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Sample records for 532-nm fiber laser

  1. A 532 nm Chaotic Fiber Laser Transmitter for Underwater Lidar

    DTIC Science & Technology

    2013-04-23

    cooling to deal with the heat. There are no direct solid-state blue-green transitions, but neodymium -doped YAG crystal lasers (Nd:YAG)) is commonly...dopants include neodymium , thulium, praseodymium, yt- terbium, and erbium, but the latter two are by far the most common. Erbium-doped fiber lasers

  2. In vitro assessment of fiber sweeping speed during Q-switched 532-nm laser tissue ablation

    NASA Astrophysics Data System (ADS)

    Rajabhandharaks, Danop; Kang, Hyun Wook; Ko, Woo Jin; Stinson, Douglas; Choi, Benjamin

    2011-03-01

    Photoselective vaporization of the prostate (PVP) is considered a minimally invasive procedure to treat benign prostatic hyperplasia (BPH). During the PVP, the prostate gland is irradiated by the 532-nm laser and the fiber is swept and dragged along the urethra. In this study the speed of sweeping fiber during the PVP is being investigated. In vitro porcine kidney model was used (N=100) throughout the experiment. A Q-switched 532-nm laser, equipped with sidefiring 750-Um fiber, was employed and set to power levels of 120 and 180 W. The speed of fiber sweeping was the only variable in this study and varied at 0 (i.e. no sweeping), 0.5, 1.0, 1.5, and 2.0 sweep/s. Ablation rate, depth, and coagulation thickness were quantified. Based on the current settings, ablation rate decreased as sweeping speed increased and was maximized between 0 to 1.0 sweep/s for 120-W power level and between 0 to 0.5 sweep/s for 180-W power level. Ablation rate at 180 W was higher than that at 120 W, regardless of sweeping speed. Ablation depth at both 120 and 180 W was maximized at 0 sweep/s and decreased 35% at 0.5 sweep/s. The overall coagulation thickness was less than 1.5 mm and comparable from 0 to 1.5 sweep/s (0.8~0.9 mm) and increased at 2.0 sweep/s (~1.1 mm). This study demonstrated that tissue ablation performance was contingent upon sweeping speed and maximized at slow sweeping speed due to longer laser-tissue interaction time and larger area coverage by the 532-nm light.

  3. MoXy fiber with active cooling cap for bovine prostate vaporization with high power 200W 532 nm laser

    NASA Astrophysics Data System (ADS)

    Peng, Steven Y.; Kang, Hyun Wook; Pirzadeh, Homa; Stinson, Douglas

    2011-03-01

    A novel MoXyTM fiber delivery device with Active Cooling Cap (ACCTM) is designed to transmit up to 180W of 532 nm laser light to treat benign prostatic hyperplasia (BPH). Under such high power tissue ablation, effective cooling is key to maintaining fiber power transmission and ensuring the reliability of the fiber delivery device To handle high power and reduce fiber degradation, the MoXy fiber features a larger core size (750 micrometer) and an internal fluid channel to ensure better cooling of the fiber tip to prevent the cap from burning, detaching, or shattering during the BPH treatment. The internal cooling channel was created with a metal cap and tubing that surrounds the optical fiber. In this study MoXy fibers were used to investigate the effect of power levels of 120 and 200 W on in-vitro bovine prostate ablation using a 532 nm XPSTM laser system. For procedures requiring more than 100 kJ, the MoXy fiber at 200W removed tissue at twice the rate of the current HPS fiber at 120W. The fiber maintained a constant tissue vaporization rate during the entire tissue ablation process. The coagulation at 200W was about 20% thicker than at 120W. In conclusion, the new fibers at 200W doubled the tissue removal rate, maintained vaporization efficiency throughout delivery of 400kJ energy, and induced similar coagulation to the existing HPS fiber at 120W.

  4. In vitro assessment of fiber sweeping angle during Q-switched 532-nm laser tissue ablation

    NASA Astrophysics Data System (ADS)

    Rajabhandharaks, Danop; Kang, Hyun Wook; Ko, Woo Jin; Stinson, Douglas; Choi, Benjamin

    2011-03-01

    Photoselective vaporization of the prostate (PVP) has been widely used to treat benign prostatic hyperplasia (BPH). It is well regarded as a safe and minimally invasive procedure and an alternative to the gold standard transurethral resection of the prostate (TURP). Despite of its greatness, as well aware of, the operative procedure time during the PVP is still prolonged. Such attempts have been tried out in order to shorten the operative time and increase its efficacy. However, scientific study to investigate techniques used during the PVP is still lacking. The objective of this study is to investigate how sweeping angle might affect the PVP performance. Porcine kidneys acquired from a local grocery store were used (N=140). A Q-switched 532-nm GreenLight XPSTM (American Medical Systems, Inc., MN, USA), together with 750- μm core MoXyTM fiber, was set to have power levels of 120 W and 180 W. Treatment speed and sweeping speed were fixed at 2 mm/s and 0.5 sweep/s, respectively. Sweeping angles were varied from 0 (no sweeping motion) to 120 degree. Ablation rate, depth, and coagulation zone were measured and quantified. Tissue ablation rate was peaked at 15 and 30 degree for both 120- and 180-W power levels and dramatically decreased beyond 60 degree. At 180 W, ablation rate increased 20% at 30 degree compared to 0 degree. This study demonstrated that ablation rate could be maximized and was contingent upon sweeping angle.

  5. Superconducting nanowire single photon detector at 532 nm and demonstration in satellite laser ranging.

    PubMed

    Li, Hao; Chen, Sijing; You, Lixing; Meng, Wengdong; Wu, Zhibo; Zhang, Zhongping; Tang, Kai; Zhang, Lu; Zhang, Weijun; Yang, Xiaoyan; Liu, Xiaoyu; Wang, Zhen; Xie, Xiaoming

    2016-02-22

    Superconducting nanowire single-photon detectors (SNSPDs) at a wavelength of 532 nm were designed and fabricated aiming to satellite laser ranging (SLR) applications. The NbN SNSPDs were fabricated on one-dimensional photonic crystals with a sensitive-area diameter of 42 μm. The devices were coupled with multimode fiber (ϕ = 50 μm) and exhibited a maximum system detection efficiency of 75% at an extremely low dark count rate of <0.1 Hz. An SLR experiment using an SNSPD at a wavelength of 532 nm was successfully demonstrated. The results showed a depth ranging with a precision of ~8.0 mm for the target satellite LARES, which is ~3,000 km away from the ground ranging station at the Sheshan Observatory.

  6. The 532-nm 180-W (GreenLight®) laser vaporization of the prostate for the treatment of lower urinary tract symptoms: how durable is the new side-fire fiber with integrated cooling system?

    PubMed

    Brunken, Claus; Munsch, Maximilian; Tauber, Stephan; Schmidt, Rainer; Seitz, Christian

    2014-05-01

    The 532-nm side-fire laser vaporization is established for the treatment of symptomatic benign prostate hyperplasia. Meanwhile, the third generation of this system is offered by American Medical Systems, Inc. The laser power increased from 80 and 120 to 180 W from the first to the third generation. Despite good functional results, with the 80- and 120-W systems, the removal of prostate tissue is limited because of fiber degradation. To overcome this problem, the fiber was designed newly with an integrated cooling system and a sensor for decreasing the laser energy in case of overheating. We evaluate whether the new fiber still suffers from degradation with consecutive drop of power transmission during the procedure. The power output of the cooled fiber was measured in vitro and during prostate vaporization in ten patients. Laser beam power was measured at baseline and after the application each of 50 kJ during laser vaporization. Power emission of the fiber remains constant at 20, 80, and 180 W of power settings over the whole 40-kJ lifespan. During the transurethral procedure, a median total energy of 276 kJ (standard deviation 153 kJ) was applied for vaporization. Median power output from the fiber at the end of the procedure was 97% from the baseline value. There were no fiber malfunctions observed. In contrast to former generations, the third-generation laser fiber is durable without significant power loss during prostate vaporization.

  7. Interaction between high power 532nm laser and prostatic tissue: in vitro evaluation for laser prostatectomy

    NASA Astrophysics Data System (ADS)

    Kang, Hyun Wook; Peng, Yihlih Steven; Stinson, Douglas

    2011-03-01

    Photoselective vaporization of the prostate (PVP) has been developed for effective treatment of obstructive benign prostatic hyperplasia. To maximize tissue ablation for large prostate gland, identifying the optimal power level for PVP is still necessary. We investigated the effect of various power levels on in vitro bovine prostate ablation with a 532-nm laser system. A custom-made 532-nm laser was employed to provide various power levels, delivered through a newly designed 750-μm side-firing fiber. Tissue ablation efficiency was evaluated in terms of power (P; 120~200W), treatment speed of fiber (TS; 2~8 mm/s), and working distance between fiber and tissue surface (WD; 1~5 mm). Coagulation depth was also estimated macroscopically and histologically (H&E) at various Ps. Both 180 and 200W yielded comparable ablated volume (104.3+/-24.7 vs. 104.1+/-23.9 mm3 at TS=4 mm/s and WD=2 mm; p=0.99); thus, 180W was identified as the optimal power to maximize tissue ablation, by removing tissue up to 80% faster than 120W (41.7+/-9.9 vs. 23.2+/-3.4 mm3/s at TS=4 mm/s and WD=2 mm; p<0.005). Tissue ablation was maximized at TS=4 mm/s and ablated equally efficiently at up to 3 mm WD (104.5+/-16.7 mm3 for WD=1 mm vs. 93.4+/-7.4 mm3 for WD=3 mm at 180W; p=0.33). The mean thickness of coagulation zone for 180W was 20% thicker than that for 120W (1.31+/-0.17 vs. 1.09+/-0.16 mm; p<0.005). The current in vitro study demonstrated that 180W was the optimal power to maximize tissue ablation efficiency with enhanced coagulation characteristics.

  8. Improving the laser-induced damage threshold of 532-nm antireflection coating using plasma ion cleaning

    NASA Astrophysics Data System (ADS)

    Zhu, Meiping; Xing, Huanbin; Chai, Yingjie; Yi, Kui; Sun, Jian; Wang, Jianguo; Shao, Jianda

    2017-01-01

    BK7 glass substrates were precleaned by different cleaning procedures before being loaded into a vacuum chamber, and then a series of plasma ion cleaning procedures were conducted at different bias voltages in the vacuum chamber, prior to the deposition of 532-nm antireflection (AR) coatings. The plasma ion cleaning process was implemented by the plasma ion bombardment from an advanced plasma source. The surface morphology of the plasma ion-cleaned substrate, as well as the laser-induced damage threshold (LIDT) of the 532-nm AR coating was investigated. The results indicated that the LIDT of 532-nm AR coating can be greatly influenced by the plasma ion cleaning energy. The plasma ion cleaning with lower energy is an attractive method to improve the LIDT of the 532-nm AR coating, due to the removal of the adsorbed contaminations on the substrate surface, as well as the removal of part of the chemical impurities hidden in the surface layer.

  9. Performance of multilayer optical coatings under long-term 532nm laser exposure

    NASA Astrophysics Data System (ADS)

    Poulios, D.; Konoplev, O.; Chiragh, F.; Vasilyev, A.; Stephen, M.; Strickler, K.

    2013-11-01

    The effects of long-term exposure to high intensity 532 nm radiation on various dielectric-coated optics are studied. To investigate potential photodarkening effects on optical surfaces, an accelerated life test platform was constructed where optics were exposed to 532 nm radiation from a short-pulse, high repetition rate fiber amplifier at total doses up to 1 trillion shots. The first run of trillion-shot tests were conducted on e-beam deposited and ion beam sputtering (IBS) coated high reflecting mirrors with onsurface intensities ranging from 1.0-1.4 GW/cm2. It was found that the e-beam coated mirrors failed catastrophically at less than 150 billion shots, while the IBS coated mirror was able to complete the trillionshot test with no measurable loss of reflectivity. Profiling the IBS mirror surface with a high-resolution white light interferometer post-irradiation revealed a ~10 nm high photocontamination deposit at the irradiation site that closely matched the intensity profile of the laser spot. Trillion-shot surface exposure tests were also conducted at multiple surface sites of an LBO frequency doubling crystal at ~1.5 GW/cm2 at multiple surface sites. The transmitted power and on-surface beam size were monitored throughout the tests, and periodic measurements of the beam quality and waist location of the transmitted light were also made using an M2 meter. No changes in transmitted power or M2 were observed in any of the tests, but 3D surface profiling revealed laser-induced contamination deposits at each site tested.

  10. Remote Raman spectra of benzene obtained from 217 meters using a single 532 nm laser pulse.

    PubMed

    Chen, Teng; Madey, John M J; Price, Frank M; Sharma, Shiv K; Lienert, Barry

    2007-06-01

    This report describes a mobile Raman lidar system that has been developed for spectral measurements of samples located remotely at ranges of hundreds of meters. The performance of this system has been quantitatively verified in a lidar calibration experiment using a hard target of standardized reflectance. A new record in detection range was achieved for remote Raman systems using 532 nm laser excitation. Specifically, Raman spectra of liquid benzene were measured with an integration time corresponding to a single 532 nm laser pulse at a distance of 217 meters. The single-shot Raman spectra at 217 meters demonstrated high signal-to-noise ratio and good resolution sufficient for the unambiguous identification of the samples of interest. The transmitter consists of a 20 Hz Nd:YAG laser emitting at 532 nm and 1064 nm and a 178 mm telescope through the use of which allows the system to produce a focused beam at the target location. The receiver consists of a large custom telescope (609 mm aperture) and a Czerny-Turner monochromator equipped with two fast photomultiplier tubes.

  11. Interaction of pulse laser radiation of 532 nm with model coloration layers for medieval stone artefacts

    NASA Astrophysics Data System (ADS)

    Colson, J.; Nimmrichter, J.; Kautek, W.

    2014-05-01

    Multilayer polychrome coatings on medieval and Renaissance stone artefacts represent substantial challenges in laser cleaning. Therefore, polychromic models with classical pigments, minium Pb22+PbO, zinc white (ZnO), and lead white ((PbCO3)2·Pb(OH)2) in an acrylic binder, were irradiated with a Q-switched Nd:YAG laser emitting at 532 nm. The studied medieval pigments exhibit strongly varying incubation behaviours directly correlated to their band gap energies. Higher band gaps beyond the laser photon energy of 2.3 eV require more incubative generation of defects for resonant transitions. A matching of the modification thresholds after more than four laser pulses was observed. Laser cleaning with multiple pulsing should not exceed ca. 0.05 J/cm2 when these pigments coexist in close spatial proximity.

  12. Effects of Nd:YAG (532 nm) laser radiation on `clean' cotton

    NASA Astrophysics Data System (ADS)

    Bloisi, F.; Vicari, L.; Barone, A. C.; Martuscelli, E.; Gentile, G.; Polcaro, C.

    The use of pulsed laser radiation in order to remove small particles from a substrate has gained a growing interest in the last decade, finding applications in several fields ranging from the microcircuits industry to cultural heritage restoration and conservation. The application of such a technique requires the knowledge of the correct laser irradiation parameters to be used in order to obtain a desired result avoiding substrate damage. In this paper we have studied the effect of frequency-doubled (532 nm) Nd:YAG laser radiation on clean cotton samples. We have observed that `yellowing' is present even at low fluences. This suggests that less invasive laser assisted particle removal techniques, some of which have already been proposed by different authors, must be considered.

  13. Influence of consecutive picosecond pulses at 532 nm wavelength on laser ablation of human teeth

    NASA Astrophysics Data System (ADS)

    Mirdan, Balsam M.; Antonelli, Luca; Batani, Dimitri; Jafer, Rashida; Jakubowska, Katarzyna; Tarazi, Saad al; Villa, Anna Maria; Vodopivec, Bruno; Volpe, Luca

    2014-07-01

    The interaction of 40 ps pulse duration laser emitting at 532 nm wavelength with human dental tissue (enamel, dentin, and dentin-enamel junction) has been investigated. The crater profile and the surface morphology have been studied by using a confocal auto-fluorescence microscope (working in reflection mode) and a scanning electron microscope. Crater profile and crater morphology were studied after applying consecutive laser pulses and it was found that the ablation depth increases with the number of consecutive pulses, leaving the crater diameter unchanged. We found that the thermal damage is reduced by using short duration laser pulses, which implies an increased retention of restorative material. We observe carbonization of the irradiated samples, which does not imply changes in the chemical composition. Finally, the use of 40 ps pulse duration laser may become a state of art in conservative dentistry.

  14. Pulsed 532 nm laser wirestripping: Removal of dye-doped polyurethane insulation

    NASA Astrophysics Data System (ADS)

    Brannon, J.; Snyder, C.

    1994-07-01

    Removal of rhodamine 6G doped polyurethane insulation coated onto 50 μm diameter wire is shown to proceed efficiently and cleanly by irradiation with 532 nm Q-switched pulses from a Nd:YAG laser. The stripping action produced by this method is similar in quality to excimer laser wirestripping. Several experimental parameters were explored including fluence, pulse duration, dye concentration, and the number of incident pulses. Acceptable stripping conditions were obtained for a 3 5 s exposure at 10 Hz, using a dye concentration of 10% by weight, and 12 n pulses at 650 mJ/cm2. Nearly 0.5 μm/pulse is removed at this fluence, which exceeds the threshold fluence of ≈600 mJ/cm2 by only 50 mJ/cm2. The measured 532 nm absorption coefficient of the 10% dye-doped polyurethane was ≈4×104 cm-1. Lower fluences and/or dye concentrations produced inadequate stripping, while shorter duration pulses caused unacceptable melting of the thin gold layer which covered the copper core of the wire. Pulse-by-pulse photographs of the stripping action clearly show melting of the dye/polymer insulation, and thermal “rollback” of the insulation near the stripped end. Regardless, excellent edge definition is obtained by this method.

  15. Stimulated scattering effects in gold-nanorod-water samples pumped by 532 nm laser pulses.

    PubMed

    Shi, Jiulin; Wu, Haopeng; Liu, Juan; Li, Shujing; He, Xingdao

    2015-07-15

    Stimulated scattering in gold-nanorod-water samples has been investigated experimentally. The scattering centers are impurity particles rather than the atoms or molecules of conventional homogeneous scattering media. The pump source for exciting stimulated scattering is a pulsed and narrow linewidth second-harmonic Nd: YAG laser, with 532 nm wavelength, ~8 ns pulse duration, and 10 Hz repetition rate. Experimental results indicate that SMBS, SBS and STRS can be generated in gold-nanorod-water samples under appropriate pump and absorption conditions. The incident pump energy has to be larger than a certain threshold value before stimulated scattering can be detected. The absorption coefficient of samples at 532 nm wavelength depends on the one of characteristic absorption bands of gold nanorods located around 530 nm. A critical absorption coefficient can be determined for the transition from SBS to STRS. Also, the spectral-line-broadening effects of STRS have been observed, the line-shape presents a pseudo-Voigt profile due to the random thermal motion of molecules and strong particle collision.

  16. Optimal irradiance for sintering of inkjet-printed Ag electrodes with a 532nm CW laser

    NASA Astrophysics Data System (ADS)

    Moon, Yoon Jae; Kang, Heuiseok; Kang, Kyungtae; Hwang, Jun Young; Moon, Seung Jae

    2013-09-01

    Industrial solar cell fabrication generally adopts printing process to deposit the front electrodes, which needs additional heat treatment after printing to enhance electrical conductivity. As a heating method, laser irradiation draws attention not only because of its special selectivity, but also because of its intense heating to achieve high electric conductivity which is essential to reduce ohmic loss of solar cells. In this study, variation of electric conductivity was examined with laser irradiation having various beam intensity. 532 nm continuous wave (CW) laser was irradiated on inkjet-printed silver lines on glass substrate and electrical resistance was measured in situ during the irradiation. The results demonstrate that electric conductivity varies nonlinearly with laser intensity, having minimum specific resistance of 4.1 x 10-8 Ωm at 529 W/cm2 irradiation. The results is interesting because the specific resistance achieved by the present laser irradiation was about 1.8 times lower than the best value obtainable by oven heating, even though it was still higher by 2.5 times than that of bulk silver. It is also demonstrated that the irradiation time, needed to finish sintering process, decreases with laser intensity. The numerical simulation of laser heating showed that the optimal heating temperature could be as high as 300 oC for laser sintering, while it was limited to 250 oC for oven sintering. The nonlinear response of sintering with heating intensity was discussed, based on the results of FESEM images and XRD analysis.

  17. 532 nm Low-Power Laser Irradiation Facilitates the Migration of GABAergic Neural Stem/Progenitor Cells in Mouse Neocortex

    PubMed Central

    Fukuzaki, Yumi; Shin, Hyeryun; Kawai, Hideki D.; Yamanoha, Banri; Kogure, Shinichi

    2015-01-01

    Background and Objective Accumulating evidence has shown that low-power laser irradiation (LLI) affects cell proliferation and survival, but little is known about LLI effects on neural stem/progenitor cells (NSPCs). Here we investigate whether transcranial 532 nm LLI affects NSPCs in adult murine neocortex and in neurospheres from embryonic mice. Study Design/Materials and Methods We applied 532 nm LLI (Nd:YVO4, CW, 60 mW) on neocortical surface via cranium in adult mice and on cultured cells from embryonic mouse brains in vitro to investigate the proliferation and migration of NSPCs and Akt expression using immunohistochemical assays and Western blotting techniques. Results In vivo experiments demonstrated that 532 nm LLI significantly facilitated the migration of GABAergic NSPCs that were induced to proliferate in layer 1 by mild ischemia. In vitro experiments using GABAergic NSPCs derived from embryonic day 14 ganglionic eminence demonstrated that 532 nm LLI for 60 min promoted the migration of GAD67-immunopositive NSPCs with a significant increase of Akt expression. Meanwhile, the LLI induced proliferation, but not migration, of NSPCs that give rise to excitatory neurons. Conclusion It is concluded that 532 nm LLI promoted the migration of GABAergic NSPCs into deeper layers of the neocortex in vivo by elevating Akt expression. PMID:25919297

  18. LD pumped high-repetition-rate high-power 532nm Nd:YAG/LBO solid state laser

    NASA Astrophysics Data System (ADS)

    Li, Pingxue; Liu, Dongyu; Chi, Junjie; Yang, Chun; Zhao, Ziqiang; Hu, Haowei; Zhang, Guangju; Yao, Yifei

    2013-09-01

    Diode pumped solid state 532 nm green laser is widely required for many industrial, medical and scientific applications. Among most of these applications, high power quasi-continuous-wave (QCW) green laser output is demanded. This can be efficiently achieved through a diode-side-pumped acoustic-optic Q-switched Nd:YAG laser with an intracavity second harmonic generation (SHG). In our experiment, LBO crystal is used for the second harmonic generation of high-average-power lasers of near infrared (NIR) range, though its effective NLO coefficient deff is relatively small. It is because of its high damage threshold (greater than 2.5 GW/cm2), large acceptance angle, small walk-off angle, and the nonhygroscopic characteristic. In this paper, we reported a high-repetition-rate high-power diode-side-pumped AO Q-switched Nd:YAG 532 nm laser. A plane-plane cavity with two rods, two AO Q-switches and the type II critical phase-matched LBO at room temperature were employed. Under the LD pump power of 480 W, 95.86 W at 1064 nm wavelength was achieved when the repetition rate was 15 kHz, and the 532 nm average output power of 44.77 W was obtained, with a pulse width of 111.7 ns, corresponding to an optical to optical conversion efficiency of 46.7% from 1064 nm to 532 nm. The 532 nm average output power was 40.10 W at a repetition rate of 10 kHz with a pulse width of 78.65 ns. The output characteristics of the SHG varying with the pumping current and the pulse repetition frequency (PRF) of the laser were also investigated. Further improvement of the SHG is under study.

  19. 532-nm laser sources based on intracavity frequency doubling of extended-cavity surface-emitting diode lasers

    NASA Astrophysics Data System (ADS)

    Shchegrov, Andrei V.; Umbrasas, Arvydas; Watson, Jason P.; Lee, Dicky; Amsden, Charles A.; Ha, Wonill; Carey, Glen P.; Doan, Vincent V.; Moran, Bryan; Lewis, Alan; Mooradian, Aram

    2004-07-01

    We introduce a novel type of cw green laser source, the Protera 532, based on the intracavity frequency doubling of an extended-cavity, surface-emitting diode laser. The distinguishing characteristics of this platform are high compactness and efficiency in a stable, single-longitudinal mode with beam quality M2 < 1.2. The laser design is based on the previously reported NECSEL architecture used for 488nm lasers, and includes several novel features to accommodate different types of nonlinear optical materials. The infrared laser die wavelength is increased from 976nm to 1064nm without compromising performance or reliability. The intracavity frequency doubling to 532nm has been demonstrated with both bulk and periodically poled nonlinear materials, with single-ended cw power outputs of greater than 30 mW.

  20. Anti-Fungal Laser Treatment of Paper: A Model Study with a Laser Wavelength of 532 nm

    NASA Astrophysics Data System (ADS)

    Pilch, E.; Pentzien, S.; Mädebach, H.; Kautek, W.

    Biodeterioration of organic cultural heritage materials is a common problem. Particularly the removal of discoloration caused by fungal pigments is yet an unsolved problem in paper conservation. In the present study, cellulose (cotton and linters) and 16th century paper (rag), were incubated with several fungi types, such as Cladosporium, Epicoccum, Alternaria, Chaetomium, Aspergillus, Trichophyton, and Penicillium on agar for three weeks. Then they were immersed in 70% Ethanol for removal of hyphae and mycelia and deactivation of the remaining conidia. These specimens were laser-treated in a computer-controlled laser cleaning system with a high pulse energy diode pumped Q-switched Nd:YAG laser operating at 532 nm and a pulse duration of 8 ns. Colour differences were determined spectrophotometrically. Best cleaning results were observed with fungi such as Penicillium and Alternaria. Dry laser cleaning generally turned out to be superb over wet bleaching approaches.

  1. KTP 532-nm laser treatment of leg telangiectases resistant to sclerotherapy: follow-up after one year

    NASA Astrophysics Data System (ADS)

    Marangoni, Ovidio

    2002-10-01

    Leg telangiectasias are venous, arterial and arteriovenous capillarya dilatations of the subpapillary dermal plexus, which is directly connected to the deep dermal plexus and indirectly through perforating to the subfascial saphenic and deep venous circulation. These angectasias are almost always indicators of varicose pathology. After accurage history taking and precise diagnosis they should be treated by sclerosis, but only after having verified possible saphenous ostial refluxes which must be eliminated first by surgical means. Laser photosclerosis is aimed at the small (red) residual, resistant and matting vessels. The 532nm lasers are irreplaceable because of the surface delicacy with which they vaporise selectively the telangiectatic and vascular malforming lesions of the face. The aim of this study was to verify the effectiveness of the 532nm on leg angectasiae resistant to sclerotherapy. We used a laser 532nm Combi Zeiss, Jena in 20 cases selected for residual, resistant relapsing and matting leg telangiectasias (0,1 -1mm) on a total of 64 angectatic areas. The areas were cooled down with ice cubes for at least two minutes. 15 - 40 J/sq cm fluences, 10 - 50 msec. pulse durations and 1,5 mm spots were applied. As soon as the vessel blanched, it was cooled down for two further minutes. Four patients had positive results after one session only, twelve patients asked for a second session after 20 days, four patients were retouched for a third time. Follow up examinations were performed after 7-30 days and one year. In all cases the treatment was reported as painless. The immediate erythema was followed by microcrusting in 52 areas, which disappeared in 15-20 days. The one-year follow-up evidenced partial relapses in six patients and complete replases in four on a total of 30 areas (48%). Two patients had hypo-chromic micro-scars in three areas; two patients had four residual dyspigmented areas. Our results suggest that the use of the 532nm laser is justified in

  2. Reconditioning of the trabeculo-descemet's membrane with the 532-nm Nd : YAG (SLT) laser after deep sclerectomy.

    PubMed

    Mansouri, K; Mariani, A; Ravinet, E

    2011-12-01

    The purpose of this study was to evaluate the intraocular pressure (IOP)-lowering effect of modified goniopuncture with the 532-nm Nd : YAG selective laser trabeculoplasty (SLT) laser on eyes after deep sclerectomy with collagen implant (DSCI). This was an interventional cased series. The effects of modified goniopuncture on eyes with insufficient IOP-lowering after DSCI were observed. Goniopuncture was performed using a Q-switched, frequency-doubled 532-nm Nd : YAG laser (SLT-goniopuncture, SLT-G). Outcome measures were amount of IOP-lowering and rapidity of decrease after laser intervention. In all, 10 eyes of 10 patients with a mean age of 71.0±7.7 (SD) years were treated with SLT-G. The mean time of SLT-G after DSCI procedure was 7.1±10.9 months. SLT-G decreased IOP from an average of 16.1±3.4 mm Hg to 14.2±2.8 mm Hg (after 15 min), 13.6±3.9 mm Hg (at 1 day), 12.5±4.1 mm Hg (at 1 month), and 12.6±2.5 (at 6 months) (P<0.0125). There were no complications related to the intervention. Patients in this series achieved an average 22.5% of IOP reduction after SLT-G. The use of the SLT laser appears to be an effective and safe alternative to the traditional Nd : YAG laser for goniopuncture in eyes after DSCI, with potential advantages related to non-perforation of trabeculo-descemet's membrane (TDM).

  3. Changing the optical and electrical properties of a crown dielectric surface using a 532 nm diode laser

    NASA Astrophysics Data System (ADS)

    Khairuzzaman, Md

    The optical response of a dielectric surface to a given laser radiation can be modified when this surface receives a supplemental uniform energy from an external source such as from the uniform electric field set up by a capacitor voltage. A low capacitor voltage across the dielectric can shift the wavelength of the probe laser as perceived by the dielectric surface toward smaller values. This shift is due to an increase of the vibrational frequency of the electric dipoles located on the dielectric surface. The change in the polarization properties of the dielectric surface suggests the usage of this configuration as an optoelectronic switch driven by a relatively small capacitor voltage. Another goal of this work is to observe the coupling between two lasers through a simultaneous interaction on the surface of a crown dielectric material. We analyze the destructive interference pattern between a weak probe laser and a stronger coupling laser in an electromagnetic induced transparency (EIT)-type configuration. We compare our destructive interference pattern obtained with crown glass illuminated with a diode laser of 532 nm, with previous results where a flint dielectric material was illuminated with the same radiation in similar experimental conditions.

  4. Fractional 532-nm Q-switched Nd:YAG laser: One of the safest novel treatment modality to treat café-au-lait macules.

    PubMed

    Won, Kwang Hee; Lee, Ye Jin; Rhee, Do Young; Chang, Sung Eun

    2016-10-01

    Café-au-lait macules (CALMs) are benign epidermal basilar hyperpigmentations that can be found in an isolated form or in association with neurocutaneous syndromes. Frequency-doubled Q-switched neodymium-doped yttrium aluminum garnet laser (532-nm QSNYL) does not penetrate deeply into the skin and is therefore suitable for epidermal pigmented lesion. Fractional photothermolysis (FP) targets only very small areas of the skin, without injuring adjacent areas of healthy, normal skin. Herein, we report a case of CALMs successfully treated with fractional 532-nm QSNYL. By applying FP to 532-nm QSNYL, we could treat CALMs safely with less downtime as compared to conventional laser treatments and expect more energy delivery for each microscopic hole, thereby allowing higher response rate.

  5. Stimulated scattering effects in gold-nanorod-water samples pumped by 532 nm laser pulses

    PubMed Central

    Shi, Jiulin; Wu, Haopeng; Liu, Juan; Li, Shujing; He, Xingdao

    2015-01-01

    Stimulated scattering in gold-nanorod-water samples has been investigated experimentally. The scattering centers are impurity particles rather than the atoms or molecules of conventional homogeneous scattering media. The pump source for exciting stimulated scattering is a pulsed and narrow linewidth second-harmonic Nd: YAG laser, with 532 nm wavelength, ~8 ns pulse duration, and 10 Hz repetition rate. Experimental results indicate that SMBS, SBS and STRS can be generated in gold-nanorod-water samples under appropriate pump and absorption conditions. The incident pump energy has to be larger than a certain threshold value before stimulated scattering can be detected. The absorption coefficient of samples at 532 nm wavelength depends on the one of characteristic absorption bands of gold nanorods located around 530 nm. A critical absorption coefficient can be determined for the transition from SBS to STRS. Also, the spectral-line-broadening effects of STRS have been observed, the line-shape presents a pseudo-Voigt profile due to the random thermal motion of molecules and strong particle collision. PMID:26173804

  6. Stimulated scattering effects in gold-nanorod-water samples pumped by 532 nm laser pulses

    NASA Astrophysics Data System (ADS)

    Shi, Jiulin; Wu, Haopeng; Liu, Juan; Li, Shujing; He, Xingdao

    2015-07-01

    Stimulated scattering in gold-nanorod-water samples has been investigated experimentally. The scattering centers are impurity particles rather than the atoms or molecules of conventional homogeneous scattering media. The pump source for exciting stimulated scattering is a pulsed and narrow linewidth second-harmonic Nd: YAG laser, with 532 nm wavelength, ~8 ns pulse duration, and 10 Hz repetition rate. Experimental results indicate that SMBS, SBS and STRS can be generated in gold-nanorod-water samples under appropriate pump and absorption conditions. The incident pump energy has to be larger than a certain threshold value before stimulated scattering can be detected. The absorption coefficient of samples at 532 nm wavelength depends on the one of characteristic absorption bands of gold nanorods located around 530 nm. A critical absorption coefficient can be determined for the transition from SBS to STRS. Also, the spectral-line-broadening effects of STRS have been observed, the line-shape presents a pseudo-Voigt profile due to the random thermal motion of molecules and strong particle collision.

  7. The study of stability on a laser-diode-pumped high-power high-repetition-rate intracavity frequency-doubled 532-nm laser

    NASA Astrophysics Data System (ADS)

    Zhao, Shi-yong; Yao, Jian-Quan; Xu, De-gang; Zhou, Rui; Zhang, Bai-gang; Zhou, Jia-ning; Wang, Peng

    2005-01-01

    High power laser-diode-pumped 532nm laser sources (including continuous wave and high repetition rate operation) are directly used for precise processing of metals and plastics. Furthermore, high power green laser will be used in some fields such as ocean exploration, laser probe and underwater communication. Recently, we reported a 110W diode-side-pumped Nd:YAG intracavity frequency doubled high stability 532nm laser. In the experiment, we found that the average output power of second harmonic fluctuated acutely with the variety of pumping current. Moreover, the length of arms between the mirrors were very sensitive to this cavity. We consider that one of the reason is the focus length of thermal lens of Nd:YAG rod alter with the variational pumping current, which makes the cavity be unstable. We consider the KTP crystal as a thin lens for its short length. As thermal lensing effect of the Nd:YAG rod is quite severe, so we consider it as thermal lensing medium. By ray matrix methods, we have obtained the stable regions and beam waist radii distribution in the flat-concave cavity. In our experiment, we used a pump head consisting of 80 diode bars with pentagon pump model and employed flat-concave cavity structure in order to achieve high stability output and increase output power. The total cavity length is 505mm. By using an acousto-optic Q-switching with high diffraction loss and the KTP crystal which is type II phase matching, 110 W high stability 532nm laser is achieved. The experimental result is in good agreement with the calculation.

  8. Successful Treatment of Tattoo-Induced Pseudolymphoma with Sequential Ablative Fractional Resurfacing Followed by Q-Switched Nd: YAG 532 nm Laser.

    PubMed

    Tan, Lucinda Siyun; Lucinda, Tan Siyun; Oon, Hazel Hwee; Hazel, Oon Hwee Boon; Lee, Joyce Siong Siong; Joyce, Lee Siong See; Chua, Sze Hon; Hon, Chua Sze

    2013-10-01

    Decorative tattooing has been linked with a range of complications, with pseudolymphoma being unusual and challenging to manage. We report a case of tattoo-induced pseudolymphoma, who failed treatment with potent topical and intralesional steroids. She responded well to sequential treatment with ablative fractional resurfacing (AFR) followed by Q-Switched (QS) Nd:YAG 532 nm laser. Interestingly, we managed to document the clearance of her tattoo pigments after laser treatments on histology and would like to highlight the use of special stains such as the Grocott's Methenamine Silver (GMS) stain as a useful method to assess the presence of tattoo pigment in cases where dense inflammatory infiltrates are present.

  9. Differential Gene Expression in Explanted Human Retinal Pigment Epithelial Cells 24-Hours Post-Exposure to 532 nm, 3.0 ns Pulsed Laser Light and 1064 nm, 170 ps Pulsed Laser Light 12-Hours Post-Exposure: Results Compendium

    DTIC Science & Technology

    2004-06-01

    Laser Light and 1064 nm, 170 ps Pulsed Laser Light 12-hours Post-Exposure: Results Compendium John W. Obringer Martin D. Johnson Laser and Optics...Explanted Human Retinal Pigment Epithelial Cells 12-hours Post-Exposure to 532 nm, 3.0 ns Pulsed Laser Light and 1064 nm, 170 ps Pulsed Laser Lightl2-hours...Explanted Human Retinal Pigment Epithelial USAFA F05611-02-P-0471 Cells 24-Hours Post-Exposure to 532 nm, 3.0 ns Pulsed Laser-Light and 1064nm, 170 ps Pulsed

  10. Laser intervention on trabeculo-Descemet's membrane after resistant viscocanalostomy: Selective 532 nm gonioreconditioning or conventional 1064 nm neodymium-doped yttrium aluminum garnet laser goniopuncture?

    PubMed Central

    Sabur, Huri; Baykara, Mehmet; Can, Basak

    2016-01-01

    Purpose: To compare the results of conventional 1064 nm neodymium-doped yttrium-aluminum garnet laser goniopuncture (Nd:YAG-GP) and selective 532 nm Nd:YAG laser (selective laser trabeculoplasty [SLT]) gonioreconditioning (GR) on trabeculo-Descemet's membrane in eyes resistant to viscocanalostomy surgery. Methods: Thirty-eight eyes of 35 patients who underwent laser procedure after successful viscocanalostomy surgery were included in the study. When postoperative intraocular pressure (IOP) was above the individual target, the eyes were scheduled for laser procedure. Nineteen eyes underwent 532 nm SLT-GR (Group 1), and the remaining 19 eyes underwent conventional 1064 nm Nd:YAG-GP (Group 2). IOPs before and after laser (1 week, 1 month, 3 months, 6 months, 1 year, and last visit), follow-up periods, number of glaucoma medications, and complications were recorded for both groups. Results: Mean times from surgery to laser procedures were 17.3 ± 9.6 months in Group 1 and 13.0 ± 11.4 months in Group 2. Mean IOPs before laser procedures were 21.2 ± 1.7 mmHg in Group 1 and 22.8 ± 1.9 mmHg in Group 2 (P = 0.454). Postlaser IOP measurements of Group 1 were 12.1 ± 3.4 mmHg and 13.8 ± 1.7 mmHg in the 1st week and last visit, respectively; in Group 2, these measurements were 13.6 ± 3.7 mmHg and 14.9 ± 4.8 mmHg, respectively. There were statistically significant differences (P < 0.001) in IOP reduction at all visits in both groups; the results of the two groups were similar (P > 0.05). Mean follow-up was 16.6 ± 6.4 months after SLT-GR and 18.9 ± 11.2 months after Nd:YAG-GP. Conclusions: While conventional Nd:YAG-GP and SLT-GR, a novel procedure, are both effective choices in eyes resistant to viscocanalostomy, there are fewer complications with SLT-GR. SLT-GR can be an alternative to conventional Nd:YAG-GP. PMID:27688277

  11. Spectroscopic study of carbon plasma produced by the first (1064 nm) and second (532 nm) harmonics of Nd:YAG laser

    SciTech Connect

    Hanif, M.; Salik, M.; Arif, F.

    2015-03-15

    In this research work, spectroscopic studies of carbon (C) plasma by using laser-induced breakdown spectroscopy (LIBS) are presented. The plasma was produced by the first (1064 nm) and second (532 nm) harmonics of a Q-switched Nd:YAG (Quantel Brilliant) pulsed laser having a pulse duration of 5 ns and 10-Hz repetition rate, which is capable of delivering 400 mJ at 1064 nm and 200 mJ at 532 nm. The laser beam was focused on the target material (100% carbon) by placing it in air at atmospheric pressure. The experimentally observed line profiles of five neutral carbon (C I) lines at 247.85, 394.22, 396.14, 588.95, and 591.25 nm were used to extract the electron temperature T{sub e} by using the Boltzmann plot method and determine its value, 9880 and 9400 K, respectively, for the fundamental and second harmonics of the laser, whereas the electron density N{sub e} was determined from the Stark broadening profile of neutral carbon line at 247.85 nm. The values of N{sub e} at a distance of 0.05 mm from the target surface for the fundamental-harmonic laser with a pulse energy of 130 mJ and the second-harmonic laser with a pulse energy of 72 mJ are 4.68 × 10{sup 17} and 5.98 × 10{sup 17} cm{sup −3}, respectively. This extracted information on T{sub e} and N{sub e} is useful for the deposition of carbon thin films by using the pulsed laser deposition technique. Moreover, both plasma parameters (T{sub e} and N{sub e}) were also calculated by varying the distance from the target surface along the line of propagation of the plasma plume and also by varying the laser irradiance.

  12. Miniaturized diode laser module emitting green light at 532 nm with a power of more than 900 mW for next-generation holographic displays

    NASA Astrophysics Data System (ADS)

    Hofmann, Julian; Blume, Gunnar; Jedrzejczyk, Daniel; Eppich, Bernd; Feise, David; Kreutzmann, Sabrina; Sahm, Alexander; Paschke, Katrin

    2016-02-01

    We present a micro-integrated laser module based on an amplified diode laser and second harmonic generation which is a promising candidate for a green light source in next-generation 3D holographic displays. The light emitted by the amplified laser has a wavelength of 1064 nm, reaches a power up to 8.2 W and has a long coherence length of >400 m. For second harmonic generation, we tested two geometries of periodically poled lithium niobate crystals in single pass: a bulk crystal and a planar waveguide crystal. With the planar waveguide crystal, we achieve an output power >900 mW and a coherence length >20 m at a wavelength of 532 nm.

  13. [Optical properties of human normal small intestine tissue with theoretical model of optics about biological tissues at Ar+ laser and 532 nm laser and their linearly polarized laser irradiation in vitro].

    PubMed

    Wei, Hua-jiang; Xing, Da; Wu, Guo-yong; Jin, Ying; Gu, Huai-min

    2004-05-01

    A double-integrating-spheres system, basic principle of measuring technology of ray radiation, and optical model of biological tissues were used for the study. Optical properties of human normal small intestine tissue at 476.5, 488, 496.5, 514.5 and 532 nm laser and their linearly polarized laser irradiation were studied. The results of measurement showed that the total attenuation coefficient and scattering coefficient of the tissue at these wavelengths of laser and their linearly polarized laser irradiation increased with decreasing wavelengths. And obviously there was a distinction at 514.5 to 532 nm wavelength between lasers and their linearly polarized laser irradiation. Absorption coefficient of tissue at these wavelengths of laser and their linearly polarized laser irradiation increased with decreasing wavelengths. Absorption coefficient of tissue at 514.5 to 532 nm wavelength of laser was obviously decreasing, which was independent of these wavelengths of laser or their linearly polarized laser irradiation. Mean cosine of scattering of tissue at these wavelengths of laser and their linearly polarized laser irradiation also increased with decreasing wavelengths. But penetration depth of tissue at these wavelengths of laser and their linearly polarized laser irradiation also increased with increasing of wavelengths. Refractive index of tissue between these wavelengths of laser was within 1.38 to 1.48. Absorption coefficient, scattering coefficient, total attenuation coefficient, effective attenuation coefficients of tissue in Kubelka-Munk two-flux model at the same wavelength of laser and their linearly polarized laser irradiation showed no prominent distinction (P>0.01). Absorption coefficient, scattering coefficient, total attenuation coefficient, effective attenuation coefficients of tissue in Kubelka-Munk two-flux model at different wavelength of laser and their linearly polarized laser irradiation showed obvious distinction. Optical properties of tissue

  14. Direct Write Processing of Multi-micron Thickness Copper Nano-particle Paste on Flexible Substrates with 532 nm Laser Wavelength

    NASA Astrophysics Data System (ADS)

    Lopez-Espiricueta, Dunia; Fearon, Eamonn; Edwardson, Stuart; Dearden, Geoffrey

    The Laser Assisted Direct Write (LA-DW) method has been implemented in the development of different markets and material processing, recently also used for creating Printed Circuit Boards (PCB) or electrical circuitry. The process consists in the deposition of metallic nano-particle (NP) inks, which are afterwards cured or sintered by laser irradiation, thus creating conductive pathways; advantages are speed, accuracy and the protection of the heat affected zone (HAZ). This research will study the behaviour of the heat dissipation relatively within the Nano-particle Copper paste after being irradiated with 1064 nm and 532 nm wavelengths, research will be developed on different widths and depths deposited onto flat surfaces such as flexible PET. Comparisons to be made between resistivity results obtained from different wavelengths.

  15. High-quality ultraviolet beam generation in multimode photonic crystal fiber through nondegenerate four-wave mixing at 532 nm.

    PubMed

    Sévigny, Benoit; Cassez, Andy; Vanvincq, Olivier; Quiquempois, Yves; Bouwmans, Géraud

    2015-05-15

    All-fiber ultraviolet (UV) light sources are of great practical interest for a multitude of applications spanned across different sectors, from industrial processes such as nonthermal, high-resolution materials processing, to biomedical applications such as eye surgery, to name a few. However, production of UV light sources with high beam quality has been a problem to this day as the fiber designs required to reach UV wavelengths by four-wave mixing with widely available pumps (i.e., 532 nm) are challenging because of their small size and increased risk of material damage. In this Letter, a specific pumping scheme is presented that allows the conversion of two pump photons in different modes to UV light in the fundamental mode and the corresponding idler in a higher order mode. The process has also been shown to work experimentally, and UV light at 390.5 nm in the fundamental mode was successfully generated.

  16. Differential Gene Expression in Explanted Human Retinal Pigment Epithelial Cells 12-Hours Post-Exposure to 532 nm, 120 ps Pulsed Laser Light

    DTIC Science & Technology

    2004-04-01

    years or younger, either sex, with no mitigating ocular or retinal pathology such as glaucoma, diabetic retinopathy, retinitis pigmentosa , etc. Donor: The...USAFA TR 2004-01 Differential Gene Expression in Explanted Human Retinal Pigment Epithelial Cells 12-hours Post-Exposure to 532 nm, 120 ps Pulsed...TR 2004-01 This article, "Differential Gene Expression in Explanted Human Retinal Pigment Epithelial Cells 12-hours Post-Exposure to 532 nm, 120 ps

  17. Investigation of N2O Production from 266 and 532 nm Laser Flash Photolysis of O3/N2/O2 Mixtures

    NASA Technical Reports Server (NTRS)

    Estupinan, E. G.; Nicovich, J. M.; Li, J.; Cunnold, D. M.; Wine, P. H.

    2002-01-01

    Tunable diode laser absorption spectroscopy has been employed to measure the amount of N2O produced from laser flash photolysis of O3/N2/O2 mixtures at 266 and 532 nm. In the 532 nm photolysis experiments very little N2O is observed, thus allowing an upper limit yield of 7 x 10(exp -8) to be established for the process O3 + N2 yield N2O + O2, where O3 is nascent O3 that is newly formed via O(3P(sub J)) + O2 recombination (with vibrational excitation near the dissociation energy of O3). The measured upper limit yield is a factor of approx. 600 smaller than a previous literature value and is approximately a factor of 10 below the threshold for atmospheric importance. In the 266 nm photolysis experiments, significant N2O production is observed and the N2O quantum yield is found to increase linearly with pressure over the range 100 - 900 Torr in air bath gas. The source of N2O in the 266 nm photolysis experiments is believed to be the addition reaction O(1D(sub 2)) + N2 + M yields (k(sub sigma)) N2O + M, although reaction of (very short-lived) electronically excited O3 with N2 cannot be ruled out by the available data. Assuming that all observed N2O comes from the O(1D(sub 2)) + N2 + M reaction, the following expression describes the temperature dependence of k(sub sigma) (in its third-order low-pressure limit) that is consistent with the N2O yield data: k(sub sigma) = (2.8 +/- 0.1) x 10(exp -36)(T/300)(sup -(0-88+0.36)) cm(sup 6) molecule(sup -2)/s, where the uncertainties are 2(sigma) and represent precision only. The accuracy of the reported rate coefficients at the 95% confidence level is estimated to be 30 - 40% depending on the temperature. Model calculations suggest that gas phase processes initiated by ozone absorption of a UV photon represent about 1.4% of the currently estimated global source strength of atmospheric N2O. However, these processes could account for a significant fraction of the oxygen mass-independent enrichment observed in atmospheric N2O, and

  18. Magnetorheological finishing (MRF) of potassium dihydrogen phosphate (KDP) crystals: nonaqueous fluids development, optical finish, and laser damage performance at 1064 nm and 532 nm

    SciTech Connect

    Menapace, J A; Ehrmann, P R; Bickel, R C

    2009-11-05

    Over the past year we have been working on specialized MR fluids for polishing KDP crystals. KDP is an extremely difficult material to conventionally polish due to its water solubility, low hardness, and temperature sensitivity. Today, KDP crystals are finished using single-point diamond turning (SPDT) tools and nonaqueous lubricants/coolants. KDP optics fabricated using SPDT, however, are limited to surface corrections due to tool/method characteristics with surface quality driven by microroughness from machine pitch, speed, force, and diamond tool character. MRF polishing offers a means to circumvent many of these issues since it is deterministic which makes the technique practical for surface and transmitted wavefront correction, is low force, and is temperature independent. What is lacking is a usable nonaqueous MR fluid that is chemically and physically compatible with KDP which can be used for polishing and subsequently cleaned from the optical surface. In this study, we will present the fluid parameters important in the design and development of nonaqueous MR fluid formulations capable of polishing KDP and how these parameters affect MRF polishing. We will also discuss requirements peculiar to successful KDP polishing and how they affect optical figure/finish and laser damage performance at 1064 nm and 532 nm.

  19. Nonlinear optical response of nanocomposites based on KDP single crystal with incorporated Al2O3*nH2O nanofibriles under CW and pulsed laser irradiation at 532 nm

    NASA Astrophysics Data System (ADS)

    Popov, A. S.; Uklein, A. V.; Multian, V. V.; Dantec, R. Le; Kostenyukova, E. I.; Bezkrovnaya, O. N.; Pritula, I. M.; Gayvoronsky, V. Ya.

    2016-11-01

    Optical properties and nonlinear optical response due to the CW and pulsed laser radiation self-action at 532 nm were studied in composites based on KDP single crystals with incorporated nanofibriles of nanostructured oxyhydroxide of aluminum (NOA). It was shown a high optical quality and structural homogeneity of nanocomposites KDP:NOA by the transmittance spectra, elastic optical scattering and XRD analysis. It was observed manifestation of the second harmonic generation efficiency enhancement in the KDP:NOA versus the nominally pure KDP (λ=1064 nm, τ=1 ns) that is correlated with efficient refractive index self-modulation Δn ∼10-4 (λ=532 nm, τ=30 ps). In the pyramidal and prismatic growth sectors of the nominally pure KDP crystal it was shown opposite signs of the photoinduced variations both of the refractive index and of the optical absorption/bleaching due to resonant excitation of the native defects at 532 nm. It should be considered for the wide-aperture laser frequency KDP family based convertors fabrication.

  20. Measurement of optical absorption coefficient of bio-tissue at 532nm wavelength

    NASA Astrophysics Data System (ADS)

    Huang, Chuyun; Li, Zhengjia; Yao, Yucheng; He, Yanyan

    2007-05-01

    Laser technology has succeeded in medical application. High power 532nm laser has applied in prostate ablation and other clinic application. To understand optical property of bio-tissue at 532nm wavelength, a method of monitoring surface temperature was used to measure absorption coefficient of gall-stone, porcine liver and canine prostate. The absorption coefficient of gall-stone is about 62cm -1 at 532nm wavelength, and those of porcine liver and canine prostate are about 13cm -1 and 5.4cm -1, respectively. These results help to understand the optical property of bio-tissue and offer theoretic reference for optical dosimetry in clinic application.

  1. Gas-Filled Hollow Core Fiber Lasers Based on Population Inversion

    DTIC Science & Technology

    2013-12-05

    iodine (I2) and pumped at ~ 532 nm was studied. Toward improved fiber transmission measurements, novel thulium /holmium fiber laser near 2 microns...transmission, we have demonstrated a novel thulium /holmium fiber laser near 2 microns. Abstract (short): Hollow-core Optical Fiber Gas LASer...measurements, novel thulium /holmium fiber laser near 2 microns were created. H. Schlossberg Hollow-Core Optical Fiber Gas Lasers K. Corwin et al

  2. Tunable Solid-Etalon Filter for the ICESat/GLAS 532 nm Channel Lidar Receiver

    NASA Technical Reports Server (NTRS)

    Krainak, Michael A.; Stephen, Mark A.; Martino, Anthony J.; Lunt, David L.

    2003-01-01

    The Geoscience Laser Altimeter System (GLAS) was launched into Earth orbit on board the Ice, Cloud and land Elevation Satellite (ICESat) on January 12, 2003. GLAS is a laser altimeter designed to measure ice-sheet topography and associated temporal changes, as well as cloud and atmospheric properties. Each (of the three identical) GLAS lasers is a diode pumped, Q-switched Nd:YAG laser with energy levels of 75 mJ (1064 nm) and 35 mJ (532 nm). The infrared pulse is used for both surface altimetry and atmospheric measurements while the green pulse is used primarily for atmospheric measurements. The receiver uses a 1 meter diameter telescope. We report on the tunable solid-etalon filter used in the ICESat/GLAS 532 nm channel lidar receiver.

  3. Investigation of wavelength-dependent tissue ablation: visible (λ=532 nm) vs IR (λ=2.01 μm)

    NASA Astrophysics Data System (ADS)

    Kang, Hyun Wook; Peng, Yihlih Steven

    2010-02-01

    Laser prostatectomy with various lasers has been shown to be effective in the treatment of benign prostate hyperplasia. However, the impact of laser parameters on tissue ablation is still in question. The aim of this study is to experimentally characterize laser-tissue interactions in terms of wavelength by comparing visible (λ= 532 nm) and infrared (λ= 2.01 μm) spectra. Porcine kidney tissue was used as it has thermal properties and glandular structure similar to human prostatic tissue. Q-switched 532 nm (GreenLightTM HPS) and continuous-wave (CW) 2.01 μm (custom-made Tm:YAG) lasers were employed to remove soft tissue under various settings (power, working distance, and treatment speed). For both laser systems, ablation rate increased with power and was maximized at 4 mm/s. The 532 nm laser generated approximately 30% (p<0.005) higher ablation efficiency than the IR laser. A comparable ablation depth was found between the two wavelengths, but the 532nm laser generated relatively wider (up to 30%; p<0.005) craters. Owing to constant heating due the CW mode, the IR laser induced 20% thicker coagulation depth than the 532 nm (0.94 vs. 0.8 mm at 100 W; p<0.005). Histology also confirmed coagulation depth in response to each wavelength. Due to light absorption in aqueous environment, the IR laser exhibited a dramatic decrease in power transmission and ablation volume with increasing working distance whereas the 532 nm laser maintained relatively constant features. In conclusion, the characteristics of tissue ablation were contingent upon the applied wavelengths due to optical properties and laser parameters.

  4. Nonlinear optical effects related to saturable and reverse saturable absorption by subphthalocyanines at 532 nm.

    PubMed

    Dini, Danilo; Vagin, Sergej; Hanack, Michael; Amendola, Vincenzo; Meneghetti, Moreno

    2005-08-14

    It is found that both effects of saturable absorption and reverse saturable absorption are obtained with a solution of subphthalocyanine at 532 nm depending on the intensity of 9 ns laser pulses; saturable absorption occurs at lower intensity levels whereas the reverse effect prevails at higher levels; contrary to expectations, subphthalocyanines can behave as reverse saturable absorbers at 532 nm, despite the high linear absorption at this wavelength; data have been fitted with a five-level model which considers three consecutive electronic transitions with absorption cross-section values of 1.4 x 10(-16), 1.0 x 10(-16) and 40 x 10(-16) cm(2), respectively.

  5. Optical characterization, visual function, and pursuit tracking performance using a 532 nm reflecting holographic filter

    NASA Astrophysics Data System (ADS)

    Stamper, D. A.; Lund, D. J.; Esgandarian, G. E.; Levine, R. R.; Stuck, B. E.; Beatrice, E. S.

    1982-09-01

    A series of tests, involving the optical characterization, visual function, and pursuit tracking, were conducted to evaluate a newly developed laser ocular protective filter. The filter, a reflecting holograph, was designed to provide narrow hand protection against the doubled neodymium (532 nm) wavelength. Optical characterization of the material was determined by measuring broad band radiant transmission through the filter, photopic luminous transmission, optical density (OD) at 532 nm, variation of OD as a function of position, and the relationship between OD and the angle of incidence. Tests of visual function included the Snellen Acuity Chart, Arden Contrast Sensitivity Test, and Farnsworth Munsell 100 Hue Test. Pursuit tracking was evaluated using the BLASER tracking simulator which utilizes a terrain board model with moving targets and a viscous-damped tracking device. The optical characterization test results showed that at the 530 nm rejection band the holographic filter at the 50% transmission point had a band width of 30 nm and a 3.7 OD was achieved over much of the filter. The visual functions test indicated that the subjects had difficulty in color discrimination involving blue and green. No systematic differences were found on the contrast sensitivity test or Snellen Acuity Test.

  6. Nanosecond laser damage of optical multimode fibers

    NASA Astrophysics Data System (ADS)

    Mann, Guido; Krüger, Jörg

    2016-07-01

    For pulse laser materials processing often optical step index and gradient index multimode fibers with core diameters ranging from 100 to 600 μm are used. The design of a high power fiber transmission system must take into account limitations resulting from both surface and volume damage effects. Especially, breakdown at the fiber end faces and selffocusing in the fiber volume critically influence the fiber performance. At least operation charts are desirable to select the appropriate fiber type for given laser parameters. In industry-relevant studies the influence of fiber core diameter and end face preparation on laser-induced (surface) damage thresholds (LIDT) was investigated for frequently used all-silica fiber types (manufacturer LEONI). Experiments on preform material (initial fiber material) and compact specimens (models of the cladding and coating material) accompanied the tests performed in accordance with the relevant LIDT standards ISO 21254-1 and ISO 21254-2 for 1-on-1 and S-on-1 irradiation conditions, respectively. The relation beam diameter vs. LIDT was investigated for fused silica fibers. Additionally, laser-induced (bulk) damage thresholds of fused silica preform material F300 (manufacturer Heraeus) in dependence on external mechanical stress simulating fiber bending were measured. All experiments were performed with 10-ns laser pulses at 1064 and 532 nm wavelength with a Gaussian beam profile.

  7. Measurements of Stokes parameters of materials at 1064-nm and 532-nm wavelengths

    NASA Astrophysics Data System (ADS)

    Tan, Songxin; Narayanan, Ram M.; Kalshoven, James E., Jr.

    2001-09-01

    Laser radar systems have found wide applications in the field of remote sensing. Reflectance as well as polarization features are used together for applications ranging from environmental monitoring to target classification. The Stokes parameters are ideal quantities for characterizing the above features because they provide useful information on both light intensity and polarization state. The University of Nebraska is currently refurbishing an airborne multi-wavelength laser radar system based on the NASA Goddard Space Flight Center (GSFC) developed Airborne Laser Polarimetric Sensor (ALPS). The system uses a Nd:YAG laser operating at wavelengths of 1064 nm and 532 nm, and contains four channels at each wavelength to measure the polarization states. This system was used to measure the Stokes parameters of backscattered laser light from different materials. These included canvas tarp, white paper, plywood, concrete, aluminum plate and anodized aluminum plate. The data provide an understanding of the polarized scattering properties of various materials, and are expected to be useful in developing target discrimination algorithms.

  8. Nonlinear bleaching, absorption, and scattering of 532-nm-irradiated plasmonic nanoparticles

    SciTech Connect

    Liberman, V.; Sworin, M.; Kingsborough, R. P.; Geurtsen, G. P.; Rothschild, M.

    2013-02-07

    Single-pulse irradiation of Au and Ag suspensions of nanospheres and nanodisks with 532-nm 4-ns pulses has identified complex optical nonlinearities while minimizing material damage. For all materials tested, we observe competition between saturable absorption (SA) and reverse SA (RSA), with RSA behavior dominating for intensities above {approx}50 MW/cm{sup 2}. Due to reduced laser damage in single-pulse experiments, the observed intrinsic nonlinear absorption coefficients are the highest reported to date for Au nanoparticles. We find size dependence to the nonlinear absorption enhancement for Au nanoparticles, peaking in magnitude for 80-nm nanospheres and falling off at larger sizes. The nonlinear absorption coefficients for Au and Ag spheres are comparable in magnitude. On the other hand, the nonlinear absorption for Ag disks, when corrected for volume fraction, is several times higher. These trends in nonlinear absorption are correlated to local electric field enhancement through quasi-static mean-field theory. Through variable size aperture measurements, we also separate nonlinear scattering from nonlinear absorption. For all materials tested, we find that nonlinear scattering is highly directional and that its magnitude is comparable to that of nonlinear absorption. These results indicate methods to improve the efficacy of plasmonic nanoparticles as optical limiters in pulsed laser systems.

  9. Revised Calibration Strategy for the CALIOP 532 nm Channel. Part II; Daytime

    NASA Technical Reports Server (NTRS)

    Powell, Kathleen A.; Vaughan, Mark A.; Kuehn, Ralph; Hunt, William H.; Pee, Kam-Pui

    2008-01-01

    The CALIPSO lidar (CALIOP) makes backscatter measurements at 532 nm and 1064 nm and linear depolarization ratios at 532 nm. Accurate calibration of the backscatter measurements is essential in the retrieval of optical properties. An assessment of the nighttime 532 nm parallel channel calibration showed that the calibration strategy used for the initial release (Release 1) of the CALIOP lidar level 1B data was acceptable. In general, the nighttime calibration coefficients are relatively constant over the darkest segment of the orbit, but then change rapidly over a short period as the satellite enters sunlight. The daytime 532 nm parallel channel calibration scheme implemented in Release 1 derived the daytime calibration coefficients from the previous nighttime coefficients. A subsequent review of the daytime 532 nm parallel channel calibration revealed that the daytime calibration coefficients do not remain constant, but vary considerably over the course of the orbit, due to thermally-induced misalignment of the transmitter and receiver. A correction to the daytime calibration scheme is applied in Release 2 of the data. Results of both nighttime and daytime calibration performance are presented in this paper.

  10. Assessment of the CALIPSO Lidar 532 nm Attenuated Backscatter Calibration Using the NASA LaRC Airborne High Spectral Resolution Lidar

    NASA Technical Reports Server (NTRS)

    Rogers, Raymond R.; Hostetler, Chris A.; Hair, Johnathan W.; Ferrare, Richard A.; Liu, Zhaoyan; Obland, Michael D.; Harper, David B.; Cook, Anthony L.; Powell, Kathleen A.; Vaughan, Mark A.; Winker, David M.

    2011-01-01

    The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) spacecraft has provided global, high-resolution vertical profiles of aerosols and clouds since it became operational on 13 June 2006. On 14 June 2006, the NASA Langley Research Center (LaRC) High Spectral Resolution Lidar (HSRL) was deployed aboard the NASA Langley B-200 aircraft for the first of a series of 86 underflights of the CALIPSO satellite to provide validation measurements for the CALIOP data products. To better assess the range of conditions under which CALIOP data products are produced, these validation flights were conducted under both daytime and nighttime lighting conditions, in multiple seasons, and over a large range of latitudes and aerosol and cloud conditions. This paper presents a quantitative assessment of the CALIOP 532 nm calibration (through the 532 nm total attenuated backscatter) using an internally calibrated airborne HSRL underflight data and is the most extensive study of CALIOP 532 nm calibration. Results show that average HSRL and CALIOP 532 nm total attenuated backscatter agree on average within 2.7% +/- 2.1% (CALIOP lower) at night and within 2.9 % +/- 3.9% (CALIOP lower) during the day., demonstrating the accuracy of the CALIOP 532 nm calibration algorithms. Additionally, comparisons with HSRL show consistency of the CALIOP calibration before and after the laser switch in 2009 as well as improvements in the daytime version 3 calibration scheme compared with the version 2 calibration scheme. Potential systematic uncertainties in the methodology relevant to validating satellite lidar measurements with an airborne lidar system are discussed and found to be less than 3.7% for this validation effort with HSRL. Results from this study are also compared to those from prior assessments of CALIOP calibration and attenuated backscatter.

  11. Efficient green-light generation by frequency doubling of a picosecond all-fiber ytterbium-doped fiber amplifier in PPKTP waveguide inscribed by femtosecond laser direct writing.

    PubMed

    Tu, Chenghou; Huang, Zhangchao; Lou, Kai; Liu, Hongjun; Wang, Yishan; Li, Yongnan; Lu, Fuyun; Wang, Hui-Tian

    2010-11-22

    We have demonstrated an ultrashort, compact green light radiation by frequency doubling of an all-fiber ytterbium-doped fiber laser source in a PPKTP waveguide fabricated by femtosecond laser pulses. Using the fabricated PPKTP waveguide crystal containing a 10 mm single grating with a period of 9.0 μm, we generate 310 mW of picosecond radiation at 532 nm for a fundamental power of 1.6W, corresponding to a conversion efficiency of 19.3%. The temperature tuning range of 8°C is achieved for a fixed fundamental wavelength of 1064 nm, the FWHM of the wavelength tuning curve is 4.2 nm at room temperature. The generated ultrashort pulses at 532 nm are of great importance and have comprehensive applications in photobiology research and high-resolution spectroscopy.

  12. Compact, 17W average power, 100kW peak power, nanosecond fiber laser system

    NASA Astrophysics Data System (ADS)

    Saracco, Matthieu J.; Logan, David; Green, Jared; Balsley, David; Nelson, Mike; Small, Jay; Mettlen, Scott; Lowder, Tyson L.; McComb, Timothy S.; Kutscha, Tim; Burkholder, Gary; Smith, Michael R.; Kliner, Dahv A. V.; Randall, Matthew; Fanning, Geoff; Bell, Jake

    2013-03-01

    We demonstrate a robust, compact, low-cost, pulsed, linearly polarized, 1064 nm, Yb:fiber laser system capable of generating ~100 kW peak power pulses and >17 W average power at repetition rates of 80 - 285 kHz. The system employs a configurable microchip seed laser that provides nanosecond (~1.0 - 1.5 ns) pulse durations. The seed pulses are amplified in an all-fiber, polarization maintaining, large mode area (LMA) fiber amplifier optimized for high peak power operation. The LMA Yb:fiber amplifier enables near diffraction limited beam quality at 100 kW peak power. The seed laser, fiber amplifier, and beam delivery optics are packaged into an air-cooled laser head of 152×330×87 mm3 with pump power provided from a separate air-cooled laser controller. Due to the high peak power, high beam quality, spectral purity, and linearly polarized nature of the output beam, the laser is readily frequency doubled to 532 nm. Average 532 nm powers up to 7 W and peak powers exceeding 40 kW have been demonstrated. Potential for scaling to higher peak and average powers in both the green and infrared (IR) will be discussed. This laser system has been field tested and demonstrated in numerous materials processing applications in both the IR and green, including scribing and marking. We discuss recent results that demonstrate success in processing a diverse array of representative industrial samples.

  13. Seagrass Identification Using High-Resolution 532nm Bathymetric LiDAR and Hyperspectral Imagery

    NASA Astrophysics Data System (ADS)

    Pan, Z.; Prasad, S.; Starek, M. J.; Fernandez Diaz, J. C.; Glennie, C. L.; Carter, W. E.; Shrestha, R. L.; Singhania, A.; Gibeaut, J. C.

    2013-12-01

    Seagrass provides vital habitat for marine fisheries and is a key indicator species of coastal ecosystem vitality. Monitoring seagrass is therefore an important environmental initiative, but measuring details of seagrass distribution over large areas via remote sensing has proved challenging. Developments in airborne bathymetric light detection and ranging (LiDAR) provide great potential in this regard. Traditional bathymetric LiDAR systems have been limited in their ability to map within the shallow water zone (< 1 m) where seagrass is typically present due to limitations in receiver response and laser pulse length. Emergent short-pulse width bathymetric LiDAR sensors and waveform processing algorithms enable depth measurements in shallow water environments previously inaccessible. This 3D information of the benthic layer can be applied to detect seagrass and characterize its distribution. Researchers with the National Center for Airborne Laser Mapping (NCALM) at the University of Houston (UH) and the Coastal and Marine Geospatial Sciences Lab (CMGL) of the Harte Research Institute at Texas A&M University-Corpus Christi conducted a coordinated airborne and boat-based survey of the Redfish Bay State Scientific Area as part of a collaborative study to investigate the capabilities of bathymetric LiDAR and hyperspectral imaging for seagrass mapping. Redfish Bay, located along the middle Texas coast of the Gulf of Mexico, is a state scientific area designated for the purpose of protecting and studying native seagrasses. Redfish Bay is part of the broader Coastal Bend Bays estuary system recognized by the US Environmental Protection Agency (EPA) as a national estuary of significance. For this survey, UH acquired high-resolution discrete-return and full-waveform bathymetric data using their Optech Aquarius 532 nm green LiDAR. In a separate flight, UH collected 2 sets of hyperspectral imaging data (1.2-m pixel resolution and 72 bands, and 0.6m pixel resolution and 36

  14. High power, picosecond green laser based on a frequency-doubled, all-fiber, narrow-bandwidth, linearly polarized, Yb-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Tian, Wenyan; Isyanova, Yelena; Stegeman, Robert; Huang, Ye; Chieffo, Logan R.; Moulton, Peter F.

    2016-03-01

    We report on the development of an all-fiber, 68-kW-peak-power, 16-ps-pulse-width, narrow-bandwidth, linearly polarized, 1064-nm fiber laser suitable for high-power, picosecond-pulse-width, green-light generation. Our 1064-nm fiber laser delivered an average power of up to 110 W at a repetition of 100- MHz in a narrow bandwidth, with minimal nonlinear distortion. We developed a high-power, picosecond green source at 532 nm through use of single-pass frequency-doubling of our 1064-nm fiber laser in lithium triborate (LBO). Using a 15-mm long LBO crystal, we have generated 30 W of average power in the second harmonic with 73-W of fundamental average power, for a conversion efficiency of 41%.

  15. Thermal and damage data from multiple microsecond pulse trains at 532nm in an in vitro retinal model

    NASA Astrophysics Data System (ADS)

    Denton, Michael L.; Tijerina, Amanda J.; Hoffman, Aaron; Clark, Clifton D.; Noojin, Gary D.; Rickman, John M.; Castellanos, Cherry C.; Shingledecker, Aurora D.; Boukhris, Sarah J.; Thomas, Robert J.; Rockwell, Benjamin A.

    2014-03-01

    An artificially pigmented retinal pigment epithelial (RPE) cell model was used to study the damage rates for exposure to 1, 10, 100, and 1,000 230-μs laser pulses at 532 nm, at two different concentrations of melanosome particles (MPs) per cell. Multiple pulses were delivered at pulse repetition rates of 50 and 99 pulses per second. Standard fluorescence viability indicator dyes and the method of microthermography were used to assess damage and thermal responses, respectively. Although frame rate during microthermography was more than five times slower than the duration of laser pulses, thermal information was useful in refining the BTEC computational model for simulating high-resolution thermal responses by the pigmented cells. When we temporally sampled the thermal model output at a rate similar to our microthermography, the resulting thermal profiles for multiple pulses resembled the thermal experimental profiles. Complementary to the thermal simulations, our computer-generated thresholds were in good agreement with the in vitro data. Findings are examined within the context of common exposure limit definitions in the national and international laser safety standards.

  16. Resolved Sideband Spectroscopy and Cooling of Strontium in a 532-nm Optical Lattice

    NASA Astrophysics Data System (ADS)

    Aman, James; Hill, Joshua; Killian, T. C.

    2016-05-01

    Resolved sideband cooling is a powerful and well established technique for driving ultracold atoms in optical lattices to the motional ground state of individual lattice sites. Here we present spectroscopy of the narrow 5s21S0 --> 5 s 5 p3P1 transition for neutral strontium-84 in a 532nm optical lattice. Resolved red- and blue-detuned sidebands are observed corresponding to changes in the motional state in the lattice sites. Driving the red sideband, we demonstrate cooling into the ground state, which increases the initial phase-space density before forced evaporative cooling. This is a promising technique for improving the production of strontium quantum degenerate gases. Research supported by the Robert A, Welch Foundation under Grant No. C-1844.

  17. Ultra low-loss hypocycloid-core Kagome hollow-core photonic crystal fiber for green spectral-range applications.

    PubMed

    Debord, B; Alharbi, M; Benoît, A; Ghosh, D; Dontabactouny, M; Vincetti, L; Blondy, J-M; Gérôme, F; Benabid, F

    2014-11-01

    We report on the development of a hypocycloidal-core Kagome hollow-core photonic crystal fiber guiding, with low transmission loss in the 450-650 nm visible spectral range. Transmission loss records have been achieved with 70  dB/km at 600 nm, and 130  dB/km at 532 nm. As a demonstration of the fiber potential applications, we report on a compact 600 THz wide Raman comb generator, centered around 532 nm, and on a 10 W average power frequency-doubled Yb-fiber picosecond laser beam delivery, along with its use for organic material laser micro-processing.

  18. Diode Pumped Fiber Laser

    DTIC Science & Technology

    1983-07-01

    acousto - optic beam deflector for greater absolute accuracy. The detection system was also upgraded to a response time of • 1 usec. The... 2 C. SUMMARY OF RESULTS.., 3 D . GENERAL PLAN 5 II. Nd:YAG FIBER PREPARATION 7 A. FIBER GROWTH 7 B. PHYSICAL PROPERTIES OF Nd:YAG...A. INTRODUCTION 25 B. GENERAL FORMALISM 26 C. FREE-SPACE LASERS 35 D . FIBER LASERS 43 1. Fiber Laser Configuration 43 2 . F

  19. Raman fiber lasers

    NASA Astrophysics Data System (ADS)

    Supradeepa, V. R.; Feng, Yan; Nicholson, Jeffrey W.

    2017-02-01

    High-power fiber lasers have seen tremendous development in the last decade, with output powers exceeding multiple kilowatts from a single fiber. Ytterbium has been at the forefront as the primary rare-earth-doped gain medium owing to its inherent material advantages. However, for this reason, the lasers are largely confined to the narrow emission wavelength region of ytterbium. Power scaling at other wavelength regions has lagged significantly, and a large number of applications rely upon the diversity of emission wavelengths. Currently, Raman fiber lasers are the only known wavelength agile, scalable, high-power fiber laser technology that can span the wavelength spectrum. In this review, we address the technology of Raman fiber lasers, specifically focused on the most recent developments. We will also discuss several applications of Raman fiber lasers in laser pumping, frequency conversion, optical communications and biology.

  20. Continuous-wave 532 nm pumped MgO:PPLN optical parametric oscillator with external power regulation and spatial mode filtering.

    PubMed

    Lee, Dong-Hoon; Kim, Seung Kwan; Park, Seung-Nam; Park, Hee Su; Lee, Jae Yong; Choi, Sang-Kyung

    2009-01-01

    We report a continuous-wave (CW) optical parametric oscillator (OPO) based on a MgO-doped periodically poled LiNbO(3) (MgO:PPLN) crystal. The 532 nm pump generates coherent radiation that is tunable from 800 to 920 nm for the signal and from 1250 to 1580 nm for the idler, respectively. The OPO output power exhibits a slowly varying instability that we attribute to a thermal effect induced by the pump. This instability is truncated by means of a low-pass servo that includes a single-mode fiber that filters the beam into a single spatial mode. The resulting output characteristics are promising for radiometric applications in the near infrared including most fiber-optic communication bands.

  1. Fiber optic laser rod

    DOEpatents

    Erickson, G.F.

    1988-04-13

    A laser rod is formed from a plurality of optical fibers, each forming an individual laser. Synchronization of the individual fiber lasers is obtained by evanescent wave coupling between adjacent optical fiber cores. The fiber cores are dye-doped and spaced at a distance appropriate for evanescent wave coupling at the wavelength of the selected dye. An interstitial material having an index of refraction lower than that of the fiber core provides the optical isolation for effective lasing action while maintaining the cores at the appropriate coupling distance. 2 figs.

  2. Comparative Study of Remote Fiber Laser and Water-Jet Guided Laser Cutting of Thin Metal Sheets

    NASA Astrophysics Data System (ADS)

    Hock, Klaus; Adelmann, Benedikt; Hellmann, Ralf

    This article presents a comparison between remote laser cutting with a fiber laser and water-jet guided laser cutting using a 532 nm solid state laser. Complex contours are processed in stainless steel and brass sheets (thickness ≤ 100 μm), respectively. Results for achievable quality and productivity as well as possible applications for both systems are shown and discussed. We sustained dross free cuts with almost no heat affected zone and small kerf width for the water-jet guided process, whereas small dross, notable heat affected zone and varying kerf width where observed for remote cutting. However, process times for the water-jet guided process where considerably higher than those for remote cutting.

  3. Spectral diagnostics of a vapor-plasma plume produced during welding with a high-power ytterbium fiber laser

    NASA Astrophysics Data System (ADS)

    Uspenskiy, S. A.; Shcheglov, P. Yu.; Petrovskiy, V. N.; Gumenyuk, A. V.; Rethmeier, M.

    2013-07-01

    We have conducted spectroscopic studies of the welding plasma formed in the process of welding with an ytterbium fiber laser delivering output power of up to 20 kW. The influence of shielding gases (Ar, He) on different parts of the welding plume is investigated. The absorption coefficient of the laser radiation by the welding-plume plasma is estimated. Scattering of 532-nm probe radiation from particles of the condensed metal vapor within the caustic of a high-power fiber laser beam is measured. Based on the obtained results, conclusions are made on the influence of the plasma formation and metal vapor condensation on the radiation of the high-power fiber laser and the stability of the welding process.

  4. Evaluation of CALIOP 532-nm Aerosol Optical Depth Over Opaque Water Clouds

    NASA Technical Reports Server (NTRS)

    Liu, Z.; Winker, D.; Omar, A.; Vaughan, M.; Kar, J.; Trepte, C.; Hu, Y.; Schuster, G.

    2015-01-01

    With its height-resolved measurements and near global coverage, the CALIOP lidar onboard the CALIPSO satellite offers a new capability for aerosol retrievals in cloudy skies. Validation of these retrievals is difficult, however, as independent, collocated and co-temporal data sets are generally not available. In this paper, we evaluate CALIOP aerosol products above opaque water clouds by applying multiple retrieval techniques to CALIOP Level 1 profile data and comparing the results. This approach allows us to both characterize the accuracy of the CALIOP above-cloud aerosol optical depth (AOD) and develop an error budget that quantifies the relative contributions of different error sources. We focus on two spatial domains: the African dust transport pathway over the tropical North Atlantic and the African smoke transport pathway over the southeastern Atlantic. Six years of CALIOP observations (2007-2012) from the northern hemisphere summer and early fall are analyzed. The analysis is limited to cases where aerosol layers are located above opaque water clouds so that a constrained retrieval technique can be used to directly retrieve 532 nm aerosol optical depth and lidar ratio. For the moderately dense Sahara dust layers detected in the CALIOP data used in this study, the mean/median values of the lidar ratios derived from a constrained opaque water cloud (OWC) technique are 45.1/44.4 +/- 8.8 sr, which are somewhat larger than the value of 40 +/- 20 sr used in the CALIOP Level 2 (L2) data products. Comparisons of CALIOP L2 AOD with the OWC-retrieved AOD reveal that for nighttime conditions the L2 AOD in the dust region is underestimated on average by approx. 26% (0.183 vs. 0.247). Examination of the error sources indicates that errors in the L2 dust AOD are primarily due to using a lidar ratio that is somewhat too small. The mean/median lidar ratio retrieved for smoke is 70.8/70.4 +/- 16.2 sr, which is consistent with the modeled value of 70 +/- 28 sr used in the

  5. Tunable random fiber laser

    SciTech Connect

    Babin, S. A.; Podivilov, E. V.; El-Taher, A. E.; Harper, P.; Turitsyn, S. K.

    2011-08-15

    An optical fiber is treated as a natural one-dimensional random system where lasing is possible due to a combination of Rayleigh scattering by refractive index inhomogeneities and distributed amplification through the Raman effect. We present such a random fiber laser that is tunable over a broad wavelength range with uniquely flat output power and high efficiency, which outperforms traditional lasers of the same category. Outstanding characteristics defined by deep underlying physics and the simplicity of the scheme make the demonstrated laser a very attractive light source both for fundamental science and practical applications.

  6. Differential Absorption Measurements of Atmospheric Water Vapor with a Coherent Lidar at 2050.532 nm

    NASA Technical Reports Server (NTRS)

    Koch, Grady J.; Dharamsi, Amin; Davis, Richard E.; Petros, Mulugeta; McCarthy, John C.

    1999-01-01

    Wind and water vapor are two major factors driving the Earth's atmospheric circulation, and direct measurement of these factors is needed for better understanding of basic atmospheric science, weather forecasting, and climate studies. Coherent lidar has proved to be a valuable tool for Doppler profiling of wind fields, and differential absorption lidar (DIAL) has shown its effectiveness in profiling water vapor. These two lidar techniques are generally considered distinctly different, but this paper explores an experimental combination of the Doppler and DIAL techniques for measuring both wind and water vapor with an eye-safe wavelength based on a solid-state laser material. Researchers have analyzed and demonstrated coherent DIAL water vapor measurements at 10 micrometers wavelength based on CO2 lasers. The hope of the research presented here is that the 2 gm wavelength in a holmium or thulium-based laser may offer smaller packaging and more rugged operation that the CO2-based approach. Researchers have extensively modeled 2 um coherent lasers for water vapor profiling, but no published demonstration is known. Studies have also been made, and results published on the Doppler portion, of a Nd:YAG-based coherent DIAL operating at 1.12 micrometers. Eye-safety of the 1.12 micrometer wavelength may be a concern, whereas the longer 2 micrometer and 10 micrometer systems allow a high level of eyesafety.

  7. Thulium Fiber Laser lithotripsy

    NASA Astrophysics Data System (ADS)

    Blackmon, Richard Leious, Jr.

    The Thulium Fiber Laser (TFL) has been studied as a potential alternative to the conventional Holmium:YAG laser (Ho:YAG) for the treatment of kidney stones. The TFL is more ideally suited for laser lithotripsy because of the higher absorption coefficient of the emitted wavelength in water, the superior Gaussian profile of the laser beam, and the ability to operate at arbitrary temporal pulse profiles. The higher absorption of the TFL by water helps translate into higher ablation of urinary stones using less energy. The Gaussian spatial beam profile allows the TFL to couple into fibers much smaller than those currently being used for Ho:YAG lithotripsy. Lastly, the ability of arbitrary pulse operation by the TFL allows energy to be delivered to the stone efficiently so as to avoid negative effects (such as burning or bouncing of the stone) while maximizing ablation. Along with these improvements, the unique properties of the TFL have led to more novel techniques that have currently not been used in the clinic, such as the ability to control the movement of stones based on the manner in which the laser energy is delivered. Lastly, the TFL has led to the development of novel fibers, such as the tapered fiber and removable tip fiber, to be used for lithotripsy which can lead to safer and less expensive treatment of urinary stones. Overall, the TFL has been demonstrated as a viable alternative to the conventional Ho:YAG laser and has the potential to advance methods and tools for treatment of kidney stones.

  8. Monolithic blue upconversion fiber laser

    NASA Astrophysics Data System (ADS)

    Gaebler, Volker; Eichler, Hans J.

    2002-06-01

    We report a monolithic low threshold 482nm Tm:ZBLAN upconversion fiber laser. The laser cavity consists of a directly coated single-mode fluoride fiber. The vapor deposit coatings significantly reduce the coupling losses and are suitable to be pumped by laser diodes. The laser operation and threshold characteristics have been investigated. The output stability and beam quality was tested.

  9. Optical fiber laser

    SciTech Connect

    Hakimi, F.; Po, H.; Snitzer, E.

    1987-07-14

    An optical fiber laser is described comprising: a gain cavity including a single mode optical fiber of given length having a core with a given index of refraction and a cladding surrounding the core and having an index of refraction lower than that of the core. The core comprises a host glass having incorporated a laser gain material with a fluorescence spectrum having at least one broadband region in which there is at least one peak emission line; filter means optically coupled to one end of the gain cavity and reflective to radiation emitted from the gain material over a predetermined wavelength interval about the peak emission line to provide feedback in the gain cavity; an etalon filter section butt coupled to the remaining end of the gain cavity optical fiber, the etalon filter section comprising a pair of filters spaced apart in parallel by a predetermined length of material transparent to any radiation emitted from the gain cavity. The predetermined length of the transparent material is such that the etalon filter section is no longer than the distance over which the wave train energy from the fiber core remains substantially planar so that the etalon filter section is inside the divergent region to enhance feedback in the gain cavity; and means for pumping energy into the gain cavity to raise the interval energy level such that only a small part of the ion population, corresponding to a predetermined bandwidth about the peak emission line, is raised above laser threshold. The laser emits radiation only over narrow lines over a narrow wavelength interval centered about the peak emission line.

  10. Diode Pumped Fiber Laser.

    DTIC Science & Technology

    1987-08-01

    mounting fixture beeame soft and gradually come out of the fixture. S)me chemical reaction was takin- place between the epoxy and the dye solvent , which...loose. The solvent apparenlly did no)t affect the bonding agent used to attach the fibers inside the capillarie,. \\lthmigh individual capillarv tubes...pure solvent . was added to the cavity laser oscillation ceased, and was onlv re, ,t()red after readjuisting the orientation of the output coupler, as

  11. Discrete bisoliton fiber laser

    PubMed Central

    Liu, X. M.; Han, X. X.; Yao, X. K.

    2016-01-01

    Dissipative solitons, which result from the intricate balance between dispersion and nonlinearity as well as gain and loss, are of the fundamental scientific interest and numerous important applications. Here, we report a fiber laser that generates bisoliton – two consecutive dissipative solitons that preserve a fixed separation between them. Deviations from this separation result in its restoration. It is also found that these bisolitons have multiple discrete equilibrium distances with the quantized separations, as is confirmed by the theoretical analysis and the experimental observations. The main feature of our laser is the anomalous dispersion that is increased by an order of magnitude in comparison to previous studies. Then the spectral filtering effect plays a significant role in pulse-shaping. The proposed laser has the potential applications in optical communications and high-resolution optics for coding and transmission of information in higher-level modulation formats. PMID:27767075

  12. Discrete bisoliton fiber laser

    NASA Astrophysics Data System (ADS)

    Liu, X. M.; Han, X. X.; Yao, X. K.

    2016-10-01

    Dissipative solitons, which result from the intricate balance between dispersion and nonlinearity as well as gain and loss, are of the fundamental scientific interest and numerous important applications. Here, we report a fiber laser that generates bisoliton – two consecutive dissipative solitons that preserve a fixed separation between them. Deviations from this separation result in its restoration. It is also found that these bisolitons have multiple discrete equilibrium distances with the quantized separations, as is confirmed by the theoretical analysis and the experimental observations. The main feature of our laser is the anomalous dispersion that is increased by an order of magnitude in comparison to previous studies. Then the spectral filtering effect plays a significant role in pulse-shaping. The proposed laser has the potential applications in optical communications and high-resolution optics for coding and transmission of information in higher-level modulation formats.

  13. Fiber Laser Development for LISA

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Chen, Jeffrey R.

    2009-01-01

    We have developed a linearly-polarized Ytterbium-doped fiber ring laser with single longitudinal-mode output at 1064nm for LISA and other space applications. Single longitudinal-mode selection was achieved by using a fiber Bragg grating (FBG) and a fiber Fabry-Perot (FFP). The FFP also serves as a frequency-reference within our ring laser. Our laser exhibits comparable low frequency and intensity noise to Non-Planar Ring Oscillator (NPRO). By using a fiber-coupled phase modulator as a frequency actuator, the laser frequency can be electro-optically tuned at a rate of 100kHz. It appears that our fiber ring laser is promising for space applications where robustness of fiber optics is desirable.

  14. Fiber lasers for material processing

    NASA Astrophysics Data System (ADS)

    Shiner, Bill

    2005-03-01

    Low power fiber lasers began entering the commercial markets in the early 1990s. Since their introduction, fiber lasers have rapidly progressed in power levels level with greatly improved beam quality to the point where they now exceed any other commercial material processing laser. These lasers, with single mode operation to 1 kilowatt and multi-mode operation to beyond 20 kilowatts, have high wall plug efficiency, an extremely compact footprint, are maintenance free and have a predicted diode life beyond 100,000 hours of continuous operation. Fiber lasers are making inroads into the scientific, medical, government, and in particular, material processing markets. These lasers have greatly expanded the application umbrella due to their unparallel performance combined with the ability to operate at different wavelengths, address remote applications and be propagated great distances in fiber. In the material processing markets, fiber lasers are rapidly gaining share in the automotive, microelectronic, medical device and marking markets, to name a few. The single mode lasers are redefining process parameters that have been accepted for decades. The high brightness multimode-kilowatt class lasers are achieving speeds and depths greater than comparable powered conventional lasers while providing the only commercial material processing lasers operating beyond 6 kilowatts at the 1 micron region.

  15. The fiber optic system for the advanced topographic laser altimeter system instrument (ATLAS)

    NASA Astrophysics Data System (ADS)

    Ott, Melanie N.; Thomes, W. Joe; Onuma, Eleanya; Switzer, Robert; Chuska, Richard; Blair, Diana; Frese, Erich; Matyseck, Marc

    2016-09-01

    The Advanced Topographic Laser Altimeter System (ATLAS) Instrument has been in integration and testing over the past 18 months in preparation for the Ice, Cloud and Land Elevation Satellite - 2 (ICESat-2) Mission, scheduled to launch in 2017. ICESat-2 is the follow on to ICESat which launched in 2003 and operated until 2009. ATLAS will measure the elevation of ice sheets, glaciers and sea ice or the "cryosphere" (as well as terrain) to provide data for assessing the earth's global climate changes. Where ICESat's instrument, the Geo-Science Laser Altimeter (GLAS) used a single beam measured with a 70 m spot on the ground and a distance between spots of 170 m, ATLAS will measure a spot size of 10 m with a spacing of 70 cm using six beams to measure terrain height changes as small as 4 mm.[1] The ATLAS pulsed transmission system consists of two lasers operating at 532 nm with transmitter optics for beam steering, a diffractive optical element that splits the signal into 6 separate beams, receivers for start pulse detection and a wavelength tracking system. The optical receiver telescope system consists of optics that focus all six beams into optical fibers that feed a filter system that transmits the signal via fiber assemblies to the detectors. Also included on the instrument is a system that calibrates the alignment of the transmitted pulses to the receiver optics for precise signal capture. The larger electro optical subsystems for transmission, calibration, and signal receive, stay aligned and transmitting sufficiently due to the optical fiber system that links them together. The robust design of the fiber optic system, consisting of a variety of multi fiber arrays and simplex assemblies with multiple fiber core sizes and types, will enable the system to maintain consistent critical alignments for the entire life of the mission. Some of the development approaches used to meet the challenging optical system requirements for ATLAS are discussed here.

  16. The fiber optic system for the Advanced Topographic Laser Altimeter System (ATLAS) instrument.

    PubMed

    Ott, Melanie N; Thomes, Joe; Onuma, Eleanya; Switzer, Robert; Chuska, Richard; Blair, Diana; Frese, Erich; Matyseck, Marc

    2016-08-28

    The Advanced Topographic Laser Altimeter System (ATLAS) Instrument has been in integration and testing over the past 18 months in preparation for the Ice, Cloud and Land Elevation Satellite - 2 (ICESat-2) Mission, scheduled to launch in 2017. ICESat-2 is the follow on to ICESat which launched in 2003 and operated until 2009. ATLAS will measure the elevation of ice sheets, glaciers and sea ice or the "cryosphere" (as well as terrain) to provide data for assessing the earth's global climate changes. Where ICESat's instrument, the Geo-Science Laser Altimeter (GLAS) used a single beam measured with a 70 m spot on the ground and a distance between spots of 170 m, ATLAS will measure a spot size of 10 m with a spacing of 70 cm using six beams to measure terrain height changes as small as 4 mm.[1] The ATLAS pulsed transmission system consists of two lasers operating at 532 nm with transmitter optics for beam steering, a diffractive optical element that splits the signal into 6 separate beams, receivers for start pulse detection and a wavelength tracking system. The optical receiver telescope system consists of optics that focus all six beams into optical fibers that feed a filter system that transmits the signal via fiber assemblies to the detectors. Also included on the instrument is a system that calibrates the alignment of the transmitted pulses to the receiver optics for precise signal capture. The larger electro optical subsystems for transmission, calibration, and signal receive, stay aligned and transmitting sufficiently due to the optical fiber system that links them together. The robust design of the fiber optic system, consisting of a variety of multi fiber arrays and simplex assemblies with multiple fiber core sizes and types, will enable the system to maintain consistent critical alignments for the entire life of the mission. Some of the development approaches used to meet the challenging optical system requirements for ATLAS are discussed here.

  17. Imaging dynamic processes using fiber laser optical-resolution photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Shi, Wei; Shao, Peng; Hajireza, Parsin; Forbrich, Alexander; Zemp, Roger J.

    2012-02-01

    Recently we have reported in vivo near-real-time volumetric optical-resolution photoacoustic microscopy (OR-PAM) using a high pulse-repetition-rate (PRR) nanosecond fiber-laser to realize 2 volumetric image frames per second (fps) within 1mm × 1mm field of view (FOV). Based on our previous OR-PAM system, we are developing a label-free realtime OR-PAM system in reflection mode for higher frame-rates. The system permits imaging of microcirculation hemodynamics, and helps make the technology easier to use for biologists, providing real-time feedback for focusing and positioning. Using a nanosecond-pulsed 532-nm fiber laser combined with fast-scanning mirrors, our proposed system demonstrated its capability of sustained in vivo imaging of horizontal and vertical translation at 0.5 fps for 1mm × 1mm FOV (400 × 400 pixels). Also, real-time in vivo imaging of blood flow at 30 fps for 250μm × 250μm FOV (100 × 100 pixels) was demonstrated. It is anticipated that the real-time nature of the system should prove important in clinical and preclinical adaption, and may prove useful for functional brain imaging studies.

  18. Dissipative solitons in fiber lasers

    NASA Astrophysics Data System (ADS)

    Turitsyn, S. K.; Rosanov, N. N.; Yarutkina, I. A.; Bednyakova, A. E.; Fedorov, S. V.; Shtyrina, O. V.; Fedoruk, M. P.

    2016-07-01

    Dissipative solitons (also known as auto-solitons) are stable, nonlinear, time- or space-localized solitary waves that occur due to the balance between energy excitation and dissipation. We review the theory of dissipative solitons applied to fiber laser systems. The discussion context includes the classical Ginzburg-Landau and Maxwell-Bloch equations and their modifications that allow describing laser-cavity-produced waves. Practical examples of laser systems generating dissipative solitons are discussed.

  19. In vivo near-realtime volumetric optical-resolution photoacoustic microscopy using a high-repetition-rate nanosecond fiber-laser

    NASA Astrophysics Data System (ADS)

    Shi, Wei; Hajireza, Parsin; Shao, Peng; Forbrich, Alexander; Zemp, Roger J.

    2011-08-01

    Optical-resolution photoacoustic microscopy (OR-PAM) is capable of achieving optical-absorption-contrast images with micron-scale spatial resolution. Previous OR-PAM systems have been frame-rate limited by mechanical scanning speeds and laser pulse repetition rate (PRR). We demonstrate OR-PAM imaging using a diode-pumped nanosecond-pulsed Ytterbium-doped 532-nm fiber laser with PRR up to 600 kHz. Combined with fast-scanning mirrors, our proposed system provides C-scan and 3D images with acquisition frame rate of 4 frames per second (fps) or higher, two orders of magnitude faster than previously published systems. High-contrast images of capillary-scale microvasculature in a live Swiss Webster mouse ear with ~6-μm optical lateral spatial resolution are demonstrated.

  20. Laser peening with fiber optic delivery

    DOEpatents

    Friedman, Herbert W.; Ault, Earl R.; Scheibner, Karl F.

    2004-11-16

    A system for processing a workpiece using a laser. The laser produces at least one laser pulse. A laser processing unit is used to process the workpiece using the at least one laser pulse. A fiber optic cable is used for transmitting the at least one laser pulse from the laser to the laser processing unit.

  1. A High Power Frequency Doubled Fiber Laser

    NASA Technical Reports Server (NTRS)

    Thompson, Rob; Tu, Meirong; Aveline, Dave; Lundblad, Nathan; Maleki, Lute

    2003-01-01

    This slide presentation reviews the power frequencies for the doubled fiber laser. It includes information on the 780 nm laser, second harmonic generation in one crystal, cascading crystals, the tenability of laser systems, laser cooling, and directions for future work.

  2. High Power Fiber Lasers

    DTIC Science & Technology

    2012-08-02

    mode, purity of polarization state, minimization of nonlinear effects, compatibility with all-fiber pumps, and high temperature buffer coatings. Over...nonlinear effects, compatibility with all-fiber pumps, and high temperature buffer coatings. Over the duration of this program the most significant...minimization of nonlinear effects, compatibility with all-fiber pumps, and high temperature buffer coatings. Over the duration of this program the most

  3. 2 micron femtosecond fiber laser

    DOEpatents

    Liu, Jian; Wan, Peng; Yang, Lihmei

    2014-07-29

    Methods and systems for generating femtosecond fiber laser pulses are disclose, including generating a signal laser pulse from a seed laser oscillator; using a first amplifier stage comprising an input and an output, wherein the signal laser pulse is coupled into the input of the first stage amplifier and the output of the first amplifier stage emits an amplified and stretched signal laser pulse; using an amplifier chain comprising an input and an output, wherein the amplified and stretched signal laser pulse from the output of the first amplifier stage is coupled into the input of the amplifier chain and the output of the amplifier chain emits a further amplified, stretched signal laser pulse. Other embodiments are described and claimed.

  4. Ultrafast fiber lasers: practical applications

    NASA Astrophysics Data System (ADS)

    Pastirk, Igor; Sell, Alexander; Herda, Robert; Brodschelm, Andreas; Zach, Armin

    2015-05-01

    Over past three decades ultrafast lasers have come a long way from the bulky, demanding and very sensitive scientific research projects to widely available commercial products. For the majority of this period the titanium-sapphire-based ultrafast systems were the workhorse for scientific and emerging industrial and biomedical applications. However the complexity and intrinsic bulkiness of solid state lasers have prevented even larger penetration into wider array of practical applications. With emergence of femtosecond fiber lasers, based primarily on Er-doped and Yb-doped fibers that provide compact, inexpensive and dependable fs and ps pulses, new practical applications have become a reality. The overview of current state of the art ultrafast fiber sources, their basic principles and most prominent applications will be presented, including micromachining and biomedical implementations (ophthalmology) on one end of the pulse energy spectrum and 3D lithography and THz applications on the other.

  5. Fiber Laser Array

    DTIC Science & Technology

    2004-01-01

    telecommunications market and do not emphasize high powers. Because high power applications are of significant interest to the Air Force, we were interested in fiber...available from NTIC . 9. T.B. Simpson, A. Gavrielides and P. Peterson, “Extraction Characteristics of a Dual Fiber Compound Cavity,” Optics Express 10

  6. All fiber passively Q-switched laser

    DOEpatents

    Soh, Daniel B. S.; Bisson, Scott E

    2015-05-12

    Embodiments relate to an all fiber passively Q-switched laser. The laser includes a large core doped gain fiber having a first end. The large core doped gain fiber has a first core diameter. The laser includes a doped single mode fiber (saturable absorber) having a second core diameter that is smaller than the first core diameter. The laser includes a mode transformer positioned between a second end of the large core doped gain fiber and a first end of the single mode fiber. The mode transformer has a core diameter that transitions from the first core diameter to the second core diameter and filters out light modes not supported by the doped single mode fiber. The laser includes a laser cavity formed between a first reflector positioned adjacent the large core doped gain fiber and a second reflector positioned adjacent the doped single mode fiber.

  7. Fiber-coupled, 10 kHz simultaneous OH planar laser-induced fluorescence/particle-image velocimetry.

    PubMed

    Hsu, Paul S; Jiang, Naibo; Gord, James R; Roy, Sukesh

    2013-01-15

    Planar laser-induced fluorescence (PLIF) and particle-image velocimetry (PIV) techniques that employ free-standing optics face severe challenges when implemented in harsh environments associated with practical combustion facilities because of limited optical access and restrictions on operation of sensitive laser systems. To circumvent this problem, we have developed and implemented a fiber-coupled, high-speed ultraviolet (UV) PLIF/PIV system for measuring hydroxyl radical (OH) concentration and velocity in a realistic 4 MW combustion rig. This system permits delivery of high-power, 10 kHz, nanosecond-duration OH-PLIF excitation pulses (283 nm) and PIV pulses (532 nm) through a common 6 m long, 600 μm core, deep-UV-enhanced multimode fiber. Simultaneous OH-PLIF and PIV imaging at a data-acquisition rate of 10 kHz is demonstrated in turbulent premixed flames behind a bluff body. The effects of delivering high-repetition-rate, intense UV and visible beams through a long optical fiber are investigated, and potential system improvements are discussed.

  8. Optical turbulence in fiber lasers.

    PubMed

    Wabnitz, Stefan

    2014-03-15

    We analyze the nonlinear stage of modulation instability in passively mode-locked fiber lasers leading to chaotic or noise-like emission. We present the phase-transition diagram among different regimes of chaotic emission in terms of the key cavity parameters: amplitude or phase turbulence, and spatio-temporal intermittency.

  9. Fiber-Coupled Planar Light-Wave Circuit for Seed Laser Control in High Spectral Resolution Lidar Systems

    NASA Technical Reports Server (NTRS)

    Cook, Anthony; McNeil, Shirley; Switzer, Gregg; Battle, Philip

    2010-01-01

    Precise laser remote sensing of aerosol extinction and backscatter in the atmosphere requires a high-power, pulsed, frequency doubled Nd:YAG laser that is wavelength- stabilized to a narrow absorption line such as found in iodine vapor. One method for precise wavelength control is to injection seed the Nd:YAG laser with a low-power CW laser that is stabilized by frequency converting a fraction of the beam to 532 nm, and to actively frequency-lock it to an iodine vapor absorption line. While the feasibility of this approach has been demonstrated using bulk optics in NASA Langley s Airborne High Spectral Resolution Lidar (HSRL) program, an ideal, lower cost solution is to develop an all-waveguide, frequency-locked seed laser in a compact, robust package that will withstand the temperature, shock, and vibration levels associated with airborne and space-based remote sensing platforms. A key technology leading to this miniaturization is the integration of an efficient waveguide frequency doubling element, and a low-voltage phase modulation element into a single, monolithic, planar light-wave circuit (PLC). The PLC concept advances NASA's future lidar systems due to its compact, efficient and reliable design, thus enabling use on small aircraft and satellites. The immediate application for this technology is targeted for NASA Langley's HSRL system for aerosol and cloud characterization. This Phase I effort proposes the development of a potassium titanyl phosphate (KTP) waveguide phase modulator for future integration into a PLC. For this innovation, the proposed device is the integration of a waveguide-based frequency doubler and phase modulator in a single, fiber pigtail device that will be capable of efficient second harmonic generation of 1,064-nm light and subsequent phase modulation of the 532 nm light at 250 MHz, providing a properly spectrally formatted beam for HSRL s seed laser locking system. Fabrication of the integrated PLC chip for NASA Langley, planned for

  10. Fiber-laser-based green-pumped picosecond MgO:sPPLT optical parametric oscillator.

    PubMed

    Chaitanya Kumar, S; Ebrahim-Zadeh, M

    2013-12-15

    We report a stable, high-power, picosecond optical parametric oscillator (OPO) at 160 MHz repetition rate synchronously pumped by a frequency-doubled mode-locked Yb-fiber laser at 532 nm and tunable in the near-infrared, across 874-1008 nm (signal) and 1126-1359 nm (idler). Using a 30-mm-long MgO:sPPLT crystal, the OPO provides average output power up to 780 mW in the signal at 918.58 nm and 600 mW in the idler at 1242 nm. The device operates stably over many days, even close to degeneracy, exhibiting passive long-term power stability better than 1.8% rms in the signal and 2.4% rms in the idler over 2.5 h at a temperature of 55°C. We investigate spectral and temporal characteristics of the signal pulses under different conditions and demonstrate cavity-length tuning enabled by the dispersion properties of MgO:sPPLT. The output signal pulses have a duration of 2.4 ps at 967 nm.

  11. Visible supercontinuum generation in photonic crystal fiber using various harmonics of subnanosecond Q-switched laser

    NASA Astrophysics Data System (ADS)

    Vengelis, Julius; Jarutis, Vygandas; Sirutkaitis, Valdas

    2016-09-01

    We report results of supercontinuum generation in highly nonlinear polarization maintaining photonic crystal fiber (PCF) using the first or second harmonics of a subnanosecond passively Q-switched Nd:YAG microlaser. The Nd:YAG microlaser generated 50 μJ energy 300 ps duration pulses at 1064 nm with a kilohertz repetition rate. We demonstrated that we can expand the supercontinuum spectrum to cover the whole visible range and beyond using either first or second harmonics of our pump laser in the case of such pump pulse durations. In the case of a first-harmonic pump (λp=1064 nm), the supercontinuum extended from 400 to 1300 nm and in the case of a second-harmonic pump (λp=532 nm), it extended from 400 to 900 nm. In addition, we compared the supercontinuum evolution and dependence on pump pulse energy in both cases. We also performed numerical simulations of supercontinuum generation in PCF using an improved approach. The generalized nonlinear Schrödinger equation was modified so that numerical simulations would yield greater accuracy in the case of longer (300 ps) pulses. The simulated supercontinuum spectra display the same qualitative features as that measured in the experiment.

  12. Diode Pumped Fiber Laser.

    DTIC Science & Technology

    1984-12-01

    72 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 2. Mechanical Q-Switching ..................... 72 3...nonuniform heating of the molten zone due to the manner in which the laser beams are inc ident upon the source rod, and (3) mechanical vibrations in the motor...were attached to a solid block of aluminum for better mechanical stability. Curved mirrors (R = 10 cm) were obtained from an outside manufacturer for

  13. Developing Pulsed Fiber Lasers

    DTIC Science & Technology

    2007-06-15

    moving pupil imaging system. Y. Kawagoe et al. furthered the research in the early 80’s by using a rotating aperture at the Fourier ...dependent terms in Eq. 16 by their respective Fourier Series Eq. 16 can be written in the following form, ( ) ( ) ( ) ( )( ) ( ) ( ) ( )( )( ) 1 2 0...Asakura, “Speckle reduction by a rotating aperture at the Fourier transform plane,” Opt. Lasers in Eng., 3 197-218, (1982) [8] T. Iwai, N. Takai

  14. Single-frequency, fully integrated, miniature DPSS laser based on monolithic resonator

    NASA Astrophysics Data System (ADS)

    Dudzik, G.; Sotor, J.; Krzempek, K.; Soboń, G.; Abramski, K. M.

    2014-02-01

    We present a single frequency, stable, narrow linewidth, miniature laser sources operating at 532 nm (or 1064 nm) based on a monolithic resonators. Such resonators utilize birefringent filters formed by YVO4 beam displacer and KTP or YVO4 crystals to force single frequency operation at 532 nm or 1064 nm, respectively. In both configurations Nd:YVO4 gain crystal is used. The resonators dimensions are 1x1x10.5 mm3 and 1x1x8.5 mm3 for green and infrared configurations, respectively. Presented laser devices, with total dimensions of 40x52x120 mm3, are fully equipped with driving electronics, pump diode, optical and mechanical components. The highly integrated (36x15x65 mm3) low noise driving electronics with implemented digital PID controller was designed. It provides pump current and resonator temperature stability of ±30 μA@650 mA and ±0,003ºC, respectively. The laser parameters can be set and monitored via the USB interface by external application. The developed laser construction is universal. Hence, the other wavelengths can be obtained only by replacing the monolithic resonator. The optical output powers in single frequency regime was at the level of 42 mW@532 nm and 0.5 W@1064 nm with the long-term fluctuations of ±0.85 %. The linewidth and the passive frequency stability under the free running conditions were Δν < 100 kHz and 3ṡ10-9@1 s integration time, respectively. The total electrical power supply consumption of laser module was only 4 W. Presented compact, single frequency laser operating at 532 nm and 1064 nm may be used as an excellent source for laser vibrometry, interferometry or seed laser for fiber amplifiers.

  15. [Solid-state multi-wavelength lasers equipment for retina treatment].

    PubMed

    Liu, Wenlu; Zhou, Chuanqing; Ren, Qiushi

    2012-09-01

    Solid-state multi-wavelength laser equipment is the treatment device with selected wavelength Nd: YAG laser frequency technology, integrated red (659 nm), yellow (589 nm) and green (532 nm) of three solid-state lasers. The device is designed by the accurate controlled laser output system, precision optical and electronic control through the optical coupler into the optical fiber transmission system. It's combined with an eye slit lamp integration of high precision, good stability stability for all solid-state multi-wavelength lasers equipment.

  16. Fiber-laser-based, high-repetition-rate, picosecond ultraviolet source tunable across 329-348  nm.

    PubMed

    Devi, Kavita; Chaitanya Kumar, S; Ebrahim-Zadeh, M

    2016-10-15

    We report a compact, fiber-laser-based, high-repetition-rate picosecond source for the ultraviolet (UV), providing multi-tens of milliwatt of average power across 329-348 nm. The source is based on internal sum-frequency-generation (SFG) in a singly resonant optical parametric oscillator (OPO), synchronously pumped at 532 nm by the second harmonic of a picosecond Yb-fiber laser at 80 MHz repetition rate. Using a 30-mm-long single-grating MgO:sPPLT crystal for the OPO and a 5-mm-long BiB3O6 crystal for intracavity SFG, we generate up to 115 mW of average UV power at 339.9 nm, with >50  mW over 73% of the tuning range, for 1.6 W of input pump power. The UV output exhibits a passive rms power stability of ∼2.9% rms over 1 min and 6.5% rms over 2 h in high beam quality. Angular acceptance bandwidth and cavity detuning effects have also been studied.

  17. Simultaneous self-starting additive pulse mode-locking and second harmonic generation of an Nd:YAG laser using self-organised germanosilicate optical fibres

    NASA Astrophysics Data System (ADS)

    Bernardin, J. P.; Lawandy, N. M.

    1991-08-01

    The simultaneous operation of self-starting additive pulse mode-locking and optical fiber second harmonic generation of an Nd:YAG laser resulting in picosecond radiation at 1.06 mm and 532 nm was demonstrated. The IR pulses were measured to be 5 ps in duration, and the green pulses are expected to be approximately 3.5 ps due to the nonlinear interaction. Effects of self-modulation and cross-phase modulation on the conversion efficiency are discussed.

  18. Fiber laser coupled optical spark delivery system

    DOEpatents

    Yalin, Azer; Willson, Bryan; Defoort, Morgan; Joshi, Sachin; Reynolds, Adam

    2008-03-04

    A spark delivery system for generating a spark using a laser beam is provided, and includes a laser light source and a laser delivery assembly. The laser delivery assembly includes a hollow fiber and a launch assembly comprising launch focusing optics to input the laser beam in the hollow fiber. The laser delivery assembly further includes exit focusing optics that demagnify an exit beam of laser light from the hollow fiber, thereby increasing the intensity of the laser beam and creating a spark. Other embodiments use a fiber laser to generate a spark. Embodiments of the present invention may be used to create a spark in an engine. Yet other embodiments include collecting light from the spark or a flame resulting from the spark and conveying the light for diagnostics. Methods of using the spark delivery systems and diagnostic systems are provided.

  19. Cladded single crystal fibers for high power fiber lasers

    NASA Astrophysics Data System (ADS)

    Kim, W.; Shaw, B.; Bayya, S.; Askins, C.; Peele, J.; Rhonehouse, D.; Meyers, J.; Thapa, R.; Gibson, D.; Sanghera, J.

    2016-09-01

    We report on the recent progress in the development of cladded single crystal fibers for high power single frequency lasers. Various rare earth doped single crystal YAG fibers with diameters down to 17 μm with length > 1 m have been successfully drawn using a state-of-the-art Laser Heated Pedestal Growth system. Single and double cladding on rare earth doped YAG fibers have been developed using glasses where optical and physical properties were precisely matched to doped YAG core single crystal fiber. The double clad Yb:YAG fiber structures have dimensions analogous to large mode area (LMA) silica fiber. We also report successful fabrications of all crystalline core/clad fibers where thermal and optical properties are superior over glass cladded YAG fibers. Various fabrication methods, optical characterization and gain measurements on these cladded YAG fibers are reported.

  20. Fiber Laser Front Ends for High Energy, Short Pulse Lasers

    SciTech Connect

    Dawson, J; Messerly, M; Phan, H; Siders, C; Beach, R; Barty, C

    2007-06-21

    We are developing a fiber laser system for short pulse (1-10ps), high energy ({approx}1kJ) glass laser systems. Fiber lasers are ideal for these systems as they are highly reliable and enable long term stable operation.

  1. Fiber lasers and their applications [Invited].

    PubMed

    Shi, Wei; Fang, Qiang; Zhu, Xiushan; Norwood, R A; Peyghambarian, N

    2014-10-01

    Fiber lasers have seen progressive developments in terms of spectral coverage and linewidth, output power, pulse energy, and ultrashort pulse width since the first demonstration of a glass fiber laser in 1964. Their applications have extended into a variety of fields accordingly. In this paper, the milestones of glass fiber laser development are briefly reviewed and recent advances of high-power continuous wave, Q-switched, mode-locked, and single-frequency fiber lasers in the 1, 1.5, 2, and 3 μm regions and their applications in such areas as industry, medicine, research, defense, and security are addressed in detail.

  2. Mode-locked fiber lasers based on doped fiber arrays.

    PubMed

    Zhang, Xiao; Song, Yanrong

    2014-05-10

    We designed a new kind of mode-locked fiber laser based on fiber arrays, where the central core is doped. A theoretical model is given for an all-fiber self-starting mode-locked laser based on this kind of doped fiber array. Two different kinds of fiber lasers with negative dispersion and positive dispersion are simulated and discussed. The stable mode-locked pulses are generated from initial noise conditions by the realistic parameters. The process of self-starting mode-locking multipulse transition and the relationship between the energy of the central core and the propagation distance of the pulses are discussed. Finally, we analyze the difference between the averaged mode-locked laser and the discrete mode-locked laser.

  3. Advanced fiber lasers and related all-fiber devices

    NASA Astrophysics Data System (ADS)

    Srinivasan, Balaji

    2000-11-01

    Fiber lasers based on rare-earth ions now play an important role in several applications ranging from communications and surgery to spectroscopic sensing because of their efficiency and compactness, and their intrinsic compatibility with single mode communication fibers. As such, there is a strong need to investigate key issues related to the design and fabrication of ``rugged'' state-of-the-art fiber lasers, and in particular to fabricate versatile high-performance fiber lasers based on ``all-fiber'' devices, i.e. using only in-fiber devices. This dissertation addresses some of these needs. One such issue is the polarization property of lasers and amplifiers based on polarization preserving fibers. A dedicated study of the polarization properties of amplifiers and lasers based on rare-earth doped elliptical core fibers has been performed. The results indicate a polarization dependent gain, with a larger gain at the polarization parallel to the major axis of the ellipse. This gain anisotropy is attributed to the differences in the confinement of the two orthogonally polarized fundamental modes of the fiber. Another issue that has been driven by several medical, sensing, and data storage applications is that of efficient laser transitions in the mid-infrared and visible spectral regions. Such lasers are difficult to achieve in conventional fibers based on silica glass hosts due to their relatively large phonon energies. A fluoride based glass host (ZBLAN) with low phonon energy was chosen to enable green and blue laser transitions using upconversion schemes in erbium and thulium respectively, and realize an efficient mid-infrared transition in erbium. Specifically, the following results have been demonstrated: (1)Green (544 nm) fiber laser with the highest combination of power (50 mW) and efficiency (37%) in Er:ZBLAN; (2)Novel Raman fiber laser-pumped 22 mW blue (490 nm) laser in Tm:ZBLAN; (3)Diode-pumped mid-infrared (2.7 μm) laser with 660 mW output in Er

  4. 2-μm fiber laser sources for sensing

    NASA Astrophysics Data System (ADS)

    Wang, Qing; Geng, Jihong; Jiang, Shibin

    2014-06-01

    2-μm fiber lasers have become a research topic with an increased emphasis due to a variety of applications including eye-safe LIDAR, spectroscopy, remote sensing, and mid-infrared (mid-IR) frequency generation. We review our latest development on various 2-μm fiber laser sources, including single-frequency fiber lasers, Q-switched fiber lasers, mode-locked fiber lasers, and mid-IR supercontinuum fiber sources. All these fiber laser sources are based on thulium and holmium ions using our proprietary glass fiber technology. Potential applications of these fiber laser sources for sensing are also briefly discussed.

  5. Yb-fiber-laser-based, 1.8 W average power, picosecond ultraviolet source at 266 nm.

    PubMed

    Chaitanya Kumar, S; Canals Casals, J; Sanchez Bautista, E; Devi, K; Ebrahim-Zadeh, M

    2015-05-15

    We report a compact, stable, high-power, picosecond ultraviolet (UV) source at 266 nm based on simple single-pass two-step fourth-harmonic generation (FHG) of a mode-locked Yb-fiber laser at 79.5 MHz in LiB3O5 (LBO) and β-BaB2O4. Using a 30-mm-long LBO crystal for single-pass second-harmonic generation, we achieve up to 9.1 W of average green power at 532 nm for 16.8 W of Yb-fiber power at a conversion efficiency of 54% in 16.2 ps pulses with a TEM00 spatial profile and passive power stability better than 0.5% rms over 16 h. The generated green radiation is then used for single-pass FHG into the UV, providing as much as 1.8 W of average power at 266 nm under the optimum focusing condition in the presence of spatial walk-off, at an overall FHG conversion efficiency of ∼11%. The generated UV output exhibits passive power stability better than 4.6% rms over 1.5 h and beam pointing stability better than 84 μrad over 1 h. The UV output beam has a circularity of >80% in high beam quality with the TEM00 mode profile. To the best of our knowledge, this is the first report of picosecond UV generation at 266 nm at megahertz repetition rates.

  6. Fiber optic applications for laser polarized targets

    SciTech Connect

    Cummings, W.J.; Kowalczyk, R.S.

    1997-10-01

    For the past two years, the laser polarized target group at Argonne has been used multi-mode fiber optic patch cords for a variety of applications. In this paper, the authors describe the design for transporting high power laser beams with optical fibers currently in use at IUCF.

  7. Microring embedded hollow polymer fiber laser

    SciTech Connect

    Linslal, C. L. Sebastian, S.; Mathew, S.; Radhakrishnan, P.; Nampoori, V. P. N.; Girijavallabhan, C. P.; Kailasnath, M.

    2015-03-30

    Strongly modulated laser emission has been observed from rhodamine B doped microring resonator embedded in a hollow polymer optical fiber by transverse optical pumping. The microring resonator is fabricated on the inner wall of a hollow polymer fiber. Highly sharp lasing lines, strong mode selection, and a collimated laser beam are observed from the fiber. Nearly single mode lasing with a side mode suppression ratio of up to 11.8 dB is obtained from the strongly modulated lasing spectrum. The microring embedded hollow polymer fiber laser has shown efficient lasing characteristics even at a propagation length of 1.5 m.

  8. Multiwavelength fiber laser for the fiber link monitoring system

    NASA Astrophysics Data System (ADS)

    Peng, Peng-Chun; Lee, Wei-Yun; Wu, Shin-Shian; Hu, Hsuan-Lun

    2013-10-01

    This work proposes a novel fiber link monitoring system that uses a multiwavelength fiber laser for wavelength-division-multiplexed (WDM) passive optical network (PON). The multiwavelength fiber laser is based on an erbium-doped fiber amplifier (EDFA) and a semiconductor optical amplifier (SOA). Experimental results show the feasibility using the system to monitor a fiber link with a high and stable signal-to-noise ratio (SNR) of over 26 dB. The link quality of downstream signals as well as the fiber link on WDM channels can be monitored in real time. Favorable carrier-to-noise ratio (CNR), composite second-order (CSO), and composite triple beat (CTB) performance metrics were obtained for cable television (CATV) signals that were transported through 25 km of standard single-mode fiber (SMF).

  9. Advances in drilling with fiber lasers

    NASA Astrophysics Data System (ADS)

    Naeem, Mohammed

    2015-07-01

    High brightness quasi- continuous wave (QCW) and continuous wave (CW) fiber lasers are routinely being used for cutting and welding for a range of industrial applications. However, to date very little work has been carried out or has been reported on laser drilling with these laser sources. This work describes laser drilling ((trepan and percussion) of nickel based superalloys (thermal barrier coated and uncoated) with a high power QCW fiber laser. This presentation will highlight some of the most significant aspect of laser drilling, i.e. SmartPierceTM, deep hole drilling and small hole drilling. These advances in processing also demonstrate the potential for fiber laser processing when an advanced interface between laser and an open architecture controller are used.

  10. Diode pumped alkali vapor fiber laser

    DOEpatents

    Payne, Stephen A.; Beach, Raymond J.; Dawson, Jay W.; Krupke, William F.

    2006-07-26

    A method and apparatus is provided for producing near-diffraction-limited laser light, or amplifying near-diffraction-limited light, in diode pumped alkali vapor photonic-band-gap fiber lasers or amplifiers. Laser light is both substantially generated and propagated in an alkali gas instead of a solid, allowing the nonlinear and damage limitations of conventional solid core fibers to be circumvented. Alkali vapor is introduced into the center hole of a photonic-band-gap fiber, which can then be pumped with light from a pump laser and operated as an oscillator with a seed beam, or can be configured as an amplifier.

  11. Diode pumped alkali vapor fiber laser

    DOEpatents

    Payne, Stephen A.; Beach, Raymond J.; Dawson, Jay W.; Krupke, William F.

    2007-10-23

    A method and apparatus is provided for producing near-diffraction-limited laser light, or amplifying near-diffraction-limited light, in diode pumped alkali vapor photonic-band-gap fiber lasers or amplifiers. Laser light is both substantially generated and propagated in an alkali gas instead of a solid, allowing the nonlinear and damage limitations of conventional solid core fibers to be circumvented. Alkali vapor is introduced into the center hole of a photonic-band-gap fiber, which can then be pumped with light from a pump laser and operated as an oscillator with a seed beam, or can be configured as an amplifier.

  12. Dark pulse emission of a fiber laser

    SciTech Connect

    Zhang, H.; Tang, D. Y.; Zhao, L. M.; Wu, X.

    2009-10-15

    We report on the dark pulse emission of an all-normal dispersion erbium-doped fiber laser with a polarizer in cavity. We found experimentally that apart from the bright pulse emission, under appropriate conditions the fiber laser could also emit single or multiple dark pulses. Based on numerical simulations we interpret the dark pulse formation in the laser as a result of dark soliton shaping.

  13. Internal modulation of a random fiber laser.

    PubMed

    Bravo, M; Fernandez-Vallejo, M; Lopez-Amo, M

    2013-05-01

    A characterization of a modulated random mirror laser has been experimentally carried out. Unlike conventional internally modulated fiber lasers, no distortion of the modulating frequency or self-mode-locking effects were measured. The behavior of the laser using pulsed and analog modulation up to 12 GHz is shown.

  14. Mobile fiber-optic laser Doppler anemometer.

    PubMed

    Stieglmeier, M; Tropea, C

    1992-07-20

    A laser Doppler anemometer (LDA) has been developed that combines the compactness and low power consumption of laser diodes and avalanche photodiodes with the flexibility and possibility of miniaturization by using fiber-optic probes. The system has been named DFLDA for laser diode fiber LDA and is especially suited for mobile applications, for example, in trains, airplanes, or automobiles. Optimization considerations of fiber-optic probes are put forward and several probe examples are described in detail. Measurement results from three typical applications are given to illustrate the use of the DFLDA. Finally, a number of future configurations of the DFLDA concept are discussed.

  15. Fiber laser performance in industrial applications

    NASA Astrophysics Data System (ADS)

    McCulloch, S.; Hassey, A.; Harrison, P.

    2013-02-01

    Fiber lasers are competing with the traditional CO2 Laser, Plasma, Water Jet and Press Punch technology. This paper concentrates on the drivers behind the progress that <=500W CW fiber lasers have made in the thin metal cutting and welding market. Thin metal cutting in this case is defined as below 4mm and the dominant technology has been the Press Punch for higher quality, large volume components and Plasma for lower quality, small quantities. Up until the fiber lasers were commercially available many machine manufacturers were deterred from incorporating lasers due to the technical barriers posed by the lasers available at that time. In particular fiber laser requires no maintenance does not necessitate a beam path to be aligned and kept free of contaminant so have encouraged many traditionally non-laser machine builders to integrate fiber sources into a variety of applications and push the performance envelope. All of the components to build a fibre laser cutting or welding system are now available "off-the shelf" which is even allowing end users to design and build their own systems directly in production environments.

  16. Mid-Infrared Fiber Lasers (Les fibres laser infrarouge moyen)

    DTIC Science & Technology

    2010-09-01

    à fibres sont intrinsèquement mieux adaptés à ces applications que les lasers à l’état solide conventionnels, offrant un confinement optique , une...Sep 2010 Mid-Infrared Fiber Lasers (Les fibres laser infrarouge moyen) Research and Technology Organisation (NATO) BP 25, F-92201 Neuilly-sur-Seine...SET-171)TP/370 www.rto.nato.int RTO MEETING PROCEEDINGS MP-SET-171 Mid-Infrared Fiber Lasers (Les fibres laser infrarouge moyen) Papers presented

  17. Investigation of Microstructured Optical Fiber in Eight Fiber Laser

    NASA Astrophysics Data System (ADS)

    Bahloul, Faouzi; Ennejah, Tarek; Attia, Rabah

    2012-06-01

    In passively mode locked fiber laser, case of 8FL (Eight Fiber Laser), the management of length, linear and non linear parameters of the cavity plays a paramount role in the generation of stable ultra short pulses with high peak powers. In this work, we propose an 8FL consisted of MOF (Microstructured Optical Fiber). According to the various properties of the MOF, we studied the variation of the pulses peak power and width. We demonstrated that there are optimal parameters of the MOF for which the peak power is maximal and the width is minimal.

  18. Investigation of Microstructured Optical Fiber in Eight Fiber Laser

    NASA Astrophysics Data System (ADS)

    Bahloul, Faouzi; Ennejah, Tarek; Attia, Rabah

    2011-09-01

    In passively mode locked fiber laser, case of 8FL (Eight Fiber Laser), the management of length, linear and non linear parameters of the cavity plays a paramount role in the generation of stable ultra short pulses with high peak powers. In this work, we propose an 8FL consisted of MOF (Microstructured Optical Fiber). According to the various properties of the MOF, we studied the variation of the pulses peak power and width. We demonstrated that there are optimal parameters of the MOF for which the peak power is maximal and the width is minimal.

  19. Progress in Cherenkov femtosecond fiber lasers

    PubMed Central

    Liu, Xiaomin; Svane, Ask S.; Lægsgaard, Jesper; Tu, Haohua; Boppart, Stephen A.; Turchinovich, Dmitry

    2016-01-01

    We review the recent developments in the field of ultrafast Cherenkov fiber lasers. Two essential properties of such laser systems – broad wavelength tunability and high efficiency of Cherenkov radiation wavelength conversion are discussed. The exceptional performance of the Cherenkov fiber laser systems are highlighted - dependent on the realization scheme, the Cherenkov lasers can generate the femtosecond output tunable across the entire visible and even the UV range, and for certain designs more than 40 % conversion efficiency from the pump to Cherenkov signal can be achieved. The femtosecond Cherenkov laser with all-fiber architecture is presented and discussed. Operating in the visible range, it delivers 100–200 fs wavelength-tunable pulses with multimilliwatt output power and exceptionally low noise figure an order of magnitude lower than the traditional wavelength tunable supercontinuum-based femtosecond sources. The applications for Cherenkov laser systems in practical biophotonics and biomedical applications, such as bio-imaging and microscopy, are discussed. PMID:27110037

  20. Progress in Cherenkov femtosecond fiber lasers

    NASA Astrophysics Data System (ADS)

    Liu, Xiaomin; Svane, Ask S.; Lægsgaard, Jesper; Tu, Haohua; Boppart, Stephen A.; Turchinovich, Dmitry

    2016-01-01

    We review the recent developments in the field of ultrafast Cherenkov fiber lasers. Two essential properties of such laser systems—broad wavelength tunability and high efficiency of Cherenkov radiation wavelength conversion are discussed. The exceptional performance of the Cherenkov fiber laser systems are highlighted—dependent on the realization scheme, the Cherenkov lasers can generate the femtosecond output tunable across the entire visible and even the UV range, and for certain designs more than 40% conversion efficiency from the pump to Cherenkov signal can be achieved. The femtosecond Cherenkov laser with all-fiber architecture is presented and discussed. Operating in the visible range, it delivers 100-200 fs wavelength-tunable pulses with multimilliwatt output power and exceptionally low noise figure an order of magnitude lower than the traditional wavelength tunable supercontinuum-based femtosecond sources. The applications for Cherenkov laser systems in practical biophotonics and biomedical applications, such as bio-imaging and microscopy, are discussed.

  1. Progress in Cherenkov femtosecond fiber lasers.

    PubMed

    Liu, Xiaomin; Svane, Ask S; Lægsgaard, Jesper; Tu, Haohua; Boppart, Stephen A; Turchinovich, Dmitry

    2016-01-20

    We review the recent developments in the field of ultrafast Cherenkov fiber lasers. Two essential properties of such laser systems - broad wavelength tunability and high efficiency of Cherenkov radiation wavelength conversion are discussed. The exceptional performance of the Cherenkov fiber laser systems are highlighted - dependent on the realization scheme, the Cherenkov lasers can generate the femtosecond output tunable across the entire visible and even the UV range, and for certain designs more than 40 % conversion efficiency from the pump to Cherenkov signal can be achieved. The femtosecond Cherenkov laser with all-fiber architecture is presented and discussed. Operating in the visible range, it delivers 100-200 fs wavelength-tunable pulses with multimilliwatt output power and exceptionally low noise figure an order of magnitude lower than the traditional wavelength tunable supercontinuum-based femtosecond sources. The applications for Cherenkov laser systems in practical biophotonics and biomedical applications, such as bio-imaging and microscopy, are discussed.

  2. Fiber laser for high speed laser transfer printing

    NASA Astrophysics Data System (ADS)

    Petkovšek, Rok; Novak, Vid; Agrež, Vid

    2017-01-01

    High speed industrial laser transfer printing requires high power lasers that can deliver pulses on demand and having arbitrary pulse duration in range of few nanoseconds to milliseconds or more. A special kind of MOPA fiber laser is presented using wavelength multiplexing to achieve pulses on demand with minimal transients. The system is further tested in printing application.

  3. Multiplexed fiber-ring laser sensors for ultrasonic detection.

    PubMed

    Liu, Tongqing; Hu, Lingling; Han, Ming

    2013-12-16

    We propose and demonstrate a multiplexing method for ultrasonic sensors based on fiber Bragg gratings (FBGs) that are included inside the laser cavity of a fiber-ring laser. The multiplexing is achieved using add-drop filters to route the light signals, according to their wavelengths, into different optical paths, each of which contains a separate span of erbium-doped fiber (EDF) as the gain medium. Because a specific span of EDF only addresses a single wavelength channel, mode completion is avoided and the FBG ultrasonic sensors can be simultaneously demodulated. The proposed method is experimentally demonstrated using a two-channel system with two sensing FBGs in a single span of fiber.

  4. Yb-fiber-laser-pumped, high-repetition-rate picosecond optical parametric oscillator tunable in the ultraviolet.

    PubMed

    Samanta, G K; Kumar, S Chaitanya; Aadhi, A; Ebrahim-Zadeh, M

    2014-05-19

    We report a compact tunable 240-MHz picosecond source for the ultraviolet based on intra-cavity frequency doubling of a signal-resonant MgO:sPPLT optical parametric oscillator (OPO), synchronously pumped at 532 nm in the green by the second harmonic of a mode-locked Yb-fiber laser at 80-MHz repetition rate. By deploying a 30-mm-long multi-grating MgO:sPPLT crystal for the OPO and a 5-mm-long BiB(3)O(6) crystal for internal doubling, we have generated tunable UV radiation across 317-340.5 nm, with up to 30 mW at 334.5 nm. The OPO also provides tunable visible signal in the red, across 634-681 nm, and mid-infrared idler radiation over 2429-3298 nm, with as maximum signal power of 800 mW at 642 nm. The signal pulses have a temporal duration of 12 ps at 665 nm and exhibit high spatial beam quality with Gaussian profile. The signal power is recorded to be naturally stable with a fluctuation of 1.4% rms over 14 hours, while UV power degradation has been observed and studied.

  5. Supercontinuum generation in polarization maintaining photonic crystal fiber by using various harmonics of sub-nanosecond Q-switched laser

    NASA Astrophysics Data System (ADS)

    Vengelis, Julius; Jarutis, Vygandas; Sirutkaitis, Valdas

    2016-04-01

    We present results of supercontinuum generation in highly nonlinear polarization maintaining photonic crystal fiber using various harmonics of sub-nanosecond passively Q-switched Nd:YAG microlaser. The pump source was a Nd:YAG microlaser generating 50 μJ energy 300 ps duration pulses at 1064 nm with kilohertz repetition rate. We demonstrated that we can expand the supercontinuum spectrum to cover the whole visible range and beyond using either first or second harmonic of our pump laser in simple experimental setups: supercontinuum extended from 400 nm to 1300 nm in case of λp = 1064 nm and from 400 nm to 900 nm in case of λp = 532 nm. We compared supercontinuum evolution and dependence on pump pulse energy in both cases. We also performed numerical simulations of supercontinuum generation in PCF by applying the traditional approach of solving generalized nonlinear Schrödinger equation (GNLSE) and also presented a new numerical simulation approach -deriving and solving equation for evolution of spectral components of pulse propagating in the PCF. In case of GNLSE approach, the simulated supercontinuum spectra display the same qualitative features as the ones measured in the experiment.

  6. Thulium fiber laser lithotripsy using small spherical distal fiber tips

    NASA Astrophysics Data System (ADS)

    Wilson, Christopher R.; Hardy, Luke A.; Kennedy, Joshua D.; Irby, Pierce B.; Fried, Nathaniel M.

    2016-02-01

    This study tests a 100-μm-core fiber with 300-μm-diameter ball tip during Thulium fiber laser (TFL) lithotripsy. The TFL was operated at 1908 nm wavelength with 35-mJ pulse energy, 500-μs pulse duration, and 300-Hz pulse rate. Calcium oxalate/phosphate stone samples were weighed, laser procedure times measured, and ablation rates calculated for ball tip fibers, with comparison to bare tip fibers. Photographs of ball tips were taken before and after each procedure to observe ball tip degradation and determine number of procedures completed before need to replace fiber. Saline irrigation rates and ureteroscope deflection were measured with and without TFL fiber present. There was no statistical difference (P > 0.05) between stone ablation rates for single-use ball tip fiber (1.3 +/- 0.4 mg/s) (n=10), multiple-use ball tip fiber (1.3 +/- 0.5 mg/s) (n=44), and conventional single-use bare tip fibers (1.3 +/- 0.2 mg/s) (n=10). Ball tip durability varied widely, but fibers averaged > 4 stone procedures before decline in stone ablation rates due to mechanical damage at front surface of ball tip. The small fiber diameter did not impact ureteroscope deflection or saline flow rates. The miniature ball tip fiber may provide a cost-effective design for safe fiber insertion through the ureteroscope working channel and the ureter without risk of scope damage or tissue perforation, and without compromising stone ablation efficiency during TFL ablation of kidney stones.

  7. Wideband ultrafast fiber laser sources for OCT and metrology

    NASA Astrophysics Data System (ADS)

    Nishizawa, Norihiko

    2016-09-01

    Fiber lasers, which use optical fibers as ideal waveguides, have been attracting a great deal of attention as stable, practical, and maintenance-free lasers. Using a combination of an ultrashort-pulse fiber laser and a nonlinear fiber, we can realize wideband highly functional ultrafast fiber laser sources. The generation of ultrashort pulses with wide wavelength tunability and supercontinua based on fiber lasers and nonlinear fibers has been demonstrated. These techniques are useful for laser applications, especially for imaging and metrology. In this topical review, the fundamentals of and recent progress in wideband ultrafast fiber laser sources and their applications are reviewed mainly based on the author’s work. First, a new pulse source based on a passively-mode-locked ultrashort-pulse fiber laser using carbon nanotubes is explained. Next, the development of wideband ultrafast fiber laser sources and their applications in ultrahigh-resolution optical coherence tomography, optical frequency combs, and nonlinear microscopy are reviewed.

  8. Frequency Doubling In Raman Fiber Lasers

    DTIC Science & Technology

    2009-02-01

    into the fiber . Recenlly 1 0 kW CW YFL system appears on the market (ILR-100(){] by IPG Photonics Corp., USA). In splle of the outstanding advances in...germanosilicate (GeO2/SiO2) ones is 3 times larger Stokes shift, therefore is possible to convert powerful Yb-doped fiber laser (YDFL) pump radiation at...one used in tunable RFL configuration [8]. The YDFL is pumped by 3 laser diodes (LDs) and delivers up to 13.8 W at ~1.11 µm via output fiber Bragg

  9. Multi-wavelength narrow linewidth fiber laser based on distributed feedback fiber lasers

    NASA Astrophysics Data System (ADS)

    Lv, Jingsheng; Qi, Haifeng; Song, Zhiqiang; Guo, Jian; Ni, Jiasheng; Wang, Chang; Peng, Gangding

    2016-09-01

    A narrow linewidth laser configuration based on distributed feedback fiber lasers (DFB-FL) with eight wavelengths in the international telecommunication union (ITU) grid is presented and realized. In this laser configuration, eight phase-shifted gratings in series are bidirectionally pumped by two 980-nm laser diodes (LDs). The final laser output with over 10-mW power for each wavelength can be obtained, and the maximum power difference within eight wavelengths is 1.2 dB. The laser configuration with multiple wavelengths and uniform power outputs can be very useful in large scaled optical fiber hydrophone fields.

  10. Comparison of fiber lasers based on distributed side-coupled cladding-pumped fibers and double-cladding fibers.

    PubMed

    Huang, Zhihe; Cao, Jianqiu; Guo, Shaofeng; Chen, Jinbao; Xu, Xiaojun

    2014-04-01

    We compare both analytically and numerically the distributed side-coupled cladding-pumped (DSCCP) fiber lasers and double cladding fiber (DCF) lasers. We show that, through optimization of the coupling and absorbing coefficients, the optical-to-optical efficiency of DSCCP fiber lasers can be made as high as that of DCF lasers. At the same time, DSCCP fiber lasers are better than the DCF lasers in terms of thermal management.

  11. Actively mode-locked Raman fiber laser.

    PubMed

    Yang, Xuezong; Zhang, Lei; Jiang, Huawei; Fan, Tingwei; Feng, Yan

    2015-07-27

    Active mode-locking of Raman fiber laser is experimentally investigated for the first time. An all fiber connected and polarization maintaining loop cavity of ~500 m long is pumped by a linearly polarized 1120 nm Yb fiber laser and modulated by an acousto-optic modulator. Stable 2 ns width pulse train at 1178 nm is obtained with modulator opening time of > 50 ns. At higher power, pulses become longer, and second order Raman Stokes could take place, which however can be suppressed by adjusting the open time and modulation frequency. Transient pulse evolution measurement confirms the absence of relaxation oscillation in Raman fiber laser. Tuning of repetition rate from 392 kHz to 31.37 MHz is obtained with harmonic mode locking.

  12. Laser fiber optics ordnance initiation system

    NASA Technical Reports Server (NTRS)

    Yang, L. C.

    1976-01-01

    Recent progress on system development in the laser initiation of explosive devices is summarized. The topics included are: development of compact free-running mode and Q-switched lasers, development of low-loss fiber optic bundles and connectors, study of nuclear radiation effects on the system, characterization of laser initiation sensitivities of insensitive high explosives, and the design methods used to achieve attractive system weight and cost savings. Direction for future work is discussed.

  13. Photonic crystal fiber amplifiers for high power ultrafast fiber lasers

    NASA Astrophysics Data System (ADS)

    Alkeskjold, Thomas T.; Laurila, Marko; Weirich, Johannes; Johansen, Mette M.; Olausson, Christina B.; Lumholt, Ole; Noordegraaf, Danny; Maack, Martin D.; Jakobsen, Christian

    2013-12-01

    In recent years, ultrafast laser systems using large-mode-area fiber amplifiers delivering several hundreds of watts of average power has attracted significant academic and industrial interest. These amplifiers can generate hundreds of kilowatts to megawatts of peak power using direct amplification and multi-gigawatts of peak power using pulse stretching techniques. These amplifiers are enabled by advancements in Photonic Crystal Fiber (PCF) design and manufacturing technology. In this paper, we will give a short overview of state-of-the-art PCF amplifiers and describe the performance in ultrafast ps laser systems.

  14. Femtosecond fiber laser additive manufacturing of tungsten

    NASA Astrophysics Data System (ADS)

    Bai, Shuang; Liu, Jian; Yang, Pei; Zhai, Meiyu; Huang, Huan; Yang, Lih-Mei

    2016-04-01

    Additive manufacturing (AM) is promising to produce complex shaped components, including metals and alloys, to meet requirements from different industries such as aerospace, defense and biomedicines. Current laser AM uses CW lasers and very few publications have been reported for using pulsed lasers (esp. ultrafast lasers). In this paper, additive manufacturing of Tungsten materials is investigated by using femtosecond (fs) fiber lasers. Various processing conditions are studied, which leads to desired characteristics in terms of morphology, porosity, hardness, microstructural and mechanical properties of the processed components. Fully dense Tungsten part with refined grain and increased hardness was obtained and compared with parts made with different pulse widths and CW laser. The results are evidenced that the fs laser based AM provides more dimensions to modify mechanical properties with controlled heating, rapid melting and cooling rates compared with a CW or long pulsed laser. This can greatly benefit to the make of complicated structures and materials that could not be achieved before.

  15. Compact Fiber Laser for 589nm Laser Guide Star Generation

    NASA Astrophysics Data System (ADS)

    Pennington, D.; Drobshoff, D.; Mitchell, S.; Brown, A.

    Laser guide stars are crucial to the broad use of astronomical adaptive optics, because they facilitate access to a large fraction of possible locations on the sky. Lasers tuned to the 589 nm atomic sodium resonance can create an artificial beacon at altitudes of 95-105 km, thus coming close to reproducing the light path of starlight. The deployment of multiconjugate adaptive optics on large aperture telescopes world-wide will require the use of three to nine sodium laser guide stars in order to achieve uniform correction over the aperture with a high Strehl value. Current estimates place the minimum required laser power at > 10 W per laser for a continuous wave source, though a pulsed format, nominally 6?s in length at ~ 16.7 kHz, is currently preferred as it would enable tracking the laser through the Na layer to mitigate spot elongation. The lasers also need to be compact, efficient, robust and turnkey. We are developing an all-fiber laser system for generating a 589 nm source for laser-guided adaptive optics. Fiber lasers are more compact and insensitive to alignment than their bulk laser counterparts, and the heat-dissipation characteristics of fibers, coupled with the high efficiencies demonstrated and excellent spatial mode characteristics, make them a preferred candidate for many high power applications. Our design is based on sum-frequency mixing an Er/Yb:doped fiber laser operating at 1583 nm with a 938 nm Nd:silica fiber laser in a periodically poled crystal to generate 589 nm. We have demonstrated 14 W at 1583 nm with an Er/Yb:doped fiber laser, based on a Koheras single frequency fiber oscillator amplified in an IPG Photonics fiber amplifier. The Nd:silica fiber laser is a somewhat more novel device, since the Nd3+ ions must operate on the resonance transition (i.e. 4F3/2-4I9/2), while suppressing ASE losses at the more conventional 1088 nm transition. Optimization of the ratio of the fiber core and cladding permits operation of the laser at room

  16. Ho:YLF Laser Pumped by TM:Fiber Laser

    NASA Astrophysics Data System (ADS)

    Mizutani, Kohei; Ishii, Shoken; Itabe, Toshikazu; Asai, Kazuhiro; Sato, Atsushi

    2016-06-01

    A 2-micron Ho:YLF laser end-pumped by 1.94-micron Tm:fiber laser is described. A ring resonator of 3m length is adopted for the oscillator. The laser is a master oscillator and an amplifier system. It is operated at high repetition rate of 200-5000 Hz in room temperature. The laser outputs were about 9W in CW and more than 6W in Q-switched operation. This laser was developed to be used for wind and CO2 measurements.

  17. Technology and applications of ultrafast fiber lasers

    NASA Astrophysics Data System (ADS)

    Lang, Marion; Hellerer, Thomas; Stuhler, Juergen

    2012-03-01

    We briefly review the key technology of modern fiber based femtosecond laser sources summarizing advantages and disadvantages of different mode-locking solutions. A description of possible extensions of a FemtoFiber-type modelocked Er-doped fiber laser oscillator (1560 nm) reveals the flexibility with respect to wavelength coverage (488 nm .. 2200 nm) and pulse duration (10 fs .. 10 ps). The resulting FemtoFiber family and its versions for instrument integration allow one to use these state-of-the-art light sources in many important applications, e.g. THz spectroscopy and microscopy. We show that, depending on the fiber laser model and the THz emitter, THz radiation can be produced with 4-10 THz bandwidth and detected with up to 60 dB signal-to-noise ratio (SNR). Electronically controlled optical scanning (ECOPS) - a unique method for fast, precise and comfortable sampling of the THz pulse or other pump-probe experiments - is described and recommended for efficient data acquisition. As examples for modern microscopy with ultrafast fiber lasers we present results of two-photon fluorescence, coherent microscopy techniques (SHG/THG/CARS) and fluorescence lifetime imaging (FLIM).

  18. Technology and applications of ultrafast fiber lasers

    NASA Astrophysics Data System (ADS)

    Lang, Marion; Hellerer, Thomas; Stuhler, Juergen

    2011-11-01

    We briefly review the key technology of modern fiber based femtosecond laser sources summarizing advantages and disadvantages of different mode-locking solutions. A description of possible extensions of a FemtoFiber-type modelocked Er-doped fiber laser oscillator (1560 nm) reveals the flexibility with respect to wavelength coverage (488 nm .. 2200 nm) and pulse duration (10 fs .. 10 ps). The resulting FemtoFiber family and its versions for instrument integration allow one to use these state-of-the-art light sources in many important applications, e.g. THz spectroscopy and microscopy. We show that, depending on the fiber laser model and the THz emitter, THz radiation can be produced with 4-10 THz bandwidth and detected with up to 60 dB signal-to-noise ratio (SNR). Electronically controlled optical scanning (ECOPS) - a unique method for fast, precise and comfortable sampling of the THz pulse or other pump-probe experiments - is described and recommended for efficient data acquisition. As examples for modern microscopy with ultrafast fiber lasers we present results of two-photon fluorescence, coherent microscopy techniques (SHG/THG/CARS) and fluorescence lifetime imaging (FLIM).

  19. Next Generation Large Mode Area Fiber Technologies for High Power Fiber Laser Arrays

    DTIC Science & Technology

    2012-06-08

    REPORT Next Generation Large Mode Area Fiber Technologies for High Power Fiber Laser Arrays 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: This program...monolithically-integrated building blocks (individual laser channels) of high power beam-combined fiber laser arrays. Robust single-mode performance...of CCC fibers with core sizes of up to ~60?m has been rigorously demonstrated. Various CCC fiber based high power lasers have been also

  20. Laser cleaning of 19th century Congo rattan mats

    NASA Astrophysics Data System (ADS)

    Carmona, N.; Oujja, M.; Roemich, H.; Castillejo, M.

    2011-09-01

    There is a growing interest by art conservators for laser cleaning of organic materials, such as wooden artworks, paper and textiles, since traditional cleaning with solvents can be a source of further decay and mechanical cleaning may be too abrasive for sensitive fibers. In this work we present a successful laser cleaning approach for 19th century rattan mats from the Brooklyn Museum collection of African Art, now part of the study collection at the Conservation Center in New York. Tests were carried out using the fundamental (1064 nm) and second harmonic (532 nm) wavelength of a Q-switched Nd:YAG laser to measure threshold values both for surface damage and color changes for different types of rattan samples. The irradiated substrates were investigated by optical microscopy, scanning electron microscopy and by UV-vis spectroscopy in order to determine the efficiency of laser cleaning and to assess possible deterioration effects that may have occurred as a result of laser irradiation. The study showed that by using the laser emission at 532 nm, a wavelength for which photon energy is below the bond dissociation level of the main cellulosic compounds and the water absorption is negligible, it is possible to select a range of laser fluences to remove the black dust layer without damaging the rattan material.

  1. Ceramic bracket debonding with ytterbium fiber laser.

    PubMed

    Sarp, Ayşe Sena Kabaş; Gülsoy, Murat

    2011-09-01

    Since the early 1990 s, lasers have been used experimentally for debonding ceramic brackets. Lasers reduce the required debonding force and risk of enamel damage. However, the thermal effect during the laser radiation on dental tissues can cause undesirable results. The aim of this study is to develop a laser debonding technique for ceramic brackets that is better than mechanical debonding and also to minimize the side-effects of laser applications. A new fiber laser (1,070-nm ytterbium fiber laser) was tested, debonding procedure was quantified with a universal testing machine, and intrapulpal temperature was monitored for limiting the injury or pain. Experiments were performed in two sections according to the type of lasing mode: continuous wave (CW) and modulated mode. In continuous wave (CW) mode, a laser was applied on samples with different constant power levels continuously. In the second set of experiments, brackets were irradiated in modulated mode, in which the laser energy was delivered with on-and-off cycles. Laser power and duty cycles were adjusted by controlling the current, which was set to 4.99 A of current for 18 W of emission. Debonding force, debonding time, and work done by a universal testing machine were all significantly decreased for both modalities of laser irradiation compared to the control group. When laser parameters were set to proper doses, a 50% of reduction in required load for debonding and a three-fold decrease in debonding time were observed. Intrapulpal temperature changes were below the accepted threshold value (5.5°C) until the level of 3.5 W of laser power in continuous wave mode. During debonding, the work done by the universal testing machine is decreased up to five times by irradiation. Parameters were compared for both modes of operations and it was concluded that modulated mode laser application (Group 300/900) provided faster and easier debonding with less temperature change.

  2. 100 W all fiber picosecond MOPA laser.

    PubMed

    Chen, Sheng-Ping; Chen, Hong-Wei; Hou, Jing; Liu, Ze-Jin

    2009-12-21

    A high power picosecond laser is constructed in an all fiber master oscillator power amplifier (MOPA) configuration. The seed source is an ytterbium-doped single mode fiber laser passively mode-locked by a semiconductor saturable absorber mirror (SESAM). It produces 20 mW average power with 13 ps pulse width and 59.8 MHz repetition rate. A direct amplification of this seed source encounters obvious nonlinear effects hence serious spectral broadening at only ten watt power level. To avoid these nonlinear effects, we octupled the repetition rate to about 478 MHz though a self-made all fiber device before amplification. The ultimate output laser exhibits an average power of 96 W, a pulse width of 16 ps, a beam quality M2 of less than 1.5, and an optical conversion efficiency of 61.5%.

  3. High-efficiency fiber laser at 1018 nm using Yb-doped phosphosilicate fiber.

    PubMed

    Wang, Jianhua; Chen, Gui; Zhang, Lei; Hu, Jinmeng; Li, Jinyan; He, Bing; Chen, Jinbao; Gu, Xijia; Zhou, Jun; Feng, Yan

    2012-10-10

    A high-efficiency fiber laser at 1018 nm using homemade Yb-doped phosphosilicate fiber is demonstrated. The fiber shows blueshifted emission spectrum compared to Yb-doped aluminosilicate fiber, and is considered favorable for the short wavelength Yb-doped fiber laser. With a 7 m gain fiber, up to 22.8 W output at 1018 nm is achieved with an optical efficiency of 53%. The amplified spontaneous emission at 1030 nm is suppressed to 50 dB below the 1018 nm laser. This work shows that highly-efficient fiber laser at 1018 nm can be obtained with Yb-doped phosphosilicate fiber.

  4. Through nanohole formation in thin metallic film by single nanosecond laser pulses using optical dielectric apertureless probe.

    PubMed

    Kulchin, Y N; Vitrik, O B; Kuchmizhak, A A; Nepomnyashchii, A V; Savchuk, A G; Ionin, A A; Kudryashov, S I; Makarov, S V

    2013-05-01

    Separate nanoholes with the minimum size down to 35 nm (~λ/15) and nanohole arrays with the hole size about 100 nm (~λ/5) were fabricated in a 50 nm optically "thick" Au/Pd film, using single 532 nm pump nanosecond laser pulses focused to diffraction-limited spots by a specially designed apertureless dielectric fiber probe. Nanohole fabrication in the metallic film was found to result from lateral heat diffusion and center-symmetrical lateral expulsion of the melt by its vapor recoil pressure. The optimized apertureless dielectric microprobe was demonstrated to enable laser fabrication of deep through nanoholes.

  5. Advanced specialty fiber designs for high power fiber lasers

    NASA Astrophysics Data System (ADS)

    Gu, Guancheng

    The output power of fiber lasers has increased rapidly over the last decade. There are two major limiting factors, namely nonlinear effects and transverse mode instability, prohibiting the power scaling capability of fiber lasers. The nonlinear effects, originating from high optical intensity, primarily limit the peak power scaling. The mode instability, on the other hand, arises from quantum-defect driven heating, causing undesired mode coupling once the power exceeds the threshold and degradation of beam quality. The mode instability has now become the bottleneck for average output power scaling of fiber lasers. Mode area scaling is the most effective way to mitigate nonlinear effects. However, the use of large mode area may increase the tendency to support multiple modes in the core, resulting in lower mode instability threshold. Therefore, it is critical to maintain single mode operation in a large mode area fiber. Sufficient higher order mode suppression can lead to effective single-transverse-mode propagation. In this dissertation, we explore the feasibility of using specialty fiber to construct high power fiber lasers with robust single-mode output. The first type of fiber discussed is the resonantly-enhanced leakage channel fiber. Coherent reflection at the fiber outer boundary can lead to additional confinement especially for highly leaky HOM, leading to lower HOM losses than what are predicted by conventional finite element mothod mode solver considering infinite cladding. In this work, we conducted careful measurements of HOM losses in two leakage channel fibers (LCF) with circular and rounded hexagonal boundary shapes respectively. Impact on HOM losses from coiling, fiber boundary shapes and coating indexes were studied in comparison to simulations. This work demonstrates the limit of the simulation method commonly used in the large-mode-area fiber designs and the need for an improved approach. More importantly, this work also demonstrates that a

  6. A Hybrid Fiber/Solid-State Regenerative Amplifier with Tunable Pulse Widths for Satellite Laser Ranging

    NASA Technical Reports Server (NTRS)

    Coyle, Barry; Poulios, Demetrios

    2013-01-01

    crystal, approx. = 2.1 W of 532-nm output (>1 mJ) was measured. This corresponds to a nonlinear conversion efficiency of >60%. Furthermore, by pulse pumping this system, a single pulse per laser shot can be created for the SLR (satellite laser ranging) measurement, and this can be ejected into the instrument. This is operated at the precise frequency needed by the measurement, as opposed to commercial short-pulsed, mode-locked systems that need to operate in a continuous fashion, or CW (continuous wave), and create pulses at many MHz. Therefore, this design does not need to throw away or dump 99% of the laser energy to produce what is required; this system can be far smaller, more efficient, cheaper, and readily deployed in the field when packaged efficiently. Finally, by producing custom diode seed pulses electronically, two major advantages over commercial systems are realized: First, this pulse shape is customizable and not affected by the cavity length or gain of the amplifier cavity, and second, it can produce adjustable (selectable) pulse widths by simply adding multiple seed diodes and coupling each into commercial, low-cost fiber-optic combiners.

  7. CO2-Laser Cutting Fiber Reinforced Polymers

    NASA Astrophysics Data System (ADS)

    Mueller, R.; Nuss, Rudolf; Geiger, Manfred

    1989-10-01

    Guided by experimental investigations laser cutting of glass fiber reinforced reactive injection moulded (RRIM)-polyurethanes which are used e.g. in car industry for bumpers, spoilers, and further components is described. A Comparison with other cutting techniques as there are water jet cutting, milling, punching, sawing, cutting with conventional knife and with ultrasonic excited knife is given. Parameters which mainly influence cutting results e.g. laser power, cutting speed, gas nature and pressure will be discussed. The problematic nature in characterising micro and macro geometry of laser cut edges of fiber reinforced plastic (FRP) is explained. The topography of cut edges is described and several characteristic values are introduced to specify the obtained working quality. The surface roughness of laser cut edges is measured by both, an optical and a mechanical sensor and their reliabilities are compared.

  8. Robust synchronization in fiber laser arrays.

    PubMed

    Peles, Slaven; Rogers, Jeffrey L; Wiesenfeld, Kurt

    2006-02-01

    Synchronization of coupled fiber lasers has been reported in recent experiments [Bruesselbach, Opt. Lett. 30, 1339 (2005); Minden, Proc. SPIE 5335, 89 (2004)]. While these results may lead to dramatic advances in laser technology, the mechanism by which these lasers synchronize is not understood. We analyze a recently proposed [Rogers, IEEE J. Quantum Electron. 41, 767 (2005)] iterated map model of fiber laser arrays to explore this phenomenon. In particular, we look at synchronous solutions of the maps when the gain fields are constant. Determining the stability of these solutions is analytically tractable for a number of different coupling schemes. We find that in the most symmetric physical configurations the most symmetric solution is either unstable or stable over insufficient parameter range to be practical. In contrast, a lower symmetry configuration yields surprisingly robust coherence. This coherence persists beyond the pumping threshold for which the gain fields become time dependent.

  9. Fiber Bragg grating inscription with UV femtosecond exposure and two beam interference for fiber laser applications

    NASA Astrophysics Data System (ADS)

    Becker, Martin; Brückner, Sven; Lindner, Eric; Rothhardt, Manfred; Unger, Sonja; Kobelke, Jens; Schuster, Kay; Bartelt, Hartmut

    2010-06-01

    Fiber Bragg grating based fiber lasers are promising for stable all fiber laser solutions. Standard methods for fiber Bragg gratings in fiber lasers apply germanium doped passive fibers which are connected to the amplifier section of the fiber laser with a splice. The connection is usually recoated using a low-index polymer coating to maintain guidance properties for the pump light. At high pump powers the spliced connections are affected by absorbed pump light and are prone to thermal degradation. Fiber Bragg gratings made with femtosecond laser exposure allow the direct inscription of resonator mirrors for fiber lasers into the amplifying section of the fiber laser. Such a technology has a number of advantages. The number of splices in the laser cavity is reduced. Fiber Bragg grating inscription does not relay on hydrogenation to increase the photosensitivity of the fiber. This is of special interest since hydrogen loading in large mode area fibers is a time consuming procedure due to the diffusion time of hydrogen in silica glass. Finally, one gets direct access to fiber Bragg gratings in air-clad fibers. In this paper we use a two beam interferometric inscription setup in combination with an frequency tripled femtosecond laser for grating inscription. It allows to write fiber Bragg gratings in rare earth doped fibers with a reflection wavelength span that covers the Ytterbium amplification band. Reflections with values higher than 90% have been realized.

  10. Hybrid fiber-rod laser

    DOEpatents

    Beach, Raymond J.; Dawson, Jay W.; Messerly, Michael J.; Barty, Christopher P. J.

    2012-12-18

    Single, or near single transverse mode waveguide definition is produced using a single homogeneous medium to transport both the pump excitation light and generated laser light. By properly configuring the pump deposition and resulting thermal power generation in the waveguide device, a thermal focusing power is established that supports perturbation-stable guided wave propagation of an appropriately configured single or near single transverse mode laser beam and/or laser pulse.

  11. Supercontinuum fiber lasers: new developments and applications

    NASA Astrophysics Data System (ADS)

    Devine, Adam; Hooper, Lucy; Clowes, John

    2016-05-01

    In this talk we give an overview of recent advances in the development of high power supercontinuum fiber lasers with powers exceeding 50W and spectral brightness of tens of mW/nm. We also discuss the fundamental limitations of power scaling and spectral broadening and review the existing and emerging applications of this unique light source which combines the broadband properties of a light bulb with the spatial properties of a laser.

  12. High-performance iodine fiber frequency standard.

    PubMed

    Lurie, Anna; Baynes, Fred N; Anstie, James D; Light, Philip S; Benabid, Fetah; Stace, Thomas M; Luiten, Andre N

    2011-12-15

    We have constructed a compact and robust optical frequency standard based around iodine vapor loaded into the core of a hollow-core photonic crystal fiber (HC-PCF). A 532 nm laser was frequency locked to one hyperfine component of the R(56) 32-0 (127)I(2) transition using modulation transfer spectroscopy. The stabilized laser demonstrated a frequency stability of 2.3×10(-12) at 1 s, almost an order of magnitude better than previously reported for a laser stabilized to a gas-filled HC-PCF. This limit is set by the shot noise in the detection system. We present a discussion of the current limitations to the performance and a route to improve the performance by more than an order of magnitude.

  13. Fiber Optic Solutions for Short Pulse Lasers

    SciTech Connect

    Beach, R; Dawson, J; Liao, Z; Jovanovic, I; Wattellier, B; Payne, S; Barty, C P

    2003-01-29

    For applications requiring high beam quality radiation from efficient, compact and rugged sources, diffraction limited fiber lasers are ideal, and to date have been demonstrated at average CW power levels exceeding 100 W with near diffraction limited: output. For conventional single-core step-index single-mode fibers, this power level represents the sealing limit because of nonlinear and laser damage considerations. Higher average powers would exceed nonlinear process thresholds such as the Raman and stimulated Brillouin scattering limit, or else damage the fiber due to the high intensity level in the fiber's core. The obvious way to increase the average power capability of fibers is to increase the area of their core. Simply expanding the core dimensions of the fiber allows a straightforward power sealing due to enhanced nonlinear and power handling characteristics that scale directly with the core area. Femtosecond, chirped-pulse, fiber lasers with pulse energies greater than 1mJ have been demonstrated in the literature [2] using this technique. This output energy was still limited by the onset of stimulated Raman scattering. We have pursued an alternative and complimentary approach which is to reduce the intensity of light propagating in the core by distributing it more evenly across the core area via careful design of the refractive index profile [3]. We have also sought to address the primary issue that results from scaling the core. The enhanced power handling capability comes at the expense of beam quality, as increasing the core diameter in standard step index fibers permits multiple transverse modes to lase simultaneously. Although this problem of multimode operation can be mitigated to some extent by appropriately designing the fiber's waveguide structure, limitations such as bend radius loss, sensitivity to thermally induced perturbations of the waveguide structure, and refractive index control, all become more stringent as the core diameter grows

  14. Hybrid Fiber-Bulk Pulsed Erbium Laser

    DTIC Science & Technology

    2007-11-02

    Judd - Ofelt analysis (for radiative lifetimes) and the gap law (for non-radiative transitions by phonon emission). In both calculations, we have...3.6 Prospects for further power scaling 4.0 Fiber laser pumped Er:YAG laser 4.1 Introduction 4.2 Er:YAG laser design 4.3 Effect of Er3 ...procedure, so it is extremely important to identify the main factors affecting the overall efficiency. Er3 + and Yb3+ ion concentrations and background

  15. Fiber ring laser with a feedback mirror.

    PubMed

    Abitan, H; Bohr, H; Pedersen, C F

    2005-12-20

    We describe the spectral and power features of a ytterbium-doped double-clad photonic crystal fiber laser that is operated in a ring configuration with an external mirror that feeds back only one of its two output beams. We compare the operation of the laser with and without an external feedback mirror. We find that the feedback mirror reduces significantly the spectral and power fluctuations. It is also responsible for an interesting spectral phenomenon: The laser frequency is drifting periodically over 9 nm at a rate of 2 nm/s from a short wavelength to a longer wavelength and vice versa.

  16. Reverse spontaneous laser line sweeping in ytterbium fiber laser

    NASA Astrophysics Data System (ADS)

    Navratil, P.; Peterka, P.; Honzatko, P.; Kubecek, V.

    2017-03-01

    Self-induced laser line sweeping of various regimes of sweep direction is reported for an experimental ytterbium fiber laser. The regimes involve sweeping from shorter to longer wavelengths (1076~\\text{nm}\\to 1083 nm)—so-called normal self-sweeping; from longer to shorter wavelengths (1079~\\text{nm}\\to 1073 nm)—so-called reverse self-sweeping; and a mixed regime in which a precarious balance of the normal and reverse sweeping exists and the sweep direction can change between consecutive sweeps. The regimes of sweeping were selected by changing the pump wavelength only. A detailed explanation of this sweep direction dynamics is presented based on a semi-empirical model. This model also provides a way to predict the sweep direction of fiber lasers based on other rare-earth-doped laser media.

  17. Ribbon Fiber Laser-Theory and Experiment

    SciTech Connect

    Beach, R J; Feit, M D; Brasure, L D; Payne, S A

    2002-05-10

    A scalable fiber laser approach is described based on phase-locking multiple gain cores in an antiguided structure. The waveguide is comprised of periodic sequences of gain- and no-gain-loaded segments having uniform index, within the cladding region. Initial experimental results are presented.

  18. Wavelength-codified fiber laser hydrogen detector

    NASA Astrophysics Data System (ADS)

    Ortigosa-Blanch, A.; Díez, A.; González-Segura, A.; Cruz, J. L.; Andrés, M. V.

    2005-11-01

    We report a scheme for an optical hydrogen detector that codifies the information in wavelength. The system is based on an erbium-doped fiber laser with two coupled cavities and a Palladium-coated tapered fiber within one of the laser cavities. The tapered fiber acts as the hydrogen-sensing element. When the sensing element is exposed to a hydrogen atmosphere, its attenuation decreases changing the cavity losses. This change leads the system to switch lasing from the wavelength of the auxiliary cavity to the characteristic wavelength of the cavity which contains the sensing element. The detection level can be shifted by adjusting the reflective elements of the cavity containing the sensing element.

  19. Powerful narrow linewidth random fiber laser

    NASA Astrophysics Data System (ADS)

    Ye, Jun; Xu, Jiangming; Zhang, Hanwei; Zhou, Pu

    2016-11-01

    In this paper, we demonstrate a narrow linewidth random fiber laser, which employs a tunable pump laser to select the operating wavelength for efficiency optimization, a narrow-band fiber Bragg grating (FBG) and a section of single mode fiber to construct a half-open cavity, and a circulator to separate pump light input and random lasing output. Spectral linewidth down to 42.31 GHz is achieved through filtering by the FBG. When 8.97 W pump light centered at the optimized wavelength 1036.5 nm is launched into the half-open cavity, 1081.4 nm random lasing with the maximum output power of 2.15 W is achieved, which is more powerful than the previous reported results.

  20. Powerful narrow linewidth random fiber laser

    NASA Astrophysics Data System (ADS)

    Ye, Jun; Xu, Jiangming; Zhang, Hanwei; Zhou, Pu

    2017-03-01

    In this paper, we demonstrate a narrow linewidth random fiber laser, which employs a tunable pump laser to select the operating wavelength for efficiency optimization, a narrow-band fiber Bragg grating (FBG) and a section of single mode fiber to construct a half-open cavity, and a circulator to separate pump light input and random lasing output. Spectral linewidth down to 42.31 GHz is achieved through filtering by the FBG. When 8.97 W pump light centered at the optimized wavelength 1036.5 nm is launched into the half-open cavity, 1081.4 nm random lasing with the maximum output power of 2.15 W is achieved, which is more powerful than the previous reported results.

  1. Electrically tunable liquid crystal photonic bandgap fiber laser

    NASA Astrophysics Data System (ADS)

    Olausson, Christina B.; Scolari, Lara; Wei, Lei; Noordegraaf, Danny; Weirich, Johannes; Alkeskjold, Thomas T.; Hansen, Kim P.; Bjarklev, Anders

    2010-02-01

    We demonstrate electrical tunability of a fiber laser using a liquid crystal photonic bandgap fiber. Tuning of the laser is achieved by combining the wavelength filtering effect of a liquid crystal photonic bandgap fiber device with an ytterbium-doped photonic crystal fiber. We fabricate an all-spliced laser cavity based on a liquid crystal photonic bandgap fiber mounted on a silicon assembly, a pump/signal combiner with single-mode signal feed-through and an ytterbium-doped photonic crystal fiber. The laser cavity produces a single-mode output and is tuned in the range 1040- 1065 nm by applying an electric field to the silicon assembly.

  2. Transverse modes switchable fiber laser based on few-mode fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Sun, Biao; Wang, Anting; Zhou, Yong; Gu, Chun; Lin, Zhongxi; Xu, Lixin; Ming, Hai

    2012-11-01

    Based on the few-mode fiber Bragg grating's reflection characteristics, we propose and demonstrate a transverse modes switchable fiber laser fiber laser, fundamental mode and 1st higher order modes, and the states be switched by tuning the laser's oscillating wavelength. The radial vector beam is also obtained by splitting the degenerated 1st higher order modes.

  3. Actively Q-switched Raman fiber laser

    NASA Astrophysics Data System (ADS)

    Kuznetsov, A. G.; Podivilov, E. V.; Babin, S. A.

    2015-03-01

    A new scheme providing actively Q-switched operation of a Raman fiber laser (RFL) has been proposed and tested. The RFL consists of a 1 km single-mode fiber with a switchable loop mirror at one end and an angled cleaved output end. An 1080 nm pulse with microsecond duration is generated at the output by means of acousto-optic switching of the mirror at ~30 kHz in the presence of 6 W backward pumping at 1030 nm. In the proposed scheme, the generated pulse energy is defined by the pump energy distributed along the passive fiber, which amounts to 30 μJ in our case. The available pump energy may be increased by means of fiber lengthening. Pulse shortening is also expected.

  4. Nonlinear High-Energy Pulse Propagation in Graded-Index Multimode Optical Fibers for Mode-Locked Fiber Lasers

    DTIC Science & Technology

    2014-12-23

    High-Energy Pulse Propagation in Graded -Index Multimode Optical Fibers for Mode-Locked Fiber Lasers 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-12-1...integration of large-core graded -index multimode fibers (GIMFs) in ultrafast mode-locked fiber lasers to dramatically increase the pulse energy...optical fibers, graded -index multimode fibers, nonlinear switching, waveguides, mode-locked fiber lasers, ultra-short pulse fiber lasers 16. SECURITY

  5. Performance analysis of CO2 laser polished angled ribbon fiber

    NASA Astrophysics Data System (ADS)

    Sohn, Ik-Bu; Choi, Hun-Kook; Noh, Young-Chul; Lee, Man-Seop; Oh, Jin-Kyoung; Kim, Seong-min; Ahsan, Md. Shamim

    2017-01-01

    This paper demonstrates CO2 laser assisted simultaneous polishing of angled ribbon fibers consisting eight set of optical fibers. The ribbon fibers were rotated vertically at an angle of 12° and polished by repetitive irradiation of CO2 laser beam at the end faces of the fibers. Compared to mechanically polished sharp edged angled fibers, CO2 laser polishing forms curve edged angled fibers. Increase in the curvature of the end faces of the ribbon fibers causes the increase of the fibers' strength, which in turn represents great robustness against fiber connections with other devices. The CO2 laser polished angled fibers have great smoothness throughout the polished area. The smoothness of the fiber end faces have been controlled by varying the number of laser irradiation. After CO2 laser polishing, the average value of the fiber angle of the ribbon fibers is ∼8.28°. The laser polished ribbon fibers show low insertion and return losses when connecting with commercial optical communication devices. The proposed technique of polishing the angled ribbon fibers is highly replicable and reliable and thus suitable for commercial applications.

  6. All-fiber passively mode-locked Ho-laser pumped by ytterbium fiber laser

    NASA Astrophysics Data System (ADS)

    Filatova, S. A.; Kamynin, V. A.; Zhluktova, I. V.; Trikshev, A. I.; Tsvetkov, V. B.

    2016-11-01

    We report an all-fiber mode-lock holmium-doped ring laser passively mode-locked by nonlinear polarization rotation without dispersion compensation. The laser produced picosecond pulses at 2.057 µm. The average output power was 4.5 mW.

  7. All-Fiber Configuration Laser Self-Mixing Doppler Velocimeter Based on Distributed Feedback Fiber Laser

    PubMed Central

    Wu, Shuang; Wang, Dehui; Xiang, Rong; Zhou, Junfeng; Ma, Yangcheng; Gui, Huaqiao; Liu, Jianguo; Wang, Huanqin; Lu, Liang; Yu, Benli

    2016-01-01

    In this paper, a novel velocimeter based on laser self-mixing Doppler technology has been developed for speed measurement. The laser employed in our experiment is a distributed feedback (DFB) fiber laser, which is an all-fiber structure using only one Fiber Bragg Grating to realize optical feedback and wavelength selection. Self-mixing interference for optical velocity sensing is experimentally investigated in this novel system, and the experimental results show that the Doppler frequency is linearly proportional to the velocity of a moving target, which agrees with the theoretical analysis commendably. In our experimental system, the velocity measurement can be achieved in the range of 3.58 mm/s–2216 mm/s with a relative error under one percent, demonstrating that our novel all-fiber configuration velocimeter can implement wide-range velocity measurements with high accuracy. PMID:27472342

  8. Fiber Coupled Laser Diodes with Even Illumination Pattern

    NASA Technical Reports Server (NTRS)

    Howard, Richard T. (Inventor)

    2007-01-01

    An optical fiber for evenly illuminating a target. The optical fiber is coupled to a laser emitting diode and receives laser light. The la ser light travels through the fiber optic and exits at an exit end. T he exit end has a diffractive optical pattern formed thereon via etch ing, molding or cutting, to reduce the Gaussian profile present in co nventional fiber optic cables The reduction of the Gaussian provides an even illumination from the fiber optic cable.

  9. All fiber laser using a ring cavity

    NASA Astrophysics Data System (ADS)

    Flores, Alberto Varguez; Pérez, Georgina Beltrán; Aguirre, Severino Muñoz; Mixcóatl, Juan Castillo

    2008-04-01

    Mode-locked laser have a number of potential applications, depending on the wavelength and pulse width. They could be used as sources in communications systems for time division multiplexing (TDM) or wavelength-division-multiplexing (WDM) as spectroscopic tools in the laboratory for time-resolved studies of fast nonlinear phenomena in semiconductors, or as seeds for solid-state amplifers such as Nd:Glass, color center alexandrite, or Ti:Sapphire. Short pulses also have potential use in electro-optic sampling systems, as a source for pulsed sensors, or as tunable seed pulses for lasers in medical applications. Applications such as optical coherent tomography could take advantage of the broad bandwidth of a mode-locked fiber laser rather that the temporal ultra-short pulse width. This work shows the characterization of active mode-locking all-fiber laser by using an acousto-optic frequency shifter to the ring cavity, an erbium doped fiber (EDF) and polarization controllers (PC). The results shows a highly stable mode-locked, low noise of pulse generation with repetition rate of 10 MHz and width of 1.6 ns

  10. Multi-watt 589nm fiber laser source

    SciTech Connect

    DAWSON, J W; DROBSHOFF, A D; BEACH, R J; MESSERLY, M J; PAYNE, S A; BROWN, A; PENNINGTON, D M; BAMFORD, D J; SHARPE, S J; COOK, D J

    2006-01-19

    We have demonstrated 3.5W of 589nm light from a fiber laser using periodically poled stoichiometric Lithium Tantalate (PPSLT) as the frequency conversion crystal. The system employs 938nm and 1583nm fiber lasers, which were sum-frequency mixed in PPSLT to generate 589nm light. The 938nm fiber laser consists of a single frequency diode laser master oscillator (200mW), which was amplified in two stages to >15W using cladding pumped Nd{sup 3+} fiber amplifiers. The fiber amplifiers operate at 938nm and minimize amplified spontaneous emission at 1088nm by employing a specialty fiber design, which maximizes the core size relative to the cladding diameter. This design allows the 3-level laser system to operate at high inversion, thus making it competitive with the competing 1088nm 4-level laser transition. At 15W, the 938nm laser has an M{sup 2} of 1.1 and good polarization (correctable with a quarter and half wave plate to >15:1). The 1583nm fiber laser consists of a Koheras 1583nm fiber DFB laser that is pre-amplified to 100mW, phase modulated and then amplified to 14W in a commercial IPG fiber amplifier. As a part of our research efforts we are also investigating pulsed laser formats and power scaling of the 589nm system. We will discuss the fiber laser design and operation as well as our results in power scaling at 589nm.

  11. Multi-watt 589nm fiber laser source

    NASA Astrophysics Data System (ADS)

    Dawson, Jay W.; Drobshoff, Alex D.; Beach, Raymond J.; Messerly, Michael J.; Payne, Stephen A.; Brown, Aaron; Pennington, Deanna M.; Bamford, Douglas J.; Sharpe, Scott J.; Cook, David J.

    2006-02-01

    We have demonstrated 3.5W of 589nm light from a fiber laser using periodically poled stoichio-metric Lithium Tantalate (PPSLT) as the frequency conversion crystal. The system employs 938nm and 1583nm fiber lasers, which were sum-frequency mixed in PPSLT to generate 589nm light. The 938nm fiber laser consists of a single frequency diode laser master oscillator (200mW), which was amplified in two stages to >15W using cladding pumped Nd 3+ fiber amplifiers. The fiber amplifiers operate at 938nm and minimize amplified spontaneous emission at 1088nm by employing a specialty fiber design, which maximizes the core size relative to the cladding diameter. This design allows the 3-level laser system to operate at high inversion, thus making it competitive with the 1088nm 4-level laser transition. At 15W, the 938nm laser has an M2 of 1.1 and good polarization (correctable with a quarter and half wave plate to >15:1). The 1583nm fiber laser consists of a Koheras 1583nm fiber DFB laser that is pre-amplified to 100mW, phase modulated and then amplified to 14W in a commercial IPG fiber amplifier. As a part of our research efforts we are also investigating pulsed laser formats and power scaling of the 589nm system. We will discuss the fiber laser design and operation as well as our results in power scaling at 589nm.

  12. Polarization-modulated random fiber laser

    NASA Astrophysics Data System (ADS)

    Wu, Han; Wang, Zinan; He, Qiheng; Fan, Mengqiu; Li, Yunqi; Sun, Wei; Zhang, Li; Li, Yi; Rao, Yunjiang

    2016-05-01

    In this letter, we propose and experimentally demonstrate a polarization-modulated random fiber laser (RFL) for the first time. It is found that the output power of the half-opened RFL with polarized pumping is sensitive to the state of polarization (SOP) of the Stokes light in a fiber loop acting as a mirror. By inserting a polarization switch (PSW) in the loop mirror, the state of the random lasing can be switched between on/off states, thus such a polarization-modulated RFL can generate pulsed output with high extinction ratio.

  13. MOPA pulsed fiber laser for silicon scribing

    NASA Astrophysics Data System (ADS)

    Yang, Limei; Huang, Wei; Deng, Mengmeng; Li, Feng

    2016-06-01

    A 1064 nm master oscillator power amplifier (MOPA) pulsed fiber laser is developed with flexible control over the pulse width, repetition frequency and peak power, and it is used to investigate the dependence of mono-crystalline silicon scribe depth on the laser pulse width, scanning speed and repeat times. Experimental results indicate that long pulses with low peak powers lead to deep ablation depths. We also demonstrate that the ablation depth grows fast with the scanning repeat times at first and progressively tends to be saturated when the repeat times reach a certain level. A thermal model considering the laser pulse overlapping effect that predicts the silicon temperature variation and scribe depth is employed to verify the experimental conclusions with reasonably close agreement. These conclusions are of great benefits to the optimization of the laser material processing with high efficiency.

  14. Laser and Optical Fiber Metrology in Romania

    SciTech Connect

    Sporea, Dan; Sporea, Adelina

    2008-04-15

    The Romanian government established in the last five years a National Program for the improvement of country's infrastructure of metrology. The set goal was to develop and accredit testing and calibration laboratories, as well as certification bodies, according to the ISO 17025:2005 norm. Our Institute benefited from this policy, and developed a laboratory for laser and optical fibers metrology in order to provide testing and calibration services for the certification of laser-based industrial, medical and communication products. The paper will present the laboratory accredited facilities and some of the results obtained in the evaluation of irradiation effects of optical and optoelectronic parts, tests run under the EU's Fusion Program.

  15. Laser and Optical Fiber Metrology in Romania

    NASA Astrophysics Data System (ADS)

    Sporea, Dan; Sporea, Adelina

    2008-04-01

    The Romanian government established in the last five years a National Program for the improvement of country's infrastructure of metrology. The set goal was to develop and accredit testing and calibration laboratories, as well as certification bodies, according to the ISO 17025:2005 norm. Our Institute benefited from this policy, and developed a laboratory for laser and optical fibers metrology in order to provide testing and calibration services for the certification of laser-based industrial, medical and communication products. The paper will present the laboratory accredited facilities and some of the results obtained in the evaluation of irradiation effects of optical and optoelectronic parts, tests run under the EU's Fusion Program.

  16. Drilling with fiber-transmitted, visible lasers

    SciTech Connect

    Kautz, D.D.; Berzins, L.V.; Dragon, E.P.; Werve, M.E.; Warner, B.E.

    1994-02-17

    High power and radiance copper-vapor laser technology developed at Lawrence Livermore National Laboratory shows great promise for many materials processing tasks. The authors recently transmitted the visible light produced by these lasers through fiber optics to perform hole drilling experiments. They found the tolerances on the hole circulatory and cylindricity to be excellent when compared to that produced by conventional optics. This technique lends itself to many applications that are difficult to perform when using conventional optics, including robotic manipulation and hole drilling in non-symmetric parts.

  17. Laser cutting of carbon fiber reinforced thermo-plastics (CFRTP) by single-mode fiber laser irradiation

    NASA Astrophysics Data System (ADS)

    Niino, Hiroyuki; Kawaguchi, Yoshizo; Sato, Tadatake; Narazaki, Aiko; Kurosaki, Ryozo; Muramatsu, Mayu; Harada, Yoshihisa; Anzai, Kenji; Aoyama, Mitsuaki; Matsushita, Masafumi; Furukawa, Koichi; Nishino, Michiteru; Fujisaki, Akira; Miyato, Taizo; Kayahara, Takashi

    2014-03-01

    We report on the laser cutting of carbon fiber reinforced thermo-plastics (CFRTP) with a cw IR fiber laser (single-mode fiber laser, average power: 350 W). CFRTP is a high strength composite material with a lightweight, and is increasingly being used various applications. A well-defined cutting of CFRTP which were free of debris and thermal-damages around the grooves, were performed by the laser irradiation with a fast beam galvanometer scanning on a multiple-scanpass method.

  18. Theory of a random fiber laser

    SciTech Connect

    Kolokolov, I. V. Lebedev, V. V.; Podivilov, E. V.; Vergeles, S. S.

    2014-12-15

    We develop the theory explaining the role of nonlinearity in generation of radiation in a fiber laser that is pumped by external light. The pumping energy is converted into the generating signal due to the Raman scattering supplying an effective gain for the signal. The signal is generated with frequencies near the one corresponding to the maximum value of the gain. Generation conditions and spectral properties of the generated signal are examined. We focus mainly on the case of a random laser where reflection of the signal occurs on impurities of the fiber. From the theoretical standpoint, kinetics of a wave system close to an integrable one are investigated. We demonstrate that in this case, the perturbation expansion in the kinetic equation has to use the closeness to the integrable case.

  19. Pressure-gradient fiber laser hydrophone

    NASA Astrophysics Data System (ADS)

    Zhang, Wentao; Zhang, Faxiang; Li, Fang; Liu, Yuliang

    2009-10-01

    A pressure-gradient fiber laser hydrophone (FLH) is demonstrated. Two brass diaphragms are installed at the end of a metal cylinder as the sensing element. There are two orifices at the middle of the cylinder. This structure can work as a pressure-gradient microphone in the acoustic field. Thus the DFB fiber laser fixed at the center of the two diaphragms is elongated or shortened due to the acoustic wave. Theoretical analysis is given based on the electro-acoustic theory. Experiments are carried out to test the performance of the hydrophone. A sensitivity of 100 nm/MPa has been achieved. Furthermore, the hydrostatic pressure is self-compensated and a ultra-thin dimension is achieved based on the proposed structure.

  20. Self-Centering of a Ball Lens by Laser Trapping: Fiber-Ball-Fiber Coupling Analysis

    NASA Astrophysics Data System (ADS)

    Gauthier, Robert C.; Friesen, Michael; Gerrard, Thomas; Hassouneh, Wissam; Koziorowski, Piotr; Moore, Damian; Oprea, Karen; Uttamalingam, Sivasanker

    2003-03-01

    Fiber-to-fiber coupling through use of a laser-trapped microball lens is examined. A model based on radiation pressure predicts that the ball lens will align axially between the fiber endfaces. Laser manipulation of the ball lens axial position results in a configuration in which the ball lens optically bridges the gap between the fibers. Experimental results are presented for several fiber endface separations, and it is found that the presence of the microball lens can increase the coupling by a factor of 2 above the level expected by direct fiber-to-fiber coupling for the same fiber endface separation.

  1. Germanate Glass Fiber Lasers for High Power

    DTIC Science & Technology

    2016-01-04

    germanate based glasses with a specific focus on glass stability during thermal- cycling which is representative of the steps required to fabricate a doped...evidence of crystallisation after thermal cycling , and is of a low enough loss to realize a fiber laser. The glass stability is demonstrated by...specific focus on glass stability during thermal- cycling which is representative of the steps required to fabricate a doped micro-structured germanate

  2. High Power Fiber Lasers and Applications to Manufacturing

    NASA Astrophysics Data System (ADS)

    Richardson, Martin; McComb, Timothy; Sudesh, Vikas

    2008-09-01

    We summarize recent developments in high power fiber laser technologies and discuss future trends, particularly in their current and future use in manufacturing technologies. We will also describe our current research programs in fiber laser development, ultra-fast and new lasers, and will mention the expectations in these areas for the new Townes Laser Institute. It will focus on new core laser technologies and their applications in medical technologies, advanced manufacturing technologies and defense applications. We will describe a program on large mode area fiber development that includes results with the new gain-guiding approach, as well as high power infra-red fiber lasers. We will review the opportunities for high power fiber lasers in various manufacturing technologies and illustrate this with applications we are pursuing in the areas of femtosecond laser applications, advanced lithographies, and mid-IR technologies.

  3. Optical pulse generation using fiber lasers and integrated optics

    SciTech Connect

    Wilcox, R.B.; Browning, D.F.; Burkhart, S.C.; VanWonterghem, B.W.

    1995-03-27

    We have demonstrated an optical pulse forming system using fiber and integrated optics, and have designed a multiple-output system for a proposed fusion laser facility. Our approach is an advancement over previous designs for fusion lasers, and an unusual application of fiber lasers and integrated optics.

  4. Comparison of core fibers and contact probes for laser surgery

    NASA Astrophysics Data System (ADS)

    Steiner, Rudolf W.; Keckstein, J.; Finger, Anthonio

    1990-07-01

    Advanced laser operational techniques have been introduced using the Nd:YAG or the argon laser in combination with fiber techniques and contact probes . In gynaecology, for exantple, surgeons need highly flexible fiber transmission systems for laparoscopic operations 2 Indications such as adhesiolysis or endornetriosis can be treated without mechanical traumatisation and bleeding using the laser light. Laser systems with different wavelengths, fibers and tips have become a very flexible surgical instrument. Feedback control of the reaction of the laser light with tissue makes the inedical laser system save and reliable.

  5. Multi-wavelength fiber laser based on a fiber Fabry-Perot interferometer

    NASA Astrophysics Data System (ADS)

    Estudillo-Ayala, J. M.; Jauregui-Vazquez, D.; Haus, J. W.; Perez-Maciel, M.; Sierra-Hernandez, J. M.; Avila-Garcia, M. S.; Rojas-Laguna, R.; Lopez-Dieguez, Y.; Hernandez-Garcia, J. C.

    2015-12-01

    In this work we report experimental studies of an erbium-doped fiber laser design that simultaneously emits up to three wavelengths. The laser cavity configuration has an all-fiber, Fabry-Perot interferometer, based on the insertion of air cavities in the fiber, near one end of a conventional single-mode fiber. The laser emissions have a side-mode suppression ratio over 25 dB, wavelength variations around 0.04 nm, and 2 dB power fluctuations. By using a simple, controlled fiber curvature technique cavity losses are varied over a section of convectional single-mode fiber and the laser output is switched between single-, dual-, and triple-wavelength emission. Moreover, by applying a refractive index change over the fiber filter the emission wavelengths are shifted. The fiber laser offers a compact, simple, and low-cost design for a multiple wavelength outputs that can be adopted in future applications.

  6. Development of Fiber-Based Laser Systems for LISA

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Camp, Jordan

    2010-01-01

    We present efforts on fiber-based laser systems for the LISA mission at the NASA Goddard Space Flight Center. A fiber-based system has the advantage of higher robustness against external disturbances and easier implementation of redundancies. For a master oscillator, we are developing a ring fiber laser and evaluating two commercial products, a DBR linear fiber laser and a planar-waveguide external cavity diode laser. They all have comparable performance to a traditional NPRO at LISA band. We are also performing reliability tests of a 2-W Yb fiber amplifier and radiation tests of fiber laser/amplifier components. We describe our progress to date and discuss the path to a working LISA laser system design.

  7. Comparative study of ring and random cavities for fiber lasers.

    PubMed

    Fernandez-Vallejo, Montserrat; Rota-Rodrigo, Sergio; Lopez-Amo, Manuel

    2014-06-01

    An experimental comparison of three fiber laser structures with the same Raman gain medium is presented in order to establish the main pros and cons of each basic scheme. The first fiber laser is based on a hybrid ring-random fiber laser, the second one is a pure ring fiber laser, and the last one is a random fiber laser. Several aspects have been taken into account in the study. First, from the optical point of view, the parameters of interest compared are output power, lasing threshold, slope efficiency, power fluctuations, and the longitudinal modes have been analyzed. Second, the possible utilization of fiber lasers in digital modulated optical communication systems is also studied.

  8. Proximal fiber tip damage during Holmium:YAG and thulium fiber laser ablation of kidney stones

    NASA Astrophysics Data System (ADS)

    Wilson, Christopher R.; Hardy, Luke A.; Irby, Pierce B.; Fried, Nathaniel M.

    2016-02-01

    The Thulium fiber laser (TFL) is being studied as an alternative to Holmium:YAG laser for lithotripsy. TFL beam originates within an 18-μm-core thulium doped silica fiber, and its near single mode, Gaussian beam profile enables transmission of higher laser power through smaller fibers than possible during Holmium laser lithotripsy. This study examines whether TFL beam profile also reduces proximal fiber tip damage compared to Holmium laser multimodal beam. TFL beam at wavelength of 1908 nm was coupled into 105-μm-core silica fibers, with 35-mJ energy, 500-μs pulse duration, and pulse rates of 50-500 Hz. For each pulse rate, 500,000 pulses were delivered. Magnified images of proximal fiber surfaces were taken before and after each trial. For comparison, 20 single-use, 270-μm-core fibers were collected after clinical Holmium laser lithotripsy procedures using standard settings (600 mJ, 350 μs, 6 Hz). Total laser energy, number of laser pulses, and laser irradiation time were recorded, and fibers were rated for damage. For TFL studies, output power was stable, and no proximal fiber damage was observed after delivery of 500,000 pulses at settings up to 35 mJ, 500 Hz, and 17.5 W average power. In contrast, confocal microscopy images of fiber tips after Holmium lithotripsy showed proximal fiber tip degradation in all 20 fibers. The proximal fiber tip of a 105-μm-core fiber transmitted 17.5 W of TFL power without degradation, compared to degradation of 270-μm-core fibers after transmission of 3.6 W of Holmium laser power. The smaller and more uniform TFL beam profile may improve fiber lifetime, and potentially reduce costs for the surgical disposables as well.

  9. Thulium-doped all-fiber mode-locked laser synchronously pumping by a fiber laser

    NASA Astrophysics Data System (ADS)

    Li, Gen; Hu, Yangyang; Yan, Ke; Zhang, Chun; Zhang, Junyi; Gu, Chun; Xu, Lixin

    2016-09-01

    We demonstrate a thulium-doped all fiber actively mode-locked laser by synchronously pumping without electronic modulator. A mode-locked fiber laser operating at 1550 nm based on nonlinear polarization rotation (NPR) is innovatively utilized as the pulsed pump. Through cavity length matching, stable mode-locking that operate at 1891.25 nm is achieved with a spectral width of 0.52 nm at 3 dB. The repetition rate is 11.59 MHz with an estimated pulse duration less than 125 ps.

  10. Photodegradation of fluoride glass blue fiber laser

    NASA Astrophysics Data System (ADS)

    Chandonnet, Alain; Laperle, Pierre; LaRochelle, Sophie; Vallee, Real

    1997-01-01

    The first demonstration of blue upconversion fiber lasers in Tm-ZBLAN has generated considerable interest among laser scientists looking for all-solid-state visible sources. Although initial experiments have shown a large conversion efficiency, a good spatial beam quality and an overall simplicity of the approach, these sources have not yet appeared on the market. In an attempt to reproduce these early results, many research teams including our own have encountered unexplained and detrimental start-up effects in these lasers. We have recently shown that this behavior is the result of photochromic damage in the fluoride fibers generated by the infrared pumping source. Progressive build- up of photoinduced loss ultimately prevents operation of the device. The photoinduced absorption spectrum extends from the UV to the near infrared, with three major bands centered around 300 nm, 500 nm and 800 nm. Pump-probe experiments show that the damage mechanism depends on the Tm3+ concentration and that it follows a fourth power dependence on the pumping intensity. Further investigation has revealed that photobleaching of the defects is possible using visible and near infrared radiation. The residual absorption spectrum following photobleaching suggests that three different species of defects are created. One type of defects is related to the 800 nm band and can be permanently removed. The other two are only temporarily removed by photobleaching and reappear on a time-scale of a few minutes. In addition, thermal bleaching can completely erase the defects in certain fibers. This paper summarizes the current understanding of photoinduced phenomena occurring in Tm3+-ZBLAN fibers.

  11. High-Power Fiber Lasers for Directed-Energy Applications

    DTIC Science & Technology

    2008-01-01

    demonstrated in a moder- ately turbulent environment. HIgH-PowEr FIbEr LAsErs Although a number of companies manufacture high-power fiber lasers , IPG ...in approximately one year. Multi- kilowatt , single-mode fiber lasers are robust, compact, and have high wall- plug efficiency, random polarization...and large band- width (~0.1%). A 1 kW, single-mode IPG fiber laser module, operating at wavelength l = 1.075 μm, exclud- ing power supply, measures w

  12. Novel fiber optic tip designs and devices for laser surgery

    NASA Astrophysics Data System (ADS)

    Hutchens, Thomas Clifton

    Fiber optic delivery of laser energy has been used for years in various types of surgical procedures in the human body. Optical energy provides several benefits over electrical or mechanical surgery, including the ability to selectively target specific tissue types while preserving others. Specialty fiber optic tips have also been introduced to further customize delivery of laser energy to the tissue. Recent evolution in lasers and miniaturization has opened up opportunities for many novel surgical techniques. Currently, ophthalmic surgeons use relatively invasive mechanical tools to dissect retinal deposits which occur in proliferative diabetic retinopathy. By using the tight focusing properties of microspheres combined with the short optical penetration depth of the Erbium:YAG laser and mid-IR fiber delivery, a precise laser scalpel can be constructed as an alternative, less invasive and more precise approach to this surgery. Chains of microspheres may allow for a self limiting ablation depth of approximately 10 microm based on the defocusing of paraxial rays. The microsphere laser scalpel may also be integrated with other surgical instruments to reduce the total number of handpieces for the surgeon. In current clinical laser lithotripsy procedures, poor input coupling of the Holmium:YAG laser energy frequently damages and requires discarding of the optical fiber. However, recent stone ablation studies with the Thulium fiber laser have provided comparable results to the Ho:YAG laser. The improved spatial beam profile of the Thulium fiber laser can also be efficiently coupled into a fiber approximately one third the diameter and reduces the risk of damaging the fiber input. For this reason, the trunk optical fiber minus the distal fiber tip can be preserved between procedures. The distal fiber tip, which degrades during stone ablation, could be made detachable and disposable. A novel, low-profile, twist-locking, detachable distal fiber tip interface was designed

  13. Advances in fiber laser spectral beam combining for power scaling

    NASA Astrophysics Data System (ADS)

    Honea, Eric; Afzal, Robert S.; Savage-Leuchs, Matthias; Henrie, Jason; Brar, Khush; Kurz, Nathan; Jander, Don; Gitkind, Neil; Hu, Dan; Robin, Craig; Jones, Andrew M.; Kasinadhuni, Ravi; Humphreys, Richard

    2016-03-01

    Spectral Beam Combining (SBC) of fiber lasers provides a simple, robust architecture for high brightness power scaling beyond the limit of a single fiber. We review recent progress in power scaling and describe what we believe is the highest power SBC fiber demonstration and largest number of fiber lasers combined to date. Here we report results on a fiber SBC system where we achieved > 30 kW by combining 96 individual fiber lasers into a single high brightness beam with a beam quality of M2 = 1.6 x 1.8. The potential for further power scaling at the system level is highlighted with examples of beam combinable fiber laser power scaling.

  14. Plasticity of climbing fibers after laser axotomy

    NASA Astrophysics Data System (ADS)

    Allegra Mascaro, A. L.; Cesare, P.; Sacconi, L.; Grasselli, G.; Strata, P.; Pavone, F. S.

    2010-02-01

    In the adult nervous system, different population of neurons corresponds to different regenerative behavior. Although previous works show that olivocerebellar fibers are capable of axonal regeneration in a suitable environment as a response to injury1, we have hitherto no details about the real dynamics of fiber regeneration. We coupled two photon imaging to laser-induced lesions to perform in vivo multiphoton nanosurgery in the CNS of living mice expressing fluorescent proteins to investigate the reparative properties of Climbing Fibers (CFs) in the adult CNS, following the time evolution of this plastic process in vivo. Here we show that a regenerative event may take place in a murine model in the days that follow a sub-micrometric lesion on the distal portion of the climbing fiber. Furthermore this unique model could allow, through manipulation of the viral vector, to explore in detail the biochemical mechanisms underlying the reparative process. The great potential of long-term two photon imaging, coupled to genetic manipulation, opens great opportunities to further investigate the dynamic properties of neurons and their rearrangement following an injury.

  15. Property and Shape Modulation of Carbon Fibers Using Lasers.

    PubMed

    Blaker, Jonny J; Anthony, David B; Tang, Guang; Shamsuddin, Siti-Ros; Kalinka, Gerhard; Weinrich, Malte; Abdolvand, Amin; Shaffer, Milo S P; Bismarck, Alexander

    2016-06-29

    An exciting challenge is to create unduloid-reinforcing fibers with tailored dimensions to produce synthetic composites with improved toughness and increased ductility. Continuous carbon fibers, the state-of-the-art reinforcement for structural composites, were modified via controlled laser irradiation to result in expanded outwardly tapered regions, as well as fibers with Q-tip (cotton-bud) end shapes. A pulsed laser treatment was used to introduce damage at the single carbon fiber level, creating expanded regions at predetermined points along the lengths of continuous carbon fibers, while maintaining much of their stiffness. The range of produced shapes was quantified and correlated to single fiber tensile properties. Mapped Raman spectroscopy was used to elucidate the local compositional and structural changes. Irradiation conditions were adjusted to create a swollen weakened region, such that fiber failure occurred in the laser treated region producing two fiber ends with outwardly tapered ends. Loading the tapered fibers allows for viscoelastic energy dissipation during fiber pull-out by enhanced friction as the fibers plough through a matrix. In these tapered fibers, diameters were locally increased up to 53%, forming outward taper angles of up to 1.8°. The tensile strength and strain to failure of the modified fibers were significantly reduced, by 75% and 55%, respectively, ensuring localization of the break in the expanded region; however, the fiber stiffness was only reduced by 17%. Using harsher irradiation conditions, carbon fibers were completely cut, resulting in cotton-bud fiber end shapes. Single fiber pull-out tests performed using these fibers revealed a 6.75-fold increase in work of pull-out compared to pristine carbon fibers. Controlled laser irradiation is a route to modify the shape of continuous carbon fibers along their lengths, as well as to cut them into controlled lengths leaving tapered or cotton-bud shapes.

  16. χ{sup (3)} measurements of axial ligand modified high valent tin(IV) porphyrins using degenarete four wave mixing at 532nm

    SciTech Connect

    Narendran, N. K. Siji Chandrasekharan, K.; Soman, Rahul; Arunkumar, Chellaiah; Sudheesh, P.

    2014-10-15

    Porphyrins and metalloporphyrins are unique class of molecules for Nonlinear Optical applications because of their unique structure of altering the central metal atom, large extended π-system, high thermal stability, tunable shape, symmetry and synthetic versatility Here, we report χ{sup (3)} Measurements of a simple phenyl porphyrins and its highvalent tin(IV) porphyrins with Bromination characterized by UV-Visible spectroscopic method. In this study, we employed the Degenerate Four Wave Mixing technique using forward Boxcar geometry with an Nd:YAG nano second pulsed laser as source and it was found that the tin(IV) porphyrin with Bromination exhibits good χ{sup (3)} value and figure of merit.

  17. Vibration mode shapes visualization in industrial environment by real-time time-averaged phase-stepped electronic speckle pattern interferometry at 10.6 μm and shearography at 532 nm

    NASA Astrophysics Data System (ADS)

    Languy, Fabian; Vandenrijt, Jean-François; Thizy, Cédric; Rochet, Jonathan; Loffet, Christophe; Simon, Daniel; Georges, Marc P.

    2016-12-01

    We present our investigations on two interferometric methods suitable for industrial conditions dedicated to the visualization of vibration modes of aeronautic blades. First, we consider long-wave infrared (LWIR) electronic speckle pattern interferometry (ESPI). The use of long wavelength allows measuring larger amplitudes of vibrations compared with what can be achieved with visible light. Also longer wavelengths allow lower sensitivity to external perturbations. Second, shearography at 532 nm is used as an alternative to LWIR ESPI. Both methods are used in time-averaged mode with the use of phase-stepping. This allows transforming Bessel fringes, typical to time averaging, into phase values that provide higher contrast and improve the visualization of vibration mode shapes. Laboratory experimental results with both techniques allowed comparison of techniques, leading to selection of shearography. Finally a vibration test on electrodynamic shaker is performed in an industrial environment and mode shapes are obtained with good quality by shearography.

  18. A review of Thulium fiber laser ablation of kidney stones

    NASA Astrophysics Data System (ADS)

    Fried, Nathaniel M.; Blackmon, Richard L.; Irby, Pierce B.

    2011-02-01

    The clinical solid-state Holmium:YAG laser lithotripter (λ=2120 nm) is capable of operating at high pulse energies, but its efficient operation is limited to low pulse rates during lithotripsy. The diode-pumped experimental Thulium Fiber Laser (λ=1908 nm) is limited to low pulse energies, but can operate at high pulse rates. This review compares stone ablation threshold, ablation rate, and retropulsion effects for Ho:YAG and TFL. Laser lithotripsy complications also include optical fiber bending failure resulting in endoscope damage and low irrigation rates leading to poor visibility. Both problems are related to fiber diameter and limited by Ho:YAG laser multimode spatial beam profile. This study exploits TFL spatial beam profile for higher power transmission through smaller fibers. A short taper is also studied for expanding TFL beam at the distal tip of a small-core fiber. Stone mass loss, stone crater depths, fiber transmission losses, fiber burn-back, irrigation rates, and deflection through a flexible ureteroscope were measured for tapered fiber and compared with conventional fibers. The stone ablation threshold for TFL was four times lower than for Ho:YAG. Stone retropulsion with Ho:YAG increased linearly with pulse energy. Retropulsion with TFL was minimal at pulse rates < 150 Hz, then rapidly increased at higher pulse rates. TFL beam profile provides higher laser power through smaller fibers than Ho:YAG laser, potentially reducing fiber failure and endoscope damage and allowing greater irrigation rates for improved visibility and safety. Use of a short tapered distal fiber tip also allows expansion of the laser beam, resulting in decreased fiber tip damage compared to conventional fibers, without compromising fiber bending, stone ablation efficiency, or irrigation rates.

  19. Femtosecond fiber laser welding of dissimilar metals.

    PubMed

    Huang, Huan; Yang, Lih-Mei; Bai, Shuang; Liu, Jian

    2014-10-01

    In this paper, welding of dissimilar metals was demonstrated for the first time, to the best of our knowledge, by using a high-energy high-repetition-rate femtosecond fiber laser. Metallurgical and mechanical properties were investigated and analyzed under various processing parameters (pulse energy, repetition rate, and welding speed). Results showed that the formation of intermetallic brittle phases and welding defects could be effectively reduced. Strong welding quality with more than 210 MPa tensile strength for stainless steel-aluminum and 175 MPa tensile strength for stainless steel-magnesium has been demonstrated. A minimal heat affected zone and uniform and homogenous phase transformation in the welding region have been demonstrated. This laser-welding technique can be extended for various applications in semiconductor, automobile, aerospace, and biomedical industries.

  20. Numerical modeling of mode-locked fiber lasers with a fiber-based saturable-absorber

    NASA Astrophysics Data System (ADS)

    Wang, Long; Chong, Andy; Haus, Joseph W.

    2017-01-01

    We report fiber laser simulations with a fiber compatible, self-focusing, saturable absorber (SA) device. The SA device consists of two tapered fiber ends separated by a bulk, nonlinear medium. An optical beam transmitted from one tapered fiber end, propagate through the nonlinear medium (chalcogenide glass As40 S e60) and couples back into the other tapered fiber end. Pulse propagation in the fiber laser cavity is performed using the Split Step Method. Stable pulses are generated with energies around 0.3 nJ and a transform limited pulse width around 200 fs.

  1. Growing Crystaline Sapphire Fibers By Laser Heated Pedestal Techiques

    DOEpatents

    Phomsakha, Vongvilay; Chang, Robert S. F.; Djeu, Nicholas I.

    1997-03-04

    An improved system and process for growing crystal fibers comprising a means for creating a laser beam having a substantially constant intensity profile through its cross sectional area, means for directing the laser beam at a portion of solid feed material located within a fiber growth chamber to form molten feed material, means to support a seed fiber above the molten feed material, means to translate the seed fiber towards and away from the molten feed material so that the seed fiber can make contact with the molten feed material, fuse to the molten feed material and then be withdrawn away from the molten feed material whereby the molten feed material is drawn off in the form of a crystal fiber. The means for creating a laser beam having a substantially constant intensity profile through its cross sectional area includes transforming a previously generated laser beam having a conventional gaussian intensity profile through its cross sectional area into a laser beam having a substantially constant intensity profile through its cross sectional area by passing the previously generated laser beam through a graded reflectivity mirror. The means for directing the laser beam at a portion of solid feed material is configured to direct the laser beam at a target zone which contains the molten feed material and a portion of crystal fiber drawn off the molten feed material by the seed fiber. The means to support the seed fiber above the molten feed material is positioned at a predetermined height above the molten feed material. This predetermined height provides the seed fiber with sufficient length and sufficient resiliency so that surface tension in the molten feed material can move the seed fiber to the center of the molten feed material irrespective of where the seed fiber makes contact with the molten feed material. The internal atmosphere of the fiber growth chamber is composed substantially of Helium gas.

  2. Novel high-brightness fiber coupled diode laser device

    NASA Astrophysics Data System (ADS)

    Haag, Matthias; Köhler, Bernd; Biesenbach, Jens; Brand, Thomas

    2007-02-01

    High brightness becomes more and more important in diode laser applications for fiber laser pumping and materials processing. For OEM customers fiber coupled devices have great advantages over direct beam modules: the fiber exit is a standardized interface, beam guiding is easy with nearly unlimited flexibility. In addition to the transport function the fiber serves as homogenizer: the beam profile of the laser radiation emitted from a fiber is symmetrical with highly repeatable beam quality and pointing stability. However, efficient fiber coupling requires an adaption of the slow-axis beam quality to the fiber requirements. Diode laser systems based on standard 10mm bars usually employ beam transformation systems to rearrange the highly asymmetrical beam of the laser bar or laser stack. These beam transformation systems (prism arrays, lens arrays, fiber bundles etc.) are expensive and become inefficient with increasing complexity. This is especially true for high power devices with small fiber diameters. On the other hand, systems based on single emitters are claimed to have good potential in cost reduction. Brightness of the inevitable fiber bundles, though, is limited due to inherent fill-factor losses. At DILAS a novel diode laser device has been developed combining the advantages of diode bars and single emitters: high brightness at high reliability with single emitter cost structure. Heart of the device is a specially tailored laser bar (T-Bar), which epitaxial and lateral structure was designed such that only standard fast- and slow-axis collimator lenses are required to couple the beam into a 200μm fiber. Up to 30 of these T-Bars of one wavelength can be combined to reach a total of > 500W ex fiber in the first step. Going to a power level of today's single emitter diodes even 1kW ex 200μm fiber can be expected.

  3. Morphological alterations on Citrobacter freundii bacteria induced by erythrosine dye and laser light.

    PubMed

    Silva, Josmary R; Cardoso, Gleidson; Maciel, Rafael R G; de Souza, Nara C

    2015-01-01

    The effect of the laser irradiation (532 nm) on films prepared from Citrobacter freundii mixed with erythrosine dye was investigated by using atomic force microscopy. It was observed that morphological changes of bacterial surfaces after irradiations, which were attributed to cellular damage of the outer membranes, are a result of a photodynamic effect. The results suggested that the combination of erythrosine and laser light at 532 nm could be a candidate to a photodynamic therapy against C. freundii.

  4. Packaging considerations of fiber-optic laser sources

    NASA Astrophysics Data System (ADS)

    Heikkinen, Veli; Tukkiniemi, Kari; Vaehaekangas, Jouko; Hannula, Tapio

    1991-12-01

    The continuous progress in material and component technology has generated new laser-based applications that require special packaging techniques. Hybrid integration offers a flexible method to accomplish custom design needs. This paper discusses several aspects in fiber optic packaging including optical, thermal, and mechanical issues. Special emphasis is on optical coupling between a laser diode and a single-mode fiber.

  5. Green pumped Alexandrite lasers

    NASA Astrophysics Data System (ADS)

    Kuper, Jerry W.; Brown, David C.

    2005-04-01

    Initial experiments with pulsed and CW pumping an alexandrite laser rod at 532 nm are presented. This pumping architecture holds promise for the production of scalable diode-pumped, tunable alexandrite laser systems operating in the near infrared (750 nm), and the ultraviolet (375 and 250 nm) spectral regions.

  6. Polarization study of a supercontinuum light source for different wavelengths through a photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Valle-Atilano, F. J.; Estudillo-Ayala, J. M.; Filoteo-Razo, J. D.; Hernández-Garcia, J. C.; Lauterio-Cruz, J. P.; Jáuregui-Vázquez, D.; Ibarra-Escamilla, B.; Rojas-Laguna, R.; Pottiez, O.; Kuzin, E. A.

    2016-03-01

    In this work we show the changes of polarization at different wavelengths in the end of a photonic crystal fiber (PCF) by means bandpass filters in a supercontinuum light source. A linear and circular polarization was introduced in a piece of PCF, showing the changes of the polarization for each wavelength of each one of the filters from 450 to 700nm. We used a microchip laser as pumping source with wavelength of 532nm and short pulses of 650ps with repetition rate of 5kHz. We obtained a continuous spectrum in the visible spectral region, showing a comparison of the polarization state at the fiber input with respect to polarization state in the fiber output for different wavelengths by rotating the axes of the PCF.

  7. Profiling atmospheric water vapor using a fiber laser lidar system.

    PubMed

    De Young, Russell J; Barnes, Norman P

    2010-02-01

    A compact, lightweight, and efficient fiber laser lidar system has been developed to measure water vapor profiles in the lower atmosphere of Earth or Mars. The line narrowed laser consist of a Tm:germanate fiber pumped by two 792 nm diode arrays. The fiber laser transmits approximately 0.5 mJ Q- switched pulses at 5 Hz and can be tuned to water vapor lines near 1.94 microm with linewidth of approximately 20 pm. A lightweight lidar receiver telescope was constructed of carbon epoxy fiber with a 30 cm Fresnel lens and an advanced HgCdTe APD detector. This system has made preliminary atmospheric measurements.

  8. Narrow-band generation in random distributed feedback fiber laser.

    PubMed

    Sugavanam, Srikanth; Tarasov, Nikita; Shu, Xuewen; Churkin, Dmitry V

    2013-07-15

    Narrow-band emission of spectral width down to ~0.05 nm line-width is achieved in the random distributed feedback fiber laser employing narrow-band fiber Bragg grating or fiber Fabry-Perot interferometer filters. The observed line-width is ~10 times less than line-width of other demonstrated up to date random distributed feedback fiber lasers. The random DFB laser with Fabry-Perot interferometer filter provides simultaneously multi-wavelength and narrow-band (within each line) generation with possibility of further wavelength tuning.

  9. Polarization dependence of laser interaction with carbon fibers and CFRP.

    PubMed

    Freitag, Christian; Weber, Rudolf; Graf, Thomas

    2014-01-27

    A key factor for laser materials processing is the absorptivity of the material at the laser wavelength, which determines the fraction of the laser energy that is coupled into the material. Based on the Fresnel equations, a theoretical model is used to determine the absorptivity for carbon fiber fabrics and carbon fiber reinforced plastics (CFRP). The surface of each carbon fiber is considered as multiple layers of concentric cylinders of graphite. With this the optical properties of carbon fibers and their composites can be estimated from the well-known optical properties of graphite.

  10. New generation high-power rare-earth-doped phosphate glass fiber and fiber laser

    NASA Astrophysics Data System (ADS)

    Wu, Ruikun; Myers, John D.; Myers, Michael J.

    2001-04-01

    High power, high brightness fiber lasers have numerous potential commercial and military applications. Fiber lasers with cladding pump designs represent a new generation of diode pumped configurations that are extremely efficient, have single mode output and may be operated with or without active cooling. Kigre has invented a new family of Er/Yb/Nd phosphate laser glass materials (designated QX) that promise to facilitate a quantum leap in fiber laser technology of this field. The new phosphate glass Rare-Earth doped fiber exhibit many advantages than Silica or Fluoride base fiber, see table.1. Instead of 30 to 50 meters of fused silica with a 50 mm bend radii; Kigre's phosphate glass fiber amplifiers may be designed to be less than 4 meters long .Laser performance and various design parameters, such as the fiber core diameter, NA, inner cladding shape and doping concentration are evaluated. Laser performances was demonstrated for an experimental QX/Er doubled clading fiber commissioned by MIT having 8 micron core, a 240 X 300 micron rectangle shaped inner cladding with 0.4 NA and 500 micron outer clading.. Kigre obtained approximately 2 dB/cm gain from 15cm long fiber under 940nm pumping The same fiber was evaluated by researcher at MIT. They used 975nm pump source. Maximum 270mW output was demonstrated by 30 cm long fiber with Fresnel reflection resonator mirrors. The slope efficiency of absorbed pump power s 47%.

  11. High performance distributed feedback fiber laser sensor array system

    NASA Astrophysics Data System (ADS)

    He, Jun; Li, Fang; Xu, Tuanwei; Wang, Yan; Liu, Yuliang

    2009-11-01

    Distributed feedback (DFB) fiber lasers have their unique properties useful for sensing applications. This paper presents a high performance distributed feedback (DFB) fiber laser sensor array system. Four key techniques have been adopted to set up the system, including DFB fiber laser design and fabrication, interferometric wavelength shift demodulation, digital phase generated carrier (PGC) technique and dense wavelength division multiplexing (DWDM). Experimental results confirm that a high dynamic strain resolution of 305 fɛ/√Hz (@ 1 kHz) has been achieved by the proposed sensor array system. And the multiplexing of eight channel DFB fiber laser sensor array has been demonstrated. The proposed DFB fiber laser sensor array system is suitable for ultra-weak signal detection, and has potential applications in the field of petroleum seismic explorations, earthquake prediction, and security.

  12. Explicit solution for Raman fiber laser using Lambert W function.

    PubMed

    Huang, Chaohong; Cai, Zhiping; Ye, Chenchun; Xu, Huiying

    2007-04-16

    In this paper, an approximate explicit solution for the first-order Raman fiber laser is obtained by using Lambert W function. Good agreement between the explicit solution and numerical simulation is demonstrated. Furthermore, the optimal design of Raman fiber laser is discussed using the proposed solution. The optimal values of fiber length, reflectivity of output fiber Bragg grating and power transfer efficiency are obtained under different pump power. There exists a certain tolerance of the optimal parameters, in which the output power decreases only slightly. The optimal fiber length and reflectivity of output FBG decrease with increasing pump power.

  13. Explicit solution for Raman fiber laser using Lambert W function

    NASA Astrophysics Data System (ADS)

    Huang, Chaohong; Cai, Zhiping; Ye, Chenchun; Xu, Huiying

    2007-04-01

    In this paper, an approximate explicit solution for the first-order Raman fiber laser is obtained by using Lambert W function. Good agreement between the explicit solution and numerical simulation is demonstrated. Furthermore, the optimal design of Raman fiber laser is discussed using the proposed solution. The optimal values of fiber length, reflectivity of output fiber Bragg grating and power transfer efficiency are obtained under different pump power. There exists a certain tolerance of the optimal parameters, in which the output power decreases only slightly. The optimal fiber length and reflectivity of output FBG decrease with increasing pump power.

  14. 150 W highly-efficient Raman fiber laser.

    PubMed

    Feng, Yan; Taylor, Luke R; Calia, Domenico Bonaccini

    2009-12-21

    We report a more than 150 W spectrally-clean continuous wave Raman fiber laser at 1120 nm with an optical efficiency of 85%. A approximately 30 m standard single mode silica fiber is used as Raman gain fiber to avoid second Stokes emission. A spectrally asymmetric resonator (in the sense of mirror reflection bandwidth) with usual fiber Bragg gratings is designed to minimize the laser power lost into the unwanted direction, even when the effective reflectivity of the rear fiber Bragg grating becomes as low as 81.5%.

  15. 280  GHz dark soliton fiber laser.

    PubMed

    Song, Y F; Guo, J; Zhao, L M; Shen, D Y; Tang, D Y

    2014-06-15

    We report on an ultrahigh repetition rate dark soliton fiber laser. We show both numerically and experimentally that by taking advantage of the cavity self-induced modulation instability and the dark soliton formation in a net normal dispersion cavity fiber laser, stable ultrahigh repetition rate dark soliton trains can be formed in a dispersion-managed cavity fiber laser. Stable dark soliton trains with a repetition rate as high as ∼280  GHz have been generated in our experiment. Numerical simulations have shown that the effective gain bandwidth limitation plays an important role on the stabilization of the formed dark solitons in the laser.

  16. A cladding-pumped, tunable holmium doped fiber laser.

    PubMed

    Simakov, Nikita; Hemming, Alexander; Clarkson, W Andrew; Haub, John; Carter, Adrian

    2013-11-18

    We present a tunable, high power cladding-pumped holmium doped fiber laser. The laser generated >15 W CW average power across a wavelength range of 2.043 - 2.171 μm, with a maximum output power of 29.7 W at 2.120 μm. The laser also produced 18.2 W when operating at 2.171 µm. To the best of our knowledge this is the highest power operation of a holmium doped laser at a wavelength >2.15 µm. We discuss the significance of background losses and fiber design for achieving efficient operation in holmium doped fibers.

  17. Output-coupling optimization of Nd-doped fiber lasers.

    PubMed

    Sanchez, F; Meziane, B; Chartier, T; Stephan, G; François, P L

    1995-11-20

    A simple theoretical modeling of the static properties of a fiber laser that includes distributed losses and inhomogeneous pumping is presented. Closed-form expressions for both the output and the backward (at the input mirror) intensities are obtained. The model is based on an extended formulation of the Rigrod's theory. It is shown that the laser responds differently depending on the length of the fiber. In particular, we show that for long (short) lasers optimal output power is achieved with low (high) output-coupler reflectivities. Experimental evidence of these results is obtained with Nd-doped fiber lasers with various lengths.

  18. Dark pulse generation in fiber lasers incorporating carbon nanotubes.

    PubMed

    Liu, H H; Chow, K K

    2014-12-01

    We demonstrate the generation of dark pulses from carbon nanotube (CNT) incorporated erbium-doped fiber ring lasers with net anomalous dispersion. A side-polished fiber coated with CNT layer by optically-driven deposition method is embedded into the laser in order to enhance the birefringence and nonlinearity of the laser cavity. The dual-wavelength domain-wall dark pulses are obtained from the developed CNT-incorporated fiber laser at a relatively low pump threshold of 50.6 mW. Dark pulses repeated at the fifth-order harmonic of the fundamental cavity frequency are observed by adjusting the intra-cavity polarization state.

  19. RF-modulated pulsed fiber optic lidar transmitter for improved underwater imaging and communications

    NASA Astrophysics Data System (ADS)

    Kimpel, F.; Chen, Y.; Fouron, J.-L.; Akbulut, M.; Engin, D.; Gupta, S.

    2011-03-01

    We present results on the design, development and initial testing of a fiber-optic based RF-modulated lidar transmitter operating at 532nm, for underwater imaging application in littoral waters. The design implementation is based on using state-of-the-art high-speed FPGAs, thereby producing optical waveforms with arbitrary digital-RF-modulated pulse patterns with carrier frequencies >= 3GHz, with a repetition rate of 0.5-1MHz, and with average powers >=5W (at 532nm). Use of RF-modulated bursts above 500MHz, instead of single optical pulse lidar detection, reduces the effect of volumetric backscatter for underwater imaging application, leading to an improved signal-to-noise-ratio (SNR) and contrast, for a given range. Initial underwater target detection tests conducted at Patuxent River Naval Air Station, MD, in a large water-tank facility, validates the advantages of this hybrid-lidar-radar (HLR) approach for improved underwater imaging, over a wide range of turbidity levels and both white and black targets. The compact, robust and power-efficient fiber laser architecture lends very well to lidar sensor integration on unmanned-underwater-vehicle (UUV) platforms. HLR transmitters can also provide similar advantages in active-sensing situations dominated by continuous backscatter, e.g. underwater communications, imaging through smoke and fire environment, rotor-craft landing in degraded visual environment, and pointing-tracking of active-EO sensors through fog.

  20. High Average Power, High Energy Short Pulse Fiber Laser System

    SciTech Connect

    Messerly, M J

    2007-11-13

    Recently continuous wave fiber laser systems with output powers in excess of 500W with good beam quality have been demonstrated [1]. High energy, ultrafast, chirped pulsed fiber laser systems have achieved record output energies of 1mJ [2]. However, these high-energy systems have not been scaled beyond a few watts of average output power. Fiber laser systems are attractive for many applications because they offer the promise of high efficiency, compact, robust systems that are turn key. Applications such as cutting, drilling and materials processing, front end systems for high energy pulsed lasers (such as petawatts) and laser based sources of high spatial coherence, high flux x-rays all require high energy short pulses and two of the three of these applications also require high average power. The challenge in creating a high energy chirped pulse fiber laser system is to find a way to scale the output energy while avoiding nonlinear effects and maintaining good beam quality in the amplifier fiber. To this end, our 3-year LDRD program sought to demonstrate a high energy, high average power fiber laser system. This work included exploring designs of large mode area optical fiber amplifiers for high energy systems as well as understanding the issues associated chirped pulse amplification in optical fiber amplifier systems.

  1. Raman soliton generation in microstructured tellurite fiber pumped by hybrid Erbium/Thulium fiber laser system

    NASA Astrophysics Data System (ADS)

    Anashkina, E. A.; Koptev, M. Y.; Muravyev, S. V.; Dorofeev, V. V.; Andrianov, A. V.; Kim, A. V.

    2016-08-01

    We demonstrate a fibre laser source generating ultrashort pulses tunable in the range 2-2.5 μm. The source is based on a hybrid Er/Tm fiber laser system and microstructured suspended-core tellurite fiber where Raman soliton shifting occurs. Nonlinear soliton dynamics is studied and possibility of tuning beyond 3 μm is shown.

  2. Large Mode Area Yb-Doped Photonic Bandgap Fiber Lasers

    DTIC Science & Technology

    2015-02-08

    ABSTRACT 16. SECURITY CLASSIFICATION OF: All-solid photonic bandgap fibers (PBGF) can be spectrally tailored to suppress amplified spontaneous emission...ASE) and stimulated Raman scattering (SRS). Furthermore, this type of fiber is attractive for realizing high-power narrow-linewidth amplifiers as...area Yb-doped photonic bandgap fiber lasers Report Title All-solid photonic bandgap fibers (PBGF) can be spectrally tailored to suppress amplified

  3. Hollow steel tips for reducing distal fiber burn-back during thulium fiber laser lithotripsy.

    PubMed

    Hutchens, Thomas C; Blackmon, Richard L; Irby, Pierce B; Fried, Nathaniel M

    2013-07-01

    The use of thulium fiber laser (TFL) as a potential alternative laser lithotripter to the clinical holmium:YAG laser is being studied. The TFL's Gaussian spatial beam profile provides efficient coupling of higher laser power into smaller core fibers without proximal fiber tip degradation. Smaller fiber diameters are more desirable, because they free up space in the single working channel of the ureteroscope for increased saline irrigation rates and allow maximum ureteroscope deflection. However, distal fiber tip degradation and "burn-back" increase as fiber diameter decreases due to both excessive temperatures and mechanical stress experienced during stone ablation. To eliminate fiber tip burn-back, the distal tip of a 150-μm core silica fiber was glued inside 1-cm-long steel tubing with fiber tip recessed 100, 250, 500, 1000, or 2000 μm inside the steel tubing to create the hollow-tip fiber. TFL pulse energy of 34 mJ with 500-μs pulse duration and 150-Hz pulse rate was delivered through the hollow-tip fibers in contact with human calcium oxalate monohydrate urinary stones during ex vivo studies. Significant fiber tip burn-back and degradation was observed for bare 150-μm core-diameter fibers. However, hollow steel tip fibers experienced minimal fiber burn-back without compromising stone ablation rates. A simple, robust, compact, and inexpensive hollow fiber tip design was characterized for minimizing distal fiber burn-back during the TFL lithotripsy. Although an increase in stone retropulsion was observed, potential integration of the hollow fiber tip into a stone basket may provide rapid stone vaporization, while minimizing retropulsion.

  4. Microscopic analysis of laser-induced proximal fiber tip damage during holmium:YAG and thulium fiber laser lithotripsy

    NASA Astrophysics Data System (ADS)

    Wilson, Christopher R.; Hardy, Luke A.; Irby, Pierce B.; Fried, Nathaniel M.

    2016-04-01

    The thulium fiber laser (TFL) is being studied as an alternative to the standard holmium:YAG laser for lithotripsy. The TFL beam originates within an 18-μm-core thulium-doped silica fiber, and its near single mode, Gaussian beam profile enables transmission of higher laser power through smaller (e.g., 50- to 150-μm core) fibers than possible during holmium laser lithotripsy. This study examines whether the more uniform TFL beam profile also reduces proximal fiber tip damage compared with the holmium laser multimodal beam. Light and confocal microscopy images were taken of the proximal surface of each fiber to inspect for possible laser-induced damage. A TFL beam at a wavelength of 1908 nm was coupled into 105-μm-core silica fibers, with 35-mJ energy, and 500-μs pulse duration, and 100,000 pulses were delivered at each pulse rate setting of 50, 100, 200, 300, and 400 Hz. For comparison, single use, 270-μm-core fibers were collected after clinical holmium laser lithotripsy procedures performed with standard settings (600 mJ, 350 μs, 6 Hz). Total laser energy, number of laser pulses, and laser irradiation time were recorded, and fibers were rated for damage. For TFL studies, output pulse energy and average power were stable, and no proximal fiber damage was observed at settings up to 35 mJ, 400 Hz, and 14 W average power (n=5). In contrast, confocal microscopy images of fiber tips after holmium lithotripsy showed proximal fiber tip degradation, indicated by small ablation craters on the scale of several micrometers in all fibers (n=20). In summary, the proximal fiber tip of a 105-μm-core fiber transmitted up to 14 W of TFL power without degradation, compared to degradation of 270-μm-core fibers after transmission of 3.6 W of holmium laser power. The smaller and more uniform TFL beam profile may improve fiber lifetime, and potentially translate into lower costs for the surgical disposables as well.

  5. Incoherent Combining of High-Power Fiber Lasers for Directed-Energy Applications

    DTIC Science & Technology

    2008-01-16

    fiber lasers , IPG Photonics currently holds the record, producing over 3 kW per fiber of single-mode laser ...energy laser systems. The first field demonstration of incoherent beam combining using kilowatt -class, single-mode fiber lasers over a kilometer...combining using kilowatt -class, single-mode fiber lasers . The experiment combined four fiber lasers using a beam director consisting of

  6. Influence of the UV-induced fiber loss on the distributed feedback fiber lasers

    NASA Astrophysics Data System (ADS)

    Fan, Wei; Chen, Bai; Qiao, Qiquan; Chen, Jialing; Lin, Zunqi

    2003-06-01

    It was found that the output power of the distributed feedback fiber lasers would be improved after annealing or left unused for several days after the laser had been fabricated, and the output of the fundamental mode would not increase but be clamped while the ±1 order modes would be predominant with the enhancement of the coupling coefficient during the fabrication. The paper discussed the influence of UV-induced fiber loss on the fiber phase-shifted DFB lasers. Due to the gain saturation and fiber internal loss, which included the temperament loss and permanent loss, there was an optimum coupling coefficient for the DFB fiber lasers that the higher internal fiber loss corresponded to the lower optimum values of coupling coefficient.

  7. OSNR enhancement utilizing large effective area fiber in a multiwavelength Brillouin-Raman fiber laser

    NASA Astrophysics Data System (ADS)

    Sonee Shargh, R.; Al-Mansoori, M. H.; Anas, S. B. A.; Sahbudin, R. K. Z.; Mahdi, M. A.

    2011-02-01

    We propose a simple Brillouin-Raman multi-channel fiber laser with supportive Rayleigh scattering in a linear cavity without employing any feedback mirrors at the end of cavity. Brillouin and the consequences of Rayleigh scattering work as virtual mirrors. We employ a section of large effective area fiber in addition to a section of dispersion compensating fiber to enhance the optical signal-to-noise ratio of multi-channel Brillouin-Raman comb fiber laser. We able to produce a flat comb fiber laser with 37 nm bandwidth from 1539 to 1576 nm built-in 460 Stokes lines with 0.08 nm spacing. Furthermore, this Brillouin-Raman comb fiber laser has acceptable optical signal-to-noise ratio value of 16.8 dB for the entire bandwidth with excellent flatness and low discrepancies in power levels of about 2.3 dB between odd and even channels.

  8. Ultrashort pulsed fiber laser welding and sealing of transparent materials.

    PubMed

    Huang, Huan; Yang, Lih-Mei; Liu, Jian

    2012-05-20

    In this paper, methods of welding and sealing optically transparent materials using an ultrashort pulsed (USP) fiber laser are demonstrated which overcome the limit of small area welding of optical materials. First, the interaction of USP fiber laser radiation inside glass was studied and single line welding results with different laser parameters were investigated. Then multiline scanning was used to obtain successful area bonding. Finally, complete four-edge sealing of fused silica substrates with a USP laser was demonstrated and the hermetic seal was confirmed by water immersion test. This laser microwelding technique can be extended to various applications in the semiconductor industry and precision optic manufacturing.

  9. OEM fiber laser rangefinder for long-distance measurement

    NASA Astrophysics Data System (ADS)

    Corman, Alexandre; Chiquet, Frédéric; Avisse, Thomas; Le Flohic, Marc

    2015-05-01

    SensUp designs and manufactures electro-optical systems based on laser technology, in particular from fiber lasers. Indeed, that kind of source enables us to get a significant peak power with huge repetition rates at the same time, thus combining some characteristics of the two main technologies on the telemetry field today: laser diodes and solid-state lasers. The OEM (Original Equipment Manufacturer) fiber Laser RangeFinder (LRF) set out below, aims to fit the SWaP (Size Weight and Power) requirements of military markets, and might turn out to be a real alternative to other technologies usually used in range finding systems.

  10. Cavitation-free CW laser ablation from a solid target to synthesize low size-dispersed Au nanoparticles.

    PubMed

    Kabashin, Andrei V; Kucherik, Alexei; Ryabchikov, Yury; Kutrovskaya, Stella; Al-Kattan, Ahmed; Arakelyan, Sergei; Itina, Tatiana

    2017-02-27

    Continuous wave (CW) radiation from Yb-fiber laser (central wave length is 1064 nm, power 1-200 W) is used to initiate ablation of material Au target in deionized water and synthesize bare (unprotected) Au nanoparticles. We show that the formed nanoparticles present a single low-size-dispersed population with the mean size of the order of 10 nm, which contrasts to previously reported data on dual populations of nanoparticles during pulsed laser ablation in liquids. The lacking second population of nanoparticles is explained by the absence of cavitation-related mechanism of material ablation, which typically takes place under pulsed laser action on a solid target in liquid ambience, and this supposition is confirmed by plume visualization tests. We also observe a gradual growth of mean nanoparticles size from 8-10 to 20-25 nm under the increase of laser power for 532 nm pumping wavelength, while for 1064 nm pumping wavelength the mean size 8-10 nm is independent of radiation power. The growth of the nanoparticles observed for 532 nm wavelength is attributed to the enhanced target melting and splashing followed by an additional heating due to an efficient excitation of plasmons over Au nanoparticles. Bare, low-size-dispersed Au nanoparticles are of importance for a variety of applications, including biomedicine, catalysis, photovoltaics etc., whereas the employment of CW radiation for nanomaterial production promises an improvement of cost-efficiency of this technology.

  11. High-resolution measurement of fiber length by using a mode-locked fiber laser configuration.

    PubMed

    Hu, Y L; Zhan, L; Zhang, Z X; Luo, S Y; Xia, Y X

    2007-06-15

    A simple method to precisely measure fiber length has been experimentally demonstrated by using a mode-locked fiber laser configuration. Since the transit time in a cavity is exactly proportional to the cavity length, it is easy to obtain the fiber length from the generation of mode-locked pulses in the fiber laser with a long-range nonlinear optical loop mirror that includes the measured fiber. Our new method has a large measurement range, over hundreds of kilometers, and a high resolution, of the order of centimeters, as well as no measurement dead zone.

  12. Fiber Optic Laser Delivery For Endarterectomy Of Experimental Atheromas

    NASA Astrophysics Data System (ADS)

    Eugene, John; Pollock, Marc E.; McColgan, Stephen J.; Hammer-Wilson, Marie; Berns, Michael W.

    1986-08-01

    Fiber optic delivery of argon ion laser energy and Nd-YAG laser energy were compared by the performance of open laser endarterectomy in the rabbit arteriosclerosis model. In Group I, 6 open laser endarterectomies were performed with an argon ion laser (488 nm and 514.5 nm) with the laser beam directed through a 400 pm quartz fiber optic. In Group II, 6 open laser endarterectomies were performed with a Nd-YAG laser (1.06 pm) with the laser beam directed through a 600 pm quartz fiber optic. Gross and light microscopic examination revealed smooth endarterectomy surfaces with tapered end points in Group I. In Group II, the endarterectomy surfaces were uneven and perforation occurred at 5/6 end points. Although energy could be precisely delivered with each laser by fiber optics, satisfactory results could only be achieved with the argon ion laser because argon ion energy was well absorbed by atheromas. Successful intravascular laser use requires a strong interaction between wavelength and atheroma as well as a precise delivery system.

  13. High energy green nanosecond and picosecond pulse delivery through a negative curvature fiber for precision micro-machining.

    PubMed

    Jaworski, Piotr; Yu, Fei; Carter, Richard M; Knight, Jonathan C; Shephard, Jonathan D; Hand, Duncan P

    2015-04-06

    In this paper we present an anti-resonant guiding, low-loss Negative Curvature Fiber (NCF) for the efficient delivery of high energy short (ns) and ultrashort (ps) pulsed laser light in the green spectral region. The fabricated NCF has an attenuation of 0.15 dB/m and 0.18 dB/m at 532 nm and 515 nm respectively, and provided robust transmission of nanosecond and picosecond pulses with energies of 0.57 mJ (10.4 kW peak power) and 30 µJ (5 MW peak power) respectively. It provides single-mode, stable (low bend-sensitivity) output and maintains spectral and temporal properties of the source laser beam. The practical application of fiber-delivered pulses has been demonstrated in precision micro-machining and marking of metals and glass.

  14. Enhanced characteristics of fused silica fibers using laser polishing

    NASA Astrophysics Data System (ADS)

    Heptonstall, A.; Barton, M. A.; Bell, A. S.; Bohn, A.; Cagnoli, G.; Cumming, A.; Grant, A.; Gustafson, E.; Hammond, G. D.; Hough, J.; Jones, R.; Kumar, R.; Lee, K.; Martin, I. W.; Robertson, N. A.; Rowan, S.; Strain, K. A.; Tokmakov, K. V.

    2014-05-01

    The search for gravitational wave signals from astrophysical sources has led to the current work to upgrade the two largest of the long-baseline laser interferometers, the LIGO detectors. The first fused silica mirror suspensions for the Advanced LIGO gravitational wave detectors have been installed at the LIGO Hanford and Livingston sites. These quadruple pendulums use synthetic fused silica fibers produced using a CO2 laser pulling machine to reduce thermal noise in the final suspension stage. The suspension thermal noise in Advanced LIGO is predicted to be limited by internal damping in the surface layer of the fibers, damping in the weld regions, and the strength of the fibers. We present here a new method for increasing the fracture strength of fused silica fibers by laser polishing of the stock material from which they are produced. We also show measurements of mechanical loss in laser polished fibers, showing a reduction of 30% in internal damping in the surface layer.

  15. Improving the therapeutic window of retinal photocoagulation by spatial and temporal modulation of the laser beam

    NASA Astrophysics Data System (ADS)

    Sramek, Christopher; Leung, Loh-Shan; Leng, Theodore; Brown, Jefferson; Paulus, Yannis M.; Schuele, Georg; Palanker, Daniel

    2011-02-01

    Decreasing the pulse duration helps confine damage, shorten treatment time, and minimize pain during retinal photocoagulation. However, the safe therapeutic window (TW), the ratio of threshold powers for thermomechanical rupture of Bruch's membrane and mild coagulation, also decreases with shorter exposures. Two potential approaches toward increasing TW are investigated: (a) decreasing the central irradiance of the laser beam and (b) temporally modulating the pulse. An annular beam with adjustable central irradiance was created by coupling a 532-nm laser into a 200-μm core multimode optical fiber at a 4-7 deg angle to normal incidence. Pulse shapes were optimized using a computational model, and a waveform generator was used to drive a PASCAL photocoagulator (532 nm), producing modulated laser pulses. Acute thresholds for mild coagulation and rupture were measured in Dutch-Belted rabbit in vivo with an annular beam (154-163 μm retinal diameter) and modulated pulse (132 μm, uniform irradiance ``flat-top'' beam) with 2-50 ms pulse durations. Thresholds with conventional constant-power pulse and a flat-top beam were also determined. Both annular beam and modulated pulse provided a 28% increase in TW at 10-ms duration, affording the same TW as 20-ms pulses with conventional parameters.

  16. High Power 938nm Cladding Pumped Fiber Laser

    SciTech Connect

    Dawson, J; Beach, R; Brobshoff, A; Liao, Z; Payne, S; Pennington, D; Taylor, L; Hackenberg, W; Bonaccini, D

    2002-12-26

    We have developed a Nd:doped cladding pumped fiber amplifier, which operates at 938nm with greater than 2W of output power. The core co-dopants were specifically chosen to enhance emission at 938nm. The fiber was liquid nitrogen cooled in order to achieve four-level laser operation on a laser transition that is normally three level at room temperature, thus permitting efficient cladding pumping of the amplifier. Wavelength selective attenuation was induced by bending the fiber around a mandrel, which permitted near complete suppression of amplified spontaneous emission at 1088nm. We are presently seeking to scale the output of this laser to 10W. We will discuss the fiber and laser design issues involved in scaling the laser to the 10W power level and present our most recent results.

  17. Characterization of novel optical fibers for use in laser detonators

    NASA Astrophysics Data System (ADS)

    Bowden, M. D.; Drake, R. C.; Singleton, C. A.

    2006-08-01

    A system for launching flyers using a Q-switched Nd: YAG laser has been developed for shock initiation of secondary explosives. Flyers have been launched at velocities approaching 6 km s -1. Optical fibers are used to transport the optical energy from the laser to the detonator. The launch of these flyers with sufficient velocity requires a fluence in the region of 35 J cm -2, significantly above the damage threshold of most optical fibers. This damage is typically caused by laser absorption at the input face due to imperfections in the surface polishing. A variety of optical fibers with high quality input faces have been tested at fluences up to 50 J cm -2, and their damage thresholds and beam profiles have been measured. The standard fiber used in this system is a low hydroxyl (-OH) content, 400μm diameter core silica fiber, with CO2 laser polished faces. In addition to this, fibers tapering down to 300μm and 200μm core diameter were investigated, as a means of increasing the efficiency of the system, along with mechanically polished fibers. The fiber currently enters the detonator body from the rear. Depending on the application, it may be required for the fiber to enter from the side. To facilitate this, fibers with a machined output face, designed to produce an output at approximately 90 degrees to the fiber axis were tested. Finally, a 2:1 fiber splitter was tested, as a first step to enable simultaneous firing of several detonators. Multiple initiation points are desirable for applications such as programmable initiation, and it is intended to study fiber splitters with a higher split ratio, such as 4:1 and 8:1. The results of these experiments are presented, and assessments made of suitability for transmission of high-power Qswitched Nd:YAG laser pulses.

  18. Integrated Sagnac loop mirror circuit for fiber laser

    NASA Astrophysics Data System (ADS)

    Lee, Tae Ho; Kim, Chang-Seok; Jeong, Myung Yung

    2007-02-01

    Broadband reflection mirror is an important optical device to make a wide resonance bandwidth of the multi-wavelength fiber laser cavity including fiber Bragg grating mirrors. Though a chirped fiber Bragg grating has been used for broadband reflection mirror device, it still requires more improvements in the control of reflection wavelength bandwidth and reflection ratio, which are key design parameters of broadband reflection mirror. In this research, we propose an integrated mirror circuit based on polarization-maintaining fiber Sagnac loop interferometer to utilize for tunable resonance cavity of fiber laser with semiconductor optical amplifier. It is available to control both resonance bandwidth by varying the length of polarization-maintaining fiber and reflection ratio by tuning the polarization state of Sagnac loop. Broad resonance bandwidth of 40 nm could be obtained from Sagnac mirror with thes 0.15 m length of polarization-maintaining fiber.

  19. Laser-machined fibers as Fabry-Perot pressure sensors.

    PubMed

    Watson, Stuart; Gander, Matthew J; MacPherson, William N; Barton, James S; Jones, Julian D C; Klotzbuecher, Thomas; Braune, Torsten; Ott, Johannes; Schmitz, Felix

    2006-08-01

    Cavities have been laser ablated in the ends of single-mode optical fibers and sealed by aluminized polycarbonate diaphragms to produce Fabry-Perot pressure sensors. Both conventional fibers and novel, multicore fibers were used, demonstrating the possibility of producing compact arrays of sensors and multiple sensors on an individual fiber 125 microm in diameter. This high spatial resolution can be combined with high temporal resolution by simultaneously interrogating the sensors by using separate laser sources at three wavelengths. Shock tube tests showed a sensor response time of 3 micros to a step increase in pressure.

  20. High power 938 nanometer fiber laser and amplifier

    DOEpatents

    Dawson, Jay W.; Liao, Zhi Ming; Beach, Raymond J.; Drobshoff, Alexander D.; Payne, Stephen A.; Pennington, Deanna M.; Hackenberg, Wolfgang; Calia, Domenico Bonaccini; Taylor, Luke

    2006-05-02

    An optical fiber amplifier includes a length of silica optical fiber having a core doped with neodymium, a first cladding and a second cladding each with succeeding lower refractive indices, where the first cladding diameter is less than 10 times the diameter of the core. The doping concentration of the neodymium is chosen so that the small signal absorption for 816 nm light traveling within the core is less than 15 dB/m above the other fiber losses. The amplifier is optically pumped with one laser into the fiber core and with another laser into the first cladding.

  1. Statistical properties of partially coherent cw fiber lasers.

    PubMed

    Churkin, Dmitriy V; Smirnov, Sergey V; Podivilov, Evgenii V

    2010-10-01

    We perform a detailed quantitative numerical analysis of a partially coherent quasi-cw fiber laser on the example of a high-Q normal dispersion cavity Raman fiber laser. The key role of precise spectral performances of fiber Bragg gratings forming the laser cavity is clarified. It is shown that cross-phase modulation between the pump and Stokes waves does not affect the generation. Amplitudes of different longitudinal modes strongly fluctuate, obeying the Gaussian distribution. As the intensity statistics is noticeably nonexponential, longitudinal modes should be correlated.

  2. Multi-kW cw fiber oscillator pumped by wavelength stabilized fiber coupled diode lasers

    NASA Astrophysics Data System (ADS)

    Becker, Frank; Neumann, Benjamin; Winkelmann, Lutz; Belke, Steffen; Ruppik, Stefan; Hefter, Ulrich; Köhler, Bernd; Wolf, Paul; Biesenbach, Jens

    2013-02-01

    High power Yb doped fiber laser sources are beside CO2- and disk lasers one of the working horses of industrial laser applications. Due to their inherently given robustness, scalability and high efficiency, fiber laser sources are best suited to fulfill the requirements of modern industrial laser applications in terms of power and beam quality. Pumping Yb doped single-mode fiber lasers at 976nm is very efficient. Thus, high power levels can be realized avoiding limiting nonlinear effects like SRS. However the absorption band of Yb doped glass around 976nm is very narrow. Therefore, one has to consider the wavelength shift of the diode lasers used for pumping. The output spectrum of passively cooled diode lasers is mainly defined by the applied current and by the heat sink temperature. Furthermore the overall emission line width of a high power pump source is dominated by the large number of needed diode laser emitters, each producing an individual spectrum. Even though it is possible to operate multi-kW cw single-mode fiber lasers with free running diode laser pumps, wavelength stabilizing techniques for diode lasers (e.g. volume holographic gratings, VHG) can be utilized in future fiber laser sources to increase the output power level while keeping the energy consumption constant. To clarify the benefits of wavelength stabilized diode lasers with integrated VHG for wavelength locking the performance of a dual side pumped fiber oscillator is discussed in this article. For comparison, different pumping configurations consisting of stabilized and free-running diode lasers are presented.

  3. Fiber optic muzzle brake tip for reducing fiber burnback and stone retropulsion during thulium fiber laser lithotripsy

    NASA Astrophysics Data System (ADS)

    Hutchens, Thomas C.; Gonzalez, David A.; Irby, Pierce B.; Fried, Nathaniel M.

    2017-01-01

    The experimental thulium fiber laser (TFL) is being explored as an alternative to the current clinical gold standard Holmium:YAG laser for lithotripsy. The near single-mode TFL beam allows coupling of higher power into smaller optical fibers than the multimode Holmium laser beam profile, without proximal fiber tip degradation. A smaller fiber is desirable because it provides more space in the ureteroscope working channel for increased saline irrigation rates and allows maximum ureteroscope deflection. However, distal fiber tip burnback increases as fiber diameter decreases. Previous studies utilizing hollow steel sheaths around recessed distal fiber tips reduced fiber burnback but increased stone retropulsion. A "fiber muzzle brake" was tested for reducing both fiber burnback and stone retropulsion by manipulating vapor bubble expansion. TFL lithotripsy studies were performed at 1908 nm, 35 mJ, 500 μs, and 300 Hz using a 100-μm-core fiber. The optimal stainless steel muzzle brake tip tested consisted of a 1-cm-long, 560-μm-outer-diameter, 360-μm-inner-diameter tube with a 275-μm-diameter through hole located 250 μm from the distal end. The fiber tip was recessed a distance of 500 μm. Stone phantom retropulsion, fiber tip burnback, and calcium oxalate stone ablation studies were performed ex vivo. Small stones with a mass of 40±4 mg and 4-mm-diameter were ablated over a 1.5-mm sieve in 25±4 s (n=10) without visible distal fiber tip burnback. Reduction in stone phantom retropulsion distance by 50% and 85% was observed when using muzzle brake tips versus 100-μm-core bare fibers and hollow steel tip fibers, respectively. The muzzle brake fiber tip simultaneously provided efficient stone ablation, reduced stone retropulsion, and minimal fiber degradation during TFL lithotripsy.

  4. Power scaling of Tm3+ doped ZBLAN blue upconversion fiber lasers: modeling and experiments

    NASA Astrophysics Data System (ADS)

    Qin, G.; Huang, S.; Feng, Y.; Shirakawa, A.; Musha, M.; Ueda, K.-I.

    2006-01-01

    Power scaling of Tm3+ doped ZBLAN blue upconversion fiber lasers was investigated by a simple model. Based on our experimental results on blue fiber lasers, we discuss the effects of photodegradation and photocuring, fiber length, the reflectivity of the coupler mirror and fiber core diameter on further enhancement of blue fiber laser, respectively. The optimal parameters (including fiber length, fiber core diameter and the reflectivity of the coupler mirror) for the operation of high power (>1 W) blue fiber laser were presented through simple numerical simulations, which are valuable for the future design of high power blue upconversion fiber laser.

  5. A novel two-way wavelength division multiplexed fiber laser

    NASA Astrophysics Data System (ADS)

    Ke, Hung-Jen; Chiu, Jian-Lin; Chiang, Chia-Chin; Tsao, Shyh-Lin

    2006-08-01

    We use the fiber loop mirror to form a cavity in our laser system, and two 1.5 μm semiconductor optical amplifier (SOA) also be used as a gain material in the cavity. We analyze the lasing power, SMSR, L-I curve and the stability of our designed symmetric resonator laser with various driving current of the SOA. According to our measured results, we can find that the polarization states of our lasers are stable and the output side-mode suppression ration (SMSR) of our laser is large. We successfully designed a symmetric two-way multi-wavelength wavelength-division-multiplexed (WDM) resonator laser system. The multi-wavelength continuous-wave(CW) fiber laser by utilizing the Fabry-Perot resonance can be applied to PolSK fiber-optic communication systems.

  6. Nd/sup 3 +/-doped cw fiber laser using all-fiber reflectors

    SciTech Connect

    Miller, I.D.; Mortimore, D.B.; Urquhart, P.; Ainslie, B.J.; Craig, S.P.; Miller, C.A.; Payne, D.B.

    1987-06-01

    We demonstrate a novel all-fiber resonant optical cavity which uses two-fiber reflectors, each formed by a single loop of fiber between the output ports of a fiber directional coupler. The reflectivities of the fiber mirrors are each determined by the coupling ratio and the insertion loss of the fused couplers. When the cavity is formed in this way using a continuous length of Nd/sup 3 +/-doped fiber and pumped using a GaAs laser diode, lasing occurs at a wavelength of 1064 nm. Both theoretical and practical descriptions of the device are given.

  7. The development of novel Ytterbium fiber lasers and their applications

    NASA Astrophysics Data System (ADS)

    Nie, Bai

    The aim of my Ph.D. research is to push the fundamental limits holding back the development of novel Yb fiber lasers with high pulse energy and short pulse duration. The purpose of developing these lasers is to use them for important applications such as multiphoton microscopy and laser-induced breakdown spectroscopy. My first project was to develop a short-pulse high-energy ultrafast fiber laser for multiphoton microscopy. To achieve high multiphoton efficiency and depth resolved tissue imaging, ultrashort pulse duration and high pulse energy are required. In order to achieve this, an all-normal dispersion cavity design was adopted. Output performances of the built lasers were investigated by varying several cavity parameters, such as pump laser power, fiber length and intra-cavity spectral filter bandwidth. It was found that the length of the fiber preceding the gain fiber is critical to the laser performance. Generally, the shorter the fiber is, the broader the output spectrum is. The more interesting parameter is the intra-cavity spectral filter bandwidth. Counter intuitively, laser cavities using narrower bandwidth spectral filters generated much broader spectra. It was also found that fiber lasers with very narrow spectral filters produced laser pulses with parabolic profile, which are referred to as self-similar pulses or similaritons. This type of pulse can avoid wave-breaking and is an optimal approach to generate pulses with high pulse energy and ultrashort pulse duration. With a 3nm intra-cavity spectral filter, output pulses with about 20 nJ pulse energy were produced and compressed to about 41 fs full-width-at-half-maximum (FWHM) pulse duration. Due to the loss in the compression device, the peak power of the compressed pulses is about 250 kW. It was the highest peak power generated from a fiber oscillator when this work was published. This laser was used for multiphoton microscopy on living tissues like Drosophila larva and fruit fly wings. Several

  8. All fiber-based Yb-doped high energy, high power femtosecond fiber lasers.

    PubMed

    Wan, Peng; Yang, Lih-Mei; Liu, Jian

    2013-12-02

    Two all fiber-based laser systems are demonstrated to achieve high energy and high average power femtosecond pulsed outputs at wavelength of 1 µm. In the high energy laser system, a pulse energy of 1.05 mJ (0.85 mJ after pulse compressor) at 100 kHz repetition rate has been realized by a Yb-doped ultra large-core single-mode photonic crystal fiber (PCF) rod amplifier, seeded with a 50 µJ fiber laser. The pulse duration is 705 fs. In the high average power experiment, a large mode area (LMA) fiber has been used in the final stage amplifier, seeded with a 50 W mode locked fiber laser. The system is running at a repetition rate of 69 MHz producing 1052 W of average power before compressor. After pulse compression, a pulse duration of 800 fs was measured.

  9. High-power thulium-doped fiber laser in an all-fiber configuration

    NASA Astrophysics Data System (ADS)

    Baravets, Yauhen; Todorov, Filip; Honzatko, Pavel

    2016-12-01

    High-power Tm-doped fiber lasers are greatly suitable for various applications, such as material processing, medicine, environmental monitoring and topography. In this work we present an all-fiber narrowband CW laser in near fundamental mode operation based on a Tm-doped double-clad active fiber pumped by 793 nm laser diodes with a central wavelength stabilized at 2039 nm by a fiber Bragg grating. The achieved output power is 60 W with a slope efficiency of 46%. The measured beam quality factor is less than 1.4. Further increasing of the output power is possible using various power scaling techniques, for example, coherent combination of several Tm-doped fiber lasers. The developed fiber laser could be employed for welding, cutting and marking of thermoplastics in industry, minimally invasive surgery in medicine or sensors in lidar systems. Future improvements of thulium fiber lasers are possible due to the extremely wide gain-bandwidth of the active medium and the rapid growth of 2-μm fiber components production.

  10. Vibrating Optical Fibers to Make Laser Speckle Disappear

    NASA Technical Reports Server (NTRS)

    McGill, Matthew; Scott, V. Stanley

    2005-01-01

    In optical systems in which laser illumination is delivered via multimode optical fibers, laser speckle can be rendered incoherent by a simple but highly effective technique. The need to eliminate speckle arises because speckle can make it difficult to observe edges and other sharp features, thereby making it difficult to perform precision alignment of optical components. The basic ideas of the technique is to vibrate the optical fiber(s) to cause shifting of electromagnetic modes within the fiber(s) and consequent shifting of the speckle pattern in the light emerging from the fiber(s). If the frequency of vibration is high enough, a human eye cannot follow the shifting speckle pattern, so that instead of speckle, a human observer sees a smoothed pattern of light corresponding to a mixture of many electromagnetic modes. If necessary, the optical fiber(s) could be vibrated manually. However, in a typical laboratory situation, it would be more practical to attach a vibrating mechanism to the fiber(s) for routine use as part of the fiber-optic illuminator. In experiments, a commercially available small, gentle, quiet, variable- speed vibratory device was used in this way, with the result that the appearance of speckle was eliminated, as expected. Figures 1 and 2 illustrate the difference.

  11. Modeling compact high power fiber lasers and vecsels

    NASA Astrophysics Data System (ADS)

    Li, Hongbo

    Compact high power fiber lasers and the vertical-external-cavity surface-emitting lasers (VECSELs) are promising candidates for high power laser sources with diffraction-limited beam quality and are currently the subject of intensive research and development. Here three large mode area fiber lasers, namely, the photonic crystal fiber (PCF) laser, the multicore fiber (MCF) laser, and the multimode interference (MMI) fiber laser, as well as the VECSEL are modeled and designed. For the PCF laser, the effective refractive index and the effective core radius of the PCF are investigated using vectorial approaches and reformulated. Then, the classical step-index fiber theory is extended to PCFs, resulting in a highly efficient vectorial effective-index method for the design and analysis of PCFs. The new approach is employed to analyze the modal properties of the PCF lasers with depressed-index cores and to effectively estimate the number of guided modes for PCFs. The MCF laser, consisting of an active MCF and a passive coreless fiber, is modeled using the vectorial mode expansion method developed in this work. The results illustrate that the mode selection in the MCF laser by the coreless fiber section is determined by the MMI effect, not the Talbot effect. Based on the MMI and self-imaging in multimode fibers, the vectorial mode expansion approach is employed to design the first MMI fiber laser demonstrated experimentally. For the design and modeling of VECSELs, the optical, thermal, and structural properties of common material systems are investigated and the most reliable material models are summarized. The nanoscale heat transport theory is applied for the first time, to the best of my knowledge, to design and model VECSELs. In addition, the most accurate strain compensation approach is selected for VECSELs incorporating strained quantum wells to maintain structural stability. The design principles for the VECSEL subcavity are elaborated and applied to design a 1040nm

  12. Linear dissipative soliton in an anomalous-dispersion fiber laser.

    PubMed

    Wang, Ruixin; Dai, Yitang; Yin, Feifei; Xu, Kun; Li, Jianqiang; Lin, Jintong

    2014-12-01

    We report on the generation of linear dissipative soliton (LDS) from an erbium-doped actively mode-locked fiber laser. We show that depending on the down-chirping effect of quadratic phase modulation, instead of the fiber nonlinear Kerr effect in an all-normal-dispersion (ANDi) cavity, stable LDS can be realized in the linear dissipative system. The DS operation of ANDi laser and LDS operation of anomalous dispersion laser are experimentally investigated and compared, and the formation mechanisms of the DS and LDS are discussed. Finally, optical frequency comb generated by the LDS laser is demonstrated.

  13. High-power synchronously pumped femtosecond Raman fiber laser.

    PubMed

    Churin, D; Olson, J; Norwood, R A; Peyghambarian, N; Kieu, K

    2015-06-01

    We report a high-power synchronously pumped femtosecond Raman fiber laser operating in the normal dispersion regime. The Raman laser is pumped by a picosecond Yb(3+)-doped fiber laser. It produces highly chirped pulses with energy up to 18 nJ, average power of 0.76 W and 88% efficiency. The pulse duration is measured to be 147 fs after external compression. We observed two different regimes of operation of the laser: coherent and noise-like regime. Both regimes were experimentally characterized. Numerical simulations are in a good agreement with experimental results.

  14. Small core fiber coupled 60-W laser diode

    NASA Astrophysics Data System (ADS)

    Fernie, Douglas P.; Mannonen, Ilkka; Raven, Anthony L.

    1995-05-01

    Semiconductor laser diodes are compact, efficient and reliable sources of laser light and 25 W fiber coupled systems developed by Diomed have been in clinical use for over three years. For certain applications, particularly in the treatment of benign prostatic hyperplasia and flexible endoscopy, higher powers are desirable. In these applications the use of flexible optical fibers of no more than 600 micrometers core diameter is essential for compatibility with most commercial delivery fibers and instrumentation. A high power 60 W diode laser system for driving these small core fibers has been developed. The design requirements for medical applications are analyzed and system performance and results of use in gastroenterology and urology with small core fibers will be presented.

  15. Optical fiber sensing based on reflection laser spectroscopy.

    PubMed

    Gagliardi, Gianluca; Salza, Mario; Ferraro, Pietro; Chehura, Edmond; Tatam, Ralph P; Gangopadhyay, Tarun K; Ballard, Nicholas; Paz-Soldan, Daniel; Barnes, Jack A; Loock, Hans-Peter; Lam, Timothy T-Y; Chow, Jong H; De Natale, Paolo

    2010-01-01

    An overview on high-resolution and fast interrogation of optical-fiber sensors relying on laser reflection spectroscopy is given. Fiber Bragg-gratings (FBGs) and FBG resonators built in fibers of different types are used for strain, temperature and acceleration measurements using heterodyne-detection and optical frequency-locking techniques. Silica fiber-ring cavities are used for chemical sensing based on evanescent-wave spectroscopy. Various arrangements for signal recovery and noise reduction, as an extension of most typical spectroscopic techniques, are illustrated and results on detection performances are presented.

  16. High-Power Fiber Lasers Using Photonic Band Gap Materials

    NASA Technical Reports Server (NTRS)

    DiDomenico, Leo; Dowling, Jonathan

    2005-01-01

    High-power fiber lasers (HPFLs) would be made from photonic band gap (PBG) materials, according to the proposal. Such lasers would be scalable in the sense that a large number of fiber lasers could be arranged in an array or bundle and then operated in phase-locked condition to generate a superposition and highly directed high-power laser beam. It has been estimated that an average power level as high as 1,000 W per fiber could be achieved in such an array. Examples of potential applications for the proposed single-fiber lasers include welding and laser surgery. Additionally, the bundled fibers have applications in beaming power through free space for autonomous vehicles, laser weapons, free-space communications, and inducing photochemical reactions in large-scale industrial processes. The proposal has been inspired in part by recent improvements in the capabilities of single-mode fiber amplifiers and lasers to produce continuous high-power radiation. In particular, it has been found that the average output power of a single strand of a fiber laser can be increased by suitably changing the doping profile of active ions in its gain medium to optimize the spatial overlap of the electromagnetic field with the distribution of active ions. Such optimization minimizes pump power losses and increases the gain in the fiber laser system. The proposal would expand the basic concept of this type of optimization to incorporate exploitation of the properties (including, in some cases, nonlinearities) of PBG materials to obtain power levels and efficiencies higher than are now possible. Another element of the proposal is to enable pumping by concentrated sunlight. Somewhat more specifically, the proposal calls for exploitation of the properties of PBG materials to overcome a number of stubborn adverse phenomena that have impeded prior efforts to perfect HPFLs. The most relevant of those phenomena is amplified spontaneous emission (ASE), which causes saturation of gain and power

  17. Novel technique for mode selection in a multimode fiber laser.

    PubMed

    Daniel, J M O; Chan, J S P; Kim, J W; Sahu, J K; Ibsen, M; Clarkson, W A

    2011-06-20

    A simple technique for transverse mode selection in a large-mode-area (multimode) fiber laser is described. The technique exploits the different spectral responses of feedback elements based on a fiber Bragg grating and a volume Bragg grating to achieve wavelength-dependent mode filtering. This approach has been applied to a cladding-pumped thulium-doped fiber laser with a multimode core to achieve a single-spatial-mode output beam with a beam propagation factor (M2) of 1.05 at 1923 nm. Without mode selection the free-running fiber laser has a multimode output beam with an M2 parameter of 3.3. Selective excitation of higher order modes is also possible via the technique and preliminary results for laser oscillation on the LP11 mode are also discussed along with the prospects for scaling to higher power levels.

  18. SURFACE MORPHOLOGY OF CARBON FIBER POLYMER COMPOSITES AFTER LASER STRUCTURING

    SciTech Connect

    Sabau, Adrian S; Chen, Jian; Jones, Jonaaron F.; Alexandra, Hackett; Jellison Jr, Gerald Earle; Daniel, Claus; Warren, Charles David; Rehkopf, Jackie D.

    2015-01-01

    The increasing use of Carbon Fiber Polymer Composite (CFPC) as a lightweight material in automotive and aerospace industries requires the control of surface morphology. In this study, the composites surface was prepared by ablating the resin in the top fiber layer of the composite using an Nd:YAG laser. The CFPC specimens with T700S carbon fiber and Prepreg - T83 resin (epoxy) were supplied by Plasan Carbon Composites, Inc. as 4 ply thick, 0/90o plaques. The effect of laser fluence, scanning speed, and wavelength was investigated to remove resin without an excessive damage of the fibers. In addition, resin ablation due to the power variation created by a laser interference technique is presented. Optical property measurements, optical micrographs, 3D imaging, and high-resolution optical profiler images were used to study the effect of the laser processing on the surface morphology.

  19. Application of fiber laser for a Higgs factory

    SciTech Connect

    Chou, W.

    2014-06-04

    This paper proposes a medium size(~6km) circular Higgs factory based on a photon collider. The recent breakthrough in fiber laser technology by means of a coherent amplifier network makes such a collider feasible and probably also affordable.

  20. 126 W fiber laser at 1018 nm and its application in tandem pumped fiber amplifier

    NASA Astrophysics Data System (ADS)

    Yang, Hening; Zhao, Wei; Si, Jinhai; Zhao, Baoyin; Zhu, Yonggang

    2016-12-01

    We report on a 126 W fiber laser operating at 1018 nm with an optical efficiency of 75%. The optimal length for such a fiber laser is theoretically analyzed using steady-state rate equations including amplified spontaneous emission. Excellent agreement on the maximum output power is achieved between the numerical result and the experimental counterpart. Furthermore, a monolithic tandem pumped fiber amplifier is established by using conventional 30/250 μm double clad ytterbium-doped fiber, and 185 W output power with 85% optical efficiency is realized.

  1. Application and the key technology on high power fiber-optic laser in laser weapon

    NASA Astrophysics Data System (ADS)

    Qu, Zhou; Li, Qiushi; Meng, Haihong; Sui, Xin; Zhang, Hongtao; Zhai, Xuhua

    2014-12-01

    The soft-killing laser weapon plays an important role in photoelectric defense technology. It can be used for photoelectric detection, search, blinding of photoelectric sensor and other devices on fire control and guidance devices, therefore it draws more and more attentions by many scholars. High power fiber-optic laser has many virtues such as small volume, simple structure, nimble handling, high efficiency, qualified light beam, easy thermal management, leading to blinding. Consequently, it may be used as the key device of soft-killing laser weapon. The present study introduced the development of high power fiber-optic laser and its main features. Meanwhile the key technology of large mode area (LMA) optical fiber design, the beam combination technology, double-clad fiber technology and pumping optical coupling technology was stated. The present study is aimed to design high doping LMA fiber, ensure single mode output by increasing core diameter and decrease NA. By means of reducing the spontaneous emission particle absorbed by fiber core and Increasing the power density in the optical fiber, the threshold power of nonlinear effect can increase, and the power of single fiber will be improved. Meantime, high power will be obtained by the beam combination technology. Application prospect of high power fiber laser in photoelectric defense technology was also set forth. Lastly, the present study explored the advantages of high power fiber laser in photoelectric defense technology.

  2. Investigation of a Pulsed 1550 nm Fiber Laser System

    DTIC Science & Technology

    2015-12-15

    Jain 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT...14. ABSTRACT There is a strong need for a pulsed laser system at eye safe wavelengths for illuminator applications . High power pulsed 1550 nm fiber...system at eye safe wavelengths for illuminator applications . High power pulsed 1550 nm fiber lasers systems are able to generate, shaped, pulses at

  3. Even Illumination from Fiber-Optic-Coupled Laser Diodes

    NASA Technical Reports Server (NTRS)

    Howard, Richard T.

    2006-01-01

    A method of equipping fiber-optic-coupled laser diodes to evenly illuminate specified fields of view has been proposed. The essence of the method is to shape the tips of the optical fibers into suitably designed diffractive optical elements. One of the main benefits afforded by the method would be more nearly complete utilization of the available light. Diffractive optics is a relatively new field of optics in which laser beams are shaped by use of diffraction instead of refraction.

  4. Self-Frequency-Doubling Glass-Fiber Laser

    NASA Technical Reports Server (NTRS)

    Selker, Mark D.; Dallas, Joseph L.

    1993-01-01

    Specially prepared germanium and phosphorous-doped glass optical fiber doped with neodymium shown to act as self-frequency-doubling laser. Self-frequency-doubling fiber laser with further refinements, eliminates need for expensive, easily damaged, nonlinear crystals currently used. Enables one to avoid loss and damage mechanisms associated with interfaces of nonlinear crystals as well as to eliminate angle/temperature phase-matching tuning.

  5. All-fiber frequency-stabilized erbium doped ring laser.

    PubMed

    Marty, Patrick Thomas; Morel, Jacques; Feurer, Thomas

    2010-12-20

    We present an all-fiber frequency-stabilized ring laser system with an integrated reference gas cell consisting of a hollow core fiber filled with acetylene. Through nonlinear absorption spectroscopy the laser frequency is stabilized to a specific absorption line of acetylene. Three different stabilization schemes are investigated and the minimum Allan deviation obtained after 100 s is 4.4 · 10(-11).

  6. Simplified method for numerical modeling of fiber lasers.

    PubMed

    Shtyrina, O V; Yarutkina, I A; Fedoruk, M P

    2014-12-29

    A simplified numerical approach to modeling of dissipative dispersion-managed fiber lasers is examined. We present a new numerical iteration algorithm for finding the periodic solutions of the system of nonlinear ordinary differential equations describing the intra-cavity dynamics of the dissipative soliton characteristics in dispersion-managed fiber lasers. We demonstrate that results obtained using simplified model are in good agreement with full numerical modeling based on the corresponding partial differential equations.

  7. Laser Intensity Scaling Through Stimulated Scattering in Optical Fibers

    DTIC Science & Technology

    2007-11-02

    restriction this imposes on the power of a fiber laser or amplifier. The suppression was modeled using both a holmium dopant and adding a long period grating to...the wavelength of the laser, and the dotted line represents the first order Stokes beam. ......141 Figure 65: Holmium absorption in silicate glass...the molar % of holmium doped into the fiber....................................144 Figure 67: A long period grating couples light out of the core

  8. Fiber sensor systems based on fiber laser and microwave photonic technologies.

    PubMed

    Fu, Hongyan; Chen, Daru; Cai, Zhiping

    2012-01-01

    Fiber-optic sensors, especially fiber Bragg grating (FBG) sensors are very attractive due to their numerous advantages over traditional sensors, such as light weight, high sensitivity, cost-effectiveness, immunity to electromagnetic interference, ease of multiplexing and so on. Therefore, fiber-optic sensors have been intensively studied during the last several decades. Nowadays, with the development of novel fiber technology, more and more newly invented fiber technologies bring better and superior performance to fiber-optic sensing networks. In this paper, the applications of some advanced photonic technologies including fiber lasers and microwave photonic technologies for fiber sensing applications are reviewed. FBG interrogations based on several kinds of fiber lasers, especially the novel Fourier domain mode locking fiber laser, have been introduced; for the application of microwave photonic technology, examples of microwave photonic filtering utilized as a FBG sensing interrogator and microwave signal generation acting as a transversal loading sensor have been given. Both theoretical analysis and experimental demonstrations have been carried out. The comparison of these advanced photonic technologies for the applications of fiber sensing is carried out and important issues related to the applications have been addressed and the suitable and potential application examples have also been discussed in this paper.

  9. Laser diode pumped 106 mW blue upconversion fiber laser

    NASA Astrophysics Data System (ADS)

    Sanders, S.; Waarts, R. G.; Mehuys, D. G.; Welch, D. F.

    1995-09-01

    A laser diode pumped Tm3+-doped ZBLAN fiber upconversion laser is demonstrated with blue output power levels up to 106 mW. Differential optical-to-optical conversion efficiencies up to 30% are measured with respect to pump power coupled into the upconversion fiber. A single spatial mode blue output beam is demonstrated, with an M2 value of 1.4.

  10. Phase generated carrier technique for fiber laser hydrophone

    NASA Astrophysics Data System (ADS)

    Li, Rizhong; Wang, Xinbing; Huang, Junbin; Gu, Hongcan

    2013-08-01

    A distributed feedback (DFB) fiber laser is compact, and is very suitable for using as a hydrophone to sense acoustic pressure. A DFB fiber laser hydrophone was researched. In the fiber laser hydrophone signal demodulating system, an unbalanced Michelson fiber interferometer and a Phase Generated Carrier (PGC) method were used. The PGC method can be used to demodulating the acoustic signal from the interference signal. Comparing with the Naval Research Laboratory (NRL) method and Naval Postgraduate School (NPS) method, the digitized PGC method requires a greater amount of computation because of the high signal sampling, but it demands only one interference signal which makes the less fiber connections of the fiber laser hydrophone array. So the fiber laser hydrophone array based on the PGC method has lower complexity and higher reliability than that based on the NRL method or NPS method. The experimental results approve that the PGC method can demodulate acoustic signal between 20~2000 Hz frequency range with good signal-to-noise ratio (SNR) when the PZT driving frequency is 20 kHz.

  11. Tapered fiber bundles for combining high-power diode lasers.

    PubMed

    Kosterin, Andrey; Temyanko, Valery; Fallahi, Mahmoud; Mansuripur, Masud

    2004-07-01

    Tapered fiber bundles are often used to combine the output power of several semiconductor lasers into a multimode optical fiber for the purpose of pumping fiber lasers and amplifiers. It is generally recognized that the brightness of such combiners does not exceed the brightness of the individual input fibers. We report that the brightness of the tapered fibers (and fiber bundles) depends on both the taper ratio and the mode-filling properties of the beams launched into the individual fibers. Brightness, therefore, can be increased by selection of sources that fill a small fraction of the input fiber's modal capacity. As proof of concept, we present the results of measurements on tapered fiber-bundle combiners having a low-output étendue. Under low mode-filling conditions per input multimode fiber (i.e., fraction of filled modes < or =0.29), we report brightness enhancements of 8.0 dB for 19 x 1 bundles, 6.7 dB for 7 x 1 bundles, and 4.0 dB for 3 x 1 combiners. Our measured coupling efficiency variations of approximately 1%-2% among the various fibers in a given bundle confirm the uniformity and quality of the fabricated devices.

  12. Fiber inline Michelson interferometer fabricated by a femtosecond laser.

    PubMed

    Yuan, Lei; Wei, Tao; Han, Qun; Wang, Hanzheng; Huang, Jie; Jiang, Lan; Xiao, Hai

    2012-11-01

    A fiber inline Michelson interferometer was fabricated by micromachining a step structure at the tip of a single-mode optical fiber using a femtosecond laser. The step structure splits the fiber core into two reflection paths and produces an interference signal. A fringe visibility of 18 dB was achieved. Temperature sensing up to 1000°C was demonstrated using the fabricated assembly-free device.

  13. Thulium:ZBLAN blue fiber laser pumped by two wavelengths

    NASA Astrophysics Data System (ADS)

    Tohmon, Genji; Sato, Hisanao; Ohya, Jun; Uno, Tomoaki

    1997-05-01

    We demonstrate and analyze an upconversion blue fiber laser pumped by two wavelengths. Lasing at 0.48 m with very low pump threshold power is obtained from a Tm-doped fluorozirconate fiber that is counterpropagating pumped by 1.21- and 0.649- m light. We employed a rate-equation analysis using parameters obtained by fitting to the experimental data to predict the 0.48- m output characteristics as a function of fiber length and output reflectivity.

  14. Thulium:ZBLAN blue fiber laser pumped by two wavelengths.

    PubMed

    Tohmon, G; Sato, H; Ohya, J; Uno, T

    1997-05-20

    We demonstrate and analyze an upconversion blue fiber laser pumped by two wavelengths. Lasing at 0.48 mum with very low pump threshold power is obtained from a Tm-doped fluorozirconate fiber that is counterpropagating pumped by 1.21- and 0.649-mum light. We employed a rate-equation analysis using parameters obtained by fitting to the experimental data to predict the 0.48-mum output characteristics as a function of fiber length and output reflectivity.

  15. Recent development on high-power tandem-pumped fiber laser

    NASA Astrophysics Data System (ADS)

    Zhou, Pu; Xiao, Hu; Leng, Jinyong; Zhang, Hanwei; Xu, Jiangmin; Wu, Jian

    2016-11-01

    High power fiber laser is attracting more and more attention due to its advantage in excellent beam quality, high electricto- optical conversion efficiency and compact system configuration. Power scaling of fiber laser is challenged by the brightness of pump source, nonlinear effect, modal instability and so on. Pumping active fiber by using high-brightness fiber laser instead of common laser diode may be the solution for the brightness limitation. In this paper, we will present the recent development of various kinds of high power fiber laser based on tandem pumping scheme. According to the absorption property of Ytterbium-doped fiber, Thulium-doped fiber and Holmium-doped fiber, we have theoretically studied the fiber lasers that operate at 1018 nm, 1178 nm and 1150 nm, respectively in detail. Consequently, according to the numerical results we have optimized the fiber laser system design, and we have achieved (1) 500 watt level 1018nm Ytterbium-doped fiber laser (2) 100 watt level 1150 nm fiber laser and 100 watt level random fiber laser (3) 30 watt 1178 nm Ytterbium-doped fiber laser, 200 watt-level random fiber laser. All of the above-mentioned are the record power for the corresponded type of fiber laser to the best of our knowledge. By using the high-brightness fiber laser operate at 1018 nm, 1178 nm and 1150 nm that we have developed, we have achieved the following high power fiber laser (1) 3.5 kW 1090 nm Ytterbium-doped fiber amplifier (2) 100 watt level Thulium-doped fiber laser and (3) 50 watt level Holmium -doped fiber laser.

  16. Ceramic bracket debonding with Tm:fiber laser

    NASA Astrophysics Data System (ADS)

    Demirkan, İrem; Sarp, Ayşe Sena Kabaş; Gülsoy, Murat

    2016-06-01

    Lasers have the potential for reducing the required debonding force and can prevent the mechanical damage given to the enamel surface as a result of conventional debonding procedure. However, excessive thermal effects limit the use of lasers for debonding purposes. The aim of this study was to investigate the optimal parameters of 1940-nm Tm:fiber laser for debonding ceramic brackets. Pulling force and intrapulpal temperature measurements were done during laser irradiation simultaneously. A laser beam was delivered in two different modes: scanning the fiber tip on the bracket surface with a Z shape movement or direct application of the fiber tip at one point in the center of the bracket. Results showed that debonding force could be decreased significantly compared to the control samples, in which brackets were debonded by only mechanical force. Intrapulpal temperature was kept equal or under the 5.5°C threshold value of probable thermal damage to pulp. Scanning was found to have no extra contribution to the process. It was concluded that using 1940-nm Tm:fiber laser would facilitate the debonding of ceramic brackets and can be proposed as a promising debonding tool with all the advantageous aspects of fiber lasers.

  17. High-brightness, fiber-coupled pump modules in fiber laser applications

    NASA Astrophysics Data System (ADS)

    Hemenway, Marty; Urbanek, Wolfram; Hoener, Kylan; Kennedy, Keith W.; Bao, Ling; Dawson, David; Cragerud, Emily S.; Balsley, David; Burkholder, Gary; Reynolds, Mitch; Price, Kirk; Haden, Jim; Kanskar, Manoj; Kliner, Dahv A.

    2014-03-01

    High-power, high-brightness, fiber-coupled pump modules enable high-performance industrial fiber lasers with simple system architectures, multi-kW output powers, excellent beam quality, unsurpassed reliability, and low initial and operating costs. We report commercially available (element™), single-emitter-based, 9xx nm pump sources with powers up to 130 W in a 105 μm fiber and 250 W in a 200 μm fiber. This combination of high power and high brightness translates into improved fiber laser performance, e.g., simultaneously achieving high nonlinear thresholds and excellent beam quality at kW power levels. Wavelength-stabilized, 976 nm versions of these pumps are available for applications requiring minimization of the gain-fiber length (e.g., generation of high-peak-power pulses). Recent prototypes have achieved output powers up to 300 W in a 200 μm fiber. Extensive environmental and life testing at both the chip and module level under accelerated and real-world operating conditions have demonstrated extremely high reliability, with innovative designs having eliminated package-induced-failure mechanisms. Finally, we report integrated Pump Modules that provide < 1.6 kW of fiber-coupled power conveniently formatted for fiber-laser pumping or direct-diode applications; these 19" rack-mountable, 2U units combine the outputs of up to 14 elements™ using fused-fiber combiners, and they include high-efficiency diode drivers and safety sensors.

  18. Mid-Infrared Fiber Laser Based on Super-Continuum

    DTIC Science & Technology

    2007-01-31

    the pump wavelength. The gain fiber comprises a.lm of highly doped, large mode area ( LMA ) erbium-doped fiber amplifier (EDFA). Two 1480nm pump laser...amplified stimulation emission. In addition, the LMA EDFA can be incorporated and spliced into the pump laser set-up, and up to several Omni Sciences...Outputnput from 5m Nufern Er/Yb ~2SF ~0mL# gain fiber 71125 pm 6W 976nm pump Figure 4. Detailed lay-out for power amplifier stage using cladding

  19. 25 W Raman-fiber-amplifier-based 589 nm laser for laser guide star.

    PubMed

    Feng, Yan; Taylor, Luke R; Calia, Domenico Bonaccini

    2009-10-12

    We report on a 25 W continuous wave narrow linewidth (< 2.3 MHz) 589 nm laser by efficient (> 95%) coherent beam combination of two narrow linewidth (< 1.5 MHz) Raman fiber amplifiers with a Mach-Zehnder interferometer scheme and frequency doubling in an external resonant cavity with an efficiency of 86%. The results demonstrate the narrow linewidth Raman fiber amplifier technology as a promising solution for developing laser for sodium laser guide star adaptive optics.

  20. All-fiber ring Raman laser generating parabolic pulses

    SciTech Connect

    Kruglov, V. I.; Mechin, D.; Harvey, J. D.

    2010-02-15

    We present theoretical and numerical results for an all-fiber laser using self-similar parabolic pulses ('similaritons') designed to operate using self-similar propagation regimes. The similariton laser features a frequency filter and a Sagnac loop which operate together to generate an integrated all-fiber mode-locked laser. Numerical studies show that this laser generates parabolic pulses with linear chirp in good agreement with analytical predictions. The period for propagating similariton pulses in stable regimes can vary from one to two round trips for different laser parameters. Two-round-trip-period operation in the mode-locked laser appears at bifurcation points for certain cavity parameters. The stability of the similariton regimes has been confirmed by numerical simulations for large numbers of round trips.

  1. High-power disk and fiber lasers: a performance comparison

    NASA Astrophysics Data System (ADS)

    Ruppik, Stefan; Becker, Frank; Grundmann, Frank-Peter; Rath, Wolfram; Hefter, Ulrich

    2012-03-01

    The Performance of High Power Disk Lasers and Fiber Lasers along with their rapid development to the high power cw regime have been of great interest throughout the last decade. Both technologies are still in the focus of several conferences, workshops, and papers and represent the "state-of-the-art" of industrial high power solid state lasers for material processing. As both laser concepts are considered to be the leading 1 μm light-source, this presentation presents an objective and fair comparison of the two different technologies from a manufacturer who pursued both. From the geometry of the active material, through the resonator design, cooling regime, and pumping method to the point of beam quality and power scaling, the different approaches associated with the advantages, challenge and limits of each technology will be discussed. Based on ROFIN's substantial industrial experience with both laser concepts, an outlook into future trends and chances, especially linked to fiber laser, will be given.

  2. Sideband-controllable mode-locking fiber laser based on chirped fiber Bragg gratings.

    PubMed

    Han, Dongdong; Liu, Xueming

    2012-11-19

    We have proposed a sideband-controllable fiber soliton laser by means of chirped fiber Bragg gratings (CFBGs). Each side of the spectral sidebands of laser could be removed by using a CFBG with proper dispersion. Numerical simulations have well reproduced the experimental observations. The numerical and experimental investigations show that the generation of the unilateral sidebands is attributed to the CFBG-induced spectral filtering effect. Our work provides an effective way to manage conventional solitons with spectral sidebands.

  3. Efficiency of Laser Cutting of Carbon Fiber Textiles

    NASA Astrophysics Data System (ADS)

    Fuchs, Alexander N.; Zaeh, Michael F.

    Laser cutting of carbon fiber textiles has various advantages over conventional processes like ultrasonic knife cutting: It is wear free, no fibers are left uncut in the kerf, it is able to cut complex contours, and the cut edge is clearly defined. To ensure a complete cut under variable conditions, e.g. the thickness of the material, line energy has to be applied at a higher level than theoretically necessary to account for those variations. This energy is transilluminated through the kerf. In addition, not all laser energy is absorbed by the fibers but reflected and transmitted within the space between the fibers. Experiments were carried out to measure the percentage of laser power transilluminated through multi-layered carbon fiber textiles during laser cutting with maximum speed. To do so, blocks of poly(methyl methacrylate) (PMMA) were placed underneath the samples and the mass of the sublimed material was measured. Depending on the angle of the fiber, between 9% and 40% of the laser power was transilluminated.

  4. New fiber laser for lidar developments in disaster management

    NASA Astrophysics Data System (ADS)

    Besson, C.; Augere, B.; Canat, G.; Cezard, N.; Dolfi-Bouteyre, A.; Fleury, D.; Goular, D.; Lombard, L.; Planchat, C.; Renard, W.; Valla, M.

    2014-10-01

    Recent progress in fiber technology has enabled new laser designs along with all fiber lidar architectures. Their asset is to avoid free-space optics, sparing lengthy alignment procedures and yielding compact setups that are well adapted for field operations and on board applications thanks to their intrinsic vibration-resistant architectures. We present results in remote sensing for disaster management recently achieved with fiber laser systems. Field trials of a 3-paths lidar vibrometer for the remote study of modal parameters of buildings has shown that application-related constraints were fulfilled and that the obtained results are consistent with simultaneous in situ seismic sensors measurements. Remote multi-gas detection can be obtained using broadband infrared spectroscopy. Results obtained on methane concentration measurement using an infrared supercontinuum fiber laser and analysis in the 3-4 μm band are reported. For gas flux retrieval, air velocity measurement is also required. Long range scanning all-fiber wind lidars are now available thanks to innovative laser architectures. High peak power highly coherent pulses can be extracted from Er3+:Yb3+ and Tm3+ active fibers using methods described in the paper. The additional laser power provides increased coherent lidar capability in range and scanning of large areas but also better system resistance to adverse weather conditions. Wind sensing at ranges beyond 10 km have been achieved and on-going tests of a scanning system dedicated to airport safety is reported.

  5. A 1-Joule laser for a 16-fiber injection system

    SciTech Connect

    Honig, J

    2004-04-06

    A 1-J laser was designed to launch light down 16, multi-mode fibers (400-{micro}m-core dia.). A diffractive-optic splitter was designed in collaboration with Digital Optics Corporation (DOC), and was delivered by DOC. Using this splitter, the energy injected into each fiber varied <1%. The spatial profile out of each fiber was such that there were no ''hot spots,'' a flyer could successfully be launched and a PETN pellet could be initiated. Preliminary designs of the system were driven by system efficiency where a pristine TEM{sub 00} laser beam would be required. The laser is a master oscillator, power amplifier (MOPA) consisting of a 4-mm-dia. Nd:YLF rod in the stable, q-switched oscillator and a 9.5-mm-dia. Nd:YLF rod in the double-passed amplifier. Using a TEM{sub 00} oscillator beam resulted in excellent transmission efficiencies through the fibers at lower energies but proved to be quite unreliable at higher energies, causing premature fiber damage, flyer plate rupture, stimulated Raman scattering (SRS), and stimulated Brillouin scattering (SBS). Upon further investigation, it was found that both temporal and spatial beam formatting of the laser were required to successfully initiate the PETN. Results from the single-mode experiments, including fiber damage, SRS and SBS losses, will be presented. In addition, results showing the improvement that can be obtained by proper laser beam formatting will also be presented.

  6. Mode Selection for a Single-Frequency Fiber Laser

    NASA Technical Reports Server (NTRS)

    Liu, Jian

    2010-01-01

    A superstructured fiber-grating-based mode selection filter for a single-frequency fiber laser eliminates all free-space components, and makes the laser truly all-fiber. A ring cavity provides for stable operations in both frequency and power. There is no alignment or realignment required. After the fibers and components are spliced together and packaged, there is no need for specially trained technicians for operation or maintenance. It can be integrated with other modules, such as telescope systems, without extra optical alignment due to the flexibility of the optical fiber. The filter features a narrow line width of 1 kHz and side mode suppression ratio of 65 dB. It provides a high-quality laser for lidar in terms of coherence length and signal-to-noise ratio, which is 20 dB higher than solid-state or microchip lasers. This concept is useful in material processing, medical equipment, biomedical instrumentation, and optical communications. The pulse-shaping fiber laser can be directly used in space, airborne, and satellite applications including lidar, remote sensing, illuminators, and phase-array antenna systems.

  7. Single-crystal silicon optical fiber by direct laser crystallization

    SciTech Connect

    Ji, Xiaoyu; Lei, Shiming; Yu, Shih -Ying; Cheng, Hiu Yan; Liu, Wenjun; Poilvert, Nicolas; Xiong, Yihuang; Dabo, Ismaila; Mohney, Suzanne E.; Badding, John V.; Gopalan, Venkatraman

    2016-12-05

    Semiconductor core optical fibers with a silica cladding are of great interest in nonlinear photonics and optoelectronics applications. Laser crystallization has been recently demonstrated for crystallizing amorphous silicon fibers into crystalline form. Here we explore the underlying mechanism by which long single-crystal silicon fibers, which are novel platforms for silicon photonics, can be achieved by this process. Using finite element modeling, we construct a laser processing diagram that reveals a parameter space within which single crystals can be grown. Utilizing this diagram, we illustrate the creation of single-crystal silicon core fibers by laser crystallizing amorphous silicon deposited inside silica capillary fibers by high-pressure chemical vapor deposition. The single-crystal fibers, up to 5.1 mm long, have a very welldefined core/cladding interface and a chemically pure silicon core that leads to very low optical losses down to ~0.47-1dB/cm at the standard telecommunication wavelength (1550 nm). Furthermore, tt also exhibits a photosensitivity that is comparable to bulk silicon. Creating such laser processing diagrams can provide a general framework for developing single-crystal fibers in other materials of technological importance.

  8. Single-crystal silicon optical fiber by direct laser crystallization

    DOE PAGES

    Ji, Xiaoyu; Lei, Shiming; Yu, Shih -Ying; ...

    2016-12-05

    Semiconductor core optical fibers with a silica cladding are of great interest in nonlinear photonics and optoelectronics applications. Laser crystallization has been recently demonstrated for crystallizing amorphous silicon fibers into crystalline form. Here we explore the underlying mechanism by which long single-crystal silicon fibers, which are novel platforms for silicon photonics, can be achieved by this process. Using finite element modeling, we construct a laser processing diagram that reveals a parameter space within which single crystals can be grown. Utilizing this diagram, we illustrate the creation of single-crystal silicon core fibers by laser crystallizing amorphous silicon deposited inside silica capillarymore » fibers by high-pressure chemical vapor deposition. The single-crystal fibers, up to 5.1 mm long, have a very welldefined core/cladding interface and a chemically pure silicon core that leads to very low optical losses down to ~0.47-1dB/cm at the standard telecommunication wavelength (1550 nm). Furthermore, tt also exhibits a photosensitivity that is comparable to bulk silicon. Creating such laser processing diagrams can provide a general framework for developing single-crystal fibers in other materials of technological importance.« less

  9. Cascaded combiners for a high power CW fiber laser

    NASA Astrophysics Data System (ADS)

    Tan, Qirui; Ge, Tingwu; Zhang, Xuexia; Wang, Zhiyong

    2016-02-01

    We report cascaded combiners for a high power continuous wave (CW) fiber laser in this paper. The cascaded combiners are fabricated with an improved lateral splicing process. During the fusing process, there is no stress or tension between the pump fiber and the double-cladding fiber. Thus, the parameters of the combiner are better than those that have been reported. The coupling efficiency is 98.5%, and the signal insertion loss is 1%. The coupling efficiency of the cascaded combiners is 97.5%. The pump lights are individually coupled into the double-cladding fiber via five combiners. The thermal effects cannot cause damage to the combiners and the cascaded combiners can operate stably in high power CW fiber lasers. We also develop a high power CW fiber laser that generates a maximum 780 W of CW signal power at 1080 nm with 71% optical-to-optical conversion efficiency. The fiber laser is pumped via five intra-cavity cascaded combiners and five extra-cavity cascaded combiners with a maximum pump power of 1096 W and a pump wavelength of 975 nm.

  10. Mode-locked fiber laser based on chalcogenide microwires.

    PubMed

    Al-Kadry, Alaa; El Amraoui, Mohammed; Messaddeq, Younès; Rochette, Martin

    2015-09-15

    We report the first mode-locked fiber laser using a chalcogenide microwire as the nonlinear medium. The laser is passively mode-locked with nonlinear polarization rotation and can be adjusted for the emission of solitons or noise-like pulses. The use of the microwire leads to a mode-locking threshold at the microwatt level and shortens the cavity length by 4 orders of magnitude with respect to other lasers of its kind. The controlled birefringence of the microwire, combined with a linear polarizer in the cavity, enables multiwavelength laser operation with tunable central wavelength, switchable wavelength separation, and a variable number of laser wavelengths.

  11. Development of ceramic fibers for high-energy laser applications

    NASA Astrophysics Data System (ADS)

    Fair, Geoff E.; Kim, Hyun Jun; Lee, HeeDong; Parthasarathy, Triplicane A.; Keller, Kristin A.; Miller, Zachary D.

    2011-06-01

    Polycrystalline ceramics offer a number of advantages relative to single crystal materials such as lower processing temperatures, improved mechanical properties, and higher doping levels with more uniform distribution of dopants for improved laser performance. Ceramic YAG (Y3Al5O12) and rare earth sesquioxide (RE2O3) fibers promise to enable a number of high power laser devices via high thermal conductivity and higher allowable dopant concentration; however, these materials are not currently available as fine diameter optical-quality fibers. Powder processing approaches for laser quality polycrystalline ceramic fibers are in development at AFRL. Current processing techniques will be reviewed. The effects of a number of processing variables on the resulting fibers as well as preliminary optical characterization will also be presented.

  12. Multiplexed multi-longitudinal mode fiber laser sensor.

    PubMed

    Huang, Long; Wang, Peng; Gao, Liang; Zhang, Tingting; Chen, Xiangfei

    2014-10-20

    A multiplexed multi-longitudinal mode fiber laser sensor system is proposed and demonstrated. By incorporating two matched wavelength division multiplexers (WDMs) and a semiconductor optical amplifier (SOA) into a fiber laser cavity, multiwavelength oscillation is established. Each wavelength corresponding to one channel of WDMs contains multi-longitudinal modes. The multiwavelength output of the laser is directed to another WDM which functions as a demultiplexer. By monitoring the longitudinal mode beat frequency generated at photodetectors following the WDM, the sensing information can be demodulated. Preliminary results for multiplexing two sensors measuring strain and temperature are presented to verify the principle of the system.

  13. Tm:germanate Fiber Laser: Tuning And Q-switching

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Walsh, Brian M.; Reichle, Donald J.; DeYoung, R. J.; Jiang, Shibin

    2007-01-01

    A Tm:germanate fiber laser produced >0.25 mJ/pulse in a 45 ns pulse. It is capable of producing multiple Q-switched pulses from a single p ump pulse. With the addition of a diffraction grating, Tm:germanate f iber lasers produced a wide, but length dependent, tuning range. By s electing the fiber length, the tuning range extends from 1.88 to 2.04 ?m. These traits make Tm:germanate lasers suitable for remote sensin g of water vapor.

  14. Cracks measurement using fiber-phased array laser ultrasound generation

    NASA Astrophysics Data System (ADS)

    Pei, Cuixiang; Demachi, Kazuyuki; Fukuchi, Tetsuo; Koyama, Kazuyoshi; Uesaka, Mitsuru

    2013-04-01

    A phased array laser ultrasound generation system by using fiber optic delivery and a custom-designed focusing objective lens has been developed for crack inspection. The enhancement of crack tip diffraction by using phased array laser ultrasound is simulated with finite element method and validated by experiment. A non-contact and non-destructive measurement of inner-surface cracks by time-of-flight diffraction method using fiber-phased array laser ultrasound generation and electromagnetic acoustic transducer detection has been studied.

  15. Transportation of megawatt millijoule laser pulses via optical fibers?

    NASA Astrophysics Data System (ADS)

    Tauer, Johannes; Kofler, Heinrich; Schwarz, Elisabeth; Wintner, Ernst

    2010-04-01

    Laser ignition is considered to be one of the most promising future concepts for internal combustion engines. It combines the legally required reduction of pollutant emissions and higher engine efficiencies. The igniting plasma is generated by a focused pulsed laser beam. Having pulse durations of a few nanoseconds, the pulse energy E p for reliable ignition amounts to the order of 10 mJ. Different methods of laser ignition with an emphasis on fiber-based systems will be discussed and evaluated.

  16. Multiwavelength L-band fiber laser with bismuth-oxide EDF and photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Ramzia Salem, A. M.; Al-Mansoori, M. H.; Hizam, H.; Mohd Noor, S. B.; Abu Bakar, M. H.; Mahdi, M. A.

    2011-05-01

    A multiwavelength laser comb using a bismuth-based erbium-doped fiber and 50 m photonic crystal fiber is demonstrated in a ring cavity configuration. The fiber laser is solely pumped by a single 1455 nm Raman pump laser to exploit its higher power delivery compared to that of a single-mode laser diode pump. At 264 mW Raman pump power and 1 mW Brillouin pump power, 38 output channels in the L-band have been realized with an optical signal-to-noise ratio above 15 dB and a Stokes line spacing of 0.08 nm. The laser exhibits a tuning range of 12 nm and produces stable Stokes lines across the tuning range between Brillouin pump wavelengths of 1603 nm and 1615 nm.

  17. Frequency noise induced by fiber perturbations in a fiber-linked stabilized laser

    NASA Technical Reports Server (NTRS)

    Pang, YI; Hamilton, Jeffrey J.; Richard, Jean-Paul

    1992-01-01

    The effects of acoustic perturbations on an optical fiber that links a stabilized laser to its reference cavity are studied. An extrapolation indicates that 69 dB of acoustic noise impinging on a 1-m segment of the 10-m fiber contribute frequency noise at the level of 1 Hz/(Hz)1/2 in the 1100-2100-Hz band.

  18. Detachable fiber optic tips for use in thulium fiber laser lithotripsy.

    PubMed

    Hutchens, Thomas C; Blackmon, Richard L; Irby, Pierce B; Fried, Nathaniel M

    2013-03-01

    The thulium fiber laser (TFL) has recently been proposed as an alternative to the Holmium:YAG (Ho:YAG) laser for lithotripsy. The TFL's Gaussian spatial beam profile provides higher power transmission through smaller optical fibers with reduced proximal fiber tip damage, and improved saline irrigation and flexibility through the ureteroscope. However, distal fiber tip damage may still occur during stone fragmentation, resulting in disposal of the entire fiber after the procedure. A novel design for a short, detachable, distal fiber tip that can fit into an ureteroscope's working channel is proposed. A prototype, twist-lock, spring-loaded mechanism was constructed using micromachining methods, mating a 150-μm-core trunk fiber to 300-μm-core fiber tip. Optical transmission measuring 80% was observed using a 30-mJ pulse energy and 500-μs pulse duration. Ex vivo human calcium oxalate monohydrate urinary stones were vaporized at an average rate of 187  μg/s using 20-Hz modulated, 50% duty cycle 5 pulse packets. The highest stone ablation rates corresponded to the highest fiber tip degradation, thus providing motivation for use of detachable and disposable distal fiber tips during lithotripsy. The 1-mm outer-diameter prototype also functioned comparable to previously tested tapered fiber tips.

  19. Plume attenuation of laser radiation during high power fiber laser welding

    NASA Astrophysics Data System (ADS)

    Shcheglov, P. Yu; Uspenskiy, S. A.; Gumenyuk, A. V.; Petrovskiy, V. N.; Rethmeier, M.; Yermachenko, V. M.

    2011-06-01

    The results of an in-situ plume-laser interaction measurement during welding of mild steel with a 5 kW ytterbium fiber laser are reported. A measurement of the attenuation of probe laser beam passing through the plume has allowed to estimate the plume characteristics like the size of the extinction area and the spatial distribution of the extinction coefficient. The power loss of the fiber laser radiation propagating through the whole plume length was calculated. Together with a measured temporal characteristics of extinction the result indicates a significant decreasing of the laser radiation stability, which can lead to the formation of the macroscopic welding defects.

  20. Fiber optics interface for a dye laser oscillator and method

    DOEpatents

    Johnson, S.A.; Seppala, L.G.

    1984-06-13

    A dye laser oscillator in which one light beam is used to pump a continuous stream of dye within a cooperating dye chamber for producing a second, different beam is generally disclosed herein along with a specific arrangement including an optical fiber and a fiber optics interface for directing the pumping beam into the dye chamber. The specific fiber optics interface illustrated includes three cooperating lenses which together image one particular dimension of the pumping beam into the dye chamber from the output end of the optical fiber in order to insure that the dye chamber is properly illuminated by the pumping beam.

  1. Fiber optics interface for a dye laser oscillator and method

    DOEpatents

    Johnson, Steve A.; Seppala, Lynn G.

    1986-01-01

    A dye laser oscillator in which one light beam is used to pump a continuous tream of dye within a cooperating dye chamber for producing a second, different beam is generally disclosed herein along with a specific arrangement including an optical fiber and a fiber optics interface for directing the pumping beam into the dye chamber. The specific fiber optics interface illustrated includes three cooperating lenses which together image one particular dimension of the pumping beam into the dye chamber from the output end of the optical fiber in order to insure that the dye chamber is properly illuminated by the pumping beam.

  2. 954 nm Raman fiber laser with multimode laser diode pumping

    NASA Astrophysics Data System (ADS)

    Zlobina, E. A.; Kablukov, S. I.; Skvortsov, M. I.; Nemov, I. N.; Babin, S. A.

    2016-03-01

    CW Raman fiber laser emitting at 954 nm under direct pumping by a high-power multimode laser diode at 915 nm is demonstrated. A cavity of the laser is formed with 2.5 km-long multimode graded-index fiber and two mirrors: highly reflective fiber Bragg grating (FBG) at one side and normally cleaved fiber end at the other side. The laser generates low-index transverse modes at the Stokes wavelength with output power above 4 W at a slope efficiency above 40%. It is shown that utilization of a narrowband FBG mirror with low reflectivity instead of the cleaved fiber end with Fresnel reflection leads to stronger spectral mode selection, but the generated power is reduced in this case.

  3. Fiber laser as the pulse source for a laser rangefinder system

    NASA Astrophysics Data System (ADS)

    Nissilae, Seppo M.; Kostamovaara, Juha T.

    1993-05-01

    Active fibers, i.e. optically pumped doped fibers, have been developed and studied intensively during the last few years, and an optical amplifier based mainly on erbium-doped fibers has just been launched on the expanding telecommunications market. Fiber lasers have a market of their own in the sensor applications. The use of fiber lasers as pulse sources in laser rangefinder applications is studied here. The main advantages with respect to high energy pulses and a small emitting area are listed, the problems and disadvantages are discussed and some practical solutions to these problems are given. Possible Q-switching techniques for obtaining short, powerful pulses (> 10 W) of about 10 ns are studied as are liquid-crystal, PLZT crystal, acousto-optic and Pockels Cell modulators. Finally, the practicability of these modulators for laser pulsing in industrial environments is discussed.

  4. Incoherent Combining of High-Power Fibers Lasers for Long-Range Directed Energy Applications

    DTIC Science & Technology

    2006-06-27

    Europe meeting IPG Photonics reported [2] CW powers of 2 kW at a wavelength of A = 1.075/.n from a ytterbium fiber laser . The fiber laser operated in a...propagation of the laser beams from the fiber array of Fig. 6 to the target. HELCAP is a 3 -dimensional, fully time-dependent, nonlinear atmospheric...configuration uses recently-developed, multi- kilowatt fiber lasers . These lasers , however, are not suitable for coherent beam combining because of their

  5. Fiber laser hydrogen sensor codified in the time domain

    NASA Astrophysics Data System (ADS)

    Barmenkov, Yuri O.; Ortigosa-Blanch, Arturo; Diez, Antonio; Cruz Munoz, Jose Luis; Andres, Miguel V.

    2004-10-01

    A novel scheme for a fiber optic hydrogen sensor is presented. The sensor is based on an erbium-doped fiber laser with a Pd-coated tapered fiber within the laser cavity acting as the hydrogen-sensing element. When the sensing element is exposed to a hydrogen atmosphere, its attenuation decreases changing the cavity losses, which leads to a modification of the switching-on laser transient. The hydrogen concentration can be obtained by a simple measurement of the build-up time of the laser. This technique translates the measurement of hydrogen concentration into the time domain. Sensing techniques translating the measurement to the time domain offer the possibility to acquire and process the information very easily and accurately using reliable and low-cost electronics. We have also studied the influence of the pumping conditions. We have found that changing from a 100% modulation depth of the pump to biasing the laser with a certain pump power (being this value always below the laser threshold) the sensitivity of the sensor is substantially enhanced. Hence the sensitivity of the fiber laser sensor can be adjusted to certain requirements by simply controlling the pump. Relative build-up times variations of up to 55% for 10% hydrogen concentration are demonstrated.

  6. Quasi mode-locking of coherent feedback random fiber laser

    NASA Astrophysics Data System (ADS)

    Ma, R.; Zhang, W. L.; Zeng, X. P.; Yang, Z. J.; Rao, Y. J.; Yao, B. C.; Yu, C. B.; Wu, Y.; Yu, S. F.

    2016-12-01

    Mode-locking is a milestone in the history of lasers that allows the generation of short light pulses and stabilization of lasers. This phenomenon is known to occur only in standard ordered lasers for long time and until recently it is found that it also occurs in disordered random lasers formed by nanoscale particles. Here, we report the realization of a so-called quasi mode-locking of coherent feedback random fiber laser which consists of a partially disordered linear cavity formed between a point reflector and a random distributed fiber Bragg grating array with an inserted graphene saturable absorber. We show that multi-groups of regular light pulses/sub-pulses with different repetition frequencies are generated within the quasi mode-locking regime through the so-called collective resonances phenomenon in such a random fiber laser. This work may provide a platform to study mode locking as well as pulse dynamic regulation of random lasing emission of coherent feedback disordered structures and pave the way to the development of novel multi-frequency pulse fiber lasers with potentially wide frequency tuning range.

  7. Quasi mode-locking of coherent feedback random fiber laser

    PubMed Central

    Ma, R.; Zhang, W. L.; Zeng, X. P.; Yang, Z. J.; Rao, Y. J.; Yao, B. C.; Yu, C. B.; Wu, Y.; Yu, S. F.

    2016-01-01

    Mode-locking is a milestone in the history of lasers that allows the generation of short light pulses and stabilization of lasers. This phenomenon is known to occur only in standard ordered lasers for long time and until recently it is found that it also occurs in disordered random lasers formed by nanoscale particles. Here, we report the realization of a so-called quasi mode-locking of coherent feedback random fiber laser which consists of a partially disordered linear cavity formed between a point reflector and a random distributed fiber Bragg grating array with an inserted graphene saturable absorber. We show that multi-groups of regular light pulses/sub-pulses with different repetition frequencies are generated within the quasi mode-locking regime through the so-called collective resonances phenomenon in such a random fiber laser. This work may provide a platform to study mode locking as well as pulse dynamic regulation of random lasing emission of coherent feedback disordered structures and pave the way to the development of novel multi-frequency pulse fiber lasers with potentially wide frequency tuning range. PMID:28004785

  8. High efficiency Yb:YAG crystalline fiber-waveguide lasers.

    PubMed

    Mu, Xiaodong; Meissner, Stephanie; Meissner, Helmuth; Yu, Anthony W

    2014-11-01

    A laser diode (LD) cladding pumped single-mode 1030 nm laser has been demonstrated, in an adhesive-free bonded 40 μm core Yb:YAG crystalline fiber waveguide (CFW). A laser output power of 13.2 W at a wavelength of 1.03 μm has been achieved, for an input pump power of 39.5 W. The corresponded laser efficiency is 33.4%. The laser beam quality is confirmed to be near diffraction-limited, with a measured M2 = 1.02. A LD core pumped single-clad Yb:YAG CFW laser has also been demonstrated with a top-hat laser beam profile, with a laser output power of 28 W and a slope efficiency of 78%.

  9. Making custom fiber lasers for use in an atomic physics experiment

    NASA Astrophysics Data System (ADS)

    Khademian, Ali; Cameron, Garnet; Nault, Kyla; Shiner, David

    2016-05-01

    Fiber lasers can be a reasonable choice for a laser source in atomic physics. Our particular applications involve the optical pumping and in some applications cooling of various transitions in atomic helium. Doped fiber with emission at the required wavelengths is necessary. Readily available fiber and approximate wavelength emission ranges include Yb (990 - 1150 nm), Er/Yb (1530 - 1625 nm) and Th (1900 -2100 nm). High efficiency conversion of pump photons into stable single frequency laser emission at the required wavelength is the function of the fiber laser. A simple fiber laser cavity uses a short (~ few mm) fiber grating high reflector mirror, a doped fiber section for the laser cavity, and a long (~ few cm) fiber grating output coupler. To ensure reliable single frequency operation, the laser cavity length should be within 2-3 times the output grating length. However the cavity length must be long enough for round trip gains to compensate for the output mirror transmission loss. Efficiency can be maximized by avoiding fiber splices in the fiber laser cavity. This requires that the gratings be written into the doped fiber directly. In our previous designs, back coupling of the fiber laser into the pump laser contributes to instability and sometimes caused catastrophic pump failure. Current designs use a fiber based wavelength splitter (WDM) to study and circumvent this problem. Data will be presented on the fiber lasers at 1083 nm. Work on a Thulium 2057 nm fiber laser will also be discussed. This work is supported by NSF Grant # 1404498.

  10. Nearly-octave wavelength tuning of a continuous wave fiber laser.

    PubMed

    Zhang, Lei; Jiang, Huawei; Yang, Xuezong; Pan, Weiwei; Cui, Shuzhen; Feng, Yan

    2017-02-15

    The wavelength tunability of conventional fiber lasers are limited by the bandwidth of gain spectrum and the tunability of feedback mechanism. Here a fiber laser which is continuously tunable from 1 to 1.9 μm is reported. It is a random distributed feedback Raman fiber laser, pumped by a tunable Yb doped fiber laser. The ultra-wide wavelength tunability is enabled by the unique property of random distributed feedback Raman fiber laser that both stimulated Raman scattering gain and Rayleigh scattering feedback are available at any wavelength. The dispersion property of the gain fiber is used to control the spectral purity of the laser output.

  11. Nearly-octave wavelength tuning of a continuous wave fiber laser

    PubMed Central

    Zhang, Lei; Jiang, Huawei; Yang, Xuezong; Pan, Weiwei; Cui, Shuzhen; Feng, Yan

    2017-01-01

    The wavelength tunability of conventional fiber lasers are limited by the bandwidth of gain spectrum and the tunability of feedback mechanism. Here a fiber laser which is continuously tunable from 1 to 1.9 μm is reported. It is a random distributed feedback Raman fiber laser, pumped by a tunable Yb doped fiber laser. The ultra-wide wavelength tunability is enabled by the unique property of random distributed feedback Raman fiber laser that both stimulated Raman scattering gain and Rayleigh scattering feedback are available at any wavelength. The dispersion property of the gain fiber is used to control the spectral purity of the laser output. PMID:28198414

  12. High power tandem-pumped thulium-doped fiber laser.

    PubMed

    Wang, Yao; Yang, Jianlong; Huang, Chongyuan; Luo, Yongfeng; Wang, Shiwei; Tang, Yulong; Xu, Jianqiu

    2015-02-09

    We propose a cascaded tandem pumping technique and show its high power and high efficient operation in the 2-μm wavelength region, opening up a new way to scale the output power of the 2-μm fiber laser to new levels (e.g. 10 kW). Using a 1942 nm Tm(3+) fiber laser as the pump source with the co- (counter-) propagating configuration, the 2020 nm Tm(3+) fiber laser generates 34.68 W (35.15W) of output power with 84.4% (86.3%) optical-to-optical efficiency and 91.7% (92.4%) slope efficiency, with respect to launched pump power. It provides the highest slope efficiency reported for 2-μm Tm(3+)-doped fiber lasers, and the highest output power for all-fiber tandem-pumped 2-μm fiber oscillators. This system fulfills the complete structure of the proposed cascaded tandem pumping technique in the 2-μm wavelength region (~1900 nm → ~1940 nm → ~2020 nm). Numerical analysis is also carried out to show the power scaling capability and efficiency of the cascaded tandem pumping technique.

  13. Hybrid lasing in an ultra-long ring fiber laser.

    PubMed

    Rao, Y J; Zhang, W L; Zhu, J M; Yang, Z X; Wang, Z N; Jia, X H

    2012-09-24

    In this paper, we reported the realization of an ultra-long ring fiber laser (RFL) with hybrid emission related to both random lasing and cavity resonance. Compared with a linear random fiber laser (LRFL), the Rayleigh scattering (RS) inducting distributed feedback effect and the cavity inducting resonance effect exist simultaneously in the laser, which reduces the lasing threshold considerably and provides a hybrid way to form random lasing (RL). The laser output can be purely modeless RL when pump power is high enough. It is also discovered that the laser is insensitive to temperature variation and mechanical disturbance, this is unique and quite different from conventional RFLs which are environmentally unstable due to existence of the cavity modes.

  14. Medical Applications Of CO2 Laser Fiber Optics

    NASA Astrophysics Data System (ADS)

    McCord, R. C.

    1981-07-01

    In 1978, Hughes Laboratories reported development of fiber optics that were capable of transmitting CO2 laser energy. These fibers are now being tested for medical applications. Wide ranging medical investigation with CO2 lasers has occurred during the twelve years since the first observations of laser hemostasis. Specialists in ophthalmology, neurosurgery, urology, gynecology, otolaryngology, maxillo-facial/plastic surgery, dermatology, and oncology among others, have explored its use. In principle, all these specialists use CO2 laser radiation at 10.6 microns to thermally destroy diseased tissues. As such, CO2 lasers compare and compete with electrosurgical devices. The fundamental difference between these modalities lies in how they generate heat in treated tissue.

  15. Cavitation bubble dynamics during thulium fiber laser lithotripsy

    NASA Astrophysics Data System (ADS)

    Hardy, Luke A.; Kennedy, Joshua D.; Wilson, Christopher R.; Irby, Pierce B.; Fried, Nathaniel M.

    2016-02-01

    The Thulium fiber laser (TFL) is being explored for lithotripsy. TFL parameters differ from standard Holmium:YAG laser in several ways, including smaller fiber delivery, more strongly absorbed wavelength, low pulse energy/high pulse rate operation, and more uniform temporal pulse structure. High speed imaging of cavitation bubbles was performed at 105,000 fps and 10 μm spatial resolution to determine influence of these laser parameters on bubble formation. TFL was operated at 1908 nm with pulse energies of 5-75 mJ, and pulse durations of 200-1000 μs, delivered through 100-μm-core fiber. Cavitation bubble dynamics using Holmium laser at 2100 nm with pulse energies of 200-1000 mJ and pulse duration of 350 μs was studied, for comparison. A single, 500 μs TFL pulse produced a bubble stream extending 1090 +/- 110 μm from fiber tip, and maximum bubble diameters averaged 590 +/- 20 μm (n=4). These observations are consistent with previous studies which reported TFL ablation stallout at working distances < 1.0 mm. TFL bubble dimensions were five times smaller than for Holmium laser due to lower pulse energy, higher water absorption coefficient, and smaller fiber diameter used.

  16. Laser heating of metallic nanoparticles for photothermal ablation applications

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoming; Shan, Guangshuai; Yu, Junsheng; Yang, Wei; Ren, Zhaodi; Wang, Xiaohui; Xie, Xi; Chen, Hui-jiuan; Chen, Xiaodong

    2017-02-01

    In order to search for a suitable frequency and material with higher photothermal efficacy for hyperthermia application in cancer treatment, a comparative study on laser heating of Au/Ag nanoparticles and Ag nanowires has been conducted. It is found that gold nanoparticles are more photothermal efficient in comparison with silver nanoparticles and silver nanowires at 450nm and 532 nm. Gold nanoparticles are more heated by 532 nm laser than 450 nm laser. In contrast, silver nanoparticles show slightly less temperature rise at 532 nm than 450 nm laser. For silver nanowires, no significant photothermal effect has been observed. Size-dependent effect study indicates that the absorption efficiency of single gold nanoparticles of larger diameter is higher than that of smaller diameter, in the diameter range of 0-50nm. A mathematical model for describing the heating profile in the heating sample has been built. The mathematical model can be utilized to predict the optimal treatment size of tumor.

  17. Tunable Fiber Bragg Grating Ring Lasers using Macro Fiber Composite Actuators

    NASA Technical Reports Server (NTRS)

    Geddis, Demetris L.; Allison, Sidney G.; Shams, Qamar A.

    2006-01-01

    The research reported herein includes the fabrication of a tunable optical fiber Bragg grating (FBG) fiber ring laser (FRL)1 from commercially available components as a high-speed alternative tunable laser source for NASA Langley s optical frequency domain reflectometer (OFDR) interrogator, which reads low reflectivity FBG sensors. A Macro-Fiber Composite (MFC) actuator invented at NASA Langley Research Center (LaRC) was selected to tune the laser. MFC actuators use a piezoelectric sheet cut into uniaxially aligned rectangular piezo-fibers surrounded by a polymer matrix and incorporate interdigitated electrodes to deliver electric fields along the length of the piezo-fibers. This configuration enables MFC actuators to produce displacements larger than the original uncut piezoelectric sheet. The FBG filter was sandwiched between two MFC actuators, and when strained, produced approximately 3.62 nm of wavelength shift in the FRL when biasing the MFC actuators from 500 V to 2000 V. This tunability range is comparable to that of other tunable lasers and is adequate for interrogating FBG sensors using OFDR technology. Three different FRL configurations were studied. Configuration A examined the importance of erbium-doped fiber length and output coupling. Configuration B demonstrated the importance of the FBG filter. Configuration C added an output coupler to increase the output power and to isolate the filter. Only configuration C was tuned because it offered the best optical power output of the three configurations. Use of Plastic Optical Fiber (POF) FBG s holds promise for enhanced tunability in future research.

  18. Laser-jamming effectiveness analysis of combined-fiber lasers for airborne defense systems.

    PubMed

    Jie, Xu; Shanghong, Zhao; Rui, Hou; Shengbao, Zhan; Lei, Shi; Jili, Wu; Shaoqiang, Fang; Yongjun, Li

    2008-12-20

    The laser-jamming effectiveness of combined fiber lasers for airborne defense systems is analyzed in detail. Our preliminary experimental results are proof of the concept of getting a high-power laser through a beam combination technique. Based on combined fiber lasers, the jamming effectiveness of four-quadrant guidance and imaging guidance systems are evaluated. The simulation results have proved that for a four-quadrant guidance system, the tracking system takes only two seconds to complete tracking, and the new tracking target is the jamming laser; for the imaging guidance system, increasing the power of the jamming laser or the distance between the target and the jamming laser are both efficient ways to achieve a successful laser jamming.

  19. Innovative laser based approaches to laryngeal cancer: what an engineer and physicist need to know

    NASA Astrophysics Data System (ADS)

    Burns, James A.

    2008-02-01

    Innovative laser-based approaches to laryngeal cancer include the clinical applications of two new technologies, photoangiolysis using a 532nm wavelength pulsed-KTP laser and fiber-based cutting using a 2μm wavelength thulium laser. Photoangiolysis is well-suited for treatment of minimally invasive glottic cancer and allows maximum preservation of phonatory surfaces needed for optimal voicing. The thulium laser offers an alternative to the carbon dioxide laser as an endolaryngeal cutting tool due to its enhanced hemostatic properties and fiber-based delivery. Clinical examples of pulsed-KTP laser involution of early glottic cancer will be presented in order to highlight the concept of targeting tumor angiogenesis in treating laryngeal cancer. The surgical experience using the thulium laser for complex endoscopic endolaryngeal excisions of large laryngeal cancers is presented to demonstrate the expanded clinical applications of endolaryngeal cutting offered by this laser. The laryngeal tissue effects of various laser power and pulse width (PW) settings, mode of delivery, active cooling to reduce thermal trauma, and wavelength selection have been extensively studied for the KTP and thulium lasers in both ex-vivo and live-perfusing models. The results from these studies, included herein, determine the clinical efficacy and safety of these innovative laser-based approaches to laryngeal cancer.

  20. Dual frequency comb metrology with one fiber laser

    NASA Astrophysics Data System (ADS)

    Zhao, Xin; Takeshi, Yasui; Zheng, Zheng

    2016-11-01

    Optical metrology techniques based on dual optical frequency combs have emerged as a hotly studied area targeting a wide range of applications from optical spectroscopy to microwave and terahertz frequency measurement. Generating two sets of high-quality comb lines with slightly different comb-tooth spacings with high mutual coherence and stability is the key to most of the dual-comb schemes. The complexity and costs of such laser sources and the associated control systems to lock the two frequency combs hinder the wider adoption of such techniques. Here we demonstrate a very simple and rather different approach to tackle such a challenge. By employing novel laser cavity designs in a mode-locked fiber laser, a simple fiber laser setup could emit dual-comb pulse output with high stability and good coherence between the pulse trains. Based on such lasers, comb-tooth-resolved dual-comb optical spectroscopy is demonstrated. Picometer spectral resolving capability could be realized with a fiber-optic setup and a low-cost data acquisition system and standard algorithms. Besides, the frequency of microwave signals over a large range can be determined based on a simple setup. Our results show the capability of such single-fiber-laser-based dual-comb scheme to reduce the complexity and cost of dual-comb systems with excellent quality for different dual-comb applications.

  1. A phase-stabilized carbon nanotube fiber laser frequency comb.

    PubMed

    Lim, Jinkang; Knabe, Kevin; Tillman, Karl A; Neely, William; Wang, Yishan; Amezcua-Correa, Rodrigo; Couny, François; Light, Philip S; Benabid, Fetah; Knight, Jonathan C; Corwin, Kristan L; Nicholson, Jeffrey W; Washburn, Brian R

    2009-08-03

    A frequency comb generated by a 167 MHz repetition frequency erbium-doped fiber ring laser using a carbon nanotube saturable absorber is phase-stabilized for the first time. Measurements of the in-loop phase noise show an integrated phase error on the carrier envelope offset frequency of 0.35 radians. The carbon nanotube fiber laser comb is compared with a CW laser near 1533 nm stabilized to the nu(1) + nu(3) overtone transition in an acetylene-filled kagome photonic crystal fiber reference, while the CW laser is simultaneously compared to another frequency comb based on a Cr:Forsterite laser. These measurements demonstrate that the stability of a GPS-disciplined Rb clock is transferred to the comb, resulting in an upper limit on the locked comb's frequency instability of 1.2 x 10(-11) in 1 s, and a relative instability of <3 x 10(-12) in 1 s. The carbon nanotube laser frequency comb offers much promise as a robust and inexpensive all-fiber frequency comb with potential for scaling to higher repetition frequencies.

  2. Double nanosecond pulses generation in ytterbium fiber laser

    NASA Astrophysics Data System (ADS)

    Veiko, V. P.; Lednev, V. N.; Pershin, S. M.; Samokhvalov, A. A.; Yakovlev, E. B.; Zhitenev, I. Yu.; Kliushin, A. N.

    2016-06-01

    Double pulse generation mode for nanosecond ytterbium fiber laser was developed. Two sequential 60-200 ns laser pulses with variable delay between them were generated by acousto-optic modulator opening with continuous diode pumping. A custom radio frequency generator was developed to produce two sequential "opening" radio pulses with a delay of 0.2-1 μs. It was demonstrated that double pulse generation did not decrease the average laser power while providing the control over the laser pulse power profile. Surprisingly, a greater peak power in the double pulse mode was observed for the second laser pulse. Laser crater studies and plasma emission measurements revealed an improved efficiency of laser ablation in the double pulse mode.

  3. Nd-doped phosphate glass microstructured optical fiber laser

    NASA Astrophysics Data System (ADS)

    Zhang, G.; Luo, F. F.; Liu, X. F.; Dong, G. P.; Zhang, Q.; Lin, G.; Zhou, Q. L.; Qiu, J. R.; Hu, L. L.; Chen, D. P.

    2010-06-01

    We experimentally demonstrated a single-mode laser at 1056 nm with Nd-doped phosphate glass microstructured optical fiber (MOF), which was fabricated with conventional stack-and-draw method. The laser action was observed from a Fabry-Perot cavity formed by placing two dichroic mirrors of ˜100 and 85% reflectivity, to the two end facets of MOF. Pumped by CW laser diodes (LDs) at 808 nm, the MOF laser yielded a maximum output power of 8.5 mW and a slope efficiency of 2%.

  4. Long-term laser frequency stabilization using fiber interferometers

    SciTech Connect

    Kong, Jia; Lucivero, Vito Giovanni; Jiménez-Martínez, Ricardo; Mitchell, Morgan W.

    2015-07-15

    We report long-term laser frequency stabilization using only the target laser and a pair of 5 m fiber interferometers, one as a frequency reference and the second as a sensitive thermometer to stabilize the frequency reference. When used to stabilize a distributed feedback laser at 795 nm, the frequency Allan deviation at 1000 s drops from 5.6 × 10{sup −8} to 6.9 × 10{sup −10}. The performance equals that of an offset lock employing a second, atom-stabilized laser in the temperature control.

  5. Innovative fiber systems for laser medicine and technology

    NASA Astrophysics Data System (ADS)

    Artiouchenko, Viatcheslav G.; Wojciechowski, Cezar

    2003-10-01

    Development of Polycrystalline Infrared (PIR-) fibers extruded from solid solutions of AgCl/AgBr has opened a new horizon of molecular spectroscopy applications in 4-18 micron range of spectra. PIR-fiber cables and probes could be coupled with a variety of Fourier Transform Infrared (FTIR) spectrometer and Tunable Diode Lasers (TDL), including pig tailing of Mercury Cadmium Tellurium (MCT) detectors. Using these techniques no sample preparation is necessary for PIR-fiber probes have been used to measure reflection and absorption spectra, in situ, in vivo, in real time and even multiplexed. Such PIR-fiber probes have been used for evanescent absorption spectroscopy of malignant tissue and skin surface diagnostics in-vivo, glucose detection in blood as well as crude oil composition analysis, for organic pollution and nuclear waste monitoring. A review of various PIR-fiber applications in medicine, industry and environment control is presented. The synergy of PIR-fibers flexibility with a super high spectral resolution of TDL spectrometers with Δv=10-4cm-1, provides the unique tool for gas analysis, specifically wiht PIR-fibers are coupled as pigtails with MCT-detectors and Pb-salt lasers. Design of multichannel PIR-fiber tailed TDL spectrometer could be used as a portable device for multispectral gas analysis as 1 ppb level of detectivity for various applications in medicine and biotechnology.

  6. Innovative fiber systems for laser medicine and technology

    NASA Astrophysics Data System (ADS)

    Artiouchenko, Viatcheslav G.; Wojciechowski, Cezar

    2004-09-01

    Development of Polycrystalline Infrared (PIR-) fibers extruded from solid solutions of AgCl/AgBr has opened a new horizon of molecular spectroscopy applications in 4 - 18 micron range of spectra. PIR-fiber cables and probes could be coupled with a variety of Fourier Transform Infrared (FTIR) spectrometer and Tunable Diode Lasers (TDL), including pig tailing of Mercury Cadmium Tellurium (MCT) detectors. Using these techniques no sample preparation is necessary for PIR-fiber probes to measure reflection and absorption spectra, in situ, in vivo, in real time and even multiplexed. Such PIR-fiber probes have been used for evanescent absorption spectroscopy of malignant tissue and skin surface diagnostics in-vivo, glucose detection in blood as well as crude oil composition analysis, for organic pollution and nuclear waste monitoring. A review of various PIR-fiber applications in medicine, industry and environment control is presented. The synergy of PIR-fibers flexibility with a super high spectral resolution of TDL spectrometers with Δν=10-4cm-1, provides the unique tool for gas analysis, specifically when PIR-fibers are coupled as pigtails with MCT-detectors and Pb-salt lasers. Design of multichannel PIR-fiber tailed TDL spectrometer could be used as a portable device for multispectral gas analysis at 1 ppb level of detectivity for various applications in medicine and biotechnology.

  7. 157 W all-fiber high-power picosecond laser.

    PubMed

    Song, Rui; Hou, Jing; Chen, Shengping; Yang, Weiqiang; Lu, Qisheng

    2012-05-01

    An all-fiber high-power picosecond laser is constructed in a master oscillator power amplifier configuration. The self-constructed fiber laser seed is passively mode locked by a semiconductor saturable absorber mirror. Average output power of 157 W is obtained after three stages of amplification at a fundamental repetition rate of 60 MHz. A short length of ytterbium double-clad fiber with a high doping level is used to suppress nonlinear effects. However, a stimulated Raman scattering (SRS) effect occurs owing to the 78 kW high peak power. A self-made all-fiber repetition rate increasing system is used to octuple the repetition rate and decrease the high peak power. Average output power of 156.6 W is obtained without SRS under the same pump power at a 480 MHz repetition rate with 0.6 nm line width.

  8. Clad Nd:YAG fibers for laser applications

    SciTech Connect

    Digonnet, M.J.F.; Shaw, H.J.; Gaeta, C.J.; O'meara, D.

    1987-05-01

    The implementation of an extrusion method to clad Nd:YAG single crystal fibers with index-matched glasses (Delta-n = 0.048) is reported. A propagation-loss coefficient of 0.08 dB/cm was measured for the fundamental mode of a 41-micron-diameter glass-clad fiber laser, an improvement of about one order of magnitude over unclad fibers. Guided clad fiber lasers operated at 1.064 microns with thresholds as low as 0.3-0.5 mW and up to 65-mW CW output power are also reported. The origins of and means of reducing the residual loss are discussed. 14 references.

  9. Subhertz linewidth laser by locking to a fiber delay line.

    PubMed

    Dong, Jing; Hu, Yongqi; Huang, Junchao; Ye, Meifeng; Qu, Qiuzhi; Li, Tang; Liu, Liang

    2015-02-10

    An ultralow-noise, subhertz 1.55 μm erbium-doped fiber laser that is locked on an all-fiber-based Michelson interferometer is presented in this paper. The interferometer uses 500 m SMF-28 optical fiber and an acousto-optic modulator to allow heterodyne detection. By comparing two identical laser systems, a 0.67 (0.21) Hz linewidth beat-note signal is achieved and we obtain fractional frequency instability of 7×10(-15) at short timescales (0.1-1 s). The frequency noise power spectral density of two identical lasers is below -1  dB Hz(2)/Hz at 1 Hz and it reaches -18  dB Hz(2)/Hz from 200 Hz to 1 kHz.

  10. Rare Earth Doped IR Fiber Lasers For Medical Applications

    NASA Astrophysics Data System (ADS)

    Esterowitz, Leon; Allen, Roger

    1989-06-01

    Trivalent rare earth doped lasers in fluorozirconate glasses and fibers that lase between 2 and 3 μm are reviewed. There have been a large number of laser-fiber optic systems below 2pm developed for clinical microsurgery at a variety of sites. The required flexibility of the fiber optic waveguide varies with the clinical use, such as: intraocular (through a small diameter rigid tube), endoscopically accessible pulmonary and gastric mucosa (through a port of a fiber-optic endoscope of intermediate flexibility), and intra-arterial (as an integral part of a flexible catheter, which in the case of the coronaries must be very flexible so as to negotiate abrupt bends and bifurcations without damage to the vessels). Laser energy absorbed by tissue is capable of coagulation of tissue (denaturation of structural proteins), melting of fatty deposits or other structures (solid or gel to liquid phase transitions), as well as direct breakage of chemical bonds by high energy photons. It is of general interest to develop a pulsed laser system transmitted through flexible fiber optics that is capable of precise ablation of targeted tissue with minimal damage to the remaining tissue. Ideally, the device should be able to ablate any tissue because of the general absorptive properties of tissue, and not a specific chromophore such as melanin or hemoglobin, the concentration of which varies widely among tissues. Two obvious ubiquitous chromophores have been widely discussed: 1) proteins and nucleic acids whose high concentration and absorption coefficients lead to strong tissue absorption in the ultraviolet and 2) water whose strong infrared absorption bands have been widely utilized in CO2 laser surgery. Non-linear absorption occurring at very high power densities (~1 GW/cm2) has been shown to be very effective for non-invasive ocular (an optically transparent field) microsurgery at the image plane of a slit lamp, but this approach appears impractical in fiber optic systems because

  11. An integrated fiber and stone basket device for use in Thulium fiber laser lithotripsy

    NASA Astrophysics Data System (ADS)

    Wilson, Christopher R.; Hutchens, Thomas C.; Hardy, Luke A.; Irby, Pierce B.; Fried, Nathaniel M.

    2014-03-01

    The Thulium fiber laser (TFL) is being explored as an alternative laser lithotripter to the Holmium:YAG laser. The TFL's superior near-single mode beam profile enables higher power transmission through smaller fibers with reduced proximal fiber tip damage. Recent studies have also reported that attaching hollow steel tubing to the distal fiber tip decreases fiber degradation and burn-back without compromising stone ablation rates. However, significant stone retropulsion was observed, which increased with pulse rate. In this study, the hollow steel tip fiber design was integrated with a stone basket to minimize stone retropulsion during ablation. A device was constructed consisting of a 100-μm-core, 140-μm-OD silica fiber outfitted with 5-mm-long stainless steel tubing at the distal tip, and integrated with a 1.3-Fr (0.433-mm-OD) disposable nitinol wire basket, to form an overall 1.9-Fr (0.633-mm- OD) integrated device. This compact design may provide several potential advantages including increased flexibility, higher saline irrigation rates through the ureteroscope working channel, and reduced fiber tip degradation compared to separate fiber and stone basket manipulation. TFL pulse energy of 31.5 mJ with 500 μs pulse duration and pulse rate of 500 Hz was delivered through the integrated fiber/basket device in contact with human uric acid stones, ex vivo. TFL stone ablation rates measured 1.5 +/- 0.2 mg/s, comparable to 1.7 +/- 0.3 mg/s (P > 0.05) using standard bare fiber tips separately with a stone basket. With further development, this device may be useful for minimizing stone retropulsion, thus enabling more efficient TFL lithotripsy at higher pulse rates.

  12. Stable two-wavelength lasers by use of a double alpha-type fiber cavity with fiber grating mirrors

    NASA Astrophysics Data System (ADS)

    Kim, Ho-Young; Oh, Myoung-Suk; Nam, Eun-Soo; Cho, Kyoung-Ik

    2005-12-01

    For high-frequency (20-200 GHz) modulated light sources, we developed and investigated two-wavelength lasers using the double alpha-type fiber cavities with fiber grating mirrors. For variations of polarization states and pump powers, parallel alpha-type coupled cavity lasers were found to be more stable than serial lasers.

  13. Power optimization of random distributed feedback fiber lasers.

    PubMed

    Vatnik, Ilya D; Churkin, Dmitry V; Babin, Sergey A

    2012-12-17

    We present a comprehensive study of power output characteristics of random distributed feedback Raman fiber lasers. The calculated optimal slope efficiency of the backward wave generation in the one-arm configuration is shown to be as high as ~90% for 1 W threshold. Nevertheless, in real applications a presence of a small reflection at fiber ends can appreciably deteriorate the power performance. The developed numerical model well describes the experimental data.

  14. Compact low-cost detector for in vivo assessment of microphytobenthos using laser induced fluorescence

    NASA Astrophysics Data System (ADS)

    Utkin, A. B.; Vieira, S.; Marques da Silva, J.; Lavrov, A.; Leite, E.; Cartaxana, P.

    2013-03-01

    The development of a compact low-cost detector for non-destructive assessment of microphytobenthos using laser induced fluorescence was described. The detector was built from a specially modified commercial miniature fiber optic spectrometer (Ocean Optics USB4000). Its usefulness is experimentally verified by the study of diatom-dominated biofilms inhabiting the upper layers of intertidal sediments of the Tagus Estuary, Portugal. It is demonstrated that, operating with a laser emitter producing 30 mJ pulses at the wavelength of 532 nm, the detector is capable to record fluorescence signals with sufficient intensity for the quantitative biomass characterization of the motile epipelic microphytobenthic communities and to monitor their migratory activity. This paves the way for building an entire emitter-detector LIF system for microphytobenthos monitoring, which will enable microalgae communities occupying hardly accessible intertidal flats to be monitored in vivo at affordable cost.

  15. Solid-state laser source of narrowband ultraviolet B light for skin disease care

    NASA Astrophysics Data System (ADS)

    Tarasov, Aleksandr A.; Chu, Hong

    2013-03-01

    We report about the development of all-solid-state laser source of narrowband UV-B light for medical applications. The device is based on a gain-switched Ti: Sapphire laser with volume Bragg grating, pumped at 532 nm and operating at 931.8 nm, followed by a third harmonic generator and a fiber optic beam homogenizer. The maximum available pulse energy exceeded 5 mJ at 310.6 nm, with a pulse repetition rates of 50 Hz. The output characteristics satisfy the medical requirements for psoriasis and vitiligo treatment. A new optical scheme for third harmonic generation enhancement at moderate levels of input intensities is proposed and investigated. As a result, 40% harmonic efficiency was obtained, when input pulse power was only 300 kW.

  16. Comparative study on laser tissue ablation between PV and HPS lasers

    NASA Astrophysics Data System (ADS)

    Kang, Hyun Wook; Jebens, David; Mitchell, Gerald; Koullick, Ed

    2008-02-01

    Laser therapy for obstructive benign prostatic hyperplasia (BPH) has gained broad adoption due to effective tissue removal, immediate hemostasis, and minor complications. The aim of this study is to quantitatively compare ablation characteristics of PV (Photoselective Vaporization) and the newly introduced HPS (High Performance System) 532 nm lasers. Bovine prostatic tissues were ablated in vitro, using a custom-made scanning system. Laser-induced volume produced by two lasers was quantified as a function of applied power, fiber working distance (WD), and treatment speed. Given the same power of 80 W and speed of 4 mm/s, HPS created up to 50 % higher tissue ablation volume than PV did. PV induced a rapid decrease of ablation volume when WD increased from 0.5 mm to 3 mm while HPS yielded almost constant tissue removal up to 3 mm for both 80 W and 120 W. As the treatment speed increased, both lasers reached saturation in tissue ablation volume. Lastly, both PV and HPS lasers exhibited approximately 1 mm thick heat affected zone (HAZ) in this study although HPS created twice deeper ablation channels with a depth of up to 4 mm. Due to a smaller beam size and a higher output power, HPS maximized tissue ablation rate with minimal thermal effects to the adjacent tissue. Furthermore, more collimated beam characteristics provides more spatial flexibility and may even help to decrease the rate of fiber degradation associated with thermal damage from debris reattachment to the tip.

  17. Fiber-Laser-Based Ultrasound Sensor for Photoacoustic Imaging

    NASA Astrophysics Data System (ADS)

    Liang, Yizhi; Jin, Long; Wang, Lidai; Bai, Xue; Cheng, Linghao; Guan, Bai-Ou

    2017-01-01

    Photoacoustic imaging, especially for intravascular and endoscopic applications, requires ultrasound probes with miniature size and high sensitivity. In this paper, we present a new photoacoustic sensor based on a small-sized fiber laser. Incident ultrasound waves exert pressures on the optical fiber laser and induce harmonic vibrations of the fiber, which is detected by the frequency shift of the beating signal between the two orthogonal polarization modes in the fiber laser. This ultrasound sensor presents a noise-equivalent pressure of 40 Pa over a 50-MHz bandwidth. We demonstrate this new ultrasound sensor on an optical-resolution photoacoustic microscope. The axial and lateral resolutions are 48 μm and 3.3 μm. The field of view is up to 1.57 mm2. The sensor exhibits strong resistance to environmental perturbations, such as temperature changes, due to common-mode cancellation between the two orthogonal modes. The present fiber laser ultrasound sensor offers a new tool for all-optical photoacoustic imaging.

  18. Fiber-Laser-Based Ultrasound Sensor for Photoacoustic Imaging

    PubMed Central

    Liang, Yizhi; Jin, Long; Wang, Lidai; Bai, Xue; Cheng, Linghao; Guan, Bai-Ou

    2017-01-01

    Photoacoustic imaging, especially for intravascular and endoscopic applications, requires ultrasound probes with miniature size and high sensitivity. In this paper, we present a new photoacoustic sensor based on a small-sized fiber laser. Incident ultrasound waves exert pressures on the optical fiber laser and induce harmonic vibrations of the fiber, which is detected by the frequency shift of the beating signal between the two orthogonal polarization modes in the fiber laser. This ultrasound sensor presents a noise-equivalent pressure of 40 Pa over a 50-MHz bandwidth. We demonstrate this new ultrasound sensor on an optical-resolution photoacoustic microscope. The axial and lateral resolutions are 48 μm and 3.3 μm. The field of view is up to 1.57 mm2. The sensor exhibits strong resistance to environmental perturbations, such as temperature changes, due to common-mode cancellation between the two orthogonal modes. The present fiber laser ultrasound sensor offers a new tool for all-optical photoacoustic imaging. PMID:28098201

  19. Parabolic similariton Yb-fiber laser with triangular pulse evolution

    NASA Astrophysics Data System (ADS)

    Wang, Sijia; Wang, Lei

    2016-04-01

    We propose a novel mode-locked fiber laser design which features a passive nonlinear triangular pulse formation and self-similar parabolic pulse amplification intra cavity. Attribute to the nonlinear reshaping progress in the passive fiber, a triangular-profiled pulse with negative-chirp is generated and paved the way for rapid and efficient self-similar parabolic evolution in a following short-length high-gain fiber. In the meanwhile, the accompanied significantly compressed narrow spectrum from this passive nonlinear reshaping also gives the promise of pulse stabilization and gain-shaping robustness without strong filtering. The resulting short average intra-cavity pulse duration, low amplified spontaneous emission (ASE) and low intra-cavity power loss are essential for the low-noise operation. Simulations predict this modelocked fiber laser allows for high-energy ultra-short transform-limited pulse generation exceeding the gain bandwidth. The output pulse has a de-chirped duration (full-width at half maximum, FWHM) of 27 fs. In addition to the ultrafast laser applications, the proposed fiber laser scheme can support low-noise parabolic and triangular pulse trains at the same time, which are also attractive in optical pulse shaping, all-optical signal processing and high-speed communication applications.

  20. Laser heated pedestal growth system commissioning and fiber processing

    NASA Astrophysics Data System (ADS)

    Buric, Michael; Yip, M. J.; Chorpening, Ben; Ohodnicki, Paul

    2016-05-01

    A new Laser Heated Pedestal Growth system was designed and fabricated using various aspects of effective legacy designs for the growth of single-crystal high-temperature-compatible optical fibers. The system is heated by a 100-watt, DC driven, CO2 laser with PID power control. Fiber diameter measurements are performed using a telecentric video system which identifies the molten zone and utilizes edge detection algorithms to report fiber-diameter. Beam shaping components include a beam telescope; along with gold-coated reflaxicon, turning, and parabolic focusing mirrors consistent with similar previous systems. The optical system permits melting of sapphire-feedstock up to 1.5mm in diameter for growth. Details regarding operational characteristics are reviewed and properties of single-crystal sapphire fibers produced by the system are evaluated. Aspects of the control algorithm efficacy will be discussed, along with relevant alternatives. Finally, some new techniques for in-situ processing making use of the laser-heating system are discussed. Ex-situ fiber modification and processing are also examined for improvements in fiber properties.

  1. Fiber optic coherent laser radar 3d vision system

    SciTech Connect

    Sebastian, R.L.; Clark, R.B.; Simonson, D.L.

    1994-12-31

    Recent advances in fiber optic component technology and digital processing components have enabled the development of a new 3D vision system based upon a fiber optic FMCW coherent laser radar. The approach includes a compact scanner with no moving parts capable of randomly addressing all pixels. The system maintains the immunity to lighting and surface shading conditions which is characteristic of coherent laser radar. The random pixel addressability allows concentration of scanning and processing on the active areas of a scene, as is done by the human eye-brain system.

  2. Laser to single-mode-fiber coupling: A laboratory guide

    NASA Astrophysics Data System (ADS)

    Ladany, I.

    1992-07-01

    All the information necessary to achieve reasonably efficient coupling of semiconductor lasers to single mode fibers is collected from the literature, reworked when necessary, and presented in a mostly tabular form. Formulas for determining the laser waist radius and the fiber mode radius are given. Imaging relations connecting these values with the object and image distances are given for three types of lenses: ball, hemisphere, and Gradient Index (GRIN). Sources for these lenses are indicated, and a brief discussion is given about ways of reducing feedback effects.

  3. Fast Fiber-Laser Alignment: Beam Spot-Size Method

    NASA Astrophysics Data System (ADS)

    Zhang, Rong; Guo, Jingyan; Shi, Frank G.

    2005-03-01

    A novel fast and cost-effective method is introduced for the active alignment of a fiber to a laser diode: only four easy laser beam spot-size measurements are required for moving the fiber tip from the far field to the proximity of the optimal alignment position, thus dramatically reducing the total alignment time (at least five times faster than a conventional method),as experimentally confirmed. Moreover, in contrast to the existing methods,the new method is failure-proof. The principle of the proposed method can be applied generally to any type of packages and is illustrated by an example of a butterfly package.

  4. Theoretical analysis of spectrum flattening in fiber laser oscillator

    NASA Astrophysics Data System (ADS)

    Shi, Chen; Wang, Xiaolin; Zhou, Pu; Wang, Zefeng; Xu, Xiaojun; Lu, Qisheng

    2017-01-01

    The flatness of laser spectrum is important in many applications. In this manuscript, a method of acquiring flattened spectrum directly from a fiber oscillator by optimizing the reflective spectrum of Fiber Bragg Gratings (FBG) was demonstrated and optimized result at wavelength around 1064 nm and 1080 nm was presented. An optimization path to alter the reflectivity of FBGs using greedy algorithm was interpreted by analyzing the single-trip gain inside the resonant cavity. Our method has a guiding significance of controlling the output spectrum of laser oscillator using FBGs.

  5. A novel fiber laser development for photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Yavas, Seydi; Aytac-Kipergil, Esra; Arabul, Mustafa U.; Erkol, Hakan; Akcaalan, Onder; Eldeniz, Y. Burak; Ilday, F. Omer; Unlu, Mehmet B.

    2013-03-01

    Photoacoustic microscopy, as an imaging modality, has shown promising results in imaging angiogenesis and cutaneous malignancies like melanoma, revealing systemic diseases including diabetes, hypertension, tracing drug efficiency and assessment of therapy, monitoring healing processes such as wound cicatrization, brain imaging and mapping. Clinically, photoacoustic microscopy is emerging as a capable diagnostic tool. Parameters of lasers used in photoacoustic microscopy, particularly, pulse duration, energy, pulse repetition frequency, and pulse-to-pulse stability affect signal amplitude and quality, data acquisition speed and indirectly, spatial resolution. Lasers used in photoacoustic microscopy are typically Q-switched lasers, low-power laser diodes, and recently, fiber lasers. Significantly, the key parameters cannot be adjusted independently of each other, whereas microvasculature and cellular imaging, e.g., have different requirements. Here, we report an integrated fiber laser system producing nanosecond pulses, covering the spectrum from 600 nm to 1100 nm, developed specifically for photoacoustic excitation. The system comprises of Yb-doped fiber oscillator and amplifier, an acousto-optic modulator and a photonic-crystal fiber to generate supercontinuum. Complete control over the pulse train, including generation of non-uniform pulse trains, is achieved via the AOM through custom-developed field-programmable gate-array electronics. The system is unique in that all the important parameters are adjustable: pulse duration in the range of 1-3 ns, pulse energy up to 10 μJ, repetition rate from 50 kHz to 3 MHz. Different photocoustic imaging probes can be excited with the ultrabroad spectrum. The entire system is fiber-integrated; guided-beam-propagation rendersit misalignment free and largely immune to mechanical perturbations. The laser is robust, low-cost and built using readily available components.

  6. All-optical fiber anemometer based on laser heated fiber Bragg gratings.

    PubMed

    Gao, Shaorui; Zhang, A Ping; Tam, Hwa-Yaw; Cho, L H; Lu, Chao

    2011-05-23

    A fiber-optic anemometer based on fiber Bragg gratings (FBGs) is presented. A short section of cobalt-doped fiber was utilized to make a fiber-based "hot wire" for wind speed measurement. Fiber Bragg gratings (FBGs) were fabricated in the cobalt-doped fiber using 193 nm laser pulses to serve as localized temperature sensors. A miniature all-optical fiber anemometer is constructed by using two FBGs to determine the dynamic thermal equilibrium between the laser heating and air flow cooling through monitoring the FBGs' central wavelengths. It was demonstrated that the sensitivity of the sensor can be adjusted through the power of pump laser or the coating on the FBG. Experimental results reveal that the proposed FBG-based anemometer exhibits very good performance for wind speed measurement. The resolution of the FBG-based anemometer is about 0.012 m/s for wind speed range between 2.0 m/s and 8.0 m/s.

  7. Remote Fiber Laser Cutting System for Dismantling Glass Melter - 13071

    SciTech Connect

    Mitsui, Takashi; Miura, Noriaki; Oowaki, Katsura; Kawaguchi, Isao; Miura, Yasuhiko; Ino, Tooru

    2013-07-01

    Since 2008, the equipment for dismantling the used glass melter has been developed in High-level Liquid Waste (HLW) Vitrification Facility in the Japanese Rokkasho Reprocessing Plant (RRP). Due to the high radioactivity of the glass melter, the equipment requires a fully-remote operation in the vitrification cell. The remote fiber laser cutting system was adopted as one of the major pieces of equipment. An output power of fiber laser is typically higher than other types of laser and so can provide high-cutting performance. The fiber laser can cut thick stainless steel and Inconel, which are parts of the glass melter such as casings, electrodes and nozzles. As a result, it can make the whole of the dismantling work efficiently done for a shorter period. Various conditions of the cutting test have been evaluated in the process of developing the remote fiber cutting system. In addition, the expected remote operations of the power manipulator with the laser torch have been fully verified and optimized using 3D simulations. (authors)

  8. Molecular Gas-Filled Hollow Optical Fiber Lasers in the Near Infrared

    DTIC Science & Technology

    2012-01-12

    HOLLOW OPTICAL FIBER LASERS IN THE NEAR F A9550-08-l-0344 INFRARED Sb. GRANT NUMBER Sc. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Sd. PROJECT NUMBER...SUPPLEMENTARY NOTES 14. ABSTRACT We have demonstrated of a new class of optically pumped gas lasers inside a hollow-core photonic crystal fibers . Here, a...crystal fiber . These lasers are the first in a new class of infrared lasers based on the combination of hollow- fiber and optically pumped-gas

  9. Picosecond passively mode-locked mid-infrared fiber laser

    NASA Astrophysics Data System (ADS)

    Wei, C.; Zhu, X.; Norwood, R. A.; Kieu, K.; Peyghambarian, N.

    2013-02-01

    Mode-locked mid-infrared (mid-IR) fiber lasers are of increasing interest due to their many potential applications in spectroscopic sensors, infrared countermeasures, laser surgery, and high-efficiency pump sources for nonlinear wavelength convertors. Er3+-doped ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF) fiber lasers, which can emit mid-IR light at 2.65-2.9 μm through the transition from the upper energy level 4I11/2 to the lower laser level 4I13/2, have attracted much attention because of their broad emission range, high optical efficiency, and the ready availability of diode pump lasers at the two absorption peaks of Er3+ ions (975 nm and 976 nm). In recent years, significant progress on high power Er3+- doped ZBLAN fiber lasers has been achieved and over 20 watt cw output at 2.8 μm has been demonstrated; however, there has been little progress on ultrafast mid-IR ZBLAN fiber lasers to date. We report a passively mode-locked Er3+- doped ZBLAN fiber laser in which a Fe2+:ZnSe crystal was used as the intracavity saturable absorber. Fe2+:ZnSe is an ideal material for mid-IR laser pulse generation because of its large saturable absorption cross-section and small saturation energy along with the excellent opto-mechanical (damage threshold ~2 J/cm2) and physical characteristics of the crystalline ZnSe host. A 1.6 m double-clad 8 mol% Er3+-doped ZBLAN fiber was used in our experiment. The fiber core has a diameter of 15 μm and a numerical aperture (NA) of 0.1. The inner circular cladding has a diameter of 125 μm and an NA of 0.5. Both continuous-wave and Q-switched mode-locking pulses at 2.8 μm were obtained. Continuous-wave mode locking operation with a pulse duration of 19 ps and an average power of 51 mW were achieved when a collimated beam traversed the Fe2+:ZnSe crystal. When the cavity was modified to provide a focused beam at the Fe2+:ZnSe crystal, Q-switched mode-locked operation with a pulse duration of 60 ps and an average power of 4.6 mW was achieved. More powerful

  10. Miniature ball-tip optical fibers for use in thulium fiber laser ablation of kidney stones

    NASA Astrophysics Data System (ADS)

    Wilson, Christopher R.; Hardy, Luke A.; Kennedy, Joshua D.; Irby, Pierce B.; Fried, Nathaniel M.

    2016-01-01

    Optical fibers, consisting of 240-μm-core trunk fibers with rounded, 450-μm-diameter ball tips, are currently used during Holmium:YAG laser lithotripsy to reduce mechanical damage to the inner lining of the ureteroscope working channel during fiber insertion and prolong ureteroscope lifetime. Similarly, this study tests a smaller, 100-μm-core fiber with 300-μm-diameter ball tip during thulium fiber laser (TFL) lithotripsy. TFL was operated at a wavelength of 1908 nm, with 35-mJ pulse energy, 500-μs pulse duration, and 300-Hz pulse rate. Calcium oxalate/phosphate stone samples were weighed, laser procedure times were measured, and ablation rates were calculated for ball tip fibers, with comparison to bare tip fibers. Photographs of ball tips were taken before and after each procedure to track ball tip degradation and determine number of procedures completed before need for replacement. A high speed camera also recorded the cavitation bubble dynamics during TFL lithotripsy. Additionally, saline irrigation rates and ureteroscope deflection were measured with and without the presence of TFL fiber. There was no statistical difference (P>0.05) between stone ablation rates for single-use ball tip fiber (1.3±0.4 mg/s) (n=10), multiple-use ball tip fiber (1.3±0.5 mg/s) (n=44), and conventional single-use bare tip fibers (1.3±0.2 mg/s) (n=10). Ball tip durability varied widely, but fibers averaged greater than four stone procedures before failure, defined by rapid decline in stone ablation rates. Mechanical damage at the front surface of the ball tip was the limiting factor in fiber lifetime. The small fiber diameter did not significantly impact ureteroscope deflection or saline flow rates. The miniature ball tip fiber may provide a cost-effective design for safe fiber insertion through the ureteroscope working channel and into the ureter without risk of instrument damage or tissue perforation, and without compromising stone ablation efficiency during TFL lithotripsy.

  11. Thulium:ZBLAN blue fiber laser pumped by two wavelengths

    SciTech Connect

    Tohmon, G.; Sato, H.; Ohya, J.; Uno, T.

    1997-05-01

    We demonstrate and analyze an upconversion blue fiber laser pumped by two wavelengths. Lasing at 0.48 {mu}m with very low pump threshold power is obtained from a Tm-doped fluorozirconate fiber that is counterpropagating pumped by 1.21- and 0.649-{mu}m light. We employed a rate-equation analysis using parameters obtained by fitting to the experimental data to predict the 0.48-{mu}m output characteristics as a function of fiber length and output reflectivity. {copyright} 1997 Optical Society of America

  12. Laser Processing of Carbon Fiber Reinforced Plastics - Release of Carbon Fiber Segments During Short-pulsed Laser Processing of CFRP

    NASA Astrophysics Data System (ADS)

    Walter, Juergen; Brodesser, Alexander; Hustedt, Michael; Bluemel, Sven; Jaeschke, Peter; Kaierle, Stefan

    Cutting and ablation using short-pulsed laser radiation are promising technologies to produce or repair CFRP components with outstanding mechanical properties e.g. for automotive and aircraft industry. Using sophisticated laser processing strategies and avoiding excessive heating of the workpiece, a high processing quality can be achieved. However, the interaction of laser radiation and composite material causes a notable release of hazardous substances from the process zone, amongst others carbon fiber segments or fibrous particles. In this work, amounts and geometries of the released fiber segments are analyzed and discussed in terms of their hazardous potential. Moreover, it is investigated to what extent gaseous organic process emissions are adsorbed at the fiber segments, similar to an adsorption of volatile organic compounds at activated carbon, which is typically used as filter material.

  13. Single-Frequency Narrow Linewidth 2 Micron Fiber Laser

    NASA Technical Reports Server (NTRS)

    Jiang, Shibin (Inventor); Spiegelberg, Christine (Inventor); Luo, Tao (Inventor)

    2006-01-01

    A compact single frequency, single-mode 2 .mu.m fiber laser with narrow linewidth, <100 kHz and preferably <100 kHz, is formed with a low phonon energy glass doped with triply ionized rare-earth thulium and/or holmium oxide and fiber gratings formed in sections of passive silica fiber and fused thereto. Formation of the gratings in passive silica fiber both facilitates splicing to other optical components and reduces noise thus improving linewidth. An increased doping concentration of 0.5 to 15 wt. % for thulium, holmium or mixtures thereof produces adequate gain, hence output power levels for fiber lengths less than 5 cm and preferably less than 3 cm to enable single-frequency operation.

  14. Gain enhanced L-band optical fiber amplifiers and tunable fiber lasers with erbium-doped fibers

    NASA Astrophysics Data System (ADS)

    Chen, H.; Leblanc, M.; Schinn, G. W.

    2003-02-01

    We report on the experimental investigation of gain enhanced L-band erbium-doped fiber amplifiers (EDFA) by either recycling residual ASE or using a second C-band wavelength pump laser and on the experimental demonstration of L-band tunable erbium-doped fiber ring lasers. We observed that by reflecting ASE from pumped erbium-doped fiber (EDF) the L-band EDFA gain can be enhanced of 2-15 dB depending on amplifier designs. We also studied wavelength and power dependence of second pump laser on the gain enhanced L-band EDFA and found that an optimum wavelength for second pump laser was between 1550 and 1560 nm. Finally, a L-band tunable erbium-doped fiber laser was also constructed in which lazing oscillation was observed closed to 1624 nm by recycling residual ASE. This L-band tunable laser has a line-width of about 300 MHz, an output power of 1 mW, and a signal to source spontaneous emission ratio of 60 dB.

  15. Efficient stimulated Raman scattering in hybrid liquid-silica fibers for wavelength conversion

    NASA Astrophysics Data System (ADS)

    Lebrun, Sylvie; Phan Huy, Minh-Châu.; Delaye, Philippe; Pauliat, Gilles

    2016-10-01

    Wavelength Raman converters have been developed for years to provide an elegant solution to easily shift the wavelength of existing lasers. In the pulse regime, due to relatively low Raman gains, these converters are usually limited to high-energy pulses, typically a few J or a few mJ in the nanosecond or picosecond regime. In order to build efficient Raman converters with lower energy pulses, we have developed a new class of fiber wavelength shifters based on Stimulated Raman Scattering in the liquid filling the hollow core of photonic bandgap fibers or Kagome fibers. The liquid choice, the design of the photonic crystal microstructure, the fiber length and its diameter give us enough degrees of freedom to realize efficient and versatile shifters, each being optimized for a specific wavelength shift. Connecting such a fiber device to a fixed wavelength laser allows delivering a new wavelength. With the same laser, another wavelength can be obtained by connecting another shifter. Using microlasers delivering 532 nm sub-nanosecond pulses of about 1 μJ, we already built a full series of shifters to reach any wavelength among: 556 nm; 561 nm; 582 nm; 595 nm; 612 nm; 630 nm; 650 nm; 667 nm; 772 nm. Hereafter, we detail how we design and optimize these new devices.

  16. Fiber Optically Coupled Eyesafe Laser Threat Warning System

    DTIC Science & Technology

    2000-05-11

    WARNING SYSTEM 11 MAY 2000 MSS SPECIALTY GROUP ON INFRARED COUNTERMEASURES NAVAL POSTGRADUATE SCHOOL, MONTEREY, CA PRESENTED BY: DR. AL TORRES...A Dates Covered (from... to) - Title and Subtitle Fiber Optically Coupled Eyesafe Laser Threat Warning System Contract Number Grant Number... WARNING SYSTEM (ESLTWS) PHASE II SBIR PROGRAM • CONCEPT: - TO DEVELOP A UNIQUE AND NOVEL EYE SAFE LASER THREAT WARNING RECEIVER SYSTEM. MUST BE

  17. A High Power Frequency Doubled Fiber Laser

    NASA Technical Reports Server (NTRS)

    Thompson, Robert J.; Tu, Meirong; Aveline, Dave; Lundblad, Nathan; Maleki, Lute

    2003-01-01

    This viewgraph presentation reports on the development of a high power 780 nm laser suitable for space applications of laser cooling. A possible solution is to use frequency doubling of high power 1560 nm telecom lasers. The presentation shows a diagram of the frequency conversion, and a graph of the second harmonic generation in one crystal, and the use of the cascading crystals. Graphs show the second harmonic power as a function of distance between crystals, second harmonic power vs. pump power, tunability of laser systems.

  18. Erbium-doped photonic crystal fiber chaotic laser

    NASA Astrophysics Data System (ADS)

    Martín, Juan C.; Used, Javier; Sánchez-Martín, José A.; Berdejo, Víctor; Vallés, Juan A.; Álvarez, José M.; Rebolledo, Miguel A.

    2011-09-01

    An erbium-doped photonic crystal fiber laser has been designed, constructed and characterized in order to examine the feasibility of this kind of devices for secure communications applications based on two identical chaotic lasers. Inclusion of a tailored photonic crystal fiber as active medium improves considerably the security of the device because it allows customization of the mode transversal profile, very influential on the laser dynamics and virtually impossible to be cloned by undesired listeners. The laser design has been facilitated by the combination of characterization procedures and models developed by us, which allow prediction of the most suitable laser features (losses, length of active fiber, etc.) to a given purpose (in our case, a laser that emits chaotically for a wide assortment of pump modulation conditions). The chaotic signals obtained have been characterized by means of topological analysis techniques. The underlying chaotic attractors found present topological structures belonging to classes of which very scarce experimental results have been reported. This fact is interesting from the point of view of the study of nonlinear systems and, besides, it is promising for secure communications: the stranger the signals, the more difficult for an eavesdropper to synthesize another system with similar dynamics.

  19. Hot bending with a fiber coupled solid state laser

    NASA Astrophysics Data System (ADS)

    Bammer, F.; Schumi, T.; Schuöcker, D.

    2010-09-01

    For bending of brittle materials it is necessary to heat up the forming zone. This can be done with a fiber coupled solid state laser, whose beam is evenly distributed on the bending line with a beam splitter installed in the lower tool (die) of a bending press. With polarization optics the laser beam is divided there into partial beams that are evenly distributed on the bending line with lenses and prisms. A setup for a bending length of 200mm heated by a fiber-coupled 3kW Nd:YAG-laser shows the feasibility of the concept. Successful operation was shown for the Mg-alloy AZ31, which breaks during forming at room temperature, but can be well formed at temperatures in the range of 200-300°C. Other materials benefiting from this method are Ti-alloys, high-strength-Al-alloys, and high-strength-steels. Typical heating times are in the range of up to 5s and much of the heat input is generated during the bending operation where the laser continues to work. Laser Assisted Bending with a fiber coupled solid state laser is a straightforward way to perform the bending of brittle materials in a process as simple as cold bending.

  20. Thulium fiber laser damage to Nitinol stone baskets

    NASA Astrophysics Data System (ADS)

    Wilson, Christopher R.; Hardy, Luke A.; Irby, Pierce B.; Fried, Nathaniel M.

    2015-02-01

    Our laboratory is studying the experimental Thulium fiber laser (TFL) as an alternative lithotripter to clinical gold standard Holmium:YAG laser. Safety studies characterizing undesirable Holmium laser-induced damage to Nitinol stone baskets have been previously reported. Similarly, this study characterizes TFL induced stone basket damage. A TFL beam with pulse energy of 35 mJ, pulse duration of 500 μs, and pulse rates of 50-500 Hz was delivered through 100-μm-core optical fibers, to a standard 1.9-Fr Nitinol stone basket wire. Stone basket damage was graded as a function of pulse rate, number of pulses, and working distance. Nitinol wire damage decreased with working distance and was non-existent at distances greater than 1.0 mm. In contact mode, 500 pulses delivered at pulse rates >= 200 Hz (<= 2.5 s) were sufficient to cut Nitinol wires. The Thulium fiber laser, operated in low pulse energy and high pulse rate mode, may provide a greater safety margin than standard Holmium laser for lithotripsy, as evidenced by shorter non-contact working distances for stone basket damage than previously reported with Holmium laser.

  1. Advanced experiments with an erbium-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Marques, Paulo V. S.; Marques, Manuel B.; Rosa, Carla C.

    2014-07-01

    This communication describes an optical hands-on fiber laser experiment aimed at advanced college courses. Optical amplifiers and laser sources represent very important optical devices in numerous applications ranging from telecommunications to medicine. The study of advanced photonics experiments is particularly relevant at undergraduate and master level. This paper discusses the implementation of an optical fiber laser made with a cavity built with two tunable Bragg gratings. This scheme allows the students to understand the laser working principles as a function of the laser cavity set-up. One or both of the gratings can be finely tuned in wavelength through applied stress; therefore, the degree of spectral mismatch of the two gratings can be adjusted, effectively changing the cavity feedback. The impact of the cavity conditions on the laser threshold, spectrum and efficiency is analyzed. This experiment assumes that in a previous practice, the students should had already characterized the erbium doped fiber in terms of absorption and fluorescent spectra, and the spectral gain as a function of pump power.

  2. Research of time fiducial and imaging VISAR laser for Shenguang-III laser facility

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Wang, Zhenguo; Tian, Xiaocheng; Zhou, Dandan; Zhu, Na; Wang, Jianjun; Li, Mingzhong; Xu, Dangpeng; Dang, Zhao; Hu, Dongxia; Zhu, Qihua; Zheng, Wanguo; Wang, Feng

    2015-10-01

    Time fiducial laser is an important tool for the precise measurement in high energy density physics experiments. The VISAR probe laser is also vital for shock wave diagnostics in ICF experiments. Here, time fiducial laser and VISAR light were generated from one source on SG-III laser facility. After generated from a 1064-nm DFB laser, the laser is modulated by an amplitude modulator driven by 10 GS/s arbitrary waveform generator. Using time division multiplexing technology, the ten-pulse time fiducial laser and the 20-ns VISAR pulse were split by a 1×2 multiplexer and then chosen by two acoustic optic modulators. Using the technique, cost of the system was reduced. The technologies adopted in the system also include pulse polarization stabilization, high precision fiber coupling and energy transmission. The time fiducial laser generated synchronized 12-beam 2ω and 4-beam 3ω laser, providing important reference marks for different detectors and making it convenient for the analysis of diagnostic data. After being amplified by fiber amplifiers and Nd:YAG rod amplifiers, the VISAR laser pulse was frequency-converted to 532-nm pulse by a thermally controlled LBO crystal with final output energy larger than 20 mJ. Finally, the green light was coupled into a 1-mm core diameter, multimode fused silica optical fiber and propagated to the imaging VISAR. The VISAR laser has been used in the VISAR diagnostic physics experiments. Shock wave loading and slowdown processes were measured. Function to measure velocity history of shock wave front movement in different kinds of materials was added to the SG-III laser facility.

  3. Erbium-doped CW and Q-switched fiber ring laser with fiber grating Michelson interferometer

    NASA Astrophysics Data System (ADS)

    Wang, Anting; Ming, Hai; Xie, Jianping; Xu, Lixin; Huang, Wencai; Lv, Liang; Chen, Xiyao; Li, Feng; Wu, Yunxia; Xing, Meishu

    2003-01-01

    The band-pass characteristic of fiber grating Michelson interferometer is analyzed, which acts as both band-pass filter and Q-switch. An erbium-doped fiber ring laser based on fiber grating Michelson interferometer is implemented for producing single longitudinal mode CW operation with 5 MHz spectral linewidth and up to 6 mW output power. In Q-switched operation, stable fiber laser output pulses with repetition rate of 800 Hz, pulse width of 0.6 ?s, average power of 1.8 mW and peak power of 3.4 W are demonstrated. The peak power and average power of the Q-switched pulses are varied with the repetitionrate.

  4. Intensity-demodulated fiber-ring laser sensor system for acoustic emission detection.

    PubMed

    Han, Ming; Liu, Tongqing; Hu, Lingling; Zhang, Qi

    2013-12-02

    We theoretically and experimentally demonstrate a fiber-optic ultrasonic sensor system based on a fiber-ring laser whose cavity consisting of a regular fiber Bragg grating (FBG) and a tunable optical band-pass filter (TOBPF). The FBG is the sensing element and the TOBPF is used to set the lasing wavelength at a point on the spectral slope of the FBG. The ultrasonic signal is detected by the variations of the laser output intensity in response to the cold-cavity loss modulations from the ultrasonically-induced FBG spectral shift. The system demonstrated here has a simple structure and low cost, making it attractive for acoustic emission detection in structure health monitoring.

  5. Linearly-polarized Yb-doped fiber laser based on 45-degree fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Fu, Shenggui; Liu, Xiaojuan; Guo, Liping; Ge, Xiaolu; Wei, Gongxiang

    2012-11-01

    In the paper, a 45 degree TFBG was fabricated in photosensitive fiber successfully using phase mask technique. The polarization-dependent loss characteristic of the TFBG was experimentally researched in the paper using a special measurement system. The measurement results showed that the 45 degree TFBG could act as a polarization possession element. Based on the 45 degree TFBG, a linearly-polarized Yb-doped fiber laser was demonstrated. The polarization-extinction ratio of the output laser is about 30 dB. The output power was about 13 mW with the pump power of 100 mW. The central wavelength of the laser is 1064nm and the wavelength bandwidth was about 0.7nm. Being a polarization device, the TFBG has the advantages of in-fiber, compact, good polarization capability and low price.

  6. Distributed feedback imprinted electrospun fiber lasers.

    PubMed

    Persano, Luana; Camposeo, Andrea; Del Carro, Pompilio; Fasano, Vito; Moffa, Maria; Manco, Rita; D'Agostino, Stefania; Pisignano, Dario

    2014-10-01

    Imprinted, distributed feedback lasers are demonstrated on individual, active electrospun polymer nanofibers. In addition to advantages related to miniaturization, optical confinement and grating nanopatterning lead to a significant threshold reduction compared to conventional thin-film lasers. The possibility of imprinting arbitrary photonic crystal geometries on electrospun lasing nanofibers opens new opportunities for realizing optical circuits and chips.

  7. Characterization of holmium fibers with various concentrations for fiber laser applications around 2.1 μm

    NASA Astrophysics Data System (ADS)

    Aubrecht, Jan; Peterka, Pavel; Honzatko, Pavel; Baravets, Yauhen; Jelinek, Michal; Kubecek, Vaclav; Pawliszewska, Maria; Sotor, Jaroslaw; Sobon, Grzegorz; Abramski, Krzysztof M.; Kasik, Ivan

    2016-04-01

    In this work, we present experimental results of characterization of the developed holmium-doped silica-based optical fibers with holmium ions concentrations in the range from 1000 to 10000 ppm. The fibers were fabricated by the modified chemical vapor deposition and solution doping method. They were characterized in terms of their spectral attenuation, refractive index profile, and especially performance in fiber laser. Simultaneously, two different fiber laser setups were tested. In the first one, holmium-doped fiber in Fabry-Perot configuration was pumping by in house developed thulium-doped fiber laser in ring arrangement. In the second one, bulk-optic pump-coupling configuration, consisted of a commercially available thulium fiber laser emitting at 1940 nm and system of lenses and mirrors was used. We have focused on comparison of laser output powers, slope efficiencies, and laser thresholds for individual holmiumdoped fiber in these different laser arrangements. Finally, the application of the developed fiber in subpicosecond fiber laser with graphene-based saturable absorber for mode-locking operation was investigated.

  8. Single-longitudinal-mode DBR fiber laser based on the self-made photosensitive Er-doped fiber

    NASA Astrophysics Data System (ADS)

    Ren, Wen-hua; Zheng, Jing-jing; Wang, Yan-hua; Tao, Pei-lin; Tan, Zhong-wei; Jian, Shui-sheng

    2008-12-01

    Two fiber Bragg gratings with ~35mm spatial interval are written in the self-made photosensitive Erbium-doped fiber (PEDF) to form a fiber Bragg grating Fabry-Perot (FBG F-P) cavity. A distributed Bragg reflector (DBR) fiber laser is built up based on the FBG F-P cavity. 1.8mW laser output is achieved with 63mW pump power. By calculating the mode-spacing using the effective length of the FBG F-P cavity, the output of the DBR fiber laser is proved to be singlelongitudinal- mode (SLM).

  9. All-fiber passively mode-locked femtosecond laser using a 45º-tilted fiber grating polarization element.

    PubMed

    Mou, Chengbo; Wang, Hua; Bale, Brandon G; Zhou, Kaiming; Zhang, Lin; Bennion, Ian

    2010-08-30

    We report on the demonstration of an all-fiber femtosecond erbium doped fiber laser passively mode-locked using a 45º tilted fiber grating as an in-fiber polarizer in the laser cavity. The laser generates 600 fs pulses with output pulse energies ~1 nJ. Since the 45° tilted grating has a broad polarization response, the laser output has shown a tunabilty in wavelength from 1548 nm to 1562 nm by simply adjusting the polarization controllers in the cavity.

  10. Laser-drilled free-form silica fiber preforms for microstructured optical fibers

    NASA Astrophysics Data System (ADS)

    Becker, Martin; Werner, Marcel; Fitzau, Oliver; Esser, Dominik; Kobelke, Jens; Lorenz, Adrian; Schwuchow, Anka; Rothhardt, Manfred; Schuster, Kay; Hoffmann, Dieter; Bartelt, Hartmut

    2013-10-01

    We describe a laser drilling technology suitable for structuring solid glass preforms for microstructured optical fibers. This technology offers the possibility to prepare complex preform designs that cannot be easily managed by the stack-and-draw technology. As a proof of concept, we present a four-ring hexagonal hole structure drilled in a silica rod over a length of 80 mm. A fiber drawn from such a preform has been analyzed to demonstrate the feasibility of this concept.

  11. Multiwavelength generation in a random distributed feedback fiber laser using an all fiber Lyot filter.

    PubMed

    Sugavanam, S; Yan, Z; Kamynin, V; Kurkov, A S; Zhang, L; Churkin, D V

    2014-02-10

    Multiwavelength lasing in the random distributed feedback fiber laser is demonstrated by employing an all fiber Lyot filter. Stable multiwavelength generation is obtained, with each line exhibiting sub-nanometer line-widths. A flat power distribution over multiple lines is obtained, which indicates that the power between lines is redistributed in nonlinear mixing processes. The multiwavelength generation is observed both in first and second Stokes waves.

  12. All-fiber tunable filter and laser based on two-mode fiber.

    PubMed

    Yun, S H; Hwang, I K; Kim, B Y

    1996-01-01

    We demonstrate an all-fiber acousto-optic tunable filter based on two-spatial-mode coupling, with improved ruggedness and efficiency, by using a new acoustic-transducer design. We use a rigorous modeling of the flexural acoustic wave to analyze the mode coupling with better accuracy. Using the acousto-optic tunable filter, we demonstrate a novel all-fiber tunable laser with a tuning range of more than 20 nm and a linewidth of 0.2 nm.

  13. Ultrafast, stretched-pulse thulium-doped fiber laser with a fiber-based dispersion management.

    PubMed

    Wienke, Andreas; Haxsen, Frithjof; Wandt, Dieter; Morgner, Uwe; Neumann, Jörg; Kracht, Dietmar

    2012-07-01

    An ultrafast thulium-doped fiber laser with stretched-pulse operation has been realized and investigated. The passively mode-locked oscillator emitted 119 fs pulses at a peak wavelength of 1912 nm. A normal-dispersion fiber with a high numerical aperture and small core was used for intracavity dispersion management and external compression. Numerical simulations were performed and are in good agreement with the experimental results.

  14. High energy similariton fiber laser using chirally-coupled-core fiber

    PubMed Central

    Lefrancois, Simon; Liu, Chi-Hung; Stock, Michelle L.; Sosnowski, Thomas S.; Galvanauskas, Almantas; Wise, Frank W.

    2013-01-01

    We present a high energy amplifier similariton laser based on chirally-coupled core fiber. Chirped pulse energies up to 61 nJ at 3.3 W average power are obtained with effectively singlemode output. The pulses can be compressed with a simple grating compressor to durations below 90 fs. We demonstrate for the first time a fused pump-signal combiner to confirm the integration potential of chirally-coupled core fibers. PMID:23282832

  15. Effect of frequency-doubling pulse Nd:YAG laser on microbial mutation

    NASA Astrophysics Data System (ADS)

    Zhao, Yansheng; Wang, Luyan; Zheng, Heng; Yin, Hongping; Chen, Xiangdong; Tan, Zheng; Wu, Wutong

    1999-09-01

    We are going to report the mutagenic effect of frequency-doubling pulse Nd:YAG laser (532 nm) on microbe. After irradiation with pulse laser, mutants of abscisic acid producing strains and erythromycin producing strains were obtained, one of which could produce 62.1% and 57% more products than control, respectively. In the study of mutagenization of Spirulina platensis caused by pulse laser, we selected a high photosynthetic strains, with improved productivity of protein and exocellular ploysaccharides of 12% and 246%, respectively. The experimental results indicate that frequency-doubling pulse laser (532 nm) is a potential new type of physical mutagenic factor.

  16. Highly Efficient Operation of Tm:fiber Laser Pumped Ho:YLF Laser

    NASA Technical Reports Server (NTRS)

    Bai, Yingxin; Petros, M.; Yu, Jirong; Petzar, Paul; Trieu, Bo; Chen, Sam; Lee, Hyung; Singh, U.

    2006-01-01

    A 19 W, TEM(sub 00) mode, Ho:YLF laser pumped by continuous wave Tm:fiber laser has been demonstrated at the room temperature. The slope efficiency and optical-to-optical efficiency are 65% and 55%, respectively.

  17. Research on ytterbium-doped photonic crystal fiber amplifier for the femtosecond fiber laser

    NASA Astrophysics Data System (ADS)

    Tian, Hongchun; Hou, Zhiyun; Zhang, Sa; Zhou, Guiyao; Xia, Changming; Zhang, Wei; Wu, Jiale; liu, Hongzhan; Zheng, Yan

    2016-01-01

    We report on a single-stage, high-repetition photonic crystal fiber amplifier working at 1030 nm seeded by a femtosecond fiber laser, which generates an output with average power of 2.23 W at a repetition rate of 49.5 MHz and a 3 dB spectral width of 5 nm, corresponding to a pulse energy of 45.2 nJ. After amplification, the spectrum of the femtosecond laser is broadened. A home-made, ytterbium-doped, double-clad photonic crystal fiber fabricated by laser sintering technology combined with a solution doping method with a core diameter of only 24 μm is used as the power amplifier medium. The spectral characteristics as well as the suppression of amplified spontaneous emission are discussed in detail. Experiment confirms that the amplified spontaneous emission becomes negligible with increasing incident seed power and no obvious nonlinear effects arise in this experiment. These results can provide motivation for the application of ytterbium-doped photonic crystal fiber and can provide a potential application for the high-power, all-fiber laser in the future.

  18. Rogue waves in a normal-dispersion fiber laser.

    PubMed

    Liu, Zhanwei; Zhang, Shumin; Wise, F W

    2015-04-01

    Experimental evidence of rogue-wave formation in a normal-dispersion ytterbium fiber laser is reported. Spectral filtering is a primary component of pulse-shaping in normal-dispersion lasers, and we find that the choice of filter dramatically influences the distribution of noise-pulse energies produced by these lasers. With an interference filter in the cavity, non-Gaussian distributions with pulses as large as 6 times the significant wave height are observed. These correspond to pulse energies as high as ∼50  nJ. To our knowledge, the results presented are not accounted for by existing theoretical models of rogue-wave formation.

  19. Development of pulse laser processing for mounting fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Nishimura, Aikihko; Shimada, Yukihiro; Yonemoto, Yukihiro; Suzuki, Hirokazu; Ishibashi, Hisayoshi

    2012-07-01

    Pulse laser processing has been developed for the application of industrial plants in monitoring and maintenance. Surface cleaning by nano-second laser ablation was demonstrated for decontamination of oxide layers of Cr contained steel. Direct writing by femtosecond processing induced a Bragg grating in optical fiber to make it a seismic sensor for structural health monitoring. Adhesive cement was used to fix the seismic sensor on the surface of reactor coolant pipe material. Pulse laser processing and its related technologies were presented to overcome the severe accidents of nuclear power plants.

  20. Synchronization and symmetry breaking in mutually coupled fiber lasers.

    PubMed

    Rogers-Dakin, Elizabeth A; García-Ojalvo, Jordi; DeShazer, David J; Roy, Rajarshi

    2006-04-01

    We experimentally study the synchronization and the emergence of leader-follower dynamics in two time-delayed mutually coupled fiber ring lasers. We utilize spatiotemporal representations of time series to establish the roles of leader and follower in the synchronized dynamics.

  1. Synchronization and symmetry breaking in mutually coupled fiber lasers

    NASA Astrophysics Data System (ADS)

    Rogers-Dakin, Elizabeth A.; García-Ojalvo, Jordi; Deshazer, David J.; Roy, Rajarshi

    2006-04-01

    We experimentally study the synchronization and the emergence of leader-follower dynamics in two time-delayed mutually coupled fiber ring lasers. We utilize spatiotemporal representations of time series to establish the roles of leader and follower in the synchronized dynamics.

  2. Laser Treatment, Bonding Potential Road to Success for Carbon Fiber

    ScienceCinema

    Sabau, Adrian

    2016-07-12

    Joining carbon fiber composites and aluminum for lightweight cars and other multi-material high-end products could become less expensive and the joints more robust because of a new method that harnesses a laser’s power and precision.

  3. All-fiber broad-range self-sweeping Yb-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Lobach, Ivan A.; Kablukov, Sergey A.; Podivilov, Evgeniy V.; Babin, Sergey A.

    2012-02-01

    The effect of broad-range self-sweeping in Yb-doped fiber laser has been demonstrated experimentally for the first time. The self-sweeping effect is observed in an all-fiber laser configuration with a double-clad Yb-doped fiber and a cavity formed by a broad-band fiber loop mirror and Fresnel reflection from one cleaved end. The sweep range is limited by the width of the broad-band reflector and reaches up to 16nm. It is found that the self-sweeping effect is related to selfpulsations. So the sweep rate is increased with an increase in pump power and is decreased with increasing cavity length. RF and optical spectra (linewidth is measured to be not more than 100 MHz) show that during the evolution of a single pulse a small number of longitudinal modes take a part in lasing. Based on these results we propose a model describing dynamics of the laser frequency. The model is based on the spatial hole burning effect and the gain saturation in Yb laser transition, and takes into account self-pulsations of the laser. Theoretical estimation for pulse to pulse change of lasing frequency is in good agreement with experimental data.

  4. DFB fiber laser hydrophone with band-pass response.

    PubMed

    Zhang, Faxiang; Zhang, Wentao; Li, Fang; Liu, Yuliang

    2011-11-15

    A distributed-feedback fiber laser hydrophone with band-pass response is presented. The design of the hydrophone aims to equalize static pressure and eliminate signal aliasing of high-frequency acoustic components. Theoretical analysis is presented based on electro-acoustic theory. The experimental results agree well with the theory. The measured underwater responses show that the hydrophone has a pressure sensitivity of -170 dB re:pm/μPa over a bandwidth between 100 Hz and 500 Hz. A sensitivity reduction exceeding -35 dB is observed at 2500 Hz. The tested static pressure sensitivity of the hydrophone is -226 dB. The proposed fiber laser hydrophone of this kind is expected to have important application in deep water fiber-optic sonar systems with anti-aliasing, and the understanding gained through this work can be extended to a guide of hydrophone design for required filtering bandwidth.

  5. Pulsed blue laser source based on frequency quadrupling of a thulium fiber laser

    NASA Astrophysics Data System (ADS)

    Honea, Eric; Savage-Leuchs, Matthias; Bowers, Mark S.; Yilmaz, Tolga; Mead, Roy

    2013-03-01

    We describe a pulsed blue (485 nm) laser source based on frequency quadrupling a pulsed Tm fiber laser. Up to 1.2 W at 485 nm was generated with an M2 of 1.3. At 10 kHz pulse repetition frequency, the output pulse at 485 nm was 65 ns FWHM resulting in an estimated peak power of 1.8 kW. We anticipate further improvements in power scaling with higher power Tm fiber lasers and improved conversion efficiency to the blue with optimized AR coatings and nonlinear optical crystals.

  6. All-fiber mode-locked nanosecond laser employing intracavity chirped fiber gratings.

    PubMed

    Wang, Hushan; Wang, Yishan; Zhao, Wei; Zhang, Wei; Zhang, Ting; Hu, Xiaohong; Yang, Zhi; Liu, Hongjun; Duan, Kailiang; Liu, Xuemin; Li, Cheng; Shen, Deyuan; Sui, Zhan; Liu, Bin

    2010-03-29

    We demonstrate that nanosecond pulses are generated directly from an all-fiber mode-locked ytterbium-doped fiber laser. A pair of Chirped Fiber Gratings (CFGs) with different sign of dispersion is employed for intracavity dispersion management. Self-starting stabilized mode-locking operation is achieved by nonlinear polarization evolution (NPE). The 1.27 ns pulses are obtained after one CFG with large positive dispersion. The pulse energy is up to 15 nJ at a repetition rate of 3.48 MHz.

  7. Understanding the fiber tip thermal runaway present in 3 µm fluoride glass fiber lasers.

    PubMed

    Caron, Nicolas; Bernier, Martin; Faucher, Dominic; Vallée, Réal

    2012-09-24

    When the tip of a fluoride glass fiber is exposed to ambient air, water vapor reacts with the glass constituents, increasing the OH contaminants at the surface. These OH impurities then diffuse inside the glass according to Fick's laws. Laser radiation at around 3 µm is strongly absorbed by the OH contaminants, causing local heating of the fiber tip resulting in an increase of the diffusion process which ultimately leads to fiber tip destruction. We accurately model this phenomenon by combining the diffusion theory with a basic thermal equation. Experimental measurements are in agreement with the model predictions for a good range of operating conditions.

  8. UV-laser-inscribed fiber Bragg gratings in photonic crystal fibers and sensing applications

    NASA Astrophysics Data System (ADS)

    Wang, Yiping; Bartelt, Hartmut; Ecke, Wolfgang; Willsch, Reinhardt; Kobelke, Jens

    2011-11-01

    We report about fiber Bragg gratings (FBGs) inscribed in two different types of small-core Ge-doped photonic crystal fibers with a UV laser. Sensing applications of the FBGs were systematically investigated by means of demonstrating the responses of Bragg wavelengths to temperature, strain, bending, and transverse-loading. The Bragg wavelength of the FBGs shifts toward longer wavelengths with increasing temperature, tensile strain, and transverse-loading. Moreover, the bending and transverse-loading properties of the FBGs are sensitive to the fiber orientations. The reasonable analyses for these sensing properties also are presented.

  9. Novel fiber-MOPA-based high power blue laser

    NASA Astrophysics Data System (ADS)

    Engin, Doruk; Fouron, Jean-Luc; Chen, Youming; Huffman, Andromeda; Fitzpatrick, Fran; Burnham, Ralph; Gupta, Shantanu

    2012-06-01

    5W peak power at 911 nm is demonstrated with a pulsed Neodymium (Nd) doped fiber master oscillator power amplifier (MOPA). This result is the first reported high gain (16dB) fiber amplifier operation at 911nm. Pulse repetition frequency (PRF) and duty-cycle dependence of the all fiber system is characterized. Negligible performance degreadation is observed down to 1% duty cycle and 10 kHz PRF, where 2.5μJ of pulse energy is achieved. Continuous wave (CW) MOPA experiments achieved 55mW average power and 9dB gain with 15% optical to optical (o-o) efficiency. Excellent agreement is established between dynammic fiber MOPA simulation tool and experimental results in predicting output amplified spontaneous emission (ase) and signal pulse shapes. Using the simulation tool robust Stimulated Brillion Scattering (SBS) free operation is predicted out of a two stage all fiber system that generates over 10W's of peak power with 500 MHz line-width. An all fiber 911 nm pulsed laser source with >10W of peak power is expected to increase reliability and reduce complexity of high energy 455 nm laser system based on optical parametric amplification for udnerwater applications. The views expressed are thos of the author and do not reflect the official policy or position of the Department of Defense or the U.S. Government.

  10. Dual wavelength erbium-doped fiber laser using a tapered fiber

    NASA Astrophysics Data System (ADS)

    Harun, S. W.; Lim, K. S.; Jasim, A. A.; Ahmad, H.

    2010-12-01

    A tapered fiber is fabricated by heating and stretching a piece of optical fiber after the polymer protective cladding has been removed. An equidistant comb-like transmission spectrum, with a spacing of 1.6 nm and an extinction ratio of more than 5 dB, was obtained by the tapered fiber due to the multibeam interferences of the cladding modes. The tapered fiber was applied in a ring erbium-doped fiber laser (EDFL) to generate dual-wavelength lasing oscillations. The EDFL operates at wavelengths of 1557.0 nm and 1558.6 nm with a stable peak power and a signal-to-noise ratio of more than 40 dB.

  11. Noncontact laser fiber delivery system for endoscopic medical applications

    NASA Astrophysics Data System (ADS)

    Denisov, Nikolay A.; Griffin, Stephen E.

    1999-02-01

    The objective of the study was to design and to investigate laser fiber delivery system for treatment of obstructed human internal tubular organs using endoscopic techniques. This system eliminates the main disadvantages of both applied contact and non-contact probes, namely surface contamination with concomitant hydrothermal probe deterioration and large beam divergence with poor energy density, respectively. Proposed silica or sapphire probes produce quasi-collimated beam with specific outside diameter and power distribution. To provide comparative analysis of laser delivery systems' optical properties with non-contact endoscopic probes 'steady beam distance' (SBD) and 'steady beam ratio' (SBR) coefficients are proposed. The calculation results are presented in the form of the plots of the SBR - coefficients and SBDs for a 2.0 mm specific outside beam diameter versus laser wavelength, delivery fiber core diameter and its numerical aperture for both probe material. Additionally, the cross power distributions along the SBD were studied. Results obtained could provide a useful tool to designers of non-contact fiber delivery systems intended for a variety of medical applications, including endoscopic surgery with cw or pulse laser tissue irradiation, skin de-epithelialization, laser-induced fluorescence and photodynamic therapy.

  12. Single-mode fiber laser based on core-cladding mode conversion.

    PubMed

    Suzuki, Shigeru; Schülzgen, Axel; Peyghambarian, N

    2008-02-15

    A single-mode fiber laser based on an intracavity core-cladding mode conversion is demonstrated. The fiber laser consists of an Er-doped active fiber and two fiber Bragg gratings. One Bragg grating is a core-cladding mode converter, and the other Bragg grating is a narrowband high reflector that selects the lasing wavelength. Coupling a single core mode and a single cladding mode by the grating mode converter, the laser operates as a hybrid single-mode laser. This approach for designing a laser cavity provides a much larger mode area than conventional large-mode-area step-index fibers.

  13. Random fiber laser directly pumped by a high-power laser diode.

    PubMed

    Babin, S A; Dontsova, E I; Kablukov, S I

    2013-09-01

    A random lasing based on Rayleigh scattering (RS) in a passive fiber directly pumped by a high-power laser diode (LD) has been demonstrated. Owing to the RS-based random distributed feedback (RDFB) the low-quality LD beam (938 nm) is converted into the high-quality laser output (980 nm). Because of the relatively low excess above the threshold with the available LD, the RDFB laser output is not stationary and limited in power at the 0.5 W level. In the used gradient-index fiber, the output beam has 4.5 lower divergence as compared with the pump beam thus demonstrating a new way for development of high-power fiber lasers with high-quality output.

  14. Dual-kind Q-switching of erbium fiber laser

    SciTech Connect

    Barmenkov, Yuri O. Kir'yanov, Alexander V.; Cruz, Jose L.; Andres, Miguel V.

    2014-03-03

    Two different regimes of Q-switching in the same implementation of an actively Q-switched erbium-doped fiber laser are demonstrated. Depending on the active fiber length and repetition rate of an intracavity Q-cell (acousto-optic modulator), the laser operates either in the regime of common, rather long and low-power, pulses composed of several sub-pulses or in the one of very short and powerful stimulated Brillouin scattering-induced pulses. The basic physical reason of the laser system to oscillate in one of these two regimes is the existence or absence of CW narrow-line “bad-cavity” lasing in the intervals when the Q-cell is blocked.

  15. Frequency doubling of Raman fiber lasers with random distributed feedback.

    PubMed

    Dontsova, E I; Kablukov, S I; Vatnik, I D; Babin, S A

    2016-04-01

    This Letter presents what we believe is the first experimental study of frequency doubling of a Raman fiber laser (RFL) with random distributed feedback (RDFB) in an MgO:PPLN crystal. We compared two laser configurations, each with a half-open cavity. The cavity contained either a broadband Sagnac mirror or a narrowband fiber Bragg grating (FBG). We found that spectral broadening in the studied configurations of the RDFB RFLs differed from that found in a conventional RFL with a linear cavity, as well as from each other. We also compared the second harmonic generation (SHG) efficiency for these three types of lasers. The highest SHG efficiency was obtained for the RDFB RFL with the FBG delivering >100  mW power at 654 nm.

  16. High-Energy Passive Mode-Locking of Fiber Lasers

    PubMed Central

    Ding, Edwin; Renninger, William H.; Wise, Frank W.; Grelu, Philippe; Shlizerman, Eli; Kutz, J. Nathan

    2012-01-01

    Mode-locking refers to the generation of ultrashort optical pulses in laser systems. A comprehensive study of achieving high-energy pulses in a ring cavity fiber laser that is passively mode-locked by a series of waveplates and a polarizer is presented in this paper. Specifically, it is shown that the multipulsing instability can be circumvented in favor of bifurcating to higher-energy single pulses by appropriately adjusting the group velocity dispersion in the fiber and the waveplate/polarizer settings in the saturable absorber. The findings may be used as practical guidelines for designing high-power lasers since the theoretical model relates directly to the experimental settings. PMID:22866059

  17. Tungsten diselenide Q-switched erbium-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Chen, Bohua; Zhang, Xiaoyan; Guo, Chaoshi; Wu, Kan; Chen, Jianping; Wang, Jun

    2016-08-01

    We report a tungsten diselenide (WSe2) polyvinyl alcohol (PVA)-based, saturable absorber and related experiment results of a Q-switched fiber laser. WSe2-PVA film is synthesized by liquid phase exfoliation method, and its saturable absorption is measured via a nonlinear transmission experiment. The result shows that WSe2-PVA saturable absorber has a modulation depth of 3.5%, which means it has potential for generating an ultrafast pulse laser. We apply this absorber into a ring-cavity erbium-doped fiber laser and obtain Q-switched pulses under appropriate pump power. Our work demonstrates the reliable nonlinear optical characteristics of WSe2 and the feasibility for this two-dimensional material to be applied in the field of nonlinear optics.

  18. Compact frequency-quadrupled pulsed 1030nm fiber laser

    NASA Astrophysics Data System (ADS)

    McIntosh, Chris; Goldberg, Lew; Cole, Brian; DiLazaro, Tom; Hays, Alan D.

    2016-03-01

    A compact 1030nm fiber laser for ultraviolet generation at 257.5nm is presented. The laser employs a short length of highly-doped, large core (20μm), coiled polarization-maintaining ytterbium-doped double-clad fiber pumped by a wavelength-stabilized 975nm diode. It is passively Q-switched via a Cr4+:YAG saturable absorber and generates 2.4W at 1030nm in a 110μJ pulse train. Lithium triborate (LBO) and beta-barium borate (BBO) are used to achieve 325mW average power at the fourth harmonic. The laser's small form factor, narrow linewidth and modest power consumption are suitable for use in a man-portable ultraviolet Raman explosives detection system.

  19. Spectroscopy of {sup 127}I{sub 2} hyperfine structure near 532 mm using frequency - doubled diode - laser - pumped Nd:YAG lasers

    SciTech Connect

    Guellati, S.; Elandaloussi, H.; Fretel, E.

    1994-12-31

    Frequency - doubled diode - laser - pumped Nd : Yag laser can constitute an interesting optical standard around 532 nm. More than ten of {sup 127}I{sub 2} lines can be observed inside the laser spectral range. Two independent systems, stabilized on one {sup 127}I{sub 2} hyperfine component, are used to check the frequency long term stability for metrological purpose.

  20. Dynamics of ultra-long Brillouin fiber laser

    NASA Astrophysics Data System (ADS)

    Fotiadi, Andrei A.; Lobach, Ivan; Mégret, Patrice

    2013-02-01

    We report on experimental studies of random lasing realized in optical fibers with the use of Brillouin amplification and Rayleigh backscattering employed as a distributed feedback instead of a cavity mirror. In our experiment 25-km-long high quality standard telecom single-mode fiber was employed for Rayleigh reflection uniformly distributed over all fiber length. We have observed a clear competition between a classical Brillouin scattering and Brillouin lasing. Presence of extended fluctuation-free fragments in the recorded oscilloscope traces highlights Stokes power statistics typical for laser radiation rather than for Brillouin process. The results of the experiments are in a perfect agreement with the model of Brillouin - Rayleigh cooperative process in long fibers.

  1. High-power ultralong-wavelength Tm-doped silica fiber laser cladding-pumped with a random distributed feedback fiber laser.

    PubMed

    Jin, Xiaoxi; Du, Xueyuan; Wang, Xiong; Zhou, Pu; Zhang, Hanwei; Wang, Xiaolin; Liu, Zejin

    2016-07-15

    We demonstrated a high-power ultralong-wavelength Tm-doped silica fiber laser operating at 2153 nm with the output power exceeding 18 W and the slope efficiency of 25.5%. A random distributed feedback fiber laser with the center wavelength of 1173 nm was employed as pump source of Tm-doped fiber laser for the first time. No amplified spontaneous emissions or parasitic oscillations were observed when the maximum output power reached, which indicates that employing 1173 nm random distributed feedback fiber laser as pump laser is a feasible and promising scheme to achieve high-power emission of long-wavelength Tm-doped fiber laser. The output power of this Tm-doped fiber laser could be further improved by optimizing the length of active fiber, reflectivity of FBGs, increasing optical efficiency of pump laser and using better temperature management. We also compared the operation of 2153 nm Tm-doped fiber lasers pumped with 793 nm laser diodes, and the maximum output powers were limited to ~2 W by strong amplified spontaneous emission and parasitic oscillation in the range of 1900-2000 nm.

  2. High-power ultralong-wavelength Tm-doped silica fiber laser cladding-pumped with a random distributed feedback fiber laser

    NASA Astrophysics Data System (ADS)

    Jin, Xiaoxi; Du, Xueyuan; Wang, Xiong; Zhou, Pu; Zhang, Hanwei; Wang, Xiaolin; Liu, Zejin

    2016-07-01

    We demonstrated a high-power ultralong-wavelength Tm-doped silica fiber laser operating at 2153 nm with the output power exceeding 18 W and the slope efficiency of 25.5%. A random distributed feedback fiber laser with the center wavelength of 1173 nm was employed as pump source of Tm-doped fiber laser for the first time. No amplified spontaneous emissions or parasitic oscillations were observed when the maximum output power reached, which indicates that employing 1173 nm random distributed feedback fiber laser as pump laser is a feasible and promising scheme to achieve high-power emission of long-wavelength Tm-doped fiber laser. The output power of this Tm-doped fiber laser could be further improved by optimizing the length of active fiber, reflectivity of FBGs, increasing optical efficiency of pump laser and using better temperature management. We also compared the operation of 2153 nm Tm-doped fiber lasers pumped with 793 nm laser diodes, and the maximum output powers were limited to ~2 W by strong amplified spontaneous emission and parasitic oscillation in the range of 1900-2000 nm.

  3. High-power ultralong-wavelength Tm-doped silica fiber laser cladding-pumped with a random distributed feedback fiber laser

    PubMed Central

    Jin, Xiaoxi; Du, Xueyuan; Wang, Xiong; Zhou, Pu; Zhang, Hanwei; Wang, Xiaolin; Liu, Zejin

    2016-01-01

    We demonstrated a high-power ultralong-wavelength Tm-doped silica fiber laser operating at 2153 nm with the output power exceeding 18 W and the slope efficiency of 25.5%. A random distributed feedback fiber laser with the center wavelength of 1173 nm was employed as pump source of Tm-doped fiber laser for the first time. No amplified spontaneous emissions or parasitic oscillations were observed when the maximum output power reached, which indicates that employing 1173 nm random distributed feedback fiber laser as pump laser is a feasible and promising scheme to achieve high-power emission of long-wavelength Tm-doped fiber laser. The output power of this Tm-doped fiber laser could be further improved by optimizing the length of active fiber, reflectivity of FBGs, increasing optical efficiency of pump laser and using better temperature management. We also compared the operation of 2153 nm Tm-doped fiber lasers pumped with 793 nm laser diodes, and the maximum output powers were limited to ~2 W by strong amplified spontaneous emission and parasitic oscillation in the range of 1900–2000 nm. PMID:27416893

  4. Paper surface modification by lasers

    NASA Astrophysics Data System (ADS)

    Zekou, E.; Kotsifaki, D. G.; Serafetinides, A. A.

    2010-10-01

    Lasers can provide a precious tool to conservation process due to their accuracy and the controlled energy they deliver, especially to fragile organic material such as paper. The current study concerns laser modification such as paper cleaning, initially of test papers artificially soiled and then of an original book of the early 20th Century. The test objects were A4 copier paper, newspaper, and paper Whatman No.1056. During the experiments, ink of a pen, pencil and ink from a stamp was mechanically employed on each paper surface. Laser cleaning was applied using a Q-switched Nd:YAG operating at 532 nm and CO2 laser at 10.6 μm for various fluences. The experimental results were presented by using optical microscopy. Eventually, laser cleaning of ink was performed to a book of 1934, by choosing the best conditions and parameters from cleaning the test samples, like Nd:YAG laser operating at 532 nm.

  5. Thulium fiber laser lithotripsy in an in vitro ureter model

    NASA Astrophysics Data System (ADS)

    Hardy, Luke A.; Wilson, Christopher R.; Irby, Pierce B.; Fried, Nathaniel M.

    2014-12-01

    Using a validated in vitro ureter model for laser lithotripsy, the performance of an experimental thulium fiber laser (TFL) was studied and compared to the clinical gold standard holmium:YAG laser. The holmium laser (λ=2120 nm) was operated with standard parameters of 600 mJ, 350 μs, 6 Hz, and 270-μm-core optical fiber. The TFL (λ=1908 nm) was operated with 35 mJ, 500 μs, 150 to 500 Hz, and a 100-μm-core fiber. Urinary stones (60% calcium oxalate monohydrate/40% calcium phosphate) of uniform mass and diameter (4 to 5 mm) were laser ablated with fibers through a flexible video-ureteroscope under saline irrigation with flow rates of 22.7 and 13.7 ml/min for the TFL and holmium laser, respectively. The temperature 3 mm from the tube's center and 1 mm above the mesh sieve was measured by a thermocouple and recorded throughout each experiment for both lasers. Total laser and operation times were recorded once all stone fragments passed through a 1.5-mm sieve. The holmium laser time measured 167±41 s (n=12). TFL times measured 111±49, 39±11, and 23±4 s, for pulse rates of 150, 300, and 500 Hz, respectively (n=12 each). Mean peak saline irrigation temperatures reached 24±1°C for holmium, and 33±3°C, 33±7°C, and 39±6°C, for TFL at pulse rates of 150, 300, and 500 Hz, respectively. To avoid thermal buildup and provide a sufficient safety margin, TFL lithotripsy should be performed with pulse rates below 500 Hz and/or increased saline irrigation rates. The TFL rapidly fragmented kidney stones due in part to its high pulse rate, high power density, high average power, and observation of reduced stone retropulsion and may provide a clinical alternative to the conventional holmium laser for lithotripsy.

  6. Thulium fiber laser lithotripsy in an in vitro ureter model.

    PubMed

    Hardy, Luke A; Wilson, Christopher R; Irby, Pierce B; Fried, Nathaniel M

    2014-12-01

    Using a validated in vitro ureter model for laser lithotripsy, the performance of an experimental thulium fiber laser (TFL) was studied and compared to the clinical gold standard holmium:YAG laser. The holmium laser (λ = 2120 nm) was operated with standard parameters of 600 mJ, 350 μs, 6 Hz, and 270-μm-core optical fiber. The TFL (λ=1908 nm) was operated with 35 mJ, 500 μs, 150 to 500 Hz, and a 100-μm-core fiber. Urinary stones (60% calcium oxalate monohydrate/40% calcium phosphate) of uniform mass and diameter (4 to 5 mm) were laser ablated with fibers through a flexible video-ureteroscope under saline irrigation with flow rates of 22.7 and 13.7 ml/ min for the TFL and holmium laser, respectively. The temperature 3 mm from the tube's center and 1 mm above the mesh sieve was measured by a thermocouple and recorded throughout each experiment for both lasers. Total laser and operation times were recorded once all stone fragments passed through a 1.5-mm sieve. The holmium laser time measured 167±41 s (n=12). TFL times measured 111±49, 39±11, and 23±4 s, for pulse rates of 150, 300, and 500 Hz, respectively (n=12 each). Mean peak saline irrigation temperatures reached 24±1°C for holmium, and 33±3°C, 33±7°C, and 39±6°C, for TFL at pulse rates of 150, 300, and 500 Hz, respectively. To avoid thermal buildup and provide a sufficient safety margin, TFL lithotripsy should be performed with pulse rates below 500 Hz and/or increased saline irrigation rates. The TFL rapidly fragmented kidney stones due in part to its high pulse rate, high power density, high average power, and observation of reduced stone retropulsion and may provide a clinical alternative to the conventional holmium laser for lithotripsy.

  7. Fiber optic confocal laser Doppler velocimeter using an all-fiber laser source for high resolution measurements.

    PubMed

    Sharma, Utkarsh; Chen, Gang; Kang, Jin; Ilev, Ilko; Waynant, Ronald

    2005-08-08

    We demonstrate and analyze a novel fiber optic confocal laser Doppler velocimeter using an ultra-narrow linewidth all-fiber laser source centered at around 1550 nm (eye-safe region). The narrow spectral linewidth of the fiber laser (<10 kHz) is used to achieve an extremely high velocity resolution (~0.0075 m/s), which is an order of magnitude better as compared to the commonly used semiconductor diode lasers or He-Ne lasers based systems. The directional optical circulator based design used in our system is much simpler to implement and is power conserving compared to the conventional Michelson interferometer based designs. We perform Gaussian beam propagation analysis by using the ABCD law to study the performance of the confocal design. The analysis is in good accord with our experimental results. The confocal design is capable of providing ultrahigh spatial resolution (~5microm, in both lateral and longitudinal directions) for high-precision velocity distribution measurement applications.

  8. Stimulated Brillouin Scattering Suppression in Fiber Amplifiers via Chirped Diode Lasers

    DTIC Science & Technology

    2011-09-01

    acousto- optic frequency shifters‡ ( 3 ). Coherent combination of 10 single-mode fiber lasers could then yield a robust, efficient, diffraction-limited 100... kW source. Long-distance fiber telecommunications are also adversely affected by SBS. In this case, the laser cannot be chirped without distorting...in fiber length. 3 1.5µ ChDL AOFS PLL ErFA Figure 1. Chirped diode laser seeding one or more Er fiber amplifiers, each preceded by an AOFS

  9. All-fiber nonlinearity- and dispersion-managed dissipative soliton nanotube mode-locked laser

    SciTech Connect

    Zhang, Z.; Popa, D. Wittwer, V. J.; Milana, S.; Hasan, T.; Jiang, Z.; Ferrari, A. C.; Ilday, F. Ö.

    2015-12-14

    We report dissipative soliton generation from an Yb-doped all-fiber nonlinearity- and dispersion-managed nanotube mode-locked laser. A simple all-fiber ring cavity exploits a photonic crystal fiber for both nonlinearity enhancement and dispersion compensation. The laser generates stable dissipative solitons with large linear chirp in the net normal dispersion regime. Pulses that are 8.7 ps long are externally compressed to 118 fs, outperforming current nanotube-based Yb-doped fiber laser designs.

  10. All-fiber nonlinearity- and dispersion-managed dissipative soliton nanotube mode-locked laser

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Popa, D.; Wittwer, V. J.; Milana, S.; Hasan, T.; Jiang, Z.; Ferrari, A. C.; Ilday, F. Ö.

    2015-12-01

    We report dissipative soliton generation from an Yb-doped all-fiber nonlinearity- and dispersion-managed nanotube mode-locked laser. A simple all-fiber ring cavity exploits a photonic crystal fiber for both nonlinearity enhancement and dispersion compensation. The laser generates stable dissipative solitons with large linear chirp in the net normal dispersion regime. Pulses that are 8.7 ps long are externally compressed to 118 fs, outperforming current nanotube-based Yb-doped fiber laser designs.

  11. Reflection Effects in Multimode Fiber Systems Utilizing Laser Transmitters

    NASA Technical Reports Server (NTRS)

    Bates, Harry E.

    1991-01-01

    A number of optical communication lines are now in use at NASA-Kennedy for the transmission of voice, computer data, and video signals. Now, all of these channels use a single carrier wavelength centered near 1300 or 1550 nm. Engineering tests in the past have given indications of the growth of systematic and random noise in the RF spectrum of a fiber network as the number of connector pairs is increased. This noise seems to occur when a laser transmitter is used instead of a LED. It has been suggested that the noise is caused by back reflections created at connector fiber interfaces. Experiments were performed to explore the effect of reflection on the transmitting laser under conditions of reflective feedback. This effort included computer integration of some of the instrumentation in the fiber optic lab using the Lab View software recently acquired by the lab group. The main goal was to interface the Anritsu Optical and RF spectrum analyzers to the MacIntosh II computer so that laser spectra and network RF spectra could be simultaneously and rapidly acquired in a form convenient for analysis. Both single and multimode fiber is installed at Kennedy. Since most are multimode, this effort concentrated on multimode systems.

  12. Developing high energy dissipative soliton fiber lasers at 2 micron

    PubMed Central

    Huang, Chongyuan; Wang, Cong; Shang, Wei; Yang, Nan; Tang, Yulong; Xu, Jianqiu

    2015-01-01

    While the recent discovered new mode-locking mechanism - dissipative soliton - has successfully improved the pulse energy of 1 μm and 1.5 μm fiber lasers to tens of nanojoules, it is still hard to scale the pulse energy at 2 μm due to the anomalous dispersion of the gain fiber. After analyzing the intracavity pulse dynamics, we propose that the gain fiber should be condensed to short lengths in order to generate high energy pulse at 2 μm. Numerical simulation predicts the existence of stable 2 μm dissipative soliton solutions with pulse energy over 10 nJ, comparable to that achieved in the 1 μm and 1.5 μm regimes. Experimental operation confirms the validity of the proposal. These results will advance our understanding of mode-locked fiber lasers at different wavelengths and lay an important step in achieving high energy ultrafast laser pulses from anomalous dispersion gain media. PMID:26348563

  13. Random distributed feedback Raman fiber laser with polarized pumping

    NASA Astrophysics Data System (ADS)

    Wu, H.; Wang, Z. N.; Churkin, D. V.; Vatnik, I. D.; Fan, M. Q.; Rao, Y. J.

    2015-01-01

    In this letter, the polarization properties of a random fiber laser operating via Raman gain and random distributed feedback owing to Rayleigh scattering are investigated for the first time. Using polarized pump, the partially polarized generation is obtained with a generation spectrum exhibiting discrete narrow spectral features contrary to the smooth spectrum observed for the depolarized pump. The threshold, output power, degree of polarization and the state of polarization (SOP) of the lasing can be significantly influenced by the SOP of the pump. Fine narrow spectral components are also sensitive to the SOP of the pump wave. Furthermore, we found that random lasing’s longitudinal power distributions are different in the case of polarized and depolarized pumping that results in considerable reduction of the generation slope efficiency for the polarized radiation. Our results indicate that polarization effects play an important role on the performance of the random fiber laser. This work improves the understanding of the physics of random lasing in fibers and makes a step forward towards the establishment of the vector model of random fiber lasers.

  14. Transendoscopic soft-tissue laser ablation in the equine upper respiratory tract

    NASA Astrophysics Data System (ADS)

    Bartels, K. E.; MacAllister, C. G.; Dickey, D. T.; Schafer, S. A.; Nordquist, R. E.

    1997-05-01

    Transendoscopic application of Nd:YAG laser energy for treatment of partial upper respiratory obstruction in the horse has been practiced for the last 12 years in both contact and non-contact modes. Endoscopic laser ablation has been limited to wavelengths transmitted through flexible optical fibers. Devices used for this purpose have been primarily the Nd:YAG (1064 nm), KTP (532 nm), holmium (2100 nm), and diode (805 nm) lasers. Few investigations have focused on use of the holmium or diode lasers. Objectives of this study were to evaluate use of fiber-deliverable laser wavelengths provided by newer, more portable, user-friendly, solid-state diode and holmium lasers for ablation of laryngeal tissues of the equine upper respiratory tract. In addition, information on efficacy and dosimetry for both the contact and non-contact modes was obtained using an in vitro cadaveric model. Preliminary conclusions based on histologic evaluation and scanning electron microscopy revealed that diode laser energy has the ability to penetrate laryngeal tissue easily and deeply with minimal collateral coagulation, but is sensitive to tissue color. Holmium laser energy can be used to incise laryngeal tissue easily in contact mode with moderate collateral damage, and absorption does not seem dependent on tissue color.

  15. A novel laser angioplasty guided hollow fiber using mid-infrared laser

    NASA Astrophysics Data System (ADS)

    Yoshihashi-Suzuki, Sachiko; Yamada, Shinya; Sato, Izuru; Awazu, Kunio

    2006-02-01

    We have proposed selective removal of cholesterol ester by infrared laser of wavelength with 5.75 μm irradiation; the wavelength of 5.75 μm correspond with the ester bond C=O stretching vibration. The flexible laser guiding line and a compact light source are required for our proposal. We used a compact mid-infrared tunable laser by difference frequency generation; DFG laser was developed for substitute light source of free electron laser. In the present work, first, we have developed hollow optical fiber with a diamond lens-tip to deliver DFG laser in the blood vessel and evaluated the transmission of DFG laser from 5.5 μm to 7.5 μm. The transmission of 5.75 μm is about 65%, the DFG beam was focused on the tip of fiber by diamond lens-tip. Secondly, we performed the selective removal experiment of cholesterol ester using the hollow optical fiber with diamond lens-tip and DFG laser. The sample used a two layer model, cholesterol oleate and gelatin. The cholesterol oleate was decomposed by 5.75 μm DFG irradiation with 3.8 W/cm2.

  16. High-power pulsed and CW diode-pumped mode-locked Nd:YAG lasers

    NASA Technical Reports Server (NTRS)

    Marshall, Larry R.; Hays, A. D.; Kaz, Alex; Kasinski, Jeff; Burnham, R. L.

    1991-01-01

    The operation of both pulsed and CW diode-pumped mode-locked Nd:YAG lasers are presented. The pulsed laser produced 1.0 mJ with pulsewidths of 90 psec at 20 Hz. The CW pumped laser produced 6 W output at 1.064 microns and 3 W output at 532 nm.

  17. State of the art of compact green lasers for mobile projectors

    NASA Astrophysics Data System (ADS)

    Essaian, Stepan; Khaydarov, John

    2012-11-01

    We report on progress in development of the low-cost, highly efficient miniature diode-pumped solid-state (DPSS) green laser sources for pico-projectors and other consumer electronics applications with wavelength 532 nm. As Spectralus laser has monolithic microchip structure there are other green lasers with various discrete designs. We are reviewing both approaches in this paper.

  18. High-brightness 800nm fiber-coupled laser diodes

    NASA Astrophysics Data System (ADS)

    Berk, Yuri; Levy, Moshe; Rappaport, Noam; Tessler, Renana; Peleg, Ophir; Shamay, Moshe; Yanson, Dan; Klumel, Genadi; Dahan, Nir; Baskin, Ilya; Shkedi, Lior

    2014-03-01

    Fiber-coupled laser diodes have become essential sources for fiber laser pumping and direct energy applications. Single emitters offer reliable multi-watt output power from a 100 m lateral emission aperture. By their combination and fiber coupling, pump powers up to 100 W can be achieved from a low-NA fiber pigtail. Whilst in the 9xx nm spectral range the single emitter technology is very mature with <10W output per chip, at 800nm the reliable output power from a single emitter is limited to 4 W - 5 W. Consequently, commercially available fiber coupled modules only deliver 5W - 15W at around 800nm, almost an order of magnitude down from the 9xx range pumps. To bridge this gap, we report our advancement in the brightness and reliability of 800nm single emitters. By optimizing the wafer structure, laser cavity and facet passivation process we have demonstrated QCW device operation up to 19W limited by catastrophic optical damage to the 100 μm aperture. In CW operation, the devices reach 14 W output followed by a reversible thermal rollover and a complete device shutdown at high currents, with the performance fully rebounded after cooling. We also report the beam properties of our 800nm single emitters and provide a comparative analysis with the 9xx nm single emitter family. Pump modules integrating several of these emitters with a 105 μm / 0.15 NA delivery fiber reach 35W in CW at 808 nm. We discuss the key opto-mechanical parameters that will enable further brightness scaling of multi-emitter pump modules.

  19. Latest development of high-power fiber lasers in SPI

    NASA Astrophysics Data System (ADS)

    Norman, Stephen; Zervas, Mikhail N.; Appleyard, Andrew; Durkin, Michael K.; Horley, Ray; Varnham, Malcolm P.; Nilsson, Johan; Jeong, Yoonchan

    2004-06-01

    High Power Fiber Lasers (HPFLs) and High Power Fiber Amplifiers (HPFAs) promise a number of benefits in terms of their high optical efficiency, degree of integration, beam quality, reliability, spatial compactness and thermal management. These benefits are driving the rapid adoption of HPFLs in an increasingly wide range of applications and power levels ranging from a few Watts, in for example analytical applications, to high-power >1kW materials processing (machining and welding) applications. This paper describes SPI"s innovative technologies, HPFL products and their performance capabilities. The paper highlights key aspects of the design basis and provides an overview of the applications space in both the industrial and aerospace domains. Single-fiber CW lasers delivering 1kW output power at 1080nm have been demonstrated and are being commercialized for aerospace and industrial applications with wall-plug efficiencies in the range 20 to 25%, and with beam parameter products in the range 0.5 to 100 mm.mrad (corresponding to M2 = 1.5 to 300) tailored to application requirements. At power levels in the 1 - 200 W range, SPI"s proprietary cladding-pumping technology, GTWaveTM, has been employed to produce completely fiber-integrated systems using single-emitter broad-stripe multimode pump diodes. This modular construction enables an agile and flexible approach to the configuration of a range of fiber laser / amplifier systems for operation in the 1080nm and 1550nm wavelength ranges. Reliability modeling is applied to determine Systems martins such that performance specifications are robustly met throughout the designed product lifetime. An extensive Qualification and Reliability-proving programme is underway to qualify the technology building blocks that are utilized for the fiber laser cavity, pump modules, pump-driver systems and thermo-mechanical management. In addition to the CW products, pulsed fiber lasers with pulse energies exceeding 1mJ with peak pulse

  20. Femtosecond laser inscription of asymmetric directional couplers for in-fiber optical taps and fiber cladding photonics.

    PubMed

    Grenier, Jason R; Fernandes, Luís A; Herman, Peter R

    2015-06-29

    Precise alignment of femtosecond laser tracks in standard single mode optical fiber is shown to enable controllable optical tapping of the fiber core waveguide light with fiber cladding photonic circuits. Asymmetric directional couplers are presented with tunable coupling ratios up to 62% and bandwidths up to 300 nm at telecommunication wavelengths. Real-time fiber monitoring during laser writing permitted a means of controlling the coupler length to compensate for micron-scale alignment errors and to facilitate tailored design of coupling ratio, spectral bandwidth and polarization properties. Laser induced waveguide birefringence was harnessed for polarization dependent coupling that led to the formation of in-fiber polarization-selective taps with 32 dB extinction ratio. This technology enables the interconnection of light propagating in pre-existing waveguides with laser-formed devices, thereby opening a new practical direction for the three-dimensional integration of optical devices in the cladding of optical fibers and planar lightwave circuits.

  1. Study of laser-induced damage to large core silica fiber by Nd:YAG and Alexandrite lasers

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoguang; Li, Jie; Hokansson, Adam; Whelan, Dan; Clancy, Michael

    2009-02-01

    As a continuation of our earlier study at 2.1 μm wavelength, we have investigated the laser damage to several types of step-index, large core (1500 μm) silica fibers at two new wavelengths by high power long pulsed Nd:YAG (1064 nm) and Alexandrite (755 nm) lasers. It was observed that fibers with different designs showed a significant difference in performance at these wavelengths. We will also report a correlation of damage to the fibers between the two laser wavelengths. The performance analyses of different fiber types under the given test conditions will enable optimization of fiber design for specific applications.

  2. Sub-100 fs mode-locked erbium-doped fiber laser using a 45°-tilted fiber grating.

    PubMed

    Zhang, Zuxing; Mou, Chengbo; Yan, Zhijun; Zhou, Kaiming; Zhang, Lin; Turitsyn, Sergei

    2013-11-18

    We demonstrate generation of sub-100 fs pulses at 1.5 µm in a mode-locked erbium-doped fiber laser using a 45°-tilted fiber grating element. The laser features a genuine all-fiber configuration. Based on the unique polarization properties of the 45°-tilted fiber grating, we managed to produce sub-100 fs laser pulses through proper dispersion management. To the best of our knowledge, this is the shortest pulse generated from mode-locked lasers with fiber gratings. The output pulse has an average power of 8 mW, with a repetition rate of 47.8 MHz and pulse energy of 1.68 nJ. The performance of laser also matches well the theoretical simulations.

  3. Brillouin-Erbium fiber laser with enhanced feedback coupling using common Erbium gain section.

    PubMed

    Samsuri, N M; Zamzuri, A K; Al-Mansoori, M H; Ahmad, A; Mahdi, M A

    2008-10-13

    We demonstrate an enhanced architecture of Brillouin-Erbium fiber laser utilizing the reverse-S-shaped fiber section as the coupling mechanism. The enhancement is made by locating a common section of Erbium-doped fiber next to the single-mode fiber to amplify the Brillouin pumps and the oscillating Stokes lines. The requirement of having two Erbium gain sections to enhance the multiple Brillouin Stokes lines generation is neglected by the proposed fiber laser structure. The mode competitions arise from the self-lasing cavity modes of the fiber laser are efficiently suppressed by the stronger pre-amplified Brillouin pump power before entering the single mode fiber section. The maximum output power of 20 mW is obtained from the proposed fiber laser with 10 laser lines that equally separated by 0.089 nm spacing.

  4. Towards high-quality optical ceramic YAG fibers for high-energy laser (HEL) applications

    NASA Astrophysics Data System (ADS)

    Lee, HeeDong; Keller, Kristin; Sirn, Brian

    2012-06-01

    There is a critical demand for high quality, transparent ceramic YAG fibers for high powered fiber lasers. The production of laser quality ceramic fibers hinges on advanced ceramic processing technology, along with the availability of highly sinterable powder with high phase and chemical purity. These two fundamental technologies have been successfully developed at UES. Nd (1.1 a/o) and Yb (1.0 a/o)-doped yttrium aluminum garnet (YAG) fibers with high optical quality were produced by combining UES's tailored powders with advanced consolidation processes including fiber extrusion and vacuum sintering. The as-sintered and as-annealed fibers, approximately 30 microns in diameter, appeared transparent and successfully transmitted laser beams; further development will allow for the production of doped ceramic YAG fiber lasers for advanced high power and high energy fiber laser systems.

  5. Soliton generation from an actively mode-locked fiber laser incorporating an electro-optic fiber modulator.

    PubMed

    Malmström, Mikael; Margulis, Walter; Tarasenko, Oleksandr; Pasiskevicius, Valdas; Laurell, Fredrik

    2012-01-30

    This work demonstrates an actively mode-locked fiber laser operating in soliton regime and employing an all-fiber electro-optic modulator. Nonlinear polarization rotation is utilized for femtosecond pulse generation. Stable operation of the all-fiber ring laser is readily achieved at a fundamental repetition rate of 2.6 MHz and produces 460 fs pulses with a spectral bandwidth of 5.3 nm.

  6. Laparoscopic Partial Nephrectomy Using a Flexible CO2 Laser Fiber

    PubMed Central

    Khalaileh, Abed; Ponomarenko, Oleg; Abu-Gazala, Mahmoud; Lewinsky, Reuven M.; Elazary, Ram; Shussman, Noam; Shalhav, Arieh; Mintz, Yoav

    2012-01-01

    Background and Objectives: Laparoscopic partial nephrectomy (LPN) is a challenging surgery that requires precise tissue cutting and meticulous hemostasis under warm ischemia conditions. In this study, we tested the feasibility of performing LPN using CO2 laser energy transmitted through a specialized flexible mirror optical fiber. Methods: General anesthesia and pneumoperitoneum were induced in 7 farm pigs. Various portions of a kidney, either a pole or a midportion of the kidney, were removed using a novel flexible fiber to transmit CO2 laser energy set at a power of 45W and energy per pulse of 100mJ. The collecting system was approximated with a suture or 2, but no hemostatic measures were taken besides applying a few pulses of the laser to bleeding points. The pigs were sacrificed 3 wk later. Results: Average renal mass removed was 18% of the total kidney weight. All pigs tolerated surgery well. Sharp renal cutting was accomplished in a single continuous incision, with minimal tissue charring and minimal blood loss (<10cc) in all animals. Necropsy revealed no peritoneal or retroperitoneal abnormalities. Histologic examination of the cut surface showed a thin sector of up to 100 μm of coagulation necrosis. Conclusions: We report on the first LPN done using a CO2 laser transmitted through a flexible fiber in an animal model. This novel application of the CO2 laser produced excellent parenchymal incision and hemostasis along with minimal damage to adjacent renal tissue, thus, potentially shortening ischemia time and kidney function loss. Further studies comparing this laser to standard technique are necessary to verify its usefulness for partial nephrectomy. PMID:23484569

  7. Hollow light guide and optical fiber for UV laser transmission

    NASA Astrophysics Data System (ADS)

    Kubo, Uichi; Hashishin, Yuichi; Nakano, Hitoshi; Tanaka, Hiroyuki

    1997-12-01

    The applications of ultraviolet lasers in medicine and surgery are expected to produce new therapies since UV laser is strongly absorbed by lipids, proteins and nucleic acids. The suitable tools for the UV laser power delivery, however, have not been developed yet. In an effort to make efficient delivery of UV laser, we have proposed hollow light guide which consists of an aluminum-phosphor bronze reflector and a teflon E-type rail spacer. The delivery characteristics of the hollow light guide have been investigated using the ArF and KrF excimer lasers. In case of the KrF laser, the transmittance and delivery energy reached 77%/m and 110 mJ/pulse, respectively. In the ArF laser, the transmittance and delivery energy were obtained to be 56%/m and 40 mJ/pulse, respectively. It is known that 193 nm radiation by the ArF laser are absorbed by the air. Thus, the ArF laser beam delivery were examined in the helium gas. The transmittance and the delivery energy were obtained to be 72%/m and 50 mJ/pulse using helium-filled hollow light guide, which were greatly improved for comparison with the case of the air. We have also tried the quartz fiber with OH ion doped core. The effects of a lightly doped core with Cl and a clad with B-F on the laser transmittance have been investigated. In these result, the Cl was not good core dopant. The B and F were useful clad dopants for the excimer laser transmission.

  8. Hollow light guide and optical fiber for UV laser transmission

    NASA Astrophysics Data System (ADS)

    Kubo, Uichi; Hashishin, Yuichi; Nakano, Hitoshi; Tanaka, Hiroyuki

    1998-01-01

    The applications of ultraviolet lasers in medicine and surgery are expected to produce new therapies since UV laser is strongly absorbed by lipids, proteins and nucleic acids. The suitable tools for the UV laser power delivery, however, have not been developed yet. In an effort to make efficient delivery of UV laser, we have proposed hollow light guide which consists of an aluminum-phosphor bronze reflector and a teflon E-type rail spacer. The delivery characteristics of the hollow light guide have been investigated using the ArF and KrF excimer lasers. In case of the KrF laser, the transmittance and delivery energy reached 77%/m and 110 mJ/pulse, respectively. In the ArF laser, the transmittance and delivery energy were obtained to be 56%/m and 40 mJ/pulse, respectively. It is known that 193 nm radiation by the ArF laser are absorbed by the air. Thus, the ArF laser beam delivery were examined in the helium gas. The transmittance and the delivery energy were obtained to be 72%/m and 50 mJ/pulse using helium-filled hollow light guide, which were greatly improved for comparison with the case of the air. We have also tried the quartz fiber with OH ion doped core. The effects of a lightly doped core with Cl and a clad with B-F on the laser transmittance have been investigated. In these result, the Cl was not good core dopant. The B and F were useful clad dopants for the excimer laser transmission.

  9. Stable multi-wavelength fiber lasers for temperature measurements using an optical loop mirror.

    PubMed

    Diaz, Silvia; Socorro, Abian Bentor; Martínez Manuel, Rodolfo; Fernandez, Ruben; Monasterio, Ioseba

    2016-10-10

    In this work, two novel stable multi-wavelength fiber laser configurations are proposed and demonstrated by using a spool of a single-mode fiber as an optical loop mirror and one or two fiber ring cavities, respectively. The lasers are comprised of fiber Bragg grating reflectors as the oscillation wavelength selecting filters. The influence of the length of the spool of fiber on the laser stability both in terms of wavelength and laser output power was investigated. An application for temperature measurement is also shown.

  10. Endometrial ablation using SideFire laser fiber

    NASA Astrophysics Data System (ADS)

    Everett, Royice B.

    1996-05-01

    The first successful report using the neodymium:yttrium-aluminum-garnet (Nd:YAG) Laser to control hypermenorrhea was reported in 1981. Variations on the treatment technique have been attempted to improve the amenorrhea rate. Reports using the Nd:YAG laser with the blanching or non-touch technique seem to result in a better outcome and higher rate of total amenorrhea than using the dragging technique. Due to the report of improved rates of amenorrhea when using the blanching technique and the Nd:YAG laser, a fiber was developed to direct the laser energy at right angles to the axis of the fiber, therefore allowing a total treatment of the entire uterus in a perpendicular fashion. The theoretic benefit of this would be a more complete and predictable destruction of the endometrial lining, avoiding fluid overload by coagulating and sealing of the vessels and lymphatic. After a follow-up of 12 to 36 months, 56 of the 60 patients (93%) who underwent complete endometrial ablation with the SideFireTM technique had excellent results. Total absolute amenorrhea resulted in 50 patients (83%). Contrary to earlier reports, using the rollerball electrode, this procedure technique resulted in no decrease in results in younger patients. In conclusion, this seems to be a reasonable alternative which offers improved results when compared to previously available methods using electrosurgery or the Nd:YAG laser without the use of the SideFireTM device.

  11. Successive soliton explosions in an ultrafast fiber laser.

    PubMed

    Liu, Meng; Luo, Ai-Ping; Yan, Yu-Rong; Hu, Song; Liu, Yi-Chen; Cui, Hu; Luo, Zhi-Chao; Xu, Wen-Cheng

    2016-03-15

    Soliton explosions, as one of the most fascinating nonlinear phenomena in dissipative systems, have been investigated in different branches of physics, including the ultrafast laser community. Herein, we reported on the soliton dynamics of an ultrafast fiber laser from steady state to soliton explosions, and to huge explosions by simply adjusting the pump power level. In particular, the huge soliton explosions show that the exploding behavior could operate in a sustained, but periodic, mode from one explosion to another, which we term as "successive soliton explosions." The experimental results will prove to be fruitful to the various communities interested in soliton explosions.

  12. Power scaling of high-efficiency 1.5 μm cascaded Raman fiber lasers.

    PubMed

    Supradeepa, V R; Nicholson, Jeffrey W

    2013-07-15

    High-power fiber lasers operating at the 1.5 μm wavelength region have attractive features, such as eye safety and atmospheric transparency, and cascaded Raman fiber lasers offer a convenient method to obtain high-power sources at these wavelengths. A limitation to power scaling, however, has been the lower conversion efficiency of these lasers. We recently introduced a high-efficiency architecture for high-power cascaded Raman fiber lasers applicable for 1.5 μm fiber lasers. Here we demonstrate further power scaling using this new architecture. Using numerical simulations, we identify the ideal operating conditions for the new architecture. We demonstrate a high-efficiency 1480 nm cascaded Raman fiber laser with an output power of 301 W, comparable to record power levels achieved with rare-earth-doped fiber lasers in the 1.5 μm wavelength region.

  13. Switchable dual-wavelength fiber laser based on PCF Sagnac loop and broadband FBG

    NASA Astrophysics Data System (ADS)

    Chen, Weiguo; Lou, Shuqin; Feng, Suchun; Wang, Liwen; Li, Honglei; Guo, Tieying; Jian, Shuisheng

    2009-11-01

    Switchable dual-wavelength fiber laser with photonic crystal fiber (PCF) Sagnac loop and broadband fiber Bragg grating (BFBG) at room temperature is demonstrated. By adjusting the polarization controller (PC) appropriately, the laser can be switched between the stable single- and dual-wavelength lasing operations by exploiting polarization hole burning (PHB) and spectral hole burning effects (SHB).

  14. A compact and high efficiency diode pumped green laser based on MgO doped PPLN

    NASA Astrophysics Data System (ADS)

    Zheng, X. S.; Ji, B.; Jia, F. Q.; Cai, Z. P.; Xu, H. Y.; Xu, C. Q.

    2011-11-01

    In this work, an efficient intra-cavity second harmonic generation of green laser in a periodically poled MgO doped LiNbO3 (MgO:PPLN) bulk crystal using a compact Nd:YVO4 laser as a fundamental laser source is reported. Different length, different working temperature MgO:PPLN crystals are tested and investigated in the SHG experiments. The maximum output power at 532 nm is 6.2 W at the absorbed pump power at 808 nm of 14 W, the optical to optical conversion efficiencies from 808 to 532 nm and 1064 to 532 nm are 43 and 77%, respectively, the instability in 2 hours is less than 5%.

  15. Actively mode-locked fiber laser using acousto-optic modulator

    NASA Astrophysics Data System (ADS)

    Nikodem, Michal P.; Sergeant, Hendrik; Kaczmarek, Pawel; Abramski, Krzysztof M.

    2008-12-01

    In recent years we have observed growing interest in mode-locked fiber lasers. Development of erbium doped fiber (EDF) amplifiers and WDM technique made 3rd telecommunication window extremely interesting region for ultrafast optics. The main advantages of fiber lasers i.e. narrow linewidth and wide gain bandwidth make them very attractive sources in various applications. In this paper we present an actively mode-locked erbium doped fiber ring laser. Modelocking is obtained using an acousto-optic modulator (AOM) coupled into the laser cavity. The impact of different parameters (e.g. light polarization, modulation frequency) is investigated. We study mechanisms of controlling the wavelength of the laser.

  16. Generation of 8 nJ pulses from a normal-dispersion thulium fiber laser.

    PubMed

    Tang, Yuxing; Chong, Andy; Wise, Frank W

    2015-05-15

    We report a study of a mode-locked thulium (Tm) fiber laser with varying normal dispersion. It is difficult to reach the high-energy dissipative-soliton regime due to the anomalous dispersion of most fibers at 2 μm. With large normal dispersion, the laser exhibits elements of self-similar pulse evolution, and is the first Tm fiber laser to achieve the performance benefits of normal-dispersion operation. The laser generates 7.6 nJ pulses, which can be dechirped to 130 fs duration. The resulting peak power is 4 times higher than that of previous Tm fiber lasers.

  17. Flexible pulses from carbon nanotubes mode-locked fiber laser

    NASA Astrophysics Data System (ADS)

    Yang, Ling-Zhen; Yang, Yi; Wang, Juan-Fen

    2016-12-01

    We demonstrate a flexible erbium-doped pulsed fiber laser which achieves the wavelength and pulse width tuning by adjusting an intracavity filter. The intracavity filter is flexible to achieve any of the different wavelengths and bandwidths in the tuning range. The wavelength and width of pulse can be tuned in a range of ˜ 20 nm and from ˜ 0.8 ps to 87 ps, respectively. The flexible pulsed fiber laser can be accurately controlled, which is insensitive to environmental disturbance. Project supported by the National Natural Science Foundation of China (Grant No. 61575137) and the Program on Social Development by Department of Science and Technology of Shanxi Province, China (Grant No. 20140313023-3).

  18. Fiber laser hydrophone for low frequency signal detection

    NASA Astrophysics Data System (ADS)

    Zhang, Wentao; Li, Fang; Liu, Yuliang

    2012-02-01

    A fiber laser hydrophone (FLH) based on a flat diaphragm and an L shaped lever is presented. This hydrophone uses an L shaped lever to transfer the acoustic pressure induced defection of the flat diaphragm to the axial elongation of the fiber laser. The curve where the L shaped lever contacts the diaphragm is a segment of an Archimedes spiral, which is used to enhance the responsivity. To compensate the hydrostatic pressure, a capillary tube is fixed at the end of the hydrophone. Both theoretical and experimental investigations are presented in this paper. The result shows that the proposed design has a high sensitivity of a flat frequency response below 1 kHz.

  19. Investigation on a pressure-gradient fiber laser hydrophone

    NASA Astrophysics Data System (ADS)

    Zhang, Wentao; Zhang, Faxiang; Li, Fang; Liu, Yuliang

    2010-09-01

    In this paper, a pressure-gradient fiber laser hydrophone is demonstrated. Two brass diaphragms are installed at the end of a metal cylinder as sensing elements. A distributed feedback fiber laser, fixed at the center of the two diaphragms, is elongated or shortened due to the acoustic wave. There are two orifices at the middle of the cylinder. So this structure can work as a pressure-gradient microphone in the acoustic field. Furthermore, the hydrostatic pressure is self-compensated and an ultra-thin dimension is achieved. Theoretical analysis is given based on the electro-acoustic theory. Field trials are carried out to test the performance of the hydrophone. A sensitivity of 100 nm MPa-1 has been achieved. Due to the small dimensions, no directivity is found in the test.

  20. Multi-meter fiber-delivery and pulse self-compression of milli-Joule femtosecond laser and fiber-aided laser-micromachining.

    PubMed

    Debord, B; Alharbi, M; Vincetti, L; Husakou, A; Fourcade-Dutin, C; Hoenninger, C; Mottay, E; Gérôme, F; Benabid, F

    2014-05-05

    We report on damage-free fiber-guidance of milli-Joule energy-level and 600-femtosecond laser pulses into hypocycloid core-contour Kagome hollow-core photonic crystal fibers. Up to 10 meter-long fibers were used to successfully deliver Yb-laser pulses in robustly single-mode fashion. Different pulse propagation regimes were demonstrated by simply changing the fiber dispersion and gas. Self-compression to ~50 fs, and intensity-level nearing petawatt/cm(2) were achieved. Finally, free focusing-optics laser-micromachining was also demonstrated on different materials.

  1. [A universal laser for intraocular treatment].

    PubMed

    Pomerantzeff, O; Vallat, M; Pankratov, M M; Pflibsen, K P; Schepens, C L

    1988-01-01

    The creation of a single apparatus incorporating the different lasers applicable to intraocular pathology derives from the idea of possessing the means, with one device, of objectively comparing the effects and parameters of various lasers in order to pursue a more precise line of treatment. This has led to our fabrication of the universal intraocular laser. The word universal means the ability of the machine to act on each kind of intraocular tissues with all of the various infrared or other-colored radiations, as well as with different modalities. The unit is transportable. It only requires a source of electric power (110 or 220 V) and includes an independent cooling system. The Nd: YAG laser has selectable operating parameters: pulsed or continuous excitation, Q-switched or mode-locked mode, mirror or fiber optic transmission. It is used also as the basic system of the coloured module. The colour module can provide the three clinically useful radiations: green, red, yellow. The green (532 nm) is obtained by transmission of the I.R. beam brought a birefringent crystal (KTP). Red (650 nm) and yellow (575 nm) come from two incorporated dye lasers excited by the green radiation.

  2. Continuous wave laser irradiation of explosives

    SciTech Connect

    McGrane, Shawn D.; Moore, David S.

    2010-12-01

    Quantitative measurements of the levels of continuous wave (CW) laser light that can be safely applied to bare explosives during contact operations were obtained at 532 nm, 785 nm, and 1550 nm wavelengths. A thermal camera was used to record the temperature of explosive pressed pellets and single crystals while they were irradiated using a measured laser power and laser spot size. A visible light image of the sample surface was obtained before and after the laser irradiation. Laser irradiation thresholds were obtained for the onset of any visible change to the explosive sample and for the onset of any visible chemical reaction. Deflagration to detonation transitions were not observed using any of these CW laser wavelengths on single crystals or pressed pellets in the unconfined geometry tested. Except for the photochemistry of DAAF, TATB and PBX 9502, all reactions appeared to be thermal using a 532 nm wavelength laser. For a 1550 nm wavelength laser, no photochemistry was evident, but the laser power thresholds for thermal damage in some of the materials were significantly lower than for the 532 nm laser wavelength. No reactions were observed in any of the studied explosives using the available 300 mW laser at 785 nm wavelength. Tables of laser irradiance damage and reaction thresholds are presented for pressed pellets of PBX9501, PBX9502, Composition B, HMX, TATB, RDX, DAAF, PETN, and TNT and single crystals of RDX, HMX, and PETN for each of the laser wavelengths.

  3. Polarization maintaining linear cavity Er-doped fiber femtosecond laser

    NASA Astrophysics Data System (ADS)

    Jang, Heesuk; Jang, Yoon-Soo; Kim, Seungman; Lee, Keunwoo; Han, Seongheum; Kim, Young-Jin; Kim, Seung-Woo

    2015-10-01

    We present a polarization-maintaining (PM) type of Er-doped fiber linear oscillator designed to produce femtosecond laser pulses with high operational stability. Mode locking is activated using a semiconductor saturable absorber mirror (SESAM) attached to one end of the linear PM oscillator. To avoid heat damage, the SESAM is mounted on a copper-silicon-layered heat sink and connected to the linear oscillator through a fiber buffer dissipating the residual pump power. A long-term stability test is performed to prove that the proposed oscillator design maintains a soliton-mode single-pulse operation without breakdown of mode locking over a week period. With addition of an Er-doped fiber amplifier, the output power is raised to 180 mW with 60 fs pulse duration, from which an octave-spanning supercontinuum is produced.

  4. LD-cladding-pumped 50 pm linewidth Tm 3+ -doped silica fiber laser.

    PubMed

    Yunjun, Zhang; Baoquan, Yao; Youlun, Ju; Hui, Zhou; Yuezhu, Wang

    2008-05-26

    We report on a Tm(3+)-doped fiber laser source operating at 1936.4 nm with a very narrow linewidth (50 pm) laser output. Up to 2.4 W cw laser power was obtained from an 82 cm long Tm(3+)-doped multimode-core fiber cladding pumped by a 792 nm laser diode (LD). The fiber laser cavity included a high-reflective dichroic and a low-reflective FBG output coupler. The multimode fiber Bragg grating (FBG) transmission spectrum and output laser spectrum were measured. By adjusting the distance between the dichroic and the Tm(3+)-doped fiber end, the multipeak laser spectrum changed to a single-peak laser spectrum.

  5. Laser & Fiber Optics: Instructional Manual. The North Dakota High Technology Mobile Laboratory Project.

    ERIC Educational Resources Information Center

    Eickhoff, Luvern R.

    This instructional manual contains 20 learning activity packets for use in a workshop on lasers and fiber optics. The lessons cover the following topics: what a laser; coherent light; setting up the laser; characteristics of the laser beam; scattering of light; laser beam divergence, intensity, color, ophthalmology, and reflections; directivity of…

  6. Fiber-integrated tungsten disulfide saturable absorber (mirror) for pulsed fiber lasers

    NASA Astrophysics Data System (ADS)

    Chen, Hao; Li, Irene Ling; Ruan, Shuangchen; Guo, Tuan; Yan, Peiguang

    2016-08-01

    We propose two schemes for achieving tungsten disulfide (WS2)-based saturable absorber (SA) and saturable absorber mirror (SAM). By utilizing the pulsed laser deposition method, we grow the WS2 film on microfiber to form an evanescent field interaction SA device. Incorporating this SA device into a common ring-cavity erbium-doped fiber (EDF) laser, stably passive mode-locking can be achieved with pulse duration of 395 fs and signal-to-noise ratio of 64 dB. We also produce a fiber tip integrated WS2-SAM by utilizing the magnetron sputtering technique (MST). This new type of SAM combines the WS2 layer as SA and gold mirror as high reflective mirror. By employing the WS2-SAM, we construct the linear-cavity EDF lasers, and achieve passive mode-locking operation with pulse duration of ˜1 ns and SNR of ˜61 dB. We further achieve stably passive Q-switching operation with pulse duration of ˜160 ns and pulse energy of 54.4 nJ. These fiber-integrated SAs and SAMs have merits of compactness and reliability, paving the way for the development of new photonic devices such as SAs for pulsed laser technology.

  7. Electron Acceleration Using Hollow Fiber with Table Top Terawatt Laser

    NASA Astrophysics Data System (ADS)

    Mizuta, Yoshio; Kondo, Kiminori; Zhenglin, Chen; Nakabayashi, Takashi; Nakanii, Nobuhiko; Kodama, Ryosuke; Mima, Kunioki; Tanaka, Kazuo

    2008-11-01

    A table top laser system can produce over 10TW laser pulse in present. If we focus these optical pulses to μm size, the focused intensity can be relativistic for electrons. In such a high field, the electron plasma wave (EPW) can be excited. This EPW is attractive for the accelerating field for charged particles. However, the effective interaction length is only a few hundred micro meters. For GeV electron acceleration, this short interaction length should be overcome. A simple hollow fiber is used for obtaining a longer acceleration distance. The spot diameter and the length of focused area should be 10μm and 10mm, respectively. We used the hollow fiber which has 20μm inner diameter and 10mm length. To fill the fiber with enough density atoms with keeping a good vacuum condition, the differential pumping system was used. Presently, we have succeeded in injecting μJ femtosecond pulses into the fine hollow fiber in the atmosphere. In this propagation, a strong self phase modulation occurred to generate a white light. Our plan for coming experiment and possible limiting factors will be discussed.

  8. Flexible high-repetition-rate ultrafast fiber laser

    PubMed Central

    Mao, Dong; Liu, Xueming; Sun, Zhipei; Lu, Hua; Han, Dongdong; Wang, Guoxi; Wang, Fengqiu

    2013-01-01

    High-repetition-rate pulses have widespread applications in the fields of fiber communications, frequency comb, and optical sensing. Here, we have demonstrated high-repetition-rate ultrashort pulses in an all-fiber laser by exploiting an intracavity Mach-Zehnder interferometer (MZI) as a comb filter. The repetition rate of the laser can be tuned flexibly from about 7 to 1100 GHz by controlling the optical path difference between the two arms of the MZI. The pulse duration can be reduced continuously from about 10.1 to 0.55 ps with the spectral width tunable from about 0.35 to 5.7 nm by manipulating the intracavity polarization controller. Numerical simulations well confirm the experimental observations and show that filter-driven four-wave mixing effect, induced by the MZI, is the main mechanism that governs the formation of the high-repetition-rate pulses. This all-fiber-based laser is a simple and low-cost source for various applications where high-repetition-rate pulses are necessary. PMID:24226153

  9. Fiber photo-catheters for laser treatment of atrial fibrillation

    PubMed Central

    Peshko, Igor; Rubtsov, Vladimir; Vesselov, Leonid; Sigal, Gennady; Laks, Hillel

    2009-01-01

    A fiber photo-catheter has been developed for surgical treatment of atrial fibrillation with laser radiation. Atrial fibrillation (AF) is a heart rhythm abnormality that involves irregular and rapid heartbeats. Recent studies demonstrate the superiority of treating AF disease with optical radiation of the near infrared region. To produce long continuous transmural lesions, solid-state lasers and laser diodes, along with end-emitting fiber catheters, have been used experimentally. The absence of side-emitting flexible catheters with the ability to produce long continuous lesions limits the further development of this technology. In this research, a prototype of an optical catheter, consisting of a flexible 10-cm fiber diffuser has been used to make continuous photocoagulation lesions for effective maze procedure treatments. The system also includes: a flexible optical reflector; a series of openings for rapid self-attachment to the tissue; and an optional closed-loop irrigating chamber with circulating saline to cool the optical diffuser and irrigate the tissue. PMID:19587838

  10. Similariton fiber laser with a hollow-core photonic bandgap fiber for dispersion control

    NASA Astrophysics Data System (ADS)

    Ruehl, A.; Prochnow, O.; Engelbrecht, M.; Wandt, D.; Kracht, D.

    2007-05-01

    We report on an ytterbium-doped similariton fiber ring laser with a hollow-core photonic bandgap fiber for intracavity dispersion control. The oscillator is hybrid mode locked with a saturable Bragg reflector and by nonlinear polarization evolution. This scheme allows for an exact adjustment of the transmission characteristic to avoid the formation of bunched noiselike pulses while the self-starting characteristic is preserved. The oscillator generates highly stretched similaritons at 1025 nm with a pulse energy above 1n J at a repetition rate of 21.9 MHz.

  11. [94 km Brillouin distributed optical fiber sensors based on ultra-long fiber ring laser pumping].

    PubMed

    Yuan, Cheng-Xu; Wang, Zi-Nan; Jia, Xin-Hong; Li, Jin; Yan, Xiao-Dong; Cui, An-Bin

    2014-05-01

    A novel optical amplification configuration based on ultra-long fiber laser with a ring cavity was proposed and applied to Brillouin optical time-domain analysis (BOTDA) sensing system, in order to extend the measurement distance significantly. The parameters used in the experiment were optimized, considering the main limitations of the setup, such as depletion, self-phase modulation (SPM) and pump-signal relative intensity noise (RIN) transfer. Through analyzing Brillouin gain spectrum, we demonstrated distributed sensing over 94 km of standard single-mode fiber with 3 meter spatial resolution and strain/temperature accuracy of 28 /1. 4 degree C.

  12. Fiber Bragg grating inscriptions in multimode fiber using 800 nm femtosecond laser

    NASA Astrophysics Data System (ADS)

    Rong, Qiangzhou; Qiao, Xueguang

    2015-09-01

    A short fiber Bragg grating (FBG) was successfully written in a multimode fiber (MMF) tube with core and cladding diameters of 105 μm and 125 μm using 800 nm femtosecond laser. A side-illumination technique was utilized to ensure the grating inscriptions regain over the core of MMF. Both fundamental mode and high-order modes of MMF are coupled at the core-mismatch junction and appear as two well-defined resonances in transmission. Femtosecond laserwritten three FBG-types present good thermostability up to 900 °C.

  13. Thulium fiber laser ablation of kidney stones using a 50-μm-core silica optical fiber

    NASA Astrophysics Data System (ADS)

    Blackmon, Richard L.; Hutchens, Thomas C.; Hardy, Luke A.; Wilson, Christopher R.; Irby, Pierce B.; Fried, Nathaniel M.

    2015-01-01

    Our laboratory is currently studying the experimental thulium fiber laser (TFL) as a potential alternative laser lithotripter to the gold standard, clinical Holmium:YAG laser. We have previously demonstrated the efficient coupling of TFL energy into fibers as small as 100-μm-core-diameter without damage to the proximal end. Although smaller fibers have a greater tendency to degrade at the distal tip during lithotripsy, fiber diameters (≤200 μm) have been shown to increase the saline irrigation rates through the working channel of a flexible ureteroscope, to maximize the ureteroscope deflection, and to reduce the stone retropulsion during laser lithotripsy. In this study, a 50-μm-core-diameter, 85-μm-outer-diameter, low-OH silica fiber is characterized for TFL ablation of human calcium oxalate monohydrate urinary stones, ex vivo. The 50-μm-core fiber consumes approximately 30 times less cross-sectional area inside the single working channel of a ureteroscope than the standard 270-μm-core fiber currently used in the clinic. The ureteroscope working channel flow rate, including the 50-μm fiber, decreased by only 10% with no impairment of ureteroscope deflection. The fiber delivered up to 15.4±5.9 W under extreme bending (5-mm-radius) conditions. The stone ablation rate measured 70±22 μg/s for 35-mJ-pulse-energy, 500-μs-pulse-duration, and 50-Hz-pulse-rate. Stone retropulsion and fiber burnback averaged 201±336 and 3000±2600 μm, respectively, after 2 min. With further development, thulium fiber laser lithotripsy using ultra-small, 50-μm-core fibers may introduce new integration and miniaturization possibilities and potentially provide an alternative to conventional Holmium:YAG laser lithotripsy using larger fibers.

  14. Development of Tm:fiber laser-pumped Ho:YLF laser

    NASA Astrophysics Data System (ADS)

    Mizutani, Kohei; Ishii, Shoken; Asai, Kazuhiro; Sato, Atsushi

    2016-05-01

    A 2-micron Ho:YLF laser end-pumped by 1.94-micron Tm:fiber laser was developed. A ring resonator oscillator of 3 m length and amplifier system was adopted. The laser was operated at high repetition rates of 200-5000 Hz in room temperature. The amplifier outputs were about 7.4W in CW and more than 6 Win Q-switch operation of repetition rates more than 500 Hz. This laser was developed to be used for coherent wind and CO2 measurements. Then, injection seeding was applied to the ring resonator and single mode laser emission was obtained. The laser was used for Doppler wind lidar measurements and wind profiles were obtained.

  15. Laser Welding of Copper Using Multi Mode Fiber Lasers at Near Infrared Wavelength

    NASA Astrophysics Data System (ADS)

    Liebl, S.; Wiedenmann, R.; Ganser, A.; Schmitz, P.; Zaeh, M. F.

    Due to the increasing electrification of automotive drives and the expansion of decentralized renewable energygeneration, the consumption of copper for the fabrication of electrical components such as electric motors or conducting paths increases. To jointhese components, laser welding is more frequently used since it represents a flexible and fully automatable joining process. Because of the high thermal conductivity, the low absorption coefficient forinfrared wavelength of common laser beam sources and the resulting limited process efficiency, welding of copper alloys represents a major challenge for laser assisted processes. In this paper, experimental investigationsare presented to identify arising process limits during laser welding of pure copper materials with multi-mode fiber lasers at near infrared wavelength depending on the applied laser power and welding velocity. In addition, a potential stabilization of the welding process by shielding gas support was examined. Further investigations were focused on the influence of shielding gas on the molten pool geometry.

  16. Influence of the fiber Bragg gratings with different reflective bandwidths in high power all-fiber laser oscillator

    NASA Astrophysics Data System (ADS)

    Wang, Jianming; Yan, Dapeng; Xiong, Songsong; Huang, Bao; Li, Cheng

    2017-01-01

    The effects of large-mode-area (LMA) fiber Bragg gratings (FBGs) with different reflective bandwidths on bi-directionally pumped ytterbium-doped single-mode all-fiber laser oscillator have been investigated experimentally. The forward laser output power and the backward signal leakage were measured and analyzed. It was found that the laser output power and efficiency depended on the bandwidth of the high-reflection (HR) FBG used in the laser cavity. The broader bandwidth gives higher laser efficiency, especially at high power level.

  17. Passively Q-switched Ho:YLF laser pumped by Tm3+-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Yang, Chao; Ju, Youlun; Yao, Baoquan; Dai, Tongyu; Duan, Xiaoming; Li, Jiang; Ding, Yu; Liu, Wei; Pan, Yubai; Li, Chaoyu

    2016-03-01

    We demonstrate a compact and efficient passively Q-switched (PQS) Ho:YLF laser pumped by a self-made all-fiber laser. Firstly, we design and make an all-fiber laser operating at 1940 nm with a slope efficiency of 40.6%. Then, the all-fiber laser was used to pump Ho:YLF laser directly. In the CW (continues-wave) operation Ho:YLF laser, the maximum output power was 7.79 W, corresponding to the slope efficiency of 55.2%. Using Cr2+:ZnS as the saturable absorber, the average power of 6.03 W was achieved with the slope efficiency of 45.9%. The shortest pulse duration was 15.6 ns and the pulse repetition frequency was 2.3 kHz at the pump power of 20.4 W. The pulse energy was a constant as 2.7 mJ when the pump power exceeded 15 W. The beam quality factor of M2 was 1.05, indicating nearly diffraction limited beam propagation.

  18. Wavelength tunability of L-band fiber ring lasers using mechanically induced long-period fiber gratings

    NASA Astrophysics Data System (ADS)

    Sakata, Hajime; Yoshimi, Hitoshi; Otake, Yuki

    2009-03-01

    We report on oscillation wavelength control in erbium-doped fiber ring lasers by adjusting the period of a mechanically induced long-period fiber grating (LPFG) inserted into the fiber ring resonator. Pump light is provided by a 974 nm laser diode (LD), the emission of which is coupled into the fiber ring resonator through a wavelength-division multiplexing coupler. Laser oscillation occurs with a threshold pump LD current of 40 mA, corresponding to a threshold pump power of 5 mW. When a periodic pressure of 0.81 N/mm is applied to form the LPFG, the fiber ring laser exhibits the tunable range of 40.9 nm, i.e., from 1563.1 to 1604 nm, by changing the grating period.

  19. Galvanometer beam-scanning system for laser fiber drawing.

    PubMed

    Oehrle, R C

    1979-02-15

    A major difficulty in using a laser to draw optical fibers from a glass preform has been uniformally distributing the laser's energy around the melt zone. Several systems have evolved in recent years, but to date the most successful technique has been the off-axis rotating lens system (RLS). The inability of this device to structure efficiently and dynamically the heat zone longitudinally along the preform has restricted its use to preform of less than 8-mm diameter. A new technique reported here employs two orthogonal mounted mirrors, driven by galvanometers to distribute the laser energy around the preform. This system can be retrofitted into the RLS to replace the rotating lens element. The new system, the galvanometer scanning system (GSS), operates at ten times the rotational speed of the RLS and can instantaneously modify the melt zone. The ability of the GSS to enlarge the melt zone reduces the vaporization rate at the surface of the preform permitting efficient use of higher laser power. Experiments i dicate that fibers can be drawn from significantly larger preforms by using the expanded heat zone provided by the GSS.

  20. Coilable single crystal fibers of doped-YAG for high power laser applications

    NASA Astrophysics Data System (ADS)

    Maxwell, Gisele; Soleimani, Nazila; Ponting, Bennett; Gebremichael, Eminet

    2013-05-01

    Single crystal fibers are an intermediate between laser crystals and doped glass fibers. They can combine the advantages of both by guiding laser light and matching the efficiencies found in bulk crystals, making them ideal candidates for high-power laser and fiber laser applications. In particular, a very interesting feature of single crystal fiber is that they can generate high power in the eye-safe range (Er:YAG) with a high efficiency, opening new possibilities for portable directed energy weapons. This work focuses on the growth of a flexible fiber with a core of dopant (Er, Nd, Yb, etc…) that will exhibit good waveguiding properties. Direct growth or a combination of growth and cladding experiments are described. We have, to date, demonstrated the growth of a flexible foot long 45 microns doped YAG fiber. Scattering loss measurements at visible wavelengths along with dopant profile characterization are also presented. Laser characterization for these fibers is in progress.

  1. Solutions of kW Continuous-wave All-fiber Laser

    NASA Astrophysics Data System (ADS)

    Dapeng, Yan; Libo, Li; Xiaoxu, Liu; Dayong, Min

    2011-02-01

    Solutions of kW continuous-wave (CW) all-fiber laser are proposed. In our solutions, master oscillator power amplifier (MOPA) configuration is applied. Output power of master oscillator is 10W, and then is amplified to 70W with 1st pre-amplifier and next scaled up to 400W. Finally, 400W fiber laser is used as a basic power unit, and 1000W all-fiber laser can be achieved by means of beam combining with large core double clad fiber (DCF) combiner. In this solution, fiber laser has good stability and reliability for dispersion coupling of pump source and inhibition of photon darkening effect in the fiber. In addition, this solution assures us realize a 1000W all-fiber laser product easily, and the cost is low.

  2. Experimental verification of fiber-coupling efficiency for satellite-to-ground atmospheric laser downlinks.

    PubMed

    Takenaka, Hideki; Toyoshima, Morio; Takayama, Yoshihisa

    2012-07-02

    Optical communication is a high-capacity method that can handle considerable satellite data. When common-fiber optical devices such as optical fiber amplifiers based on single mode fibers are used in free-space laser communication systems, the laser beam has to be coupled to a single-mode fiber. Under atmospheric turbulence it would be difficult to make the required fiber coupling efficiency in satellite-to-ground laser propagation paths. A fast-steering mirror that can operate at high frequencies under atmospheric turbulence is fabricated, and its tracking performance is verified in real satellite-to-ground laser communication experiments. The measured fiber coupling loss of 10-19 dB in satellite-to-ground laser communication links under atmospheric turbulence shows good agreement with the predicted fiber coupling efficiency of 17 dB.

  3. Airborne Polarimetric, Two-Color Laser Altimeter Measurements of Lake Ice Cover: A Pathfinder for NASA's ICESat-2 Spaceflight Mission

    NASA Technical Reports Server (NTRS)

    Harding, David; Dabney, Philip; Valett, Susan; Yu, Anthony; Vasilyev, Aleksey; Kelly, April

    2011-01-01

    The ICESat-2 mission will continue NASA's spaceflight laser altimeter measurements of ice sheets, sea ice and vegetation using a new measurement approach: micropulse, single photon ranging at 532 nm. Differential penetration of green laser energy into snow, ice and water could introduce errors in sea ice freeboard determination used for estimation of ice thickness. Laser pulse scattering from these surface types, and resulting range biasing due to pulse broadening, is assessed using SIMPL airborne data acquired over icecovered Lake Erie. SIMPL acquires polarimetric lidar measurements at 1064 and 532 nm using the micropulse, single photon ranging measurement approach.

  4. Novel multiple output and multiwavelength fiber ring-optical laser

    NASA Astrophysics Data System (ADS)

    Tsao, Shyh-Lin; Lin, Huang-Cuang

    2003-12-01

    The fiber ring structures optical signal processor with semiconductor optical amplifiers (SOA's) have been developed [1]. The SOA's have been demonstrated the ability of direct signal processing combining the optical amplification with ether modulation, detection, or wavelength conversion [2,3]. Moreover, the fiber-optical processors have many advantages. In this paper, we purpose new design configurations of an 8x8 array waveguide grating (AWG) connected to an SOA to achieve a ring configuration and experimentally measure its characteristics. In this paper, we can get fourteen signal processing output simultaneously by using such a fiber ring construction. The multiwavelenght and multiple output rings signal processor can be implemented by connecting any pair of the 8x8 AWG to the SOA. This application can develop a multiple-input-multiple-output processing only optical amplifier. We will present various useful parameters of application this fiber optic processor. References [1] Goodman, J.W.; Moslehi, B, "Novel amplified fiber-optic recirculating delay line processor", J.Lightwave Technol., Vol. 10 Issue: 8, pp.1142-1147, 1992 [2] U. Koren, B. I. Miller, M. G. Yang, T. L. Koch, R. M. Jopson, A. Gnauck, D. Evankow, and M. Chien, "High frequency modulation of strained layer multiple quantum well optical amplifiers", Electron. Lett., vol. 27, pp.62-64, 1991. [3] M. Gustavsson, A. Karlsson, and L. Thylen, "Traveling wave semiconductor laser amplifiers detectors", J. Lightwave Technol., vol. 8, pp. 610-617, 1990.

  5. Welding of PMMA by a femtosecond fiber laser.

    PubMed

    Volpe, Annalisa; Di Niso, Francesca; Gaudiuso, Caterina; De Rosa, Andrea; Vázquez, Rebeca Martínez; Ancona, Antonio; Lugarà, Pietro Mario; Osellame, Roberto

    2015-02-23

    Developing versatile joining techniques to weld transparent materials on a micrometer scale is of great importance in a growing number of applications, especially for the fabrication and assembly of biomedical devices. In this paper, we report on fs-laser microwelding of two transparent layers of polymethyl methacrylate (PMMA) based on nonlinear absorption and localized heat accumulation at high repetition rates. A fiber CPA laser system was used delivering 650-fs pulses at 1030 nm with repetition rates in the MHz regime. The laser-induced modifications produced by the focused beam into the bulk PMMA were firstly investigated, trying to find a suitable set of process parameters generating continuous and localized melting. Results have been evaluated based on existing heat accumulation models. Then, we have successfully laser welded two 1-mm-thick PMMA layers in a lap-joint configuration. Sealing of the sample was demonstrated through static and dynamic leakage tests. This fs-laser micro-welding process does not need any pre-processing of the samples or any intermediate absorbing layer. Furthermore, it offers several advantages compared to other joining techniques, because it prevents contamination and thermal distortion of the samples, thus being extremely interesting for application in direct laser fabrication of microfluidic devices.

  6. Broadly tunable multiwavelength fiber laser with bismuth-oxide EDF using large effective area fiber

    NASA Astrophysics Data System (ADS)

    Ramzia Salem, A. M.; Al-Mansoori, M. H.; Hizam, H.; Mohd Noor, S. B.; Mahdi, M. A.

    2011-02-01

    A multiwavelength laser comb using 2.49 m Bismuth-oxide erbium-doped fiber (Bi-EDF) with different lengths of large effective area fiber (LEAF) in a ring cavity configuration is realized. The Bi-EDF is used as the linear gain medium and LEAF is used as the non-linear gain medium for stimulated Brillouin scattering. Out of the four different lengths, the longest length of 25 km LEAF exhibits the widest tuning range of 44 nm (1576 to 1620 nm) in the L-band at 264 mW pump power and 5 mW Brillouin pump power. In addition, a total of 15 output channels are achieved with total average output power of -8 dBm from this laser structure. All Brillouin Stokes signals exhibit high peak power of above -20 dBm per signal and their optical signal-to-noise ratio of greater than 15 dB.

  7. Fiber-laser pumped actively Q-switched Er:LuYAG laser at 1648 nm

    NASA Astrophysics Data System (ADS)

    Yang, X. F.; Wang, Y.; Zhao, T.; Zhu, H. Y.; Shen, D. Y.

    2016-02-01

    We demonstrated an acousto-optic Q-switched 1648 nm Er:LuYAG laser resonantly pumped by a cladding-pumped Er,Yb fiber laser at 1532 nm. Stable Q-switching operation was obtained with the pulse repetition rate (PRR) varying from 200 Hz to 10 kHz. At PRR of 200 Hz, the laser yielded Q-switched pulses with 3.3 mJ pulse energy and 65 ns pulse duration, corresponding to a peak power of 50.7 kW for 10.4 W of incident pump power.

  8. Fiber laser pumped high power mid-infrared laser with picosecond pulse bunch output.

    PubMed

    Wei, Kaihua; Chen, Tao; Jiang, Peipei; Yang, Dingzhong; Wu, Bo; Shen, Yonghang

    2013-10-21

    We report a novel quasi-synchronously pumped PPMgLN-based high power mid-infrared (MIR) laser with picosecond pulse bunch output. The pump laser is a linearly polarized MOPA structured all fiberized Yb fiber laser with picosecond pulse bunch output. The output from a mode-locked seed fiber laser was directed to pass through a FBG reflector via a circulator to narrow the pulse duration from 800 ps to less than 50 ps and the spectral FWHM from 9 nm to 0.15 nm. The narrowed pulses were further directed to pass through a novel pulse multiplier through which each pulse was made to become a pulse bunch composing of 13 sub-pulses with pulse to pulse time interval of 1.26 ns. The pulses were then amplified via two stage Yb fiber amplifiers to obtain a linearly polarized high average power output up to 85 W, which were then directed to pass through an isolator and to pump a PPMgLN-based optical parametric oscillator via quasi-synchronization pump scheme for ps pulse bunch MIR output. High MIR output with average power up to 4 W was obtained at 3.45 micron showing the feasibility of such pump scheme for ps pulse bunch MIR output.

  9. Nondestructive thickness measurement system for multiple layers of paint based on femtosecond fiber laser technologies

    NASA Astrophysics Data System (ADS)

    Sudo, Masaaki; Takayanagi, Jun; Ohtake, Hideyuki

    2016-11-01

    Because optical fiber-based optical systems are generally robust against external interference, they can be used as reliable systems in industrial applications in various fields. This paper describes fiber lasers generating femtosecond pulses that use optical fibers as gain media and optical paths. Additionally, the nondestructive paint multilayer thickness measurement of automotive parts using terahertz waves generated and detected by femtosecond fiber laser systems was conducted.

  10. High-power 83 W holmium-doped silica fiber laser operating with high beam quality.

    PubMed

    Jackson, Stuart D; Sabella, Alex; Hemming, Alex; Bennetts, Shayne; Lancaster, David G

    2007-02-01

    A high-power 83 W cladding-pumped Tm3+-Ho3+-doped silica fiber laser is reported. Using bidirectional 793 nm diode pumping, a maximum slope efficiency of 42% was produced after a threshold launched pump power of 12 W was exceeded. The laser operated at wavelengths near 2105 nm with moderate beam quality, i.e., M2 approximately 1.5. Further power scaling of the fiber laser was limited by thermal failure of the fiber ends.

  11. High-power 83 W holmium-doped silica fiber laser operating with high beam quality

    NASA Astrophysics Data System (ADS)

    Jackson, Stuart D.; Sabella, Alex; Hemming, Alex; Bennetts, Shayne; Lancaster, David G.

    2007-02-01

    A high-power 83W cladding-pumped Tm3+-Ho3+-doped silica fiber laser is reported. Using bidirectional 793nm diode pumping, a maximum slope efficiency of 42% was produced after a threshold launched pump power of 12W was exceeded. The laser operated at wavelengths near 2105nm with moderate beam quality, i.e., M2˜1.5. Further power scaling of the fiber laser was limited by thermal failure of the fiber ends.

  12. Spectrally beam combined fiber lasers for high power, efficiency, and brightness

    NASA Astrophysics Data System (ADS)

    Honea, Eric; Afzal, Robert S.; Savage-Leuchs, Matthias; Gitkind, Neil; Humphreys, Richard; Henrie, Jason; Brar, Khush; Jander, Don

    2013-03-01

    Spectral Beam Combining (SBC) of fiber lasers provides a simple, robust architecture for power scaling lasers to high power. With appropriate designs, power scaling beyond the single fiber limit can be achieved while maintaining near diffraction limited beam quality and high efficiency. We present experimental results where we achieved > 3 kW at an M2 = 1.35 and > 39% E-O efficiency by combining 12 individual fiber lasers into a single high brightness beam.

  13. Experimental Performance of a Single-Mode Ytterbium-doped Fiber Ring Laser with Intracavity Modulator

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Camp, Jordan

    2012-01-01

    We have developed a linearly polarized Ytterbium-doped fiber ring laser with a single longitudinal mode output at 1064 run. A fiber-coupled intracavity phase modulator ensured mode-hop free operation and allowed fast frequency tuning. The fiber laser was locked with high stability to an iodine-stabilized laser, showing a frequency noise suppression of a factor approx 10 (exp 5) at 1 mHz

  14. Fiber optic laser-induced breakdown spectroscopy sensor for molten material analysis

    DOEpatents

    Zhang, Hansheng; Rai, Awadesh K.; Singh, Jagdish P.; Yueh, Fang-Yu

    2004-07-13

    A fiber optic laser-induced breakdown spectroscopy (LIBS) sensor, including a laser light source, a harmonic separator for directing the laser light, a dichroic mirror for reflecting the laser light, a coupling lens for coupling the laser light at an input of a multimode optical fiber, a connector for coupling the laser light from an output of the multimode optical fiber to an input of a high temperature holder, such as a holder made of stainless steel, and a detector portion for receiving emission signal and analyzing LIBS intensities. In one variation, the multimode optical fiber has silica core and silica cladding. The holder includes optical lenses for collimating and focusing the laser light in a molten alloy to produce a plasma, and for collecting and transmitting an emission signal to the multimode optical fiber.

  15. Long-distance fiber-optic point-sensing systems based on random fiber lasers.

    PubMed

    Wang, Z N; Rao, Y J; Wu, H; Li, P Y; Jiang, Y; Jia, X H; Zhang, W L

    2012-07-30

    We find that the random fiber laser (RFL) without point-reflectors is a temperature-insensitive distributed lasing system for the first time. Inspired by such thermal stability, we propose the novel concept of utilizing the RFL to achieve long-distance fiber-optic remote sensing, in which the RFL offers high-fidelity and long-distance transmission for the sensing signal. Two 100 km fiber Bragg grating (FBG) point-sensing schemes based on RFLs are experimentally demonstrated using the first-order and the second-order random lasing, respectively, to verify the concept. Each sensing scheme can achieve >20 dB optical signal-to-noise ratio (OSNR) over 100 km distance. It is found that the second-order random lasing scheme has much better OSNR than that of the first-order random lasing scheme due to enhanced lasing efficiency, by incorporating a 1455 nm FBG into the lasing cavity.

  16. Reversed dispersion slope photonic bandgap fibers for broadband dispersion control in femtosecond fiber lasers.

    PubMed

    Várallyay, Z; Saitoh, K; Fekete, J; Kakihara, K; Koshiba, M; Szipocs, R

    2008-09-29

    Higher-order-mode solid and hollow core photonic bandgap fibers exhibiting reversed or zero dispersion slope over tens or hundreds of nanometer bandwidths within the bandgap are presented. This attractive feature makes them well suited for broadband dispersion control in femtosecond pulse fiber lasers, amplifiers and optical parametric oscillators. The canonical form of the dispersion profile in photonic bandgap fibers is modified by a partial reflector layer/interface placed around the core forming a 2D cylindrical Gires-Tournois type interferometer. This small perturbation in the index profile induces a frequency dependent electric field distribution of the preferred propagating higher-order-mode resulting in a zero or reversed dispersion slope.

  17. Remote high temperature sensing with a reflective bandpass long-period fiber grating and a fiber ring laser

    NASA Astrophysics Data System (ADS)

    Hou, Yusong; Zhu, Tao; Shi, Leilei; Zhang, Qiang; Chiang, Kin Sing

    2013-09-01

    We demonstrate a remote high temperature fiber sensing system, where the sensing element is a long-period fiber grating (LPFG) fusion-spliced to a short section of a hollow-core fiber (HCF) and sensor interrogation is achieved with a fiber ring laser. The HCF turns the LPFG from a band-rejection filter into a reflective bandpass filter, while the ring laser selects the reflected wavelength from the LPFG sensor. Our experimental sensor shows a sensitivity of 0.095 nm °C-1 over the temperature range from 150 to 600 °C and the sensing distance is about 1 km.

  18. A switchable dual-wavelength fiber laser based on asymmetric fiber Bragg grating Fabry-Perot cavity with a SESAM

    NASA Astrophysics Data System (ADS)

    Huang, Kaiqiang; Li, Qi; Chen, Haiyan

    2016-04-01

    A switchable dual-wavelength fiber laser with an asymmetric fiber Bragg grating (FBG)-Fabry-Perot (FP) cavity based a semiconductor saturable absorber mirror (SESAM) is proposed and experimentally demonstrated. The proof of concept device consists of a FGB laser with an asymmetric FBG-FP cavity, a SESAM as mode loss modulator, and a intracavity FBG as wavelength selector by changing its operation temperature. The results demonstrate the new concept of dual-wavelength fiber laser based SESAM with asymmetric FBG-FP cavity and the technical feasibility.

  19. Switchable dual-wavelength fiber laser based on semiconductor optical amplifier and polarization-maintaining fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Feng, Suchun; Xu, Ou; Lu, Shaohua; Ren, Wenhua; Jian, Shuisheng

    2008-12-01

    Switchable dual-wavelength with orthogonal polarizations fiber laser based on semiconductor optical amplifier (SOA) and polarization-maintaining fiber Bragg grating (PMFBG) at room temperature is proposed. Owing to the polarization dependent loss of the PMFBG, the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting the polarization controller (PC). The amplitude variation in nearly half an hour is less than 0.1 dB for both wavelengths, which is more stable than that of erbium doped fiber (EDF)-based laser with similar configuration.

  20. Advances in high-power 9XXnm laser diodes for pumping fiber lasers

    NASA Astrophysics Data System (ADS)

    Skidmore, Jay; Peters, Matthew; Rossin, Victor; Guo, James; Xiao, Yan; Cheng, Jane; Shieh, Allen; Srinivasan, Raman; Singh, Jaspreet; Wei, Cailin; Duesterberg, Richard; Morehead, James J.; Zucker, Erik

    2016-03-01

    A multi-mode 9XXnm-wavelength laser diode was developed to optimize the divergence angle and reliable ex-facet power. Lasers diodes were assembled into a multi-emitter pump package that is fiber coupled via spatial and polarization multiplexing. The pump package has a 135μm diameter output fiber that leverages the same optical train and mechanical design qualified previously. Up to ~ 270W CW power at 22A is achieved at a case temperature ~ 30ºC. Power conversion efficiency is 60% (peak) that drops to 53% at 22A with little thermal roll over. Greater than 90% of the light is collected at < 0.12NA at 16A drive current that produces 3.0W/(mm-mr)2 radiance from the output fiber.

  1. Efficient femtosecond pulse generation in an all-normal-dispersion Yb:fiber ring laser at 605 MHz repetition rate.

    PubMed

    Yang, Hongyu; Wang, Aimin; Zhang, Zhigang

    2012-03-01

    We report a 1030 nm-wavelength Yb:fiber laser that produces the shortest/direct output pulse duration (502 fs) among all-normal-dispersion fiber lasers at the highest repetition rate (605 MHz) among the passively fundamentally mode-locked fiber lasers. The laser also exhibits an optical efficiency of 70% at CW and 65% at mode-locking modes.

  2. Analysis of the scalability of diffraction-limited fiber lasers and amplifiers to high average power.

    PubMed

    Dawson, Jay W; Messerly, Michael J; Beach, Raymond J; Shverdin, Miroslav Y; Stappaerts, Eddy A; Sridharan, Arun K; Pax, Paul H; Heebner, John E; Siders, Craig W; Barty, C P J

    2008-08-18

    We analyze the scalability of diffraction-limited fiber lasers considering thermal, non-linear, damage and pump coupling limits as well as fiber mode field diameter (MFD) restrictions. We derive new general relationships based upon practical considerations. Our analysis shows that if the fiber's MFD could be increased arbitrarily, 36 kW of power could be obtained with diffraction-limited quality from a fiber laser or amplifier. This power limit is determined by thermal and non-linear limits that combine to prevent further power scaling, irrespective of increases in mode size. However, limits to the scaling of the MFD may restrict fiber lasers to lower output powers.

  3. A robust all-fiber active Q-switched 1-µm Yb3+ fiber laser

    NASA Astrophysics Data System (ADS)

    Sintov, Yoav; Goldring, Sharone; Pearl, Shaul; Lebiush, Eyal; Sfez, Bruno; Malka, Dror; Zalevsky, Zeev

    2015-09-01

    An all-fiber active Q-switched Yb3+-doped fiber laser at 1 µm is presented. The laser is composed of a ring resonator with an embedded all-fiber Q-switch element, based on a null coupler with an attached piezoelectric transducer (PZT). The PZT is used as an acoustic actuator, for inducing longitudinal acoustic disturbance along the null coupler and causing light coupling between the null coupler's ports. A stable operation is achieved with an overall average output power of up to 275 mW at various pulse repetition rates (PRR), ranging from 10 to 35 kHz and typical pulse energy of 15 μJ. In addition, a self-monitoring method is implemented by an embedded microcontroller, in order to maintain stable Q-switch performance, in changing environmental conditions. An average power of 8.5 W and pulse energy of 420 μJ at a PRR of 20 kHz are demonstrated in a master oscillator power amplifier containing the Q-switched laser, followed by a power amplifier.

  4. Adaptive ultrasonic sensor using a fiber ring laser with tandem fiber Bragg gratings.

    PubMed

    Liu, Tongqing; Hu, Lingling; Han, Ming

    2014-08-01

    We propose and demonstrate an intensity-demodulated fiber-optic ultrasonic sensor system that can be self-adaptive to large quasi-static background strain perturbations. The sensor system is based on a fiber ring laser (FRL) whose laser cavity includes a pair of fiber Bragg gratings (FBGs). Self-adaptive ultrasonic detection is achieved by a tandem design where the two FBGs are engineered to have differential spectral responses to ultrasonic waves and are installed side-by-side at the same location on a structure. As a result, ultrasonic waves lead to relative spectral shifts of the FBGs and modulations to the cold-cavity loss of the FRL. Ultrasonic waves can then be detected directly from the laser intensity variations in response to the cold-cavity loss modulation. The sensor system is insensitive to quasi-static background strains because they lead to identical responses of the tandem FBGs. Based on the principle, a FRL sensor system was demonstrated and tested for adaptive ultrasonic detection when large static strains as well as dynamic sinusoidal vibrations were applied to the sensor.

  5. Efficient second-harmonic conversion of CW single-frequency Nd:YAG laser light by frequency locking to a monolithic ring frequency doubler

    NASA Technical Reports Server (NTRS)

    Gerstenberger, D. C.; Tye, G. E.; Wallace, R. W.

    1991-01-01

    Efficient second-harmonic conversion of the 1064-nm output of a diode-pumped CW single-frequency Nd:YAG laser to 532 nm was obtained by frequency locking the laser to a monolithic ring resonator constructed of magnesium-oxide-doped lithium niobate. The conversion efficiency from the fundamental to the second harmonic was 65 percent. Two hundred milliwatts of CW single-frequency 532-nm light were produced from 310 mW of power of 1064-nm light. This represents a conversion efficiency of 20 percent from the 1-W diode laser used to pump the Nd:YAG laser to single-frequency 532-nm output. No signs of degradation were observed for over 500 h of operation.

  6. 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.

  7. 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.

  8. High power ytterbium-doped fiber lasers — fundamentals and applications

    NASA Astrophysics Data System (ADS)

    Zervas, Michalis N.

    2014-03-01

    In this paper, we summarize the fundamental properties and review the latest developments in high power ytterbium-doped fiber (YDF) lasers. The review is focused primarily on the main fiber laser configurations and the related cladding pumping issues. Special attention is placed on pump combination techniques and the parameters that affect the brightness enhancements observed in high power fiber lasers. The review also includes the major limitations imposed by fiber nonlinearities and other parasitic effects, such as optical damage, modal instabilities and photodarkening. The paper summarizes the power evolution in continuous-wave (CW) and pulsed YDF lasers and their impact on material processing and other industrial applications.

  9. High-power thulium fiber laser ablation of the canine prostate

    NASA Astrophysics Data System (ADS)

    Fried, Nathaniel M.; Murray, Keith E.

    2005-04-01

    The Thulium fiber laser may have several advantages over current urology lasers, including smaller size, more efficient operation, improved spatial beam quality, more precise tissue incision, and operation in pulsed or continuous-wave modes. However, previous laser-tissue interaction studies utilizing the Thulium fiber laser have been limited to laser powers of less than 5 W. This study describes high-power Thulium fiber laser vaporization of the canine prostate, ex vivo. A continuous-wave, 110-watt Thulium fiber laser operating at a wavelength of 1.91 mm, delivered 88.5 +/- 2.3 W of power through a 600-mm-core silica fiber for non-contact vaporization of canine prostates (n=6). The Thulium fiber laser vaporized prostate tissue at a rate of 0.83 +/- 0.11 g/min. The thermal coagulation zone measured 500-2000 mm. The high-power Thulium fiber laser is capable of rapid vaporization and coagulation of the prostate, ex vivo. In vivo animal studies are currently in development for evaluation of the Thulium fiber laser for prostate vaporization and potential treatment of benign prostate hyperplasia.

  10. High-efficiency generation in a short random fiber laser

    NASA Astrophysics Data System (ADS)

    Vatnik, I. D.; Churkin, D. V.; Podivilov, E. V.; Babin, S. A.

    2014-07-01

    We demonstrate a high-efficiency random lasing in a 850 m span of a phosphosilicate fiber. Random distributed feedback owing to the Rayleigh backscattering in the fiber enables narrowband generation with output power of up to 7.3 W at the Stokes wavelength λS = 1308 nm from 11 W of the pump power at λP = 1115 nm. The laser demonstrates unique generation efficiency. Near the generation threshold, more than 2 W of output power is generated from only 0.5 W of pump power excess over the generation threshold. At high pump power, the quantum conversion efficiency defined as a ratio of generated and pump photons at the laser output exceeds 100%. It is explained by the fact that every pump photon is converted into the Stokes photon far from the output fiber end, while the Stokes photons have lower attenuation than the pump photons.

  11. Switchable multiwavelength thulium-doped fiber ring lasers

    NASA Astrophysics Data System (ADS)

    Zhao, Shui; Lu, Ping; Liu, Deming; Zhang, Jiangshan

    2013-08-01

    Two kinds of thulium-doped fiber ring lasers based on a spatial mode beating filter and comb filtering effect are presented and experimentally demonstrated, which all show multiwavelength laser spectrum around 2 μm. In the implementation of the first type of experiment configuration by the use of a piece of multimode fiber (MMF) as a spatial mode beating filter, dual-,triple-, and quadruple-wavelengths appeared whose extinction noise ratio is 25 dB by adjusting the angle of polarization controller. Different wavelength spaces are obtained by inserting different lengths of MMF. The second type is achieved by inserting a Sagnac loop mirror, which was constructed by a 3-dB coupler and a piece of polarization maintaining fiber. Seven stable wavelengths with channel spacing of 0.65 nm and an extinction ratio of 35 dB was achieved. These systems are simple and easy to construct, which can be useful for 2 μm wavelength-division-multiplexed applications.

  12. A Fiber-Optic Coupled Telescope for Water Vapor DIAL Receivers

    NASA Technical Reports Server (NTRS)

    DeYoung, Russell J.; Lonn, Frederick

    1998-01-01

    A fiber-optic coupled telescope of low complexity was constructed and tested. The major loss mechanisms of the optical system have been characterized. Light collected by the receiver mirror is focused onto an optical fiber, and the output of the fiber is filtered by an interference filter and then focused onto an APD detector. This system was used in lidar field measurements with a 532-nm Nd:YAG laser beam. The results were encouraging. A numerical model used for calculation of the expected return signal agreed with the lidar return signal obtained. The assembled system was easy to align and operate and weighed about 8 kg for a 30 cm (12") mirror system. This weight is low enough to allow mounting of the fiber-optic telescope receiver system in a UAV. Furthermore, the good agreement between the numerical lidar model and the performance of the actual receiver system, suggests that this model may be used for estimation of the performance of this and other lidar systems in the future. Such telescopes are relatively easy to construct and align. The fiber optic cable allows easy placement of the optical detector in any position. These telescope systems should find widespread use in aircraft and space home DIAL water vapor receiver systems.

  13. Modeling synchronization in networks of delay-coupled fiber ring lasers.

    PubMed

    Lindley, Brandon S; Schwartz, Ira B

    2011-11-21

    We study the onset of synchronization in a network of N delay-coupled stochastic fiber ring lasers with respect to various parameters when the coupling power is weak. In particular, for groups of three or more ring lasers mutually coupled to a central hub laser, we demonstrate a robust tendency toward out-of-phase (achronal) synchronization between the N-1 outer lasers and the single inner laser. In contrast to the achronal synchronization, we find the outer lasers synchronize with zero-lag (isochronal) with respect to each other, thus forming a set of N-1 coherent fiber lasers.

  14. Fiber lasers and amplifiers for science and exploration at NASA Goddard Space Flight Center

    NASA Technical Reports Server (NTRS)

    Krainak, Michael A.; Abshire, James; Allan, Graham R.; Stephen Mark

    2005-01-01

    We discuss present and near-term uses for high-power fiber lasers and amplifiers for NASA- specific applications including planetary topography and atmospheric spectroscopy. Fiber lasers and amplifiers offer numerous advantages for both near-term and future deployment of instruments on exploration and science remote sensing orbiting satellites. Ground-based and airborne systems provide an evolutionary path to space and a means for calibration and verification of space-borne systems. We present experimental progress on both the fiber transmitters and instrument prototypes for ongoing development efforts. These near-infrared instruments are laser sounders and lidars for measuring atmospheric carbon dioxide, oxygen, water vapor and methane and a pseudo-noise (PN) code laser ranging system. The associated fiber transmitters include high-power erbium, ytterbium, neodymium and Raman fiber amplifiers. In addition, we will discuss near-term fiber laser and amplifier requirements and programs for NASA free space optical communications, planetary topography and atmospheric spectroscopy.

  15. High-power continuous-wave cladding-pumped Raman fiber laser.

    PubMed

    Codemard, C A; Dupriez, P; Jeong, Y; Sahu, J K; Ibsen, M; Nilsson, J

    2006-08-01

    We demonstrate a high-power single-mode cladding-pumped Raman fiber laser. The Raman fiber laser consists of a 1.2 km long germanium-doped double-clad fiber in a linear cavity, which is spliced to a single-mode fiber. The laser is end pumped by a multimode erbium-ytterbium-doped fiber, which is coupled to the inner cladding of the Raman fiber. The embedded core was designed to be single mode at the Raman Stokes wavelength, and up to 10 W of power was obtained at 1660 nm from the single-mode fiber end. The laser has a slope efficiency of 67% and a threshold of 6.5 W.

  16. Pulsed operation of Tm-doped fiber lasers using piezoelectric-driven microbend applied to elliptical coating fibers

    NASA Astrophysics Data System (ADS)

    Sakata, H.; Kimpara, K.; Komori, K.; Tomiki, M.

    2014-05-01

    We report Q-switched pulse generation in Tm-doped fiber lasers by introducing piezoelectric-driven microbend into an elliptical coating fiber in a fiber ring resonator. Compared with the untreated circular fiber having a diameter of 240 μm, the elliptical coating fiber was flattened to have a major axis diameter of about 300 μm. We employed a pair of comblike plates attached on the piezoelectric actuators in order to bend the fiber from both sides. The output pulse power is improved by optimizing the tooth-width and spatial period of the comb-like plates, so that the elliptical coating fiber is easily bent and the propagation mode is efficiently coupled to radiation modes around λ = 1.9 μm. The Tm-doped fiber is pumped by a laser diode emitting at 1.63 μm and the pump light is introduced to the fiber ring resonator via the wavelength division multiplexing coupler. The emission spectra showed that the center oscillation wavelength was typically 1.92 μm. When the pump power was increased to 156 mW, the output pulse showed a peak power of 42.5 W with a pulse width of 1.06 μs. We expect that the in-fiber Q-switching technique will provide simple laser systems for environmental sensing and medical applications.

  17. Yb³⁺-doped large core silica fiber for fiber laser prepared by glass phase-separation technology.

    PubMed

    Chu, Yingbo; Ma, Yunxiu; Yang, Yu; Liao, Lei; Wang, Yibo; Hu, Xiongwei; Peng, Jinggang; Li, Haiqing; Dai, Nengli; Li, Jinyan; Yang, Luyun

    2016-03-15

    We report on the preparation and optical characteristics of an Yb(3+)-doped large core silica fiber with the active core prepared from nanoporous silica rod by the glass phase-separation technology. The measurements show that the fiber has an Yb(3+) concentration of 9811 ppm by weight, a low background attenuation of 0.02 dB/m, and absorption from Yb(3+) about 5.5 dB/m at 976 nm. The laser performance presents a high slope efficiency of 72.8% for laser emission at 1071 nm and a low laser threshold of 3 W within only 2.3 m fiber length. It is suggested that the glass phase-separation technology shows great potential for realizing active fibers with larger core and complex fiber designs.

  18. CO2 Laser Cutting of Glass Fiber Reinforce Polymer Composite

    NASA Astrophysics Data System (ADS)

    Fatimah, S.; Ishak, M.; Aqida, S. N.

    2012-09-01

    The lamination, matrix properties, fiber orientation, and relative volume fraction of matrix of polymer structure make this polymer hard to process. The cutting of polymer composite using CO2 laser could involve in producing penetration energy in the process. Identification of the dominant factors that significantly affect the cut quality is important. The objective of this experiment is to evaluate the CO2 spot size of beam cutting for Glass Fiber Reinforce Polymer Composite (GFRP). The focal length selected 9.5mm which gave smallest focus spot size according to the cutting requirements. The effect of the focal length on the cut quality was investigated by monitoring the surface profile and focus spot size. The beam parameter has great effect on both the focused spot size and surface quality.

  19. Fiber optic coherent laser radar 3D vision system

    SciTech Connect

    Clark, R.B.; Gallman, P.G.; Slotwinski, A.R.; Wagner, K.; Weaver, S.; Xu, Jieping

    1996-12-31

    This CLVS will provide a substantial advance in high speed computer vision performance to support robotic Environmental Management (EM) operations. This 3D system employs a compact fiber optic based scanner and operator at a 128 x 128 pixel frame at one frame per second with a range resolution of 1 mm over its 1.5 meter working range. Using acousto-optic deflectors, the scanner is completely randomly addressable. This can provide live 3D monitoring for situations where it is necessary to update once per second. This can be used for decontamination and decommissioning operations in which robotic systems are altering the scene such as in waste removal, surface scarafacing, or equipment disassembly and removal. The fiber- optic coherent laser radar based system is immune to variations in lighting, color, or surface shading, which have plagued the reliability of existing 3D vision systems, while providing substantially superior range resolution.

  20. Tissue effects of Nd:YAG, KTP, and FiberTomeTM lasers with varying fiber tips and power settings

    NASA Astrophysics Data System (ADS)

    Vari, Sandor G.; Snyder, Wendy J.; Pergadia, Vani R.; Fishbein, Michael C.; Weiss, Andrew B.; Duffy, J. T.; Thomas, Reem; Shi, Wei-Qiang; Fry, Stephen M.; Grundfest, Warren S.

    1994-02-01

    This study compared the laser tissue effect of the Dornier FiberTomeTM system, the conventional Nd:YAG and the KTP laser on the stomach and liver. The cutting capabilities, thermal effects of the laser systems, as well as their dependence on power output and tissue type, were evaluated. A motorized fiber holder to maintain constant conditions (cutting speed fiber angle, and pressure) was developed. The results show that the cutting depth and cutting width are inversely proportional to the output level. The thermal damage remained constant as the output increased. Use of the FiberTomeTM system appears to be more advantageous than the conventional Nd:YAG laser in pigmented tissues, in the range of the parameters tested.