Simone P C; de Boorder, Tjeerd; Grolman, Wilko; Kamalski, Digna M A

2017-08-01

Multiple laser systems have been investigated for their use in stapes surgery in patients with otosclerosis. The diode 1,470 nm laser used in this study is an attractive laser system because it is easily transported and relatively inexpensive in use. This wavelength has relative high absorption in water. This study aimed to investigate the mechanical, thermal, and acoustic effects of the diode 1,470 nm laser on a stapes in an inner ear model. Experiments were performed in an inner ear model including fresh frozen human stapes. High-speed imaging with frame rates up to 2,000 frames per second (f/s) was used to visualize the effects in the vestibule during fenestration of the footplate. A special high-speed color Schlieren technique was used to study thermal effects. The sound produced by perforation was recorded by a hydrophone. Single pulse settings of the diode 1,470 nm laser were 100 ms, 3 W. Diode 1,470 nm laser fenestration showed mechanical effects with small vapor bubbles and pressure waves pushed into the vestibule. Thermal imaging visualized an increase temperature underneath the stapes footplate. Acoustic effects were limited, but larger sounds levels were reached when vaporization bubbles arise and explode in the vestibule. The diode 1,470 nm laser highly absorbs in perilymph and is capable of forming a clear fenestration in the stapes. An overlapping laser pulse will increase the risk of vapor bubbles, pressure waves, and heating the vestibule. As long as we do not know the possible damage of these effects to the inner ear function, it seems advisable to use the laser with less potential harm. Lasers Surg. Med. 49:619-624, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

New Submount Requirement of Conductively Cooled Laser Diodes for Lidar Applications

NASA Technical Reports Server (NTRS)

Mo, S. Y.; Cutler, A. D.; Choi, S. H.; Lee, M. H.; Singh, U. N.

2000-01-01

New submount technology is essential for the development of conductively cooled high power diode laser. The simulation and experimental results indicate that thermal conductivity of submount for high power laser-diode must be at least 600 W/m/k or higher for stable operation. We have simulated several theoretical thermal model based on new submount designs and characterized high power diode lasers to determine temperature effects on the performances of laser diodes. The characterization system measures the beam power, output beam profile, temperature distribution, and spectroscopic property of high power diode laser. The characterization system is composed of four main parts: an infrared imaging camera, a CCD camera, a monochromator, and a power meter. Thermal characteristics of two commercial-grade CW 20-W diode laser bars with open heat-sink type were determined with respect to the line shift of emission spectra and beam power stability. The center wavelength of laser emission has a tendency to shift toward longer wavelength as the driving current and heat sink temperature are increased. The increase of heat sink temperature decreases the output power of the laser bar too. Such results lay the guidelines for the design of new submount for high power laser-diodes.

Diode lasers: From laboratory to industry

NASA Astrophysics Data System (ADS)

Nasim, Hira; Jamil, Yasir

2014-03-01

The invention of first laser in 1960 triggered the discovery of several new families of lasers. A rich interplay of different lasing materials resulted in a far better understanding of the phenomena particularly linked with atomic and molecular spectroscopy. Diode lasers have gone through tremendous developments on the forefront of applied physics that have shown novel ways to the researchers. Some interesting attributes of the diode lasers like cost effectiveness, miniature size, high reliability and relative simplicity of use make them good candidates for utilization in various practical applications. Diode lasers are being used by a variety of professionals and in several spectroscopic techniques covering many areas of pure and applied sciences. Diode lasers have revolutionized many fields like optical communication industry, medical science, trace gas monitoring, studies related to biology, analytical chemistry including elemental analysis, war fare studies etc. In this paper the diode laser based technologies and measurement techniques ranging from laboratory research to automated field and industry have been reviewed. The application specific developments of diode lasers and various methods of their utilization particularly during the last decade are discussed comprehensively. A detailed snapshot of the current state of the art diode laser applications is given along with a detailed discussion on the upcoming challenges.

Effect of Diode Laser Irradiation Combined with Topical Fluoride on Enamel Microhardness of Primary Teeth.

PubMed

Bahrololoomi, Zahra; Lotfian, Malihe

2015-02-01

Laser irradiation has been suggested as an adjunct to traditional caries prevention methods. But little is known about the cariostatic effect of diode laser and most studies available are on permanent teeth.The purpose of the present study was to investigate the effect of diode laser irradiation combined with topical fluoride on enamel surface microhardness. Forty-five primary teeth were used in this in vitro study. The teeth were sectioned to produce 90 slabs. The baseline Vickers microhardness number of each enamel surface was determined. The samples were randomly divided into 3 groups. Group 1: 5% NaF varnish, group 2: NaF varnish+ diode laser at 5 W power and group 3: NaF varnish+ diode laser at 7 W power. Then, the final microhardness number of each surface was again determined. The data were statistically analyzed by repeated measures ANOVA at 0.05 level of significance. In all 3 groups, microhardness number increased significantly after surface treatment (P<0.05). However, Microhardness change after treatment was not significantly different among groups (P >0.05). The combined application of diode laser and topical fluoride varnish on enamel surface did not show any significant additional effect on enamel resistance to caries.

Effect of radiant heat on conventional glass ionomer cements during setting by using a blue light diode laser system (445 nm).

PubMed

Dionysopoulos, Dimitrios; Tolidis, Kosmas; Strakas, Dimitrios; Gerasimou, Paris; Sfeikos, Thrasyvoulos; Gutknecht, Norbert

2017-04-01

The aim of this in vitro study was to evaluate the effect of radiant heat on surface hardness of three conventional glass ionomer cements (GICs) by using a blue diode laser system (445 nm) and a light-emitting diode (LED) unit. Additionally, the safety of the laser treatment was evaluated. Thirty disk-shaped specimens were prepared of each tested GIC (Equia Fil, Ketac Universal Aplicap and Riva Self Cure). The experimental groups (n = 10) of the study were as follows: group 1 was the control group of the study; in group 2, the specimens were irradiated for 60 s at the top surface using a LED light-curing unit; and in group 3, the specimens were irradiated for 60 s at the top surface using a blue light diode laser system (445 nm). Statistical analysis was performed using one-way ANOVA and Tukey post-hoc tests at a level of significance of a = 0.05. Radiant heat treatments, with both laser and LED devices, increased surface hardness (p < 0.05) but in different extent. Blue diode laser treatment was seemed to be more effective compared to LED treatment. There were no alterations in surface morphology or chemical composition after laser treatment. The tested radiant heat treatment with a blue diode laser may be advantageous for the longevity of GIC restorations. The safety of the use of blue diode laser for this application was confirmed.

Endoluminal laser delivery mode and wavelength effects on varicose veins in an ex vivo model.

PubMed

Massaki, Ane B M N; Kiripolsky, Monika G; Detwiler, Susan P; Goldman, Mitchel P

2013-02-01

Endovenous laser ablation (EVLA) has been shown to be effective for the elimination of saphenous veins and associated reflux. Mechanism is known to be heat related, but precise way in which heat causes vein ablation is not completely known. This study aimed to determine the effects of various endovenous laser wavelengths and delivery modes on ex vivo human vein both macroscopically and microscopically. We also evaluated whether protected-tip fibers, consisting of prototype silica fibers with a metal tube over the distal end, reduced vein wall perforations compared with non-protected-tip fibers. An ex vivo EVLA model with human veins harvested during ambulatory phlebectomy procedures was used. Six laser fiber combinations were tested: 810 nm continuous wave (CW) diode laser with a flat tip fiber, 810 CW diode laser with a protected tip fiber, 1,320 nm pulsed Nd:YAG laser, 1,310 nm CW diode laser, 1,470 nm CW diode laser, and 2,100 nm pulsed Ho:YAG laser. Perforation or full thickness necrosis of a portion of the vein wall was observed in 5/11 (45%), 0/11 (0%), 3/22 (14%), 7/11 (64%), 4/6 (67%), and 5/10 (50%) of cross-sections of veins treated with the 810 nm CW diode laser with a flat tip fiber, the 810 CW diode laser with a protected tip fiber, the 1,320 nm pulsed Nd:YAG laser, the 1,310 nm CW diode laser, the 1,470 nm CW diode laser, and the 2,100 nm pulsed Ho:YAG laser, respectively. Our results have shown that the delivery mode, pulsed Nd:YAG versus CW, may be just as important as the wavelength. Therefore, the 1,310 nm CW laser may not be equivalent to the 1,320 nm pulsed laser. In addition, protected 810 nm fibers may be less likely to yield wall perforations than their non-protected counterparts. Copyright © 2012 Wiley Periodicals, Inc.

Role of diode lasers in oro-facial pain management.

PubMed

Javed, F; Kellesarian, S V; Romanos, G E

2017-01-01

With the increasing use of low level laser therapy (LLLT) in clinical dentistry, the aim of the present study was to assess the effectiveness of diode lasers in the management of orofacial pain. Indexed databases were searched without language and time restrictions up to and including July 2016 using different combinations of the following key words: oral, low level laser therapy, dental, pain, diode lasers, discomfort and analgesia. From the literature reviewed it is evident that LLLT is effective compared to traditional procedures in the management of oro-facial pain associated to soft tissue and hard tissue conditions such as premalignant lesions, gingival conditions and dental extractions. However, it remains to be determined which particular wavelength will produce the more favorable and predictable outcome in terms of pain reduction. It is highly recommended that further randomized control trials with well-defined control groups should be performed to determine the precise wavelengths of the diode lasers for the management of oro-facial pain. Within the limits of the present review, it is concluded that diode lasers therapy is more effective in the management of oro-facial pain compared to traditional procedures.

Clinical Evaluation of Nd:YAG and 685-nm Diode Laser Therapy for Desensitization of Teeth with Gingival Recession

PubMed Central

Canakci, Varol; Ozdemir, Atilla; Kaya, Yavuz

2009-01-01

Abstract Objectives: The aim of this study was to evaluate the effectiveness of two types of lasers, the Nd:YAG laser and the 685-nm diode laser, as dentin desensitizers as well as both the immediate and late therapeutic effects on teeth with gingival recession. Materials and Methods: The study was conducted on 56 teeth in 14 patients with Miller's class 1 and 2 gingival recession with clinically elicitable dentin hypersensitivity (DH). The patients were divided into two groups: a Nd:YAG-laser-treated group and a 685-nm diode laser-treated group. DH was assessed by means of an air stimulus, and a visual analog scale (VAS) was used to measure DH. The selected teeth in the two groups received laser therapy for three sessions. Teeth subjected to Nd:YAG-laser treatment were irradiated at 1 W and 10 Hz for 60 sec at 1064 nm, and those receiving 685-nm diode laser treatment were irradiated at 25 mW and 9 Hz for 100 sec. Results: Significant reductions in DH occurred at all time points measured during the three treatment sessions in both treatment groups. Comparing the means of the responses in the three treatment sessions for the two groups revealed that the Nd:YAG laser group had a higher degree of desensitization compared to the other group (p < 0.01). The immediate and late therapeutic effects of the Nd:YAG laser were more evident than those of the 685-nm diode laser. Conclusions: Both of these lasers can be used to reduce DH without adverse effects. Desensitization of teeth with gingival recession with the Nd:YAG laser was more effective than with the diode laser. The Nd:YAG laser appears to be a promising new tool for successfully reducing DH. PMID:19281413

Transurethral vaporesection of prostate: diode laser or thulium laser?

PubMed

Tan, Xinji; Zhang, Xiaobo; Li, Dongjie; Chen, Xiong; Dai, Yuanqing; Gu, Jie; Chen, Mingquan; Hu, Sheng; Bai, Yao; Ning, Yu

2018-05-01

This study compared the safety and effectiveness of the diode laser and thulium laser during prostate transurethral vaporesection for treating benign prostate hyperplasia (BPH). We retrospectively analyzed 205 patients with BPH who underwent a diode laser or thulium laser technique for prostate transurethral vaporesection from June 2016 to June 2017 and who were followed up for 3 months. Baseline characteristics of the patients, perioperative data, postoperative outcomes, and complications were compared. We also assessed the International Prostate Symptom Score (IPSS), quality of life (QoL), maximum flow rate (Q max ), average flow rate (AFR), and postvoid residual volume (PVR) at 1 and 3 months postoperatively to evaluate the functional improvement of each group. There were no significant differences between the diode laser and thulium laser groups related to age, prostate volume, operative time, postoperative hospital stays, hospitalization costs, or perioperative data. The catheterization time was 3.5 ± 0.8 days for the diode laser group and 4.7 ± 1.8 days for the thulium laser group (p < 0.05). Each group had dramatic improvements in IPSS, QoL, Q max , AFR, and PVR compared with the preoperative values (p < 0.05), although there were no significant differences between the two groups. Use of both diode laser and thulium laser contributes to safe, effective transurethral vaporesection in patients with symptomatic BPH. Diode laser, however, is better than thulium laser for prostate transurethral vaporesection because of its shorter catheterization time. The choice of surgical approach is more important than the choice of laser types during clinical decision making for transurethral laser prostatectomy.

Indocyanine green-augmented diode laser therapy of telangiectatic leg veins: a randomized controlled proof-of-concept trial.

PubMed

Klein, Annette; Bäumler, Wolfgang; Koller, Michael; Shafirstein, Gal; Kohl, Elisabeth A; Landthaler, Michael; Babilas, Philipp

2012-07-01

Telangiectatic leg veins, which affect about 40-50% of adults, represent a frequent cosmetic rather than a medical problem. Besides sclerotherapy, various laser devices are common treatment options. However, complete clearance rates can only be achieved in a small number of patients. In this proof-of-concept study, the safety and efficacy of indocyanine green (ICG)-augmented diode laser therapy (808 nm) was evaluated for the treatment of telangiectatic leg veins. ICG (2 mg/kg body weight) was intravenously administered in 15 female patients (skin type II to III) with telangiectatic leg veins (measuring between 0.25 and 3 mm in diameter). Immediately after ICG injection, diode laser pulses with different radiant exposures (50-110 J/cm(2)) were applied as one single treatment. Safety and efficacy were assessed 1 and 3 months after treatment by a blinded investigator and the patient. Treatments with the pulsed dye laser (PDL) and the diode laser without ICG served as reference therapies. The safety of ICG application and diode laser treatment was excellent in all patients with no persisting side effects. Vessel clearance was dose-dependent. Diode laser treatment at radiant exposures between 100 and 110 J/cm(2) resulted in good vessel clearance, which even improved to excellent after the application of double pulses. Diode laser therapy without ICG and PDL treatment induced poor to moderate clearance of telangiectatic leg veins. ICG-augmented diode laser therapy has proved to be a safe and effective treatment option for telangiectatic leg veins. Copyright © 2012 Wiley Periodicals, Inc.

Capturing thermal, mechanical, and acoustic effects of the diode (980 nm) laser in stapedotomy.

PubMed

Kamalski, Digna M A; de Boorder, Tjeerd; Bittermann, Arnold J N; Wegner, Inge; Vincent, Robert; Grolman, Wilko

2014-07-01

The diode laser, with a wavelength of 980 nm, has promising characteristics for being used for the fenestration during stapedotomy. It is known that at this wavelength absorption in pigmented tissues is high, and absorption in water is relatively low compared with medical lasers in the infrared, making it theoretically an applicable laser for stapes surgery in patients with otosclerosis. Another important advantage is that, with respect to other lasers, this device is relatively inexpensive. Despite the potential advantages, the available literature only shows limited reports of this laser being used in stapes surgery. The present article evaluates the thermal, mechanical, and acoustic properties of the diode laser during stapes surgery. For the mechanical effects, high-speed imaging with a frame rate up to 4000 f/s (=250 μs resolution) was performed in an inner ear model. For thermal effects, the high-speed Schlieren technique was used. Acoustics were recorded by a hydrophone, incorporated in the model. Pulse settings were 100 ms, 3 W, which are the same settings used during stapes surgery. The application of the diode laser resulted in limited mechanical and thermal effects. Impulse noise was low with an average of 52 (SD, 7.8) dB (A). Before carbonization of the tip of the delivery laser, fiber enhances ablation of the footplate. The 980-nm diode laser is a useful tool for laser-assisted stapedotomy in patients with otosclerosis. Mechanical, thermal, and acoustic effects are limited and well within the safety limits.

High brightness diode lasers controlled by volume Bragg gratings

NASA Astrophysics Data System (ADS)

Glebov, Leonid

2017-02-01

Volume Bragg gratings (VBGs) recorded in photo-thermo-refractive (PTR) glass are holographic optical elements that are effective spectral and angular filters withstanding high power laser radiation. Reflecting VBGs are narrow-band spectral filters while transmitting VBGs are narrow-band angular filters. The use of these optical elements in external resonators of semiconductor lasers enables extremely resonant feedback that provides dramatic spectral and angular narrowing of laser diodes radiation without significant power and efficiency penalty. Spectral narrowing of laser diodes by reflecting VBGs demonstrated in wide spectral region from near UV to 3 μm. Commercially available VBGs have spectral width ranged from few nanometers to few tens of picometers. Efficient spectral locking was demonstrated for edge emitters (single diodes, bars, modules, and stacks), vertical cavity surface emitting lasers (VCSELs), grating coupled surface emitting lasers (GCSELs), and interband cascade lasers (ICLs). The use of multiplexed VBGs provides multiwavelength emission from a single emitter. Spectrally locked semiconductor lasers demonstrated CW power from milliwatts to a kilowatt. Angular narrowing by transmitting VBGs enables single transverse mode emission from wide aperture diode lasers having resonators with great Fresnel numbers. This feature provides close to diffraction limit divergence along a slow axis of wide stripe edge emitters. Radiation exchange between lasers by means of spatially profiled or multiplexed VBGs enables coherent combining of diode lasers. Sequence of VBGs or multiplexed VBGs enable spectral combining of spectrally narrowed diode lasers or laser modules. Thus the use of VBGs for diode lasers beam control provides dramatic increase of brightness.

Little evidence for the use of diode lasers as an adjunct to non-surgical periodontal therapy.

PubMed

Dederich, Douglas N

2015-03-01

Medline, PubMed, the Cochrane Central Register of Controlled Trials (CENTRAL) and Embase databases. Randomised controlled trials (RCTs) using thermal diode lasers as an adjunct to non-surgical conventional periodontal initial therapy conducted in patients ≥18 years old written in English or Dutch were considered. Study assessment data extraction and quality assessment was carried out independently by two reviewers. The main outcome variables were probing pocket depth (PPD) and clinical attachment loss (CAL), but plaque scores (PS), bleeding scores (BS) and the Gingival Index (GI) were also considered. Meta-analysis was carried out using a random effects model. Nine studies involving 247 patients were included. Seven studies were of split mouth design and two were parallel group studies. The study designs showed considerable heterogeneity and follow up ranged from six weeks to six months. Meta-analysis found no significant effect on PPD, CAL and PS. There was however a significant effect for GI and BS favouring adjunctive use of the diode laser. The collective evidence regarding adjunctive use of the diode laser with SRP indicates that the combined treatment provides an effect comparable to that of SRP alone. With respect to BS the results showed a small but significant effect favouring the diode laser, however, the clinical relevance of this difference remains uncertainStandard . This systematic review questions the adjunctive use of diode laser with traditional mechanical modalities of periodontal therapy in patients with periodontitis. The strength of the recommendation for the adjunctive use of the diode laser is considered to be 'moderate' for changes in PPD and CAL.

Comparison of effects of diode laser and CO2 laser on human teeth and their usefulness in topical fluoridation.

PubMed

González-Rodríguez, Alberto; de Dios López-González, Juan; del Castillo, Juan de Dios Luna; Villalba-Moreno, Juan

2011-05-01

Various authors have reported more effective fluoridation from the use of lasers combined with topical fluoride than from conventional topical fluoridation. Besides the beneficial effect of lasers in reducing the acid solubility of an enamel surface, they can also increase the uptake of fluoride. The study objectives were to compare the action of CO(2) and GaAlAs diode lasers on dental enamel and their effects on pulp temperature and enamel fluoride uptake. Different groups of selected enamel surfaces were treated with amine fluoride and irradiated with CO(2) laser at an energy power of 1 or 2 W or with diode laser at 5 or 7 W for 15 s each and compared to enamel surfaces without treatment or topical fluoridated. Samples were examined by means of environmental scanning electron microscopy (ESEM). Surfaces of all enamel samples were then acid-etched, measuring the amount of fluoride deposited on the enamel by using a selective ion electrode. Other enamel surfaces selected under the same conditions were irradiated as described above, measuring the increase in pulp temperature with a thermocouple wire. Fluorination with CO(2) laser at 1 W and diode laser at 7 W produced a significantly greater fluoride uptake on enamel (89 ± 18 mg/l) and (77 ± 17 mg/l) versus topical fluoridation alone (58 ± 7 mg/l) and no treatment (20 ± 1 mg/l). Diode laser at 5 W produced a lesser alteration of the enamel surface compared to CO(2) laser at 1 W, but greater pulp safety was provided by CO(2) laser (ΔT° 1.60° ± 0.5) than by diode laser (ΔT° 3.16° ± 0.6). Diode laser at 7 W and CO(2) laser at 2 W both caused alterations on enamel surfaces, but great pulp safety was again obtained with CO(2) (ΔT° 4.44° ± 0.60) than with diode (ΔT° 5.25° ± 0.55). Our study demonstrates that CO(2) and diode laser irradiation of the enamel surface can both increase fluoride uptake; however, laser energy parameters must be carefully controlled in order to limit increases in pulpal temperature and alterations to the enamel surface.

Ablation of dentin by irradiation of violet diode laser

NASA Astrophysics Data System (ADS)

Hatayama, H.; Kato, J.; Akashi, G.; Hirai, Y.; Inoue, A.

2006-02-01

Several lasers have been used for clinical treatment in dentistry. Among them, diode lasers are attractive because of their compactness compared with other laser sources. Near-infrared diode lasers have been practically used for cutting soft tissues. Because they penetrate deep to soft tissues, they cause sufficiently thick coagulation layer. However, they aren't suitable for removal of carious dentin because absorption by components in dentin is low. Recently, a violet diode laser with a wavelength of 405nm has been developed. It will be effective for cavity preparation because dentin contains about 20% of collagen whose absorption coefficient at a violet wavelength is larger than that at a near-infrared wavelength. In this paper, we examined cutting performance of the violet diode laser for dentin. To our knowledge, there have been no previous reports on application of a violet laser to dentin ablation. Bovine teeth were irradiated by continuous wave violet diode laser with output powers in a range from 0.4W to 2.4W. The beam diameter on the sample was about 270μm and an irradiation time was one second. We obtained the crater ablated at more than an output power of 0.8W. The depth of crater ranged from 20μm at 0.8W to 90μm at 2.4W. Furthermore, the beam spot with an output power of 1.7W was scanned at a speed of 1mm/second corresponding to movement of a dentist's hand in clinical treatment. Grooves with the depth of more than 50μm were also obtained. From these findings, the violet diode laser has good potential for cavity preparation. Therefore, the violet diode laser may become an effective tool for cavity preparation.

Bactericidal Effects of Diode Laser Irradiation on Enterococcus faecalis Using Periapical Lesion Defect Model

PubMed Central

Nagayoshi, Masato; Nishihara, Tatsuji; Nakashima, Keisuke; Iwaki, Shigetsugu; Chen, Ker-Kong; Terashita, Masamichi; Kitamura, Chiaki

2011-01-01

Objective. Photodynamic therapy has been expanded for use in endodontic treatment. The aim of this study was to investigate the antimicrobial effects of diode laser irradiation on endodontic pathogens in periapical lesions using an in vitro apical lesion model. Study Design. Enterococcus faecalis in 0.5% semisolid agar with a photosensitizer was injected into apical lesion area of in vitro apical lesion model. The direct effects of irradiation with a diode laser as well as heat produced by irradiation on the viability of microorganisms in the lesions were analyzed. Results. The viability of E. faecalis was significantly reduced by the combination of a photosensitizer and laser irradiation. The temperature caused by irradiation rose, however, there were no cytotoxic effects of heat on the viability of E. faecalis. Conclusion. Our results suggest that utilization of a diode laser in combination with a photosensitizer may be useful for clinical treatment of periapical lesions. PMID:21991489

Narrowband diode laser pump module for pumping alkali vapors.

PubMed

Rotondaro, M D; Zhdanov, B V; Shaffer, M K; Knize, R J

2018-04-16

We describe a method of line narrowing and frequency-locking a diode laser stack to an alkali atomic line for use as a pump module for Diode Pumped Alkali Lasers. The pump module consists of a 600 W antireflection coated diode laser stack configured to lase using an external cavity. The line narrowing and frequency locking is accomplished by introducing a narrowband polarization filter based on magneto-optical Faraday effect into the external cavity, which selectively transmits only the frequencies that are in resonance with the 6 2 S 1/2 → 6 2 P 3/2 transition of Cs atoms. The resulting pump module has demonstrated that a diode laser stack, which lases with a line width of 3 THz without narrowbanding, can be narrowed to 10 GHz. The line narrowed pump module produced 518 Watts that is 80% of the power generated by the original broadband diode laser stack.

An in vitro antifungal efficacy of silver nanoparticles activated by diode laser to Candida albicans

NASA Astrophysics Data System (ADS)

Astuti, S. D.; Kharisma, D. H.; Kholimatussa'diah, S.; Zaidan, A. H.

2017-09-01

Microbial infectious diseases and increased resistance to antibiotics become urgent problems requiring immediate solutions. One promising alternative is the using of silver nanoparticles. The combination of the microbial inhibition characteristic of silver nanotechnology enhances the activity of antimicrobial effect. This study aims to determine effectiveness of antifungal silver nanoparticles with the activation of the diode laser on Candida albicans. The samples were culture of Candida albicans. Candida albicans cultures were incubated with silver nanoparticles (concentration 10-4 M) and treated with various exposure time of diode laser (15, 30, 45, 60, 75, 90)s. The suspension was planted on Sabouraud Dextrone Agar sterile media and incubated for 24 hours at temperature of 37oC. The number of colony-forming units per milliliter (CFU/ml) was determined after incubation. The results were log-transformed and analyzed by analysis of variance (ANOVA). In this analysis, P value ≤0.05 was considered to indicate a statistically significant difference. The result of this study showed the quantum yield of silver nanoparticles with diode laser 450 nm was 63,61%. Irradiating with diode laser 450 nm for 75 s resulted in the highest decreasing percentage of Candida albicans viability 65,03%. Irradiating with diode laser 450 nm 75 s with silver nanoparticles resulted in the higest decreasing percentage of Candida albicans viability 84,63%. Therefore, silver nanoparticles activated with diode laser irradiation of 450 nm resulted antifungal effect to Candida albicans viability.

Efficacy of Diode Laser for the Management of Potentially Malignant Disorders.

PubMed

Reddy Kundoor, Vinay Kumar; Patimeedi, Ashwini; Roohi, Shameena; Maloth, Kotya Naik; Kesidi, Sunitha; Masabattula, Geetha Kumari

2015-01-01

Laser dentistry is a one of the upcoming advanced treatment modality for oral mucosal lesions. Diode laser is a soft tissue laser that has found much acceptance in all branches of dentistry. Available compact size and feasibility has render diode laser an enhanced tool for today's clinical practice. The aim of this study is to determine the efficacy and safety of diode laser for the management of white lesions such as oral leukoplakia (OL) and oral lichen planus (OLP). The study was conducted by using diode laser 980 nm on 10 patients with white lesions (5 OL and 5 OLP) aged between 35 to 65 years. Of the 10 patients (5 OL and 5 OLP), 3 patients (30%) complained of moderate pain and 7 patients (70%) complained of mild pain, for first 3 days after laser irradiation, and pain disappeared at end of first week. There was no recurrence of the lesion during the 6-month follow up. Diode lasers provide acceptable clinical improvement of potentially malignant lesions with minimal side effects. It can be considered one of the best alternative treatment modality for oral mucosal lesions.

The effect of bleaching gel and (940 nm and 980 nm) diode lasers photoactivation on intrapulpal temperature and teeth whitening efficiency.

PubMed

Al-Karadaghi, Tamara S; Al-Saedi, Asmaa A; Al-Maliky, Mohammed A; Mahmood, Ali S

2016-12-01

This in vitro study aimed to investigate the whitening efficacy of 940 nm and 980 nm diode laser photoactivation in tooth bleaching by analysing pulp chamber temperature, as well as the change in tooth colour. Root canals of thirty extracted human lower premolars were prepared. Laserwhite* 20 bleaching agent containing 38% of hydrogen peroxide was photoactivated with 7 W output power of 940 nm and 980 nm diode lasers for 120 s. Bleaching gel reduced 27-29% of the temperature from reaching the pulp chamber. For shade assessment, only the groups photoactivated using diode lasers showed statistically significant differences from control group P < 0.001. Within the studied parameters, both 940 nm and 980 nm diode lasers produced a safe pulp temperature increase. Diode laser photoactivation of bleaching gel resulted in more efficient teeth whitening. Photoactivation with 940 nm diode laser yielded the highest change in colour with only minor increase in pulp chamber temperature. © 2016 Australian Society of Endodontology Inc.

Promoting Robust Design of Diode Lasers for Space: A National Initiative

NASA Technical Reports Server (NTRS)

Tratt, David M.; Amzajerdian, Farzin; Kashem, Nasir B.; Shapiro, Andrew A.; Mense, Allan T.

2007-01-01

The Diode-laser Array Working Group (DAWG) is a national-level consumer/provider forum for discussion of engineering and manufacturing issues which influence the reliability and survivability of high-power broad-area laser diode devices in space, with an emphasis on laser diode arrays (LDAs) for optical pumping of solid-state laser media. The goals of the group are to formulate and validate standardized test and qualification protocols, operational control recommendations, and consensus manufacturing and certification standards. The group is using reliability and lifetime data collected by laser diode manufacturers and the user community to develop a set of standardized guidelines for specifying and qualifying laser diodes for long-duration operation in space, the ultimate goal being to promote an informed U.S. Government investment and procurement strategy for assuring the availability and durability of space-qualified LDAs. The group is also working to establish effective implementation of statistical design techniques at the supplier design, development, and manufacturing levels to help reduce product performance variability and improve product reliability for diodes employed in space applications

INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Surface effects in laser diodes

NASA Astrophysics Data System (ADS)

Beister, G.; Maege, J.; Richter, G.

1988-11-01

Changes in the current-voltage characteristics below the threshold current were observed in gain-guided stripe laser diodes after preliminary lasing. This effect was not fully understood. Similar changes in the laser characteristics appeared as a result of etching in a gaseous medium. The observed changes were attributed tentatively to surface currents.

Diode Lasers used in Plastic Welding and Selective Laser Soldering - Applications and Products

NASA Astrophysics Data System (ADS)

Reinl, S.

Aside from conventional welding methods, laser welding of plastics has established itself as a proven bonding method. The component-conserving and clean process offers numerous advantages and enables welding of sensitive assemblies in automotive, electronic, medical, human care, food packaging and consumer electronics markets. Diode lasers are established since years within plastic welding applications. Also, soft soldering using laser radiation is becoming more and more significant in the field of direct diode laser applications. Fast power controllability combined with a contactless temperature measurement to minimize thermal damage make the diode laser an ideal tool for this application. These advantages come in to full effect when soldering of increasingly small parts in temperature sensitive environments is necessary.

Spin polarization of {sup 87}Rb atoms with ultranarrow linewidth diode laser: Numerical simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Z. G.; Interdisciplinary Center of Quantum Information, National University of Defense Technology, Changsha, 410073; College of Science, National University of Defense Technology, Changsha, 410073

2016-08-15

In order to polarize {sup 87}Rb vapor effectively with ultranarrow linewidth diode laser, we studied the polarization as a function of some parameters including buffer gas pressure and laser power. Moreover, we also discussed the methods which split or modulate the diode laser frequency so as to pump the two ground hyperfine levels efficiently. We obtained some useful results through numerical simulation. If the buffer gas pressure is so high that the hyperfine structure is unresolved, the polarization is insensitive to laser frequency at peak absorption point so frequency splitting and frequency modulation methods do not show improvement. At lowmore » pressure and laser power large enough, where the hyperfine structure is clearly resolved, frequency splitting and frequency modulation methods can increase polarization effectively. For laser diodes, frequency modulation is easily realized with current modulation, so this method is attractive since it does not add any other components in the pumping laser system.« less

In Vitro Study of Dentin Hypersensitivity Treated by 980-nm Diode Laser.

PubMed

Liu, Ying; Gao, Jie; Gao, Yan; Xu, Shuaimei; Zhan, Xueling; Wu, Buling

2013-01-01

To investigate the ultrastructural changes of dentin irradiated with 980-nm diode laser under different parameters and to observe the morphological alterations of odontoblasts and pulp tissue to determine the safety parameters of 980-nm diode laser in the treatment of dentin hypersensitivity (DH). Twenty extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into four areas and was irradiated by 980-nm diode laser under different parameters: Group A: control group, 0 J/cm(2); Group B: 2 W/CW (continuous mode), 166 J/cm(2); Group C: 3W/CW, 250 J/cm(2); and Group D: 4W/CW, 333 J/cm(2). Ten additional extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into two areas and was irradiated by 980-nm diode laser: Group E: control group, 0 J/cm(2); and Group F: 2.0 W/CW, 166 J/cm(2). The morphological alterations of the dentin surfaces and odontoblasts were examined with scanning electron microscopy (SEM), and the morphological alterations of the dental pulp tissue irradiated by laser were observed with an upright microscope. The study demonstrated that dentinal tubules can be entirely blocked after irradiation by 980-nm diode laser, regardless of the parameter setting. Diode laser with settings of 2.0 W and 980-nm sealed exposed dentin tubules effectively, and no significant morphological alterations of the pulp and odontoblasts were observed after irradiation. Irradiation with 980-nm diode laser could be effective for routine clinical treatment of DH, and 2.0W/CW (166 J/cm(2)) was a suitable energy parameter due to its rapid sealing of the exposed dentin tubules and its safety to the odontoblasts and pulp tissue.

In Vitro Study of Dentin Hypersensitivity Treated by 980-nm Diode Laser

PubMed Central

Liu, Ying; Gao, Jie; Gao, Yan; XU, Shuaimei; Zhan, Xueling; Wu, Buling

2013-01-01

Introduction: To investigate the ultrastructural changes of dentin irradiated with 980-nm diode laser under different parameters and to observe the morphological alterations of odontoblasts and pulp tissue to determine the safety parameters of 980-nm diode laser in the treatment of dentin hypersensitivity (DH). Methods: Twenty extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into four areas and was irradiated by 980-nm diode laser under different parameters: Group A: control group, 0 J/cm2; Group B: 2 W/CW (continuous mode), 166 J/cm2; Group C: 3W/CW, 250 J/cm2; and Group D: 4W/CW, 333 J/cm2. Ten additional extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into two areas and was irradiated by 980-nm diode laser: Group E: control group, 0 J/cm2; and Group F: 2.0 W/CW, 166 J/cm2. The morphological alterations of the dentin surfaces and odontoblasts were examined with scanning electron microscopy (SEM), and the morphological alterations of the dental pulp tissue irradiated by laser were observed with an upright microscope. Results: The study demonstrated that dentinal tubules can be entirely blocked after irradiation by 980-nm diode laser, regardless of the parameter setting. Diode laser with settings of 2.0 W and 980-nm sealed exposed dentin tubules effectively, and no significant morphological alterations of the pulp and odontoblasts were observed after irradiation. Conclusions: Irradiation with 980-nm diode laser could be effective for routine clinical treatment of DH, and 2.0W/CW (166 J/cm2) was a suitable energy parameter due to its rapid sealing of the exposed dentin tubules and its safety to the odontoblasts and pulp tissue. PMID:25606318

Comparison of the Antibacterial Effect of 810 nm Diode Laser and Photodynamic Therapy in Reducing the Microbial Flora of Root Canal in Endodontic Retreatment in Patients With Periradicular Lesions.

PubMed

Asnaashari, Mohammad; Godiny, Mostafa; Azari-Marhabi, Saranaz; Tabatabaei, Fahimeh Sadat; Barati, Maryam

2016-01-01

The aim of this study was to compare the antibacterial efficacy of diode laser 810nm and photodynamic therapy (PDT) in reducing bacterial microflora in endodontic retreatment of teeth with periradicular lesion. In this in vivo clinical trial, 20 patients who needed endodontic retreatment were selected. After conventional chemo mechanical preparation of root canals, microbiological samples were taken with sterile paper point (PP), held in thioglycollate broth, and then were transferred to the microbiological lab. In the first group, PDT with methylene blue (MB) and diode laser (810 nm, 0.2 W, 40 seconds) was performed and in the second group diode laser (810 nm, 1.2 W, 30 seconds) was irradiated. Then second samples were taken from all canals. CFU/ml amounts showed statistically significant reduction in both groups (P < 0.001). CFU/ml amounts were compared between the two groups and there was no statistical difference. PDT and diode laser 810 nm irradiation are effective methods for root canal disinfection. PDT is a suitable alternative for diode laser 810 nm irradiation, because of lower thermal risk on root dentin.

In Vitro Comparison of the Effects of Diode Laser and CO2 Laser on Topical Fluoride Uptake in Primary Teeth

PubMed Central

Bahrololoomi, Zahra; Sorouri, Milad

2015-01-01

Objectives: Fluoride therapy is important for control and prevention of dental caries. Laser irradiation can increase fluoride uptake especially when combined with topical fluoride application. The objective of this study was to compare the effects of CO2 and diode lasers on enamel fluoride uptake in primary teeth. Materials and Methods: Forty human primary molars were randomly assigned to four groups (n=10). The roots were removed and the crowns were sectioned mesiodistally into buccal and lingual halves as the experimental and control groups. All samples were treated with 5% sodium fluoride (NaF) varnish. The experimental samples in the four groups were irradiated with 5 or 7W diode or 1 or 2W CO2 laser for 15 seconds and were compared with the controls in terms of fluoride uptake, which was determined using an ion selective electrode after acid dissolution of the specimens. Data were analyzed by SPSS version 16 using ANOVA treating the control measurements as covariates. Results: The estimated amount of fluoride uptake was 59.5± 16.31 ppm, 66.5± 14.9 ppm, 78.6± 12.43 ppm and 90.4± 11.51 ppm for 5W and 7 W diode and 1W and 2 W CO2 lasers, respectively, which were significantly greater than the values in the conventional topical fluoridation group (P<0.005). There were no significant differences between 7W diode laser and 1W CO2 laser, 5W and 7W diode laser, or 1W and 2W CO2 laser in this regard. Conclusion: The results showed that enamel surface irradiation by CO2 and diode lasers increases the fluoride uptake. PMID:27123018

In Vitro Comparison of the Effects of Diode Laser and CO2 Laser on Topical Fluoride Uptake in Primary Teeth.

PubMed

Bahrololoomi, Zahra; Fotuhi Ardakani, Faezeh; Sorouri, Milad

2015-08-01

Fluoride therapy is important for control and prevention of dental caries. Laser irradiation can increase fluoride uptake especially when combined with topical fluoride application. The objective of this study was to compare the effects of CO2 and diode lasers on enamel fluoride uptake in primary teeth. Forty human primary molars were randomly assigned to four groups (n=10). The roots were removed and the crowns were sectioned mesiodistally into buccal and lingual halves as the experimental and control groups. All samples were treated with 5% sodium fluoride (NaF) varnish. The experimental samples in the four groups were irradiated with 5 or 7W diode or 1 or 2W CO2 laser for 15 seconds and were compared with the controls in terms of fluoride uptake, which was determined using an ion selective electrode after acid dissolution of the specimens. Data were analyzed by SPSS version 16 using ANOVA treating the control measurements as covariates. The estimated amount of fluoride uptake was 59.5± 16.31 ppm, 66.5± 14.9 ppm, 78.6± 12.43 ppm and 90.4± 11.51 ppm for 5W and 7 W diode and 1W and 2 W CO2 lasers, respectively, which were significantly greater than the values in the conventional topical fluoridation group (P<0.005). There were no significant differences between 7W diode laser and 1W CO2 laser, 5W and 7W diode laser, or 1W and 2W CO2 laser in this regard. The results showed that enamel surface irradiation by CO2 and diode lasers increases the fluoride uptake.

Experimental diode laser-assisted microvascular anastomosis.

PubMed

Reali, U M; Gelli, R; Giannotti, V; Gori, F; Pratesi, R; Pini, R

1993-05-01

An experimental study to evaluate a diode-laser approach to microvascular end-to-end anastomoses is reported. Studies were carried out on the femoral arteries and veins of Wistar rats, and effective welding of vessel tissue was obtained at low laser power, by enhancing laser absorption with indocyanine green (Cardio-green) solution. The histologic and surgical effects of this laser technique were examined and compared with those of conventional microvascular sutured anastomoses.

Comparative evaluation of photoablative efficacy of erbium: yttrium-aluminium-garnet and diode laser for the treatment of gingival hyperpigmentation. A randomized split-mouth clinical trial.

PubMed

Giannelli, Marco; Formigli, Lucia; Bani, Daniele

2014-04-01

The use of lasers in periodontology is a matter of debate, mainly because of the lack of consensual therapeutic protocols. In this randomized, split-mouth trial, the clinical efficacy of two different photoablative dental lasers, erbium:yttrium-aluminum-garnet (Er:YAG) and diode, for the treatment of gingival hyperpigmentation is compared. Twenty-one patients requiring treatment for mild-to-severe gingival hyperpigmentation were enrolled. Maxillary or mandibular left or right quadrants were randomly subjected to photoablative deepithelialization with either Er:YAG or diode laser. Masked clinical assessments of each laser quadrant were made at admission and days 7, 30, and 180 postoperatively by an independent observer. Histologic examination was performed before and soon after treatment and 6 months after irradiation. Patients also compiled a subjective evaluation questionnaire. Both diode and Er:YAG lasers gave excellent results in gingival hyperpigmentation. However, Er:YAG laser induced deeper gingival tissue injury than diode laser, as judged by bleeding at surgery, delayed healing, and histopathologic analysis. The use of diode laser showed additional advantages compared to Er:YAG in terms of less postoperative discomfort and pain. This study highlights the efficacy of diode laser for photoablative deepithelialization of hyperpigmented gingiva. It is suggested that this laser can represent an effective and safe therapeutic option for gingival photoablation.

Comparative evaluation of diode laser ablation and surgical stripping technique for gingival depigmentation: A clinical and immunohistochemical study.

PubMed

Bakutra, Gaurav; Shankarapillai, Rajesh; Mathur, Lalit; Manohar, Balaji

2017-01-01

There are various treatment modalities to remove the black patches of melanin pigmentation. The aim of the study is to clinically compare the diode laser ablation and surgical stripping technique for gingival depigmentation and to evaluate their effect on the histological changes in melanocyte activity. A total of 40 sites of 20 patients with bilateral melanin hyperpigmentation were treated with the surgical stripping and diode laser ablation technique. Change in Hedin index score, change in area of pigmentation using image analyzing software, pain perception, patient preference of treatment were recorded. All 40 sites were selected for immunohistochemical analysis using HMB-45 immunohistochemical marker. At 12 months post-operative visit, in all sites, repigmentation was observed with different grades of Hedin index. Paired t -test, analysis of variance, and Chi-square tests were used for statistical analysis. Repigmentation in surgical stripping is significantly lesser compared to laser ablation. Lesser numbers of melanocytes were found on immunohistological examination at 12 months postoperatively. Comparison for patient preference and pain indices give statistically significant values for diode laser techniques. Gingival hyperpigmentation is effectively managed by diode laser ablation technique and surgical stripping method. In this study, surgical stripping technique found to be better compared to diode laser ablation.

Comparative evaluation of diode laser ablation and surgical stripping technique for gingival depigmentation: A clinical and immunohistochemical study

PubMed Central

Bakutra, Gaurav; Shankarapillai, Rajesh; Mathur, Lalit; Manohar, Balaji

2017-01-01

Introduction: There are various treatment modalities to remove the black patches of melanin pigmentation. The aim of the study is to clinically compare the diode laser ablation and surgical stripping technique for gingival depigmentation and to evaluate their effect on the histological changes in melanocyte activity. Materials and Methods: A total of 40 sites of 20 patients with bilateral melanin hyperpigmentation were treated with the surgical stripping and diode laser ablation technique. Change in Hedin index score, change in area of pigmentation using image analyzing software, pain perception, patient preference of treatment were recorded. All 40 sites were selected for immunohistochemical analysis using HMB-45 immunohistochemical marker. Results: At 12 months post-operative visit, in all sites, repigmentation was observed with different grades of Hedin index. Paired t-test, analysis of variance, and Chi-square tests were used for statistical analysis. Repigmentation in surgical stripping is significantly lesser compared to laser ablation. Lesser numbers of melanocytes were found on immunohistological examination at 12 months postoperatively. Comparison for patient preference and pain indices give statistically significant values for diode laser techniques. Conclusion: Gingival hyperpigmentation is effectively managed by diode laser ablation technique and surgical stripping method. In this study, surgical stripping technique found to be better compared to diode laser ablation. PMID:28539864

The application of diode laser in the treatment of oral soft tissues lesions. A literature review.

PubMed

Ortega-Concepción, Daniel; Cano-Durán, Jorge A; Peña-Cardelles, Juan-Francisco; Paredes-Rodríguez, Víctor-Manuel; González-Serrano, José; López-Quiles, Juan

2017-07-01

Since its appearance in the dental area, the laser has become a treatment of choice in the removal of lesions in the oral soft tissues, due to the numerous advantages they offer, being one of the most used currently the diode laser. The aim of this review was to determine the efficacy and predictability of diode laser as a treatment of soft tissue injuries compared to other surgical methods. A literature review of articles published in PubMed/MEDLINE, Scopus and the Cochrane Library databases between 2007 and 2017 was performed. "Diode laser", "soft tissue", "oral cavity" and "oral surgery" were employed for the search strategy. Only articles published English or Spanish were selected. The diode laser is a minimally invasive technology that offers great advantages, superior to those of the conventional scalpel, such as reduction of bleeding, inflammation and the lower probability of scars. Its effectiveness is comparable to that of other types of lasers, in addition to being an option of lower cost and greater ease of use. Its application in the soft tissues has been evaluated, being a safe and effective method for the excision of lesions like fibromas, epulis fissuratum and the accomplishment of frenectomies. The diode laser can be used with very good results for the removal of lesions in soft tissues, being used in small exophytic lesions due to their easy application, adequate coagulation, no need to suture and the slightest inflammation and pain. Key words: Diode laser, soft tissues, oral cavity, oral surgery.

Comparing the effect of diode laser against acyclovir cream for the treatment of herpes labialis.

PubMed

Honarmand, Marieh; Farhadmollashahi, Leila; Vosoughirahbar, Ehsan

2017-06-01

Recently alternative therapies such as the use of diode laser therapy have been introduced for recurrent herpes labial infection. The aim of this study was to evaluate the effectiveness of diode laser for treatment of recurrent herpes labialis. This was single-blind randomized clinical trial to evaluate the efficacy of diode laser for the treatment of recurrent herpes labial. In total, 60 patients whit recurrent herpes simplex labialis were selected and randomly divided in to three groups. 20 patients received treatment whit diode laser (at a wavelength of 870 nm, energy density 4.5 j/cm2), 20 patients were treated with acyclovir cream 5%, 20 patients received treatment with laser-off (placebo). The end point was lesions crusting. Data analyzed by Tukey HSD Test and One-way ANOVA (at a significance level of 0.05) in SPSS-20 software. The mean length of recovery time (day) in the laser, off laser, and acyclovir groups was 2.20±0.41, 4.30±1.03, and 3.4±1.142, respectively. There is a significant difference between three groups in this regard ( P <0.0001). The mean duration of pain (day) was 1.35±0.74, 2.65±1.27, and 2.30±0.92 for laser, off laser, and acyclovir groups, respectively ( P <0.0001). Treatment with diode laser reduced the length of recovery time and pain severity faster than treatment with acyclovir cream. Key words: Recurrent herpes labial, Acyclovir, Low level laser therapy.

Spatial Combining of Laser-Diode Beams for Pumping an NPRO

NASA Technical Reports Server (NTRS)

Gelsinger, Paul; Liu, Duncan; Mulder, Jerry; Aguayo, Francisco

2008-01-01

A free-space optical beam combiner now undergoing development makes it possible to use the outputs of multiple multimode laser diodes to pump a neodymium-doped yttrium aluminum garnet (Nd:YAG) non-planar ring oscillator (NPRO) laser while ensuring that the laser operates at only a single desired frequency. Heretofore, a Nd:YAG NPRO like the present one has been pumped by a single multimode laser-diode beam delivered via an optical fiber. It would be desirable to use multiple pump laser diodes to increase reliability beyond that obtainable from a single pump laser diode. However, as explained in this article, simplistically coupling multiple multimode laser-diode beams through a fiber-optic combiner would entail a significant reduction in coupling efficiency, and lasing would occur at one or more other frequencies in addition to the single desired frequency. To minimize coupling loss, one must ensure that the NA (approximately equal to 0.3) of the combined laser-diode beams is less than the NA of the fiber. The A(Omega) of the laser-diode beam in the slow-axis plane is 1/1.3 as large as that of the fiber. This A(Omega) is small enough to enable efficient coupling of light into the optical fiber, but too large for combining of beams in the slow-axis plane. Therefore, a pair of cylindrical lenses is used to cancel the slow-axis plane magnification introduced by the on-cylindrical lenses used to effect magnification in the fast-axis plane.

New alternatives for laser vaporization of the prostate: experimental evaluation of a 980-, 1,318- and 1,470-nm diode laser device.

PubMed

Wezel, Felix; Wendt-Nordahl, Gunnar; Huck, Nina; Bach, Thorsten; Weiss, Christel; Michel, Maurice Stephan; Häcker, Axel

2010-04-01

Several diode laser systems were introduced in recent years for the minimal-invasive surgical therapy of benign prostate enlargement. We investigated the ablation capacities, hemostatic properties and extend of tissue necrosis of different diode lasers at wavelengths of 980, 1,318 and 1,470 nm and compared the results to the 120 W GreenLight HPS laser. The laser devices were evaluated in an ex vivo model using isolated porcine kidneys. The weight difference of the porcine kidneys after 10 min of laser vaporization defined the amount of ablated tissue. Blood loss was measured in blood-perfused kidneys following laser vaporization. Histological examination was performed to assess the tissue effects. The side-firing 980 and 1,470 nm diode lasers displayed similar ablative capacities compared to the GreenLight HPS laser (n.s.). The 1,318-nm laser, equipped with a bare-ended fiber, reached a higher ablation rate compared to the other laser devices (each P < 0.05). A calculated 'output power efficiency per watt' revealed that the 1,318-nm laser with a bare-ended fiber reached the highest rate compared to the side-firing devices (each P < 0.0001). All three diode lasers showed superior hemostatic properties compared to the GreenLight HPS laser (each P < 0.01). The extend of morphological tissue necrosis was 4.62 mm (1,318 nm), 1.30 mm (1,470 nm), 4.18 mm (980 nm) and 0.84 mm (GreenLight HPS laser), respectively. The diode lasers offered similar ablative capacities and improved hemostatic properties compared to the 120 W GreenLight HPS laser in this experimental ex vivo setting. The higher tissue penetration of the diode lasers compared to the GreenLight HPS laser may explain improved hemostasis.

Temperature evaluation of dental implant surface irradiated with high-power diode laser.

PubMed

Rios, F G; Viana, E R; Ribeiro, G M; González, J C; Abelenda, A; Peruzzo, D C

2016-09-01

The prevalence of peri-implantitis and the absence of a standard approach for decontamination of the dental implant surface have led to searches for effective therapies. Since the source of diode lasers is portable, has reduced cost, and does not cause damage to the titanium surface of the implant, high-power diode lasers have been used for this purpose. The effect of laser irradiation on the implants is the elevation of the temperature surface. If this elevation exceeds 47 °C, the bone tissue is irreversibly damaged, so for a safety therapy, the laser parameters should be controlled. In this study, a diode laser of GaAsAl was used to irradiate titanium dental implants, for powers 1.32 to 2.64 W (real) or 2.00 to 4.00 W (nominal), in continuous/pulsed mode DC/AC, with exposure time of 5/10 s, with/without air flow for cooling. The elevation of the temperature was monitored in real time in two positions: cervical and apical. The best results for decontamination using a 968-nm diode laser were obtained for a power of 1.65 and 1.98 W (real) for 10 s, in DC or AC mode, with an air flow of 2.5 l/min. In our perspective in this article, we determine a suggested approach for decontamination of the dental implant surface using a 968-nm diode laser.

Effects of 980 diode laser treatment combined with scaling and root planing on periodontal pockets in chronic periodontitis patients

NASA Astrophysics Data System (ADS)

Fallah, Alireza

2010-02-01

Objective: This study compared the effect of 980 Diode laser + scaling and root planing (SRP) versus SRP alone in the treatment of chronic periodontitis. Method: 21 healthy patients with moderate periodontitis with a probing depth of at least 5mm were included in the study. A total of 42 sites were treated during 6weeks with a combination of 980 Diode laser and SRP (21 sites) or SRP alone (21 sites). The gingival index (GI), probing pocket depth (PPD) and bleeding on probing (BOP) were examined at the baseline and after 6 weeks after the start of treatment. Results: Both groups showed statistically significant improvements in GI, BOP and PPD after treatment. The results also showed significant improvement from laser+ SRP group to SRP alone group. Conclusion: The present data suggest that treatment of chronic periodontitis with either 980 Diode laser + SRP or SRP alone results in statistically significant improvements in the clinical parameters. The combination of 980 Diode laser irradiation in the gingival sulcus and SRP, was significantly better as compared to SRP alone.

High-power diode laser versus electrocautery surgery on human papillomavirus lesion treatment.

PubMed

Baeder, Fernando Martins; Santos, Maria Teresa Botti R; Pelino, Jose Eduardo Pelizon; Duarte, Danilo Antonio; Genovese, Walter Joao

2012-05-01

The use of high-power lasers has facilitated and improved human papillomavirus (HPV) treatment protocols and has also become very popular in recent years. This application has been more frequently used in hospitals, especially in gynecology. The present study aimed to evaluate the effects of high-power diode laser to remove oral lesions caused by HPV and the consequent effects on virus load following the wound tissue healing process compared with one of the most conventional surgical techniques involving electrocautery. Surgeries were performed on 5 patients who had 2 distinct lesions caused by HPV. All patients were submitted to both electrocautery and high-power diode laser. Following a 20-day period, when the area was healed, sample material was collected through curettage for virus load quantitative analysis.Observation verified the presence of virus in all the samples; however, surgeries performed with the laser also revealed a significant reduction in virus load per cell compared with those performed with electrocautery. The ease when handling the diode laser, because of the flexibility of its fibers and precision of its energy delivery system, provides high-accuracy surgery, which facilitates the treatment of large and/or multifocal lesions. The use of high-power diode laser is more effective in treatment protocols of lesions caused by HPV.

Laser interferometric studies of thermal effects of diode-pumped solid state lasing medium

NASA Astrophysics Data System (ADS)

Peng, Xiaoyuan; Asundi, Anand K.; Xu, Lei; Chen, Yihong; Xiong, Zhengjun; Lim, Gnian Cher

2000-04-01

Thermal effects dramatically influence the laser performance of diode-pumped solid state lasers (DPSSL). There are three factors accounting for thermal effects in diode-pumped laser medium: the change of the refractive index due to temperature gradient, the change of the refractive index due to thermal stress, and the change of the physical length due to thermal expansion (end effect), in which the first two effects can be called as thermal parts. A laser interferometer is proposed to measure both the bulk and physical messages of solid-state lasing medium. There are two advantages of the laser interferometry to determine the thermal lensing effect. One is that it allows separating the average thermal lens into thermal parts and end effect. Another is that the laser interferometry provides a non- invasive, full field, high-resolution means of diagnosing such effects by measuring the optical path difference induced by thermal loading in a lasing crystal reliable without disturbing the normal working conditions of the DPSS laser. Relevant measurement results are presented in this paper.

Method and system for communicating with a laser power driver

DOEpatents

Telford, Steven

2017-07-18

A system for controlling a plurality of laser diodes includes an optical transmitter coupled to the laser diode driver for each laser diode. An optical signal including bi-phase encoded data is provided to each laser diode driver. The optical signal includes current level and pulse duration information at which each of the diodes is to be driven. Upon receiving a trigger signal, the laser diode drivers operate the laser diodes using the current level and pulse duration information to output a laser beam.

Effect of diode low-level lasers on fibroblasts derived from human periodontal tissue: a systematic review of in vitro studies.

PubMed

Ren, Chong; McGrath, Colman; Jin, Lijian; Zhang, Chengfei; Yang, Yanqi

2016-09-01

This study aimed to systematically assess the parameter-specific effects of the diode low-level laser on human gingival fibroblasts (HGFs) and human periodontal ligament fibroblasts (HPDLFs). An extensive search was performed in major electronic databases including PubMed (1997), EMBASE (1947) and Web of Science (1956) and supplemented by hand search of reference lists and relevant laser journals for cell culture studies investigating the effect of diode low-level lasers on HGFs and HPDLFs published from January 1995 to December 2015. A total of 21 studies were included after screening 324 independent records, amongst which eight targeted HPDLFs and 13 focussed on HGFs. The diode low-level laser showed positive effects on promoting fibroblast proliferation and osteogenic differentiation and modulating cellular inflammation via changes in gene expression and the release of growth factors, bone-remodelling markers or inflammatory mediators in a parameter-dependent manner. Repeated irradiations with wavelengths in the red and near-infrared range and at an energy density below 16 J/cm(2) elicited favourable responses. However, considerable variations and weaknesses in the study designs and laser protocols limited the interstudy comparison and clinical transition. Current evidence showed that diode low-level lasers with adequate parameters stimulated the proliferation and modulated the inflammation of fibroblasts derived from human periodontal tissue. However, further in vitro studies with better designs and more appropriate study models and laser parameters are anticipated to provide sound evidence for clinical studies and practice.

A comparative evaluation: Oral leukoplakia surgical management using diode laser, CO2 laser, and cryosurgery.

PubMed

Natekar, Madhukar; Raghuveer, Hosahallli-Puttaiah; Rayapati, Dilip-Kumar; Shobha, Eshwara-Singh; Prashanth, Nagesh-Tavane; Rangan, Vinod; Panicker, Archana G

2017-06-01

The comparatively evaluate the three surgical treatment modalities namely cryosurgery, diode and CO2 laser surgery in terms of healing outcomes on the day of surgery, first and second week post operatively and recurrence at the end of 18 months was assessed. Thirty selected patients were divided randomly into three groups. Each group comprising of ten patients were subjected to one of the three modalities of treatment namely cryosurgery, diode laser or CO2 laser surgery for ablation of OL. Obtained data was analyzed using mainly using Chi-square and Anova tests. Study showed statistical significant differences (p > 0.05) for evaluation parameters like pain, edema and scar. The parameters like infection, recurrence, bleeding showed no statistical significance. Pain was significantly higher in CO2 laser surgery group as compared with diode laser group. There was no recurrence observed at the end of the 6 months follow up period in all the three study groups. Observations from the study highlights that all three surgical modalities used in this study were effective for treatment of OL, and the overall summation of the results of the study showed that laser therapy (CO2 and Diode) seems to offer better clinically significant results than cryotherapy. Key words: Oral premalignant lesion, leukoplakia, cryosurgery, CO2 laser surgery, diode laser surgery.

Qualification and Selection of Flight Diode Lasers for Space Applications

NASA Technical Reports Server (NTRS)

Liebe, Carl C.; Dillon, Robert P.; Gontijo, Ivair; Forouhar, Siamak; Shapiro, Andrew A.; Cooper, Mark S.; Meras, Patrick L.

2010-01-01

The reliability and lifetime of laser diodes is critical to space missions. The Nuclear Spectroscopic Telescope Array (NuSTAR) mission includes a metrology system that is based upon laser diodes. An operational test facility has been developed to qualify and select, by mission standards, laser diodes that will survive the intended space environment and mission lifetime. The facility is situated in an electrostatic discharge (ESD) certified clean-room and consist of an enclosed temperature-controlled stage that can accommodate up to 20 laser diodes. The facility is designed to characterize a single laser diode, in addition to conducting laser lifetime testing on up to 20 laser diodes simultaneously. A standard laser current driver is used to drive a single laser diode. Laser diode current, voltage, power, and wavelength are measured for each laser diode, and a method of selecting the most adequate laser diodes for space deployment is implemented. The method consists of creating histograms of laser threshold currents, powers at a designated current, and wavelengths at designated power. From these histograms, the laser diodes that illustrate a performance that is outside the normal are rejected and the remaining lasers are considered spaceborne candidates. To perform laser lifetime testing, the facility is equipped with 20 custom laser drivers that were designed and built by California Institute of Technology specifically to drive NuSTAR metrology lasers. The laser drivers can be operated in constant-current mode or alternating-current mode. Situated inside the enclosure, in front of the laser diodes, are 20 power-meter heads to record laser power throughout the duration of lifetime testing. Prior to connecting a laser diode to the current source for characterization and lifetime testing, a background program is initiated to collect current, voltage, and resistance. This backstage data collection enables the operational test facility to have full laser diode traceablity.

Comparative clinical evaluation of the immediate and late analgesic effect of GaAlAs diode lasers of 830 and 660 nm in the treatment of dentine pain: preliminary results

NASA Astrophysics Data System (ADS)

Ladalardo, Thereza C.; Mangabeira Albernaz, Pedro L.; Brugnera, Aldo, Jr.; Zanin, Fatima A. A.; Siqueira, Jose T.; Pinheiro, Antonio L. B.

2002-06-01

In this comparative clinical study, we aimed at evaluating the immediate and late analgesic effect of GaAlAs diode lasers of 660 nm and 830 nm in treatment of dentine pain. We used GaAlAs diode lasers of 660 nm and 830 nm with 35 mW, continuous wave emission, spot size 1 mm2 and a dosage of 4 joules/cm2 applied to the cervical dentine surface. In total 4 treatment sessions were performed at intervals of 7 days in a period of 4 consecutive weeks. A total of 40 teeth treated were divided into two groups comprising 20 teeth each: one group irradiated with a 660 nm wavelength laser, and the other one with a 830 nm wavelength laser. By means of a quantitative visual analogue scale (V.A.S.), we measured the sensitive responses to cold stimulus pre- treatment, and at a follow-up period of 15 and 30 minutes post-treatment in both groups in order to evaluate the immediate analgesic effect. The late effect was evaluated at a follow-up period of 15 and 30 days. Using the GaAlAs diode laser of 660 nm wavelength resulted in better levels of dentine desensitization, at both immediate and late analgesic effect analysis compared with the use of the GaAlAs diode laser of 830 nm wavelength.

Bactericidal effect of visible light in the presence of erythrosine on Porphyromonas gingivalis and Fusobacterium nucleatum compared with diode laser, an in vitro study.

PubMed

Habiboallah, Ghanbari; Mahdi, Zakeri; Mahbobeh, Naderi Nasab; Mina, Zareian Jahromi; Sina, Faghihi; Majid, Zakeri

2014-12-27

Recently, photodynamic therapy (PDT) has been introduced as a new modality in oral bacterial decontamination. Besides, the ability of laser irradiation in the presence of photosensitizing agent to lethal effect on oral bacteria is well documented. Current research aims to evaluate the effect of photodynamic killing of visible blue light in the presence of plaque disclosing agent erythrosine as photosensitizer on Porphyromonas gingivalis associated with periodontal bone loss and Fusobacterium nucleatum associated with soft tissue inflammation, comparing with the near-infrared diode laser. Standard suspension of P. gingivalis and F. nucleatum were exposed to Light Emitting Diode (LED) (440-480 nm) used to photopolymerize composite resine dental restoration in combination with erythrosine (22 µm) up to 5 minutes. Bacterial sample were also exposed to a near-infrared diode laser (wavelength, 830 nm), using identical irradiation parameters for comparison. Bacterial samples from each treatment groups (radiation-only group, erythrosine-only group and light or laser with erythrosine group) were subcultured onto the surface of agar plates. Survival of these bacteria was determined by counting the number of colony forming units (CFU) after incubation. Exposure to visible blue light and diode laser in conjugation with erythrosine significantly reduced both species examined viability, whereas erythrosine-treated samples exposed to visible light suggested a statically meaningful differences comparing to diode laser. In addition, bactericidal effect of visible light or diode laser alone on P. gingivalis as black-pigmented bacteria possess endogenous porphyrins was noticeably. Our result suggested that visible blue light source in the presence of plaque disclosing agent erythrosine could can be consider as potential approach of PDT to kill the main gram-negative periodontal pathogens. From a clinical standpoint, this regimen could be established as an additional minimally invasive antibacterial treatment of plaque induced periodontal pathologies.

Lifetime behavior of laser diodes with highly strained InGaAs QWs and emission wavelength between 1120 nm and 1180 nm

NASA Astrophysics Data System (ADS)

Bugge, F.; Bege, R.; Blume, G.; Feise, D.; Sumpf, B.; Werner, N.; Zeimer, U.; Paschke, K.; Weyers, M.

2018-06-01

Highly strained InxGa1-xAs QWs are commonly used for laser diodes in the wavelength range beyond 1100 nm, but they suffer from strain induced formation of defects. The effect of different laser structures and different laser layouts on the aging behavior was investigated. If grown and processed under optimized conditions, laser diodes emitting at 1120 nm, 1156 nm and 1180 nm have lifetimes of several 1000 h up to more than 20,000 h in dependence on structure or indium content. Laser diodes with three different emission wavelength were mounted in a microoptical bench with a second harmonic generation crystal. From these benches laser emission in the green-yellow spectral range with more than 800 mW output power was obtained.

Comparison of the Antibacterial Effect of 810 nm Diode Laser and Photodynamic Therapy in Reducing the Microbial Flora of Root Canal in Endodontic Retreatment in Patients With Periradicular Lesions

PubMed Central

Asnaashari, Mohammad; Godiny, Mostafa; Azari-Marhabi, Saranaz; Tabatabaei, Fahimeh Sadat; Barati, Maryam

2016-01-01

Introduction: The aim of this study was to compare the antibacterial efficacy of diode laser 810nm and photodynamic therapy (PDT) in reducing bacterial microflora in endodontic retreatment of teeth with periradicular lesion. Methods: In this in vivo clinical trial, 20 patients who needed endodontic retreatment were selected. After conventional chemo mechanical preparation of root canals, microbiological samples were taken with sterile paper point (PP), held in thioglycollate broth, and then were transferred to the microbiological lab. In the first group, PDT with methylene blue (MB) and diode laser (810 nm, 0.2 W, 40 seconds) was performed and in the second group diode laser (810 nm, 1.2 W, 30 seconds) was irradiated. Then second samples were taken from all canals. Results: CFU/ml amounts showed statistically significant reduction in both groups (P < 0.001). CFU/ml amounts were compared between the two groups and there was no statistical difference. Conclusion: PDT and diode laser 810 nm irradiation are effective methods for root canal disinfection. PDT is a suitable alternative for diode laser 810 nm irradiation, because of lower thermal risk on root dentin. PMID:27330705

Evaluation of the Diode laser (810nm, 980 nm) on color change of teeth after external bleaching

PubMed Central

Kiomars, Nazanin; Azarpour, Pouneh; Mirzaei, Mansooreh; Hashemi kamangar, Sedighe Sadat; Kharazifard, Mohammad Javad

2016-01-01

Subject and aim: The aim of this study was to evaluate the efficiency of diode laser-activated bleaching systems for color change of teeth. Materials & Methods: 40 premolars with intact enamel surfaces were selected for five external bleaching protocols (n=8). Two different wavelengths of diode laser (810 and 980 nm) with two different hydrogen peroxide concentrations (30% and 46%) were selected for laser bleaching. Group 1 received bleaching (Heydent- Germany) with a 810 nm diode laser; Group 2 received bleaching (Heydent- Germany) with a 980 nm diode laser; Group 3 received bleaching (laser white*20- Biolase) with a 810 nm diode laser; Group 4 received bleaching (laser white*20- Biolase) with a 980 nm diode laser, with an output power of 1.5 W, in continuous wave (cw) mode for each irradiation. Group 5 as control group received 40% hydrogen peroxide (Opalescence Boost, Ultradent-USA) with no light activation. The color of teeth was scored at baseline and 1 week after bleaching with spectrophotometer. Color change data on the CIEL*a*b* system were analyzed statistically by the one-way ANOVA and Tukey's HSD test. Results: All the bleaching techniques resulted in shade change. According to ΔE values, all techniques were effective to bleach the teeth (ΔE ≥ 3). Statistically significant differences were detected among bleaching protocols (p=0.06). Regarding shade change values expressed as ΔL*, Δa*, Δb*, ΔE*, laser bleached groups were no statistically different with each other (p>0.05). Conclusion: Bleaching with different wavelengths of diode laser resulted in the same results. PMID:28765671

Evaluation of the Diode laser (810nm, 980 nm) on color change of teeth after external bleaching.

PubMed

Kiomars, Nazanin; Azarpour, Pouneh; Mirzaei, Mansooreh; Hashemi Kamangar, Sedighe Sadat; Kharazifard, Mohammad Javad; Chiniforush, Nasim

2016-12-30

Subject and aim: The aim of this study was to evaluate the efficiency of diode laser-activated bleaching systems for color change of teeth. Materials & Methods: 40 premolars with intact enamel surfaces were selected for five external bleaching protocols (n=8). Two different wavelengths of diode laser (810 and 980 nm) with two different hydrogen peroxide concentrations (30% and 46%) were selected for laser bleaching. Group 1 received bleaching (Heydent- Germany) with a 810 nm diode laser; Group 2 received bleaching (Heydent- Germany) with a 980 nm diode laser; Group 3 received bleaching (laser white*20- Biolase) with a 810 nm diode laser; Group 4 received bleaching (laser white*20- Biolase) with a 980 nm diode laser, with an output power of 1.5 W, in continuous wave (cw) mode for each irradiation. Group 5 as control group received 40% hydrogen peroxide (Opalescence Boost, Ultradent-USA) with no light activation. The color of teeth was scored at baseline and 1 week after bleaching with spectrophotometer. Color change data on the CIEL*a*b* system were analyzed statistically by the one-way ANOVA and Tukey's HSD test. Results: All the bleaching techniques resulted in shade change. According to ΔE values, all techniques were effective to bleach the teeth (ΔE ≥ 3). Statistically significant differences were detected among bleaching protocols (p=0.06). Regarding shade change values expressed as ΔL*, Δa*, Δb*, ΔE*, laser bleached groups were no statistically different with each other (p>0.05). Conclusion: Bleaching with different wavelengths of diode laser resulted in the same results.

Systematic review of the adjunctive use of diode and Nd:YAG lasers for nonsurgical periodontal instrumentation.

PubMed

Roncati, Marisa; Gariffo, Annalisa

2014-04-01

The aims of this study were (1) to conduct a literature search and systematically evaluate the additional therapeutic effects of pulsed Nd:YAG or diode laser use in patients with periodontitis, (2) to assess evidence supporting the additional benefit of laser-mediated periodontal treatment in conjunction with scaling and root planning (SRP) (not as monotherapy), and (3) to interpret the evidence presented in retrieved publications. Opinions about the additional use of diode lasers in the nonsurgical treatment of plaque-induced periodontal lesions are conflicting. The April 2011 American Academy of Periodontology's "Statement on the Efficacy of Lasers in the Non-Surgical Treatment of Inflammatory Periodontal Disease" asserted that the use of a laser as monotherapy or in addition to nonsurgical periodontal instrumentation conveyed no advantage. After initial screening, 23/77 potentially relevant articles and abstracts identified through electronic and manual searches of the MEDLINE(®)/PubMed database and the Cochrane Central Register of Controlled Trials (1990-2012) were included in this review. A meta-analysis could be performed. The results indicate that Nd:YAG or diode laser, used in an adjunctive capacity to SRP, may provide some additional benefit, in 6 month studies, compared with mechanical debridement. The results show the adjunctive benefits that diode laser treatment can provide when it is used as an adjunct to nonsurgical periodontal treatment in adults with chronic periodontitis. Further long-term, well-designed, parallel randomized clinical trials are needed to assess the effectiveness of the adjunctive use of the diode laser, as well as the appropriate dosimetry and laser settings.

Direct diode lasers and their advantages for materials processing and other applications

NASA Astrophysics Data System (ADS)

Fritsche, Haro; Ferrario, Fabio; Koch, Ralf; Kruschke, Bastian; Pahl, Ulrich; Pflueger, Silke; Grohe, Andreas; Gries, Wolfgang; Eibl, Florian; Kohl, Stefanie; Dobler, Michael

2015-03-01

The brightness of diode lasers is improving continuously and has recently started to approach the level of some solid state lasers. The main technology drivers over the last decade were improvements of the diode laser output power and divergence, enhanced optical stacking techniques and system design, and most recently dense spectral combining. Power densities at the work piece exceed 1 MW/cm2 with commercially available industrial focus optics. These power densities are sufficient for cutting and welding as well as ablation. Single emitter based diode laser systems further offer the advantage of fast current modulation due their lower drive current compared to diode bars. Direct diode lasers may not be able to compete with other technologies as fiber or CO2-lasers in terms of maximum power or beam quality. But diode lasers offer a range of features that are not possible to implement in a classical laser. We present an overview of those features that will make the direct diode laser a very valuable addition in the near future, especially for the materials processing market. As the brightness of diode lasers is constantly improving, BPP of less than 5mm*mrad have been reported with multikW output power. Especially single emitter-based diode lasers further offer the advantage of very fast current modulation due to their low drive current and therefore low drive voltage. State of the art diode drivers are already demonstrated with pulse durations of <10μs and repetition rates can be adjusted continuously from several kHz up to cw mode while addressing power levels from 0-100%. By combining trigger signals with analog modulations nearly any kind of pulse form can be realized. Diode lasers also offer a wide, adaptable range of wavelengths, and wavelength stabilization. We report a line width of less than 0.1nm while the wavelength stability is in the range of MHz which is comparable to solid state lasers. In terms of applications, especially our (broad) wavelength combining technology for power scaling opens the window to new processes of cutting or welding and process control. Fast power modulation through direct current control allows pulses of several microseconds with hundreds of watts average power. Spot sizes of less than 100 μm are obtained at the work piece. Such a diode system allows materials processing with a pulse parameter range that is hardly addressed by any other laser system. High productivity material ablation with cost effective lasers is enabled. The wide variety of wavelengths, high brightness, fast power modulation and high efficiency of diode lasers results in a strong pull of existing markets, but also spurs the development of a wide variety of new applications.

Evaluation of a satellite laser ranging technique using pseudonoise code modulated laser diodes

NASA Technical Reports Server (NTRS)

Ball, Carolyn Kay

1987-01-01

Several types of Satellite Laser Ranging systems exist, operating with pulsed, high-energy lasers. The distance between a ground point and an orbiting satellite can be determined to within a few centimeters. A new technique substitutes pseudonoise code modulated laser diodes, which are much more compact, reliable and less costly, for the lasers now used. Since laser diode technology is only now achieving sufficiently powerful lasers, the capabilities of the new technique are investigated. Also examined are the effects of using an avalanche photodiode detector instead of a photomultiplier tube. The influence of noise terms (including background radiation, detector dark and thermal noise and speckle) that limit the system range and performance is evaluated.

Evaluation of antimicrobial and thermal effects of diode laser on root canal dentin.

PubMed

Kıvanc, B H; Arısu, H D; Sağlam, B C; Akça, G; Gürel, M A; Görgül, G

2017-12-01

The aim of this study was to evaluate the antimicrobial effects of diode laser and temperature rise on the root surface during application. Thirty-six teeth were chemomechanically prepared and irrigated with 2.5% sodium hypochlorite and 17% ethylenediaminetetraacetic acid, and then autoclaved and incubated with a suspension of Enterococcus faecalis. The specimens were randomly divided into three groups (n = 12): Group 1, irradiated by diode laser at 1.2 W; Group 2, irradiated by diode laser at 2 W; and Group 3, irradiated by diode laser at 3 W. The grown bacteria were counted and the mean numbers of the each test tube were determined. The temperature was measured on the external apical third of the root during laser application. The mean values of results for each group were compared using one-way analysis of variance and Tukey test. No significant difference was obtained among the test groups in terms of the colony counts (P > 0.05). According to the temperature changes, there was a significant difference between groups (P < 0.05). Temperature rises were 16.79°C, 10.20°C, and 6.25°C in Group 3, Group 2, and Group 1, respectively. Diode laser irradiation with 1.2 W demonstrated comparable performance with 2 W and 3 W power sets for elimination of E. faecalis from root canal with less temperature rise.

Diffractive Combiner of Single-Mode Pump Laser-Diode Beams

NASA Technical Reports Server (NTRS)

Liu, Duncan; Wilson, Daniel; Qiu, Yueming; Forouhar, Siamak

2007-01-01

An optical beam combiner now under development would make it possible to use the outputs of multiple single-mode laser diodes to pump a neodymium: yttrium aluminum garnet (Nd:YAG) nonplanar ring oscillator (NPRO) laser while ensuring that the laser operates at only a single desired frequency. Heretofore, an Nd:YAG NPRO like the present one has been pumped by a single multimode laser-diode beam delivered via an optical fiber. It would be desirable to use multiple pump laser diodes to increase reliability beyond that obtainable from a single pump laser diode. However, as explained below, simplistically coupling multiple multimode laser-diode beams through a fiber-optic combiner would entail a significant reduction in coupling efficiency, and lasing would occur at one or more other frequencies in addition to the single desired frequency. Figure 1 schematically illustrates the principle of operation of a laser-diode-pumped Nd:YAG NPRO. The laser beam path is confined in a Nd:YAG crystal by means of total internal reflections on the three back facets and a partial-reflection coating on the front facet. The wavelength of the pump beam - 808 nm - is the wavelength most strongly absorbed by the Nd:YAG crystal. The crystal can lase at a wavelength of either 1,064 nm or 1,319 nm - which one depending on the optical coating on the front facet. A thermal lens effect induced by the pump beam enables stable lasing in the lowest-order transverse electromagnetic mode (the TEM00 mode). The frequency of this laser is very stable because of the mechanical stability of the laser crystal and the unidirectional nature of the lasing. The unidirectionality is a result of the combined effects of (1) a Faraday rotation induced by an externally applied magnetic field and (2) polarization associated with non-normal incidence and reflection on the front facet.

[Photodynamic therapy of dysplasias and early carcinomas in Barrett esophagus with a diode laser system--a pilot study].

PubMed

Zöpf, T; Rosenbaum, A; Apel, D; Jakobs, R; Arnold, J C; Riemann, J F

2001-04-15

Photodynamic therapy (PDT) of dysplasia and early cancer of the esophagus could show good results in the potential of ablation. Unfortunately, the existing expensive and temperamental dye laser systems foiled a broad clinical use. In this pilot study, we investigated the feasibility of an inexpensive and maintenance-free diode laser system for PDT of dysplasia and early cancer in Barrett's esophagus. Eight patients with Barrett's esophagus and/or early cancer were treated. As light source we used a diode laser system with a maximum power output of 2 W and a wavelength of 633 +/- 3 nm. One patient was treated initially with Photosan-3, seven patients received 5-aminolevulinic acid. In all patients we could achieve reduction in length and/or histologically proven downgrading. In three quarters of the patients, complete eradication of adenocarcinoma could be attained. Columnar-lined metaplastic epithelium could also be completely eradicated. PDT using a diode laser system is comparably effective in Barrett's esophagus/early cancer as PDT with dye laser systems. PDT is a gentle and effective technique with little side effects.

Biological effects of a semiconductor diode laser on human periodontal ligament fibroblasts

PubMed Central

Choi, Eun-Jeong; Yim, Ju-Young; Koo, Ki-Tae; Seol, Yang-Jo; Lee, Yong-Moo; Ku, Young; Rhyu, In-Chul; Chung, Chong-Pyoung

2010-01-01

Purpose It has been reported that low-level semiconductor diode lasers could enhance the wound healing process. The periodontal ligament is crucial for maintaining the tooth and surrounding tissues in periodontal wound healing. While low-level semiconductor diode lasers have been used in low-level laser therapy, there have been few reports on their effects on periodontal ligament fibroblasts (PDLFs). We performed this study to investigate the biological effects of semiconductor diode lasers on human PDLFs. Methods Human PDLFs were cultured and irradiated with a gallium-aluminum-arsenate (GaAlAs) semiconductor diode laser of which the wavelength was 810 nm. The power output was fixed at 500 mW in the continuous wave mode with various energy fluencies, which were 1.97, 3.94, and 5.91 J/cm2. A culture of PDLFs without laser irradiation was regarded as a control. Then, cells were additionally incubated in 72 hours for MTS assay and an alkaline phosphatase (ALPase) activity test. At 48 hours post-laser irradiation, western blot analysis was performed to determine extracellular signal-regulated kinase (ERK) activity. ANOVA was used to assess the significance level of the differences among groups (P<0.05). Results At all energy fluencies of laser irradiation, PDLFs proliferation gradually increased for 72 hours without any significant differences compared with the control over the entire period taken together. However, an increment of cell proliferation significantly greater than in the control occurred between 24 and 48 hours at laser irradiation settings of 1.97 and 3.94 J/cm2 (P<0.05). The highest ALPase activity was found at 48 and 72 hours post-laser irradiation with 3.94 J/cm2 energy fluency (P<0.05). The phosphorylated ERK level was more prominent at 3.94 J/cm2 energy fluency than in the control. Conclusions The present study demonstrated that the GaAlAs semiconductor diode laser promoted proliferation and differentiation of human PDLFs. PMID:20607054

Infrared diode laser spectroscopy of the △ ν = 2 band of AlF

NASA Astrophysics Data System (ADS)

Horiai, Koui; Uehara, Hiromichi

2006-04-01

A vibrational-rotational spectrum of the △ ν = 2 transitions of a high-temperature molecule AlF was observed between 1490 and 1586 cm -1 with a diode laser spectrometer. Measurements were made on the ν = 3-1, 4-2, 5-3 and 8-6 bands at a temperature of 900 °C. Measured spectral lines were fitted to effective band constants ν0, Bν and Dν for each band. Present measurements were made with only one Pb-salt laser diode. Physical significance of the effective band constants is discussed.

Tunable diode-laser heterodyne spectrometer for remote observations near 8 microns

NASA Technical Reports Server (NTRS)

Glenar, D.; Kostiuk, T.; Jennings, D. E.; Buhl, D.; Mumma, M. J.

1982-01-01

A diode-laser-based, ultrahigh resolution IR heterodyne spectrometer for laboratory and field use has been developed for operation between 7.5 and 8.5 microns. The local oscillator is a PbSe tunable diode laser kept continuously at operating temperatures of 12-60 K using a closed-cycle cooler. The laser output frequency is controlled and stabilized using a high-precision diode current supply, constant temperature controller, and a shock isolator mounted between the refrigerator cold tip and the diode mount. The system largely employs reflecting optics to minimize losses from internal reflection and absorption and to eliminate chromatic effects. Spectral analysis of the diode-laser output between 0 and 1 GHz reveals excess noise at many diode current settings, which limits the IR spectral regions over which useful heterodyne operation can be achieved. Observations have been made of atmospheric N2O, O3, and CH4 between 1170 and 1200/cm, using both a single-frequency swept IF channel and a 64-channel RF spectral line receiver with a total IF coverage of 1600 MHz.

Low-Coherence light source design for ESPI in-plane displacement measurements

NASA Astrophysics Data System (ADS)

Heikkinen, J. J.; Schajer, G. S.

2018-01-01

The ESPI method for surface deformation measurements requires the use of a light source with high coherence length to accommodate the optical path length differences present in the apparatus. Such high-coherence lasers, however, are typically large, delicate and costly. Laser diodes, on the other hand, are compact, mechanically robust and inexpensive, but unfortunately they have short coherence length. The present work aims to enable the use of a laser diode as an illumination source by equalizing the path lengths within an ESPI interferometer. This is done by using a reflection type diffraction grating to compensate for the path length differences. The high optical power efficiency of such diffraction gratings allows the use of much lower optical power than in previous interferometer designs using transmission gratings. The proposed concept was experimentally investigated by doing in-plane ESPI measurements using a high-coherence single longitudinal mode (SLM) laser, a laser diode and then a laser diode with path length optimization. The results demonstrated the limitations of using an uncompensated laser diode. They then showed the effectiveness of adding a reflection type diffraction grating to equalize the interferometer path lengths. This addition enabled the laser diode to produce high measurement quality across the entire field of view, rivaling although not quite equaling the performance of a high-coherence SLM laser source.

Diode pumped solid-state laser oscillators for spectroscopic applications

NASA Technical Reports Server (NTRS)

Byer, R. L.; Basu, S.; Fan, T. Y.; Kozlovsky, W. J.; Nabors, C. D.; Nilsson, A.; Huber, G.

1987-01-01

The rapid improvement in diode laser pump sources has led to the recent progress in diode laser pumped solid state lasers. To date, electrical efficiencies of greater than 10 percent were demonstrated. As diode laser costs decrease with increased production volume, diode laser and diode laser array pumped solid state lasers will replace the traditional flashlamp pumped Nd:YAG laser sources. The use of laser diode array pumping of slab geometry lasers will allow efficient, high peak and average power solid state laser sources to be developed. Perhaps the greatest impact of diode laser pumped solid state lasers will be in spectroscopic applications of miniature, monolithic devices. Single-stripe diode-pumped operation of a continuous-wave 946 nm Nd:YAG laser with less than 10 m/w threshold was demonstrated. A slope efficiency of 16 percent near threshold was shown with a projected slope efficiency well above a threshold of 34 percent based on results under Rhodamine 6G dye-laser pumping. Nonlinear crystals for second-harmonic generation of this source were evaluated. The KNbO3 and periodically poled LiNbO3 appear to be the most promising.

An in-vitro evaluation of the effect of 980 nm diode laser irradiation on intra-canal dentin surface and dentinal tubule openings after biomechanical preparation: Scanning electron microscopic study

PubMed Central

Jhingan, Pulkit; Sandhu, Meera; Jindal, Garima; Goel, Deepti; Sachdev, Vinod

2015-01-01

Context: Very recently, diode laser has been used for disinfecting the root canals in endodontic treatment and increasing its success rate and longevity utilizing the thermal effect of laser on surrounding tissues. Aims: The aim of this study is to evaluate the effect of 980 nm laser irradiation on intra-canal dentin surface – scanning electron microscopic (SEM) - in-vitro study. Methods: A total of 40 single-rooted freshly extracted permanent teeth were collected. Teeth were sectioned at the cemento-enamel junction using diamond disc. Root canals of all samples were prepared using hand ProTaper, which were randomly assigned into two groups (n = 20 each). Group 1: Receiving no treatment after biomechanical preparation; Group 2: 980 nm diode laser-treated root canals. Teeth were prepared for SEM analysis to check the size of intra-canal dentinal tubule openings. Statistical Analysis Used: Data were analyzed using SPSS V.16 software and compared using Levene's and independent t-test. Results: On statistical analysis, width of intracanal dentinal tubule openings in Group 1 (control) was significantly higher than those observed in Group 2 (diode laser-treated) (P < 0.001). Conclusion: This study showed that the application of 980 nm diode laser on intra-radicular dentin resulted in ultrastructural alterations resulting in melting of dentin. PMID:26097338

Quantum Noise in Laser Diodes

NASA Technical Reports Server (NTRS)

Giacobino, E.; Marin, F.; Bramati, A.; Jost, V.; Poizat, J. Ph.; Roch, J.-F.; Grangier, P.; Zhang, T.-C.

1996-01-01

We have investigated the intensity noise of single mode laser diodes, either free-running or using different types of line narrowing techniques at room temperature. We have measured an intensity squeezing of 1.2 dB with grating-extended cavity lasers and 1.4 dB with injection locked lasers (respectively 1.6 dB and 2.3 dB inferred at the laser output). We have observed that the intensity noise of a free-running nominally single mode laser diode results from a cancellation effect between large anti-correlated fluctuations of the main mode and of weak longitudinal side modes. Reducing the side modes by line narrowing techniques results in intensity squeezing.

Clinical application of a new 0.63- to 0.65-μm pulse diode laser in treating ear, throat, and nose diseases in adults and children

NASA Astrophysics Data System (ADS)

Nasedkin, Alexy N.; Pletnev, A. S.

2001-04-01

An investigation was made of applying a pulsed diode laser emitting at the wavelengths of 0.63 to 0.65 micrometers to treat various otolaryngological diseases, such as rhinosinusitis, acute rhinitis, vasomotor rhinitis, allergic rhinitis, the illness of the lymphoid ring, adenoiditis, chronic tonsillitis, pharyngitis, and catarrhal and suppurative otitis. The therapeutic effect produced by the pulsed diode laser was compared with that of conventional therapeutic lasers. It was found that the pulsed low-intensity laser radiation in the red spectrum region offered a number of advantages over conventional laser therapeutic techniques.

Theoretical model for frequency locking a diode laser with a Faraday cell

NASA Technical Reports Server (NTRS)

Wanninger, P.; Shay, T. M.

1992-01-01

A new method was developed for frequency locking a diode lasers, called 'the Faraday anomalous dispersion optical transmitter (FADOT) laser locking', which is much simpler than other known locking schemes. The FADOT laser locking method uses commercial laser diodes with no antireflection coatings, an atomic Faraday cell with a single polarizer, and an output coupler to form a compound cavity. The FADOT method is vibration insensitive and exhibits minimal thermal expansion effects. The system has a frequency pull in the range of 443.2 GHz (9 A). The method has potential applications in optical communication, remote sensing, and pumping laser excited optical filters.

Means for phase locking the outputs of a surface emitting laser diode array

NASA Technical Reports Server (NTRS)

Lesh, James R. (Inventor)

1987-01-01

An array of diode lasers, either a two-dimensional array of surface emitting lasers, or a linear array of stripe lasers, is phase locked by a diode laser through a hologram which focuses the output of the diode laser into a set of distinct, spatially separated beams, each one focused onto the back facet of a separate diode laser of the array. The outputs of the diode lasers thus form an emitted coherent beam out of the front of the array.

Efficacy of diode laser (810 and 940 nm) for facial skin tightening.

PubMed

Voravutinon, Nataya; Seawthaweesin, Kanikar; Bureethan, Apron; Srivipatana, Anchisa; Vejanurug, Patnapa

2015-12-01

Laser treatment has been introduced for facial skin tightening. However, no prior study has used a diode laser to treat facial skin laxity. To evaluate the efficacy and safety of a 810- and 940-nm diode laser (MeDioStarNeXT) for treating facial skin laxity. Thirty patients, with facial skin laxity grading scale II-IV, were enrolled in this study. Each patient underwent four sessions with a 810- and 940-nm diode laser (MeDioStarNeXT) treatment over 3-week intervals. Improvement in the laxity of facial skin was evaluated using a Cutometer MPA 580, spectrophotometer, and a grading scale. Significant improvement was observed with the Cutometer F3 and R7 parameters at 1 and 3 months after complete treatment, respectively. Physician assessment showed significant improvement in the laxity scale at 1 and 6 months after treatment. Approximately 10% of the patients reported mild pain or minor adverse events. Ninety-eight percent of the patients were satisfied with the treatments. Treatment with a diode laser (810 and 940 nm) is safe and may be effective for facial skin tightening. Maintenance treatment is necessary to sustain the effect of treatment. © 2015 Wiley Periodicals, Inc.

Minimal Invasive Approach for Lips Venous Lake Treatment by 980 nm Diode Laser with Emphasis on the Aesthetic Results. А Clinical Series.

PubMed

Voynov, Parvan P; Tomov, Georgi T; Mateva, Nonka G

2016-01-01

A venous lake (VL) is a vascular lesion with common occurrence in many patients, manifested as a dark blue-to-violet compressible papule, caused by dilation of venules. The main reasons for the treatment of VL are aesthetic. The haemorrhaging episodes or impairment of oral normal functions are also under considerations. Treatment of lip VL includes surgical excision, selective photocoagulation, cryotherapy, sclerotherapy and electrodessication. The high-intensity diode laser is an option. The 980 nm diode laser is selectively absorbed by haemoglobin and selectively destroys blood vessels, minimising injury to the surrounding healthy skin. The purpose of this study was to evaluate the effectiveness of diode laser in the treatment of VL lesions with the accent on the postoperative defects and aesthetic results. 35 patients aged 37 to 71 were included in this study. A 980 nm diode laser was used in noncontact mode, under local anaesthesia in continuous wave (2-3W, for 20-60s). All patients received only one procedure. Healing process was completed within 2 to 4 weeks after treatment with no scarring. None of the typical adverse effects were observed in the process of healing. Selective photocoagulation is an effective method for treatment of VL. Lower morbidity, minimal patient discomfort and satisfactory functional and aesthetic results are favourable for patients. To optimise the results and to reduce the adverse effects, basic knowledge on lasers and laser-tissue interactions is requisite.

Development and performance of a laser heterodyne spectrometer using tunable semiconductor lasers as local oscillators

NASA Technical Reports Server (NTRS)

Glenar, D.; Kostiuk, T.; Jennings, D. E.; Mumma, M. J.

1980-01-01

A diode laser based IR heterodyne spectrometer for laboratory and field use was developed for high efficiency operation between 7.5 and 8.5 microns. The local oscillator is a PbSSe tunable diode laser kept continuously at operating temperatures of 12-60 K using a closed cycle cooler. The laser output frequency is controlled and stabilized using a high precision diode current supply, constant temperature controller, and a shock isolator mounted between the refrigerator cold tip and the diode mount. Single laser modes are selected by a grating placed in the local oscillator beam. The system employs reflecting optics throughout to minimize losses from internal reflection and absorption, and to eliminate chromatic effects. Spectral analysis of the diode laser output between 0 and 1 GHz reveals excess noise at many diode current settings, which limits the infrared spectral regions over which useful heterodyne operation can be achieved. System performance has been studied by making heterodyne measurements of etalon fringes and several Freon 13 (CF3Cl) absorption lines against a laboratory blackbody source. Preliminary field tests have also been performed using the Sun as a source.

Effect of laser speckle on light from laser diode-pumped phosphor-converted light sources.

PubMed

Aquino, Felipe; Jadwisienczak, Wojciech M; Rahman, Faiz

2017-01-10

Laser diode (LD) pumped white light sources are being developed as an alternative to light-emitting diode-pumped sources for high efficiency and/or high brightness applications. While several performance metrics of laser-pumped phosphor-converted light sources have been investigated, the effect of laser speckle has not been sufficiently explored. This paper describes our experimental studies on how laser speckle affects the behavior of light from laser-excited phosphor lamps. A single LD pumping a phosphor plate was the geometry explored in this work. Overall, our findings are that the down-converted light did not exhibit any speckle, whereas speckle was present in the residual pump light but much reduced from that in direct laser light. Furthermore, a thicker coating of small-grained phosphors served to effectively reduce speckle through static pump light diffusion in the phosphor coating. Our investigations showed that speckle is not of concern in illumination from LD-pumped phosphor-converted light sources.

The Effect of Diode Laser on Planktonic Enterococcus faecalis in Infected Root Canals in an Ex Vivo Model.

PubMed

Cretella, Gilda; Lajolo, Carlo; Castagnola, Raffaella; Somma, Francesco; Inchingolo, MariaTeresa; Marigo, Luca

2017-04-01

This study examined the bactericidal effect of diode laser irradiation against intracanal Enterococcus faecalis. m total of 128 extracted single-rooted and single-canal teeth were treated with ProTaper instruments (Dentsply Maillefer, Ballaigues, Switzerland). A total of 120 root canals were inoculated with E. faecalis for 21 days, and the samples were randomly divided into five groups: Group 1 (n = 24) samples were irrigated with only saline solution (positive controls); Group 2 (n = 24) was treated with only 5.25% sodium hypochlorite; Group 3 (n = 24) was irrigated with saline solutions activated by diode laser; Group 4 (n = 24) was treated with 5.25% sodium hypochlorite activated by diode laser; and Group 5 (n = 24) was irrigated with saline solution with methylene blue dye activated by the diode laser Fox (Sweden & Martina, Padova, Italy); additionally, eight teeth were not contaminated and their canals were irrigated with saline solution and used as a negative control. The Uro-Quick system was used to determine the microbial residual charge. The data were analyzed using Pearson's chi-square test (p < 0.001). A statistically significant reduction in bacterial count was observed in Group 2 and Group 4 (p < 0.001). There were no statistically significant differences among the other groups (p > 0.001). Evidence indicates that the diode laser was not more effective than sodium hypochlorite in reducing free bacteria.

Analysis of High-Power Diode Laser Heating Effects on HY-80 Steel for Laser Assisted Friction Stir Welding Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiechec, Maxwell; Baker, Brad; McNelley, Terry

In this research, several conditions of high power diode laser heated HY-80 steel were characterized to determine the viability of using such lasers as a preheating source before friction stir welding in order to reduce frictional forces thereby reducing tool wear and increasing welding speeds. Differences in microstructures within heat affected zones were identified at specific laser powers and traverse speeds. Vickers hardness values were recorded and analyzed to validate the formation of additional martensite in diode laser heated regions of HY-80 steel. Conditions that produced little to no additional martensite were identified and relationships among high power diode lasermore » power, traverse speed, and martensite formation were determined. The development of heat affected zones, change in grain structure, and creation of additional martensite in HY-80 can be prevented through the optimization of laser amperage and transverse speed.« less

Management of Chronic Periodontitis Using Chlorhexidine Chip and Diode Laser-A Clinical Study.

PubMed

Jose, Kachapilly Arun; Ambooken, Majo; Mathew, Jayan Jacob; Issac, Annie Valayil; Kunju, Ajithkumar Parachalil; Parameshwaran, Renjith Athirkandathil

2016-04-01

The use of adjuncts like chlorhexidine local delivery and diode laser decontamination have been found to improve the clinical outcomes of scaling and root planing in non-surgical periodontal therapy in patients with chronic periodontitis. To evaluate the effects of diode laser and chlorhexidine chip as adjuncts to scaling and root planing in the management of chronic periodontitis. The objective is to evaluate the outcome of chlorhexidine chip and diode laser as adjuncts to scaling and root planing on clinical parameters like Plaque Index, Gingival Index, probing pocket depth and clinical attachment level. Department of Periodontics. Randomized clinical trial with split mouth design. Fifteen chronic periodontitis patients having a probing pocket depth of 5mm-7mm on at least one interproximal site in each quadrant of the mouth were included in the study. After initial treatment, four sites in each patient were randomly subjected to scaling and root planing (control), chlorhexidine chip application (CHX chip group), diode laser (810 nm) decontamination (Diode laser group) or combination of both (Diode laser and chip group). Plaque Index (PI), Gingival Index (GI), probing pocket depth (PPD) and clinical attachment level (CAL) were assessed at baseline, one month and three months. Results were statistically analysed using paired T test, one-way ANOVA, Tukey's HSD test and repeated measure ANOVA. Post-treatment, the test and control sites showed a statistically significant reduction in PI, GI, PPD, and CAL. After three months, a mean PPD reduction of 1.47±0.52 mm in control group, 1.40±0.83 mm in diode laser group, 2.67±0.62 mm in CHX group, and 2.80± 0.77 mm in combination group was seen. The mean gain in CAL were 1.47±0.52 mm in the control group, 1.40±0.83 mm in diode laser group, 2.67± 0.49 mm in CHX group and 2.67± 0.82 mm in combination group respectively. The differences in PPD reduction and CAL gain between control group and CHX chip and combination groups were statistically significant (p<0.05) at three months, whereas, the diode laser group did not show any significant difference from the control group. Chlorhexidine local delivery alone or in combination with diode laser decontamination is effective in reducing probing pocket depth and improving clinical attachment levels when used as adjuncts to scaling and root planing in non-surgical periodontal therapy of patients with chronic periodontitis.

Management of Chronic Periodontitis Using Chlorhexidine Chip and Diode Laser-A Clinical Study

PubMed Central

Ambooken, Majo; Mathew, Jayan Jacob; Issac, Annie Valayil; Kunju, Ajithkumar Parachalil; Parameshwaran, Renjith Athirkandathil

2016-01-01

Introduction The use of adjuncts like chlorhexidine local delivery and diode laser decontamination have been found to improve the clinical outcomes of scaling and root planing in non-surgical periodontal therapy in patients with chronic periodontitis. Aim To evaluate the effects of diode laser and chlorhexidine chip as adjuncts to scaling and root planing in the management of chronic periodontitis. The objective is to evaluate the outcome of chlorhexidine chip and diode laser as adjuncts to scaling and root planing on clinical parameters like Plaque Index, Gingival Index, probing pocket depth and clinical attachment level. Study and Design Department of Periodontics. Randomized clinical trial with split mouth design. Materials and Methods Fifteen chronic periodontitis patients having a probing pocket depth of 5mm-7mm on at least one interproximal site in each quadrant of the mouth were included in the study. After initial treatment, four sites in each patient were randomly subjected to scaling and root planing (control), chlorhexidine chip application (CHX chip group), diode laser (810 nm) decontamination (Diode laser group) or combination of both (Diode laser and chip group). Plaque Index (PI), Gingival Index (GI), probing pocket depth (PPD) and clinical attachment level (CAL) were assessed at baseline, one month and three months. Statistical analysis Results were statistically analysed using paired T test, one-way ANOVA, Tukey’s HSD test and repeated measure ANOVA. Results Post-treatment, the test and control sites showed a statistically significant reduction in PI, GI, PPD, and CAL. After three months, a mean PPD reduction of 1.47±0.52 mm in control group, 1.40±0.83 mm in diode laser group, 2.67±0.62 mm in CHX group, and 2.80± 0.77 mm in combination group was seen. The mean gain in CAL were 1.47±0.52 mm in the control group, 1.40±0.83 mm in diode laser group, 2.67± 0.49 mm in CHX group and 2.67± 0.82 mm in combination group respectively. The differences in PPD reduction and CAL gain between control group and CHX chip and combination groups were statistically significant (p<0.05) at three months, whereas, the diode laser group did not show any significant difference from the control group. Conclusion Chlorhexidine local delivery alone or in combination with diode laser decontamination is effective in reducing probing pocket depth and improving clinical attachment levels when used as adjuncts to scaling and root planing in non-surgical periodontal therapy of patients with chronic periodontitis. PMID:27190958

Intraindividual comparison of 1,470 nm diode laser versus carbon dioxide laser for tonsillotomy: a prospective, randomized, double blind, controlled feasibility trial.

PubMed

Havel, Miriam; Sroka, Ronald; Englert, Elsa; Stelter, Klaus; Leunig, Andreas; Betz, Christian S

2012-09-01

The need for reduction of post-tonsillectomy hemorrhage has led to promotion of tonsillotomy techniques for tonsil tissue reduction in obstructive tonsillar hypertrophy. This trial compares ablative tissue effects using 1,470 nm diode laser and carbon dioxide laser for tonsillotomy in an intraindividual design. 21 children aged 3-13 years (mean age 6.3 years) underwent laser tonsillotomy for obstructive tonsillar hypertrophy in this double blind, prospective, randomized, clinical feasibility trial. In each of the blinded patients, tonsillotomy was performed using fiber guided 1,470 nm diode laser (contact mode, 15 W power) on the one side and carbon dioxide laser (12 W power) on the other side. An independent, blinded physician documented clinical presentation and patients' symptoms preoperatively and on Days 1, 3, 7, 14, and 21 post-operatively using standardized questionnaire including VAS for each side separately. The mean duration of operative treatment was 2.7 min using 1,470 nm laser and 4.9 min using carbon dioxide laser respectively. Intraoperative bleeding and the frequency of bipolar forceps use for intraoperative bleeding control was significantly less using 1,470 nm diode laser system. There was no difference in post-operative pain scores between the carbon dioxide laser treated and the 1,470 nm fiber guided diode laser treated side. No infections, hemorrhages or other complications occurred in the course of the 3 weeks post-operative period. A fiber-guided 1,470 nm diode laser system offers an efficient and safe method for tonsillotomy as treatment of obstructive tonsillar hypertrophy. Compared to our standard practice (carbon dioxide laser), 1,470 nm laser application provides comparable tissue ablation effects with less intraoperative bleeding and shorter operation time. Copyright © 2012 Wiley Periodicals, Inc.

885-nm laser diode array pumped ceramic Nd:YAG master oscillator power amplifier system

NASA Astrophysics Data System (ADS)

Yu, Anthony W.; Li, Steven X.; Stephen, Mark A.; Seas, Antonios; Troupaki, Elisavet; Vasilyev, Aleksey; Conley, Heather; Filemyr, Tim; Kirchner, Cynthia; Rosanova, Alberto

2010-04-01

The objective of this effort is to develop more reliable, higher efficiency diode pumped Nd:YAG laser systems for space applications by leveraging technology investments from the DoD and other commercial industries. Our goal is to design, build, test and demonstrate the effectiveness of combining 885 nm laser pump diodes and the use of ceramic Nd:YAG for future flight missions. The significant reduction in thermal loading on the gain medium by the use of 885 nm pump lasers will improve system efficiency.

Bistable optical devices with laser diodes coupled to absorbers of narrow spectral bandwidth.

PubMed

Maeda, Y

1994-06-20

An optical signal inverter was demonstrated with a combination of the following two effects: One is the decrease of the transmission of an Er-doped YAG crystal with increasing red shift of a laser diode resulting from an increase in the injection current, and the other is a negative nonlinear absorption in which the transmission decreases inversely with increasing laser intensity. Because a hysteresis characteristic exists in the relationship between the wavelength and the injection current of the laser diode, an optical bistability was observed in this system.

Comparison between sequentional treatment with diode and alexandrite lasers versus alexandrite laser alone in the treatment of hirsutism.

PubMed

Nilforoushzadeh, Mohammad Ali; Naieni, Farahnaz Fatemi; Siadat, Amir Hossein; Rad, Leila

2011-11-01

Laser systems that are commonly used for the treatment of hirsutism include the ruby laser (694 nm), the diode laser (800 nm), the alexandrite laser (755 nm) and the Nd:YAG laser (1084 nm). The diode laser and alexandrite laser are considered effective in treatment of hirsutism in dark-skinned patients. The response of hairs to these laser systems is variable and not complete. In this study, we compared the efficacy of these two laser systems for permanent hair removal. This was a randomized, controlled clinical trial that was performed with women of the age range 15-45 years old. After obtaining informed consent, the samples were randomized into two groups using random allocation software. The first group was treated with alexandrite laser alone (four sessions, two months apart). The second group was treated sequentially with diode laser for the first two sessions and alexandrite laser for the next two sessions. Overall, 111 patients (57 patients in the alexandrite laser group and 54 patients in the sequential diode-alexandrite laser group) were evaluated. There was no significant difference regarding mean of hair reduction between the two groups during the courses of treatment. Except for the first session, there was no significant difference regarding percent of patient satisfaction between the two groups (P value >0.05). Comparison between the two groups showed no significant difference one month, three months and six months after the last treatment (P value >0.05). Regarding the results of our study, there is no significant difference between sequential treatment with diode and alexandrite lasers versus alexandrite laser alone in the treatment of hirsutism. We suggest that in further studies, the efficacy of sequential treatment with other laser systems is evaluated against single treatment methods.

The Beam Characteristics of High Power Diode Laser Stack

NASA Astrophysics Data System (ADS)

Gu, Yuanyuan; Fu, Yueming; Lu, Hui; Cui, Yan

2018-03-01

Direct diode lasers have some of the most attractive features of any laser. They are very efficient, compact, wavelength versatile, low cost, and highly reliable. However, the full utilization of direct diode lasers has yet to be realized. However, the poor quality of diode laser beam itself, directly affect its application ranges, in order to better use of diode laser stack, need a proper correction of optical system, which requires accurate understanding of the diode laser beam characteristics. Diode laser could make it possible to establish the practical application because of rectangular beam patterns which are suitable to make fine bead with less power. Therefore diode laser cladding will open a new field of repairing for the damaged machinery parts which must contribute to recycling of the used machines and saving of cost.

Direct diode lasers with comparable beam quality to fiber, CO2, and solid state lasers

NASA Astrophysics Data System (ADS)

Huang, Robin K.; Chann, Bien; Burgess, James; Kaiman, Michael; Overman, Robert; Glenn, John D.; Tayebati, Parviz

2012-03-01

TeraDiode has produced kW-class ultra-high brightness fiber-coupled direct diode lasers. A fiber-coupled direct diode laser with a power level of 2,040 W from a 50 μm core diameter, 0.15 numerical aperture (NA) output fiber at a single center wavelength was demonstrated. This was achieved with a novel beam combining and shaping technique using COTS diode lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 3.75 mm-mrad and is the lowest BPP kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 2-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers.

Treatment of keloid scars with a 1210-nm diode laser in an animal model.

PubMed

Philandrianos, Cécile; Bertrand, Baptiste; Andrac-Meyer, Lucile; Magalon, Guy; Casanova, Dominique; Kerfant, Nathalie; Mordon, Serge

2015-12-01

A temperature increase can improve wound healing by activation of heat shock protein 70 and stimulation of fibroblasts. Since keloids are a dysfunction of collagen fiber synthesis and organization, this study aimed to evaluate if a 1,210 nm diode laser could have effects in a new animal model of keloid scars. A total of 39 nude mice were used for this study. Phototypes IV and V human keloids were grafted into their backs and after 1 month of healing, the mice were divided into four groups: Control, Laser, Resection, Resection/Laser. In the Laser group, the keloids were treated with a 1,210-nm diode-laser with the following parameters: 4 W; 10 seconds; fluence: 51 J/cm(2) ; spot: 18.9 × 3.7 mm(2) . In the Resection group, surgical intra-lesional excision was performed. In the Resection/Laser group, keloids were treated with the 1,210-nm laser-diode after surgical intra-lesional excision. Temperature measurements were made during the laser treatment. Clinical examination and histological study were performed on the day of treatment and 1 month, 2 months, and 3 months later. Mean temperature measurement was of 44.8°C (42-48°) in the Laser groups. No healing complications or keloid proliferation was observed in any group. Keloid histologic characters were confirmed in all grafts. No histologic particularity was observed in the laser groups in comparison with the Control and Resection groups. First, this keloid animal model appears to be adapted for laser study. Secondly, the 1,210-nm diode laser does not induce keloid thermal damage in vivo. Further studies with different 1,210-nm laser diode parameters should be performed in order to observe significant effects on keloids. © 2015 Wiley Periodicals, Inc.

Arbitrary waveform generator to improve laser diode driver performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fulkerson, Jr, Edward Steven

2015-11-03

An arbitrary waveform generator modifies the input signal to a laser diode driver circuit in order to reduce the overshoot/undershoot and provide a "flat-top" signal to the laser diode driver circuit. The input signal is modified based on the original received signal and the feedback from the laser diode by measuring the actual current flowing in the laser diode after the original signal is applied to the laser diode.

Clinical Evaluation of Hair Removal Using an 810 nm Diode Laser With a Novel Scanning Device.

PubMed

Courtney, Erin; Goldberg, David J

2016-11-01

Diode lasers are often considered as the gold standard preference for hair removal due to the deep penetration and ef- fective targeting of the hair follicle. A wide variety of diode lasers are available, which can differ in terms of their parameters (such as fluence, pulse duration, repetition rate, scanner, and cooling). The objective of the study was to evaluate the safety and ef cacy of hair removal with an 810 nm novel scanning diode laser, up to six months after last treatment. A scanning 810 nm diode laser was used for axillary hair removal of 14 female patients who received 3 treatments, 4-6 weeks apart. Follow-up on hair count was conducted 3 and 6 months after last treatment and compared to baseline hair count. No unexpected or signi cant adverse events were recorded. An average hair count reduction of 72.8% after 3 months and 67.6% 6 months after the last treatment is demonstrated. The examined 810 nm diode laser was proven to be safe and effective for hair removal. Results were sustained for 6 months after last treatment. Longer follow-up data are followed for further substantiation of the clinical effect. Scanning technology can provide for potentially faster and safer treatments. J Drugs Dermatol. 2016;15(11):1330-1333..

Numerical analysis of high-power broad-area laser diode with improved heat sinking structure using epitaxial liftoff technique

NASA Astrophysics Data System (ADS)

Kim, Younghyun; Sung, Yunsu; Yang, Jung-Tack; Choi, Woo-Young

2018-02-01

The characteristics of high-power broad-area laser diodes with the improved heat sinking structure are numerically analyzed by a technology computer-aided design based self-consistent electro-thermal-optical simulation. The high-power laser diodes consist of a separate confinement heterostructure of a compressively strained InGaAsP quantum well and GaInP optical cavity layers, and a 100-μm-wide rib and a 2000-μm long cavity. In order to overcome the performance deteriorations of high-power laser diodes caused by self-heating such as thermal rollover and thermal blooming, we propose the high-power broad-area laser diode with improved heat-sinking structure, which another effective heat-sinking path toward the substrate side is added by removing a bulk substrate. It is possible to obtain by removing a 400-μm-thick GaAs substrate with an AlAs sacrificial layer utilizing well-known epitaxial liftoff techniques. In this study, we present the performance improvement of the high-power laser diode with the heat-sinking structure by suppressing thermal effects. It is found that the lateral far-field angle as well as quantum well temperature is expected to be improved by the proposed heat-sinking structure which is required for high beam quality and optical output power, respectively.

Determination of the effective refractive index spectrum of a quantum-well semiconductor laser diode from the measured modal gain spectrum

NASA Astrophysics Data System (ADS)

Wu, Linzhang; Tian, Wei; Gao, Feng

2004-09-01

This paper presents a self-consistent method to directly determine the effective refractive-index spectrum of a semiconductor quantum-well (QW) laser diode from the measured modal gain spectrum for a given current. The dispersion spectra of the optical waveguide confinement factor and the strongly carrier-density-dependent refractive index of the QW active layer of the test laser are also accurately obtained. The experimental result from a single QW GaInP/AlGaInP laser diode, which has 6 nm thick compressively strained Ga0.4InP active layer sandwiched by two 80 nm thick Al0.33GaInP, is presented.

Development and optimization of a diode laser for photodynamic therapy.

PubMed

Lim, Hyun Soo

2011-01-01

This study demonstrated the development of a laser system for cancer treatment with photodynamic therapy (PDT) based on a 635 nm laser diode. In order to optimize efficacy in PDT, the ideal laser system should deliver a homogeneous nondivergent light energy with a variable spot size and specific wavelength at a stable output power. We developed a digital laser beam controller using the constant current method to protect the laser diode resonator from the current spikes and other fluctuations, and electrical faults. To improve the PDT effects, the laser system should deliver stable laser energy in continuous wave (CW), burst mode and super burst mode, with variable irradiation times depending on the tumor type and condition. The experimental results showed the diode laser system described herein was eminently suitable for PDT. The laser beam was homogeneous without diverging and the output power increased stably and in a linear manner from 10 mW to 1500 mW according to the increasing input current. Variation between the set and delivered output was less than 7%. The diode laser system developed by the author for use in PDT was compact, user-friendly, and delivered a stable and easily adjustable output power at a specific wavelength and user-set emission modes.

Development and optimization of a diode laser for photodynamic therapy

PubMed Central

Lim, Hyun Soo

2011-01-01

Background and Aims: This study demonstrated the development of a laser system for cancer treatment with photodynamic therapy (PDT) based on a 635 nm laser diode. In order to optimize efficacy in PDT, the ideal laser system should deliver a homogeneous nondivergent light energy with a variable spot size and specific wavelength at a stable output power. Materials and Methods: We developed a digital laser beam controller using the constant current method to protect the laser diode resonator from the current spikes and other fluctuations, and electrical faults. To improve the PDT effects, the laser system should deliver stable laser energy in continuous wave (CW), burst mode and super burst mode, with variable irradiation times depending on the tumor type and condition. Results and Comments: The experimental results showed the diode laser system described herein was eminently suitable for PDT. The laser beam was homogeneous without diverging and the output power increased stably and in a linear manner from 10 mW to 1500 mW according to the increasing input current. Variation between the set and delivered output was less than 7%. Conclusions: The diode laser system developed by the author for use in PDT was compact, user-friendly, and delivered a stable and easily adjustable output power at a specific wavelength and user-set emission modes. PMID:24155529

Comparison of Refractive Error Changes in Retinopathy of Prematurity Patients Treated with Diode and Red Lasers.

PubMed

Roohipoor, Ramak; Karkhaneh, Reza; Riazi Esfahani, Mohammad; Alipour, Fateme; Haghighat, Mahtab; Ebrahimiadib, Nazanin; Zarei, Mohammad; Mehrdad, Ramin

2016-01-01

To compare refractive error changes in retinopathy of prematurity (ROP) patients treated with diode and red lasers. A randomized double-masked clinical trial was performed, and infants with threshold or prethreshold type 1 ROP were assigned to red or diode laser groups. Gestational age, birth weight, pretreatment cycloplegic refraction, time of treatment, disease stage, zone and disease severity were recorded. Patients received either red or diode laser treatment and were regularly followed up for retina assessment and refraction. The information at month 12 of corrected age was considered for comparison. One hundred and fifty eyes of 75 infants were enrolled in the study. Seventy-four eyes received diode and 76 red laser therapy. The mean gestational age and birth weight of the infants were 28.6 ± 3.2 weeks and 1,441 ± 491 g, respectively. The mean baseline refractive error was +2.3 ± 1.7 dpt. Posttreatment refraction showed a significant myopic shift (mean 2.6 ± 2.0 dpt) with significant difference between the two groups (p < 0.001). There was a greater myopic shift among children with zone I and diode laser treatment (mean 6.00 dpt) and a lesser shift among children with zone II and red laser treatment (mean 1.12 dpt). The linear regression model, using the generalized estimating equation method, showed that the type of laser used has a significant effect on myopic shift even after adjustment for other variables. Myopic shift in laser-treated ROP patients is related to the type of laser used and the involved zone. Red laser seems to cause less myopic shift than diode laser, and those with zone I involvement have a greater myopic shift than those with ROP in zone II. © 2016 S. Karger AG, Basel.

Comparison of Antibacterial Effects of 810 and 980- nanometer Diode Lasers on Enterococcus Faecalis in the Root Canal System -An in vitro study.

PubMed

Asnaashari, Mohamad; Ebad, Leila Tahmasebi; Shojaeian, Shiva

2016-10-01

Background and aim: Use of laser technology in endodontics has greatly increased in the recent years due to the introduction of new wavelengths and methods and optimal antimicrobial and smear layer removal properties of lasers. This in vitro study aimed to compare the antibacterial effects of diode lasers of 810 nm and 980 nm wavelength on Enterococcus faecalis (E. faecalis) biofilm in the root canal system. Materials and methods: Fifty single-canal human anterior teeth were cleaned, shaped, sterilized and randomly divided into four groups namely two experimental, one positive and one negative control group. The experimental and positive control groups were inoculated with E. faecalis and incubated for two weeks. The experimental group one (n=20) received 810 nm diode laser irradiation (1.5W) while the experimental group two (n=20) was subjected to 980 nm diode laser irradiation (1.5W). The E. faecalis colony forming units (CFUs) were counted in each root canal before and after laser irradiation. Results: Laser irradiation significantly decreased the bacterial colony count in both experimental groups. The reduction in microbial count was significantly greater in 810 nm laser group compared to 980 nm laser group. Conclusion: Irradiation of both 810 and 980 nm lasers significantly decreased the E. faecalis count in the root canal system; 810 nm laser was more effective in decreasing the intracanal microbial load.

Comparison of Antibacterial Effects of 810 and 980- nanometer Diode Lasers on Enterococcus Faecalis in the Root Canal System —An in vitro study

PubMed Central

Asnaashari, Mohamad; Ebad, Leila Tahmasebi

2016-01-01

Background and aim: Use of laser technology in endodontics has greatly increased in the recent years due to the introduction of new wavelengths and methods and optimal antimicrobial and smear layer removal properties of lasers. This in vitro study aimed to compare the antibacterial effects of diode lasers of 810 nm and 980 nm wavelength on Enterococcus faecalis (E. faecalis) biofilm in the root canal system. Materials and methods: Fifty single-canal human anterior teeth were cleaned, shaped, sterilized and randomly divided into four groups namely two experimental, one positive and one negative control group. The experimental and positive control groups were inoculated with E. faecalis and incubated for two weeks. The experimental group one (n=20) received 810 nm diode laser irradiation (1.5W) while the experimental group two (n=20) was subjected to 980 nm diode laser irradiation (1.5W). The E. faecalis colony forming units (CFUs) were counted in each root canal before and after laser irradiation. Results: Laser irradiation significantly decreased the bacterial colony count in both experimental groups. The reduction in microbial count was significantly greater in 810 nm laser group compared to 980 nm laser group. Conclusion: Irradiation of both 810 and 980 nm lasers significantly decreased the E. faecalis count in the root canal system; 810 nm laser was more effective in decreasing the intracanal microbial load. PMID:27853346

High-Reliability Pump Module for Non-Planar Ring Oscillator Laser

NASA Technical Reports Server (NTRS)

Liu, Duncan T.; Qiu, Yueming; Wilson, Daniel W.; Dubovitsky, Serge; Forouhar, Siamak

2007-01-01

We propose and have demonstrated a prototype high-reliability pump module for pumping a Non-Planar Ring Oscillator (NPRO) laser suitable for space missions. The pump module consists of multiple fiber-coupled single-mode laser diodes and a fiber array micro-lens array based fiber combiner. The reported Single-Mode laser diode combiner laser pump module (LPM) provides a higher normalized brightness at the combined beam than multimode laser diode based LPMs. A higher brightness from the pump source is essential for efficient NPRO laser pumping and leads to higher reliability because higher efficiency requires a lower operating power for the laser diodes, which in turn increases the reliability and lifetime of the laser diodes. Single-mode laser diodes with Fiber Bragg Grating (FBG) stabilized wavelength permit the pump module to be operated without a thermal electric cooler (TEC) and this further improves the overall reliability of the pump module. The single-mode laser diode LPM is scalable in terms of the number of pump diodes and is capable of combining hundreds of fiber-coupled laser diodes. In the proof-of-concept demonstration, an e-beam written diffractive micro lens array, a custom fiber array, commercial 808nm single mode laser diodes, and a custom NPRO laser head are used. The reliability of the proposed LPM is discussed.

698-nm diode laser with 1-Hz linewidth

NASA Astrophysics Data System (ADS)

Chen, Long; Zhang, Linbo; Xu, Guanjun; Liu, Jun; Dong, Ruifang; Liu, Tao

2017-01-01

Two diode lasers at 698 nm are separately locked to two independent optical reference cavities with a finesse of about 128,000 by the Pound-Drever-Hall method. The more accurate coefficient between voltage and frequency of the error signal is measured, with which quantitative evaluation of the effect of many noises on the frequency stability can be made much more conveniently. A temperature-insensitive method is taken to reduce the effect of residual amplitude modulation on laser frequency stability. With an active fiber noise cancellation, the optical heterodyne beat between two independent lasers shows that the linewidth of one diode laser reaches 1 Hz. The fractional Allan deviation removed linear frequency shift less than 30 mHz/s is below 2.6×10-15 with 1- to 100-s average time.

Comparative evaluation of antimicrobial effects of Er:YAG, diode, and CO₂ lasers on titanium discs: an experimental study.

PubMed

Tosun, Emre; Tasar, Ferda; Strauss, Robert; Kıvanc, Dolunay Gulmez; Ungor, Cem

2012-05-01

This study examined carbon dioxide (CO(2); 10,600 nm), diode (808 nm), and erbium (Er):yttrium-aluminum-garnet (YAG; 2,940 nm) laser applications on Staphylococcus aureus contaminated, sandblasted, large-grit, acid-etched surface titanium discs and performed a comparative evaluation of the obtained bactericidal effects and the applicability of these effects in clinical practice. This study was carried out in 5 main groups: Er:YAG laser in very short pulse (VSP) emission mode, Er:YAG laser in short pulse (SP) emission mode, diode laser with a 320-nm fiber optic diode laser with an R24-B handpiece, and CO(2) laser. After laser irradiation, dilutions were spread on sheep blood agar plates and, after an incubation period of 24 hours, colony-forming units were counted and compared with the control group, and the bactericidal activity was assessed in relation to the colony counts. The CO(2) laser eliminated 100% of the bacteria at 6 W, 20 Hz, and a 10-ms exposure time/pulse with a 10-second application period (0.8-mm spot size). The continuous-wave diode laser eliminated 97% of the bacteria at 1 W using a 10-second application with a 320-μm optic fiber, 100% of the bacteria were killed with a 1-W, 10-second continuous-wave application with an R14-B handpiece. The Er:YAG laser eliminated 100% of the bacteria at 90 mJ and 10 Hz using a 10-second application in a superpulse mode (300-ms exposure time/pulse). The Er:YAG laser also eliminated 99% to 100% of the bacteria in VSP mode at 90 mJ and 10 Hz with a 10-second application. The results of this study show that a complete, or near complete, elimination of surface bacteria on titanium surfaces can be accomplished in vitro using a CO(2), diode, or Er:YAG laser as long as appropriate parameters are used. Copyright © 2012 American Association of Oral and Maxillofacial Surgeons. All rights reserved.

Effectiveness of a diode laser in addition to non-surgical periodontal therapy: study of intervention.

PubMed

Crispino, Antonio; Figliuzzi, Michele Mario; Iovane, Claudio; Del Giudice, Teresa; Lomanno, Simona; Pacifico, Delfina; Fortunato, Leonzio; Del Giudice, Roberto

2015-01-01

Chronic periodontitis affects 47% of adult population over the age of 30. The first phase of periodontal treatment is always represented by scaling and root planning (SRP), that is a causal, non-surgical therapy that recognizes as primary aims the control of bacterial infection and the reduction of periodontal plaque-associated inflammation. Yet, another innovative causal therapy is represented by the irradiation of periodontal pockets with laser. To evaluate the effect of a 940-nm diode laser as an adjunct to SRP in patients affected by periodontitis. Sixty-eight adult patients with moderate-to-severe periodontitis were sequentially enrolled and undergone to periodontal examination (V1) in order to detect gingival index (GI), plaque index (PI) and probing depth (PD). The patients were randomly divided into two groups: the first (n=34) received SRP treatment alone, the control group (n=34) received SRP and 940-nm diode laser therapy. Data were analyzed by Student's t-test, with two tails; for all clinical parameters, both groups reported statistically significant differences compared to basal values (p<0.0001). Both procedures were effective in improving GI, PI and PD, but the use of diode laser was associated with more evident results. Considered the better clinical outcomes, diode laser can be routinely associated with SRP in the treatment of periodontal pockets of patients with moderate-to-severe periodontitis.

[Laservaporization of the prostate: current status of the greenlight and diode laser].

PubMed

Rieken, M; Bachmann, A; Gratzke, C

2013-03-01

In the last decade laser vaporization of the prostate has emerged as a safe and effective alternative to transurethral resection of the prostate (TURP). This was facilitated in particular by the introduction of photoselective vaporization of the prostate (PVP) with a 532 nm 80 W KTP laser in 2002. Prospective randomized trials comparing PVP and TURP with a maximum follow-up of 3 years mostly demonstrated comparable functional results. Cohort studies showed a safe application of PVP in patients under oral anticoagulation and with large prostates. Systems from various manufacturers with different maximum power output and wavelengths are now available for diode laser vaporization of the prostate. Prospective randomized trials comparing diode lasers and TURP are not yet available. In cohort studies and comparative studies PVP diode lasers are characterized by excellent hemostatic properties but functional results vary greatly with some studies reporting high reoperation rates.

Clinical assessment of diode laser-assisted endoscopic intrasphenoidal vidian neurectomy in the treatment of refractory rhinitis.

PubMed

Lai, Wen-Sen; Cheng, Sheng-Yao; Lin, Yuan-Yung; Yang, Pei-Lin; Lin, Hung-Che; Cheng, Li-Hsiang; Yang, Jinn-Moon; Lee, Jih-Chin

2017-12-01

For chronic rhinitis that is refractory to medical therapy, surgical intervention such as endoscopic vidian neurectomy (VN) can be used to control the intractable symptoms. Lasers can contribute to minimizing the invasiveness of ENT surgery. The aim of this retrospective study is to compare in patients who underwent diode laser-assisted versus traditional VN in terms of operative time, surgical field, quality of life, and postoperative complications. All patients had refractory rhinitis with a poor treatment response to a 6-month trial of corticosteroid nasal sprays and underwent endoscopic VN between November 2006 and September 2015. They were non-randomly allocated into either a cold instrument group or a diode laser-assisted group. Vidian nerve was excised with a 940-nm continuous wave diode laser through a 600-μm silica optical fiber, utilizing a contact mode with the power set at 5 W. A visual analog scale (VAS) was used to grade the severity of the rhinitis symptoms for quality of life assessment before the surgery and 6 months after. Of the 118 patients enrolled in the study, 75 patients underwent cold instrument VN and 43 patients underwent diode laser-assisted VN. Patients in the laser-assisted group had a significantly lower surgical field score and a lower postoperative bleeding rate than those in the cold instrument group. Changes in the VAS were significant in preoperative and postoperative nasal symptoms in each group. The application of diode lasers for vidian nerve transection showed a better surgical field and a lower incidence of postoperative hemorrhage. Recent advancements in laser application and endoscopic technique has made VN safer and more effective. We recommend this surgical approach as a reliable and effective treatment for patients with refractory rhinitis.

High duty cycle hard soldered kilowatt laser diode arrays

NASA Astrophysics Data System (ADS)

Klumel, Genady; Karni, Yoram; Oppenheim, Jacob; Berk, Yuri; Shamay, Moshe; Tessler, Renana; Cohen, Shalom

2010-02-01

High-brightness laser diode arrays operating at a duty cycle of 10% - 20% are in ever-increasing demand for the optical pumping of solid state lasers and directed energy applications. Under high duty-cycle operation at 10% - 20%, passive (conductive) cooling is of limited use, while micro-coolers using de-ionized cooling water can considerably degrade device reliability. When designing and developing actively-cooled collimated laser diode arrays for high duty cycle operation, three main problems should be carefully addressed: an effective local and total heat removal, a minimization of packaging-induced and operational stresses, and high-precision fast axis collimation. In this paper, we present a novel laser diode array incorporating a built-in tap water cooling system, all-hard-solder bonded assembly, facet-passivated high-power 940 nm laser bars and tight fast axis collimation. By employing an appropriate layout of water cooling channels, careful choice of packaging materials, proper design of critical parts, and active optics alignment, we have demonstrated actively-cooled collimated laser diode arrays with extended lifetime and reliability, without compromising their efficiency, optical power density, brightness or compactness. Among the key performance benchmarks achieved are: 150 W/bar optical peak power at 10% duty cycle, >50% wallplug efficiency and <1° collimated fast axis divergence. A lifetime of >0.5 Ghots with <2% degradation has been experimentally proven. The laser diode arrays have also been successfully tested under harsh environmental conditions, including thermal cycling between -20°C and 40°C and mechanical shocks at 500g acceleration. The results of both performance and reliability testing bear out the effectiveness and robustness of the manufacturing technology for high duty-cycle laser arrays.

The Effects of Diode Laser Therapy as an Adjunct to Scaling and Root Planing in the Treatment of Aggressive Periodontitis: A 1-Year Randomized Controlled Clinical Trial.

PubMed

Matarese, Giovanni; Ramaglia, Luca; Cicciù, Marco; Cordasco, Giancarlo; Isola, Gaetano

2017-12-01

The aim of this study was to investigate and compare the clinical, microbial, and inflammatory effects of a diode laser as an adjunct to scaling and root planing (SRP) versus SRP alone for the treatment of generalized aggressive periodontitis (GAgP). Using a split-mouth design, 31 patients with GAgP were enrolled in the study. The maxillary right and left quadrants were randomly assigned to SRP+diode laser or SRP alone. Patients were examined on a regular basis for clinical, microbiological, and inflammatory mediator changes over a 1-year period. Clinical attachment level (CAL) was the primary outcome variable chosen. In addition, subgingival biofilm samples and gingival crevicular fluid (GCF) inflammatory mediators were analyzed at each follow-up session. Compared to baseline, both treatments demonstrated an improvement in periodontal parameters at 1 year. However, SRP+diode laser produced a significant improvement in probing depth (PD; 2.56 ± 0.44 vs. 3.36 ± 0.51 mm, p < 0.05) and CAL (3.47 ± 0.25 vs. 4.11 ± 0.26 mm, p < 0.05) values compared to SRP alone. Similarly, in the SRP+diode laser group, the bacteria of orange complex group were significantly reduced at 30 and 60 days compared to SRP alone. Moreover, SRP+diode laser determined a reduction in mean GCF level of interleukin (IL)-1β and IL-1β/IL-10 ratio at 15 and 30 days compared to SRP alone (p < 0.05). At 1 year, SRP+diode laser yielded a significant reduction in some clinical parameters, while microbial and inflammatory mediator changes were not significantly reduced compared to SRP alone.

Laser therapy of muscle injuries.

PubMed

Dawood, Munqith S; Al-Salihi, Anam Rasheed; Qasim, Amenah Wala'a

2013-05-01

Low-level lasers are used in general therapy and healing process due to their good photo-bio-stimulation effects. In this paper, the effects of diode laser and Nd:YAG laser on the healing process of practically managed skeletal muscle trauma has been successfully studied. Standard impact trauma was induced by using a specially designed mechanical device. The impacted muscle was left for 3 days for complete development of blunt trauma. After that it was irradiated by five laser sessions for 5 days. Two types of lasers were used; 785-nm diode laser and 1.064-nm Nd:YAG laser, both in continuous and pulsed modes. A special electronic circuit was designed and implemented to modulate the diode laser for this purpose. Tissue samples of crushed skeletal muscle have been dissected from the injured irradiated muscle then bio-chemically analyzed for the regeneration of contractile and collagenous proteins using Lowry assay for protein determination and Reddy and Enwemeka assay for hydroxyproline determination. The results showed that both lasers stimulate the regeneration capability of traumatized skeletal muscle. The diode laser in CW and pulsed modes showed better results than the Nd:YAG in accelerating the preservation of the normal tissue content of collagenous and contractile proteins beside controlling the regeneration of non-functional fibrous tissue. This study proved that the healing achieved by the laser treatment was faster than the control group by 15-20 days.

Distributed feedback laser diode integrated with distributed Bragg reflector for continuous-wave terahertz generation.

PubMed

Kim, Namje; Han, Sang-Pil; Ryu, Han-Cheol; Ko, Hyunsung; Park, Jeong-Woo; Lee, Donghun; Jeon, Min Yong; Park, Kyung Hyun

2012-07-30

A widely tunable dual mode laser diode with a single cavity structure is demonstrated. This novel device consists of a distributed feedback (DFB) laser diode and distributed Bragg reflector (DBR). Micro-heaters are integrated on the top of each section for continuous and independent wavelength tuning of each mode. By using a single gain medium in the DFB section, an effective common optical cavity and common modes are realized. The laser diode shows a wide tunability of the optical beat frequency, from 0.48 THz to over 2.36 THz. Continuous wave THz radiation is also successfully generated with low-temperature grown InGaAs photomixers from 0.48 GHz to 1.5 THz.

Evaluation of the use of a 940 nm diode laser as an adjunct in flap surgery for treatment of chronic periodontitis

PubMed Central

Lobo, Tanya Marguerite; Pol, Dilip Ganpat

2015-01-01

Background: Lasers have several potential benefits such as antibacterial effect and stimulation of wound healing. In addition, hemostasis and delaying epithelial migration may facilitate the outcome of flap surgery. There is a minimal research and evidence currently available for the optimum method of use of a diode laser in flap surgery and its benefit and safety. Hence, this study aimed to investigate the adjunctive effect of diode laser irradiation in open flap debridement (OFD), while treating chronic periodontitis. Materials and Methods: A total of 30 patients with generalized chronic moderate to severe periodontitis with pocket probing depth (PD) ≥5 mm post - Phase I therapy were selected for a split-mouth study. Flap surgery with adjunctive diode laser irradiation was performed in the test quadrant while routine OFD was done in the control quadrant. Clinical parameters including PD, clinical attachment level, gingival recession, plaque index, gingival index and tooth mobility were recorded at baseline, 3 months and 6 months following treatment. In addition, patients’ rating of procedural pain as well as the development of complications postoperatively was assessed. Results: All clinical parameters significantly improved after therapy without any statistically significant difference between the two groups for any of the parameters. The exception was a significantly greater reduction in gingival inflammation in the laser treated group. The laser treatment was acceptable to the patient and did not cause any complications. Conclusion: The diode laser can be safely and effectively used as an adjunct to the treatment of chronic periodontitis with the advantage of decreased gingival inflammation. PMID:25810592

Effective Management of a pregnancy tumour using a soft tissue diode laser: a case Report.

PubMed

Sharma, Ambika; Mathur, Vijay Prakash; Sardana, Divesh

2014-12-27

Pregnancy tumours (PTs) are a non-neoplastic, reactive, inflammatory conditional gingival enlargement which occurs in the oral cavity during pregnancy. The lesion most frequently occurs on the gingiva but may also develop on the lip, tongue, oral mucosa and palate. When a large PT develops, it can interfere with mastication, speech, maintenance of oral hygiene and can be aesthetically disfiguring. The treatment of PTs depends upon the size of the lesion; smaller lesions can regress after parturition however large lesions need to be surgically removed. Conventional surgical techniques have the disadvantage of more bleeding from the surgical site and delay in healing of the scar tissue. The diode laser is a relatively new alternative to conventional surgical technique in intra-oral areas with the added advantage of bloodless procedures and rapid healing. The purpose of the present study is to highlight the management of a PT in a 25-year-old female using a diode laser delivering a painless, bloodless procedure with rapid postoperative healing. Diode laser excision of a persistent pregnancy tumour in a postpartum patient was safe and effective with minimal bleeding, good coagulation, and good wound healing. Among other lasers, the diode laser can therefore be considered for excisional treatment of persistent PTs.

Modeling the effect of heatsink performance in high-peak-power laser-diode-bar pump sources for solid-state lasers 011 011

DOE Office of Scientific and Technical Information (OSTI.GOV)

Honea, E.C., LLNL

We derive approximate expressions for transient output power and wavelength chirp of high- peak-power laser-diode bars assuming one-dimensional heat flow and linear temperature dependences for chirp and efficiency. The model is derived for pulse durations, 10 < {tau} < 1000 ps, typically used for diode-pumped solid-state lasers and is in good agreement with experimental data for Si heatsink mounted 940 nm laser-diode bars operating at 100 W/cm. The analytic expressions are more flexible and easily used than the results of operating point dependent numerical modeling. In addition, the analytic expressions used here can be integrated to describe the energy permore » unit wavelength for a given pulse duration, initial emission bandwidth and heatsink material. We find that the figure-of-merit for a heatsink material in this application is ({rho}C{sub p}K) where {rho}C{sub p} is the volumetric heat capacity and K is the thermal conductivity. As an example of the utility of the derived expressions, we determine an effective absorption coefficient as a function of pump pulse duration for a diode-pumped solid-state laser utilizing Yb:Sr{sub 5}(PO{sub 4}){sub 3}F (Yb:S-FAP) as the gain medium.« less

GreenLight HPS laser 120-W versus diode laser 200-W vaporization of the prostate: comparative clinical experience.

PubMed

Chiang, Po Hui; Chen, Chien Hsu; Kang, Chih Hsiung; Chuang, Yao Chi

2010-09-01

We present our clinical experiences of two recently introduced vaporization laser systems: the GreenLight High Performance System (HPS) laser (532 nm, 120 W) and the Diolas LFD diode laser (980 nm, 200 W). Two laser systems were evaluated to compare their clinical results for the treatment of benign prostatic hyperplasia (BPH). Patients were treated using either the GreenLight HPS laser (n = 84) or the diode laser (n = 55) in a prospective randomized study. The data of International Prostate Symptom Score (IPSS), maximum flow rate (Q(max)), post-void residual urine (PVR), and quality of life score (Qols) were recorded at baseline, 1-, 6-, and 12-month follow-ups. The prostate volume and prostate-specific antigen (PSA) level were assessed at baseline and 6-month follow-up. All complications were also recorded. There was a statistically significant difference in IPSS, Q(max), PVR, and QoLs in each laser group at the 1-, 6-, and 12-month follow-ups compared with baseline. There was no statistical significant difference in any of these parameters at any follow-up interval between each group. The diode laser demonstrates superior hemostatic properties compared with the GreenLight HPS laser. Postoperative incontinence and postoperative irritative symptoms are more pronounced (P < 0.05) after diode laser prostatectomy. Higher incidence of dysuria with sloughing tissues and epididymitis (P < 0.05) is noted after diode laser prostatectomy. Other complications were comparable for both procedures. Although both lasers can improve subjective and objective parameters of BPH, both can produce undesired effects. The search for the ideal vaporization laser to treat BPH still continues. 2010 Wiley-Liss, Inc.

Physics of frequency-modulated comb generation in quantum-well diode lasers

NASA Astrophysics Data System (ADS)

Dong, Mark; Cundiff, Steven T.; Winful, Herbert G.

2018-05-01

We investigate the physical origin of frequency-modulated combs generated from single-section semiconductor diode lasers based on quantum wells, isolating the essential physics necessary for comb generation. We find that the two effects necessary for comb generation—spatial hole burning (leading to multimode operation) and four-wave mixing (leading to phase locking)—are indeed present in some quantum-well systems. The physics of comb generation in quantum wells is similar to that in quantum dot and quantum cascade lasers. We discuss the nature of the spectral phase and some important material parameters of these diode lasers.

Low intensity 635 nm diode laser irradiation inhibits fibroblast-myofibroblast transition reducing TRPC1 channel expression/activity: New perspectives for tissue fibrosis treatment.

PubMed

Sassoli, Chiara; Chellini, Flaminia; Squecco, Roberta; Tani, Alessia; Idrizaj, Eglantina; Nosi, Daniele; Giannelli, Marco; Zecchi-Orlandini, Sandra

2016-03-01

Low-level laser therapy (LLLT) or photobiomodulation therapy is emerging as a promising new therapeutic option for fibrosis in different damaged and/or diseased organs. However, the anti-fibrotic potential of this treatment needs to be elucidated and the cellular and molecular targets of the laser clarified. Here, we investigated the effects of a low intensity 635 ± 5 nm diode laser irradiation on fibroblast-myofibroblast transition, a key event in the onset of fibrosis, and elucidated some of the underlying molecular mechanisms. NIH/3T3 fibroblasts were cultured in a low serum medium in the presence of transforming growth factor (TGF)-β1 and irradiated with a 635 ± 5 nm diode laser (continuous wave, 89 mW, 0.3 J/cm(2) ). Fibroblast-myofibroblast differentiation was assayed by morphological, biochemical, and electrophysiological approaches. Expression of matrix metalloproteinase (MMP)-2 and MMP-9 and of Tissue inhibitor of MMPs, namely TIMP-1 and TIMP-2, after laser exposure was also evaluated by confocal immunofluorescence analyses. Moreover, the effect of the diode laser on transient receptor potential canonical channel (TRPC) 1/stretch-activated channel (SAC) expression and activity and on TGF-β1/Smad3 signaling was investigated. Diode laser treatment inhibited TGF-β1-induced fibroblast-myofibroblast transition as judged by reduction of stress fibers formation, α-smooth muscle actin (sma) and type-1 collagen expression and by changes in electrophysiological properties such as resting membrane potential, cell capacitance and inwardly rectifying K(+) currents. In addition, the irradiation up-regulated the expression of MMP-2 and MMP-9 and downregulated that of TIMP-1 and TIMP-2 in TGF-β1-treated cells. This laser effect was shown to involve TRPC1/SAC channel functionality. Finally, diode laser stimulation and TRPC1 functionality negatively affected fibroblast-myofibroblast transition by interfering with TGF-β1 signaling, namely reducing the expression of Smad3, the TGF-β1 downstream signaling molecule. Low intensity irradiation with 635 ± 5 nm diode laser inhibited TGF-β1/Smad3-mediated fibroblast-myofibroblast transition and this effect involved the modulation of TRPC1 ion channels. These data contribute to support the potential anti-fibrotic effect of LLLT and may offer further informations for considering this therapy as a promising therapeutic tool for the treatment of tissue fibrosis. © 2015 Wiley Periodicals, Inc.

Healing effects and superoxide dismutase activity of diode/Ga-As lasers in a rabbit model of osteoarthritis.

PubMed

Lee, Jae Yeon; Lee, Sang Ui; Lim, Taekjoo; Choi, Seok Hwa

2014-01-01

Osteoarthritis is a major cause of pain and disability in joints. The present study investigated the effects of differences of wavelengths and continuous versus pulsed delivery modes of low-level laser therapy (LLT) in a rabbit model of osteoarthritis. Comparison of the healing effects and superoxide dismutase (SOD) activity between therapy using diode and Ga-As lasers was our primary interest. Simple continuous wave (808-nm diode) and super-pulsed wave (904-nm Ga-As) lasers were used. Osteoarthritis was induced by injecting hydrogen peroxide into the articular spaces of the right stifle in rabbits. The rabbits were randomly assigned to four groups: normal control without osteoarthritis induction (G1), osteoarthritis-induction group without treatment (G2), osteoarthritis induction with diode irradiation (G3), and osteoarthritis induction with Ga-As irradiation (G4). Laser irradiation was applied transcutaneously for 5 min every day for over four weeks, starting the first day after confirmation of induction of osteoarthritis. The induction of osteoarthritis and effects of LLT were evaluated by biochemistry, computed tomography, and histological analyses. The SOD activity in G3 and G4 rabbits at two and four weeks after laser irradiation was significantly higher than that of G1 animals (p<0.05). However, there was no significant difference between G3 and G4 animals. Moreover, there were significant differences at two and four weeks between the control and osteoarthritis-induction groups, but no significant difference between G3 and G4 in the computed tomographic analyses and histological findings. These results indicate that diode and Ga-As lasers are similarly effective in healing and inducing SOD activity for LLT applications in a rabbit model of OA. Copyright © 2014 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Frequency stabilization of diode-laser-pumped solid state lasers

NASA Technical Reports Server (NTRS)

Byer, Robert L.

1988-01-01

The goal of the NASA Sunlite program is to fly two diode-laser-pumped solid-state lasers on the space shuttle and while doing so to perform a measurement of their frequency stability and temporal coherence. These measurements will be made by combining the outputs of the two lasers on an optical radiation detector and spectrally analyzing the beat note. Diode-laser-pumped solid-state lasers have several characteristics that will make them useful in space borne experiments. First, this laser has high electrical efficiency. Second, it is of a technology that enables scaling to higher powers in the future. Third, the laser can be made extremely reliable, which is crucial for many space based applications. Fourth, they are frequency and amplitude stable and have high temporal coherence. Diode-laser-pumped solid-state lasers are inherently efficient. Recent results have shown 59 percent slope efficiency for a diode-laser-pumped solid-state laser. As for reliability, the laser proposed should be capable of continuous operation. This is possible because the diode lasers can be remote from the solid state gain medium by coupling through optical fibers. Diode lasers are constructed with optical detectors for monitoring their output power built into their mounting case. A computer can actively monitor the output of each diode laser. If it sees any variation in the output power that might indicate a problem, the computer can turn off that diode laser and turn on a backup diode laser. As for stability requirements, it is now generally believed that any laser can be stabilized if the laser has a frequency actuator capable of tuning the laser frequency as far as it is likely to drift in a measurement time.

Development of a red diode laser system for photodynamic therapy

NASA Astrophysics Data System (ADS)

Halkiotis, Konstantinos N.; Yova, Dido M.; Uzunoglou, Nikolaos K.; Papastergiou, Georgios; Matakias, Sotiris; Koukouvinos, Ilias

1998-07-01

The effectiveness of photodynamic treatment modality has been proven experimentally for a large variety of tumors, during the last years. This therapy utilizes the combined action of light and photosensitizing drug. Until now, a disadvantage of PDT has be the low tissue penetration of light, at the wavelengths of most commonly available lasers, for clinical studies. The red wavelength offers the advantage of increased penetration depth in tissue, in addition several new wavelength offers the advantage of increased penetration depth in tissue, in addition several new photosensitizers present absorption band at the region 630nm to 690nm. The development of high power red diode laser system for photodynamic therapy, has provided a cost effective alternative to existing lasers for use in PDT. This paper will describe the system design, development and performance of a diode laser system, connected with a fiber optic facility, to be used for PDT. The system was based on a high power semiconductor diode laser emitting at 655nm. The laser output power was approximately 60mW at the output of a 62.5/125/900 micron fiber optic probe. FUll technical details and optical performance characteristics of the system will be discussed in this paper.

Solid state laser systems for space application

NASA Technical Reports Server (NTRS)

Kay, Richard B.

1994-01-01

Since the last report several things have happened to effect the research effort. In laser metrology, measurements using Michelson type interferometers with an FM modulated diode laser source have been performed. The discrete Fourier transform technique has been implemented. Problems associated with this technique as well as the overall FM scheme were identified. The accuracy of the technique is not at the level we would expect at this point. We are now investigating the effect of various types of noise on the accuracy as well as making changes to the system. One problem can be addressed by modifying the original optical layout. Our research effort was also expanded to include the assembly and testing of a diode pumped\\Nd:YAG laser pumped\\Ti sapphire laser for possible use in sounding rocket applications. At this stage, the diode pumped Nd:YAG laser has been assembled and made operational.

Subthreshold diode laser micropulse photocoagulation for the treatment of diabetic macular edema.

PubMed

Sivaprasad, Sobha; Dorin, Giorgio

2012-03-01

Diabetic macular edema (DME) is a sight-threatening complication of diabetic retinopathy, the leading cause of visual loss in the working-age population in the industrialized and emerging world. The standard of care for DME is focal/grid laser photocoagulation, which is proven effective in reducing the risk of vision loss, but inherently destructive and associated with tissue damage and collateral effects. Subthreshold diode laser micropulse photocoagulation is a nondestructive tissue-sparing laser procedure, which, in randomized controlled trials for the treatment of DME, has been found equally effective as conventional photocoagulation. Functional and anatomical outcomes from four independent randomized controlled trials provide level one evidence that vision stabilization/improvement and edema resolution/reduction can be elicited with less or no retinal damage, and with fewer or no complications. This review describes the principles of subthreshold diode laser micropulse photocoagulation, its treatment modalities and clinical outcomes in the context of standard laser treatments and of emerging nonlaser therapies for DME.

Comparison of a novel high-power blue diode laser (λ=442 nm) with Ho:YAG (λ=2100 nm), Tm fiber (λ=1940 nm), and KTP (λ=532 nm) lasers for soft tissue ablation

NASA Astrophysics Data System (ADS)

Vinnichenko, Victoriya; Kovalenko, Anastasiya; Arkhipova, Valeriya; Yaroslavsky, Ilya; Altshuler, Gregory; Gapontsev, Valentin

2018-02-01

Three lasers were directly compared, including the Ho:YAG laser (λ = 2100 nm), Tm fiber laser (λ = 1940 nm) operating in 3 different modes (CW, regular pulse, and super pulse), and blue diode laser (λ = 442 nm) for vaporization and coagulation efficiency for treating blood-rich soft tissues, ex vivo, in a porcine kidney model at quasi-contact cutting in water. In addition, experimental results were compared with published data on performance of KTP laser (λ = 532 nm) at similar experimental settings (Power = 60 W and cutting speed = 2 mm/s). Tm fiber laser in pulsed mode and blue laser produced highest vaporization rates of 3.7 and 3.4 mm3/s, respectively. Tm fiber laser (in both CW and pulsed modes) also produced the largest coagulation zone among the laser sources tested. A carbonization zone was observed for Tm fiber laser in CW and pulsed modes, as well as for the blue diode laser. Tm fiber laser in super-pulse mode and Ho:YAG laser both resulted in irregular coagulation zones without carbonization. Comparison with known data for KTP laser revealed that tissue effects of the blue laser are similar to that of the KTP laser. These results suggest that the combination of the two lasers (Tm fiber and blue diode) in one system may achieve high cutting efficiency and optimal coagulation for hemostasis during surgical treatment. Ex vivo testing of the combined system revealed feasibility of this approach. The combination of the CW Tm fiber laser (120W) and the blue diode laser (60W) emitting through a combination tip were compared with CW 120 W Tm fiber laser alone and 120 W Ho:YAG laser. Vaporization rates measured 34, 28, and 6 mm3/s, and coagulation zones measured 0.6, 1.3, and 1.7 mm, respectively. A carbonization zone was only observed with CW Tm fiber laser. The vaporization rate of combined CW Tm fiber laser / blue diode laser was comparable to published data for KTP laser for equivalent total power. Thus, high-power blue diode laser, Tm fiber laser, and their combination may provide an alternative to conventional Ho:YAG and KTP lasers for applications in urology and other surgical fields.

Construction of an Extended Cavity Tunable Diode Laser

NASA Astrophysics Data System (ADS)

Deveney, Edward; Metcalf, Harold; Noe, John

2001-03-01

A diverse and vast amount of experiments at the forefront of experimental physics typically use diode lasers as an integral part of their arrangement. However, researchers who use unmodified commercially available diode lasers run into several complications. The laser diode that is purchased is often not of the same wavelength as is advertised; thus the researcher’s desired wavelength is not met. Because the semiconductor has such a short external cavity, it is very sensitive to the injection current, changes in room temperature, and has a large linewidth making it harder to tune. To obtain a finely tuned diode laser, temperature and current controlling of the diode laser are used in conjunction with an extended semiconductor cavity. This is achieved by mounting the hermetically sealed assembly atop a thermoelectric cooler, which uses the Peltier effect. Furthermore, the variation of the injection current may be used as an additional control for the wavelength output of the diode. The power range of 70 mW as controlled by the injection current adjusts the wavelength by a span of only 4 nanometers. The extended cavity consists of a diffraction grating adhered to a mirror mount and is used for grating feedback. That in turn is used to reduce the linewidth sufficiently enough in order to provide much better tunability. In the next three weeks, the tunable diode laser will be specifically applied to research in the areas of Second Harmonic Generation in a PPLN Crystal and Saturated Rubidium Spectroscopy. This study was supported in part by NSF grant PHY99-12312.

A pulsated weak-resonant-cavity laser diode with transient wavelength scanning and tracking for injection-locked RZ transmission.

PubMed

Lin, Gong-Ru; Chi, Yu-Chieh; Liao, Yu-Sheng; Kuo, Hao-Chung; Liao, Zhi-Wang; Wang, Hai-Lin; Lin, Gong-Cheng

2012-06-18

By spectrally slicing a single longitudinal-mode from a master weak-resonant-cavity Fabry-Perot laser diode with transient wavelength scanning and tracking functions, the broadened self-injection-locking of a slave weak-resonant-cavity Fabry-Perot laser diode is demonstrated to achieve bi-directional transmission in a 200-GHz array-waveguide-grating channelized dense-wavelength-division-multiplexing passive optical network system. Both the down- and up-stream slave weak-resonant-cavity Fabry-Perot laser diodes are non-return-to-zero modulated below threshold and coherently injection-locked to deliver the pulsed carrier for 25-km bi-directional 2.5 Gbits/s return-to-zero transmission. The master weak-resonant-cavity Fabry-Perot laser diode is gain-switched at near threshold condition and delivers an optical coherent pulse-train with its mode linewidth broadened from 0.2 to 0.8 nm by transient wavelength scanning, which facilitates the broadband injection-locking of the slave weak-resonant-cavity Fabry-Perot laser diodes with a threshold current reducing by 10 mA. Such a transient wavelength scanning induced spectral broadening greatly releases the limitation on wavelength injection-locking range required for the slave weak-resonant-cavity Fabry-Perot laser diode. The theoretical modeling and numerical simulation on the wavelength scanning and tracking effects of the master and slave weak-resonant-cavity Fabry-Perot laser diodes are performed. The receiving power sensitivity for back-to-back transmission at bit-error-rate <10(-10) is -25.6 dBm, and the power penalty added after 25-km transmission is less than 2 dB for all 16 channels.

Linear laser diode arrays for improvement in optical disk recording for space stations

NASA Technical Reports Server (NTRS)

Alphonse, G. A.; Carlin, D. B.; Connolly, J. C.

1990-01-01

The design and fabrication of individually addressable laser diode arrays for high performance magneto-optic recording systems are presented. Ten diode arrays with 30 mW cW light output, linear light vs. current characteristics and single longitudinal mode spectrum were fabricated using channel substrate planar (CSP) structures. Preliminary results on the inverse CSP structure, whose fabrication is less critically dependent on device parameters than the CSP, are also presented. The impact of systems parameters and requirements, in particular, the effect of feedback on laser design is assessed, and techniques to reduce feedback or minimize its effect on systems performance, including mode-stabilized structures, are evaluated.

Diode laser prostatectomy (VLAP): initial canine evaluation

NASA Astrophysics Data System (ADS)

Kopchok, George E.; Verbin, Chris; Ayres, Bruce; Peng, Shi-Kaung; White, Rodney A.

1995-05-01

This study evaluated the acute and chronic effects of diode laser (960 nm) prostatectomy using a Prolase II fiber in a canine model (n equals 5). The laser fiber consists of a 1000 um quartz fiber which reflects a cone of laser energy, at 45 degree(s) to the axis of the fiber, into the prostatic urethra (Visual Laser Ablation of Prostate). Perineal access was used to guide a 15.5 Fr cystoscope to the level of the prostate. Under visual guidance and continual saline irrigation, 60 watts of laser power was delivered for 60 seconds at 3, 9, and 12 o'clock and 30 seconds at the 6 o'clock (posterior) positions for a total energy fluence of 12,600 J. One prostate received an additional 60 second exposure at 3 and 9 o'clock for a total fluence of 19,800 J. The prostates were evaluated at one day (n equals 1) and 8 weeks (n equals 4). The histopathology of laser effects at one day show areas of necrosis with loss of glandular structures and stromal edema. Surrounding this area was a zone of degenerative glandular structures extending up to 17.5 mm (cross sectional diameter). The histopathology of the 8 week laser treated animals demonstrated dilated prostatic urethras with maximum cross- sectional diameter of 23.4 mm (mean equals 18.5 +/- 3.9 mm). This study demonstrates the effectiveness of diode laser energy for prostatic tissue coagulation and eventual sloughing. The results also demonstrate the safety of diode laser energy, with similar tissue response as seen with Nd:YAG laser, for laser prostatectomy.

Comparison of the effects of 665 nm low level diode Laser Hat versus and a combination of 665 nm and 808nm low level diode Laser Scanner of hair growth in androgenic alopecia.

PubMed

Barikbin, Behrooz; Khodamrdi, Zeinab; Kholoosi, Leila; Akhgri, Mohammad Reza; Haj Abbasi, Majid; Hajabbasi, Mojgan; Razzaghi, Zahra; Akbarpour, Samaneh

2017-05-17

This study aimed to evaluate the effectiveness of a combined set of low level diode laser scanner (665 nm and 808nm) on hair growth, and assessment of safety and effectiveness of a new laser scanner on hair growth treatment procedure in androgenic alopecia. 90 patients (18 to 70 years) with androgenic alopecia were randomized into three groups. The first group (n=30) received 655 nm red light using laser hat, the second group (n=30) received 655 nm red laser plus 808 nm infrared laser using a laser scanner of hair growth device (with the patent number: 77733) and the third group (n=30) received no laser as the control group. Patients in laser scanner group had better results and showed a higher increase in terminal hair density compared with laser hat group (mean of 9.61 versus 9.16 per cm 2 ). We found significant decrease in terminal hair density from baseline in control group (mean -1.8 per cm 2 , p<0.0001). Results showed a statistically significant improvement in the laser scanner of the hair growth group compared with laser hat and the control group. The study showed that treatment with new laser devise had a promising result without any observable adverse effects.

Teradiode's high brightness semiconductor lasers

NASA Astrophysics Data System (ADS)

Huang, Robin K.; Chann, Bien; Burgess, James; Lochman, Bryan; Zhou, Wang; Cruz, Mike; Cook, Rob; Dugmore, Dan; Shattuck, Jeff; Tayebati, Parviz

2016-03-01

TeraDiode is manufacturing multi-kW-class ultra-high brightness fiber-coupled direct diode lasers for industrial applications. A fiber-coupled direct diode laser with a power level of 4,680 W from a 100 μm core diameter, <0.08 numerical aperture (NA) output fiber at a single center wavelength was demonstrated. Our TeraBlade industrial platform achieves world-record brightness levels for direct diode lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 3.5 mm-mrad and is the lowest BPP multi-kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 4-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers. We have also demonstrated novel high peak power lasers and high brightness Mid-Infrared Lasers.

Compact and highly efficient laser pump cavity

DOEpatents

Chang, Jim J.; Bass, Isaac L.; Zapata, Luis E.

1999-01-01

A new, compact, side-pumped laser pump cavity design which uses non-conventional optics for injection of laser-diode light into a laser pump chamber includes a plurality of elongated light concentration channels. In one embodiment, the light concentration channels are compound parabolic concentrators (CPC) which have very small exit apertures so that light will not escape from the pumping chamber and will be multiply reflected through the laser rod. This new design effectively traps the pump radiation inside the pump chamber that encloses the laser rod. It enables more uniform laser pumping and highly effective recycle of pump radiation, leading to significantly improved laser performance. This new design also effectively widens the acceptable radiation wavelength of the diodes, resulting in a more reliable laser performance with lower cost.

Semiconductor laser devices having lateral refractive index tailoring

DOEpatents

Ashby, Carol I. H.; Hadley, G. Ronald; Hohimer, John P.; Owyoung, Adelbert

1990-01-01

A broad-area semiconductor laser diode includes an active lasing region interposed between an upper and a lower cladding layer, the laser diode further comprising structure for controllably varying a lateral refractive index profile of the diode to substantially compensate for an effect of junction heating during operation. In embodiments disclosed the controlling structure comprises resistive heating strips or non-radiative linear junctions disposed parallel to the active region. Another embodiment discloses a multi-layered upper cladding region selectively disordered by implanted or diffused dopant impurities. Still another embodiment discloses an upper cladding layer of variable thickness that is convex in shape and symmetrically disposed about a central axis of the active region. The teaching of the invention is also shown to be applicable to arrays of semiconductor laser diodes.

Comparative Morphologic Evaluation and Occluding Effectiveness of Nd: YAG, CO2 and Diode Lasers on Exposed Human Dentinal Tubules: An Invitro SEM Study

PubMed Central

Grover, Harpreet Singh; Choudhary, Pankaj

2016-01-01

Introduction Dentinal hypersensitivity is one of the most common problem, encountered in dental practice but has least predictable treatment outcome. The advent of lasers in dentistry has provided an additional therapeutic option for treating dentinal hypersensitivity. Although various lasers have been tried over a period of time to treat dentinal hypersensitivity, but still the doubt persist as to which laser leads to maximum dentinal tubular occlusion and is most suitable with minimal hazardous effects. Aim To compare the effects of Nd: YAG, CO2 and 810-nm diode lasers on width of exposed dentinal tubule orifices and to evaluate the morphologic changes on dentinal surface of human tooth after laser irradiation by scanning electron microscope (SEM). Materials and Methods Forty root specimens were obtained from ten freshly extracted human premolars, which were randomly divided into four groups of ten each. Group I: control group treated with only saline, Group II: Nd:YAG laser, Group III: CO2 laser and Group IV: 810-nm diode laser. The specimens were examined using SEM. After calculating mean tubular diameter for each group, the values were compared statistically using parametric one-way ANOVA test and Turkey’s post hoc multiple comparison test. Results All the three lased groups showed a highly statistical significant result with p-value of <0.001 as compared to non-lased group. On intergroup comparison within the lased groups, all the three groups showed statistically significant difference in the reduction of dentinal tubular diameter (p-value < 0.001). Conclusion Nd: YAG laser was found to be most effective, followed by the CO2 laser and 810-nm diode laser was found to be least effective. The morphologic changes like craters, cracks and charring effect of the dentine were seen maximum by the use of CO2 laser. PMID:27630957

Comparative Morphologic Evaluation and Occluding Effectiveness of Nd: YAG, CO2 and Diode Lasers on Exposed Human Dentinal Tubules: An Invitro SEM Study.

PubMed

Saluja, Mini; Grover, Harpreet Singh; Choudhary, Pankaj

2016-07-01

Dentinal hypersensitivity is one of the most common problem, encountered in dental practice but has least predictable treatment outcome. The advent of lasers in dentistry has provided an additional therapeutic option for treating dentinal hypersensitivity. Although various lasers have been tried over a period of time to treat dentinal hypersensitivity, but still the doubt persist as to which laser leads to maximum dentinal tubular occlusion and is most suitable with minimal hazardous effects. To compare the effects of Nd: YAG, CO2 and 810-nm diode lasers on width of exposed dentinal tubule orifices and to evaluate the morphologic changes on dentinal surface of human tooth after laser irradiation by scanning electron microscope (SEM). Forty root specimens were obtained from ten freshly extracted human premolars, which were randomly divided into four groups of ten each. Group I: control group treated with only saline, Group II: Nd:YAG laser, Group III: CO2 laser and Group IV: 810-nm diode laser. The specimens were examined using SEM. After calculating mean tubular diameter for each group, the values were compared statistically using parametric one-way ANOVA test and Turkey's post hoc multiple comparison test. All the three lased groups showed a highly statistical significant result with p-value of <0.001 as compared to non-lased group. On intergroup comparison within the lased groups, all the three groups showed statistically significant difference in the reduction of dentinal tubular diameter (p-value < 0.001). Nd: YAG laser was found to be most effective, followed by the CO2 laser and 810-nm diode laser was found to be least effective. The morphologic changes like craters, cracks and charring effect of the dentine were seen maximum by the use of CO2 laser.

Narrow-line, cw orange light generation in a diode-pumped Nd:YVO4 laser using volume Bragg gratings.

PubMed

Chen, Y L; Chen, W W; Du, C E; Chang, W K; Wang, J L; Chung, T Y; Chen, Y H

2009-12-07

We report on the demonstration of a narrow-line, cw orange 593-nm laser achieved via intracavity sum-frequency generation (SFG) of a diode-pumped dual-wavelength (1064 and 1342 nm) Nd:YVO(4) laser using two volume Bragg grating (VBG) reflectors. At diode pump power of up to 3.6 W, the 593-nm intracavity SFG laser radiates at the single longitudinal mode of spectral linewidth as narrow as approximately 15 MHz. More than 23-mW single-longitudinal-mode or 40-mW, <8.5-GHz (10-pm) linewidth (at 4.2-W diode pump power) 593-nm orange lights can be obtained from this compact laser system. Spectral tuning of the orange light was performed via the temperature tuning of the two VBGs in this system, achieving an effective tuning rate of ~5 pm/degrees C.

Qualification and Testing of Quantum Cascade Lasers for Harsh Environments

NASA Astrophysics Data System (ADS)

Brauer, C. S.; Myers, T. L.; Cannon, B. D.; Anderson, C. G.; Crowther, B. G.; Hansen, S.

2014-12-01

Quantum cascade lasers (QCLs) offer the potential for the development of novel, laser-based instruments for both terrestrial and space applications. In order to withstand harsh conditions encountered in these environments, lasers must be robust, and rigorous testing is required before new systems can be utilized. A particular concern for space applications is the potential damage to laser performance caused by radiation exposure. While the effects of radiation exposure in diode lasers have been studied extensively, the effect on QCLs, which are fundamentally different from diode lasers, is not well known. We thus present work to quantify the performance of QCLs after exposure to moderate and high levels of radiation from different sources, including protons and gamma rays, to determine the effects of radiation damage.

The effects of diode laser on Staphylococcus aureus biofilm and Escherichia coli lipopolysaccharide adherent to titanium oxide surface of dental implants. An in vitro study.

PubMed

Giannelli, Marco; Landini, Giulia; Materassi, Fabrizio; Chellini, Flaminia; Antonelli, Alberto; Tani, Alessia; Zecchi-Orlandini, Sandra; Rossolini, Gian Maria; Bani, Daniele

2016-11-01

Effective decontamination of biofilm and bacterial toxins from the surface of dental implants is a yet unresolved issue. This in vitro study aims at providing the experimental basis for possible use of diode laser (λ 808 nm) in the treatment of peri-implantitis. Staphylococcus aureus biofilm was grown for 48 h on titanium discs with porous surface corresponding to the bone-implant interface and then irradiated with a diode laser (λ 808 nm) in noncontact mode with airflow cooling for 1 min using a Ø 600-μm fiber. Setting parameters were 2 W (400 J/cm 2 ) for continuous wave mode; 22 μJ, 20 kHz, 7 μs (88 J/cm 2 ) for pulsed wave mode. Bactericidal effect was evaluated using fluorescence microscopy and counting the residual colony-forming units. Biofilm and titanium surface morphology were analyzed by scanning electron microscopy (SEM). In parallel experiments, the titanium discs were coated with Escherichia coli lipopolysaccharide (LPS), laser-irradiated and seeded with RAW 264.7 macrophages to quantify LPS-driven inflammatory cell activation by measuring the enhanced generation of nitric oxide (NO). Diode laser irradiation in both continuous and pulsed modes induced a statistically significant reduction of viable bacteria and nitrite levels. These results indicate that in addition to its bactericidal effect laser irradiation can also inhibit LPS-induced macrophage activation and thus blunt the inflammatory response. The λ 808-nm diode laser emerges as a valuable tool for decontamination/detoxification of the titanium implant surface and may be used in the treatment of peri-implantitis.

Laser Application in Dentistry: Irradiation Effects of Nd:YAG 1064 nm and Diode 810 nm and 980 nm in Infected Root Canals-A Literature Overview.

PubMed

Saydjari, Yves; Kuypers, Thorsten; Gutknecht, Norbert

2016-01-01

Objective. In endodontics, Nd:YAG laser (1064 nm) and diode laser (810 nm and 980 nm) devices are used to remove bacteria in infected teeth. A literature review was elaborated to compare and evaluate the advantages and disadvantages of using these lasers. Methods. Using combined search terms, eligible articles were retrieved from PubMed and printed journals. The initial search yielded 40 titles and 27 articles were assigned to full-text analysis. The studies were classified based upon laser source, laser energy level, duration/similarity of application, and initial and final bacterial count at a minimum of 20 prepared root canals. Part of the analysis was only reduced microorganisms and mechanically treated root canals upon preparation size of ISO 30. All studies were compared to evaluate the most favorable laser device for best results in endodontic therapy. Results. A total of 22 eligible studies were found regarding Nd:YAG laser 1064 nm. Four studies fulfilled all demanded criteria. Seven studies referring to the diode laser 980 nm were examined, although only one fulfilled all criteria. Eleven studies were found regarding the diode laser 810 nm, although only one study fulfilled all necessary criteria. Conclusions. Laser therapy is effective in endodontics, although a comparison of efficiency between the laser devices is not possible at present due to different study designs, materials, and equipment.

Laser Application in Dentistry: Irradiation Effects of Nd:YAG 1064 nm and Diode 810 nm and 980 nm in Infected Root Canals—A Literature Overview

PubMed Central

Kuypers, Thorsten; Gutknecht, Norbert

2016-01-01

Objective. In endodontics, Nd:YAG laser (1064 nm) and diode laser (810 nm and 980 nm) devices are used to remove bacteria in infected teeth. A literature review was elaborated to compare and evaluate the advantages and disadvantages of using these lasers. Methods. Using combined search terms, eligible articles were retrieved from PubMed and printed journals. The initial search yielded 40 titles and 27 articles were assigned to full-text analysis. The studies were classified based upon laser source, laser energy level, duration/similarity of application, and initial and final bacterial count at a minimum of 20 prepared root canals. Part of the analysis was only reduced microorganisms and mechanically treated root canals upon preparation size of ISO 30. All studies were compared to evaluate the most favorable laser device for best results in endodontic therapy. Results. A total of 22 eligible studies were found regarding Nd:YAG laser 1064 nm. Four studies fulfilled all demanded criteria. Seven studies referring to the diode laser 980 nm were examined, although only one fulfilled all criteria. Eleven studies were found regarding the diode laser 810 nm, although only one study fulfilled all necessary criteria. Conclusions. Laser therapy is effective in endodontics, although a comparison of efficiency between the laser devices is not possible at present due to different study designs, materials, and equipment. PMID:27462611

Effects of blue diode laser (445 nm) and LED (430-480 nm) radiant heat treatments on dental glass ionomer restoratives

NASA Astrophysics Data System (ADS)

Dionysopoulos, Dimitrios; Tolidis, Kosmas; Strakas, Dimitrios; Gerasimou, Paris; Sfeikos, Thrasyvoulos; Gutknecht, Norbert

2018-02-01

The purpose of this in vitro study was to evaluate the effect of two radiant heat treatments on water sorption, solubility and surface roughness of three conventional glass ionomer cements by using a blue diode laser (445 nm) and a light emitting diode (LED) unit (430-480 nm). Thirty disk-shaped specimens were prepared for each tested GIC (Equia Fil, Ketac Universal Aplicap and Riva Self Cure). The experimental groups (n = 10) of the study were as follows: Group 1 was the control group, in Group 2 the specimens were irradiated for 60 s at the top surface using a LED light-curing unit and in Group 3 the specimens were irradiated for 60 s at the top surface using a blue light diode laser. Statistical analysis was performed using one-way ANOVA and Tukey post hoc tests at a level of significance of a = 0.05. Radiant heat treatments with both laser and LED devices significantly decreased water sorption and solubility (p < 0.05) of most of the tested GICs. Blue diode laser treatment was seemed to be more effective compared to LED treatment for some of the tested materials. There were no changes in surface roughness of the GICs after the treatments (p > 0.05). Among the tested materials there were differences in water sorption and solubility (p < 0.05) but not in surface roughness (p > 0.05). The use of the blue diode laser for this radiant heat treatment was harmless for the surface of the tested GICs and may be advantageous for the longevity of their restorations.

Environmental testing of a diode-laser-pumped Nd:YAG laser and a set of diode-laser-arrays

NASA Technical Reports Server (NTRS)

Hemmati, H.; Lesh, J. R.

1989-01-01

Results of the environmental test of a compact, rigid and lightweight diode-laser-pumped Nd:YAG laser module are discussed. All optical elements are bonded onto the module using space applicable epoxy, and two 200 mW diode laser arrays for pump sources are used to achieve 126 mW of CW output with about 7 percent electrical-to-optical conversion efficiency. This laser assembly and a set of 20 semiconductor diode laser arrays were environmentally tested by being subjected to vibrational and thermal conditions similar to those experienced during launch of the Space Shuttle, and both performed well. Nevertheless, some damage to the laser front facet in diode lasers was observed. Significant degradation was observed only on lasers which performed poorly in the life test. Improvements in the reliability of the Nd:YAG laser are suggested.

Long-term efficacy of linear-scanning 808 nm diode laser for hair removal compared to a scanned alexandrite laser.

PubMed

Grunewald, Sonja; Bodendorf, Marc Oliver; Zygouris, Alexander; Simon, Jan Christoph; Paasch, Uwe

2014-01-01

Alexandrite and diode lasers are commonly used for hair removal. To date, the available spot sizes and repetition rates are defining factors in terms of penetration depth, treatment speed, and efficacy. Still, larger treatment areas and faster systems are desirable. To compare the efficacy, tolerability, and subject satisfaction of a continuously linear-scanning 808 nm diode laser with an alexandrite 755 nm laser for axillary hair removal. A total of 31 adults with skin types I-IV received 6 treatments at 4-week intervals with a 755 nm alexandrite laser (right axilla) and a continuously linear-scanning 808 nm diode laser (left axilla). Axillary hair density was assessed using a computerized hair detection system. There was a significant reduction in axillary hair after the 6th treatment (P < 0.05) on both sides (left, 808 nm: hair clearance of 72.16%; right, 755 nm: hair clearance of 71.30%). The difference in reduction between the two lasers was not significant, but both were persistant at 18 months follow-up (left: hair clearance of 73.71%; right: hair clearance of 71.90%). Erythema and perifollicular edema were more common after alexandrite laser treatment, but all side effects were transient. While 62.50% of patients reported more pain in response to treatment with the new diode laser, all patients rated treatment with either laser tolerable. Treatment with either the alexandrite or the linear-scanning diode laser results in significant, comparable, persistent (at least 18 months) axillary hair reduction among individuals with skin types I-IV. © 2013 Wiley Periodicals, Inc.

Effects of high-frequency near-infrared diode laser irradiation on the proliferation and migration of mouse calvarial osteoblasts.

PubMed

Kunimatsu, Ryo; Gunji, Hidemi; Tsuka, Yuji; Yoshimi, Yuki; Awada, Tetsuya; Sumi, Keisuke; Nakajima, Kengo; Kimura, Aya; Hiraki, Tomoka; Abe, Takaharu; Naoto, Hirose; Yanoshita, Makoto; Tanimoto, Kotaro

2018-07-01

Laser irradiation activates a range of cellular processes and can promote tissue repair. Here, we examined the effects of high-frequency near-infrared (NIR) diode laser irradiation on the proliferation and migration of mouse calvarial osteoblastic cells (MC3T3-E1). MC3T3-E1 cells were cultured and exposed to high-frequency (30 kHz) 910-nm diode laser irradiation at a dose of 0, 1.42, 2.85, 5.7, or 17.1 J/cm 2 . Cell proliferation was evaluated with BrdU and ATP concentration assays. Cell migration was analyzed by quantitative assessment of wound healing using the Incucyt ® ZOOM system. In addition, phosphorylation of mitogen-activated protein kinase (MAPK) family members including p38 mitogen-activated protein kinase (p38), stress-activated protein kinase/Jun-amino-terminal kinase (SAPK/JNK), and extracellular signal-regulated protein kinase (ERK)1/2) after laser irradiation was examined with western blotting. Compared to the control, cell proliferation was significantly increased by laser irradiation at a dose of 2.85, 5.7, or 17.1 J/cm 2 . Laser irradiation at a dose of 2.85 J/cm 2 induced MC3T3-E1 cells to migrate more rapidly than non-irradiated control cells. Irradiation with the high-frequency 910-nm diode laser at a dose of 2.85 J/cm 2 induced phosphorylation of MAPK/ERK1/2 15 and 30 min later. However, phosphorylation of p38 MAPK and SAPK/JNK was not changed by NIR diode laser irradiation at a dose of 2.85 J/cm 2 . Irradiation with a high-frequency NIR diode laser increased cell division and migration of MT3T3-E1 cells, possibly via MAPK/ERK signaling. These observations may be important for enhancing proliferation and migration of osteoblasts to improve regeneration of bone tissues.

Monolithic microchannel heatsink

DOEpatents

Benett, W.J.; Beach, R.J.; Ciarlo, D.R.

1996-08-20

A silicon wafer has slots sawn in it that allow diode laser bars to be mounted in contact with the silicon. Microchannels are etched into the back of the wafer to provide cooling of the diode bars. To facilitate getting the channels close to the diode bars, the channels are rotated from an angle perpendicular to the diode bars which allows increased penetration between the mounted diode bars. This invention enables the fabrication of monolithic silicon microchannel heatsinks for laser diodes. The heatsinks have low thermal resistance because of the close proximity of the microchannels to the laser diode being cooled. This allows high average power operation of two-dimensional laser diode arrays that have a high density of laser diode bars and therefore high optical power density. 9 figs.

Monolithic microchannel heatsink

DOEpatents

Benett, William J.; Beach, Raymond J.; Ciarlo, Dino R.

1996-01-01

A silicon wafer has slots sawn in it that allow diode laser bars to be mounted in contact with the silicon. Microchannels are etched into the back of the wafer to provide cooling of the diode bars. To facilitate getting the channels close to the diode bars, the channels are rotated from an angle perpendicular to the diode bars which allows increased penetration between the mounted diode bars. This invention enables the fabrication of monolithic silicon microchannel heatsinks for laser diodes. The heatsinks have low thermal resistance because of the close proximity of the microchannels to the laser diode being cooled. This allows high average power operation of two-dimensional laser diode arrays that have a high density of laser diode bars and therefore high optical power density.

Fragmentation of salivary stones with a 980nm diode laser.

PubMed

Luers, Jan Christoffer; Petry-Schmelzer, Jan Niklas; Hein, Wolfgang G; Gostian, Antoniu-Oreste; Hüttenbrink, Karl-Bernd; Beutner, Dirk

2014-02-01

Intraductal laser lithotripsy is a preferred method to fragment large, immobile intraglandular salivary stones. A number of different laser systems has been investigated for this purpose. It was our aim to study the effectiveness of a 980nm diode laser when fragmenting salivary stones in an experimental set up. In an experimental set up we used a 980nm diode laser for the lithotripsy of 9 salivary stones. The temperature circle around the laser fibre tip was measured and stone remnants were chemically analysed for their composition. The salivary stones had a mean diameter of 6.7mm×5.6mm×3.0mm. Laser fragmentation with the diode laser was successful at all stones. The temperature next to the salivary stone increased to around 30°C during the active lithotripsy with continuous rinsing (fluid temperature 21°C). At a distance of 2mm the temperature around the laser fibre's tip is reduced by already about 50%. The salivary stones mainly consisted of carbonate apatite, followed by β-calcium phosphate and other calcium phosphates. The fragmentation of salivary stones with a 980nm diode laser is possible in principle. Under a continuous irrigation with a positioning of the laser fibre's tip at the centre of the stone, no relevant temperature increase in the vicinity of the stone occurs. However, before the laser is used in humans, in vivo experiments on animal material seem to be advisable. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Diode Laser Assisted Excision and Low Level Laser Therapy in the Management of Mucus Extravasation Cysts: A Case Series

PubMed Central

Ahad, Abdul; Tandon, Shruti; Lamba, Arundeep Kaur; Faraz, Farrukh; Anand, Parimal; Aleem, Abdul

2017-01-01

Introduction: Mucus extravasation cyst is a commonly occurring lesion in oral cavity that may result from traumatic severance of a salivary gland duct with subsequent extravasation of mucus into fibrous connective tissue. After a conventional excision or marsupialization, recurrence is not uncommon. Diode laser offers an effective modality for management of such lesions. Case Reports: Four patients were referred with painless fluctuant swellings on labial and buccal mucosa. After recording history and clinical examination, provisional diagnosis of mucocele was made. All the lesions were excised with a diode laser and biopsy was performed. Surgical wounds were treated with low-level laser therapy (LLLT). Results: Uneventful healing was observed in all 4 cases. Significant reduction in postoperative discomfort was recorded after application of LLLT. Histopathological findings were suggestive of mucus extravasation cysts. Conclusion: Diode laser appears to be a good alternative to conventional modalities for the management of mucus extravasation cysts. PMID:29123637

Diode Laser Assisted Excision and Low Level Laser Therapy in the Management of Mucus Extravasation Cysts: A Case Series.

PubMed

Ahad, Abdul; Tandon, Shruti; Lamba, Arundeep Kaur; Faraz, Farrukh; Anand, Parimal; Aleem, Abdul

2017-01-01

Introduction: Mucus extravasation cyst is a commonly occurring lesion in oral cavity that may result from traumatic severance of a salivary gland duct with subsequent extravasation of mucus into fibrous connective tissue. After a conventional excision or marsupialization, recurrence is not uncommon. Diode laser offers an effective modality for management of such lesions. Case Reports: Four patients were referred with painless fluctuant swellings on labial and buccal mucosa. After recording history and clinical examination, provisional diagnosis of mucocele was made. All the lesions were excised with a diode laser and biopsy was performed. Surgical wounds were treated with low-level laser therapy (LLLT). Results: Uneventful healing was observed in all 4 cases. Significant reduction in postoperative discomfort was recorded after application of LLLT. Histopathological findings were suggestive of mucus extravasation cysts. Conclusion: Diode laser appears to be a good alternative to conventional modalities for the management of mucus extravasation cysts.

Endoscopic diode laser therapy for chronic radiation proctitis.

PubMed

Polese, Lino; Marini, Lucia; Rizzato, Roberto; Picardi, Edgardo; Merigliano, Stefano

2018-01-01

The purpose of this study is to determine the effectiveness of endoscopic diode laser therapy in patients presenting rectal bleeding due to chronic radiation proctitis (CRP). A retrospective analysis of CRP patients who underwent diode laser therapy in a single institution between 2010 and 2016 was carried out. The patients were treated by non-contact fibers without sedation in an outpatient setting. Fourteen patients (median age 77, range 73-87 years) diagnosed with CRP who had undergone high-dose radiotherapy for prostatic cancer and who presented with rectal bleeding were included. Six required blood transfusions. Antiplatelet (three patients) and anticoagulant (two patients) therapy was not suspended during the treatments. The patients underwent a median of two sessions; overall, a mean of 1684 J of laser energy per session was used. Bleeding was resolved in 10/14 (71%) patients, and other two patients showed improvement (93%). Only one patient, who did not complete the treatment, required blood transfusions after laser therapy; no complications were noted during or after the procedures. Study findings demonstrated that endoscopic non-contact diode laser treatment is safe and effective in CRP patients, even in those receiving antiplatelet and/or anticoagulant therapy.

Venous Lake of the Lips Treated Using Photocoagulation with High-Intensity Diode Laser

PubMed Central

Galletta, Vivian C.; de Paula Eduardo, Carlos; Migliari, Dante A.

2010-01-01

Abstract Objective: To evaluate the effectiveness of photocoagulation with high-intensity diode laser in the treatment of venous lake (VL) lesions. Background Data: VL is a common vascular lesion characterized by elevated, usually dome-shaped papules, ranging in color from dark blue to dark purple, seen more frequently in elderly patients. They often occur as single lesions on the ears, face, lips, or neck. Once formed, lesions persist throughout life. Although these lesions are usually asymptomatic, they can bleed if injured. Methods: Seventeen patients (7 men and 10 women) with VL on the lip were treated using a noncontact diode laser (wavelength 808 nm, power output 2–3 W in continuous wave). Results: After only one irradiation exposure, all lesions were successfully treated. Healing was completed in approximately 2 to 3 weeks, and none of the patients experienced complications. Postoperative discomfort and scarring were not present or were minimal. Conclusion: Photocoagulation with high-intensity diode laser is an effective, bloodless procedure for the treatment of VL. PMID:19811083

Pump Diode Characterization for an Unstable Diode-Pumped Alkali Laser Resonator

DTIC Science & Technology

2013-03-01

2003. Petersen, A., and R. Lane, Second harmonic operation of diode-pumped Rb vapor lasers , Proc. of SPIE, 7005, 2008. Siegman , A. E., Lasers ...University Science Books, Sausalito, CA, 1986. Siegman , A. E., Defining, measuring and optimizing laser beam quality, Proc. of SPIE, 1868, 1993. Steck, D...PUMP DIODE CHARACTERIZATION FOR AN UNSTABLE DIODE-PUMPED ALKALI LASER RESONATOR THESIS Chad T. Taguba, Master Sergeant, USAF AFIT-ENP-13-M-33

Rectified diode response of a multimode quantum cascade laser integrated terahertz transceiver.

PubMed

Dyer, Gregory C; Norquist, Christopher D; Cich, Michael J; Grine, Albert D; Fuller, Charles T; Reno, John L; Wanke, Michael C

2013-02-25

We characterized the DC transport response of a diode embedded in a THz quantum cascade laser as the laser current was changed. The overall response is described by parallel contributions from the rectification of the laser field due to the non-linearity of the diode I-V and from thermally activated transport. Sudden jumps in the diode response when the laser changes from single mode to multi-mode operation, with no corresponding jumps in output power, suggest that the coupling between the diode and laser field depends on the spatial distribution of internal fields. The results demonstrate conclusively that the internal laser field couples directly to the integrated diode.

Laser diode package with enhanced cooling

DOEpatents

Deri, Robert J [Pleasanton, CA; Kotovsky, Jack [Oakland, CA; Spadaccini, Christopher M [Oakland, CA

2011-09-13

A laser diode package assembly includes a reservoir filled with a fusible metal in close proximity to a laser diode. The fusible metal absorbs heat from the laser diode and undergoes a phase change from solid to liquid during the operation of the laser. The metal absorbs heat during the phase transition. Once the laser diode is turned off, the liquid metal cools off and resolidifies. The reservoir is designed such that that the liquid metal does not leave the reservoir even when in liquid state. The laser diode assembly further includes a lid with one or more fin structures that extend into the reservoir and are in contact with the metal in the reservoir.

Laser diode package with enhanced cooling

DOEpatents

Deri, Robert J [Pleasanton, CA; Kotovsky, Jack [Oakland, CA; Spadaccini, Christopher M [Oakland, CA

2012-06-12

A laser diode package assembly includes a reservoir filled with a fusible metal in close proximity to a laser diode. The fusible metal absorbs heat from the laser diode and undergoes a phase change from solid to liquid during the operation of the laser. The metal absorbs heat during the phase transition. Once the laser diode is turned off, the liquid metal cools off and resolidifies. The reservoir is designed such that that the liquid metal does not leave the reservoir even when in liquid state. The laser diode assembly further includes a lid with one or more fin structures that extend into the reservoir and are in contact with the metal in the reservoir.

Laser diode package with enhanced cooling

DOEpatents

Deri, Robert J; Kotovsky, Jack; Spadaccini, Christopher M

2012-06-26

A laser diode package assembly includes a reservoir filled with a fusible metal in close proximity to a laser diode. The fusible metal absorbs heat from the laser diode and undergoes a phase change from solid to liquid during the operation of the laser. The metal absorbs heat during the phase transition. Once the laser diode is turned off, the liquid metal cools off and resolidifies. The reservoir is designed such that that the liquid metal does not leave the reservoir even when in liquid state. The laser diode assembly further includes a lid with one or more fin structures that extend into the reservoir and are in contact with the metal in the reservoir.

Highly-reliable laser diodes and modules for spaceborne applications

NASA Astrophysics Data System (ADS)

Deichsel, E.

2017-11-01

Laser applications become more and more interesting in contemporary missions such as earth observations or optical communication in space. One of these applications is light detection and ranging (LIDAR), which comprises huge scientific potential in future missions. The Nd:YAG solid-state laser of such a LIDAR system is optically pumped using 808nm emitting pump sources based on semiconductor laser-diodes in quasi-continuous wave (qcw) operation. Therefore reliable and efficient laser diodes with increased output powers are an important requirement for a spaceborne LIDAR-system. In the past, many tests were performed regarding the performance and life-time of such laser-diodes. There were also studies for spaceborne applications, but a test with long operation times at high powers and statistical relevance is pending. Other applications, such as science packages (e.g. Raman-spectroscopy) on planetary rovers require also reliable high-power light sources. Typically fiber-coupled laser diode modules are used for such applications. Besides high reliability and life-time, designs compatible to the harsh environmental conditions must be taken in account. Mechanical loads, such as shock or strong vibration are expected due to take-off or landing procedures. Many temperature cycles with high change rates and differences must be taken in account due to sun-shadow effects in planetary orbits. Cosmic radiation has strong impact on optical components and must also be taken in account. Last, a hermetic sealing must be considered, since vacuum can have disadvantageous effects on optoelectronics components.

Effect of diode laser and ultrasonics with and without ethylenediaminetetraacetic acid on smear layer removal from the root canals: A scanning electron microscope study.

PubMed

Amin, Khalid; Masoodi, Ajaz; Nabi, Shahnaz; Ahmad, Parvaiz; Farooq, Riyaz; Purra, Aamir Rashid; Ahangar, Fayaz Ahmad

2016-01-01

To evaluate the effect of diode laser and ultrasonics with and without ethylenediaminetetraacetic acid (EDTA) on the smear layer removal from root canals. A total of 120 mandibular premolars were decoronated to working the length of 12 mm and prepared with protaper rotary files up to size F3. Group A canals irrigated with 1 ml of 3% sodium hypochlorite (NaOCl) followed by 3 ml of 3% NaOCl. Group B canals irrigated with 1 ml of 17% EDTA followed by 3 ml of 3% NaOCl. Group C canals lased with a diode laser. Group D canals were initially irrigated with 0.8 ml of 17% EDTA the remaining 0.2 ml was used to fill the root canals, and diode laser application was done. Group E canals were irrigated with 1 ml distilled water with passive ultrasonic activation, followed by 3 ml of 3% NaOCl. Group F canals were irrigated with 1 ml EDTA with passive ultrasonic activation, followed by 3 ml of 3% NaOCl. Scanning electron microscope examination of canals was done for remaining smear layer at coronal middle and apical third levels. Ultrasonics with EDTA had the least smear layer scores. Diode laser alone performed significantly better than ultrasonics.

Surgical effects on soft tissue produced by a 405-nm violet diode laser in vivo

NASA Astrophysics Data System (ADS)

Miyazaki, H.; Kato, J.; Kawai, S.; Hatayama, H.; Uchida, K.; Otsuki, M.; Tagami, J.; Yokoo, S.

2011-12-01

This study evaluated the surgical performance of a 405-nm diode laser in vivo, using living rat liver tissue. Tissue was incised by irradiation with the laser at low output power ranging from 1 W (722 W/cm2) to 3 W (2165 W/cm2) on a manual control at a rate of 1 mm/s. As a control, incisions using a stainless scalpel were compared. Immediately after operation, the surface of the incisions was macroscopically observed and histopathologically evaluated by microscopy. Laser-ablated liver tissue was smooth with observable signs of remnant carbonization and easily acquired hemostasis. The thickness of the denatured layer increased in proportion to the output power; the coagulation layer did not thicken accordingly. Bleeding could not be stopped for tissues incised with the stainless scalpel. The 405-nm diode laser thus proved to be effective for ablating soft tissue with high hemostatic ability at low power.

Complete indium-free CW 200W passively cooled high power diode laser array using double-side cooling technology

NASA Astrophysics Data System (ADS)

Wang, Jingwei; Zhu, Pengfei; Liu, Hui; Liang, Xuejie; Wu, Dihai; Liu, Yalong; Yu, Dongshan; Zah, Chung-en; Liu, Xingsheng

2017-02-01

High power diode lasers have been widely used in many fields. To meet the requirements of high power and high reliability, passively cooled single bar CS-packaged diode lasers must be robust to withstand thermal fatigue and operate long lifetime. In this work, a novel complete indium-free double-side cooling technology has been applied to package passively cooled high power diode lasers. Thermal behavior of hard solder CS-package diode lasers with different packaging structures was simulated and analyzed. Based on these results, the device structure and packaging process of double-side cooled CS-packaged diode lasers were optimized. A series of CW 200W 940nm high power diode lasers were developed and fabricated using hard solder bonding technology. The performance of the CW 200W 940nm high power diode lasers, such as output power, spectrum, thermal resistance, near field, far field, smile, lifetime, etc., is characterized and analyzed.

Extremely high-brightness kW-class fiber coupled diode lasers with wavelength stabilization

NASA Astrophysics Data System (ADS)

Huang, Robin K.; Chann, Bien; Glenn, John D.

2011-06-01

TeraDiode has produced ultra-high brightness fiber-coupled direct diode lasers. A fiber-coupled direct diode laser with a power level of 1,040 W from a 200 μm core diameter, 0.18 numerical aperture (NA) output fiber at a single center wavelength was demonstrated. This was achieved with a novel beam combining and shaping technique using COTS diode lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 18 mm-mrad and is the lowest BPP kW-class direct diode laser yet reported. The laser has been used to demonstrate laser cutting and welding of steel sheet metal up to 6.65 mm thick. Higher brightness fiber-coupled diode lasers, including a module with 418 W of power coupled to a 100 μm, 0.15 NA fiber, have also been demonstrated.

Solitary pulse-on-demand production by optical injection locking of passively Q-switched InGaN diode laser near lasing threshold

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeng, X., E-mail: xi.zeng@csem.ch, E-mail: dmitri.boiko@csem.ch; Stadelmann, T.; Grossmann, S.

2015-02-16

In this letter, we investigate the behavior of a Q-switched InGaN multi-section laser diode (MSLD) under optical injection from a continuous wave external cavity diode laser. We obtain solitary optical pulse generation when the slave MSLD is driven near free running threshold, and the peak output power is significantly enhanced with respect to free running configuration. When the slave laser is driven well above threshold, optical injection reduces the peak power. Using standard semiconductor laser rate equation model, we find that both power enhancement and suppression effects are the result of partial bleaching of the saturable absorber by externally injectedmore » photons.« less

A comparison of diode laser and Er:YAG lasers in the treatment of gingival melanin pigmentation.

PubMed

Simşek Kaya, Göksel; Yapici Yavuz, Günay; Sümbüllü, Muhammed A; Dayi, Ertunç

2012-03-01

This study compared the use of diode and Er:YAG lasers in treating gingival melanin pigmentation (GMP) in terms of gingival depigmentation, local anesthesia requirements, postoperative pain/discomfort, depigmentation effectiveness, and total treatment duration. Twenty patients (13 female, 7 male) referred with GMP were enrolled in the study. Patients were randomly divided into 2 groups. Group 1 was treated with a gallium aluminum arsenide diode laser with a continuous wavelength of 808 nm, and group 2 was treated with an Er:YAG laser with a continuous wavelength of 2,940 nm. Gingival depigmentation was performed by applying the laser at 1 W. Treatment was administered on a weekly basis until a normal pink gingival color was observable in clinical examination and photographs. In addition, patients were asked to evaluate the procedure by using a self-administered questionnaire. Procedures were carried out without the need for any topical or local anesthetic, and no unpleasant events occurred during the actual procedure or the healing period. The total length of treatment was significantly shorter with the diode laser (group 1) than with the Er:YAG laser (group 2; P < .05). No melanin recurrence was detected during any follow-up session. Diode and Er:YAG lasers administered at 1 W both result in satisfactory depigmentation of GMP. Copyright © 2012 Elsevier Inc. All rights reserved.

Effective of diode laser on teeth enamel in the teeth whitening treatment

NASA Astrophysics Data System (ADS)

Klunboot, U.; Arayathanitkul, K.; Chitaree, R.; Emarat, N.

2011-12-01

This research purpose is to investigate the changing of teeth color and to study the surface of teeth after treatment by laser diode at different power densities for tooth whitening treatment. In the experiment, human-extracted teeth samples were divided into 7 groups of 6 teeth each. After that laser diode was irradiated to teeth, which were coated by 38% concentration of hydrogen peroxide, during for 20, 30 and 60 seconds at power densities of 10.9 and 52.1 W/cm2. The results of teeth color change were described by the CIEL*a*b* systems and the damage of teeth surface were investigated by scanning electron microscopy (SEM). The results showed that the power density of the laser diode could affect the whiteness of teeth. The high power density caused more luminous teeth than the low power density did, but on the other hand the high power density also caused damage to the teeth surface. Therefore, the laser diode at the low power densities has high efficiency for tooth whitening treatment and it has a potential for other clinical applications.

Antibacterial Activity of Diode Laser and Sodium Hypochlorite in Enterococcus Faecalis-Contaminated Root Canals.

PubMed

Sohrabi, Khosrow; Sooratgar, Aidin; Zolfagharnasab, Kaveh; Kharazifard, Mohammad Javad; Afkhami, Farzaneh

2016-01-01

The aim of the present in vitro study was to evaluate the disinfection ability of 980-nm diode laser in comparison with sodium hypochlorite (NaOCl) as a common root canal irrigant in canals infected with Enterococcus faecalis (E. faecalis). The root canals of 18 extracted single-rooted premolars were prepared by rotary system. After decoronation, the roots were autoclaved. One specimen was chosen for the negative control, and the remaining teeth were incubated with E. faecalis suspension for two weeks. Subsequently, one specimen was selected as the positive control and the remaining samples were divided into two groups (n=8). The samples of the first group were irrigated with 5.25% NaOCl and the second group were treated with a 980-nm diode laser. Microbial samples were taken from the root canals and bacterial cultivation was carried out. The average value and the standard deviation of colony-forming units (CFU) of each specimen were measured using descriptive statistics. The student's t-test was used to compare the reduction in CFU in each group. The equality of variance of CFU was measured by the Levene's test. NaOCl resulted in 99.87% removal of the bacteria and showed significantly more antibacterial effect compared to the 980-nm diode laser which led to 96.56% bacterial reduction (P<0.05). Although 5.25% NaOCl seems to reduce E. faecalis more effectively, the diode laser also reduced the bacterial count. Therefore a 980-nm diode laser could be considered as a complementary disinfection method in root canal treatment.

Comparative clinical study using laser and LED-therapy for orofacial pain relief: dentin hypersensitivity and cervicogenic headache

NASA Astrophysics Data System (ADS)

Lizarelli, Rosane F. Z.; Pizzo, Renata C. A.; Florez, Fernando L. E.; Grecco, Clovis; Speciali, Jose G.; Bagnato, Vanderlei S.

2015-06-01

Considering several clinical situations, low intensity laser therapy has been widely applied in pain relief or analgesia mechanism. With the advent of new LED-based (light emitting diode) light sources, the need of further clinical experiments aiming to compare the effectiveness among them is paramount. The LED system therapeutic use can be denominated as LEDT - Light Emitting Diode Therapy. This study proposed two clinical evaluations of pain relief effect: to dentin hypersensitivity and to cervicogenic headache using different sources of lasers (low and high intensity) and light emitting diodes (LEDs), one emitting at the spectral band of red (630+/- 5nm) and the other one at infrared band (880+/- 5nm). Two different clinical studies were performed and presented interesting results. Considering dentin hypersensitivity, red and infrared led were so effective than the control group (high intensity laser system); by the other side, considering cervicogenic headache, control group (infrared laser) was the best treatment in comparison to red and infrared led system.

Construction of a Visible Diode Laser Source for Free Radical Photochemistry and Spectroscopy Experiments

NASA Technical Reports Server (NTRS)

Newman, Bronjelyn; Halpern, Joshua B.

1997-01-01

Tunable diode lasers are reliable sources of narrow-band light and comparatively cheap. Optical feedback simplifies frequency tuning of the laser diodes. We are building an inexpensive diode laser system incorporating optical feedback from a diffraction grating. The external optical cavity can be used with lasers that emit between 2 and 100 mW, and will also work if they are pulsed, although this will significantly degrade the bandwidth. The diode laser output power and bandwidth are comparable to CW dye lasers used in kinetics and dynamics experiments. However, their cost and maintenance will be much less as will alignment time. We intend to use the diode lasers to investigate CN and C2 kinetics as well as to study dissociation dynamics of atmospherically important molecules.

Diode laser cyclophotocoagulation: histopathology in two cases of clinical failure.

PubMed

Walland, M J; McKelvie, P A

1998-10-01

Diode laser photocoagulation is an alternative technique to Nd:YAG laser or cryotherapy in cycloablation. It may be more titratable with fewer local side effects. The effect is not, however, always maintained in the long term. The authors wished to establish histologic correlates with in vivo clinical outcomes of failure. Histologic findings in two cases of clinical failure of a single treatment with contact diode laser cyclophotocoagulation are presented. A recurrence of uncontrolled intraocular pressure (IOP) finally led to enucleation of the eyes 5 and 6 months after laser treatment. Histologic examination demonstrated preservation in both specimens of some ciliary processes outside the treatment zone, which was evidently over the pars plana in a case with a relatively low axial length. Persisting damage of treated ciliary processes was seen. Some efforts at ciliary epithelial regeneration were made in these, but in a disorganized and presumably nonfunctional fashion, so that a histologic explanation for the gradual postoperative rise in IOP was not evident. Diode laser cyclophotocoagulation may lower IOP by mechanisms other than destruction of ciliary epithelium. Reversal of a laser-induced increase in uveoscleral outflow may explain the gradual rise in IOP seen postoperatively in these two cases, given the ineffectual secretory epithelial regeneration in one case and the treatment over the pars plana in the other. Methods to enhance probe placement, such as ultrasound biomicroscopy, transillumination, or axial length measurement, may be useful to ensure that treatment is directed to the pars plicata. [Ophthalmic Surg Lasers 1998;29:852-856.] Cyclodestructive procedures have been likened to "duck hunting in the dark (without radar) since the 'shooter' sees neither the target nor the effect of the blast!" Although the use of Nd:YAG and semiconductor diode laser cyclophotocoagulation instead of cyclocryotherapy has progressively refined the caliber of the weapon and its titratability, aim in the placement of the destruction remains inexact. The assumption has generally been, however, that treatment must be directed to ablation of the ciliary epithelium to achieve a hypotensive effect. We present the histopathology from two cases of contact diode laser cyclophotocoagulation (DLCPC), both of which resulted in initially successful intraocular pressure (IOP) control, but which finally required enucleation for problems supervening on a recurrently raised IOP.

Laser-diode-pumped 1319-nm monolithic non-planar ring single-frequency laser

NASA Astrophysics Data System (ADS)

Wang, Qing; Gao, Chunqing; Zhao, Yan; Yang, Suhui; Wei, Guanghui; 2, Dongmei Hong

2003-10-01

Single-frequency 1319-nm laser was obtained by using a laser-diode-pumped monolithic Nd:YAG crystal with a non-planar ring oscillator (NPRO). When the NPRO laser was pumped by an 800-?m fiber coupled laser diode, the output power of the single-frequency 1319-nm laser was 220 mW, and the slope efficiency was 16%. With a 100-1m fiber coupled diode laser pumped, 99-mW single-frequency 1319-nm laser was obtained with a slope efficiency of 29%.

Quasi-CW Laser Diode Bar Life Tests

NASA Technical Reports Server (NTRS)

Stephen, Mark A.; Krainak, Michael A.; Dallas, Joseph L.

1997-01-01

NASA's Goddard Space Flight Center is developing technology for satellite-based, high peak power, LIDAR transmitters requiring 3-5 years of reliable operation. Semi-conductor laser diodes provide high efficiency pumping of solid state lasers with the promise of long-lived, reliable operation. 100-watt quasi- CW laser diode bars have been baselined for the next generation laser altimeters. Multi-billion shot lifetimes are required. The authors have monitored the performance of several diodes for billions of shots and investigated operational modes for improving diode lifetime.

Post-Flight Test Results of Seed Laser Module Subjected to Space Exposure. Paper No. 8876-9

NASA Technical Reports Server (NTRS)

Prasad, Narasimha S.

2013-01-01

The objective of the Materials International Space Station Experiment (MISSE) is to study the performance of novel materials when subjected to the synergistic effects of the harsh space environment for several months. MISSE missions provide an opportunity for developing space qualifiable materials. Several laser and lidar components were sent by NASA Langley Research Center (LaRC) as a part of the MISSE 7 mission. The MISSE 7 module was transported to the international space station (ISS) via STS 129 mission that was launched on Nov 16, 2009. Later, the MISSE 7 module was brought back to the earth via the STS 134 that landed on June 1, 2011. The MISSE 7 module that was subjected to exposure in space environment for more than one and a half year included fiber laser, solid-state laser gain materials, detectors, and semiconductor laser diode. Performance testing of these components is now progressing. In this paper, the results of performance testing of a laser diode module sent by NASA Langley Research Center on MISSE 7 mission will be discussed. This paper will present the comparison of pre-flight and post-flight performance curves and discuss the effect of space exposure on the laser diode module. Preliminary findings on output power measurements show that the COTS laser diode characteristics did not undergo any significant performance degradation.

Effects of continuous wave and fractionated diode laser on human fibroblast cancer and dermal normal cells by zinc phthalocyanine in photodynamic therapy: A comparative study.

PubMed

Navaeipour, Farzaneh; Afsharan, Hadi; Tajalli, Habib; Mollabashi, Mahmood; Ranjbari, Farideh; Montaseri, Azadeh; Rashidi, Mohammad-Reza

2016-08-01

In this experimental study, cancer and normal cells behavior during an in vitro photodynamic therapy (PDT) under exposure of continuous wave (CW) and fractionated mode of laser with different irradiation power and time intervals was compared and investigated. At the first, human fibroblast cancer cell line (SW 872) and human dermal normal (HFFF2) cell line were incubated with different concentrations of zinc phthalocyanine (ZnPc), as a PDT drug. The cells, then, were irradiated with a 675nm diode laser and the cell viability was evaluated using MTT assay. Under optimized conditions, the viability of the cancer cells was eventually reduced to 3.23% and 13.17%, and that of normal cells was decreased to 20.83% and 36.23% using CW and fractionated diode lasers, respectively. In general, the ratio of ZnPc LD50 values for the normal cells to the cancer cells with CW laser was much higher than that of the fractionated laser. Subsequently, cancer cells in comparison with normal ones were found to be more sensitive toward the photodynamic damage induced by ZnPc. In addition, treatment with CW laser was found to be more effective against the cancer cells with a lower toxicity to the normal cells compared with the fractionated diode laser. Copyright © 2016 Elsevier B.V. All rights reserved.

Use of high-power diode lasers for hardening and thermal conduction welding of metals

NASA Astrophysics Data System (ADS)

Klocke, Fritz; Demmer, Axel; Zaboklicki, A.

1997-08-01

CO2 and Nd:YAG high power lasers have become established as machining tools in industrial manufacturing over the last few years. The most important advantages compared to conventional processing techniques lie in the absence of forces introduced by the laser into the workpiece and in the simple arid highly accurate control in terms ofpositioning and timing making the laser a universally applicable, wear-free and extremely flexible tool /1,2/. The laser can be utilised costeffectively in numerous manufacturing processes but there are also further applications for the laser which produce excellent results from a technical point of view, but are not justified in terms of cost. The extensive use of lasers, particularly in small companies and workshops, is hindered by two main reasons: the complexity and size ofthe laser source and plant and the high investment costs /3/. A new generation of lasers, the high power diode lasers (HDL), combines high performance with a compact design, making the laser a cheap and easy to use tool with many applications /3,4,5,6/. In the diode laser, the laser beam is generated by a microelectronic diode which transforms electrical energy directly into laser energy. Diode lasers with low power outputs have, for some time, been making their mark in our everyday lives: they are used in CD players, laser printers and scanners at cash tills. Modern telecommunications would be impossible without these lasers which enable information to be transmitted in the form oflight impulses through optical fibres. They can also be found in compact precision measurement instrumentation - range fmders, interferometers and pollutant analysis devices /3,6/. In the field of material processing, the first applications ofthe laser, such as for soldering, inscribing, surface hardening and plastic or heat conduction welding, will exceed the limits ofthe relatively low performance output currently available. The diode laser has a shorter wavelength than the CO2 and Nd:YAG lasers making it more favourable in terms ofthe absorption behaviour ofthe laser beam - an advantage that will soon have a significant effect on the range of its applications.

INITIAL EXPERIENCE WITH TRANSPUPILLARY DIODE LASER PHOTOCOAGULATION FOR RETINAL DISEASES.

PubMed

Uhumwangho, O M; Iyiriaro, Iao

2014-01-01

Lasers are an invaluable treatment modality for the management of some retinovascular diseases. One of these lasers is the diode laser which is easy to procure and maintain. To review the outcomes of diode laser photocoagulation in patients with a variety of retinal conditions. A retrospective case series of all patients who had retinal laser photocoagulation between July 2012 and June 2014 with the semiconductor infrared diode laser was performed. Demographic and clinical data collected included age, sex, eye involved, visual acuity, diagnosis, associated systemic and ocular diseases, intra and post treatment findings, laser treatment parameters and follow up. A total of 22 eyes of 15 patients had diode laser treatment during the period under review comprising 8(53.3%) males and 7(46.7%) females with a mean age at presentation of 53.4±8.9 years. The indications for treatment were proliferative diabetic retinopathy in 18(81.8%) eyes of 11 patients, retinal vein occlusion in 2(9.1%) eyes of 2 patients and retinal breaks with lattice in 2(9.1%) eyes of 2 patients with fellow eye retinal detachment. Visual acuity in eyes with diabetic retinopathy improved in 9(50%) eyes, worsened in 3(16.7%) eyes and was unchanged/ stable in 6(33.3%) eyes. Regression of neovascularization was achieved in 2(100%) eyes with retinal vein occlusion. The retina of the 2(100%) eyes with breaks following retinopexy remained attached during the follow up period. The follow up period ranged from 2 days to 2 years with a mean duration of 13.5±15.8 months. The diode laser is an effective and beneficial treatment modality in the management of proliferative retinopathies and some retinal diseases.

Effect of 830 nm Diode Laser Irradiation of Root Canal on Bond Strength of Metal and Fiber Post.

PubMed

Strefezza, Claudia; Amaral, Marcello Magri; Quinto, José; Gouw-Soares, Sheila Cynthia; Zamataro, Claudia Bianchi; Zezell, Denise Maria

2018-05-16

The correct selections of the cementing agent, the endodontic post material and placement protocol are critical to provide an increased longevity of the teeth that went through endodontic treatment. The irradiation with diode laser before post cementation, can promote an antimicrobial effect. However, there is a lack of information about the effect of 830 nm diode laser on the post bond strength. This study analyzed the effect of dentin root canal irradiation with high-intensity diode laser, at 830 nm, operating in continuous or pulsed mode, on the retention of metal or fiber posts, cemented with self-etching resinous composite (Panavia F) and zinc phosphate cement (ZnPO 4 ). Human roots were irradiated with diode laser (continuous and pulsed mode). The fiber posts were luted with Panavia F and the metal posts with Panavia F or ZnPO 4 cement. Specimens were sectioned into three sections (cervical, middle, and apical). The bond strength was measured by a push-out mechanical analysis. For the statistical analysis, a three-way ANOVA test was applied following a Tukey's pairwise comparison with a significance level of p = 0.05. The irradiated groups presented higher bond strength compared with nonirradiated group (p < 0.05), and the cervical and middle thirds presented higher on bond strength than the apical. The association of metal post and Panavia F presented higher bond strength when irradiated on continuous mode (p < 0.05). Fiber post and Panavia F presented higher bond strength associated to pulsed mode. The mode seems not to make a significant difference. These results corroborate the importance of the post bond to dentin and root canal debris removal to increase the tooth longevity. It was shown that the dentin to post bond strength were enhanced by the diode laser irradiation either on continuous or pulsed modes.

High-brightness tapered laser diodes with photonic crystal structures

NASA Astrophysics Data System (ADS)

Li, Yi; Du, Weichuan; Kun, Zhou; Gao, Songxin; Ma, Yi; Tang, Chun

2018-02-01

Beam quality of tapered laser diodes is limited by higher order lateral mode. On purpose of optimizing the brightness of tapered laser diodes, we developed a novel design of tapered diodes. This devices based on InGaAs/AlGaAs asymmetry epitaxial structure, containing higher order lateral mode filtering schemes especially photonic crystal structures, which fabricated cost effectively by using standard photolithography and dry etch processes. Meanwhile, the effects of photonic crystal structures on mode control are also investigated theoretically by FDBPM (Finite-Difference Beam Propagation Method) calculation. We achieved a CW optical output power of 6.9W at 940nm for a single emitter with 4 mm cavity length. A nearly diffraction limited beam of M2 ≍1.9 @ 0.5W has been demonstrated, and a highest brightness of β =75MW/(cm2 ·sr) was reached.

Comparative study of the bactericidal effects of indocyanine green- and methyl aminolevulinate-based photodynamic therapy on Propionibacterium acnes as a new treatment for acne.

PubMed

Choi, Seung-Hwan; Seo, Jeong-Wan; Kim, Ki-Ho

2018-05-03

Acne vulgaris is one of the most common dermatological problems, and its therapeutic options include topical and systemic retinoids and antibiotics. However, increase in problems associated with acne treatment, such as side-effects from conventional agents and bacterial resistance to antibiotics, has led to greater use of photodynamic therapy. The purpose of this study was to compare the bactericidal effects of indocyanine green- and methyl aminolevulinate-based photodynamic therapy on Propionibacterium acnes. P. acnes were cultured under anaerobic conditions; then they were divided into three groups (control, treated with indocyanine green and treated with methyl aminolevulinate) and illuminated with different lights (630-nm light-emitting diode, 805-nm diode laser and 830-nm light-emitting diode). The bactericidal effects were evaluated by comparing each group's colony-forming units. The cultured P. acnes were killed with an 805-nm diode laser and 830-nm light-emitting diode in the indocyanine green group. No bactericidal effects of methyl aminolevulinate-based photodynamic therapy were identified. The clinical efficacy of indocyanine green-based photodynamic therapy in 21 patients was retrospectively analyzed. The Korean Acne Grading System was used to evaluate treatment efficacy, which was significantly decreased after treatment. The difference in the efficacy of the 805-nm diode laser and 830-nm light-emitting diode was not statistically significant. Although the methyl aminolevulinate-based photodynamic therapy showed no bactericidal effect, the indocyanine green-based photodynamic therapy has bactericidal effect and clinical efficacy. © 2018 Japanese Dermatological Association.

Dynamical regimes and intracavity propagation delay in external cavity semiconductor diode lasers

NASA Astrophysics Data System (ADS)

Jayaprasath, E.; Sivaprakasam, S.

2017-11-01

Intracavity propagation delay, a delay introduced by a semiconductor diode laser, is found to significantly influence synchronization of multiple semiconductor diode lasers, operated either in stable or in chaotic regime. Two diode lasers coupled in unidirectional scheme is considered in this numerical study. A diode laser subjected to an optical feedback, also called an external cavity diode laser, acts as the transmitter laser (TL). A solitary diode laser acts as the receiver laser (RL). The optical output of the TL is coupled to the RL and laser operating parameters are optimized to achieve synchronization in their output intensities. The time-of-flight between the TL and RL introduces an intercavity time delay in the dynamics of RL. In addition to this, an intracavity propagation delay arises as the TL's field propagated within the RL. This intracavity propagation delay is evaluated by cross-correlation analysis between the output intensities of the lasers. The intracavity propagation delay is found to increase as the external cavity feedback rate of TL is increased, while an increment in the injection rate between the two lasers resulted in a reduction of intracavity propagation delay.

1047 nm laser diode master oscillator Nd:YLF power amplifier laser system

NASA Technical Reports Server (NTRS)

Yu, A. W.; Krainak, M. A.; Unger, G. L.

1993-01-01

A master oscillator power amplifier (MOPA) laser transmitter system at 1047 nm wavelength using a semiconductor laser diode and a diode pumped solid state (Nd:YLF) laser (DPSSL) amplifier is described. A small signal gain of 23 dB, a near diffraction limited beam, 1 Gbit/s modulation rates and greater than 0.6 W average power are achieved. This MOPA laser has the advantage of amplifying the modulation signal from the laser diode master oscillator (MO) with no signal degradation.

Micropulsed diode laser therapy: evolution and clinical applications.

PubMed

Sivaprasad, Sobha; Elagouz, Mohammed; McHugh, Dominic; Shona, Olajumoke; Dorin, Giorgio

2010-01-01

Many clinical trials have demonstrated the clinical efficacy of laser photocoagulation in the treatment of retinal vascular diseases, including diabetic retinopathy. There is, however, collateral iatrogenic retinal damage and functional loss after conventional laser treatment. Such side effects may occur even when the treatment is appropriately performed because of morphological damage caused by the visible endpoint, typically a whitening burn. The development of the diode laser with micropulsed emission has allowed subthreshold therapy without a visible burn endpoint. This greatly reduces the risk of structural and functional retinal damage, while retaining the therapeutic efficacy of conventional laser treatment. Studies using subthreshold micropulse laser protocols have reported successful outcomes for diabetic macular edema, central serous chorioretinopathy, macular edema secondary to retinal vein occlusion, and primary open angle glaucoma. The report includes the rationale and basic principles underlying micropulse diode laser therapy, together with a review of its current clinical applications. Copyright © 2010 Elsevier Inc. All rights reserved.

Continuous-wave laser operation at 743 and 753 nm based on a diode-pumped c-cut Pr:YAlO3 crystal

NASA Astrophysics Data System (ADS)

Lin, Xiuji; Huang, Xiaoxu; Liu, Bin; Xu, Bin; Xu, Huiying; Cai, Zhiping; Xu, Xiaodong; Li, Dongzhen; Liu, Jian; Xu, Jun

2018-02-01

We report on blue-diode-pumped continuous-wave Pr:YAlO3 (YAP) crystal lasers. Using a b-cut sample, a maximum output power of 181 mW is achieved at ∼747 nm with slope efficiency of 12.7% with respect to the absorbed power. Using a c-cut sample, a dual-wavelength laser at ∼743 and ∼753 nm is obtained with a total maximum output power of 72 mW by using the blue diode pumping, for the first time to our knowledge. These laser emissions are all linearly polarized and M2 factors of these output laser beams are also measured. YAP is experimentally verified to be one of effective oxide hosts for Pr-doped visible laser operation besides its fluoride counterparts.

980-nm, 15-W cw laser diodes on F-mount-type heat sinks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bezotosnyi, V V; Krokhin, O N; Oleshchenko, V A

2015-12-31

We have studied the key optical emission parameters of laser diodes (emission wavelength, 980 nm; stripe contact width, 95 μm) mounted directly on F- and C-mount-type copper heat sinks, without intermediate elements (submounts). When effectively cooled by a thermoelectric microcooler, the lasers on the F-mount operated stably at output powers up to 20 W. The lasers were tested for reliable operation at an output power of 15 W for 100 h, and no decrease in output power was detected to within measurement accuracy. The experimentally determined maximum total efficiency is 71.7% and the efficiency at a nominal output power ofmore » 15 W is 61%. We compare parameters of the laser diodes mounted on C- and F-mounts and discuss the advantages of the F-mounts. (lasers)« less

Diode laser application in soft tissue oral surgery.

PubMed

Azma, Ehsan; Safavi, Nassimeh

2013-01-01

Diode laser with wavelengths ranging from 810 to 980 nm in a continuous or pulsed mode was used as a possible instrument for soft tissue surgery in the oral cavity. Diode laser is one of laser systems in which photons are produced by electric current with wavelengths of 810, 940 and 980nm. The application of diode laser in soft tissue oral surgery has been evaluated from a safety point of view, for facial pigmentation and vascular lesions and in oral surgery excision; for example frenectomy, epulis fissuratum and fibroma. The advantages of laser application are that it provides relatively bloodless surgical and post surgical courses with minimal swelling and scarring. We used diode laser for excisional biopsy of pyogenic granuloma and gingival pigmentation. The diode laser can be used as a modality for oral soft tissue surgery.

Diode Laser Application in Soft Tissue Oral Surgery

PubMed Central

Azma, Ehsan; Safavi, Nassimeh

2013-01-01

Introduction: Diode laser with wavelengths ranging from 810 to 980 nm in a continuous or pulsed mode was used as a possible instrument for soft tissue surgery in the oral cavity. Discussion: Diode laser is one of laser systems in which photons are produced by electric current with wavelengths of 810, 940 and 980nm. The application of diode laser in soft tissue oral surgery has been evaluated from a safety point of view, for facial pigmentation and vascular lesions and in oral surgery excision; for example frenectomy, epulis fissuratum and fibroma. The advantages of laser application are that it provides relatively bloodless surgical and post surgical courses with minimal swelling and scarring. We used diode laser for excisional biopsy of pyogenic granuloma and gingival pigmentation. Conclusion: The diode laser can be used as a modality for oral soft tissue surgery PMID:25606331

Improving Reliability of High Power Quasi-CW Laser Diode Arrays for Pumping Solid State Lasers

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Baggott, Renee S.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.

2005-01-01

Most Lidar applications rely on moderate to high power solid state lasers to generate the required transmitted pulses. However, the reliability of solid state lasers, which can operate autonomously over long periods, is constrained by their laser diode pump arrays. Thermal cycling of the active regions is considered the primary reason for rapid degradation of the quasi-CW high power laser diode arrays, and the excessive temperature rise is the leading suspect in premature failure. The thermal issues of laser diode arrays are even more drastic for 2-micron solid state lasers which require considerably longer pump pulses compared to the more commonly used pump arrays for 1-micron lasers. This paper describes several advanced packaging techniques being employed for more efficient heat removal from the active regions of the laser diode bars. Experimental results for several high power laser diode array devices will be reported and their performance when operated at long pulsewidths of about 1msec will be described.

High-power direct diode laser output by spectral beam combining

NASA Astrophysics Data System (ADS)

Tan, Hao; Meng, Huicheng; Ruan, Xu; Du, Weichuan; Wang, Zhao

2018-03-01

We demonstrate a spectral beam combining scheme based on multiple mini-bar stacks, which have more diode laser combining elements, to increase the combined diode laser power and realize equal beam quality in both the fast and slow axes. A spectral beam combining diode laser output of 1130 W is achieved with an operating current of 75 A. When a 9.6 X de-magnifying telescope is introduced between the output mirror and the diffraction grating, to restrain cross-talk among diode laser emitters, a 710 W spectral beam combining diode laser output is achieved at the operating current of 70 A, and the beam quality on the fast and slow axes of the combined beam is about 7.5 mm mrad and 7.3 mm mrad respectively. The power reduction is caused by the existence of a couple resonator between the rear facet of the diode laser and the fast axis collimation lens, and it should be eliminated by using diode laser chips with higher front facet transmission efficiency and a fast axis collimation lens with lower residual reflectivity.

High-power direct green laser oscillation of 598 mW in Pr(3+)-doped waterproof fluoroaluminate glass fiber excited by two-polarization-combined GaN laser diodes.

PubMed

Nakanishi, Jun; Horiuchi, Yuya; Yamada, Tsuyoshi; Ishii, Osamu; Yamazaki, Masaaki; Yoshida, Minoru; Fujimoto, Yasushi

2011-05-15

We demonstrated a high-power and highly efficient Pr-doped waterproof fluoride glass fiber laser at 522.2 nm excited by two-polarization-combined GaN laser diodes and achieved a subwatt output power of 598 mW and slope efficiency of 43.0%. This system will enable us to make a vivid laser display, a photocoagulation laser for eye surgery, a color confocal scanning laser microscope, and an effective laser for material processing. Direct visible ultrashort pulse generation is also expected. © 2011 Optical Society of America

Diode laser soft-tissue surgery: advancements aimed at consistent cutting, improved clinical outcomes.

PubMed

Romanos, Georgios E

2013-01-01

Laser dentistry and soft-tissue surgery, in particular, have become widely adopted in recent years. Significant cost reductions for dental lasers and the increasing popularity of CADCAM, among other factors, have contributed to a substantial increase in the installed base of dental lasers, especially soft-tissue lasers. New development in soft-tissue surgery, based on the modern understanding of laser-tissue interactions and contact soft-tissue surgery mechanisms, will bring a higher quality and consistency level to laser soft-tissue surgery. Recently introduced diode-laser technology enables enhanced control of side effects that result from tissue overheating and may improve soft-tissue surgical outcomes.

High-power single spatial mode AlGaAs channeled-substrate-planar semiconductor diode lasers for spaceborne communications

NASA Technical Reports Server (NTRS)

Connolly, J. C.; Carlin, D. B.; Ettenberg, M.

1989-01-01

A high power single spatial mode channeled substrate planar AlGaAs semiconductor diode laser was developed. The emission wavelength was optimized at 860 to 880 nm. The operating characteristics (power current, single spatial mode behavior, far field radiation patterns, and spectral behavior) and results of computer modeling studies on the performance of the laser are discussed. Reliability assessment at high output levels is included. Performance results on a new type of channeled substrate planar diode laser incorporating current blocking layers, grown by metalorganic chemical vapor deposition, to more effectively focus the operational current to the lasing region was demonstrated. The optoelectronic behavior and fabrication procedures for this new diode laser are discussed. The highlights include single spatial mode devices with up to 160 mW output at 8600 A, and quantum efficiencies of 70 percent (1 W/amp) with demonstrated operating lifetimes of 10,000 h at 50 mW.

Integrated RGB laser light module for autostereoscopic outdoor displays

NASA Astrophysics Data System (ADS)

Reitterer, Jörg; Fidler, Franz; Hambeck, Christian; Saint Julien-Wallsee, Ferdinand; Najda, Stephen; Perlin, Piotr; Stanczyk, Szymon; Czernecki, Robert; McDougall, Stewart D.; Meredith, Wyn; Vickers, Garrie; Landles, Kennedy; Schmid, Ulrich

2015-02-01

We have developed highly compact RGB laser light modules to be used as light sources in multi-view autostereoscopic outdoor displays and projection devices. Each light module consists of an AlGaInP red laser diode, a GaInN blue laser diode, a GaInN green laser diode, as well as a common cylindrical microlens. The plano-convex microlens is a so-called "fast axis collimator", which is widely used for collimating light beams emitted from high-power laser diode bars, and has been optimized for polychromatic RGB laser diodes. The three light beams emitted from the red, green, and blue laser diodes are collimated in only one transverse direction, the so-called "fast axis", and in the orthogonal direction, the so-called "slow axis", the beams pass the microlens uncollimated. In the far field of the integrated RGB light module this produces Gaussian beams with a large ellipticity which are required, e.g., for the application in autostereoscopic outdoor displays. For this application only very low optical output powers of a few milliwatts per laser diode are required and therefore we have developed tailored low-power laser diode chips with short cavity lengths of 250 μm for red and 300 μm for blue. Our RGB laser light module including the three laser diode chips, associated monitor photodiodes, the common microlens, as well as the hermetically sealed package has a total volume of only 0.45 cm³, which to our knowledge is the smallest RGB laser light source to date.

Clinical effectiveness of diode laser therapy as an adjunct to non-surgical periodontal treatment: a randomized clinical study.

PubMed

Dukić, Walter; Bago, Ivona; Aurer, Andrej; Roguljić, Marija

2013-08-01

The aim of this randomized clinical study is to evaluate the effect of a 980-nm diode laser as an adjunct to scaling and root planing (SRP) treatment. Thirty-five patients with chronic periodontitis were selected for the split-mouth clinical study. SRP was performed using a sonic device and hand instruments. Quadrants were equally divided between the right and left sides. Teeth were treated with SRP in two control quadrants (control groups [CG]), and the diode laser was used adjunctively with SRP in contralateral quadrants (laser groups [LG]). Diode laser therapy was applied to periodontal pockets on days 1, 3, and 7 after SRP. Baseline data, including approximal plaque index (API), bleeding on probing (BOP), probing depth (PD), and clinical attachment level (CAL), were recorded before the treatment and 6 and 18 weeks after treatment. Changes in PD and CAL were analyzed separately for initially moderate (4 to 6 mm) and deep (7 to 10 mm) pockets. The results were similar for both groups in terms of API, BOP, PD in deep pockets, and CAL. The laser group showed only significant PD gain in moderate pockets during the baseline to 18-week (P <0.05) and 6- to 18- week (P <0.05) periods, whereas no difference was found between LG and CG in the remaining clinical parameters (P >0.05). The present study indicates that, compared to SRP alone, multiple adjunctive applications of a 980-nm diode laser with SRP showed PD improvements only in moderate periodontal pockets (4 to 6 mm).

Method and system for powering and cooling semiconductor lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Telford, Steven J; Ladran, Anthony S

A semiconductor laser system includes a diode laser tile. The diode laser tile includes a mounting fixture having a first side and a second side opposing the first side and an array of semiconductor laser pumps coupled to the first side of the mounting fixture. The semiconductor laser system also includes an electrical pulse generator thermally coupled to the diode bar and a cooling member thermally coupled to the diode bar and the electrical pulse generator.

Free-space laser communication technologies II; Proceedings of the Meeting, Los Angeles, CA, Jan. 15-17, 1990

NASA Technical Reports Server (NTRS)

Begley, David L. (Editor); Seery, Bernard D. (Editor)

1990-01-01

Various papers on free-space laser communication technologies are presented. Individual topics addressed include: optical intersatellite link experiment between the earth station and ETS-VI, the Goddard optical communications program, technologies and techniques for lasercom terminal size, weight, and cost reduction, laser beam acquisition and tracking system for ETS-VI laser communication equipment, analog dividers for acquisition and tracking signal normalization, fine pointing mechanism using multilayered piezoelectric actuator for optical ISL system, analysis of SILEX tracking sensor performance, new telescope concept for space communication, telescope considered as a very high gain antenna, design of compact transceiver optical systems for optical intersatellite links, ultralightweight optics for laser communications, highly sensitive measurement method for stray light and retroreflected light, depolarization effects on free space laser transceiver communication systems, in-orbit measurements of microaccelerations of ESA's communication satellite Olympus, high-performance laser diode transmitter for optical free space communication, diode-pumped Nd:host laser transmitter for intersatellite optical communications, single-frequency diode-pumped laser for free-space communication.

Treatment of burning mouth syndrome with a low-level energy diode laser.

PubMed

Yang, Hui-Wen; Huang, Yu-Feng

2011-02-01

To test the therapeutic efficacy of low-level energy diode laser on burning mouth syndrome. Burning mouth syndrome is characterized by burning and painful sensations in the mouth, especially the tongue, in the absence of significant mucosal abnormalities. Although burning mouth syndrome is relatively common, little is known regarding its etiology and pathophysiology. As a result, no treatment is effective in all patients. Low-level energy diode laser therapy has been used in a variety of chronic and acute pain conditions, including neck, back and myofascial pain, degenerative osteoarthritis, and headache. A total of 17 patients who had been diagnosed with burning mouth syndrome were treated with an 800-nm wavelength diode laser. A straight handpiece was used with an end of 1-cm diameter with the fiber end standing 4 cm away from the end of handpiece. When the laser was applied, the handpiece directly contacted or was immediately above the symptomatic lingual surface. The output used was 3 W, 50 msec intermittent pulsing, and a frequency of 10 Hz, which was equivalent to an average power of 1.5 W/cm(2) (3 W × 0.05 msec × 10 Hz = 1.5 W/cm(2)). Depending on the involved area, laser was applied to a 1-cm(2) area for 70 sec until all involved area was covered. Overall pain and discomfort were analyzed with a 10-cm visual analogue scale. All patients received diode laser therapy between one and seven times. The average pain score before the treatment was 6.7 (ranging from 2.9 to 9.8). The results showed an average reduction in pain of 47.6% (ranging from 9.3% to 91.8%). The burning sensation remained unchanged for up to 12 months. Low-level energy diode laser may be an effective treatment for burning mouth syndrome.

Bactericidal effect of the 908 nm diode laser on Enterococcus faecalis in infected root canals

PubMed Central

Preethee, Thomas; Kandaswamy, Deivanayagam; Arathi, Ganesh; Hannah, Rosaline

2012-01-01

Aim: The aim of this study is to evaluate the bactericidal effect of 908 nm diode laser in conjunction with various irrigation regimes in disinfection of apical third of root dentin. Materials and Methods: Sixty prepared teeth with single canals were contaminated with Enterococcus faecalis. The specimens were divided into 6 groups (n = 10): Group 1 and 3 and 5 were subjected to chemo-mechanical preparation using 5.25% sodium hypochlorite (NaOCl), 17% Ethylenediaminetetraacetic acid (EDTA); 1.3% NaOCl, MTAD (mixture of doxycycline, citric acid and a detergent (Tween 80); and, 8.5% saline, respectively followed by 908 nm diode laser irradiation; Group 2 and 4, followed the same procedure as Group1 and 3, however without laser irradiation; and, Group 6, rinsed with saline solution (control). Dentin shavings from apical third were analyzed for the presence of E. faecalis using culture method and Polymerase Chain reaction (PCR). Results: One-way Analysis of variance showed statistically significant differences between the laser irradiated groups, non irradiated groups and the control group. Conclusion: 908 nm diode used in conjunction with conventional chemomechanical techniques demonstrated a significant elimination of E. faecalis in the apical third of root dentin. PMID:22368335

Extension of wavelength-modulation spectroscopy to large modulation depth for diode laser absorption measurements in high-pressure gases

NASA Astrophysics Data System (ADS)

Li, Hejie; Rieker, Gregory B.; Liu, Xiang; Jeffries, Jay B.; Hanson, Ronald K.

2006-02-01

Tunable diode laser absorption measurements at high pressures by use of wavelength-modulation spectroscopy (WMS) require large modulation depths for optimum detection of molecular absorption spectra blended by collisional broadening or dense spacing of the rovibrational transitions. Diode lasers have a large and nonlinear intensity modulation when the wavelength is modulated over a large range by injection-current tuning. In addition to this intensity modulation, other laser performance parameters are measured, including the phase shift between the frequency modulation and the intensity modulation. Following published theory, these parameters are incorporated into an improved model of the WMS signal. The influence of these nonideal laser effects is investigated by means of wavelength-scanned WMS measurements as a function of bath gas pressure on rovibrational transitions of water vapor near 1388 nm. Lock-in detection of the magnitude of the 2f signal is performed to remove the dependence on detection phase. We find good agreement between measurements and the improved model developed for the 2f component of the WMS signal. The effects of the nonideal performance parameters of commercial diode lasers are especially important away from the line center of discrete spectra, and these contributions become more pronounced for 2f signals with the large modulation depths needed for WMS at elevated pressures.

Power blue and green laser diodes and their applications

NASA Astrophysics Data System (ADS)

Hager, Thomas; Strauß, Uwe; Eichler, Christoph; Vierheilig, Clemens; Tautz, Sönke; Brüderl, Georg; Stojetz, Bernhard; Wurm, Teresa; Avramescu, Adrian; Somers, André; Ristic, Jelena; Gerhard, Sven; Lell, Alfred; Morgott, Stefan; Mehl, Oliver

2013-03-01

InGaN based green laser diodes with output powers up to 50mW are now well established for variety of applications ranging from leveling to special lighting effects and mobile projection of 12lm brightness. In future the highest market potential for visible single mode profile lasers might be laser projection of 20lm. Therefore direct green single-mode laser diodes with higher power are required. We found that self heating was the limiting factor for higher current operation. We present power-current characteristics of improved R and D samples with up to 200mW in cw-operation. An optical output power of 100mW is reached at 215mA, a current level which is suitable for long term operation. Blue InGaN laser diodes are also the ideal source for phosphor based generation of green light sources of high luminance. We present a light engine based on LARP (Laser Activated Remote Phosphor) which can be used in business projectors of several thousand lumens on screen. We discuss the advantages of a laser based systems in comparison with LED light engines. LARP requires highly efficient blue power laser diodes with output power above 1W. Future market penetration of LARP will require lower costs. Therefore we studied new designs for higher powers levels. R and D chips with power-current characteristics up to 4W in continuous wave operation on C-mount at 25°C are presented.

Ruggedized microchannel-cooled laser diode array with self-aligned microlens

DOEpatents

Freitas, Barry L.; Skidmore, Jay A.

2003-11-11

A microchannel-cooled, optically corrected, laser diode array is fabricated by mounting laser diode bars onto Si surfaces. This approach allows for the highest thermal impedance, in a ruggedized, low-cost assembly that includes passive microlens attachment without the need for lens frames. The microlensed laser diode array is usable in all solid-state laser systems that require efficient, directional, narrow bandwidth, high optical power density pump sources.

Self-compensation of thermal lens in high-power diode pumped solid-state lasers

NASA Astrophysics Data System (ADS)

Wang, Xiao-Jun

2010-02-01

We present a comprehensive model to describe the optic-thermal coupling in the diode pumped solid-state lasers (DPSSL). The thermal transition of particles at the upper laser level leads the heat-generation of laser crystals to depend on shape of the laser beam, while the laser field is also influenced by the temperature because of the thermal excitation of doped particles among various Stark levels. These effects, together with the usual thermal-optic effect that induces a fluctuation of the refraction index by an inhomogeneous temperature distribution, cause a complicated coupling between the laser field and the temperature field. We show that the optic-thermal coupling plays an important role in high-power DPSSL with larger size beam. That effect may yield a self-compensation for the thermal lens and improve the beam quality.

The Influence of Geometrical Structure of AlInGaN Double Quantum Well (DQWs) UV Diode Laser on Its Performance and Operating Parameters

NASA Astrophysics Data System (ADS)

Ghazai, A. J.; Thahab, S. M.; Hassan, H. Abu; Hassan, Z.

2010-07-01

The development of efficient MQWs active regions of quaternary InAlGaN in the ultraviolet (UV) region is an engaging challenge by itself. Demonstrating lasers at such low wavelength will require resolving a number of materials, growth and device design issues. However, the quaternary AlInGaN represents a more versatile material since the bandgap and lattice constant can be independently varied. We report a quaternary AlInGaN double-quantum wells (DQWs) UV laser diode (LDs) study by using the simulation program of Integrated System Engineering-Technical Computer Aided Design (ISE TCAD). Advanced physical models of semiconductor properties were used. In this paper, the enhancement in the performance of AlInGaN laser diode can be achieved by optimizing the laser structure geometry design. The AlInGaN laser diodes operating parameters such as internal quantum efficiency ηi, internal loss αi and transparency threshold current density show effective improvements that contribute to a better performance.

Effect of diode laser in the treatment of patients with nonspecific chronic low back pain: a randomized controlled trial.

PubMed

Vallone, Francesco; Benedicenti, Stefano; Sorrenti, Eugenio; Schiavetti, Irene; Angiero, Francesca

2014-09-01

Low back pain is a common, highly debilitating condition, whose severity is variable. This study evaluated the efficacy of treatment with Ga-Al-As diode laser (980 nm) with a large diameter spot (32 cm(2)), in association with exercise therapy, in reducing pain. The present study aimed to evaluate the pain reduction efficacy of treatment with the Ga-Al-As diode laser (980 nm) in combination with exercise therapy, in patients with chronic low back pain (CLBP). This study evaluated 100 patients with CLBP (mean age 60 years) who were randomly assigned to two groups. The laser plus exercises group (Laser+EX: 50 patients) received low-level laser therapy (LLLT) with a diode laser, 980 nm, with a specific handpiece [32 cm(2) irradiation spot size, power 20 W in continuous wave (CW), fluence 37.5J/cm(2), total energy per point 1200 J] thrice weekly, and followed a daily exercise schedule for 3 weeks (5 days/week). The exercises group (EX: 50 patients) received placebo laser therapy plus daily exercises. The outcome was evaluated on the visual analogue pain scale (VAS), before and after treatment. At the end of the 3 week period, the Laser+EX group showed a significantly greater decrease in pain than did the EX group. There was a significant difference between the two groups, with average Δ VAS scores of 3.96 (Laser+EX group) and 2.23 (EX group). The Student's t test demonstrated a statistically significant difference between the two groups, at p<0.001. This study demonstrated that the use of diode laser (980 nm) with large diameter spot size, in association with exercise therapy, appears to be effective. Such treatment might be considered a valid therapeutic option within rehabilitation programs for nonspecific CLBP.

Iodine-stabilized single-frequency green InGaN diode laser.

PubMed

Chen, Yi-Hsi; Lin, Wei-Chen; Shy, Jow-Tsong; Chui, Hsiang-Chen

2018-01-01

A 520-nm InGaN diode laser can emit a milliwatt-level, single-frequency laser beam when the applied current slightly exceeds the lasing threshold. The laser frequency was less sensitive to diode temperature and could be finely tuned by adjusting the applied current. Laser frequency was stabilized onto a hyperfine component in an iodine transition through the saturated absorption spectroscopy. The uncertainty of frequency stabilization was approximately 8×10 -9 at a 10-s integration time. This compact laser system can replace the conventional green diode-pumped solid-state laser and applied as a frequency reference. A single longitudinal mode operational region with diode temperature, current, and output power was investigated.

Ultra-high brightness wavelength-stabilized kW-class fiber coupled diode laser

NASA Astrophysics Data System (ADS)

Huang, Robin K.; Chann, Bien; Glenn, John D.

2011-03-01

TeraDiode has produced a fiber-coupled direct diode laser with a power level of 1,040 W from a 200 μm core diameter, 0.18 numerical aperture (NA) output fiber at a single center wavelength. This was achieved with a novel beam combining and shaping technique using COTS diode lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 18 mm-mrad and is the lowest BPP kW-class direct diode laser yet reported. The laser has been used to demonstrate laser cutting and welding of steel sheet metal up to 6.65 mm thick. Further advances of these ultra-bright lasers are also projected.

The Adjunctive Soft-Tissue Diode Laser in Orthodontics.

PubMed

Borzabadi-Farahani, Ali

2017-04-01

Lasers are a relatively new addition to the orthodontist's armamentarium. This article reviews the fundamental basic science of available soft-tissue lasers, with an emphasis on diode lasers, and discusses various adjunct applications of the diode laser for soft-tissue orthodontic procedures. Diode lasers function by cutting with an initiated hot tip and produce minimal to no interaction with healthy dental hard tissue, making them suitable for soft-tissue procedures. The contact cutting mode provides enhanced bloodless site visibility and facility to perform delicate soft tissue procedures, which is important in areas with difficult access. Such adjunctive uses include laser gingivectomy to improve oral hygiene or bracket positioning, esthetic laser gingival recontouring, and laser exposure of superficially impacted teeth. Selected cases treated with a 940-nm indium-gallium-arsenide-phosphide (InGaAsP) diode laser will be presented.

High power diode and solid state lasers

NASA Astrophysics Data System (ADS)

Eichler, H. J.; Fritsche, H.; Lux, O.; Strohmaier, S. G.

2017-01-01

Diode lasers are now basic pump sources of crystal, glass fiber and other solid state lasers. Progress in the performance of all these lasers is related. Examples of recently developed diode pumped lasers and Raman frequency converters are described for applications in materials processing, Lidar and medical surgery.

Treatment of inflammatory facial acne vulgaris in Chinese patients with the 1450-nm diode laser: a pilot study

NASA Astrophysics Data System (ADS)

Liu, Huaxu; Dang, Yongyan; Wang, Zhan; Ma, Li; Ren, Qiushi

2007-02-01

The 1450-nm diode laser has been found to be effective for the treatment of inflammatory acne in USA, Europe and Japan. However, there is no report on its efficacy in Chinese acne vulgaris patients. We conduct this pilot study to evaluate the efficacy and safety of the 1450-nm diode laser in the treatment of inflammatory facial acne vulgaris in Chinese patients. Nineteen patients with inflammatory facial acne were treated with the 1450-nm diode laser at 4- to 6-week intervals. Clinical photographs and lesion counts were obtained at baseline and after each treatment. Subjective evaluation of response to treatment and pain was assessed using a questionnaire. In our study, clinical improvement was seen in all patients and was generally dramatic. Lesion counts decreased 34% after one treatment (p<0.01), 56% after two treatments (p<0.01), and 81% after three treatments (p<0.01). However, the treatment-related pain was comparatively hard to be tolerated in Chinese patitents, and the other main adverse effect was the hyper-pigmentation after treatments (36.84%, 7/19).

Free space broad-bandwidth tunable laser diode based on Littman configuration for 3D profile measurement

NASA Astrophysics Data System (ADS)

Shirazi, Muhammad Faizan; Kim, Pilun; Jeon, Mansik; Kim, Chang-Seok; Kim, Jeehyun

2018-05-01

We developed a tunable laser diode for an optical coherence tomography system that can perform three-dimensional profile measurement using an area scanning technique. The tunable laser diode is designed using an Eagleyard tunable laser diode with a galvano filter. The Littman free space configuration is used to demonstrate laser operation. The line- and bandwidths of this source are 0.27 nm (∼110 GHz) and 43 nm, respectively, at the center wavelength of 860 nm. The output power is 20 mW at an operating current of 150 mA. A step height target is imaged using a wide-area scanning system to show the measurement accuracy of the proposed tunable laser diode. A TEM grid is also imaged to measure the topography and thickness of the sample by proposed tunable laser diode.

Diode laser assisted minimal invasive sphenoidotomy for endoscopic transphenoidal pituitary surgery: our technique and results.

PubMed

Lee, Jih-Chin; Lai, Wen-Sen; Ju, Da-Tong; Chu, Yueng-Hsiang; Yang, Jinn-Moon

2015-03-01

During endoscopic sinus surgery (ESS), intra-operative bleeding can significantly compromise visualization of the surgical field. The diode laser that provides good hemostatic and vaporization effects and excellent photocoagulation has been successfully applied in endoscopic surgery with several advantages. The current retrospective study demonstrates the feasibility of diode laser-combined endoscopic sinus surgery on sphenoidotomy. The patients who went through endoscopic transphenoidal pituitary surgery were enrolled. During the operation, the quality of the surgical field was assessed and graded by the operating surgeon using the scale proposed by Boezaart. The mean operation time was 37.80 ± 10.90 minutes. The mean score on the quality of surgical field was 1.95. A positive correlation between the lower surgical field quality score and the shorter surgical time was found with statistical significance (P < 0.0001). No infections, hemorrhages, or other complications occurred intra- or post-operatively. The diode laser-assisted sphenoidotomy is a reliable and safe approach of pituitary gland surgery with minimal invasiveness. It is found that application of diode laser significantly improved quality of surgical field and shortened operation time. © 2015 Wiley Periodicals, Inc.

V-shaped resonators for addition of broad-area laser diode arrays

DOEpatents

Liu, Bo; Liu, Yun; Braiman, Yehuda Y.

2012-12-25

A system and method for addition of broad-area semiconductor laser diode arrays are described. The system can include an array of laser diodes, a V-shaped external cavity, and grating systems to provide feedback for phase-locking of the laser diode array. A V-shaped mirror used to couple the laser diode emissions along two optical paths can be a V-shaped prism mirror, a V-shaped stepped mirror or include multiple V-shaped micro-mirrors. The V-shaped external cavity can be a ring cavity. The system can include an external injection laser to further improve coherence and phase-locking.

Effects of erbium-and chromium-doped yttrium scandium gallium garnet and diode lasers on the surfaces of restorative dental materials: a scanning electron microscope study.

PubMed

Hatipoglu, M; Barutcigil, C

2015-01-01

The aim of this study is to evaluate the potential effects of laser irradiation, which is commonly performed in periodontal surgery, on the surfaces of restorative materials. Five different restorative dental materials were used in this study, as follows: (1) Resin composite, (2) poly acid-modified resin composite (compomer), (3) conventional glass ionomer cement (GIC), (4) resin-modified glass ionomer cement (RMGIC), and (5) amalgam. Four cylindrical samples (8 mm diameter, 2 mm height) were prepared for each restorative material. In addition, four freshly extracted, sound human incisors teeth were selected. Two different laser systems commonly used in periodontal surgery were examined in this study: A 810 nm diode laser at a setting of 1 W with continuous-phase laser irradiation for 10 s, and an erbium-and chromium-doped yttrium scandium gallium garnet (Er, Cr: YSGG) laser at settings of 2.5 W, 3.25 W, and 4 W with 25 Hz laser irradiation for 10 s. Scanning electron microscopy (SEM) analysis was performed to evaluate the morphology and surface deformation of the restorative materials and tooth surfaces. According to the SEM images, the Er, Cr: YSGG laser causes irradiation markings that appear as demineralized surfaces on tooth samples. The Er, Cr: YSGG laser also caused deep defects on composite, compomer, and RMGIC surfaces because of its high power, and the ablation was deeper for these samples. High-magnification SEM images of GIC samples showed the melting and combustion effects of the Er, Cr: YSGG laser, which increased as the laser power was increased. In amalgam samples, neither laser left significant harmful effects at the lowest power setting. The diode laser did cause irradiation markings, but they were insignificant compared with those left by the Er, Cr: YSGG laser on the surfaces of the different materials and teeth. Within the limitations of this study, it can be concluded that Er, Cr: YSGG laser irradiation could cause distortions of the surfaces of restorative materials. Diode lasers can be preferred for periodontal surgery.

WDM Nanoscale Laser Diodes for Si Photonic Interconnects

DTIC Science & Technology

2016-07-25

mounting on silicon. The nanoscale VCSELs can achieve small optical modes and present a compact laser diode that is also robust. In this work we have used...Distribution Unlimited UU UU UU UU 25-07-2016 1-Feb-2012 31-Dec-2015 Final Report: WDM Nanoscale Laser Diodes for Si Photonic Interconnects The views...P.O. Box 12211 Research Triangle Park, NC 27709-2211 VCSEL, optical interconnect, laser diode , semiconductor laser, microcavity REPORT DOCUMENTATION

Active media for up-conversion diode-pumped lasers

NASA Astrophysics Data System (ADS)

Tkachuk, Alexandra M.

1996-03-01

In this work, we consider the different methods of populating the initial and final working levels of laser transitions in TR-doped crystals under the selective 'up-conversion' and 'avalanche' diode laser pumping. On the basis of estimates of the probabilities of competing non-radiative energy-transfer processes rates obtained from the experimental data and theoretical calculations, we estimated the efficiency of the up-conversion pumping and selfquenching of the upper TR3+ states excited by laser-diode emission. The effect of the host composition, dopant concentration, and temperature on the output characteristics and up-conversion processes in YLF:Er; BaY2F8:Er; BaY2F8:Er,Yb and BaY2F8:Yb,Ho are determined.

Research and development for improved lead-salt diode lasers

NASA Technical Reports Server (NTRS)

Butler, J. F.

1976-01-01

A substantial increase in output power levels for lead-salt diode lasers, through the development of improved fabrication methods, as demonstrated. The goal of 1 mW of CW, single-mode, single-ended power output, was achieved, with exceptional devices exhibiting values greater than 8 mW. It was found that the current tuning rate could be controlled by adjusting the p-n junction depth, allowing the tuning rate to be optimized for particular applications. An unexpected phenomenon was encountered when crystal composition was observed to be significantly altered by annealing at temperatures as low as 600 C; the composition was changed by transport of material through the vapor phase. This effect caused problems in obtaining diode lasers with the desired operating characteristics. It was discovered that the present packaging method introduces gross damaging effects in the laser crystal through pressure applied by the C-bend.

Clinical Application of Diode Laser (980 nm) in Maxillofacial Surgical Procedures.

PubMed

Aldelaimi, Tahrir N; Khalil, Afrah A

2015-06-01

For many procedures, lasers are now becoming the treatment of choice by both clinicians and patients, and in some cases, the standard of care. This clinical study was carried out at Department of Maxillofacial Surgery, Ramadi Teaching Hospital, Rashid Private Hospital and Razi Private Hospital, Anbar Health Directorate, Anbar Province, Iraq. A total of 32 patients including 22 (≈ 70%) male and 10 (≈ 30%) female with age range from 5 months to 34 years old. Chirolas 20 W diode laser emitting at 980 nm was used. Our preliminary clinical findings include sufficient hemostasis, coagulation properties, precise incision margin, lack of swelling, bleeding, pain, scar tissue formation and overall satisfaction were observed in the clinical application. The clinical application of the diode (980 nm) laser in maxillofacial surgery proved to be of beneficial effect for daily practice and considered practical, effective, easy to used, offers a safe, acceptable, and impressive alternative for conventional surgical techniques.

Direct-current polarization characteristics of various AlGaAs laser diodes

NASA Technical Reports Server (NTRS)

Fuhr, P. L.

1984-01-01

Polarization characteristics of AlGaAs laser diodes having various device geometries have been measured. Measurements were performed with the laser diodes operating under dc conditions. Results show that laser diodes having different device geometries have optical outputs that exhibit varying degrees of polarization purity. Implications of this result, with respect to incoherent polarization-beam combining, are addressed.

Nonimaging concentrators for diode-pumped slab lasers

NASA Astrophysics Data System (ADS)

Lacovara, Philip; Gleckman, Philip L.; Holman, Robert L.; Winston, Roland

1991-10-01

Diode-pumped slab lasers require concentrators for high-average power operation. We detail the properties of diode lasers and slab lasers which set the concentration requirements and the concentrator design methodologies that are used, and describe some concentrator designs used in high-average power slab lasers at Lincoln Laboratory.

Generation of high powers from diode pumped chromium-3+ doped colquiriites

NASA Astrophysics Data System (ADS)

Eichenholz, Jason Matthew

1998-12-01

There is considerable interest in the area of laser diode pumped solid-state lasers. Diode pumped solid-state lasers (DPSSL) operating at high average power levels are attractive light sources for various applications such as materials processing, laser radar, and fundamental physics experiments. These laser systems have become more commonplace because of their efficiency, reliability, compactness, low relative cost, and long operational lifetimes. Induced thermal effects in the solid-state laser medium hinder the scaling of DPSSL's to higher average power levels. Therefore a deep insight into the thermo-mechanical properties of the solid state laser is crucial in order to ensure a laser design which is optimized for high average power operation. A comprehensive study of the factors that contribute to thermal loading of the colquiriites was performed. A three-dimensional thermal model has been created to determine the temperature rise inside the laser crystal. This new model calculates the temperature distribution by considering quantum defect, upconversion, and upper-state lifetime quenching as heating sources. The thermally induced lensing in end pumped Cr3+ doped LiSrAlF6, LiSrGaF6, LiSrCaAlF6, and LiCaAlF6 were experimentally measured. Several diode pumped colquiriite laser systems were assembled to quantitatively observe and identify thermally induced effects. Significant differences in each of the colquiriite materials were observed. These differences are explained by the differences in the thermo-mechanical and thermo-optical properties of the material and are explained by the theoretical thermal model.

Short range laser obstacle detector. [for surface vehicles using laser diode array

NASA Technical Reports Server (NTRS)

Kuriger, W. L. (Inventor)

1973-01-01

A short range obstacle detector for surface vehicles is described which utilizes an array of laser diodes. The diodes operate one at a time, with one diode for each adjacent azimuth sector. A vibrating mirror a short distance above the surface provides continuous scanning in elevation for all azimuth sectors. A diode laser is synchronized with the vibrating mirror to enable one diode laser to be fired, by pulses from a clock pulse source, a number of times during each elevation scan cycle. The time for a given pulse of light to be reflected from an obstacle and received is detected as a measure of range to the obstacle.

Thin planar package for cooling an array of edge-emitting laser diodes

DOEpatents

Mundinger, David C.; Benett, William J.

1992-01-01

A laser diode array is disclosed that includes a plurality of planar assemblies and active cooling of each assembly. The laser diode array may be operated in a long duty cycle, or in continuous operation. A laser diode bar and a microchannel heat sink are thermally coupled in a compact, thin planar assembly having the laser diode bar located proximate to one edge. In an array, a number of such thin planar assemblies are secured together in a stacked configuration, in close proximity so that the laser diodes are spaced closely. The cooling means includes a microchannel heat sink proximate to the laser diode bar to absorb heat generated by laser operation. To provide the coolant to the microchannels, each thin planar assembly comprises passageways that connect the microchannels to inlet and outlet corridors. Each inlet passageway may comprise a narrow slot that directs coolant into the microchannels and increases the velocity of flow therethrough. The corridors comprises holes extending through each of the assemblies in the array. The inlet and outlet corridors are connected to a conventional coolant circulation system. The laser diode array with active cooling has applications as an optical pump for high power solid state lasers, or by mating the diodes with fiber optic lenses. Further, the arrays can be useful in applications having space constraints and energy limitations, and in military and space applications. The arrays can be incorporated in equipment such as communications devices and active sensors.

Off-axis spectral beam combining of Bragg reflection waveguide photonic crystal diode lasers

NASA Astrophysics Data System (ADS)

Sun, Fangyuan; Wang, Lijie; Zhao, Yufei; Hou, Guanyu; Shu, Shili; Zhang, Jun; Peng, Hangyu; Tian, Sicong; Tong, Cunzhu; Wang, Lijun

2018-06-01

The spectral beam combining (SBC) of Bragg reflection waveguide photonic crystal (BRW-PC) diode lasers was studied for the first time. An off-axis feedback system was constructed using a stripe mirror and a spatial filter to control beam quality in the external cavity. It was found that the BRW-PC diode lasers with a low divergence and a circular beam provided a simplified and cost-effective SBC. The off-axis feedback broke the beam quality limit of a single element, and an M 2 factor of 3.8 times lower than that of a single emitter in the slow axis was demonstrated.

Arrangement for damping the resonance in a laser diode

NASA Technical Reports Server (NTRS)

Katz, J.; Yariv, A.; Margalit, S. (Inventor)

1985-01-01

An arrangement for damping the resonance in a laser diode is described. This arrangement includes an additional layer which together with the conventional laser diode form a structure (35) of a bipolar transistor. Therein, the additional layer serves as the collector, the cladding layer next to it as the base, and the active region and the other cladding layer as the emitter. A capacitor is connected across the base and the collector. It is chosen so that at any frequency above a certain selected frequency which is far below the resonance frequency the capacitor impedance is very low, effectively shorting the base to the collector.

Hybrid integration of laser source on silicon photonic integrated circuit for low-cost interferometry medical device

NASA Astrophysics Data System (ADS)

Duperron, Matthieu; Carroll, Lee; Rensing, Marc; Collins, Sean; Zhao, Yan; Li, Yanlu; Baets, Roel; O'Brien, Peter

2017-02-01

The cost-effective integration of laser sources on Silicon Photonic Integrated Circuits (Si-PICs) is a key challenge to realizing the full potential of on-chip photonic solutions for telecommunication and medical applications. Hybrid integration can offer a route to high-yield solutions, using only known-good laser-chips, and simple freespace micro-optics to transport light from a discrete laser-diode to a grating-coupler on the Si-PIC. In this work, we describe a passively assembled micro-optical bench (MOB) for the hybrid integration of a 1550nm 20MHz linewidth laser-diode on a Si-PIC, developed for an on-chip interferometer based medical device. A dual-lens MOB design minimizes aberrations in the laser spot transported to the standard grating-coupler (15 μm x 12 μm) on the Si-PIC, and facilitates the inclusion of a sub-millimeter latched-garnet optical-isolator. The 20dB suppression from the isolator helps ensure the high-frequency stability of the laser-diode, while the high thermal conductivity of the AlN submount (300/W=m.°C), and the close integration of a micro-bead thermistor, ensure the stable and efficient thermo-electric cooling of the laser-diode, which helps minimise low-frequency drift during the approximately 15s of operation needed for the point-of-care measurement. The dual-lens MOB is compatible with cost-effective passively-aligned mass-production, and can be optimised for alternative PIC-based applications.

Ablation of intervertebral discs in dogs using a MicroJet-assisted dye-enhanced injection device coupled with the diode laser

NASA Astrophysics Data System (ADS)

Bartels, Kenneth E.; Henry, George A.; Dickey, D. Thomas; Stair, Ernest L.; Powell, Ronald; Schafer, Steven A.; Nordquist, Robert E.; Frederickson, Christopher J.; Hayes, Donald J.; Wallace, David B.

1998-07-01

Use of holmium laser energy for vaporization/coagulation of the nucleus pulposus in canine intervertebral discs has been previously reported and is currently being applied clinically in veterinary medicine. The procedure was originally developed in the canine model and intended for potential human use. Since the pulsed (15 Hz) holmium laser energy exerts photomechanical and photothermal effects, the potential for extrusion of additional disc material to the detriment of the patient is possible using the procedure developed for the dog. To reduce this potential complication, use of diode laser (805 nm - CW mode) energy, coupled with indocyanine green (ICG) as a selective laser energy absorber, was formulated as a possible alternative. Delivery of the ICG and diode laser energy was through a MicroJet device that could dispense dye interactively between individual laser 'shots.' Results have shown that it is possible to selectively ablate nucleus pulposus in the canine model using the device described. Acute observations (gross and histopathologic) illustrate that accurate placement of the spinal needle before introduction of the MicroJet device is critically dependent on the expertise of the interventional radiologist. In addition, the success of the overall technique depends on consistent delivery of both ICG and diode laser energy. Minimizing tissue carbonization on the tip of the MicroJet device is also of crucial importance for effective application of the technique in clinical veterinary medicine.

Advancement of High Power Quasi-CW Laser Diode Arrays For Space-based Laser Instruments

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin; Meadows, Byron L.; Baker, nathaniel R.; Baggott, Renee S.; Singh, Upendra N.; Kavaya, Michael J.

2004-01-01

Space-based laser and lidar instruments play an important role in NASA s plans for meeting its objectives in both Earth Science and Space Exploration areas. Almost all the lidar instrument concepts being considered by NASA scientist utilize moderate to high power diode-pumped solid state lasers as their transmitter source. Perhaps the most critical component of any solid state laser system is its pump laser diode array which essentially dictates instrument efficiency, reliability and lifetime. For this reason, premature failures and rapid degradation of high power laser diode arrays that have been experienced by laser system designers are of major concern to NASA. This work addresses these reliability and lifetime issues by attempting to eliminate the causes of failures and developing methods for screening laser diode arrays and qualifying them for operation in space.

Comparison of Alexandrite and Diode Lasers for Hair Removal in Dark and Medium Skin: Which is Better?

PubMed Central

Mustafa, Farhad Hamad; Jaafar, Mohamad Suhimi; Ismail, Asaad Hamid; Mutter, Kussay Nugamesh

2014-01-01

Introduction: To improve laser hair removal (LHR) for dark skin, the fluence rate reaching the hair follicle in LHR is important. This paper presents the results of a comparative study examining the function of wavelength on dark skin types using 755 nm alexandrite and 810 nm diode lasers. Methods: The structure of the skin was created using a realistic skin model by the Advanced Systems Analysis Program. Result: In this study, the alexandrite laser (755 nm) and diode laser (810 nm) beam–skin tissue interactions were simulated. The simulation results for both lasers differed. The transmission ratio of the diode laser to the dark skin dermis was approximately 4% more than that of the alexandrite laser for the same skin type. For the diode laser at skin depth z = 0.67 mm, the average transmission ratios of both samples were 36% and 27.5%, but those for the alexandrite laser at the same skin depth were 32% and 25%. Conclusion: Both lasers were suitable in LHR for dark skin types, but the diode laser was better than the alexandrite laser because the former could penetrate deeper into the dermis layer. PMID:25653820

Comparison of Alexandrite and Diode Lasers for Hair Removal in Dark and Medium Skin: Which is Better?

PubMed

Mustafa, Farhad Hamad; Jaafar, Mohamad Suhimi; Ismail, Asaad Hamid; Mutter, Kussay Nugamesh

2014-01-01

To improve laser hair removal (LHR) for dark skin, the fluence rate reaching the hair follicle in LHR is important. This paper presents the results of a comparative study examining the function of wavelength on dark skin types using 755 nm alexandrite and 810 nm diode lasers. The structure of the skin was created using a realistic skin model by the Advanced Systems Analysis Program. In this study, the alexandrite laser (755 nm) and diode laser (810 nm) beam-skin tissue interactions were simulated. The simulation results for both lasers differed. The transmission ratio of the diode laser to the dark skin dermis was approximately 4% more than that of the alexandrite laser for the same skin type. For the diode laser at skin depth z = 0.67 mm, the average transmission ratios of both samples were 36% and 27.5%, but those for the alexandrite laser at the same skin depth were 32% and 25%. Both lasers were suitable in LHR for dark skin types, but the diode laser was better than the alexandrite laser because the former could penetrate deeper into the dermis layer.

Efficient, diode-laser-pumped, diode-laser-seeded, high-peak-power Nd:YLF regenerative amplifier.

PubMed

Selker, M D; Afzal, R S; Dallas, J L; Yu, A W

1994-04-15

Optical amplification of 11 orders of magnitude in a microlens-collimated, diode-laser-pumped regenerative amplifier has been demonstrated. The amplifier was seeded with 20-ps pulses from an FM mode-locked oscillator and with 0.9-ns pulses from a modulated diode laser. Seed pulses from both sources were amplified to energies exceeding 2.5 mJ. With the thermoelectric coolers and the Pockels cell electronics neglected, the diode-seeded system exhibited an electrical-to-optical efficiency of 2.2%.

Compact 2100 nm laser diode module for next-generation DIRCM

NASA Astrophysics Data System (ADS)

Dvinelis, Edgaras; Greibus, Mindaugas; TrinkÅ«nas, Augustinas; NaujokaitÄ--, Greta; Vizbaras, Augustinas; Vizbaras, Dominykas; Vizbaras, Kristijonas

2017-10-01

Compact high-power 2100 nm laser diode module for next-generation directional infrared countermeasure (DIRCM) systems is presented. Next-generation DIRCM systems require compact, light-weight and robust laser modules which could provide intense IR light emission capable of disrupting the tracking sensor of heat-seeking missile. Currently used solid-state and fiber laser solutions for mid-IR band are bulky and heavy making them difficult to implement in smaller form-factor DIRCM systems. Recent development of GaSb laser diode technology greatly improved optical output powers and efficiencies of laser diodes working in 1900 - 2450 nm band [1] while also maintaining very attractive size, weight, power consumption and cost characteristics. 2100 nm laser diode module presented in this work performance is based on high-efficiency broad emitting area GaSb laser diode technology. Each laser diode emitter is able to provide 1 W of CW output optical power with working point efficiency up to 20% at temperature of 20 °C. For output beam collimation custom designed fast-axis collimator and slow-axis collimator lenses were used. These lenses were actively aligned and attached using UV epoxy curing. Total 2 emitters stacked vertically were used in 2100 nm laser diode module. Final optical output power of the module goes up to 2 W at temperature of 20 °C. Total dimensions of the laser diode module are 35 x 25 x 16 mm (L x W x H) with a weight of 28 grams. Finally output beam is bore-sighted to mechanical axes of the module housing allowing for easy integration into next-generation DIRCM systems.

Frequency-doubled DBR-tapered diode laser for direct pumping of Ti:sapphire lasers generating sub-20 fs pulses.

PubMed

Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika; Le, Tuan; Stingl, Andreas; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E; Petersen, Paul Michael

2011-06-20

For the first time a single-pass frequency doubled DBR-tapered diode laser suitable for pumping Ti:sapphire lasers generating ultrashort pulses is demonstrated. The maximum output powers achieved when pumping the Ti:sapphire laser are 110 mW (CW) and 82 mW (mode-locked) respectively at 1.2 W of pump power. This corresponds to a reduction in optical conversion efficiencies to 75% of the values achieved with a commercial diode pumped solid-state laser. However, the superior electro-optical efficiency of the diode laser improves the overall efficiency of the Ti:sapphire laser by a factor > 2. The optical spectrum emitted by the Ti:sapphire laser when pumped with our diode laser shows a spectral width of 112 nm (FWHM). Based on autocorrelation measurements, pulse widths of less than 20 fs can therefore be expected.

Inferior turbinate reduction: Diode laser or conventional partial turbinectomy?

PubMed

Doreyawar, Venkatesh; Gadag, Raveendra P; Manjunath, Dandi Narasaiah; Javali, Shivalingappa B; Maradi, Nagaraj; Shetty, Deekshit

2018-01-01

Hypertrophy of the inferior nasal turbinate is one of the most common causes of nasal obstruction. The diode laser has proven to be as effective as other lasers for this indication. Our objective was to study various outcomes associated with the use of the diode laser, such as improvements in nasal obstruction and postoperative pain, reduction in intraoperative bleeding, and rapidity of healing. A nonrandomized, controlled trial was conducted in which outcomes were compared between diode laser turbinate reduction (LTR) and conventional partial inferior turbinectomy (PIT) in 60 patients, 30 who underwent LTR and 30 who underwent PIT. The improvement in nasal obstruction was measured postoperatively up to 6 months. Intraoperative bleeding was measured and postoperative pain scores were assessed each day up to the fifth postoperative day. Rapidity of healing was evaluated until 6 months postoperatively. Subjective relief of nasal obstruction occurred in 90.8% of the LTR group and 65% of the PIT group at 6 months (p < 0.05). Pain scores were significantly higher until 5 days postoperatively in the PIT group compared with the LTR group (p = 0.0001). Intraoperative bleeding mean scores (ml) were 8.03 in the LTR group and 23.29 in the PIT group (p = 0.00001). Healing was faster in the LTR group at a mean of 3.03 weeks compared with 6.33 weeks in the PIT group (p = 0.00001). Outcomes with the diode laser were better and diode LTR caused less morbidity compared with the conventional technique.

AlGaAs diode pumped tunable chromium lasers

DOEpatents

Krupke, William F.; Payne, Stephen A.

1992-01-01

An all-solid-state laser system is disclosed wherein the laser is pumped in the longwave wing of the pump absorption band. By utilizing a laser material that will accept unusually high dopant concentrations without deleterious effects on the crystal lattice one is able to compensate for the decreased cross section in the wing of the absorption band, and the number of pump sources which can be used with such a material increases correspondingly. In a particular embodiment a chromium doped colquiriite-structure crystal such as Cr:LiSrAlF.sub.6 is the laser material. The invention avoids the problems associated with using AlGaInP diodes by doping the Cr:LiSrAlF.sub.6 heavily to enable efficient pumping in the longwave wing of the absorption band with more practical AlGaAs diodes.

High Power Laser Diode Arrays for 2-Micron Solid State Coherent Lidars Applications

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin; Meadows, Byron; Kavaya, Michael J.; Singh, Upendra; Sudesh, Vikas; Baker, Nathaniel

2003-01-01

Laser diode arrays are critical components of any diode-pumped solid state laser systems, constraining their performance and reliability. Laser diode arrays (LDAs) are used as the pump source for energizing the solid state lasing media to generate an intense coherent laser beam with a high spatial and spectral quality. The solid state laser design and the characteristics of its lasing materials define the operating wavelength, pulse duration, and power of the laser diodes. The pump requirements for high pulse energy 2-micron solid state lasers are substantially different from those of more widely used 1-micron lasers and in many aspects more challenging [1]. Furthermore, the reliability and lifetime demanded by many coherent lidar applications, such as global wind profiling from space and long-range clear air turbulence detection from aircraft, are beyond the capability of currently available LDAs. In addition to the need for more reliable LDAs with longer lifetime, further improvement in the operational parameters of high power quasi-cw LDAs, such as electrical efficiency, brightness, and duty cycle, are also necessary for developing cost-effective 2-micron coherent lidar systems for applications that impose stringent size, heat dissipation, and power constraints. Global wind sounding from space is one of such applications, which is the main driver for this work as part of NASA s Laser Risk Reduction Program. This paper discusses the current state of the 792 nm LDA technology and the technology areas being pursued toward improving their performance. The design and development of a unique characterization facility for addressing the specific issues associated with the LDAs for pumping 2-micron coherent lidar transmitters and identifying areas of technological improvement will be described. Finally, the results of measurements to date on various standard laser diode packages, as well as custom-designed packages with potentially longer lifetime, will be reported.

Atomic force microscopy visualization of injuries in Enterococcus faecalis surface caused by Er,Cr:YSGG and diode lasers

PubMed Central

López-Jiménez, Lidia; Viñas, Miguel; Vinuesa, Teresa

2015-01-01

Aim: To visualize by Atomic Force Microscopy the alterations induced on Enterococcus. faecalis surface after treatment with 2 types of laser: Erbium chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser and Diode laser. Material and Methods: Bacterial suspensions from overnight cultures of E. faecalis were irradiated during 30 seconds with the laser-lights at 1 W and 2 W of power, leaving one untreated sample as control. Surface alterations on treated E. faecalis were visualized by Atomic Force Microscopy (AFM) and its surface roughness determined. Results: AFM imaging showed that at high potency of laser both cell morphology and surface roughness resulted altered, and that several cell lysis signs were easily visualized. Surface roughness clearly increase after the treatment with Er,Cr:YSGG at 2W of power, while the other treatments gave similar values of surface roughness. The effect of lasers on bacterial surfaces visualized by AFM revealed drastic alterations. Conclusions: AFM is a good tool to evaluate surface injuries after laser treatment; and could constitute a measure of antimicrobial effect that can complete data obtained by determination of microbial viability. Key words:Atomic force microscopy, Er,Cr:YSGG laser, diode laser, Enterococcus faecalis, surface roughness. PMID:25475770

Effects of laser-assisted lipolysis on nipple-areola complex.

PubMed

Sönmez Ergün, Selma; Kayan, Reşit Burak; Güleş, Mustafa Ekrem; Kuzu, İsmail Melih

2017-08-01

Gynecomastia, as a most common benign condition, represents itself as the enlargement of the male breast and also nipple-areola complex as the severity of the condition increases. With this study, we aimed to clarify the effects of 980-nm diode laser on nipple-areola complex (NAC). Although numerous open techniques have been described to correct gynecomastia, nowadays trends have shifted to minimally invasive techniques such as laser-assisted lipolysis (LAL). A total of 25 patients with bilateral gynecomastia treated with LAL by using a 980-nm diode laser. The resultant contour and reduced size of the complex were satisfactory. LAL leads to significant reduction of the size of NAC.

Hypertrichosis in Becker's nevus: effective low-fluence laser hair removal.

PubMed

Lapidoth, M; Adatto, M; Cohen, S; Ben-Amitai, D; Halachmi, S

2014-01-01

Becker's nevus is cosmetically bothersome both due to the hyperpigmentation and due to the hypertrichosis which can accompany it, particularly in males. Laser hair removal can be considered, but the pigmented background of the Becker's nevus makes the treatment more challenging. Fifteen patients with Becker's nevus underwent eight sessions of hair removal with low-fluence high-repetition-rate diode lasers (808-810 nm). All participants experienced significant hair reduction at 6 and 12 months. No adverse events were reported. The study supports the use of low fluence with high-repetition-rate diode laser hair removal as a safe and effective method for the management of hypertrichosis in Becker's nevus.

Schlieren with a laser diode source

NASA Technical Reports Server (NTRS)

Burner, A. W.; Franke, J. M.

1981-01-01

The use of a laser diode as a light source for a schlieren system designed to study phase objects such as a wind-tunnel flow is explored. A laser diode schlieren photograph and a white light schlieren photograph (zirconium arc source) are presented for comparison. The laser diode has increased sensitivity, compared with light schlieren, without appreciable image degradiation, and is an acceptable source for schlieren flow visualization.

Free-space and underwater GHz data transmission using AlGaInN laser diode technology

NASA Astrophysics Data System (ADS)

Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Boćkowski, M.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Kucharski, R.; Targowski, G.; Watson, S.; Kelly, A. E.

2016-05-01

Laser diodes fabricated from the AlGaInN material system is an emerging technology for defence and security applications; in particular for free space laser communication. Conventional underwater communication is done acoustically with very slow data rates, short reach, and vulnurable for interception. AlGaInN blue-green laser diode technology allows the possibility of both airbourne links and underwater telecom that operate at very fast data rates (GHz), long reach (100's of metres underwater) and can also be quantum encrypted. The latest developments in AlGaInN laser diode technology are reviewed for defence and security applications. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well. Ridge waveguide laser diode structures are fabricated to achieve single mode operation with optical powers of <100mW. Visible light communications at high frequency (up to 2.5 Gbit/s) using a directly modulated 422nm Galliumnitride (GaN) blue laser diode is reported in free-space and underwater.

Generation of 369.4 nm Radiation by Efficient Doubling of a Diode Laser

NASA Technical Reports Server (NTRS)

Williams, A.; Seidel, D. J.; Maleki, J.

1993-01-01

A resonant cavity second harmonic generation system has been developed to produce 369.4 nm radiation from a 738.8 nm diode laser with 10 mW nominal output power. This system utilizes a polarization technique to lock the cavity to the laser frequency. In this paper we report on an evaluation of the system using a Titanium:Sapphire laser as the input source, and preliminary results with a diode laser source. To our knowledge, this is the deepest uv light ever produced by frequency-doubling a diode laser.

Subthreshold and micropulse diode laser photocoagulation.

PubMed

Dorin, Giorgio

2003-09-01

Retinal laser photocoagulation is a proven, effective treatment for various retinal disorders. Common clinical protocols use intra-operatively visible endpoints that cause iatrogenic chorioretinal damage. For this reason, laser therapy is normally limited to levels of disease severity for which the benefit-to-risk ratio justifies its application. The use of 810 nm diode lasers in the MicroPulse mode offers the surgeon the possibility to minimize iatrogenic retinal damage. A less destructive laser therapy with a more favorable benefit-to-risk ratio could justify treatment earlier in the course of the disease, allowing for stabilization or improvement of less compromised visual functions.

A New Cost-Effective Diode Laser Polarimeter Apparatus Constructed by Undergraduate Students

ERIC Educational Resources Information Center

Lisboa, Pedro; Sotomayor, Joo; Ribeiro, Paulo

2010-01-01

The construction of a diode laser polarimeter apparatus by undergraduate students is described. The construction of the modular apparatus by undergraduate students gives them an insight into how it works and how the measurement of a physical or chemical property is conducted. The students use the polarimeter to obtain rotation angle values for the…

Controlled feasibility trial comparing the use of 1470nm and 940nm diode laser for the treatment of hyperplastic inferior nasal turbinates

NASA Astrophysics Data System (ADS)

Sroka, Ronald; Havel, Miriam; Leunig, Andreas; Betz, Christian S.

2012-02-01

Introduction: So far various laser systems have been used for volume reduction of hyperplastic nasal turbinates. In case of endonasal application, fiber controlled diode lasers are preferred due to reasons of cost and practicability. The aim of this clinical study was to compare the coagulative tissue effects using either λ=1470nm vs. λ=940nm emitting lasers in treatment of hyperplastic inferior nasal turbinates in an intraindividual manner. Patients and methods: This prospective, randomized, double-blind, clinical feasibility trial included 20 patients suffering from hyperplastic inferior nasal turbinates. In each case, one nasal cavity was treated using 1470nm laser at 4- 5W, the other one with 940nm laser at 12W. Treatment was performed endoscopically controlled in non-contact mode. Clinical presentation and patients symptoms were documented preoperatively and on day 1, 3, 7, 14 and 21 postoperatively using rhinomanometry, standardized questionnaires including SNOT 20 GAV (German adapted version), and separate endoscopic examination respectively. Results: None of the patients showed infections, hemorrhages or other complications occurred intra- or postoperatively. The mean operation time was significantly shorter using the 1470nm diode laser as compared to the 940nm laser, thus lower energy was applied. There was a significant reduction of nasal obstruction on day 21 postoperatively compared to the preoperative condition on both sides regardless of the laser system used. Evaluation of the SNOT-Scores as assessed before and three weeks after surgery showed significant subjective improvements. Conclusion: Compared with standard application of 940nm diode laser, 1470nm diode laser application provides an equivalent tissue reduction in shorter operation time using less total energy and a comparable relief of nasal obstruction postoperatively.

Inhibition of enamel demineralisation using "Nd-YAG and diode laser assisted fluoride therapy".

PubMed

Chand, B R; Kulkarni, S; Mishra, P

2016-02-01

This in vitro study was to evaluate the irradiation efficacy of the Diode laser and the Nd-YAG laser either un-assisted or assisted by acidulated phosphate fluoride (APF) treatment on enamel's acid resistance. Seventy-two enamel samples, obtained from 12 extracted human molars, were randomly assigned to 6 groups as follows: (1) Control (C); (2) Exposed to APF gel (F); (3) Diode laser (DL); (4) Irradiated with Diode laser through APF gel (DL/F); (5) Nd-YAG laser (NL) and (6) Irradiated with Nd-YAG laser through APF gel (NL/F). The specimens were individually demineralised in an acidified hydroxyethylcellulose system, and the acid resistance was evaluated by determining the calcium ion dissolution using atomic absorption spectrometry. The average concentration of the calcium ion determined in groups 1 to 6 was 901, 757, 736, 592, 497 and 416 parts per million micrograms/gram, respectively. The results showed that demineralisation in the NL/F group was significantly less than the other groups and the control group was significantly greater than the other groups (P < 0.001). The effect of Nd-YAG laser irradiation, used alone or in combination with APF, in decreasing the enamel demineralisation was greater than all the other groups.

Pediatric endocanalicular diode laser dacryocystorhinostomy: results of a minimally invasive surgical technique.

PubMed

Uysal, Ismail Onder; Ozçimen, Muammer; Yener, Halil Ibrahim; Kal, Ali

2011-09-01

The purpose of this study was to evaluate the effectiveness of endocanalicular diode laser dacryocystorhinostomy (DCR), which is a minimally invasive surgical technique, in pediatric patients with congenital nasolacrimal duct obstruction (NLDO). A retrospective study was carried out on patients treated between October 2008 and August 2009 for nasolacrimal duct obstruction with an endocanalicular diode laser procedure. Patients diagnosed as having nasolacrimal duct obstruction were included in this study and an endocanalicular diode laser procedure was performed. The main outcome measures were patients' previous treatments, clinical presentation, operative and postoperative complications, postoperative follow-up and resolution of epiphora. Eighteen children (10 girls, 8 boys) with a mean age of 6.11 ± 2.08 years (range, 4-10) underwent 20 endocanalicular laser DCR operations for congenital NLDO. In all eyes (100%), there was a history of epiphora and chronic dacryocystitis; two (10%) presented with acute dacryocystitis. Previous procedures included probing and irrigation of all eyes (100%) and silicone tube intubation in nine eyes (45%). None of the patients underwent any previous DCR operations. During a mean postoperative follow-up period of 20.50 ± 3.24 months (range, 14-24 months), the anatomical success rate (patency of ostium on nasal endoscopy) was 100%, and the clinical success rate (resolution of epiphora) was 85%. Endocanalicular diode laser DCR is an effective treatment modality for pediatric patients with congenital NLDO that compares favorably with the reported success rates of external and endoscopic endonasal DCR. Moreover, it has an added advantage of shorter operative time, less morbidity and avoidance of overnight admission.

Comparative effectiveness of light emitting diodes (LEDs) and Lasers in near infrared photoimmunotherapy

PubMed Central

Sato, Kazuhide; Watanabe, Rira; Hanaoka, Hirofumi; Nakajima, Takahito; Choyke, Peter L.; Kobayashi, Hisataka

2016-01-01

Near infrared photoimmunotherapy (NIR-PIT) is a new cancer treatment that combines the specificity of antibodies for targeting tumors with the toxicity induced by photosensitizers after exposure to near infrared (NIR) light. Herein we compare two NIR-light sources; light emitting diodes (LEDs) and Lasers, for their effectiveness in NIR-PIT. A photosensitizer, IRDye-700DX, conjugated to panitumumab (pan-IR700), was incubated with EGFR-expressing A431 and MDA-MB-468-luc cells. NIR-light was provided by LEDs or Lasers at the same light dose. Laser-light produced more cytotoxicity and greater reductions in IR700-fluorescence intensity than LED-light. Laser-light also produced more cytotoxicity in vivo in both cell lines. Assessment of super-enhanced permeability and retention (SUPR) effects were stronger with Laser than LED. These results suggest that Laser-light produced significantly more cytotoxic effects compared to LEDs. Although LED is less expensive, Laser-light produces superior results in NIR-PIT. PMID:26885688

Comparative effectiveness of light emitting diodes (LEDs) and Lasers in near infrared photoimmunotherapy.

PubMed

Sato, Kazuhide; Watanabe, Rira; Hanaoka, Hirofumi; Nakajima, Takahito; Choyke, Peter L; Kobayashi, Hisataka

2016-03-22

Near infrared photoimmunotherapy (NIR-PIT) is a new cancer treatment that combines the specificity of antibodies for targeting tumors with the toxicity induced by photosensitizers after exposure to near infrared (NIR) light. Herein we compare two NIR-light sources; light emitting diodes (LEDs) and Lasers, for their effectiveness in NIR-PIT. A photosensitizer, IRDye-700DX, conjugated to panitumumab (pan-IR700), was incubated with EGFR-expressing A431 and MDA-MB-468-luc cells. NIR-light was provided by LEDs or Lasers at the same light dose. Laser-light produced more cytotoxicity and greater reductions in IR700-fluorescence intensity than LED-light. Laser-light also produced more cytotoxicity in vivo in both cell lines. Assessment of super-enhanced permeability and retention (SUPR) effects were stronger with Laser than LED. These results suggest that Laser-light produced significantly more cytotoxic effects compared to LEDs. Although LED is less expensive, Laser-light produces superior results in NIR-PIT.

Characterization of High-power Quasi-cw Laser Diode Arrays

NASA Technical Reports Server (NTRS)

Stephen, Mark A.; Vasilyev, Aleksey; Troupaki, Elisavet; Allan, Graham R.; Kashem, Nasir B.

2005-01-01

NASA s requirements for high reliability, high performance satellite laser instruments have driven the investigation of many critical components; specifically, 808 nm laser diode array (LDA) pump devices. Performance and comprehensive characterization data of Quasi-CW, High-power, laser diode arrays is presented.

Quasi-CW 110 kW AlGaAs Laser Diode Array Module for Inertial Fusion Energy Laser Driver

NASA Astrophysics Data System (ADS)

Kawashima, Toshiyuki; Kanzaki, Takeshi; Matsui, Ken; Kato, Yoshinori; Matsui, Hiroki; Kanabe, Tadashi; Yamanaka, Masanobu; Nakatsuka, Masahiro; Izawa, Yasukazu; Nakai, Sadao; Miyamoto, Masahiro; Kan, Hirofumi; Hiruma, Teruo

2001-12-01

We have successfully demonstrated a large aperture 803 nm AlGaAs diode laser module as a pump source for a 1053 nm, 10 J output Nd:glass slab laser amplifier for diode-pumped solid-state laser (DPSSL) fusion driver. Detailed performance results of the laser diode module are presented, including bar package and stack configuration, and their thermal design and analysis. A sufficiently low thermal impedance of the stack was realized by combining backplane liquid cooling configuration with modular bar package architecture. Total peak power of 110 kW and electrical to optical conversion efficiency of 46% were obtained from the module consisting of a total of 1000 laser diode bars. A peak intensity of 2.6 kW/cm2 was accomplished across an emitting area of 418 mm× 10 mm. Currently, this laser diode array module with a large two-dimensional aperture is, to our knowledge, the only operational pump source for the high output energy DPSSL.

Effects of 445-nm Diode Laser-Assisted Debonding of Self-Ligating Ceramic Brackets on Shear Bond Strength.

PubMed

Stein, Steffen; Hellak, Andreas; Schauseil, Michael; Korbmacher-Steiner, Heike; Braun, Andreas

2018-01-01

The aim of this study was to measure the effect of irradiation with a novel 445-nm diode laser on the shear bond strength (SBS) of ceramic brackets before debonding. Thirty ceramic brackets (In-Ovation ® C, GAC) were bonded in standard manner to the planed and polished buccal enamel surfaces of 30 caries-free human third molars. Each tooth was randomly allocated to the laser or control group, with 15 samples per group. The brackets in the laser group were irradiated with the diode laser (SIROLaser Blue ® ; Sirona) on three sides of the bracket bases for 5 sec each (lateral-coronal-lateral, a total of 15 sec) immediately before debonding. SBS values were measured for the laser group and control group. To assess the adhesive remnant index (ARI) and the degree of enamel fractures, micrographs of the enamel surface were taken with 10-fold magnification after debonding. The SBS values were significantly lower statistically in the laser group in comparison with the control group (p < 0.05). The ARI scores were also significantly lower statistically in the laser group in comparison with the control group (p < 0.05). No bracket fractures or enamel fractures occurred in either group after debonding. Irradiation of ceramic brackets with the novel diode laser before debonding significantly reduces the SBS values. This is of clinical importance, as it means that the risk of damage to the teeth, bracket fractures, and the overall treatment time can be reduced.

Wavelength stabilized multi-kW diode laser systems

NASA Astrophysics Data System (ADS)

Köhler, Bernd; Unger, Andreas; Kindervater, Tobias; Drovs, Simon; Wolf, Paul; Hubrich, Ralf; Beczkowiak, Anna; Auch, Stefan; Müntz, Holger; Biesenbach, Jens

2015-03-01

We report on wavelength stabilized high-power diode laser systems with enhanced spectral brightness by means of Volume Holographic Gratings. High-power diode laser modules typically have a relatively broad spectral width of about 3 to 6 nm. In addition the center wavelength shifts by changing the temperature and the driving current, which is obstructive for pumping applications with small absorption bandwidths. Wavelength stabilization of high-power diode laser systems is an important method to increase the efficiency of diode pumped solid-state lasers. It also enables power scaling by dense wavelength multiplexing. To ensure a wide locking range and efficient wavelength stabilization the parameters of the Volume Holographic Grating and the parameters of the diode laser bar have to be adapted carefully. Important parameters are the reflectivity of the Volume Holographic Grating, the reflectivity of the diode laser bar as well as its angular and spectral emission characteristics. In this paper we present detailed data on wavelength stabilized diode laser systems with and without fiber coupling in the spectral range from 634 nm up to 1533 nm. The maximum output power of 2.7 kW was measured for a fiber coupled system (1000 μm, NA 0.22), which was stabilized at a wavelength of 969 nm with a spectral width of only 0.6 nm (90% value). Another example is a narrow line-width diode laser stack, which was stabilized at a wavelength of 1533 nm with a spectral bandwidth below 1 nm and an output power of 835 W.

Short-Term Audiological Results of Diode Laser in Comparison with Manual Perforation in Stapes Surgery

PubMed Central

Hamerschmidt, Rogerio; Saab, Stephanie Sbizera; Carvalho, Bettina; Carmo, Carolina do

2018-01-01

Introduction  Diode laser is a new alternative in stapes surgery for otosclerosis. The present study is the first to compare the short-term results of the surgery performed using diode laser to those obtained through the conventional fenestration technique. Objective  To use audiometry to establish a comparative analysis between the functional results obtained through surgery for otosclerosis using diode laser and the conventional technique. Method  Audiometric evaluation of 12 patients submitted to stapes surgery for otosclerosis, using diode laser or conventional fenestration by needle and drills, between 2014 and 2015. Each group was composed of 6 patients. Pre and post-operative measures were compared for three months in both groups. The speech recognition threshold, the air and bone conduction threshold, as well as the gap between them at 500 Hz, 1 KHz, 2 KHz and 4 KHz were measured. Results  Significant difference in bone conduction and SRT was observed when compared post- and preoperative results in the diode group. However diode and conventional technique groups presented significant differences in air conduction and air-bone gap, suggesting that both can provide functional improvement. Conclusion  Laser stapedotomy is a safe technique with good results. Both laser surgery and the conventional technique have improved the hearing of patients with a discreet advantage for the diode laser. Further prospective and randomized clinical trials are required to disclose all possible benefits of the stapes surgery using diode laser. PMID:29619098

Short-Term Audiological Results of Diode Laser in Comparison with Manual Perforation in Stapes Surgery.

PubMed

Hamerschmidt, Rogerio; Saab, Stephanie Sbizera; Carvalho, Bettina; Carmo, Carolina do

2018-04-01

Introduction  Diode laser is a new alternative in stapes surgery for otosclerosis. The present study is the first to compare the short-term results of the surgery performed using diode laser to those obtained through the conventional fenestration technique. Objective  To use audiometry to establish a comparative analysis between the functional results obtained through surgery for otosclerosis using diode laser and the conventional technique. Method  Audiometric evaluation of 12 patients submitted to stapes surgery for otosclerosis, using diode laser or conventional fenestration by needle and drills, between 2014 and 2015. Each group was composed of 6 patients. Pre and post-operative measures were compared for three months in both groups. The speech recognition threshold, the air and bone conduction threshold, as well as the gap between them at 500 Hz, 1 KHz, 2 KHz and 4 KHz were measured. Results  Significant difference in bone conduction and SRT was observed when compared post- and preoperative results in the diode group. However diode and conventional technique groups presented significant differences in air conduction and air-bone gap, suggesting that both can provide functional improvement. Conclusion  Laser stapedotomy is a safe technique with good results. Both laser surgery and the conventional technique have improved the hearing of patients with a discreet advantage for the diode laser. Further prospective and randomized clinical trials are required to disclose all possible benefits of the stapes surgery using diode laser.

Rugged TDLAS system for High Energy Laser atmospheric propagation characterization

NASA Astrophysics Data System (ADS)

Perram, Glen; Rice, Christopher

2008-10-01

An active remote sensing instrument for the characterization of atmospheric absorption, scattering, and scintillation at several key high energy laser wavelengths is in development. The instrument is based on narrow band tunable diode lasers fiber coupled to a 12'' Ritchey-Chretien transmit telescope and a second receive telescope with visible or near infrared imager. For example, tunable diode lasers have been used to obtain absorption spectra in the laboratory for the Cs D2 lines near 852 nm and the oxygen X-b lines near 760 nm, key to the Diode Pumped Alkali Laser (DPAL) concept. Absorbencies of less than 0.5% are observable. Applications will be assessed including effects to HEL atmospheric propagation from molecular and aerosol absorption and scattering, Cn2 estimation from atmospheric turbulence, hazardous chemical emission detection, and laser communication interception from side scattering. The system will soon be deployed to a military laser test range to characterize path lengths of greater than 1 km.

Innovative Facet Passivation for High-Brightness Laser Diodes

DTIC Science & Technology

2016-02-05

and anti-reflection (AR) coatings are deposited after cleaving. Edge- emitting laser diodes emit very high optical powers from small emission areas, as...SECURITY CLASSIFICATION OF: The objective of this effort is to increase the power of low fill-factor (20%) laser diode (LD) bars from the present...2012 16-Nov-2015 Approved for Public Release; Distribution Unlimited Final Report: Innovative Facet Passivation for High-Brightness Laser Diodes The

High-power laser diodes at various wavelengths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Emanuel, M.A.

High power laser diodes at various wavelengths are described. First, performance and reliability of an optimized large transverse mode diode structure at 808 and 941 nm are presented. Next, data are presented on a 9.5 kW peak power array at 900 nm having a narrow emission bandwidth suitable for pumping Yb:S-FAP laser materials. Finally, results on a fiber-coupled laser diode array at {approx}730 nm are presented.

120W, NA_0.15 fiber coupled LD module with 125-μm clad/NA 0.22 fiber by spatial coupling method

NASA Astrophysics Data System (ADS)

Ishige, Yuta; Kaji, Eisaku; Katayama, Etsuji; Ohki, Yutaka; Gajdátsy, Gábor; Cserteg, András.

2018-02-01

We have fabricated a fiber coupled semiconductor laser diode module by means of spatial beam combining of single emitter broad area semiconductor laser diode chips in the 9xx nm band. In the spatial beam multiplexing method, the numerical aperture of the output light from the optical fiber increases by increasing the number of laser diodes coupled into the fiber. To reduce it, we have tried the approach to improving assembly process technology. As a result, we could fabricate laser diode modules having a light output power of 120W or more and 95% power within NA of 0.15 or less from a single optical fiber with 125-μm cladding diameter. Furthermore, we have obtained that the laser diode module maintaining high coupling efficiency can be realized even around the fill factor of 0.95. This has been achieved by improving the optical alignment method regarding the fast axis stack pitch of the laser diodes in the laser diode module. Therefore, without using techniques such as polarization combining and wavelength combining, high output power was realized while keeping small numerical aperture. This contributes to a reduction in unit price per light output power of the pumping laser diode module.

Photothermal effect of infrared lasers on ex vivo lamb brain tissues

NASA Astrophysics Data System (ADS)

Özgürün, Baturay; Gülsoy, Murat

2018-02-01

Here, the most suitable infrared laser for a neurosurgery operation is suggested, among 1940-nm thulium fiber, 1470-nm diode, 1070-nm ytterbium fiber and 980-nm diode lasers. Cortical and subcortical ex-vivo lamb brain tissues are exposed to the laser light with the combinations of some laser parameters such as output power, energy density, operation mode (continuous and pulsed-modulated) and operation time. In this way, the greatest ablation efficiency associated with the best neurosurgical laser type can be defined. The research can be divided into two parts; pre-dosimetry and dosimetry studies. The former is used to determine safe operation zones for the dosimetry study by defining coagulation and carbonization onset times for each of the brain tissues. The latter is the main part of this research, and both tissues are exposed to laser irradiation with various energy density levels associated with the output power and operation time. In addition, photo-thermal effects are compared for two laser operation modes, and then coagulation and ablation diameters to calculate the ablation efficiency are measured under a light microscope. Consequently, results are compared graphically and statistically, and it is found that thulium and 1470-nm diode lasers can be utilized as subcortical and cortical tissue ablator devices, respectively.

Comparison of the ablation ability of nucleus pulposus after 1,064 nm Nd:YAG laser and 980 nm diode laser radiation.

PubMed

Yin, Jian; Han, Zhengfeng; Guo, Baofeng; Guo, Han; Zhang, Tongtong; Zeng, Yanjun; Ren, Longxi

2015-07-01

To compare the ablation ability of nucleus pulposus after 1,064 nm Nd:YAG laser and 980 nm diode laser radiation. Goat spine specimen (GSS) was radiated using Nd:YAG laser and 980 nm diode laser and then divided into five groups based on the final energy--200, 400, 600, 800 and 1,000 J groups. The ablation quality of nucleus pulposus after radiation was recorded. The ablation quality of GSS was greater at higher radiation energies in both lasers. When compared at the same energy level, the ablation quality of GSS was greater in 980 nm diode laser than in 1,064 nm Nd:YAG laser. Statistical significance was observed in 200 and 400 J groups (P < 0.05) and in 600, 800 and 1,000 J groups (P < 0.01). Radiation with 980 nm diode laser showed better ablation ability than 1,064 nm Nd:YAG laser.

2.05 µm holmium-doped all-fiber laser diode-pumped at 1.125 µm

NASA Astrophysics Data System (ADS)

Kir'yanov, A. V.; Barmenkov, Y. O.; Villegas Garcia, I.

2017-08-01

We report a holmium-doped all-fiber laser oscillating at ~2.05 µm in continuous wave at direct in-core pumping by a 1.125 µm laser diode. Two types of home-made holmium-doped alumino-germano-silicate fiber (HDF), differentiated in the Ho3+ doping level, were fabricated to implement the laser, for revealing the effect of Ho3+ concentration upon the laser output. Firstly, the fibers were characterized thoroughly from the material and optical viewpoints. Then, laser action with both HDFs was assessed using the simplest Fabry-Perot cavity, assembled by a couple of spectrally adjusted fiber Bragg gratings, also made-in-house. In the best case, when using the lower-doped HDF of proper length (1.4 m), low threshold (~370 mW) and moderate slope efficiency (~13%) of ~2.05 µm lasing were obtained at 1.125 µm diode pumping. Long-term stability, high brightness, low noise, and purely CW operation are shown to be the laser’s attractive features. Yet, when utilizing the heavier-doped HDF, laser output is revealed to be overall worse, with a possible reason being the deteriorating Ho3+ concentration-related effects.

Holographic injection locking of a broad area laser diode via a photorefractive thin-film device.

PubMed

van Voorst, P D; de Wit, M R; Offerhaus, H L; Tay, S; Thomas, J; Peyghambarian, N; Boller, K-J

2007-12-24

We demonstrate locking of a high power broad area laser diode to a single frequency using holographic feedback from a photorefractive polymer thin-film device for the first time. A four-wave mixing setup is used to generate feedback for the broad area diode at the wavelength of the single frequency source (Ti:Sapphire laser) while the spatial distribution adapts to the preferred profile of the broad area diode. The result is an injection-locked broad area diode emitting with a linewidth comparable to the Ti:Sapphire laser.

Management of Oral Lichen Planus by 980 nm Diode Laser

PubMed Central

Derikvand, Nahid; Ghasemi, Seyedeh Sara; Moharami, Mohammad; Shafiei, Ehsan; Chiniforush, Nasim

2017-01-01

Introduction: Oral lichen planus (OLP) is a mucocutaneous disease with uncertain etiology. As the etiology is unknown standard treatment modalities are not available. The traditional and common treatment relies on corticosteroids whether topical or systemic. In recent years, development of lasers made a proper path to use this instrument for treatment of the diseases which are refractory to conventional treatments. Previous studies in this field used CO2, ND:YAG, Excimer and some wavelength of diode lasers for the treatment of different types of lichen planus. Case Report: In this study, we present an OLP case which is treated using 980 nm diode laser. The result was measured by visual analogue scale (VAS) and clinical assessment; as a result, symptoms including pain and soreness started to decrease within a week, and by the end of a month completely subsided; the lesion disappeared totally as well. No recurrence was observed after a month and no side-effect was reported. Conclusion: 980 nm diode laser can be successfully used for treatment of patients with OLP PMID:29123636

Cost-effective wavelength-tunable fiber laser using self-seeding Fabry-Perot laser diode.

PubMed

Yeh, Chien-Hung; Shih, Fu Y; Wang, Chia H; Chow, Chi W; Chi, Sien

2008-01-07

We propose and experimentally demonstrate a continuous wave (CW) tunable-wavelength fiber laser using self-seeding Fabry-Perot laser diode (FP-LD) without optical amplifier inside gain cavity. By employing a tunable bandpass filter (TBF) and a fiber reflected mirror (FRM) within a gain cavity, the fiber laser can lase a single-longitudinal wavelength due to the self-seeding operation. The proposed tunable wavelength laser has a good performance of the output power (> -15 dBm) and optical side-mode suppression ratio (> 40 dB) in the wavelength tuning range of 1533.75 to 1560.95 nm. In addition, the output stabilities of the fiber laser are also investigated.

High temperature semiconductor diode laser pumps for high energy laser applications

NASA Astrophysics Data System (ADS)

Campbell, Jenna; Semenic, Tadej; Guinn, Keith; Leisher, Paul O.; Bhunia, Avijit; Mashanovitch, Milan; Renner, Daniel

2018-02-01

Existing thermal management technologies for diode laser pumps place a significant load on the size, weight and power consumption of High Power Solid State and Fiber Laser systems, thus making current laser systems very large, heavy, and inefficient in many important practical applications. To mitigate this thermal management burden, it is desirable for diode pumps to operate efficiently at high heat sink temperatures. In this work, we have developed a scalable cooling architecture, based on jet-impingement technology with industrial coolant, for efficient cooling of diode laser bars. We have demonstrated 60% electrical-to-optical efficiency from a 9xx nm two-bar laser stack operating with propylene-glycolwater coolant, at 50 °C coolant temperature. To our knowledge, this is the highest efficiency achieved from a diode stack using 50 °C industrial fluid coolant. The output power is greater than 100 W per bar. Stacks with additional laser bars are currently in development, as this cooler architecture is scalable to a 1 kW system. This work will enable compact and robust fiber-coupled diode pump modules for high energy laser applications.

High Power High Efficiency Diode Laser Stack for Processing

NASA Astrophysics Data System (ADS)

Gu, Yuanyuan; Lu, Hui; Fu, Yueming; Cui, Yan

2018-03-01

High-power diode lasers based on GaAs semiconductor bars are well established as reliable and highly efficient laser sources. As diode laser is simple in structure, small size, longer life expectancy with the advantages of low prices, it is widely used in the industry processing, such as heat treating, welding, hardening, cladding and so on. Respectively, diode laser could make it possible to establish the practical application because of rectangular beam patterns which are suitable to make fine bead with less power. At this power level, it can have many important applications, such as surgery, welding of polymers, soldering, coatings and surface treatment of metals. But there are some applications, which require much higher power and brightness, e.g. hardening, key hole welding, cutting and metal welding. In addition, High power diode lasers in the military field also have important applications. So all developed countries have attached great importance to high-power diode laser system and its applications. This is mainly due their low performance. In this paper we will introduce the structure and the principle of the high power diode stack.

Far field beam pattern of one MW combined beam of laser diode array amplifiers for space power transmission

NASA Technical Reports Server (NTRS)

Kwon, Jin H.; Lee, Ja H.

1989-01-01

The far-field beam pattern and the power-collection efficiency are calculated for a multistage laser-diode-array amplifier consisting of about 200,000 5-W laser diode arrays with random distributions of phase and orientation errors and random diode failures. From the numerical calculation it is found that the far-field beam pattern is little affected by random failures of up to 20 percent of the laser diodes with reference of 80 percent receiving efficiency in the center spot. The random differences in phases among laser diodes due to probable manufacturing errors is allowed to about 0.2 times the wavelength. The maximum allowable orientation error is about 20 percent of the diffraction angle of a single laser diode aperture (about 1 cm). The preliminary results indicate that the amplifier could be used for space beam-power transmission with an efficiency of about 80 percent for a moderate-size (3-m-diameter) receiver placed at a distance of less than 50,000 km.

High power multiple wavelength diode laser stack for DPSSL application without temperature control

NASA Astrophysics Data System (ADS)

Hou, Dong; Yin, Xia; Wang, Jingwei; Chen, Shi; Zhan, Yun; Li, Xiaoning; Fan, Yingmin; Liu, Xingsheng

2018-02-01

High power diode laser stack is widely used in pumping solid-state laser for years. Normally an integrated temperature control module is required for stabilizing the output power of solid-state laser, as the output power of the solid-state laser highly depends on the emission wavelength and the wavelength shift of diode lasers according to the temperature changes. However the temperature control module is inconvenient for this application, due to its large dimension, high electric power consumption and extra adding a complicated controlling system. Furthermore, it takes dozens of seconds to stabilize the output power when the laser system is turned on. In this work, a compact hard soldered high power conduction cooled diode laser stack with multiple wavelengths is developed for stabilizing the output power of solid-state laser in a certain temperature range. The stack consists of 5 laser bars with the pitch of 0.43mm. The peak output power of each bar in the diode laser stack reaches as much as 557W and the combined lasing wavelength spectrum profile spans 15nm. The solidstate laser, structured with multiple wavelength diode laser stacks, allows the ambient temperature change of 65°C without suddenly degrading the optical performance.

Treatment of Gingival Hyperpigmentation by Diode Laser for Esthetical Purposes

PubMed Central

El Shenawy, Hanaa M.; Nasry, Sherine A.; Zaky, Ahmed A.; Quriba, Mohamed A. A.

2015-01-01

BACKGROUND: Gingival hyperpigmentation is a common esthetical concern in patients with gummy smile or excessive gingival display. Laser ablation has been recognized recently as the most effective, pleasant and reliable technique. It has the advantage of easy handling, short treatment time, hemostasis, decontamination, and sterilization effect. AIM: In the present study we wanted to explore the efficacy of a 980 nm wavelength diode laser in gingival depigmentation clinically by using both VAS and digital imaging method as means of assessment. METHODS: Diode laser ablation was done for 15 patients who requested cosmetic therapy for melanin pigmented gums. The laser beam delivered by fiberoptic with a diameter of 320 µm, the diode laser system has 980 nm wave lengths and 3 W irradiation powers, in a continuous contact mode in all cases, the entire surface of each pigmented maxillary and mandibular gingiva that required treatment was irradiated in a single session. Clinical examination and digital image analysis were done and the patients were followed up for 3 successive months. RESULTS: There was a statistically significant change in prevalence of bleeding after treatment, as none of the cases showed any signs of bleeding 1 week, 1 month and 3 months after ablation. No statistically significant change was observed in the prevalence of swelling after treatment The VAS evaluation demonstrated that only 4 patients complained of mild pain immediately after the procedure. No pain was perceived from the patients in the rest of the follow up period. There was no statistically significant change in prevalence of pain immediately after treatment compared to pain during treatment. There was a decrease in cases with mild pain after 1 week, 1 month as well as 3 months compared to pain during treatment and immediately after treatment. CONCLUSION: Within the limitations of this study, the use of diode laser was shown to be a safe and effective treatment modality that provides optimal aesthetics with minimal discomfort in patients with gingival hyperpigmentation. PMID:27275269

Fully utilizing high power diode lasers by synergizing diode laser light sources and beam shaping micro-optics

NASA Astrophysics Data System (ADS)

Fan, Yingmin; Wang, Jingwei; Cai, Lei; Mitra, Thomas; Hauschild, Dirk; Zah, Chung-En; Liu, Xingsheng

2018-02-01

High power diode lasers (HPDLs) offer the highest wall-plug efficiency, highest specific power (power-to-weight ratio), arguably the lowest cost and highest reliability among all laser types. However, the poor beam quality of commercially HPDLs is the main bottleneck limiting their direct applications requiring high brightness at least in one dimension. In order to expand the applications of HPDLs, beam shaping and optical design are essential. In this work, we report the recent progresses on maximizing applications of HPDLs by synergizing diode laser light source and beam shaping micro-optics. Successful examples of matching of diode laser light sources and beam shaping micro-optics driving new applications are presented.

Efficacy and safety of a diode laser in second-stage implant surgery: a comparative study.

PubMed

El-Kholey, K E

2014-05-01

For more than a decade, peri-implant tissues have been treated with soft tissue lasers to create a bloodless flap for implant placement and to uncover implants with minimal bleeding, trauma, and anaesthesia. This study was designed to assess if dental implant uncovering is possible with a diode laser without anaesthesia, and to compare its performance with traditional cold scalpel surgery. Thirty patients with a total of 45 completely osseointegrated implants participated in this study. Patients were divided into two groups. For the study group, second-stage implant surgery was done with a 970nm diode laser. For the control group, the implants were exposed with a surgical blade. Certain parameters were used for evaluation of the two techniques. The use of the diode laser obviated the need for local anaesthesia; there was a significant difference between the two groups regarding the need for anaesthesia (P<0.0001). However, there were no significant differences between the two techniques regarding duration of surgery, postoperative pain, time for healing, and success of the implants. The diode laser can be used effectively for second-stage implant surgery, providing both the dentist and the patient with additional advantages over the conventional methods used for implant exposure. Copyright © 2013 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

450 nm diode laser: A new help in oral surgery.

PubMed

Fornaini, Carlo; Rocca, Jean-Paul; Merigo, Elisabetta

2016-09-16

To describe the performance of 450 nm diode laser in oral surgery procedures. The case described consisted of the removal of a lower lip fibroma through a blue diode laser (λ = 450 nm). The efficacy of this device, even at very low power (1W, CW), allows us to obtain very high intra and postoperative comfort for the patient, even with just topical anaesthesia and without needing suture. The healing process was completed in one week and, during the follow-up, the patient did not report any problems, pain or discomfort even without the consumption of any kind of drugs, such as painkillers and antibiotics. The histological examination performed by the pathologist showed a large area of fibrous connective tissue with some portions of epithelium-connective detachments and a regular incision with very scanty areas of carbonization. The 450 nm diode laser proved of being very efficient in the oral soft tissue surgical procedures, with no side effects for the patients.

Disruptive laser diode source for embedded LIDAR sensors

NASA Astrophysics Data System (ADS)

Canal, Celine; Laugustin, Arnaud; Kohl, Andreas; Rabot, Olivier

2017-02-01

Active imaging based on laser illumination is used in various fields such as medicine, security, defense, civil engineering and in the automotive sector. In this last domain, research and development to bring autonomous vehicles on the roads has been intensified these last years with an emphasis on lidar technology that is probably the key to achieve full automation level. Based on time-of-flight measurements, the profile of objects can be measured together with their location in various conditions, creating a 3D mapping of the environment. To be embedded on a vehicle as advanced driver assistance systems (ADAS), these sensors require compactness, low-cost and reliability, as it is provided by a flash lidar. An attractive candidate, especially with respect to cost reduction, for the laser source integrated in these devices is certainly laser diodes as long as they can provide sufficiently short pulses with a high energy. A recent breakthrough in laser diode and diode driver technology made by Quantel (Les Ulis, France) now allows laser emission higher than 1 mJ with pulses as short as 12 ns in a footprint of 4x5 cm2 (including both the laser diode and driver) and an electrical-to-optical conversion efficiency of the whole laser diode source higher than 25% at this level of energy. The components used for the laser source presented here can all be manufactured at low cost. In particular, instead of having several individual laser diodes positioned side by side, the laser diodes are monolithically integrated on a single semiconductor chip. The chips are then integrated directly on the driver board in a single assembly step. These laser sources emit in the range of 800-1000 nm and their emission is considered to be eye safe when taking into account the high divergence of the output beam and the aperture of possible macro lenses so that they can be used for end consumer applications. Experimental characterization of these state-of-the-art pulsed laser diode sources will be given. Future work leads will be discussed for miniaturization of the laser diode and drastic cost reduction.

Comparison between single-diode low-level laser therapy (LLLT) and LED multi-diode (cluster) therapy (LEDT) applications before high-intensity exercise.

PubMed

Leal Junior, Ernesto Cesar Pinto; Lopes-Martins, Rodrigo Alvaro Brandão; Baroni, Bruno Manfredini; De Marchi, Thiago; Rossi, Rafael Paolo; Grosselli, Douglas; Generosi, Rafael Abeche; de Godoi, Vanessa; Basso, Maira; Mancalossi, José Luis; Bjordal, Jan Magnus

2009-08-01

There is anecdotal evidence that low-level laser therapy (LLLT) may affect the development of muscular fatigue, minor muscle damage, and recovery after heavy exercises. Although manufacturers claim that cluster probes (LEDT) maybe more effective than single-diode lasers in clinical settings, there is a lack of head-to-head comparisons in controlled trials. This study was designed to compare the effect of single-diode LLLT and cluster LEDT before heavy exercise. This was a randomized, placebo-controlled, double-blind cross-over study. Young male volleyball players (n = 8) were enrolled and asked to perform three Wingate cycle tests after 4 x 30 sec LLLT or LEDT pretreatment of the rectus femoris muscle with either (1) an active LEDT cluster-probe (660/850 nm, 10/30 mW), (2) a placebo cluster-probe with no output, and (3) a single-diode 810-nm 200-mW laser. The active LEDT group had significantly decreased post-exercise creatine kinase (CK) levels (-18.88 +/- 41.48 U/L), compared to the placebo cluster group (26.88 +/- 15.18 U/L) (p < 0.05) and the active single-diode laser group (43.38 +/- 32.90 U/L) (p < 0.01). None of the pre-exercise LLLT or LEDT protocols enhanced performance on the Wingate tests or reduced post-exercise blood lactate levels. However, a non-significant tendency toward lower post-exercise blood lactate levels in the treated groups should be explored further. In this experimental set-up, only the active LEDT probe decreased post-exercise CK levels after the Wingate cycle test. Neither performance nor blood lactate levels were significantly affected by this protocol of pre-exercise LEDT or LLLT.

Orofacial hereditary haemorrhagic telangiectasia: high power diode laser in early and advanced lesion treatment

NASA Astrophysics Data System (ADS)

Tempesta, Angela; Franco, Simonetta; Miccoli, Simona; Suppressa, Patrizia; De Falco, Vincenzo; Crincoli, Vito; Lacaita, Mariagrazia; Giuliani, Michele; Favia, Gianfranco

2014-01-01

Hereditary Haemorrhagic Telangiectasia (HHT) is a muco-cutaneous inherited disease. Symptoms are epistaxis, visceral arterio-venous malformations, multiple muco-cutaneous telangiectasia with the risk of number increasing enlargement, bleeding, and super-infection. The aim of this work is to show the dual Diode Laser efficacy in preventive treatment of Early Lesions (EL < 2mm) and therapeutic treatment of Advanced Lesions (AL < 2mm). 21 patients affected by HHT with 822 muco-cutaneous telangiectatic nodules have been treated in several sessions with local anaesthesia and cooling of treated sites. EL preventive treatment consists of single Laser impulse (fibre 320) in ultrapulsed mode (2 mm single point spot). AL therapeutic treatment consists of repeated Laser impulses in pulsed mode (on 200ms / off 400ms). According to the results, Diode Laser used in pulsed and ultra-pulsed mode is very effective as noninvasive treatment both in early and advanced oral and perioral telangiectasia.

Robust modeling and performance analysis of high-power diode side-pumped solid-state laser systems.

PubMed

Kashef, Tamer; Ghoniemy, Samy; Mokhtar, Ayman

2015-12-20

In this paper, we present an enhanced high-power extrinsic diode side-pumped solid-state laser (DPSSL) model to accurately predict the dynamic operations and pump distribution under different practical conditions. We introduce a new implementation technique for the proposed model that provides a compelling incentive for the performance assessment and enhancement of high-power diode side-pumped Nd:YAG lasers using cooperative agents and by relying on the MATLAB, GLAD, and Zemax ray tracing software packages. A large-signal laser model that includes thermal effects and a modified laser gain formulation and incorporates the geometrical pump distribution for three radially arranged arrays of laser diodes is presented. The design of a customized prototype diode side-pumped high-power laser head fabricated for the purpose of testing is discussed. A detailed comparative experimental and simulation study of the dynamic operation and the beam characteristics that are used to verify the accuracy of the proposed model for analyzing the performance of high-power DPSSLs under different conditions are discussed. The simulated and measured results of power, pump distribution, beam shape, and slope efficiency are shown under different conditions and for a specific case, where the targeted output power is 140 W, while the input pumping power is 400 W. The 95% output coupler reflectivity showed good agreement with the slope efficiency, which is approximately 35%; this assures the robustness of the proposed model to accurately predict the design parameters of practical, high-power DPSSLs.

Reliability of High Power Laser Diode Arrays Operating in Long Pulse Mode

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin; Meadows, Byron L.; Barnes, Bruce W.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.; Baker, Nathaniel R.

2006-01-01

Reliability and lifetime of quasi-CW laser diode arrays are greatly influenced by their thermal characteristics. This paper examines the thermal properties of laser diode arrays operating in long pulse duration regime.

Natural gas pipeline leak detector based on NIR diode laser absorption spectroscopy.

PubMed

Gao, Xiaoming; Fan, Hong; Huang, Teng; Wang, Xia; Bao, Jian; Li, Xiaoyun; Huang, Wei; Zhang, Weijun

2006-09-01

The paper reports on the development of an integrated natural gas pipeline leak detector based on diode laser absorption spectroscopy. The detector transmits a 1.653 microm DFB diode laser with 10 mW and detects a fraction of the backscatter reflected from the topographic targets. To eliminate the effect of topographic scatter targets, a ratio detection technique was used. Wavelength modulation and harmonic detection were used to improve the detection sensitivity. The experimental detection limit is 50 ppmm, remote detection for a distance up to 20 m away topographic scatter target is demonstrated. Using a known simulative leak pipe, minimum detectable pipe leak flux is less than 10 ml/min.

Green high-power tunable external-cavity GaN diode laser at 515  nm.

PubMed

Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

2016-09-15

A 480 mW green tunable diode laser system is demonstrated for the first time to our knowledge. The laser system is based on a GaN broad-area diode laser and Littrow external-cavity feedback. The green laser system is operated in two modes by switching the polarization direction of the laser beam incident on the grating. When the laser beam is p-polarized, an output power of 50 mW with a tunable range of 9.2 nm is achieved. When the laser beam is s-polarized, an output power of 480 mW with a tunable range of 2.1 nm is obtained. This constitutes the highest output power from a tunable green diode laser system.

Targeting doxorubicin encapsulated in stealth liposomes to solid tumors by non thermal diode laser.

PubMed

Ghannam, Magdy M; El Gebaly, Reem; Fadel, Maha

2016-04-05

The use of liposomes as drug delivery systems is the most promising technique for targeting drug especially for anticancer therapy. In this study sterically stabilized liposomes was prepared from DPPC/Cholesterol/PEG-PE encapsulated doxorubicin. The effect of lyophilization on liposomal stability and hence expiration date were studied. Moreover, the effect of diode laser on the drug released from liposomesin vitro and in vivo in mice carrying implanted solid tumor were also studied. The results indicated that lyophilization of the prepared liposomes encapsulating doxorubicin led to marked stability when stored at 5 °C and it is possible to use the re-hydrated lyophilized liposomes within 12 days post reconstitution. Moreover, the use of low energy diode laser for targeting anticancer drug to the tumor cells is a promising method in cancer therapy. We can conclude that lyophilization of the liposomes encapsulating doxorubicin lead to marked stability for the liposomes when stored at 5 °C. Moreover, the use of low energy diode laser for targeting anticancer drug to the tumor cells through the use of photosensitive sterically stabilized liposomes loaded with doxorubicin is a promising method. It proved to be applicable and successful for treatment of Ehrlich solid tumors implanted in mice and eliminated toxic side effects of doxorubicin.

Safety and efficacy of low fluence, high repetition rate versus high fluence, low repetition rate 810-nm diode laser for axillary hair removal in Chinese women.

PubMed

Li, Wenhai; Liu, Chengyi; Chen, Zhou; Cai, Lin; Zhou, Cheng; Xu, Qianxi; Li, Houmin; Zhang, Jianzhong

2016-11-01

High-fluence diode lasers with contact cooling have emerged as the gold standard to remove unwanted hair. Lowering the energy should result in less pain and could theoretically affect the efficacy of the therapy. To compare the safety and efficacy of a low fluence high repetition rate 810-nm diode laser to those of a high fluence, low repetition rate diode laser for permanent axillary hair removal in Chinese women. Ninety-two Chinese women received four axillae laser hair removal treatments at 4-week intervals using the low fluence, high repetition rate 810-nm diode laser in super hair removal (SHR) mode on one side and the high fluence, low repetition rate diode laser in hair removal (HR) mode on the other side. Hair counts were done at each follow-up visit and 6-month follow-up after the final laser treatment using a "Hi Quality Hair Analysis Program System"; the immediate pain score after each treatment session was recorded by a visual analog scale. The overall median reduction of hair was 90.2% with the 810-nm diode laser in SHR mode and 87% with the same laser in HR mode at 6-month follow-up. The median pain scores in SHR mode and in HR mode were 2.75 and 6.75, respectively. Low fluence, high repetition rate diode laser can efficiently remove unwanted hair but also significantly improve tolerability and reduce adverse events during the course of treatment.

GreenLight laser vs diode laser vaporization of the prostate: 3-year results of a prospective nonrandomized study.

PubMed

Guo, Sanwei; Müller, Georg; Bonkat, Gernot; Püschel, Heike; Gasser, Thomas; Bachmann, Alexander; Rieken, Malte

2015-04-01

Laser vaporization of the prostate is one of the alternatives to transurethral resection of the prostate. Short-term studies report a comparable outcome after laser vaporization with the 532 nm 120-W GreenLight high-performance system (HPS) laser and the 980 nm 200 W high-intensity diode (diode) laser. In this study, we analyzed the intermediate-term results of both techniques. From January 2007 to January 2008, 112 consecutive patients with symptomatic benign prostate enlargement were nonrandomly assigned to treatment with the GreenLight laser or the diode laser. Perioperative parameters, postoperative functional outcome, complications, and the reoperation rate at 3 years were analyzed. Improvement of voiding symptoms (International Prostate Symptom Score, quality-of-life) and micturition parameters (maximum flow rate, postvoid residual volume) showed no significant difference between the HPS group and the diode group. A significantly higher reoperation rate was observed in the diode group in comparison to the HPS group (37.5% vs 8.9%, p=0.0003) due to obstructive necrotic tissue (16.1% vs 0%, p=0.0018), bladder neck stricture (16.1% vs 1.8%, p=0.008), and persisting or recurrent adenoma (5.4% vs 7.1%, p=0.70), respectively. Both lasers lead to comparable improvement of voiding parameters and micturition symptoms. Treatment with the 200 W diode laser led to a significantly higher reoperation rate, which might be attributed to a higher degree of coagulation necrosis. Thus, a careful clinical application of this diode laser type is warranted.

Polarization/Spatial Combining of Laser-Diode Pump Beams

NASA Technical Reports Server (NTRS)

Gelsinger, Paul; Liu, Duncan

2008-01-01

A breadboard version of an optical beam combiner is depicted which make it possible to use the outputs of any or all of four multimode laser diodes to pump a non-planar ring oscillator (NPRO) laser. The output of each laser diode has a single-mode profile in the meridional plane containing an axis denoted the 'fast' axis and a narrower multimode profile in the orthogonal meridional plane, which contains an axis denoted the 'slow' axis and a narrower multimode profile in the orthogonal meridional plane, which contains an axis denoted the 'slow' axis. One of the purposes served by the beam-combining optics is to reduce the fast-axis numerical aperture (NA) of the laser-diode output to match the NA of the optical fiber. Along the slow axis, the unmodified laser-diode NA is already well matched to the fiber optic NA, so no further slow-axis beam shaping is needed. In this beam combiner, the laser-diode outputs are collimated by aspherical lenses, then half-wave plates and polarizing beam splitters are used to combine the four collimated beams into two beams. Spatial combination of the two beams and coupling into the optical fiber is effected by use of anamorphic prisms, mirrors, and a focusing lens. The anamorphic prisms are critical elements in the NA-matching scheme, in that they reduce the fast-axis beam width to 1/6 of its original values. Inasmuch as no slow-axis beam shaping is needed, the collimating and focusing lenses are matched for 1:1 iumaging. Because these lenses are well corrected for infinite conjugates the combiner offers diffraction-limited performance along both the fast and slow axes.

Diode laser (808 nm) applied to oral soft tissue lesions: a retrospective study to assess histopathological diagnosis and evaluate physical damage.

PubMed

Angiero, Francesca; Parma, Luisa; Crippa, Rolando; Benedicenti, Stefano

2012-03-01

The diode laser is today widely used in oral pathology to excise lesions; however, some controversy surrounds laser surgery, specifically the accuracy of pathological diagnosis and the control over thermal tissue damage. This study aimed to establish if physical damage induced by the diode laser could affect the histopathological diagnosis and to evaluate the damage caused to the resection margins. Between 2005 and 2010, at S. Gerardo Hospital, Milan, 608 cases of soft tissue lesions localized in the oral cavity (cheek, gingiva, buccal mucosa, tongue, and lips) were examined. Specimens were excised with an 808-nm diode laser, output 1.6-2.7 W, in continuous-wave mode with fibers of 320 μm. Specimens were fixed in 10% buffered formalin solution and examined separately under an optical microscope by two pathologists. In all of the specimens, changes to the epithelium, connective tissue and blood vessels, shape of incision damage, and overall width of modified tissues were evaluated. The data for specimens larger than 3 mm excised with the diode laser were not significant in terms of stromal changes or vascular stasis, while epithelial and stromal changes were significantly more frequent in specimens with a mean size below 3 mm; the diagnosis was not achievable in 46.15%. Our data show that the diode laser is a valid therapeutic instrument for excising oral lesions larger than 3 mm in diameter, but induces serious thermal effects in small lesions (mean size below 3 mm). However, from a clinical standpoint, it is suggested necessary that the specimens taken have in vivo a diameter of at least 5 mm in order to have a reliable reading of the histological sample.

Subthreshold Diode Micropulse Laser Photocoagulation (SDM) as Invisible Retinal Phototherapy for Diabetic Macular Edema: A Review

PubMed Central

Luttrull, Jeffrey K; Dorin, Giorgio

2012-01-01

Purpose: To present the state-of-the-art of subthreshold diode laser micropulse photocoagulation (SDM) as invisible retinal phototherapy for diabetic macular edema (DME). Method: To review the role and evolution of retinal laser treatment for DME. Results: Thermal laser retinal photocoagulation has been the cornerstone of treatment for diabetic macular edema for over four decades. Throughout, laser induced retinal damage produced by conventional photocoagulation has been universally accepted as necessary to produce a therapeutic benefit, despite the inherent risks, adverse effects and limitations of thermally destructive treatment. Recently, SDM, performed as invisible retinal phototherapy for DME, has been found to be effective in the absence of any retinal damage or adverse effect, fundamentally altering our understanding of laser treatment for retinal disease. Summary: The discovery of clinically effective and harmless SDM treatment for DME offers exciting new information that will improve our understanding of laser treatment for retinal disease, expand treatment indications, and improve patient outcomes. PMID:22587512

Diverse effects of a 445 nm diode laser on isometric contraction of the rat aorta

PubMed Central

Park, Sang Woong; Shin, Kyung Chul; Park, Hyun Ji; Lee, In Wha; Kim, Hyung-Sik; Chung, Soon-Cheol; Kim, Ji-Sun; Jun, Jae-Hoon; Kim, Bokyung; Bae, Young Min

2015-01-01

The usefulness of visible lasers in treating vascular diseases is controversial. It is probable that multiple effects of visible lasers on blood vessels and their unclear mechanisms have hampered the usefulness of this therapy. Therefore, elucidating the precise actions and mechanisms of the effects of lasers on blood vessels would provide insight into potential biomedical applications. Here, using organ chamber isometric contraction measurements, western blotting, patch-clamp, and en face immunohistochemistry, we showed that a 445 nm diode laser contracted rat aortic rings, both by activating endothelial nitric oxide synthase and by increasing oxidative stress. In addition to the effects on the endothelium, the laser also directly relaxed and contracted vascular smooth muscle by inhibiting L-type Ca2+ channels and by activating protein tyrosine kinases, respectively. Thus, we conclude that exposure to 445 nm laser might contract and dilate blood vessels in the endothelium and smooth muscle via distinct mechanisms. PMID:26417517

Subthreshold diode micropulse laser photocoagulation (SDM) as invisible retinal phototherapy for diabetic macular edema: a review.

PubMed

Luttrull, Jeffrey K; Dorin, Giorgio

2012-07-01

To present the state-of-the-art of subthreshold diode laser micropulse photocoagulation (SDM) as invisible retinal phototherapy for diabetic macular edema (DME). To review the role and evolution of retinal laser treatment for DME. Thermal laser retinal photocoagulation has been the cornerstone of treatment for diabetic macular edema for over four decades. Throughout, laser induced retinal damage produced by conventional photocoagulation has been universally accepted as necessary to produce a therapeutic benefit, despite the inherent risks, adverse effects and limitations of thermally destructive treatment. Recently, SDM, performed as invisible retinal phototherapy for DME, has been found to be effective in the absence of any retinal damage or adverse effect, fundamentally altering our understanding of laser treatment for retinal disease. The discovery of clinically effective and harmless SDM treatment for DME offers exciting new information that will improve our understanding of laser treatment for retinal disease, expand treatment indications, and improve patient outcomes.

Self-tuning method for monitoring the density of a gas vapor component using a tunable laser

DOEpatents

Hagans, Karla; Berzins, Leon; Galkowski, Joseph; Seng, Rita

1996-01-01

The present invention relates to a vapor density monitor and laser atomic absorption spectroscopy method for highly accurate, continuous monitoring of vapor densities, composition, flow velocity, internal and kinetic temperatures and constituent distributions. The vapor density monitor employs a diode laser, preferably of an external cavity design. By using a diode laser, the vapor density monitor is significantly less expensive and more reliable than prior art vapor density monitoring devices. In addition, the compact size of diode lasers enables the vapor density monitor to be portable. According to the method of the present invention, the density of a component of a gas vapor is calculated by tuning the diode laser to a frequency at which the amount of light absorbed by the component is at a minimum or a maximum within about 50 MHz of that frequency. Laser light from the diode laser is then transmitted at the determined frequency across a predetermined pathlength of the gas vapor. By comparing the amount of light transmitted by the diode laser to the amount of light transmitted after the laser light passes through the gas vapor, the density of the component can be determined using Beer's law.

Self-tuning method for monitoring the density of a gas vapor component using a tunable laser

DOEpatents

Hagans, K.; Berzins, L.; Galkowski, J.; Seng, R.

1996-08-27

The present invention relates to a vapor density monitor and laser atomic absorption spectroscopy method for highly accurate, continuous monitoring of vapor densities, composition, flow velocity, internal and kinetic temperatures and constituent distributions. The vapor density monitor employs a diode laser, preferably of an external cavity design. By using a diode laser, the vapor density monitor is significantly less expensive and more reliable than prior art vapor density monitoring devices. In addition, the compact size of diode lasers enables the vapor density monitor to be portable. According to the method of the present invention, the density of a component of a gas vapor is calculated by tuning the diode laser to a frequency at which the amount of light absorbed by the component is at a minimum or a maximum within about 50 MHz of that frequency. Laser light from the diode laser is then transmitted at the determined frequency across a predetermined pathlength of the gas vapor. By comparing the amount of light transmitted by the diode laser to the amount of light transmitted after the laser light passes through the gas vapor, the density of the component can be determined using Beer`s law. 6 figs.

High-temperature CW and pulsed operation in constricted double-heterojunction AlGaAs diode lasers

NASA Technical Reports Server (NTRS)

Botez, D.; Connolly, J. C.; Gilbert, D. B.

1981-01-01

The behavior of constricted double-heterojunction (CDH) diode lasers has been investigated up to 170 C CW and 270 C pulsed. It is found that the temperature-dependent current concentration effect responsible for low threshold-current sensitivity and temperature-invariant external differential quantum efficiency in CDH lasers saturates at about 100 C. It is also found that over a wide temperature interval (180-280 C) the threshold current density has a To value of 40-50 C and that the spontaneous emission becomes increasingly sublinear above 220 C. Both effects are believed to reflect Auger recombination.

Temperature changes accompanying near infrared diode laser endodontic treatment of wet canals.

PubMed

Hmud, Raghad; Kahler, William A; Walsh, Laurence J

2010-05-01

Diode laser endodontic treatments such as disinfection or the generation of cavitations should not cause deleterious thermal changes in radicular dentin. This study assessed thermal changes in the root canal and on the root surface when using 940 and 980 nm lasers at settings of 4 W/10 Hz and 2.5 W/25 Hz, respectively, delivered into 2000-mum fibers to generate cavitations in water. The root surface temperature in the apical third was recorded, as was the water temperature in coronal, middle, and apical third regions, by using thermocouples placed inside the canal. Lasing was undertaken with either rest periods or rinsing between 5-second laser exposures. Both diode lasers induced only modest temperature changes on the external root surface at the settings used. Even though the temperature of the water within the canal increased during lasing by as much as 30 degrees C, the external root surface temperature increased by only a maximum of 4 degrees C. Irrigation between laser exposures was highly effective in minimizing thermal changes within the root canal and on the root surface. Diode laser parameters that induce cavitation do not result in adverse thermal changes in radicular dentin. Copyright (c) 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Fixed, low radiant exposure vs. incremental radiant exposure approach for diode laser hair reduction: a randomized, split axilla, comparative single-blinded trial.

PubMed

Pavlović, M D; Adamič, M; Nenadić, D

2015-12-01

Diode lasers are the most commonly used treatment modalities for unwanted hair reduction. Only a few controlled clinical trials but not a single randomized controlled trial (RCT) compared the impact of various laser parameters, especially radiant exposure, onto efficacy, tolerability and safety of laser hair reduction. To compare the safety, tolerability and mid-term efficacy of fixed, low and incremental radiant exposures of diode lasers (800 nm) for axillary hair removal, we conducted an intrapatient, left-to-right, patient- and assessor-blinded and controlled trial. Diode laser (800 nm) treatments were evaluated in 39 study participants (skin type II-III) with unwanted axillary hairs. Randomization and allocation to split axilla treatments were carried out by a web-based randomization tool. Six treatments were performed at 4- to 6-week intervals with study subjects blinded to the type of treatment. Final assessment of hair reduction was conducted 6 months after the last treatment by means of blinded 4-point clinical scale using photographs. The primary endpoint was reduction in hair growth, and secondary endpoints were patient-rated tolerability and satisfaction with the treatment, treatment-related pain and adverse effects. Excellent reduction in axillary hairs (≥ 76%) at 6-month follow-up visit after receiving fixed, low and incremental radiant exposure diode laser treatments was obtained in 59% and 67% of study participants respectively (Z value: 1.342, P = 0.180). Patients reported lower visual analogue scale (VAS) pain score on the fixed (4.26) than on the incremental radiant exposure side (5.64) (P < 0.0003). The only side-effect was mild and transient erythema. Subjects better tolerated the fixed, low radiant exposure protocol (P = 0.03). The majority of the study participants were satisfied with both treatments. Both low and incremental radiant exposures produced similar hair reduction and high and comparable patient satisfaction. However, low radiant exposure diode laser treatments were less painful and better tolerated. © 2015 European Academy of Dermatology and Venereology.

Active mode-locked operation of a diode pumped colour-centre laser

NASA Astrophysics Data System (ADS)

Mazighi, K.; Doualan, J. L.; Hamel, J.; Margerie, J.; Mounier, D.; Ostrovsky, A.

1991-09-01

The cw laser diode pumping of an (F +2) ∗ colour centre laser has been recently demonstrated in our laboratory. The intensity of the pumping diode can easily be hf modulated. We present here the first experiments in which the colour centre laser is synchronously pumped at the mode spacing frequency, resulting in the emission of clean, regularly spaced pulses. The opto-electronic feedback is a very promising method of obtaining such a pulsed operation of a diode pumped colour centre laser without the use of an external hf oscillator.

Fiber optic coupling of a microlens conditioned, stacked semiconductor laser diode array

DOEpatents

Beach, Raymond J.; Benett, William J.; Mills, Steven T.

1997-01-01

The output radiation from the two-dimensional aperture of a semiconductor laser diode array is efficiently coupled into an optical fiber. The two-dimensional aperture is formed by stacking individual laser diode bars on top of another in a "rack and stack" configuration. Coupling into the fiber is then accomplished using individual microlenses to condition the output radiation of the laser diode bars. A lens that matches the divergence properties and wavefront characteristics of the laser light to the fiber optic is used to focus this conditioned radiation into the fiber.

Coherent addition of high power broad-area laser diodes with a compact VBG V-shaped external Talbot cavity

DOE PAGES

Liu, Bo; Braiman, Yehuda

2018-02-06

In this paper, we introduced a compact V-shaped external Talbot cavity for phase locking of high power broad-area laser diodes. The length of compact cavity is ~25 mm. Near diffraction-limit coherent addition of 10 broad-area laser diodes indicated that high quality phase locking was achieved. We measured the near-field emission mode of each individual broad-area laser diode with different feedback, such as a volume Bragg grating and a high reflection mirror. Finally, we found out that the best result of phase locking broad-area laser diodes was achieved by the compact V-shaped external Talbot cavity with volume Bragg grating feedback.

Coherent addition of high power broad-area laser diodes with a compact VBG V-shaped external Talbot cavity

NASA Astrophysics Data System (ADS)

Liu, Bo; Braiman, Yehuda

2018-05-01

We introduced a compact V-shaped external Talbot cavity for phase locking of high power broad-area laser diodes. The length of compact cavity is ∼25 mm. Near diffraction-limit coherent addition of 10 broad-area laser diodes indicated that high quality phase locking was achieved. We measured the near-field emission mode of each individual broad-area laser diode with different feedback, such as a volume Bragg grating and a high reflection mirror. We found out that the best result of phase locking broad-area laser diodes was achieved by the compact V-shaped external Talbot cavity with volume Bragg grating feedback.

Research and Development of Laser Diode Based Instruments for Applications in Space

NASA Technical Reports Server (NTRS)

Krainak, Michael; Abshire, James; Cornwell, Donald; Dragic, Peter; Duerksen, Gary; Switzer, Gregg

1999-01-01

Laser diode technology continues to advance at a very rapid rate due to commercial applications such as telecommunications and data storage. The advantages of laser diodes include, wide diversity of wavelengths, high efficiency, small size and weight and high reliability. Semiconductor and fiber optical-amplifiers permit efficient, high power master oscillator power amplifier (MOPA) transmitter systems. Laser diode systems which incorporate monolithic or discrete (fiber optic) gratings permit single frequency operation. We describe experimental and theoretical results of laser diode based instruments currently under development at NASA Goddard Space Flight Center including miniature lidars for measuring clouds and aerosols, water vapor and wind for Earth and planetary (Mars Lander) use.

High brightness laser-diode device emitting 160 watts from a 100 μm/NA 0.22 fiber.

PubMed

Yu, Junhong; Guo, Linui; Wu, Hualing; Wang, Zhao; Tan, Hao; Gao, Songxin; Wu, Deyong; Zhang, Kai

2015-11-10

A practical method of achieving a high-brightness and high-power fiber-coupled laser-diode device is demonstrated both by experiment and ZEMAX software simulation, which is obtained by a beam transformation system, free-space beam combining, and polarization beam combining based on a mini-bar laser-diode chip. Using this method, fiber-coupled laser-diode module output power from the multimode fiber with 100 μm core diameter and 0.22 numerical aperture (NA) could reach 174 W, with equalizing brightness of 14.2  MW/(cm2·sr). By this method, much wider applications of fiber-coupled laser-diodes are anticipated.

Coherent addition of high power broad-area laser diodes with a compact VBG V-shaped external Talbot cavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Bo; Braiman, Yehuda

In this paper, we introduced a compact V-shaped external Talbot cavity for phase locking of high power broad-area laser diodes. The length of compact cavity is ~25 mm. Near diffraction-limit coherent addition of 10 broad-area laser diodes indicated that high quality phase locking was achieved. We measured the near-field emission mode of each individual broad-area laser diode with different feedback, such as a volume Bragg grating and a high reflection mirror. Finally, we found out that the best result of phase locking broad-area laser diodes was achieved by the compact V-shaped external Talbot cavity with volume Bragg grating feedback.

Modular package for cooling a laser diode array

DOEpatents

Mundinger, David C.; Benett, William J.; Beach, Raymond J.

1992-01-01

A laser diode array is disclosed that includes a plurality of planar packages and active cooling. The laser diode array may be operated in a long duty cycle, or in continuous operation. A laser diode bar and a microchannel heat sink are thermally coupled in a compact, thin planar package having the laser diode bar located proximate to one edge. In an array, a number of such thin planar packages are secured together in a stacked configuration, in close proximity so that the laser diodes are spaced closely. The cooling means includes a microchannel heat sink that is attached proximate to the laser bar so that it absorbs heat generated by laser operation. To provide the coolant to the microchannels, each thin planar package comprises a thin inlet manifold and a thin outlet manifold connected to an inlet corridor and an outlet corridor. The inlet corridor comprises a hole extending through each of the packages in the array, and the outlet corridor comprises a hole extending through each of the packages in the array. The inlet and outlet corridors are connected to a conventional coolant circulation system. The laser diode array with active cooling has application as an optical pump for high power solid state lasers. Further, it can be incorporated in equipment such as communications devices and active sensors, and in military and space applications, and it can be useful in applications having space constraints and energy limitations.

Ultra-narrow band diode lasers with arbitrary pulse shape modulation (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ryasnyanskiy, Aleksandr I.; Smirnov, Vadim; Mokhun, Oleksiy; Glebov, Alexei L.; Glebov, Leon B.

2017-03-01

Wideband emission spectra of laser diode bars (several nanometers) can be largely narrowed by the usage of thick volume Bragg gratings (VBGs) recorded in photo-thermo-refractive glass. Such narrowband systems, with GHz-wide emission spectra, found broad applications for Diode Pumped Alkali vapor Lasers, optically pumped rare gas metastable lasers, Spin Exchange Optical Pumping, atom cooling, etc. Although the majority of current applications of narrow line diode lasers require CW operation, there are a variety of fields where operation in a different pulse mode regime is necessary. Commercial electric pulse generators can provide arbitrary current pulse profiles (sinusoidal, rectangular, triangular and their combinations). The pulse duration and repetition rate however, have an influence on the laser diode temperature, and therefore, the emitting wavelength. Thus, a detailed analysis is needed to understand the correspondence between the optical pulse profiles from a diode laser and the current pulse profiles; how the pulse profile and duty cycle affects the laser performance (e.g. the wavelength stability, signal to noise ratio, power stability etc.). We present the results of detailed studies of the narrowband laser diode performance operating in different temporal regimes with arbitrary pulse profiles. The developed narrowband (16 pm) tunable laser systems at 795 nm are capable of operating in different pulse regimes while keeping the linewidth, wavelength, and signal-to-noise ratio (>20 dB) similar to the corresponding CW modules.

Low level diode laser accelerates wound healing.

PubMed

Dawood, Munqith S; Salman, Saif Dawood

2013-05-01

The effect of wound illumination time by pulsed diode laser on the wound healing process was studied in this paper. For this purpose, the original electronic drive circuit of a 650-nm wavelength CW diode laser was reconstructed to give pulsed output laser of 50 % duty cycle and 1 MHz pulse repetition frequency. Twenty male mice, 3 months old were used to follow up the laser photobiostimulation effect on the wound healing progress. They were subdivided into two groups and then the wounds were made on the bilateral back sides of each mouse. Two sessions of pulsed laser therapy were carried along 15 days. Each mice group wounds were illuminated by this pulsed laser for 12 or 18 min per session during these 12 days. The results of this study were compared with the results of our previous wound healing therapy study by using the same type of laser. The mice wounds in that study received only 5 min of illumination time therapy in the first and second days of healing process. In this study, we found that the wounds, which were illuminated for 12 min/session healed in about 3 days earlier than those which were illuminated for 18 min/session. Both of them were healed earlier in about 10-11 days than the control group did.

Pulpal response following photo-biomodulation with a 904-nm diode laser: a double-blind clinical study.

PubMed

Liang, Ryan; George, Roy; Walsh, Laurence J

2016-12-01

The aim of this study was to evaluate pulpal responses in healthy human teeth to photo-biomodulation therapy (PBMT) with 904-nm GaAs diode laser. The study followed a double-blind split mouth design, with a randomly selected maxillary first premolar acting as a sham-irradiated control tooth, and the contralateral tooth receiving active laser treatment. Two coded but otherwise identical laser probes (Irradia™, SpectraMedics Ltd., NC, USA) were used to deliver the sham (placebo) and laser radiation, with both the operator and patient unaware of each probe's identity. The selection of teeth for sham or laser irradiation was randomised for each treatment. Pulpal responses were assessed using electric pulp testing (EPT), 2 min prior to exposure, and immediately after laser irradiation (60 s, 30 mW average power, 25 Hz pulse frequency, 3.6 J/cm 2 ). Treatment effects were analysed using the Wilcoxon-signed rank test. A total of 30 participants provided written informed consent. Majority of the participants (66.7 %) demonstrated an analgesic effect following PBMT (elevated EPT scores); however, nine participants (30 %) reported the lower EPT scores than the control. Both the treatment effects (stimulation and analgesia) were significant compared to the placebo. In most individuals, PBMT of healthy teeth with a 904-nm GaAs diode laser can induce analgesia, as witnessed by elevated EPT scores. A converse effect can occur in a minority of subjects.

Determination of temperature and residual laser energy on film fiber-optic thermal converter for diode laser surgery.

PubMed

Liu, Weichao; Kong, Yaqun; Shi, Xiafei; Dong, Xiaoxi; Wang, Hong; Zhao, Jizhi; Li, Yingxin

2017-12-01

The diode laser was utilized in soft tissue incision of oral surgery based on the photothermic effect. The contradiction between the ablation efficiency and the thermal damage has always been in diode laser surgery, due to low absorption of its radiation in the near infrared region by biological tissues. Fiber-optic thermal converters (FOTCs) were used to improve efficiency for diode laser surgery. The purpose of this study was to determine the photothermic effect by the temperature and residual laser energy on film FOTCs. The film FOTC was made by a distal end of optical fiber impacting on paper. The external surface of the converter is covered by a film contained amorphous carbon. The diode laser with 810 nm worked at the different rated power of 1.0 W, 1.5 W, 2.0 W, 3.0 W, 4.0 W, 5.0 W, 6.0 W, 7.0 W, 8.0 W in continuous wave (CW)and pulse mode. The temperature of the distal end of optical fiber was recorded and the power of the residual laser energy from the film FOTC was measured synchronously. The temperature, residual power and the output power were analyzed by linear or exponential regression model and Pearson correlations analysis. The residual power has good linearity versus output power in CW and pulse modes (R 2  = 0.963, P < 0.01 for both). The temperature on film FOTCs increases exponentially with adjusted R 2  = 0.959 in continuous wave mode, while in pulsed mode with adjusted R 2  = 0.934. The temperature was elevated up to about 210 °C and eventually to be a stable state. Film FOTCs centralized approximately 50% of laser energy on the fiber tip both in CW and pulsed mode while limiting the ability of the laser light to interact directly with target tissue. Film FOTCs can concentrate part of laser energy transferred to heat on distal end of optical fiber, which have the feasibility of improving efficiency and reducing thermal damage of deep tissue.

Diode Laser Measurements of Concentration and Temperature in Microgravity Combustion

NASA Technical Reports Server (NTRS)

Silver, Joel A.; Kane, Daniel J.

1999-01-01

Diode laser absorption spectroscopy provides a direct method of determinating species concentration and local gas temperature in combustion flames. Under microgravity conditions, diode lasers are particularly suitable, given their compact size, low mass and low power requirements. The development of diode laser-based sensors for gas detection in microgravity is presented, detailing measurements of molecular oxygen. Current progress of this work and future application possibilities for these methods on the International Space Station are discussed.

A randomised controlled trial of coblation, diode laser and cold dissection in paediatric tonsillectomy.

PubMed

Elbadawey, M R; Hegazy, H M; Eltahan, A E; Powell, J

2015-11-01

This study aimed to compare the efficacy of diode laser, coblation and cold dissection tonsillectomy in paediatric patients. A total of 120 patients aged 10-15 years with recurrent tonsillitis were recruited. Participants were prospectively randomised to diode laser, coblation or cold dissection tonsillectomy. Operative time and blood loss were recorded. Pain was recorded on a Wong-Baker FACES(®) pain scale. The operative time (10 ± 0.99 minutes), blood loss (20 ± 0.85 ml) and pain were significantly lower with coblation tonsillectomy than with cold dissection tonsillectomy (20 ± 1.0 minutes and 30 ± 1.0 ml; p = 0.0001) and diode laser tonsillectomy (15 ± 0.83 minutes and 25 ± 0.83 ml; p = 0.0001). Diode laser tonsillectomy had a shorter operative time (p = 0.0001) and less blood loss (p = 0.001) compared with cold dissection tonsillectomy. However, at post-operative day seven, the diode laser tonsillectomy group had significantly higher pain scores compared with the cold dissection (p = 0.042) and coblation (p = 0.04) tonsillectomy groups. Both coblation and diode laser tonsillectomy are associated with significantly reduced blood loss and shorter operative times compared with cold dissection tonsillectomy. However, we advocate coblation tonsillectomy because of the lower post-operative pain scores compared with diode laser and cold dissection tonsillectomy.

Active stabilization of a diode laser injection lock.

PubMed

Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep

2016-06-01

We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser's transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399 nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.

Passive harmonic mode locking by mode selection in Fabry-Perot diode lasers with patterned effective index.

PubMed

Bitauld, David; Osborne, Simon; O'Brien, Stephen

2010-07-01

We demonstrate passive harmonic mode locking of a quantum-well laser diode designed to support a discrete comb of Fabry-Perot modes. Spectral filtering of the mode spectrum was achieved using a nonperiodic patterning of the cavity effective index. By selecting six modes spaced at twice the fundamental mode spacing, near-transform-limited pulsed output with 2 ps pulse duration was obtained at a repetition rate of 100 GHz.

Efficient single-mode (TEM{sub 00}) Nd : YVO{sub 4} laser with longitudinal 808-nm diode pumping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donin, V I; Yakovin, D V; Yakovin, M D

2013-10-31

A single-mode Nd : YVO{sub 4} laser with unidirectional longitudinal pumping by laser diodes with λ = 808 nm and a power of 40 W is studied. In the TEM{sub 00} mode, the output laser power is 24 W with the optical efficiency η{sub opt} = 57.1 % (slope efficiency 63.3 %), which, as far as we know, is the best result for Nd{sup 3+} : YVO{sub 4} lasers with longitudinal pumping at λ = 808 nm from one face of the active crystal. Estimates of thermal effects show that, using a Nd : YVO{sub 4} crystal (length 20 mm,more » diameter 3 mm, dopant concentration 0.27 at%) with two undoped ends and bidirectional diode pumping with a total power of 170 W, one can obtain an output power of ∼100 W in the TEM{sub 00} mode from one active element. (lasers)« less

Cultured Human Fibroblast Biostimulation Using a 940 nm Diode Laser

PubMed Central

Illescas-Montes, Rebeca; Melguizo-Rodríguez, Lucía; Manzano-Moreno, Francisco Javier; García-Martínez, Olga; Ruiz, Concepción

2017-01-01

Background: Fibroblasts are the main cells involved in regeneration during wound healing. The objective was to determine the effect of 940 nm diode laser on cultured human fibroblasts using different irradiation regimens. Methods: The CCD-1064Sk human epithelial fibroblast cell line was treated with a 940 nm diode laser at different energy doses (power: 0.2–1 W and energy density: 1–7 J/cm2) using different transmission modes (continuous or pulsed). The effect on cell growth at 24 and 72 h post-treatment was examined by measuring the proliferative capacity, the impact on the cell cycle, and the effect on cell differentiation. Results: fibroblast proliferative capacity was increased at 24 and 72 h post-treatment as a function of the energy dose. The greatest increase was observed with a power of 0.2 or 0.5 W and energy density between 1 and 4 J/cm2; no difference was observed between continuous and pulsed modes. There were no significant differences in cell cycle between treated groups and controls. α-actin expression was increased by treatment, indicating enhanced cell differentiation. Conclusion: The 940 nm diode laser has biostimulating effects on fibroblasts, stimulating proliferative capacity and cell differentiation without altering the cell cycle. Further researches are necessary to explore its potential clinical usefulness in wound healing. PMID:28773152

High density, optically corrected, micro-channel cooled, v-groove monolithic laser diode array

DOEpatents

Freitas, Barry L.

1998-01-01

An optically corrected, micro-channel cooled, high density laser diode array achieves stacking pitches to 33 bars/cm by mounting laser diodes into V-shaped grooves. This design will deliver>4kW/cm2 of directional pulsed laser power. This optically corrected, micro-channel cooled, high density laser is usable in all solid state laser systems which require efficient, directional, narrow bandwidth, high optical power density pump sources.

High speed visible light communication using blue GaN laser diodes

NASA Astrophysics Data System (ADS)

Watson, S.; Viola, S.; Giuliano, G.; Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Targowski, G.; Watson, M. A.; White, H.; Rowe, D.; Laycock, L.; Kelly, A. E.

2016-10-01

GaN-based laser diodes have been developed over the last 20 years making them desirable for many security and defence applications, in particular, free space laser communications. Unlike their LED counterparts, laser diodes are not limited by their carrier lifetime which makes them attractive for high speed communication, whether in free space, through fiber or underwater. Gigabit data transmission can be achieved in free space by modulating the visible light from the laser with a pseudo-random bit sequence (PRBS), with recent results approaching 5 Gbit/s error free data transmission. By exploiting the low-loss in the blue part of the spectrum through water, data transmission experiments have also been conducted to show rates of 2.5 Gbit/s underwater. Different water types have been tested to monitor the effect of scattering and to see how this affects the overall transmission rate and distance. This is of great interest for communication with unmanned underwater vehicles (UUV) as the current method using acoustics is much slower and vulnerable to interception. These types of laser diodes can typically reach 50-100 mW of power which increases the length at which the data can be transmitted. This distance could be further improved by making use of high power laser arrays. Highly uniform GaN substrates with low defectivity allow individually addressable laser bars to be fabricated. This could ultimately increase optical power levels to 4 W for a 20-emitter array. Overall, the development of GaN laser diodes will play an important part in free space optical communications and will be vital in the advancement of security and defence applications.

Non-ablative 1,450-nm diode laser treatment of striae distensae.

PubMed

Tay, Yong-Kwang; Kwok, Colin; Tan, Eileen

2006-03-01

Striae distensae are dermal scars with flattening and atrophy of the epidermis. Successful treatment of these stretch marks has been disappointing. The non-ablative 1,450-nm diode laser has been shown to improve atrophic scars and may be expected to improve striae. As yet, no study has been published to document the effects of this laser on striae. Our aim is to evaluate the efficacy of the 1,450-nm diode laser in the treatment of striae rubra and striae alba in Asian patients with skin types 4-6. Striae on one half of the body in 11 patients were treated with the 1,450-nm diode laser with cryogen cooling spray with the other half serving as a control. The following parameters were used: 6 mm spot size and dynamic cooling device (DCD) for 40 milliseconds to protect the epidermis. Patients were randomly assigned to receive either 4, 8, or 12 J/cm2. A total of three treatments were given at 6-week intervals. The following sites were treated: abdomen, arms, back, buttocks, and thighs. Two patients had striae rubra and nine striae alba. Clinical photographs were taken before and after each treatment and analysis was undertaken through photographic evaluation by non-treating physicians. At 2 months after the last treatment, no patients showed any noticeable improvement in the striae on the treated side compared to baseline and to the control areas. Side effects were limited to transient erythema and postinflammatory hyperpigmentation (PIH), which occurred in seven (64%) patients. The non-ablative 1,450-nm diode laser is not useful in the treatment of striae in patients with skin types 4, 5, and 6. 2006 Wiley-Liss, Inc.

Nanoscale effects on the thermal and mechanical properties of AlGaAs/GaAs quantum well laser diodes: influence on the catastrophic optical damage

NASA Astrophysics Data System (ADS)

Souto, Jorge; Pura, José Luis; Jiménez, Juan

2017-06-01

In this work we study the catastrophic optical damage (COD) of graded-index separate confinement heterostructure quantum well (QW) laser diodes based on AlGaAs/GaAs. The emphasis is placed on the impact that the nanoscale physical properties have on the operation and degradation of the active layers of these devices. When these laser diodes run in continuous-wave mode with high internal optical power densities, the QW and guide layers can experiment very intense local heating phenomena that lead to device failure. A thermo-mechanical model has been set up to study the mechanism of degradation. This model has been solved by applying finite element methods. A variety of physical factors related to the materials properties, which play a paramount role in the laser degradation process, have been considered. Among these, the reduced thicknesses of the QW and the guides lead to thermal conductivities smaller than the bulk figures, which are further reduced as extended defects develop in these layers. This results in a progressively deteriorating thermal management in the device. To the best of our knowledge, this model for laser diodes is the first one to have taken into account low scale mechanical effects that result in enhanced strengths in the structural layers. Moreover, the consequences of these conflicting size-dependent properties on the thermo-mechanical behaviour on the route to COD are examined. Subsequently, this approach opens the possibility of taking advantage of these properties in order to design robust diode lasers (or other types of power devices) in a controlled manner.

Long-term clinical evaluation of a 800-nm long-pulsed diode laser with a large spot size and vacuum-assisted suction for hair removal.

PubMed

Ibrahimi, Omar A; Kilmer, Suzanne L

2012-06-01

The long-pulsed diode (800-810-nm) laser is one of the most commonly used and effective lasers for hair removal. Limitations of currently available devices include a small treatment spot size, treatment-associated pain, and the need for skin cooling. To evaluate the long-term hair reduction capabilities of a long-pulsed diode laser with a large spot size and vacuum assisted suction. Thirty-five subjects were enrolled in a prospective, self-controlled, single-center study of axillary hair removal. The study consisted of three treatments using a long-pulsed diode laser with a large spot size and vacuum-assisted suction at 4- to 6-week intervals with follow-up visits 6 and 15 months after the last treatment. Hair clearance was quantified using macro hair-count photographs taken at baseline and at 6- and 15-month follow-up visits. Changes in hair thickness and color, levels of treatment-associated pain, and adverse events were additional study endpoints. There was statistically significant hair clearance at the 6 (54%) and 15-month (42%) follow-up visits. Remaining hairs were thinner and lighter at the 15-month follow-up visit, and the majority of subjects reported feeling up to mild to moderate pain during treatment without the use of pretreatment anesthesia or skin cooling. A long-pulsed diode laser with a large spot size and vacuum-assisted suction is safe and effective for long-term hair removal. This is the largest prospective study to evaluate long-term hair removal and the first to quantify decreases in hair thickness and darkness with treatment. © 2012 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Degradation phenomena in laser diodes

NASA Astrophysics Data System (ADS)

Beister, G.; Krispin, P.; Maege, J.; Richter, G.; Weber, H.; Rechenberg, I.

1988-11-01

Accelerated tests on GaAlAs/GaAs double heterostructure laser diodes showed, in agreement with earlier results on light-emitting diodes, that ageing appeared in three distinct forms: initial and slow degradation stages, both obeying a logarithmic time dependence, and a superimposed "gradation" (enhancement of the output power). Measurements made by the method of deep level transient spectroscopy during the accelerated tests on these lasers, operated as light-emitting diodes, revealed the appearance right from the beginning of B levels attributed to the antisite GaAs defects. The B levels appeared again in diodes tested in the lasing mode. In the case of a group of 21 laser diodes the mean time-to-failure was 9000 h at 70°C for 5 mW (in accordance with the Weibull statistics of degradation rates).

Paramecium: a promising non-animal bioassay to study the effect of 808 nm infrared diode laser photobiomodulation.

PubMed

Amaroli, Andrea; Parker, Steven; Dorigo, Gianluca; Benedicenti, Alberico; Benedicenti, Stefano

2015-01-01

Photobiostimulation and photobiomodulation (PBM) are terms applied to the manipulation of cellular behavior using low intensity light sources, which works on the principle of inducing a biological response through energy transfer. The aim of this investigation was to identify a laboratory assay to test the effect of an infrared diode laser light (808 nm) on cell fission rate. Sixty cells of Paramecium primaurelia were divided in two groups of 30. The first group (test group) was irradiated, at a temperature of 24°C, for 50 sec by a 808 nm diode laser with a flat top handpiece [1 cm of spot diameter, 1 W in continuous wave (CW), 50 sec irradiation time, 64 J/cm(2) of fluence]. The second group (control group) received no laser irradiation. All cells were transferred onto a depression slide, fed, and incubated in a moist chamber at a temperature of 24°C. The cells were exposed and monitored for 10 consecutive fission rates. Changes in temperature and pH were also evaluated. The exposed cells had a fission rate rhythm faster than the control cells, showing a binary fission significantly (p<0.05) shorter than unexposed cells. No significant effects of laser irradiation on pH and temperature of Paramecium's lettuce infusion medium were observed. The 808 nm infrared diode laser light, at the irradiation parameters used in our work, results in a precocious fission rate in P. primaurelia cells, probably through an increase in metabolic activity, secondary to an energy transfer.

Evaluation of diode laser and stannous fluoride in the treatment of root sensitivity after access flap surgery: Randomized controlled clinical trial.

PubMed

Raut, Chetan Purushottam; Sethi, Kunal Sunder; Kohale, Bhagyashree; Mamajiwala, Alefiya; Warang, Ayushya

2018-01-01

Postsurgical root sensitivity has always been an enigma to the periodontists. There is a plethora of evidence suggesting the presence of root sensitivity following periodontal flap surgical procedures. Thus, the aim of the present study was to compare and evaluate the effect of low-power diode lasers with and without topical application of stannous fluoride (SnF 2 ) gel in the treatment of root sensitivity and also evaluate whether laser creates any placebo effect in the control group or not. Thirty patients participated in this study and 99 teeth were included. Root sensitivity was assessed for all groups with a Verbal Rating Scale (VRS). For each patient, the teeth were randomized into three groups. In the test Group I, sensitive teeth were treated with SnF 2 and diode laser. In the test Group II, sensitive teeth were irradiated with laser only. In the control group, no treatment was performed. The mean ± standard deviation (SD) score for VRS and Visual Analog Scale at baseline was not statistically significant ( P > 0.05) between the three groups. After 15 min, statistical significant difference was seen in test Group I and test Group II, although no difference was found in the control group. At 15 th day and 30 th day, the mean ± SD scores were statistically significant ( P < 0.05). Within the limitations of the study, it can be concluded that diode lasers alone and in combination with 0.4% SnF 2 was effective in the treatment of root sensitivity after access flap surgery.

Injection locking of a high power ultraviolet laser diode for laser cooling of ytterbium atoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hosoya, Toshiyuki; Miranda, Martin; Inoue, Ryotaro

2015-07-15

We developed a high-power laser system at a wavelength of 399 nm for laser cooling of ytterbium atoms with ultraviolet laser diodes. The system is composed of an external cavity laser diode providing frequency stabilized output at a power of 40 mW and another laser diode for amplifying the laser power up to 220 mW by injection locking. The systematic method for optimization of our injection locking can also be applied to high power light sources at any other wavelengths. Our system does not depend on complex nonlinear frequency-doubling and can be made compact, which will be useful for providing light sources formore » laser cooling experiments including transportable optical lattice clocks.« less

The effect of diode laser and topical steroid on serum level of TNF-alpha in oral lichen planus patients.

PubMed

Othman, Nagwa-Abdelhamid; Shaker, Olfat-Gamil; Elshenawy, Hanaa-Mohamed; Abd-Elmoniem, Wessam; Eldin, Amany-Mohy; Fakhr, Mariam-Yehia

2016-12-01

Oral lichen planus (OLP) is a common chronic inflammatory mucosal disease with a multifactorial etiology. It is a T-cell mediated autoimmune disease in which the cytotoxic CD8+T cells trigger apoptosis of the basal cells of oral epithelium. Various treatment regimens have been employed for management of symptomatic OLP. This study was carried out to evaluate the effect of topical steroids as well as laser on the clinical signs and symptoms detected by reticular, atrophic, erosive score (RAE score) and tumor necrosis factor- α (TNF-α) level in the serum of patients with symptomatic OLP. The study was conducted on twenty-four patients (18 females and 6 males) with symptomatic OLP that were allocated into two groups. Each included twelve patients. The first group treated either with diode laser (970nm SIROLaser Advance class IIIb, SIRONA The Dental Company, Germany) twice weekly with maximum of ten sessions while the second group were treated with topical corticosteroids (0.1% triamcinolone acetonide orabase, Kenacort-A Orabase Pomad, DEVA HOLDING A.Ș, Istanbul, Turkey) for four weeks. Corticosteroids group showed less clinical signs and symptoms of reticular, atrophic, erosive RAE score ( p =0.02) and TNF-α serum level ( p =0.028) than diode laser group with no reported therapy side effects or complications in any of the treated patients. Topical steroids reduce pain, reticular, atrophic, erosive RAE score and TNF-α serum level more than laser treatment. Moreover, laser treatment can be used as an alternative treatment when steroids are contraindicated for the treatment of symptomatic OLP. Key words: Oral lichen planus, diode laser, topical steroid, RAE score, TNF-α.

Thermal effects of λ = 808 nm GaAlAs diode laser irradiation on different titanium surfaces.

PubMed

Giannelli, Marco; Lasagni, Massimo; Bani, Daniele

2015-12-01

Diode lasers are widely used in dental laser treatment, but little is known about their thermal effects on different titanium implant surfaces. This is a key issue because already a 10 °C increase over the normal body temperature can induce bone injury and compromise osseo-integration. The present study aimed at evaluating the temperature changes and surface alterations experienced by different titanium surfaces upon irradiation with a λ = 808 nm diode laser with different settings and modalities. Titanium discs with surfaces mimicking different dental implant surfaces including TiUnite and anodized, machined surfaces were laser-irradiated in contact and non-contact mode, and with and without airflow cooling. Settings were 0.5-2.0 W for the continuous wave mode and 10-45 μJ, 20 kHz, 5-20 μs for the pulsed wave mode. The results show that the surface characteristics have a marked influence on temperature changes in response to irradiation. The TiUnite surface, corresponding to the osseous interface of dental implants, was the most susceptible to thermal rise, while the machined surfaces, corresponding to the implant collar, were less affected. In non-contact mode and upon continuous wave emission, the temperature rose above the 50 °C tissue damage threshold. Scanning electron microscopy investigation of surface alterations revealed that laser treatment in contact mode resulted in surface scratches even when no irradiation was performed. These findings indicate that the effects of diode laser irradiation on implant surfaces depend on physical features of the titanium coating and that in order to avoid thermal or physical damage to implant surface the irradiation treatment has to be carefully selected.

High power diode lasers emitting from 639 nm to 690 nm

NASA Astrophysics Data System (ADS)

Bao, L.; Grimshaw, M.; DeVito, M.; Kanskar, M.; Dong, W.; Guan, X.; Zhang, S.; Patterson, J.; Dickerson, P.; Kennedy, K.; Li, S.; Haden, J.; Martinsen, R.

2014-03-01

There is increasing market demand for high power reliable red lasers for display and cinema applications. Due to the fundamental material system limit at this wavelength range, red diode lasers have lower efficiency and are more temperature sensitive, compared to 790-980 nm diode lasers. In terms of reliability, red lasers are also more sensitive to catastrophic optical mirror damage (COMD) due to the higher photon energy. Thus developing higher power-reliable red lasers is very challenging. This paper will present nLIGHT's released red products from 639 nm to 690nm, with established high performance and long-term reliability. These single emitter diode lasers can work as stand-alone singleemitter units or efficiently integrate into our compact, passively-cooled Pearl™ fiber-coupled module architectures for higher output power and improved reliability. In order to further improve power and reliability, new chip optimizations have been focused on improving epitaxial design/growth, chip configuration/processing and optical facet passivation. Initial optimization has demonstrated promising results for 639 nm diode lasers to be reliably rated at 1.5 W and 690nm diode lasers to be reliably rated at 4.0 W. Accelerated life-test has started and further design optimization are underway.

Space Qualification of Laser Diode Arrays

NASA Technical Reports Server (NTRS)

Troupaki, Elisavet; Kashem, Nasir B.; Allan, Graham R.; Vasilyev, Aleksey; Stephen, Mark

2005-01-01

Laser instruments have great potential in enabling a new generation of remote-sensing scientific instruments. NASA s desire to employ laser instruments aboard satellites, imposes stringent reliability requirements under severe conditions. As a result of these requirements, NASA has a research program to understand, quantify and reduce the risk of failure to these instruments when deployed on satellites. Most of NASA s proposed laser missions have base-lined diode-pumped Nd:YAG lasers that generally use quasi-constant wave (QCW), 808 nm Laser Diode Arrays (LDAs). Our group has an on-going test program to measure the performance of these LDAs when operated in conditions replicating launch and orbit. In this paper, we report on the results of tests designed to measure the effect of vibration loads simulating launch into space and the radiation environment encountered on orbit. Our primary objective is to quantify the performance of the LDAs in conditions replicating those of a satellite instrument, determine their limitations and strengths which will enable better and more robust designs. To this end we have developed a systematic testing strategy to quantify the effect of environmental stresses on the optical and electrical properties of the LDA.

Effects of Different Polarization Strategies on Laser Cutting with Direct Diode Lasers

NASA Astrophysics Data System (ADS)

Rodrigues, G. Costa; Duflou, J. R.

As Direct Diode Lasers are introduced as an emerging technology for laser cutting of metal sheets, new challenges arise. The relatively low beam quality remains a limitation to the maximum cutting speed. One way to balance this may be a strategic use of laser polarization in order to influence laser material interaction in the cutting kerf. In this paper the effects of cross-, linear-, radial- and azimuthal- laser beam polarization arrangements are studied with both Fusion and Flame cutting at an output power of approximately 750W. Different combinations of materials and thicknesses were cut and the maximum cutting speed and edge quality analyzed. It is found that at similar cutting edge quality, improvements in cutting speed can go up to 40% with an inert gas, such as Nitrogen, and up to 20% with a reactive gas, such as Oxygen, in agreement with analytical models for absorption previously developed by the authors.

Kerr-lens mode-locked Ti:Sapphire laser pumped by a single laser diode

NASA Astrophysics Data System (ADS)

Kopylov, D. A.; Esaulkov, M. N.; Kuritsyn, I. I.; Mavritskiy, A. O.; Perminov, B. E.; Konyashchenko, A. V.; Murzina, T. V.; Maydykovskiy, A. I.

2018-04-01

The performance of a Ti:sapphire laser pumped by a single 461 nm laser diode is presented for both the continuous-wave and the mode-locked regimes of operation. We introduce a simple astigmatism correction scheme for the laser diode beam consisting of two cylindrical lenses affecting the pump beam along the fast axis of the laser diode, which provides the mode-matching between the nearly square-shaped pump beam and the cavity mode. The resulting efficiency of the suggested Ti:Sapphire oscillator pumped by such a laser diode is analyzed for the Ti:sapphire crystals of 3 mm, 5 mm and 10 mm in length. We demonstrate that such a system provides the generation of ultrashort pulses up to 15 fs in duration with the repetition rate of 87 MHz, the average power being 170 mW.

Photonic Breast Tomography and Tumor Aggressiveness Assessment

DTIC Science & Technology

2012-07-01

c) Raw Image 11 The entrance face of the slab sample (source plane) was illuminated by a 100-mW 790-nm diode laser beam. The multi-source...schematically shown in Figure 6. A 10mW 785 nm diode laser beam was used to illuminate the first sample, while a 100mW 785 nm diode laser beam was used for the...signal transmitting narrow-band filter; TS = translation stage; CCD = charge cou- pled device; and PC = computer. Continuous wave 790-nm diode laser

Investigation of Diode Pumped Alkali Laser Atmospheric Transmission Using Tunable Diode Laser Absorption Spectroscopy

DTIC Science & Technology

2012-09-01

atmosphere”. Applied Physics B: Lasers and Optics, 82(1):133–140, 2006. 11. Barrass, S., Y. Grard, R.J. Holdsworth, and P.A. Martin . “Near-infrared tun...15. Brown, M. S., S. Williams, C. D. Lindstrom , and D. L. Barone. Progress in Applying Tunable Diode Laser Absorption Spectroscopy to Scramjet

Diode laser-assisted endoscopic dacryocystorhinostomy: a comparison of three different combinations of adjunctive procedures.

PubMed

Dogan, Remzi; Meric, Aysenur; Ozsütcü, Mustafa; Yenigun, Alper

2013-08-01

Chronic dacryocystitis is a frequently encountered condition which can be corrected by dacryocystorhinostomy. Today, the diode laser is increasingly put to use in such corrective operations. This study aims to answer the questions of which adjunctive procedures and which combinations of such procedures are necessary and effective in securing more successful outcomes in diode laser dacryocystorhinostomy. This prospective randomized study included eighty patients (13 male, 67 female) who underwent dacryocystorhinostomy in our hospital during the 2 year period of January 2009-January 2011. The patients were selected consecutively and were randomly allocated to three groups. Group 1 (30): diode laser + mitomycin C + silicone intubation; Group 2 (27): diode laser + silicone intubation; Group 3 (23): diode laser + mitomycin C. All patients were evaluated postoperatively on day 1, week 1, and on the 1st, 3rd, 6th, 12th, 18th, and 24th months. The postoperative evaluation consisted of preoperative and postoperative ostium measurements, recording postoperative complications, and calculating and comparing success rates and operative times. The mean ages of the patients were 63.4 for Group 1, 60.7 for Group 2, and 61.8 for Group 3. No statistically significant difference was found among the groups regarding pre- and postoperative ostium measurements. The success rates were 84.3, 80, and 76.9 % for Groups 1, 2, and 3, respectively. Complications noted in Group 1 were restenosis (3), premature silicone tube loss (1), development of granulation tissue (3), synechia (2), infection (2), and hemorrhage (3). Those for Group 2 were restenosis (5), premature tube loss (2), granulation (8), synechia (6), infection (3), and hemorrhage (4). Group 3 had 6 cases with stenosis, 5 with granulation, 3 with infection, 6 with synechia, and 5 with hemorrhage. The operative times of the groups were 25.5, 15.3, and 18.1 min, respectively, for Group 1, 2, and 3. All three groups had statistically significant differences regarding the duration of surgery, with p < 0.001, p < 0.001, and p = 0.002 for Group 1 and 2, Group 1 and 3, and Group 2 and 3, respectively. Our study showed that when diode laser DCR was combined with bicanalicular silicone intubation and intraoperative mitomycin C application, those adjunctive procedures, while increasing operative time, enhanced the success rate and diminished complications as compared to diode laser plus intubation and/or diode laser plus mitomycin C.

Investigations of large area electron beam diodes for excimer lasers. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1993-12-31

This report summarizes the results of a one year research program at the University of Michigan to investigate the physics and technology of microsecond electron beam diodes. These experiments were performed on the Michigan Electron Long Beam Accelerator (MELBA) at parameters: Voltage {equals} {minus}0.65 to {minus}0.9 MV, current {equals} 1 {minus}50 kA, and pulselength {equals} 0.5 {minus} 5 microseconds. Major accomplishments include: (1) the first two-wavelength (CO2 and HeNe) laser deflection measurements of diode plasma and neutrals; (2) measurements of the effects on magnetic field gradient on microsecond diode closure; (3) demonstration of good fidelity of processed x-ray signals asmore » a diagnostic of beam voltage; (4) extended-pulselength scaling of electron beam diode arcing and diode closure; and (5) innovative Cerenkov plate diagnostics of e-beam dynamics.« less

Diode-pumped solid state lasers (DPSSLs) for Inertial Fusion Energy (IFE)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krupke, W.F.

The status of diode-pumped, transverse-gas-flow cooled, Yb-S-FAP slab lasers is reviewed. Recently acquired experimental performance data are combined with a cost/performance IFE driver design code to define a cost-effective development path for IFE DPSSL drivers. Specific design parameters are described for the Mercury 100J/10 Hz, 1 kW system (first in the development scenario).

700 W blue fiber-coupled diode-laser emitting at 450 nm

NASA Astrophysics Data System (ADS)

Balck, A.; Baumann, M.; Malchus, J.; Chacko, R. V.; Marfels, S.; Witte, U.; Dinakaran, D.; Ocylok, S.; Weinbach, M.; Bachert, C.; Kösters, A.; Krause, V.; König, H.; Lell, A.; Stojetz, B.; Löffler, A.; Strauss, U.

2018-02-01

A high-power blue laser source was long-awaited for processing materials with low absorption in the near infrared (NIR) spectral range like copper or gold. Due to the huge progress of GaN-based semiconductors, the performance of blue diode-lasers has made a major step forward recently. With the availability of unprecedented power levels at cw-operating blue diode-lasers emitting at 450 nm, it was possible to set up a high-power diode-laser in the blue spectral range to address these conventional laser applications and probably beyond that to establish completely new utilizations for lasers. Within the scope of the research project "BlauLas", funded within the German photonic initiative "EFFILAS" [8] by the German Federal Ministry of Education and Research (BMBF), Laserline in cooperation with OSRAM aims to realize a cw fiber-coupled diode-laser exceeding 1 kW blue laser power. In this paper the conceptual design and experimental results of a 700 W blue fiber-coupled diode-laser are presented. Initially a close look had to be taken on the mounting techniques of the semiconductors to serve the requirements of the GaN laser diodes. Early samples were used for extensive long term tests to investigate degradation processes. With first functional laser-modules we set up fiber-coupled laser-systems for further testing. Besides adaption of well-known optical concepts a main task within the development of the laser system was the selection and examination of suitable materials and assembling in order to minimize degradation and reach adequate lifetimes. We realized R&D blue lasersystems with lifetimes above 5,000 h, which enable first application experiments on processing of various materials as well as experiments on conversion to white-light.

Photobiomodulation by Infrared Diode Laser: Effects on Intracellular Calcium Concentration and Nitric Oxide Production of Paramecium.

PubMed

Amaroli, Andrea; Benedicenti, Alberico; Ferrando, Sara; Parker, Steven; Selting, Wayne; Gallus, Lorenzo; Benedicenti, Stefano

2016-11-01

In Paramecium, cilia beating is correlated to intracellular calcium concentration ([Ca 2+ ]i) and nitric oxide (NO) synthesis. Recent findings affirm that photobiomodulation (PBM) can transiently increase the [Ca 2+ ]i in mammalian cells. In this study, we investigated the effect of both 808 and 980 nm diode laser irradiated with flat-top hand-piece on [Ca 2+ ]i and NO production of Paramecium primaurelia, to provide basic information for the development of new therapeutic approaches. In the experiments, the laser power in CW varied (0.1; 0.5; 1; and 1.5 W) to generate the following respective fluences: 6.4; 32; 64; and 96 J cm -2 . The 6.4 J cm -2 did not induce PBM if irradiated by both 808 and 980 nm diode laser. Conversely, the 32 J cm -2 fluence had no effect on Paramecium cells if irradiated by the 808 nm laser, while if irradiated by the 980 nm laser induced increment in swimming speed (suggesting an effect on the [Ca 2+ ]i, NO production, similar to the 64 J cm -2 with the 808 nm wavelength). The more evident discordance occurred with the 96 J cm -2 fluence, which had the more efficient effect on PBM among the parameters if irradiated with the 808 nm laser and killed the Paramecium cells if irradiated by the 980 nm laser. Lastly, the 980 nm and 64 or 96 J cm -2 were the only parameters to induce a release of stored calcium. © 2016 The American Society of Photobiology.

The effectiveness of laser diode induction to Carica Papaya L. chlorophyll extract to be ROS generating in the photodynamic inactivation mechanisms for C.albicans biofilms

NASA Astrophysics Data System (ADS)

Dewi Astuty, S.; Baktir, A.

2017-05-01

Research on the effectiveness of photo inactivation of C.albicans biofilms led by a-PDT system mediated by chlorophyll-diode-laser-induced was done. This research was done using in vitro technique in order to effectively determine chlorophyll extract of ROS-generated Carica Papaya L. using in situ technique. This technique induced laser diode on different dose and C. albicans with reduced degree. This research is a preliminary study in efforts to find anew sensitizer agent candidate made of chlorophyll extract and antifungal of Carica Papaya L. The effectiveness of eradication has been tested with MDA’s content and OD of biomass biofilms as well as analyzed using ANOVA and Tukey Test (α=0.05). The characteristic of chlorophyll extract of Carica Papaya L. has maximum absorptions on blue areas (λmax = 420 nm) and red areas (λmax = 670 nm). The MIC value of Carica Papaya L.’schlorophyll extract against C. albicans planktonic and biofilms cell is 63.8 μM and 31.9 μM respectively. The result shows that treatment using laser which was combined with chlorophyll extract is more effective than that with laser only or chlorophyll extract only. The treatment using laser combined with chlorophyll extract obtained more than 65% (α=0.05) (more than that of negative control) for P2L1 group with OD595 0.915. The MDA’s content showed that group of laser which was mediated with chlorophyll extract had larger values than group of laser or chlorophyll extract only.

Status of 2 micron laser technology program

NASA Technical Reports Server (NTRS)

Storm, Mark

1991-01-01

The status of 2 micron lasers for windshear detection is described in viewgraph form Theoretical atmospheric and instrument system studies have demonstrated that the 2.1 micron Ho:YAG lasers can effectively measure wind speeds in both wet and dry conditions with accuracies of 1 m/sec. Two micron laser technology looks very promising in the near future, but several technical questions remain. The Ho:YAG laser would be small, compact, and efficient, requiring little or no maintenance. Since the Ho:YAG laser is laser diode pumped and has no moving part, the lifetime of this laser would be directly related to the diode laser lifetimes which can perform in excess of 10,000 hours. Efficiencies of 3 to 12 percent are expected, but laser demonstrations confirming the ability to Q-switch this laser are required. Coherent laser operation has been demonstrated for both the CW and Q-switched lasers.

Three Hundred Patients Treated with Ultrapulsed 980 nm Diode Laser for Skin Disorders

PubMed Central

Wollina, Uwe

2016-01-01

The use of lasers in skin diseases is quite common. In contrast to other laser types, medical literature about 980 nm ultrapulsed diode laser is sparse in dermatology. Herein, we report the use of ultrapulsed diode 980 nm laser in 300 patients with vascular lesions, cysts and pseudocysts, infectious disease, and malignant tumors. This laser is a versatile tool with excellent safety and efficacy in the hands of the experienced user. PMID:27688445

High density, optically corrected, micro-channel cooled, v-groove monolithic laser diode array

DOEpatents

Freitas, B.L.

1998-10-27

An optically corrected, micro-channel cooled, high density laser diode array achieves stacking pitches to 33 bars/cm by mounting laser diodes into V-shaped grooves. This design will deliver > 4kW/cm{sup 2} of directional pulsed laser power. This optically corrected, micro-channel cooled, high density laser is usable in all solid state laser systems which require efficient, directional, narrow bandwidth, high optical power density pump sources. 13 figs.

Enhanced vbasis laser diode package

DOEpatents

Deri, Robert J.; Chen, Diana; Bayramian, Andy; Freitas, Barry; Kotovsky, Jack

2014-08-19

A substrate having an upper surface and a lower surface is provided. The substrate includes a plurality of v-grooves formed in the upper surface. Each v-groove includes a first side and a second side perpendicular to the first side. A laser diode bar assembly is disposed within each of the v-grooves and attached to the first side. The laser diode bar assembly includes a first adhesion layer disposed on the first side of the v-groove, a metal plate attached to the first adhesion layer, a second adhesion layer disposed over the metal plate, and a laser diode bar attached to the second adhesion layer. The laser diode bar has a coefficient of thermal expansion (CTE) substantially similar to that of the metal plate.

Fiber optic coupling of a microlens conditioned, stacked semiconductor laser diode array

DOEpatents

Beach, R.J.; Benett, W.J.; Mills, S.T.

1997-04-01

The output radiation from the two-dimensional aperture of a semiconductor laser diode array is efficiently coupled into an optical fiber. The two-dimensional aperture is formed by stacking individual laser diode bars on top of another in a ``rack and stack`` configuration. Coupling into the fiber is then accomplished using individual microlenses to condition the output radiation of the laser diode bars. A lens that matches the divergence properties and wavefront characteristics of the laser light to the fiber optic is used to focus this conditioned radiation into the fiber. 3 figs.

AlGaInN laser diode technology and systems for defence and security applications

NASA Astrophysics Data System (ADS)

Najda, Stephen P.; Perlin, Piotr; Suski, Tadek; Marona, Lucja; Boćkowski, Mike; Leszczyński, Mike; Wisniewski, Przemek; Czernecki, Robert; Kucharski, Robert; Targowski, Grzegorz; Watson, Scott; Kelly, Antony E.

2015-05-01

The latest developments in AlGaInN laser diode technology are reviewed for defence and security applications such as underwater communications. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well. Thus AlGaInN laser diode technology is a key enabler for the development of new disruptive system level applications in displays, telecom, defence and other industries.

The advances and characteristics of high-power diode laser materials processing

NASA Astrophysics Data System (ADS)

Li, Lin

2000-10-01

This paper presents a review of the direct applications of high-power diode lasers for materials processing including soldering, surface modification (hardening, cladding, glazing and wetting modifications), welding, scribing, sheet metal bending, marking, engraving, paint stripping, powder sintering, synthesis, brazing and machining. The specific advantages and disadvantages of diode laser materials processing are compared with CO 2, Nd:YAG and excimer lasers. An effort is made to identify the fundamental differences in their beam/material interaction characteristics and materials behaviour. Also an appraisal of the future prospects of the high-power diode lasers for materials processing is given.

Passive Optical Locking Techniques for Diode Lasers

NASA Astrophysics Data System (ADS)

Zhang, Quan

1995-01-01

Most current diode-based nonlinear frequency converters utilize electronic frequency locking techniques. However, this type of locking technique typically involves very complex electronics, and suffers the 'power-drop' problem. This dissertation is devoted to the development of an all-optical passive locking technique that locks the diode laser frequency to the external cavity resonance stably without using any kind of electronic servo. The amplitude noise problem associated with the strong optical locking has been studied. Single-mode operation of a passively locked single-stripe diode with an amplitude stability better than 1% has been achieved. This passive optical locking technique applies to broad-area diodes as well as single-stripe diodes, and can be easily used to generate blue light. A schematic of a milliwatt level blue laser based on the single-stripe diode locking technique has been proposed. A 120 mW 467 nm blue laser has been built using the tapered amplifier locking technique. In addition to diode-based blue lasers, this passive locking technique has applications in nonlinear frequency conversions, resonant spectroscopy, particle counter devices, telecommunications, and medical devices.

VCSEL Scaling, Laser Integration on Silicon, and Bit Energy

DTIC Science & Technology

2017-03-01

need of high efficiency with high temperature operation eliminates essentially all laser diode technologies except VCSELs. Therefore scaling of the...CW laser diode and separate modulator. Lower diagram circuitry shows the case for a DML VCSEL. The small gain volume and high speed modulation...speed of the modulator. However the CW laser that is needed for the modulator appears to create a technological roadblock for laser diode platforms

Application of a 1.48-microm diode laser for bisecting oocytes into two identical hemizonae for the hemizona assay.

PubMed

Edenfeld, J; Schöpper, B; Sturm, R; Diedrich, K; Al-Hasani, S

2002-04-01

Laser systems are very promising new technical tools in assisted reproduction. It was investigated if laser radiation can replace the mechanical cutting procedure via micromanipulator in the hemizona assay (HZA), a commonly used bioassay to determine the sperm-zona pellucida binding capacity. An oocyte was bisected precisely into two identical hemizonae with approximately 20 laser pulses (pulse length 30 msec) using a 1.48-microm diode laser. Compared with the conventional method using microscalpels for zona bisection, laser treated hemizonae showed equivalent sperm-binding and within the two groups there was no detectable difference between matching hemizonae in their capacity for tight sperm-binding. To evaluate whether laser radiation affects the outcome of the HZA when effects of certain substances are investigated, the spermatozoa were preincubated with human follicular fluid (hFF), which inhibits the binding of spermatozoa to zona pellucida in vitro. Supplementation with follicular fluid exerted an inhibitory effect in both groups. The hemizona index (HZI) showed no statistical differences between the two methods. Therefore, the 1.48-microm diode laser is a suitable new instrument for generating equally sized hemizonae. There is no use for holding pipettes and microscalpels, on the contrary, for performing the HZA the laser is a precise, very quick and easy to use new working tool.

Curved adjustable fibre-optic diode laser in microscopic cholesteatoma surgery: description of use and review of the relevant literature.

PubMed

McCaffer, C J; Pabla, L; Watson, C

2018-04-01

The use of lasers in cholesteatoma surgery is common and well accepted. The most commonly used laser fibres are straight and non-adjustable; these have several limitations. This paper describes the use of an alternative laser fibre. This 'How I Do It' paper describes and illustrates the use of an alternative curved adjustable fibre-optic diode laser in microscopic cholesteatoma surgery. The curved, adjustable laser fibre allows accurate and atraumatic disease removal when the use of a straight laser fibre may be less effective or accurate. It reduces potential damage to delicate structures without the need for extra drilling or bone removal. It is suggested that the curved adjustable laser fibre is superior to the traditional straight fibre for cholesteatoma surgery.

Dual-beam, second-derivative tunable diode-laser infrared spectroscopy applied to trace-gas measurement

NASA Astrophysics Data System (ADS)

Tallant, D. R.; Jungst, R. G.

1981-04-01

A dual base diode laser spectrometer was constructed using off axis reflective optics. The spectrometer was amplitude modulated for direct absorption measurements or frequency modulated to obtain derivative spectra. The spectrometer had: high throughput; was easy to operate and align; provided good dual beam compensation; and had no evidence of the interference effects that were observed in diode laser spectrometers using refractive optics. Unpurged, using second derivative techniques, the instrument measured 108 parts per million CO (10/cm absorption cell, atmospheric pressure broadened) with good signal/noise. With the replacement of marginal instrumental components, the signal/noise was substantially increased. This instrument was developed to monitor the evolution of decomposition gases in sealed containers of small volume at atmospheric pressure.

Diode-pumped femtosecond mode-locked Nd, Y-codoped CaF2 laser

NASA Astrophysics Data System (ADS)

Zhu, Jiangfeng; Zhang, Lijuan; Gao, Ziye; Wang, Junli; Wang, Zhaohua; Su, Liangbi; Zheng, Lihe; Wang, Jingya; Xu, Jun; Wei, Zhiyi

2015-03-01

A passively mode-locked femtosecond laser based on an Nd, Y-codoped CaF2 disordered crystal was demonstrated. The Y3+-codoping in Nd : CaF2 markedly suppressed the quenching effect and improved the fluorescence quantum efficiency and emission spectra. With a fiber-coupled laser diode as the pump source, the continuous wave tuning range covering from 1042 to 1076 nm was realized, while the mode-locked operation generated 264 fs pulses with an average output power of 180 mW at a repetition rate of 85 MHz. The experimental results show that the Nd, Y-codoped CaF2 disordered crystal has potential in a new generation diode-pumped high repetition rate chirped pulse amplifier.

In Vitro Effect of Bleaching With 810 nm and 980 nm Diode Laser on Microhardness of Self-cure and Light-Cure Glass Ionomer Cements.

PubMed

Ranjbar Omrani, Ladan; Khoshamad, Sara; Tabatabaei Ghomshe, Elham; Chiniforush, Nasim; Hashemi Kamangar, Sedighe Sadat

2017-01-01

Introduction: This study sought to assess the effect of bleaching combined with irradiation of 810 nm and 980 nm diode laser on microhardness of 2 commonly used self-cure and light-cure glass ionomer cements (GICs) in comparison with conventional bleaching (without laser). Methods: In this in vitro, experimental study, 60 samples were fabricated of A2 shade of Fuji IX and Fuji II LC GICs (n=30) and each group was divided into 3 subgroups (n=10). The first subgroups were subjected to bleaching with Opalescence Xtra Boost plus 980 nm diode laser irradiation. The second subgroups were subjected to bleaching with Opalescence Boost plus 810 nm diode laser irradiation and the third subgroups were subjected to bleaching with Opalescence Xtra Boost without laser. Microhardness was measured at baseline and after the intervention using Vickers hardness tester. The data were analyzed using two-way analysis of variance (ANOVA) ( P <0.05). Results: Microhardness decreased in all subgroups after the intervention (P<0.001) irrespective of the type of GIC ( P =0.201) or surface treatment ( P =0.570). The baseline microhardness of the three subgroups within each group of GIC was not significantly different ( P =0.456), but the baseline microhardness of conventional GIC was significantly higher than that of resin modified GIC ( P =0.004). Conclusion: Bleaching with/without laser irradiation decreases the microhardness of GICs. The baseline microhardness of conventional GIC is higher than that of resin modified GIC.

Effect of different diode laser wavelengths on root dentin decontamination infected with Enterococcus faecalis.

PubMed

Borges, Caroline Cristina; Estrela, Carlos; Lopes, Fabiane Carneiro; Palma-Dibb, Regina Guenka; Pecora, Jesus Djalma; De Araújo Estrela, Cyntia Rodrigues; Sousa-Neto, Manoel Damião de

2017-11-01

The objective of this study was to evaluate the antibacterial effect and the ultrastructural alterations of diode laser with different wavelengths (808nm and 970nm) and its association with irrigating solutions (2.5% sodium hypochlorite and 2% chlorhexidine) in root dentin contaminated by a five days biofilm. Thirteen uniradicular teeth were sectioned into 100 dentin intraradicular blocks. Initially, the blocks were immersed for 5min in 17% EDTA and washed with distilled water for 5min, then samples were sterilized for 30min at 120°C. The dentin samples were inoculated with 0.1mL of E. faecalis suspension in 5mL BHI (Brain Heart Infusion) and incubated at 37°C for 5days. After contamination, the specimens were distributed into ten groups (n=10) according to surface treatment: GI - 5mL NaOCl 2.5%, GII - 5mL NaOCl 2.5%+808nm diode (0.1W for 20s), GIII - 5mL NaOCl 2.5%+970nm diode (0.5W for 4s), GIV - 808nm diode (0.1W for 20s), GV - 970nm diode (0.5W for 4s), GVI - CHX 2%, GVII - CHX 2%+808nm diode (0.1W for 20s), GVIII - CHX 2%+970nm diode (0.5W for 4s), GIX - positive control and GX - negative control. Bacterial growth was analyzed by turbidity and optical density of the growth medium by spectrophotometry (nm). Then, the specimens were processed for analysis ultrastructural changes of the dentin surface by SEM. The data was subject to the One-way ANOVA test. GI (77.5±12.1), GII (72.5±12.2), GIII (68.7±8.7), GV (68.3±8.7), GVI (62.0±5.5) and GVII (67.5±3.3) were statistically similar and statistically different from GIV (58.8±25.0), GVIII (59.2±4.0) and control groups (p<0.05). SEM analysis showed a modified amorphous organic matrix layer with melted intertubular dentin when dentin samples were irradiated with 970nm diode laser; erosion of the intertubular dentin in blocks submitted to 808nm diode laser irradiation; and an increased erosion of the intertubular dentin when 2.5% NaOCl was associated to the different wavelengths lasers. All the therapeutic protocols were able to reduce the bacterial contingent in dentin blocks, and the association of diode laser and solutions did not significantly improve the reduction of the bacterial contingent. Copyright © 2017 Elsevier B.V. All rights reserved.

Diode laser surgery versus scalpel surgery in the treatment of fibrous hyperplasia: a randomized clinical trial.

PubMed

Amaral, M B F; de Ávila, J M S; Abreu, M H G; Mesquita, R A

2015-11-01

Fibrous hyperplasia is treated by surgical incision using a scalpel, together with removal of the source of chronic trauma. However, scalpel techniques do not provide the haemostasis that is necessary when dealing with highly vascular tissues. Diode laser surgery can be used in the management of oral tissues due to its high absorption by water and haemoglobin, and has provided good results in both periodontal surgery and oral lesions. The aim of the present study was to compare the effects of diode laser surgery to those of the conventional technique in patients with fibrous hyperplasia. A randomized clinical trial was performed in which surgical and postoperative evaluations were analyzed. On comparison of the laser-treated (study group) patients to those treated with a scalpel (control group), significant differences were observed in the duration of surgery and the use of analgesic medications. Over a 3-week period, clinical healing of the postoperative wound was significantly faster in the control group as compared to the study group. In conclusion, diode laser surgery proved to be more effective and less invasive when compared to scalpel surgery in the management of fibrous hyperplasia. However, wound healing proved to be faster when using scalpel surgery. Copyright © 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Temperature effects on tunable cw Alexandrite lasers under diode end-pumping.

PubMed

Kerridge-Johns, William R; Damzen, Michael J

2018-03-19

Diode pumped Alexandrite is a promising route to high power, efficient and inexpensive lasers with a broad (701 nm to 858 nm) gain bandwidth; however, there are challenges with its complex laser dynamics. We present an analytical model applied to experimental red diode end-pumped Alexandrite lasers, which enabled a record 54 % slope efficiency with an output power of 1.2 W. A record lowest lasing wavelength (714 nm) and record tuning range (104 nm) was obtained by optimising the crystal temperature between 8 °C and 105 °C in the vibronic mode. The properties of Alexandrite and the analytical model were examined to understand and give general rules in optimising Alexandrite lasers, along with their fundamental efficiency limits. It was found that the lowest threshold laser wavelength was not necessarily the most efficient, and that higher and lower temperatures were optimal for longer and shorter laser wavelengths, respectively. The pump excited to ground state absorption ratio was measured to decrease from 0.8 to 0.7 by changing the crystal temperature from 10 °C to 90 °C.

Polarization effects associated with thermal processing of HY-80 structural steel using high-power laser diode array

NASA Astrophysics Data System (ADS)

Wu, Sheldon S. Q.; Baker, Bradford W.; Rotter, Mark D.; Rubenchik, Alexander M.; Wiechec, Maxwell E.; Brown, Zachary M.; Beach, Raymond J.; Matthews, Manyalibo J.

2017-12-01

Localized heating of roughened steel surfaces using highly divergent laser light emitted from high-power laser diode arrays was experimentally demonstrated and compared with theoretical predictions. Polarization dependence was analyzed using Fresnel coefficients to understand the laser-induced temperature rise of HY-80 steel plates under 383- to 612-W laser irradiation. Laser-induced, transient temperature distributions were directly measured using bulk thermocouple probes and thermal imaging. Finite-element analysis yielded quantitative assessment of energy deposition and heat transport in HY-80 steel using absorptivity as a tuning parameter. The extracted absorptivity values ranged from 0.62 to 0.75 for S-polarized and 0.63 to 0.85 for P-polarized light, in agreement with partially oxidized iron surfaces. Microstructural analysis using electron backscatter diffraction revealed a heat affected zone for the highest temperature conditions (612 W, P-polarized) as evidence of rapid quenching and an austenite to martensite transformation. The efficient use of diode arrays for laser-assisted advanced manufacturing technologies, such as hybrid friction stir welding, is discussed.

Ultrastructural analysis of root canal dentine irradiated with 980-nm diode laser energy at different parameters.

PubMed

Marchesan, Melissa Andréia; Brugnera-Junior, Aldo; Souza-Gabriel, Aline Evangelista; Correa-Silva, Silvio Rocha; Sousa-Neto, Manoel D

2008-06-01

The purpose of this in vitro study was to investigate using the scanning electron microscope (SEM) the ultrastructural morphological changes of the radicular dentine surface after irradiation with 980-nm diode laser energy at different parameters and angles of incidence. There have been limited reports on the effects of diode laser irradiation at 980 nm on radicular dentin morphology. Seventy-two maxillary canines were sectioned and roots were biomechanically prepared using K3 rotary instruments. The teeth were irrigated with 2 mL of distilled water between files and final irrigation was performed with 10 mL of distilled water. The teeth were then randomly divided into five groups (n = 8 each) according to their diode laser parameters: Group 1: no irradiation (control); group 2: 1.5 W/continuous wave (CW) emission (the manufacturer's parameters); group 3: 1.5 W/100 Hz; group 4: 3 W/CW; and group 5: 3 W/100 Hz. Laser energy was applied with helicoid movements (parallel to the canal walls) for 20 sec. Eight additional teeth for each group were endodontically prepared and split longitudinally and irradiation was applied perpendicularly to the root surface. Statistical analysis showed no difference between the root canal thirds irradiated with the 980-nm diode laser, and similar results between the parameters 1.5 W/CW and 3 W/100 Hz (p > 0.05). When considering different output powers and delivery modes our results showed that changes varied from smear layer removal to dentine fusion.

Investigation of mode partition noise in Fabry-Perot laser diode

NASA Astrophysics Data System (ADS)

Guo, Qingyi; Deng, Lanxin; Mu, Jianwei; Li, Xun; Huang, Wei-Ping

2014-09-01

Passive optical network (PON) is considered as the most appealing access network architecture in terms of cost-effectiveness, bandwidth management flexibility, scalability and durability. And to further reduce the cost per subscriber, a Fabry-Perot (FP) laser diode is preferred as the transmitter at the optical network units (ONUs) because of its lower cost compared to distributed feedback (DFB) laser diode. However, the mode partition noise (MPN) associated with the multi-longitudinal-mode FP laser diode becomes the limiting factor in the network. This paper studies the MPN characteristics of the FP laser diode using the time-domain simulation of noise-driven multi-mode laser rate equation. The probability density functions are calculated for each longitudinal mode. The paper focuses on the investigation of the k-factor, which is a simple yet important measure of the noise power, but is usually taken as a fitted or assumed value in the penalty calculations. In this paper, the sources of the k-factor are studied with simulation, including the intrinsic source of the laser Langevin noise, and the extrinsic source of the bit pattern. The photon waveforms are shown under four simulation conditions for regular or random bit pattern, and with or without Langevin noise. The k-factors contributed by those sources are studied with a variety of bias current and modulation current. Simulation results are illustrated in figures, and show that the contribution of Langevin noise to the k-factor is larger than that of the random bit pattern, and is more dominant at lower bias current or higher modulation current.

Diode laser operating on an atomic transition limited by an isotope ⁸⁷Rb Faraday filter at 780 nm.

PubMed

Tao, Zhiming; Hong, Yelong; Luo, Bin; Chen, Jingbiao; Guo, Hong

2015-09-15

We demonstrate an extended cavity Faraday laser system using an antireflection-coated laser diode as the gain medium and the isotope (87)Rb Faraday anomalous dispersion optical filter (FADOF) as the frequency selective device. Using this method, the laser wavelength works stably at the highest transmission peak of the isotope (87)Rb FADOF over the laser diode current from 55 to 140 mA and the temperature from 15°C to 35°C. Neither the current nor the temperature of the laser diode has significant influence on the output frequency. Compared with previous extended cavity laser systems operating at frequencies irrelevant to spectacular atomic transition lines, the laser system realized here provides a stable laser source with the frequency operating on atomic transitions for many practical applications.

Induratio penis plastica (IPP) and laser: a review

NASA Astrophysics Data System (ADS)

Longo, Leonardo; Mancini, S.; Postiglione, M. G.

2002-10-01

The first employments of Laser therapy for I.P.P. came from back to more than twenty years ago. At the beginning it was employed only in the acute forms as analgesic laser laser was used also as anti-inflammatory following the doses of Low Level Laser Therapy. Than the science tried to use the laser effect remodelling phase of the scars, to make the fibrosis regrade in the chronic forms. Tunable laser in small optical fiber was used for ablation of calcified zones with very good results. For the slight forms were used diode laser 660 and 904 nm, alone ir coupling with CO2 laser with large spot. At first some Author used helium-Neon laser 632. Some of these lasers were combined wtih microiontophoresis and ultrasounds therapy in teh same treatment. Now we use 810 nm surgical diode laser in almost all induratio forms. The immediate results and follow up will be discussed. Thanks to these results we could conclude that IPP laser therapy can be effective in most of the clinic forms. Although the used procedure is subject to improvement.

AlGaInN laser diode technology for defence, security and sensing applications

NASA Astrophysics Data System (ADS)

Najda, Stephen P.; Perlin, Piotr; Suski, Tadek; Marona, Lucja; Boćkowski, Mike; Leszczyński, Mike; Wisniewski, Przemek; Czernecki, Robert; Kucharski, Robert; Targowski, Grzegorz; Watson, Scott; Kelly, Antony E.

2014-10-01

The latest developments in AlGaInN laser diode technology are reviewed for defence, security and sensing applications. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., i.e, 380nm, to the visible, i.e., 530nm, by tuning the indium content of the laser GaInN quantum well. Advantages of using Plasma assisted MBE (PAMBE) compared to more conventional MOCVD epitaxy to grow AlGaInN laser structures are highlighted. Ridge waveguide laser diode structures are fabricated to achieve single mode operation with optical powers of <100mW in the 400-420nm wavelength range that are suitable for telecom applications. Visible light communications at high frequency (up to 2.5 Gbit/s) using a directly modulated 422nm Gallium-nitride (GaN) blue laser diode is reported. High power operation of AlGaInN laser diodes is demonstrated with a single chip, AlGaInN laser diode `mini-array' with a common p-contact configuration at powers up to 2.5W cw at 410nm. Low defectivity and highly uniform GaN substrates allow arrays and bars of nitride lasers to be fabricated. GaN laser bars of up to 5mm with 20 emitters, mounted in a CS mount package, give optical powers up to 4W cw at ~410nm with a common contact configuration. An alternative package configuration for AlGaInN laser arrays allows for each individual laser to be individually addressable allowing complex free-space and/or fibre optic system integration within a very small form-factor.or.

One joule per Q-switched pulse diode-pumped laser

NASA Technical Reports Server (NTRS)

Holder, Lonnie E.; Kennedy, Chandler; Long, Larry; Dube, George

1992-01-01

Q-switched 1-J output has been achieved from diode-pumped zig-zag Nd:YAG slabs in an oscillator-amplifier configuration. The oscillator was single transverse and longitudinal model. This laser set records for Q-switched energy per pulse, and for average power from a diode-pumped laser. The laser was constructed in a rugged configuration suitable for routine laboratory use.

Modulation of distributed feedback (DFB) laser diode with the autonomous Chua's circuit: Theory and experiment

NASA Astrophysics Data System (ADS)

Talla Mbé, Jimmi Hervé; Woafo, Paul

2018-03-01

We report on a simple way to generate complex optical waveforms with very cheap and accessible equipments. The general idea consists in modulating a laser diode with an autonomous electronic oscillator, and in the case of this study, we use a distributed feedback (DFB) laser diode pumped with an electronic Chua's circuit. Based on the adiabatic P-I characteristics of the laser diode at low frequencies, we show that when the total pump is greater than the laser threshold, it is possible to convert the electrical waveforms of the Chua's circuit into optical carriers. But, if that is not the case, the on-off dynamical behavior of the laser permits to obtain many other optical waveform signals, mainly pulses. Our numerical results are consistent with experimental measurements. The work presents the advantage of extending the range of possible chaotic dynamics of the laser diodes in the time domains (millisecond) where it is not usually expected with conventional modulation techniques. Moreover, this new technique of laser diodes modulation brings a general benefit in the physical equipment, reduces their cost and congestion so that, it can constitute a step towards photonic integrated circuits.

Wavelength-Agile External-Cavity Diode Laser for DWDM

NASA Technical Reports Server (NTRS)

Pilgrim, Jeffrey S.; Bomse, David S.

2006-01-01

A prototype external-cavity diode laser (ECDL) has been developed for communication systems utilizing dense wavelength- division multiplexing (DWDM). This ECDL is an updated version of the ECDL reported in Wavelength-Agile External- Cavity Diode Laser (LEW-17090), NASA Tech Briefs, Vol. 25, No. 11 (November 2001), page 14a. To recapitulate: The wavelength-agile ECDL combines the stability of an external-cavity laser with the wavelength agility of a diode laser. Wavelength is modulated by modulating the injection current of the diode-laser gain element. The external cavity is a Littman-Metcalf resonator, in which the zeroth-order output from a diffraction grating is used as the laser output and the first-order-diffracted light is retro-reflected by a cavity feedback mirror, which establishes one end of the resonator. The other end of the resonator is the output surface of a Fabry-Perot resonator that constitutes the diode-laser gain element. Wavelength is selected by choosing the angle of the diffracted return beam, as determined by position of the feedback mirror. The present wavelength-agile ECDL is distinguished by design details that enable coverage of all 60 channels, separated by 100-GHz frequency intervals, that are specified in DWDM standards.

QUANTITATIVE DETECTION OF ENVIRONMENTALLY IMPORTANT DYES USING DIODE LASER/FIBER-OPTIC RAMAN

EPA Science Inventory

A compact diode laser/fiber-optic Raman spectrometer is used for quantitative detection of environmentally important dyes. This system is based on diode laser excitation at 782 mm, fiber optic probe technology, an imaging spectrometer, and state-of-the-art scientific CCD camera. ...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Afonenko, A A; Dorogush, E S; Malyshev, S A

Using a system of coupled travelling wave equations, in the small-signal regime we analyse frequency and noise characteristics of index- or absorption-coupled distributed feedback laser diodes, as well as of Fabry – Perot (FP) laser diodes. It is shown that the weakest dependence of the direct modulation efficiency on the locking frequency in the regime of strong external optical injection locking is exhibited by a FP laser diode formed by highly reflective and antireflective coatings on the end faces of a laser structure. A reduction in the dependence of output characteristics of the laser diode on the locking frequency canmore » be attained by decreasing the reflection coefficient of the antireflective FP mirror. (control of laser radiation parameters)« less

Resonantly diode-pumped eye-safe Er:YAG laser with fiber-shaped crystal

NASA Astrophysics Data System (ADS)

Němec, Michal; Šulc, Jan; Hlinomaz, Kryštof; Jelínková, Helena; Nejezchleb, Karel; Čech, Miroslav

2018-02-01

Solid-state eye-safe lasers are interesting sources for various applications, such as lidar, remote sensing, and ranging. A resonantly diode-pumped Er:YAG laser could be one of them allowing to reach a tunable laser emission in 1.6 μm spectral region. To overcome low pump absorption and poor pumping beam quality generated by commercially available laser diode, an active medium could be formed to long and thin laser rod guiding pumping radiation. Such an effective cooling during a high power pumping, which is a "crystal-fiber" benefit, may be useful for "standard" crystal active medium. The main goal of this work was to investigate the laser characteristics of new developed Er:YAG crystal with a special shape for diode-pumping. Er:YAG fiber-shape crystal with square cross-section (1x1mm) and 40mm in length was doped by 0.1% Er3+ ions. All sides of this crystal were polished and in addition the end-faces of it were antireflection coatings for the wavelength 1470 and 1645 nm. As a pump system, a fiber coupled laser diode (f = 10 Hz, t = 10 ms) emitting radiation at 1465 nm wavelength was used. Er:YAG fiber-shape crystal was placed onto a copper holder in the 85 mm long plan-concave resonator consisting of a pump flat mirror and output curved (r = 150 mm) coupler with a reflectivity of 96 % @ 1645 nm. The dependence of the output peak power on absorbed pump power was investigated and the maximum 0.8 W was obtained. The corresponding slope efficiency was 14.5 %. The emitting wavelength was equaled to 1645 nm (4 nm linewidth, FWHM). The spatial beam structure was close to the Gaussian mode.

303 nm continuous wave ultraviolet laser generated by intracavity frequency-doubling of diode-pumped Pr3+:LiYF4 laser

NASA Astrophysics Data System (ADS)

Zhu, Pengfei; Zhang, Chaomin; Zhu, Kun; Ping, Yunxia; Song, Pei; Sun, Xiaohui; Wang, Fuxin; Yao, Yi

2018-03-01

We demonstrate an efficient and compact ultraviolet laser at 303 nm generated by intracavity frequency doubling of a continuous wave (CW) laser diode-pumped Pr3+:YLiF4 laser at 607 nm. A cesium lithium borate (CLBO) crystal, cut for critical type I phase matching at room temperature, is used for second-harmonic generation (SHG) of the fundamental laser. By using an InGaN laser diode array emitting at 444.3 nm with a maximum incident power of 10 W, as high as 68 mW of CW output power at 303 nm is achieved. The output power stability in 4 h is better than 2.85%. To the best of our knowledge, this is high efficient UV laser generated by frequency doubling of an InGaN laser diode array pumped Pr3+:YLiF4 laser.

Combinational light emitting diode-high frequency focused ultrasound treatment for HeLa cell.

PubMed

Choe, Se-Woon; Park, Kitae; Park, Chulwoo; Ryu, Jaemyung; Choi, Hojong

2017-12-01

Light sources such as laser and light emitting diode or ultrasound devices have been widely used for cancer therapy and regenerative medicines, since they are more cost-effective and less harmful than radiation therapy, chemotherapy or magnetic treatment. Compared to laser and low intensity ultrasound techniques, light emitting diode and high frequency focused ultrasound shows enhanced therapeutic effects, especially for small tumors. We propose combinational light emitting diode-high frequency focused ultrasound treatment for human cervical cancer HeLa cells. Individual red, green, and blue light emitting diode light only, high frequency focused ultrasound only, or light emitting diode light combined with high frequency focused ultrasound treatments were applied in order to characterize the responses of HeLa cells. Cell density exposed by blue light emitting diode light combined with high frequency focused ultrasound (2.19 ± 0.58%) was much lower than that of cells exposed by red and green light emitting diode lights (81.71 ± 9.92% and 61.81 ± 4.09%), blue light emitting diode light (11.19 ± 2.51%) or high frequency focused ultrasound only (9.72 ± 1.04%). We believe that the proposed combinational blue light emitting diode-high frequency focused ultrasound treatment could have therapeutic benefits to alleviate cancer cell proliferation.

Preliminary experiences on diode laser welding of skin

NASA Astrophysics Data System (ADS)

Reali, Umberto M.; Borgognoni, L.; Martini, L.; Chiarugi, C.; Gori, F.; Pini, Roberto; Toncelli, F.; Vanni, U.

1994-12-01

Dye enhanced laser welding has been recently proposed for skin closures to exploit the advantages of laser procedure (possible reduction of scar formation, no inflammatory reaction). In this preliminary study we used the diode laser-assisted technique to perform welding of rats' skin. In the pilot phase of the study we investigated the effect of the interaction between diode laser radiation and 20 full thickness skin wounds, performed on the shaved backs of 10 Wistar rats, using laser power in the range of 200 - 150 mW and, as the photoenhancing chromophore, Indocyanine Cardio-green (ICG) dye saturated solution in plasma. Ten wounds were sutured with 4.0 nylon thread, to provide a comparison with the traditional procedure. Wounds' samples were explanted on day 3 and 7 after the treatment, for histological evaluation. Clinical examination on the same days showed a high percentage of wounds dehiscence and presence of scales and crusts. Histologic examination demonstrated evidence of thermal injury and a heightened inflammation, superior to that of suture closures. In the second phase of the study, a lower laser power (150 - 80 mW), ICG-plasma-non saturated solution (ICG-sol) and ICG-plasma-saturated-sodium hyaluronate gel (ICG-gel), were used. Six wounds were filled with ICG-sol and six with ICG-gel, then irradiated at 150, 120 and 80 mW. Postoperative explants were performed on day 3 and 7. Clinical and histological results from this group were satisfactory: we recorded only one case of dehiscence, well healed wounds, no epidermal necrosis and a mild inflammatory reaction, reduced respect to that of traditional closure. We characterized the optimum range of parameters of diode laser-assisted technique to achieve an effective skin welding and the corresponding clinical and histologic pattern was described.

CO2 and diode laser for excisional biopsies of oral mucosal lesions. A pilot study evaluating clinical and histopathological parameters.

PubMed

Suter, Valérie G A; Altermatt, Hans Jörg; Sendi, Pedram; Mettraux, Gérald; Bornstein, Michael M

2010-01-01

The present pilot study evaluates the histopathological characteristics and suitability of CO2 and diode lasers for performing excisional biopsies in the buccal mucosa with special emphasis on the extent of the thermal damage zone created. 15 patients agreed to undergo surgical removal of their fibrous hyperplasias with a laser. These patients were randomly assigned to one diode or two CO2 laser groups. The CO2 laser was used in a continuous wave mode (cw) with a power of 5 W (Watts), and in a pulsed char-free mode (cf). Power settings for the diode laser were 5.12 W in a pulsed mode. The thermal damage zone of the three lasers and intraoperative and postoperative complications were assessed and compared. The collateral thermal damage zone on the borders of the excisional biopsies was significantly smaller with the CO, laser for both settings tested compared to the diode laser regarding values in pm or histopathological index scores. The only intraoperative complication encountered was bleeding, which had to be controlled with electrocauterization. No postoperative complications occurred in any of the three groups. The CO2 laser seems to be appropriate for excisional biopsies of benign oral mucosal lesions. The CO2 laser offers clear advantages in terms of smaller thermal damage zones over the diode laser. More study participants are needed to demonstrate potential differences between the two different CO2 laser settings tested.

Application of Diode Laser in the Treatment of Dentine Hypersensitivity.

PubMed

Gojkov-Vukelic, Mirjana; Hadzic, Sanja; Zukanovic, Amila; Pasic, Enes; Pavlic, Veriva

2016-12-01

Dentine hypersensitivity is characterized by acute, sharp pain arising from the exposed dentine, most commonly in response to thermal, tactile, or chemical stimuli, and which cannot be linked to any other pathological changes in the tooth or the environment. Therapy uses various impregnating agents in the form of solutions or gels and, in more recent times, laser. The aim of this research was to examine the effects of treatment of hypersensitive dental cervix with diode laser. The study included 18 patients with 82 sensitive teeth. The degree of dentine hypersensitivity was evaluated by visual analogue scale (VAS), and the treatment was carried out by application of low-power diode laser over the span of three visits, which depended on the initial sensitivity. There is a significant difference in VAS values measured at the onset of treatment (baseline) and immediately after the first laser treatment (t=9.275; p=0.000), after 7 days, after the second laser treatment (14 days) (t=7.085, p=0.000), as well as after 14 days and the third laser treatment (t=5.517, p=0.000), which confirms the effectiveness of this therapeutic procedure. The results showed a reduction of hypersensitivity in response to tactile stimulus with a probe after the third treatment, even with teeth whose value on the VAS was very high at the beginning of treatment (baseline). Within the scope of the conducted study, laser therapy has provided extremely safe and effective results in the treatment of cervical dentine hypersensitivity.

Unclassified Publications of Lincoln Laboratory, 1 January-31 December 1987. Volume 13

DTIC Science & Technology

1987-12-31

Visible-Laser Photochemical Etching of Cr , Mo, and W 5901 High-Speed Electronic Beam Steering Using Injection Locking of a Laser-Diode Array...of High- Power Broad-Area Diode Lasers High-Temperature Point-Contact Transistors and Schottky Diodes Formed on Synthetic Boron- Doped Diamond...SPEECHES MS No. 593IB C02 Laser Radar 6550B Recent Advances in Transition-Metal- Doped Lasers 6714D Radiation Damage in Dry

Integrated injection-locked semiconductor diode laser

DOEpatents

Hadley, G. Ronald; Hohimer, John P.; Owyoung, Adelbert

1991-01-01

A continuous wave integrated injection-locked high-power diode laser array is provided with an on-chip independently-controlled master laser. The integrated injection locked high-power diode laser array is capable of continuous wave lasing in a single near-diffraction limited output beam at single-facet power levels up to 125 mW (250 mW total). Electronic steering of the array emission over an angle of 0.5 degrees is obtained by varying current to the master laser. The master laser injects a laser beam into the slave array by reflection of a rear facet.

Visible-to-visible four-photon ultrahigh resolution microscopic imaging with 730-nm diode laser excited nanocrystals.

PubMed

Wang, Baoju; Zhan, Qiuqiang; Zhao, Yuxiang; Wu, Ruitao; Liu, Jing; He, Sailing

2016-01-25

Further development of multiphoton microscopic imaging is confronted with a number of limitations, including high-cost, high complexity and relatively low spatial resolution due to the long excitation wavelength. To overcome these problems, for the first time, we propose visible-to-visible four-photon ultrahigh resolution microscopic imaging by using a common cost-effective 730-nm laser diode to excite the prepared Nd(3+)-sensitized upconversion nanoparticles (Nd(3+)-UCNPs). An ordinary multiphoton scanning microscope system was built using a visible CW diode laser and the lateral imaging resolution as high as 161-nm was achieved via the four-photon upconversion process. The demonstrated large saturation excitation power for Nd(3+)-UCNPs would be more practical and facilitate the four-photon imaging in the application. A sample with fine structure was imaged to demonstrate the advantages of visible-to-visible four-photon ultrahigh resolution microscopic imaging with 730-nm diode laser excited nanocrystals. Combining the uniqueness of UCNPs, the proposed visible-to-visible four-photon imaging would be highly promising and attractive in the field of multiphoton imaging.

Next generation diode lasers with enhanced brightness

NASA Astrophysics Data System (ADS)

Ried, S.; Rauch, S.; Irmler, L.; Rikels, J.; Killi, A.; Papastathopoulos, E.; Sarailou, E.; Zimer, H.

2018-02-01

High-power diode lasers are nowadays well established manufacturing tools in high power materials processing, mainly for tactile welding, surface treatment and cladding applications. Typical beam parameter products (BPP) of such lasers range from 30 to 50 mm·mrad at several kilowatts of output power. TRUMPF offers a product line of diode lasers to its customers ranging from 150 W up to 6 kW of output power. These diode lasers combine high reliability with small footprint and high efficiency. However, up to now these lasers are limited in brightness due to the commonly used spatial and coarse spectral beam combining techniques. Recently diode lasers with enhanced brightness have been presented by use of dense wavelength multiplexing (DWM). In this paper we report on TRUMPF's diode lasers utilizing DWM. We demonstrate a 2 kW and a 4 kW system ideally suited for fine welding and scanner welding applications. The typical laser efficiency is in the range of 50%. The system offers plug and play exchange of the fiber beam delivery cable, multiple optical outputs and integrated cooling in a very compact package. An advanced control system offers flexible integration in any customer's shop floor environment and includes industry 4.0 capabilities (e.g. condition monitoring and predictive maintenance).

1-kilowatt CW all-fiber laser oscillator pumped with wavelength-beam-combined diode stacks.

PubMed

Xiao, Y; Brunet, F; Kanskar, M; Faucher, M; Wetter, A; Holehouse, N

2012-01-30

We have demonstrated a monolithic cladding-pumped ytterbium-doped single all-fiber laser oscillator generating 1 kW of CW signal power at 1080 nm with 71% slope efficiency and near diffraction-limited beam quality. Fiber components were highly integrated on "spliceless" passive fibers to promote laser efficiency and alleviate non-linear effects. The laser was pumped through a 7:1 pump combiner with seven 200-W 91x nm fiber-pigtailed wavelength-beam-combined diode-stack modules. The signal power of such a single all-fiber laser oscillator showed no evidence of roll-over, and the highest output was limited only by available pump power.

Cylindrical microlens with an internally reflecting surface and a method of fabrication

DOEpatents

Beach, Raymond J.; Freitas, Barry L.

2004-03-23

A fast (high numerical aperture) cylindrical microlens, which includes an internally reflective surface, that functions to deviate the direction of the light that enters the lens from its original propagation direction is employed in optically conditioning laser diodes, laser diode arrays and laser diode bars.

A Cylindrical Microlens With An Internally Reflective Surface And A Method Of Fabrication

DOEpatents

Beach, Raymond J.; Freitas, Barry L.

2005-09-27

A fast (high numerical aperture) cylindrical microlens, which includes an internally reflective surface, that functions to deviate the direction of the light that enters the lens from its original propagation direction is employed in optically conditioning laser diodes, laser diode arrays and laser diode bars.

Forward voltage short-pulse technique for measuring high power laser array junction temperature

NASA Technical Reports Server (NTRS)

Meadows, Byron L. (Inventor); Amzajerdian, Frazin (Inventor); Barnes, Bruce W. (Inventor); Baker, Nathaniel R. (Inventor)

2012-01-01

The present invention relates to a method of measuring the temperature of the P-N junction within the light-emitting region of a quasi-continuous-wave or pulsed semiconductor laser diode device. A series of relatively short and low current monitor pulses are applied to the laser diode in the period between the main drive current pulses necessary to cause the semiconductor to lase. At the sufficiently low current level of the monitor pulses, the laser diode device does not lase and behaves similar to an electronic diode. The voltage across the laser diode resulting from each of these low current monitor pulses is measured with a high degree of precision. The junction temperature is then determined from the measured junction voltage using their known linear relationship.

Demonstration of a diode-laser-based high spectral resolution lidar (HSRL) for quantitative profiling of clouds and aerosols.

PubMed

Hayman, Matthew; Spuler, Scott

2017-11-27

We present a demonstration of a diode-laser-based high spectral resolution lidar. It is capable of performing calibrated retrievals of aerosol and cloud optical properties at a 150 m range resolution with less than 1 minute integration time over an approximate range of 12 km during day and night. This instrument operates at 780 nm, a wavelength that is well established for reliable semiconductor lasers and detectors, and was chosen because it corresponds to the D2 rubidium absorption line. A heated vapor reference cell of isotopic rubidium 87 is used as an effective and reliable aerosol signal blocking filter in the instrument. In principle, the diode-laser-based high spectral resolution lidar can be made cost competitive with elastic backscatter lidar systems, yet delivers a significant improvement in data quality through direct retrieval of quantitative optical properties of clouds and aerosols.

Transition to Complicated Behavior in Infinite Dimensional Dynamical Systems

DTIC Science & Technology

1990-03-01

solitons in nonlinear refractive periodic media," Phys. Lett. A. 141 37 (1989). A.3. Dynamics of Free-Running and Injection- Locked Laser Diode Arrays...Fibers * Dynamics of Free-Running and Injection- Locked Laser Diode Arrays I Diffraction/Diffusion Mediated Instabilities in Self-focusing/Defocusing...optics, the interplay between the coherence of solitons and the scattering (Anderson localization) effects of randomness, and the value in looking at

In vitro histological evaluation of the surgical margins made by different laser wavelengths in tongue tissues

PubMed Central

Azevedo, Ana-Salvaterra; Ferreira, Fernando; Delgado, Maria-Leonor; Garcês, Fernanda; Carreira, Sofia; Martins, Marco; Suarez-Quintanilla, Juan

2016-01-01

Background Lasers have become standard tools for the surgical treatment of oral lesions. The purpose of this study is to determine the surgical margins and histologically evaluate the tissue thermal effects induced by different types of surgical instruments. Material and Methods Cuts were made in pork tongues’ mucosa with different lasers (Er:YAG at 2W with and without air / water spray and at 4W with and without air / water spray; CO2 at 3.5W and 7W in pulsed mode and at 7W in continuous mode; the diode laser at 3.5W and boost 3.5W in pulsed mode; Nd:YAG at 6W, 40Hz and electroscalpel at 5W and conventional scalpel as control. Macroscopic and microscopic morphological changes were evaluated. Results The results of this study showed that the surgical instruments that caused greater tissue damage extension were: the Nd:YAG laser (670.68μm), the diode 3.5W and boost PW (626.82μm), the CO2 7W CW (571.18μm), the CO2 at 7W PW (485.45μm), the diode 3.5W PW (456.15μm), the electroscalpel (409.57μm) and lastly the CO2 laser 3.5W PW (306.19μm) and Er:YAG (74.66μm) laser, regardless of power, mode or air / water spray used. An association between the Tissue Damage Extension and the Degree of Carbonization (r = 0.789; P = 0.01), and an association between the Tissue Damage Extension and Regularity of the Incision were found (r = -, 299; P = 0.01). Conclusions The results of this study suggest that lasers can be used in soft tissues biopsies of the oral cavity, enabling a correct histopathological analysis, as long as the biological effects of each laser type are considered. The Er:YAG laser revealed its potential for biopsies of the oral mucosa ensuring a successful histological evaluation and the CO2 laser at 3,5W in pulsed mode presented itself as the best choice for surgeries with hemostasis. Key words:CO2 laser, diode laser, Er:YAG laser, laser surgery, Nd:YAG laser, oral mucosa, thermal effect. PMID:27703606

Generating a high brightness multi-kilowatt laser by dense spectral combination of VBG stabilized single emitter laser diodes

NASA Astrophysics Data System (ADS)

Fritsche, H.; Koch, Ralf; Krusche, B.; Ferrario, F.; Grohe, Andreas; Pflueger, S.; Gries, W.

2014-05-01

Generating high power laser radiation with diode lasers is commonly realized by geometrical stacking of diode bars, which results in high output power but poor beam parameter product (BPP). The accessible brightness in this approach is limited by the fill factor, both in slow and fast axis. By using a geometry that accesses the BPP of the individual diodes, generating a multi kilowatt diode laser with a BPP comparable to fiber lasers is possible. We will demonstrate such a modular approach for generating multi kilowatt lasers by combining single emitter diode lasers. Single emitter diodes have advantages over bars, mainly a simplified cooling, better reliability and a higher brightness per emitter. Additionally, because single emitters can be arranged in many different geometries, they allow building laser modules where the brightness of the single emitters is preserved. In order to maintain the high brightness of the single emitter we developed a modular laser design which uses single emitters in a staircase arrangement, then coupling two of those bases with polarization combination which is our basic module. Those modules generate up to 160 W with a BPP better than 7.5 mm*mrad. For further power scaling wavelength stabilization is crucial. The wavelength is stabilized with only one Volume Bragg Grating (VBG) in front of a base providing the very same feedback to all of the laser diodes. This results in a bandwidth of < 0.5 nm and a wavelength stability of better than 250 MHz over one hour. Dense spectral combination with dichroic mirrors and narrow channel spacing allows us to combine multiple wavelength channels, resulting in a 2 kW laser module with a BPP better than 7.5 mm*mrad, which can easily coupled into a 100 μm fiber and 0.15 NA.

Qualification Testing of Laser Diode Pump Arrays for a Space-Based 2-micron Coherent Doppler Lidar

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Singh, Upendra N.; Kavaya, Michael J.

2007-01-01

The 2-micron thulium and holmium-based lasers being considered as the transmitter source for space-based coherent Doppler lidar require high power laser diode pump arrays operating in a long pulse regime of about 1 msec. Operating laser diode arrays over such long pulses drastically impact their useful lifetime due to the excessive localized heating and substantial pulse-to-pulse thermal cycling of their active regions. This paper describes the long pulse performance of laser diode arrays and their critical thermal characteristics. A viable approach is then offered that allows for determining the optimum operational parameters leading to the maximum attainable lifetime.

Nitride-based stacked laser diodes with a tunnel junction

NASA Astrophysics Data System (ADS)

Okawara, Satoru; Aoki, Yuta; Kuwabara, Masakazu; Takagi, Yasufumi; Maeda, Junya; Yoshida, Harumasa

2018-01-01

We report on nitride-based two-stack laser diodes with a tunnel junction for the first time. The stacked laser diode was monolithically grown by metalorganic vapor phase epitaxy. It was confirmed that the two-stack InGaN/GaN multiple-quantum-well laser diode with an emission wavelength of 394 nm exhibited laser oscillation up to a peak output power of over 10 W in the pulsed current mode. The upper and lower emitters of the device were capable of lasing at different threshold currents of 2.4 and 5.2 A with different slope efficiencies of 0.8 and 0.3 W/A, respectively.

Effect of Initiators on Thermal Changes in Soft Tissues Using a Diode Laser.

PubMed

Romanos, Georgios E; Sacks, Danielle; Montanaro, Nicholas; Delgado-Ruiz, Rafael; Calvo-Guirado, Jose Luis; Javed, Fawad

2018-06-15

The aim was to determine the effect of various initiators on the thermal changes that occur during incisions performed in soft tissues using a diode laser. There are no studies that have assessed the effect of various initiators on the thermal changes that occur during incisions performed in soft tissues using a diode laser. Thermal changes were observed during standardized incisions in chicken breast (without skin) via thermoelements over a 10-sec irradiation period. Incisions were created using a 975 nm diode laser with a 320 μ fiber tip diameter. Incisions (10 in each group) were performed with and without an initiator (control group). Red/blue articulating paper, cork, and SureStep ® were used as initiators. The tissue was irradiated in a continuous wave mode at 3 and 6 W in room temperature (21°C). At 3 and 6 W without any initiator, the mean temperature increased by 5.7°C versus 12.4°C, respectively. Cork initiator at 3 and 6 W resulted in temperature increase by 4.88°C versus 6.21°C, respectively. Incisions made using the blue/red articulating paper-initiated tip resulted in temperature increase by 2.9/5.8°C versus 8.2/7.6°C at 3 and 6 W power settings, respectively. Initiation with SureStep resulted in temperature increase by 2.3°C and at 6 W by 4.1°C. No significant differences were recorded between the different groups, but higher temperatures were associated with higher power settings. The power settings of the diode laser and type of initiator used, both effect the degree to which the temperature of the soft tissue increases during incisions and have to be considered for the safety in soft tissue applications.

LONG-TERM SD-OCT/SLO IMAGING OF NEURORETINA AND RETINAL PIGMENT EPITHELIUM AFTER SUB-THRESHOLD INFRARED LASER TREATMENT OF DRUSEN

PubMed Central

MOJANA, FRANCESCA; BRAR, MANPREET; CHENG, LINGYUN; BARTSCH, DIRK-UWE G.; FREEMAN, WILLIAM R.

2012-01-01

PURPOSE To determine the long-term effect of sub-threshold diode laser treatment for drusen in patients with non-exudative age-related macular degeneration (AMD) with spectral domain optical coherence tomography combined with simultaneous scanning laser ophthalmoscope (SD-OCT/SLO). METHODS 8 eyes of 4 consecutive AMD patients with bilateral drusen previously treated with sub-threshold diode laser were imaged with SD-OCT/SLO. Abnormalities in the outer retina layers reflectivity as seen with SD-OCT/SLO were retrospectively analyzed and compared with color fundus pictures and autofluorescence images (AF) acquired immediately before and after the laser treatment. RESULTS A focal discrete disruptions in the reflectivity of the outer retinal layers was noted in 29% of the laser lesions. The junction in between the inner and outer segment of the photoreceptor was more frequently affected, with associated focal damage of the outer nuclear layer. Defects of the RPE were occasionally detected. These changes did not correspond to threshold burns on color fundus photography, but corresponded to focal areas of increased AF in the majority of the cases. CONCLUSIONS Sub-threshold diode laser treatment causes long-term disruption of the retinal photoreceptor layer as analyzed by SD-OCT/SLO. The concept that sub-threshold laser treatment can achieve a selected RPE effect without damage to rods and cones may be flawed. PMID:21157398

Comparing the 810nm diode laser with conventional surgery in orthodontic soft tissue procedures.

PubMed

Ize-Iyamu, I N; Saheeb, B D; Edetanlen, B E

2013-09-01

To compare the use of the 810nm diode laser with conventional surgery in the management of soft tissue mucogingival problems associated with orthodontic treatment. Orthodontic patients requiring different soft tissue surgical procedures were randomly assigned to receive conventional surgery or soft tissue diode laser, (wavelength 810 nm). Parameters documented include the type of anaesthesia used, intra and post operative pain, bleeding, the use of scalpel and sutures. The chi-squared test was used to test for significance at 95% confidence level. Probability values (p-values) less than 0.05 were regarded as significant. Only 2(16.7%) of the procedures carried out with the soft tissue laser required infiltration anaesthesia compared to 10 (90.9%) with conventional surgery and this was significant (P<0.001). Post operative pain was significantly reduced in all cases treated with the diode laser (P<0.001). There was also a significant difference (P<0.05) in post operative bleeding in all cases treated with the diode laser. No sutures were used in all soft tissue cases managed with the diode laser and this was significant (P<0.001). There was no statistically significant difference in treatment time in the use of the laser compared with conventional surgery. Orthodontic patients treated with the diode laser required less infiltration anaesthesia, had reduced bleeding during and after surgery, rapid postoperative haemostasis, elimination of the need for sutures and an improved postoperative comfort and healing.

Fast photocatalytic degradation of methylene blue dye using a low-power diode laser.

PubMed

Liu, Xianhua; Yang, Yulou; Shi, Xiaoxuan; Li, Kexun

2015-01-01

This study focused on the application of diode lasers as alternative light sources for the fast photocatalytic degradation of methylene blue. The photocatalytic decomposition of methylene blue in aqueous solution under 443 nm laser light irradiation was found to be technically feasible using Ag/AgCl nanoparticles as photocatalysts. The effects of various experimental parameters, such as irradiation time, light source, catalyst loading, initial dye concentration, pH, and laser energy on decolorization and degradation were investigated. The mineralization of methylene blue was confirmed by chemical oxygen demand analysis. The results demonstrate that the laser-induced photocatalytic process can effectively degrade methylene blue under the optimum conditions (pH 9.63, 4 mg/L MB concentration, and 1.4 g/L Ag/AgCl nanoparticles). Copyright © 2014 Elsevier B.V. All rights reserved.

Solid Sampling with a Diode Laser for Portable Ambient Mass Spectrometry

PubMed Central

2017-01-01

A hand-held diode laser is implemented for solid sampling in portable ambient mass spectrometry (MS). Specifically, a pseudocontinuous wave battery-powered surgical laser diode is employed for portable laser diode thermal desorption (LDTD) at 940 nm and compared with nanosecond pulsed laser ablation at 2940 nm. Postionization is achieved in both cases using atmospheric pressure photoionization (APPI). The laser ablation atmospheric pressure photoionization (LAAPPI) and LDTD-APPI mass spectra of sage leaves (Salvia officinalis) using a field-deployable quadrupole ion trap MS display many similar ion peaks, as do the mass spectra of membrane grown biofilms of Pseudomonas aeruginosa. These results indicate that LDTD-APPI method should be useful for in-field sampling of plant and microbial communities, for example, by portable ambient MS. The feasibility of many portable MS applications is facilitated by the availability of relatively low cost, portable, battery-powered diode lasers. LDTD could also be coupled with plasma- or electrospray-based ionization for the analysis of a variety of solid samples. PMID:28632988

Solid Sampling with a Diode Laser for Portable Ambient Mass Spectrometry.

PubMed

Yung, Yeni P; Wickramasinghe, Raveendra; Vaikkinen, Anu; Kauppila, Tiina J; Veryovkin, Igor V; Hanley, Luke

2017-07-18

A hand-held diode laser is implemented for solid sampling in portable ambient mass spectrometry (MS). Specifically, a pseudocontinuous wave battery-powered surgical laser diode is employed for portable laser diode thermal desorption (LDTD) at 940 nm and compared with nanosecond pulsed laser ablation at 2940 nm. Postionization is achieved in both cases using atmospheric pressure photoionization (APPI). The laser ablation atmospheric pressure photoionization (LAAPPI) and LDTD-APPI mass spectra of sage leaves (Salvia officinalis) using a field-deployable quadrupole ion trap MS display many similar ion peaks, as do the mass spectra of membrane grown biofilms of Pseudomonas aeruginosa. These results indicate that LDTD-APPI method should be useful for in-field sampling of plant and microbial communities, for example, by portable ambient MS. The feasibility of many portable MS applications is facilitated by the availability of relatively low cost, portable, battery-powered diode lasers. LDTD could also be coupled with plasma- or electrospray-based ionization for the analysis of a variety of solid samples.

Application of a 980-nanometer diode laser in neuroendoscopy: a case series.

PubMed

Reis, Rodolfo Casimiro; Teixeira, Manoel Jacobsen; Mancini, Marilia Wellichan; Almeida-Lopes, Luciana; de Oliveira, Matheus Fernandes; Pinto, Fernando Campos Gomes

2016-02-01

Ventricular neuroendoscopy represents an important advance in the treatment of hydrocephalus. High-power (surgical) Nd:YAG laser and low-level laser therapy (using 685-nm-wavelength diode laser) have been used in conjunction with neuroendoscopy with favorable results. This study evaluated the use of surgical 980-nm-wavelength diode laser for the neuroendoscopic treatment of ventricular diseases. Nine patients underwent a neuroendoscopic procedure with 980-nm diode laser. Complications and follow-up were recorded. Three in-hospital postoperative complications were recorded (1 intraventricular hemorrhage and 2 meningitis cases). The remaining 6 patients had symptom improvement after endoscopic surgery and were discharged from the hospital within 24-48 hours after surgery. Patients were followed for an average of 14 months: 1 patient developed meningitis and another died suddenly at home. The other patients did well and were asymptomatic until the last follow-up consultation. The 980-nm diode laser is considered an important therapeutic tool for endoscopic neurological surgeries. This study showed its application in different ventricular diseases.

Efficient Ho:LuLiF4 laser diode-pumped at 1.15 μm.

PubMed

Wang, Sheng-Li; Huang, Chong-Yuan; Zhao, Cheng-Chun; Li, Hong-Qiang; Tang, Yu-Long; Yang, Nan; Zhang, Shuai-Yi; Hang, Yin; Xu, Jian-Qiu

2013-07-15

We report the first laser operation based on Ho(3+)-doped LuLiF(4) single crystal, which is directly pumped with 1.15-μm laser diode (LD). Based on the numerical model, it is found that the "two-for-one" effect induced by the cross-relaxation plays an important role for the laser efficiency. The maximum continuous wave (CW) output power of 1.4 W is produced with a beam propagation factor of M(2) ~2 at the lasing wavelength of 2.066 μm. The slope efficiency of 29% with respect to absorbed power is obtained.

Electronic safing of a diode laser arm-fire device

NASA Astrophysics Data System (ADS)

Willis, Kenneth E.; Chang, Suk T.

1993-06-01

The paper describes a rocket motor arm-fire device which uses a diode laser protected from unintentional function with a specially designed RF frequency attenuating coupler (RFAC). The RFAC transfers power into a Faraday cage via magnetic flux, thereby protecting the diode, its drive circuit, and the pyrotechnic from all electromagnetic and electrostatic hazards. Diagrams of the diode laser arm-fire device are presented together with a diagram illustrating the RFAC principle of operation.

The Impact of a 940 nm Diode Laser with Radial Firing Tip and Bare End Fiber Tip on Enterococcus faecalis in the Root Canal Wall Dentin of Bovine Teeth: An In Vitro Study.

PubMed

Schulte-Lünzum, Ruth; Gutknecht, Norbert; Conrads, Georg; Franzen, Rene

2017-07-01

This in vitro study aimed to compare the bactericidal effect of two different laser delivery systems, a radial firing tip (RFT) and bare end fiber tip (BFT) used with the 940 nm diode laser on Enterococcus faecalis inoculated onto bovine radicular dentin. A total of 100 bovine dentin slices with a defined thickness of 500 and 1000 μm were prepared. They were assigned into four test groups together with untreated samples served as control for each slice thickness. The slices were inoculated on one side with 1 μL E. faecalis suspension and laser irradiation was performed indirectly on the opposite side with the 940 nm diode laser delivered with a 200 μm RFT and a BFT at 1 and 1.5 W in continuous wave mode for 8 sec per cycle and repeated four times. After irradiation, the remaining bacteria were detached and the produced suspension was diluted and plated onto blood agar plates with 5% sheep blood and incubated overnight at 37°C in a CO 2 -rich atmosphere. The colony-forming units of E. faecalis were counted and the bacterial reduction was analyzed. The diode laser equipped with RFT fiber design further reduced the number of vital E. faecalis cells significantly compared with BFT design, regardless of the used power and dentin thickness (p < 0.0001). The highest average value of 4 log kills was observed in 500 μm slice thickness irradiated with RFT at 1.5 W. Temperature measurements on the external root surface at 1 mm from the apex did not elicit a harmful temperature elevation in both power settings and fiber designs. Within the studied parameters, 940 nm diode laser in conjugation with RFT showed a satisfactory bactericidal effect without any thermal side effect to the tooth-supporting tissues.

Respiratory complications after diode-laser-assisted tonsillotomy.

PubMed

Fischer, Miloš; Horn, Iris-Susanne; Quante, Mirja; Merkenschlager, Andreas; Schnoor, Jörg; Kaisers, Udo X; Dietz, Andreas; Kluba, Karsten

2014-08-01

Children with certain risk factors, such as comorbidities or severe obstructive sleep apnea syndrome (OSAS) are known to require extended postoperative monitoring after adenotonsillectomy. However, there are no recommendations available for diode-laser-assisted tonsillotomy. A retrospective chart review of 96 children who underwent diode-laser-assisted tonsillotomy (07/2011-06/2013) was performed. Data for general and sleep apnea history, power of the applied diode-laser (λ = 940 nm), anesthesia parameters, the presence of postoperative respiratory complications and postoperative healing were evaluated. After initially uncomplicated diode-laser-assisted tonsillotomy, an adjustment of post-anesthesia care was necessary in 16 of 96 patients due to respiratory failure. Respiratory complications were more frequent in younger children (3.1 vs. 4.0 years, p = 0.049, 95 % CI -1.7952 to -0.0048) and in children who suffered from nocturnal apneas (OR = 5.00, p < 0.01, 95 % CI 1.4780-16.9152) or who suffered from relevant comorbidities (OR = 4.84, p < 0.01, 95 % CI 1.5202-15.4091). Moreover, a diode-laser power higher than 13 W could be identified as a risk factor for the occurrence of a postoperative oropharyngeal edema (OR = 3.45, p < 0.01, 95 % CI 1.3924-8.5602). Postoperative respiratory complications should not be underestimated in children with sleep-disordered breathing (SDB). Therefore, children with SDB, children with comorbidities or children younger than 3 years should be considered "at risk" and children with confirmed moderate to severe OSAS should be referred to a PICU following diode-laser-assisted tonsillotomy. We recommend a reduced diode-laser power (<13 W) to reduce oropharyngeal edema.

Theoretical study on the thermal and optical features of a diode side-pumped alkali laser

NASA Astrophysics Data System (ADS)

Han, Juhong; Liu, Xiaoxu; Wang, Hongyuan; Cai, He; An, Guofei; Zhang, Wei; Wang, You

2018-03-01

As one of the most hopeful candidates to achieve high power performances, a diode-pumped alkali laser (DPAL) has attracted a lot of attention in the last decade. Comparing with a diode end-pumped alkali laser (DEPAL), a diode side-pumped alkali laser (DSPAL) has great potentiality to realize an even-higher output of alkali lasers. However, there are few related researching studies concern DSPAL. In this paper, we introduce a theoretical model to investigate the physical features of a double-directions side-pumped alkali laser. The distributions of the population density, temperature, and absorption power at the cross section of a vapor cell are systematically studied. The analyses should be valuable for design of a steady high-powered DPAL.

Update on the use of diode laser in the management of benign prostate obstruction in 2014.

PubMed

Lusuardi, Lukas; Mitterberger, Michael; Hruby, Stephan; Kunit, Thomas; Kloss, Birgit; Engelhardt, Paul F; Sieberer, Manuela; Janetschek, Günter

2015-04-01

To determine the status quo in respect of various diode lasers and present the techniques in use, their results and complications. We assess how these compare with transurethral resection of the prostate and other types of laser in randomized controlled trials (RCTs). When adequate RCTs were not available, case studies and reports were evaluated. Laser for the treatment of benign prostatic hyperplasia (BPH) has aroused the interest and curiosity of urologists as well as patients. The patient associates the term laser with a successful and modern procedure. The journey that started with coagulative necrosis of prostatic adenoma based on neodymium: yttrium-aluminum-garnet (Nd:YAG) laser has culminated in endoscopic "enucleation" with holmium laser. Diode laser is being used in urology for about 10 years now. Various techniques have been employed to relieve bladder outlet obstruction due to BPH. The diode laser scenario is marked by a diversity of surgical techniques and wavelengths. We summarize the current published literature in respect of functional results and complications. More randomized controlled studies are needed to determine the position and the ideal technique of diode laser treatment for BPH.

CO.sub.2 optically pumped distributed feedback diode laser

DOEpatents

Rockwood, Stephen D.

1980-01-01

A diode laser optically pumped by a CO.sub.2 coherent source. Interference fringes generated by feeding the optical pumping beam against a second beam, periodically alter the reflectivity of the diode medium allowing frequency variation of the output signal by varying the impingent angle of the CO.sub.2 laser beams.

Indocyanine green-laser thermolysis of acne vulgaris

NASA Astrophysics Data System (ADS)

Genina, Elina A.; Bashkatov, Alexey N.; Simonenko, Georgy V.; Tuchin, Valery V.; Yaroslavsky, Ilya V.; Altshuler, Gregory B.

2005-08-01

The near-infrared (NIR) laser radiation due to its high penetration depth is widely used in phototherapy and photothermolysis. In application to skin appendages a high selectivity of laser treatment is needed to prevent light action on surrounding tissues. Indocyanine Green (ICG) dye may provide a high selectivity of treatment due to effective ICG uploading by a target and its narrow band of considerable absorption just at the wavelength of the NIR diode laser. The goal of this study is to demonstrate the efficacy of the NIR diode laser photothermolysis in combination with topical application of ICG suggested for treatment of acne vulgaris. Two volunteers with back-located acne were enrolled. Skin sites of subjects were stained by ICG and irradiated by NIR laser-diode light (803 or 809 nm). The individual acne lesions were photothermally treated at 18 W/cm2 (803 nm, 0.5 sec) without skin surface cooling or at 200 W/cm2 (809 nm, 0.5 sec) with cooling. The results of the observations during a month after the treatment have shown that ICG stained acne inflammatory elements were destructed for light exposures of 0.5 sec.

Four-Pass Coupler for Laser-Diode-Pumped Solid-State Laser

NASA Technical Reports Server (NTRS)

Coyle, Donald B.

2008-01-01

A four-pass optical coupler affords increased (in comparison with related prior two-pass optical couplers) utilization of light generated by a laser diode in side pumping of a solid-state laser slab. The original application for which this coupler was conceived involves a neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal slab, which, when pumped by a row of laser diodes at a wavelength of 809 nm, lases at a wavelength of 1,064 nm. Heretofore, typically, a thin laser slab has been pumped in two passes, the second pass occurring by virtue of reflection of pump light from a highly reflective thin film on the side opposite the side through which the pump light enters. In two-pass pumping, a Nd:YAG slab having a thickness of 2 mm (which is typical) absorbs about 84 percent of the 809-nm pump light power, leaving about 16 percent of the pump light power to travel back toward the laser diodes. This unused power can cause localized heating of the laser diodes, thereby reducing their lifetimes. Moreover, if the slab is thinner than 2 mm, then even more unused power travels back toward the laser diodes. The four-pass optical coupler captures most of this unused pump light and sends it back to the laser slab for two more passes. As a result, the slab absorbs more pump light, as though it were twice as thick. The gain and laser cavity beam quality of a smaller laser slab in conjunction with this optical coupler can thus be made comparable to those of a larger two-pass-pumped laser slab.

Resonantly diode-pumped continuous-wave and Q-switched Er:YAG laser at 1645 nm.

PubMed

Chang, N W H; Simakov, N; Hosken, D J; Munch, J; Ottaway, D J; Veitch, P J

2010-06-21

We describe an efficient Er:YAG laser that is resonantly pumped using continuous-wave (CW) laser diodes at 1470 nm. For CW lasing, it emits 6.1 W at 1645 nm with a slope efficiency of 36%, the highest efficiency reported for an Er:YAG laser that is pumped in this manner. In Q-switched operation, the laser produces diffraction-limited pulses with an average power of 2.5 W at 2 kHz PRF. To our knowledge this is the first Q-switched Er:YAG laser resonantly pumped by CW laser diodes.

Integrated injection-locked semiconductor diode laser

DOEpatents

Hadley, G.R.; Hohimer, J.P.; Owyoung, A.

1991-02-19

A continuous wave integrated injection-locked high-power diode laser array is provided with an on-chip independently-controlled master laser. The integrated injection locked high-power diode laser array is capable of continuous wave lasing in a single near-diffraction limited output beam at single-facet power levels up to 125 mW (250 mW total). Electronic steering of the array emission over an angle of 0.5 degrees is obtained by varying current to the master laser. The master laser injects a laser beam into the slave array by reflection of a rear facet. 18 figures.

Generation conditions of CW Diode Laser Sustained Plasma

NASA Astrophysics Data System (ADS)

Nishimoto, Koji; Matsui, Makoto; Ono, Takahiro

2016-09-01

Laser sustained plasma was generated using 1 kW class continuous wave diode laser. The laser beam was focused on the seed plasma generated by arc discharge in 1 MPa xenon lamp. The diode laser has advantages of high energy conversion efficiency of 80%, ease of maintenance, compact size and availability of conventional quartz based optics. Therefore, it has a prospect of further development compared with conventional CO2 laser. In this study, variation of the plasma shape caused by laser power is observed and also temperature distribution in the direction of plasma radius is measured by optical emission spectroscopy.

Characterization of diode-laser stacks for high-energy-class solid state lasers

NASA Astrophysics Data System (ADS)

Pilar, Jan; Sikocinski, Pawel; Pranowicz, Alina; Divoky, Martin; Crump, P.; Staske, R.; Lucianetti, Antonio; Mocek, Tomas

2014-03-01

In this work, we present a comparative study of high power diode stacks produced by world's leading manufacturers such as DILAS, Jenoptik, and Quantel. The diode-laser stacks are characterized by central wavelength around 939 nm, duty cycle of 1 %, and maximum repetition rate of 10 Hz. The characterization includes peak power, electrical-to-optical efficiency, central wavelength and full width at half maximum (FWHM) as a function of diode current and cooling temperature. A cross-check of measurements performed at HiLASE-IoP and Ferdinand-Braun-Institut (FBH) shows very good agreement between the results. Our study reveals also the presence of discontinuities in the spectra of two diode stacks. We consider the results presented here a valuable tool to optimize pump sources for ultra-high average power lasers, including laser fusion facilities.

Laser Space Propulsion Overview (Postprint)

DTIC Science & Technology

2006-09-01

meet with currently fielded thruster technology. However, a laser-ablation propulsion engine using a set of diode-pumped glass fiber amplifiers with a...with Cm = 56µN/W and ηAB = 100%. These two units will be combined in a single device using low-mass diode-pumped glass fiber laser amplifiers to...advantage of extremely lightweight diode-pumped glass fiber lasers onboard the spacecraft to provide thrust with variable Isp and unmatched thrust

Influence of high power 405 nm multi-mode and single-mode diode laser light on the long-term stability of fused silica fibers

NASA Astrophysics Data System (ADS)

Gonschior, C. P.; Klein, K.-F.; Sun, T.; Grattan, K. T. V.

2012-04-01

As the demand for high power fiber-coupled violet laser systems increases existing problems remain. The typical power of commercially available diode lasers around 400 nm is in the order of 100 to 300 mW, depending on the type of laser. But in combination with the small core of single-mode fibers reduced spot sizes are needed for good coupling efficiencies, leading to power densities in the MW/cm2 range. We investigated the influence of 405 nm laser light irradiation on different fused silica fibers and differently treated end-faces. The effect of glued-and-polished, cleaved-and-clamped and of cleaved-and-fusion-arc-treated fiber end-faces on the damage rate and behavior are presented. In addition, effects in the deep ultra-violet were determined spectrally using newest spectrometer technology, allowing the measurement of color centers around 200 nm in small core fibers. Periodic surface structures were found on the proximal end-faces and were investigated concerning generation control parameters and composition. The used fiber types range from low-mode fiber to single-mode and polarization-maintaining fiber. For this investigation 405 nm single-mode or multi-mode diode lasers with 150 mW or 300 mW, respectively, were employed.

Temperature issues with white laser diodes, calculation and approach for new packages

NASA Astrophysics Data System (ADS)

Lachmayer, Roland; Kloppenburg, Gerolf; Stephan, Serge

2015-01-01

Bright white light sources are of significant importance for automotive front lighting systems. Today's upper class systems mainly use HID or LED light sources. As a further step laser diode based systems offer a high luminance, efficiency and allow the realization of new dynamic and adaptive light functions and styling concepts. The use of white laser diode systems in automotive applications is still limited to laboratories and prototypes even though announcements of laser based front lighting systems have been made. But the environment conditions for vehicles and other industry sectors differ from laboratory conditions. Therefor a model of the system's thermal behavior is set up. The power loss of a laser diode is transported as thermal flux from the junction layer to the diode's case and on to the environment. Therefor its optical power is limited by the maximum junction temperature (for blue diodes typically 125 - 150 °C), the environment temperature and the diode's packaging with its thermal resistances. In a car's headlamp the environment temperature can reach up to 80 °C. While the difference between allowed case temperature and environment temperature is getting small or negative the relevant heat flux also becomes small or negative. In early stages of LED development similar challenges had to be solved. Adapting LED packages to the conditions in a vehicle environment lead to today's efficient and bright headlights. In this paper the need to transfer these results to laser diodes is shown by calculating the diodes lifetimes based on the presented model.

Comparison of 1470nm diode laser vs. C02-laserlaser for tonsillotomy and a clinical feasability trial on the use of 1940nm in ENT

NASA Astrophysics Data System (ADS)

Sroka, Ronald; Pongratz, Thomas; Havel, Miriam; Englert, Elsa; Kremser, Thomas; Betz, Christain S.; Leunig, Andreas

2013-03-01

Introduction: The need for reduction of post-tonsillectomy hemorrhage has led to promotion of tonsillotomy techniques for tonsil tissue reduction in obstructive tonsillar hypertrophy. A first study compares ablative tissue effects using 1470nm diode laser and CO2-laser for tonsillotomy in an intraindividual design. A number of different laser systems have been used for volume reduction of hyperplastic nasal turbinates. The aim of a 2nd clinical feasibility study was to show the coagulative and tissue reducing effects using a novel Tm: fiber laser system emitting at λ = 1940 nm Patients and methods: First 21 children aged 3 -13 years (mean age 6.3 years) underwent laser tonsillotomy for obstructive tonsillar hypertrophy in this double blind, prospective, randomized, clinical feasibility trial. In each case, tonsillotomy was performed using fibre guided 1470nm diode laser (contact mode, 15 W power) on the one side and CO2-laser (12 W power) on the other side. An independent physician documented clinical presentation and patients' symptoms preoperatively and on day 1, 3, 7, 14 and 21 postoperatively using standardized questionnaire including VAS (was ist das) for each side separately. The 2nd clinical feasibility trial included 11 patients suffering from hyperplastic inferior nasal turbinates, who were therapy-refractory to conservative medical treatment. The obstructive nasal cavity was treated using the 1940 nm Tm: fiber laser at < 5 W output power. The treatment was performed in non-contact mode under endoscopic control. Patients ' symptoms were documented both preoperatively and on days 1 - 3 and 28 postoperatively using a non-validated questionnaire. Additionally, an endoscopic examination was performed. Results: Mean duration of single tonsillotomy operative treatment was 2.7 min using 1470nm laser and 4.9 min using CO2 laser respectively. Intraoperative bleeding and the frequency of bipolar forceps use for intraoperative bleeding control was significantly less pronounced using the 1470nm diode laser system. There was no difference in postoperative pain scores between the CO2-laser treated and the 1470nm fibre guided diode laser treated side. No infections, hemorrhages or other complications occurred in the course of the three weeks postoperative period. In the turbinate study, none of the patients showed infections, and no hemorrhages or other complications occurred intraor postoperatively.The mean laser activation time was extremely short being 28.0 +/- 8.5 s. In conjunction with a low power setting (median, 3 W; mean +/- standard deviation, 3.3 +/- 1.1 W), a low energy of 90.2 +/- 37.8 J was applied. A significant reduction in nasal obstruction could be documented in all patients on day 28 postoperatively. Evaluation, as assessed preoperatively and 4 weeks postoperatively, showed significant subjective improvements. Conclusion: A fiber-guided 1470nm diode laser system offers an efficient and safe method for tonsillotomy as treatment of obstructive tonsillar hypertrophy. Compared to our standard practice with CO2- laser, 1470nm laser application provides comparable tissue ablation effects with less intraoperative bleeding and shorter operation time. The treatment of hyperplastic inferior turbinates using a 1940 nm Tm: fiber laser provides sufficient tissue reduction in a short operation time using low total energy. Patients described a significant improvement in nasal breathing postoperatively.

AlGaInN laser diode technology for free-space telecom applications

NASA Astrophysics Data System (ADS)

Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Boćkowski, M.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Kucharski, R.; Targowski, G.; Watson, S.; Kelly, A. E.; Watson, M. A.; Blanchard, P.; White, H.

2015-03-01

The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well. We consider the suitability of AlGaInN laser diode technology for free space laser communication, both airborne links and underwater telecom applications, mainly for defense and oil and gas industries.

Semiconductor Laser with a Self-Pumped Phase Conjugate External Cavity

DTIC Science & Technology

1992-10-01

laser light is considered planar. In actuality, the HLP 1400 laser diode used in this experiment has a gaussian profile. This approximation is frequently...return beam is in phase with either the light transmitted through or reflected off the rear facet of the diode laser. In Fig. 3.2, E, is the light ...In the first case an anti-reflection coated laser diode was used. It emitted a broadband spectrum without the feedback. The PCM just lowered the

Bioeffect of lipohemia rabbits irradiated in oral mucosa with 650-nm diode-laser-accompanied oxygen inspiration and clinical application

NASA Astrophysics Data System (ADS)

Yang, Fu-Shou; Tang, Jin-Xian; Liu, Cheng; Yang, Xi-Cheng; Pang, Hi-Xiu

1998-11-01

The study on irradiating in oral mucosa of rabbits with 650 nm diode laser and clinical application has been reported in this paper. The result of animal experiment showed: the obvious decrease of cholesterin and triglyceride has been found among those highly lipohemia rabbits in the experiments of 650nm diode laser irradiating accompanying with oxygen, as well as the parameters of hemorheology obviously being improved, as compared with highly lipohemia rabbits un-irradiating, the statistical analysis showing P < 0.01. In the meantime, the observation of histopathology shows, the lipide decreasing in aorta wall, intramyocardinal membranous layer,and renal interstitial in the group of rabbits which are irradiated with laser and accompanying with oxygen inspiration, and even the perfectly recovered tissue in some rabbits has been seen. This experimental result is significantly for clinical application. The results of clinic application showed, that the patients employed this method which treatment cerebral infarction, lipohemia, the total effective ratio achieved 91.7 percent, perfect effect 30.6 percent.

Temperature changes in the pulpal chamber and the sealing performance of various methods of direct pulp capping of primary teeth.

PubMed

Yilmaz, Y; Keles, S; Mete, A

2013-06-01

To compare changes in pulpal chamber temperature during the visible-light curing of direct pulp capping compounds and various modes of diode laser irradiation without prior placement of a pulp capping compound and the resultant seals. Pulp exposure holes were made in 100 extracted human primary first molars, which were randomly assigned to ten equal groups. The holes were sealed by (a= Group 1, 2, 3, 4, 5, 6 and 7) different pulp capping compounds which were cured using various types of visible-light curing units or (b=Group 8, 9 and 10) diode laser irradiation without prior application of a pulp capping compound. Pulpal chamber temperatures were recorded during the procedure, and the resultant seals were examined under a scanning electron microscope. Visible-light curing of the pulp capping compounds and diode laser irradiation at a 0.7 W output power can cause non-injurious temperature rises in the pulpal chamber. At higher output powers of the diode laser, the temperature rises are sufficient to cause thermal injury. The seals were complete when pulp capping compounds were used for direct pulp capping, but were incomplete when laser irradiation without prior placement of a pulp capping compound was used for the identical purpose. The visible-light curing of pulp capping compounds is not harmful to vital pulp, and provides an effective seal of the pulp exposure hole. Laser irradiation is not an effective sealant, and can cause thermal injury to vital pulp at high output powers.

High efficient bone ablation with diode pumped Erbium and Thulium lasers including different delivery fibers: a comparative in vitro study

NASA Astrophysics Data System (ADS)

Stock, Karl; Hausladen, Florian; Stegmayer, Thomas; Wurm, Holger

2018-02-01

Er:YAG lasers (3μm) allow efficient bone ablation caused by the strong absorption in water. Unfortunately, there are only a few and comparable expensive fiber materials for this wavelength available which are suitable for high laser power. The bone ablation efficiency of the Tm:YAG laser is minor (2μm) but inexpensive silica fibers can be used. The aim of this study was to investigate the bone ablation, using novel diode pumped high power Er:YAG (laser power 40W) and Tm:YAG laser system (60W) and adaptive fiber delivery systems. Expected advantage of these lasers is the longer lifetime of the fibers because of the high repetition rate and low pulse energy compared to the flash lamp pumped laser systems. The bare fiber output ends of a sapphire fiber (Er:YAG laser) and of a silica fiber (Tm:YAG laser) were attached under water and a water filled container including the fixed sample (bovine bone slices) was moved by a computer controlled translation stage. In a second set-up we provided a focusing unit and appropriate water spray unit. The generated cut kerfs were analyzed by light microcopy and laser scanning microscopy. The results show that with the diode pumped Er:YAG laser and sapphire fiber a particular high efficient bone ablation (> 0.16mm2/J) is possible both with bare fiber under water and focusing unit with water spray. The higher power of the Tm:YAG laser also results in high ablation rates but causes enlarged thermal damages. In conclusion, this study demonstrates that efficient bone ablation is possible with both diode pumped laser systems. In terms of efficiency the Er:YAG laser is outstanding. The Tm:YAG laser also allows fast bone ablation, provided that the thermal impact is limited by effective cooling and high movement velocity of the laser spot, for example by using an automatic scanner.

Overview on new diode lasers for defense applications

NASA Astrophysics Data System (ADS)

Neukum, Joerg

2012-11-01

Diode lasers have a broad wavelength range, from the visible to beyond 2.2μm. This allows for various applications in the defense sector, ranging from classic pumping of DPSSL in range finders or target designators, up to pumping directed energy weapons in the 50+ kW range. Also direct diode applications for illumination above 1.55μm, or direct IR countermeasures are of interest. Here an overview is given on some new wavelengths and applications which are recently under discussion. In this overview the following aspects are reviewed: • High Power CW pumps at 808 / 880 / 940nm • Pumps for DPAL - Diode Pumped Alkali Lasers • High Power Diode Lasers in the range < 1.0 μm • Scalable Mini-Bar concept for high brightness fiber coupled modules • The Light Weight Fiber Coupled module based on the Mini-Bar concept Overall, High Power Diode Lasers offer many ways to be used in new applications in the defense market.

Improving confocal microscopy with solid-state semiconductor excitation sources

NASA Astrophysics Data System (ADS)

Sivers, Nelson L.

To efficiently excite the fluorescent dyes used in imaging biological samples with a confocal microscope, the wavelengths of the exciting laser must be near the fluorochrome absorption peak. However, this causes imaging problems when the fluorochrome absorption and emission spectra overlap significantly, i.e. have small Stokes shifts, which is the case for most fluorochromes that emit in the red to infrared. As a result, the reflected laser excitation cannot be distinguished from the information-containing fluorescence signal. However, cryogenically cooling the exciting laser diode enabled the laser emission wavelengths to be tuned to shorter wavelengths, decreasing the interference between the laser and the fluorochrome's fluorescence. This reduced the amount of reflected laser light in the confocal image. However, the cooled laser diode's shorter wavelength signal resulted in slightly less efficient fluorochrome excitation. Spectrophotometric analysis showed that as the laser diodes were cooled, their output power increased, which more than compensated for the lower fluorochrome excitation and resulted in significantly more intense fluorescence. Thus, by tuning the laser diode emission wavelengths away from the fluorescence signal, less reflected laser light and more fluorescence information reached the detector, creating images with better signal to noise ratios. Additionally, new, high, luminous flux, light-emitting diodes (LEDs) are now powerful enough to create confocal fluorescence signals comparable to those produced by the traditional laser excitation sources in fluorescence confocal microscopes. The broader LED spectral response effectively excited the fluorochrome, yet was spectrally limited enough for standard filter sets to separate the LED excitation from the fluorochrome fluorescence signal. Spectrophotometric analysis of the excitation and fluorescence spectra of several fluorochromes showed that high-powered, LED-induced fluorescence contained the same spectral information and could be more intense than that produced by lasers. An alternative, LED-based, confocal microscope is proposed in this thesis that would be capable of exciting multiple fluorochromes in a single specimen, producing images of several distinct cellular components simultaneously. The inexpensive, LED-based, confocal microscope would require lower peak excitation intensities to produce fluorescence signals equal to those produced by laser excitation, reducing cellular damage and slowing fluorochrome photobleaching.

Nd:GdVO4 ring laser pumped by laser diodes

NASA Astrophysics Data System (ADS)

Hao, E. J.; Li, T.; Wang, Z. D.; Zhang, Y.

2013-02-01

The design and operation of a laser diode-pumped Nd:GdVO4 ring laser is described. A composite crystal (Nd:GdVO4/YVO4) with undoped ends is single-end pumped by a fiber-coupled laser diode (LD) at 808 nm. A four-mirror ring cavity is designed to keep the laser operating unidirectionally, which eliminates spatial hole burning in the standing-wave cavity. This laser can operate either as continuous wave (CW) or Q-switched. The single-frequency power obtained was 9.1 W at 1063 nm. Q-switched operation produced 0.23 mJ/pulse at 20 kHz in the fundamental laser.

Quasi-passive heat sink for high-power laser diodes

NASA Astrophysics Data System (ADS)

Vetrovec, John

2009-02-01

We report on a novel heat sink for high-power laser diodes offering unparalleled capacity in high-heat flux handling and temperature control. The heat sink uses a liquid coolant flowing at high speed in a miniature closed and sealed loop. Diode waste heat is received at high flux and transferred to environment, coolant fluid, heat pipe, or structure at a reduced flux. When pumping solid-state or alkali vapor lasers, diode wavelength can be electronically tuned to the absorption features of the laser gain medium. This paper presents the heat sink physics, engineering design, performance modeling, and configurations.

[Gas pipeline leak detection based on tunable diode laser absorption spectroscopy].

PubMed

Zhang, Qi-Xing; Wang, Jin-Jun; Liu, Bing-Hai; Cai, Ting-Li; Qiao, Li-Feng; Zhang, Yong-Ming

2009-08-01

The principle of tunable diode laser absorption spectroscopy and harmonic detection technique was introduced. An experimental device was developed by point sampling through small multi-reflection gas cell. A specific line near 1 653. 7 nm was targeted for methane measurement using a distributed feedback diode laser as tunable light source. The linearity between the intensity of second harmonic signal and the concentration of methane was determined. The background content of methane in air was measured. The results show that gas sensors using tunable diode lasers provide a high sensitivity and high selectivity method for city gas pipeline leak detection.

Safety of laser use under the dental microscope.

PubMed

Saegusa, Hidetoshi; Watanabe, Satoshi; Anjo, Tomoo; Ebihara, Arata; Suda, Hideaki

2010-04-01

The aim of this study was to investigate the safety of laser use under the dental microscope. Nd:YAG, Er:YAG and diode lasers were used. The end of the tips was positioned at a distance of 5 cm from the objective lens of a dental microscope. Each eye protector was made into a flat disc, which was fixed on the lens of the microscope. The filters were placed in front of the objective lens or behind the eye lens. Transmitted energy through the microscope with or without the filters was measured. No transmitted laser energy was detected when using matched eye protectors. Mismatched eye protectors were not effective for shutting out laser energy, especially for Nd:YAG and diode lasers. None or very little laser energy was detected through the microscope even without any laser filter. Matched filters shut out all laser energy irrespective of their positions.

Primary investigations on the potential of a novel diode pumped Er:YAG laser system for middle ear surgery

NASA Astrophysics Data System (ADS)

Stock, Karl; Wurm, Holger; Hausladen, Florian

2016-02-01

Flashlamp pumped Er:YAG lasers are successfully used clinically for both precise soft and hard tissue ablation. Since several years a novel diode pumped Er:YAG laser system (Pantec Engineering AG) is available, with mean laser power up to 40 W and pulse repetition rate up to 1 kHz. The aim of the study was to investigate the suitability of the laser system specifically for stapedotomy. Firstly an experimental setup was realized with a beam focusing unit and a computer controlled translation stage to move the samples (slices of porcine bone) with a defined velocity while irradiation with various laser parameters. A microphone was positioned in a defined distance to the ablation point and the resulting acoustic signal of the ablation process was recorded. For comparison, measurements were also performed with a flash lamp pumped Er:YAG laser system. After irradiation the resulting ablation quality and efficacy were determined using light microscopy. Using a high speed camera and "Töpler-Schlierentechnik" the cavitation bubble in water after perforation of a bone slice was investigated. The results show efficient bone ablation using the diode pumped Er:YAG laser system. Also a decrease of the sound level and of the cavitation bubble volume was observed with decreasing pulse duration. Higher repetition rates lead to a slightly increase of thermal side effects but have no influence on the ablation efficiency. In conclusion, these first experiments demonstrate the high potential of the diode pumped Er:YAG laser system for use in middle ear surgery.

Blood flow measurement in extracorporeal circulation using self-mixing laser diode

NASA Astrophysics Data System (ADS)

Cattini, Stefano; Norgia, Michele; Pesatori, Alessandro; Rovati, Luigi

2010-02-01

To measure blood flow rate in ex-vivo circulation, we propose an optical Doppler flowmeter based on the self-mixing effect within a laser diode (SM-LD). Advantages in adopting SM-LD techniques derive from reduced costs, ease of implementation and limited size. Moreover, the provided contactless sensing allows sensor reuse, hence further cost reduction. Preliminary measurements performed on bovine blood are reported, thus demonstrating the applicability of the proposed measurement method.

Stable CW Single-Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking

NASA Technical Reports Server (NTRS)

Duerksen, Gary L.; Krainak, Michael A.

1999-01-01

Previously, single-frequency semiconductor laser operation using fiber Bragg gratings has been achieved by two methods: 1) use of the FBG as the output coupler for an anti-reflection-coated semiconductor gain element'; 2) pulsed operation of a gain-switched Fabry-Perot laser diode with FBG-optical and RF-electrical feedback. Here, we demonstrate CW single frequency operation from a non-AR coated Fabry-Perot laser diode using only FBG optical feedback. We coupled a nominal 935 run-wavelength Fabry-Perot laser diode to an ultra narrow band (18 pm) FBG. When tuned by varying its temperature, the laser wavelength is pulled toward the centerline of the Bragg grating, and the spectrum of the laser output is seen to fall into three discrete stability regimes as measured by the side-mode suppression ratio.

Generation of 3.5 W of diffraction-limited green light from SHG of a single tapered diode laser in a cascade of nonlinear crystals

NASA Astrophysics Data System (ADS)

Hansen, Anders K.; Jensen, Ole B.; Sumpf, Bernd; Erbert, Götz; Unterhuber, Angelika; Drexler, Wolfgang; Andersen, Peter E.; Petersen, Paul Michael

2014-02-01

Many applications, e.g., within biomedicine stand to benefit greatly from the development of diode laser-based multi- Watt efficient compact green laser sources. The low power of existing diode lasers in the green area (about 100 mW) means that the most promising approach remains nonlinear frequency conversion of infrared tapered diode lasers. Here, we describe the generation of 3.5 W of diffraction-limited green light from SHG of a single tapered diode laser, itself yielding 10 W at 1063 nm. This SHG is performed in single pass through a cascade of two PPMgO:LN crystals with re-focusing and dispersion compensating optics between the two nonlinear crystals. In the low-power limit, such a cascade of two crystals has the theoretical potential for generation of four times as much power as a single crystal without adding significantly to the complexity of the system. The experimentally achieved power of 3.5 W corresponds to a power enhancement greater than 2 compared to SHG in each of the crystals individually and is the highest visible output power generated by frequency conversion of a single diode laser. Such laser sources provide the necessary pump power for biophotonics applications, such as optical coherence tomography or multimodal imaging devices, e.g., FTCARS-OCT, based on a strongly pumped ultrafast Ti:Sapphire laser.

Femtosecond Cr:LiSAF and Cr:LiCAF lasers pumped by tapered diode lasers.

PubMed

Demirbas, Umit; Schmalz, Michael; Sumpf, Bernd; Erbert, Götz; Petrich, Gale S; Kolodziejski, Leslie A; Fujimoto, James G; Kärtner, Franz X; Leitenstorfer, Alfred

2011-10-10

We report compact, low-cost and efficient Cr:Colquiriite lasers that are pumped by high brightness tapered laser diodes. The tapered laser diodes provided 1 to 1.2 W of output power around 675 nm, at an electrical-to-optical conversion efficiency of about 30%. Using a single tapered diode laser as the pump source, we have demonstrated output powers of 500 mW and 410 mW together with slope efficiencies of 47% and 41% from continuous wave (cw) Cr:LiSAF and Cr:LiCAF lasers, respectively. In cw mode-locked operation, sub-100-fs pulse trains with average power between 200 mW and 250 mW were obtained at repetition rates around 100 MHz. Upon pumping the Cr:Colquiriite lasers with two tapered laser diodes (one from each side of the crystal), we have observed scaling of cw powers to 850 mW in Cr:LiSAF and to 650 mW in Cr:LiCAF. From the double side pumped Cr:LiCAF laser, we have also obtained ~220 fs long pulses with 5.4 nJ of pulse energy at 77 MHz repetition rate. These are the highest energy levels reported from Cr:Colquiriite so far at these repetition rates. Our findings indicate that tapered diodes in the red spectral region are likely to become the standard pump source for Cr:Colquiriite lasers in the near future. Moreover, the simplified pumping scheme might facilitate efficient commercialization of Cr:Colquiriite systems, bearing the potential to significantly boost applications of cw and femtosecond lasers in this spectral region (750-1000 nm).

Semiconductor diode laser device adjuvanting intradermal vaccine

PubMed Central

Kimizuka, Yoshifumi; Callahan, John J.; Huang, Zilong; Morse, Kaitlyn; Katagiri, Wataru; Shigeta, Ayako; Bronson, Roderick; Takeuchi, Shu; Shimaoka, Yusuke; Chan, Megan P. K.; Zeng, Yang; Li, Binghao; Chen, Huabiao; Tan, Rhea Y. Y.; Dwyer, Conor; Mulley, Tyler; Leblanc, Pierre; Goudie, Calum; Gelfand, Jeffrey; Tsukada, Kosuke; Brauns, Timothy; Poznansky, Mark C.; Bean, David; Kashiwagi, Satoshi

2017-01-01

A brief exposure of skin to a low-power, non-tissue damaging laser light has been demonstrated to augment immune responses to intradermal vaccination. Both preclinical and clinical studies show that this approach is simple, effective, safe and well tolerated compared to standard chemical or biological adjuvants. Until now, these laser exposures have been performed using a diode-pumped solid-state laser (DPSSL) devices, which are expensive and require labor-intensive maintenance and special training. Development of an inexpensive, easy-to-use and small device would form an important step in translating this technology toward clinical application Here we report that we have established a handheld, near-infrared (NIR) laser device using semiconductor diodes emitting either 1061, 1258, or 1301 nm light that costs less than $4,000, and that this device replicates the adjuvant effect of a DPSSL system in a mouse model of influenza vaccination. Our results also indicate that a broader range of NIR laser wavelengths possess the ability to enhance vaccine immune responses, allowing engineering options for the device design. This small, low-cost device establishes the feasibility of using a laser adjuvant approach for mass-vaccination programs in a clinical setting, opens the door for broader testing of this technology with a variety of vaccines and forms the foundation for development of devices ready for use in the clinic. PMID:28365253

Semiconductor diode laser device adjuvanting intradermal vaccine.

PubMed

Kimizuka, Yoshifumi; Callahan, John J; Huang, Zilong; Morse, Kaitlyn; Katagiri, Wataru; Shigeta, Ayako; Bronson, Roderick; Takeuchi, Shu; Shimaoka, Yusuke; Chan, Megan P K; Zeng, Yang; Li, Binghao; Chen, Huabiao; Tan, Rhea Y Y; Dwyer, Conor; Mulley, Tyler; Leblanc, Pierre; Goudie, Calum; Gelfand, Jeffrey; Tsukada, Kosuke; Brauns, Timothy; Poznansky, Mark C; Bean, David; Kashiwagi, Satoshi

2017-04-25

A brief exposure of skin to a low-power, non-tissue damaging laser light has been demonstrated to augment immune responses to intradermal vaccination. Both preclinical and clinical studies show that this approach is simple, effective, safe and well tolerated compared to standard chemical or biological adjuvants. Until now, these laser exposures have been performed using a diode-pumped solid-state laser (DPSSL) devices, which are expensive and require labor-intensive maintenance and special training. Development of an inexpensive, easy-to-use and small device would form an important step in translating this technology toward clinical application. Here we report that we have established a handheld, near-infrared (NIR) laser device using semiconductor diodes emitting either 1061, 1258, or 1301nm light that costs less than $4000, and that this device replicates the adjuvant effect of a DPSSL system in a mouse model of influenza vaccination. Our results also indicate that a broader range of NIR laser wavelengths possess the ability to enhance vaccine immune responses, allowing engineering options for the device design. This small, low-cost device establishes the feasibility of using a laser adjuvant approach for mass-vaccination programs in a clinical setting, opens the door for broader testing of this technology with a variety of vaccines and forms the foundation for development of devices ready for use in the clinic. Copyright © 2017 Elsevier Ltd. All rights reserved.

Shock isolator for diode laser operation on a closed-cycle refrigerator

NASA Technical Reports Server (NTRS)

Jennings, D. E.; Hillman, J. J.

1977-01-01

Closed-cycle helium refrigerators are widely used as coolers for semiconductor diode lasers. These refrigerators pose several difficulties including temperature oscillations due to varying refrigerator capacity during the Solvay cycle, and impact shocks delivered to the diode in the cycle's expansion phase. A shock isolator has been designed to isolate diode lasers from such impact shocks. Slow diode current scans have been made before installation of the shock isolator, with the isolator but no thermal damper, and with both devices. With the isolator and no damper, the diode output frequency oscillated at the refrigerator cycle rate, deviating by plus or minus 40 MHz. Using the isolator and the damper no frequency fluctuation was detected.

Novel Optical Methods for Identification, Imaging, and Preservation of the Cavernous Nerves Responsible for Penile Erections during Prostate Cancer Surgery

DTIC Science & Technology

2011-03-01

epartment of Physics and Optical Science harlotte, North Carolina 28223 homas P. Weldon niversity of North Carolina at Charlotte epartment of...Lens Glass Ferrule Visible Diode Laser IR Diode Laser 90% 10% Fiber Coupler 10/90 (SMF-28) Butterfly Diode Laser Mount 1420 1430 147014501440

Diode laser for the treatment of telangiectasias following hemangioma involution.

PubMed

Cerrati, Eric W; O, Teresa M; Chung, Hoyun; Waner, Milton

2015-02-01

Infantile hemangiomas are well known for their rapid growth during the first 6 to 9 months of life, followed by a spontaneous but slow involution. The standard of care is to treat these lesions at an early age with propranolol to expedite the involution process; however, surgery still remains an active component in the management. Medical treatment with propranolol or natural involution will often result in residual telangiectasias. We evaluated the efficacy of using a diode laser as a treatment for telangiectasias following cervicofacial infantile hemangioma involution. Case series with chart review. Tertiary care hospital and practice specializing in the care of vascular anomalies. Twenty patients, aged 4 months to 11 years (average 2.69 years), underwent treatment with a 532-nm diode laser to treat the residual telangiectasias following hemangioma involution. All procedures were performed in the operating room. To assess the efficacy, we independently evaluated pre- and posttreatment digital photographs and ranked them on a 0- to 4-point scale (0 = no change and 4 = complete response). Adverse reactions were also recorded. The telangiectasias showed considerable improvement following treatment. In more than half of the patients treated, the affected area demonstrated a complete response. No adverse reactions were noted. A 532-nm diode laser effectively treats the remaining telangiectasias following hemangioma involution. Whether used independently or in conjunction with other treatment modalities, the diode laser should be part of the surgical armamentarium when treating infantile hemangiomas. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2014.

The Safety and Efficacy of Treatment With a 1,927-nm Diode Laser With and Without Topical Hydroquinone for Facial Hyperpigmentation and Melasma in Darker Skin Types.

PubMed

Vanaman Wilson, Monique J; Jones, Isabela T; Bolton, Joanna; Larsen, Lisa; Fabi, Sabrina Guillen

2018-04-13

The nonablative, fractional, 1,927-nm diode laser is theoretically a safe and effective treatment for hyperpigmentation and melasma in darker skin and may potentiate topical cosmeceutical delivery. To evaluate the use of a nonablative, fractional, 1,927-nm diode laser with and without topical 2% hydroquinone (HQ) cream for moderate-to-severe facial hyperpigmentation in Fitzpatrick skin Types III-V. Forty adults underwent 4 laser treatments at 2-week intervals and were randomized to daily application of 2% HQ cream or moisturizer. Follow-ups were conducted 4 and 12 weeks after the final laser treatment. Hydroquinone and moisturizer groups demonstrated Mottled Pigmentation Area and Severity Index improvements of approximately 50% at post-treatment Weeks 4 and 12. Blinded investigator-assessed hyperpigmentation and photodamage improved significantly for both the groups at post-treatment Weeks 4 and 12. Subject satisfaction improved significantly in both the groups by post-treatment Week 4. Although investigator-rated Global Aesthetic Improvement Scale scores were significantly better in the HQ group at post-treatment Week 12, satisfaction was higher among those using moisturizer. No adverse events were noted. The nonablative, fractional, 1,927-nm diode laser produced significant improvement in hyperpigmentation in Fitzpatrick skin Types III-V by 4 weeks, with maintenance of results at 12 weeks after treatment even without HQ.

Diode-side-pumped intracavity frequency-doubled Nd:YAG/BaWO4 Raman laser generating average output power of 3.14 W at 590 nm.

PubMed

Li, Shutao; Zhang, Xingyu; Wang, Qingpu; Zhang, Xiaolei; Cong, Zhenhua; Zhang, Huaijin; Wang, Jiyang

2007-10-15

We report a linear-cavity high-power all-solid-state Q-switched yellow laser. The laser source comprises a diode-side-pumped Nd:YAG module that produces 1064 nm fundamental radiation, an intracavity BaWO(4) Raman crystal that generates a first-Stokes laser at 1180 nm, and a KTP crystal that frequency doubles the first-Stokes laser to 590 nm. A convex-plane cavity is employed in this configuration to counteract some of the thermal effect caused by high pump power. An average output power of 3.14 W at 590 nm is obtained at a pulse repetition frequency of 10 kHz.

A Treatment of Amblyopia Using Laser Diodes

NASA Astrophysics Data System (ADS)

Wang, Di; Wang, Yi-Ding; Liu, Bing-Chun

2000-04-01

We propose the treatment of amblyopia using yellow-green laser diodes. There are amblyopia children in excess of fifty million in the world. Because the causative agent of amblyopia hasn't been well understood,only roughly considered to be concerned with visual sense cell, optic nerve network and function of nerve center, no appropriate treatment is found up to date. The vision of person is determined by the center hollow region of retina, where there are three kinds of cone cell. The corresponding peak wavelength in absorption spectrum locates 447nm (blue light), 532nm (green light) and 565nm (yellow light), respectively. When stimulated by white light, excited degree of three kinds of cone cell are identical,or yellow-green light, to which person eye is most sensitive, will significantly takes effects. Therefore the yellow-green laser diode is suitable for treating amblyopia. The weak laser, namely laser power less than mW order of magnitude, shows curative by stimulating bion tissue. When stimulating light power density is less than 0.001W/cm, the compounding speed of nucleic acid DNA is significantly increased. The growth rate of cell, activity of enzyme, content of hemoglobin and the growth of blood vessel, are all increased. However, it's key to control the dose of light. When the dose transcend some value, a inhibition will occur. The little dose of weak laser treatment can be accumulated with a parabolic characteristics, that is the weak laser generate bion response stengthening gradually versus time. Then it will weaken gradually after the peak. When the treatment duration is longer than a certain time, a inhibition also takes place. A suggested theraphy is characterized by little dose and short treatment course. In a conclusion, the yellow-green laser diode should be used for the treatment of amblyopia. The little dose and short treatment couse are to be adopted. Key words:treatment amblyopia laser diode

Treating Mucocele in Pediatric Patients Using a Diode Laser: Three Case Reports.

PubMed

Bagher, Sara M; Sulimany, Ayman M; Kaplan, Martin; Loo, Cheen Y

2018-05-09

A mucocele is the most common minor salivary gland disease and among the most common biopsied oral lesions in pediatric patients. Clinically, a mucocele appears as a round well-circumscribed painless swelling ranging from deep blue to mucosa alike in color. Mucoceles rarely resolve on their own and surgical removal under local anesthesia is required in most cases. Different treatment options are described in the literature, including cryosurgery, intra-lesion injection of corticosteroid, micro-marsupialization and conventional surgical removal using a scalpel, and laser ablation. Therefore, the goal of this paper was to report three cases of mucocele removal in pediatric patients using a diode laser with a one-month follow-up. Mucoceles were removed by a pediatric dentist using a diode laser with a wavelength of 930 nm in continuous mode and a power setting of 1.8 Watts. In all cases, no bleeding occurred during or after the procedure and there was no need for suturing. On clinical examination during the one-month follow-up, in all three cases there was minimal or no scarring, minimal post-operative discomfort or pain, and no recurrence. Diode lasers provide an effective, rapid, simple, bloodless and well accepted procedure for treating mucocele in pediatric patients. Minimal post-operative discomfort and scarring was reported by all the three patients.

Comparison of the photothermal effects of 808nm gold nanorod and indocyanine green solutions using an 805nm diode laser

NASA Astrophysics Data System (ADS)

Hasanjee, Aamr M.; Zhou, Feifan; West, Connor; Silk, Kegan; Doughty, Austin; Bahavar, Cody F.; Chen, Wei R.

2016-03-01

Non-invasive laser immunotherapy (NLIT) is a treatment method for metastatic cancer which combines noninvasive laser irradiation with immunologically modified nanostructures to ablate a primary tumor and induce a systemic anti-tumor response. To further expand the development of NLIT, two different photosensitizing agents were compared: gold nanorods (GNR) with an optical absorption peak of 808 nm and indocyanine green (ICG) with an optical absorption peak of ~800 nm. Various concentrations of GNR and ICG solutions were irradiated at different power densities using an 805 nm diode laser, and the temperature of the solutions was monitored during irradiation using a thermal camera. For comparison, dye balls made up of a 1:1 volume ratio of gel solution to GNR or ICG solution were placed in phantom gels and were then irradiated using the 805 nm diode laser to imitate the effect of laser irradiation on in vivo tumors. Non-invasive laser irradiation of GNR solution for 2 minutes resulted in a maximum increase in temperature by 31.8 °C. Additionally, similar irradiation of GNR solution dye ball within phantom gel for 10 minutes resulted in a maximum temperature increase of 8.2 °C. Comparatively, non-invasive laser irradiation of ICG solution for 2 minutes resulted in a maximum increase in temperature by 28.0 °C. Similar irradiation of ICG solution dye ball within phantom gel for 10 minutes yielded a maximum temperature increase of only 3.4 °C. Qualitatively, these studies showed that GNR solutions are more effective photosensitizing agents than ICG solution.

Laser welding in penetrating keratoplasty and cataract surgery of pediatric patients: early results

NASA Astrophysics Data System (ADS)

Rossi, Francesca; Pini, Roberto; Menabuoni, Luca; Malandrini, Alex; Canovetti, Annalisa; Lenzetti, Ivo; Capozzi, Paolo; Valente, Paola; Buzzonetti, Luca

2013-03-01

Diode laser welding of ocular tissues is a procedure that enables minimally invasive closure of a corneal wound. This procedure is based on a photothermal effect: a water solution of Indocyanine Green (ICG) is inserted in the surgical wound, in order to stain the corneal tissue walls. The stained tissue is then irradiated with a low power infrared diode laser, delivering laser light through a 300-μm core diameter optical fiber. This procedure enables an immediate closure of the wounds: it is thus possible to reduce or to substitute the use of surgical threads. This is of particular interest in children, because the immediate closure improves refractive outcome and anti-amblyopic effect; moreover this procedure avoids several general anaesthesia for suture management. In this work, we present the first use of diode laser welding procedure in paediatric patients. 5 selected patients underwent cataract surgery (Group 1), while 4 underwent fs-laserassisted penetrating keratoplasty (Group 2). In Group 1 the conventional surgery procedure was performed, while no stitches were used for the closure of the surgical wounds: these were laser welded and immediately closed. In Group 2 the donor button was sutured upon the recipient by 8 single stitches, instead of 16 single stitches or a running suture. The laser welding procedure was performed in order to join the donor tissue to the recipient bed. Objective observations in the follow up study evidenced a perfect adhesion of the laser welded tissues, no collateral effects and an optimal restoration of the treated tissues.

AlGaInN laser diode technology and systems for defence and security applications

NASA Astrophysics Data System (ADS)

Najda, Stephen P.; Perlin, Piotr; Suski, Tadek; Marona, Lujca; Boćkowski, Mike; Leszczyński, Mike; Wisniewski, Przemek; Czernecki, Robert; Kucharski, Robert; Targowski, Grzegorz; Watson, Scott; Kelly, Antony E.

2015-10-01

AlGaInN laser diodes is an emerging technology for defence and security applications such as underwater communications and sensing, atomic clocks and quantum information. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well. Thus AlGaInN laser diode technology is a key enabler for the development of new disruptive system level applications in displays, telecom, defence and other industries. Ridge waveguide laser diodes are fabricated to achieve single mode operation with optical powers up to 100mW with the 400-440nm wavelength range with high reliability. Visible free-space and underwater communication at frequencies up to 2.5GHz is reported using a directly modulated 422nm GaN laser diode. Low defectivity and highly uniform GaN substrates allow arrays and bars to be fabricated. High power operation operation of AlGaInN laser bars with up to 20 emitters have been demonstrated at optical powers up to 4W in a CS package with common contact configuration. An alternative package configuration for AlGaInN laser arrays allows for each individual laser to be individually addressable allowing complex free-space or optical fibre system integration with a very small form-factor.

Hysteroscopic metroplasty for the septate uterus with diode laser: a pilot study.

PubMed

Nappi, Luigi; Pontis, Alessandro; Sorrentino, Felice; Greco, Pantaleo; Angioni, Stefano

2016-11-01

To evaluate the feasibility and safety of office hysteroscopic metroplasty using a 980nm diode laser. 18 patients were treated for septate uterus between 2013 and 2016. The indications for hysteroscopic metroplasty were recurrent abortion in 11 of the women and primary infertility in the other seven. We used a 5mm-office hysteroscope with a diode laser fibre. After exploration of the cavity, the septum was divided with use of the laser fibre. Operating time was 13,16±1,33min. Intraoperative pain was 3,05±0,72. No intraoperative or postoperative complications were observed. Follow-up performed 2 months after the hysteroscopic metroplasty confirmed the complete removal of the septum and no evidence of intrauterine synechiae. Office hysteroscopic metroplasty with use of a diode laser is safe and feasible; we believe that vaporization of the septum with a diode laser could reduce the formation of adhesions and consequently reduce the occurrence of septum persistence. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

100W high-brightness multi-emitter laser pump

NASA Astrophysics Data System (ADS)

Duesterberg, Richard; Xu, Lei; Skidmore, Jay A.; Guo, James; Cheng, Jane; Du, Jihua; Johnson, Brad; Vecht, David L.; Guerin, Nicolas; Huang, Benlih; Yin, Dongliang; Cheng, Peter; Raju, Reddy; Lee, Kong Weng; Cai, Jason; Rossin, Victor; Zucker, Erik P.

2011-03-01

We report results of a spatially-multiplexed broad area laser diode platform designed for efficient pumping of fiber lasers or direct-diode systems. Optical output power in excess of 100W from a 105μm core, 0.15NA fiber is demonstrated with high coupling efficiency. The compact form factor and low thermal resistance enable tight packing densities needed for kW-class fiber laser systems. Broad area laser diodes have been optimized to reduce near- and far-field performance and prevent blooming without sacrificing other electro-optic parameters. With proper lens optimization this produces ~5% increase in coupling / wall plug efficiency for our design. In addition to performance characteristics, an update on long term reliability testing of 9XX nm broad area laser diode is provided that continues to show no wear out under high acceleration. Under nominal operating conditions of 12W ex-facet power at 25C, the diode mean time to failure (MTTF) is forecast to be ~ 480 kh.

Cavity-Enhanced Raman Spectroscopy of Natural Gas with Optical Feedback cw-Diode Lasers.

PubMed

Hippler, Michael

2015-08-04

We report on improvements made on our previously introduced technique of cavity-enhanced Raman spectroscopy (CERS) with optical feedback cw-diode lasers in the gas phase, including a new mode-matching procedure which keeps the laser in resonance with the optical cavity without inducing long-term frequency shifts of the laser, and using a new CCD camera with improved noise performance. With 10 mW of 636.2 nm diode laser excitation and 30 s integration time, cavity enhancement achieves noise-equivalent detection limits below 1 mbar at 1 bar total pressure, depending on Raman cross sections. Detection limits can be easily improved using higher power diodes. We further demonstrate a relevant analytical application of CERS, the multicomponent analysis of natural gas samples. Several spectroscopic features have been identified and characterized. CERS with low power diode lasers is suitable for online monitoring of natural gas mixtures with sensitivity and spectroscopic selectivity, including monitoring H2, H2S, N2, CO2, and alkanes.

A comparison of the antibacterial activity of the two methods of photodynamic therapy (using diode laser 810 nm and LED lamp 630 nm) against Enterococcus faecalis in extracted human anterior teeth.

PubMed

Asnaashari, Mohammad; Mojahedi, Seyed Masoud; Asadi, Zahra; Azari-Marhabi, Saranaz; Maleki, Alireza

2016-03-01

Failure of endodontic treatment is usually due to an inadequate disinfection of the root canal system. Enterococcus faecalis has been widely used as a valuable microbiological marker for in-vitro studies because of its ability to colonize in a biofilm like style in root canals, invading dentinal tubules and resistance to some endodontic treatments. The aim of this study was to investigate the antibacterial effects of two methods of photodynamic therapy using a light emitting diode lamp (LED lamp, 630 nm) and a diode laser (810 nm) on E. faecalis biofilms in anterior extracted human teeth. Fifty six single-rooted extracted teeth were used in this study. After routine root canal cleansing, shaping and sterilization, the teeth were incubated with E. faecalis for a period of two weeks. Teeth were then divided into two experimental groups (nu=23) and two control groups (nu=5). Teeth in one experimental group were exposed to a diode laser (810 nm), and in the other group samples were exposed to a LED lamp (630 nm). Intracanal bacterial sampling was done, and bacterial survival rate was then evaluated for each group. The Colony Forming Unit (CFU) in LED group (log10 CFUs=4.88±0.82) was significantly lower than the laser group (log CFUs=5.49±0.71) (p value=0.021). CFUs in positive control group (Log10 CFUs=10.96±0.44) were significantly higher than the treatment group (p˂0.001). No bacterial colony was found in negative control group. The results of this research show that photodynamic therapy could be an effective supplement in root canal disinfection. PDT using LED lamp was more effective than diode laser 810 nm in reducing CFUs of E. faecalis in human teeth. Copyright © 2015 Elsevier B.V. All rights reserved.

Dynamic response of a fiber-optic ring resonator: Analysis with influences of light-source parameters

NASA Astrophysics Data System (ADS)

Seraji, Faramarz E.

2009-03-01

In practice, dynamic behavior of fiber-optic ring resonator (FORR) appears as a detrimental factor to influence the transmission response of the FORR. This paper presents dynamic response analysis of the FORR by considering phase modulation of the FORR loop and sinewave modulation of input signal applied to the FORR from a laser diode. The analysis investigates the influences of modulation frequency and amplitude modulation index of laser diode, loop delay time of the FORR, phase angle between FM and AM response of laser diode, and laser diode line-width on dynamic response of the FORR. The analysis shows that the transient response of the FORR strongly depends on the product of modulation frequency and loop delay time, coupling and transmission coefficients of the FORR. The analyses presented here may have applications in optical systems employing an FORR with a laser diode source.

The method of pulsed x-ray detection with a diode laser.

PubMed

Liu, Jun; Ouyang, Xiaoping; Zhang, Zhongbing; Sheng, Liang; Chen, Liang; Tan, Xinjian; Weng, Xiufeng

2016-12-01

A new class of pulsed X-ray detection methods by sensing carrier changes in a diode laser cavity has been presented and demonstrated. The proof-of-principle experiments on detecting pulsed X-ray temporal profile have been done through the diode laser with a multiple quantum well active layer. The result shows that our method can achieve the aim of detecting the temporal profile of a pulsed X-ray source. We predict that there is a minimum value for the pre-bias current of the diode laser by analyzing the carrier rate equation, which exists near the threshold current of the diode laser chip in experiments. This behaviour generally agrees with the characterizations of theoretical analysis. The relative sensitivity is estimated at about 3.3 × 10 -17 C ⋅ cm 2 . We have analyzed the time scale of about 10 ps response with both rate equation and Monte Carlo methods.

Closure of skin incisions by laser-welding with a combination of two near-infrared diode lasers: preliminary study for determination of optimal parameters

NASA Astrophysics Data System (ADS)

Hu, Liming; Lu, Zhihua; Wang, Biao; Cao, Junsheng; Ma, Xiaobo; Tian, Zhenhua; Gao, Zhijian; Qin, Li; Wu, Xiaodong; Liu, Yun; Wang, Lijun

2011-03-01

Laser welding has the potential to become an effective method for wound closure and healing without sutures. Closure of skin incisions by laser welding with a combination of two near-infrared lasers (980 and 1064 nm), was performed for the first time in this study. One centimeter long, full-thickness incisions were made on the Wistar rat's dorsal skin. The efficiencies of laser-welding with different parameters were investigated. Incision-healing, histology examination, and a tensile strength test of incisions were recorded. Laser welding with the irradiance level of 15.9 W/cm2 for both 980 and 1064-nm lasers and exposure time of 5 s per spot in continuous wave mode yielded a more effective closure and healing with minimal thermal damage, faster recovery, and stronger apposition in comparison with a suturing technique. The conclusion is that skin welding with a combination of two near-infrared diode lasers can be a good candidate for incision closure, and further investigations are in progress for clinical use.

Closure of skin incisions by laser-welding with a combination of two near-infrared diode lasers: preliminary study for determination of optimal parameters.

PubMed

Hu, Liming; Lu, Zhihua; Wang, Biao; Cao, Junsheng; Ma, Xiaobo; Tian, Zhenhua; Gao, Zhijian; Qin, Li; Wu, Xiaodong; Liu, Yun; Wang, Lijun

2011-03-01

Laser welding has the potential to become an effective method for wound closure and healing without sutures. Closure of skin incisions by laser welding with a combination of two near-infrared lasers (980 and 1064 nm), was performed for the first time in this study. One centimeter long, full-thickness incisions were made on the Wistar rat's dorsal skin. The efficiencies of laser-welding with different parameters were investigated. Incision-healing, histology examination, and a tensile strength test of incisions were recorded. Laser welding with the irradiance level of 15.9 W∕cm(2) for both 980 and 1064-nm lasers and exposure time of 5 s per spot in continuous wave mode yielded a more effective closure and healing with minimal thermal damage, faster recovery, and stronger apposition in comparison with a suturing technique. The conclusion is that skin welding with a combination of two near-infrared diode lasers can be a good candidate for incision closure, and further investigations are in progress for clinical use.

Effects of laser-aided circumferential supracrestal fiberotomy on root surfaces.

PubMed

Lee, Ji-Won; Park, Ki-Ho; Chung, Jong-Hyuk; Kim, Su-Jung

2011-11-01

To evaluate and compare the effects of circumferential supracrestal fiberotomy in vivo (using diode, CO(2), and Er∶YAG lasers) on the morphology and chemical composition of the root surface. Forty healthy premolar teeth, intended for extraction for orthodontic reasons, were used in this study. Root surfaces were treated using different laser methods, as follows: (1) control; (2) Er∶YAG laser (2.94 µm, 100 mJ, 10 Hz); (3) diode laser (808 nm, 1.2 W, continuous wave); and (4) CO(2) laser (10.6 µm, 3 W, continuous wave). Subsequently, the teeth were removed and subjected to scanning electron microscopic (SEM) examination and energy dispersive x-ray (EDX) spectrometric analysis. SEM analysis indicated that no thermal changes, including melting or carbonization, were observed following the lasing procedures. EDX analysis showed that the laser procedures resulted in similar mineral contents (weight % of calcium and phosphate) as compared to those in the control group. Based on these findings, we concluded that laser-aided procedures, when used at appropriate laser settings, preserve the original morphology and chemical composition of cementum.

Laser antisepsis of Phorphyromonas gingivalis in vitro with dental lasers

NASA Astrophysics Data System (ADS)

Harris, David M.

2004-05-01

It has been shown that both pulsed Nd:YAG (1064nm) and continuous diode (810nm) dental lasers kill pathogenic bacteria (laser antisepsis), but a quantitative method for determining clinical dosimetry does not exist. The purpose of this study was to develop a method to quantify the efficacy of ablation of Porphyromonas gingivalis (Pg) in vitro for two different lasers. The ablation thresholds for the two lasers were compared in the following manner. The energy density was measured as a function of distance from the output of the fiber-optic delivery system. Pg cultures were grown on blood agar plates under standard anaerobic conditions. Blood agar provides an approximation of gingival tissue for the wavelengths tested in having hemoglobin as a primary absorber. Single pulses (Nd:YAG: 100- Œs diode: 100-msec) of laser energy were delivered to Pg colonies and the energy density was increased until the appearance of a small plume was observed coincident with a laser pulse. The energy density at this point defines the ablation threshold. Ablation thresholds to a single pulse were determined for both Pg and for blood agar alone. The large difference in ablation thresholds between the pigmented pathogen and the host matrix for pulsed-Nd:YAG represented a significant therapeutic ratio and Pg was ablated without visible effect on the blood agar. Near threshold the 810-nm diode laser destroyed both the pathogen and the gel. Clinically, the pulsed Nd:YAG may selectively destroy pigmented pathogens leaving the surrounding tissue intact. The 810-nm diode laser may not demonstrate this selectivity due to its longer pulse length and greater absorption by hemoglobin.

Study of phase-locked diode laser array and DFB/DBR surface emitting laser diode

NASA Astrophysics Data System (ADS)

Hsin, Wei

New types of phased-array and surface-emitting lasers are designed. The importance and approaches (or structures) of different phased array and surface emitting laser diodes are reviewed. The following are described: (1) a large optical cavity channel substrate planar laser array with layer thickness chirping; (2) a vertical cavity surface emitter with distributed feedback (DFB) optical cavity and a transverse junction buried heterostructure; (3) a microcavity distributed Bragg reflector (DBR) surface emitter; and (4) two surface emitting laser structures which utilized lateral current injection schemes to overcome the problems occurring in the vertical injection scheme.

The Versatility of 980 nm Diode Laser in Dentistry: A Case Series

PubMed Central

Derikvand, Nahid; Chinipardaz, Zahra; Ghasemi, Sara; Chiniforush, Nasim

2016-01-01

Introduction: Laser surgery has been considered a popular alternative over conventional modalities in dentistry during the last few years. Among different types of lasers, diode lasers have gained special attention in oral soft tissue surgery. Case Reports: Five patients were referred to a private office. After careful evaluation of medical history and oral examination, oral diagnosis and treatment plan of each patient was established as follows: (1) A 21-year-old female with ankyloglossia (tongue-tie); (2) A 65-year-old female with a poor denture fit needing vestibuloplasty and frenectomy; (3) A 10-year-old male patient with pigmented gingiva in mandible and maxilla; (4) A 14-year-old female needing exposure of maxillary right canine for bracket bonding; and (5) A 25-year-old female patient who has a gingival maxillary frenum with a nodule. The treatment plan for all the patients was laser surgery with diode laser at 980 nm, in continuous mode. Results: All the patients experienced normal healing process with no postoperative complications. Favorable outcomes of laser surgery were observed on follow-up sessions. Conclusion: Considering the versatility of the 980 nm diode laser in oral soft tissue surgeries and the advantages of laser surgery, this study suggests the use of 980 nm diode laser in this regard. PMID:28144444

The Versatility of 980 nm Diode Laser in Dentistry: A Case Series.

PubMed

Derikvand, Nahid; Chinipardaz, Zahra; Ghasemi, Sara; Chiniforush, Nasim

2016-01-01

Introduction: Laser surgery has been considered a popular alternative over conventional modalities in dentistry during the last few years. Among different types of lasers, diode lasers have gained special attention in oral soft tissue surgery. Case Reports: Five patients were referred to a private office. After careful evaluation of medical history and oral examination, oral diagnosis and treatment plan of each patient was established as follows: (1) A 21-year-old female with ankyloglossia (tongue-tie); (2) A 65-year-old female with a poor denture fit needing vestibuloplasty and frenectomy; (3) A 10-year-old male patient with pigmented gingiva in mandible and maxilla; (4) A 14-year-old female needing exposure of maxillary right canine for bracket bonding; and (5) A 25-year-old female patient who has a gingival maxillary frenum with a nodule. The treatment plan for all the patients was laser surgery with diode laser at 980 nm, in continuous mode. Results: All the patients experienced normal healing process with no postoperative complications. Favorable outcomes of laser surgery were observed on follow-up sessions. Conclusion: Considering the versatility of the 980 nm diode laser in oral soft tissue surgeries and the advantages of laser surgery, this study suggests the use of 980 nm diode laser in this regard.

Thermal investigation on high power dfb broad area lasers at 975 nm, with 60% efficiency

NASA Astrophysics Data System (ADS)

Mostallino, R.; Garcia, M.; Deshayes, Y.; Larrue, A.; Robert, Y.; Vinet, E.; Bechou, L.; Lecomte, M.; Parillaud, O.; Krakowski, M.

2016-03-01

The demand of high power diode lasers in the range of 910-980nm is regularly growing. This kind of device for many applications, such as fiber laser pumping [1], material processing [1], solid-state laser pumping [1], defense and medical/dental. The key role of this device lies in the efficiency (𝜂𝐸) of converting input electrical power into output optical power. The high value of 𝜂𝐸 allows high power level and reduces the need in heat dissipation. The requirement of wavelength stabilization with temperature is more obvious in the case of multimode 975nm diode lasers used for pumping Yb, Er and Yb/Er co-doped solid-state lasers, due to the narrow absorption line close to this wavelength. Such spectral width property (<1 nm), combined with wavelength thermal stabilization (0.07 𝑛𝑚 • °𝐶-1), provided by a uniform distributed feedback grating (DFB) introduced by etching and re-growth process techniques, is achievable in high power diode lasers using optical feedback. This paper reports on the development of the diode laser structure and the process techniques required to write the gratings taking into account of the thermal dissipation and optical performances. Performances are particularly determined in terms of experimental electro-optical characterizations. One of the main objectives is to determine the thermal resistance of the complete assembly to ensure the mastering of the diode laser temperature for operating condition. The classical approach to determine junction temperature is based on the infrared thermal camera, the spectral measurement and the pulse electrical method. In our case, we base our measurement on the spectral measurement but this approach is not well adapted to the high power diodes laser studied. We develop a new measurement based on the pulse electrical method and using the T3STERequipment. This method is well known for electronic devices and LEDs but is weakly developed for the high power diodes laser. This crucial measurement compared to spectral one is critical for understand the thermal management of diode laser device and improve the structure based on design for reliability. To have a perfect relation between structure, and their modification, and temperature, FEM simulations are performed using COMSOL software. In this case, we can understand the impact of structure on the isothermal distribution and then reveal the sensitive zones in the diode laser. To validate the simulation, we compare the simulation results to the experimental one and develop an analytical model to determine the different contributions of the thermal heating. This paper reports on the development laser structure and the process techniques required to write the gratings. Performances are particularly characterized in terms of experimental electro-optical characterization and spectral response. The extraction of thermal resistance (Rth) is particularly difficult, because of the implicit low value (Rth ≈ 2𝐾/𝑊) and the multimodal nature of the diode laser. In such a context, thermal resistance has been measured using a dedicated equipment namely T3STER©. The results have been compared with those given by the well-known technique achieved from the spectrum of the diode laser (central wavelength variations vs temperature) that is more difficult to apply for multimodal diodes laser. The last section deals with thermal simulations based on finite elements method (FEM) modeling in order to estimate junction temperature . This study represent a significant part of the general Design for Reliability (DfR) effort carried out on such devices to produce efficient and reliable high power devices at the industrial level.

Highly reliable high-power AlGaAs/GaAs 808 nm diode laser bars

NASA Astrophysics Data System (ADS)

Hülsewede, R.; Schulze, H.; Sebastian, J.; Schröder, D.; Meusel, J.; Hennig, P.

2007-02-01

There are strong demands at the market to increase power and reliability for 808 nm diode laser bars. Responding to this JENOPTIK Diode Lab GmbH developed high performance 808 nm diode laser bars in the AlGaAs/GaAs material system with special emphasis to high power operation and long term stability. Optimization of the epitaxy structure and improvements in the diode laser bar design results in very high slope efficiency of >1.2 W/A, low threshold current and small beam divergence in slow axis direction. Including low serial resistance the overall wall plug efficiency is up to 65% for our 20%, 30% and 50% filling factor 10 mm diode laser bars. With the JENOPTIK Diode Lab cleaving and coating technique the maximum output power is 205 W in CW operation and 377 W in QCW operation (200 μs, 2% duty cycle) for bars with 50% filling factor. These bars mounted on micro channel cooled package are showing a very high reliability of >15.000 h. Mounted on conductive cooled package high power operation at 100 W is demonstrated for more than 5000h.

Low absorption loss p-AlGaN superlattice cladding layer for current-injection deep ultraviolet laser diodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martens, M.; Kuhn, C.; Ziffer, E.

2016-04-11

Current injection into AlGaN-based laser diode structures with high aluminum mole fractions for deep ultraviolet emission is investigated. The electrical characteristics of laser diode structures with different p-AlGaN short period superlattice (SPSL) cladding layers with various aluminum mole fractions are compared. The heterostructures contain all elements that are needed for a current-injection laser diode including cladding and waveguide layers as well as an AlGaN quantum well active region emitting near 270 nm. We found that with increasing aluminum content in the p-AlGaN cladding, the diode turn-on voltage increases, while the series resistance slightly decreases. By introducing an SPSL instead of bulkmore » layers, the operating voltage is significantly reduced. A gain guided broad area laser diode structure with transparent p-Al{sub 0.70}Ga{sub 0.30}N waveguide layers and a transparent p-cladding with an average aluminum content of 81% was designed for strong confinement of the transverse optical mode and low optical losses. Using an optimized SPSL, this diode could sustain current densities of more than 4.5 kA/cm{sup 2}.« less

Design of a quasi-CW laser diode driver for space-based laser transmitter

NASA Astrophysics Data System (ADS)

Singh, Ravindra; Dangwal, Nishma; Chandraprakash, .; Agrawal, Lalita; Pal, Suranjan; Kamlakar, J. A.

2006-12-01

LASTEC Delhi in a joint collaborative activity with LEOS, Bangalore is developing a space qualified diode array pumped Nd:YAG laser transmitter delivering 30 mJ @ 10 pps of 10 ns duration. For space applications laser diodes are preferred because of their excellent reliability with lifetimes exceeding 100,000 hours. However, they are extremely sensitive to electro-static discharge, excessive current levels, and current spikes and transients. Small variations in bias voltage may produce large fluctuations in the current causing instability and damage to the device. Hence instead of the traditional power supplies a current controlled laser diode driver is required. This paper presents the design of a Q-CW laser diode driver based on closed loop current regulator, capable of driving 24 QCW laser diode bars each with 75W peak power at 70 A. The driver can generate up to 100 Amp peak current and 200μsec pulse width operating at 10 Hz. The current source design includes special circuits for low noise operation, slow turn-on and turn-off, circuits for over voltage and transient current protection; and good regulation. Space qualified and radiation hardened components are required to be used to sustain stringent space environment requirements during mission life of two years.

Hole transport in c-plane InGaN-based green laser diodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Yang; Liu, Jianping, E-mail: jpliu2010@sinano.ac.cn; Tian, Aiqin

2016-08-29

Hole transport in c-plane InGaN-based green laser diodes (LDs) has been investigated by both simulations and experiments. It is found that holes can overflow from the green double quantum wells (DQWs) at high current density, which reduces carrier injection efficiency of c-plane InGaN-based green LDs. A heavily silicon-doped layer right below the green DQWs can effectively suppress hole overflow from the green DQWs.

Transient behavior of an actively mode-locked semiconductor laser diode

NASA Technical Reports Server (NTRS)

Auyeung, J. C.; Bergman, L. A.; Johnston, A. R.

1982-01-01

Experimental investigation was carried out to study the transient regimes during the buildup and decay of the active mode-locked state in a laser diode. The mode locking was achieved through a sinusoidal modulation of the diode current with the laser in an external cavity. The pulse shape evolution and the time constants for the buildup and decay were determined.

Optical signal inverter of erbium-doped yttrium aluminum garnet with red shift of laser diodes.

PubMed

Maeda, Y

1994-08-10

An optical signal inverter was demonstrated in a simple structure that combined a laser diode with Er-doped YAG crystal. The optical signal inversion occurred at a response time of 7 ns and was caused by the decrease of transmission of Er:YAG against the red shift of the wavelength of the laser diode.

Diode laser spectroscopy: precise spectral line shape measurements

NASA Astrophysics Data System (ADS)

Nadezhdinskii, A. I.

1996-07-01

When one speaks about modern trends in tunable diode laser spectroscopy (TDLS) one should mention that precise line shape measurements have become one of the most promising applications of diode lasers in high resolution molecular spectroscopy. Accuracy limitations of TDL spectrometers are considered in this paper, proving the ability to measure spectral line profile with precision better than 1%. A four parameter Voigt profile is used to fit the experimental spectrum, and the possibility of line shift measurements with an accuracy of 2 × 10 -5 cm -1 is shown. Test experiments demonstrate the error line intensity ratios to be less than 0.3% for the proposed approach. Differences between "soft" and "hard" models of line shape have been observed experimentally for the first time. Some observed resonance effects are considered with respect to collision adiabacity.

Detection of gaseous oxygen using temperature tuned laser diodes

NASA Technical Reports Server (NTRS)

Fox, Curtis W.; Disimile, Peter J.

1990-01-01

The development of an optical differential absorption technique using laser diodes is discussed. The technique is being developed as a solution to overcome the difficulties imposed by conventional liquid rocket propulsion system leak detection such as damage to the engine, cumbersome equipment, and excessive amounts of time. The detection of O2 at atmospheric pressure and temperature using laser diodes is demonstrated. Also, it is shown that, by temperature tuning the laser diode, the wavelength was shifted to a level where the oxygen absorption peaks are found. The levels of transmission determined via experimental means and those calculated from spectral data are found to be in close agreement.

Quantitative Detection of Combustion Species using Ultra-Violet Diode Lasers

NASA Technical Reports Server (NTRS)

Pilgrim, J. S.; Peterson, K. A.

2001-01-01

Southwest Sciences is developing a new microgravity combustion diagnostic based on UV diode lasers. The instrument will allow absolute concentration measurements of combustion species on a variety of microgravity combustion platforms including the Space Station. Our approach uses newly available room temperature UV diode lasers, thereby keeping the instrument compact, rugged and energy efficient. The feasibility of the technique was demonstrated by measurement of CH radicals in laboratory flames. Further progress in fabrication technology of UV diode lasers at shorter wavelengths and higher power will result in detection of transient species in the deeper UV. High sensitivity detection of combustion radicals is provided with wavelength modulation absorption spectroscopy.

Research at Lincoln Laboratory leading up to the development of the injection laser in 1962

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rediker, R.H.

1987-06-01

In 1958 the semiconductor device group at Lincoln Laboratory began to concentrate its efforts on exploiting GaAs. These efforts, in addition to yielding diodes with ns switching speeds, led to the development in early 1962 of diodes which emitted near-bandgap radiation with very high efficiency, and to the development in October 1962 of the diode laser. The theory of the semiconductor laser developed at Lincoln Laboratory in the mid-to-late 1950's provided the foundation necessary for the design of the diode laser structure after the highly efficient production of near-bandgap radiation was demonstrated.

Research at Lincoln Laboratory leading up to the development of the injection laser in 1962

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rediker, R.H.

1987-06-01

In 1958 the Semiconductor Device Group at Lincoln Laboratory began to concentrate its efforts on exploiting GaAs. these efforts, in addition to yielding diodes which ns switching speeds, led to the development in early 1962 of diodes that emitted near-bandgap radiation with very high efficiency, and to the development in October 1962 of the diode laser. The theory of the semiconductor laser developed at Lincoln Laboratory in the mid-to-late 1950's provided the foundation necessary for the design of the diode laser structure after the highly efficient production of near-bandgap radiation was demonstrated.

2000W high beam quality diode laser for direct materials processing

NASA Astrophysics Data System (ADS)

Qin, Wen-bin; Liu, You-qiang; Cao, Yin-hua; Gao, Jing; Pan, Fei; Wang, Zhi-yong

2011-11-01

This article describes high beam quality and kilowatt-class diode laser system for direct materials processing, using optical design software ZEMAX® to simulate the diode laser optical path, including the beam shaping, collimation, coupling, focus, etc.. In the experiment, the diode laser stack of 808nm and the diode laser stack of 915nm were used for the wavelength coupling, which were built vertical stacks up to 16 bars. The threshold current of the stack is 6.4A, the operating current is 85A and the output power is 1280W. Through experiments, after collimating the diode laser beam with micro-lenses, the fast axis BPP of the stack is less than 60mm.mrad, and the slow-axis BPP of the stack is less than 75mm.mrad. After shaping the laser beam and improving the beam quality, the fast axis BPP of the stack is still 60mm.mrad, and the slow-axis BPP of the stack is less than 19mm.mrad. After wavelength coupling and focusing, ultimately the power of 2150W was obtained, focal spot size of 1.5mm * 1.2mm with focal length 300mm. The laser power density is 1.2×105W/cm2, and that can be used for metal remelting, alloying, cladding and welding. The total optical coupling conversion efficiency is 84%, and the total electrical - optical conversion efficiency is 50%.

Development of laser diode otolaryngological intracavity procedures and its clinical practice

NASA Astrophysics Data System (ADS)

Wang, Qingguo; Mao, Haitao; Bu, Hongjian; Dong, Xingfa; Li, Jikai; Li, Fangzheng; Zhang, Wenqing

1998-08-01

Because laser is diffusely reflected by the skin as well as scattered and absorbed by the subcutaneous tissue, the lasing intensity which enters into the tissue through the skin is exponentially attenuated with the increase in the depth. Therefore, when the medium-small energy laser is transmitted to the tissue depth through the skin, the lasing intensity is quite finite. However, a lot of diseases occur in the crooked and narrow tube, sinus or deep tissue, for these diseases, it is difficult to get the curative effect by normal laser radiation. As above, we have developed an otolaryngological intracavity therapeutic apparatus of laser diode. Visible GaAlAs laser diode is adopted on this apparatus, its lasing wavelength is 670 nm. The lasing beam is guided into the crooked and narrow tube, sinus or deep tissue, which passes through the optical fiber and the laser pins of different forms and sizes (such as straight, curved and sidelight etc.). Using the fiber-optic connector the laser pins can be changed conveniently. The lasing output power of laser pin can be adjusted from 0 to 20 mW. The lasing intensity may be modulated which changes the rectangular wave form 0 to 1 kHz. Five hundred patients were suffering from 35 kind of otolaryngological diseases were treated in the period of clinical test. The rate of efficiency (cure or improvement) is 89%. Nobody had the side effect or deteriorated. This apparatus has the best curative effect on the inflammation of the mucosa and shallow tissue, such as auris media dropsy, maxillary sinus inflammation, auris external inflammation, chronic laryngitis, otitis media, tinnitus, vertigo, and so on.

Stabilized diode seed laser for flight and space-based remote lidar sensing applications

NASA Astrophysics Data System (ADS)

McNeil, Shirley; Pandit, Pushkar; Battle, Philip; Rudd, Joe; Hovis, Floyd

2017-08-01

AdvR, through support of the NASA SBIR program, has developed fiber-based components and sub-systems that are routinely used on NASA's airborne missions, and is now developing an environmentally hardened, diode-based, locked wavelength, seed laser for future space-based high spectral resolution lidar applications. The seed laser source utilizes a fiber-coupled diode laser, a fiber-coupled, calibrated iodine reference module to provide an absolute wavelength reference, and an integrated, dual-element, nonlinear optical waveguide component for second harmonic generation, spectral formatting and wavelength locking. The diode laser operates over a range close to 1064.5 nm, provides for stabilization of the seed to the desired iodine transition and allows for a highly-efficient, fully-integrated seed source that is well-suited for use in airborne and space-based environments. A summary of component level environmental testing and spectral purity measurements with a seeded Nd:YAG laser will be presented. A direct-diode, wavelength-locked seed laser will reduce the overall size weight and power (SWaP) requirements of the laser transmitter, thus directly addressing the need for developing compact, efficient, lidar component technologies for use in airborne and space-based environments.

Low-Cost, Single-Frequency Sources for Spectroscopy using Conventional Fabry-Perot Diode Lasers

NASA Technical Reports Server (NTRS)

Duerksen, Gary L.; Krainak, Michael A.

1999-01-01

Commercial (uncoated) Fabry-Perot laser diodes are converted to single-frequency spectroscopy sources by passively locking the laser frequency to the band edge of a fiber Bragg grating, which phase-locks the laser oscillations through self-injection seeding.

Low-Cost, Single-Frequency Sources for Spectroscopy Using Conventional Fabry-Perot Diode Lasers

NASA Technical Reports Server (NTRS)

Krainak, Michael A.; Duerksen, Gary L.

1999-01-01

Commercial (uncoated) Fabry-Perot laser diodes are converted to single-frequency spectroscopy sources by passively locking the laser frequency to the band edge of a fiber Bragg grating, which phase-locks the laser oscillations through self-injection seeding.

Diode Lasers and Practical Trace Analysis.

ERIC Educational Resources Information Center

Imasaka, Totaro; Nobuhiko, Ishibashi

1990-01-01

Applications of lasers to molecular absorption spectrometry, molecular fluorescence spectrometry, visible semiconductor fluorometry, atomic absorption spectrometry, and atomic fluorescence spectrometry are discussed. Details of the use of the frequency-doubled diode laser are provided. (CW)

High-resolution investigation of longitudinal modes of a GaN-based blue laser diode

NASA Astrophysics Data System (ADS)

Al-Basheer, Watheq; Aljalal, Abdulaziz; Gasmi, Khaled; Adigun, Taofeek O.

2017-05-01

Typical emission spectra of GaN-based blue laser diodes are known to have irregular shapes. Hence, well-resolved study of their spectra may help in understanding the origin of their spectral shapes irregularity. In this paper, the spectra of a commercial GaN-based blue laser diode are studied as a function of injection current and temperature using a spectrometer with highresolution of 0.003-nm over the spectral region 440 - 450 nm. The obtained laser spectra are used to track the longitudinal modes evolution as a function of operating currents and temperatures as well as to precisely map single mode operation. In addition, yielded laser spectra will be utilized to evaluate few parameters related to the laser diode, such as mode spacing, optical gain, slope efficiency and threshold current at certain temperature.

[Pilot study on the use of diode laser therapy for treatment of dermatitis in koi carp (Cyprinus carpio)].

PubMed

Pees, Michael; Schmidt, V; Pees, K

2011-01-01

Therapy of dermatitis in koi using a diode laser technique. A diode laser with a wavelength of 980 nm and an energy density of 9 J/cm(2) was used to treat defined skin alterations in ten koi carp. The clinical situation after repeated laser application was recorded. In addition, the diode laser was used for surgical removal of proliferative skin alterations caused by Dermocystidium sp. in two koi ponds. An improvement of the clinical situation following laser therapy was seen in nine of the ten koi carp. Complete healing of the wound area occurred in four carp. A pronounced healing process was observed in four patients and a low healing tendency in one fish. Healing of the skin lesions following removal of the alterations caused by Dermocystidium sp. was unproblematic in one pond, whereas in the other collection a repeated treatment was necessary due to relapse of the alterations. Diode laser therapy for treatment of dermatitis in koi is a promising technique. An expedited wound healing process was seen in wound areas that were present for long periods and resistant to previous therapy attempts, including antibiotics. Wound healing was undisturbed following surgical use of the laser technique for the removal of skin proliferations. Therefore, the diode laser technique can be recommended for the treatment of dermatitis in koi, especially in cases of unsuccessful treatment using anti-infective drugs, and for the treatment of Dermocystidium infections.

Human papilloma virus lesions of the oral cavity: healing and relapse after treatment with 810-980 nm diode laser.

PubMed

Angiero, Francesca; Buccianti, Alberto; Parma, Luisa; Crippa, Rolando

2015-02-01

This study evaluated the therapeutic efficacy of laser therapy in treating oral human papilloma virus (HPV) lesions. In particular, mode of action, healing, postoperative patient compliance, visual numeric scale (VNS) pain index, and recurrence were analyzed. During 2001-2012, in 170 patients (80 women and 90 men), 174 intraoral and lip HPV lesions were detected and excised by diode laser of different wavelengths (810-980 nm), with an average power of 2.1 W, in continuous wave mode, using 300 to 320 μm optical fibers. In most cases (95.4%), complete healing occurred in the first 30 days. There were no adverse effects and all patients were carefully followed up until complete healing occurred, documenting any complications. There was only one recurrence, which was later treated successfully; the mean VNS pain score was below one. In treating HPV lesions, the diode laser is not only a valuable tool for their eradication but especially it reduces relapses, thanks to the characteristics of the laser light.

New laser materials for laser diode pumping

NASA Technical Reports Server (NTRS)

Jenssen, H. P.

1990-01-01

The potential advantages of laser diode pumped solid state lasers are many with high overall efficiency being the most important. In order to realize these advantages, the solid state laser material needs to be optimized for diode laser pumping and for the particular application. In the case of the Nd laser, materials with a longer upper level radiative lifetime are desirable. This is because the laser diode is fundamentally a cw source, and to obtain high energy storage, a long integration time is necessary. Fluoride crystals are investigated as host materials for the Nd laser and also for IR laser transitions in other rare earths, such as the 2 micron Ho laser and the 3 micron Er laser. The approach is to investigate both known crystals, such as BaY2F8, as well as new crystals such as NaYF8. Emphasis is on the growth and spectroscopy of BaY2F8. These two efforts are parallel efforts. The growth effort is aimed at establishing conditions for obtaining large, high quality boules for laser samples. This requires numerous experimental growth runs; however, from these runs, samples suitable for spectroscopy become available.

Laser-assisted selective fusing of thermal sprayed Ni-based self-fluxing alloys by using high-power diode lasers

NASA Astrophysics Data System (ADS)

Chun, Eun-Joon; Kim, Min-Su; Nishikawa, Hiroshi; Park, Changkyoo; Suh, Jeong

2018-03-01

Fusing treatment of Ni-based self-fluxing alloys (Metco-16C and 1276F) was performed using high-power diode lasers to control the temperature of the substrate's surface in real time. The effects of the fusing treatment temperature on the microstructural change and hardness distribution were also investigated. For Metco-16C and 1276F, the macrostructural inhomogeneity (voids) within the thermal sprayed layer decreased considerably as the fusing temperature increased. For both self-fluxing alloys, the optimal temperature for fusing was approximately 1423 K (for Metco-16C) and 1373 K (for 1276F), both of which are within the solid state temperature range; these temperatures maximize the alloy hardness together with the macrostructural homogeneity. In this temperature range, the microstructure consists of a lamellar-structured matrix phase with fine (<5 μm) carbides and borides. Selective fusing for a thermal sprayed layer 0.2-0.5 mm in thickness could be successfully achieved in a high-power diode laser system.

Integration of high power laser diodes with microoptical components in a compact pumping source for visible fiber laser

NASA Astrophysics Data System (ADS)

Goering, Rolf; Hoefer, Bernd; Kraeplin, Anke; Schreiber, Peter; Kley, Ernst-Bernhard; Schmeisser, Volkmar

1999-04-01

A novel technique, the so-called skew ray imaging concept, has been developed for beam transformation of high power diode laser bars. It leads to beam circularization with optimum brightness conservation. This concept uses two key microoptical components: a fast axis collimator microlens (FAC) of high isoplanatism and a special array of beam deflecting elements, the number of which corresponds to the single emitter number of the diode laser. Using this concept of skew ray imaging in a modified form, prototypes of pumping sources for visible fiber laser have been developed and built up. Several watts of optical power have been focused into a small spot of 25 micrometers with a numerical aperture of 0.35. GRIN cylindrical microlenses with 0.1 mm focal length and diffractive blazed gratings as redirector have been used. The grating periods of the redirector sections have been between 8 and 100 (mu) M. They have been produced by e-beam direct writing in resist. After optimization of the fabrication process the diffraction efficiencies of al sections have been beyond 86 percent with good reproducibility. Special techniques have been sued for system integration. The FAC microlenses have been attached to a copper lens holder with a subsequent gluing process of the holder to the laser diode heatsink. A UV-curable adhesive with extremely low shrinkage has been selected. The redirector element has been integrated with an additional possibility for lateral adjustment in order to compensate minor residual walk-off effects of the microlens when the laser power is varied from zero to maximum. A very compact pumping source of 3 inches X 1 inch X 1 inch dimensions has been realized with 5 W optical power in the desired spot. First diode pumped fiber laser operation in the visible has been demonstrated with this source.

11-kW direct diode laser system with homogenized 55 × 20 mm2 Top-Hat intensity distribution

NASA Astrophysics Data System (ADS)

Köhler, Bernd; Noeske, Axel; Kindervater, Tobias; Wessollek, Armin; Brand, Thomas; Biesenbach, Jens

2007-02-01

In comparison with other laser systems diode lasers are characterized by a unique overall efficiency, a small footprint and high reliability. However, one major drawback of direct diode laser systems is the inhomogeneous intensity distribution in the far field. Furthermore the output power of current commercially available systems is limited to about 6 kW. We report on a diode laser system with 11 kW output power at a single wavelength of 940 nm aiming for customer specific large area treatment. To the best of our knowledge this is the highest output power reported so far for a direct diode laser system. In addition to the high output power the intensity distribution of the laser beam is homogenized in both axes leading to a 55 x 20 mm2 Top-Hat intensity profile at a working distance of 400 mm. Homogeneity of the intensity distribution is better than 90%. The intensity in the focal plane is 1 kW/cm2. We will present a detailed characterization of the laser system, including measurements of power, power stability and intensity distribution of the homogenized laser beam. In addition we will compare the experimental data with the results of non-sequential raytracing simulations.

Tunable diode laser absorption spectroscopy-based tomography system for on-line monitoring of two-dimensional distributions of temperature and H2O mole fraction.

PubMed

Xu, Lijun; Liu, Chang; Jing, Wenyang; Cao, Zhang; Xue, Xin; Lin, Yuzhen

2016-01-01

To monitor two-dimensional (2D) distributions of temperature and H2O mole fraction, an on-line tomography system based on tunable diode laser absorption spectroscopy (TDLAS) was developed. To the best of the authors' knowledge, this is the first report on a multi-view TDLAS-based system for simultaneous tomographic visualization of temperature and H2O mole fraction in real time. The system consists of two distributed feedback (DFB) laser diodes, a tomographic sensor, electronic circuits, and a computer. The central frequencies of the two DFB laser diodes are at 7444.36 cm(-1) (1343.3 nm) and 7185.6 cm(-1) (1391.67 nm), respectively. The tomographic sensor is used to generate fan-beam illumination from five views and to produce 60 ray measurements. The electronic circuits not only provide stable temperature and precise current controlling signals for the laser diodes but also can accurately sample the transmitted laser intensities and extract integrated absorbances in real time. Finally, the integrated absorbances are transferred to the computer, in which the 2D distributions of temperature and H2O mole fraction are reconstructed by using a modified Landweber algorithm. In the experiments, the TDLAS-based tomography system was validated by using asymmetric premixed flames with fixed and time-varying equivalent ratios, respectively. The results demonstrate that the system is able to reconstruct the profiles of the 2D distributions of temperature and H2O mole fraction of the flame and effectively capture the dynamics of the combustion process, which exhibits good potential for flame monitoring and on-line combustion diagnosis.

Tunable diode laser absorption spectroscopy-based tomography system for on-line monitoring of two-dimensional distributions of temperature and H2O mole fraction

NASA Astrophysics Data System (ADS)

Xu, Lijun; Liu, Chang; Jing, Wenyang; Cao, Zhang; Xue, Xin; Lin, Yuzhen

2016-01-01

To monitor two-dimensional (2D) distributions of temperature and H2O mole fraction, an on-line tomography system based on tunable diode laser absorption spectroscopy (TDLAS) was developed. To the best of the authors' knowledge, this is the first report on a multi-view TDLAS-based system for simultaneous tomographic visualization of temperature and H2O mole fraction in real time. The system consists of two distributed feedback (DFB) laser diodes, a tomographic sensor, electronic circuits, and a computer. The central frequencies of the two DFB laser diodes are at 7444.36 cm-1 (1343.3 nm) and 7185.6 cm-1 (1391.67 nm), respectively. The tomographic sensor is used to generate fan-beam illumination from five views and to produce 60 ray measurements. The electronic circuits not only provide stable temperature and precise current controlling signals for the laser diodes but also can accurately sample the transmitted laser intensities and extract integrated absorbances in real time. Finally, the integrated absorbances are transferred to the computer, in which the 2D distributions of temperature and H2O mole fraction are reconstructed by using a modified Landweber algorithm. In the experiments, the TDLAS-based tomography system was validated by using asymmetric premixed flames with fixed and time-varying equivalent ratios, respectively. The results demonstrate that the system is able to reconstruct the profiles of the 2D distributions of temperature and H2O mole fraction of the flame and effectively capture the dynamics of the combustion process, which exhibits good potential for flame monitoring and on-line combustion diagnosis.

Tunable diode laser absorption spectroscopy-based tomography system for on-line monitoring of two-dimensional distributions of temperature and H{sub 2}O mole fraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Lijun, E-mail: lijunxu@buaa.edu.cn; Liu, Chang; Jing, Wenyang

2016-01-15

To monitor two-dimensional (2D) distributions of temperature and H{sub 2}O mole fraction, an on-line tomography system based on tunable diode laser absorption spectroscopy (TDLAS) was developed. To the best of the authors’ knowledge, this is the first report on a multi-view TDLAS-based system for simultaneous tomographic visualization of temperature and H{sub 2}O mole fraction in real time. The system consists of two distributed feedback (DFB) laser diodes, a tomographic sensor, electronic circuits, and a computer. The central frequencies of the two DFB laser diodes are at 7444.36 cm{sup −1} (1343.3 nm) and 7185.6 cm{sup −1} (1391.67 nm), respectively. The tomographicmore » sensor is used to generate fan-beam illumination from five views and to produce 60 ray measurements. The electronic circuits not only provide stable temperature and precise current controlling signals for the laser diodes but also can accurately sample the transmitted laser intensities and extract integrated absorbances in real time. Finally, the integrated absorbances are transferred to the computer, in which the 2D distributions of temperature and H{sub 2}O mole fraction are reconstructed by using a modified Landweber algorithm. In the experiments, the TDLAS-based tomography system was validated by using asymmetric premixed flames with fixed and time-varying equivalent ratios, respectively. The results demonstrate that the system is able to reconstruct the profiles of the 2D distributions of temperature and H{sub 2}O mole fraction of the flame and effectively capture the dynamics of the combustion process, which exhibits good potential for flame monitoring and on-line combustion diagnosis.« less

1064-nm Nd:YAG and 980-nm Diode Laser EDTA Agitation on the Retention of an Epoxy-Based Sealer to Root Dentin.

PubMed

Macedo, Helena Suleiman de; Messias, Danielle Cristine Furtado; Rached-Júnior, Fuad Jacob; Oliveira, Ligia Teixeira de; Silva-Sousa, Yara Teresinha Correa; Raucci-Neto, Walter

2016-01-01

Root canal irrigants are used to minimize the negative effects of smear layer on endodontic sealer retention. The aim of this study was to evaluate the efficacy of agitation of 17% ethylenediaminetetraacetic acid (EDTA) with ultrasonic, 1064-nm Nd:YAG and 980-nm diode laser on the retention of an epoxy-based sealer to the root canal walls. Forty single-rooted bovine teeth were instrumented with ProTaper rotary system and divided into four groups according to the final irrigation protocol (n = 10): (1) 17% EDTA (control); (2) 17% EDTA with 50-s ultrasonic agitation; (3) 17% EDTA with 50-s diode laser (2-W) agitation; and (4) 17% EDTA with 50-s Nd:YAG (1.5-W) laser agitation. After endodontic filling with gutta-percha F5 master cone and Sealer 26, the roots were sectioned at the cervical, middle, and apical root thirds to obtain 1.5-mm slices. Push-out tests were performed using a universal testing machine at a 1 mm/min crosshead speed. Data were analyzed using two-way ANOVA and Tukey's tests (α=0.05). Apical root thirds had significant higher retention values than cervical and middle thirds (p < 0.05). EDTA with 1064-nm Nd:YAG or 980-nm diode laser presented the highest retention values and was significantly different from EDTA with ultrasonic agitation and EDTA only (p < 0.05). Adhesive failures were predominant to EDTA only group. Mixed failures were predominant to all agitation groups. 1064-nm Nd:YAG and 980-nm diode laser EDTA agitation enhanced the retention of the epoxy-based sealer to the root canal walls compared with that due to EDTA only or EDTA with ultrasonic agitation.

Photodynamic therapy using a novel irradiation source, LED lamp, is similarly effective to photodynamic therapy using diode laser or metal-halide lamp on DMBA- and TPA-induced mouse skin papillomas.

PubMed

Takahashi, Hidetoshi; Nakajima, Susumu; Ogasawara, Koji; Asano, Ryuji; Nakae, Yoshinori; Sakata, Isao; Iizuka, Hajime

2014-08-01

Photodynamic therapy (PDT) is useful for superficial skin tumors such as actinic keratosis and Bowen disease. Although PDT is non-surgical and easily-performed treatment modality, irradiation apparatus is large and expensive. Using 7, 12-dimethylbenz[a]anthracene (DMBA) and 12-ο-tetradecanoylphorbol-13-acetate (TPA)-induced mouse skin papilloma model, we compared the efficacy of TONS501- and ALA-PDT with a LED lamp, a diode laser lamp or a metal-halide lamp on the skin tumor regression. TONS501-PDT using 660 nm LED lamp showed anti-tumor effect at 1 day following the irradiation and the maximal anti-tumor effect was observed at 3 days following the irradiation. There was no significant difference in the anti-tumor effects among TONS501-PDT using LED, TONS501-PDT using diode laser, and 5-aminolevulinic acid hydrochloride (ALA)-PDT using metal-halide lamp. Potent anti-tumor effect on DMBA- and TPA-induced mouse skin papilloma was observed by TONS501-PDT using 660 nm LED, which might be more useful for clinical applications. © 2014 Japanese Dermatological Association.

Computer-Assisted Experiments with a Laser Diode

ERIC Educational Resources Information Center

Kraftmakher, Yaakov

2011-01-01

A laser diode from an inexpensive laser pen (laser pointer) is used in simple experiments. The radiant output power and efficiency of the laser are measured, and polarization of the light beam is shown. The "h/e" ratio is available from the threshold of spontaneous emission. The lasing threshold is found using several methods. With a…

Advanced chip designs and novel cooling techniques for brightness scaling of industrial, high power diode laser bars

NASA Astrophysics Data System (ADS)

Heinemann, S.; McDougall, S. D.; Ryu, G.; Zhao, L.; Liu, X.; Holy, C.; Jiang, C.-L.; Modak, P.; Xiong, Y.; Vethake, T.; Strohmaier, S. G.; Schmidt, B.; Zimer, H.

2018-02-01

The advance of high power semiconductor diode laser technology is driven by the rapidly growing industrial laser market, with such high power solid state laser systems requiring ever more reliable diode sources with higher brightness and efficiency at lower cost. In this paper we report simulation and experimental data demonstrating most recent progress in high brightness semiconductor laser bars for industrial applications. The advancements are in three principle areas: vertical laser chip epitaxy design, lateral laser chip current injection control, and chip cooling technology. With such improvements, we demonstrate disk laser pump laser bars with output power over 250W with 60% efficiency at the operating current. Ion implantation was investigated for improved current confinement. Initial lifetime tests show excellent reliability. For direct diode applications <1 um smile and >96% polarization are additional requirements. Double sided cooling deploying hard solder and optimized laser design enable single emitter performance also for high fill factor bars and allow further power scaling to more than 350W with 65% peak efficiency with less than 8 degrees slow axis divergence and high polarization.

The effectiveness of low-level diode laser therapy on orthodontic pain management: a systematic review and meta-analysis.

PubMed

Ren, Chong; McGrath, Colman; Yang, Yanqi

2015-09-01

To assess the effectiveness of diode low-level laser therapy (LLLT) for orthodontic pain control, a systematic and extensive electronic search for randomised controlled trials (RCTs) investigating the effects of diode LLLT on orthodontic pain prior to November 2014 was performed using the Cochrane Library (Issue 9, 2014), PubMed (1997), EMBASE (1947) and Web of Science (1956). The Cochrane tool for risk of bias evaluation was used to assess the bias risk in the chosen data. A meta-analysis was conducted using RevMan 5.3. Of the 186 results, 14 RCTs, with a total of 659 participants from 11 countries, were included. Except for three studies assessed as having a 'moderate risk of bias', the RCTs were rated as having a 'high risk of bias'. The methodological weaknesses were mainly due to 'blinding' and 'allocation concealment'. The meta-analysis showed that diode LLLT significantly reduced orthodontic pain by 39 % in comparison with placebo groups (P = 0.02). Diode LLLT was shown to significantly reduce the maximum pain intensity among parallel-design studies (P = 0.003 versus placebo groups; P = 0.000 versus control groups). However, no significant effects were shown for split-mouth-design studies (P = 0.38 versus placebo groups). It was concluded that the use of diode LLLT for orthodontic pain appears promising. However, due to methodological weaknesses, there was insufficient evidence to support or refute LLLT's effectiveness. RCTs with better designs and appropriate sample power are required to provide stronger evidence for diode LLLT's clinical applications.

High Power Laser Diode Array Qualification and Guidelines for Space Flight Environments

NASA Technical Reports Server (NTRS)

Eegholm, Niels; Ott, Melanie; Stephen, Mark; Leidecker, Henning

2005-01-01

Semiconductor laser diodes emit coherent light by simulated emission generated inside the cavity formed by the cleaved end facets of a slab of semiconductor that is typically less than a millimeter in any dimension for single emitters. The diode is pumped by current injection in the p-n junction through the metallic contacts. Laser diodes emitting in the range of 0.8 micron to 1.06 micron have a wide variety of applications from pumping erbium doped fiber amplifiers, dual-clad fiber lasers, solid-state lasers used in telecom, aerospace, military, medical purposes and all the way to CD players, laser printers and other consumer and industrial products. Laser diode bars have many single emitters side by side and spaced approximately .5 mm on a single slab of semiconductor material approximately .5 mm x 10 mm. The individual emitters are connected in parallel maintaining the voltage at -2V but increasing the current to 50-100A/bar. Stacking these laser diode bars in multiple layers, 2 to 20+ high, yields high power laser diode arrays capable of emitting several hundreds of Watts. Electrically the bars are wired in series increasing the voltage by 2V/bar but maintaining the total current at 50-100A. These arrays are one of the enabling technologies for efficient, high power solid-state lasers. Traditionally these arrays are operated in QCW (Quasi CW) mode with pulse widths 10-200 (mu)s and with repetition rates of 10-200Hz. In QCW mode the wavelength and the output power of the laser reaches steady-state but the temperature does not. The advantage is a substantially higher output power than in CW mode, where the output power would be limited by the internal heating and hence the thermal and heat sinking properties of the device. The down side is a much higher thermal induced mechanical stress caused by the constant heating and cooling cycle inherent to the QCW mode.

Novel diode laser-based sensors for gas sensing applications

NASA Technical Reports Server (NTRS)

Tittel, F. K.; Lancaster, D. G.; Richter, D.

2000-01-01

The development of compact spectroscopic gas sensors and their applications to environmental sensing will be described. These sensors employ mid-infrared difference-frequency generation (DFG) in periodically poled lithium niobate (PPLN) crystals pumped by two single-frequency solid state lasers such as diode lasers, diode-pumped solid state, and fiber lasers. Ultrasensitive, highly selective, and real-time measurements of several important atmospheric trace gases, including carbon monoxide, nitrous oxide, carbon dioxide, formaldehyde [correction of formaldehye], and methane, have been demonstrated.

Diode Lasers and Light Emitting Diodes Operating at Room Temperature with Wavelengths Above 3 Micrometers

DTIC Science & Technology

2011-11-29

as an active region of mid - infrared LEDs. It should be noted that active region based on interband transition is equally useful for both laser and...IR LED technology for infrared scene projectors”, Dr. E. Golden, Air Force Research Laboratory, Eglin Air Force Base .  “A stable mid -IR, GaSb...multimode lasers. Single spatial mode 3-3.2 J.lm diode lasers were developed. LEDs operate at wavelength above 4 J.lm at RT. Dual color mid - infrared

Stable CW Single Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking

NASA Technical Reports Server (NTRS)

Duerksen, Gary L.; Krainak, Michael A.

1999-01-01

Previously, single-frequency semiconductor laser operation using fiber Bragg gratings has been achieved by tWo methods: 1) use of the FBG as the output coupler for an anti-reflection-coated semiconductor gain element'; 2) pulsed operation of a gain-switched Fabry-Perot laser diode with FBG-optical and RF-electrical feedback'. Here, we demonstrate CW single frequency operation from a non-AR coated Fabry-Perot laser diode using only FBG optical feedback.

Stable CW Single-Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking

NASA Technical Reports Server (NTRS)

Duerksen, Gary L.; Krainak, Michael A.

1998-01-01

Previously, single-frequency semiconductor laser operation using fiber Bragg gratings (FBG) has been achieved by two methods: (1) use of the FBG as the output coupler for an anti-reflection-coated semiconductor gain element; (2) pulsed operation of a gain-switched Fabry-Perot laser diode with FBG-optical and RF-electrical feedback. Here, we demonstrate CW single frequency operation from a non-AR coated Fabry-Perot laser diode using only FBG optical feedback.

Computer Processing Of Tunable-Diode-Laser Spectra

NASA Technical Reports Server (NTRS)

May, Randy D.

1991-01-01

Tunable-diode-laser spectrometer measuring transmission spectrum of gas operates under control of computer, which also processes measurement data. Measurements in three channels processed into spectra. Computer controls current supplied to tunable diode laser, stepping it through small increments of wavelength while processing spectral measurements at each step. Program includes library of routines for general manipulation and plotting of spectra, least-squares fitting of direct-transmission and harmonic-absorption spectra, and deconvolution for determination of laser linewidth and for removal of instrumental broadening of spectral lines.

Advances in single mode and high power AlGaInN laser diode technology for systems applications

NASA Astrophysics Data System (ADS)

Najda, Stephen P.; Perlin, Piotr; Suski, Tadek; Marona, Lujca; Boćkowski, Michal; Leszczyński, Mike; Wisniewski, Przemek; Czernecki, Robert; Kucharski, Robert; Targowski, Grzegorz; Smalc-Koziorowska, Julita; Stanczyk, Szymon; Watson, Scott; Kelly, Antony E.

2015-03-01

The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well. Thus AlGaInN laser diode technology is a key enabler for the development of new disruptive system level applications in displays, telecom, defence and other industries.

Visible light surface emitting semiconductor laser

DOEpatents

Olbright, Gregory R.; Jewell, Jack L.

1993-01-01

A vertical-cavity surface-emitting laser is disclosed comprising a laser cavity sandwiched between two distributed Bragg reflectors. The laser cavity comprises a pair of spacer layers surrounding one or more active, optically emitting quantum-well layers having a bandgap in the visible which serve as the active optically emitting material of the device. The thickness of the laser cavity is m .lambda./2n.sub.eff where m is an integer, .lambda. is the free-space wavelength of the laser radiation and n.sub.eff is the effective index of refraction of the cavity. Electrical pumping of the laser is achieved by heavily doping the bottom mirror and substrate to one conductivity-type and heavily doping regions of the upper mirror with the opposite conductivity type to form a diode structure and applying a suitable voltage to the diode structure. Specific embodiments of the invention for generating red, green, and blue radiation are described.

AlGaInN laser diode technology for systems applications

NASA Astrophysics Data System (ADS)

Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Bockowski, M.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Kucharski, R.; Targowski, G.; Watson, S.; Kelly, A. E.

2016-02-01

Gallium Nitride (GaN) laser diodes fabricated from the AlGaInN material system is an emerging technology that allows laser diodes to be fabricated over a very wide wavelength range from u.v. to the visible, and is a key enabler for the development of new system applications such as (underwater and terrestrial) telecommunications, quantum technologies, display sources and medical instrumentation.

Developments in holographic-based scanner designs

NASA Astrophysics Data System (ADS)

Rowe, David M.

1997-07-01

Holographic-based scanning systems have been used for years in the high resolution prepress markets where monochromatic lasers are generally utilized. However, until recently, due to the dispersive properties of holographic optical elements (HOEs), along with the high cost associated with recording 'master' HOEs, holographic scanners have not been able to penetrate major scanning markets such as the laser printer and digital copier markets, low to mid-range imagesetter markets, and the non-contact inspection scanner market. Each of these markets has developed cost effective laser diode based solutions using conventional scanning approaches such as polygon/f-theta lens combinations. In order to penetrate these markets, holographic-based systems must exhibit low cost and immunity to wavelength shifts associated with laser diodes. This paper describes recent developments in the design of holographic scanners in which multiple HOEs, each possessing optical power, are used in conjunction with one curved mirror to passively correct focal plane position errors and spot size changes caused by the wavelength instability of laser diodes. This paper also describes recent advancements in low cost production of high quality HOEs and curved mirrors. Together these developments allow holographic scanners to be economically competitive alternatives to conventional devices in every segment of the laser scanning industry.

Thermal effect of diode-pumped solid state lasers based on composite crystals

NASA Astrophysics Data System (ADS)

Hao, Ming-ming; Lu, Guo-guang; Zhu, Hong-bo; Huang, Yun; En, Yun-fei

2013-12-01

Thermal effect of diode-pumped solid-state lasers (DPSSL) based on YAP/Tm:YAP composite crystal is studied by using of finite element method (FEM). It is found that the peak temperature in a composite rod decreases to less than 80% of that in a non-composite crystal. Thermal stress of composite rod is obviously reduced to less than 70% comparing with non-composite crystal. It is also demonstrated that length of thermal lens unchanged with increasing of un-doped crystal length, which means that beam quality of composite laser wouldn't be improved by non-composite crystal. Therefore, it is concluded that using composite crystal would benefit for the properties of temperature and heat stress while insignificance for beam quality of DPSSL.

Mode-locked Ti:sapphire laser oscillators pumped by wavelength-multiplexed laser diodes

NASA Astrophysics Data System (ADS)

Sugiyama, Naoto; Tanaka, Hiroki; Kannari, Fumihiko

2018-05-01

We directly pumped a Ti:sapphire laser by combining 478 and 520 nm laser diodes to prevent the effect of absorption loss induced by the pump laser of shorter wavelengths (∼450 nm). We obtain a continuous-wave output power of 660 mW at a total incident pump power of 3.15 W. We demonstrate mode locking using a semiconductor saturable absorber mirror, and 126 fs pulses were obtained at a repetition rate of 192 MHz. At the maximum pump power, the average output power is 315 mW. Shorter mode-locked pulses of 42 and 48 fs were respectively achieved by Kerr-lens mode locking with average output powers of 280 and 360 mW at a repetition rate of 117 MHz.