Yb:YAG disc for high energy laser systems

NASA Astrophysics Data System (ADS)

Nejezchleb, Karel; Kubát, Jan; Å ulc, Jan; Jelínková, Helena

2017-02-01

Large Yb:YAG crystals were grown using of new improved technology enabling to produce YAG crystals without central growth defect. The crystals diameter reached 115-120mm and their central part was used for manufacturing of discs with the diameter larger than 55 mm. Both sides of this discs were polished and coated. Doping concentration of Yb3+ ions in Yb:YAG crystals was measured using of X-ray fluorescence spectrometry. Absorption coefficient of Yb:YAG was measured for different doping concentration of Yb3+ ions. Fluorescence decay time of Yb:YAG was measured at temperatures of 300K and 80 K. We found the fluorescence decay time of the values of 0.95-1 ms at both temperatures stable and independent on the Yb3+ doping concentration in the range of 1-10 at.% Yb/Y demonstrating high chemical purity of grown crystals. Optical homogeneity as measured using of Fizeau double pass interferometer at 633nm resulted with PV values lower than 0.15 λ on clear aperture of 35 mm. Polished surfaces were ideally parallel with the wedge lower than 2 arcsec. Uniformity of laser properties of Yb:YAG was verified by scanning of the disc as active media in plan-convex pulsed laser resonator pumped by semiconductor diode (wavelength 969 nm, pumping beam diameter 100 μm). It was confirmed, that newly developed technology allows to manufacture very large high quality Yb:YAG discs suitable for high power lasers and amplifiers.

Micro-pulling-down furnace modification and single crystal fibers growth

NASA Astrophysics Data System (ADS)

Yuan, Dongsheng; Jia, Zhitai; Li, Yang; Wu, Baiyi; Tao, Xutang

2016-03-01

Single crystal fiber (SCF) combines the excellent instinct properties of conventional bulk laser crystals, and the special geometry advantage of active optical fibers. YAG and LuAG are proper host candidates for single crystal fiber laser with high thermal conductivity. Despite a lower thermal conductivity for pure crystal than YAG, LuAG crystal is easier to obtain homogeneous optical quality, and has a thermal conductivity nearly independent from the doping level. Micropulling- down (μ-PD) has relatively small thermal gradient, and here we use μ-PD to carry out high quality SCFs. Through the μ-PD furnace manufactured by ourselves, crystal fibers with different diameters have been grown successfully. We designed and fabricated a method to adjust the thermal distribution, and with the favor of pulling-down rate, the specific diameter can be controlled perfectly. The crystalline quality and homogeneity along the whole fiber were investigated, and LuAG SCF was confirmed to have a fine crystal quality for laser.

1.44-μm giant pulse generation

NASA Astrophysics Data System (ADS)

Šulc, Jan; Arátor, Pavel; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav

2007-02-01

We have compared two solid-state saturable absorbers for Q-switching of longitudinally diode-pumped Nd:YAG laser operating at wavelength 1444 nm: vanadium doped garnet (V 3+:Y 3Al IIO 5, V:YAG), and cobalt doped spinel (Co 2+:MgAl IIO 4, Co:MALO). V:YAG crystal with initial transmission 91% was 2.2mm thick. Co:MALO crystal with initial transmission 91% was 2.0mm thick. Q-switched laser consisted of the Nd:YAG composite rod (8mm long Nd-doped part, 4mm long undoped YAG part) and the saturable absorber placed in 80mm long hemispheric cavity. As an output coupler was used concave mirror (r = 150mm) with reflectivity 98% on lasing wavelength. Giant pulses were obtained with both passive Q-switches. When V:YAG saturable absorber was used, 55 ns long (FWHM) pulses were generated with peak power 0.47kW (pulse energy 26 μJ). Using Co:MALO, more powerful pulses were obtained (40 ns long, 1.0kW peak power, 45 μJ energy). Advantage of less efficient V:YAG consist in possibility of diffusion bonding between Q-switch and laser active medium which allows to prepare miniature compact laser device. This concept was demonstrated by using of Nd:YAG/V:YAG monolith crystal (4mm long undoped YAG part, 8mm long Nd:YAG part, 0.5mm long V:YAG part - initial transmission 97% @ 1444 nm). This monolithic crystal, originally designed for 1338nm lasing, was placed into 23mm long cavity resonating at wavelength 1444 nm. For output coupler reflectivity 96% pulses 39 ns long with peak power 0.64kW were generated at wavelength 1444 nm.

Growth of rare-earth doped single crystal yttrium aluminum garnet fibers

NASA Astrophysics Data System (ADS)

Bera, Subhabrata; Nie, Craig D.; Harrington, James A.; Cheng, Long; Rand, Stephen C.; Li, Yuan; Johnson, Eric G.

2018-02-01

Rare-earth doped single crystal (SC) yttrium aluminum garnet (YAG) fibers have great potential as high-power laser gain media. SC fibers combine the superior material properties of crystals with the advantages of a fiber geometry. Improving processing techniques, growth of low-loss YAG SC fibers have been reported. A low-cost technique that allows for the growth of optical quality Ho:YAG single crystal (SC) fibers with different dopant concentrations have been developed and discussed. This technique is a low-cost sol-gel based method which offers greater flexibility in terms of dopant concentration. Self-segregation of Nd ions in YAG SC fibers have been observed. Such a phenomenon can be utilized to fabricate monolithic SC fibers with graded index.

Study on growth techniques and macro defects of large-size Nd:YAG laser crystal

NASA Astrophysics Data System (ADS)

Quan, Jiliang; Yang, Xin; Yang, Mingming; Ma, Decai; Huang, Jinqiang; Zhu, Yunzhong; Wang, Biao

2018-02-01

Large-size neodymium-doped yttrium aluminum garnet (Nd:YAG) single crystals were grown by the Czochralski method. The extinction ratio and wavefront distortion of the crystal were tested to determine the optical homogeneity. Moreover, under different growth conditions, the macro defects of inclusion, striations, and cracking in the as-grown Nd:YAG crystals were analyzed. Specifically, the inclusion defects were characterized using scanning electron microscopy and energy dispersive spectroscopy. The stresses of growth striations and cracking were studied via a parallel plane polariscope. These results demonstrate that improper growth parameters and temperature fields can enhance defects significantly. Thus, by adjusting the growth parameters and optimizing the thermal environment, high-optical-quality Nd:YAG crystals with a diameter of 80 mm and a total length of 400 mm have been obtained successfully.

Low-cost Engineering of Laser Rods and Slabs with Liquid Phase Epitaxy

DTIC Science & Technology

2011-09-01

SUPPLEMENTARY NOTES 14. ABSTRACT We investigated the use of a liquid phase epitaxial ( LPE ) coating to improve the performance of a rod or slab laser. A...single crystal erbium-doped yttrium aluminum garnet (Er:YAG) rod coated with undoped YAG, and an uncoated sample were procured, then compared on the...the whispering gallery modes, which otherwise would deplete the gain in ~50% of the rod volume. We also investigated LPE growth on a ceramic sample

Sensitivity-enhanced Tm3+/Yb3+ co-doped YAG single crystal optical fiber thermometry based on upconversion emissions

NASA Astrophysics Data System (ADS)

Yu, Lu; Ye, Linhua; Bao, Renjie; Zhang, Xianwei; Wang, Li-Gang

2018-03-01

Optical thermometry based on Y3Al5O12 (YAG) single crystal optical fiber with end Tm3+/Yb3+ co-doped is presented. The YAG crystal fiber with end Tm3+/Yb3+ co-doped was grown by laser heated pedestal growth (LHPG) method. Under a 976 nm laser diode excitation, the upconversion (UC) emissions, originating from 3F2,3 →3H6 and 3H4 →3H6 transitions of Tm3+ ions, were investigated in the temperature range from 333 K to 733 K. Interestingly, the UC emission intensity of 3F2,3 →3H6 transition was significantly enhanced with increase of temperature, as compared with the other Tm3+/Yb3+ co-doped materials. The temperature dependence of fluorescence intensity ratio (FIR) of these two emission bands (3F2,3/3H4 →3H6) suggests that this doped YAG crystal fiber can be used as a highly sensitive optical thermal probe, which demonstrates a high absolute sensitivity with the maximum value of 0.021 K-1 at 733 K. In addition, due to the compact structure, strong mechanical strength and high thermal stability, such thermal probe may be a more promising candidate for temperature sensor with a high spatial resolution.

Laser-induced damage of coatings on Yb:YAG crystals at cryogenic condition

NASA Astrophysics Data System (ADS)

Wang, He; Zhang, Weili; Chen, Shunli; Zhu, Meiping; He, Hongbo; Fan, Zhengxiu

2011-12-01

As large amounts of heat need to be dissipated during laser operation, some diode pumped solid state lasers (DPSSL), especially Yb:YAG laser, operate at cryogenic condition. This work investigated the laser induced damage of coatings (high-reflective and anti-reflective coatings) on Yb:YAG crystals at cryogenic temperature and room temperature. The results show that the damage threshold of coatings at cryogenic temperature is lower than the one at room temperature. Field-emission scanning electron microscopy (FESEM), optical profiler, step profiler and Atomic force microscope (AFM) were used to obtain the damage morphology, size and depth. Taking alteration of physical parameters, microstructure of coatings and the environmental pollution into consideration, we analyzed the key factor of lowering the coating damage threshold at cryogenic conditions. The results are important to understand the mechanisms leading to damage at cryogenic condition.

Experimental investigation of a diode-pumped powerful continuous-wave dual-wavelength Nd:YAG laser at 946 and 938.6 nm

NASA Astrophysics Data System (ADS)

Chen, F.; Yu, X.; Yan, R. P.; Li, X. D.; Li, D. J.; Yang, G. L.; Xie, J. J.; Guo, J.

2013-05-01

In this paper, a diode-pumped high-power continuous-wave (cw) dual-wavelength Nd:YAG laser at 946 and 938.6 nm is reported. By using an end-pumped structure, comparative experiments indicate that a 5 mm-length Nd:YAG crystal with a Nd3+-doping concentration of 0.3 at.% is favorable for high-power laser operation, and the optimal transmissivity of the output coupler is 9%. As a result, a maximum output power of 17.2 W for a dual-wavelength laser at 946 and 938.6 nm is obtained at an incident pump power of 75.9 W, corresponding to a slope efficiency of 26.5%. To the best of our knowledge, this is the highest output power of a quasi-three-level dual-wavelength laser using a conventional Nd:YAG crystal achieved to date. By using a traveling knife-edge method, the beam quality factor and far-field divergence angle at 17 W power level are estimated to be 4.0 and 6.13 mrad, respectively.

Y-junctions based on circular depressed-cladding waveguides fabricated with femtosecond pulses in Nd:YAG crystal: A route to integrate complex photonic circuits in crystals

NASA Astrophysics Data System (ADS)

Ajates, Javier G.; Romero, Carolina; Castillo, Gabriel R.; Chen, Feng; Vázquez de Aldana, Javier R.

2017-10-01

We have designed and fabricated photonic structures such as, Y-junctions (one of the basic building blocks for construction any integrated photonic devices) and Mach-Zehnder interferometers, based on circular depressed-cladding waveguides by direct femtosecond laser irradiation in Nd:YAG crystal. The waveguides were optically characterized at 633 nm, showing nearly mono-modal behaviour for the selected waveguide radius (9 μm). The effect of the splitting angle in the Y structures was investigated finding a good preservation of the modal profiles up to more than 2°, with 1 dB of additional losses in comparison with straight waveguides. The dependence with polarization of these splitters keeps in a reasonable low level. Our designs pave the way for the fabrication of arbitrarily complex 3D photonic circuits in crystals with cladding waveguides.

A spatio-spectral polarization analysis of 1 µm-pumped bulk supercontinuum in a cubic crystal (YAG)

NASA Astrophysics Data System (ADS)

Choudhuri, Aradhana; Chatterjee, Gourab; Zheng, Jiaan; Hartl, Ingmar; Ruehl, Axel; Dwayne Miller, R. J.

2018-06-01

We present the first systematic study of the spatio-spectral polarization properties of a supercontinuum generated in a cubic crystal, yttrium-aluminum garnet (YAG), including a full spectral analysis of the white light core and surrounding ring structure. We observe no depolarization of the supercontinuum, and no spatial dependence of polarization ratios for any wavelength. We discuss the discrepancy of YAG's polarization behavior in the context of well-established results in literature reporting self-induced depolarization in other cubic crystals.

Growth and optical properties of Dy:Y3Al5O12 crystal

NASA Astrophysics Data System (ADS)

Pan, Yuxin; Zhou, Shidong; Li, Dongzhen; Liu, Bin; Song, Qingsong; Liu, Jian; Liu, Peng; Ding, Yuchong; Wang, Xiaodan; Xu, Xiaodong; Xu, Jun

2018-02-01

High optical quality Dy:Y3Al5O12 (Dy:YAG) crystal has been grown by the Czochralski method. Absorption spectra, fluorescence spectra and fluorescence decay curve of Dy:YAG have been recorded at room temperature. The strongest emission of Dy:YAG crystal is near 583 nm, corresponding to the 4F9/2 → 6H13/2 transition. The Judd-Ofelt parameters Ω2, Ω4 and Ω6 were calculated to be 1.49 × 10-20 cm2, 0.94 × 10-20 cm2 and 3.20 × 10-20 cm2, respectively. The radiative transition rates, branching ratios and the emission cross sections were calculated. The fluorescence and radiative lifetimes are 0.40 ms and 1.02 ms, respectively, resulting in a quantum efficiency of 39.2%. The results indicate that the Dy:YAG crystal would be a promising yellow solid state laser material.

Stable continuous-wave single-frequency Nd:YAG blue laser at 473 nm considering the influence of the energy-transfer upconversion.

PubMed

Wang, Yaoting; Liu, Jianli; Liu, Qin; Li, Yuanji; Zhang, Kuanshou

2010-06-07

We report a continuous-wave (cw) single frequency Nd:YAG blue laser at 473 nm end-pumped by a laser diode. A ring laser resonator was designed, the frequency doubling efficiency and the length of nonlinear crystal were optimized based on the investigation of the influence of the frequency doubling efficiency on the thermal lensing effect induced by energy-transfer upconversion. By intracavity frequency doubling with PPKTP crystal, an output power of 1 W all-solid-state cw blue laser of single-frequency operation was achieved. The stability of the blue output power was better than +/- 1.8% in the given four hours.

Comparative study of optical and scintillation properties of Tm3+:YAG, and Tm3+:LuAG single crystals

NASA Astrophysics Data System (ADS)

Fujimoto, Yutaka; Sugiyama, Makoto; Yanagida, Takayuki; Wakahara, Shingo; Suzuki, Shotaro; Kurosawa, Shunsuke; Chani, Valery; Yoshikawa, Akira

2013-09-01

The optical and scintillation properties of Tm3+-doped yttrium aluminum garnet Y3Al5O12 (YAG) and Tm3+-doped lutetium aluminum garnet Lu3Al5O12 (LuAG) are compared. The Tm3+-doped single crystals were grown by the micro-pulling down (μ-PD) technique. Both crystals demonstrated some emission peaks originated from 4f-4f forbidden transition of Tm3+ under 241Am alpha-ray excitation. The scintillation decay time of Tm3+-doped YAG was similar to that of LuAG. When irradiated by the gamma-rays from a 137Cs source, the relative scintillation light yields of Tm:YAG was 90% greater than that of Tm:LuAG.

Actively Q-switched laser with novel Nd:YAG/YAG polygonal active-mirror

NASA Astrophysics Data System (ADS)

Lang, Ye; Chen, Yanzhong; Ge, Wenqi; He, Jianguo; Zhang, Hongbo; Liao, Lifen; Xin, Jianguo; Zhang, Jian; Fan, Zhongwei

2018-03-01

In this work, we demonstrate an efficient actively Q-switched laser based on a novel crystal Nd:YAG/YAG polygonal active mirror. A passively cooled crystal Nd:YAG/YAG polygonal active mirror with an end pump scheme was used as the gain medium. For the overlap between the TEM00 laser mode and large gain profile, a cavity was carefully designed with a large fundamental mode volume. With a maximum absorbed power of 3.1 W, a 685 mW average output power with a pulse repetition of 5 kHz was attained, and the corresponding optical-optical and slope efficiency were 22.1% and 27.7%, respectively. The pulse width was 133.9 ns. The beam quality (M 2) was 1.561 in the horizontal direction and 1.261 in the vertical direction.

Efficient dual-wavelength laser at 946 and 1064 nm with compactly combined Nd:YAG and Nd:YVO4 crystals

NASA Astrophysics Data System (ADS)

Cho, C. Y.; Chang, C. C.; Chen, Y. F.

2013-04-01

We originally employ a compact combination of a Nd:YAG crystal and a Nd:YVO4 crystal to develop an efficient dual-wavelength laser operating at 946 and 1064 nm. We exploit a short Nd:YAG crystal to generate 946 nm laser by reducing the reabsorption loss and a follow-up Nd:YVO4 crystal to generate a 1064 nm laser by absorbing the residual pump light. The output power ratio between the 946 and 1064 nm emissions can be flexibly adjusted from 0.3 to 0.9 by varying the separation between the two output couplers. At an incident pump power of 17 W, the total output power is generally higher than 5.2 W, with an overall optical-to-optical efficiency greater than 30%.

Thermal Stress Analysis of a Continuous and Pulsed End-Pumped Nd:YAG Rod Crystal Using Non-Classic Conduction Heat Transfer Theory

NASA Astrophysics Data System (ADS)

Mojahedi, Mahdi; Shekoohinejad, Hamidreza

2018-02-01

In this paper, temperature distribution in the continuous and pulsed end-pumped Nd:YAG rod crystal is determined using nonclassical and classical heat conduction theories. In order to find the temperature distribution in crystal, heat transfer differential equations of crystal with consideration of boundary conditions are derived based on non-Fourier's model and temperature distribution of the crystal is achieved by an analytical method. Then, by transferring non-Fourier differential equations to matrix equations, using finite element method, temperature and stress of every point of crystal are calculated in the time domain. According to the results, a comparison between classical and nonclassical theories is represented to investigate rupture power values. In continuous end pumping with equal input powers, non-Fourier theory predicts greater temperature and stress compared to Fourier theory. It also shows that with an increase in relaxation time, crystal rupture power decreases. Despite of these results, in single rectangular pulsed end-pumping condition, with an equal input power, Fourier theory indicates higher temperature and stress rather than non-Fourier theory. It is also observed that, when the relaxation time increases, maximum amounts of temperature and stress decrease.

Growth and lasing of single crystal YAG fibers with different Ho3+ concentrations

NASA Astrophysics Data System (ADS)

Bera, Subhabrata; Nie, Craig D.; Soskind, Michael G.; Li, Yuan; Harrington, James A.; Johnson, Eric G.

2018-01-01

A method to grow single crystal (SC) yttrium aluminum garnet (YAG) fibers with varied rare-earth ion dopant concentration has been proposed. Crystalline holmium aluminum garnet (HoAG), prepared via sol-gel process, was dip-coated on to previously grown SC YAG fibers. The HoAG coated SC YAG fiber preforms were re-grown to a smaller diameter using the laser heated pedestal growth (LHPG) technique. The final dopant concentration of the re-grown SC fiber was varied by changing the number of HoAG coatings on the preform. 120 μm diameter SC Ho:YAG fibers with four different dopant concentrations were grown. Lasing was demonstrated at 2.09 μm for these fibers. A maximum of 58.5% optical-to-optical slope efficiency was obtained.

Comparative study of blue laser diode driven cerium-doped single crystal phosphors in application of high-power lighting and display technologies

NASA Astrophysics Data System (ADS)

Balci, Mustafa H.; Chen, Fan; Cunbul, A. Burak; Svensen, Øyvind; Akram, M. Nadeem; Chen, Xuyuan

2018-02-01

Cerium-doped single crystals (Ce:LuAG, Ce:YAG, Ce:GAGG, Ce:GdYAG) have been investigated as stationary phosphor candidates for blue laser driven solid-state lighting without heat sink. The luminous properties of the single crystals are superior compared to the commercial ceramic powder phosphor wheels (Ce3+: Y3Al5O12). The high-power blue laser diode driven temperature increase of the crystals versus quantum efficiency is experimentally measured and discussed. We have carried out realistic measurements at high excitation power levels and at high temperatures. Limitation of phosphors as stationary sources is determined for commercial usage. The measurements were done without any heat sink to see the relative comparison of SCPs in the worst-case scenarios. The results indicate that Gd and Ga addition decreases the luminescence quenching temperature. Based on their superior properties, these single crystals can serve as potential phosphor candidates for high-power blue diode laser driven picture projectors for the green and red channels.

Influence of bis-thiourea nickel nitrate on the structural, optical, electrical, thermal and mechanical behavior of a KDP single crystal for NLO applications

NASA Astrophysics Data System (ADS)

Rasal, Y. B.; Shaikh, R. N.; Shirsat, M. D.; Kalainathan, S.; Hussaini, S. S.

2017-03-01

A single crystal of bis-thiourea nickel nitrate (BTNN) doped potassium dihydrogen phosphate (KDP) has been grown from solution at room temperature by a slow evaporation technique. The cell parameters of the grown crystals were determined using single crystal x-ray diffraction analysis. The different functional groups of the grown crystal were confirmed using Fourier transform infrared analysis. The improved optical parameters of the grown crystal have been evaluated in the range of 200-900 nm using UV-visible spectral analysis. The grown crystal was transparent in the entire visible region and the band gap value was found to be 4.96 eV. The influence of BTNN on the third order nonlinear optical properties of KDP crystal has been investigated by means of the Z-scan technique. The second harmonic generation (SHG) efficiency of grown crystal measured using a Nd-YAG laser is 1.98 times higher than that of pure KDP. The third order nonlinear optical susceptibility (χ 3) and nonlinear absorption coefficient (β) of BTNN doped KDP crystal is found to be 1.77  ×  10-5 esu and 5.57  ×  10-6 cm W-1 respectively. The laser damage threshold (LDT) energy for the grown crystal has been measured by using a Q-switched Nd:YAG laser source. The bis-thiourea nickel nitrate shows authoritative impact on the dielectric properties of doped crystal. The influence of bis-thiourea nickel nitrate on the mechanical behavior of KDP crystal has been investigated using Vickers microhardness intender. The thermal behavior of BTNN doped KDP crystal has been analyzed by TGA/DTA analysis.

Growth of single-crystal YAG fiber optics.

PubMed

Nie, Craig D; Bera, Subhabrata; Harrington, James A

2016-07-11

Single-crystal YAG (Y₃Al₅O₁₂) fibers have been grown by the laser heated pedestal growth technique with losses as low as 0.3 dB/m at 1.06 μm. These YAG fibers are as long as about 60 cm with diameters around 330 μm. The early fibers were grown from unoriented YAG seed fibers and these fibers exhibited facet steps or ridges on the surface of the fiber. However, recently we have grown fibers using an oriented seed to grow step-free fibers. Scattering losses made on the fibers indicate that the scattering losses are equal to about 30% of the total loss.

Q-switched Nd:YAG/V:YAG microchip 1338 nm laser for laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Šulc, Jan; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav

2017-12-01

Q-switched microchip laser emitting radiation at wavelength 1338nm was tested as a radiation source for laser induced breakdown spectroscopy (LIBS). This laser used sandwich crystal which combined in one piece the cooling part (undoped YAG crystal 4mm long), the active laser part (Nd:YAG crystal 12mm long), and the saturable absorber (V:YAG crystal 0.7mm long). The diameter of this crystal was 5 mm. The microchip resonator consisted of dielectric mirrors directly deposited on the monolith crystal surfaces. The pump mirror (HT @ 808 nm, HR @ 1.3 ¹m) was placed on the undoped YAG part. The output coupler (R = 90% @ 1338 nm) was placed on the V:YAG part. The fibre-coupled 808nm pumping laser diode was operating in pulsed regime (rep. rate 250 Hz, pulse width 300 ¹s, pulse energy 6 mJ). Using this pumping, stable and high reproducible Q-switched pulses were generated at wavelength 1338 nm. Pulse length was 6.2 ns (FWHM) and the mean output power was 33mW. The single pulse energy and peak power was 0.13mJ and 21kW, respectively. Laser was operating in fundamental TEM00 mode. The laser radiation was focused on a tested sample using single plano-convex lens (focal length 75 mm). The focal spot radius was 40 ¹m. The corresponding peak-power density was 0.83GW/cm2. The laser induced break-down was successfully reached and corresponding laser-induced plasma spectra were recorded for set of metallic elements (Cu, Ag, Au, In, Zn, Al, Fe, Ni, Cr) and alloys (Sn-Pb solder, duralumin, stainless-steel, brass). To record the spectra, StellarNet BLACK-Comet concave grating CCD-based spectrometer was used without any special collimation optics. Thanks to used laser wavelength far from the detector sensitivity, no special filtering was needed to overcome the CCD dazzling. The constructed laser could significantly improve repletion-rate of up-to-date LIBS devices.

Effects of carbon dioxide, Nd:YAG and carbon dioxide-Nd:YAG combination lasers at high energy densities on synthetic hydroxyaptite.

PubMed

Meurman, J H; Voegel, J C; Rauhamaa-Mäkinen, R; Gasser, P; Thomann, J M; Hemmerle, J; Luomanen, M; Paunio, I; Frank, R M

1992-01-01

The aim of this study was to determine the crystalline structure and chemical alterations of synthetic hydroxyapatite after irradiation with either CO2, Nd:YAG or CO2-Nd:YAG combination lasers at high energy densities of 500-3,230 J.cm2. Further, dissolution kinetics of the lased material were analysed and compared with those of unlased apatite. Electron microscopy showed that the lased material consisted of two kinds of crystals. From the micrographs their diameters varied from 600 to 1,200 A and from 3,000 to 6,000 A, respectively. The larger crystals showed 6.9-Angström periodic lattice fringes in the transmission electron microscope. alpha-Tricalcium phosphate (TCP) was identified by X-ray diffraction. Selective-area electron diffraction identified the large crystals to consist of tricalcium phosphate while the smaller crystals were probably hydroxyapatite. Assays of dissolution kinetics showed that at these high energy densities lased material dissolved more rapidly than unlased synthetic hydroxyapatite due to the higher solubility of TCP.

Highly efficient solar-pumped Nd:YAG laser.

PubMed

Liang, Dawei; Almeida, Joana

2011-12-19

The recent progress in solar-pumped laser with Fresnel lens and Cr:Nd:YAG ceramic medium has revitalized solar laser researches, revealing a promising future for renewable reduction of magnesium from magnesium oxide. Here we show a big advance in solar laser collection efficiency by utilizing an economical Fresnel lens and a most widely used Nd:YAG single-crystal rod. The incoming solar radiation from the sun is focused by a 0.9 m diameter Fresnel lens. A dielectric totally internally reflecting secondary concentrator is employed to couple the concentrated solar radiation from the focal zone to a 4 mm diameter Nd:YAG rod within a conical pumping cavity. 12.3 W cw laser power is produced, corresponding to 19.3 W/m(2) collection efficiency, which is 2.9 times larger than the previous results with Nd:YAG single-crystal medium. Record-high slope efficiency of 3.9% is also registered. Laser beam quality is considerably improved by pumping a 3 mm diameter Nd:YAG rod.

Scanning electron microscope comparative surface evaluation of glazed-lithium disilicate ceramics under different irradiation settings of Nd:YAG and Er:YAG lasers.

PubMed

Viskic, Josko; Jokic, Drazen; Jakovljevic, Suzana; Bergman, Lana; Ortolan, Sladana Milardovic; Mestrovic, Senka; Mehulic, Ketij

2018-01-01

To evaluate the surface of glazed lithium disilicate dental ceramics after irradiation under different irradiation settings of Nd:YAG and Er:YAG lasers using a scanning electron microscope (SEM). Three glazed-press lithium disilicate ceramic discs were treated with HF, Er:YAG, and Nd:YAG, respectively. The laser-setting variables tested were laser mode, repetition rate (Hz), power (W), time of exposure (seconds), and laser energy (mJ). Sixteen different variable settings were tested for each laser type, and all the samples were analyzed by SEM at 500× and 1000× magnification. Surface analysis of the HF-treated sample showed a typical surface texture with a homogenously rough pattern and exposed ceramic crystals. Er:YAG showed no effect on the surface under any irradiation setting. The surface of Nd:YAG-irradiated samples showed cracking, melting, and resolidifying of the ceramic glaze. These changes became more pronounced as the power increased. At the highest power setting (2.25 W), craters on the surface with large areas of melted or resolidified glaze surrounded by globules were visible. However, there was little to no exposure of ceramic crystals or visible regular surface roughening. Neither Er:YAG nor Nd:YAG dental lasers exhibited adequate surface modification for bonding of orthodontic brackets on glazed lithium disilicate ceramics compared with the control treated with 9.5% HF.

Over 0.5 MW green laser from sub-nanosecond giant pulsed microchip laser

NASA Astrophysics Data System (ADS)

Zheng, Lihe; Taira, Takunori

2016-03-01

A sub-nanosecond green laser with laser head sized 35 × 35 × 35 mm3 was developed from a giant pulsed microchip laser for laser processing on organic superconducting transistor with a flexible substrate. A composite monolithic Y3Al5O12 (YAG) /Nd:YAG/Cr4+:YAG/YAG crystal was designed for generating giant pulsed 1064 nm laser. A fibercoupled 30 W laser diode centered at 808 nm was used with pump pulse duration of 245 μs. The 532 nm green laser was obtained from a LiB3O5 (LBO) crystal with output energy of 150 μJ and pulse duration of 268 ps. The sub-nanosecond green laser is interesting for 2-D ablation patterns.

Kinetics and pathways for crystallization of amorphous mullite and YAG

NASA Astrophysics Data System (ADS)

Johnson, Bradley Richard

The crystallization behavior of quenched mullite (3Al2O 3•2SiO2) and YAG (Y3Al5O 12) composition glasses (made using containerless methods) were characterized with the ultimate goal of producing single crystal, structural, ceramic oxide fibers from these materials. The kinetics for crystallization were determined from thermal analysis experiments. From the results, time-temperature-transformation (TTT) curves were calculated. The crystallization pathways were determined by examining the crystal structure, microstructure, and chemical composition of heat treated specimens using x-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A machine was also designed and built to facilitate controlled crystallization of amorphous fibers. Quenched, Y3Al5O12 composition beads crystallized at temperatures as low as 840°C. The as-received specimens contained a few, small YAG crystals, in addition to a mixture of different amorphous phases. The coexistence of two different amorphous phases of the same composition, but having different densities is termed polyamorphism, and this has been reported to occur in Y3Al5O12 composition quenched melts. Although various crystallization pathways have been reported for chemically synthesized YAG precursors, these specimens crystallized directly into YAG, which was the only phase formed. Quenched, 3Al2O3•2SiO2 composition mullite beads and fibers crystallized at temperatures as low as 920°C. Due to phase separation in the quenched melts, multiple phases with slightly different compositions and different crystallization activation energies crystallized. These phases were not equilibrium, 3:2 mullite, but metastable, alumina-rich, pseudotetragonal mullite. The residual, amorphous, silica-rich phase existed as numerous, 7--10 nm sized inclusions embedded within pseudotetragonal mullite. A large amount of internal strain was detected in pseudotetragonal mullite, and the source of this strain was suggested to be the embedded, silica-rich inclusions. Pseudotetragonal mullite gradually converted to equilibrium, orthorhombic, 3:2 mullite between 1000--1400°C. This was characterized by assimilation of the embedded, silica-rich inclusions and the elimination of internal strain. Additionally, recrystallization of numerous, small, strain- and inclusion-free, 3:2 mullite grains was observed to occur as the process proceeded to completion.

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.

Investigation of YAG:Ce Scintillating Fiber Properties Using Silicon Photomultipliers

DTIC Science & Technology

2011-03-01

Maj Benjamin R. Kowash (Chairman) Date ____________________________________ ________________ Lt Col Michael R. Hawks...Member) Date ____________________________________ ________________ Abigail Bickley, PhD (Member) Date iv AFIT/GNE/ENP/11-M11 Abstract...Properties of Rare Earth Garnet Crystals ...........................................................36 Page vii 4. 2. Properties of the

Thermal effects on cavity stability of chromium- and neodymium-doped gadolinium scandium gallium garnet laser under solar-simulator pumping

NASA Technical Reports Server (NTRS)

Kim, Kyong H.; Venable, Demetrius D.; Brown, Lamarr A.; Lee, Ja H.

1991-01-01

Results are presented on testing a Cr- and Nd-codoped Gd-Sc-Ga-garnet (Cr:Nd:GSGG) crystal and a Nd:YAG crystal (both of 3.2 mm diam and 76-mm long) for pulsed and CW laser operations using a flashlamp and solar simulator as pumping sources. Results from experiments with the flashlamp show that, at pulse lengths of 0.11, 0.28, and 0.90 ms, the slope efficiency of the Cd:Nd:GSGG crystal was higher than that of the Nd:YAG crystal and increased with pulse width. With the solar simulator, however, the CW laser operation of the Cr:Nd:GSGG crystal was limited to intensities not greater than 1500 solar constants, while the Nd:YAG laser successfully performed for all pump beam intensities available. It was found that the exposure for several minutes of the Cr:Nd:GSGG crystal to pump beam intensity of 3000 solar constants led to its damage by thermal cracking, indicating that a better solar-pumped CW laser performance may be difficult to realize with rod geometry.

Power scaling of supercontinuum seeded megahertz-repetition rate optical parametric chirped pulse amplifiers.

PubMed

Riedel, R; Stephanides, A; Prandolini, M J; Gronloh, B; Jungbluth, B; Mans, T; Tavella, F

2014-03-15

Optical parametric chirped-pulse amplifiers with high average power are possible with novel high-power Yb:YAG amplifiers with kW-level output powers. We demonstrate a compact wavelength-tunable sub-30-fs amplifier with 11.4 W average power with 20.7% pump-to-signal conversion efficiency. For parametric amplification, a beta-barium borate crystal is pumped by a 140 W, 1 ps Yb:YAG InnoSlab amplifier at 3.25 MHz repetition rate. The broadband seed is generated via supercontinuum generation in a YAG crystal.

Crystalline perfection and optical studies of L-Histidinium dihydrogen phosphate orthophosphoric acid (LHDP) single crystals

NASA Astrophysics Data System (ADS)

Ittyachan, Reena; Arunkumar, A.; Bhagavannarayana, G.

2015-10-01

Single crystals of L-Histidinium dihydrogenphosphate orthophosphoric acid (LHDP) were grown by slow evaporation solution growth technique. The grown crystals were confirmed by single crystal X-ray diffraction techniques. The HRXRD rocking curve measurements revealed the crystalline perfection of grown crystal and the absence of structural grain boundaries. The lower optical cut-off wavelength for this crystal was observed at 240 nm. The third order nonlinear refractive index (n2), nonlinear absorption coefficient (β) and susceptibility (χ(3)) were calculated by Z-scan studies using Nd: YAG laser as a source. The single shot laser damage threshold of grown crystal was measured to be 6.286 GW/cm2 using Nd: YAG laser.

High-efficient Nd:YAG microchip laser for optical surface scanning

NASA Astrophysics Data System (ADS)

Šulc, Jan; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav

2017-12-01

A CW operating, compact, high-power, high-efficient diode pumped 1064nm laser, based on Nd:YAG active medium, was developed for optical surface scanning and mapping applications. To enhance the output beam quality, laser stability, and compactness, a microchip configuration was used. In this arrangement the resonator mirrors were deposited directly on to the laser crystal faces. The Nd-doping concentration was 1 at.% Nd/Y. The Nd:YAG crystal was 5mm long. The laser resonator without pumping radiation recuperation was investigated {the output coupler was transparent for pumping radiation. For the generated laser radiation the output coupler reflectivity was 95%@1064 nm. The diameter of the samples was 5 mm. For the laser pumping two arrangements were investigated. Firstly, a fibre coupled laser diode operating at wavelength 808nm was used in CW mode. The 400 ¹m fiber was delivering up to 14W of pump power amplitude to the microchip laser. The maximum CW output power of 7.2W @ 1064nm in close to TEM00 beam was obtained for incident pumping power 13.7W @ 808 nm. The differential efficiency in respect to the incident pump power reached 56 %. Secondly, a single-emitter, 1W laser diode operating at 808nm was used for Nd:YAG microchip pumping. The laser pumping was directly coupled into the microchip laser using free-space lens optics. Slope efficiency up to 70% was obtained in stable, high-quality, 1064nm laser beam with CW power up to 350mW. The system was successfully used for scanning of super-Gaussian laser mirrors reflectivity profile.

Modeling of thermal lensing in a [1 1 1]-cut Nd:YAG rod with temperature-dependent parameters and different pumping profiles

NASA Astrophysics Data System (ADS)

Bričkus, D.; Dement'ev, A. S.

2017-05-01

Temperature dependences of the thermo-optical coefficients of YAG crystals are often neglected when thermal lensing in laser rods is investigated, though their influence is very significant. It is especially significant for transversally non-uniform thermal loading. An analytical solution of the heat transfer equation with only the radial heat flow is found in the integral form, which is very convenient for numerical simulations. Uniform, top-hat, parabolic, Gaussian, super-Gaussian and annular heat source distributions are used in the calculations. The generalization of the thermally-induced refractive index change for long enough [1 1 1]-cut YAG rods to the case of temperature-dependent YAG parameters is developed and applied to the calculation of the corresponding optical path differences. Different definitions of the optical power of the aberrated thermal lens (TL) are discussed in detail. It is shown that for each of the heat source distributions, the temperature dependences of the YAG parameters significantly increase (1.5-1.8 times) the paraxial optical power of the induced TL.

Passively Q-switched Nd:YAG/Cr(4+):YAG bonded crystal microchip laser operating at 1112  nm and its application for second-harmonic generation.

PubMed

Fu, S G; Ouyang, X Y; Liu, X J

2015-10-10

A passively Q-switched Nd:YAG/Cr⁴⁺:YAG microchip laser operating at 1112 nm is demonstrated. Under a pump power of 5.5 W, a maximum average output power of 623 mW was obtained with T=6% output coupler, corresponding to an optical-to-optical conversion efficiency of 11.3% and a slope efficiency of 19.5%. The minimum pulse width was 2.8 ns, the pulse energy and peak power were 39.3 μJ and 14 kW, respectively. Additionally, based on the 1112 nm laser, a 230 mW 556 nm green-yellow laser was achieved within an LBO crystal.

An intra-cavity pumped dual-wavelength laser operating at 946 nm and 1064 nm with Nd:YAG  +  Nd:YVO4 crystals

NASA Astrophysics Data System (ADS)

He-Dong, Xiao; Yuan, Dong; Yu, Liu; Shu-Tao, Li; Yong-Ji, Yu; Guang-Yong, Jin

2016-09-01

We adopt a compact intra-cavity pumped structure of Nd:YAG and Nd:YVO4 crystals to develop an efficient dual-wavelength laser that operates at 946 nm and 1064 nm. A 808 nm laser diode is used to pump the Nd:YAG crystal, which emits at 946 nm, and the Nd:YVO4 crystal, which emits at 1064 nm, is intra-cavity pumped at 946 nm. In order to avoid unnecessary pump light passing though the Nd:YAG crystal, reaching the Nd:YVO4 crystal and having an impact on the cavity pump, the two crystals are placed as far from one another as possible in this experiment. The output power at 1064 nm can be adjusted from 1 W-2.9 W by varying the separation between the two crystals. A total output power of 4 W at the dual-wavelengths is achieved at an incident pump power of 30.5 W, where the individual output powers for the 946 nm and 1064 nm emissions are 1.1 W and 2.9 W, respectively.

Thermo-optical and spectroscopic properties of Nd:YAG fine grain ceramics: towards a better performance than the Nd:YAG laser crystals

NASA Astrophysics Data System (ADS)

Santos, W. Q.; Benayas, A.; Jaque, D.; García-Solé, J.; Catunda, T.; Jacinto, C.

2016-02-01

In this work, we investigated the thermo-optical properties of highly Nd3+ doped YAG ceramics. The normalized lifetime thermal lens method was used to obtain the fluorescence quantum efficiency (η) versus Nd3+ concentration (N t) and to study the energy transfer microparameters C DD and C DA. The N t dependence of η was compared to the results of the previous literature. The C DA found is very similar to those of the previous literature, while the C DD is very different and higher than C DA, although the main dependence of η with N t is assigned to C DA. The figure of merit (η.N t versus N t) indicated a maximum around 3.8 at.% Nd2O3, which in addition to the very low ds/dT value, evidences the YAG ceramic as an excellent material for an ultra-high-power microchip laser system and for devices requiring minimum pump-induced local heating generation.

Synthesis, analysis and processing of novel materials in the yttrium oxide-aluminum oxide system

NASA Astrophysics Data System (ADS)

Marchal, Julien Claudius

In the current work, liquid feed flame spray pyrolysis (LF-FSP) was used to create three novel nanopowders in the Y2O3-Al 2O3 system: alpha-Al2O3, YAG (garnet Y3Al5O12) and hexagonal Y3Al 5O12. For example, LF-FSP combustion of metalloorganic yttrium and aluminum precursors in a 3/5 ratio forms hexagonal Y3Al5O 12, a newly discovered crystalline phase detailed in this work. The resulting 15-35 nm average particle size, single crystal nanopowders were characterized by TGA-DTA, XRD, HR-TEM, electron diffraction and FTIR. The data was used to establish a model for the crystal structure of this new phase (hexagonal, with crystal parameter of a = 0.736 nm, c = 1.052) consisting of a superlattice of substituted hexagonal YAlO3. YAG has been extensively investigated for its applications as scintillators, phosphors and as a laser host. Fully dispersible, unaggregated single crystal YAG nanopowders with average particle sizes of 35-50 nm were obtained from hexagonal Y3Al5O12 after annealing at 850°C-1200°C (for 2h-8d). The resulting YAG nanopowder was processed into green bodies using cold isostatic pressing after adding binders. 99%+ dense monoliths were obtained after sintering at 1400°C in vacuum (6-8 h), while maintaining grain sizes < 500 nm. The ability to sinter while keeping sub-micron grains differs from present techniques (where translucency is obtained through exaggerated grain growth to 5-10 microns) reported in the literature for sintering polycrystalline YAG, and is the first step for improving polycrystalline YAG laser host optical properties. LF-FSP processing of transition Al2O3 nanopowders converts them to single crystal alpha-Al2O3 nanopowders, previously thought impossible to obtain. The alpha-Al2O 3 nanopowders thus obtained, consist of unaggregated 30-40 nm single particles. These nanopowders were characterized by XRD, HR-TEM, SEM, DLS, FTIR. Green bodies of alpha-Al2O3 nanopowders were sintered to 99% density without sintering aids at 1400°C (6-8 h). After HIPing at 1400°C and 138 MPa, the pellets exhibited some transparency. LF-FSP thus allows synthesis of large quantities of previously unavailable alpha-Al 2O3 nanopowders necessary for developing nanograined alpha-Al 2O3 ceramic monoliths for transparent armors, polycrystalline laser hosts and prosthetic implants. Most importantly, it demonstrates the use of LF-FSP to modify the crystalline phase of nanopowders, without causing aggregation.

YAG glass-ceramic phosphor for white LED (II): luminescence characteristics

NASA Astrophysics Data System (ADS)

Tanabe, Setsuhisa; Fujita, Shunsuke; Yoshihara, Satoru; Sakamoto, Akihiko; Yamamoto, Shigeru

2005-09-01

Optical properties of the Ce:YAG glass-ceramic (GC) phosphor for the white LED were investigated. Concentration dependence of fluorescence intensity of Ce3+:5d→4f transition in the GC showed a maximum at 0.5mol%Ce2O3. Quantum efficiency (QE) of Ce3+ fluorescence in the GC materials, the color coordinate and luminous flux of electroluminescence of LED composite were evaluated with an integrating sphere. QE increased with increasing ceramming temperature of the as-made glass. The color coordinates (x,y) of the composite were increased with increasing thickness of the GC mounted on a blue LED chip. The effect of Gd2O3 substitution on the optical properties of the GC materials was also investigated. The excitation and emission wavelength shifted to longer side up to Gd/(Y+Gd)=0.40 in molar composition. As a result, the color coordinate locus of the LED with various thickness of the GdYAG-GC shifted to closer to the Planckian locus for the blackbody radiation. These results were explained by partial substitution of Gd3+ ions in the precipitated YAG micro-crystals, leading to the increase of lattice constant of unit cell, which was confirmed by X-ray diffraction.

Direct solar-pumped iodine laser amplifier

NASA Technical Reports Server (NTRS)

Han, Kwang S.

1987-01-01

This semiannual progress report covers the period from March 1, 1987 to September 30, 1987 under NASA grant NAG1-441 entitled 'Direct solar-pumped iodine laser amplifier'. During this period Nd:YAG and Nd:Cr:GSGG crystals have been tested for the solar-simulator pumped cw laser, and loss mechanisms of the laser output power in a flashlamp-pumped iodine laser also have been identified theoretically. It was observed that the threshold pump-beam intensities for both Nd:YAG and Nd:Cr:GSGG crystals were about 1000 solar constants, and the cw laser operation of the Nd:Cr:GSGG crystal was more difficult than that of the Nd:YAG crystal under the solar-simulator pumping. The possibility of the Nd:Cr:GSGG laser operation with a fast continuously chopped pumping was also observed. In addition, good agreement between the theoretical calculations and the experimental data on the loss mechanisms of a flashlamp-pumped iodine laser at various fill pressures and various lasants was achieved.

CIE colorimetric system fails to calculate the chroma of a Nd:YAG crystal under the fluorescent illuminant F7

NASA Astrophysics Data System (ADS)

Liu, Yan; Chen, Qinghan; Bu, Xianhui; Feng, Pingyun

2002-06-01

The rare earth element neodymium doped yttrium aluminum garnet (Nd:YAG) is a laser crystal widely used for producing laser in the infrared range. Neodymium causes many characteristic absorption peaks in the transmittance spectrum of the Nd:YAG crystal in the visible range. The crystal appears pink under daylight and incandescent light, and colorless under fluorescent light. The colorimetric calculation results of chroma under the CIE standard fluorescent illuminant F7 do not agree with the color appearance under fluorescent light. The calculated chroma values should be near zero to agree with a colorless appearance, but it is actually 11.79 in the CIELAB color space. This failure of the colorimetric calculation is caused by the color matching functions of the CIE colorimetric observers. The color matching functions do not agree with the spectral sensitivity curves of the human eye, especially the x(λ) function does not matches the spectral sensitivity curve of the long wavelength cone photoreceptors.

Periodic grain-boundary formation in a poly-Si thin film crystallized by linearly polarized Nd:YAG pulse laser with an oblique incident angle

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

Kaki, Hirokazu; Horita, Susumu

2005-01-01

We investigated the periodic grain-boundary formation in the polycrystalline silicon film crystallized by a linearly polarized Nd:YAG (where YAG is yttrium aluminum garnet) pulse laser with an oblique incident angle {theta}{sub i}=25 deg. , compared with the normal incident angle {theta}{sub i}=0. The alignment of the grain boundary was uncontrollable and fluctuated in the case of the oblique incident and large irradiation pulse number while that in the case of the normal incident was performed stably. It was found that the main cause for its low controllability was the nonphase matching between the periodic surface corrugation of the crystallized siliconmore » film and the periodic temperature profile induced by the laser irradiation. Also, it was found that, in the case of {theta}{sub i}=25 deg. , the dominant periodic width of the grain boundary depended on the pulse number N. That is, it was around {lambda}/(1+sin {theta}{sub i}) for small N{approx_equal}10 and {lambda}/(1-sin {theta}{sub i}) for large N{approx_equal}100 at the laser wavelength of {lambda}=532 nm. In order to explain this dependence, we proposed a model to take into account the periodic corrugation height proportional to the molten volume of the silicon film, the impediment in interference between the incident beam and diffracted beam on the irradiated surface due to the corrugation height, and the reduction of the liquid surface roughness during melting-crystallization process due to liquid-silicon viscosity.« less

Polycrystalline scintillators for large area detectors in HEP experiments

NASA Astrophysics Data System (ADS)

Dosovitskiy, G.; Fedorov, A.; Karpyuk, P.; Kuznetsova, D.; Mikhlin, A.; Kozlov, D.; Dosovitskiy, A.; Korjik, M.

2017-06-01

After significant increase of the accelerator luminosity throughout the High Luminosity phase of LHC, charged hadrons and neutrons with fluences higher than 1014 p/cm2 per year in the largest pseudo-rapidity regions of the detectors will cause increased radiation damage of materials. Increasing activation of the experimental equipment will make periodical maintenance and replacement of detector components difficult. Therefore, the selected materials for new detectors should be tolerant to radiation damage. Y3Al5O12:Ce (YAG:Ce) crystal was found to be one of the most radiation hard scintillation materials. However, production of YAG:Ce in a single crystalline form is costly, because crystal growth is performed at temperature near 1900°C with a very low rate of transformation of a raw material into a crystal. We propose translucent YAG:Ce ceramics as an alternative cheaper solution. Ceramic samples were sintered up to density ~98% of the theoretical value and were translucent. The samples have demonstrated light yield of 2200 phot./MeV under 662 keV γ-quanta, which gives the expected response to minimum ionizing particle around 3000 phot. for 2 mm thick plate. Scintillation light yield, registered under surface layer excitation with α-particles, was 50-70% higher than for the reference single crystal YAG:Ce.

Development of mid-infrared solid state lasers for spaceborne lidar

NASA Technical Reports Server (NTRS)

Whitney, Donald A.; Kim, Kyong H.

1989-01-01

Laser performance of Ho(3+):Tm(3+):Cr(3+):YAG crystals was investigated under both Cr:GSAG laser and flashlamp pumping. A flashlamp pumped Cr:GSAG laser was built to simulate high power quasi-CW laser diode pumping of a 2.1 micrometer holmium laser. The 2.1 micrometer output laser energy exceeded more than 14 mJ, the highest value reported to date under laser pumping near 785 nm. This was obtained in a pulse length of nearly 650 microsec from a 3 x 3 mm Ho:Tm:Cr:YAG rod by using the flashlamp-pumped Cr:CSAG laser as a pumping source at the diode laser wavelength, 785 micrometers. In addition, Ho:Tm:Cr:YAG crystals with various Tm(3+) concentrations were evaluated for flashlamp-pumped normal mode and Q-switched 2.1 micrometer laser operations under a wide variety of experimental conditions in order to understand internal dynamic processes among the ions and to determine an optimum lasing condition. An increase of the laser slope efficiency was observed with the increase of the Tm(3+) concentration from 2.5 to 4.5 atomic percent. The thermal dependence of the laser performance was also investigated. Q-switched laser output energies corresponding to nearly 100 percent of the normal-mode laser energies were obtained in a strong single spike of 200 ns pulse length by optimizing the opening time of a lithium niobate Q-switch.

Laser performance and modeling of RE3+:YAG double-clad crystalline fiber waveguides

NASA Astrophysics Data System (ADS)

Li, Da; Lee, Huai-Chuan; Meissner, Stephanie K.; Meissner, Helmuth E.

2018-02-01

We report on laser performance of ceramic Yb:YAG and single crystal Tm:YAG double-clad crystalline fiber waveguide (CFW) lasers towards the goal of demonstrating the design and manufacturing strategy of scaling to high output power. The laser component is a double-clad CFW, with RE3+:YAG (RE = Yb, Tm respectively) core, un-doped YAG inner cladding, and ceramic spinel or sapphire outer cladding. Laser performance of the CFW has been demonstrated with 53.6% slope efficiency and 27.5-W stable output power at 1030-nm for Yb:YAG CFW, and 31.6% slope efficiency and 46.7-W stable output power at 2019-nm for Tm:YAG CFW, respectively. Adhesive-Free Bond (AFB®) technology enables a designable refractive index difference between core and inner cladding, and designable core and inner cladding sizes, which are essential for single transverse mode CFW propagation. To guide further development of CFW designs, we present thermal modeling, power scaling and design of single transverse mode operation of double-clad CFWs and redefine the single-mode operation criterion for the double-clad structure design. The power scaling modeling of double-clad CFW shows that in order to achieve the maximum possible output power limited by the physical properties, including diode brightness, thermal lens effect, and simulated Brillion scattering, the length of waveguide is in the range of 0.5 2 meters. The length of an individual CFW is limited by single crystal growth and doping uniformity to about 100 to 200 mm lengths, and also by availability of starting crystals and manufacturing complexity. To overcome the limitation of CFW lengths, end-to-end proximity-coupling of CFWs is introduced.

Structural, thermal and optical properties of a semiorganic nonlinear optical single crystal: glycine zinc sulphate.

PubMed

Balakrishnan, T; Ramamurthi, K

2007-10-01

Glycine zinc sulphate salt was synthesized and the solubility and metastable zonewidth were estimated from the aqueous solution. Single crystals of glycine zinc sulphate were grown by solvent evaporation method from aqueous solution. Grown crystals were characterized by X-ray diffraction and FT-IR spectral analyses. The range and percentage of optical transmission was ascertained by recording UV-vis-NIR spectrum. Thermal properties of the crystal were investigated by thermogravimetric analysis. Microhardness study was carried out on (01-1) face of the grown crystal. Its powder second harmonic generation efficiency was measured using Nd:YAG laser and the value was observed to be 0.7 times that of potassium dihydrogen orthophosphate.

Nondestructive method for chemically machining crucibles or molds from their enclosed ingots and castings

DOEpatents

Stout, Norman D.; Newkirk, Herbert W.

1991-01-01

An inventive method is described for chemically machining rhenium, rhenium and tungsten alloy, and group 5b and 6b crucibles or molds from included ingots and castings comprised of oxide crystals including YAG and YAG based crystals, garnets, corundum crystals, and ceramic oxides. A mixture of potassium hydroxide and 15 to 90 weight percent of potassium nitrate is prepared and maintained at a temperature above melting and below the lower of 500 degrees centigrade or the temperature of decomposition of the mixture. The enveloping metal container together with its included oxide crystal object is rotated within the heated KOH-KNO.sub.3 mixture, until the container is safely chemically machined away from the included oxide crystal object.

Sintering and microstructure of silicon carbide ceramic with Y3Al5O12 added by sol-gel method*

PubMed Central

Guo, Xing-zhong; Yang, Hui

2005-01-01

Silicon carbide (SiC) ceramic with YAG (Y3Al5O12) additive added by sol-gel method was liquid-phase sintered at different sintering temperatures, and the sintering mechanism and microstructural characteristics of resulting silicon carbide ceramics were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and elemental distribution of surface (EDS). YAG (yttrium aluminum garnet) phase formed before the sintering and its uniform distribution in the SiC/YAG composite powder decreased the sintering temperature and improved the densification of SiC ceramic. The suitable sintering temperature was 1860 °C with the specimen sintered at this temperature having superior sintering and mechanical properties, smaller crystal size and fewer microstructure defects. Three characteristics of improved toughness of SiC ceramic with YAG added by sol-gel method were microstructural densification, main-crack deflection and crystal ‘bridging’. PMID:15682507

Cladding-like waveguide fabricated by cooperation of ultrafast laser writing and ion irradiation: characterization and laser generation.

PubMed

Lv, Jinman; Shang, Zhen; Tan, Yang; Vázquez de Aldana, Javier Rodríguez; Chen, Feng

2017-08-07

We report the surface cladding-like waveguide fabricated by the cooperation of the ultrafast laser writing and the ion irradiation. The ultrafast laser writes tracks near the surface of the Nd:YAG crystal, constructing a semi-circle columnar structure with a decreased refractive index of - 0.00208. Then, the Nd:YAG crystal is irradiated by the Carbon ion beam, forming an enhanced-well in the semi-circle columnar with an increased refractive index of + 0.0024. Tracks and the enhanced-well consisted a surface cladding-like waveguide. Utilizing this cladding-like waveguide as the gain medium for the waveguide lasing, optimized characterizations were observed compared with the monolayer waveguide. This work demonstrates the refractive index of the Nd:YAG crystal can be well tailored by the cooperation of the ultrafast laser writing and the ion irradiation, which provides an convenient way to fabricate the complex and multilayered photonics devices.

Single-Frequency Nd:YAG Ring Lasers with Corner Cube Prism

NASA Astrophysics Data System (ADS)

Wu, Ke-Ying; Yang, Su-Hui; Zhao, Chang-Ming; Wei, Guang-Hui

2000-10-01

We put forward another form of the non-planar ring lasers, in which the corner cube prism is the key element and the Nd:YAG crystal is used as a Porro prism to enclose the ring resonator. The phase shift due to the total internal reflections of the three differently orientated reflection planes of the corner cube prism, Faraday rotation in the Nd:YAG crystal placed in a magnetic field and the different output coupling in S and P polarization form an optical diode and enforce the single-frequency generating power. A round trip analysis of the polarization properties of the resonator is made by the evaluation of Jones matrix.

Passive Q switching of a solar-pumped Nd:YAG laser.

PubMed

Lando, M; Shimony, Y; Noter, Y; Benmair, R M; Yogev, A

2000-04-20

Passive Q switching is a preferable choice for switching the Q factor of a solar-pumped laser because it requires neither a driver nor an electrical power supply. The superior thermal characteristics and durability of Cr(4+):YAG single crystals as passive Q switches for lamp and diode-pumped high-power lasers has been demonstrated. Here we report on an average power of 37 W and a switching efficiency of 80% obtained by use of a solar-pumped Nd:YAG laser Q switched by a Cr(4+):YAG saturable absorber. Concentration of the pumping solar energy on the laser crystal was obtained with a three-stage concentrator, composed of 12 heliostats, a three-dimensional compound parabolic concentrator (CPC) and a two-dimensional CPC. The water-cooled passive Q switch also served as the laser rear mirror. Repetition rates of as much as 50 kHz, at pulse durations between 190 and 310 ns (FWHM) were achieved. From the experimental results, the saturated single-pass power absorption of the Cr(4+):YAG device was estimated as 3 ? 1%.

Effects of nano-YAG (Y 3Al 5O 12) crystallization on the structure and photoluminescence properties of Nd 3+-doped K 2O-SiO 2-Y 2O 3-Al 2O 3 glasses

NASA Astrophysics Data System (ADS)

Tarafder, Anal; Molla, Atiar Rahaman; Karmakar, Basudeb

2010-10-01

Nd 3+-doped precursor glass in the K 2O-SiO 2-Y 2O 3-Al 2O 3 (KSYA) system was prepared by the melt-quench technique. The transparent Y 3Al 5O 12 (YAG) glass-ceramics were derived from this glass by a controlled crystallization process at 750 °C for 5-100 h. The formation of YAG crystal phase, size and morphology with progress of heat-treatment was examined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Fourier transformed infrared reflectance spectroscopy (FT-IRRS). The crystallite sizes obtained from XRD are found to increase with heat-treatment time and vary in the range 25-40 nm. The measured photoluminescence spectra have exhibited emission transitions of 4F 3/2 → 4I J ( J = 9/2, 11/2 and 13/2) from Nd 3+ ions upon excitation at 829 nm. It is observed that the photoluminescence intensity and excited state lifetime of Nd 3+ ions decrease with increase in heat-treatment time. The present study indicates that the incorporation of Nd 3+ ions into YAG crystal lattice enhance the fluorescence performance of the glass-ceramic nanocomposites.

Structured laser gain-medium by new bonding for power micro-laser

NASA Astrophysics Data System (ADS)

Kausas, Arvydas; Zheng, Lihe; Taira, Takunori

2017-02-01

In this work, we have compared the Q-switched performance of single rod crystal to a newly developed distributed face cooling structure. This structure was made by surface activated bonding technology and allowed to combine transparent heatsink to a gain crystal at room temperature. The Sapphire and Nd3+:YAG crystal plates were combined in this fashion to produce eight crystal chip which was further used to obtain Q-switch pulses with Cr4+:YAG crystal as saturable absorber. Energy of 9 mJ and pulse duration of 815 ps were achieved. Although the energy obtained with single rod system was 10 mJ, the degradation of the beam prevents such crystal to be used in further applications. This is the first demonstration of distributed face cooling system outperformed conventionally single rod system.

Development of mid-infrared solid state lasers for spaceborne lidar

NASA Technical Reports Server (NTRS)

Whitney, Donald A.

1990-01-01

Researchers investigated laser performance of Ho(3+):Tm(3+):Cr(3+):YAG crystals under both Cr:GSAG laser and flashlamp pumping. A flashlamp pumped Cr:GSAG laser was built to simulate high power quasi-CW laser diode pumping of a 2.1 micron holmium laser. The 2.1 micron output laser energy exceeded more than 14 mJ, the highest value reported to date under laser pumping near 785 nm. This was obtained in a pulse length of nearly 650 microns from a 3 x 3 mm Ho:Tm:Cr:YAG rod by using the flashlamp-pumped Cr:GSAG laser as a pumping source at the diode laser wavelength, 785 microns. In addition, Ho:Tm:Cr:YAG crystals with various Tm(3+) concentrations have been evaluated for flashlamp-pumped normal mode and Q-switched 2.1 micron laser operations under a wide variety of experimental conditions in order to understand internal dynamic processes among the ions and to determine an optimum lasing condition. An increase of the laser slope efficiency was observed with the increase of the Tm(3+) concentration from 2.5 atomic percent to 4.5 atomic percent. The thermal dependence of the laser performance was also investigated. Q-switched laser output energies corresponding to nearly 100 percent of the normal-mode laser energies were obtained in a strong single spike of 200 ns pulse length by optimizing the opening time of a lithium niobate Q-switch.

Optimizing alignment and growth of low-loss YAG single crystal fibers using laser heated pedestal growth technique.

PubMed

Bera, Subhabrata; Nie, Craig D; Soskind, Michael G; Harrington, James A

2017-12-10

The effect of misalignments of different optical components in the laser heated pedestal growth apparatus have been modeled using Zemax optical design software. By isolating the misalignments causing the non-uniformity in the melt zone, the alignment of the components was fine-tuned. Using this optimized alignment, low-loss YAG single crystal fibers of 120 μm diameter were grown, with total attenuation loss as low as 0.5 dB/m at 1064 nm.

Modeling Cr-to-Tm and Cr-to-Tm-to-Ho energy transfer in YAG crystals

NASA Technical Reports Server (NTRS)

Swetits, John J.

1991-01-01

A systematic analysis of energy transfer processes in crystals of YAG doped with varying concentrations of Cr and Tm is described. Both spectral measurements and measurements of the temporal response to pulsed excitation are used to give independent determinations of the microscopic interaction parameter for Cr to Tm transfer. The different factors in influencing the temperature dependence of the Cr to Tm transfer are discussed. The dependence of the Tm cross-relaxation rate on Tm concentration is determined.

Diode-pumped quasi-three-level Nd:GdV O4-Nd:YAG sum-frequency laser at 464 nm

NASA Astrophysics Data System (ADS)

Lu, Jie

2014-04-01

We report a laser architecture to obtain continuous-wave (cw) blue radiation at 464 nm. A 808 nm diode pumped a Nd:GdV O4 crystal emitting at 912 nm. A part of the pump power was then absorbed by the Nd:GdV O4 crystal. The remainder was used to pump a Nd:YAG crystal emitting at 946 nm. Intracavity sum-frequency mixing at 912 and 946 nm was then realized in a LiB3O5 (LBO) crystal to produce blue radiation. We obtained a cw output power of 1.52 W at 464 nm with a pump laser diode emitting 18.4 W at 808 nm.

Multi-watt passively Q-switched Yb:YAB/Cr:YAG microchip lasers

NASA Astrophysics Data System (ADS)

Serres, Josep Maria; Loiko, Pavel; Mateos, Xavier; Liu, Junhai; Zhang, Huaijing; Yumashev, Konstantin; Griebner, Uwe; Petrov, Valentin; Aguiló, Magdalena; Díaz, Francesc

2017-02-01

A trigonal 5.6 at.% Yb:YAl3(BO3)4 (Yb:YAB) crystal is employed in continuous-wave (CW) and passively Q-switched microchip lasers pumped by a diode at 978 nm. Using a 3 mm-thick, c-cut Yb:YAB crystal, which has a higher pump absorption efficiency, efficient CW microchip laser operation is demonstrated. This laser generated a maximum output power of 7.18 W at 1041-1044 nm with a slope efficiency η of 67% (with respect to the absorbed pump power) and an almost diffraction-limited beam, M2 x,y < 1.1. Inserting a Cr:YAG saturable absorber, stable passive Q-switching of the Yb:YAB microchip laser was obtained. The maximum average output power from the Yb:YAB/Cr:YAG laser reached 2.82 W at 1042 nm with η = 53% and a conversion efficiency with respect to the CW mode of 65% (when using a 0.7 mm-thick Cr:YAG). The latter corresponded to a pulse duration and energy of 7.1 ns / 47 μJ at a pulse repetition rate (PRR) of 60 kHz. Using a 1.3 mm-thick Cr:YAG, 2.02 W were achieved at 1041 nm corresponding to η = 38%. The pulse characteristics were 4.9 ns / 83 μJ at PRR = 24.3 kHz and the maximum peak power reached 17 kW. Yb:YAB crystals are very promising for compact sub-ns power-scalable microchip lasers.

LD side-pumped Nd:YAG Q-switched laser without water cooling

NASA Astrophysics Data System (ADS)

Ling, Ming; Jin, Guang-yong; Tan, Xue-chun; Wu, Zhi-chao; Liang, Zhu

2009-07-01

A novel LD side-pumped Nd:YAG Q-switched solid-state laser, which made use of the special pumping strcture with conductive cooling instead of water cooling, was investigated.After selecting an appropriate length and diameter of Nd:YAG laser crystal rod and using three groups of laser diode centimeter bar which was composed by 12 laser diodes and uniformly arranged according to the angle of 120°,side-pumping structure of laser was accomplished.Adopting plano-concave resonator ,mending double end face of laser crystal and designing heat-stability resonator made the resonator steadily oscillate.Laser crystal rod which was tight fastened by copper net was conductively cooled and radiation block was furnished on the external of copper net for increasing the radiation capacity.High reflection gold film was plated on the cooling wall in the opposite way of pumping light, so that the laser crystal was uniformly pumped and the laser with low order mode output.Making the use of pillar lens focus and ray trace computing, reasonable parameters were caculated to couple pumping light to laser with high-efficiency.It was the electrooptic Q-switched which was made to be micro-integration eliminating voltage by KD*P crystal that improved the ratio between acting and unacting.Inner heat radiated from laser in good time with TE cooler and the laser ran at constant temperature with water cooling when the big external heat sink emanated a steady heat to periphery. Experiments revealed that the syetem pumping efficiency riseed by 18% and the laser threshold energy was 192 mJ under the condition of this novel pumping structure. The low mode output of 10-12ns pulse width and the maximum output energy of 98 mJ was achieved with an incident pump energy of 720 mJ in 1064nm.The optical-to-optical conversion efficiency was up to 13. 6 %,and the power instability in 24 h was better than +/-1. 7 %.

Stress Tuning of Laser Crystals

NASA Technical Reports Server (NTRS)

Carty, Atherton A.

1995-01-01

The topic of stress tunable laser crystals is addressed in this study with the purpose of determining the piezo-optic coefficients of a new laser material. This data was collected using a quadruple pass birefringence technique because of its high degree of sensitivity relative to the other methods examined including fringe shift analysis using a Mach-Zender interferometer. A green He-Ne laser was passed through a light chopper and Glan-Thompson prism before entering a crystal of Erbium doped Yttrium Aluminum Garnet (Er:YAG) (used in order to validate the experimental technique). The Er:YAG crystal is mounted in a press mechanism and the laser is quadruple passed through test specimen before being returned through the prism and the orthogonally polarized portion of the beam measured with a optical sensor. At a later stage, the Er:YAG crystal was replaced with a new crystal in order to determine the piezo-optic coefficients of this uncharacterized material. The applied load was monitored with the use of a 50 lb. load cell placed in line with the press. Light transmission readings were taken using a lock-in amplifier while load cell measurements were taken with a voltmeter from a 5 volt, 0.5 amp power supply. Despite the fact that an effective crystal press damping system was developed, size limitations precluded the use of the complete system. For this reason, data points were taken only once per full turn so as to minimize the effect of non uniform load application on the collected data. Good correlation was found in the transmission data between the experimentally determined Er:YAG and the previously known peizo-optic constants of non-doped crystal with which it was compared. The variation which was found between the two could be accounted for by the aforementioned presence of Erbium in the experimental sample (for which exact empirical data was not known). The same test procedure was then carried out on a Yttrium Gallium Aluminum garnet (YGAG) for the purpose of establishing values of its unknown piezo-optic constant tensor using experimentally collected transmission data. Significant variation between the piezo-optic constants of YAG and YGAG crystals was found however, the excellent data correlation of separate experimental runs carried out on the YGAG sample demonstrates the validity of these results. The data collected during the stressing of the YGAG was of high quality, however the amount of data collected was somewhat limited by a fracture of YGAG specimen which undoubted altered the crystalline lattice structure and hence precluded any further testing.

Structural, optical, thermal and mechanical properties of Urea tartaric acid single crystals.

PubMed

Vinothkumar, P; Rajeswari, K; Kumar, R Mohan; Bhaskaran, A

2015-06-15

Urea tartaric acid (UT) an organic nonlinear optical (NLO) material was synthesized from aqueous solution and the crystals were grown by the slow evaporation technique. The single crystal X-ray diffraction (XRD) analysis revealed that the UT crystal belongs to the orthorhombic system. The functional groups of UT have been identified by the Fourier transform infrared spectral studies. The optical transparent window in the visible and near the IR regions was investigated. The transmittance of UT has been used to calculate the refractive index (n) as a function of the wavelength. The nonlinear optical property of the grown crystal has been confirmed by the Kurtz powder second harmonic generation test. The birefringence of the crystal was determined using a tungsten halogen lamp source. The laser induced surface damage threshold for the grown crystal was measured using the Nd:YAG laser. The anisotropic in mechanical property of the grown crystals was studied using Vicker's microhardness tester at different planes. The etch pit density of UT crystals was investigated. The thermal behavior of UT was investigated using the TG-DTA and DSC studies. Copyright © 2015 Elsevier B.V. All rights reserved.

High-power laser with Nd:YAG single-crystal fiber grown by the micro-pulling-down technique

NASA Astrophysics Data System (ADS)

Didierjean, Julien; Castaing, Marc; Balembois, François; Georges, Patrick; Perrodin, Didier; Fourmigué, Jean Marie; Lebbou, Kherreddine; Brenier, Alain; Tillement, Olivier

2006-12-01

We present optical characterization and laser results achieved with single-crystal fibers directly grown by the micro-pulling-down technique. We investigate the spectroscopic and optical quality of the fiber, and we present the first laser results. We achieved a cw laser power of 10 W at 1064 nm for an incident pump power of 60 W at 808 nm and 360 kW peak power for 12 ns pulses at 1 kHz in the Q-switched regime. It is, to the best of our knowledge, the highest laser power ever achieved with directly grown single-crystal fibers.

Investigation of 2.1-micron lasing properties of Ho:Tm:Cr:YAG crystals under flash-lamp pumping at various operating conditions

NASA Technical Reports Server (NTRS)

Kim, Kyong H.; Choi, Young S.; Barnes, Norman P.; Hess, Robert V.; Bair, Clayton H.; Brockman, Philip

1993-01-01

Flash-lamp-pumped normal-mode and Q-switched 2.1-micron laser operations of Ho:Tm:Cr:YAG crystals have been evaluated under a wide variety of experimental conditions in order to determine an optimum lasing condition and to characterize the laser outputs. Q-switched laser-output energies equal to, or in some cases exceeding the normal-mode laser energies, were obtained in the form of a strong single spike through an optimization of the opening time of a lithium niobate Q switch. The increase of the normal-mode laser slope efficiency was observed with the increase of the Tm concentration from 2.5 to 4.5 at. pct at operating temperatures from 120 K to near room temperature. Laser transitions were observed only at 2.098 and 2.091 microns under various conditions. The 2.091-micron laser transition appeared to be dominant at high-temperature operations with low-reflective-output couplers.

High-energy azimuthally polarized laser beam generation from an actively Q-switched Nd:YAG laser with c-cut YVO4 crystal

NASA Astrophysics Data System (ADS)

Guo, Jing; Zhang, Baofu; Jiao, Zhongxing; He, Guangyuan; Wang, Biao

2018-05-01

A high-energy, azimuthally polarized (AP) and actively Q-switched Nd:YAG laser is demonstrated. The thermal bipolar lensing effect in the Nd:YAG laser rod is used as a polarization discriminator, and a c-cut YVO4 crystal is inserted into the laser cavity to increase the mode-selecting ability of the cavity for AP mode. The laser generated AP pulses with maximum pulse energy as high as 4.2 mJ. To the best of our knowledge, this is the highest pulse energy obtained from an actively Q-switched AP laser. The pulse energy remained higher than 1 mJ over a wide range of repetition rates from 5 kHz to 25 kHz.

Investigations on nonlinear absorption and nonlinear refraction of a new photonic crystal using Z-scan

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

Shetty, T. C. S., E-mail: tcsshetty@gmail.com; Department of Post Graduate Studies in Physics, St Aloysius College; Sandeep, K. M.

A new photonic material, (2E)-1-(3-chlorophenyl)-3-(2,4-dichlorophenyl)prop-2-en-1-one (DCPP) was synthesized and crystallised at room temperature. The functional groups of synthesised material were confirmed using FT-IR. The third order nonlinear optical (NLO) properties were investigated using Z-scan technique with 5 ns Nd:YAG laser pulses operating at a wavelength of 532 nm. Linear absorption spectrum of DCPP crystals shows an optical transmittance window and a lower cutoff wavelength of absorption at 380 nm. The direct transition band gap energy was determined using Tauc’s plot. The melting point and thermal stability of the crystal have been investigated by thermo gravimetric analysis/differential thermal analysis (TGA/DTA). Themore » Thermo gravimetric curve showed absence of any phase transition before melting point.« less

Surface Thermometry of Energetic Materials by Laser-Induced Fluorescence

DTIC Science & Technology

1989-09-01

at 34 yttrium- aluminum -garnet (Dy:YAG). The simplified energy diagram of Dy:YAG is shown in Fig. 1. Absorbed laser light (at 355 nrm) can 5 excite the...the thermometric technique on a surface similar to that of an energetic material, a thermal-setting plastic supplied by Buehler, Ltd., was employed...temperature over the temperature range of interest. The rare-earth ion dysprosium (Dy) doped into a yttrium- aluminum -garnet (YAG) crystal was I determined

Scintillation properties of selected oxide monocrystals activated with Ce and Pr

NASA Astrophysics Data System (ADS)

Wojtowicz, Andrzej J.; Drozdowski, Winicjusz; Wisniewski, Dariusz; Lefaucheur, Jean-Luc; Galazka, Zbigniew; Gou, Zhenhui; Lukasiewicz, Tadeusz; Kisielewski, Jaroslaw

2006-01-01

In the last 10-15 years there has been a significant effort toward development of new, more efficient and faster materials for detection of ionizing radiation. A growing demand for better scintillator crystals for detection of 511 keV gamma particles has been due mostly to recent advances in modern imaging systems employing positron emitting radionuclides for medical diagnostics in neurology, oncology and cardiology. While older imaging systems were almost exclusively based on BGO and NaI:Tl crystals the new systems, e.g., ECAT Accel, developed by Siemens/CTI, are based on recently discovered and developed LSO (Lu 2SiO 5:Ce, Ce-activated lutetium oxyorthosilicate) crystals. Interestingly, despite very good properties of LSO, there still is a strong drive toward development of new scintillator crystals that would show even better performance and characteristics. In this presentation we shall review spectroscopic and scintillator characterization of new complex oxide crystals, namely LSO, LYSO, YAG, LuAP (LuAlO 3, lutetium aluminate perovskite) and LuYAP activated with Ce and Pr. The LSO:Ce crystals have been grown by CTI Inc (USA), LYSO:Ce, LuAP:Ce and LuYAP:Ce crystals have been grown by Photonic Materials Ltd., Scotland (PML is the only company providing large LuAP:Ce crystals on a commercial scale), while YAG:Pr and LuAP:Pr crystals have been grown by Institute of Electronic Materials Technology (Poland). All these crystals have been characterized at Institute of Physics, N. Copernicus University (Poland). We will review and compare results of measurements of radioluminescence, VUV spectroscopy, scintillation light yields, scintillation time profiles and low temperature thermoluminescence performed on these crystals. We will demonstrate that all experiments clearly indicate that there is a significant room for improvement of LuAP, LuYAP and YAG. While both Ce-activated LSO and LYSO perform very well, we also note that LuYAP:Ce, LuAP:Ce and YAG:Pr offer some advantages and, after a likely improvement of some parameters, may also present a viable and desired alternative in applications that require high counting rates or better time resolution. Unfortunately, LuAP:Pr, although the fastest among all the materials studied, may be seriously limited in its achievable light yield by inherent physical processes that are responsible for nonradiative quenching of scintillation light in this material.

Polarized spectral properties and 1.5-1.6 μm laser operation of Er:Sr3Yb2(BO3)4 crystal

NASA Astrophysics Data System (ADS)

Lin, F. L.; Huang, J. H.; Chen, Y. J.; Gong, X. H.; Lin, Y. F.; Luo, Z. D.; Huang, Y. D.

2013-10-01

Undoped and Er3+-doped Sr3Yb2(BO3)4 crystals were grown by the Czochralski method. Room temperature polarized spectral properties of the Er:Sr3Yb2(BO3)4 crystal were investigated. The efficiency of the energy transfer from Yb3+ to Er3+ ions in this crystal was calculated to be about 95%. End-pumped by a diode laser at 970 nm in a hemispherical cavity, a 0.75 W quasi-CW laser at 1.5-1.6 μm with a slope efficiency of 7% and an absorbed pump threshold of 3.8 W was achieved in a 0.5-mm-thick Z-cut crystal glued on a 5-mm-thick pure YAG crystal with UV-curable adhesive.

Synthesis, crystal growth, optical, thermal, and mechanical properties of a nonlinear optical single crystal: ammonium sulfate hydrogen sulphamate (ASHS)

NASA Astrophysics Data System (ADS)

Sudhakar, K.; Nandhini, S.; Muniyappan, S.; Arumanayagam, T.; Vivek, P.; Murugakoothan, P.

2018-04-01

Ammonium sulfate hydrogen sulphamate (ASHS), an inorganic nonlinear optical crystal, was grown from the aqueous solution by slow evaporation solution growth technique. The single-crystal XRD confirms that the grown single crystal belongs to the orthorhombic system with the space group of Pna21. Powder XRD confirms the crystalline nature and the diffraction planes were indexed. Crystalline perfection of grown crystal was analysed by high-resolution X-ray diffraction rocking curve technique. UV-Vis-NIR studies revealed that ASHS crystal has optical transparency 65% and lower cut-off wavelength at 218 nm. The violet light emission of the crystal was identified by photoluminescence studies. The particle size-dependent second-harmonic generation efficiency for ASHS crystal was evaluated by Kurtz-Perry powder technique using Nd:YAG laser which established the existence of phase matching. Surface laser damage threshold value was evaluated using Nd:YAG laser. Optical homogeneity of the crystal was evaluated using modified channel spectrum method through birefringence study. Thermal analysis reveals that ASHS crystal is stable up to 213 °C. The mechanical behaviour of the ASHS crystal was analysed using Vickers microhardness study.

Internal photopumping of Nd3+ (2H9/2, 4F5/2) states in yttrium aluminum garnet by excitation transfer from oxygen deficiency centers and Fe3+ continuum emission

NASA Astrophysics Data System (ADS)

Hewitt, J. D.; Spinka, T. M.; Senin, A. A.; Eden, J. G.

2011-07-01

Photoexcitation of Nd3+ (2H9/2, 4F5/2) states by the broad (˜70 nm FWHM), near-infrared continuum provided by Fe3+ has been observed at 300 K in bulk yttrium aluminum garnet (YAG) crystals doped with trace concentrations (<50 ppm) of Fe, Cr, and Eu. Irradiation of YAG at 248 nm with a KrF laser, which excites the oxygen deficiency center (ODC) in YAG having peak absorption at ˜240 nm, culminates in ODC→Fe3+ excitation transfer and subsequent Fe3+ emission. This internal optical pumping mechanism for rare earth ions is unencumbered by the requirement for donor-acceptor proximity that constrains conventional Förster-Dexter excitation transfer in co-doped crystals.

Composite Laser Ceramics by Advanced Bonding Technology

PubMed Central

Kamimura, Tomosumi; Honda, Sawao

2018-01-01

Composites obtained by bonding materials with the same crystal structure and different chemical compositions can create new functions that do not exist in conventional concepts. We have succeeded in bonding polycrystalline YAG and Nd:YAG ceramics without any interstices at the bonding interface, and the bonding state of this composite was at the atomic level, similar to the grain boundary structure in ceramics. The mechanical strength of the bonded composite reached 278 MPa, which was not less than the strength of each host material (269 and 255 MPa). Thermal conductivity of the composite was 12.3 W/mK (theoretical value) which is intermediate between the thermal conductivities of YAG and Nd:YAG (14.1 and 10.2 W/mK, respectively). Light scattering cannot be detected at the bonding interface of the ceramic composite by laser tomography. Since the scattering coefficients of the monolithic material and the composite material formed by bonding up to 15 layers of the same materials were both 0.10%/cm, there was no occurrence of light scattering due to the bonding. In addition, it was not detected that the optical distortion and non-uniformity of the refractive index variation were caused by the bonding. An excitation light source (LD = 808 nm) was collimated to 200 μm and irradiated into a commercial 1% Nd:YAG single crystal, but fracture damage occurred at a low damage threshold of 80 kW/cm2. On the other hand, the same test was conducted on the bonded interface of 1% Nd:YAG-YAG composite ceramics fabricated in this study, but it was not damaged until the excitation density reached 127 kW/cm2. 0.6% Nd:YAG-YAG composite ceramics showed high damage resistance (up to 223 kW/cm2). It was concluded that composites formed by bonding polycrystalline ceramics are ideal in terms of thermo-mechanical and optical properties. PMID:29425152

Diffractive Combiner of Single-Mode Pump Laser-Diode Beams

NASA Technical Reports Server (NTRS)

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

2007-01-01

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

Tunable, diode side-pumped Er: YAG laser

DOEpatents

Hamilton, Charles E.; Furu, Laurence H.

1997-01-01

A discrete-element Er:YAG laser, side pumped by a 220 Watt peak-power InGaAs diode array, generates >500 mWatts at 2.94 .mu.m, and is tunable over a 6 nm range near about 2.936 .mu.m. The oscillator is a plano-concave resonator consisting of a concave high reflector, a flat output coupler, a Er:YAG crystal and a YAG intracavity etalon, which serves as the tuning element. The cavity length is variable from 3 cm to 4 cm. The oscillator uses total internal reflection in the Er:YAG crystal to allow efficient coupling of the diode emission into the resonating modes of the oscillator. With the tuning element removed, the oscillator produces up to 1.3 Watts of average power at 2.94 .mu.m. The duty factor of the laser is 6.5% and the repetition rate is variable up to 1 kHz. This laser is useful for tuning to an atmospheric transmission window at 2.935 .mu.m (air wavelength). The laser is also useful as a spectroscopic tool because it can access several infrared water vapor transitions, as well as transitions in organic compounds. Other uses include medical applications (e.g., for tissue ablation and uses with fiber optic laser scalpels) and as part of industrial effluent monitoring systems.

Tunable, diode side-pumped Er:YAG laser

DOEpatents

Hamilton, C.E.; Furu, L.H.

1997-04-22

A discrete-element Er:YAG laser, side pumped by a 220 Watt peak-power InGaAs diode array, generates >500 mWatts at 2.94 {micro}m, and is tunable over a 6 nm range near about 2.936 {micro}m. The oscillator is a plano-concave resonator consisting of a concave high reflector, a flat output coupler, a Er:YAG crystal and a YAG intracavity etalon, which serves as the tuning element. The cavity length is variable from 3 cm to 4 cm. The oscillator uses total internal reflection in the Er:YAG crystal to allow efficient coupling of the diode emission into the resonating modes of the oscillator. With the tuning element removed, the oscillator produces up to 1.3 Watts of average power at 2.94 {micro}m. The duty factor of the laser is 6.5% and the repetition rate is variable up to 1 kHz. This laser is useful for tuning to an atmospheric transmission window at 2.935 {micro}m (air wavelength). The laser is also useful as a spectroscopic tool because it can access several infrared water vapor transitions, as well as transitions in organic compounds. Other uses include medical applications (e.g., for tissue ablation and uses with fiber optic laser scalpels) and as part of industrial effluent monitoring systems. 4 figs.

2D SiNx photonic crystal coated Y3Al5O12:Ce3+ ceramic plate phosphor for high-power white light-emitting diodes.

PubMed

Park, Hoo Keun; Oh, Jeong Rok; Do, Young Rag

2011-12-05

This paper reports the optical effects of a two-dimensional (2D) SiNx photonic crystal layer (PCL) on Y3Al5O12:Ce3+ (YAG:Ce) yellow ceramic plate phosphor (CPP) in order to enhance the forward emission of YAG:Ce CPP-capped high-power white light-emitting diodes (LEDs). By adding the 2D SiNx PCL with a 580 nm lattice constant, integrated yellow emission was improved by a factor of 1.72 compared to that of a conventional YAG:Ce CPP capped on a blue LED cup. This enhanced forward yellow emission is attributed to increased extraction of yellow emission light and improved absorption of blue excitation light through Bragg scattering and/or the leaky modes produced by the 2D PCLs. The introduction of 2D PCL can also reduce the wide variation of optical properties as a function of both ambient temperature and applied current, compared to those of a high-power YAG:Ce CPP-capped LED.

Habit modification of bis-thiourea zinc chloride (ZTC) semi organic crystals by impurities

NASA Astrophysics Data System (ADS)

Ruby Nirmala, L.; Thomas Joseph Prakash, J.

2013-06-01

Single crystals of bis-thiourea zinc chloride (ZTC) doped with metal ion (Li+) possess excellent nonlinear optical properties. These crystals were grown by slow evaporation solution growth technique. The effect of Li+ dopant on the growth and properties of ZTC single crystal were investigated and reported. The grown crystals were crystallized in orthorhombic structure with non-centro symmetric space group Pn21a through the parent compound. The amount of dopant incorporated in the parent crystal was revealed by the inductively coupled plasma (ICP-OES) studies. The FT-IR spectroscopy study was done for finding and confirming the functional groups present in the compound. The UV-Visible spectral study was carried out to find the optical behavior and transparency nature of the grown crystal. TG/DTA measurements and Vickers microhardness measurements were traced to find out the thermal and mechanical stability of the grown crystals respectively. Using Nd:YAG laser, the Second harmonic generation (SHG) for the grown crystals were confirmed.

Habit modification of bis-thiourea zinc chloride (ZTC) semi organic crystals by impurities.

PubMed

Ruby Nirmala, L; Thomas Joseph Prakash, J

2013-06-01

Single crystals of bis-thiourea zinc chloride (ZTC) doped with metal ion (Li(+)) possess excellent nonlinear optical properties. These crystals were grown by slow evaporation solution growth technique. The effect of Li(+) dopant on the growth and properties of ZTC single crystal were investigated and reported. The grown crystals were crystallized in orthorhombic structure with non-centro symmetric space group Pn21a through the parent compound. The amount of dopant incorporated in the parent crystal was revealed by the inductively coupled plasma (ICP-OES) studies. The FT-IR spectroscopy study was done for finding and confirming the functional groups present in the compound. The UV-Visible spectral study was carried out to find the optical behavior and transparency nature of the grown crystal. TG/DTA measurements and Vickers microhardness measurements were traced to find out the thermal and mechanical stability of the grown crystals respectively. Using Nd:YAG laser, the Second harmonic generation (SHG) for the grown crystals were confirmed. Copyright © 2013 Elsevier B.V. All rights reserved.

Delivery of high energy Er:YAG pulsed laser light at 2.94 µm through a silica hollow core photonic crystal fibre.

PubMed

Urich, A; Maier, R R J; Mangan, B J; Renshaw, S; Knight, J C; Hand, D P; Shephard, J D

2012-03-12

In this paper the delivery of high power Er:YAG laser pulses through a silica hollow core photonic crystal fibre is demonstrated. The Er:YAG wavelength of 2.94 µm is well beyond the normal transmittance of bulk silica but the unique hollow core guidance allows silica to guide in this regime. We have demonstrated for the first time the ability to deliver high energy pulses through an all-silica fibre at 2.94 µm. These silica fibres are mechanically and chemically robust, biocompatible and have low sensitivity to bending. A maximum pulse energy of 14 mJ at 2.94 µm was delivered through the fibre. This, to our knowledge, is the first time a silica hollow core photonic crystal fibre has been shown to transmit 2.94 μm laser light at a fluence exceeding the thresholds required for modification (e.g. cutting and drilling) of hard biological tissue. Consequently, laser delivery systems based on these fibres have the potential for the realization of novel, minimally-invasive surgical procedures.

Femtosecond-laser inscribed double-cladding waveguides in Nd:YAG crystal: a promising prototype for integrated lasers.

PubMed

Liu, Hongliang; Chen, Feng; Vázquez de Aldana, Javier R; Jaque, D

2013-09-01

We report on the design and implementation of a prototype of optical waveguides fabricated in Nd:YAG crystals by using femtosecond-laser irradiation. In this prototype, two concentric tubular structures with nearly circular cross sections of different diameters have been inscribed in the Nd:YAG crystals, generating double-cladding waveguides. Under 808 nm optical pumping, waveguide lasers have been realized in the double-cladding structures. Compared with single-cladding waveguides, the concentric tubular structures, benefiting from the large pump area of the outermost cladding, possess both superior laser performance and nearly single-mode beam profile in the inner cladding. Double-cladding waveguides of the same size were fabricated and coated by a thin optical film, and a maximum output power of 384 mW and a slope efficiency of 46.1% were obtained. Since the large diameters of the outer claddings are comparable with those of the optical fibers, this prototype paves a way to construct an integrated single-mode laser system with a direct fiber-waveguide configuration.

Tensile behavior of laser treated Fe-Si-B metallic glass

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

Joshi, Sameehan S.; Samimi, Peyman; Ghamarian, Iman

2015-10-28

Fe-Si-B metallic glass foils were treated with a linear laser track using a continuous wave Nd-YAG laser and its effect on the overall tensile behavior was investigated. Microstructure and phase evolutions were evaluated using X-ray diffraction, resistivity measurements, and transmission electron microscopy. Crystallization fraction was estimated via the differential scanning calorimetry technique. Metallic glass foils treated with the lower laser fluences (<0.49 J/mm{sup 2}) experienced structural relaxation, whereas higher laser fluences led to crystallization within the laser treated region. The overall tensile behavior was least impacted by structural relaxation, whereas crystallization severely reduced the ultimate tensile strength of the laser treatedmore » metallic glass foils.« less

Fine wavelength control in 1.3 μm Nd:YAG lasers by electro-optical crystal lens

NASA Astrophysics Data System (ADS)

Lü, Yanfei; Zhang, Jing; Liu, Huilong; Xia, Jing; Fu, Xihong; Zhang, Anfeng

2014-02-01

A diode-pumped tunable and multi-wavelength continuous-wave Nd:YAG laser based on the 4F3/2-4I13/2 transition has been demonstrated for the first time. The combination of the glass plane positioned at the Brewster angle and the electro-optical crystal KH2PO4 (KDP) lens formed a Lyot filter in the cavity and compressed the available gain bandwidth. With an adjustable voltage applied to the KDP crystal lens, the laser wavelength could be tuned from 1333.8 to 1338.2 nm. Moreover, we can also realize cw dual-wavelength and triple-wavelength lasers with smaller wavelength separation by adjusting the free spectral range of the Lyot filter.

160 W 800 fs Yb:YAG single crystal fiber amplifier without CPA.

PubMed

Markovic, Vesna; Rohrbacher, Andreas; Hofmann, Peter; Pallmann, Wolfgang; Pierrot, Simonette; Resan, Bojan

2015-10-05

We demonstrate a compact and simple two-stage Yb:YAG single crystal fiber amplifier which delivers 160 W average power, 800 fs pulses without chirped pulse amplification. This is the highest average power of femtosecond laser based on SCF. Additionally, we demonstrate the highest small signal gain of 32.5 dB from the SCF in the first stage and the highest extraction efficiency of 42% in the second stage. The excellent performance of the second stage was obtained using the bidirectional pumping scheme, which is applied to SCF for the first time.

Diode-pumped continuous-wave and passively Q-switched Nd:GdLuAG laser at 1443.9 nm

NASA Astrophysics Data System (ADS)

Wu, Qianwen; Liu, Zhaojun; Zhang, Sasa; Cong, Zhenghua; Guan, Chen; Xue, Feng; Chen, Hui; Huang, Qingjie; Xu, Xiaodong; Xu, Jun; Qin, Zengguang

2017-12-01

We investigated the 1443.9 nm laser characteristics of Nd:GdLuAG crystal. Diode-end-pumping configuration was employed under both continuous-wave (CW) and passively Q-switched operations. For CW operation, the maximum average output power was 1.36 W with a slope efficiency of 15%. By using a V3+:YAG crystal as the saturable absorber, we obtained the maximum average output power of 164 mW under Q-switched operation. The corresponding pulse energy was 29.3 μJ and pulse duration was 59 ns.

10J water-cooled DPSSL system based on Yb:YAG crystal edge-cladded by Cr:YAG ceramics (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zheng, Jian-Gang; Yan, Xiongwei; Jiang, Xinying; Wang, Zhenguo; Li, Mingzhong; Zhang, Jun; Zhu, Qihua; Zheng, Wanguo

2017-05-01

Laser Inertial Fusion Energy (IFE) has been attracting the interests of the researchers around the world, because of the promising to the future energy. The Yb:YAG was broadly used in the research field of high-peak power and large energy laser with repetition-rate for IFE because of its outstanding performance, including significant thermal and mechanical capacities, long upper energy level lifetime, high quantum efficiency and highly doping capacity. But it exhibits high saturation fluence at room temperature because of the small emission and absorption cross-section. And at the same time this gain material exhibits self-absorption of laser because of the thermal population at lower laser level at room temperature. Ant it appears to have been solved by means of the cryogenic temperature, but the total efficiency of the laser system will be decreased as the use of cryogenic temperature. The amplified spontaneous emission (ASE) effect of the amplifier can be relaxed by means of edge-cladded absorption material. And the difficulties of edge cladding can be will solved as the emergence of ceramics. But at present the ceramics exhibits high scattering and many disfigurements, which limited the application in the high-power large-energy laser system. So the edge-cladding of Yb:YAG crystal will be a key issue for solution the ASE in amplifier. In this paper, we will introduce a 10J water-cooled DPSSL system, based on Yb:YAG crystal at room temperature. In this system a new edge cladding method has been used, that the Yb:YAG crystal was edge cladded by Cr:YAG ceramics, which was used as the absorption material of ASE. The amplifier was an active mirror water-cooled room temperature amplifier. With the help of this edge cladding the ASE has been lowered, and about 5 times small signal gain has been obtained in a single pass amplification, which was much higher than the earlier of 2 times. And the wavefront aberrance of the laser beam was also reduced due to the thermal equilibrium between the edge cladding and the gain region. the amplifiers can be stably operated under 10Hz. Finally the output of the laser system was about 7.15J@10Hz and 10.8J@1-2Hz. The total optical-to-optical efficiency was about 8.3% for 1-2Hz (under the condition of 120kW/1ms pumping, 880mJ input and 10.8J output) and 5.6% for 10Hz.

Development of an eye-safe solid-state tunable laser transmitter in the 1.4-1.5 μm wavelength region based on Cr4+:YAG crystal for lidar applications

NASA Astrophysics Data System (ADS)

Petrova-Mayor, Anna; Wulfmeyer, Volker; Weibring, Petter

2008-04-01

An experimental optimization of the efficiency of a gain switched tunable Cr4+:YAG laser at 10 Hz is described. The thermal lensing during pulsed operation was measured. Optimal performance occurred at a crystal temperature of 34 °C and resulted in an output energy of ~7 mJ and a pulse duration of ~35 ns. Tunability in the range of 1350-1500 nm, spectral linewidth of ~200 GHz, and M2<4 are demonstrated. The main laser material parameters are estimated. Such a laser could be employed in a laboratory-based nonscanning lidar system if a narrowband birefringent filter is installed. The tunability will permit the improvement of the Cr4+:YAG transmitter for water-vapor differential absorption lidar if injection seeding is applied.

Small Business Innovations (Crystal Components)

NASA Technical Reports Server (NTRS)

1991-01-01

Scientific Materials Corporation, Bozeman, MT developed the SciMax line of improved Nd:Yag crystals under an Small Business Innovation Research (SBIR) contract with Langley Research Center. They reduced the amount of water trapped in the crystals during growth to improve the optical quality and efficiency. Applications of the crystals include fiber optics, telecommunications, welding, drilling, eye surgery and medical instrumentation.

High power diode pumped solid state (DPSS) laser systems active media robust modeling and analysis

NASA Astrophysics Data System (ADS)

Kashef, Tamer M.; Mokhtar, Ayman M.; Ghoniemy, Samy A.

2018-02-01

Diode side-pumped solid-state lasers have the potential to yield high quality laser beams with high efficiency and reliability. This paper summarizes the results of simulation of the most predominant active media that are used in high power diode pumped solid-state (DPSS) laser systems. Nd:YAG, Nd:glass, and Nd:YLF rods laser systems were simulated using the special finite element analysis software program LASCAD. A performance trade off analysis for Nd:YAG, Nd:glass, and Nd:YLF rods was performed in order to predict the system optimized parameters and to investigate thermally induced thermal fracture that may occur due to heat load and mechanical stress. The simulation results showed that at the optimized values Nd:YAG rod achieved the highest output power of 175W with 43% efficiency and heat load of 1.873W/mm3. A negligible changes in laser output power, heat load, stress, and temperature distributions were observed when the Nd:YAG rod length was increased from 72 to 80mm. Simulation of Nd:glass at different rod diameters at the same pumping conditions showed better results for mechanical stress and thermal load than that of Nd:YAG and Nd:YLF which makes it very suitable for high power laser applications especially for large rod diameters. For large rod diameters Nd:YLF is mechanically weaker and softer crystal compared to Nd:YAG and Nd:glass due to its poor thermomechanical properties which limits its usage to only low to medium power systems.

Plasmonic nanoparticles embedded in single crystals synthesized by gold ion implantation for enhanced optical nonlinearity and efficient Q-switched lasing.

PubMed

Nie, W J; Zhang, Y X; Yu, H H; Li, R; He, R Y; Dong, N N; Wang, J; Hübner, R; Böttger, R; Zhou, S Q; Amekura, H; Chen, F

2018-03-01

We report on the synthesis of embedded gold (Au) nanoparticles (NPs) in Nd:YAG single crystals using ion implantation and subsequent thermal annealing. Both linear and nonlinear absorption of the Nd:YAG crystals have been enhanced significantly due to the embedded Au NPs, which is induced by the surface plasmon resonance (SPR) effect in the visible light wavelength band. Particularly, through a typical Z-scan system excited by a femtosecond laser at 515 nm within the SPR band, the nonlinear absorption coefficients of crystals with Au NPs have been observed to be nearly 5 orders of magnitude larger than that without Au NPs. This giant enhancement of nonlinear absorption properties is correlated with the saturable absorption (SA) effect, which is the basis of passive Q-switching or mode-locking for pulsed laser generation. In addition, the linear and nonlinear absorption enhancement could be tailored by varying the fluence of implanted Au + ions, corresponding to the NP size and concentration modulation. Finally, the Nd:YAG wafer with embedded Au NPs has been applied as a saturable absorber in a Pr:LuLiF 4 crystal laser cavity, and efficient pulsed laser generation at 639 nm has been realized, which presents superior performance to the MoS 2 saturable absorber based system. This work opens an avenue to enhance and modulate the nonlinearities of dielectrics by embedding plasmonic Au NPs for efficient pulsed laser operation.

Characteristics of AFB interfaces of dissimilar crystal composites as components for solid state lasers

NASA Astrophysics Data System (ADS)

Lee, H. C.; Meissner, O. R.; Meissner, H. E.

2005-06-01

Adhesive-free bonded (AFB®) composite crystals have proven to be useful components in diode-pumped solid-state lasers (DPSSL). The combination of a lasing medium of higher index of refraction with laser-inactive cladding layers of lower index results in light- or wave-guided slab architectures. The cladding layers also serve to provide mechanical support, thermal uniformity and a heat sink during laser operation. Therefore, the optical and mechanical properties of these components are of interest for the design of DPSSL, especially at high laser fluencies and output power. We report on process parameters and material attributes that result in stress-free AFB® composites that are resistant to thermally induced failure. Formation of stress-free and durable bonds between two dissimilar materials requires heat-treatment of composites to a temperature high enough to ensure durable bonds and low enough to prevent forming of permanent chemical bonds. The onset temperature for forming permanent bonds at the interface sets the upper limit for heat treatment. This limiting temperature is dependent on the chemical composition, crystallographic orientation, and surface characteristics. We have determined the upper temperature limits for forming stress-free bonds between YAG and sapphire, YAG and GGG, YAG and spinel, spinel and sapphire, spinel and GGG, and sapphire and GGG composites. We also deduce the relative magnitude of thermal expansion coefficients amongst the respective single crystals as αGGG > αsapp_c > αspinel > αYAG > αsapp_a from interferometric analysis.

Optical signal inverter of erbium-doped yttrium aluminum garnet with red shift of laser diodes.

PubMed

Maeda, Y

1994-08-10

An optical signal inverter was demonstrated in a simple structure that combined a laser diode with Er-doped YAG crystal. The optical signal inversion occurred at a response time of 7 ns and was caused by the decrease of transmission of Er:YAG against the red shift of the wavelength of the laser diode.

A compound crystal with film scintillator for electron detection

NASA Astrophysics Data System (ADS)

McKinney, George; McDonnald, Warren; Tzolov, Marian

2015-03-01

Yttrium Aluminum Garnets (YAG) and Yttrium Aluminum Perovskite (YAP) are widely used as electron detectors. This application requires a top conducting layer which hinders their application at low electron energies. We have developed a layer of zinc tungstate which delivers conductivity large enough to prevent charging while still being an efficient scintillator. For better coupling between the two systems we have studied their optical properties. Ce doping is an essential element in YAP and YAG in order for them to be efficient scintillators. We have studied the Ce content and we show that higher Ce content leads to reabsorption in the YAP scintillators. These details were revealed by using photoluminescence emission and excitation spectroscopy. The absorption spectrum for the YAG scintillators coincides with the excitation for the main emission lines. The optical studies of the zinc tungstate films and a single crystal have shown that the films are more efficient light emitters. We have integrated the zinc tungstate films with YAG scintillators and we will report on the performance of this compound scintillator. It is expected that it will perform well at low and high electron energies, which makes it a very cost effective platform for electron detectors.

A compact Nd:YAG DPSSL using diamond-cooled technology

NASA Astrophysics Data System (ADS)

Chou, Hsian P.; Wang, Yu-Lin; Hasson, Victor H.; Trainor, Daniel W.

2005-03-01

In our diamond-cooled approach, thin disks of laser gain material, e.g., Nd:YAG, are alternated between thin disks of single crystal synthetic diamond whose heat conductivity is over 2000 W/m-°K. The gain medium is face-pumped (along the optical axis) by the output of laser diode arrays. This optical configuration produces heat transfer from Nd:YAG to the diamond, in the direction of the optical axis, and then heat is rapidly conducted radially outward through the diamond to the cooling fluid circulating at the circumference of the diamond/YAG assembly. This geometry effectively removes the heat from the gain material in a manner that permits the attainment of high power output with excellent beam quality.

Cascade conical refraction for annular pumping of a vortex Nd:YAG laser and selective excitation of low- and high-order Laguerre–Gaussian modes

NASA Astrophysics Data System (ADS)

Wu, Yongxiao; Wang, Zhongyang; Chen, Sanbin; Shirakwa, Akira; Ueda, Ken-ichi; Li, Jianlang

2018-05-01

We proposed an efficient and vortex Nd:YAG laser for selective lasing of low- and high-order vortex modes, in which multiple-ring pump light was originated from cascaded conical refraction of multiple biaxial crystals. In our proof of concept demonstration, we used two-crystal cascade conical refraction to generate two-ring pump light; the mutual intensity ratio and relative separation of the inner ring and outer ring were controlled by rotating the second biaxial crystal and by moving the imaging lens, respectively. As a result, we obtained selective excitation of Laguerre–Gaussian (LG01 and LG03) vortex modes in the end-pump Nd:YAG laser. For LG01-mode output, the laser power reached 439 mW with 52.5% slope efficiency; for LG03-mode output, the laser power reached 160 mW with 41.3% slope efficiency. Our results revealed that the multiple-ring pumping technique based on cascaded conical refraction would pave the way for realization of the efficient and switchable excitation of low- and high-order LG modes in an end-pumped solid-state laser.

Effect of doping of KDP crystal with amino acid L-arginine on the strength properties and character of laser damage

NASA Astrophysics Data System (ADS)

Dolzhenkova, E. F.; Kostenyukova, E. I.; Bezkrovnaya, O. N.; Pritula, I. M.

2017-11-01

Studied were the strength characteristics of KDP crystals doped with L-arginine under a concentrated load and irradiation of the first harmonic YAG:Nd3+ laser. The crystals were obtained by means of the temperature reduction method on a point seed, the content of L-arginine in the aqueous solution being 0.3, 0.4, 1.0 and 1.4 wt%. The character of the dependence of KDP microhardness versus the concentration of amino acid in the crystal was investigated. The regularities of brittle damage of the doped KDP crystal at mechanical testing and laser irradiation were shown to be similar. As confirmed in the study, the planes of easy crack extension in the crystal are {2 2 1}, (1 0 0), and (0 0 1) planes, the cracks mainly propagate parallel to {2 2 1} planes. The mechanical and laser strength values of doped KDP crystals were evaluated.

120 watt continuous wave solar-pumped laser with a liquid light-guide lens and an Nd:YAG rod.

PubMed

Dinh, T H; Ohkubo, T; Yabe, T; Kuboyama, H

2012-07-01

We propose a simple and efficient pumping approach for a high-power solar-pumped laser by using a liquid light-guide lens (LLGL) and a hybrid pumping cavity. A 2×2 m Fresnel lens is used as a primary concentrator to collect natural sunlight; 120 W cw laser power and a 4.3% total slope efficiency are achieved with a 6-mm diameter Nd:YAG rod within a 14-mm diameter LLGL. The corresponded collection efficiency is 30.0 W/m(2), which is 1.5 times larger than the previous record. This result is unexpectedly better than that of Cr:Nd:YAG ceramics. It is because the scattering coefficient of Cr:Nd:YAG ceramics is 0.004cm(1), which is 2 times larger than that of the Nd:YAG crystal, although both have similar saturation gains.

Theoretical analyses of a 1.617-μm laser with a MOPA configuration

NASA Astrophysics Data System (ADS)

Cai, He; Han, Juhong; Wang, You; Rong, Kepeng; Yu, Hang; Wang, Shunyan; An, Guofei; Zhang, Wei; Wu, Peng; Yu, Qiang; Wang, Hongyuan

2018-01-01

In the recent years, lasers around 1.6 μm are attracted much attention since their wavelengths fit the atmospheric transmission window and can be used for applications in a range of fields including laser radar, gas sensing, and free-space communications. As one of the lasing wavelengths of an Er:YAG medium is just located in the 1.6 μm region, such a laser has been gaining more and more extensive applications in the near infrared. Until now, rare literatures have been found in the MOPA (Master Oscillator Power Amplifier) study of a 1.617 μm Er:YAG laser because the effect of upconversion will become greater while a higher doping concentration is adopted. In this study, we theoretically analyze the amplification features of a 1.617 μm Er:YAG seed laser by using a multiple MOPA configuration. In the simulation, a kinetic model is established to investigate how the doping concentration, crystal length, and pump power affect the amplification efficiency of a seed laser. The results would be helpful to construct a feasible 1.617 μm laser system.

Single-frequency Nd:YAG ring lasers with corner cube prism

NASA Astrophysics Data System (ADS)

Wu, Ke Ying; Yang, Su Hui; Zhao, Chang Ming; Wei, Guang Hui

2000-04-01

Kane and Byer reported the first monolithic non-planar miniature ring lasers in 1985. An intrinsic optical diode enforces unidirectional and hence single-frequency oscillation of this device. It has the advantages of compactness, reliability and high efficiency. We put forward another form of the non-planar ring lasers, in which the corner cube prism is the key element and the Nd:YAG crystal is used as a Porro prism to enclose the ring resonator. The phase shift due to the total internal reflections of the three differently orientated reflection planes of the corner cube prism, Faraday rotation in the Nd:YAG crystal placed in a magnetic field and the different output coupling in S and P polarization form an optical diode and enforce the single- frequency generating. A round trip analysis of the polarization properties of the resonator is made by the evaluation of Jones matrix. The results of our initial experiment are given in the paper.

The effect of Fe 3+ doping in Potassium Hydrogen Phthalate single crystals on structural and optical properties

NASA Astrophysics Data System (ADS)

Kumar, R. Ashok; Sivakumar, N.; Vizhi, R. Ezhil; Babu, D. Rajan

2011-02-01

This work investigates the influence of iron doping on Potassium Hydrogen Phthalate (KHP) single crystals by the slow evaporation solution growth technique. Factors such as evaporation rate, solution pH, solute concentration, super saturation limit, etc. are very important in order to have optically transparent single crystals. As part of the work, the effects of metallic salt FeCl 3 in different concentrations were analyzed with pure KHP. Powder X-ray diffraction suggests that the grown crystals are crystallized in the orthorhombic structure. The functional groups and the effect of moisture on the doped crystals can be analyzed with the help of a FTIR spectrum. The pure and doped KHP single crystal shows good transparency in the entire visible region, which is suitable for optical device applications. The refractive indices along b axis of pure and doped KHP single crystals were analyzed by the prism coupling technique. The emission of green light with the use of a Nd:YAG laser ( λ=1064 nm) confirmed the second harmonic generation properties of the grown crystals.

Morphological and ultrastructural comparative analysis of bone tissue after Er:YAG laser and surgical drill osteotomy.

PubMed

Panduric, Dragana Gabric; Juric, Ivona Bago; Music, Svetozar; Molčanov, Krešimir; Sušic, Mato; Anic, Ivica

2014-07-01

The purpose of this study was to analyze morphological, chemical, and crystallographic changes of bone tissue after osteotomy performed with an erbium:yttrium-aluminium-garnet (Er:YAG) laser and a low speed pilot drill. Bone blocks were prepared from porcine ribs, and on each block, two tunnel preparations were performed using the Er:YAG laser (pulse energy: 1000 mJ, pulse duration: 300 μs, pulse repetition rate: 20 Hz) or the low-speed surgical pilot drill. The morphological changes of the cortical and the spongious surface of the tunnel preparations were analyzed under the field emission scanning electron microscopy (FE-SEM) at low and high resolution. The distribution and the level of chemical elements in the treated surfaces were evaluated by qualitative and semiquantitative energy dispersive x-ray analysis (SEM-EDX). Diffraction x-ray analysis was used to detect any differences and thermally induced modifications of hydroxyapatite crystals. FE-SEM revealed sharp edges of the Er:YAG preparations, with empty intertrabecular spaces and no signs of carbonization. In the drill group, the surface of the preparations was smooth, completely covered with smear layer and microcracks, and with hairy-like irregularities on the edges. SEM-EDX analysis did not reveal any differences in the number of specific chemical elements between the laser and the drill group. There were no thermally induced modifications of hydroxyapatite crystal structure in the bone tissue in either group. The Er:YAG laser ablation did not cause any chemical or crystallographic changes of the bone tissue. Compared with the drill, Er:YAG laser created well-defined edges of the preparations, and cortical bone had no smear layer.

Single, composite, and ceramic Nd:YAG 946-nm lasers

NASA Astrophysics Data System (ADS)

Lan, Rui-Jun; Yang, Guang; Zheng-Ping, Wang

2015-06-01

Single, composite crystal and ceramic continuous wave (CW) 946-nm Nd:YAG lasers are demonstrated, respectively. The ceramic laser behaves better than the crystal laser. With 5-mm long ceramic, a CW output power of 1.46 W is generated with an optical conversion efficiency of 13.9%, while the slope efficiency is 17.9%. The optimal ceramic length for a 946-nm laser is also calculated. Project supported by the National Natural Science Foundation of China (Grant No. 61405171), the Natural Science Foundation of Shandong Province, China (Grant No. ZR2012FQ014), and the Science and Technology Program of the Shandong Higher Education Institutions of China (Grant No. J13LJ05).

Thermal Shock Behavior of Single Crystal Oxide Refractive Concentrators for High Temperatures Solar Thermal Propulsion

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Choi, Sung R.; Jacobson, Nathan S.; Miller, Robert A.

1999-01-01

Single crystal oxides such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium-aluminum-garnet (Y3Al5O12, or YAG), magnesium oxide (MgO) and sapphire (Al2O3) have been considered as refractive secondary concentrator materials for high temperature solar propulsion applications. However, thermal mechanical reliability of the oxide components in severe thermal environments during space mission sun/shade transitions is of great concern. In this paper, critical mechanical properties of these oxide crystals are determined by the indentation technique. Thermal shock resistance of the oxides is evaluated using a high power CO, laser under high temperature-high thermal gradients. Thermal stress fracture behavior and failure mechanisms of these oxide materials are investigated under various temperature and heating conditions.

Performance study of highly efficient 520 W average power long pulse ceramic Nd:YAG rod laser

NASA Astrophysics Data System (ADS)

Choubey, Ambar; Vishwakarma, S. C.; Ali, Sabir; Jain, R. K.; Upadhyaya, B. N.; Oak, S. M.

2013-10-01

We report the performance study of a 2% atomic doped ceramic Nd:YAG rod for long pulse laser operation in the millisecond regime with pulse duration in the range of 0.5-20 ms. A maximum average output power of 520 W with 180 J maximum pulse energy has been achieved with a slope efficiency of 5.4% using a dual rod configuration, which is the highest for typical lamp pumped ceramic Nd:YAG lasers. The laser output characteristics of the ceramic Nd:YAG rod were revealed to be nearly equivalent or superior to those of high-quality single crystal Nd:YAG rod. The laser pump chamber and resonator were designed and optimized to achieve a high efficiency and good beam quality with a beam parameter product of 16 mm mrad (M2˜47). The laser output beam was efficiently coupled through a 400 μm core diameter optical fiber with 90% overall transmission efficiency. This ceramic Nd:YAG laser will be useful for various material processing applications in industry.

Optical triggering of a Q-switched Nd:YAG laser via transverse bleaching of a Cr:YAG saturable absorber.

PubMed

Cole, Brian; Lei, Jonathan; DiLazaro, Tom; Schilling, Bradley; Goldberg, Lew

2009-11-01

Optical triggering via direct bleaching of a Cr:YAG saturable absorber was applied to a monolithic Nd:YAG/Cr:YAG laser crystal. The method uses a single laser diode bar to bleach a thin sheet within the saturable absorber from a direction orthogonal to the lasing axis. By placing the Q-switch at the time corresponding to the steepest slope (dT/dt) for change in transmission during bleaching, the pulse-to-pulse timing jitter showed a 13.2x reduction in standard deviation, from 132 ns for free-running operation to 10 ns with optical triggering. We measured that a fluence of 60 kW/cm(2) was sufficient to enable optical triggering, where a diode appropriately sized for the length of the Cr:YAG (approximately 3 mm) would then require only approximately 150 W of optical power over a 1-2 micros duration to enable effective jitter reduction. Additionally, we measured an increase in optical-to-optical efficiency with optical triggering, where the efficiency improved from 12% to 13.5%.

Rare earth garnet selective emitter

NASA Technical Reports Server (NTRS)

Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

1994-01-01

Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approximately equal to 0.74, ((4)l(sub 15/2)) - ( (4)l(sub13/2)), for Er-YAG and epsilon(sub lambda) approximately equal to 0.65, ((5)l(sub 7))-((5)l(sub 8)) for Ho-YAG) at excellent candidates for high efficiency selective emitters in the thermophotovoltaics (TPV) systems operating at moderate temperatures (1200-1500K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. This paper presents normal spectral emittance, epsilon(sub lambda), measurements of holmium (Ho), and erbium (Er) doped YAG thin film selective emitters at 1500 K, and compares those results with the theoretical spectral emittance.

Solid-state Yb : YAG amplifier pumped by a single-mode laser at 920 nm

NASA Astrophysics Data System (ADS)

Obronov, I. V.; Demkin, A. S.; Myasnikov, D. V.

2018-03-01

An optical amplifier scheme for ultrashort 1030-nm pulses is proposed based on an Yb : YAG crystal with axial pumping by a transverse single-mode laser at a wavelength of 920 nm. A small-signal gain up to 40 dB per pass with a high output beam quality is demonstrated. The maximum average power is 14 W with a slope efficiency exceeding 50%.

Growth, density functional theory (DFT) and spectral studies on L-2-aminobutyric acid -biologically active material

NASA Astrophysics Data System (ADS)

Usha, C.; Santhakumari, R.; Meenakshi, R.; Jayasree, R.; Bhuvaneswari, M.

2017-12-01

Single crystal of L-2-aminobutyric acid (ABA) was grown from water by slow evaporation at room temperature. The crystalline nature of the grown crystal was confirmed using powder X-ray diffraction studies. The grown crystal was subjected to FT-IR, FT-Raman, 1H NMR and 13C NMR spectral analyses to confirm the presence of functional group and molecular structure respectively. Thermal properties were investigated by thermogravimetric and differential thermal analyses. The range and percentage of optical transmission was ascertained by recording UV-vis-NIR spectrum. The electronic charge distribution and reactivity of the molecules within the crystal were studied by HOMO and LUMO analysis and the molecular electrostatic potential (MEP) of the grown crystal was performed using the B3LYP method. The anti-bacterial activities of the crystal were performed by disk diffusion method against the standard bacteria E. coli. The crystal exhibits good anti-bacterial activity. Second harmonic generation efficiency of the powdered ABA crystal was tested using Nd:YAG laser and it is found to be ∼3.3 times that of potassium dihydrogen orthophosphate.

Trivalent cerium coped crystals as tunable laser systems: two bad apples

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

Hamilton, D.S.

1985-01-01

The 5d-4f transitions of trivalent doped crystals have broad emission bands with large oscillator strengths and near unity quantum efficiency. These characteristics make cerium systems strong candidates for tunable solid state lasers. However, two such cerium crystals will probably never lase. The first is Ce/sup 3 +/:YAG where a strong excited state absorption quenches the lasing transition. Our recent measurements have indicated that the excited state absorption terminates in the YAG conduction band with a peak cross section of 1.0 x 10/sup -17/ cm/sup 2/ at 700 nm. Some of the general features of impurity ion to band spectra aremore » discussed. The second system is Ce/sup 3 +/:CaF/sub 2/ where a uv pump induced photochromic center is produced following excitation of the cerium ions. The initial measurements of cerium related transient absorptions in Ce/sup 3 +/:YLF are also presented.« less

TEM00 mode Nd:YAG solar laser by side-pumping a grooved rod

NASA Astrophysics Data System (ADS)

Vistas, Cláudia R.; Liang, Dawei; Almeida, Joana; Guillot, Emmanuel

2016-05-01

A simple TEM00 mode solar laser system with a grooved Nd:YAG rod pumped through a heliostat-parabolic mirror system is reported here. The radiation coupling capacity of a fused silica tube lens was combined with the multipass pumping ability of a 2 V-shaped cavity to provide efficient side-pumping along a 4.0 mm diameter grooved Nd:YAG single-crystal rod. TEM00 mode solar laser power of 3.4 W was measured by adopting an asymmetric large-mode laser resonant cavity. Record TEM00 mode solar laser collection efficiency of 3.4 W/m2and slope efficiency of 1.9% was achieved, which corresponds to 1.8 and 2.4 times more than the previous TEM00 mode Nd:YAG solar laser using the PROMES-CNRS heliostat-parabolic mirror system, respectively.

Efficient green light generation by Q-switched Nd: YAG laser in periodically poled potassium titanyl phosphate crystal

NASA Astrophysics Data System (ADS)

Zhang, Shuanggen; Guo, Wengang; Lv, Fuyun

2014-07-01

A PPKTP crystal was used to efficient green emission. Spectrum characteristics of FF and SH wave was analyzed, and phase-matching wavelength shift results from thermally-induced poling period shift. A conversion efficiency of 26.1% can be achieved.

Nonlinear Optical Effects in Liquid Crystals.

DTIC Science & Technology

1980-12-10

susceptibilities Lasers , Nematic, Cholesteric, Flexoelectric, Second-harmonic generation 20M AV*--YRAc rR-r, m, revere i It nf le4U7 siad Idsiully byr...samples are irradiated with laser beam at the fundamental frequency. The laser used in a Q-switched Nd-YAG laser . Sample alignment is achieved either...irradiated with laser beam at the fundamental frequency. The laser used is a Q-switched Nd-YAG laser . Sample alignment is achieved either with rubbing

Growth and anisotropic thermal properties of biaxial Ho:YAlO3 crystal

NASA Astrophysics Data System (ADS)

Dong, Qin; Zhao, Guangjun; Chen, Jianyu; Ding, Yuchong; Zhao, Chengchun

2010-07-01

Ho:YAlO3 (YAP) crystal with large size and good optical quality has been grown by the Czochralski method. Thermal properties of the as-grown Ho:YAP crystal have been investigated by measuring the temperature-dependent, anisotropic thermal expansion, specific heat, thermal diffusion, and thermal conductivity. The results show that Ho:YAP crystal possesses a large anisotropic thermal expansion and good thermal conductivity. The calculated average thermal expansion coefficients along a, b, and c axis are αa=9.18×10-6/K, αb=1.94×10-6/K, and αc=7.61×10-6/K from 293.15 to 770.15 K. The thermal conductivities along a, b, and c axis are up to 11.6, 9.9, and 12.3 W m-1 K-1 at 298.15 K. Compared with Ho: Y3Al5O12 (YAG), Ho:YAP crystal has a larger thermal conductivity along a axis from 298.15 to 568.15 K.

Growth, structural, thermal, linear and nonlinear optical and laser damage threshold studies of picolinium tartrate monohydrate single crystals.

PubMed

Peramaiyan, G; Pandi, P; Sornamurthy, B M; Bhagavannarayana, G; Mohan Kumar, R

2012-09-01

Picolinium tartrate monohydrate (PTM), a novel organic nonlinear optical material was synthesized and bulk crystals were grown from aqueous solution by slow cooling technique. The cell parameters of the grown crystal were found by single and powder X-ray diffraction analyses. The crystalline perfection of the grown crystals has been analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements. The presence of functional groups in the grown crystal was identified by FTIR and FT-Raman spectral analyses. UV-Vis spectral studies reveal PTM crystals are transparent in the wavelength region of 295-1100 nm. The thermal characteristics of PTM were analyzed by TGA/DTA studies. The dielectric and mechanical behaviours of PTM crystals were investigated. Dislocation density was estimated to be 2.89 × 10(3) cm(-2) on the flat-surface of PTM crystals from the etching studies. The laser induced surface damage threshold for the grown crystal was measured using Nd:YAG laser. Its second harmonic generation relative efficiency was measured by Kurtz and Perry powder technique and was observed to be comparable with KDP crystal. Copyright © 2012 Elsevier B.V. All rights reserved.

Single Crystal Faceplate Evaluation

DTIC Science & Technology

1993-10-25

conventional powder phosphor. The utility of garnets is amplified by the high state of the art of liquid phase epitaxy ( LPE ). Liquid phase epitaxy of...7]. Much the research at Allied-Signal, Inc. in garnet layer growth has been involved with the kinetics of crystallization of garnet from LPE melts...acceptable resolution and light output characteristics. Single crystal faceplates being evaluated are composed of yttrium aluminum garnet (YAG) with an

Development of flashlamp-pumped Q-switched Ho:Tm:Cr:YAG lasers for mid-infrared LIDAR application

NASA Technical Reports Server (NTRS)

Choi, Young S.; Kim, Kyong H.; Whitney, Donald A.; Hess, Robert V.; Barnes, Norman P.; Bair, Clayton H.; Brockman, Philip

1989-01-01

A flashlamp-pumped 2.1 micron Ho:Tm:Cr:YAG laser was studied for both normal mode and Q-switched operations under a wide variety of experimental conditions in order to optimize performance. Laser output energy, slope efficiency, threshold and pulselength were determined as a function of operating temperature, output mirror reflectivity, input electrical energy and Q-switch opening time. The measured normal-mode laser thresholds of a Ho(3+) (0.45 atomic percent):Tm(3+) (2.5 atomic percent):Cr(3+) (0.8 atomic percent):YAG crystal ranged form 26 to 50 J between 120 and 200 K with slope efficiencies up to 0.36 percent with a 60 percent reflective output mirror. Under Q-switched operation the slope efficiency was 90 percent of the normal-mode result. Development of solid state lasers with Ho(3+), Tm(3+) and/or Er(3+) doped crystals has been pursued by NASA for eye-dafe mid-infrared LIDAR (light detection and ranging) application. As a part of the project, the authors have been working on evaluating Ho(3+):Tm(3+):Cr(3+):YAG crystals for normal-mode and Q-switched 2.1 micron laser operations in order to determine an optimum Tm(3+) concentration under flashlamp pumping conditions. Lasing properties of the Ho(3+) in the mid-infrared region have been studied by many research groups since the early 1960's. However, the technology of those lasers is still premature for lidar application. In order to overcome the inefficiency related to narrow absorption bands of the Ho(3+), Tm(3+) and Er(3+), the erbium has been replaced by chromium. The improvement in flashlamp-pumped Ho(3+) laser efficiency has been demonstrated recently by several research groups by utilizing the broad absorption spectrum of Cr(3+) which covers the flashlamp's emission spectrum. Efficient energy transfer to the Tm(3+) and then the Ho(3+) occurs subsequently. It is known that high Tm(3+) concentration and low Ho(3+) concentration are preferred to achieve a quantum efficiency approaching two and to avoid large reabsorption losses. However, determination of the optimum Tm(3+) concentration required to ensure efficient energy transfer from Cr(3+) to Tm(3+) and from Tm(3+) to Ho(3+) has not been made in the Ho:Tm:CR:YAG crystal. The results obtained so far are given.

Optimization of diode-pumped doubly QML laser with neodymium-doped vanadate crystals at 1.34 μm

NASA Astrophysics Data System (ADS)

Zhang, Gang; Jiao, Zhiyong

2018-05-01

We present a theoretical model for a diode-pumped, 1.34 μm V3+:YAG laser that is equipped with an acoustic-optic modulator. The model includes the loss introduced by the acoustic-optic modulator combined with the physical properties of the laser resonator, the neodymium-doped vanadate crystals and the output coupler. The parameters are adjusted within a reasonable range to optimize the pulse output characteristics. A typical Q-switched and mode-locked Nd:Lu0.15Y0.85VO4 laser at 1.34 μm with acoustic-optic modulator and V3+:YAG is set up, and the experimental output characteristics are consistent with the theoretical simulation results.

Diode-side-pumped intracavity frequency-doubled Nd:YAG/BaWO4 Raman laser generating average output power of 3.14 W at 590 nm.

PubMed

Li, Shutao; Zhang, Xingyu; Wang, Qingpu; Zhang, Xiaolei; Cong, Zhenhua; Zhang, Huaijin; Wang, Jiyang

2007-10-15

We report a linear-cavity high-power all-solid-state Q-switched yellow laser. The laser source comprises a diode-side-pumped Nd:YAG module that produces 1064 nm fundamental radiation, an intracavity BaWO(4) Raman crystal that generates a first-Stokes laser at 1180 nm, and a KTP crystal that frequency doubles the first-Stokes laser to 590 nm. A convex-plane cavity is employed in this configuration to counteract some of the thermal effect caused by high pump power. An average output power of 3.14 W at 590 nm is obtained at a pulse repetition frequency of 10 kHz.

Optical phase conjugation by four-wave mixing in Nd:YAG laser oscillator for optical energy transfer to a remote target

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

Kawakami, K., E-mail: k.kawakami@al.t.u-tokyo.ac.jp; Komurasaki, K.; Okamura, H.

2015-02-28

A self-starting phase conjugator was designed for optical energy transfer to a remote target. Saturable-gain four-wave mixing in a laser resonator was achieved using a flash-lamp pumped Nd:YAG crystal and phase-conjugate light (PCL) generation were verified. Wavefront correction experimentation revealed that beam wander caused by air turbulence is compensated. Tracking capability was demonstrated in the range of 9 mrad with tracking accuracy of ±0.04 mrad. The maximum field of view was measured to be 4.7°. Dependence of phase-conjugate light energy on reference light energy was investigated. The maximum output of 320 mJ was obtained. The temporal behavior of PCL ismore » discussed based on the four-wave mixing mechanism. Unlike a conventional loop resonator type phase conjugator, this system is applicable for wireless energy transfer to a remote target.« less

11-GHz waveguide Nd:YAG laser CW mode-locked with single-layer graphene.

PubMed

Okhrimchuk, Andrey G; Obraztsov, Petr A

2015-06-08

We report stable, passive, continuous-wave (CW) mode-locking of a compact diode-pumped waveguide Nd:YAG laser with a single-layer graphene saturable absorber. The depressed cladding waveguide in the Nd:YAG crystal is fabricated with an ultrafast laser inscription method. The saturable absorber is formed by direct deposition of CVD single-layer graphene on the output coupler. The few millimeter-long cavity provides generation of 16-ps pulses with repetition rates in the GHz range (up to 11.3 GHz) and 12 mW average power. Stable CW mode-locking operation is achieved by controlling the group delay dispersion in the laser cavity with a Gires-Tournois interferometer.

Highly efficient end-side-pumped Nd:YAG solar laser by a heliostat-parabolic mirror system.

PubMed

Almeida, J; Liang, D; Vistas, C R; Guillot, E

2015-03-10

We report a large improvement in the collection and slope efficiency of an Nd:YAG solar laser pumped by a heliostat-parabolic mirror system. A conical fused silica lens was used to further concentrate the solar radiation from the focal zone of a 2 m diameter primary concentrator to a Nd:YAG single-crystal rod within a conical pump cavity, which enabled multipass pumping to the active medium. A 56 W cw laser power was measured, corresponding to 21.1  W/m2 record-high solar laser collection efficiency with the heliostat-parabolic mirror system. 4.9% slope efficiency was calculated, corresponding to 175% enhancement over our previous result.

11-GHz waveguide Nd:YAG laser CW mode-locked with single-layer graphene

PubMed Central

Okhrimchuk, Andrey G.; Obraztsov, Petr A.

2015-01-01

We report stable, passive, continuous-wave (CW) mode-locking of a compact diode-pumped waveguide Nd:YAG laser with a single-layer graphene saturable absorber. The depressed cladding waveguide in the Nd:YAG crystal is fabricated with an ultrafast laser inscription method. The saturable absorber is formed by direct deposition of CVD single-layer graphene on the output coupler. The few millimeter-long cavity provides generation of 16-ps pulses with repetition rates in the GHz range (up to 11.3 GHz) and 12 mW average power. Stable CW mode-locking operation is achieved by controlling the group delay dispersion in the laser cavity with a Gires–Tournois interferometer. PMID:26052678

Continuous two-wave lasing in microchip Nd : YAG lasers

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

Ievlev, Ivan V; Koryukin, Igor' V; Lebedeva, Yu S

2011-08-31

Simultaneous two-wave lasing was obtained in microchip end-pumped Nd:YAG lasers at the wavelengths of 1061.5 and 1064.17 nm at room temperature. Laser wave intensities were studied as functions of crystal temperature and pump power. The ranges of parameters were determined in which the two-wave lasing occurs and the reasons for such lasing were established. A model is suggested, which adequately describes the experimental results obtained. (control of radiation parameters)

Theoretical model predictions and experimental results for a wavelength switchable Tm:YAG laser.

PubMed

Niu, Yanxiong; Wang, Caili; Liu, Wenwen; Niu, Haisha; Xu, Bing; Man, Da

2014-07-01

We present a theoretical model study of a quasi-three-level laser with particular attention given to the Tm:YAG laser. The oscillating conditions of this laser were theoretically analyzed from the point of the pump threshold while taking into account reabsorption loss. The laser oscillation at 2.02 μm with large stimulated emission sections was suppressed by selecting the appropriate coating for the cavity mirrors, then an efficient laser-diode side-pumped continuous-wave Tm:YAG crystal laser operating at 2.07 μm was realized. Experiments with the Tm:YAG laser confirmed the accuracy of the model, and the model was able to accurately predict that the high Stark sub-level within the H3₆ ground state manifold has a low laser threshold and long laser wavelength, which was achieved by decreasing the transmission of the output coupler.

High peak power Q-switched Er:YAG laser with two polarizers and its ablation performance for hard dental tissues.

PubMed

Yang, Jingwei; Wang, Li; Wu, Xianyou; Cheng, Tingqing; Jiang, Haihe

2014-06-30

An electro-optically Q-switched high-energy Er:YAG laser with two polarizers is proposed. By using two Al(2)O(3) polarizing plates and a LiNbO(3) crystal with Brewster angle, the polarization efficiency is significantly improved. As a result, 226 mJ pulse energy with 62 ns pulse width is achieved at the repetition rate of 3 Hz, the corresponding peak power is 3.6 MW. To our knowledge, such a high peak power has not been reported in literature. With our designed laser, in-vitro teeth were irradiated under Q-switched and free-running modes. Results of a laser ablation experiment on hard dental tissue with the high-peak-power laser demonstrates that the Q-switched Er:YAG laser has higher ablation precision and less thermal damage than the free-running Er:YAG laser.

Structural, thermal and optical characterization of an organic NLO material--benzaldehyde thiosemicarbazone monohydrate single crystals.

PubMed

Santhakumari, R; Ramamurthi, K

2011-02-01

Single crystals of the organic NLO material, benzaldehyde thiosemicarbazone (BTSC) monohydrate, were grown by slow evaporation method. Solubility of BTSC monohydrate was determined in ethanol at different temperatures. The grown crystals were characterized by single crystal X-ray diffraction analysis to determine the cell parameters and by FT-IR technique to study the presence of the functional groups. Thermogravimetric and differential thermal analyses reveal the thermal stability of the crystal. UV-vis-NIR spectrum shows excellent transmission in the region of 200-1100 nm. Theoretical calculations were carried out to determine the linear optical constants such as extinction coefficient and refractive index. Further the optical nonlinearities of BTSC have been investigated by Z-scan technique with He-Ne laser radiation of wavelength 632.8 nm. Mechanical properties of the grown crystal were studied using Vickers microhardness tester. Second harmonic generation efficiency of the powdered BTSC monohydrate was tested using Nd:YAG laser and it is found to be ∼5.3 times that of potassium dihydrogen orthophosphate. Copyright © 2010 Elsevier B.V. All rights reserved.

Synthesis and physicochemical properties of bis(L-asparaginato) zinc(II): A promising new semiorganic crystal with high laser damage threshold for shorter wavelength generation

NASA Astrophysics Data System (ADS)

Subhashini, R.; Arjunan, S.

2018-05-01

An exceedingly apparent nonlinear semiorganic optical crystals of bis(L-asparaginato)zinc(II) [BLAZ], was synthesized by a traditional slow evaporation solution growth technique. The cell parameters were estimated from single crystal X-ray diffraction analysis. Spectroscopic study substantiates the presence of functional groups. The UV spectrum shows the sustenance of wide transparency window and several optical constants, such as extinction coefficient (K), refractive index, optical conductivity and electric susceptibility with real and imaginary parts of dielectric constant were calculated using the transmittance data. The fluorescence emission spectrum of the crystal pronounces red emission. The laser induced surface damage threshold of the crystal was measured using Nd:YAG laser. The output intensity of second harmonic generation was estimated using the Kurtz and Perry powder method. The hardness stability was investigated by Vickers microhardness test. The decomposition and thermal stability of the compound were scrutinized by TGA-DSC studies. Dielectric studies were carried out to anatomize the electrical properties of the crystal. SEM analysis reveals the existence of minute crystallites on the growth surface.

Diode-pumped cw Nd:YAG three-level laser at 869 nm.

PubMed

Lü, Yanfei; Xia, Jing; Cheng, Weibo; Chen, Jifeng; Ning, Guobin; Liang, Zuoliang

2010-11-01

We report for the first time (to our knowledge) a diode-pumped Nd:YAG laser emitting at 869 nm based on the (4)F(3/2)-(4)I(9/2) transition, generally used for a 946 nm emission. Power of 453 mW at 869 nm has been achieved in cw operation with a fiber-coupled laser diode emitting 35.4 W at 809 nm. Intracavity second-harmonic generation in the cw mode has also been demonstrated with power of 118 mW at 435 nm by using a BiB(3)O(6) nonlinear crystal. In our experiment, we used a LiNbO(3) crystal lens to complement the thermal lens of the laser rod, and we obtained good beam quality and high output power stability.

Low loss depressed cladding waveguide inscribed in YAG:Nd single crystal by femtosecond laser pulses.

PubMed

Okhrimchuk, Andrey; Mezentsev, Vladimir; Shestakov, Alexander; Bennion, Ian

2012-02-13

A depressed cladding waveguide with record low loss of 0.12 dB/cm is inscribed in YAG:Nd(0.3at.%) crystal by femtosecond laser pulses with an elliptical beam waist. The waveguide is formed by a set of parallel tracks which constitute the depressed cladding. It is a key element for compact and efficient CW waveguide laser operating at 1064 nm and pumped by a multimode laser diode. Special attention is paid to mechanical stress resulting from the inscription process. Numerical calculation of mode distribution and propagation loss with the elasto-optical effect taken into account leads to the conclusion that the depressed cladding is a dominating factor in waveguide mode formation, while the mechanical stress only slightly distorts waveguide modes.

Development and Fabrication of a Space Hardened Nd(3+) YAG Laser Transmitter System for Orbital Range and Altitude Control

DTIC Science & Technology

1975-05-06

YAG system, to. be able to operate’in a ground launched satellite. ) Study was conducted to identify and eliminate all sources of laser degradation...further studies and the design of the space-hardened Laser Transmitter.I The study included such topics as general interferometer stability, internally...generated perturbances, external perturbations and their effects on the I’ laser stability. Further study covered the Laser Crystal parameters such as

Growth, spectral, optical, laser damage threshold and DFT investigations on 2-amino 4-methyl pyridinium 4-methoxy benzoate (2A4MP4MB): A potential organic third order nonlinear optical material for optoelectronic applications

NASA Astrophysics Data System (ADS)

Krishnakumar, M.; Karthick, S.; Thirupugalmani, K.; Babu, B.; Vinitha, G.

2018-05-01

In present investigation, single crystals of organic charge transfer complex, 2-amino-4-methyl pyridinium-4-methoxy benzoate (2A4MP4MB) was grown by controlled slow evaporation solution growth technique using methanol as a solvent at room temperature. Single crystal XRD analysis confirmed the crystal system and lattice parameters of 2A4MP4MB. The crystalline nature, presence of various vibrational modes and other chemical bonds in the compound have been recognized and confirmed by powder X-ray diffraction, FT-IR and FT-Raman spectroscopic techniques respectively. The presence of various proton and carbon positions in title compound was confirmed using 1H NMR and 13C NMR spectral studies. The wide optical operating window and cut-off wavelength were identified and band gap value of the title compound was calculated using UV-vis-NIR study. The specific heat capacity (cp) values of the title compound, 1.712 J g-1·K-1 at 300 K and 13.6 J g-1 K-1 at 433 K (melting point) were measured using Modulated Differential Scanning Calorimetric studies (MDSC). From Z-scan study, nonlinear refractive index (n2), nonlinear absorption (β) and third order nonlinear susceptibility (χ(3)) values were determined. The self-defocusing effect and saturable absorption behavior of the material were utilized to exhibit the optical limiting action at λ = 532 nm by employing the same continuous wave (cw) Nd: YAG laser source. The laser damage threshold (LDT) study of title compound was carried out using Nd: YAG laser of 532 nm wavelength. The Vickers' micro hardness test was carried out at room temperature and obtained results were investigated using classical Meyer's law. In addition, DFT calculations were carried out for the first time for this compound. These characterization studies performed on the title compound planned to probe the valuable and safe region of optical, thermal and mechanical properties to improve efficacy of 2A4MP4MB single crystals in optoelectronic device applications.

Near Infrared Luminescence Properties of Mn(5+): Ca5(PO4)3F

NASA Technical Reports Server (NTRS)

Davis, Valetta R.; Hoemmerich, Uwe; Loutts, George B.

1997-01-01

We report a spectroscopic investigation of Mn(5+) doped Ca5(PO4)(sub 3)F or FAP. Mn(5+) doped crystals have recently attracted world wide attention for potential solid-state laser applications. Following optical excitation of Mn: FAP with the 600 nm output of a Nd: YAG OPO laser system, we observed a strong near infrared luminescence centered at around 1150 nm. The room temperature luminescence decay time was measured to be approximately 635 microseconds. We attribute the infrared luminescence to the(1)E yields (3)A2 transition of tetrahedrally coordinated Mn5+ ions located in a strong crystal field environment. Absorption, luminescence and lifetime data of Mn: FAP will be presented and discussed.

Generation of orthogonally polarized self-mode-locked Nd:YAG lasers with tunable beat frequencies from the thermally induced birefringence.

PubMed

Sung, C L; Cheng, H P; Lee, C Y; Cho, C Y; Liang, H C; Chen, Y F

2016-04-15

The simultaneous self-mode-locking of two orthogonally polarized states in a Nd:YAG laser is demonstrated by using a short linear cavity. A total output power of 3.8 W can be obtained at an incident pump power of 8.2 W. The beat frequency Δfc between two orthogonally polarized mode-locked components is observed and measured precisely. It is found that the beat frequency increases linearly with an increase in the absorbed pump power. The origin of the beat frequency can be utterly manifested by considering the thermally induced birefringence in the Nd:YAG crystal. The present result offers a promising approach to generate orthogonally polarized mode-locked lasers with tunable beat frequency.

Multi-Fresnel lenses pumping approach for improving high-power Nd:YAG solar laser beam quality.

PubMed

Liang, Dawei; Almeida, Joana

2013-07-20

To significantly improve the present-day high-power solar laser beam quality, a three-stage multi-Fresnel lenses approach is proposed for side-pumping either a Nd:YAG single-crystal or a core-doped Sm(3+)Nd:YAG ceramic rod. Optimum pumping and laser beam parameters are found through ZEMAX and LASCAD numerical analysis. The proposed scheme offers a uniform absorption profile along the rod. 167 W laser power can be achieved, corresponding to 29.3 W/m(2) collection efficiency. High brightness figure of merit of 8.34 W is expected for the core-doped rod within a convex-concave resonator, which is 1300 times higher than that of the most-recent high-power solar laser.

Investigation of continuous wave and pulsed laser performance based on Nd3+:Gd0.6Y1.4SiO5 crystal

NASA Astrophysics Data System (ADS)

Feng, Chao; Liu, Zhaojun; Cong, Zhenhua; Shen, Hongbin; Li, Yongfu; Wang, Qingpu; Fang, Jiaxiong; Xu, Xiaodong; Xu, Jun; Zhang, Xingyu

2015-12-01

We systematically investigated a laser diode (LD) pumped Nd:GYSO (Nd3+:Gd0.6Y1.4SiO5) laser. The output power of the continuous wave laser was as high as 3.5 W with a slope efficiency of 31.8%. In the Q-switched operation; the laser exhibited dual-wavelengths output (1073.6 nm and 1074.7 nm) synchronously with a Cr4+:YAG as the saturable absorber (SA). Additionally, a passively mode-locked laser was demonstrated using a semiconductor SA mirror with a maximum average output power of 510 mW at a central wavelength of 1074 nm, while the pulse width of the laser was as short as 5 ps. Our experiment proved that the Nd:GYSO mixed crystal was a promising material for a solid-state laser.

Low-threshold, nanosecond, high-repetition-rate vortex pulses with controllable helicity generated in Cr,Nd:YAG self-Q-switched microchip laser

NASA Astrophysics Data System (ADS)

He, Hong-Sen; Chen, Zhen; Li, Hong-Bin; Dong, Jun

2018-05-01

A high repetition rate, nanosecond, pulsed optical vortex beam has been generated in a Cr,Nd:YAG self-Q-switched microchip laser pumped by the annular-beam formed with a hollow focus lens. The lasing threshold for vortex pulses is 0.9 W. A pulse width of 6.5 ns and a repetition rate of over 330 kHz have been achieved. The average output power of 1 W and the slope efficiency of 46.6% have been obtained. The helicity of the optical vortices has been controlled by adjusting the tilted angle between Cr,Nd:YAG crystal and output coupler. The work provides a new method for developing pulsed optical vortices for potential applications on quantum communication and optical trapping.

Nd:YAG laser ablation and acid resistance of enamel.

PubMed

Kwon, Yong Hoon; Kwon, Oh-Won; Kim, Hyung-Il; Kim, Kyo-Han

2003-09-01

The acid resistance of Nd:YAG laser-ablated enamel surfaces was studied by evaluating crystal structure, mineral distribution, and fluorescence radiance and image in the present study. For comparison, 37% phosphoric acid etching was performed. The formation of beta-tricalcium phosphate (beta-TCP) was confirmed in the laser-ablated surface. The Ca/P ratio increased after ablation due to mineral re-distribution. In contrast, the Ca/P ratio decreased after acid etching due to mineral loss. The laser-ablated enamels showed a smaller increase of fluorescence radiances and less clear laser confocal scanning microscope images than those observed in the acid-etched enamels. The former suggests a minimized mineral loss. The Nd:YAG laser irradiation will enhance the acid resistance and retard the carious progression in enamel.

Continuous-wave operation of a room-temperature, diode-laser-pumped, 946-nm Nd:YAG laser

NASA Technical Reports Server (NTRS)

Fan, T. Y.; Byer, Robert L.

1987-01-01

Single-stripe diode-laser-pumped operation of a continuous-wave 946-nm Nd:YAG laser with less than 10-mW threshold has been demonstrated. A slope efficiency of 16 percent near threshold was shown with a projected slope efficiency well above a threshold of 34 percent based on results under Rhodamine 6G dye-laser pumping. Nonlinear crystals for second-harmonic generation of this source were evaluated. KNbO3 and periodically poled LiNbO3 appear to be the most promising.

Ho:YAG Single Crystal Fiber: Fabrication and Optical Characterization

DTIC Science & Technology

2014-06-16

between the 5I8 and 5I7 energy levels. The results verified the absorption peaks suitable for in- band direct pumping at 1908 nm and 1932 nm with the...Efficient high-power Ho:YAG laser directly in- band pumped by a GaSb -based laser diode stack at 1.9 μm,” Appl. Phys. B 106(2), 315–319 (2012). 21. M...characterized for its optical absorption and emission properties involving transitions between the 5I8 and 5I7 energy levels. The results verified

Nonlinear optical and microscopic analysis of Cu2+ doped zinc thiourea chloride (ZTC) monocrystal

NASA Astrophysics Data System (ADS)

Ramteke, S. P.; Anis, Mohd; Pandian, M. S.; Kalainathan, S.; Baig, M. I.; Ramasamy, P.; Muley, G. G.

2018-02-01

Organometallic crystals offer considerable nonlinear response therefore, present article focuses on bulk growth and investigation of Cu2+ ion doped zinc thiourea chloride (ZTC) crystal to explore its technological impetus for laser assisted nonlinear optical (NLO) device applications. The Cu2+ ion doped ZTC bulk single crystal of dimension 03 × 2.4 × 0.4 cm3 has been grown from pH controlled aqueous solution by employing slow solvent evaporation technique. The structural analysis has been performed by means of single crystal X-ray diffraction technique. The doping of Cu2+ ion in ZTC crystal matrix has been confirmed by means of energy dispersive spectroscopic (EDS) technique. The origin of nonlinear optical properties in Cu2+ ion doped ZTC crystal has been studied by employing the Kurtz-Perry test and Z-scan analysis. The remarkable enhancement in second harmonic generation (SHG) efficiency of Cu2+ ion doped ZTC crystal with reference to ZTC crystal has been determined. The He-Ne laser assisted Z-scan analysis has been performed to determine the third order nonlinear optical (TONLO) nature of grown crystal. The TONLO parameters such as susceptibility, absorption coefficient, refractive index and figure of merit of Cu-ZTC crystal have been evaluated using the Z-scan transmittance data. The laser damage threshold of grown crystal to high intensity of Nd:YAG laser is found to be 706.2 MW/cm2. The hardness number, work hardening index, yield strength and elastic stiffness coefficient of grown crystal has been investigated under microhardness study. The etching study has been carried out to determine the growth likelihood, nature of etch pits and surface quality of grown crystal.

Diode-pumped continuous-wave and passively Q-switched 1066 nm Nd:GYNbO4 laser

NASA Astrophysics Data System (ADS)

Ma, Yufei; Peng, Zhenfang; He, Ying; Li, Xudong; Yan, Renpeng; Yu, Xin; Zhang, Qingli; Ding, Shoujun; Sun, Dunlu

2017-08-01

A diode-pumped passively Q-switched 1066 nm laser with a novel Nd:Gd0.69Y0.3NbO4 mixed crystal was demonstrated for the first time to the best of our knowledge. In the continuous-wave (CW) operation, optimization selection of output couplers was carried out, and a maximum output power of 2.13 W was obtained when the plane mirror with transmission of 25% was chosen and the absorbed pump power was 10.5 W. The Cr4+:YAG passively Q-switched Nd:Gd0.69Y0.3NbO4 laser performance was investigated. At an absorbed pump power of 10.5 W, using Cr4+:YAG with initial transmission of 80%, the obtained minimum pulse width was 7.2 ns with the pulse repetition rate of 19 kHz. The single pulse energy and peak power were estimated to be 26.7 µJ and 3.7 kW, respectively.

Crystal growth, structural, optical, mechanical and thermal properties of a new nonlinear optical single crystal: L-Ornithine monohydrochloride.

PubMed

Balakrishnan, T; Ramamurthi, K

2009-03-01

Amino acid family crystals exhibit excellent nonlinear optical and electro optical properties. l-Ornithine monohydrochloride single crystal, belongs to the amino acid group, was grown by the slow evaporation solution growth technique at room temperature. The grown crystals were characterized by single crystal and powder X-ray diffraction analysis, Fourier transform infrared (FTIR) spectroscopy, TGA, DTA and DSC analyses. UV-vis-NIR spectrum shows excellent transmission in the UV, visible and NIR region (300-1600nm). The mechanical properties of grown crystals were studied using Vickers microhardness tester. Its second harmonic generation efficiency was tested using Nd:YAG laser and is 1.25 times that of KDP.

Research progress on laser crystals in China

NASA Astrophysics Data System (ADS)

Yingxia, Z.

1985-01-01

Current Chinese research on laser crystals is now quite extensive and involves more than 30 research teams with nearly 1,000 technicians and workers actively engaged in the study of more than 20 types of laser cyrstals. Neodymium-doped yttrium aluminum garnet (Nd:YAG) and ruby (Cr:Al2O3) lasers have been manufactured and are widely employed. There are several new and promising crystals now under study which will find applications, and both basic and exploratory research have given rise to new developments.

Fabrication of optical element from unidirectional grown imidazole-imidazolium picrate monohydrate (IIP) organic crystals for nonlinear optical applications

NASA Astrophysics Data System (ADS)

Vivek, P.; Murugakoothan, P.

2014-12-01

Nonlinear optical bulk single crystal of Imidazole-imidazolium picrate monohydrate (IIP) has been grown by Sankaranarayanan-Ramasamy (SR) method using acetonitrile as solvent. First time we report the bulk growth of IIP crystal by SR method. The transparent IIP single crystal of maximum diameter 21 mm and length 46 mm was obtained by employing SR method. The grown crystal was subjected to high resolution X-ray diffraction, UV-vis-NIR transmittance, refractive index, hardness, dielectric and laser damage threshold studies. The crystalline perfection of the grown crystal was analyzed using HRXRD. Cut off wavelength and optical transmission window of the crystal was assessed by UV-vis-NIR and the refractive index of the crystal was found. The mechanical property of the crystal was estimated by Vicker's hardness test. The dielectric property of the crystal was measured as a function of frequency. The laser damage threshold value was determined. The particle size dependent second harmonic generation efficiency for IIP was evaluated with standard reference material potassium dihydrogen phosphate (KDP) by Kurtz-Perry powder method using Nd:YAG laser, which established the existence of phase matching. The second harmonic generation (SHG) of IIP crystal was investigated by the SHG Maker fringes technique. The mechanism of growth is revealed by carrying out chemical etching using acetonitrile as etchant.

Phase-matching properties of yellow color HgGa₂S₄ for SHG and SFG in the 0.944-10.5910  μm range.

PubMed

Kato, Kiyoshi; Petrov, Valentin; Umemura, Nobuhiro

2016-04-20

We report new experimental results on the phase-matching properties of yellow color HgGa₂S₄ crystals for harmonic generation of an Nd:YAG laser-pumped KTiOPO₄ (KTP) optical parametric oscillator (OPO) and CO₂ lasers in the 0.944-10.5910 μm range. In addition, we present new Sellmeier equations that provide a good reproduction of the present experimental results as well as the published data points for second-harmonic generation of CO₂ laser radiation at 9.2197-9.6392 μm and Nd:YAG laser-pumped OPOs at 1.205-1.725 μm and 2.77-9.10 μm that were achieved with the orange and yellow color crystals.

Czochralski and modified Bridgman-Stockbarger growth of pure, Cd 2+ and Nd 3+ doped benzil single crystals

NASA Astrophysics Data System (ADS)

Aggarwal, M. D.; Wang, W. S.; Tambwe, M.

1993-03-01

Pure, Cd2+ and Nd3+-doped benzil C6H5COCOC6H5 have been grown from melt using the Czochralski and modified Bridgman-Stockbarger methods. Angle-tuned second harmonic generation of pure benzil from Nd:YAG laser radiation of λ = 1.06 μm with a conversion efficiency η = I2w/Iw = 0.4% has been demonstrated. We have used a Nd:YAG pulse laser to measure the radiation damage threshold as 15.9 MW/cm2 (c-axis) and 23.9 MW/cm2 (a-axis) under the conditions that laser pulse width is 10 ns. Under the same conditions, the conversion efficiency of Nd3+ and Cd2+-doped benzil, η= I2w/Iw = 1.1%, has been demonstrated. The radiation threshold is higher than for pure benzil crystals.

80-W green KTP laser used in photoselective laser vaporization of the prostrate by frequency doubling of Yb 3+ -doped large-mode area fiber laser

NASA Astrophysics Data System (ADS)

Xia, Hongxing; Li, Zhengjia

2007-05-01

Photoselective laser vaporization of the prostate (PVP) is the most promising method for the treatment of benign prostatic hyperplasia (BPH), but KTP lasers used in PVP with lamp-pumped are low efficient .To increase the efficiency , we develop a 80-W, 400kHz, linearly polarized green laser based on a frequency-doubled fiber laser. A polarization-maintaining large-mode area (LMA) fiber amplifier generate polarized 1064nm fundamental wave by amplifying the seed signal from a composite Cr 4+:YAG-Nd 3+:YAG crystal fiber laser. The fundamental wave is injected into a KTP crystal with confined temperature management to achieve second harmonic generation (SHG). The overall electrical efficiency to the green portion of the spectrum is 10%.80-W maintenance-free long-lifetime KTP laser obtained can well satisfy the need of PVP.

A protected annealing strategy to enhanced light emission and photostability of YAG:Ce nanoparticle-based films

NASA Astrophysics Data System (ADS)

Revaux, Amelie; Dantelle, Geraldine; George, Nathan; Seshadri, Ram; Gacoin, Thierry; Boilot, Jean-Pierre

2011-05-01

A significant obstacle in the development of YAG:Ce nanoparticles as light converters in white LEDs and as biological labels is associated with the difficulty of finding preparative conditions that allow simultaneous control of structure, particle size and size distribution, while maintaining the optical properties of bulk samples. Preparation conditions frequently involve high-temperature treatments of precursors (up to 1400 °C), which result in increased particle size and aggregation, and lead to oxidation of Ce(iii) to Ce(iv). We report here a process that we term protected annealing, that allows the thermal treatment of preformed precursor particles at temperatures up to 1000 °C while preserving their small size and state of dispersion. In a first step, pristine nanoparticles are prepared by a glycothermal reaction, leading to a mixture of YAG and boehmite crystalline phases. The preformed nanoparticles are then dispersed in a porous silica. Annealing of the composite material at 1000 °C is followed by dissolution of the amorphous silica by hydrofluoric acid to recover the annealed particles as a colloidal dispersion. This simple process allows completion of YAG crystallization while preserving their small size. The redox state of Ce ions can be controlled through the annealing atmosphere. The obtained particles of YAG:Ce (60 +/- 10 nm in size) can be dispersed as nearly transparent aqueous suspensions, with a luminescence quantum yield of 60%. Transparent YAG:Ce nanoparticle-based films of micron thickness can be deposited on glass substrates using aerosol spraying. Films formed from particles prepared by the protected annealing strategy display significantly improved photostability over particles that have not been subject to such annealing.A significant obstacle in the development of YAG:Ce nanoparticles as light converters in white LEDs and as biological labels is associated with the difficulty of finding preparative conditions that allow simultaneous control of structure, particle size and size distribution, while maintaining the optical properties of bulk samples. Preparation conditions frequently involve high-temperature treatments of precursors (up to 1400 °C), which result in increased particle size and aggregation, and lead to oxidation of Ce(iii) to Ce(iv). We report here a process that we term protected annealing, that allows the thermal treatment of preformed precursor particles at temperatures up to 1000 °C while preserving their small size and state of dispersion. In a first step, pristine nanoparticles are prepared by a glycothermal reaction, leading to a mixture of YAG and boehmite crystalline phases. The preformed nanoparticles are then dispersed in a porous silica. Annealing of the composite material at 1000 °C is followed by dissolution of the amorphous silica by hydrofluoric acid to recover the annealed particles as a colloidal dispersion. This simple process allows completion of YAG crystallization while preserving their small size. The redox state of Ce ions can be controlled through the annealing atmosphere. The obtained particles of YAG:Ce (60 +/- 10 nm in size) can be dispersed as nearly transparent aqueous suspensions, with a luminescence quantum yield of 60%. Transparent YAG:Ce nanoparticle-based films of micron thickness can be deposited on glass substrates using aerosol spraying. Films formed from particles prepared by the protected annealing strategy display significantly improved photostability over particles that have not been subject to such annealing. Electronic supplementary information (ESI) available: Thermogravimetric analysis curve, picture of a YAG:Ce3+ thin film. See DOI: 10.1039/c0nr01000f

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Thermally induced optical damage to barium-sodium niobate crystals

NASA Astrophysics Data System (ADS)

Baryshev, S. A.; Goncharova, I. F.; Konvisar, P. G.; Kuznetsov, V. A.

1990-06-01

Thermally induced optical damage (TIOD) was observed in undoped barium-sodium niobate (BSN) crystals as a result of changes in their temperature. This damage was deduced from the behavior of YAG:Nd3+ laser radiation when a BSN crystal was inserted in the resonator and also using a helium-neon laser probe beam. The experimental results were satisfactorily explained by the familiar pyroelectric model of TIOD and, in the crystals studied, an inhomogeneity of the conductivity rather than an inhomogeneity of the pyroelectric constant played the main role.

Phase-matching properties of BaGa₄Se₇ for SHG and SFG in the 0.901-10.5910  μm range.

PubMed

Kato, Kiyoshi; Miyata, Kentaro; Petrov, Valentin

2017-04-10

We report new experimental results on the phase-matching properties of a BaGa₄Se₇ crystal for harmonic generation of a Nd:YAG laser-pumped AgGaS₂ optical parametric oscillator (OPO) and a CO₂ laser in the 0.901-10.5910 μm range. In addition, we present new Sellmeier equations that provide a good reproduction of the present experimental results as well as the published data points for a Nd:YAG laser-pumped OPO and an optical parametric amplifier (OPA) in the 3.10-15.22 μm range and a Ho:YAG laser-pumped OPA in the 3.49-5.18 μm range.

Growth and characterization of hexamethylenetetramine crystals grown from solution

NASA Astrophysics Data System (ADS)

Babu, B.; Chandrasekaran, J.; Balaprabhakaran, S.

2014-06-01

Organic nonlinear optical single crystals of hexamethylenetetramine (HMT; 10 × 10 × 5 mm3) were prepared by crystallization from methanol solution. The grown crystals were subjected to various characterization techniques such as single crystal XRD, powder XRD, UV-Vis and electrical studies. Single crystal XRD analysis confirmed the crystalline structure of the grown crystals. Their crystalline nature was also confirmed by powder XRD technique. The optical transmittance property was identified from UV-Vis spectrum. Dielectric measurements were performed as a function of frequency at different temperatures. DC conductivity and photoconductivity studies were also carried out for the crystal. The powder second harmonic generation efficiency (SHG) of the crystal was measured using Nd:YAG laser and the efficiency was found to be two times greater than that of potassium dihydrogen phosphate (KDP).

Electronic refractive index changes and measurement of saturation intensity in Cr3+-doped YAG crystal

NASA Astrophysics Data System (ADS)

Kesavulu, C. R.; Moncorgé, R.; Fromager, M.; Ait-Ameur, K.; Catunda, T.

2018-04-01

The electronic refractive index variation is associated with the difference in the polarizabilities (Δαp) of the Cr3+ ion in its ground and excited states. In order to further address the physical origin of Δαp in a Cr3+-doped YAG crystal, time-resolved Z-scan measurements were performed and analyzed at λ = 457 nm by using a chopped Ar+ ion laser. It is found a nonlinear refractive index with the real and imaginary parts n2‧ = 2.2 × 10-8 cm2/W and n2‧‧ = 2.8 × 10-10 cm2/W, respectively. The real part is associated with a polarizability difference Δαp = 2.2 × 10-25 cm3. The imaginary part indicates that excited state absorption (ESA) occurs and that Cr:YAG behaves as a saturable absorber. The transient response of the Z-scan signal decreases with the laser intensity as τ-1 = τo-1(1+I/Is), where τo is the excited state lifetime and Is the saturation intensity. By measuring this transient response at different laser intensities, it was possible to confirm the τo value which can be derived from fluorescence measurements and to determine a Is value of 8.3 kW/cm2.

Growth and characterization of Bis(L-threonine) copper (II) monohydrate single crystals: A semiorganic second order nonlinear optical material

NASA Astrophysics Data System (ADS)

Subhashini, R.; Sathya, D.; Sivashankar, V.; Latha Mageshwari, P. S.; Arjunan, S.

2016-12-01

Highly transparent solitary nonlinear semiorganic optical material Bis(L-threonine) copper (II) monohydrate [BLTCM], was synthesized by a conventional slow evaporation solution growth technique. The grown crystals were subjected to structural, optical, electrical, thermal, mechanical, SHG and Laser damage threshold studies. Single crystal XRD shows that the material crystallizes in monoclinic system with noncentrosymmetric space group P21. FT-IR and FT-RAMAN analyses confirm the various functional groups present in the grown crystal. The transparency range of BLTCM was determined by UV-vis-NIR studies and various optical constants such as extinction coefficient (K), refractive index, optical conductivity and electric susceptibility with real and imaginary parts of dielectric constant were calculated using the transmittance data which have applications in optoelectronic devices. Dielectric studies of the crystal were carried out at different frequencies and temperatures to analyze the electrical properties. TGA and DSC analyses were performed to study the thermal behaviour of the sample. The hardness stability of the grown specimen was investigated by Vickers microhardness test. The output intensity of second harmonic generation was confirmed using the Kurtz and Perry powder method. The laser induced surface damage threshold of the crystal was measured using Nd:YAG laser.

Comparative research on medicine application with 0.53-um, 1.06-um, and 1.32-um Nd:YAG lasers

NASA Astrophysics Data System (ADS)

Li, Yahua; Li, Zhenjia; Zhu, Changhong; Huang, Yizhong

1996-09-01

Because of its high power and excellent optical features, laser has almost been applied to everywhere of medical research and clinic. Over the past several years, laser medical has achieved a rapid progress, and laser medical instruments has developed promptly, each new wavelength can be successfully applied in diagnostic and treatment of diseases. Among the medical lasers, Nd:YAG solid-state laser systems have proven useful in surgical use operate, such as neurosurgery, gastroenterology, cardioangiology, urology, gynecology, dermatology and ENT. As with other solid-state lasers, the Nd:YAG laser can be made to emit various wavelengths by means of suitable resonator configurations and some newest solid-state laser technology, pumped by the Krypton lamp, the Nd:YAG laser at room temperature exhibits transition at 1.06 micrometer Nd:YAG, using nonlinear crystal and Q-switch to double its frequency can attain 0.53 micrometer green beam. In our laser systems, the efficiency at 1.06 micrometer is more than 3 percent, an efficiency of 0.5 percent at 1.32 micrometer and 0.53 micrometer can be attained. For a power of 100w at 1.06 micrometer, 15w at 1.32 micrometer and 0.53 micrometer can therefore be produced. All of three kinds Nd:YAG laser hold these characteristics: high output power; optical fiber transition that can be cooperated with endoscope. The paper mainly discusses laser operating characteristics and clinic applications of three kinds wavelengths at 0.53 micrometer 1.06 micrometer and 1.32 micrometer Nd:YAG laser systems.

Two-dimensional microsphere quasi-crystal: fabrication and properties

NASA Astrophysics Data System (ADS)

Noginova, Natalia E.; Venkateswarlu, Putcha; Kukhtarev, Nickolai V.; Sarkisov, Sergey S.; Noginov, Mikhail A.; Caulfield, H. John; Curley, Michael J.

1996-11-01

2D quasi-crystals were fabricated from polystyrene microspheres and characterized for their structural, diffraction, and non-linear optics properties. The quasi- crystals were produced with the method based on Langmuir- Blodgett thin film technique. Illuminating the crystal with the laser beam, we observed the diffraction pattern in the direction of the beam propagation and in the direction of the back scattering, similar to the x-ray Laue pattern observed in regular crystals with hexagonal structure. The absorption spectrum of the quasi-crystal demonstrated two series of regular maxima and minima, with the spacing inversely proportional to the microspheres diameter. Illumination of the dye-doped microspheres crystal with Q- switched radiation of Nd:YAG laser showed the enhancement of non-linear properties, in particular, second harmonic generation.

Structural and optical behavior due to thermal effects in end-pumped Yb:YAG disk lasers.

PubMed

Sazegari, Vahid; Milani, Mohammad Reza Jafari; Jafari, Ahmad Khayat

2010-12-20

We employ a Monte Carlo ray-tracing code along with the ANSYS package to predict the optical and structural behavior in end-pumped CW Yb:YAG disk lasers. The presence of inhomogeneous temperature, stress, and strain distributions is responsible for many deleterious effects for laser action through disk fracture, strain-induced birefringence, and thermal lensing. The thermal lensing, in turn, results in the optical phase distortion in solid-state lasers. Furthermore, the dependence of optical phase distortion on variables such as the heat transfer coefficient, the cooling fluid temperature, and crystal thickness is discussed.

A solid state tunable laser for resonance measurements of atmospheric sodium

NASA Technical Reports Server (NTRS)

Philbrick, C. R.; Bufton, J. L.; Gardner, C. S.

1985-01-01

The measurement of wave dynamics in the upper mesosphere using a solid-state laser to excite the resonance fluorescence line of sodium is examined. Two Nd:YAG lasers are employed to produce the sodium resonance line. The method involves mixing the 1064 nm radiation with that from a second Nd:YAG operating at 1319 nm in a nonlinear infrared crystal to directly produce 589 nm radiation by sum frequency generation. The use of the transmitter to measure the sodium layer from the Space Shuttle Platform is proposed. A diagram of the laser transmitter is presented.

Theoretical modeling of diode-laser-pumped 3-μm Er3+ crystal lasers

NASA Astrophysics Data System (ADS)

Tikerpae, Mark; Jackson, Stuart D.; King, Terence A.

1997-05-01

We present results from a theoretical model that has been developed to simulate the 3-micrometer laser transition in Er3+ doped Y3Al5O12 (YAG), Y2Sc2Ga3O12 (YSGG), LiYF4 (YLF) and BaY2F8 (BaYF) host crystals. The rate equations for the lowest seven energy levels of Er3+ were solved numerically and laser action was simulated under cw, gain-switched (pulse pumped) and Q-switched operation with optical pumping at wavelengths of 975 nm and 795 nm. The relative performance of each laser crystal was compared under identical pumping and cavity conditions to establish the optimum crystal host, doping concentration and pump wavelength for each mode of operation. Some unexpected saturation effects were investigated that could limit the maximum practical pump fluence used for high energy Q-switched systems. We investigate possible additional multi-ion energy transfer processes that may cause the decrease in efficiency that is observed experimentally at high Er3+ ion concentrations. In addition, lower laser level deactivation by co-doping with Pr3+ in BaYF was simulated and compared with singly doped Er:BaYF for a range of Er3+ and Pr3+ concentrations. It was found that co-doping was not as effective as the cooperative upconversion process present in singly doped Er3+ crystals for efficient laser operation.

Studies on the growth aspects, structural, thermal, dielectric and third order nonlinear optical properties of solution grown 4-methylpyridinium p-nitrophenolate single crystal

NASA Astrophysics Data System (ADS)

Devi, S. Reena; Kalaiyarasi, S.; Zahid, I. MD.; Kumar, R. Mohan

2016-11-01

An ionic organic optical crystal of 4-methylpyridinium p-nitrophenolate was grown from methanol by slow evaporation method at ambient temperature. Powder and single crystal X-ray diffraction studies revealed the crystal system and its crystalline perfection. The rocking curve recorded from HRXRD study confirmed the crystal quality. FTIR spectral analysis confirmed the functional groups present in the title compound. UV-visible spectral study revealed the optical window and band gap of grown crystal. The thermal, electrical and surface laser damage threshold properties of harvested crystal were examined by using TGA/DTA, LCR/Impedance Analyzer and Nd:YAG laser system respectively. The third order nonlinear optical property of grown crystal was elucidated by Z-scan technique.

Nd:(Gd0.3Y0.7)2SiO5 crystal: A novel efficient dual-wavelength continuous-wave medium

NASA Astrophysics Data System (ADS)

Xu, Xiaodong; Di, Juqing; Zhang, Jian; Tang, Dingyuan; Xu, Jun

2016-05-01

Efficient dual-wavelength continuous-wave (CW) and passively Q-switched laser operation of Nd:(Gd0.3Y0.7)2SiO5 crystal were investigated for the first time to our knowledge. Maximum CW output power of 2.3 W was obtained under the absorbed pump power of 4.6 W, corresponding to the slope efficiency of 55%. Dual-wavelength CW laser with respective wavelengths around 1074 nm and 1078 nm were achieved. With Cr4+:YAG as the saturable absorber, passive Q-switched performance was obtained. The slope efficiency of passively Q-switched operation was 45%. The shortest pulse width, the corresponding pulse energy and peak power were calculated to be 13.1 ns, 50.2 μJ and 3.8 kW, respectively.

Positive hysteresis of Ce-doped GAGG scintillator

NASA Astrophysics Data System (ADS)

Yanagida, Takayuki; Fujimoto, Yutaka; Koshimizu, Masanori; Watanabe, Kenichi; Sato, Hiroki; Yagi, Hideki; Yanagitani, Takagimi

2014-10-01

Positive hysteresis and radiation tolerance to high-dose radiation exposure were investigated for Ce 1% and 3% doped Gd3(Al, Ga)5O12 (Ce:GAGG) crystal scintillator on comparison with other garnet scintillators such Ce:YAG, Ce:LuAG, Pr:LuAG, and ceramic Ce:GAGG. When they were irradiated by several Gy 60Co γ-rays, Ce 1% doped GAGG crystal exhibited ∼20% light yield enhancement (positive hysteresis). This is the first time to observe positive hysteresis in Ce doped GAGG. On the other hand, other garnet materials did not show the positive hysteresis and their light yields were stable after 800 Gy irradiation except Pr:LuAG. The light yield of Pr:LuAG decreased largely. When irradiated Ce:GAGG which showed positive hysteresis was evaluated in Synchrotron facility (UVSOR), new excitation band was created around 60 nm.

Synthesis, growth, structural, thermal and optical studies of pyrrolidinium-2-carboxylate-4-nitrophenol single crystals.

PubMed

Swarna Sowmya, N; Sampathkrishnan, S; Vidyalakshmi, Y; Sudhahar, S; Mohan Kumar, R

2015-06-15

Organic nonlinear optical material, pyrrolidinium-2-carboxylate-4-nitrophenol (PCN) was synthesized and single crystals were grown by slow evaporation solution growth method. Single crystal X-ray diffraction analysis confirmed the structure and lattice parameters of PCN crystals. Infrared, Raman and NMR spectral analyses were used to elucidate the functional groups present in the compound. The thermal behavior of synthesized compound was studied by thermogravimetric and differential scanning calorimetry (TG-DSC) analyses. The photoluminescence property was studied by exciting the crystal at 360 nm. The relative second harmonic generation (SHG) efficiency of grown crystal was estimated by using Nd:YAG laser with fundamental wavelength of 1,064 nm. Copyright © 2015 Elsevier B.V. All rights reserved.

885-nm Pumped Ceramic Nd:YAG Master Oscillator Power Amplifier Laser System

NASA Technical Reports Server (NTRS)

Yu, Anthony

2012-01-01

The performance of a traditional diode pumped solid-state laser that is typically pumped with 808-nm laser diode array (LDA) and crystalline Nd:YAG was improved by using 885-nm LDAs and ceramic Nd:YAG. The advantage is lower quantum defect, which will improve the thermal loading on laser gain medium, resulting in a higher-performance laser. The use of ceramic Nd:YAG allows a higher Nd dopant level that will make up the lower absorption at the 885-nm wavelength on Nd:YAG. When compared to traditional 808-nm pump, 885-nm diodes will have 30% less thermal load (or wasted heat) and will thus see a similar percentage improvement in the overall laser efficiency. In order to provide a more efficient laser system for future flight missions that require the use of low-repetition- rate (1% Nd. To make certain that the absorption at 885 nm is on the same par as the 808-nm diode, the Nd:YAG material needs to be doped with higher concentration of Nd. Ceramic Nd:YAG is the only material that can be tailored to specific needs.

Injection seeded, diode pumped regenerative ring Nd:YAG amplifier for spaceborne laser ranging technology development

NASA Technical Reports Server (NTRS)

Coyle, D. Barry; Kay, Richard B.; Degnan, John J.; Krebs, Danny J.; Seery, Bernard D.

1992-01-01

A small, all solid state, regenerative ring amplifier designed as a prototype for space application is discussed. Novel features include dual side pumping of the Nd:YAG crystal and a triangular ring cavity design which minimizes the number of optical components and losses. The amplifier is relatively small (3 ns round trip time) even though standard optical elements are employed. The ring regeneratively amplifies a 100 ps single pulse by approximately 10(exp 5) at a repetition rate of 10 to 100 Hz. The amplifier is designed to be injection seeded with a pulsed, 100 ps laser diode at 1.06 microns, but another Nd:YAG laser system supplying higher pulse energies was employed for laboratory experiment. This system is a prototype laser oscillator for the Geoscience Laser Ranging System (GLRS) platform. Results on measurements of beam quality, astigmatism, and gain are given.

Diode pumped, regenerative Nd:YAG ring amplifier for space application

NASA Technical Reports Server (NTRS)

Coyle, D. B.; Kay, Richard B.; Degnan, John J.; Krebs, Danny J.; Seery, Bernard D.

1992-01-01

The study reviews the research and development of a prototype laser used to study one possible method of short-pulse production and amplification, in particular, a pulsed Nd:YAG ring laser pumped by laser diode arrays and injected seeded by a 100-ps source. The diode array pumped, regenerative amplifier consists of only five optical elements, two mirrors, one thin film polarizer, one Nd:YAG crystal, and one pockels cell. The pockels cell performed both as a Q-switch and a cavity dumper for amplified pulse ejection through the thin film polarizer. The total optical efficiency was low principally due to the low gain provided by the 2-bar pumped laser head. After comparison with a computer model, a real seed threshold of about 10 exp -15 J was achieved because only about 0.1 percent of the injected energy mode-matched with the ring.

Compact, passively Q-switched, all-solid-state master oscillator-power amplifier-optical parametric oscillator (MOPA-OPO) system pumped by a fiber-coupled diode laser generating high-brightness, tunable, ultraviolet radiation.

PubMed

Peuser, Peter; Platz, Willi; Fix, Andreas; Ehret, Gerhard; Meister, Alexander; Haag, Matthias; Zolichowski, Paul

2009-07-01

We report on a compact, tunable ultraviolet laser system that consists of an optical parametric oscillator (OPO) and a longitudinally diode-pumped Nd:YAG master oscillator-power amplifier (MOPA). The pump energy for the whole laser system is supplied via a single delivery fiber. Nanosecond pulses are produced by an oscillator that is passively Q-switched by a Cr(4+):YAG crystal. The OPO is pumped by the second harmonic of the Nd:YAG MOPA. Continuously tunable radiation is generated by an intracavity sum-frequency mixing process within the OPO in the range of 245-260 nm with high beam quality. Maximum pulse energies of 1.2 mJ were achieved, which correspond to an optical efficiency of 3.75%, relating to the pulse energy of the MOPA at 1064 nm.

Investigations on nucleation, HRXRD, optical, piezoelectric, polarizability and Z-scan analysis of L-arginine maleate dihydrate single crystals

NASA Astrophysics Data System (ADS)

Sakthy Priya, S.; Alexandar, A.; Surendran, P.; Lakshmanan, A.; Rameshkumar, P.; Sagayaraj, P.

2017-04-01

An efficient organic nonlinear optical single crystal of L-arginine maleate dihydrate (LAMD) has been grown by slow evaporation solution technique (SEST) and slow cooling technique (SCT). The crystalline perfection of the crystal was examined using high-resolution X-ray diffractometry (HRXRD) analysis. Photoluminescence study confirmed the optical properties and defects level in the crystal lattice. Electromechanical behaviour was observed using piezoelectric co-efficient (d33) analysis. The photoconductivity analysis confirmed the negative photoconducting nature of the material. The dielectric constant and loss were measured as a function of frequency with varying temperature and vice-versa. The laser damage threshold (LDT) measurement was carried out using Nd:YAG Laser with a wavelength of 1064 nm (Focal length is 35 cm) and the obtained results showed that LDT value of the crystal is high compared to KDP crystal. The high laser damage threshold of the grown crystal makes it a potential candidate for second and higher order nonlinear optical device application. The third order nonlinear optical parameters of LAMD crystal is determined by open-aperture and closed-aperture studies using Z-scan technique. The third order linear and nonlinear optical parameters such as the nonlinear refractive index (n2), two photon absorption coefficient (β), Real part (Reχ3) and imaginary part (Imχ3) of third-order nonlinear optical susceptibility are calculated.

Growth and characterization of organic material 4-dimethylaminobenzaldehyde single crystal.

PubMed

Jebin, R P; Suthan, T; Rajesh, N P; Vinitha, G; Madhusoodhanan, U

2015-01-25

The organic material 4-dimethylaminobenzaldehyde single crystals were grown by slow evaporation technique. The grown crystal was confirmed by the single crystal and powder X-ray diffraction analyses. The functional groups of the crystal have been identified from the Fourier Transform Infrared (FTIR) and FT-Raman studies. The optical property of the grown crystal was analyzed by UV-Vis-NIR and photoluminescence (PL) spectral measurements. The thermal behavior of the grown crystal was analyzed by thermogravimetric (TG) and differential thermal analyses (DTA). Dielectric measurements were carried out with different frequencies by using parallel plate capacitor method. The third order nonlinear optical properties of 4-dimethylaminobenzaldehyde was measured by the Z-scan technique using 532 nm diode pumped continuous wave (CW) Nd:YAG laser. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of caries progression on dentin after irradiation with Nd:YAG laser by FTIR spectroscopy and fluorescence imaging

NASA Astrophysics Data System (ADS)

Ana, P. A.; Brito, A. M. M.; Zezell, D. M.; Lins, E. C. C. C.

2015-06-01

Considering the use of high intensity lasers for preventing dental caries, this blind in vitro study evaluated the compositional and fluorescence effects promoted by Nd:YAG laser (λ=1064 nm) when applied for prevention of progression of dentin caries, in association or not with topical application of acidulated phosphate fluoride (APF). Sixty bovine root dentin slabs were prepared and demineralized by 32h in order to create early caries lesions. After, the slabs were distributed into six experimental groups: G1- untreated and not submitted to a pH-cycling model; G2- untreated and submitted to a pH-cycling model; G3- acidulated phosphate fluoride application (APF); G4- Nd:YAG irradiation (84.9 J/cm2, 60 mJ/pulse); G5- treated with Nd:YAG+APF; G6- treated with APF+Nd:YAG. After treatments, the samples of groups G2 to G6 were submitted to a 4-day pH-cycling model in order to simulate the progression of early caries lesions. All samples were characterized by the micro-attenuated total reflection technique of Fourier transformed infrared spectroscopy (μATR-FTIR), using a diamond crystal, and by a fluorescence imaging system (FIS), in which it was used an illuminating system at λ= 405±30 nm. Demineralization promoted reduction in carbonate and phosphate contents, exposing the organic matter; as well, it was observed a significant reduction of fluorescence intensity. Nd:YAG laser promoted additional chemical changes, and increased the fluorescence intensity even with the development of caries lesions. It was concluded that the compositional changes promoted by Nd:YAG, when associated to APF, are responsible for the reduction of demineralization progression observed on root dentin.

Rare Earth Garnet Selective Emitter

NASA Technical Reports Server (NTRS)

Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

1994-01-01

Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approx. = 0.75, sup 4)|(sub 15/2) - (sup 4)|(sub 13/2),for Er-YAG and epsilon(sub lambda) approx. = 0.65, (sup 5)|(sub 7) - (sup 5)|(sub 8) for Ho-YAG) at 1500 K. In addition, low out-of-band spectral emittance, epsilon(sub lambda) less than 0.2, suggest these materials would be excellent candidates for high efficiency selective emitters in thermophotovoltaic (TPV) systems operating at moderate temperatures (1200-1500 K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. Selective emitters in the near IR are of special interest for thermophotovoltaic (TPV) energy conversion. The most promising solid selective emitters for use in a TPV system are rare earth oxides. Early spectral emittance work on rare earth oxides showed strong emission bands in the infrared (0.9 - 3 microns). However, the emittance outside the emission band was also significant and the efficiency of these emitters was low. Recent improvements in efficiency have been made with emitters fabricated from fine (5 - 10 microns) rare earth oxide fibers similar to the Welsbach mantle used in gas lanterns. However, the rare earth garnet emitters are more rugged than the mantle type emitters. A thin film selective emitter on a low emissivity substrate such as gold, platinum etc., is rugged and easily adapted to a wide variety of thermal sources. The garnet structure and its many subgroups have been successfully used as hosts for rare earth ions, introduced as substitutional impurities, in the development of solid state laser crystals. Doping, dependent on the particular ion and crystal structure, may be as high as 100 at. % (complete substitution of yttrium ion with the rare earth ion). These materials have high melting points, 1940 C for YAG (Yttrium Aluminum Garnet), and low emissivity in the near infrared making them excellent candidates for a thin film selective emitter. As previously stated, the spectral emittance of a rare earth emitter is characterized by one or more well defined emission bands. Outside the emission band the emittance(absorptance) is much lower. Therefore, it is expected that emission outside the band for a thin film selective emitter will be dominated by the emitter substrate. For an efficient emitter (power in the emission band/total emitted power) the substrate must have low emittance, epsilon(sub S). This paper presents normal spectral emittance, epsilon(sub lambda), measurements of holmium(Ho) and erbium (Er) doped YAG thin film selective emitters at (1500 K), and compares those results with the theoretical spectral emittance.

High power high repetition rate VCSEL array side-pumped pulsed blue laser

NASA Astrophysics Data System (ADS)

van Leeuwen, Robert; Zhao, Pu; Chen, Tong; Xu, Bing; Watkins, Laurence; Seurin, Jean-Francois; Xu, Guoyang; Miglo, Alexander; Wang, Qing; Ghosh, Chuni

2013-03-01

High power, kW-class, 808 nm pump modules based on the vertical-cavity surface-emitting laser (VCSEL) technology were developed for side-pumping of solid-state lasers. Two 1.2 kW VCSEL pump modules were implemented in a dual side-pumped Q-switched Nd:YAG laser operating at 946 nm. The laser output was frequency doubled in a BBO crystal to produce pulsed blue light. With 125 μs pump pulses at a 300 Hz repetition rate 6.1 W QCW 946 nm laser power was produced. The laser power was limited by thermal lensing in the Nd:YAG rod.

Design of ultrahigh brightness solar-pumped disk laser.

PubMed

Liang, Dawei; Almeida, Joana

2012-09-10

To significantly improve the solar-pumped laser beam brightness, a multi-Fresnel lens scheme is proposed for side-pumping either a single-crystal Nd:YAG or a core-doped ceramic Sm(3+) Nd:YAG disk. Optimum laser system parameters are found through ZEMAX and LASCAD numerical analysis. An ultrahigh laser beam figure of merit B of 53 W is numerically calculated, corresponding to a significant enhancement of more than 180 times over the previous record. 17.7 W/m(2) collection efficiency is also numerically attained. The strong thermal effects that have hampered present-day rod-type solar-pumped lasers can also be largely alleviated.

36 W Q-switched Ho:YAG laser at 2097 nm pumped by a Tm fiber laser: evaluation of different Ho3+ doping concentrations

NASA Astrophysics Data System (ADS)

Antipov, O. L.; Eranov, I. D.; Kositsyn, R. I.

2017-01-01

A laser oscillator based on Ho:YAG crystal pumped by a Tm fiber laser with an acousto-optical Q-switch was optimized for maximum output power and pulse-to-pulse stability. Stable operation at 2097 nm in Q-switched mode is demonstrated, with pulse repetition rates from 10 to 30 kHz, and output power of 36 W (at 55 W of pump power at 1908 nm) in the good quality beam. The influence of Ho ion up-conversion and thermal lensing on the oscillation efficiency is discussed.

Growth and characterization of an efficient new NLO single crystal L-phenylalanine D-methionine for frequency conversion and optoelectronic applications

NASA Astrophysics Data System (ADS)

Sangeetha, P.; Jayaprakash, P.; Nageshwari, M.; Rathika Thaya Kumari, C.; Sudha, S.; Prakash, M.; Vinitha, G.; Lydia Caroline, M.

2017-11-01

Optically active single crystals of L-phenylalanine D-methionine (LPDM) were grown by slow evaporation technique by co-crystallization of amino acids L-phenylalanine and D-methionine in water. The unit cell dimensions have been identified from single crystal X-ray diffraction technique. The existences of various hydrocarbyls were examined by FTIR and FT-Raman spectroscopy. The carbon and hydrogen environment of the grown crystals were analyzed by FT NMR spectrum. The optical absorption studies show that the crystal is transparent in the visible region with a lower cut-off wavelength of 259 nm and there by optical band gap energy Eg is calculated to be 5.35 eV. The Urbach energy, extinction coefficient, reflectance were calculated from UV-absorption data. Further, the thermal stability and accurate melting point has been investigated by TG/DSC techniques. The Kurtz powder SHG was confirmed using Nd:YAG laser with fundamental wavelength of 1064 nm. The dielectric behavior of the specimen has been determined for various temperatures (313 K, 333 K, 353 K, 373 K) at different frequencies. Fluorescence study and the time resolved decay calculation was also performed for the LPDM crystal. Optical nonlinear susceptibility was measured in LPDM and the real and imaginary part of χ3 was evaluated by Z-scan technique using open and closed apertures.

Chromium Recharging Processes in the Y3Al5O12: Mg, Cr Single Crystal under the Reducing and Oxidizing Annealing Influence

DTIC Science & Technology

2001-01-01

approximately 0.2% of total number of chromium ions occupied tetrahedral sites forming phototropic centers in the YAG: Mg, Cr crystal. Keywords: yttrium...aluminium garnet, Cr doping, thermal treatment, phototropic centers, optical characterization, electron paramagnetic resonance. 1. INTRODUCTION An...of garnet structure while the main part of chromium occupies octahedral sites in three-valence state. 10-12 The dependence of amount of phototropic

Growth and characterization of a novel nonlinear optical borate crystal - Yttrium calcium borate (YCB)

NASA Astrophysics Data System (ADS)

Arun Kumar, R.; Arivanandhan, M.; Dhanasekaran, R.; Hayakawa, Y.

2013-06-01

A new nonlinear optical single crystal yttrium calcium borate Y2CaB10O19 (YCB) was grown for the first time from its melt. The starting materials were prepared by the solid-state reaction method. The melting point of the synthesized material was identified to be 967 °C. YCB crystal exhibits monoclinic crystal structure with the space group C2. The crystalline perfection of the grown YCB crystal was found to be good. From the UV-VIS-NIR studies, the lower cutoff wavelength of the crystal occurs below 200 nm. The functional groups of the grown crystal were assigned using the FTIR data. The second harmonic generation (SHG) of the YCB crystal was observed using a Nd:YAG laser with a fundamental wavelength of 1064 nm. The laser damage threshold value of the YCB crystal was found to be very high - 10.5 GW/cm2.

Time-of-flight spectroscopy characterization of the plasma plume from a laser-ablated potassium titanyl phosphate crystal

NASA Astrophysics Data System (ADS)

Ying, Minju; Wang, XiaoXiao; Cheng, Wei; Liao, Bin; Zhang, Xu

2015-06-01

Optical emission spectra of the plasma produced by 1.06-μm Nd:YAG laser irradiation of a potassium titanyl phosphate (KTP) crystal were recorded and analyzed in a time- and spatially resolved manner. The composition and evolution of the plasma plume were studied in low vacuum conditions. Emission lines associated with Ti(I), Ti(II) and K(I) were identified in the plasma. The delay times of emission peaks for the ablated species were investigated as a function of the observation distance from the target surface, and the velocities of these species were derived accordingly. Two emission peaks corresponding to a fast and a slow component of ablated Ti(I) were observed by optical time-of-flight spectroscopy. The origins of the two peaks and a possible mechanism for the laser ablation are discussed.

Growth and characterization of Cadmium Thiosemicarbazide Bromide crystals for antibacterial and nonlinear optical applications

NASA Astrophysics Data System (ADS)

Thomas Joseph Prakash, J.; Martin Sam Gnanaraj, J.

2015-01-01

Semiorganic nonlinear optical crystals of Cadmium Thiosemicarbazide Bromide was grown by slow evaporation solution growth technique. The unit cell parameters were estimated by subjecting the crystals to single crystal X-ray diffraction. The grown crystals were subjected to Powder X-ray diffraction for analyzing the crystalline nature of the sample. FTIR studies reveal the functional groups and the optical characters were analyzed by UV-Vis spectral studies. Mechanical stability of the sample was assessed by Vicker's micro hardness test. The presence of surface dislocations was identified by chemical etching technique. Antibacterial study was carried out against ACDP declared harmful pathogens. SHG efficiency of CTSB crystal was tested using Nd: YAG laser and it was found to be ∼1.8 times that of potassium dihydrogen phosphate.

Growth, structural, optical and thermal properties of gamma-glycine crystal.

PubMed

Balakrishnan, T; Babu, R Ramesh; Ramamurthi, K

2008-04-01

Single crystals of gamma-glycine were grown from a mixture of glycine, water and lithium bromide. Single crystal X-ray diffraction analysis confirmed the growth of gamma-glycine phase. Presence of various functional groups of gamma-glycine was identified by FTIR spectrum. Optical absorbance spectrum recorded in the wavelength range of UV-vis-NIR revealed that this crystal has good optical transparency in the range 250-1500 nm. Vickers microhardness values were estimated on the prominent (100) face. Thermogravimetric and differential scanning calorimetric analyses were carried out to study the thermal properties of gamma-glycine. Second harmonic generation efficiency of the crystal measured by Kurtz's powder method using Nd:YAG laser is about three times that of KDP.

Growth, structural, spectral, optical, and thermal studies on amino acid based new NLO single crystal: L-phenylalanine-4-nitrophenol.

PubMed

Prakash, M; Lydia Caroline, M; Geetha, D

2013-05-01

A new organic nonlinear optical single crystal, L-phenylalanine-4-nitrophenol (LPAPN) belonging to the amino acid group has been successfully grown by slow evaporation technique. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. FT-IR spectrum was recorded to identify the presence of functional group and molecular structure was confirmed by NMR spectrum. Thermal strength of the grown crystal has been studied using TG-DTA analyses. The grown crystals were found to be transparent in the entire visible region. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm. Copyright © 2013 Elsevier B.V. All rights reserved.

Low-threshold ablation of enamel and dentin using Nd:YAG laser assisted with chromophore with different pulse shapes

NASA Astrophysics Data System (ADS)

Bonora, Stefano; Benazzato, Paolo; Stefani, Alessandro; Villoresi, Paolo

2004-05-01

Neodimium laser treatment has several drawbacks when used in the hard tissue cutting, because of the low absorption of the dental tissues at its wavelength. This investigation proved that the Nd:YAG radiation is a powerful ablation tool if it is used with the dye assisted method. Several in vitro tests on enamel and dentin were accomplished changing some laser parameters to have different pulse shapes and durations from 125μs up to 1.4ms. The importance of short time high power peaks, typical of crystal lasers, in the ablation process was investigated. The pulse shapes were analyzed by their intensity in space and time profiles. A first set of results found the optimum dye concentration be used in all the following tests. Furthermore the ablation threshold for this technique was found for each different pulse shapes and durations. A low energy ablation method was found to avoid temperature increase and surface cracks formation. In vitro temperature analysis was reported comparing the differences between no dye application laser treatment and with a dye spray applied. A strong reduction of the temperature increase was found in the dye assisted method. A discussion on the general findings and their possible clinical applications is presented.

Transition of Emission Colours as a Consequence of Heat-Treatment of Carbon Coated Ce3+-Doped YAG Phosphors

PubMed Central

Yin, Liang-Jun; Dierre, Benjamin; Sekiguchi, Takashi; van Ommen, J. Ruud; Hintzen, Hubertus T. (Bert); Cho, Yujin

2017-01-01

To modify the luminescence properties of Ce3+-doped Y3Al5O12 (YAG) phosphors, they have been coated with a carbon layer by chemical vapor deposition and subsequently heat-treated at high temperature under N2 atmosphere. Luminescence of the carbon coated YAG:Ce3+ phosphors has been investigated as a function of heat-treatment at 1500 and 1650 °C. The 540 nm emission intensity of C@YAG:Ce3+ is the highest when heated at 1650 °C, while a blue emission at 400–420 nm is observed when heated at 1500 °C but not at 1650 °C. It is verified by X-ray diffraction (XRD) that the intriguing luminescence changes are induced by the formation of new phases in C@YAG:Ce3+-1500 °C, which disappear in C@YAG:Ce3+-1650 °C. In order to understand the mechanisms responsible for the enhancement of YAG:Ce3+ emission and the presence of the blue emission observed for C@YAG:Ce3+-1500 °C, the samples have been investigated by a combination of several electron microscopy techniques, such as HRTEM, SEM-CL, and SEM-EDS. This local and cross-sectional analysis clearly reveals a gradual transformation of phase and morphology in heated C@YAG:Ce3+ phosphors, which is related to a reaction between C and YAG:Ce3+ in N2 atmosphere. Through reaction between the carbon layer and YAG host materials, the emission colour of the phosphors can be modified from yellow, white, and then back to yellow under UV excitation as a function of heat-treatment in N2 atmosphere. PMID:29035336

Transition of Emission Colours as a Consequence of Heat-Treatment of Carbon Coated Ce3+-Doped YAG Phosphors.

PubMed

Yin, Liang-Jun; Dierre, Benjamin; Sekiguchi, Takashi; van Ommen, J Ruud; Hintzen, Hubertus T Bert; Cho, Yujin

2017-10-16

To modify the luminescence properties of Ce 3+ -doped Y₃Al₅O 12 (YAG) phosphors, they have been coated with a carbon layer by chemical vapor deposition and subsequently heat-treated at high temperature under N₂ atmosphere. Luminescence of the carbon coated YAG:Ce 3+ phosphors has been investigated as a function of heat-treatment at 1500 and 1650 °C. The 540 nm emission intensity of C@YAG:Ce 3+ is the highest when heated at 1650 °C, while a blue emission at 400-420 nm is observed when heated at 1500 °C but not at 1650 °C. It is verified by X-ray diffraction (XRD) that the intriguing luminescence changes are induced by the formation of new phases in C@YAG:Ce 3+ -1500 °C, which disappear in C@YAG:Ce 3+ -1650 °C. In order to understand the mechanisms responsible for the enhancement of YAG:Ce 3+ emission and the presence of the blue emission observed for C@YAG:Ce 3+ -1500 °C, the samples have been investigated by a combination of several electron microscopy techniques, such as HRTEM, SEM-CL, and SEM-EDS. This local and cross-sectional analysis clearly reveals a gradual transformation of phase and morphology in heated C@YAG:Ce 3+ phosphors, which is related to a reaction between C and YAG:Ce 3+ in N₂ atmosphere. Through reaction between the carbon layer and YAG host materials, the emission colour of the phosphors can be modified from yellow, white, and then back to yellow under UV excitation as a function of heat-treatment in N₂ atmosphere.

A comparison of the effects of Nd:YAG and Ho:YAG laser irradiation on dentine and enamel.

PubMed

Cernavin, I

1995-04-01

This preliminary study was undertaken to investigate the effects of Nd:YAG and Ho:YAG lasers on enamel and dentine of extracted teeth. The Ho:YAG laser (spot size 250 microns, energy density 4160 J/cm2) produced a cleaner puncture in dentine with less melting of the surrounding tissue than did the Nd:YAG laser (spot size 20 microns), energy density 50,000 J/cm2), which produced considerable melting and recrystallization of dentine and was more difficult to control. It was possible to cut enamel and dentine with both lasers, but considerable melted and recrystallized enamel was produced. From the limited observations of this study it appears that the Ho:YAG laser is more suitable for cutting both enamel and dentine than the Nd:YAG laser. More work needs to be done to ascertain the effect on enamel and dentine of modification of the parameters of both lasers.

Spectroscopic and quantum chemical perspectives on 2-amino 5-methylpyridinium 4-nitrobenzoate - An organic single crystals for optoelectronics device applications

NASA Astrophysics Data System (ADS)

Gandhimathi, A.; Karunakaran, R. T.; Kumaran, A. Elakkina; Prabahar, S.

2018-07-01

In this work, an optical quality single crystals of 2-amino 5-methylpyridinium 4-nitrobenzoate (2A5MPNB) were grown by slow evaporation solution growth technique using methanol as a solvent. The phases and functional groups of 2A5MPNB have been confirmed through powder X-ray diffraction and Fourier transform infrared (FTIR) studies, respectively. The optical transmittance window and the lower cut-off wavelength of the 2A5MPNB have been identified by UV-Vis-NIR studies. Dielectric and photoconductivity studies were also performed for the grown crystals. In order to analyze the mechanical strength Vickers hardness studies were taken for the grown crystal. The thermal behaviour was investigated by TG/DTA studies. NLO and laser damage properties were explored using Nd:YAG laser. Moreover, the quantum chemical calculations on 2A5MPNB have been performed by density functional theory (DFT) calculations using the B3LYP method with 6-311++G(d,p) basis set. The predicted first hyperpolarizability is found to be 14.45 times greater than that of urea and suggests that the title compound could be an attractive material for nonlinear optical applications.

Influence of tartaric acid on linear-nonlinear optical and electrical properties of KH2PO4 crystal

NASA Astrophysics Data System (ADS)

Baig, M. I.; Anis, Mohd; Muley, G. G.

2017-10-01

KH2PO4 (KDOP) is widely demanded technological crystal for applications in laser driven photonic devices. Therefore, present article is focused to investigate the effect of tartaric acid (TA) on laser induced nonlinear optical properties of KDOP crystal. The optically transparent TA doped KDOP crystal of size 15 × 10 × 04 mm3 has been grown by slow solvent evaporation technique at 35 °C. The structural analysis of pure and TA doped KDOP crystal has been achieved by means of single crystal X-ray diffraction technique. The functional groups of TA doped KDOP crystal has been identified by means of Fourier transform infrared spectral analysis. The UV-visible studies have been performed to determine the optical transparency and evaluate the linear optical constants of pure and TA doped KDOP crystal. The Kurtz-Perry test has been employed to confirm the frequency doubling phenomenon of crystal and the SHG efficiency of TA doped KDOP crystal is found to be 5.68 times higher than that of standard KDP material. The Z-scan technique has been employed to explore the third order nonlinear optical (TONLO) refraction (n2), absorption (β) and susceptibility (χ3) of pure and TA doped KDOP crystal at 632.8 nm. The TA facilitated optical switching in TONLO response of KDOP crystal is found to be an interesting effect to examine. The laser damage threshold of TA doped KDOP crystal has been determined at 1064 nm using the Nd:YAG laser. The comparative electrical analysis on pure and TA doped KDOP crystal has been accomplished by means of dielectric and photoconductivity characterization studies.

Radially polarized and passively Q-switched fiber laser

PubMed Central

Lin, Di; Xia, Kegui; Li, Ruxin; Li, Xiaojun; Li, Guoqiang; Ueda, Ken-ichi; Li, Jianlang

2017-01-01

We report, for the first time to our knowledge, a radially polarized and passively Q-switched Yb-doped fiber laser. By using a Cr4+:YAG crystal as a saturable absorber and a photonic crystal grating as a polarization mirror, a radially polarized pulse is produced, which has 202 W of peak power, 75 ns duration, and ~92% polarization purity at a 56.6 kHz repetition rate. The Q-switched pulse with radial polarization from the fiber laser would facilitate numerous applications. PMID:21042354

Efficient Cryogenic Near-Infrared Tm: YLF Laser

DTIC Science & Technology

2016-12-22

pumped at 781.5 nm and operated at 816 nm. Although Tm:YLF has lower nonradiative decay rate than Tm:YAG, residual population trapping still affects...mitigated by cryogenic cooling, use of a YLF crystal host to reduce nonradiative decay rates and the use of a dual-wavelength resonator to

Calculation of photonic bandgap for 2D hexagonal and square structure base on hybrid polymer material

NASA Astrophysics Data System (ADS)

Hidayat, S.; Riveli, N.

2018-05-01

We have calculated 2D photonic crystal band gap using plane-wave expansion method. The studied model of structures is hexagonal lattice and square lattice of rod cylinder in air. We have simulated the dispersion relation of it structure using hybrid polymer as rod material. The parameter structures are nrod = 1.5, nhole = 1, and rrod = 0.25a, where a is lattice constant. We found the distributed feedback occurs at the edge of upper band or frequency at 0.66 (a/λ). In our experimental work, we have successfully fabricated the 2D photonic crystal from hybrid polymer incorporated with organic dye laser. The lasing characteristics ware investigated using strip-line excitation light of SHG Nd-YAG laser (λ=532 nm). The lasing wavelengths for hexagonal structure are observed at 606 nm and 621 nm for photonic crystal period of 400 nm and 410 nm, respectively. λ=532 nm). Whereas the square structure, the lasing wavelengths are observed at (588 nm ± 2) and (606 nm ± 2 nm) for grating period of 391 nm and 405 nm.

Crystal growth, spectral, structural and optical studies of π-conjugated stilbazolium crystal: 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate.

PubMed

Krishna Kumar, M; Sudhahar, S; Bhagavannarayana, G; Mohan Kumar, R

2014-05-05

Nonlinear optical (NLO) organic compound, 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate was synthesized by reflux method. The formation of molecular complex was confirmed from (1)H NMR, FT-IR and FT-Raman spectral analyses. The single crystals were grown by slow evaporation solution growth method and the crystal structure and atomic packing of grown crystal was identified. The morphology and growth axis of grown crystal were determined. The crystal perfection was analyzed using high resolution X-ray diffraction study on (001) plane. Thermal stability, decomposition stages and melting point of the grown crystal were analyzed. The optical absorption coefficient (α) and energy band gap (E(g)) of the crystal were determined using UV-visible absorption studies. Second harmonic generation efficiency of the grown crystal was examined by Kurtz powder method with different particle size using 1064 nm laser. Laser induced damage threshold study was carried out for the grown crystal using Nd:YAG laser. Copyright © 2014 Elsevier B.V. All rights reserved.

Spectroscopic study of gel grown L-Valine Zinc Glycine Thiourea Sulfate (VZGTS) crystal: A novel NLO crystal

NASA Astrophysics Data System (ADS)

Rathod, Kiran T.; Patel, I. B.

2017-05-01

In recent years, organometalic non linear optical (NLO) materials have attained immense appeal form researchers due to its range of technological applications in photonic field and optoelectronic technology. In present research work, novel semi organic NLO L-Valine Zinc Glycine Thiourea Sulfate crystals (VZGTS) with different morphologies were grown by gel method at ambient temperature. Presence and identification of functional groups were confirmed by FITR analysis. Spectroscopic studies were carried out for it. The UV-Vis spectroscopy is recorded for crystal. PL study stats that the crystal has insulating nature. Spectroscopic study shows that this crystal has good transparency in the case of fundamental wavelength of Nd : YAG laser. Second Harmonic Generation (SHG) efficiency was confirmed by Kurtz - Perry powder method. Results are discussed in the paper.

Holmium:YAG surgical lasers.

PubMed

1995-03-01

"Holmium:YAG (Ho:YAG)" is the shorthand name for a family of solid-state lasers that use the doping element holmium in a laser crystal (e.g., YAG [yttrium-aluminum-garnet]) and that emit energy at approximately 2.1 microns. This wavelength is relatively new to medicine and has been used in laser surgery for only about the last six years. Like the carbon dioxide (CO2) laser when it was first used clinically, the Ho:YAG laser is poised for rapid and wide-spread use. Ho:YAG lasers, like CO2 lasers, offer precise cutting with minimal damage to adjacent tissue; however, unlike CO2 lasers, they also offer fiberoptic delivery (which is ideal for endoscopic use) and the ability to treat tissue in a liquid-filled environment (e.g., saline, blood). The initial specialty for which the Ho:YAG laser was used was arthroscopic surgery, especially diskectomy. Today, it is effectively used in many surgical specialties, including general surgery, urology, laparoscopy, neurosurgery, lithotripsy, angioplasty, orthopedic surgery (which includes procedures such as meniscectomy, bone sculpting [may also be performed in plastic surgery], and some experimental surgery, such as cartilage shrinking to tighten loose joints), and dentistry. Because of its broad range of potential applications, it has been called the "Swiss Army Knife" of lasers. High-powered Ho:YAG lasers, which enable surgeons to work more quickly and cut more smoothly, have been made available only within the last three years (units offering > 20 W) to 18 months (units offering > 60 W). Because of this rapid increase, high-powered units are still relatively expensive, and it is not yet clear whether maximum power outputs will continue to increase or whether the cost of higher-power units will begin to come down. Although low-power and high-power Ho:YAG lasers can be used for the same procedures, their different ranges of possible clinical techniques make them better suited to different applications: low-power units are preferable for small-joint and some head-and-neck surgeries or for office use, and high-power units are more suitable for use in major surgery, such as gastrointestinal surgery or surgery in large joints. This evaluation includes two units at both ends of the Ho:YAG power spectrum--one 10 W and one 60 W--and thus provides a guide to evaluating other Ho:YAG lasers that are currently available or that will be entering the market.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of Er:YAG laser irradiation on human dentin: polarizing microscopic, light microscopic and microradiographic observations, and FT-IR analysis.

PubMed

Ishizaka, Yaeko; Eguro, Toru; Maeda, Toru; Tanaka, Hisayoshi

2002-01-01

The effects of Er:YAG laser irradiation on dentin have not been sufficiently investigated. The purpose of this study was to investigate the effects of Er:YAG laser irradiation on dentin. After cavities were prepared using Er:YAG laser irradiation or rotary cutting instruments, histological observations of cavity-floor dentin utilizing polarizing microscopy, microradiography and light microscopy, and analysis of composition of cavity-floor dentin using Fourier-transformed (FT-IR) spectrometry were conducted. In the laser-treated side, a deeply stained basophilic layer was observed. The number of odontoblastic processes present was obviously less in the laser-treated side than in the bur-treated side. FT-IR analysis revealed that compared to the bur-treated side, a broad background peak at around 1,600 cm(-1) was present. Er:YAG laser irradiation might have denatured the organic materials of dentin. Copyright 2002 Wiley-Liss, Inc.

Nd:YAG-laser-Q-switching with a photo-elastic modulator and applications

NASA Astrophysics Data System (ADS)

Bammer, F.; Petkovšek, R.; Dominguez, H.; Liedl, G.

2010-05-01

We present a rod-Nd:YAG-Laser, side-pumped with eight 50W-laser diode bars at 808nm, and Q-switched with a Single Crystal Photo-Elastic Modulator at 95.1 kHz. The latter is made of a z-cut LiNbO3-crystal, which is electrically y-excited on the mechanical resonance frequency of the x-longitudinal oscillation. With a voltage amplitude of 3 V the crystal shows a strong oscillation such that due to the photo-elastic effect a high polarization modulation is achieved, which, together with a polarizer, can be used as a simple optical switch. With this inside the laser resonator the average power is 47.8W in cw-mode and 45.5W in pulsed mode, with pulse peak powers of 4 kW and pulse widths of 100ns. This kind of operation is similar to cw-operation but offers due to the high peak powers different interaction physics with matter. The source is therefore suited for micro-welding of metals, LIDAR, rapid prototyping of plastics, marking/engraving/cutting of plastics, marking of glasses. In cases where high precision and a small heat affected zone are necessary this simple kind of pulsed operation may be advantageous, when compared to cw-operation.

Rigrod laser-pumped-laser resonator model: II. Application to thin and optically-dilute laser media

NASA Astrophysics Data System (ADS)

Brown, D. C.

2014-08-01

In part I of this paper, and to set the foundation for this part II, we derived the resonator equations describing the normalized intensities, output power, gain, and extraction efficiency for a standard resonator incorporating two dielectric mirrors and a gain element. We then generalized the results to include an absorbing region representing a second laser crystal characterized by a small-signal transmission T0. Explicit expressions were found for the output power extracted into absorption by the second laser crystal and the extraction efficiency, and the limits to each were discussed. It was shown that efficient absorption by a thin or dilute second laser crystal can be realized in resonators in which the mirror reflectivities were high and in which the single-pass absorption was low, due to the finite photon lifetime and multi-passing of the absorbing laser element. In this paper, we apply the model derived in part I to thin or dilute laser materials, concentrating on a Yb, Er:glass intracavity pumped by a 946 nm Nd:YAG laser, a Yb, Er:glass laser-pumped intracavity by a 977 nm diode laser, and an Er:YAG laser-pumped intracavity to a 1530 nm diode laser. It is shown that efficient absorption can be obtained in all cases examined.

Red and orange laser operation of Pr:KYF4 pumped by a Nd:YAG/LBO laser at 469.1 nm and a InGaN laser diode at 444 nm.

PubMed

Xu, B; Starecki, F; Pabœuf, D; Camy, P; Doualan, J L; Cai, Z P; Braud, A; Moncorgé, R; Goldner, Ph; Bretenaker, F

2013-03-11

We report the basic luminescence properties and the continuous-wave (CW) laser operation of a Pr(3+)-doped KYF(4) single crystal in the Red and Orange spectral regions by using a new pumping scheme. The pump source is an especially developed, compact, slightly tunable and intra-cavity frequency-doubled diode-pumped Nd:YAG laser delivering a CW output power up to about 1.4 W around 469.1 nm. At this pump wavelength, red and orange laser emissions are obtained at about 642.3 and 605.5 nm, with maximum output powers of 11.3 and 1 mW and associated slope efficiencies of 9.3% and 3.4%, with respect to absorbed pump powers, respectively. For comparison, the Pr:KYF(4) crystal is also pumped by a InGaN blue laser diode operating around 444 nm. In this case, the same red and orange lasers are obtained, but with maximum output powers of 7.8 and 2 mW and the associated slope efficiencies of 7 and 5.8%, respectively. Wavelength tuning for the two lasers is demonstrated by slightly tilting the crystal. Orange laser operation and laser wavelength tuning are reported for the first time.

Use of the holmium:YAG laser in urology.

PubMed

Johnson, D E; Cromeens, D M; Price, R E

1992-01-01

The tissue effects of a holmium:YAG (Ho:YAG) laser operating at a wavelength of 2.1 mu with a maximum power of 15 watts (W) and 10 different energy-pulse settings was systematically evaluated on kidney, bladder, prostate, ureteral, and vasal tissue in the dog. In addition, various urologic surgical procedures (partial nephrectomy, transurethral laser incision of the prostate, and laser-assisted vasovasostomy) were performed in the dog, and a laparoscopic pelvic lymph node dissection was carried out in a pig. Although the Ho:YAG laser has a strong affinity for water, precise tissue ablation was achieved in both the contact and non-contact mode when used endoscopically in a fluid medium to ablate prostatic and vesical tissue. Using the usual parameters for tissue destruction (blanching without charring), the depth of thermal injury in the bladder and ureter was kept superficial. In performing partial nephrectomies, a 2-fold reduction in the zone of coagulative necrosis was demonstrated compared to the use of the continuous wave Neodymium:YAG laser (Nd:YAG). When used through the laparoscope, the Ho:YAG laser provided precise cutting and, combined with electrocautery, allowed the dissection to proceed quickly and smoothly. Hemostatic control was adequate in all surgical procedures. Although the results of these investigations are preliminary, our initial experience with the Ho:YAG laser has been favorable and warrants further investigations.

Growth and characterization of unidirectional benzil single crystal for photonic applications

NASA Astrophysics Data System (ADS)

Saranraj, A.; Thirupathy, J.; Dhas, S. Sahaya Jude; Jose, M.; Vinitha, G.; Dhas, S. A. Martin Britto

2018-06-01

Organic nonlinear optical benzil single crystal of fine quality with the dimensions of 168 × 14 mm2 was successfully grown in (100) plane from saturated solution by unidirectional SR method. The structural identity of the grown crystal was confirmed by powder XRD. High-resolution X-ray diffraction analysis indicates the crystalline perfection of the grown benzil crystal. The optical analysis was carried out by UV-visible spectroscopy which shows that the benzil crystal's cut off wavelength is 437 nm. The dielectric constant and dielectric loss of benzil crystal are found to be very much depending upon temperature and frequency. Ferroelectric nature of grown crystal was identified by P- E hysteresis analysis and to find the values of spontaneous polarization and coercive field. The laser damage threshold energy was studied with the help of Nd:YAG laser. The presence of third harmonic generation was identified by z-scan techniques.

A protected annealing strategy to enhanced light emission and photostability of YAG:Ce nanoparticle-based films.

PubMed

Revaux, Amelie; Dantelle, Geraldine; George, Nathan; Seshadri, Ram; Gacoin, Thierry; Boilot, Jean-Pierre

2011-05-01

A significant obstacle in the development of YAG:Ce nanoparticles as light converters in white LEDs and as biological labels is associated with the difficulty of finding preparative conditions that allow simultaneous control of structure, particle size and size distribution, while maintaining the optical properties of bulk samples. Preparation conditions frequently involve high-temperature treatments of precursors (up to 1400 °C), which result in increased particle size and aggregation, and lead to oxidation of Ce(iii) to Ce(iv). We report here a process that we term protected annealing, that allows the thermal treatment of preformed precursor particles at temperatures up to 1000 °C while preserving their small size and state of dispersion. In a first step, pristine nanoparticles are prepared by a glycothermal reaction, leading to a mixture of YAG and boehmite crystalline phases. The preformed nanoparticles are then dispersed in a porous silica. Annealing of the composite material at 1000 °C is followed by dissolution of the amorphous silica by hydrofluoric acid to recover the annealed particles as a colloidal dispersion. This simple process allows completion of YAG crystallization while preserving their small size. The redox state of Ce ions can be controlled through the annealing atmosphere. The obtained particles of YAG:Ce (60 ± 10 nm in size) can be dispersed as nearly transparent aqueous suspensions, with a luminescence quantum yield of 60%. Transparent YAG:Ce nanoparticle-based films of micron thickness can be deposited on glass substrates using aerosol spraying. Films formed from particles prepared by the protected annealing strategy display significantly improved photostability over particles that have not been subject to such annealing. © The Royal Society of Chemistry 2011

Effect of Li and NH4 doping on the crystal perfection, second harmonic generation efficiency and laser damage threshold of potassium pentaborate crystals

NASA Astrophysics Data System (ADS)

Vigneshwaran, A. N.; Kalainathan, S.; Raja, C. Ramachandra

2018-03-01

Potassium pentaborate (KB5) is an excellent nonlinear optical material especially in the UV region. In this work, Li and NH4 doped KB5 crystals were grown using slow evaporation solution growth method. The incorporation of dopant has been confirmed and analysed by Energy dispersive X-ray analysis (EDAX), Inductively coupled plasma (ICP) analysis and Raman spectroscopy. The crystalline perfection of pure and doped KB5 crystals was studied by High resolution X-ray diffraction (HRXRD) analysis. Structural grain boundaries were observed in doped crystals. Second harmonic generation was confirmed for pure and doped crystals and output values revealed the enhancement of SHG efficiency in doped crystals. Resistance against laser damage was carried out using 1064 nm Nd-YAG laser of pulse width 10 ns. The laser damage threshold value is increased in Li doped crystal and decreased in NH4 doped crystal when compared to pure KB5 crystal.

Synthesis, crystal growth, structural, thermal and optical properties of naphthalene picrate an organic NLO material.

PubMed

Chandramohan, A; Bharathikannan, R; Kandavelu, V; Chandrasekaran, J; Kandhaswamy, M A

2008-12-01

Crystalline substance of naphthalene picrate (NP) was synthesized and single crystals were grown using slow evaporation solution growth technique. The solubility of the naphthalene picrate complex was estimated using different solvents such as chloroform and benzene. The material was characterized by elemental analysis, powder X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and fourier transform-infrared (FT-IR) techniques. The electronic absorption was studied through UV-vis spectrophotometer. Thermal behavior and stability of the crystal were studied using thermogravimetric (TG) and differential thermal analysis (DTA) techniques. The second harmonic generation (SHG) of the material was confirmed using Nd:YAG laser.

Crystal growth and characterization of semi-organic 2-amino-5-nitropyridinium bromide (2A5NPBr) single crystals for third-order nonlinear optical (NLO) applications

NASA Astrophysics Data System (ADS)

Vediyappan, Sivasubramani; Arumugam, Raja; Pichan, Karuppasamy; Kasthuri, Ramachandran; Muthu, Senthil Pandian; Perumal, Ramasamy

2017-12-01

Semi-organic nonlinear optical (NLO) 2-amino-5-nitropyridinium bromide (2A5NPBr) single crystals have been grown by slow evaporation solution technique (SEST) with the growth period of 60 days. The single-crystal XRD analysis confirms the unit cell parameters of the grown crystal. The crystallinity of grown 2A5NPBr was analyzed by powder X-ray diffraction (PXRD) measurement. The presence of functional groups of 2A5NPBr crystal was confirmed by Fourier transform infrared (FTIR) spectrum analysis. The optical transmittance of the grown crystal was analyzed by UV-Vis-NIR analysis. It shows good transparency in the visible and NIR region and it is favorable for nonlinear optical (NLO) device applications. The chemical etching study was carried out and it reveals that the grown crystal has less dislocation density. The photoconductivity study reveals that the grown crystal possesses positive photoconductive nature. The thermal stability of the crystal has been investigated by thermogravimetric (TG) and differential thermal analysis (DTA). The dielectric constant and dielectric loss as a function of frequency were measured. The electronic polarizability (α) of 2A5NPBr molecule has been calculated theoretically by different ways such as Penn analysis, Clausius-Mossotti relation, Lorentz-Lorenz equation, optical bandgap, and coupled dipole method (CDM). The obtained values of electronic polarizability (α) are in good agreement with each other. Laser damage threshold (LDT) of 2A5NPBr crystal has been measured using Nd:YAG laser with the wavelength of 1064 nm. Third-order nonlinear optical property of the grown crystal was studied by Z-scan technique using He-Ne laser of wavelength 632.8 nm.

Improvement of thermal management in the composite Yb:YAG/YAG thin-disk laser

NASA Astrophysics Data System (ADS)

Kuznetsov, I. I.; Mukhin, I. B.; Palashov, O. V.

2016-04-01

To improve the thermal management in the composite Yb:YAG/YAG thin-disk laser a new design of laser head is developed. Thermal-induced phase distortions, small signal gain and lasing in the upgraded laser head are investigated and compared with previously published results. A substantial decrease of the thermal lens optical power and phase aberrations and increase of the laser slope efficiency are observed. A continuous-wave laser with 440 W average power and 44% slope efficiency is constructed.

Studies on synthesis, growth, structural, thermal, linear and nonlinear optical properties of organic picolinium maleate single crystals.

PubMed

Pandi, P; Peramaiyan, G; Sudhahar, S; Chakkaravarthi, G; Mohan Kumar, R; Bhagavannarayana, G; Jayavel, R

2012-12-01

Picolinium maleate (PM), an organic material has been synthesised and single crystals were grown by slow evaporation technique. The structure of the grown crystal was elucidated by using single crystal X-ray diffraction analysis. PM crystal belongs to the monoclinic crystallographic system with space group P2(1)/c. The crystalline perfection of the grown crystals was analyzed by high-resolution X-ray diffraction rocking curve measurements. The presence of functional groups in PM was identified by FTIR and FT-NMR spectral analyses. Thermal behaviour and stability of picolinium maleate were studied by TGA/DTA analyses. UV-Vis spectral studies reveal that PM crystals are transparent in the wavelength region 327-1100 nm. The laser damage threshold value of PM crystal was found to be 4.3 GW/cm(2) using Nd:YAG laser. The Kurtz and Perry powder second harmonic generation technique confirms the nonlinear optical property of the grown crystal. Copyright © 2012 Elsevier B.V. All rights reserved.

Investigation of 100 mJ all solid state end-pumped 1064 nm Q-switched laser

NASA Astrophysics Data System (ADS)

Xie, Shiyong; Wang, Caili; Liu, Hui; Bo, Yong; Xu, Zuyan

2017-11-01

High energy 1064 nm Q-switched laser output is obtained by LD vertical array end pumping Nd:YAG. Cylindrical lens are used for beam shaping of LD array for different divergence angle of fast and slow axis. Based on the theoretical simulation of fundamental mode radius using ABCD transfer matrix, the resonant cavity is optimized and curvature radius of cavity mirrors is determined. The intracavity power density is calculated according to the output laser pulse energy and transmittance of output coupling mirror is optimized under the condition that optical device is not damaged. 1064 nm laser with a maximum output of 110 mJ is generated under LD pump energy of 600 mJ, corresponding to optical conversion efficiency of 18.3%. The laser pulse width is 11 ns and divergence angle is 1.2 mrad. For saturation phenomenon of Q-switched laser output, LD temperature is adjusted to make wavelength deviate from absorption peak of Nd:YAG crystal. The parasitic oscillation, which affects the enhancement of Q-switched laser energy, can be effectively suppressed by reducing gain of pump end of laser medium, which provides an effective technical means for obtaining high energy end-pumped Q-switched laser.

Crystalline and magnetooptical characteristics of (Tb,Bi)3(Fe,Ga)5O12 deposited on (Y,Nd)3Al5O12

NASA Astrophysics Data System (ADS)

Morimoto, Ryohei; Goto, Taichi; Nakamura, Yuichi; Boey Lim, Pang; Uchida, Hironaga; Inoue, Mitsuteru

2018-06-01

We prepared Bi- and Ga-substituted Tb3Fe5O12 (BiGa:TIG) films on a Nd-substituted Y3Al5O12 (Nd:YAG) single crystal substrate by pulsed laser deposition, and investigated their magnetic, optical, and magnetooptical properties. A BiGa:TIG film deposited with a substrate temperature of 700 °C shows the easy axis of magnetization along the out-of-plane direction of the film and the Faraday rotation angle of 900°/cm at a wavelength of 1064 nm. The epitaxial growth of the film is confirmed by X-ray diffraction analysis.

High-efficency stable 213-nm generation for LASIK application

NASA Astrophysics Data System (ADS)

Wang, Zhenglin; Alameh, Kamal; Zheng, Rong

2005-01-01

213nm Solid-state laser technology provides an alternative method to replace toxic excimer laser in LASIK system. In this paper, we report a compact fifth harmonic generation system to generate high pulse energy 213nm laser from Q-switched Nd:YAG laser for LASIK application based on three stages harmonic generation procedures. A novel crystal housing was specifically designed to hold the three crystals with each crystal has independent, precise angular adjustment structure and automatic tuning control. The crystal temperature is well maintained at ~130°C to improve harmonic generation stability and crystal operation lifetime. An output pulse energy 35mJ is obtained at 213nm, corresponding to total conversion efficiency ~10% from 1064nm pump laser. In system verification tests, the 213nm output power drops less than 5% after 5 millions pulse shots and no significant damage appears in the crystals.

Crystal growth, thermal and optical studies of semiorganic nonlinear optical material: L-lysine hydrochloride dihydrate

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

Kalaiselvi, D.; Mohan Kumar, R.; Jayavel, R.

2008-07-01

Single crystals of L-lysine hydrochloride dihydrate (LLHCD), a nonlinear optical material, have been grown by slow cooling technique from its aqueous solution. LLHCD was found to be highly soluble in water. The grown crystals have been subjected to single crystal X-ray diffraction to confirm the structure and to estimate the lattice parameters. The vibrational structure of the molecule is elucidated from FTIR spectra. Thermal analysis revealed the thermal stability of the grown crystals. The optical transmittance spectrum shows that the material possesses good optical transparency in the entire visible region with a UV cut-off wavelength at 228 nm. The mechanicalmore » properties of the grown crystal have been studied using Vicker's microhardness test. The laser damage threshold of 52.25 MW/cm{sup 2} has been measured by irradiating Q-switched Nd:YAG laser (1064 nm)« less

Optical properties and Faraday effect of ceramic terbium gallium garnet for a room temperature Faraday rotator.

PubMed

Yoshida, Hidetsugu; Tsubakimoto, Koji; Fujimoto, Yasushi; Mikami, Katsuhiro; Fujita, Hisanori; Miyanaga, Noriaki; Nozawa, Hoshiteru; Yagi, Hideki; Yanagitani, Takagimi; Nagata, Yutaka; Kinoshita, Hiroo

2011-08-01

The optical properties, Faraday effect and Verdet constant of ceramic terbium gallium garnet (TGG) have been measured at 1064 nm, and were found to be similar to those of single crystal TGG at room temperature. Observed optical characteristics, laser induced bulk-damage threshold and optical scattering properties of ceramic TGG were compared with those of single crystal TGG. Ceramic TGG is a promising Faraday material for high-average-power YAG lasers, Yb fiber lasers and high-peak power glass lasers for inertial fusion energy drivers.

Is There Segregation of Rare Earth Ions in Garnet Optical Ceramics?

NASA Astrophysics Data System (ADS)

Boulon, Georges; Epicier, T.; Zhao, W.; Guzik, M.; Pan, Y.; Jiang, B.

Research on advanced optical materials for a large variety of applications is always increasing. As an example, we can note high progress in solid-state laser sources like laser-diode (LD) - pumped solid-state lasers (DPSSL) including developments of new materials and high-power laser diode led to high-power and tuneable solid-state lasers. A wide variety of materials has been studied to develop more efficient and high power microchip lasers [1]. In end-pumping schemes, in particular, materials with a short absorption length for the LD pump beam are strongly anticipated for highly efficient operations because of the excellent match between the mode and pump beam profiles. High Nd3+ concentrations were so considered such as NdP5O14, LiNdP4O12 (LNP), and NdAl3(BO3)O4. However, crystal growths of these compositions are not so easy. Cubic crystals are much more researched. When looking at the literature for actual applications, we see immediately the importance of cubic garnet crystals for which dodecahedral (Y3+), octahedral (Al3+) and tetrahedral (Al3+) sites are considered as a reservoir for many activators like: Ce3+, Nd3+, Er3+, Tm3+, Ho3+, Yb3+ rare earth ions in dodecahedral symmetry sites and transition metal ions like Cr3+ in the octahedral symmetry sites or Cr4+ in the tetrahedral symmetry sites. Among garnet crystals, Y3Al5O12 (YAG) host is the most used, commercially produced by the Czochralski method. However, in the case of the most used Nd3+: YAG laser crystal, the Nd3+ concentration that affects the performance in laser applications, is strongly limited to 0.2-1.4 Nd3+ at. % as a result of the segregation distribution coefficient [1].

Ceramic Laser Materials

PubMed Central

Sanghera, Jasbinder; Kim, Woohong; Villalobos, Guillermo; Shaw, Brandon; Baker, Colin; Frantz, Jesse; Sadowski, Bryan; Aggarwal, Ishwar

2012-01-01

Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements. PMID:28817044

Continuous-wave yellow-green laser at 0.56  μm based on frequency doubling of a diode-end-pumped ceramic Nd:YAG laser.

PubMed

Yao, Wenming; Gao, Jing; Zhang, Long; Li, Jiang; Tian, Yubing; Ma, Yufei; Wu, Xiaodong; Ma, Gangfei; Yang, Jianming; Pan, Yubai; Dai, Xianjin

2015-06-20

We present what is, to the best of our knowledge, the first report on yellow-green laser generation based on the frequency doubling of the 1.1 μm transitions in Nd:YAG ceramics. By employing an 885 nm diode laser as the end-pumping source and a lithium triborate crystal as the frequency doubler, the highest continuous wave output powers of 1.4, 0.5, and 1.1 W at 556, 558, and 561 nm are achieved, respectively. These result in optical-to-optical efficiencies of 6.9%, 2.5%, and 5.4% with respect to the absorbed pump power, respectively.

Structural, thermal, laser damage, photoconductivity, NLO and mechanical properties of modified vertical Bridgman method grown AgGa0.5In0.5Se2 single crystal

NASA Astrophysics Data System (ADS)

Vijayakumar, P.; Ramasamy, P.

2016-08-01

AgGa0.5In0.5Se2 single crystal was grown using modified vertical Bridgman method. The structural perfection of the AgGa0.5In0.5Se2 single crystal has been analyzed by high-resolution X-ray diffraction rocking curve measurements. The structural and compositional uniformities of AgGa0.5In0.5Se2 were studied using Raman scattering spectroscopy at room temperature. The FWHM of the Γ1 (W1) and Γ5L (Γ15) measured at different regions of the crystal confirms that the composition throughout its length is fairly uniform. Thermal properties of the as-grown crystal, including specific heat, thermal diffusivity and thermal conductivity have been investigated. The multiple shot surface laser damage threshold value was measured using Nd:YAG laser. Photoconductivity measurements with different temperatures have confirmed the positive photoconducting behavior. Second harmonic generation (SHG) on powder samples has been measured using the Kurtz and Perry technique and the results display that AgGa0.5In0.5Se2 is a phase-matchable NLO material. The hardness behavior has been measured using Vickers micro hardness measurement and the indentation size effect has been observed. The classical Meyer's law, propositional resistance model and modified propositional resistance model have been used to analyse the micro hardness behavior.

Thermal-Mechanical Stability of Single Crystal Oxide Refractive Concentrators for High-Temperature Solar Thermal Propulsion

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Jacobson, Nathan S.; Miller, Robert A.

1999-01-01

Single crystal oxides such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium aluminum garnet (Y3Al5O12, or YAG), magnesium oxide (MgO) and sapphire (Al2O3) are candidate refractive secondary concentrator materials for high temperature solar propulsion applications. However, thermo-mechanical reliability of these components in severe thermal environments during the space mission sun/shade transition is of great concern. Simulated mission tests are important for evaluating these candidate oxide materials under a variety of transient and steady-state heat flux conditions, and thus provide vital information for the component design. In this paper, a controlled heat flux thermal shock test approach is established for the single crystal oxide materials using a 3.0 kW continuous wave CO2 laser, with a wavelength 10.6 micron. Thermal fracture behavior and failure mechanisms of these oxide materials are investigated and critical temperature gradients are determined under various temperature and heating conditions. The test results show that single crystal sapphire is able to sustain the highest temperature gradient and heating-cooling rate, and thus exhibit the best thermal shock resistance, as compared to the yttria-stabilized zirconia, yttrium aluminum garnet and magnesium oxide.

Thermal-Mechanical Stability of Single Crystal Oxide Refractive Concentrators for High-Temperature Solar Thermal Propulsion

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Jacobson, Nathan S.; Miller, Robert A.

1999-01-01

Single crystal oxides such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium aluminum garnet (Y3Al5O12, or YAG), magnesium oxide (MgO) and sapphire (Al2O3) are candidate refractive secondary concentrator materials for high temperature solar propulsion applications. However, thermo-mechanical reliability of these components in severe thermal environments during the space mission sun/shade transition is of great concern. Simulated mission tests are important for evaluating these candidate oxide materials under a variety of transient and steady-state heat flux conditions, and thus provide vital information for the component design. In this paper, a controlled heat flux thermal shock test approach is established for the single crystal oxide materials using a 3.0 kW continuous wave CO2 laser, with a wavelength 10.6 micron. Thermal fracture behavior and failure mechanisms of these oxide materials are investigated and critical temperature gradients are determined under various temperature and heating conditions. The test results show that single crystal sapphire is able to sustain the highest temperature gradient and heating-cooling rate, and thus exhibit the best thermal shock resistance, as compared to the yttria-stabilized zirconia, yttrium aluminum garnet, and magnesium oxide.

A flux-free method for synthesis of Ce{sup 3+}-doped YAG phosphor for white LEDs

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

Qiang, Yaochun; Yu, Yuxi, E-mail: yu_heart@xmu.edu.cn; Chen, Guolong

2016-02-15

Highlights: • A series of CeF{sub 3}-doped YAG phosphors were successfully synthesized. • CeF{sub 3} not only can be used as the Ce{sup 3+} source but also can play the role of a flux. • The QY of YAG:CeF{sub 3} phosphor is 91% but the QY of YAG:Ce{sub 2}O{sub 3} phosphor is just 80%. • YAG:CeF{sub 3} phosphor exhibits excellent thermal stability. • Using CeF{sub 3} as the Ce{sup 3+} source is a promising flux-free method to prepare YAG:Ce{sup 3+}. - Abstract: A series of CeF{sub 3}-doped Y{sub 3}Al{sub 5}O{sub 12} (YAG:CeF{sub 3}) phosphor, CeO{sub 2}-doped Y{sub 3}Al{sub 5}O{sub 12}more » (YAG:Ce{sub 2}O{sub 3}) phosphor and 5 wt% BaF{sub 2} added YAG:Ce{sub 2}O{sub 3} (YAG:Ce{sub 2}O{sub 3} + BaF{sub 2}) phosphor were successfully synthesized by a solid-state reaction method. The microstructure, morphology, luminescence spectra, luminescence quantum yield (QY) and thermal quenching of the phosphors were investigated. The QY of YAG:CeF{sub 3} phosphor is 91% but the QY of YAG:Ce{sub 2}O{sub 3} phosphor is just 80%. At 150 °C, the luminescence intensity of YAG:CeF{sub 3} phosphor, YAG:Ce{sub 2}O{sub 3} phosphor and YAG:Ce{sub 2}O{sub 3} + BaF{sub 2} phosphor was 85%, 86% and 89% of that measured at 25 °C, respectively. The comprehensive performance of the white LED lamp employing YAG:CeF{sub 3} phosphor is even better than that of the white LED lamp employing YAG:Ce{sub 2}O{sub 3} + BaF{sub 2} phosphor. The experimental results show that it is a promising flux-free method to synthesize Ce{sup 3+}-doped YAG phosphor by employing CeF{sub 3} as the Ce{sup 3+} source.« less

Nonlinear optical properties of flux growth KTiOPO4

NASA Astrophysics Data System (ADS)

Stolzenberger, Richard A.

1988-09-01

The properties of large flux grown KTiOPO4 second harmonic generators were measured. A technique which provides a sensitive assessment of crystal uniformity is described. Optically perfect second harmonic generation crystals of up to 1 cu cm were found to have nonlinear optical properties comparable with those grown by other methods. A Q-switched Nd:YAG laser was used to determine temperature acceptance width-length product (20 C cm), angular acceptance width-length product (13 mrad cm), and doubling efficiency (50 percent). Spectral bandwidth (4.5 A cm) and wavefront distortion (1/4 wave at 633 nm) were also measured. The dependence of these properties on crystal homogeneity is demonstrated.

Giant-pulse Nd:YVO4 microchip laser with MW-level peak power by emission cross-sectional control.

PubMed

Kausas, Arvydas; Taira, Takunori

2016-02-22

We present a giant-pulse generation laser realized by the emission cross-section control of a gain medium in a passively Q-switched Nd:YVO4 microchip laser with a Cr4+:YAG saturable absorber. Up to 1.17 MW peak power and 1.03 mJ pulse energy were obtained with a 100 Hz repetition rate. By combining the Nd:YVO4 crystal with a Sapphire plate, lower temperature difference between a pump region in the gain crystal and a crystal holder was obtained which helped to keep the cavity in stability zone at elevated temperatures and allowed the achievement of the high peak power for this laser system.

Effects of fabrication methods on spin relaxation and crystallite quality in Tm-doped ? powders studied using spectral hole burning

NASA Astrophysics Data System (ADS)

Lutz, Thomas; Veissier, Lucile; Thiel, Charles W.; Woodburn, Philip J. T.; Cone, Rufus L.; Barclay, Paul E.; Tittel, Wolfgang

2016-01-01

High-quality rare-earth-ion (REI) doped materials are a prerequisite for many applications such as quantum memories, ultra-high-resolution optical spectrum analyzers and information processing. Compared to bulk materials, REI doped powders offer low-cost fabrication and a greater range of accessible material systems. Here we show that crystal properties, such as nuclear spin lifetime, are strongly affected by mechanical treatment, and that spectral hole burning can serve as a sensitive method to characterize the quality of REI doped powders. We focus on the specific case of thulium doped ? (Tm:YAG). Different methods for obtaining the powders are compared and the influence of annealing on the spectroscopic quality of powders is investigated on a few examples. We conclude that annealing can reverse some detrimental effects of powder fabrication and, in certain cases, the properties of the bulk material can be reached. Our results may be applicable to other impurities and other crystals, including color centers in nano-structured diamond.

Spherical silicon-shell photonic band gap structures fabricated by laser-assisted chemical vapor deposition

NASA Astrophysics Data System (ADS)

Wang, H.; Yang, Z. Y.; Lu, Y. F.

2007-02-01

Laser-assisted chemical vapor deposition was applied in fabricating three-dimensional (3D) spherical-shell photonic band gap (PBG) structures by depositing silicon shells covering silica particles, which had been self-assembled into 3D colloidal crystals. The colloidal crystals of self-assembled silica particles were formed on silicon substrates using the isothermal heating evaporation approach. A continuous wave Nd:YAG laser (1064nm wavelength) was used to deposit silicon shells by thermally decomposing disilane gas. Periodic silicon-shell/silica-particle PBG structures were obtained. By removing the silica particles enclosed in the silicon shells using hydrofluoric acid, hollow spherical silicon-shell arrays were produced. This technique is capable of fabricating structures with complete photonic band gaps, which is predicted by simulations with the plane wave method. The techniques developed in this study have the potential to flexibly engineer the positions of the PBGs by varying both the silica particle size and the silicon-shell thickness. Ellipsometry was used to investigate the specific photonic band gaps for both structures.

Growth, structural, optical, thermal and laser damage threshold studies of an organic single crystal: 1,3,5 – triphenylbenzene (TPB)

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

Raja, R. Subramaniyan; Babu, G. Anandha; Ramasamy, P., E-mail: E-mail-ramasamyp@ssn.edu.in

2016-05-23

Good quality single crystals of pure hydrocarbon 1,3,5-Triphenylbenzene (TPB) have been successfully grown using toluene as a solvent using controlled slow cooling solution growth technique. TPB crystallizes in orthorhombic structure with the space group Pna2{sub 1}. The structural perfection of the grown crystal has been analysed by high resolution X-ray diffraction measurements. The range and percentage of the optical transmission are ascertained by recording the UV-vis spectrum. Thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study its thermal properties. Powder second harmonic generation studies were carried out to explore its NLO properties. Laser damage threshold valuemore » has been determined using Nd:YAG laser operating at 1064 nm.« less

Beam Switching of an Nd:YAG Laser Using Domain-Engineered Prisms in Magnesium-Oxide-Doped Congruent Lithium Niobate

DTIC Science & Technology

2010-08-01

In this work, a novel electro - optic beam switch (EOBS) is designed, fabricated and demonstrated. The EOBS presented in this work is designed for a...consists of a series of electronically controlled prisms fabricated by ferroelectric domain inversion in an electro - optic crystal wafer. The prisms are

Flow tube used to cool solar-pumped laser

NASA Technical Reports Server (NTRS)

1968-01-01

A flow tube has been designed and constructed to provide two major functions in the application of a laser beam for transmission of both sound and video. It maintains the YAG laser at the proper operating temperature of 300 degrees K under solar pumping conditions, and it serves as a pump cavity for the laser crystal.

Study of thin film production of ceramic ZrO2 on silicon wafer using second harmonic Nd-Yag laser with pulsed laser deposition technique

NASA Astrophysics Data System (ADS)

Suliyanti, Maria M.; Hidayah, Affi Nur; Kurniawan, K. H.

2012-06-01

Study about thin film production using technique pulsed laser deposition have been done. The Pulsed Laser Deposition (PLD) method has been used for growing thin film of ZrO2 on silicon wafer substrate (111 single crystal, thickness 400μm and diameter 7.5 cm). The target made from Zirconia oxide powder mixing with PVA and press using pressure 100kgN. The laser beam was focused by a lens (f = 100mm) through a quartz window onto the sample surface and the substrate was placed in parallel line with target. The distance between the target and the substrate is about 1 cm. The early results of this synthesis using 75 mJ Nd-YAG second harmonic laser pulse (532 nm Nd-YAG) and low pressure chamber surrounding gas 5 Torr. The irradiation of laser take around 6000 shoots or 10 minutes using frequencies laser 10 Hz. The micro thickness of film can be produced on silicon wafer using this technique. The results of ZrO2 thin film on substrate about 26.92%.

A novel dual‐wavelength, Nd:YAG, picosecond‐domain laser safely and effectively removes multicolor tattoos

PubMed Central

Schomacker, Kevin T.; Basilavecchio, Lisa D.; Plugis, Jessica M.; Bhawalkar, Jayant D.

2015-01-01

Background and Objectives Although nanosecond‐domain lasers have been the mainstay of laser tattoo removal for decades, recent disruptive innovations in laser design have introduced a new class of commercial Q‐switched lasers that generate picosecond‐domain pulses. Study A picosecond‐domain, Nd:YAG laser with a KTP frequency‐doubling crystal was used to treat 31 decorative tattoos in 21 subjects. Safety and effectiveness were determined by blinded evaluation of digital images in this prospective clinical study. Results The average clearance overall as evaluated by blinded observers evaluating randomized digital photographs was 79 ± 0.9% (mean ± sem) after an average of 6.5 treatments. Of the 31 tattoos completing treatment, 6 had evidence of mild hyper‐ or hypo‐pigmentation by evaluation of photographs. Conclusion The 350 picosecond, 532 nm, and 450 picosecond 1,064 nm Nd:YAG laser is safe and effective for removing decorative tattoos. Lasers Surg. Med. 47:542–548, 2015. © 2015 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc. PMID:26175187

Thermal, mechanical, optical and conductivity studies of a novel NLO active L-phenylalanine L-phenylalaninium dihydrogenphosphate single crystal

NASA Astrophysics Data System (ADS)

Sujatha, T.; Cyrac Peter, A.; Vimalan, M.; Merline Shyla, J.; Madhavan, J.

2010-08-01

An efficient, novel, semi-organic, nonlinear optical (NLO) material L-phenylalanine L-phenylalaninium dihydrogenphosphate (LPADHP), single crystal of dimension 11×5×2 mm 3, has been grown by the slow evaporation solution growth technique. Single crystal X-ray diffraction studies confirm that the grown crystal belongs to monoclinic system with the space group P2 1. The functional groups present in the crystal were confirmed by the Fourier transform infrared technique. Optical absorption spectrum shows that the material possesses very low absorption in the entire visible region. Thermal analysis confirmed that the crystal is thermally stable up to 161 °C. The frequency dependent dielectric properties of the grown crystal were studied for various temperatures. The second harmonic generation (SHG) efficiency of the grown crystal is 1.2 times greater than that of the potassium dihydrogenphosphate (KDP) single crystal. The laser induced surface damage threshold for the grown crystal was found to be 6.3 GW cm -2 with Nd:YAG laser assembly AC and DC conductivity and photoconductivity experiments are also carried out and the results are discussed.

Effects of pulsed mid-IR lasers on bovine knee joint tissues

NASA Astrophysics Data System (ADS)

Vari, Sandor G.; Shi, Wei-Qiang; Pergadia, Vani R.; Duffy, J. T.; Miller, J. M.; van der Veen, Maurits J.; Weiss, Andrew B.; Fishbein, Michael C.; Grundfest, Warren S.

1993-07-01

We investigated the effect of varying Tm:YAG (2.014 micrometers ) and Ho:YAG (2.130 micrometers ) laser parameters on ablation rate and consequent thermal damage. Mid-infrared wavelengths are strongly absorbed by most biological tissues due to the tissue's high water content. The ablation rate of fresh bovine knee joint tissues (fibrous cartilage, hyaline cartilage, and bone) in saline was assessed as a function of radiant exposure (160 - 950 J/cm2), at pulse widths of 200 microsecond(s) ec for Tm:YAG and 250 microsecond(s) ec for Ho:YAG and a repetition rate of 2 Hz. All tissues used in this study could be efficiently ablated using two micron lasers. The mechanism of action is likely related to the formation and collapse of cavitation bubbles, associated with mid-infrared lasers. We concluded that the Tm:YAG and Ho:YAG lasers are capable of effective knee joint tissue ablation.

2-μm Cr2+: CdSe passively Q-switched laser

NASA Astrophysics Data System (ADS)

Ji, E. C.; Liu, Q.; Yao, Y.; Lu, S.; Lue, Q. T.

2018-02-01

We demonstrate the bleaching characteristics of Cr2+: CdSe (Cr: CdSe) crystal around 2 μm and prove that Cr: CdSe crystal is an effective saturable absorber to obtain Q-switched pulsed output in Tm3+-doped fiber laser pumped Ho: YAG system. The saturable absorption property of Cr: CdSe is investigated with a pulsed source at 2090 nm. The laserinduced damage threshold of uncoated Cr: CdSe is estimated around 9.92 J/cm2 at 2090 nm with the pulse duration of 30 ns. With the measured bleaching curve, the estimated pulse saturation fluence is around 1.06 J/cm2, and the estimated ground-state absorption cross section is 8.97×10-20 cm2, which is very close to the experimental value. The preliminary laser experiments are all finished with an antireflection coated Cr: CdSe crystal to reduce the insertion loss. The maximum output pulse energy is about 1.8 mJ with repetition frequency of 685 Hz, pulse duration of 15.4 ns, and pulse peak power of 115 kW. The pulsed laser wavelength is measured to be 2090.2 nm.

Synthesis, crystal growth and studies on non-linear optical property of new chalcones

NASA Astrophysics Data System (ADS)

Sarojini, B. K.; Narayana, B.; Ashalatha, B. V.; Indira, J.; Lobo, K. G.

2006-09-01

The synthesis, crystal growth and non-linear optical (NLO) property of new chalcone derivatives are reported. 4-Propyloxy and 4-butoxy benzaldehydes were made to under go Claisen-Schmidt condensation with 4-methoxy, 4-nitro and 4-phenoxy acetophenones to form corresponding chalcones. The newly synthesized compounds were characterized by analytical and spectral data. The Second harmonic generation (SHG) efficiency of these compounds was measured by powder technique using Nd:YAG laser. Among tested compounds three chalcones showed NLO property. The chalcone 1-(4-methoxyphenyl)-3-(4-propyloxy phenyl)-2-propen-1-one exhibited SHG conversion efficiency 2.7 times that of urea. The bulk crystal of 1-(4-methoxyphenyl)-3-(4-butoxyphenyl)-2-propen-1-one (crystal size 65×28×15 mm 3) was grown by slow-evaporation technique from acetone. Microhardness of the crystal was tested by Vicker's microhardness method.

20 mJ, 1 ps Yb:YAG Thin-disk Regenerative Amplifier

PubMed Central

Alismail, Ayman; Wang, Haochuan; Brons, Jonathan; Fattahi, Hanieh

2017-01-01

This is a report on a 100 W, 20 mJ, 1 ps Yb:YAG thin-disk regenerative amplifier. A homemade Yb:YAG thin-disk, Kerr-lens mode-locked oscillator with turn-key performance and microjoule-level pulse energy is used to seed the regenerative chirped-pulse amplifier. The amplifier is placed in airtight housing. It operates at room temperature and exhibits stable operation at a 5 kHz repetition rate, with a pulse-to-pulse stability less than 1%. By employing a 1.5 mm-thick beta barium borate crystal, the frequency of the laser output is doubled to 515 nm, with an average power of 70 W, which corresponds to an optical-to-optical efficiency of 70%. This superior performance makes the system an attractive pump source for optical parametric chirped-pulse amplifiers in the near-infrared and mid-infrared spectral range. Combining the turn-key performance and the superior stability of the regenerative amplifier, the system facilitates the generation of a broadband, CEP-stable seed. Providing the seed and pump of the optical parametric chirped-pulse amplification (OPCPA) from one laser source eliminates the demand of active temporal synchronization between these pulses. This work presents a detailed guide to set up and operate a Yb:YAG thin-disk regenerative amplifier, based on chirped-pulse amplification (CPA), as a pump source for an optical parametric chirped-pulse amplifier. PMID:28745636

Multi-wavelength Yb:YAG/Nd³⁺:YVO₄ continuous-wave microchip Raman laser.

PubMed

Wang, Xiao-Lei; Dong, Jun; Wang, Xiao-Jie; Xu, Jie; Ueda, Ken-Ichi; Kaminskii, Alexander A

2016-08-01

Multi-wavelength continuous-wave (CW) Raman lasers in a laser diode pumped Yb:YAG/Nd³⁺:YVO₄ microchip Raman laser have been demonstrated for the first time to our best knowledge. The multi-wavelength laser of the first Stokes radiation around 1.08 μm has been achieved with a Raman shift of 261  cm^-1 for a-cut Nd:YVO₄ crystal corresponding to the fundamental wavelength at 1.05 μm. Multi-wavelength laser operation simultaneously around 1.05 and 1.08 μm has been achieved under the incident pump power between 1.5 and 1.7 W. Multi-wavelength Raman laser with frequency separation of 1 THz around 1.08 μm has been obtained when the incident pump power is higher than 1.7 W. The maximum Raman laser output power of 260 mW at 1.08 μm is obtained and the corresponding optical-to-optical conversion efficiency is 4.2%. Elliptically polarized fundamental laser and linearly polarized Raman laser were observed in an Yb:YAG/Nd:YVO₄ CW microchip Raman laser. The experimental results of linearly polarized, multi-wavelength Yb:YAG/Nd:YVO₄ CW microchip Raman laser with adjustable frequency separation provide a novel approach for developing potential compact laser sources for Terahertz generation.

Evaluation of the surface roughness of zirconia ceramics after different surface treatments.

PubMed

Kirmali, Omer; Akin, Hakan; Kapdan, Alper

2014-08-01

This study aimed to investigate the effects of different mechanical surface treatments of pre-sintered zirconium oxide (ZrO2) in an attempt to improve its bonding potential. One hundred and twenty IPS e-max ZirCAD (Ivoclar Vivadent) pre-sintered zirconia blocks (7 mm diameter, 3 mm height) received six different surface treatments (n = 20): Group C was untreated (control); Group E was Er:YAG laser irradiated; Group N was Nd:YAG laser irradiated; Group SB was sandblasted, Group SN was sandblasted and Nd:YAG laser irradiated; and Group SE was sandblasted and Er:YAG laser irradiated. After the surface treatments, the average surface roughness (Ra, µm) of each specimen was determined with a profilometer, then all the specimens were sintered. The surface roughness values were analysed through one-way ANOVA and Tukey's test. Changes in the morphological characteristics of ZrO2 were examined through scanning electron microscopy (SEM). Sintered sandblasted, Er:YAG laser treatment, sandblasted + Er:YAG laser and sandblasted + Nd:YAG laser irradiation resulted in a rougher surface than the other treatments. Nd:YAG laser irradiation alone was not effective in altering the zirconia surface morphology.

The effect of Ce3+ concentration and heat treatment on the luminescence efficiency of YAG phosphor

NASA Astrophysics Data System (ADS)

Valiev, Damir; Han, Tao; Vaganov, Vitaly; Stepanov, Sergey

2018-05-01

Y3Al5O12 (YAG) phosphor powders doped with Ce3+ at different concentrations (YAG:xCe, x = 0.02, 0.04, 0.06, 0.08, 0.1 wt%) were synthesized by the solid-state reaction method with the addition of BaF2 flux. The effects of cerium concentration and heat treatment on the luminescence efficiency of the YAG:Ce3+ phosphor were investigated. The introduction of Ce3+ ions leads to an increase in luminescent intensity of the YAG phosphor at 560 nm. The band at 530 nm is attributed to Ce3+ ions (optical transitions from the 4f-5d excited state). We assumed that such an increase in the luminescent intensity is due to the ability of Ce3+ to act as a luminescence sensitizer of intrinsic defects in YAG phosphor. The analysis of luminescence decay kinetics in the investigated samples has shown that the decay time in all samples does not differ significantly and equals τ ≈ 60 ± 3 ns. We showed experimentally that increasing the luminescence intensity has an effect observed with relatively low temperature treatment (T = 400 K). The nature of possible luminescence centers and the effect of low heat treatment on the luminescence properties of the powders are discussed.

Crystal growth, perfection, linear and nonlinear optical, photoconductivity, dielectric, thermal and laser damage threshold properties of 4-methylimidazolium picrate: an interesting organic crystal for photonic and optoelectronic devices

NASA Astrophysics Data System (ADS)

Rajesh, K.; Arun, A.; Mani, A.; Praveen Kumar, P.

2016-10-01

The 4-methylimidazolium picrate has been synthesized and characterized successfully. Single and powder x-ray diffraction studies were conducted which confirmed the crystal structure, and the value of the strain was calculated. The crystal perfection was determined by a HRXR diffractometer. The transmission spectrum exhibited a better transmittance of the crystal in the entire visible region with a lower cut-off wavelength of 209 nm. The linear absorption value was calculated by the optical limiting method. A birefringence study was also carried out. Second and third order nonlinear optical properties of the crystal were found by second harmonic generation and the z-scan technique. The crystals were also characterized by dielectric measurement and a photoconductivity analyzer to determine the dielectric property and the optical conductivity of the crystal. The laser damage threshold activity of the grown crystal was studied by a Q-switched Nd:YAG laser beam. Thermal studies established that the compound did not undergo a phase transition and was stable up to 240 °C.

Solar-Pumped TEM₀₀ Mode Nd:YAG laser.

PubMed

Liang, Dawei; Almeida, Joana

2013-10-21

Here we show a significant advance in solar-pumped laser beam brightness by utilizing a 1.0 m diameter Fresnel lens and a 3 mm diameter Nd:YAG single-crystal rod. The incoming solar radiation is firstly focused by the Fresnel lens on a solar tracker. A large aspheric lens and a 2D-CPC concentrator are then combined to further compress the concentrated solar radiation along the thin laser rod within a V-shaped pumping cavity. 2.3 W cw TEM₀₀ (M² ≤ 1.1) solar laser power is finally produced, attaining 1.9 W laser beam brightness figure of merit, which is 6.6 times higher than the previous record. For multimode operation, 8.1 W cw laser power is produced, corresponding to 143% enhancement in collection efficiency.

Tuning the sapphire EFG process to the growth of Al2O3/YAG/ZrO2:Y eutectic

NASA Astrophysics Data System (ADS)

Carroz, L.; Duffar, T.

2018-05-01

In this work, a model is proposed, in order to analytically study the working point of the Edge defined Film-fed Growth (EFG) pulling of crystal plates. The model takes into account the heat equilibrium at the interface and the pressure equilibrium across the meniscus. It is validated on an industrial device dedicated to the pulling of sapphire ribbons. Then, the model is applied to pulling ceramic alloy plates, of the ternary eutectic Al2O3/YAG/ZrO2:Y. This allowed understanding the experimental difficulties of pulling this new material and suggested improvements of the control software. From these results, pulling net shaped ceramic alloy plates was successful in the same industrial equipment as used for sapphire.

Nanophotonic switch: gold-in-Ga2O3 peapod nanowires.

PubMed

Hsieh, Chin-Hua; Chou, Li-Jen; Lin, Gong-Ru; Bando, Yoshio; Golberg, Dimitri

2008-10-01

A novel metal-insulator heterostructure made of twinned Ga2O3 nanowires embedding discrete gold particles along the twin boundary was formed through a reaction between gold, gallium, and silica at 800 degrees C during simple thermal annealing. The Au-in-Ga2O3 peapods spontaneously crystallized under phase separation induced by the formation of twin boundaries. The nanostructures were analyzed by field emission scanning (FESEM) and transmission electron microscopes (FETEM), and their photoresponse was investigated using a double-frequency Nd:YAG laser with a wavelength of 532 nm on a designed single-nanowire device. The surface plasmon resonance (SPR) effects of embedded Au nanoparticles are proposed to be responsible for the remarkable photoresponse of these novel structures.

Growth and characterization of Yb:Ho:YAG single crystal fiber

NASA Astrophysics Data System (ADS)

Yang, Yilun; Ye, Linhua; Bao, Renjie; Li, Shanming; Zhang, Peixiong; Xu, Min; Hang, Yin

2018-06-01

High quality Yb and Ho co-doped Y3Al5O12 single crystal fibers have been successfully grown by the laser heated pedestal growth method of up to 124 mm in length and 450 μm in diameter for the first time. The results of inductively coupled plasma-atomic emission spectrometry analysis, X-ray diffraction and Raman spectroscopy reveal that the lattice structure and doping concentrations of the SCF are the same as that of the bulk. Scanning electron microscopy microphotographs shows that the fibers only have minor diameter fluctuations within 0.5%.

Superresolution Microscopy of Single Rare-Earth Emitters in YAG and H 3 Centers in Diamond

NASA Astrophysics Data System (ADS)

Kolesov, R.; Lasse, S.; Rothfuchs, C.; Wieck, A. D.; Xia, K.; Kornher, T.; Wrachtrup, J.

2018-01-01

We demonstrate superresolution imaging of single rare-earth emitting centers, namely, trivalent cerium, in yttrium aluminum garnet crystals by means of stimulated emission depletion (STED) microscopy. The achieved all-optical resolution is ≈50 nm . Similar results were obtained on H 3 color centers in diamond. In both cases, STED resolution is improving slower than the conventional inverse square-root dependence on the depletion beam intensity. In the proposed model of this effect, the anomalous behavior is caused by excited state absorption and the interaction of the emitter with nonfluorescing crystal defects in its local surrounding.

Comparison between Er:YAG laser and bipolar radiofrequency combined with infrared diode laser for the treatment of acne scars: Differential expression of fibrogenetic biomolecules may be associated with differences in efficacy between ablative and non-ablative laser treatment.

PubMed

Min, Seonguk; Park, Seon Yong; Moon, Jungyoon; Kwon, Hyuck Hoon; Yoon, Ji Young; Suh, Dae Hun

2017-04-01

Fractional Er:YAG minimizes the risk associated with skin ablation. Infrared diode laser and radiofrequency have suggested comparable improvements in acne scar. We compared the clinical efficacy of Er:YAG laser and bipolar radiofrequency combined with diode laser (BRDL) for the treatment of acne scars. Moreover, acute molecular changes of cytokine profile associated with wound healing have been evaluated to suggest mechanisms of improvement of acne scar. Twenty-four subjects with mild-to-moderate acne scars were treated in a split-face manner with Er:YAG and BRDL, with two treatment sessions, 4 weeks apart. Objective and subjective assessments were done at baseline, 1, 3, 7 days after each treatment and 4 weeks after last treatment. Skin biopsy specimens were obtained at baseline, 1, 3, 7, 28 days after one session of treatment for investigation of molecular profile of acute skin changes by laser treatment. Investigator's Global Assessment representing the improvement degree shows 2.1 (50%) in fractional Er:YAG and 1.2 (25%) in BRDL. Er:YAG induced the later and higher peak expression of TGFβs and collagenases, whereas BRDL induced earlier and lower expression of TGFβ and collagenases, relatively. PPARγ dropped rapidly after a peak in Er:YAG-treated side, which is associated with tissue inhibitor of metalloproteinase (TIMP) expression. We observed higher expression of TIMP after Er:YAG treatment compared with BRDL by immunohistochemistry, which may be associated with the expression of upregulation of collagen fibers. The superior efficacy of Er:YAG to BRDL in the treatment of acne scars may be associated with higher expression of collagen which is associated with differential expression of TGFβs, collagenases, PPARγ, and TIMP. Lasers Surg. Med. 49:341-347, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Bracket debonding by mid-infrared laser radiation

NASA Astrophysics Data System (ADS)

Jelínková, H.; Šulc, J.; Dostálová, T.; Koranda, P.; Němec, M.; Hofmanova, P.

2009-03-01

The purpose of the study was to determine the proper laser radiation for ceramic bracket debonding and the investigation of the tooth root temperature injury. The debonding was investigated by diode-pumped continuously running Tm:YAP and Nd:YAG lasers, and by GaAs laser diode generating radiation with the wavelengths 1.997 μm, 1.444 μm, and 0.808 μm, respectively. The possibility of brackets removal by laser radiation was investigated together with the tooth and, it specifically, root temperature rise. From the results it follows that continuously running diode pumped Tm:YAG or Nd:YAG laser generating wavelengths 1.997 μm or 1.444 μm, respectively, having the output power 1 W can be good candidates for ceramic brackets debonding.

Laser ablation of dental tissues with picosecond pulses of 1.06-microm radiation transmitted through a hollow-core photonic-crystal fiber.

PubMed

Konorov, Stanislav O; Mitrokhin, Vladimir P; Fedotov, Andrei B; Sidorov-Biryukov, Dmitrii A; Beloglazov, Valentin I; Skibina, Nina B; Shcherbakov, Andrei V; Wintner, Ernst; Scalora, Michael; Zheltikov, Aleksei M

2004-04-10

Sequences of picosecond pulses of 1.06-microm Nd:YAG laser radiation with a total energy of approximately 2 mJ are transmitted through a hollow-core photonic-crystal fiber with a core diameter of approximately 14 microm and are focused onto a tooth's surface in vitro to ablate dental tissue. The hollow-core photonic-crystal fiber is shown to support the single-fundamental-mode regime for 1.06-microm laser radiation, serving as a spatial filter and allowing the laser beam's quality to be substantially improved. The same fiber is used to transmit emission from plasmas produced by laser pulses onto the tooth's surface in the backward direction for detection and optical diagnostics.

Optimization of mid-IR generation from a periodically poled MgO doped stoichiometric lithium tantalate optical parametric oscillator with intracavity difference frequency mixing

NASA Astrophysics Data System (ADS)

Hatano, Hideki; Slater, Richard; Takekawa, Shunji; Kusano, Masahiro; Watanabe, Makoto

2017-07-01

We demonstrate 43% slope efficiency for generation of ∼3200 nm light, a wavelength considered to be ideal for laser induced ultrasound generation in carbon fiber reinforced plastic. High slope efficiency was obtained by optimizing crystal lengths, cavity length and mirror reflectivity using a two crystal optical parametric oscillator+difference frequency mixing (OPO+DFM) nonlinear wavelength conversion scheme. Mid-IR output >12 mJ was obtained from a 1064 nm Nd:YAG pump laser with 12 ns pulse width (FWHM) and containing pulse energy of 43 mJ. A compact, single temperature crystal oven is described along with some suggestions for improving the slope efficiency.

Growth and physicochemical properties of second-order nonlinear optical 2-amino-5-chloropyridinium trichloroacetate single crystals

NASA Astrophysics Data System (ADS)

Renugadevi, R.; Kesavasamy, R.

2015-09-01

The growth of organic nonlinear optical (NLO) crystal 2-amino-5-chloropyridinium trichloroacetate (2A5CPTCA) has been synthesized and single crystals have been grown from methanol solvent by slow evaporation technique. The grown crystals were subjected to various characterization analyses in order to find out the suitability for device fabrication. Single crystal X-ray diffraction analysis reveals that 2A5CPTCA crystallizes in monoclinic system with the space group Cc. The grown crystal was further characterized by Fourier transform infrared spectral analysis to find out the functional groups. The nuclear magnetic resonance spectroscopy is a research technique that exploits the magnetic properties of certain atomic nuclei. The optical transparency window in the visible and near-IR (200--1100 nm) regions was found to be good for NLO applications. Thermogravimetric analysis and differential thermal analysis were used to study its thermal properties. The powder second harmonic generation efficiency measurement with Nd:YAG laser (1064 nm) radiation shows that the highest value when compared with the standard potassium dihydrogen phosphate crystal.

Primary investigations on the potential of a novel diode pumped Er:YAG laser system for middle ear surgery

NASA Astrophysics Data System (ADS)

Stock, Karl; Wurm, Holger; Hausladen, Florian

2016-02-01

Flashlamp pumped Er:YAG lasers are successfully used clinically for both precise soft and hard tissue ablation. Since several years a novel diode pumped Er:YAG laser system (Pantec Engineering AG) is available, with mean laser power up to 40 W and pulse repetition rate up to 1 kHz. The aim of the study was to investigate the suitability of the laser system specifically for stapedotomy. Firstly an experimental setup was realized with a beam focusing unit and a computer controlled translation stage to move the samples (slices of porcine bone) with a defined velocity while irradiation with various laser parameters. A microphone was positioned in a defined distance to the ablation point and the resulting acoustic signal of the ablation process was recorded. For comparison, measurements were also performed with a flash lamp pumped Er:YAG laser system. After irradiation the resulting ablation quality and efficacy were determined using light microscopy. Using a high speed camera and "Töpler-Schlierentechnik" the cavitation bubble in water after perforation of a bone slice was investigated. The results show efficient bone ablation using the diode pumped Er:YAG laser system. Also a decrease of the sound level and of the cavitation bubble volume was observed with decreasing pulse duration. Higher repetition rates lead to a slightly increase of thermal side effects but have no influence on the ablation efficiency. In conclusion, these first experiments demonstrate the high potential of the diode pumped Er:YAG laser system for use in middle ear surgery.

Effect of different surface treatments on tensile bond strength of silicone-based soft denture liner.

PubMed

Akin, Hakan; Tugut, Faik; Mutaf, Burcu; Akin, Gulsah; Ozdemir, A Kemal

2011-11-01

Failure of the bond between the acrylic resin and resilient liner material is commonly encountered in clinical practice. The purpose of this study was to investigate the effect of different surface treatments (sandblasting, Er:YAG, Nd:YAG, and KTP lasers) on tensile bond strength of silicone-based soft denture liner. Polymethyl methacrylate test specimens were fabricated and each received one of eight surface treatments: untreated (control), sandblasted, Er:YAG laser irradiated, sandblasted + Er:YAG laser irradiated, Nd:YAG laser irradiated, sandblasted + Nd:YAG laser irradiated, KTP laser irradiated, and sandblasted + KTP laser irradiated. The resilient liner specimens (n = 15) were processed between two polymethyl methacrylate (PMMA) blocks. Bonding strength of the liners to PMMA were compared by tensile test with the use of a universal testing machine at a crosshead speed of 5 mm/min. Kruskal-Wallis and Wilcoxon tests were used to analyze the data (α = 0.05). Altering the polymethyl methacrylate surface by Er:YAG laser significantly increased the bond strengths in polymethyl methacrylate/silicone specimens, however, sandblasting before applying a lining material had a weakening effect on the bond. In addition, Nd:YAG and KTP lasers were found to be ineffective for increasing the strength of the bond.

Efficient nonlinear optical conversion of 1.319-micron laser radiation

NASA Astrophysics Data System (ADS)

Byer, Robert L.; Eckardt, Robert C.

1993-01-01

The accomplishments of this program are in the development and application of periodically poled nonlinear optical materials for nonlinear frequency-conversion. We have demonstrated the use of periodically poled lithium niobate (PPLN) as a bulk material for external resonant cavity second-harmonic generation with continuous-wave (cw) output power of 1.7 W. Work that is following this investigation is showing that planar waveguides of PPLN may well be the most satisfactory method of generation of 10's of mW of the 659-nm harmonic of the 1.32-micrometer Nd:YAG laser. We encountered major obstacles obtaining multilayer dielectric coatings necessary to pursue our proposed design of monolithic bulk optical harmonic generators. Additional alternative approaches such as discrete component resonant second harmonic generation employing single domain and periodically poled bulk crystals and monolithic single domain resonators formed by total internal reflection remain under investigation.

Neodymium: YAG laser damage threshold. A comparison of injection-molded and lathe-cut polymethylmethacrylate intraocular lenses.

PubMed

Wilson, S E; Brubaker, R F

1987-01-01

The possibility that injection-molded intraocular lenses (IOLs) with imperfections called iridescent clefts could have a decreased threshold to neodymium: YAG (Nd:YAG) laser-induced damage was investigated. Thresholds for Nd:YAG laser-induced damage were determined for injection-molded and lathe-cut polymethylmethacrylate lenses. When aimed at a membrane in contact with a posterior convex surface, the average thresholds were 0.96 +/- 0.18 mJ (Standard deviation [SD]) and 1.80 +/- 0.55 mJ, respectively. The difference was significant at P = 0.001. When injection-molding polymethylmethacrylate was used to make lathe-cut IOLs, very few iridescent clefts were present, and the threshold to Nd:YAG laser-induced damage was 0.94 +/- 0.25 mJ. Iridescent clefts are therefore produced during the injection-molding process but they do not lower the threshold to Nd:YAG laser-induced damage. Rather, the reduced threshold in injection-molded lenses is most probably a result of the polymethylmethacrylate used in their manufacture. Clinically, iridescent clefts in a lens suggest that it has been manufactured by an injection-molding process and that Nd:YAG laser posterior capsulotomy must be performed at the lowest possible energy level to avoid damage.

Millijoule-level 20 ps Nd:YAG oscillator-amplifier laser system for investigation of stimulated Raman scattering and optical parametric generation

NASA Astrophysics Data System (ADS)

Jelínek, Michal; Kubecek, Vàclav

2012-06-01

We report on quasi-continuously pumped oscillator-amplifier laser system. The laser oscillator was based on highly 2.4 at.% doped crystalline Nd:YAG in a bounce geometry and passively mode locked by a semiconductor saturable absorber mirror. Using the cavity dumping technique, 19 ps pulses with the energy of 20 μJ and Gaussian spatial beam profile were generated directly from the oscillator at the repetition rate up to 50 Hz. For applications requiring more energetic pulses the amplification was studied using either an identical highly doped Nd:YAG module in bounce geometry or flashlamp pumped Nd:YAG laser rod. Using compact all diode pumped oscillator-amplifier system, 130 μJ pulses were generated. The flashlamp pumped amplifier with 100 mm long Nd:YAG enabled to obtain higher energy. In the single pass configuration the pulse was amplified to 4.5 mJ, using the double pass configuration the pulse energy was further increased up to 20 mJ with the duration of 25 ps at 10 Hz. The developed laser system was used for investigation of stimulated Raman scattering in Strontium Barium Niobate and optical parametric generation in CdSiP2.

Laboratory investigation of the efficacy of holmium:YAG laser irradiation in removing intracanal debris

NASA Astrophysics Data System (ADS)

Nuebler-Moritz, Michael; Gutknecht, Norbert; Sailer, Hermann F.; Hering, Peter; Prettl, Wilhelm

1997-05-01

Current endodontic therapy involves debridement and disinfection of the root canal by means of mechanical instrumentation and chemical irrigation. However, several studies have shown that these techniques fail to achieve complete cleansing. Recently, lasers have been suggested for use within root canals. This study was conducted to determine the efficacy of Holmium:YAG laser irradiation in removing intracanal debris and smear layer. Root canal surfaces of freshly-extracted human teeth were exposed to pulsed Ho:YAG laser radiation. Subsequently, laser induced structural changes were investigated using scanning electron microscopy. Temperature measurements during irradiation were performed by means of thermocouples. The result of this survey give a preliminary indication of the ability of the Ho:YAG laser to improve current endodontic treatment survey give a preliminary indication of the ability of the Ho:YAG laser to improve current endodontic treatment modalities. However, limitations exist with regard to circumscribed and well-quantified irradiation of root canal surfaces, due to the lack of perpendicular delivery of the laser beam. Additional studies will be required to develop suitable optical transmission systems, in order to achieve complete cleansing and to avoid damage to the periradicular tissues, respectively.

Treatment of Melasma with the Photoacoustic Twin Pulse Mode of Low-Fluence 1,064 nm Q-Switched Nd:YAG Laser.

PubMed

Kim, Jee Young; Choi, Misoo; Nam, Chan Hee; Kim, Ji Seok; Kim, Myung Hwa; Park, Byung Cheol; Hong, Seung Phil

2016-06-01

Low-fluence 1,064 nm Q-switched Nd:YAG laser has been widely used for the treatment of melasma. Although new Q-switched Nd:YAG lasers with photoacoustic twin pulse (PTP) mode have been recently developed for high-efficiency, there is limited information available for the new technique. This study was designed to investigate the efficacy and adverse effects after few sessions of repeated low fluence 1,064 nm Q-switched Nd:YAG laser treatment with PTP mode in Asian women with melasma. Twenty-two Korean women were treated with a total of five sessions of low-fluence PTP mode Nd:YAG laser treatment (Pastelle®) at 2 weeks interval. Responses to treatments were evaluated by using Melasma Area and Severity Index (MASI) scoring, colorimeter measurement, and the investigators' and patients' overall assessments. Adverse events were recorded at each visit. Investigators' and patients' overall assessment showed that 'significantly improved' was assessed by 13 (59.1%) and 19 of 22 patients (86.4%), respectively. MASI scores were significantly reduced by 20.4%. The lightness, measured by using a colorimeter, was significantly increased by 1.3 point. Notable adverse events were not observed. After 5 sessions of laser therapy alone, about 60% of the subjects showed significant improvement. Few sessions of repeated laser toning treatment using the PTP mode is a safe and effective way to treat facial melasma.

High-power ultraviolet 278-nm laser from fourth-harmonic generation of an Nd:YAG amplifier in CsB3O5 crystal

NASA Astrophysics Data System (ADS)

He, Miao; Yang, Feng; Dong, Cheng; Wang, Zhi-Chao; Yuan, Lei; Xu, Yi-Ting; Zhang, Guo-Chun; Wang, Zhi-Min; Bo, Yong; Peng, Qin-Jun; Cui, Da-Fu; Wu, Yi-Cheng; Xu, Zu-Yan

2018-05-01

Not Available Project supported by the National Natural Science Foundation Program of China (Grant Nos. 11504389 and 61505226), the National Key Research Development Program of China (Grant Nos. 2016YFB040203 and 61535013), and the National Development Project for Major Scientific Research Facility of China (Grant No. ZDYZ2012-2).

New life of recycled rare earth-oxides powders for lighting applications.

NASA Astrophysics Data System (ADS)

Carlo Ricci, Pier; Murgia, Massimiliano; Carbonaro, Carlo Maria; Sgariotto, Serena; Stagi, Luigi; Corpino, Riccardo; Chiriu, Daniele; Grilli, Maria Luisa

2018-03-01

In this work we analysed the optical and structural properties of Ce:YAG regenerated phosphors. The concentrate resulted as the final product of an industrial recycling process of waste electrical and electronic equipment (WEEE), and in particular fluorescent powders coming from spent lamps treatment plant. The waste pristine materials were re-utilized without any further purification and or separation process as starting materials to obtain a YAG matrix (Y2Al5O12) doped with Cerium ions. We tested out the recovered concentrate against commercial Ce:YAG phosphors comparing their structural and optical properties by means of XRD measurements and steady time and time resolved luminescence. The analysis reveals that the new phosphors obtained by scrap powder have the same crystal structure as the commercial reference sample and comparable optical properties. In particular, the Ce-related emission efficiency has a quantum yield of about 0.75 when excited at 450 nm, in good agreement with our reference sample and with the one of commercial powder presently exploited in white LED. This achievement strongly suggests the possibility of a new life for the exhausted phosphors and a possible step forward to a complete circular process for lighting equipment.

On the use of a chirped Bragg grating as a cavity mirror of a picosecond Nd : YAG laser

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

Zubko, A E; Shashkov, E V; Smirnov, A V

2016-02-28

The first experimental evidence is presented that the use of a chirped volume Bragg grating (CVBG) as a cavity mirror of a Q-switched picosecond Nd : YAG laser with self-mode-locking leads to significant changes in the temporal parameters of the laser output. Measurements have been performed at two positions of the CVBG: with the grating placed so that shorter wavelengths reflected from its front part lead longer wavelengths or with the grating rotated through 180°, so that longer wavelengths are reflected first. In the former case, the duration of individual pulses in a train increased from ∼35 to ∼300 ps,more » whereas the pulse train shape and duration remained the same as in the case of a conventional laser with a mirror cavity. In the latter case, the full width at half maximum of pulse trains increased from ∼70 ns (Nd : YAG laser with a mirror cavity) to ∼1 ms, and the duration of individual pulses increased from 35 ps to ∼1.2 ns, respectively, which is more typical of free-running laser operation. (laser crystals and braggg ratings)« less

Single fiber temperature probe configuration using anti-Stokes luminescence from Cr:GdAlO3

NASA Astrophysics Data System (ADS)

Eldridge, Jeffrey I.

2018-06-01

Single-photon excitation of anti-Stokes-shifted emission from a thermographic phosphor allows operation of a luminescence decay-based single fiber temperature probe with negligible interference from background fiber-generated Raman scattering. While single fiber probe configurations for luminescence-based fiber optic thermometers offer advantages of simple design, compactness, and superior emission light collection efficiency, their effective use has been limited by interference from Raman scattering in the fiber probe and excitation delivery fiber that produces distortion of the luminescence decay that follows the excitation pulse. The near elimination of interference by background fiber-generated Raman scattering was demonstrated by incorporating a Cr-doped GdAlO3 (Cr:GdAlO3) thermographic phosphor as the sensing element at the end of a single fiber luminescence decay-based thermometer and detecting anti-Stokes-shifted luminescence centered at 542 or 593 nm produced by 695 nm excitation. Measurements were performed using both silica (up to 1150 °C) and single-crystal YAG (up to 1200 °C) fiber-based thermometers. Selection of emission detection centered at 542 nm greatly benefited the YAG fiber probe measurements by practically eliminating detection of otherwise significant luminescence from Cr3+ impurities in the YAG fiber. For both the silica and YAG fiber probes, the relative benefit of adopting single-photon excitation of anti-Stokes-shifted luminescence was evaluated by comparison with results obtained by conventional 532 nm excitation of Stokes-shifted luminescence.

Idler-resonant intracavity KTA-based OPO pumped by a dual-loss modulated-Q-switched-laser with AOM and Cr4+:YAG

NASA Astrophysics Data System (ADS)

Qiao, Junpeng; Zhao, Shengzhi; Yang, Kejian; Zhao, Jia; Li, Guiqiu; Li, Dechun; Li, Tao; Qiao, Wenchao

2017-06-01

An idler-resonant KTiOAsO4 (KTA)-based intracavity optical parametric oscillator (IOPO) pumped by a dual-loss-modulated Q-switched laser with an acousto-optic modulator (AOM) and a Cr4+:YAG saturable absorber (Cr4+:YAG-SA) has been presented. By utilizing a type-II non-critically phase-matched KTA crystal, signal wave at 1535 nm and idler wave at 3467 nm have been generated. Under an incident pump power of 18.3 W, maximum output powers of 615 mW for signal wave and 228 mW for idler wave were obtained at an AOM modulation rate of 10 kHz, corresponding to a whole optical-to-optical conversion efficiency of 4.6%. The shortest pulse widths of signal and idler wave were measured to be 898 ps and 2.9 ns, corresponding to the highest peak powers of 68.4 and 7.9 kW, respectively. In comparison with IOPO pumped by a singly Q-switched laser with an AOM, the IOPO pumped by a doubly Q-switched laser (DIOPO) with an AOM and a Cr4+:YAG-SA can generate signal wave and idler wave with shorter pulse width and higher peak power. By considering the spatial Gaussian distribution of intracavity photon density, a set of coupled rate equations for the idler-resonant DIOPO were built for the first time to the best of our knowledge. The simulation results agreed well with the experimental results.

Dual-wavelength, continuous-wave Yb:YAG laser for high-resolution photothermal common-path interferometry.

PubMed

Zhuang, Fengjiang; Jungbluth, Bernd; Gronloh, Bastian; Hoffmann, Hans-Dieter; Zhang, Ge

2013-07-20

We present a continuous-wave (CW) intracavity frequency-doubled Yb:YAG laser providing 1030 and 515 nm output simultaneously. This laser system was designed for photothermal common-path interferometry to measure spatially resolved profiles of the linear absorption in dielectric media and coatings for visible or infrared light as well as of the nonlinear absorption for the combination of both. A Z-shape laser cavity was designed, providing a beam waist in which an LBO crystal was located for effective second-harmonic generation (SHG). Suitable frequency conversion parameters and cavity configurations were discussed to achieve the optimal performance of a diode-pumped CW SHG laser. A 12.4 W 1030 nm laser and 5.4 W 515 nm laser were developed simultaneously in our experiment.

Temperature tuning of lasing emission from dye-doped liquid crystal at intermediate twisted phase

NASA Astrophysics Data System (ADS)

Liao, Kuan-Cheng; Lin, Ja-Hon; Jian, Li-Hao; Chen, Yao-Hui; Wu, Jin-Jei

2015-07-01

Temperature tuning of lasing emission from dye-doped cholesteric liquid crystal (CLC) at intermediate twisted phase has been demonstrated in this work. With heavily doping of 42.5% chiral molecules into the nematic liquid crystals, the shifts of photonic bandgap versus temperature is obviously as thermal controlling of the sample below the certain value. By the differential scanning calorimetr measuremet, we demonstrate the phase transition from the CLC to the smectic phase when the temperature is lowered to be about 15°C. Between CLC and smectic phase, the liquid crystal mixtures are operated at intermediate twisted phase that can be used the temperature related refractive mirror. After pump by the Q-switched Nd:YAG laser, the lasing emission from this dye doped LC mixtures has been demonstrated whose emission wavelength can be tuned from 566 to 637 nm with 1.4°C variation.

Characterization of LaF 3 coatings prepared at different temperatures and rates

NASA Astrophysics Data System (ADS)

Yu, Hua; Shen, Yanming; Cui, Yun; Qi, Hongji; Shao, JianDa; Fan, ZhengXiu

2008-01-01

LaF 3 thin films were prepared by thermal boat evaporation at different substrate temperatures and various deposition rates. X-ray diffraction (XRD), Lambda 900 spectrophotometer and X-ray photoelectron spectroscopy (XPS) were employed to study crystal structure, transmittance and chemical composition of the coatings, respectively. Laser-induce damage threshold (LIDT) was determined by a tripled Nd:YAG laser system with a pulse width of 8 ns. It is found that the crystal structure became more perfect and the refractive index increased gradually with the temperature rising. The LIDT was comparatively high at high temperature. In the other hand, the crystallization status also became better and the refractive index increased when the deposition rate enhanced at a low level. If the rate was super rapid, the crystallization worsened instead and the refractive index would lessen greatly. On the whole, the LIDT decreased with increasing rate.

Efficient eye-safe neodymium doped composite yttrium gallium garnet crystal laser.

PubMed

Yu, Haohai; Wang, Shuxian; Han, Shuo; Wu, Kui; Su, Liangbi; Zhang, Huaijin; Wang, Zhengping; Xu, Jun; Wang, Jiyang

2014-03-15

We report a laser-diode pumped continuous-wave (cw) and passively Q-switched eye-safe laser at about 1.42 μm with the neodymium-doped yttrium gallium garnet (Nd:YGG) crystal for the first time to our knowledge. The composite Nd:YGG crystal was developed originally. A systematic comparison of laser performance between the homogeneously doped and composite Nd:YGG crystal was made, which showed that the composite Nd:YGG manifested less thermally induced effects. Cw output power of 2.06 W was obtained with the slope efficiency of 20.7%. With a V:YAG as a saturable absorber, the passive Q-switching at 1.42 μm was gotten with the pulse width, pulse energy, and peak power of 34 ns, 46.7 μJ, and 1.4 kW, respectively. The present work should provide a potential candidate for the generation of eye-safe lasers.

Dual-laser-beam-induced breakdown spectroscopy of copper using simultaneous continuous wave CO(2) and Q-switched Nd:YAG lasers.

PubMed

Shoursheini, S Z; Parvin, P; Sajad, B; Bassam, M A

2009-04-01

In this work, we investigate the enhancement of Cu emission lines of a micro-plasma induced by a Nd:YAG laser due to the thermal effect of simultaneous irradiation by a continuous wave (CW) CO(2) laser. The enhancement of the emission lines was achieved at a higher temperature with minimal distortion of the target when the focal point of the Nd:YAG laser was located approximately 1 mm away from the sample surface.

Emittance Theory for Thin Film Selective Emitter

NASA Technical Reports Server (NTRS)

Chubb, Donald L.; Lowe, Roland A.; Good, Brian S.

1994-01-01

Thin films of high temperature garnet materials such as yttrium aluminum garnet (YAG) doped with rare earths are currently being investigated as selective emitters. This paper presents a radiative transfer analysis of the thin film emitter. From this analysis the emitter efficiency and power density are calculated. Results based on measured extinction coefficients for erbium-YAG and holmium-YAG are presented. These results indicated that emitter efficiencies of 50 percent and power densities of several watts/sq cm are attainable at moderate temperatures (less than 1750 K).

Crystal growth, structural, spectral, thermal, linear and nonlinear optical characterization of a new organic nonlinear chiral compound: L-tryptophan-fumaric acid-water (1/1/1) suitable for laser frequency conversion

NASA Astrophysics Data System (ADS)

Peer Mohamed, M.; Jayaprakash, P.; Nageshwari, M.; Rathika Thaya Kumari, C.; Sangeetha, P.; Sudha, S.; Mani, G.; Lydia Caroline, M.

2017-08-01

A new organic active nonlinear optical crystal L-tryptophan fumaric acid water (1/1/1), (C15H17N2 O7. H2O)(LTFAW), consisting of zwitterion tryptophan molecule in conjunction with a fumaric acid molecule and a water molecule was grown by slow solvent evaporation technique from aqueous solution. The organic chromophore crystallizes from water in its zwitterions exhibiting tabular habit in monoclinic system with acentric space group C2 (Z = 4). The sharp peaks observed in Powder X-ray diffractogram depicts the crystalline nature. The presence of functional groups in the grown crystal was analyzed using FT-IR spectrum. The carbon and hydrogen environment in molecular structure was investigated using FT-NMR technique using deuterated DMSO solution. Ultraviolet-visible spectral analysis reveal that the crystal possess lower cut-off wavelength down to 275 nm, is a key factor to exhibit Second Harmonic Generation (SHG) signal. The direct optical band gap is evaluated to be 5.28 eV from the UV absorption profile. The evaluation of optical constants by employing UV-visible absorbance data such as, extinction coefficient, reflectance, refractive index, optical conductivity are supportive towards good performance as NLO devices. Temperature of decomposition was investigated using thermogravimetric analysis/differential thermal analysis techniques (TG/DTA). The luminescence profile exhibited two peaks (362 nm, 683 nm) due to the donation of protons from carboxylic group to amino group. The nonlinear optical behavior from the noncentrosymmetric crystal was observed by the generation of frequency doubled (2ω) optical radiation when subjected to pulsed Nd:YAG laser (1064 nm, 10 ns, 10 Hz) using Kurtz-Perry method. The variation of dielectric constant (εʹ) and dielectric loss (εʹʹ) vs. Log f for the title compound was analysed at a few selected temperatures and frequencies.

Hollow-core photonic-crystal fibres for laser dentistry.

PubMed

Konorov, Stanislav O; Mitrokhin, Vladimir P; Fedotov, Andrei B; Sidorov-Biryukov, Dmitrii A; Beloglazov, Valentin I; Skibina, Nina B; Wintner, Ernst; Scalora, Michael; Zheltikov, Aleksei M

2004-04-07

Hollow-core photonic-crystal fibres (PCFs) for the delivery of high-fluence laser radiation capable of ablating tooth enamel are developed. Sequences of picosecond pulses of 1.06 microm Nd:YAG-laser radiation with a total energy of about 2 mJ are transmitted through a hollow-core photonic-crystal fibre with a core diameter of approximately 14 microm and are focused on a tooth surface in vitro to ablate dental tissue. The hollow-core PCF is shown to support the single-fundamental-mode regime for 1.06 microm laser radiation, serving as a spatial filter and allowing the laser beam quality to be substantially improved. The same fibre is used to transmit emission from plasmas produced by laser pulses on the tooth surface in the backward direction for detection and optical diagnostics.

Impact of Laser Radiation on Microhardness of a Semiconductor

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

Medvid', A.; Onufrijevs, P.; Chiradze, G.

2011-12-23

It was found that strongly absorbed Nd:YAG laser radiation leads to a non-monotonous dependence of microhardness of p- and n-type Si crystals on laser radiation. This dependence is characterized by two maxima for p-Si and one maximum for n-Si crystals. In both cases the increase of microhardness at higher laser intensity is explained by formation of mechanically compressed layer at the irradiated surface due to concentration of the interstitial atoms of Si at the surface in temperature gradient field. The decrease of the microhardness is explained by formation of nano-cones as a result of plastic deformation of the mechanically stressedmore » layer. The additional maximum at lower laser intensity for p-Si crystal is explained by p-n type inversion of Si conductivity.« less

A high repetition rate passively Q-switched microchip laser for controllable transverse laser modes

NASA Astrophysics Data System (ADS)

Dong, Jun; Bai, Sheng-Chuang; Liu, Sheng-Hui; Ueda, Ken-Ichi; Kaminskii, Alexander A.

2016-05-01

A Cr4+:YAG passively Q-switched Nd:YVO4 microchip laser for versatile controllable transverse laser modes has been demonstrated by adjusting the position of the Nd:YVO4 crystal along the tilted pump beam direction. The pump beam diameter-dependent asymmetric saturated inversion population inside the Nd:YVO4 crystal governs the oscillation of various Laguerre-Gaussian, Ince-Gaussian and Hermite-Gaussian modes. Controllable transverse laser modes with repetition rates over 25 kHz and up to 183 kHz, depending on the position of the Nd:YVO4 crystal, have been achieved. The controllable transverse laser beams with a nanosecond pulse width and peak power over hundreds of watts have been obtained for potential applications in optical trapping and quantum computation.

Radially polarized and passively Q-switched Yb-doped fiber laser based on intracavity birefringent mode discrimination

NASA Astrophysics Data System (ADS)

Sun, Xuehuan; Wu, Yongxiao; Chen, Sanbin; Li, Jianlang

2018-05-01

In this paper, we demonstrated a passive Q-switched ytterbium-doped fiber laser with radially polarized beam emission by using a c-cut YVO4 birefringent crystal as the intracavity polarization discriminator, and a Cr4+:YAG crystal as the saturable absorber and output coupler. The maximum averaged laser power reached 3.89 W with a high slope efficiency of 66.5%. The laser pulse had a peak power of 161 W, 160 ns duration, and 151 kHz repetition rate at the absorbed pump power of 6.48 W. Such a radially polarized pulse would facilitate numerous applications.

Potential applications of Erbium:YAG laser in periodontics.

PubMed

Ishikawa, Isao; Aoki, Akira; Takasaki, Aristeo Atsushi

2004-08-01

Since lasers were introduced for the treatment of oral diseases, there has been considerable advancement in technology. As a result, numerous laser systems are currently available for oral use. Neodymium:Yttrium-Aluminum:Garnet (Nd:YAG), carbon dioxide (CO(2)) laser and the semiconductor Diode lasers have already been approved by the US Food and Drug Administration for soft tissue treatment in oral cavity. The Erbium:YAG (Er:YAG) laser was approved in 1997 for hard tissue treatment in dentistry and recent studies have reported positive results. This suggests that the Er:YAG laser system is a promising apparatus, which will be able to revolutionize and improve dental practice, in particular periodontal treatment. In this mini-review, we would like to describe the positive characteristics of the Er:YAG laser which indicate its potential as a new treatment modality in periodontics. Recent findings are summarized briefly to evaluate the potential of the Er:YAG laser for clinical application in periodontics. The Er:YAG laser possesses suitable characteristics for oral soft and hard tissue ablation. Recently, it has been applied for effective elimination of granulation tissue, gingival melanin pigmentation and gingival discoloration. Contouring and cutting of bone with minimal damage and even or faster healing can also be performed with this laser. In addition, irradiation with the Er:YAG laser has a bactericidal effect with reduction of lipopolysaccharide, high ability of plaque and calculus removal, with the effect limited to a very thin layer of the surface and is effective for implant maintenance. The Er:YAG laser seems to be an effective tool for periodontal therapy, however, further clinical and basic investigations are required to confirm its clinical application. Copyright Blackwell Munksgaard, 2004

Two-wavelength, passive self-injection-controlled operation of diode-pumped cw Yb-doped crystal lasers.

PubMed

Louyer, Yann; Wallerand, Jean-Pierre; Himbert, Marc; Deneva, Margarita; Nenchev, Marin

2003-09-20

We demonstrate and investigate a peculiar mode of cw Yb3+-doped crystal laser operation when two emissions, at two independently tunable wavelengths, are simultaneously produced. Both emissions are generated from a single pumped volume and take place in either a single beam or spatially separated beams. The laser employs original two-channel cavities that use a passive self-injection-locking (PSIL) control to reduce intracavity loss. The advantages of the application of the PSIL technique and some limitations are shown. The conditions for two-wavelength multimode operation of the cw quasi-three-level diode-pumped Yb3+ lasers and the peculiarity of such an operation are carried out both theoretically and experimentally. The results reported are based on the example of a Yb3+:GGG laser but similar results are also obtained with a Yb3+:YAG laser. The laser operates in the 1023-1033-nm (1030-1040-nm) range with a total output power of 0.4 W. A two-wavelength, single longitudinal mode generation is also obtained.

HOMO-LUMO analysis of multi walled carbon nanotubes doped Tetrafluoro Phthalate crystals for nonlinear optical applications

NASA Astrophysics Data System (ADS)

Latha, B.; Kumaresan, P.; Nithiyanantham, S.; Sampathkumar, K.

2018-01-01

The MWCNTs doped Tetrafluoro Phthalate (C6H2F4O4) precious stones are constantly having higher transmission rate contrasted with immaculate Tetrafluoro Phthalate crystal. The dependability of Tetrafluoro Phthalate crystal was enhanced by doping MWCNTs.The basic, synthetic, optical, mechanical and non-direct optical properties of the doped precious crystals were dissected with the portrayal concentrates, for example, powder XRD, FT-IR, UV-Visible, Hardness and SHG estimations individually. The dopants are relied upon to substitute the carbon iotas in the Tetrafluoro Phthalate grid because of their change of valency and in addition vicinity of ionic sweep. The strength and charge delocalization of the particle were additionally concentrated on by characteristic security orbital (NBO) examination. The HOMO-LUMO energies depict the charge exchange happens inside the atom. Atomic electrostatic potential has been dissected. The SHG productivity of the immaculate and colors doped TFP crystals were additionally contemplated utilizing Nd:YAG Q-exchanged laser.

Synthesis, growth, structure and nonlinear optical properties of a semiorganic 2-carboxy pyridinium dihydrogen phosphate single crystal

NASA Astrophysics Data System (ADS)

Nagapandiselvi, P.; Baby, C.; Gopalakrishnan, R.

2015-09-01

A new semiorganic compound namely, 2-carboxy pyridinium dihydrogen phosphate (2CPDP) was synthesised and grown as single crystals by slow evaporation solution growth technique. Single crystal XRD showed that 2CPDP belongs to monoclinic crystal system with space group P21/n. The molecular structure was further confirmed by modern spectroscopic techniques like FT-NMR (1H, 13C &31P), FT-IR, UV-Vis-NIR and Fluorescence. The UV-Vis-NIR analysis revealed suitability of the crystal for nonlinear optical applications. The photo active nature of the material is established from fluorescence studies. TG-DSC analysis showed that 2CPDP was thermally stable up to 170 °C. The dependence of dielectric properties on frequency and temperature were also studied. Nonlinear optical absorption determined from open aperture Z-Scan analysis by employing picosecond Nd-YAG laser, revealed that 2CPDP can serve as a promising candidate for optical limiting applications.

Er:YAG laser debonding of porcelain veneers

NASA Astrophysics Data System (ADS)

Buu, Natalie; Morford, Cynthia; Finzen, Frederick; Sharma, Arun; Rechmann, Peter

2010-02-01

The removal of porcelain veneers using Er:YAG lasers has not been previously described in the scientific literature. This study was designed to systematically investigate the efficacy of an Er:YAG laser on veneer debonding without damaging the underlying tooth structure, as well as preserving a new or misplaced veneer. Initially, Fourier Transform Infrared Spectroscopy (FTIR) was used on flat porcelain veneer samples (IPS Empress Esthetic; Ivoclar Vivadent, Amherst, NY) to assess which infrared laser wavelengths are transmitted through the veneer. Additionally, FTIR spectra from a veneer bonding cement (RelyX Veneer Cement A1; 3M ESPE, St. Paul, MN) were obtained. While the veneer material showed no characteristic water absorption bands in the FTIR, the bonding cement has a broad H2O/OH absorption band coinciding with the ER:YAG laser emission wavelength. Consequently Er:YAG laser energy transmission through different veneer thicknesses was measured. The porcelain veneers transmitted 11 - 18 % of the incident Er:YAG laser energy depending on their thicknesses (Er:YAG laser: LiteTouch by Syneron; wavelength 2,940 nm, 10 Hz repetition rate, pulse duration 100 μs at 133 mJ/pulse; straight sapphire tip 1,100 μm diameter; Syneron, Yokneam, Israel). Initial signs of cement ablation occurred at approximately 1.8 - 4.0 J/cm2. This can be achieved by irradiating through the veneer with the fiber tip positioned at a distance of 3-6 mm from the veneer surface, and operating the Er:YAG laser with 133 mJ output energy. All eleven veneers bonded on extracted anterior incisor teeth were easily removed using the Er:YAG laser. The removal occurred without damaging underlying tooth structure as verified by light microscopic investigation (Incident Light Microscope Olympus B 50, Micropublisher RTV 3.3 MP, Image Pro software, Olympus). The debonding mainly occurred at the cement/veneer interface. When the samples were stored in saline solution for 5 days and/or an air-waterspray was used during irradiation, there was a high chance that the veneer would fractured during debonding. However if samples were not stored in water and only air spray was used, 75% of the veneers could be removed without any fracture. The use of an Er:YAG laser can be effective in not only debonding porcelain veneers and preserving tooth structure, but also in maintaining veneer integrity.

Laser-induced Fluorescence Spectroscopy for applications in chemical sensing and optical refrigeration

NASA Astrophysics Data System (ADS)

Kumi Barimah, Eric

Laser-induced breakdown spectroscopy (LIBS) is an innovative technique that has been used as a method for fast elemental analysis in real time. Conventional ultraviolet-visible (UV-VIS) LIBS has been applied to detect the elemental composition of different materials, including explosives, pharmaceutical drugs, and biological samples. The extension of conventional LIBS to the infrared region (˜1-12 mum) promises to provide additional information on molecular emission signatures due to rotational-vibrational transitions. In this research, a pulsed Nd: YAG laser operating at 1064 nm was focused onto several sodium compounds (NaCl, NaClO3, Na2CO3 and NaClO4) and potassium compounds (KCl, KClO3, K2CO3 and KClO4) to produce an intense plasma at the target surface. Several distinct infrared (IR) atomic emission signatures were observed from all sodium and potassium containing compounds. The atomic emission lines observed from the investigated samples matched assigned transitions of neutral sodium and potassium atoms published in the National Institute of Standards and Technology (NIST) atomic database. In addition to the intense atomic lines, the rst evidence of molecular LIBS emission structures were observed at ˜10.0 m in KClO3 and NaClO3 for the chlorate anion (ClO3 --1), at ˜6.7 to 8.0 mum in KNO3 and NaNO 3 for the nitrate anion (NO3--1 ), ˜8.0 to 10.0 mum in KClO4 and NaClO4 for perchlorate anion (ClO4--1 ), and ˜6.88 mum and 11.53 mum in Na2CO3 for the carbonate anion (CO3--1 ). The observed molecular emission showed strong correlation with the conventional Fourier Transform Infrared Spectrometry (FTIR) absorption spectra of the investigated samples. IR LIBS was also applied to determine the limit of detection (LOD) for the perchlorate anion in KClO4 using the 8.0 -11.0 mum IR-LIBS emission band. The calibration curve of ClO4 in KClO4 was constructed using peak and integrated emission intensities for known concentrations of mixed KClO4/NH4NO3 samples. The limit of detection for ClO4, was determined to be 14.7 +/- 0.5 wt%/wt for the given experimental conditions. In the second part of this research, the temperature-dependent absorption and emission properties of Tm doped KPb2Cl5 (KPC) and KPb2Br5 (KPB) were evaluated for applications in laser cooling. A Tm doped Y3Al5O12 (YAG) crystal was also included for comparative studies. Under laser pumping, all crystals exhibited broad IR fluorescence at room temperature with a mean fluorescence wavelength of ˜1.82 mum and bandwidth of 0.14 mum (FWHM) for Tm:KPC/KPB and ˜1.79 mum for Tm:YAG. Initial experiments on laser-induced heating/cooling were performed using a combined IR imaging and fluorescence thermometry setup. Employing a continuous-wave laser operating at 1.907 mum, Tm: KPC and Tm: KPB crystals revealed a very small heat load resulting in temperature increase of ˜ 0.3 ( +/- 0.1)°C. The heat loading in Tm:YAG was signicantly larger and resulted in a temperature increase of ˜0.9 (+/-0.1)°C. The results derived from IR imaging were also conrmed by the fluorescence thermometry experiments, which showed only minimal changes in the FIR intensity ratio of the green Er3+ fluorescence lines from Er:KPC.

Treatment of Melasma with the Photoacoustic Twin Pulse Mode of Low-Fluence 1,064 nm Q-Switched Nd:YAG Laser

PubMed Central

Kim, Jee Young; Choi, Misoo; Nam, Chan Hee; Kim, Ji Seok; Kim, Myung Hwa; Park, Byung Cheol

2016-01-01

Background Low-fluence 1,064 nm Q-switched Nd:YAG laser has been widely used for the treatment of melasma. Although new Q-switched Nd:YAG lasers with photoacoustic twin pulse (PTP) mode have been recently developed for high-efficiency, there is limited information available for the new technique. Objective This study was designed to investigate the efficacy and adverse effects after few sessions of repeated low fluence 1,064 nm Q-switched Nd:YAG laser treatment with PTP mode in Asian women with melasma. Methods Twenty-two Korean women were treated with a total of five sessions of low-fluence PTP mode Nd:YAG laser treatment (Pastelle®) at 2 weeks interval. Responses to treatments were evaluated by using Melasma Area and Severity Index (MASI) scoring, colorimeter measurement, and the investigators' and patients' overall assessments. Adverse events were recorded at each visit. Results Investigators' and patients' overall assessment showed that 'significantly improved' was assessed by 13 (59.1%) and 19 of 22 patients (86.4%), respectively. MASI scores were significantly reduced by 20.4%. The lightness, measured by using a colorimeter, was significantly increased by 1.3 point. Notable adverse events were not observed. Conclusion After 5 sessions of laser therapy alone, about 60% of the subjects showed significant improvement. Few sessions of repeated laser toning treatment using the PTP mode is a safe and effective way to treat facial melasma. PMID:27274626

Ultrastructural properties of laser-irradiated and heat-treated dentin.

PubMed

Rohanizadeh, R; LeGeros, R Z; Fan, D; Jean, A; Daculsi, G

1999-12-01

Previous studies using scanning electron microscopy and infrared absorption spectroscopy reported that laser irradiation causes compositional changes in enamel. The purpose of this study was to evaluate the ultrastructural and compositional changes in dentin caused by irradiation with a short-pulse laser (Q-switched Nd:YAG). The irradiated and non-irradiated areas of the lased dentin samples were investigated by scanning (SEM) and transmission electron microscopy (TEM), micro-micro electron diffraction, and electron microprobe analysis of dispersive energy (EDX). Heat-treated dentin was similarly investigated. This study demonstrated that laser irradiation resulted in the recrystallization of dentin apatite and in the formation of additional calcium phosphate phases consisting of magnesium-substituted beta-tricalcium phosphate, beta-TCMP, beta-(Ca,Mg)3(PO4)2, and tetracalcium phosphate, TetCP, Ca4(PO4)O. TEM analyses of the modified and unmodified zones of the irradiated areas showed two types of crystal populations: much larger crystals from the modified zone and crystals with size and morphology similar to those of dentin apatite in the unmodified zone. The morphology of crystals in the modified zones in the irradiated dentin resembled those of dentin sintered at 800 or 950 degrees C. In the irradiated areas (modified and unmodified zones), the Ca/P ratio was lower compared with that in the non-irradiated dentin. The Mg/Ca ratio in the modified zones was higher than that in the unmodified zones and in the non-irradiated dentin. In sintered dentin, the Mg/Ca ratio increased as a function of sintering temperature. The ultrastructural and compositional changes observed in laser-irradiated dentin may be attributed to high temperature and high pressure induced by microplasma during laser irradiation. These changes may alter the solubility of the irradiated dentin, making it less susceptible to acid dissolution or to the caries process.

Crystal growth, structural, optical, spectral and thermal studies of tris( L-phenylalanine) L-phenylalaninium nitrate: A new organic nonlinear optical material

NASA Astrophysics Data System (ADS)

Prakash, M.; Geetha, D.; Lydia Caroline, M.

2011-10-01

Tris( L-phenylalanine) L-phenylalaninium nitrate, C 9H 12NO 2+·NO 3-·3C 9H 11NO 2 (TPLPN), a new organic nonlinear optical material was grown from aqueous solution by slow evaporation solution growth at room temperature. The grown crystals were subjected to powder X-ray diffraction and single crystal X-ray diffraction studies to confirm the crystalline nature and crystal structure. The modes of vibration of different molecular groups present in TPLPN have been identified by FTIR spectral analysis. The presence of hydrogen and carbon in the grown crystal were confirmed by using proton and carbon nuclear magnetic resonance (NMR) spectral analyses. The optical transmission spectral study establishes good transmitting ability of the crystal in the entire visible region. The thermogravimetric (TG) and differential thermal analyses (DTA) were carried out to understand the thermal stability of the sample. The nonlinear optical property of the compound observed using Kurtz powder second harmonic generation test assets the suitability of the grown material for the frequency conversion of laser radiation of Nd:YAG.

Optical coatings on laser crystals for HiPER project

NASA Astrophysics Data System (ADS)

Oulehla, Jindrich; Pokorný, Pavel; Lazar, Josef

2011-12-01

In this contribution we present a technology for deposition of interference coatings for optical components designed to operate as active media in power pulsed lasers. The aim of the technology is to prepare crystals for lasers for the HiPER project (High Power laser Energy Research facility) which should demonstrate the feasibility of laser driven fusion as a future energy source. Diode pumped solid state lasers (DPSSL) are the most likely option for fusion ignition. The choice of the material for the lasers' active medium is critical. Some of the most important properties include the ability to be antireflection coated to reduce the energy losses and increase the overall efficiency. This contribution deals with some of the materials considered to be candidates for slabs serving as the active medium of the DPSSLs. We tested Yb:YAG and Yb:CaF2 samples. As large amounts of heat need to be dissipated during laser operation, cryogenic cooling is necessary. Appropriate coating materials and techniques need to be chosen. Therefore differences between available coating techniques are investigated in terms of adhesion, enduring of stress from temperature shocks, etc. Coated samples were placed into cryogenic environment in order to simulate conditions similar to those in real life operation. Optical microscopy was used for coating investigation after the conducted experiments.

AR coatings on laser crystals for HiPER project

NASA Astrophysics Data System (ADS)

Oulehla, Jindřich; Pokorný, Pavel

2010-08-01

In this contribution we present a technology for deposition of interference coatings for optical components designed to operate as active media in power pulsed lasers. The aim of the technology is to prepare crystals for lasers for the HiPER project (High Power laser Energy Research) which should demonstrate the feasibility of laser driven fusion as a future energy source. Diode pumped solid state lasers (DPSSL) are the most likely option for fusion ignition. The choice of material for the lasers active medium is critical. Some of the most important properties include the ability to be antireflection coated to reduce the energy losses and increase the overall efficiency. This contribution deals with some of the materials considered to be candidates for slabs serving as the active medium of the DPSSLs. We tested Yb:YAG, Yb:CaF2 samples. As large amounts of heat need to be dissipated during laser operation, cryogenic cooling is necessary. Appropriate coating materials and techniques need to be chosen. Therefore differences between available coating techniques are investigated in terms of adhesion, enduring of stress resulting from temperature shocks, etc. Coated samples were placed into cryogenic environment in order to simulate conditions similar to those in real life operation. Optical microscopy was used for coating investigation after the conducted experiments.

Growth and characterization of a new nonlinear optical organic crystal: 2,4,6-Trimethylacetanilide

NASA Astrophysics Data System (ADS)

Upadhyaya, V.; Prabhu, Sharada G.

2015-09-01

A new nonlinear optical organic material, 2,4,6-trimethylacetanilide (246TMAA), also known as N-[2,4,6- trimethylphenyl]acetamide, has been synthesized and grown as a single crystal by the slow evaporation technique by organic solvents. The grown crystals have been characterized by morphology study. The crystals are prismatic. Surface examination shows granular dendritic pattern in optical micrograph. The Scanning Electron Micrograph shows the layered growth of the crystal. The Differential Scanning Calorimeter plot shows no phase change until melting point (219°C). The density of the crystals is 1.1g/cc and the crystals are soft. The crystals are transparent in the visible region and in the ultra-violet region till 280 nm. 246TMAA crystallizes with 2 molecules in a monoclinic unit cell in the noncentrosymmetric point group m, space group Pn. Refractive indices of this optically biaxial crystal along the three crystallophysical axes have been measured at 633 nm. The optical second harmonic generation efficiency of the crystal at 1064 nm is about half that of the urea crystal, measured by powder method using Nd:YAG laser. The results show that the 246TMAA crystal can efficiently be used for up-conversion of infrared radiation into visible green light. The powder X-ray diffraction spectrum of the crystal has been obtained.

Solid state laser technology - A NASA perspective

NASA Technical Reports Server (NTRS)

Allario, F.

1985-01-01

NASA's program for developing solid-state laser technology and applying it to the Space Shuttle and Space Platform is discussed. Solid-state lasers are required to fulfill the Earth Observation System's requirements. The role of the Office of Aeronautics and Space Technology in developing a NASA tunable solid-state laser program is described. The major goals of the program involve developing a solid-state pump laser in the green, using AlGaAs array technology, pumping a Nd:YAG/SLAB crystal or glass, and fabricating a lidar system, with either a CO2 laser at 10.6 microns or a Nd:YAG laser at 1.06 microns, to measure tropospheric winds to an accuracy of + or - 1 m/s and a vertical resolution of 1 km. The procedures to be followed in order to visualize this technology plan include: (1) material development and characterization, (2) laser development, and (3) implementation of the lasers.

16.7 W 885 nm diode-side-pumped actively Q-switched Nd:YAG/YVO4 intracavity Raman laser at 1176 nm

NASA Astrophysics Data System (ADS)

Jiang, Pengbo; Zhang, Guizhong; Liu, Jian; Ding, Xin; Sheng, Quan; Yu, Xuanyi; Sun, Bing; Shi, Rui; Wu, Liang; Wang, Rui; Yao, Jianquan

2017-11-01

We proposed and experimentally demonstrated the generation of high-power 1176 nm Stokes wave by frequency shifting of a 885 nm diode-side-pumped Nd:YAG laser using a YVO4 crystal in a Z-shaped cavity configuration. Employing the 885 nm diode-side-pumped scheme and the Z-shaped cavity, for the first time to our knowledge, we realized the thermal management effectively, achieving excellent 1176 nm Stokes wave consequently. With an incident pump power of ~190.0 W, a maximum average output power of 16.7 W was obtained at the pulse repetition frequency of 10 kHz. The pulse duration and spectrum linewidth of the Stokes wave at the maximum output power were 20.3 ns and ~0.08 nm, respectively.

Influence of UV illumination on the cold temperature operation of a LiNbO(3) Q-switched Nd:YAG laser.

PubMed

Cole, Brian; Goldberg, Lew; King, Vernon; Leach, Jeff

2010-04-26

UV illumination of a lithium niobate Q-switch was demonstrated as an effective means to eliminate a loss in hold-off and associated prelasing that occurs under cold temperature operation of Q-switched lasers. This degradation occurs due to the pyroelectric effect, where an accumulation of charge on crystal faces results in a reduction in the Q-switch hold-off and a spatially variable loss of the Q-switch in its high-transmission state, both resulting in lowering of the maximum Q-switched pulse energy. With UV illumination, the resulting creation of photo-generated carriers was shown to be effective in eliminating both of these effects. A Q-switched Nd:YAG laser utilizing UV-illuminated LiNbO(3) was shown to operate under cold temperatures without prelasing or spatially variable loss.

YAG:Er3+, CaF2:Er3+, and Er2O3 Emission Spectra Under Laser and Laser Thermal Excitation

NASA Astrophysics Data System (ADS)

Marchenko, V. M.

2018-05-01

Experimental luminescence and selective-emission (SE) spectra of YAG:Er3+ (10 at.%) and CaF2:Er3+ (1 at.%) single crystals and Er2O3 polycrystal under laser and laser thermal excitation of the Er3+-ion multiplets are compared. Luminescence spectra under resonant excitation are determined by multiplet population relaxation with the corresponding radiative and nonradiative probabilities. The form of the SE spectra is determined by the thermal population of the multiplets and the probabilities of only radiative transitions. The SE band at 800 nm (4I9/2 → 4I15/2) is an indicator of high-temperature thermal emission of Er3+ ions. The absence of this band in luminescence spectra is explained by the short lifetime of the τ(4I9/2) level of 53 ns at T = 300 K.

Analysis of laser pumping and thermal effects based on element analysis

NASA Astrophysics Data System (ADS)

Cui, Li; Liu, Zhijia; Zhang, Yizhuo; Han, Juan

2018-03-01

Thermal effect is a plateau that limits the output of high-power, high beam quality laser, and thermal effects become worse with the increase of pump power. We can reduce the effects caused by thermal effects from pumping, laser medium shape, cooling method and other aspects. In this article, by using finite element analysis software, the thermal effects between Nd:Glass and Nd:YAG laser crystal was analyzed and compared. The causes of generation for thermal effects, and factors that influence the distribution in laser medium were analyzed, including the light source, the laser medium shape and the working mode. Nd:Glass is more suitable for low repetition frequency, high energy pulsed laser output, due to its large size, line width and so on, and Nd:YAG is more suitable for continue or high repetition rate laser output, due to its higher thermal conductivity.

25  W/m² collection efficiency solar-pumped Nd:YAG laser by a heliostat-parabolic mirror system.

PubMed

Liang, D; Almeida, J; Vistas, C R

2016-09-20

A large aspheric fused silica lens was used to couple efficiently the concentrated solar radiation from the focal zone of a 1.5-m-diameter primary concentrator into a 4-mm-diameter, 35-mm-long Nd:YAG single-crystal rod within a conical pump cavity. Continuous-wave laser power of 29.3 W was measured, attaining 25.0  W/m² solar laser collection efficiency, corresponding to a 19% increase over the previous record. Its laser beam figure of merit-the ratio between laser power and the product of Mx2, My2 beam quality factors-of 0.01 W is 1.6 times higher than that of a direct tracking solar laser with 30  W/m² collection efficiency. A strong dependency of solar laser power on laser resonator cavity length was found.

A Cr4+:YAG passively Q-switched Nd:YVO4 microchip laser for controllable high-order Hermite-Gaussian modes

NASA Astrophysics Data System (ADS)

Dong, Jun; He, Yu; Bai, Sheng-Chuang; Ueda, Ken-ichi; Kaminskii, Alexander A.

2016-09-01

A nanosecond, high peak power, passively Q-switched laser for controllable Hermite-Gaussian (HG) modes has been achieved by manipulating the saturated inversion population inside the gain medium. The stable HG modes are generated in a Cr4+:YAG passively Q-switched Nd:YVO4 microchip laser by applying a tilted pump beam. The asymmetrical saturated inversion population distribution inside the Nd:YVO4 crystal for desirable HG modes is manipulated by choosing the proper pump beam diameter and varying pump power. A HG9,8 mode passively Q-switched Nd:YVO4 microchip laser with average output power of 265 mW has been obtained. Laser pulses with a pulse width of 7.3 ns and peak power of over 1.7 kW working at 21 kHz have been generated in the passively Q-switched Nd:YVO4 microchip laser.

Stress-induced waveguides in Nd:YAG by simultaneous double-beam irradiation with femtosecond pulses

NASA Astrophysics Data System (ADS)

Castillo, Gabriel R.; Romero, Carolina; Lifante, Ginés; Jaque, Daniel; Chen, Feng; Varela, Óscar; García-García, Enrique; Méndez, Cruz; Camacho-López, Santiago; Vázquez de Aldana, Javier R.

2016-01-01

We report on the fabrication of stress-induced waveguides in Nd:YAG (neodymium doped yttrium aluminum garnet, Nd:Y3Al5O12) by simultaneous double-beam irradiation with femtosecond laser pulses. An interferometer was used to generate two femtosecond laser beams that, focused with certain lateral separation inside the crystal, produced two parallel damage tracks with a single scan. The propagation of the mechanical waves simultaneously created in both focal spots produced a highly symmetrical stress field that is clearly revealed in micro-luminescence maps. The optical properties of the double-beam waveguides are studied and compared to those of single-beam irradiation, showing relevant differences. The creation of more symmetric stress patterns and a slight reduction of propagation losses are explained in terms of the fact that simultaneous inscription allows for a drastic reduction in the magnitude of "incubation" effects related to the existence of pre-damaged states.

High Temperature Mechanical Behavior of MgAl2O4-YAG Eutectic Ceramic In Situ Composites by Float Zone Method

NASA Astrophysics Data System (ADS)

Abalı, Serkan

2017-09-01

The directionally solidified eutectic MgAl2O4-Y3Al5O12 crystal was prepared at a pressure of 0.4 MPa of ambient nitrogen gas by the high frequency induction heated floating zone furnace. In order to determine the high temperature characteristics, directionally solidified MgAl2O4-Y3Al5O12 eutectic phase has been analyzed with creep test, tensile strength, young modulus and fracture toughness at the various temperatures and the microstructural variations have been studied according to the analysis results. It has been seen that directionally solidified with zone melting MgAl2O4-YAG eutectic ceramic which has given the value of 168 MPa below 10-6/s strain rate at 1,700 °C temperature has revealed minimum stress.

Power amplification for petawatt Ti: Sapphire lasers: New strategies for high fluence pumping

NASA Astrophysics Data System (ADS)

Canova, F.; Chambaret, J.-P.

2006-06-01

One of the major bottlenecks when we pump large Ti:Sapphire crystals, to reach Petawatt level laser amplification, is the careful control of the spatial energy distribution of Nd:Glass pump lasers. Commercially available nanosecond Nd:Glass and Nd:YAG lasers exhibit poor spatial profile quality especially in the near and in the intermediate field, which can lead to local hot spots, responsible of damages in crystals, and parasitic transverse lasing enhancement, strongly dependent on the profile of the pump beam . For these reasons, it is mandatory to keep the pump beam intensity profile as flat as possible on the pumped crystal. To guarantee the best pumping conditions we are investigating the combined use of DOE (diffractive optical elements) and optical smoothing techniques. In parallel we are starting a study on laser induced damages mechanisms in crystal. With DOE and microlens arrays we plan to guarantee to the beam a supergaussian shape. Simulation and first experiments with both optical systems show that a flat top spatial profile with less than 10% fluctuations and a 8th order supergaussian is possible with the present technology.Optical smoothing will keep the beam free of hot spots. We especially focused on the smoothing techniques involving optical fibers. This is the first time to our knowledge that this technique is applied to the pumping beams for Ti:Sapphire systems. A deep study of laser-crystal interaction will allow us to fully understand the damages created by hot spots. The knowledge of the phenomena involved in laser damages on Ti:Sapphire is mandatory to control the pumping processes and thresholds. In conclusion, mixing the advantages of these different approaches to overcome this bottleneck will allow us to amplify in a safety way femtosecond laser beams to the Petawatt level using Ti:Sapphire crystals.

Phase separation, crystallization and polyamorphism in the Y2O3 Al2O3 system

NASA Astrophysics Data System (ADS)

Skinner, Lawrie B.; Barnes, Adrian C.; Salmon, Philip S.; Crichton, Wilson A.

2008-05-01

A detailed study of glass formation from aerodynamically levitated liquids in the (Y2O3)x(Al2O3)1-x system for the composition range 0.21<=x<=0.41 was undertaken by using pyrometric, optical imaging and x-ray diffraction methods. Homogeneous and clear single-phase glasses were produced over the composition range 0.27 \\lesssim x \\lesssim 0.33 . For Y2O3-rich compositions (0.33 \\lesssim x \\le 0.375 ), cloudy materials were produced which contain inclusions of crystalline yttrium aluminium garnet (YAG) of diameter up to 40 µm in a glassy matrix. For Y2O3-poor compositions around x = 0.24, cloudy materials were also produced, but it was not possible to deduce whether this resulted from (i) sub-micron inclusions of a nano-crystalline or glassy material in a glassy matrix or (ii) a glass formed by spinodal decomposition. For x = 0.21, however, the sample cloudiness results from crystallization into at least two phases comprising yttrium aluminium perovskite and alumina. The associated pyrometric cooling curve shows slow recalescence events with a continuous and slow evolution of excess heat which contrasts with the sharp recalescence events observed for the crystallization of YAG at compositions near x = 0.375. The materials that are the most likely candidates for demonstrating homogeneous nucleation of a second liquid phase occur around x = 0.25, which corresponds to the limit for formation of a continuous random network of corner-shared AlO4 tetrahedra.

Rare earth activated yttrium aluminate phosphors with modulated luminescence.

PubMed

Muresan, L E; Popovici, E J; Perhaita, I; Indrea, E; Oro, J; Casan Pastor, N

2016-06-01

Yttrium aluminate (Y3 A5 O12 ) was doped with different rare earth ions (i.e. Gd(3+) , Ce(3+) , Eu(3+) and/or Tb(3+) ) in order to obtain phosphors (YAG:RE) with general formula,Y3-x-a Gdx REa Al5 O12 (x = 0; 1.485; 2.97 and a = 0.03). The synthesis of the phosphor samples was done using the simultaneous addition of reagents technique. This study reveals new aspects regarding the influence of different activator ions on the morpho-structural and luminescent characteristics of garnet type phosphor. All YAG:RE phosphors are well crystallized powders containing a cubic-Y3 Al5 O12 phase as major component along with monoclinic-Y4 Al2 O9 and orthorhombic-YAlO3 phases as the impurity. The crystallites dimensions of YAG:RE phosphors vary between 38 nm and 88 nm, while the unit cell slowly increase as the ionic radius of the activator increases. Under UV excitation, YAG:Ce exhibits yellow emission due to electron transition in Ce(3+) from the 5d level to the ground state levels ((2) F5/2 , (2) F7/2 ). The emission intensity of Ce(3+) is enhanced in the presence of the Tb(3+) ions and is decreased in the presence of Eu(3+) ions due to some radiative or non-radiative processes that take place between activator ions. By varying the rare earth ions, the emission colour can be modulated from green to white and red. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Quenching And Luminescence Efficiency Of Nd3+ In YAG

NASA Astrophysics Data System (ADS)

Lupei, Voicu; Lupei, Aurelia; Georgescu, Serban; Ionescu, Christian I.; Yen, William M.

1989-05-01

The effect of the concentration luminescence quenching of the 4F 3/2, level of Nd3+ in YAG on the relative efficiency is presented. Based on the analysis of the decay curves in terms of the energy transfer theory, an analytical expression for the relative luminescence efficiency is obtained. In the low concentration range (up to q,1.5 at % Nd3+), the efficiency linearly decreases when Nd3+ concentration increases. It is also stressed that pairs quenching contribute about 20 % to the nonradiative energy transfer losses. Quantum efficiency of luminescence is an important parameter for the characterization of laser active media; its lowering is due to either multiphonon relaxation or energy transfer processes. The multiphonon non-radiative probability depends on the energy gap between levels, on the phonon energy and temperature; usually at low activator doping it is practically independent on concentration. On the other hand, energy transfer losses show a marked dependence on activator concentration, a fact that severely limits the range of useful con-centration of active centers in some laser crystals. In the YAG:Nd case the minimum energy gap between the Stark components of the 4F,I.) and the next lower level 4F15/2 is of about 4700 cm-1. Since in YAG tree phonons most effdbtively coupled to the Rare pi.th ions have an energy of 1, 700 cm-1, the probability for multiphonon relaxation from the 'F3/, level, even at room temperature, is very low and therefore for low Nd 3+ concentrations quantum efficiency is expected to be close to 1.

Mid-IR lasers based on transition metal and rare-earth ion doped crystals

NASA Astrophysics Data System (ADS)

Mirov, S.; Fedorov, V.; Martyshkin, D.; Moskalev, I.; Mirov, M.; Vasilyev, S.

2015-05-01

We report a novel design of CW Cr2+:ZnS/ZnSe laser systems and demonstrate record output powers of 27.5 W at 2.45 μm and 13.9 W at 2.94 μm with slope efficiencies of 63.7% and 37.4%, respectively. Power scaling of ultra-fast Cr2+:ZnS/ZnSe Kerr mode-locked lasers beyond 2 W level, as well as the shortest pulse duration of 29 fs, are also reported. New development of Fe:ZnSe laser with average output power > 35 W at 4.1 μm output wavelength and 100 Hz pulse repetition rate (PRR) was achieved in a nonselective cavity. With intracavity prim selector, wavelength tunability of 3.88-4.17 μm was obtained with maximum average output power of 23 W. We also report new results on Tm-fiber pumped passively and actively Q-switched Ho:YAG laser systems. High peak power actively Q-switched Ho:YAG laser demonstrates stable operation with pulse energy > 50 mJ, 12 ns pulse duration, and 100-1000 Hz PRR which correspondents to more than 4 MW peak power. The actively Q-switched Ho:YAG laser system optimized for high repetition rate delivers 40 W average output power at 10-100 kHz PRR. The Ho:YAG laser with passive Q-switcher demonstrates constant 5 mJ output energy from 200 Hz to 2.23 kHz PRR with optical slope efficiency with respect to Tm-fiber laser of ~43%.

Treatment of pigmented keratosis pilaris in Asian patients with a novel Q-switched Nd:YAG laser.

PubMed

Kim, Sangeun

2011-06-01

Treatment for most cases of keratosis pilaris requires simple reassurance and general skin care recommendations. Many Asian patients find lesions due to pigmented keratosis pilaris to be cosmetically unappealing. Treatment of post-inflammatory hyperpigmentation using a 1064-nm Q-switched Nd:YAG laser with low fluence is reported. To investigate the efficacy of a novel Q-switched Nd:YAG laser for the treatment of pigmented keratosis pilaris in Asian patients. Ten patients with pigmented keratosis pilaris underwent five weekly treatments using a Q-switched Nd:YAG laser (RevLite(®); HOYA ConBio(®), Freemont, CA, USA) at 1064 nm with a 6-mm spot size and a fluence of 5.9 J/cm(2). Photographic documentation was obtained at baseline and 2 months after the final treatment. Clinical improvement was achieved in all 10 patients with minimal adverse effects. For the treatment of keratosis pilaris, the use of a Q-switched Nd:YAG laser can be helpful for improving cosmetic appearance as it can improve pigmentation.

Thermal Mechanical Stability of Single-Crystal-Oxide Refractive Concentrators Evaluated for High-Temperature Solar-Thermal Propulsion

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.; Jacobson, Nathan S.; Miller, Robert A.

1999-01-01

Recently, refractive secondary solar concentrator systems were developed for solar thermal power and propulsion (ref. 1). Single-crystal oxides-such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium aluminum garnet (Y3Al5O12, or YAG), magnesium oxide (MgO), and sapphire (Al2O3)-are candidate refractive secondary concentrator materials. However, the refractive concentrator system will experience high-temperature thermal cycling in the solar thermal engine during the sun/shade transition of a space mission. The thermal mechanical reliability of these components in severe thermal environments is of great concern. Simulated mission tests are important for evaluating these candidate oxide materials under a variety of transient and steady-state heat flux conditions. In this research at the NASA Lewis Research Center, a controlled heat flux test approach was developed for investigating the thermal mechanical stability of the candidate oxide. This approach used a 3.0-kW continuous-wave (wavelength, 10.6 mm) carbon dioxide (CO2) laser (ref. 2). The CO2 laser is especially well-suited for single-crystal thermal shock tests because it can directly deliver well-characterized heat energy to the oxide surfaces. Since the oxides are opaque at the 10.6-mm wavelength of the laser beam, the light energy is absorbed at the surfaces rather than transmitting into the crystals, and thus generates the required temperature gradients within the specimens. The following figure is a schematic diagram of the test rig.

Non linear optical studies on semiorganic single crystal: L-arginine 4-nitrophenalate 4-nitrophenol dihydrate (LAPP)

NASA Astrophysics Data System (ADS)

Mahadevan, M.; Sankar, P. K.; Vinitha, G.; Arivanandhan, M.; Ramachandran, K.; Anandan, P.

2017-07-01

L-arginine 4-nitrophenalate 4-nitrophenol dihydrate (LAPP) has been synthesized and grown by solution growth at room temperature using deionized water as a solvent. The various functional groups of the sample were identified by Fourier transform infra-red and Fourier transforms - Raman spectroscopic analyses. The Laser damage threshold of LAPP has been studied. Refractive index of LAPP single crystal was measured using Metricon prism coupler Instrument. The etching studies were carried out to study the quality of the grown crystals. The third order nonlinear optical properties of LAPP sample was analyzed by the Z-scan technique using 532 nm diode pumped CW Nd: YAG laser. The LAPP material exhibits negative optical nonlinearity. The results show that LAPP sample has potential applications in nonlinear optics and it can be exploited for optical limiting or switching.

Comparative Evaluation of Effects of Laser Modalities on Shear Bond Strengths of Veneering Porcelains to Laser Sintered Substructures: An In Vitro Study.

PubMed

Gorler, Oguzhan; Saygin, Aysegul Goze

2017-06-01

Laser modalities and direct metal laser sintering (DMLS) have a potential to enhance micromechanical bonding between dental super- and infrastructures. However, the effect of different manufacturing methods on the metal-ceramic bond strength needs further evaluation. We investigated the effect of surface treatment with Er:YAG, Nd:YAG, and Ho:YAG lasers on the shear bond strength (SBS) of high-fusion dental porcelains (Vita and G-Ceram) to infrastructures prepared with DMLS in vitro settings. Study specimens (n = 128) were randomly divided into study subsets (n = 8), considering treatment types applied on the surface of infrastructures, including sandblasting and selected laser modalities; infrastructure types as direct laser sintered (DLS) and Ni-Cr based; and superstructure porcelains as Vita and G-Ceram. The SBS test was performed to assess the effectiveness of surface modifications that were also examined with a stereo microscope. Considering laser procedure types, the highest SBS values were obtained by Er:YAG laser, followed by, with a decreasing efficiency, Ho:YAG laser and sandblasting procedures, and Nd:YAG laser procedure (p < 0.05). Nd:YAG laser decreases the bonding of Vita and G-Ceram in all the infrastructures compared with sandblasting. Considering porcelains, the highest SBS values were obtained by Vita (p < 0.05). Considering infrastructures, the highest SBS values were obtained by DMLS procedure (p < 0.05). The laser procedures caused surface irregularities as revealed by the stereo microscopic examination. In current experimental settings, Er:YAG laser applied to DLS infrastructure veneered with Vita porcelain increases bonding strength more distinctly, and Nd:YAG laser applied to Ni-Cr-based infrastructure veneered with G-Ceram porcelain alters bonding strength unfavorably.

Room temperature operation of 2.67 mJ pulse LD end pumped Q-switched Tm:YAG laser

NASA Astrophysics Data System (ADS)

Song, Xuedi; Wu, Chunting; Chen, Xinyu; Yu, Kai; Jin, Guangyong

2014-12-01

Due to 2 μm band in the absorption of water and CO2, the diode pumped solid state lasers with wavelength around 2 μm have important applications in laser medicine and remote sensing, such as it can be used as a scalpe or a light source of Coherent Doppler Wind Lidar and Differential Absorption Lidar. In the recently years, scientists have done much work on the development of such lasers. There're many reports on continuous Tm:YAG laser. However, the study on Q-switched Tm:YAG laser, which is more useful in applications, was very rare. As the light source of Coherent Doppler Wind Lidar, large energy and wide pulse width is desired. Current reports mostly adopted CW pumped source, but it would make a mount of heat. Pulse pumping method could reduce the heat accumulation and improve the heat stability of the laser. How to improve the single pulse energy was the focus of current study. In this paper, a single end bonding Tm:YAG crystal with Tm3+ doping concentration of 3.5at.% was used. Acousto-optic (AO) Q-switched (GOOCH and HOUSEGO QS041-10M-HI8) operation was adopted in our experiment. In the repetition frequency of 100Hz, a maximum single energy of 2.67 mJ (measured by Ophir 30A-BB) and the narrowest pulse width of 149 ns (measured by Vigo PCI-3TE-12 detector) were achieved at room temperature. The M2x was 1.31 and the M2y was 1.35 (measured by Spiricon Pyrocam-III). Tm:YAG laser was developed by using a pulse diode pumped L shape resonant cavity. The transmittance of the curve output mirror was 4% and the curvature radius of which was 300 mm. The output center wavelength of the laser was measured to be 2013.5 nm (measured by YOKOGAWA AQ6375).

Er:YAG Laser Versus Cold Knife Excision in the Treatment of Nondysplastic Oral Lesions: A Randomized Comparative Study for the Postoperative Period.

PubMed

Broccoletti, Roberto; Cafaro, Adriana; Gambino, Alessio; Romagnoli, Ercole; Arduino, Paolo Giacomo

2015-12-01

The aim of this prospective study was to estimate the effects of Erbium substituted: Yttrium Aluminium Garnet (Er:YAG) laser, compared with traditional scalpel, on the early postoperative sequelae of nondysplastic oral lesion removal. There is limited evidence that laser surgery could exhibit advantages over scalpel in oral mucosal surgery. The investigators studied a cohort of 344 patients; 394 lesions were randomized and treated. Outcome statistically evaluated variables were: age, gender, the site and size of investigated lesions, visual analogue score (VAS) of pain, the Oral Health Impact Profile questionnaire (OHIP-14) and the Quality of Life test (QOL), and number of analgesics taken in the 1st week after surgery. Significant differences were found if considering the surgical time, VAS, and QOL and OHIP-14 questionnaires; regarding those data, the Er:YAG laser appeared to be faster and less painful than traditional scalpel (p < 0.05). For bigger lesions, patients statistically took more painkillers if they had undergone traditional surgery. Considering the site of the treated lesions, Er:YAG laser was less painful, especially in the gingiva and palate (p < 0.05). This is the first randomized controlled surgical trial reported for the management of nondysplastic oral lesions with the use of an Er:YAG laser. With many limitations, the present report identifies significant difference in the immediate postoperative surgical period between the two treatments, meaning that the Er:YAG laser seemed to be less painful, and better accepted by patients, than traditional scalpel.

An in vitro investigation of the temperature rises produced in dentine by Nd:YAG laser light with and without water cooling.

PubMed

Gow, A M; McDonald, A V; Pearson, G J; Setchell, D J

1999-01-01

Infrared lasers are reported to have thermal side effects which may damage pulp tissue. This study investigated the thermal effects of the pulsed Nd:YAG laser. Prepared, extracted teeth were measured prior to irradiation. Temperature was recorded using a thermocouple/data logging system. Laser irradiation was carried out with or without water spray for an exposure time of ten seconds. Results indicated that dry irradiation produced unacceptable temperature rises with dentine thicknesses used. Wet irradiation produced a significantly lower temperature rise. It was concluded that the Nd:YAG laser produced thermal effects which could potentially cause pulpal trauma. A water coolant was effective in reducing these thermal effects, but the temperature rise achieved whilst using water coolant may still cause pulpal damage.

Diamond Raman laser emitting at 1194, 1419, and 597 nm

NASA Astrophysics Data System (ADS)

Pashinin, V. P.; Ralchenko, V. G.; Bolshakov, A. P.; Ashkinazi, E. E.; Konov, V. I.

2018-03-01

A Raman laser based on a synthetic diamond crystal pumped by nanosecond pulses of a 1030-nm Yb : YAG laser and emitting in the IR region at the first and second Stokes wavelengths of 1194 and 1419 nm, respectively, was developed. The conversion efficiency was 34% with a slope efficiency of 50% and an average power of 1.1 W at a wavelength of 1194 nm; the average power at 1419 nm was 0.52 W. Frequency doubling of the first Stokes component in a nonlinear BBO crystal resulted in orange (597.3 nm) radiation with a pulse energy of 0.15 mJ, an average power of 0.22 W, and a maximum efficiency of 20%.

Blackbody absorption efficiencies for six lamp pumped Nd laser materials

NASA Technical Reports Server (NTRS)

Cross, Patricia L.; Barnes, Norman P.; Skolaut, Milton W., Jr.; Storm, Mark E.

1990-01-01

Utilizing high resolution spectra, the absorption efficiencies for six Nd laser materials were calculated as functions of the effective blackbody temperature of the lamp and laser crystal size. The six materials were Nd:YAG, Nd:YLF, Nd:Q-98 Glass, Nd:YVO4, Nd:BEL, and Nd:Cr:GSGG. Under the guidelines of this study, Nd:Cr:GSGG's absorption efficiency is twice the absorption efficiency of any of the other laser materials.

Power Systems and Energy Storage Modeling for Directed Energy Weapons

DTIC Science & Technology

2014-06-01

neodymium or ytterbium doped yttrium aluminum garnet (YAG) crystal.6 The Maritime Laser Demonstration (MLD) features several 15 kW slab lasers combined...The laser substrate is similar to a fiber optic cable that is doped with a rare earth element (typically neodymium or ytterbium); many fibers can be...but with different elements. A typical construction consists of a sheet of Lithium- cobalt -oxide and a sheet of carbon separated by an insulator

Antireflective surface structures on optics for high energy lasers

NASA Astrophysics Data System (ADS)

Busse, Lynda E.; Florea, Catalin M.; Shaw, L. Brandon; Frantz, Jesse; Bayya, Shyam; Poutous, Menelaos K.; Joshi, Rajendra; Aggarwal, Ishwar D.; Sanghera, Jas S.

2014-02-01

We report results for antireflective surface structures (ARSS) fabricated directly into the surface of optics and lenses which are important as high energy (multi-kW) laser components, including fused silica windows and lenses, YAG crystals and ceramics and spinel ceramics. Very low reflection losses as well as high laser damage thresholds have been measured for optics with ARSS. Progress to scale up the process for large size windows will also be presented..

Experimental investigations of the use of an erbium:YAG laser on temporomandibular joint (TMJ) structures: first experimental results

NASA Astrophysics Data System (ADS)

Nuebler-Moritz, Michael; Niederdellmann, Herbert; Hering, Peter; Deuerling, Christian; Dammer, Ralf; Behr, M.

1995-04-01

The following paper introduces the results of an interdisciplinary research project. With the aid of photomacroscopic examination, light and scanning electron microscope investigations, changes to temporomandibular joint structures were detected in vitro after irradiation with an Erbium:YAG laser system. The solid-state Erbium:YAG laser, operating at a wavelength of 2.94 micrometers was used in the normal- spiking mode. The free-running laser beam was focussed onto freshly excised porcine tissue samples using a 108-mm sapphire lens. In this study the output was generally pulsed at a repetition rate of 4 Hz, with a pulse duration varying from 120 microsecond(s) to 500 microsecond(s) . Between 50 mJ and 500 mJ per pulse were applied to create pinpoint lesions. The optimum average energy density and pulse duration of the Erbium:YAG laser radiation for the purpose of TMJ-surgery (as far as it concerns meniscus and articulating facets) - which means efficient etch rate and minimal adjacent injury - seems to be about 24-42 J/cm2 and 120 microsecond(s) -240 microsecond(s) , respectively.

Growth and characterizaion of urea p-nitrophenol crystal: an organic nonlinear optical material for optoelectronic device application

NASA Astrophysics Data System (ADS)

Suresh, A.; Manikandan, N.; Jauhar, RO. MU.; Murugakoothan, P.; Vinitha, G.

2018-06-01

Urea p-nitrophenol, an organic nonlinear optical crystal was synthesized and grown adopting slow evaporation and seed rotation method. Single crystal X-ray diffraction study confirmed the formation of the desired crystal. High resolution X-ray diffraction study showed the defect nature of the crystal. The presence of functional groups in the material was confirmed by FTIR analysis. UV-Vis-NIR study indicates that the grown crystal has a wider transparency region with the lower cutoff wavelength at 423 nm. The grown crystal is thermally stable up to 120 °C as assessed by TG-DTA analysis. The optical homogeneity of the grown crystal was confirmed by birefringence study. The 1064 nm Nd-YAG laser was used to obtain laser induced surface damage threshold which was found to be 0.38, 0.25 and 0.33 GW/cm2 for (0 1 0), (1 1 - 1) and (0 1 1) planes, respectively. The dielectric study was performed to find the charge distribution inside the crystal. The hardness property of the titular material has been found using Vicker's microhardness study. The optical nonlinearity obtained from third order nonlinear optical measurements carried out using Z-scan technique showed that these samples could be exploited for optical limiting studies.

High efficient bone ablation with diode pumped Erbium and Thulium lasers including different delivery fibers: a comparative in vitro study

NASA Astrophysics Data System (ADS)

Stock, Karl; Hausladen, Florian; Stegmayer, Thomas; Wurm, Holger

2018-02-01

Er:YAG lasers (3μm) allow efficient bone ablation caused by the strong absorption in water. Unfortunately, there are only a few and comparable expensive fiber materials for this wavelength available which are suitable for high laser power. The bone ablation efficiency of the Tm:YAG laser is minor (2μm) but inexpensive silica fibers can be used. The aim of this study was to investigate the bone ablation, using novel diode pumped high power Er:YAG (laser power 40W) and Tm:YAG laser system (60W) and adaptive fiber delivery systems. Expected advantage of these lasers is the longer lifetime of the fibers because of the high repetition rate and low pulse energy compared to the flash lamp pumped laser systems. The bare fiber output ends of a sapphire fiber (Er:YAG laser) and of a silica fiber (Tm:YAG laser) were attached under water and a water filled container including the fixed sample (bovine bone slices) was moved by a computer controlled translation stage. In a second set-up we provided a focusing unit and appropriate water spray unit. The generated cut kerfs were analyzed by light microcopy and laser scanning microscopy. The results show that with the diode pumped Er:YAG laser and sapphire fiber a particular high efficient bone ablation (> 0.16mm2/J) is possible both with bare fiber under water and focusing unit with water spray. The higher power of the Tm:YAG laser also results in high ablation rates but causes enlarged thermal damages. In conclusion, this study demonstrates that efficient bone ablation is possible with both diode pumped laser systems. In terms of efficiency the Er:YAG laser is outstanding. The Tm:YAG laser also allows fast bone ablation, provided that the thermal impact is limited by effective cooling and high movement velocity of the laser spot, for example by using an automatic scanner.

Comparative morphological investigation on the rabbit's auricle after exposure to CO2- and Nd:YAG-laser radiation.

PubMed

Wandhöfer, A; Bally, G; Kauffmann, G; Karduck, A

1977-10-31

By comparing the effects of CO2- and Nd:YAG-laser radiation (mainly differing in wave-length by a factor of 10), a surgical instrument suitable for Otorhinolaryngology had to be found. The studies were performed on the rabbit's auricle in order to examine the effect of the laser irradiation mainly on the cartilage. The CO2-laser was found to be more efficient in cutting and caused less extended tissue damage than the Nd:YAG-laser. The latter seems to be more suitable for soft tissue surgery.

Quantification of holmium:YAG optical tip degradation

NASA Astrophysics Data System (ADS)

Mues, Adam C.; Teichman, Joel M. H.; Knudsen, Bodo E.

2009-02-01

The holmium:yttrium aluminum garnet (YAG) laser is the gold standard laser for intracorporeal lithotripsy. Optical fibers are utilized to transmit laser energy to the surface of a stone for fragmentation. During lithotripsy, fiber tip degradation (burn back) can occur. The exact mechanism for tip degradation and related factors are not completely understood, and have not been investigated. This characteristic is important because fiber burn back may affect diminish fragmentation efficiency, increase operative time, and increase cost due to the need for fiber replacement. We hypothesize that fiber tip degradation (burn back) varies amongst different commercially available holmium:YAG laser fibers.

Erbium:YAG laser contouring of the nasal dorsum: a preliminary investigation

NASA Astrophysics Data System (ADS)

Truong, Mai T.; Majaron, Boris; Pandoh, Nidhi S.; Wong, Brian J.

2001-05-01

In conventional aesthetic rhinoplasty operations, manual or powered rasps are used to reduce the osseo-cartilagenous nasal dorsum. This tactile method requires palpation of the instrument and the dorsum during surgery to estimate the degree of volume reduction, and often requires forceful manipulation of the dorsum which may illicit pain during surgery and contribute to post-operative edema and echymosis. In this preliminary study, we investigated the use of the Erbium:YAG laser ((lambda) equals294 micrometers ) to reduce bone and cartilage using ex-vivo porcine nasal dorsum and human cadaveric tissues. The short pulsed length and high absorption of this laser in biologic tissues results in minimization of thermal injury which are ideal for non- contact optical contouring of osseous and cartilagenous tissues in the face. Two Erbium:YAG lasers were used to ablate fresh porcine nasal bone and compared for their use. One Erbium:YAG laser, the Fidelis Laser, Fontana Medical Lasers, Ljubljana, Slovenija with variable pulse repetition rates (2 to 50 Hz), pulse energy (80 to 1000 mJ), and pulse duration (100, 300, 750 and 1000 microsecond(s) ) was used and compared to the Ultrafine Erbium:YAG laser, Coherent Inc., Santa Clara California, with variable pulse repetition rate (2 to 10 Hz), pulse energy (2-16 J/cm2), and spot diameter (2-6 mm). Only laser parameters approximating the conditions for thermal confinement were evaluated.

Solid-state synthesis of YAG powders through microwave coupling of oxide/carbon particulate mixtures

DOE PAGES

Wildfire, Christina; Sabolsky, Edward M.; Spencer, Michael J.; ...

2017-06-14

The rapid synthesis of yttrium aluminum garnet (Y 3Al 15O 12, YAG) powder was investigated through the use of microwave irradiation of the oxide precursor system. For this investigation, an external hybrid heating source was not used. Instead, the rapid heating of the precursor materials (yttria and alumina powders, which are typically transparent to 2.45 GHz microwaves) was initiated by mixing an intrinsic absorbing material (carbon) into the original oxide precursors. The effect of the carbon characteristics, such as carbon source, concentration, particle size, and agglomerate microstructure were evaluated on the efficiency of coupling and resultant oxide reaction. The microwavemore » power was varied to optimize the YAG conversion and eliminate intermediate phase formation. Interactions between the conductive carbon particles and the dielectric oxides within the microwave exposure produced local arching and micro-plasma formation within the powder bed, resulting in the rapid formation of the refractory YAG composition. This optimal conduction led to temperatures of 1000°C that could be achieved in less than 5 min resulting in the formation of > 90 vol% YAG. The understanding of a conductor/dielectric particulate system here, provided insight into possible application of similar systems where microwave irradiation could be used for enhanced solid-state formation, local melting events, and gas phase reactions with a composite powder media.« less

Power scaling of diode-pumped neodymium yttrium aluminum borate laser

NASA Technical Reports Server (NTRS)

Hemmati, Hamid

1991-01-01

Preliminary results are presented of the efficient diode-pumped operation of a neodymium yttrium aluminum borate (NYAB) laser at 531.5 nm using two 1-W diode-laser arrays for the pump. With 1380 mW of CW power incident on the crystal, as much as 51 mW of 532.5-nm laser radiation was obtained with the unoptimized cavity. The corresponding optical-to-optical conversion efficiency was 3.7 percent. A plot of the output 531.5 nm vs incident 807 nm pump power is shown. The crystal output power was critically dependent on the rotational and translational adjustment of the NYAB crystal inside the cavity. It is suggested that a crystal cut at the exact phase matching angle, placed in a cavity with proper optimal reflection and transmission mirror coatings, and pumped at proper wavelength can result in higher output power. Thus, the NYAB output power approaches that of a CW intracavity frequency doubled Nd:YAG laser.

Plate-shaped Yb:LuPO4 crystal for efficient CW and passively Q-switched microchip lasers

NASA Astrophysics Data System (ADS)

Liu, Junhai; Wang, Lisha; Han, Wenjuan; Xu, Honghao; Zhong, Degao; Teng, Bing

2016-10-01

It is demonstrated that plate-shaped crystals of Yb:LuPO4, which are grown from spontaneous nucleation by high-temperature solution method, can be utilized to make microchip lasers operating in continuous-wave (CW) or passively Q-switched mode. Efficient operation of such a microchip laser, which is built with a 0.3 mm thick crystal plate in a 2 mm long plane-parallel cavity, is realized at room temperature. With 2.37 W of pump power absorbed, 1.45 W of CW output power is generated with a slope efficiency of 73%. When passively Q-switched with a Cr4+:YAG crystal plate as saturable absorber, the laser produces a maximum pulsed output power of 0.53 W at 1013.3 nm, at a pulse repetition rate of 23.8 kHz, the resulting pulse energy, duration, and peak power are 22.3 μJ, 4.0 ns, and 5.6 kW, respectively.

Nd:YAG Laser-aided ceramic brackets debonding: Effects on shear bond strength and enamel surface

NASA Astrophysics Data System (ADS)

Han, Xianglong; Liu, Xiaolin; Bai, Ding; Meng, Yao; Huang, Lan

2008-11-01

In order to evaluate the efficiency of Nd:YAG laser-aided ceramic brackets debonding technique, both ceramic brackets and metallic brackets were bonded with orthodontic adhesive to 30 freshly extracted premolars. The specimens were divided into three groups, 10 in each, according to the brackets employed and the debonding techniques used: (1) metallic brackets with shear debonding force, (2) ceramic brackets with shear debonding force, and (3) ceramic brackets with Nd:YAG laser irradiation. The result showed that laser irradiation could diminish shear bond strength (SBS) significantly and produce the most desired ARI scores. Moreover, scanning electron microscopy investigation displayed that laser-aided technique induced little enamel scratch or loss. It was concluded that Nd:YAG laser could facilitate the debonding of ceramic brackets and diminish the amount of remnant adhesive without damaging enamel structure.

Dielectric, optical and mechanical studies of phenolic polyene OH1 organic electrooptic crystal

NASA Astrophysics Data System (ADS)

Bharath, D.; Kalainathan, S.

2014-11-01

2-{3-[2-(4-Hydroxyphenyl) vinyl]-5, 5-dimethylcyclo-hex-2-en-1-ylidene}malononitrile (OH1) phenolic locked polyene organic material has been synthesized by the Knoevenagel condensation method. OH1 single crystals were grown in methanol by a slow evaporation method. In order to avoid the multinucleation and reduce the metastable zone width, phosphoric acid is added in different concentrations. The linear optical property of OH1 crystal has been studied using UV-vis-NIR spectroscopy in the wavelength range 190-1100 nm and optical constants are calculated theoretically. The magnitude of nonlinear refractive index (10-12 m2/W), nonlinear absorption (10-6 m/W) and third order nonlinear susceptibility (10-6 esu) has been studied using a Z-scan technique. Dielectric property of OH1 crystal has been studied in frequency range 50 Hz-5 MHz. Photoluminescence spectrum was recorded using a xenon lamp in the range of 450-700 nm. Laser optical damage threshold of OH1 crystal was obtained (0.62 GW/cm2) using a pulsed Nd-YAG laser (1064 nm) of repetition rate 10 ns.

Growth, structural, spectroscopic, thermal, dielectric and optical study of cobalt sulphide-doped ADP crystals

NASA Astrophysics Data System (ADS)

Kochuparampil, A. P.; Joshi, J. H.; Joshi, M. J.

2017-09-01

As ammonium dihydrogen phosphate (ADP) is a popular nonlinear optical crystal, to engineer its linear and nonlinear optical properties, the chalcogenide compound cobalt sulphide (CoS) was doped and the crystals were grown by the slow solvent evaporation method. To increase the solubility of CoS in water, its nanoparticles were synthesized by wet chemical technique using ethylene diamine as the capping agent followed by microwave irradiation. The nanoparticle sample exhibited finite solubility in water and was used to dope in ADP crystals. The powder XRD patterns showed the single phase nature of the doped crystals. The FTIR spectra confirmed the presence of various functional groups and EDAX gave the estimation of Co and S elements. The EPR spectroscopy also confirmed the presence of cobalt in the doped samples. TGA indicated slightly less thermal stability of the doped crystals compared to the pure ADP. The dielectric study was carried out at room temperature in the frequency range from 100Hz to 1MHz. Also, various linear optical parameters were evaluated for pure and doped crystals using UV-Vis spectroscopy. The second harmonic generation (SHG) efficiency of Nd:YAG laser was evaluated by the Kurtz and Parry method for the doped samples, it was found to be slightly lesser than that of the pure ADP crystals.

Development and performance characteristics of flash lamp pumped Yb:YAG, Cr:Tm:Ho:YAG, Er:Tm:Ho:YLF laser sources and investigation of their potential biological applications

NASA Astrophysics Data System (ADS)

Karadimitriou, N.; Klinkenberg, B.; Papadopoulos, D. N.; Serafetinides, A. A.

2007-07-01

Laser ablation for the formation of apodized patterns on intraocular lenses, as an alternative of the conventional injection molding, has been proved to be a very promising new technique. For the precise lenses ablation, the use of suitable laser wavelength and pulse duration, resulting in a small optical penetration depth in the lens and in confinement of the energy deposition in a small volume, as well as the reduced thermal damage to the surrounding tissue, is essential. Mid-infrared laser wavelengths, at which the organic biological simulators absorption coefficient is large, meet well the above conditions. Towards the complete understanding of the intraocular lens ablation procedure and therefore the choice of the optimum laser beam characteristics for the most accurate, efficient and safe surgical application, the comparative study of various mid-infrared laser sources is of great interest. In this work we investigate the potential of the development of three different mid-infrared laser sources, namely the Yb:YAG, the Cr:Tm:Ho:YAG and the Er:Tm:Ho:YLF laser, operating at 1029 nm, 2060 nm and 2080 nm respectively and their ability in forming patterns on biomaterials. Pumping was achieved with conventional Xe flash lamps in a double elliptical pump chamber. A properly designed Pulse-Forming- Network capable of delivering energy up to 800 J, in variable lamp illumination durations is used. Several hundreds of mJoules were achieved from the Yb:YAG laser oscillator and several Joules from the Ho:YAG and Ho:YLF laser oscillators. Free running and Q-switched laser operation studies and preliminary experiments on laser and biomaterials (biopolymers and animal tissues) interactions will be reported.

Synthesis, Hirshfeld surface analysis, laser damage threshold, third-order nonlinear optical property and DFT computation studies of Dichlorobis(DL-valine)zinc(II): A spectroscopic approach

NASA Astrophysics Data System (ADS)

Chitrambalam, S.; Manimaran, D.; Hubert Joe, I.; Rastogi, V. K.; Ul Hassan, Israr

2018-01-01

The organometallic crystal of Dichlorobis(DL-valine)zinc(II) was grown by solution growth method. The computed structural geometry, vibrational wavenumbers and UV-visible spectra were compared with experimental results. Hirshfeld surface map was used to locate electron density and the fingerprint plots percentages are responsible for the stabilization of intermolecular interactions in molecular crystal. The second-order hyperpolarizability value of the molecule was also calculated at density functional theory method. The surface resistance and third-order nonlinear optical property of the crystal were studied by laser induced surface damage threshold and Z-scan techniques, respectively using Nd:YAG laser with wavelength 532 nm. The open aperture result exhibits the reverse saturation absorption, which indicate that this material has potential candidate for optical limiting and optoelectronic applications.

The non-planar single-frequency ring laser with variable output coupling

NASA Astrophysics Data System (ADS)

Wu, Ke-ying; Yang, Su-hui; Wei, Guang-hui

2002-03-01

We put forward a novel non-planar single-frequency ring laser, which consists of a corner cube prism and a specially cut Porro prism made by Nd:YAG crystal. The relative angle between the corner cube and the Porro prism could be adjusted to control the output coupling of the laser resonator and the polarization-state of the output laser. A 1.06 μm single-frequency laser with 1 W output has been obtained.

Bibliography of Soviet Laser Developments, Number 52, March - April 1981.

DTIC Science & Technology

1982-05-17

KNbOj crystal and pumped by the second harmonic of a YAG laser. KE, no. 4, 1981, 715-721. 187. Soldatov, A.N., V.B. Sukhanov , Yu.P. Polunin, and A.I...27.63SLOBODYANYUC A V 36 SUENDER D 96 TOLSTOY M N 7SNIRNOY A N 88 SUKHANOV V B 30 TOMCHUK YE YA 59SMIRNOY D F 37 SUI(HANOVA G3 B 15 TOHILINA V 1 60S?4IRNOV S

Properties of nanocones formed on a surface of semiconductors by laser radiation: quantum confinement effect of electrons, phonons, and excitons

PubMed Central

2011-01-01

On the basis of the analysis of experimental results, a two-stage mechanism of nanocones formation on the irradiated surface of semiconductors by Nd:YAG laser is proposed for elementary semiconductors and solid solutions, such as Si, Ge, SiGe, and CdZnTe. Properties observed are explained in the frame of quantum confinement effect. The first stage of the mechanism is characterized by the formation of a thin strained top layer, due to redistribution of point defects in temperature-gradient field induced by laser radiation. The second stage is characterized by mechanical plastic deformation of the stained top layer leading to arising of nanocones, due to selective laser absorption of the top layer. The nanocones formed on the irradiated surface of semiconductors by Nd:YAG laser possessing the properties of 1D graded bandgap have been found for Si, Ge, and SiGe as well, however QD structure in CdTe was observed. The model is confirmed by "blue shift" of bands in photoluminescence spectrum, "red shift" of longitudinal optical line in Raman back scattering spectrum of Ge crystal, appearance of Ge phase in SiGe solid solution after irradiation by the laser at intensity 20 MW/cm2, and non-monotonous dependence of Si crystal micro-hardness as function of the laser intensity. PMID:22060172

Structure and temperature effects on Nd3+ spectra in polycrystalline mixed scandium aluminum garnets Y3ScxAl5-xO12

NASA Astrophysics Data System (ADS)

Lupei, A.; Lupei, V.; Hau, S.; Gheorghe, C.; Voicu, F.

2015-09-01

New spectroscopic data obtained from high resolution low temperature absorption and emission spectra of Nd3+ in mixed scandium aluminum garnets Y3ScxAl5-xO12 - (x = 0-2) translucent ceramics revealed transition dependent composition effects: modification of the shapes (Lorentz at x = 0 and 2, quasi-Gauss at x = 1, x-dependent asymmetric for other x values, with obvious multicenter structure for low x), widths and shifts of the lines. Nd3+ electronic structure dependence on structural changes with composition is analyzed in terms of nephelauxetic effect and maximum splitting of manifolds: Sc3+ co-doping reduces the nephelauxetic effect, and the increase of 4F3/2 splitting from 85 cm-1 (x = 0) to 98 cm-1 (x = 2) denotes the lowering of local symmetry. The multicenter structure and inhomogeneous broadening of Nd3+ lines is attributed to crystal field distributions determined by the random occupancy of the octahedral sites by Sc3+ and Al3+. For low x (0.2) the resolved two satellites S1, S2 that accompany Nd:YAG lines are correlated to anisotropic crystal field perturbations produced by the n.n. Sc3+ by analogy to those determined by Y3+-antisites (excess of Y3+ ions that enter in octahedral sites of the melt-grown YAG crystals). The temperature evolution of the Nd3+ spectral characteristics (line intensity, shift, broadening) in the 10-300 K range is analyzed in terms of thermal population of the Stark levels, of the effect on electron-phonon interaction and on lattice expansion. The relevance of the spectroscopic properties on the laser emission characteristics in these systems is discussed.

Epitaxial Growth of LuAG:Ce and LuAG:Ce,Pr Films and Their Scintillation Properties

NASA Astrophysics Data System (ADS)

Douissard, Paul-Antoine; Martin, Thierry; Riva, Federica; Zorenko, Yuriy; Zorenko, Tetiana; Paprocki, Kazimierz; Fedorov, Alexander; Bilski, Pawel; Twardak, Anna

2016-06-01

We performed the growth by Liquid Phase Epitaxy (LPE) of Ce and Ce-Pr doped Lu3Al5O12 (LuAG) Single Crystalline Films (SCFs) onto LuAG and Y3Al5O12 (YAG) substrates. The structural properties of LuAG:Ce and LuAG:Ce,Pr SCFs were examined by X-ray diffraction. The optical properties of the SCFs were studied through cathodoluminescence (CL) spectra, scintillation Light Yield (LY), decay kinetic under α-particle (Pu239) excitation, X-ray excited luminescence, thermostimulated luminescence (TSL) and afterglow measurements. The SCFs grown on LuAG substrates displayed good surface quality and structural perfection, whereas the SCFs grown on YAG substrates showed a rough surface and poorer crystalline quality, due to a large lattice mismatch between the film and the substrate (0.82%). Under α-particle excitation, the LY of LuAG:Ce SCF exceeded by 2 times that of the best YAG:Ce SCF sample used as reference. Under X-ray excitation, the LuAG:Ce SCF with optimized Ce concentration showed LY close (77%) to a reference YAG:Ce Single Crystal (SC) scintillator. The afterglow of LuAG:Ce and LuAG:Ce,Pr SCFs was lower (by 1 decade) than that of the tested reference LuAG:Ce SC. However there is not a complete suppression of the afterglow at room temperature (RT), despite the fact that the SCFs present much lower concentration of antisite and vacancy type defects than their SC counterparts. This can be explained by the presence in the films of other trap centers responsible for TSL above RT.

Microstructure and mechanical changes induced by Q-Switched pulse laser on human enamel with aim of caries prevention

NASA Astrophysics Data System (ADS)

Apsari, R.; Pratomo, D. A.; Hikmawati, D.; Bidin, N.

2016-03-01

This study was conducted to determine the effect of Q-Switched Nd: YAG laser energy dose to human enamel caries. The specifications of Q-Switched Nd: YAG laser as followed: wavelength of 1064 nm and 6 ns pulse width. Caries enamel samples taken from human teeth molars of 17-35 ages and the type of media caries. Energy doses used in this study were 723.65 mJ/cm2, 767.72 mJ/cm2, and 1065.515 mJ/cm2; 5 Hz repetition rate, and 20 second exposure time. Samples characterized the surface morphology and the percentage of constituent elements, especially calcium/phosphorus (Ca/P) with FESEM-EDAX. The fraction volume and crystallinity percentage of hydroxyapatite (HA) with XRD and hardness value using Vickers Microhardness Test. The results indicated that exposure of Q-Switched Nd:YAG laser on enamel caries resulting cracks, holes, and melt due to plasma production effects in the surface. Plasma production effect also resulted in micro properties such as percentage of Ca/P was close to normal, the fraction volume and crystallinity percentage of HA went up but did not change the crystal structure (in terms of the lattice structure). The hardness value also rose as linear as exposure energy dose caused by phototermal effect. Based on the results, Q-Switched Nd:YAG laser can be used as contactless drill dental caries replacement candidate with the additional therapy effect such as localized caries in order to avoid the spread, the ratio of Ca/P approaching healthy teeth, the fraction volume and crystallinity percentage of HA rose and established stronger teeth with peak energy dose 1065.515 mJ/cm2.

Growth and characterization of Methyl 2-amino-5-bromobenzoate crystal for NLO applications

NASA Astrophysics Data System (ADS)

Parthasarathy, M.; Gopalakrishnan, R.

2012-11-01

Good quality single crystal of organic Methyl 2-amino-5-bromobenzoate (M2A5B) was grown using slow evaporation solution growth technique. The grown crystal was confirmed by single crystal X-ray diffraction. The functional groups and vibrational frequencies were identified using FT-IR and FT-Raman spectral analyses. The presence of hydrogen and carbon atoms in the grown sample was confirmed with proton and carbon NMR spectral studies. The optical energy band gap of the title compound is found to be 2.7 eV from the optical transmission spectra. The refractive indices nx, ny, and nz were found to be 1.569, 1.587 and 1.600, respectively using Brewster's angle method. The melting point of the material obtained with melting point apparatus is 74 °C. Thermal stability of the grown crystal was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The mechanical behaviour of the grown crystal was analyzed with Vicker's microhardness tester. The particle size dependent second harmonic generation efficiency for M2A5B was evaluated by Kurtz-Perry powder method using Nd:YAG laser, which established the existence of phase matching.

Crystal growth, structural, optical, spectral and thermal studies of tris(L-phenylalanine)L-phenylalaninium nitrate: a new organic nonlinear optical material.

PubMed

Prakash, M; Geetha, D; Lydia Caroline, M

2011-10-15

Tris(L-phenylalanine)L-phenylalaninium nitrate, C(9)H(12)NO(2)(+)·NO(3)(-)·3C(9)H(11)NO(2) (TPLPN), a new organic nonlinear optical material was grown from aqueous solution by slow evaporation solution growth at room temperature. The grown crystals were subjected to powder X-ray diffraction and single crystal X-ray diffraction studies to confirm the crystalline nature and crystal structure. The modes of vibration of different molecular groups present in TPLPN have been identified by FTIR spectral analysis. The presence of hydrogen and carbon in the grown crystal were confirmed by using proton and carbon nuclear magnetic resonance (NMR) spectral analyses. The optical transmission spectral study establishes good transmitting ability of the crystal in the entire visible region. The thermogravimetric (TG) and differential thermal analyses (DTA) were carried out to understand the thermal stability of the sample. The nonlinear optical property of the compound observed using Kurtz powder second harmonic generation test assets the suitability of the grown material for the frequency conversion of laser radiation of Nd:YAG. Copyright © 2011 Elsevier B.V. All rights reserved.

Double Stokes-Mueller polarimetry in KTP (Potassium Titanyl Phosphate) crystal

NASA Astrophysics Data System (ADS)

Shaji, Chitra; S B, Sruthil Lal; Sharan, Alok

2017-04-01

Ultra-structural properties of material are being probed by Double Stokes-Mueller polarimetry (DSMP) technique. It makes use of higher dimensions of Stokes vector (9 X 1) and Mueller matrix (4 X9) to characterize the nonlinear optical properties of a material. Second harmonic generation (SHG) at 532nm using 1064nm as fundamental cw beam from Nd: YAG laser in type II phase matched KTP (Potassium Titanyl Phosphate) crystal is studied using DSMP. The experimental measurements for determining double Mueller matrix are carried out in the ``Polarization In Polarization Out'' (PIPO) arrangement. Nine input polarization states are incident on the sample and the linear Stokes vector of the emerging light from the sample is measured. The KTP crystal is oriented such that the SHG signal efficiency at the incident horizontal and vertical polarizations is high as compared to diagonal polarization states. The susceptibility tensor components and the phase difference between them at this orientation are determined from the double Mueller matrix elements. These determined values give information regarding the crystal axis orientations. To our knowledge, this is the first report of the use of DSMP technique to determine the crystal orientations of a biaxial crystal.

Fractional Er:YAG laser assisting topical betamethasone solution in combination with NB-UVB for resistant non-segmental vitiligo.

PubMed

Yan, Ru; Yuan, Jinping; Chen, Hongqiang; Li, Yuan-Hong; Wu, Yan; Gao, Xing-Hua; Chen, Hong-Duo

2017-09-01

Resistant non-segmental vitiligo is difficult to be treated. Ablative erbium-YAG (Er:YAG) laser has been used in the treatment of vitiligo, but the ablation of entire epidermis frustrated the compliance of patients. The purpose of this study is to investigate the effects of fractional Er:YAG laser followed by topical betamethasone and narrow band ultraviolet B (NB-UVB) therapy in the treatment of resistant non-segmental vitiligo. The vitiligo lesions of each enrolled patient were divided into four treatment parts, which were all irradiated with NB-UVB. Three parts were, respectively, treated with low, medium, or high energy of Er:YAG laser, followed by topical betamethasone solution application. A control part was spared with laser treatment and topical betamethasone. The treatment period lasted 6 months. The efficacy was assessed by two blinded dermatologists. Treatment protocol with high energy of 1800 mJ/P of fractional Er:YAG laser followed by topical betamethasone solution and in combination with NB-UVB made 60% patients achieve marked to excellent improvement in white patches. The protocol with medium energy of 1200 mJ/P of laser assisted approximate 36% patients achieve such improvement. The two protocols, respectively, showed better efficacies than NB-UVB only protocol. However, fractional Er:YAG laser at low energy of 600 mJ/P did not provide such contributions to the treatment of vitiligo. The fractional Er:YAG laser in combination with topical betamethasone solution and NB-UVB was suitable for resistant non-segmental vitiligo. The energy of laser was preferred to be set at relatively high level.

Damage thresholds of silica fibers in holmium:YAG laser energy delivery for medical applications

NASA Astrophysics Data System (ADS)

Marolda, Matthew D.; Perrault, Donald F., Jr.; Pankratov, Michail M.; Shapshay, Stanley M.

1993-07-01

Pulsed Holmium:YAG (Ho:YAG) laser has been approved for some clinical applications and is under investigation for others. There is little published evidence on the durability or damage parameters for the fibers used in delivering energy from pulsed Ho:YAG laser. This study makes an initial attempt to investigate the damage threshold of different silica fibers under various conditions. Three types of fibers supplied by different manufacturers underwent laboratory testing. The overall finding of the study is that a new `perfect' fiber sustains no damage when fired without a target in air or in saline at energies up to 1.5 J/pulse and repetition rate up to 10 Hz. This study suggests that one may need to chose a fiber according to the clinical procedure to be performed: in cases where only soft tissue is to be manipulated - - any fiber may fare well, in cases where bone or calcified tissue is to be lased -- one may need fiber with aluminized or other hard coating. We also conclude that only professional refinishing with the removal of all exposed core-cladding material can insure trouble free performance.

Passively Q-switched Nd3+ solid-state lasers with antimonene as saturable absorber.

PubMed

Wang, Mengixa; Zhang, Fang; Wang, Zhengping; Wu, Zhixin; Xu, Xinguang

2018-02-19

Based on the saturable absorption feature of a two-dimensional (2D) nano-material, antimonene, the passively Q-switched operation for solid-state laser was realized for the first time. For the 946 and 1064 nm laser emissions of the Nd:YAG crystal, the Q-switched pulse widths were 209 and 129 ns, and the peak powers were 1.48, 1.77 W, respectively. For the 1342 nm laser emission of the Nd:YVO 4 crystal, the Q-switched pulse width was 48 ns, giving a peak power of 28.17 W. Our research shows that antimonene can be used as a stable, broadband optical modulating device for a solid-state laser, which will be particularly effective for long wavelength operation.

Growth, structural, optical, thermal and mechanical properties of cytosinium hydrogen selenite: A novel nonlinear optical single crystal

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

Jaikumar, P.; Sathiskumar, S.; Balakrishnan, T., E-mail: balacrystalgrowth@gmail.com

Highlights: • Growth of bulk single crystals of cytosinium hydrogen selenite (CHS) is reported. • Dielectric constant of CHS is measured as a function of Frequency and temperature. • Lower cut off value of UV–vis-NIR spectrum of CHS crystal is observed at 210 nm. • Meyer’s index value of CHS crystal calculated identifies it as a soft material. • Powder SHG efficiency of CHS is about 1.5 times that of KDP crystal. - Abstract: A novel nonlinear optical single crystal of cytosinium hydrogen selenite was grown from aqueous solution of cytosinium hydrogen selenite by slow solvent evaporation method at roommore » temperature. The structural properties of grown crystal have been studied by single crystal and powder X-ray diffraction analysis. Presence of various functional groups was identified from Fourier transform infrared spectroscopy. The optical transmittance and absorbance spectra were recorded by UV–vis-NIR spectrometer and the grown crystal possesses good transparency in the entire visible region. The dielectric constant and dielectric loss of the crystal were calculated as a function of frequency at different temperatures. The mechanical strength of the cytosinium hydrogen selenite crystal was estimated using Vicker’s microhardness tester. Etch patterns of the cytosinium hydrogen selenite crystal were obtained using distilled water as etchant for different etching time. Second harmonic generation efficiency tested using Nd:YAG laser is about 1.5 times that of KDP.« less

The Laser Guide Star System for Adaptive Optics at Subaru Telescope

NASA Astrophysics Data System (ADS)

Hayano, Y.; Saito, Y.; Ito, M.; Saito, N.; Akagawa, K.; Takazawa, A.; Ito, M.; Wada, S.; Takami, H.; Iye, M.

We report on the current status of developing the new laser guide star (LGS) system for the Subaru adaptive optics (AO) system. We have three major subsystems: the laser unit, the relay optical fiber and the laser launching telescope. A 4W-class all-solid-state 589nm laser has been developed as a light source for sodium laser guide star. We use two mode-locked Nd:YAG lasers operated at the wavelength of 1064nm and 1319nm to generate sum-frequency conversion into 589nm. The side-LD pumped configuration is used for the mode-locked Nd:YAG lasers. We have carefully considered the thermal lens effect in the cavity to achieve a high beam quality with TEM00; M2 = 1.06. The mode-locked frequency is selected at 143 MHz. We obtained the output powers of 16.5 W and 5.0 W at 1064nm and 1319 nm. Sum frequency generated by mixing two synchronized Nd:YAG mode-locked pulsed beams is precisely tuned to the sodium D2 line by thermal control of the etalon in the 1064nm Nd:YAG laser by observing the maximum fluorescence intensity of heated sodium vapor cell. The maximum output power at 589.159 nm reaches to 4.6 W using a PPMgOSLT crystal as a nonlinear optical crystal. And the output power can be maintained within a stability of +/- 1.2% for more than 3 days without optical damage. We developed a single-mode photonic crystal fiber (PCF) to relay the laser beam from laser clean room, in which the laser unit is located on the Nasmyth platform, to the laser launching telescope mounted behind the secondary mirror of Subaru Telescope. The photonic crystal fiber has solid pure silica core with the mode field diameter of 14 micron, which is relatively larger than that of the conventional step-index type single mode fiber. The length of the PCF is 35m and transmission loss due to the pure silica is 10dB/km at 589nm, which means PCF transmits 92% of the laser beam. We have preliminary achieved 75% throughput in total. Small mode-locked pulse width in time allows us to transmit the high-power laser beam with no suffer from the non-linear scatter effect, i.e. stimulated Brillouin scatter, in the PCF. The laser launching telescope (LLT) has an output clear aperture as 50 cm. It is classical Cassegrain type optical configuration with tertiary mirror to insert the laser beam from the side. The wavefront error is designed to be 60 to 70nm. The LLT is a copy product what European Southern Observatory has been designed for the laser guide star system at Very Large Telescope. We succeeded to launch the laser beam to the sky on October 12, 2006. After several tests on the sky, we succeeded to get an image of the laser guide star with the size of more than 10 arc second. The larger size of the laser guide star is caused by the large optical aberration on the primary mirror of LLT due to the heat stress generated at the trigonal support points. We are making a plan to repair this problem during June and the second laser launching test will start around this summer.

Computational modelling of Er(3+): Garnet laser materials

NASA Technical Reports Server (NTRS)

Spangler, Lee H.

1994-01-01

The Er(3+) ion has attracted a lot of interest for four reasons: (1) Its (4)I(sub 13/2) yields (4)I(sub 15/2) transition lases in the eyesafe region near 1.5 micron; (2) the (4)I(sub 13/2) transition lases near 2.8 micron, an important wavelength for surgical purposes; (3) it displays surprisingly efficient upconversion with lasing observed at 1.7, 1.2, 0.85, 0.56, 0.55, and 0.47 micron following 1.5 micron pumping; and (4) it has absorption bands at 0.96 and 0.81 micron and thus can be diode pumped. However, properties desirable for upconversion reduce the efficiency of 1.5 and 3 micron laser operation and vice versa. Since all of the processes are influenced by the host via the crystal field induced stark splittings in the Er levels, this project undertook modelling of the host influence on the Er lasinng behavior. While growth and measurement of all ten Er(3+) doped garnets is the surest way of identifying hosts which maximize upconversion (or conversly, 1.5 and 3 micron performance), it is also expensive - costing approximately $10,000/material or approximately $100,000 for the materials computationally investigated here. The calculations were performed using a quantum mechanical point charge model developed by Clyde Morrison at Harry Diamond Laboratories. The programs were used to fit the Er:YAG experimental energy levels so that the crystal field parameters, B(sub nm) could be extracted. From these radial factors, rho (sub n) were determined for Er(3+) in garnets. These, in combination with crystal field components, Anm, available from X-ray data, were used to predict energy levels for Er in the other nine garnet hosts. The levels in Er:YAG were fit with an rms error of 12.2/cm over a 22,000/cm range. Predicted levels for two other garnets for which literature values were available had rms errors of less than 17/cm , showing the calculations to be reliable. Based on resonances between pairs of calculated stark levels, the model predicts GSGG as the best host for 1.5 micron laser operation, GSGG or YSAG as the best host for a 2.8 micron operation, and LuGG as the best host for an upconversion material.

Investigations on the potential of a low power diode pumped Er:YAG laser system for oral surgery

NASA Astrophysics Data System (ADS)

Stock, Karl; Wurm, Holger; Hausladen, Florian; Wagner, Sophia; Hibst, Raimund

2015-02-01

Flash lamp pumped Er:YAG-lasers are used in clinical practice for dental applications successfully. As an alternative, several diode pumped Er:YAG laser systems (Pantec Engineering AG) become available, with mean laser power of 2W, 15W, and 30W. The aim of the presented study is to investigate the potential of the 2W Er:YAG laser system for oral surgery. At first an appropriate experimental set-up was realized with a beam delivery and both, a focusing unit for non-contact tissue cutting and a fiber tip for tissue cutting in contact mode. In order to produce reproducible cuts, the samples (porcine gingiva) were moved by a computer controlled translation stage. On the fresh samples cutting depth and quality were determined by light microscopy. Afterwards histological sections were prepared and microscopically analyzed regarding cutting depth and thermal damage zone. The experiments show that low laser power ≤ 2W is sufficient to perform efficient oral soft tissue cutting with cut depth up to 2mm (sample movement 2mm/s). The width of the thermal damage zone can be controlled by the irradiation parameters within a range of about 50μm to 110μm. In general, thermal injury is more pronounced using fiber tips in contact mode compared to the focused laser beam. In conclusion the results reveal that even the low power diode pumped Er:YAG laser is an appropriate tool for oral surgery.

Optical coatings on laser crystals for HiPER project

NASA Astrophysics Data System (ADS)

Oulehla, Jindrich; Pokorný, Pavel; Lazar, Josef

2011-06-01

In this contribution we present a technology for deposition of interference coatings for optical components designed to operate as active media in power pulsed lasers. The aim of the technology is to prepare crystals for lasers for the HiPER project (High Power laser Energy Research) which should demonstrate the feasibility of laser driven fusion as a future energy source. Diode pumped solid state lasers (DPSSL) are the most likely option for fusion ignition. The choice of material for the lasers active medium is critical. Some of the most important properties include the ability to be antireflection coated to reduce the energy losses and increase the overall efficiency. This contribution deals with some of the materials considered to be candidates for slabs serving as the active medium of the DPSSLs. We tested Yb:YAG, Yb:CaF2 and Yb:KGW samples. As large amounts of heat need to be dissipated during laser operation, cryogenic cooling is necessary. Appropriate coating materials and techniques need to be chosen. Therefore differences between available coating techniques are investigated in terms of adhesion, enduring of stress resulting from temperature shocks, etc. Coated samples were placed in a specially designed cryogenic apparatus in order to simulate conditions similar to those in real life operation. Optical microscopy and spectrophotometer measurements were used for coating investigation after the conducted experiments.

The high temperature creep behavior of oxides and oxide fibers

NASA Technical Reports Server (NTRS)

Jones, Linda E.; Tressler, Richard E.

1991-01-01

A thorough review of the literature was conducted on the high-temperature creep behavior of single and polycrystalline oxides which potentially could serve as fiber reinforcements in ceramics or metal matrix applications. Sapphire when oriented with the basal plane perpendicular to the fiber axis (c-axis oriented) is highly creep resistant at temperatures in excess of 1600 C and applied loads of 100 MPa and higher. Pyramidal slip is preferentially activated in sapphire under these conditions and steady-state creep rates in the range of 10(exp -7) to 10 (exp -8)/s were reported. Data on the creep resistance of polycrystalline beryllia suggest that C-axiz oriented single crystal beryllia may be a viable candidate as a fiber reinforcement material; however, the issure of fabricability and moisture sensitivity must be addressed for this material. Yttrium aluminum garnet (YAG) also appears to be a fiber candidate material having a high resistance to creep which is due to it's complex crystal structure and high Peierl resistance. The high creep resistance of garnet suggests that there may be other complex ternary oxides such as single crystal mullite which may also be candidate materials for fiber reinforcements. Finally, CVD and single crystal SiC, although not oxides, do possess a high resistance to creep in the temperature range between 1550 and 1850 C and under stresses of 110 to 220 MPa. From a review of the literature, it appears that for high creep resistant applications sapphire, silicon carbide, yttrium aluminum garnet, mullite, and beryllia are desirable candidate materials which require further investigation.

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

Amekura, Hiro, E-mail: amekura.hiroshi@nims.go.jp; Akhmadaliev, Shavkat; Zhou, Shengqiang

When ion irradiation introduces point-defects in semiconductors/insulators, discrete energy levels can be introduced in the bandgap, and then optical transitions whose energies are lower than the bandgap become possible. The electronic transitions between the discrete level and the continuous host band are observed as a continuous tail starting from the fundamental edge. This is the well-known mechanism of the absorption tail close to the band-edge observed in many semiconductors/insulators. In this paper, we propose another mechanism for the absorption tail, which is probably active in Nd-doped yttrium aluminum garnet (Nd:YAG) after ion irradiation and annealing. A Nd:YAG bulk crystal wasmore » irradiated with 15 MeV Au{sup 5+} ions to a fluence of 8 × 10{sup 14} ions/cm{sup 2}. The irradiation generates an amorphous layer of ∼3 μm thick with refractive index reduction of Δn = −0.03. Thermal annealing at 1000 °C induces recrystallization to randomly aligned small crystalline grains. Simultaneously, an extraordinarily long absorption tail appeared in the optical spectrum covering from 0.24 to ∼2 μm without fringes. The origin of the tail is discussed based on two models: (i) conventional electronic transitions between defect levels and YAG host band and (ii) enhanced light scattering by randomly aligned small grains.« less

Vortex operation in Er:LuYAG crystal laser at ∼1.6 μm

NASA Astrophysics Data System (ADS)

Liu, Qiyao; Zhao, Yongguang; Zhou, Wei; Shen, Deyuan

2017-09-01

An Er3+-doped Lu1.5Y1.5Al5O12 (Er:LuYAG) solid-state laser with direct generation of optical vortex is reported. The vortex laser operation was realized through being pumped by an annular beam at 1532 nm, which was reformatted by a specially fabricated optical mirror. With two different laser output couplers of 10% and 20% transmissions, pure LG01 mode lasers with right-handedness at 1647.7 nm and 1619.5 nm were yielded from a simple two-mirror cavity, respectively, without any helicity control optical element. Furthermore, stable pulse trains at 1647.7 nm have been achieved via employing an acousto-optic Q-switch, and ∼0.66 mJ pulsed energy and ∼65 ns pulse duration were finally obtained at 1 kHz repetition rate, corresponding to a peak power of ∼10.2 kW. The generated pulse vortex maintained LG01 mode with well-determined right-handedness, as in the case of cw laser operation.

All-Solid-State UV Transmitter Development for Ozone Sensing Applications

NASA Technical Reports Server (NTRS)

Prasad, Narasimha S.; Singh, Upendra N.; Armstrong, Darrell Jr.

2009-01-01

In this paper, recent progress made in the development of an all-solid-state UV transmitter suitable for ozone sensing applications from space based platforms is discussed. A nonlinear optics based UV setup based on Rotated Image Singly Resonant Twisted Rectangle (RISTRA) optical parametric oscillator (OPO) module was effectively coupled to a diode pumped, single longitudinal mode, conductively cooled, short-pulsed, high-energy Nd:YAG laser operating at 1064 nm with 50 Hz PRF. An estimated 10 mJ/pulse with 10% conversion efficiency at 320 nm has been demonstrated limited only by the pump pulse spatial profile. The current arrangement has the potential for obtaining greater than 200 mJ/pulse. Previously, using a flash-lamp pumped Nd:YAG laser with round, top-hat profile, up to 24% IR-UV conversion efficiency was achieved with the same UV module. Efforts are underway to increase the IR-UV conversion efficiency of the all solid-state setup by modifying the pump laser spatial profile along with incorporating improved OPO crystals.

The use of solid-state reactions with volume loss to engineer stress and porosity into the fiber-matrix interface of a ceramic composite

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

Hay, R.S.

The effect of the 11 vol% losing during reaction of yttrium-aluminas garnet (YAG) and zirconia was observed in zirconia coated single-crystal alumina fiber-YAG matrix composites. The reaction caused plastic deformation in the alumina fibers, and possibly a minor amount of porosity at fiber-matrix interfaces that was usually indistinguishable from matrix porosity. The results were analyzed by models for diffusive cavitation modified to use reaction self-stress. Crack-healing, tensile stress states along the reaction front that approach plane stress, and the small volume of self-stressed material make crack-like pores unlikely at the high temperatures required for reaction. Smaller matrix grains might promotemore » formation of smaller cavities but are also incompatible with high temperature. Both modeling and experiment suggest that sufficient porosity for crack deflection and fiber pullout cannot form unless processing methods that form dense composites at lower temperatures are used.« less

Wideband and high-gain frequency stabilization of a 100-W injection-locked Nd:YAG laser for second-generation gravitational wave detectors.

PubMed

Ohmae, Noriaki; Moriwaki, Shigenori; Mio, Norikatsu

2010-07-01

Second-generation gravitational wave detectors require a highly stable laser with an output power greater than 100 W to attain their target sensitivity. We have developed a frequency stabilization system for a 100-W injection-locked Nd:YAG (yttrium aluminum garnet) laser. By placing an external wideband electro-optic modulator used as a fast-frequency actuator in the optical path of the slave output, we can circumvent a phase delay in the frequency control loop originating from the pole of an injection-locked slave cavity. Thus, we have developed an electro-optic modulator made of a MgO-doped stoichiometric LiNbO(3) crystal. Using this modulator, we achieve a frequency control bandwidth of 800 kHz and a control gain of 180 dB at 1 kHz. These values satisfy the requirement for a laser frequency control loop in second-generation gravitational wave detectors.

Temporal measurement on and using pulses from laser-like emission obtained from styrylpyridinium cyanine dye

NASA Astrophysics Data System (ADS)

Dharmadhikari, Aditya; Bhowmik, Achintya; Ahyi, Ayayi; Thakur, Mrinal

2000-03-01

We have recently reported observation of spectral narrowing and high-conversion laser-like emission in a solution of styrylpyridinium cynanine dye (SPCD) at a low threshold energy, pumped with the second-harmonic of a picosecond Nd:YAG laser. Fundamental and second-harmonic pulses from a Nd:YAG laser of 80 ps duration at 10 Hz repetition rate were used to pump 0.1 mol/l concentration of SPCD in methanol in two separate pumping arrangements. A highly directional emission was observed in both the pumping arrangements without incorporating any mirrors. The pulse duration of spectrally narrowed emission in both cases was measured by background-free SHG intensity autocorrelation technique. A BBO crystal was used for the autocorrelation measurement. The measured duration of the pulses was 40 ps. These pulses having a spectral linewidth of 10 nm (FWHM) were used as a probe to measure the gain in SPCD solution in a pump-probe set up. The results will be discussed.

Investigation of third-order nonlinear and optical power limiting properties of terphenyl derivatives

NASA Astrophysics Data System (ADS)

Kamath, Laxminarayana; Manjunatha, K. B.; Shettigar, Seetharam; Umesh, G.; Narayana, B.; Samshuddin, S.; Sarojini, B. K.

2014-03-01

A series of new chalcones containing terphenyl as a core and with different functional groups has been successfully synthesized by Claisen-Schmidt condensation method in search of new nonlinear optical (NLO) materials. Molecular structural characterization for the compounds was achieved by FTIR and single crystal X-ray diffraction. The third-order NLO absorption and refraction coefficients were simultaneously determined by Z-scan technique. The measurements were performed at 532 nm with 7 ns laser pulses using a Nd:YAG laser in solution form. The Z-scan experiments reveal that the compounds exhibit strong nonlinear refraction coefficient of the order 10-11 esu and the molecular two photon absorption cross section is 10-46 cm4 s/photon. The results also show that the structures of the compounds have great impact on NLO properties. The compounds show optical power limiting behavior due to two-photon absorption (TPA).

Energy Scaling of Nanosecond Gain-Switched Cr2+:ZnSe Lasers

DTIC Science & Technology

2011-01-01

outcoupler or absorption from the lightly-doped active ions. Additionally, the edges of the crystals are cut at the Brewster angle , which raises...experiments we used Brewster cut Cr:ZnSe gain elements with a chromium concentration of 8x1018 cm-3. Under Cr:Tm:Ho:YAG pumping, the first Cr:ZnSe laser...the energy scaling of nanosecond gain-switched Cr:ZnSe lasers is optimization of the gain medium. In this study we used Brewster cut Cr:ZnSe gain

Diode-Pumped, 2-Micron, Q-Switched Thulium: Y3Al5O12 (Tm:Yag) Microchip Laser

DTIC Science & Technology

2011-05-01

switch with a chromium -doped zinc selenide crystal acting as a saturable absorber passive Q-switch. Finally, we will propose possible future...literature by Heine and Huber [4] and others, while passive Q-switching of 2 μm lasers by a chromium -doped zinc selenide has been demonstrated by Tsai and...these objectives for each component of the laser system. In Chapter 4 a design is presented for replacing our acousto-optic Q-switch with a chromium

Polarization characteristic of a room-temperature Co:MgF2 laser.

PubMed

Zhang, Zengming M; Cui, Yiben B; Li, Fuli L; Zhang, Guobin B; Pu, Qirong R; Xu, Gaojie J

2002-02-20

A study of the polarization characteristic of a Co:MgF2 laser with a 1320-nm YAG pumping laser at room temperature is reported. The thresholds, output energies, and efficiencies of the laser are given at the various polarization states. The more intensive emission is in the pi-polarization pump laser and sigma-polarization laser operation. Performances of the Co:MgF2 lasers are similar for the polarized and unpolarized laser pumping along the optical axis of the crystal.

Crystal growth, physical properties and computational insights of semi-organic non-linear optical crystal diphenylguanidinium perchlorate grown by conventional solvent evaporation method

NASA Astrophysics Data System (ADS)

Kajamuhideen, M. S.; Sethuraman, K.; Ramamurthi, K.; Ramasamy, P.

2018-02-01

A splendid nonlinear optical single crystals diphenylguanidinium perchlorate (DPGP) was lucratively grown by low cost solvent evaporation method with the dimensions of 8 × 4 × 2 mm3. Structural and morphological studies of grown crystal were confirmed using X-ray diffraction studies. The presence of diverse functional groups was identified using FTIR and RAMAN studies. The molecular structure of a grown crystal was inveterate by NMR studies. The optical transmittance of DPGP crystal was analyzed using UV-vis-NIR studies. Photoluminescence spectrum shows sharp, well defined emission peak at 388 nm. Thermal studies assign that adduct is stable with the melting point of 164 °C. Microhardness studies declare that DPGP crystal belongs to the soft material class and their yield strength and elastic stiffness constant values were evaluated. Photoconductivity studies revealed the negative photoconductive nature of DPGP crystal. Second harmonic generation (SHG) efficiency of the DPGP crystal was 1.4 times that of potassium dihydrogen phosphate. Etching studies were carried out for different etching time. The dielectric studies were performed at different frequency. Laser damage threshold properties of DPGP crystal were examined using Nd:YAG laser system. The HOMO-LUMO energy gap evident the charge transfer interaction of the molecule. The calculated first order hyperpolarizability value is 5 times greater than that of urea. Thus, the grown DPGP single crystals are well suited for NLO device fabrications.

Effect of Nd:YAG laser on the solvent evaporation of adhesive systems.

PubMed

Batista, Graziela Ribeiro; Barcellos, Daphne Câmara; Rocha Gomes Torres, Carlos; Damião, Álvaro José; de Oliveira, Hueder Paulo Moisés; de Paiva Gonçalves, Sérgio Eduardo

2015-01-01

This study evaluated the influence of Nd:YAG laser on the evaporation degree (ED) of the solvent components in total-etch and self-etch adhesives. The ED of Gluma Comfort Bond (Heraeus-Kulzer) one-step self-etch adhesive, and Adper Single Bond 2 (3M ESPE), and XP Bond (Dentsply) total-etch adhesives was determined by weight alterations using two techniques: Control--spontaneous evaporation of the solvent for 5 min; Experimental--Nd:YAG laser irradiation for 1 min, followed by spontaneous evaporation for 4 min. The weight loss due to evaporation of the volatile components was measured at baseline and after 10 s, 20 s, 30 s, 40 s, 50 s, 60 s, 70 s, 80 s, 90 s, 100 s, 110 s, 2 min, 3 min, 4 min, and 5 min. Evaporation of solvent components significantly increased with Nd:YAG laser irradiation for all adhesives investigated. Gluma Comfort Bond showed significantly higher evaporation of solvent components than Adper Single Bond 2 and XP Bond. All the adhesives lost weight quickly during the first min of Nd:YAG laser irradiation. The application of Nd:YAG laser on adhesives before light curing had a significant effect on the evaporation of the solvent components, and the ED of Gluma Comfort Bond one-step self-etch adhesive was significantly higher than with Adper Single Bond 2 and XP Bond total-etch adhesives. The use of the Nd:YAG laser on the uncured adhesive technique can promote a greater ED of solvents, optimizing the longevity of the adhesive restorations.

Nd:YAG laser-induced morphology change and photothermal conversion of gold nanorods with potential application in the treatment of port-wine stain.

PubMed

Xing, Linzhuang; Chen, Bin; Li, Dong; Ma, Jun; Wu, Wenjuan; Wang, Guoxiang

2017-04-01

Based on the principle of selective photothermolysis, 1064 nm Nd:YAG laser has great potential for the treatment of deeper and larger PWS. However, the clinical effectiveness is limited because of the weak absorption of blood to Nd:YAG laser. The aim of this study is to obtain the optimal irradiation conditions to effectively destroy vascular lesions with the assistance of PEG-modified gold NRs to enhance blood absorption of Nd:YAG laser. In our study, PEG-modified gold NRs were prepared by the seeded growth method. Gold NRs after exposure to Nd:YAG laser were characterized using absorption spectra and transmission electron microscope images. The tissue-like phantom containing a glass capillary with blood was prepared and exposed to Nd:YAG laser to investigate the laser energy density and pulse number required for blood coagulation before and after the addition of gold NRs in blood. The results show that the millisecond Nd:YAG laser irradiation does not result in the shape change of gold NRs. After injection of gold NRs into the bloodstream (4.60 mg/kg), the absorbance of blood at 1064 nm increased 3.9 times. The threshold energy density for the treatment of PWS decreased by 33% (from 30 to 20 J/cm 2 ). Our findings provide an experimental guide for choosing laser parameters and gold NRs concentration for the treatment of deeper and larger PWS with the assistance of PEG-modified gold NRs in vivo in the future.

Scanning electron microscopic study of the effects of Er:YAG laser on root cementum.

PubMed

Fujii, T; Baehni, P C; Kawai, O; Kawakami, T; Matsuda, K; Kowashi, Y

1998-11-01

Use of Er:YAG laser has been proposed for the removal of microbial deposits and calculus present on teeth affected by periodontal disease. However, the influence of Er:YAG laser irradiation on root surfaces has not yet been fully investigated. The aim of the present study was to evaluate the effects of Er:YAG laser irradiation on root cementum by scanning electron microscopy (SEM). Specimens were obtained from extracted human periodontally-diseased teeth using a water-cooled high-speed bur. An Er:YAG laser beam was then applied at various powers ranging from 25 to 100 mJ/ pulse/sec. The laser irradiation was performed under water irrigation, with the tip held perpendicular to the root surface in the contact mode. Following laser exposure, specimens were fixed, dehydrated, and dried at critical-point in liquid CO2. After mounting on SEM plates and sputter-coating with gold, the cementum surface was examined by SEM. Observations of the root surface showed a relatively flat surface in control specimens. In Er:YAG exposed specimens, the laser beam created a circular, notched-edge, crater-like defect on the root. The bottom of the lesion showed an irregular and sharp-pointed surface. Subsequently, the specimens were fractured with a sharp scalpel perpendicularly to the surface. SEM observations of these specimens showed a 15 microm layer of damaged tissue within the laser-irradiated cementum. The tissue presented an amorphous appearance and the Sharpey's and matrix fiber bundles were not clearly distinguishable. These observations indicate that cementum tissue could be damaged by Er:YAG laser irradiation.

Comparative laser-tissue interaction effects at 1.96 and 2.01 um of Cr; Tm:YAG laser

NASA Astrophysics Data System (ADS)

Pankratov, Michail M.; Perrault, Donald F., Jr.; Shapshay, Stanley M.; Pinto, Joseph F.; Esterowitz, Dina; Aretz, H. Thomas

1992-08-01

A pulsed spiking and nonspiking Cr; thulium (Tm):YAG flash lamp pumped laser operating at 1.96 and 2.01 μm was investigated in vitro in the clinically relevant power range for its basic laser-tissue interaction with soft, cartilaginous, and bone tissues. Some explanations of the differences and possible medical applications are discussed.

Phase, compositional, and morphological changes of human dentin after Nd:YAG laser treatment.

PubMed

Lin, C P; Lee, B S; Lin, F H; Kok, S H; Lan, W H

2001-06-01

Although techniques for repairing root fracture have been proposed, the prognosis is generally poor. If the fusion of a root fracture by laser is possible, it will offer an alternative to extraction. Our group has attempted to use lasers to fuse a low melting-point bioactive glass to fractured dentin. This report is focused on the phase, compositional, and morphological changes observed by means of X-ray diffractometer, Fourier transforming infrared spectroscopy, and scanning electron microscopy-energy dispersive X-ray spectroscopy in human dentin after exposure to Nd:YAG laser. The irradiation energies were from 150 mJ/ pulse-10 pps-4 s to 150 mJ/pulse-30 pps-4 s. After exposure to Nd:YAG laser, dentin showed four peaks on the X-ray diffractometer that corresponding to a-tricalcium phosphate (TCP) and beta-TCP at 20 = 30.78 degrees/34.21 degrees and 32.47 degrees/33.05 degrees, respectively. The peaks of a-TCP and beta-TCP gradually increased in intensity with the elevation of irradiation energy. In Fourier transforming infrared analysis, two absorption bands at 2200 cm(-1) and 2015 cm(-1) could be traced on dentin treated by Nd:YAG laser with the irradiation energies beyond 150 mJ/pulse-10 pps-4 s. The energy dispersive X-ray results showed that the calcium/phosphorus ratios of the irradiated area proportionally increased with the elevation of irradiation energy. The laser energies of 150 mJ/ pulse-30 pps-4 s and 150 mJ/pulse-20 pps-4 s could result in the a-TCP formation and collagen breakdown. However, the formation of glass-like melted substances without a-TCP at the irradiated site was induced by the energy output of 150 mJ/ pulse-10 pps-4 s. Scanning electron micrographs also revealed that the laser energy of 150 mJ/ pulse-10 pps-4 s was sufficient to prompt melting and recrystallization of dentin crystals without cracking. Therefore, we suggest that the irradiation energy of Nd:YAG laser used to fuse a low melting-point bioactive glass to dentin is 150 mJ/ pulse-10 pps-4 s.

15 ps quasi-continuously pumped passively mode-locked highly doped Nd:YAG laser in bounce geometry

NASA Astrophysics Data System (ADS)

Jelínek, M., Jr.; Kubeček, V.

2011-09-01

A semiconductor saturable absorber mirror mode-locking of a quasi-continuously pumped laser based on 2.4 at.% Nd:YAG slab in a bounce geometry was demonstrated and investigated. Output mode-locked and Q-switched train containing 15 pulses with total energy of 500 μJ was generated directly from the oscillator. The measured 15 ps pulse duration and excellent temporal stability ±2 ps are the best values for pure passively mode-locked and Q-switched Nd:YAG laser with the pulse pumping. Furthermore, using the cavity dumping technique, single 19 ps pulse with energy of 25 μJ was extracted directly from the oscillator.

Effect of ammonium carbonate to metal ions molar ratio on synthesis and sintering of Nd:YAG nanopowders

NASA Astrophysics Data System (ADS)

Liu, Qiang; Chen, Cong; Dai, Jiawei; Hu, Zewang; Chen, Haohong; Li, Jiang

2018-06-01

Using the nanopowders synthesized by a reverse co-precipitation method, neodymium doped yttrium aluminum garnet (Nd:YAG) transparent ceramics were fabricated by vacuum sintering method. The influence of ammonium carbonate to metal ions (NH4HCO3/M3+) molar ratio (R value) on the properties of Nd:YAG precursors and powders, as well as the densification, microstructure, and transmittance of the resultant ceramics was systematically investigated. The results show that the precursors have similar compositions and the calcined powders have pure Y3Al5O12 (YAG) phase. However, the R value is closely related to the morphologies of the precursors and powders. It is found that the powder with R = 3.0 has strongest agglomeration and the powders with R = 3.2-4.0 show better dispersity. Using these powders as starting materials, the corresponding ceramics were sintered at 1720 °C for 20 h in vacuum. As a result, the ceramic with R = 3.2 obtains the best transmittance of about 72% at the wavelength of 1064 nm. The grain growth exponent and activation energy of the Nd:YAG ceramics fabricated from the powder with R = 3.2 were also studied.

Rare isotope beam energy measurements and scintillator developments for ReA3

NASA Astrophysics Data System (ADS)

Lin, Ling-Ying

The ReAccelerator for 3 MeV/u beams (ReA3) at the National Superconducting Cyclotron Laboratory (NSCL) in Michigan State University can stop rare isotope beams produced by in-flight fragmentation and reaccelerate them in a superconducting linac. The precise knowledge of the energy and the energy spread of the ion beams extracted from the ReA3 linac is essential for experimental requirement in many applications. Beam energy determination methods such as implantation on a Si detector and/or using calibrated linac settings are precise within a few tens of keV/u. In order to determine beam energies with good resolution of less than 0.5 % FWHM, a 45 degree bending magnet with a movable slit is used to determine the absolute beam energy based on the magnetic rigidity. Two methods have been developed for the energy calibration of the beam analyzing magnet: gamma-ray nuclear resonance reactions and a time-of-flight (TOF) technique. The resonance energies of gamma-ray resonant reactions provide well-known and precise calibration points. The gamma ray yields of the 27Al(p,gamma)28Si at Ep= 992 keV and 632 keV resonances and 58Ni(p,gamma)59Cu at Ep= 1843 keV resonance have been measured with the high efficiency CAESAR (CAESium iodide ARray) and SuN (Summing NaI(Tl)) detectors. By fitting the observed resonant gamma-ray yields, not only the beam energy can be precisely correlated with the magnetic field but also beam energy spread can be obtained. The measured beam energy spread is consistent with beam optics calculations. A time-of-flight system for determining the absolute energy of ion beams and calibrating the 45 degree magnetic analyzer has been developed in ReA3 by using two identical secondary electron monitors (grid-MCP detectors) with appropriate separation. The TOF technique is applicable to the variety of beam energies and ion particles. Velocities of ion beam are determined by simultaneously measuring the arrival time of beam bunches at the two detectors with respect to the acceleration RF clock. The time-of-flight system can provide beam energy information with precision of <0.1%. Scintillators are widely used to reliably measure beam profiles and beam distributions. At low energies, scintillator-based diagnostic devices are more problematic because of their fast light yield degradation under ion bombardment. The degradation of the scintillation yield of single crystal YAG: Ce under He+ irradiation at low energies between 28 and 58 keV has been systematically studied. The scintillator was irradiated at the rare isotope ReAccelerator (ReA) facility. The scintillation emission is attributed to its rapid 5d-4f transition of Ce3+ ions. As the bombardment time increases, an exponential decay of the light output is observed due to the induced radiation damage of the crystal lattice. The decrease of the experimentally observed light yield as a function of particle fluence is found to be in fair agreement with the Birks model. Analysis indicates that the damage cross section of scintillation centers slightly decreases with the ion energy. The scintillator degrades slower under higher-energy irradiation. In order to investigate scintillation degradation over a wide range of irradiation energies and scintillator materials, the scintillation processes for KBr, YAG:Ce, CaF2:Eu and CsI:Tl crystals under H2 + irradiation in the energy range of 600-2150 keV/u have been investigated. The data indicates that YAG:Ce and CsI:Tl can maintain stable luminescence under continuous ion bombardment for at least a total fluence of 1.8x10 12 ions/mm2. On the other hand, the luminescence of CaF2:Eu shows a rapid initial decay but then maintains a nearly constant luminescence yield. The extraordinary scintillation response of KBr is initially enhanced under ion bombardment, approaches a maximum, and then eventually decays. The scintillation efficiency of the CsI:Tl scintillator is superior to the other materials. The low-energy H2+ bombardment (25 keV/u) on the YAG:Ce scintillator can lead to the significant degradation of the scintillation yields. Different scintillation degradation responses for the low- and high-energy bombardments can be attributed to the transmission loss of the emitted light inside the crystal caused by displacement damages.

Measurements of striae in CR+ doped YAG laser crystals

NASA Astrophysics Data System (ADS)

Cady, Fredrick M.

1994-12-01

Striations in Czochralski (CZ) grown crystals have been observed in materials such as GaAs, silicon, photorefractive crystals used for data storage, potassium titanyl phosphate crystals and LiNbO3. Several techniques have been used for investigating these defects including electron microscopy, laser scanning tomography, selective photoetching, X-ray diffuse scattering, interference orthoscopy, laser interferometry and micro-Fourier transform infrared spectroscopy mapping. A 2mm thick sample of the material to be investigated is illuminated with light that is absorbed and non-absorbed by the ion concentration to be observed. The back surface of the sample is focused onto a solid-state image detector and images of the input beam and absorbed (and diffracted) beams are captured at two wavelengths. The variation of the coefficient of absorption asa function of distance on the sample can be derived from these measurements. A Big Sky Software Beamcode system is used to capture and display images. Software has been written to convert the Beamcode data files to a format that can be imported into a spreadsheet program such as Quatro Pro. The spreadsheet is then used to manipulate and display data. A model of the intensity map of the striae collected by the imaging system has been proposed and a data analysis procedure derived. From this, the variability of the attenuation coefficient alpha can be generated. Preliminary results show that alpha may vary by a factor of four or five over distances of 100 mu m. Potential errors and problems have been discovered and additional experiments and improvements to the experimental setup are in progress and we must now show that the measurement techniques and data analysis procedures provide 'real' information. Striae are clearly visible at all wavelengths including white light. Their basic spatial frequency does not change radically, at least when changing from blue to green to white light. Further experimental and theoretical work can be done to improve the data collection techniques and to verify the data analysis procedures.

Light and scanning electron microscope investigations comparing calculus removal using an Er:YAG laser and a frequency-doubled alexandrite laser

NASA Astrophysics Data System (ADS)

Rechmann, Peter; Hennig, Thomas; Sadegh, Hamid M. M.; Goldin, Dan S.

1997-05-01

With respect to lasers emitting within the mid-IR spectral domain fiber applicators are being developed. Intended is the use of these lasers in periodontal therapy and their application inside the gingival pocket. Aim of the study presented here is to compare the effect of an Er:YAG laser on dental calculus with the results following irradiation with a frequency doubled Alexandrite laser. The surface of freshly extracted wisdom teeth and of extracted teeth suffering from severe periodontitis were irradiated with both laser wavelengths using a standardized application protocol. Calculus on the enamel surface, at the enamel cementum junction and on the root surface was irradiated. For light microscope investigations undecalcified histological sections were prepared after treatment. For the scanning electron microscope teeth were dried in alcohol and sputtered with gold. Investigations revealed that with both laser systems calculus can be removed. Using the frequency doubled Alexandrite laser selective removal of calculus is possible while engaging the Er:YAG laser even at lowest energies necessary for calculus removal healthy cementum is ablated without control.

Comparison of tensile bond strengths of four one-bottle self-etching adhesive systems with Er:YAG laser-irradiated dentin.

PubMed

Jiang, Qianzhou; Chen, Minle; Ding, Jiangfeng

2013-12-01

This study aimed to investigate the interaction of current one-bottle self-etching adhesives and Er:YAG laser with dentin using a tensile bond strength (TBS) test and scanning electron microscopy (SEM) in vitro. Two hundred and thirteen dentin discs were randomly distributed to the Control Group using bur cutting and to the Laser Group using an Er:YAG laser (200 mJ, VSP, 20 Hz). The following adhesives were investigated: one two-step total-etch adhesive [Prime & Bond NT (Dentsply)] and four one-step self-etch adhesives [G-Bond plus (GC), XENO V (Dentsply), iBond Self Etch (Heraeus) and Adper Easy One (3 M ESPE)]. Samples were restored with composite resin, and after 24-hour storage in distilled water, subjected to the TBS test. For morphological analysis, 12 dentin specimens were prepared for SEM. No significant differences were found between the control group and laser group (p = 0.899); dentin subjected to Prime & Bond NT, XENOV and Adper Easy One produced higher TBS. In conclusion, this study indicates that Er:YAG laser-prepared dentin can perform as well as bur on TBS, and some of the one-step one-bottle adhesives are comparable to the total-etch adhesives in TBS on dentin.

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

Wildfire, Christina; Sabolsky, Edward M.; Spencer, Michael J.

The rapid synthesis of yttrium aluminum garnet (Y 3Al 15O 12, YAG) powder was investigated through the use of microwave irradiation of the oxide precursor system. For this investigation, an external hybrid heating source was not used. Instead, the rapid heating of the precursor materials (yttria and alumina powders, which are typically transparent to 2.45 GHz microwaves) was initiated by mixing an intrinsic absorbing material (carbon) into the original oxide precursors. The effect of the carbon characteristics, such as carbon source, concentration, particle size, and agglomerate microstructure were evaluated on the efficiency of coupling and resultant oxide reaction. The microwavemore » power was varied to optimize the YAG conversion and eliminate intermediate phase formation. Interactions between the conductive carbon particles and the dielectric oxides within the microwave exposure produced local arching and micro-plasma formation within the powder bed, resulting in the rapid formation of the refractory YAG composition. This optimal conduction led to temperatures of 1000°C that could be achieved in less than 5 min resulting in the formation of > 90 vol% YAG. The understanding of a conductor/dielectric particulate system here, provided insight into possible application of similar systems where microwave irradiation could be used for enhanced solid-state formation, local melting events, and gas phase reactions with a composite powder media.« less

Evaluation of the cavity margins after Er:YAG laser ablation of the enamel and dentin

NASA Astrophysics Data System (ADS)

Dostalova, Tatjana; Krejsa, Otakar; Jelinkova, Helena; Hamal, Karel

1994-12-01

This study investigates the checks of cavity margin after enamel and dentin ablation. The Er:YAG laser enamel and dentin ablation can be directly connected with the danger of cracks originating in the enamel near the cavity. This study evaluates the quality of the enamel edges after Er:YAG laser preparation. The enamel and dentin of buccal surfaces were ablated by the Er:YAG laser radiation. An Erbium:YAG laser system with the energy of 200 mJ was used to generate 200 microsecond(s) long pulses of mid-infrared 2.94 micrometers light in multimode configuration. The laser was operating in a free running mode, the repetition rate being 0.5 Hz with average laser power of 100 mW. Laser radiation was focused on the tooth tissue. Water cooling was used during the procedure in order to prevent tooth tissue destruction. The time of laser preparation was 5 minutes. A cavity of class V was prepared. The teeth were immersed into 0.5% basic fuchsin and then centrifuged at 6000 rev/min for 20 minutes. The microphotographs of the margins stained with 0.5% basic fuchsin were made and then the longitudinal section of the teeth were evaluated. The micrographs of the longitudinal section were checked and measured afterwards. The effect of the investigated laser irradiation on the origin of cracks was analyzed in the scanning electron microscope. Micrographs of each tooth before and after the laser ablation were compared. Micrographs of the intact teeth after extraction present the cracks of the enamel. They depend on the pressure exerted during extraction. The influence of the laser ablation proper is it bears no signs of new cracks. The conclusions of this study demonstrate the non-invasive nature of the Er:YAG laser ablation of the hard dental tissues.

Charge-carrier mobilities in Cd(0.8)Zn(0.2)Te single crystals used as nuclear radiation detectors

NASA Technical Reports Server (NTRS)

Burshtein, Z.; Jayatirtha, H. N.; Burger, A.; Butler, J. F.; Apotovsky, B.; Doty, F. P.

1993-01-01

Charge-carrier mobilities were measured for the first time in Cd(0.8)Zn(0.2)Te single crystals using time-of-flight measurements of charge carriers produced by short (10 ns) light pulses from a frequency-doubled Nd:YAG laser (532 nm). The electron mobility displayed a T exp -1.1 dependence on the absolute temperature T in the range 200-320 K, with a room-temperature mobility of 1350 sq cm/V s. The hole mobility displayed a T exp -2.0 dependence in the same temperature range, with a room-temperature mobility of 120 sq cm/V s. Cd(0.8)Zn(0.2)Te appears to be a very favorable material for a room-temperature electronic nuclear radiation detector.

Charge-transfer state excitation as the main mechanism of the photodarkening process in ytterbium-doped aluminosilicate fibres

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

Bobkov, K K; Rybaltovsky, A A; Vel'miskin, V V

2014-12-31

We have studied photodarkening in ytterbium-doped fibre preforms with an aluminosilicate glass core. Analysis of their absorption and luminescence spectra indicates the formation of stable Yb{sup 2+} ions in the glass network under IR laser pumping at a wavelength λ = 915 nm and under UV irradiation with an excimer laser (λ = 193 nm). We have performed comparative studies of the luminescence spectra of the preforms and crystals under excitation at a wavelength of 193 nm. The mechanism behind the formation of Yb{sup 2+} ions and aluminium – oxygen hole centres (Al-OHCs), common to ytterbium-doped YAG crystals and aluminosilicatemore » glass, has been identified: photoinduced Yb{sup 3+} charge-transfer state excitation. (optical fibres)« less

Charge deformation and orbital hybridization: intrinsic mechanisms on tunable chromaticity of Y3Al5O12:Ce3+ luminescence by doping Gd3+ for warm white LEDs

PubMed Central

Chen, Lei; Chen, Xiuling; Liu, Fayong; Chen, Haohong; Wang, Hui; Zhao, Erlong; Jiang, Yang; Chan, Ting-Shan; Wang, Chia-Hsin; Zhang, Wenhua; Wang, Yu; Chen, Shifu

2015-01-01

The deficiency of Y3Al5O12:Ce (YAG:Ce) luminescence in red component can be compensated by doping Gd3+, thus lead to it being widely used for packaging warm white light-emitting diode devices. This article presents a systematic study on the photoluminescence properties, crystal structures and electronic band structures of (Y1−xGdx)3Al5O12: Ce3+ using powerful experimental techniques of thermally stimulated luminescence, X-ray diffraction, X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS) and ultraviolet photoelectron spectra (UPS) of the valence band, assisted with theoretical calculations on the band structure, density of states (DOS), and charge deformation density (CDD). A new interpretation from the viewpoint of compression deformation of electron cloud in a rigid structure by combining orbital hybridization with solid-state energy band theory together is put forward to illustrate the intrinsic mechanisms that cause the emission spectral shift, thermal quenching, and luminescence intensity decrease of YAG: Ce upon substitution of Y3+ by Gd3+, which are out of the explanation of the classic configuration coordinate model. The results indicate that in a rigid structure, the charge deformation provides an efficient way to tune chromaticity, but the band gaps and crystal defects must be controlled by comprehensively accounting for luminescence thermal stability and efficiency. PMID:26175141

Effects of Different Combinations of Er:YAG Laser-Adhesives on Enamel Demineralization and Bracket Bond Strength

PubMed Central

Nalçacı, Ruhi; Üşümez, Serdar; Malkoç, Sıddık

2016-01-01

Abstract Objective: The purpose of this study was to investigate the demineralization around brackets and shear bond strength (SBS) of brackets bonded to Er:YAG laser-irradiated enamel at different power settings with various adhesive systems combinations. Methods: A total of 108 premolar teeth were used in this study. Teeth were assigned into three groups according to the etching procedure, then each group divided into three subgroups based on the application of different adhesive systems. There were a total of nine groups as follows. Group 1: Acid + Transbond XT Primer; group 2: Er:YAG (100 mJ, 10 Hz) etching + Transbond XT Primer; group 3: Er:YAG (200 mJ, 10 Hz) etching + Transbond XT Primer; group 4: Transbond Plus self-etching primer (SEP); group 5: Er:YAG (100 mJ, 10 Hz) etching + Transbond Plus SEP; group 6: Er:YAG (200 mJ, 10 Hz) etching + Transbond Plus SEP; group 7: Clearfil Protect Bond; group 8: Er:YAG (100 mJ, 10 Hz) etching + Clearfil Protect Bond; group 9: Er:YAG (200 mJ, 10 Hz) etching + Clearfil Protect Bond. Brackets were bonded with Transbond XT Adhesive Paste in all groups. Teeth to be evaluated for demineralization and SBS were exposed to pH and thermal cyclings, respectively. Then, demineralization samples were scanned with micro-CT to determine lesion depth values. For SBS test, a universal testing machine was used and adhesive remnant was index scored after debonding. Data were analyzed statistically. Results: No significant differences were found among the lesion depth values of the various groups, except for G7 and G8, in which the lowest values were recorded. The lowest SBS values were in G7, whereas the highest were in G9. The differences between the other groups were not significant. Conclusions: Er:YAG laser did not have a positive effect on prevention of enamel demineralization. When two step self-etch adhesive is preferred for bonding brackets, laser etching at 1 W (100 mJ, 10 Hz) is suggested to improve SBS of brackets. PMID:26987047

Effects of Different Combinations of Er:YAG Laser-Adhesives on Enamel Demineralization and Bracket Bond Strength.

PubMed

Çokakoğlu, Serpil; Nalçacı, Ruhi; Üşümez, Serdar; Malkoç, Sıddık

2016-04-01

The purpose of this study was to investigate the demineralization around brackets and shear bond strength (SBS) of brackets bonded to Er:YAG laser-irradiated enamel at different power settings with various adhesive systems combinations. A total of 108 premolar teeth were used in this study. Teeth were assigned into three groups according to the etching procedure, then each group divided into three subgroups based on the application of different adhesive systems. There were a total of nine groups as follows. Group 1: Acid + Transbond XT Primer; group 2: Er:YAG (100 mJ, 10 Hz) etching + Transbond XT Primer; group 3: Er:YAG (200 mJ, 10 Hz) etching + Transbond XT Primer; group 4: Transbond Plus self-etching primer (SEP); group 5: Er:YAG (100 mJ, 10 Hz) etching + Transbond Plus SEP; group 6: Er:YAG (200 mJ, 10 Hz) etching + Transbond Plus SEP; group 7: Clearfil Protect Bond; group 8: Er:YAG (100 mJ, 10 Hz) etching + Clearfil Protect Bond; group 9: Er:YAG (200 mJ, 10 Hz) etching + Clearfil Protect Bond. Brackets were bonded with Transbond XT Adhesive Paste in all groups. Teeth to be evaluated for demineralization and SBS were exposed to pH and thermal cyclings, respectively. Then, demineralization samples were scanned with micro-CT to determine lesion depth values. For SBS test, a universal testing machine was used and adhesive remnant was index scored after debonding. Data were analyzed statistically. No significant differences were found among the lesion depth values of the various groups, except for G7 and G8, in which the lowest values were recorded. The lowest SBS values were in G7, whereas the highest were in G9. The differences between the other groups were not significant. Er:YAG laser did not have a positive effect on prevention of enamel demineralization. When two step self-etch adhesive is preferred for bonding brackets, laser etching at 1 W (100 mJ, 10 Hz) is suggested to improve SBS of brackets.

Linearly polarized pumped passively Q-switched Nd:YVO4 microchip laser for Ince-Gaussian laser modes with controllable orientations

NASA Astrophysics Data System (ADS)

He, Hong-Sen; Zhang, Ming-Ming; Dong, Jun; Ueda, Ken-Ichi

2016-12-01

A tilted, linearly polarized laser diode end-pumped Cr4+:YAG passively Q-switched a-cut Nd:YVO4 microchip laser for generating numerous Ince-Gaussian (IG) laser modes with controllable orientations has been demonstrated by selecting the crystalline orientation of an a-cut Nd:YVO4 crystal. The same IG laser mode with different orientations has been achieved with the same absorbed pump power in a passively Q-switched Nd:YVO4 microchip laser under linearly polarized pumping when the incident pump power and the crystalline orientation of an a-cut Nd:YVO4 crystal are both properly selected. The significant improvement of pulsed laser performance of controllable IG modes has been achieved by selecting the crystalline orientation of an a-cut Nd:YVO4 crystal. The maximum pulse energy is obtained along the a-axis of an a-cut Nd:YVO4 crystal and the highest peak power is achieved along the c-axis of an a-cut Nd:YVO4 crystal, respectively, which has potential applications on quantum computation and optical manipulation. The generation of controllable IG laser modes in microchip lasers under linearly polarized pumping provides a convenient and universal way to control IG laser mode numbers with anisotropic crystal as a gain medium.

Photoablation of the cornea with a Q-switched Er:YAG laser

NASA Astrophysics Data System (ADS)

Lubatschowski, Holger; Hetzel, U.; Kermani, Omid; Ziolek, Carsten; Drommer, Wolfgang; Ertmer, Wolfgang

1997-12-01

In this study the ablation characteristics and the wound healing process of rabbit cornea irradiated with a Q- switched Er:YAG laser was evaluated. The laser, emitting at 2.94 micrometers wavelength, has a pulse width of 100 ns. The spot size on the corneal surface was 1 mm in diameter at a fluence of 750 mJ/cm2. The laser beam was applied by a `flying spot' mode, performing refractive ablations of -7 to -8 dpt. As a biological model, the corneas of 9 rabbits were irradiated. The post-treatment follow-up was as long as 39 days. The treated corneas were investigated by light and electron microscopy. The wound healing on rabbit cornea of the Q-switched Er:YAG laser radiation in corneal tissue processing resembles to what is known from ArF- excimer laser application. To shorten the pulse width by means of Q-switching is one major key to the successful application of the Er:YAG laser for PRK.

Width of thermal damage after using the YAG contact laser for cutting biological tissue: animal experimental investigation.

PubMed

Mecke, H; Schünke, M; Schnaidt, S; Freys, I; Semm, K

1991-01-01

At the University Women's Clinic in Kiel, the YAG contact laser has been used as a cutting instrument in pelviscopic operations since 1987. When the laser cuts, it produces only a scant amount of mechanical trauma. The determining factor is the amount of thermal damage produced along the wound margins and in direct neighboring tissue. The extent of the tissue change seen in the uterus and liver parenchyma of rats and the striated muscle of rabbits after application of the YAG contact laser was demonstrated using various staining techniques and stains. Liver parenchyma proved to be the most sensitive to thermal damage. In the uterine horn, enzyme-histochemical ATPase and alkaline phosphatase demonstrations showed a significantly wider zone of thermal damage after laser incision than did hematoxylin-eosin and Goldner staining techniques. A good understanding of the extent of thermal damage is essential for atraumatic pelviscopic operations using the YAG contact laser and also for the preventing of complications.

Water flow on erbium:yttrium-aluminum-garnet laser irradiation: effects on dental tissues.

PubMed

Colucci, Vivian; do Amaral, Flávia Lucisano Botelho; Pécora, Jesus Djalma; Palma-Dibb, Regina Guenka; Corona, Silmara Aparecida Milori

2009-09-01

Since lasers were introduced in dentistry, there has been considerable advancement in technology. Several wavelengths have been investigated as substitutes for high-speed air turbine. Owing to its high absorbability in water and hydroxyapatite, the erbium:yttrium-aluminum-garnet (Er:YAG) laser has been of great interest among dental practitioners and scientists. In spite of its great potential for hard tissue ablation, Er:YAG laser effectiveness and safety is directly related to an adequate setting of the working patterns. It is assumed that the ablation rate is influenced by certain conditions, such as water content of the target tissue, and laser parameters. It has been shown that Er:YAG irradiation with water coolant attenuates temperature rise and, hence, minimizes the risk of thermally induced pulp injury. It also increases ablation efficiency and enhances adhesion to the lased dental tissue. The aim of this review was to obtain insights into the ablation process and to discuss the effects of water flow on dental tissue ablation using Er:YAG laser.

Temperature rises during application of Er:YAG laser under different primary dentin thicknesses.

PubMed

Hubbezoglu, Ihsan; Unal, Murat; Zan, Recai; Hurmuzlu, Feridun

2013-05-01

The present study investigated the effects of the Er:YAG laser's different pulse repetition rates on temperature rise under various primary dentin thicknesses. The Er:YAG laser can be used for restorative approaches in clinics and is used to treat dental caries. There are some reports that explain the temperature rise effect of the Er:YAG laser. Recently, the Er:YAG laser has been found to play an important role in temperature rises during the application on dentin. Caries-free primary mandibular molars were prepared to obtain dentin discs with 0.5, 1, 1.5, and 2 mm thicknesses (n=10). These discs were placed between the Teflon mold cylinders of a temperature test apparatus. We preferred three pulse repetition rates of 10, 15, and 20 Hz with an energy density of 12.7 J/cm2 and a 230 μs pulse duration. All dentin discs were irradiated for 30 sec by the Er:YAG laser. Temperature rises were recorded using an L-type thermocouple and universal data loggers/scanners (E-680, Elimko Co., Turkey). Data were analyzed by two-way ANOVA and Tukey tests. Whereas the lowest temperature rise (0.44±0.09 °C) was measured from a 10 Hz pulse repetition rate at a dentin thickness of 2 mm, the highest temperature rise (3.86±0.43 °C) was measured from a 20 Hz pulse repetition rate at a 0.5 mm dentin thickness. Temperature rise did not reach critical value for pulpal injury in any primary dentin thicknesses irradiated by a high repetition rate of the Er:YAG laser.

Genotoxic effects of 1064-nm Nd:YAG and 532-nm KTP lasers on fibroblast cell cultures.

PubMed

Senturk, N; Bedir, A; Bilgici, B; Aydin, F; Okuyucu, A; Ozmen, Z C; Turanli, A Y

2010-07-01

Several different laser types are used in cutaneous surgery. The neodymium:yttrium-aluminium-garnet (Nd:YAG) and frequency-doubled Nd:YAG (KTP, potassium titanyl phosphate) lasers are widely used in dermatology. To investigate the possible genotoxic effects on fibroblasts of irradiation with a 1064-nm Nd:YAG laser and a 532-nm KTP laser. Fibroblast cell cultures were exposed to each of the lasers, using 10-mm spot size at 60 ms pulse duration with 10, 20, 40 J/cm(2) and 3, 6, 12 J/cm(2) fluences, respectively. Fibroblasts in passages 1-6 were used. During laser irradiation, 96-well microplate cultures were kept on a cooling block and transported on ice and in the dark, and processed immediately for single-cell gel electrophoresis (SCGE) assay (also known as a comet assay). DNA damage was determined by computerized assessment of comet assay. There was increasing damage with increasing numbers of passages. For the Nd:YAG laser, the greatest damage occurred on passages 5 and 6, whereas the greatest damage appeared at passages 3 and 4 for KTP and returned to baseline at passages 5 and 6. Damage also increased with each dose increment for both wavelengths. At the highest dose for both wavelengths (Nd:YAG 40 J/cm(2) and KTP 12 J/cm(2)), damage was higher with the Nd:YAG laser. Different patterns of cellular damage were seen for different cell-culture passages, treatment doses, and laser wavelengths. These dose ranges are generally used for the treatment of vascular and pigmented lesions and for rejuvenation purposes. As replicative ageing or cell senescence is one of the critical factors determining the extent of cell damage induced by laser therapy, these results may have important implications for clinical practice.

Explanation of the cw operation of the Er3+ 3-μm crystal laser

NASA Astrophysics Data System (ADS)

Pollnau, M.; Graf, Th.; Balmer, J. E.; Lüthy, W.; Weber, H. P.

1994-05-01

A computer simulation of the Er3+ 3-μm crystal laser considering the full rate-equation scheme up to the 4F7/2 level has been performed. The influence of the important system parameters on lasing and the interaction of these parameters has been clarified with multiple-parameter variations. Stimulated emission is fed mainly by up-conversion from the lower laser level and in many cases is reduced by the quenching of the lifetime of this level. However, also without up-conversion a set of parameters can be found that allows lasing. Up-conversion from the upper laser level is detrimental to stimulated emission but may be compensated by cross relaxation from the 4S3/2 level. For a typical experimental situation we started with the parameters of Er3+:LiYF4. In addition, the host materials Y3Al5O12 (YAG), YAlO3, Y3Sc2Al3O12 (YSGG), and BaY2F8, as well as the possibilities of codoping, are discussed. In view of the consideration of all excited levels up to 4F7/2, all lifetimes and branching ratios, ground-state depletion, excited-state absorption, three up-conversion processes as well as their inverse processes, stimulated emission, and a realistic resonator design, this is, to our knowledge, the most detailed investigation of the Er3+ 3-μm crystal laser performed so far.

12 mJ Yb:YAG/Cr:YAG microchip laser

NASA Astrophysics Data System (ADS)

Guo, Xiaoyang; Tokita, Shigeki; Kawanaka, Junji

2018-02-01

By cryogenically cooling the Yb:YAG/Cr:YAG medium, one can break through the damage limit of Yb:YAG/Cr:YAG passively Q-switched microchip lasers at room temperature and thus achieve a shorter minimum pulse duration. In the proof of principle experiment we carried out, a 160.6 ps pulse duration was obtained. To the best of our knowledge, this is the first realization of sub-200 ps pulse operation for an Yb:YAG/Cr:YAG microchip laser

Growth, spectral, thermal, laser damage threshold, microhardness, dielectric, linear and nonlinear optical properties of an organic single crystal: L-phenylalanine DL-mandelic acid

NASA Astrophysics Data System (ADS)

Jayaprakash, P.; Peer Mohamed, M.; Krishnan, P.; Nageshwari, M.; Mani, G.; Lydia Caroline, M.

2016-12-01

Single crystals of L-phenylalanine dl-mandelic acid [C9H11NO2. C8H8O3], have been grown by the slow evaporation technique at room temperature using aqueous solution. The single crystal XRD study confirms monoclinic system for the grown crystal. The functional groups present in the grown crystal have been identified by FTIR and FT-Raman analyses. The optical absorption studies show that the crystal is transparent in the visible region with a lower cut-off wavelength of 257 nm and the optical band gap energy Eg is determined to be 4.62 eV. The Kurtz powder second harmonic generation was confirmed using Nd:YAG laser with fundamental wavelength of 1064 nm. Further, the thermal studies confirmed no weight loss up to 150°C for the as-grown crystal. The photoluminescence spectrum exhibited three peaks (414 nm, 519 nm, 568 nm) due to the donation of protons from carboxylic acid to amino group. Laser damage threshold value was found to be 4.98 GW/cm2. The Vickers microhardness test was carried out on the grown crystals and there by Vickers hardness number (Hv), work hardening coefficient (n), yield strength (σy), stiffness constant C11 were evaluated. The dielectric behavior of the crystal has been determined in the frequency range 50 Hz-5 MHz at various temperatures.

Variation on Molecular Structure, Crystallinity, and Optical Properties of Dentin Due to Nd:YAG Laser and Fluoride Aimed at Tooth Erosion Prevention

PubMed Central

Freitas, Anderson Z.; Bachmann, Luciano; Benetti, Carolina; Ana, Patricia A.

2018-01-01

This in vitro study evaluated the compositional, crystalline, and morphological effects promoted by Nd:YAG laser on root dentin, and verified the effects of laser and topical acidulated phosphate fluoride application (APF-gel) on dentin erosion. 180 bovine dentin slabs were randomized into 4 groups (n = 45): G1–untreated, G2–APF-gel (1.23% F−, 4 min), G3–Nd:YAG (1064 nm, 84.9 J/cm2, 10 Hz), and G4–APF-gel application followed by Nd:YAG laser irradiation. The compositional, crystalline, and morphological effects promoted by treatments were investigated on five samples of each experimental group. The other samples were submitted to a 5-day, 10-day, or 15-day erosive and abrasive demineralization and remineralization cycling in order to create erosion lesions. The area and depth of lesions, as well as the optical attenuation coefficient, were assessed, and all data were statistically analysed (p < 0.05). Nd:YAG laser promoted the reduction of carbonate, the formation of tetracalcium phosphate, as well as the melting and recrystallization of the dentin surface. Laser significantly decreased the area and depth of erosion lesions and altered the optical attenuation coefficient when compared to untreated and APF-gel groups, but the association of APF-gel and laser did not promote an additional effect. Nd:YAG laser irradiation can be a promissory treatment to prevent dentin erosion and the abrasion process. PMID:29389868

The threshold effects of Nd and Ho: YAG laser-induced surface modification on demineralization of dentin surfaces.

PubMed

Kinney, J H; Haupt, D L; Balooch, M; White, J M; Bell, W L; Marshall, S J; Marshall, G W

1996-06-01

Laser irradiation alters the structure of dentin and produces surface layers that give the appearance of being more enamel-like. The laser-modified surface may be more resistant to demineralization; hence, many investigators are proposing continued development of the laser as a possible preventive treatment for caries. The purpose of this study was to explore the morphological changes that occur in dentin when treated at threshold illuminance with two clinically interesting laser wavelengths, and to evaluate the effectiveness of the laser-treated surface at resisting demineralization in an acid-gel solution. The Nd: YAG laser (wavelength 1060 nm) produced significant recrystallization and grain growth of the apatite, without the formation of second phases such as beta-tricalcium phosphate. This recrystallized surface layer showed resistance to demineralization; however, the layer did not provide protection of the underlying dentin from demineralization because of cracks and macroscopic voids that allowed for penetration of the demineralizing gel. The Ho: YAG laser-treated surface (wavelength 2100 nm) did not show significant evidence of recrystallization and grain growth, and only a trace amount of an acid-resistant layer was observed with demineralization. It is speculated that the Ho:YAG laser is coupling with absorbed water, and that the heat transfer from the water to the mineral phase is inefficient. For the purposes of creating a demineralization-resistant layer, threshold illuminance with both Nd: YAG and Ho: YAG was ineffective.

Pulsed Tm:YAG laser ablation of knee joint tissues

NASA Astrophysics Data System (ADS)

Shi, Wei-Qiang; Vari, Sandor G.; Duffy, J. T.; Miller, J. M.; Weiss, Andrew B.; Fishbein, Michael C.; Grundfest, Warren S.

1992-06-01

We investigated the effect of a free-running 2.01 micron pulsed Tm:YAG laser on bovine knee joint tissues. Ablation rates of fresh fibrocartilage, hyaline cartilage, and bone were measured in saline as a function of laser fluence (160 - 640 J/cm2) and fiber core size (400 and 600 microns). All tissues could be effectively ablated and the ablation rate increased linearly with the increasing fluence. Use of fibers of different core sizes, while maintaining constant energy fluence, did not result in significant difference in ablation rate. Histology analyses of the ablated tissue samples reveal average Tm:YAG radiation induced thermal damage (denatunalization) zones ranging between 130 and 540 microns, depending on the laser parameters and the tissue type.

Compact Nd:YAG laser operating at 1.06, 1.32, and 1.44 μm for dental caries effective disinfection

NASA Astrophysics Data System (ADS)

Dostálová, Tat'jana; Jelínková, Helena; Kadlecová, Martina; Němec, Michal; Å ulc, Jan; Fibrich, Martin; Nejezchleb, Karel; Kapitch, Nickalai; Å koda, Václav

2017-02-01

The analysis of the disinfection effect of Nd:YAG laser radiation was investigated for patients with high concentration of Streptococcus mutans in saliva (positive result in Saliva-check mutans test). For the interaction the Nd:YAG laser system generated separate switchable wavelengths with the maximum output energies 1.1, 0.6, and 0.3 J for wavelength 1.06 μm, 1.32, μm and 1.44 μm, respectively, was used. Our study proved that after the laser irradiation the Saliva-check test showed negative presence of Streptococcus mutans. The disinfection effect was confirmed for all used radiation wavelength. For 1.44 μm this effect was reached with a smallest energy density.

Laser emission from diode-pumped Nd:YAG ceramic waveguide lasers realized by direct femtosecond-laser writing technique.

PubMed

Salamu, Gabriela; Jipa, Florin; Zamfirescu, Marian; Pavel, Nicolaie

2014-03-10

We report on realization of buried waveguides in Nd:YAG ceramic media by direct femtosecond-laser writing technique and investigate the waveguides laser emission characteristics under the pump with fiber-coupled diode lasers. Laser pulses at 1.06 μm with energy of 2.8 mJ for the pump with pulses of 13.1-mJ energy and continuous-wave output power of 0.49 W with overall optical efficiency of 0.13 were obtained from a 100-μm diameter circular cladding waveguide realized in a 0.7-at.% Nd:YAG ceramic. A circular waveguide of 50-μm diameter yielded laser pulses at 1.3 μm with 1.2-mJ energy.

CO2 and Er:YAG laser interaction with grass tissues

NASA Astrophysics Data System (ADS)

Kim, Jaehun; Ki, Hyungson

2013-01-01

Plant leaves are multi-component optical materials consisting of water, pigments, and dry matter, among which water is the predominant constituent. In this article, we investigate laser interaction with grass using CO2 and Er:YAG lasers theoretically and experimentally, especially targeting water in grass tissues. We have first studied the optical properties of light absorbing constituents of grass theoretically, and then have identified interaction regimes and constructed interaction maps through a systematic experiment. Using the interaction maps, we have studied how interaction regimes change as process parameters are varied. This study reveals some interesting findings concerning carbonization and ablation mechanisms, the effect of laser beam diameter, and the ablation efficiency and quality of CO2 and Er:YAG lasers.

Scanning electron microscopy investigation of PMMA removal by laser irradiation (Er:YAG) in comparison with an ultrasonic system and curettage in hip joint revision arthroplasty.

PubMed

Birnbaum, Klaus; Gutknecht, Norbert

2010-07-01

The cement often left in the femur socket during hip joint revision arthroplasty is usually removed by curettage. Another method for removing the cement is to use an ultrasonic system, and yet another alternative may be to use a laser system. The aim of these investigations was to determine the pulse rate and pulse energy of the Er:YAG laser for sufficient cement ablation. We also compared the results obtained using the laser with those obtained using an ultrasonic device or curettage by histological and scanning electron microscopy (SEM) investigation of the border zone between the polymethyl methacrylate (PMMA) and unfixed specimens of femoral bone. Therefore we prepared 30 unfixed human femur stems after hip joint replacement and prepared ten sagittal sections from each femur stem (in total 300 sections). Of these 300 specimens, 180 were treated with the Er:YAG laser, 60 with the ultrasonic system and 60 by curettage. The high pulse energy of 500 mJ and a pulse rate of 4 Hz provided the highest PMMA ablation rate, although the boundary surface between PMMA and femoral bone was not as fine-grained as found in samples treated at 15 Hz and 250 mJ. However, the treatment time for the same cement ablation rate with the latter settings was twice that at 4 Hz and 500 mJ. Compared to the boundary surfaces treated with the ultrasonic device or curettage, the laser-treated samples had a more distinct undifferentiated boundary surface between PMMA and femoral bone. After development of the Er:YAG-laser to provide higher pulse energies, it may in the future be an additional efficient method for the removal of PMMA in revision arthroplasty. The Er:YAG laser should be combined with an endoscopic and a rinsing suction system so that PMMA can be removed from the femoral shaft under direct vision.

Properties of Lu3Al5O12, Lu3Al5O12:Pr, Lu3Al5O12:Pr,Mo, and (Lu1-x Y x )3Al5O12:Pr scintillator crystals

NASA Astrophysics Data System (ADS)

Talik, E.; Kusz, J.; Guzik, A.; Szubka, M.; Balin, K.; Kisielewski, J.; Wierzchowski, W.; Malinowska, A.; Strojny-Nedza, A.; Pajaczkowska, A.; Drozdowski, W.

2017-05-01

Lattice parameters, magnetic susceptibility, electronic structure, distribution of the elements and thermal properties were examined for single crystals of Lu3Al5O12 (LuAG) and (Lu1-x Y x )3Al5O12 (LuYAG) (x  =  0.25, 0.50, 0.75), either pure or doped with Pr and optionally co-doped with Mo, which are predicted as potential fast and efficient scintillators. It was indicated that specific cage-like surrounding of rare earth and aluminum ions built from oxygen ions and proper doping can influence the thermal conductivity and the emission process. Maximum light emission (LY) was observed at praseodymium concentration about 0.3 at.%. The growth atmosphere (Ar or N2) influences the crystal quality. Additional molybdenum doping below 0.01 at% concentration increases LY.

Spectroscopic, Homo-Lumo and NLO studies of tetra fluoro phthalate doped Coumarin crystals using DFT method

NASA Astrophysics Data System (ADS)

Latha, B.; Kumaresan, P.; Nithiyanantham, S.; Sampathkumar, K.

2017-08-01

In the present examination, a methodical study has been done on the development of unadulterated and Coumarin doped Tetrafluoro Phthalate precious stones. Powder X-beam diffraction studies were done and the cross section parameters were computed by minimum square technique in pure and doped crystals. FT-IR, UV-Vis, Thermal, Micro-hardness and Dielectric studies were additionally done for the pure and doped crystals. The tentatively watched FT-IR and FT-Raman groups were allotted to various ordinary methods of the atom. The steadiness and charge delocalization of the particle were likewise concentrations were done by characteristic security orbital (NBO) examination. The HOMO-LUMO energies depict the charge exchange happens inside the particle. Atomic electrostatic potential has been broken down the electronic properties such as excitation energies, oscillator quality, wavelengths and HOMO-LUMO energies were acquired by time-subordinate DFT (TD-DFT) approach. The SHG of pure and doped TFP stones were examined through Nd:YAG Q-exchanged laser.

Generation and use of high power 213 nm and 266 nm laser radiation and tunable 210-400 nm laser radiation with BBO crystal matrix array

DOEpatents

Gruen, Dieter M.

2000-01-01

A 213 nm laser beam is capable of single photon ablative photodecomposition for the removal of a polymer or biological material substrate. Breaking the molecular bonds and displacing the molecules away from the substrate in a very short time period results in most of the laser photon energy being carried away by the displaced molecules, thus minimizing thermal damage to the substrate. The incident laser beam may be unfocussed and is preferably produced by quintupling the 1064 nm radiation from a Nd:YAG solid state laser, i.e., at 213 nm. In one application, the 213 nm laser beam is expanded in cross section and directed through a plurality of small beta barium borate (BBO) crystals for increasing the energy per photon of the laser radiation directed onto the substrate. The BBO crystals are arranged in a crystal matrix array to provide a large laser beam transmission area capable of accommodating high energy laser radiation without damaging the BBO crystals. The BBO crystal matrix array may also be used with 266 nm laser radiation for carrying out single or multi photon ablative photodecomposition. The BBO crystal matrix array may also be used in an optical parametric oscillator mode to generate high power tunable laser radiation in the range of 210-400 nm.

Theoretical and experimental study on reabsorption effect and temperature characteristic of a quasi-three-level 946nm Nd:YAG laser

NASA Astrophysics Data System (ADS)

Huang, Jing; Wan, Yuan; Chen, Weibiao

2015-02-01

The influence of temperature and incident pump power on reabsorption loss is theoretically discussed. Temperature characteristic and reabsorption loss rate of a diode-pumped quasi-three-level 946 nm Nd:YAG laser are investigated. Reabsorption effect has a significant impact on laser performance. The results indicate that reabsorption loss increases as the working temperature rises and decreases with the increased incident pump power.

Investigation of luminescence from LuAG: Mn4+ for physiological temperature sensing

NASA Astrophysics Data System (ADS)

Li, Fei; Cai, Jiajia; Chi, FengFeng; Chen, Yonghu; Duan, Changkui; Yin, Min

2017-04-01

Optical thermometry based on luminescent materials has garnered much attention due to its many advantages. But higher sensitivity is still expected in physiological temperature range which is of special significance in medicine and biology. For this purpose, quadrivalent manganese doped lutetium aluminum garnet, Lu3Al5O12: Mn4+, or simply LuAG: Mn4+, has been successfully synthesized by sol-gel method and its temperature dependent luminescence has been investigated in the present work. Compared to the common red emission phosphors Y3Al5O12: Mn4+ (YAG:Mn4+) with same structure, LuAG:Mn4+ has a stronger crystal field strength and a higher thermal-quenching activation energy (ΔE) of 5732 cm-1. Rapid thermal quenching of the Mn4+ luminescence occurred above room temperature around 90 °C for our LuAG:Mn4+ sample. Temperature dependent decay curves of Mn4+ emission from LuAG:Mn4+ revealed that an extraordinary high sensitivity can be achieved from luminescence lifetime measurements covering physiological temperature range with a sensitivity of 3.75% K-1 at 38 °C.

The KTP-(greenlight-) laser--principles and experiences.

PubMed

Bachmann, Alexander; Ruszat, Robin

2007-01-01

The most recent advance in laser technology for transurethral prostatectomy is represented by the KTP laser. A potassium-titanyl-phosphate-(KTP-) crystal doubles the frequency of pulsed Neodymium: Yttrium-Aluminum-Garnet (Nd:YAG) laser energy to a 532 nm wavelength, which is in the green electromagnetic spectrum (Greenlight-laser) and is selectively absorbed by hemoglobin and not at all by water. Reducing the wavelength leads to a completely different interaction between laser beam and prostatic tissue. In contrast to the early clinical experiences with the Nd:YAG lasers in which vaporization was observed as a side-effect during the procedure, the new KTP laser offers an immediate and efficient vaporization, leading to real tissue ablation. Because of the instant and nearly complete absorption in blood, the depth in vascularized tissue such as prostate is only 0.8 mm. The superficial coagulation prevents the large tissue necrosis that is seen with the Nd:YAG laser, leading to long lasting irritative symptoms due to sloughing of necrotic tissue. Initial experiences, made with a 60W KTP system, demonstrated that the procedure was as effective as conventional transurethral resection of the prostate (TURP) with a lower intraoperative complication rate. In order to speed up vaporization of the prostate laser power has been increased to 80W. The 80W KTP laser combines the tissue debulking properties of TURP and the favourable safety profile of laser surgery. With the new 120W High Performance System, introduced in 2006, vaporization will become more powerful and faster. Initial reports are awaited.

Repetitively Q-switched Nd:BeL lasers

NASA Technical Reports Server (NTRS)

Degnan, J.; Birnbaum, M.; Deshazer, L. G.

1979-01-01

The thermal and mechanical characteristics which will ultimately limit the performance of Nd:BeL at high average power levels were investigated. The output beam characteristics (pulse width, peak power, beam dimensions and collimation) were determined at high repetition rates for both Nd:BeL and Nd:YAG. The output of Nd:BeL was shown to exceed that of Nd:YAG by a factor of 2.7 at low Q-switched repetition rates (1 Hz). This result follows from the smaller stimulated emission cross section of x-axis Nb:BeL compared to that of NdYAG by the same factor. At high repetition rates (10 Hz) the output of Nd:Bel falls to a level of three-fifths of its low repetition rate value while under similar tests the output of Nd:YAG remains essentially constant. A comparison of the measured values of the elasto-optic coefficients, the dn/dT values and the linear expansion coefficients for BeL and YAG failed to provide an explanation for the performance of BeL; however, thermal lensing was observed in Nd:BeL. Results imply that the output of a high repetition rate Q-switched Nd:BeL laser (high thermal loading) could be dramatically increased by utilization of a resonator design to compensate for the thermal lensing effects.

Dissipative Structures At Laser-Solid Interactions

NASA Astrophysics Data System (ADS)

Nanai, Laszlo

1989-05-01

The questions which are discussed in this lecture refer to one of sections of laser-solid interactions, namely: to formation of different dissipative structures on the surface of metals and semiconductors when they are irradiated by intensive laser light in chemically active media (f.e.air). Some particular examples of the development at different spatial and time instabilities, periodic and stochastic structures, auto-wave processes are present-ed using testing materials vanadium metal and semiconducting V205 single crystals and light sources: cw and pulsed CO2 and YAG lasers.

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

PubMed

Maeda, Y

1994-06-20

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

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

NASA Astrophysics Data System (ADS)

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

2003-10-01

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

Bibliography of Soviet Laser Developments, Number 65, May - June 1983.

DTIC Science & Technology

1984-05-15

crystals pumped by e -beam. ZhPS, v . 38, no. 5, 1983, 752-755. 3. Golyayev, Yu.D., and S.V. Lantratov (0). Active mode locking in c-w neodymium YAG...Bagayev, S.N., S.V. Mal’tsev, and V.P. Chebotayev (159). Nonlinear resonant shift in methane at the E -line (v3 baud P(7) transition). ZhETF P, v . 37, no...anisotropic resonator. QiS, v . 54, no. 5, 1983, 874-876. 616. Jankowska, E . (NS). Applijcab iiyo oorpi n pcl interferometries in t hep late bendin

Recent advancements in anti-reflective surface structures (ARSS) for near- to mid-infrared optics

NASA Astrophysics Data System (ADS)

Florea, Catalin M.; Busse, Lynda E.; Bayya, Shyam S.; Shaw, Brandon; Aggarwal, Ish D.; Sanghera, Jas S.

2013-06-01

Fused silica, YAG crystals, and spinel ceramics substrates have been successfully patterned through reactive ion etching (RIE). Reflection losses as low as 0.1% have been demonstrated for fused silica at 1.06 microns. Laser damage thresholds have been measured for substrates with ARSS and compared with uncoated and/or thin-film anti-reflection (AR) coated substrates. Thresholds as high as 100 J/cm2 have been demonstrated in fused silica with ARSS at 1.06 microns, with ARSS substrates showing improved thresholds when compared with uncoated substrates.

Indocyanine green-augmented diode laser therapy vs. long-pulsed Nd:YAG (1064 nm) laser treatment of telangiectatic leg veins: a randomized controlled trial.

PubMed

Klein, A; Buschmann, M; Babilas, P; Landthaler, M; Bäumler, W

2013-08-01

Telangiectatic leg veins (TLV) represent a common cosmetic problem. Near infrared lasers have been widely used in treatment because of their deeper penetration into the dermis, but with varying degrees of success, particularly because of different vessel diameters. Indocyanine green (ICG)-augmented diode laser treatment (ICG+DL) may present an alternative treatment option. This trial evaluates the efficacy of ICG+DL in the treatment of TLV and compares the safety and efficacy of therapy with the standard treatment, the long-pulsed neodymium-doped yttrium aluminium garnet (Nd:YAG) laser. In a prospective randomized controlled clinical trial, 29 study participants with TLV were treated with a Nd:YAG laser (λem = 1064 nm, 160-240 J cm(-2) , 65-ms pulse duration, 5-mm spot size) and ICG+DL (λem = 810 nm, 60-110 J cm(-2) , 48-87-ms pulse duration, 6-mm spot size; total ICG dose 4 mg kg(-1) ) in a side-by-side comparison in one single treatment setting that included histological examination in four participants. Two blinded investigators and the participants assessed clearance rate, cosmetic appearance and adverse events up to 3 months after treatment. According to both the investigators' and participants' assessment, clearance rates were significantly better after ICG+DL therapy than after Nd:YAG laser treatment (P < 0·05). On a 10-point scale indicating pain during treatment, participants rated ICG+DL therapy to be more painful (6·1 ± 2·0) than Nd:YAG laser (5·4 ± 2·0). ICG+DL therapy represents a new and promising treatment modality for TLV, with high clearance rates and a very good cosmetic outcome after one single treatment session. © 2013 British Association of Dermatologists.

Soft x-ray free-electron laser induced damage to inorganic scintillators

DOE PAGES

Burian, Tomáš; Hájková, Věra; Chalupský, Jaromír; ...

2015-01-07

An irreversible response of inorganic scintillators to intense soft x-ray laser radiation was investigated at the FLASH (Free-electron LASer in Hamburg) facility. Three ionic crystals, namely, Ce:YAG (cerium-doped yttrium aluminum garnet), PbWO4 (lead tungstate), and ZnO (zinc oxide), were exposed to single 4.6 nm ultra-short laser pulses of variable pulse energy (up to 12 μJ) under normal incidence conditions with tight focus. Damaged areas produced with various levels of pulse fluences, were analyzed on the surface of irradiated samples using differential interference contrast (DIC) and atomic force microscopy (AFM). The effective beam area of 22.2 ± 2.2 μm2 was determinedmore » by means of the ablation imprints method with the use of poly(methyl methacrylate) - PMMA. Applied to the three inorganic materials, this procedure gave almost the same values of an effective area. The single-shot damage threshold fluence was determined for each of these inorganic materials. The Ce:YAG sample seems to be the most radiation resistant under the given irradiation conditions, its damage threshold was determined to be as high as 660.8 ± 71.2 mJ/cm2. Contrary to that, the PbWO4 sample exhibited the lowest radiation resistance with a threshold fluence of 62.6 ± 11.9 mJ/cm2. The threshold for ZnO was found to be 167.8 ± 30.8 mJ/cm2. Both interaction and material characteristics responsible for the damage threshold difference are discussed in the article.« less

Efficient bone cutting with the novel diode pumped Er:YAG laser system: in vitro investigation and optimization of the treatment parameters

NASA Astrophysics Data System (ADS)

Stock, Karl; Diebolder, Rolf; Hausladen, Florian; Hibst, Raimund

2014-03-01

It is well known that flashlamp pumped Er:YAG lasers allow efficient bone ablation due to strong absorption at 3μm by water. Preliminary experiments revealed also a newly developed diode pumped Er:YAG laser system (Pantec Engineering AG) to be an efficient tool for use for bone surgery. The aim of the present in vitro study is the investigation of a new power increased version of the laser system with higher pulse energy and optimization of the treatment set-up to get high cutting quality, efficiency, and ablation depth. Optical simulations were performed to achieve various focus diameters and homogeneous beam profile. An appropriate experimental set-up with two different focusing units, a computer controlled linear stage with sample holder, and a shutter unit was realized. By this we are able to move the sample (slices of pig bone) with a defined velocity during the irradiation. Cutting was performed under appropriate water spray by moving the sample back and forth. After each path the ablation depth was measured and the focal plane was tracked to the actual bottom of the groove. Finally, the cuts were analyzed by light microcopy regarding the ablation quality and geometry, and thermal effects. In summary, the results show that with carefully adapted irradiation parameters narrow and deep cuts (ablation depth > 6mm, aspect ratio approx. 20) are possible without carbonization. In conclusion, these in vitro investigations demonstrate that high efficient bone cutting is possible with the diode pumped Er:YAG laser system using appropriate treatment set-up and parameters.

Sub-nanosecond periodically poled lithium niobate optical parametric generator and amplifier pumped by an actively Q-switched diode-pumped Nd:YAG microlaser

NASA Astrophysics Data System (ADS)

Liu, L.; Wang, H. Y.; Ning, Y.; Shen, C.; Si, L.; Yang, Y.; Bao, Q. L.; Ren, G.

2017-05-01

A sub-nanosecond seeded optical parametric generator (OPG) based on magnesium oxide-doped periodically poled lithium niobate (MgO:PPLN) crystal is presented. Pumped by an actively Q-switched diode-pumped 1 kHz, 1064 nm, Nd:YAG microlaser and seeded with a low power distributed feedback (DFB) diode continuous-wave (CW) laser, the OPG generated an output energy of 41.4 µJ and 681 ps pulse duration for the signal at 1652.4 nm, achieving a quantum conversion efficiency of 61.2% and a slope efficiency of 41.8%. Signal tuning was achieved from 1651.0 to 1652.4 nm by tuning the seed-laser current. The FWHM of the signal spectrum was approximately from 35 nm to 0.5 nm by injection seed laser. The SHG doubled the frequency of OPG signal to produce a output energy of 12 µJ with the energy conversion efficiency of 29.0% and tunanble wavelength near 826 nm.

Optical and structural properties of Bi-based nanoparticles prepared via pulsed Nd:YAG laser ablation in organic liquids

NASA Astrophysics Data System (ADS)

Dadashi, S.; Poursalehi, R.; Delavari, H.

2018-06-01

Colloidal Bi/Bi2O3 and single phase Bi nanoparticles were synthesized by pulsed Nd:YAG laser ablation of metallic bismuth target in different organic liquids. In this research, the structural characteristic, optical properties, and colloidal stability of Bi and Bi/Bi2O3 nanoparticles have been studied. Furthermore, the mechanism of nanoparticles formation in liquid media by laser ablation of Bi-based nanoparticles was proposed in different liquid environments based on their chemical nature. X-ray diffraction, scanning electron microscopy and optical extinction spectroscopy indicate the formation of pure Bi and Bi/Bi2O3 nanoparticles with mean size of 32, 43 and 54 nm in methanol, ethanol, and EMK, respectively, which indicate a mixture of different phases including rhombohedra crystal structure of Bi, monoclinic α-Bi2O3, and tetragonal β-Bi2O3. Finally, this research demonstrates the effect of the surrounding environment on characteristic properties of nanoparticles and clarifies the size, structural characteristics, and optical properties of the synthesized nanoparticles.

Diode pumped solid-state laser oscillators for spectroscopic applications

NASA Technical Reports Server (NTRS)

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

1987-01-01

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

Improving solar-pumped laser efficiency by a ring-array concentrator

NASA Astrophysics Data System (ADS)

Tibúrcio, Bruno D.; Liang, Dawei; Almeida, Joana; Matos, Rodrigo; Vistas, Cláudia R.

2018-01-01

We report here a compact pumping scheme for achieving large improvement in collection and conversion efficiency of a Nd:YAG solar-pumped laser by an innovative ring-array solar concentrator. An aspheric fused silica lens was used to further concentrate the solar radiation from the focal region of the 1.5-m-diameter ring-array concentrator to a 5.0-mm-diameter, 20-mm-length Nd:YAG single-crystal rod within a conical-shaped pump cavity, enabling multipass pumping to the laser rod. 67.3-W continuous-wave solar laser power was numerically calculated, corresponding to 38.2-W / m2 solar laser collection efficiency, being 1.22 and 1.27 times more than the state-of-the-art records by both heliostat-parabolic mirror and Fresnel lens solar laser systems, respectively. 4.0% conversion efficiency and 0.021-W brightness figure of merit were also numerically obtained, corresponding to 1.25 and 1.62 times enhancement over the previous records, respectively. The influence of tracking error on solar laser output power was also analyzed.

A new solid-state, frequency-doubled neodymium-YAG photocoagulation system.

PubMed

Jalkh, A E; Pflibsen, K; Pomerantzeff, O; Trempe, C L; Schepens, C L

1988-06-01

We have developed a solid-state laser system that produces a continuous green monochromatic laser beam of 532 nm by doubling the frequency of a neodymium-YAG laser wavelength of 1064 nm with a potassium-titamyl-phosphate crystal. Photocoagulation burns of equal size and intensity were placed in two rabbit eyes with the solid-state laser system and the regular green argon laser system, respectively, using the same slit-lamp mode of delivery. Histologic findings of lesion sections revealed no important differences between the two systems. In theory, the longer wavelength of the solid-state laser offers the advantages of less scattering in ocular media, higher absorption by oxyhemoglobin, and less absorption by macular xanthophyll than the 514-nm wavelength of the regular green argon laser. The solid-state laser has impressive technical advantages: it contains no argon-ion gas tube that wears out and is expensive to replace; it is much more power efficient, and thus considerably smaller and compact; it is sturdier and easily movable; it does not require external cooling; it uses a 220-V monophasic alternating current; and it requires little maintenance.

Crystal growth, structural, optical, thermal, mechanical, laser damage threshold and electrical properties of triphenylphosphine oxide 4-nitrophenol (TP4N) single crystals for nonlinear optical applications

NASA Astrophysics Data System (ADS)

Karuppasamy, P.; Senthil Pandian, Muthu; Ramasamy, P.; Verma, Sunil

2018-05-01

The optically good quality single crystals of triphenylphosphine oxide 4-nitrophenol (TP4N) with maximum dimension of 15 × 10 × 5 mm3 were grown by slow evaporation solution technique (SEST) at room temperature. The cell dimensions of the grown TP4N crystal were confirmed by single crystal X-ray diffraction (SXRD) and the crystalline purity was confirmed and planes were indexed by powder X-ray diffraction (PXRD) analysis. Functional groups of TP4N crystal were confirmed by Fourier transform infrared (FTIR) spectral analysis. The optical transmittance of the grown crystal was determined by the UV-Vis NIR spectral analysis and it has good optical transparency in the entire visible region. The band tail (Urbach) energy of the grown crystal was analyzed and it appears to be minimum, which indicates that the TP4N has good crystallinity. The position of valence band (Ev) and conduction band (Ec) of the TP4N have been determined from the electron affinity energy (EA) and the ionization energy (EI) of its elements and using the optical band gap. The thermal behaviour of the grown crystal was investigated by thermogravimetric and differential thermal analysis (TG-DTA). Vickers microhardness analysis was carried out to identify the mechanical stability of the grown crystal and their indentation size effect (ISE) was explained by the Meyer's law (ML), Hays-Kendall's (HK) approach, proportional specimen resistance (PSR) model, modified PSR model (MPSR), elastic/plastic deformation (EPD) model and indentation induced cracking (IIC) model. Chemical etching study was carried out to find the etch pit density (EPD) of the grown crystal. Laser damage threshold (LDT) value was measured by using Nd:YAG laser (1064 nm). The dielectric permittivity (ε՛) and dielectric loss (tan δ) as a function of frequency was measured. The electronic polarizability (α) of the TP4N crystal was calculated. It is well matched to the value which was calculated from Clausius-Mossotti relation, Lorentz-Lorentz equation, optical band gap and coupled dipole method (CDM). The Z-scan technique was carried out using solid state laser (640 nm) to analyze the nonlinear optical properties of the TP4N crystal. It exhibits the self-defocusing and saturable absorbance effect during analysis of closed and open aperture respectively. The nonlinear optical parameters such as refractive index (n2), absorption coefficient (β) and the third order nonlinear optical susceptibility (χ(3)) were analyzed.

Wavelength comparison for laser induced breakdown spectroscopy caries detection

NASA Astrophysics Data System (ADS)

Amaral, Marcello M.; Raele, Marcus P.; Ana, Patrícia A.; Núñez, Sílvia C.; Zamataro, Claudia B.; Zezell, Denise M.

2018-02-01

Laser Induced Breakdown Spectroscopy (LIBS) is a technique capable to perform elemental analyses of a variety of samples, independent of matter state. Other spectroscopy techniques may require a destructive and time-consuming sample preparation. On the other hand, LIBS is a less destructive technique with no (or considerably less) sample preparation, using a relatively simple experimental setup. LIBS also provides a multielement analysis into one single spectrum acquisition, applying a Nd:YAG short-pulsed laser to ensure the stoichiometry between the sample and the generated plasma. LIBS have been applied on the study of carious lesions using a Nd:YAG into its fundamental emission at 1064 nm. It was shown that ratio of P/Ca and Zn/Ca can be used to monitor the cariogenic process. Another minor elements, e.g. C and Cu, associated with bacteria biofilm were also measured with the Nd:YAG laser. The fundamental wavelength emission (1064 nm) of Nd:YAG is coincident with a hydroxyapatite transmission window and it may affect the result. In order to address this issue a study used the second harmonic of the Nd:YAG laser at 532 nm. It was show that it is also possible perform LIBS on carious lesion using the Nd:YAG at 532 nm. However, there is not a work direct comparing the LIBS at 532 nm and 1064 nm for carious lesion detection. So, the aim of this work was to investigate the influence of laser wavelength on the LIBS performance for carious lesion detection. In both cases the carious lesion was detected with the advantage of no interference with hydroxyapatite at 532 nm.

Evaluation of crystalline changes and resistance to demineralization of the surface of human dental enamel treated with Er:YAG laser and fluoride using x-ray diffraction analysis and Vickers microhardness

NASA Astrophysics Data System (ADS)

Behroozibakhsh, Marjan; Shahabi, Sima; Ghavami-Lahiji, Mehrsima; Sadeghian, Safura; Sadat Faal Nazari, Neda

2018-06-01

This study aimed to investigate the changes in crystalline structure and resistance to demineralization of human dental surface enamel treated with erbium-doped yttrium aluminium garnet laser (Er:YAG) laser and fluoride. The enamel surfaces were divided into four groups according to the treatment process including, (L): irradiated with Er:YAG; (F): treated with acidulated phosphate fluoride gel (LF): Pre-irradiated surfaces with Er:YAG subjected to acidulated phosphate fluoride gel and (FL): laser irradiation was performed on the fluoridated enamel surface. Before and after the treatment procedure, the samples were evaluated using X-ray diffraction, scanning electron microscope (SEM) and the Vickers microhardness test. The surface microhardness values also were measured after a pH-cycling regime and acid challenge. The a-axis of all lased groups was contracted after treatment procedure. Measurement of the area under the peaks showed the highest crysallinity in the FL group. The hardness values of all laser treated samples significantly reduced after treatment procedure compared to the F group (p  ⩽  0.001). The morphological observations showed remarkable changes on the lased enamel surfaces including cracks, craters and exposed prisms. These findings suggest, irradiation of the Er:YAG laser accompanying with fluoride application can induce some beneficial crystalline changes regarding the acid-resistance properties of enamel, however, the craters and cracks produced by laser irradiation can promote enamel demineralization and consequently the positive effects of the Er:YAG laser will be eliminated.

Preparation and characterization of highly transparent Nd:YAG/YAG composite ceramics

NASA Astrophysics Data System (ADS)

Ma, Benyuan; Zhang, Wei; Shen, Bizhou; Wang, Yuezhong; Song, Haizhi; Li, Feng; Xie, Xiumin; Zhang, Zhibin; Yang, Yongqiang; Guan, Zhouguo

2018-05-01

Using the co-precipitated Nd:YAG and YAG powders as raw materials, the Nd:YAG/YAG composite ceramics (Ф 50 mm × 5 mm) were prepared by vacuum sintering (1790 °C 50 h), followed by hot isostatic pressing (HIP) post treatment (1700 °C 2 h, 200 MPa Ar atmosphere) and air annealing (1250 °C 100 h). The optical properties of Nd:YAG/YAG samples were improved markedly by HIP post-treatment, mainly due to the elimination of residual pores in the samples. The composite sample showed a perfect bonding interface from Nd:YAG to YAG regions without obvious grain size difference, pores or other defects. This structure should be responsible for the thermal conductivity larger than that of non-composite sample. The composite sample revealed good optical properties with transmittance up to 83.9% at 1064 nm and 80.8% at 400 nm, and a maximum laser output power of 1.38 KW with the slope efficiency of 36.7% was obtained.

High power lasers for gamma source

NASA Astrophysics Data System (ADS)

Durand, Magali; Sangla, Damien; Trophème, Benoit; Sevillano, Pierre; Casanova, Alexis; Caillon, Laurianne; Courjaud, Antoine

2017-02-01

A high intensity Gamma source is required for Nuclear Spectroscopy, it will be delivered by the interaction between accelerated electron and intense laser beams. Those two interactions lasers are based on a multi-stage amplification scheme that ended with a second harmonics generation to deliver 200 mJ, 3.5 ps pulses at 515 nm and 100 Hz. A t-Pulse oscillator with slow and fast feedback loop implemented inside the oscillator cavity allows the possibility of synchronization to an optical reference. A temporal jitter of 120 fs rms is achieved, integrated from 10 Hz to 10 MHz. Then a regenerative amplifier, based on Yb:YAG technology, pumped by fiber-coupled QCW laser diodes, delivers pulses up to 30 mJ. The 1 nm bandwidth was compressed to 1.5 ps with a good spatial quality: M2 of 1.1. This amplifier is integrated in a compact sealed housing (750x500x150 cm), which allows a pulse-pulse stability of 0.1% rms, and a long-term stability of 1,9% over 100 hours (with +/-1°C environment). The main amplification stage uses a cryocooled Yb:YAG crystal in an active mirror configuration. The crystal is cooled at 130 K via a compact and low-vibration cryocooler, avoiding any additional phase noise contribution, 340 mJ in a six pass scheme was achieved, with 0.9 of Strehl ratio. The trade off to the gain of a cryogenic amplifier is the bandwidth reduction, however the 1030 nm pulse was compressed to 3.5 ps.

12  mJ Yb:YAG/Cr:YAG microchip laser.

PubMed

Guo, Xiaoyang; Tokita, Shigeki; Kawanaka, Junji

2018-02-01

We have developed a quasi-continuous wave diode end-pumped cryogenically cooled Yb:YAG/Cr:YAG passively Q-switched microchip laser. A maximum energy of 12.1 mJ with 3.7 MW of peak power was obtained. To the best of our knowledge, this is the highest energy and peak power obtained by an Yb:YAG/Cr:YAG microchip laser so far.

HAZ and Structural Defects Control in Key-Hole Welding of Titanium Using a Reptitively-Pulsed Nd: Yag Laser

NASA Astrophysics Data System (ADS)

Hamudi, Walid K.

1996-12-01

HAZ, porosity and cracks were investigated when welding 0.9 mm thick titanium sheets using a 10 J pulsed Nd: Yag laser. The effects of welding speed, joints fit-up, shielding gas, and laser parameters are presented. For optimum welding quality, 0.25 m/min scanning speed, 10 ℓ/min gas flow rate and 72 Watt average power were used. Welds of narrow heat affected zone (HAZ) with small level of porosity were obtained.

Resonantly diode-pumped Er:YAG laser: 1470-nm versus 1530-nm CW pumping case

NASA Astrophysics Data System (ADS)

Kudryashov, Igor; Ter-Gabrielyan, Nikolai; Dubinskii, Mark

2009-05-01

Growing interest to high power lasers in the eye-safe spectral domain initiated a new wave of activity in developing solid-state lasers based on bulk Er3+-doped materials. The resonant pumping of SSL allows for shifting significant part of thermal load from gain medium itself to the pump diodes, thus greatly reducing gain medium thermal distortions deleterious to SSL power scaling with high beam quality. The two major resonant pumping bands in Er:YAG are centered around 1470 and 1532 nm. Pumping into each of these bands has its pros and contras. The best approach to resonant pumping of Er:YAG active media in terms of pump wavelength is yet to be determined. We report the investigation results of high power diode-pumped Er:YAG laser aimed at direct comparison of resonant pumping at 1470 and 1532 nm. Two sources used for pumping were: 1530-nm 10-diode bar stack (>300 W CW) and 1470-nm 10-diode bar stack (>650 W CW). Both pumps were spectrally narrowed by external volume Bragg gratings. The obtained spectral width of less than 1 nm allowed for 'in-line' pumping of Er3+ in either band. The obtained CW power of over 87 W is, to the best of our knowledge, the record high power reported for resonantly pumped Er:YAG DPSSL at room temperature.

Effect of Various Laser Wavelengths on Temperature Changes During Periimplantitis Treatment: An in vitro Study.

PubMed

Monzavi, Abbas; Fekrazad, Reza; Chinipardaz, Zahra; Shahabi, Sima; Behruzi, Roohollah; Chiniforush, Nasim

2018-06-01

This study aimed to investigate and compare temperature change during implant decontamination with different laser types (carbon dioxide [Co2]/diode/neodymium-doped yttrium aluminum garnet [Nd:YAG]/erbium-doped yttrium aluminum garnet [Er:YAG]/antimicrobial photodynamic therapy [aPDT]). Sixty implants were inserted into a bone block cut from a sheep's mandible. A 3 × 8 mm vertical lesion was made at the buccal of each implant. The bone block was placed into a 37°C water bath to simulate the in vivo oral condition. A K-type thermocouple was placed in contact with the implant to register temperature changes at 3 points (apical/middle/coronal). In the entire laser irradiations, the mean of temperature changes remains below 10°C. The apical temperature rise was higher than the coronal and middle regions (P < 0.05), and the apical temperature took longer time to reach the initial temperature (37°C) (P < 0.001). Temperature changes over 10°C occurred at the apical point of the implants with the Co2, Nd:YAG, and diode laser irradiations; however, only the Co2 laser reached the statistical significance in this regard (P < 0.05). Our findings indicate the promising results of Er:YAG laser and aPDT in implant decontamination. Precaution should be taken in the application of Nd:YAG, diode, and especially Co2 lasers.

Pulsed Nd:YAG laser beam drilling: A review

NASA Astrophysics Data System (ADS)

Gautam, Girish Dutt; Pandey, Arun Kumar

2018-03-01

Laser beam drilling (LBD) is one of non contact type unconventional machining process that are employed in machining of stiff and high-strength materials, high strength temperature resistance materials such as; metal alloys, ceramics, composites and superalloys. Most of these materials are difficult-to-machine by using conventional machining methods. Also, the complex and precise holes may not be obtained by using the conventional machining processes which may be obtained by using unconventional machining processes. The laser beam drilling in one of the most important unconventional machining process that may be used for the machining of these materials with satisfactorily. In this paper, the attention is focused on the experimental and theoretical investigations on the pulsed Nd:YAG laser drilling of different categories of materials such as ferrous materials, non-ferrous materials, superalloys, composites and Ceramics. Moreover, the review has been emphasized by the use of pulsed Nd:YAG laser drilling of different materials in order to enhance productivity of this process without adverse effects on the drilled holes quality characteristics. Finally, the review is concluded with the possible scope in the area of pulsed Nd:YAG laser drilling. This review work may be very useful to the subsequent researchers in order to give an insight in the area of pulsed Nd:YAG laser drilling of different materials and research gaps available in this area.

Clinical development of holmium:YAG laser prostatectomy

NASA Astrophysics Data System (ADS)

Kabalin, John N.

1996-05-01

Holmium:YAG (Ho:YAG) laser vaporization and resection of the prostate offers advantages in immediate tissue removal compared to the Neodymium:YAG (Nd:YAG) laser. Ongoing development of appropriate operative techniques and Ho:YAG laser delivery systems suitable for endoscopic prostate surgery, including side-firing optical delivery fibers, have facilitated this approach. We performed Ho:YAG laser prostatectomy in 20 human subjects, including 2 men treated immediately prior to radical prostatectomy to assess Ho:YAG laser effects in the prostate. A total of 18 men were treated in an initial clinical trial of Ho:YAG prostatectomy. Estimated excess hyperplastic prostate tissue averaged 24 g (range 5 - 50 g). A mean of 129 kj Ho:YAG laser energy was delivered, combined with a mean of 11 kj Nd:YAG energy to provide supplemental coagulation for hemostasis. We have observed no significant perioperative or late complications. No significant intraoperative changes in hematocrit or serum electrolytes were documented. In addition to providing acute removal of obstructing prostate tissue, Ho:YAG laser resection allowed tissue specimen to be obtained for histologic examination. A total of 16 of 18 patients (90%) underwent successful removal of their urinary catheter and voiding trial within 24 hours following surgery. Immediate improvement in voiding, comparable to classic transurethral electrocautery resection of the prostate (TURP), was reported by all patients. Ho:YAG laser resection of the prostate appears to be a viable surgical technique associated with minimal morbidity and immediate improvement in voiding.

Effect of Temperature Change on Interfacial Behavior of an Acoustically Levitated Droplet

NASA Astrophysics Data System (ADS)

Kawakami, Masanori; Abe, Yutaka; Kaneko, Akiko; Yamamoto, Yuji; Hasegawa, Koji

2010-04-01

Under the microgravity environment, new and high quality materials with a homogeneous crystal structure are expected to be manufactured by undercooling solidification, since the material manufacturing under the microgravity environment is more static than that under the normal gravity. However, the temperature change on the interface of the material in space can affect on the material processing. The purpose of the present study is to investigate effect of the temperature change of interface on the large levitated droplet interface. A water droplet levitated by the acoustic standing wave is heated by YAG laser. In order to heat the water droplet by the laser heating, rhodamine 6G is solved in it to achieve high absorbance of the laser. The droplet diameter is from 4 to 5.5 mm. The deformation of the droplet interface is observed by high speed video camera. The temperature of droplet is measured by the radiation thermometer. It is noticed that the larger droplet under the higher sound pressure tends to oscillate remarkably by the laser heating.

A laser-abrasive method for the cutting of enamel and dentin.

PubMed

Altshuler, G B; Belikov, A V; Sinelnik, Y A

2001-01-01

This paper introduced a new method for the removal of hard dental tissue based upon the use of particles accelerated by laser irradiation, which the authors have called the laser-abrasive method. The particles used were sapphire as powder or an aqueous suspension. The effect of the products of enamel ablation was also investigated. The particles were accelerated using submillisecond pulses of Er:YAG and Nd:YAG lasers. A strobing CCD camera was used to measure the speed of the ejected particles. The additional contribution of these particles to the efficiency of laser ablation of enamel and dentin was also investigated. The results showed that the enamel particles produced by the beam-tissue interaction were also accelerated by this process of ablation and were effective in the removal of enamel and dentin. The use of an aqueous suspension of sapphire particles increased the efficiency of enamel removal threefold when compared with the use of an Er:YAG laser with water spray. The laser-abrasive method allowed for the removal of enamel and dentin at speeds approaching those of the high-speed turbine. Copyright 2001 Wiley-Liss, Inc.

Design and characterization of Yb and Nd doped transparent ceramics for high power laser applications: recent advancements

NASA Astrophysics Data System (ADS)

Lapucci, A.; Vannini, M.; Ciofini, M.; Pirri, A.; Nikl, M.; Li, J.; Esposito, L.; Biasini, V.; Hostasa, J.; Goto, T.; Boulon, G.; Maksimov, R.; Gizzi, L.; Labate, L.; Toci, G.

2017-01-01

We report a review on our recent developments in Yttebium and Neodymium doped laser ceramics, along two main research lines. The first is the design and development of Yb:YAG ceramics with non uniform doping distribution, for the management of thermo-mechanical stresses and for the mitigation of ASE: layered structures have been produced by solid state reactive sintering, using different forming processes (spray drying and cold press of the homogenized powders, tape cast of the slurry); samples have been characterized and compared to FEM analysis. The second is the investigation of Lutetium based ceramics (such as mixed garnets LuYAG and Lu2O3); this interest is mainly motivated by the favorable thermal properties of these hosts under high doping. We recently obtained for the first time high efficiency laser emission from Yb doped LuYAG ceramics. The investigation on sesquioxides has been focused on Nddoped Lu2O3 ceramics, fabricated with the Spark Plasma Sintering method (SPS). We recently achieved the first laser emission above 1 W from Nd doped Lu2O3 ceramics fabricated by SPS.

Theoretical and experimental investigations on high peak power Q-switched Nd:YAG laser at 1112 nm

NASA Astrophysics Data System (ADS)

He, Miao; Yang, Feng; Wang, Zhi-Chao; Gao, Hong-Wei; Yuan, Lei; Li, Chen-Long; Zong, Nan; Shen, Yu; Bo, Yong; Peng, Qin-Jun; Cui, Da-Fu; Xu, Zu-Yan

2018-07-01

We report on the experimental measurement and theoretical analysis on a Q-switched high peak power laser diode (LD) side-pumped 1112 nm Nd:YAG laser by means of special mirrors coating design in cavity. In theory, a numerical model, based on four-wavelength rate equations, is performed to analyze the competition process of different gain lines and the output characteristics of the Q-switched Nd:YAG laser. In the experiment, a maximum output power of 25.2 W with beam quality factor M2 of 1.46 is obtained at the pulse repetition rate of 2 kHz and 210 ns of pulse width, corresponding to a pulse energy and peak power of 12.6 mJ and 60 kW, respectively. The experimental data agree well with the theoretical simulation results.

The use of lasers for periodontal debridement: marketing tool or proven therapy?

PubMed

Chanthaboury, Rachel; Irinakis, Tassos

2005-10-01

The use of lasers in dentistry has recently received much attention, in both clinical practice and research; their unique properties produce favourable clinical results in some cases and encourage patient acceptance. Various types of lasers have been investigated as an adjunct to periodontal therapy; these include carbon dioxide (CO₂), diode, neodymium:yttrium-aluminium-garnet (Nd:YAG) and erbium:yttrium-aluminium-garnet (Er:YAG) lasers.However, adverse results have been associated with each type, including thermal damage to root surfaces, increases in pulpal temperature and the production of toxic by-products. The Er:YAG laser has produced the most promising results, as it can ablate effectively with minimal adverse effects. More research is needed to determine the ideal settings and methods for using the laser safely and effectively in clinical practice.

Penetration of 35% hydrogen peroxide into the pulp chamber in bovine teeth after LED or Nd:YAG laser activation.

PubMed

Camargo, Samira Esteves Afonso; Cardoso, Paula Elaine; Valera, Marcia Carneiro; de Araújo, Maria Amélia Máximo; Kojima, Alberto Noriyuki

2009-01-01

This aim of the present study was to evaluate the pulp chamber penetration of 35% hydrogen peroxide activated by LED (light-emitting diode) or Nd:YAG laser in bovine teeth, after an in-office bleaching technique. Forty-eight bovine lateral incisors were divided into four groups, acetate buffer was placed into the pulp chamber and bleaching agent was applied as follows: for group A (n = 12), activation was performed by LED; for group B (n = 12), activation was performed by Nd:YAG laser (60 mJ, 20 Hz); group C (n = 12) received no light or laser activation; and the control group (n = 12) received no bleaching gel application or light or laser activation. The acetate buffer solution was transferred to a glass tube and Leuco Crystal Violet and horseradish peroxidase were added, producing a blue solution. The optical density of this solution was determined spectrophotometrically and converted into microgram equivalents of hydrogen peroxide. The results were analysed using ANOVA and Tukey's test (5%). It was verified that the effect of activation was significant, as groups activated by LED or laser presented greater hydrogen peroxide penetration into the pulp chamber (0.499 +/- 0.622 microg) compared with groups that were not (0.198 +/- 0.218 microg). There was no statistically significant difference in the penetration of hydrogen peroxide into the pulp chamber between the two types of activation (LED or laser). The results suggest that activation by laser or LED caused an increase in hydrogen peroxide penetration into the pulp chamber.

Effect of Er:YAG laser irradiation on bonding property of zirconia ceramics to resin cement.

PubMed

Lin, Yihua; Song, Xiaomeng; Chen, Yaming; Zhu, Qingping; Zhang, Wei

2013-12-01

This study aimed to investigate whether or not an erbium: yttrium-aluminum-garnet (Er:YAG) laser could improve the bonding property of zirconia ceramics to resin cement. Surface treatments can improve the bonding properties of dental ceramics. However, little is known about the effect of Er:YAG laser irradiated on zirconia ceramics. Specimens of zirconia ceramic pieces were made, and randomly divided into 11 groups according to surface treatments, including one control group (no treatment), one air abrasion group, and nine Er:YAG laser groups. The laser groups were subdivided by applying different energy intensities (100, 200, or 300 mJ) and irradiation times (5, 10, or 15 sec). After surface treatments, ceramic pieces had their surface morphology observed, and their surface roughness was measured. All specimens were bonded to resin cement. Shear bond strength was measured after the bonded specimens were stored in water for 24 h, and additionally aged by thermocycling. Statistical analyses were performed using one way analysis of variance (ANOVA) and Tukey's test for shear bond strength, and Dunnett's t test for surface roughness, with α=0.05. Er:YAG laser irradiation changed the morphological characteristics of zirconia ceramics. Higher energy intensities (200, 300 mJ) could roughen the ceramics, but also caused surface cracks. There were no significant differences in the bond strength between the control group and the laser groups treated with different energy intensities or irradiation times. Air abrasion with alumina particles induced highest surface roughness and shear bond strength. Er:YAG laser irradiation cannot improve the bonding property of zirconia ceramics to resin cement. Enhancing irradiation intensities and extending irradiation time have no benefit on the bond of the ceramics, and might cause material defect.

Timing capabilities of garnet crystals for detection of high energy charged particles

NASA Astrophysics Data System (ADS)

Lucchini, M. T.; Gundacker, S.; Lecoq, P.; Benaglia, A.; Nikl, M.; Kamada, K.; Yoshikawa, A.; Auffray, E.

2017-04-01

Particle detectors at future collider experiments will operate at high collision rates and thus will have to face high pile up and a harsh radiation environment. Precision timing capabilities can help in the reconstruction of physics events by mitigating pile up effects. In this context, radiation tolerant, scintillating crystals coupled to silicon photomultipliers (SiPMs) can provide a flexible and compact option for the implementation of a precision timing layer inside large particle detectors. In this paper, we compare the timing performance of aluminum garnet crystals (YAG: Ce, LuAG: Ce, GAGG: Ce) and the improvements of their time resolution by means of codoping with Mg2+ ions. The crystals were read out using SiPMs from Hamamatsu glued to the rear end of the scintillator and their timing performance was evaluated by measuring the coincidence time resolution (CTR) of 150 GeV charged pions traversing a pair of crystals. The influence of crystal properties, such as density, light yield and decay kinetics on the timing performance is discussed. The best single detector time resolutions are in the range of 23-30 ps (sigma) and only achieved by codoping the garnet crystals with divalent ions, such as Mg2+. The much faster scintillation decay in the co-doped samples as compared to non co-doped garnets explains the higher timing performance. Samples of LSO: Ce, Ca and LYSO:Ce crystals have also been used as reference time device and showed a time resolution at the level of 17 ps, in agreement with previous results.

21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nd:YAG laser for posterior capsulotomy and...:YAG laser for posterior capsulotomy and peripheral iridotomy. (a) Identification. The Nd:YAG laser for... laser intended for disruption of the posterior capsule or the iris via optical breakdown. The Nd:YAG...

21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nd:YAG laser for posterior capsulotomy and...:YAG laser for posterior capsulotomy and peripheral iridotomy. (a) Identification. The Nd:YAG laser for... laser intended for disruption of the posterior capsule or the iris via optical breakdown. The Nd:YAG...

21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nd:YAG laser for posterior capsulotomy and...:YAG laser for posterior capsulotomy and peripheral iridotomy. (a) Identification. The Nd:YAG laser for... laser intended for disruption of the posterior capsule or the iris via optical breakdown. The Nd:YAG...

21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nd:YAG laser for posterior capsulotomy and...:YAG laser for posterior capsulotomy and peripheral iridotomy. (a) Identification. The Nd:YAG laser for... laser intended for disruption of the posterior capsule or the iris via optical breakdown. The Nd:YAG...

Measurements of optical properties of some molten oxides

NASA Astrophysics Data System (ADS)

Nason, D. O.; Yen, C. T.; Tiller, W. A.

1990-11-01

A method based on a fine-focussed optical laser has been developed to measure the spectral reflectance and the transmittance of small ( ∽ 1 mm) liquid or single crystal materials. The measured normal spectral emittance for 633 nm light is about 0.9 for several molten refractory oxides, 0.8 for lithium niobate and 0.7 for molten sapphire. Sapphire and YAG experience a several-fold increase in emittance on melting. The absorption coefficient and the thickness for opaqueness are calculated and some consequences of the partial transparency of small hot materials, when their temperatures are measured by optical pyrometry, are discussed.

Upconversion Effects in Resonantly Pumped Er3+ and Pr3+ Doped Low Phonon-Energy Crystals for Eye-Safe Laser Applications

DTIC Science & Technology

2015-07-14

2.4 ms [24] for Er: KPb2Cl5 and  ~ 1.9 ms [13] for Er: KPb2Br5). This feature is indicative of nonradiative ETU process taking place [16...such as YAG as nonradiative decay rates are smaller in chloride and bromide based hosts. Using equation (5) the microparameters for the infrared...is present which also contributes to the effective decay transient. Similar to Pr3+ in the halide hosts KPb2Cl5 and 25 KPb2Br5 nonradiative decay

Manipulation of Micro Scale Particles in Optical Traps Using Programmable Spatial Light Modulation

NASA Technical Reports Server (NTRS)

Seibel, Robin E.; Decker, Arthur J. (Technical Monitor)

2003-01-01

1064 nm light, from an Nd:YAG laser, was polarized and incident upon a programmable parallel aligned liquid crystal spatial light modulator (PAL-SLM), where it was phase modulated according to the program controlling the PAL-SLM. Light reflected from the PAL-SLM was injected into a microscope and focused. At the focus, multiple optical traps were formed in which 9.975 m spheres were captured. The traps and the spheres were moved by changing the program of the PAL-SLM. The motion of ordered groups of micro particles was clearly demonstrated.

High-order Stokes generation in a KTP Raman laser pumped by a passively Q-switched ND:YLF laser

NASA Astrophysics Data System (ADS)

Wang, Maorong; Zhong, Kai; Mei, Jialin; Guo, Shibei; Xu, Degang; Yao, Jianquan

2015-12-01

High-order Stokes wave was observed in an x-cut KTP crystal based on stimulated Raman scattering (SRS) pumped by a passively Q-switched Nd:YLF laser with a Cr4+:YAG saturable absorber. Output spectra including the fundamental wave at 1047 nm and six Stokes wavelengths at 1077 nm, 1110 nm, 1130 nm, 1143 nm, 1164 nm, 1180 nm based on two Raman frequency shift at 267.4 cm-1 and 693.0 cm-1 were obtained simultaneously. We also detected green light generation with output power of 12 mW from self frequency mixing in the KTP crystal. The maximum total output power reached 452 mW at the repetition frequency of 8.1 kHz, corresponding to the optical-to-optical conversion efficiency of 4.61% and pump-to-Raman conversion efficiency of 3.6%.

Stable, high power, high efficiency picosecond ultraviolet generation at 355 nm in K3B6O10 Br crystal

NASA Astrophysics Data System (ADS)

Hou, Z. Y.; Wang, L. R.; Xia, M. J.; Yan, D. X.; Zhang, Q. L.; Zhang, L.; Liu, L. J.; Xu, D. G.; Zhang, D. X.; Wang, X. Y.; Li, R. K.; Chen, C. T.

2018-06-01

We demonstrate a high efficiency and high power picosecond ultraviolet source at 355 nm with stable output by sum frequency generation from a Nd:YAG laser using a type-I critically phase matched K3B6O10 Br crystal as nonlinear optical material. Conversion efficiency as high as 30.8% was achieved using a 25 ps laser at 1064 nm operated at 10 Hz. Similar work is done by using a 35 W 10 ps laser at 1064 nm as the pump source with a repetition rate of 80 MHz, and the highest average output power obtained was up to 5.3 W. In addition, the power stability of the 355 nm output power measurement shows that the standard deviation fluctuations of the average power are ±0.69% and ±0.91% at 3.0 W and 3.5 W, respectively.

THz-wave parametric sources and imaging applications

NASA Astrophysics Data System (ADS)

Kawase, Kodo

2004-12-01

We have studied the generation of terahertz (THz) waves by optical parametric processes based on laser light scattering from the polariton mode of nonlinear crystals. Using parametric oscillation of MgO-doped LiNbO3 crystal pumped by a nano-second Q-switched Nd:YAG laser, we have realized a widely tunable coherent THz-wave sources with a simple configuration. We have also developed a novel basic technology for THz imaging, which allows detection and identification of chemicals by introducing the component spatial pattern analysis. The spatial distributions of the chemicals were obtained from terahertz multispectral trasillumination images, using absorption spectra previously measured with a widely tunable THz-wave parametric oscillator. Further we have applied this technique to the detection and identification of illicit drugs concealed in envelopes. The samples we used were methamphetamine and MDMA, two of the most widely consumed illegal drugs in Japan, and aspirin as a reference.

Measurement of Spectral Broadening in PTS-Polydiacetylene

NASA Astrophysics Data System (ADS)

Bhowmik, Achintya; Thakur, Mrinal

1998-03-01

PTS-polydiacetylene has significant potential for future applications in ultrafast all-optical switches and logic gates.(R. Quintero-Torres and M. Thakur, Appl. Phys. Lett., 66, 1310 (1995).) In this work, we have made detailed measurements of the instantaneous spectral line broadening in a 500 μm thick PTS single-crystal as a function of intensity and wavelength. A mode-locked Ti-Sapphire laser with 2 ps pulse-width at 82 MHz repetition rate, and a Nd:YAG laser with 60 ps pulse-width at 10 Hz repetition rate were used for measurements at 720-840 nm and 1064 nm wavelength respectively. The spectral bandwidth of the beam was recorded before and after passing through the PTS single-crystal by a high-resolution spectrometer. The nonlinear refractive index (n_2) of PTS as a function of wavelength has been determined from the spectral broadening data.

Computational discovery of lanthanide doped and Co-doped Y{sub 3}Al{sub 5}O{sub 12} for optoelectronic applications

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

Choudhary, Kamal; Chernatynskiy, Aleksandr; Phillpot, Simon R.

2015-09-14

We systematically elucidate the optoelectronic properties of rare-earth doped and Ce co-doped yttrium aluminum garnet (YAG) using hybrid exchange-correlation functional based density functional theory. The predicted optical transitions agree with the experimental observations for single doped Ce:YAG, Pr:YAG, and co-doped Er,Ce:YAG. We find that co-doping of Ce-doped YAG with any lanthanide except Eu and Lu lowers the transition energies; we attribute this behavior to the lanthanide-induced change in bonding environment of the dopant atoms. Furthermore, we find infrared transitions only in case of the Er, Tb, and Tm co-doped Ce:YAG and suggest Tm,Ce:YAG and Tb,Ce:YAG as possible functional materials formore » efficient spectral up-conversion devices.« less

Histologic comparison of the CO2 laser and Nd:YAG with and without water/air surface cooling on tooth root structure

NASA Astrophysics Data System (ADS)

Cobb, Charles M.; Spencer, Paulette; McCollum, Mark H.

1995-05-01

Specimens consisted of 18 extracted single rooted teeth unaffected by periodontal disease. After debriding roots, specimens were randomly divided into 4 treatment groups and subjected to a single pass, at varying energy densities, of a CO2, Nd:YAG, and Nd:YAG with air/water surface cooling (Nd:YAG-C). The rate of exposure was controlled at 4 mm/sec. Approximate energy densities were: CO2, 138, 206, 275, and 344 J/cm2; Nd:YAG, 114, 171, 229, and 286 J/cm2; Nd:YAG-C, 286, 343, 514, and 571 J/cm2. The CO2 laser was used both in continuous and pulsed beam modes (20 Hz, 0.01 sec pulse length and 0.8 mm dia spot size) whereas the Nd:YAG and Nd:YAG-C were preset at 50 Hz, 0.08 sec pulse length and 0.6 mm dia spot size. Specimen examination by SEM revealed, for all lasers, a direct correlation between increasing energy densities and depth of tissue ablation and width of tissue damage. However, to achieve the same relative dept of tissue ablation, the Nd:YAG-C required higher energy densities than either the CO2 or Nd:YAG lasers. The Nd:YAG-C generated a cavitation with sharply defined margins. Furthermore, regardless of energy density, and in contrast with other laser types, areas treated with the Nd:YAG-C did not exhibit collateral zones of heat damaged surface tissue.

Synchronization of pairs of nanosecond pulses from a laser with two gain crystals pumped with two different sources.

PubMed

Staufert, Daniel; Cudney, Roger S

2018-05-10

We report a laser that emits two Q-switched pulses, one at 1.047 μm and the other at 1.064 μm, generated by a Nd:YLF and a Nd:YVO 4 , respectively. The crystals are pumped by two fiber-coupled diode lasers (808 nm and 880 nm); the delay between the pulses can be controlled by adjusting the power of the pumps. Two kinds of Q-switching techniques are reported, passive (Cr:YAG saturable absorber) and active (electro-optic modulator). We model both the active and passive Q switching and make a comparison between numerical simulations and experiments. We show experimentally and theoretically that in both cases the pulses can be synchronized; however, the stability of the synchronization (sensitivity to pump power fluctuations) is better for active than for passive Q switching. We also report that under certain experimental conditions a third wavelength is obtained, 1156 nm, which corresponds to the first Stokes shift of the 1047 nm pulse produced by stimulated Raman scattering from the Nd:YVO 4 crystal.

Formation of surface nanolayers in chalcogenide crystals using coherent laser beams

NASA Astrophysics Data System (ADS)

Ozga, K.; Fedorchuk, A. O.; El-Naggar, A. M.; Albassam, A. A.; Kityk, V.

2018-03-01

We have shown a possibility to form laser modified surface nanolayers with thickness up to 60 nm in some ternary chalcogenide crystals (Ag3AsS3, Ag3SbS3, Tl3SbS3) The laser treatment was performed by two coherent laser beams split in a space. As the inducing lasers we have applied continuous wave (cw) Hesbnd Cd laser at wavelength 441 nm and doubled frequency cw Nd: YAG laser at 532 nm. The spectral energies of these lasers were higher with respect to the energy gaps of the studied crystals. The optical anisotropy was appeared and defected by monitoring of birefringence at probing wavelength of cw Hesbnd Ne laser at λ = 3390 nm. The changes of the laser stimulated near the surface layer morphology was monitored by TEM and AFM methods as well as by the reflected optical second harmonic generation at fundamental wavelength of microsecond CO2 laser generating at wavelength 10600 nm. This technique may open a new approach for the formation of the near the surface nanolayers in chalcogenides using external cw laser illumination.

Femtosecond diode-pumped mode-locked neodymium lasers

NASA Astrophysics Data System (ADS)

Kubeček, Václav; Jelínek, Michal; Čech, Miroslav; Vyhlídal, David; Su, Liangbi; Jiang, Dapeng; Ma, Fengkai; Qian, Xiaobo; Wang, Jingya; Xu, Jun

2016-12-01

Fluoride-type crystals (CaF2, SrF2) doped with neodymium Nd3+ and codoped with buffer ions for breaking clusters of active ions and increasing fluorescence efficiency, present interesting alternative as laser active media for the diode-pumped mode-locked lasers. In comparison with widely used materials as Nd:YAG or Nd:YVO4, they have broad emission spectra as well as longer fluorescence lifetime, in comparison with Nd:glass, SrF2 and CaF2 have better thermal conductivity. In spite of the fact, that this thermal conductivity decreases with Nd3+ doping concentration, these crystals are alternative for the Nd:glass in subpicosecond mode-locked laser systems. In this paper we review the basic results reported recently on these active materials and in the second part we present our results achieved in low power diode pumped passively mode locked lasers with Nd,La:CaF2 and Nd,Y:SrF2 crystals. The pulses as short as 258 fs at wavelength of 1057 nm were obtained in the first case, while 5 ps long pulses at 1065 nm were generated from the second laser system.

Effect of high power CO2 and Yb:YAG laser radiation on the characteristics of TIG arc in atmospherical pressure argon and helium

NASA Astrophysics Data System (ADS)

Wu, Shikai; Xiao, Rongshi

2015-04-01

The effects of laser radiation on the characteristics of the DC tungsten inert gas (TIG) arc were investigated by applying a high power slab CO2 laser and a Yb:YAG disc laser. Experiment results reveal that the arc voltage-current curve shifts downwards, the arc column expands, and the arc temperature rises while the high power CO2 laser beam vertically interacts with the TIG arc in argon. With the increase of the laser power, the voltage-current curve of the arc shifts downwards more significantly, and the closer the laser beam impingement on the arc to the cathode, the more the decrease in arc voltage. Moreover, the arc column expansion and the arc temperature rise occur mainly in the region between the laser beam incident position and the anode. However, the arc characteristics hardly change in the cases of the CO2 laser-helium arc and YAG laser-arc interactions. The reason is that the inverse Bremsstrahlung absorption coefficients are greatly different due to the different electron densities of the argon and helium arcs and the different wave lengths of CO2 and YAG lasers.

Evaluation of erbium:YAG and holmium:YAG laser radiation and dental hard tissue

NASA Astrophysics Data System (ADS)

Attrill, David Cameron

Lasers have become increasingly established in medicine as effective alternatives or adjuncts to conventional techniques. In dentistry, several clinical laser systems have been developed and marketed, but their applications have been limited to soft tissue surgery. To date, no laser has been capable of effectively cutting or modifying the highly mineralised dental tissues of enamel and dentine. The aim of this study was to evaluate two new laser systems for use in dentistry through a series of in vitro experiments. Both generic erbium and holmium lasers have theoretically superior operating characteristics over currently established lasers for applications with dental hard tissues. The two lasers investigated in this study were pulsed Er:YAG (lambda=2.94) a.m. and Cr-Tm-Ho:YAG (lambda=2.1mu.m). Both operated with a macropulse duration of approximately 200lambdas, at pulse repetition rates of 2-8Hz and mean pulse energies up to 230mJ. Radiation was focused using CaF[2] lenses (f=50-120mm). The lasers could be operated with or without the addition of a surface water film at the interaction site. Tissue removal efficiency was expressed as a latent heat of ablation (LHA, kJ/cm[3]) using a modification of the technique described by Charlton et al. (1990). The mean LHA's for the Er:YAG laser were 6.24kJ/cm[3] and 22.99kJ/cm[3] with dentine and enamel respectively without water, and 10.07kJ/cm[3] and 18.73kJ/cm[3] for dentine and enamel with water. The Cr-Tm-Ho:YAG laser was unable to effectively remove enamel at the fluences and pulse energies available; the mean LHA's for the Cr-Tm- Ho:YAG laser with dentine were 82.79kJ/cm3 and 57.57kJ/cm3 with and without water respectively. The Cr-Tm-Ho;YAG was approximately 8-9 times less efficient for tissue removal than the Er:YAG system. Er:YAG tissue removal with water was characterised by clean "surgical" cuts, comparable in histological appearance to those obtained using conventional instrumentation. Some thermal disruption and evidence of molten enamel in particular were apparent when the Er:YAG laser was used without water. The Cr-Tm-Ho;YAG laser produced extensive charring and carbonisation of tissues. It was concluded that this laser was unsuitable for clinical applications directed at the removal or modification of enamel and dentine, particularly as the Er:YAG laser offers superior qualities. Further research with the Cr-Tm-Ho:YAG laser was discontinued. A comparison of the mean shear bond strengths of a composite (ZlOO, 3M Dental Products) bonded to enamel was made using either a conventional acid etch technique or one of a range of experimental Er:YAG laser etching configurations. The mean values for acid etching (16.6 MPa) were in all cases significantly greater (p<0.01, Bonferroni) than those obtained with laser etching. The optimal laser etching parameters were a fluence of 24J/cm[2] (1/e[2] calculation) with water resulting in a mean bond strength of 11.5 MPa. This figure represents approximately 70% of the mean obtained with acid etching, and was significantly greater (p<0.01, Bonferroni) than the mean recorded for non etched negative control surfaces (4.4 MPa). Histological evaluation of the etched surfaces demonstrated clear differences in the etching patterns observed between laser and acid etching. Some surface cracking was noted in most laser etched surfaces, but the extent of this was minimised when the laser was applied in conjunction with a surface water film. Pulpal temperature increments following Er:YAG laser irradiation were significantly lower in teeth prepared with water than without (paired t-test, p<0.01). The largest increment in samples prepared with water was 3.9°C, compared to 24.7°C without water. The principal determinant of the temperature increment in either group was the total delivered energy, up to 140J. Linear regression modelling predicts that continuous irradiation up to 160J with water would not result in iatrogenic pulpal damage. In conclusion, the Er:YAG laser was shown to be an effective tool for cutting and modifying dental hard tissues. It almost certainly offers the best combination of safety, efficiency and speed of any laser system designed for preparing cavities. The laser must be used in conjunction with a water coolant on the tissues to minimise the possibility of iatrogenic damage, improve the quality of the laser cuts and in some circumstances increase cutting efficiency. The Er:YAG laser has shown much promise in these in vitro experiments and its progression to clinical use is supported. The Cr-Tm-Ho:YAG laser is significantly less efficient and in vitro results are unfavourable in comparison with the Er:YAG laser. Its clinical use is not supported.

Clinical studies of Nd:YAG laser and Chinese herbal medicine in treatment of patients with tinea unguium

NASA Astrophysics Data System (ADS)

Dan, Ming-bing; Chen, Nanjin; Chao, Changyuan

1993-03-01

Forty-seven patients with tinea unguium and 110 tinea unguium, proven bacteriologically and pathologically, were treated with an Nd:YAG laser and Chinese herbal medicine, after which they were analyzed. All patients were adult men and women. The duration of illness varied from 1 to 10 years. The patients were treated with Nd:YAG laser wavelength 1.06 micrometers and the ending output power 500 w/cm2. The diseased nail was removed by laser scanning or cauterization, charring, gasification and coagulation layer by layer until the nail matrix was exposed, and then it was bandaged with a small amount of Chinese herbal medicine. The cure rate is 80.0%. The tinea unguium infection rate of pars super finialis is very high in cities, accounting for more than 80% of the cases among the population. It influences patients' lives and finger appearance. However, removal of tinea unguium with Nd:YAG laser cauterization and coagulation is simple, painless, and does not require disinfection. Also, the reoccurrence rate is low. Treatment of tinea unguium is intractable. Oral administration of griseofulvin and ketoconazole are not completely satisfactory and hardly persist for a long-term treatment course. Moreover, long-term administration of these drugs might produce serious side effects such as renal injuries, leukopenia, psychosis, etc. Thus, we conclude from this data that Nd:YAG laser and Chinese herbal medicine are an effective treatment for hypertrophic scarand kiloid and valuable for further investigations.

Comparison of two Nd:YAG laser posterior capsulotomy: cruciate pattern vs circular pattern with vitreous strand cutting

PubMed Central

Kim, Jin-Soo; Choi, Jung Yeol; Kwon, Ji-Won; Wee, Won Ryang; Han, Young Keun

2018-01-01

AIM To investigate the effects and safety of neodymium: yttrium-aluminium-garnet (Nd:YAG) laser posterior capsulotomy with vitreous strand cutting METHODS A total of 40 eyes of 37 patients with symptomatic posterior capsular opacity (PCO) were included in this prospective randomized study and were randomly subjected to either cruciate pattern or round pattern Nd:YAG posterior capsulotomy with vitreous strand cutting (modified round pattern). The best corrected visual acuity (BCVA), intraocular pressure (IOP), refractive error, endothelial cell count (ECC), anterior segment parameters, including anterior chamber depth (ACD) and anterior chamber angle (ACA) were measured before and 1mo after the laser posterior capsulotomy. RESULTS In both groups, the BCVA improved significantly (P<0.001 for the modified round pattern group, P=0.001 for the cruciate pattern group); the IOP and ECC did not significantly change. The ACD significantly decreased (P<0.001 for both) and the ACA significantly increased (P=0.001 for the modified round pattern group and P=0.034 for the cruciate group). The extent of changes in these parameters was not significantly different between the groups. CONCLUSION Modified round pattern Nd:YAG laser posterior capsulotomy is an effective and safe method for the treatment of PCO. This method significantly changes the ACD and ACA, but the change in refraction is not significant. Modified round pattern Nd:YAG laser posterior capsulotomy can be considered a good alternative procedure in patients with symptomatic PCO. PMID:29487812

Comparison of two Nd:YAG laser posterior capsulotomy: cruciate pattern vs circular pattern with vitreous strand cutting.

PubMed

Kim, Jin-Soo; Choi, Jung Yeol; Kwon, Ji-Won; Wee, Won Ryang; Han, Young Keun

2018-01-01

To investigate the effects and safety of neodymium: yttrium-aluminium-garnet (Nd:YAG) laser posterior capsulotomy with vitreous strand cutting. A total of 40 eyes of 37 patients with symptomatic posterior capsular opacity (PCO) were included in this prospective randomized study and were randomly subjected to either cruciate pattern or round pattern Nd:YAG posterior capsulotomy with vitreous strand cutting (modified round pattern). The best corrected visual acuity (BCVA), intraocular pressure (IOP), refractive error, endothelial cell count (ECC), anterior segment parameters, including anterior chamber depth (ACD) and anterior chamber angle (ACA) were measured before and 1mo after the laser posterior capsulotomy. In both groups, the BCVA improved significantly ( P <0.001 for the modified round pattern group, P =0.001 for the cruciate pattern group); the IOP and ECC did not significantly change. The ACD significantly decreased ( P <0.001 for both) and the ACA significantly increased ( P =0.001 for the modified round pattern group and P =0.034 for the cruciate group). The extent of changes in these parameters was not significantly different between the groups. Modified round pattern Nd:YAG laser posterior capsulotomy is an effective and safe method for the treatment of PCO. This method significantly changes the ACD and ACA, but the change in refraction is not significant. Modified round pattern Nd:YAG laser posterior capsulotomy can be considered a good alternative procedure in patients with symptomatic PCO.

Minimally invasive scoliosis treatment with a Ho:YAG laser

NASA Astrophysics Data System (ADS)

Rumpf, Christian G.; Lang, Robert D.; Goetz, Marcus H.

2000-11-01

Today most surgical treatment of spinal deformations is concentrated on invasive mechanical techniques with long operation times and major effects on the patient's mobility. The proposed minimally invasive technique using laser light for tissue ablation offers a possibility of gentle scoliosis treatment. It is thought that an early removal of the epiphysial growth zone on the convex side over several vertebrae results in a straightening of the spine. In a first evaluation, four different laser systems including argon ion, Nd:YAG (Q-switched), Nd:YAG (cw), and Ho:YAG laser were compared with respect to thermal damage to adjacent tissue, ablation rates, efficiency and laser handling. For in-vivo investigation, fresh lamb spine was used. Comparison showed that the Ho:YAG laser is the most appropriate laser for the given goal, providing efficient photoablation with moderate thermal effects on the adjacent tissue. In a second step the proposed minimally invasive operation technique was performed in in-vivo experiments on young foxhounds using 3D- thoracoscopic operation techniques. During these operations temperature mapping was done using fiber-optic fluorescent probes. After 12 months of normal growth the animals were sacrificed and x-ray as well as MRI was performed on the spine. First results show a positive effect of scoliotic growth in two cases. Being able to produce a scoliosis by hemiepiphysiodesis on the vertebra, It is thought that this technique is successful for a straightening of the spine on patients with scoliosis.

Pulsed solid state lasers for medicine

NASA Astrophysics Data System (ADS)

Kertesz, Ivan; Danileiko, A. Y.; Denker, Boris I.; Kroo, Norbert; Osiko, Vyacheslav V.; Prokhorov, Alexander M.

1994-02-01

The effect on living tissues of different pulsed solid state lasers: Nd:YAG ((lambda) equals 1.06 micrometers ) Er:glass (1.54 micrometers ), Ho:YAG (2.1 micrometers ) and Er:YAG (2.94 micrometers ) is compared with the continuous wave Nd:YAG- and CO2-lasers used in operating theaters. Portable Er:glass- and Er:YAG-lasers are developed for surgery/cosmetics and HIV-safe blood testing.

Preparation of γ-Al2O3 films by laser chemical vapor deposition

NASA Astrophysics Data System (ADS)

Gao, Ming; Ito, Akihiko; Goto, Takashi

2015-06-01

γ- and α-Al2O3 films were prepared by chemical vapor deposition using CO2, Nd:YAG, and InGaAs lasers to investigate the effects of varying the laser wavelength and deposition conditions on the phase composition and microstructure. The CO2 laser was found to mostly produce α-Al2O3 films, whereas the Nd:YAG and InGaAs lasers produced γ-Al2O3 films when used at a high total pressure. γ-Al2O3 films had a cauliflower-like structure, while the α-Al2O3 films had a dense and columnar structure. Of the three lasers, it was the Nd:YAG laser that interacted most with intermediate gas species. This promoted γ-Al2O3 nucleation in the gas phase at high total pressure, which explains the cauliflower-like structure of nanoparticles observed.

0.8 mJ quasi-continuously pumped sub-nanosecond highly doped Nd:YAG oscillator-amplifier laser system in bounce geometry

NASA Astrophysics Data System (ADS)

Jelínek, M.; Kubeček, V.; Čech, M.; Hiršl, P.

2011-03-01

A quasi-continuously pumped picosecond oscillator-amplifier laser system based on two identical 2.4% Nd:YAG slabs in a single bounce geometry was developed and investigated. The oscillator was passively mode locked by the multiple quantum well saturable absorber inserted into the resonator in transmission mode. Output train containing 7 pulses with total energy of 900 μJ was generated directly from the oscillator. Single pulse with energy of 75 μJ, duration of 113 ps and Gaussian spatial profile was cavity dumped from the resonator and amplified by the single pass amplifier to the energy of 830 μJ. Comparison with our previously reported data obtained with similar system based on Nd:GdVO4 shows advantage of using highly doped Nd:YAG for generation of sub-millijoule pulses in one hundred picoseconds range, which might be interesting in many applications.

Evaluation of sub-surface penetration and bonding durability of self-etching primer systems to Er:YAG laser treated cervical dentin.

PubMed

He, Zhengdi; Chen, Lingling; Shimada, Yasushi; Tagami, Junji; Ruan, Shuangchen

2017-03-31

This study aimed to investigate self-etching bonding systems penetrating in sub-surface dentin layer after Er:YAG laser irradiation and micro-shear bonding durability over a period of 1 year. Dentin slices obtained from extracted human third molars were prepared. Two self-etching adhesive systems were evaluated: Clearfil SE Bond and Clearfil Tri-S Bond. Specimens were tested for micro-shear bond strength with one of the following treatments: Er:YAG laser irradiation and 600-grit silicon paper polishing at 24 h, 7 days, 6 months and 1 year. The adhesive interfaces between bonding agents and lased cervical dentin were studied. No hybrid layer could be observed for lased dentin. The slim resin tags could be seen penetrating through the lased subsurface layer. Bond strength to lased dentin after 6 months and 1 year were significantly decreased (p<0.05).

Safety of laser use under the dental microscope.

PubMed

Saegusa, Hidetoshi; Watanabe, Satoshi; Anjo, Tomoo; Ebihara, Arata; Suda, Hideaki

2010-04-01

The aim of this study was to investigate the safety of laser use under the dental microscope. Nd:YAG, Er:YAG and diode lasers were used. The end of the tips was positioned at a distance of 5 cm from the objective lens of a dental microscope. Each eye protector was made into a flat disc, which was fixed on the lens of the microscope. The filters were placed in front of the objective lens or behind the eye lens. Transmitted energy through the microscope with or without the filters was measured. No transmitted laser energy was detected when using matched eye protectors. Mismatched eye protectors were not effective for shutting out laser energy, especially for Nd:YAG and diode lasers. None or very little laser energy was detected through the microscope even without any laser filter. Matched filters shut out all laser energy irrespective of their positions.

Comparative study of passively Q-switched c-cut Nd:YVO4/Nd:YAG lasers based on CVD graphene and controlled operation

NASA Astrophysics Data System (ADS)

Jia, Fuqiang; Liu, Pei; Li, Kang; Chen, Hao; Cheng, Yongjie; Cai, Zhiping; Copner, Nigel

2017-07-01

In this paper, a comparative study of passively Q-switched c-cut Nd:YVO4 and Nd:YAG lasers using four different layers CVD graphene as saturable absorber are demonstrated experimentally for the first time. Moreover, it is successful to accurately control the frequency of repetition rates of the CVD graphern passively Q-switched lasers by pulsed pump. The impacts of laser materials, layers of CVD graphene and cavity length on output parameters are investigated intensively as well, the result shows that the c-cut Nd:YVO4 is a promising laser media compared with Nd:YAG for passively Q-switched lasers based on CVD graphene, as it has better performances in pulse width, pulse energy and peak power. A useful and cost-effective way to generate stable pulsed lasers by CVD graphene or other novel saturable materials are demonstrated.

Effect of the PVA (polyvinyl alcohol) concentration on the optical properties of Eu-doped YAG phosphors

NASA Astrophysics Data System (ADS)

Hora, Daniela A.; Andrade, Adriano B.; Ferreira, Nilson S.; Teixeira, Verônica C.; dos S. Rezende, Marcos V.

2016-10-01

The influence of the polyvinyl alcohol (PVA) concentration on the synthesis and structural, morphological and optical properties of Y3Al5O13: Eu (Eu-doped YAG) was systematically investigated in this work. The final concentration of PVA in the preparation step influenced the crystallite size and also the degree of particle agglomeration in Eu-doped YAG phosphors. X-ray excited optical luminescence (XEOL) emission spectra results indicated typical Eu3+ emission lines and an abnormally intense 5D0 → 7F4. The intensity parameters Ω2 and Ω4 were calculated and indicated the PVA concentration affects the ratio Ω2:Ω4. X-ray absorption spectroscopy (XAS) results showed Eu valence did not change and the symmetry around the Eu3+ is influenced by the PVA concentration. XEOL-XAS showed the luminescence increases as a function of energy.

Changes in nail keratin observed by Raman spectroscopy after Nd:YAG laser treatment.

PubMed

Shin, Min Kyung; Kim, Tae In; Kim, Wan Sun; Park, Hun-Kuk; Kim, Kyung Sook

2017-04-01

Lasers and photodynamic therapy have been considered a convergence treatment for onychomycosis, which is a fungal infection on the nail bed and nail plate. Laser therapies have shown satisfactory results without significant complications for onychomycosis; however, the mechanism of clearing remains unknown. In this work, we investigated changes in the chemical structure of nail keratin induced by Nd:YAG laser using Raman spectroscopy. Toe nails with onychomycosis were treated with 1064 nm Nd:YAG laser. After laser treatment, the disulfide band (490-590 cm -1 ) of nail keratin was rarely observed or was reduced in intensity. The amide I band (1500-1700 cm -1 ) also showed changes induced by the laser. The α-helical (1652 cm -1 ) structures dominated the β-sheet (1673 cm -1 ) in nontreated nail, but the opposite phenomenon was observed after laser treatment. © 2016 Wiley Periodicals, Inc.

Structural characterisation of advanced optical materials

NASA Astrophysics Data System (ADS)

Krsmanovic, Radenka

The rare earth systems discussed in this thesis belong to a class of new, advanced optical materials. Two different nanostuctured materials are studied: nanocrystalline oxide phosphors and glass ceramics containing luminescent nanocrystals. In both cases, the optical activity is based on the luminescence properties of rare earth dopants incorporated into the crystal structure of the insulator nanocrystals themselves. The structure, morphology and composition of these luminescent composite materials are investigated and used to demonstrate the benefits as well as the drawbacks of the synthesis and the processing techniques used, aiming to their improvement for possible industrial production. An investigation of the microstructure was done by XRD, TEM and HREM, while EDX, EELS and EFTEM spectroscopy techniques were used for the chemical identification. Our research clearly demonstrated that these techniques can be successfully applied, and in combination with optical spectroscopy can provide the complete characterization of nanostructured luminescent materials. Three different oxide phosphors in the form of nanocrystalline powders are obtained with the solution combustion technique: yttrium aluminum garnet (YAG), gadolinium gallium garnet (GGG) and scandium oxide, Sc2O 3. We found out that GGG and Sc2O3 samples have "perfect" nanocrystals, without defects or amorphous surface layer, and with uniform distribution of rare earth activators. Good crystal quality results in a long-lived phosphor and much stronger emission, which makes them promising candidate for display industry. Moreover, these luminescent nanocrystals are biocompatible and when functionalized with some molecules or biocompatible polymers can be used for bio-applications like "in vivo" markers in cell biology. For luminescence glass ceramics samples the ternary glass system Li 2O-Al2O3-SiO2 (LAS) is used as host matrix, and ZrO2 as nucleating agent for luminescent ions introduced as Eu2O3 or Er2O3. We wanted to obtain a composite with crystal-like optical properties, keeping the transparency and the processibility of the glass host. The spatial distribution of the precipitates throughout the material, their morphology, structure and composition are investigated with various TEM modes to check if we succeed in draining all rare earth dopant ions from the matrix into ZrO2 crystals. The best results are obtained for the samples containing Er as dopant.

Synthesis, growth, structural and optical studies of a new organic three dimensional framework: 4-(aminocarbonyl)pyridine 4-(aminocarbonyl)pyridinium hydrogen L-malate

NASA Astrophysics Data System (ADS)

Vijayalakshmi, A.; Vidyavathy, B.; Peramaiyan, G.; Vinitha, G.

2017-02-01

4-(aminocarbonyl)pyridine 4-(aminocarbonyl)pyridinium hydrogen L-malate [(4ACP)(4ACP).(LM)] a new organic nonlinear optical (NLO) crystal was grown by the slow evaporation method. Single crystal X-ray diffraction analysis revealed that the [(4ACP)(4ACP).(LM)] crystal belongs to monoclinic crystal system, space group P21/n, with a three dimensional network. Thermogravimetry (TG) and differential thermal (DT) analyses showed that [(4ACP)(4ACP).(LM)] is thermally stable up to 165 °C. The optical transmittance window and the lower cut-off wavelength of [(4ACP)(4ACP).(LM)] were found out by UV-vis-NIR spectral study. The molecular structure of [(4ACP)(4ACP).(LM)] was further confirmed by FTIR spectral studies. The relative dielectric permittivity and dielectric loss were determined as function of frequency and temperature. The third order nonlinear optical property of [(4ACP)(4ACP).(LM)] was studied by the Z-scan technique using a 532 nm diode pumped CW Nd:YAG laser. Nonlinear refractive index, nonlinear absorption coefficient and third order nonlinear susceptibility of the grown crystal were found to be 7.38×10-8 cm2/W, 0.08×10-4 cm/W and 5.36×10-6 esu, respectively. The laser damage threshold value is found to be 1.75 GW/cm2

Optically pumped cerium-doped LiSrAlF{sub 6} and LiCaAlF{sub 6}

DOEpatents

Marshall, C.D.; Payne, S.A.; Krupke, W.F.

1996-05-14

Ce{sup 3+}-doped LiSrAlF{sub 6} crystals are pumped by ultraviolet light which is polarized along the c axis of the crystals to effectively energize the laser system. In one embodiment, the polarized fourth harmonic light output from a conventional Nd:YAG laser operating at 266 nm is arranged to pump Ce:LiSrAlF{sub 6} with the pump light polarized along the c axis of the crystal. The Ce:LiSrAlF{sub 6} crystal may be placed in a laser cavity for generating tunable coherent ultraviolet radiation in the range of 280-320 nm. Additionally, Ce-doped crystals possessing the LiSrAlF{sub 6} type of chemical formula, e.g. Ce-doped LiCaAlF{sub 6} and LiSrGaF{sub 6}, can be used. Alternative pump sources include an ultraviolet-capable krypton or argon laser, or ultraviolet emitting flashlamps. The polarization of the pump light will impact operation. The laser system will operate efficiently when light in the 280-320 nm gain region is injected or recirculated in the system such that the beam is also polarized along the c axis of the crystal. The Ce:LiSrAlF{sub 6} laser system can be configured to generate ultrashort pulses, and it may be used to pump other devices, such as an optical parametric oscillator. 10 figs.

Optically pumped cerium-doped LiSrAlF.sub.6 and LiCaAlF.sub.6

DOEpatents

Marshall, Christopher D.; Payne, Stephen A.; Krupke, William F.

1996-01-01

Ce.sup.3+ -doped LiSrAlF.sub.6 crystals are pumped by ultraviolet light which is polarized along the c axis of the crystals to effectively energize the laser system. In one embodiment, the polarized fourth harmonic light output from a conventional Nd:YAG laser operating at 266 nm is arranged to pump Ce:LiSrAlF.sub.6 with the pump light polarized along the c axis of the crystal. The Ce:LiSrAlF.sub.6 crystal may be placed in a laser cavity for generating tunable coherent ultraviolet radiation in the range of 280-320 nm. Additionally, Ce-doped crystals possessing the LiSrAlF.sub.6 type of chemical formula, e.g. Ce-doped LiCaAlF.sub.6 and LiSrGaF.sub.6, can be used. Alternative pump sources include an ultraviolet-capable krypton or argon laser, or ultraviolet emitting flashlamps. The polarization of the pump light will impact operation. The laser system will operate efficiently when light in the 280-320 nm gain region is injected or recirculated in the system such that the beam is also polarized along the c axis of the crystal. The Ce:LiSrAlF.sub.6 laser system can be configured to generate ultrashort pulses, and it may be used to pump other devices, such as an optical parametric oscillator.

Laboratory and clinical experience with neodymium:YAG laser prostatectomy

NASA Astrophysics Data System (ADS)

Kabalin, John N.

1996-05-01

Since 1991, we have undertaken extensive laboratory and clinical studies of the Neodymium:YAG (Nd:YAG) laser for surgical treatment of bladder outlet obstruction due to prostatic enlargement or benign prostatic hyperplasia (BPH). Side-firing optical fibers which emit a divergent, relatively low energy density Nd:YAG laser beam produce coagulation necrosis of obstructing periurethral prostate tissue, followed by gradual dissolution and slough in the urinary stream. Laser-tissue interactions and Nd:YAG laser dosimetry for prostatectomy have been studied in canine and human prostate model systems, enhancing clinical application. Ongoing studies examine comparative Nd:YAG laser dosimetry for various beam configurations produced by available side-firing optical fibers and continue to refine operative technique. We have documented clinical outcomes of Nd:YAG laser prostatectomy in 230 consecutive patients treated with the UrolaseTM side-firing optical fiber. Nd:YAG laser coagulation the prostate produces a remarkably low acute morbidity profile, with no significant bleeding or fluid absorption. No postoperative incontinence has been produced. Serial assessments of voiding outcomes over more than 3 years of followup show objective and symptomatic improvement following Nd:YAG laser prostatectomy which is comparable to older but more morbid electrosurgical approaches. Nd:YAG laser prostatectomy is a safe, efficacious, durable and cost-effective treatment for BPH.

Ytterbium-doped glass-ceramics for optical refrigeration.

PubMed

Filho, Elton Soares de Lima; Krishnaiah, Kummara Venkata; Ledemi, Yannick; Yu, Ye-Jin; Messaddeq, Younes; Nemova, Galina; Kashyap, Raman

2015-02-23

We report for the first time the characterization of glass-ceramics for optical refrigeration. Ytterbium-doped nanocrystallites were grown in an oxyfluoride glass matrix of composition 2YbF(3):30SiO(2)-15Al(2)O(3)-25CdF(2)-22PbF(2)-4YF(3), forming bulk glass-ceramics at three different crystalisation levels. The samples are compared with a corresponding uncrystalised (glass) sample, as well as a Yb:YAG sample which has presented optical cooling. The measured X-ray diffraction spectra, and thermal capacities of the samples are reported. We also report for the first time the use of Yb:YAG as a reference for absolute photometric quantum efficiency measurement, and use the same setup to characterize the glass and glass-ceramic samples. The cooling figure-of-merit was measured by optical calorimetry using a fiber Bragg grating and found to depend on the level of crystallization of the sample, and that samples with nanocrystallites result in higher quantum efficiency and lower background absorption than the pure-glass sample. In addition to laser-induced cooling, the glass-ceramics have the potential to serve as a reference for quantum efficiency measurements.

Compact Ozone Differential Absorption Lidar (DIAL) Transmitter Using Solid-State Dye Polymers

NASA Technical Reports Server (NTRS)

Jones, Alton L., Jr.; DeYoung, Russell J.; Elsayid-Ele, Hani

2001-01-01

A new potential DIAL laser transmitter is described that uses solid-state dye laser materials to make a simpler, more compact, lower mass laser system. Two solid-state dye laser materials were tested to evaluate their performance in a laser oscillator cavity end pumped by a pulsed Nd:YAG laser at 532 nm. The polymer host polymethyl-methacrylate was injected with a pyrromethene laser dye, PM 580, or PM 597. A narrowband laser oscillator cavity was constructed to produce visible wavelengths of 578 and 600 nm which were frequency doubled into the UV region (299 or 300 nm) by using a BBO crystal, resulting in a maximum energy of 11 mJ at a wavelength of 578 nm when pumped by the Nd:YAG laser at an energy of 100 mJ (532 nm). A maximum output energy of 378 microJ was achieved in the UV region at a wavelength of 289 nm but lasted only 2000 laser shots at a repetition rate of 10 Hz. The results are promising and show that a solid-state dye laser based ozone DIAL system is possible with improvements in the design of the laser transmitter.

2-micron lasing in Tm:Lu2O3 ceramic: initial operation

NASA Astrophysics Data System (ADS)

Vetrovec, John; Filgas, David M.; Smith, Carey A.; Copeland, Drew A.; Litt, Amardeep S.; Briscoe, Eldridge; Schirmer, Ernestina

2018-03-01

We report on initial lasing of Tm:Lu2O3 ceramic laser with tunable output in the vicinity of 2 μm. Tm:Lu2O3 ceramic gain materials offer a much lower saturation fluence than the traditionally used Tm:YLF and Tm:YAG materials. The gain element is pumped by 796 nm diodes via a "2-for-1" crossrelaxation energy transfer mechanism, which enables high efficiency. The high thermal conductivity of the Lu2O3 host ( 18% higher than YAG) in combination with low quantum defect of 20% supports operation at high-average power. Konoshima's ceramic fabrication process overcomes the scalability limits of single crystal sesquioxides. Tm:Lu2O3 offers wide-bandwidth amplification of ultrashort pulses in a chirped-pulse amplification (CPA) system. A laser oscillator was continuously tuned over a 230 nm range from 1890 to 2120 nm while delivering up to 43W QCW output with up to 37% efficiency. This device is intended for initial testing and later seeding of a multi-pass edge-pumped disk amplifier now being developed by Aqwest which uses composite Tm:Lu2O3 disk gain elements.

The possibility of clinical application of the solid state lasers: Nd:YAG, Ho:YAG, and Er:YAG in otolaryngology - head and neck surgery

NASA Astrophysics Data System (ADS)

Tomaszewska, M.; Kukwa, A.; Tulibacki, M.; Wójtowicz, P.; Olędzka, I.; Jeżewska, E.

2007-02-01

The purpose of this study was to summarize our experiences in clinical application of Nd:YAG, Ho:YAG and Er:YAG in otolaryngology- head and neck surgery. Choosing the laser type and parameters for the particular procedures was based on our previous research on tissue effects of those lasers. During the period of 1993-2006 we performed 3988 surgical procedures with the Nd:YAG laser. Over 87% of those were made for the nasal cavity pathologies as polyps, hyperplasia of inferior nasal turbinate, granulation tissue, postoperative adhesions, vascular malformations, under the local anesthesia conditions. In our experience Nd:YAG laser gives the possibility of good clinical control and low risk of side effects for disorders of high recurrence and frequent interventions necessity, as nasal polyps or respiratory papillomatosis. Nd:YAG assisted uvulopalatoplasty gives an interesting alternative for surgical procedures for snoring and slight/mild OSA-recognized patients. Due to its good hemostatic properties, it is a perfect tool for removal of the chemodectoma from meddle ear. During the period of 1995-2006 we performed 229 surgical procedures with the Ho:YAG laser, mostly for larynx pathologies (adhesion and scar tissue removal). In our experience Ho:YAG laser can serve as a precise laser knife for both soft and bony tissue. The ER:YAG laser still remain under clinical trial. Since 2001 year we performed 24 procedures of removing stone deposits from salivary glands. We believe it may become a promising method to cope with sialolithiasis which allows for glandule function preservation. All of the laser types mentioned above, can be easily coupled with endoscopes, what makes them available for all of the head and necklocalized disorders.

Laser reduction of specific microorganisms in the periodontal pocket using Er:YAG and Nd:YAG lasers: a randomized controlled clinical study.

PubMed

Grzech-Leśniak, K; Sculean, A; Gašpirc, Boris

2018-05-15

The objective of this study was to evaluate the microbiological and clinical outcomes following nonsurgical treatment by either scaling and root planing, combination of Nd:YAG and Er:YAG lasers, or by Er:YAG laser treatment alone. The study involved 60 patients with generalized chronic periodontitis, randomly assigned into one of three treatment groups of 20 patients. The first group received scaling and root planing by hand instruments (SRP group), the second group received Er:YAG laser treatment alone (Er group), and the third group received combined treatment with Nd:YAG and Er:YAG lasers (NdErNd group). Microbiological samples, taken from the periodontal pockets at baseline and 6 months after treatments, were assessed with PET Plus tests. The combined NdErNd laser (93.0%), followed closely by Er:YAG laser (84.9%), treatment resulted in the highest reduction of all bacteria count after 6 months, whereas SRP (46.2%) failed to reduce Treponema denticola, Peptostreptococcus micros, and Capnocytophaga gingivalis. Full-mouth plaque and bleeding on probing scores dropped after 6 months and were the lowest in both laser groups. The combination of NdErNd resulted in higher probing pocket depth reduction and gain of clinical attachment level (1.99 ± 0.23 mm) compared to SRP (0.86 ± 0.13 mm) or Er:YAG laser alone (0.93 ± 0.20 mm) in 4-6 mm-deep pockets. Within their limits, the present results provide support for the combination of Nd:YAG and Er:YAG lasers to additionally improve the microbiological and clinical outcomes of nonsurgical periodontal therapy in patients with moderate to severe chronic periodontitis.

Erbium:Yttrium Aluminum Garnet Laser-Activated Sodium Hypochlorite Irrigation: A Promising Procedure for Minimally Invasive Endodontics.

PubMed

Cheng, Xiaogang; Tian, Tiantian; Tian, Yu; Xiang, Doudou; Qiu, Jun; Liu, Xiaohua; Yu, Qing

2017-12-01

This study was to evaluate the potential of Erbium:Yttrium Aluminum Garnet laser-activated sodium hypochlorite irrigation (Er:YAG + NaOCl) for minimally invasive endodontics (MIE). Er:YAG laser irradiation can dramatically enhance the penetration of NaOCl, which may be a promising protocol for MIE. Extracted human teeth were contaminated with Enterococcus faecalis for 4 weeks. The infected canals were then shaped to different apical terminal working widths (ATWW, 15#/0.04, 20#/0.04, 25#/0.04, 30#/0.04, and 40#/0.04) and treated with either Er:YAG + NaOCl (0.3 W, 20 sec) or NaOCl alone. Then, the ATWW were fixed at 15#/0.04, and the canals were treated with Er:YAG + NaOCl at 0.3 W for 40 and 60 sec, or at 0.5 and 1.0 W for 20 sec. Finally, bacterial reductions were evaluated using the cell count method. Er:YAG + NaOCl showed a higher disinfection efficacy at each ATWW compared with NaOCl alone (p < 0.001). The maximum bacterial reduction was 99.9% for the 40#/Er:YAG + NaOCl group and 93.6% for the 40#/NaOCl group. To achieve similar disinfection efficacy, the Er:YAG + NaOCl group needed a smaller ATWW than the NaOCl group. At a fixed ATWW, increasing the output power of the Er:YAG laser was more effective than increasing the radiation time to improve the disinfection efficacy of Er:YAG + NaOCl. The 15#/Er:YAG + NaOCl group reached the maximum bacterial reduction of 99.2% when the Er:YAG laser was activated at 1.0 W for 20 sec. The 15#/Er:YAG + NaOCl with the Er:YAG laser irradiation at 1.0 W for 20 sec may be considered a promising procedure for MIE.

Investigations to improve laser induced lithrotripsy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Eisel, Max; Ulaganathan, Keerthanan; Strittmatter, Frank; Pongratz, Thomas; Sroka, Ronald

2017-02-01

Laser lithotripsy is the preferred application for the destruction of ureteral and kidney stones. Clinically Ho:YAG lasers (λ=2.1μm) are used due to high absorption by water to induce thermomechanical ablation. This study focussed on the investigation of different laser parameters in relation to the stone dusting efficiency. The term dusting was defined when the ablated fragments were d<1mm in diameter while fragmentation is defined to pieces of d> 1mm. The discussion about fragment-size showed advantages like reduced surgery time. Experiments were performed using clinical available Ho:YAG laser energy transferred via a standard fibre (Ø: 365μm) onto phantom calculi (Bego-Stones of different hardness) in a water filled vessel. Dusting can be reached most efficient by using low energy/pulse (approx. 0.5J/pulse) and repetition rate of around 40 Hz. Higher energy/pulse showed strong repulsion and thereby increased mobility, while using lower repetition rates result in longer ablation times. With regard to the hardness of the phantoms it can be derived that on soft calculi or calculi with a very rugged surface dusting can be observed less because the stone breaks into large fragments after a short time of laser application. For hard calculi the ablation process takes a much longer time compared to soft stones. In the following will be shown that dusting and fragmentation process depends not only on the energy/pulse and repetition rate of a Ho:YAG-laser, but also there are differences between Ho:YAG-laser systems according to the dusting efficiency.

Primary investigations on the potential of a novel diode pumped Er:YAG laser system for bone surgery

NASA Astrophysics Data System (ADS)

Stock, Karl; Diebolder, Rolf; Hausladen, Florian; Wurm, Holger; Lorenz, Swetlana; Hibst, Raimund

2013-03-01

Flashlamp pumped Er:YAG-lasers are successfully clinically used for both precise soft and hard tissue ablation. As an alternative, actually a novel diode pumped Er:YAG laser system (Pantec Engineering AG) becomes available, with mean laser power up to 15W and pulse repetition rate up to 1kHz. The aim of the presented study is to investigate the effect of this laser system on bone tissue at various irradiation parameters, particular at repetition rates exceeding 100 Hz. For reproducible experiments, firstly an appropriate experimental set-up was realized with a beam delivery and focusing unit, a computer controlled stepper unit with sample holder, and a shutter unit. It allowed to move the sample (1mm- 3mm sawed slices of pig bone) with a defined velocity while irradiation by various laser parameters. A water spray served to moisten the sample surfaces. After irradiation the grooves were analyzed by light microscopy and laser scanning microscopy regarding to the ablation quality, the groove geometry, the ablation efficacy, and the thermal effects. The resulting grooves are slightly cone shaped (groove depth up to 3mm, width about 200μm) with sharp edges at the surface. At 1W, 200Hz, 5mm/s sample movement and with water irrigation the measured ablation speed Δz/Δt is 10.8 mm/s. The ablation depth per pulse is 54μm. In conclusion, these first experiments demonstrate that the diode pumped Er:YAG laser system is an efficient tool for use in bone surgery.

Hydrogen bonded nonlinear optical γ-glycine: Crystal growth and characterization

NASA Astrophysics Data System (ADS)

Narayana Moolya, B.; Jayarama, A.; Sureshkumar, M. R.; Dharmaprakash, S. M.

2005-07-01

Single crystals of γ-glycine(GG) were grown by solvent evaporation technique from a mixture of aqueous solutions of glycine and ammonium nitrate at ambient temperature. X-ray diffraction, thermogravimetric/differential thermal analysis, Fourier transform infrared spectral techniques were employed to characterize the crystal. The lattice parameters were calculated and they agree well with the reported values. GG exists as dipolar ions in which the carboxyl group is present as a carboxylate ion and the amino group as an ammonium ion. Due to this dipolar nature, glycine has a high decomposition temperature. The UV cutoff of GG is below 300 nm and has a wide transparency window, which is suitable for second harmonic generation of laser in the blue region. Nonlinear optical characteristics of GG were studied using Q switched Nd:YAG laser ( λ=1064 nm). The second harmonic generation conversion efficiency of GG is 1.5 times that of potassium dihydrogen phosphate . The X-ray diffraction and Fourier transform infrared spectral studies show the presence of strong hydrogen bonds which create and stabilize the crystal structure in GG. The main contributions to the nonlinear optical properties in GG results from the presence of the hydrogen bond and from the vibrational part due to very intense infrared bands of the hydrogen bond vibrations. GG is thermally stable up to 441 K.

Successful treatment of acne keloidalis nuchae with erbium:YAG laser: a comparative study.

PubMed

Gamil, Hend D; Khater, Elsayed M; Khattab, Fathia M; Khalil, Mona A

2018-05-14

Acne keloidalis nuchae (AKN) is a chronic inflammatory disease involving hair follicles of the neck. It is a form of keloidal scarring alopecia that is often refractory to medical or surgical management. To evaluate the efficacy of Er:YAG laser in the treatment of AKN as compared to long pulsed Nd:YAG laser. This study was conducted on 30 male patients with AKN. Their ages ranged from 19 to 47 years with a mean age of 36.87 ± 7.8 years. Patients were divided randomly into two groups of 15 patients, each receiving six sessions of either Er:YAG or long-pulsed Nd:YAG laser therapy. A statistically significant decrease in the number of papules was detected at the end of therapy in both groups, with a mean of 91.8% improvement in the Er:YAG group versus 88% in the Nd:YAG group. A significant decrease in plaques count was detected only in the Er: YAG group while a significant decrease in plaques size and consistency was recorded in both groups. The Er: YAG laser proved to be a potentially effective and safe modality both in the early and late AKN lesions.

Association of Er:YAG and Nd:YAG irradiation for apicoectomy and retrofilling cavity preparation compared to conventional technique: a permeability study

NASA Astrophysics Data System (ADS)

Camargo, Selma C. C.; Gavini, Giulio; Eduardo, Carlos d. P.; Aun, Carlos E.; Ribeiro, Luciano W.; Coil, Jeffrey M.

1999-05-01

The aim of this research was to evaluate dentin permeability effects at the apical cut surface prepared with Er:YAG laser and irradiated with Nd:YAG laser compared to conventional techniques. 62 extracted human teeth were divided into four groups of 7 teeth each. For Group 1 apicoectomy was performed using high speed handpiece and diamond burs. Group 2 was prepared as group 1 and lased with Nd:YAG (1W,15Hz of energy before retrograde cavity filling). For group 3 Er:YAG* laser irradiation (wavelength of 2.94μm, pulse width of 250-500μs)was used in 400mJ of energy, frequency of 6Hz, on focus mode under distilled water refrigeration and group 4 was performed as group 3 and lased with Nd:YAG (1W, 15Hz of energy before retrograde cavity filling). Permeability was evaluated by the extent of methylene blue dye penetration into the tubules. There were statistically significant differences in permeability between groups. Nd:YAG laser irradiation significantly reduced apical dentin permeability when compared to unlased groups. Er:YAG laser by itself showed higher percentage of dye penetration.

Gingival melanin depigmentation by Er:YAG laser: A literature review.

PubMed

Pavlic, Verica; Brkic, Zlata; Marin, Sasa; Cicmil, Smiljka; Gojkov-Vukelic, Mirjana; Aoki, Akira

2018-04-01

Laser ablation is recently suggested as a most effective and reliable technique for depigmentation of melanin hyperpigmented gingiva. To date, different lasers have been used for gingival depigmentation (CO 2 , diode, Nd:YAG, Er:YAG and Er,Cr:YSGG lasers). The use of Er:YAG laser for depigmentation of melanin hyperpigmented gingiva has gained increasing importance in recent years. The purpose of this study was to report removal of gingival melanin pigmentation using an Er:YAG laser in a literature review. The main outcomes, such as improvement of signs (clinical parameters of bleeding, erythema, swelling and wound healing), symptoms (pain) and melanin recurrence/repigmentation were measured. The literature demonstrated that depigmentation of gingival melanin pigmentation can be performed safely and effectively by Er:YAG laser resulting in healing and an esthetically significant improvement of gingival discoloration. Thus, Er:YAG laser seems to be safe and useful in melanin depigmentation procedure. However, the main issue in giving the final conclusion of the optimal Er:YAG laser use in melanin depigmentation is that, to date, studies are offering completely discrepant Er:YAG laser procedure protocols (complex settings of laser parameters), and different criteria for the assessment of depigmentation and repigmentation (recurrence), thus hampering the comparison of the results. Therefore, further studies are necessary to give an optimal recommendation on the use of Er:YAG laser in gingival melanin hyperpigmentation.

Synthesis, growth, structural modeling and physio-chemical properties of a charge transfer molecule: Guanidinium tosylate

NASA Astrophysics Data System (ADS)

Era, Paavai; Jauhar, RO. MU.; Vinitha, G.; Murugakoothan, P.

2018-05-01

An organic nonlinear optical material, guanidinium tosylate was synthesized adopting slow evaporation method and the crystals were harvested from aqueous methanolic medium with dimensions 13 × 9 × 3 mm3. Constitution of crystalline material was confirmed by single crystal X-ray diffraction study. The title compound crystallizes in the monoclinic crystal system with space group P21/c. The UV-vis-NIR spectral study of the grown crystal exhibits high transparency of 80% in the entire visible region with lower cut-off wavelength at 282 nm. Optimized molecular geometry of the grown crystal was obtained using density functional theory (DFT) and the frontier energy gaps calculated from the DFT aids to understand the charge transfer taking place in the molecule. The dielectric properties were studied as a function of temperature and frequency to find the charge distribution within the crystal. The titular compound is thermally stable up to 230 °C assessed by thermogravimetric and differential thermal analysis. Anisotropy in the mechanical behavior was observed while measuring for individual planes. The laser induced surface damage threshold of the grown crystal was measured to be 0.344 GW/cm2 for 1064 nm Nd:YAG laser radiation. Z-scan technique confirms the third-order nonlinear optical property with the ascertained nonlinear refractive index (n2), nonlinear absorption coefficient (β) and third order nonlinear susceptibility (χ(3)). Optical limiting study divulges that the transmitted output power step-up linearly with the increase of the input power at lower power realms and saturates from the threshold 24.95 mW/cm2 and amplitude 0.23 mW/cm2.

Random lasing in dye-doped polymer dispersed liquid crystal film

NASA Astrophysics Data System (ADS)

Wu, Rina; Shi, Rui-xin; Wu, Xiaojiao; Wu, Jie; Dai, Qin

2016-09-01

A dye-doped polymer-dispersed liquid crystal film was designed and fabricated, and random lasing action was studied. A mixture of laser dye, nematic liquid crystal, chiral dopant, and PVA was used to prepare the dye-doped polymer-dispersed liquid crystal film by means of microcapsules. Scanning electron microscopy analysis showed that most liquid crystal droplets in the polymer matrix ranged from 30 μm to 40 μm, the size of the liquid crystal droplets was small. Under frequency doubled 532 nm Nd:YAG laser-pumped optical excitation, a plurality of discrete and sharp random laser radiation peaks could be measured in the range of 575-590 nm. The line-width of the lasing peak was 0.2 nm and the threshold of the random lasing was 9 mJ. Under heating, the emission peaks of random lasing disappeared. By detecting the emission light spot energy distribution, the mechanism of radiation was found to be random lasing. The random lasing radiation mechanism was then analyzed and discussed. Experimental results indicated that the size of the liquid crystal droplets is the decisive factor that influences the lasing mechanism. The surface anchor role can be ignored when the size of the liquid crystal droplets in the polymer matrix is small, which is beneficial to form multiple scattering. The transmission path of photons is similar to that in a ring cavity, providing feedback to obtain random lasing output. Project supported by the National Natural Science Foundation of China (Grant No. 61378042), the Colleges and Universities in Liaoning Province Outstanding Young Scholars Growth Plans, China (Grant No. LJQ2015093), and Shenyang Ligong University Laser and Optical Information of Liaoning Province Key Laboratory Open Funds, China.

Development of all-solid-state coherent 589 nm light source: toward the realization of sodium lidar and laser guide star adaptive optics

NASA Astrophysics Data System (ADS)

Saito, Norihito; Akagawa, Kazuyuki; Kato, Mayumi; Takazawa, Akira; Hayano, Yutaka; Saito, Yoshihiko; Ito, Meguru; Takami, Hideki; Iye, Masanori; Wada, Satoshi

2006-12-01

We report an all-solid-state coherent 589 nm light source in single-pass sum-frequency generation (SFG) with actively mode-locked Nd:YAG lasers for the realization of sodium lidar and laser guide star adaptive optics. The Nd:YAG lasers are constructed as a LD-side-pumped configuration and are operated at 1064 and 1319 nm for 589 nm light generation in SFG. Output powers of 16.5 and 5.3 W at 1064 and 1319 nm are obtained with two pumping chambers. Each chamber consisted of three 80-W-LD arrays. Single transverse mode TEM 00; M2 ~1.1 is achieved with adjustment of cavity length considering thermal lens effect with increase of input LD power. The cavity length is set to approximately 1 m. Accordingly the mode-locked lasers are operated at a repetition rate of approximately 150 MHz. Synchronization of two pulse trains at 1064 and 1319 nm is accomplished by control of phase difference between two radio frequencies input in acousto-optic mode-lockers. Then temporal delay is controlled with a resolution of 37 ps/degree. Pump beams are mixed in periodically poled stoichiometric lithium tantalate (PPSLT) without an antireflection coating. The effective aperture and length of the crystal are 0.5 × 2 mm2 and 15 mm. When input intensity is set at 5.6 MW/cm , an average output power of 4.6 W is obtained at 589.159 nm. Precise tuning to the sodium D II line is accomplished by thermal control of etalons set in the Nd:YAG lasers. The output power at 589.159 nm is stably maintained within +/-1.2% for 8 hours.

Keratorefractive procedures

NASA Astrophysics Data System (ADS)

Seiler, Theo

1991-11-01

Two laser types are going to find a place in refractive surgery of the cornea: the excimer laser (193 nm) and mid-infrared YAG lasers, such as Ho:YAG (2.1 micrometers ) and Er:YAG (2.94 micrometers ). Whereas the excimer laser used for photorefractive keratectomy (PRK) and phototherapeutic keratectomy (PTK) is currently studied in clinical trials, Ho:YAG and Er:YAG lasers are still in the state of preclinical evaluation. For myopic corrections excimer laser PRK has shown to be safe and effective in the range up to -7.0 D. The results compare favorably with conventional procedures such as radial keratotomy. Complications are rare. Hyperopic and astigmatic corrections using the Ho:YAG laser (HOT) are effective, but safety and stability has yet to be proven. Er:YAG laser photoablation yields a healing response in animal eyes similar to the excimer laser.

Preclinical investigations of articular cartilage ablation with femtosecond and pulsed infrared lasers as an alternative to microfracture surgery

NASA Astrophysics Data System (ADS)

Su, Erica; Sun, Hui; Juhasz, Tibor; Wong, Brian J. F.

2014-09-01

Microfracture surgery is a bone marrow stimulation technique for treating cartilage defects and injuries in the knee. Current methods rely on surgical skill and instrumentation. This study investigates the potential use of laser technology as an alternate means to create the microfracture holes. Lasers investigated in this study include an erbium:YAG laser (λ=2.94 μm), titanium:sapphire femtosecond laser system (λ=1700 nm), and Nd:glass femtosecond laser (λ=1053 nm). Bovine samples were ablated at fluences of 8 to 18 J/cm2 with the erbium:YAG laser, at a power of 300±15 mW with the titanium:sapphire femtosecond system, and at an energy of 3 μJ/pulse with the Nd:glass laser. Samples were digitally photographed and histological sections were taken for analysis. The erbium:YAG laser is capable of fast and efficient ablation; specimen treated with fluences of 12 and 18 J/cm2 experienced significant amounts of bone removal and minimal carbonization with saline hydration. The femtosecond laser systems successfully removed cartilage but not clinically significant amounts of bone. Precise tissue removal was possible but not to substantial depths due to limitations of the systems. With additional studies and development, the use of femtosecond laser systems to ablate bone may be achieved at clinically valuable ablation rates.

Preclinical investigations of articular cartilage ablation with femtosecond and pulsed infrared lasers as an alternative to microfracture surgery.

PubMed

Su, Erica; Sun, Hui; Juhasz, Tibor; Wong, Brian J F

2014-09-01

Microfracture surgery is a bone marrow stimulation technique for treating cartilage defects and injuriesin the knee. Current methods rely on surgical skill and instrumentation. This study investigates the potential useof laser technology as an alternate means to create the microfracture holes. Lasers investigated in this study include an erbium:YAG laser (λ = 2.94 μm), titanium:sapphire femtosecond laser system (λ = 1700 nm), and Nd:glass femtosecond laser (λ = 1053 nm). Bovine samples were ablated at fluences of 8 to 18 J∕cm2 with the erbium:YAG laser, at a power of 300 ± 15 mW with the titanium:sapphire femtosecond system, and at an energy of 3 μJ∕pulse with the Nd:glass laser. Samples were digitally photographed and histological sections were taken for analysis. The erbium:YAG laser is capable of fast and efficient ablation; specimen treated with fluences of 12 and 18 J∕cm2 experienced significant amounts of bone removal and minimal carbonization with saline hydration. The femtosecond laser systems successfully removed cartilage but not clinically significant amounts of bone. Precise tissue removal was possible but not to substantial depths due to limitations of the systems. With additional studies and development, the use of femtosecond laser systems to ablate bone may be achieved at clinically valuable ablation rates.

Use of the Er:YAG laser for improved plating in maxillofacial surgery: comparison of bone healing in laser and drill osteotomies.

PubMed

Lewandrowski, K U; Lorente, C; Schomacker, K T; Flotte, T J; Wilkes, J W; Deutsch, T F

1996-01-01

Surgical reconstruction of bony defects in the maxillofacial region involves fixation of bony fragments with mini and micro plates. Bone stabilization during hole drilling is often challenging due to the need to apply pressure when using a conventional mechanical Hall drill. In addition, fragmentation of the fragile bones may occur and complicate the reconstruction. The pulsed Er:YAG laser offers an attractive alternative drilling modality because it does not require physical contact with the bone in order to drill holes, cuts bone with minimal thermal damage, and allows precise control of bone cutting. The objective of this study was to investigate the pulsed Er:YAG laser as an alternative to the mechanical bur by comparing bone healing using both modalities. Bone healing in an inferior border defect of the rat mandible was examined using either an Er:YAG laser or a mechanical bur for drilling. The healing of osteotomies in facial bones and of screw holes for plate stabilization of free bone fragments was studied. All defects healed by 4 weeks postoperatively. Histologic evaluation demonstrated no difference in the amount of newly formed woven bone at the osteotomy site or screw holes made by either the laser or the drill. The extent of thermal damage at the osteotomy sites was comparable in laser and mechanically cut bone fragments. On the basis of this study we suggest that the Er: YAG laser can be used clinically in thin, fragile bones in the maxillofacial region.

Beneficial Effect of Low Fluence 1,064 nm Q-Switched Neodymium:Yttrium-Aluminum-Garnet Laser in the Treatment of Senile Lentigo

PubMed Central

Nam, Jae-Hui; Kim, Han-Saem; Lee, Ga-Young

2017-01-01

Background Low fluence 1,064 nm Q-switched (QS) Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG) laser treatment, also known as laser toning, is widely used for pigmentary disorders. There has been no reliable evaluation of the effect of low fluence 1,064 nm QS Nd:YAG laser for senile lentigo. Objective To investigate the beneficial effect of low fluence 1,064 nm QS Nd:YAG laser in the treatment of senile lentigo on the face. Methods A retrospective review was conducted on patients treated only with repetitive low fluence 1,064 nm QS Nd:YAG laser. Among them, 12 patients with multiple senile lentigines before treatment were included. All side effects were recorded to assess the safety of the modality. Results Mean age was 56.1±7.8 years old and male-to-female ratio was 1:11. Mean treatment fluence was 1.62±0.16 J/cm2 and mean total treatment session was 8.8±2.6. Mean interval period between each session was 28.0±11.4 days and mean treatment session to reach marked and near total improvement was 8.7±2.8. At the final visit, seven of 12 (58.3%) patients reached marked and near total improvement, and three of 12 (25.0%) reached moderate improvement. No side effects occurred. Conclusion Repetitive low fluence 1,064 nm QS Nd:YAG laser treatment may be an effective and safe optional modality for senile lentigo. PMID:28761290

Room temperature high power mid-IR diode laser bars for atmospheric sensing applications

NASA Astrophysics Data System (ADS)

Crump, Paul; Patterson, Steve; Dong, Weimin; Grimshaw, Mike; Wang, Jun; Zhang, Shiguo; Elim, Sandrio; Bougher, Mike; Patterson, Jason; Das, Suhit; Wise, Damian; Matson, Triston; Balsley, David; Bell, Jake; DeVito, Mark; Martinsen, Rob

2007-04-01

Peak CW optical power from single 1-cm diode laser bars is advancing rapidly across all commercial wavelengths and the available range of emission wavelengths also continues to increase. Both high efficiency ~ 50% and > 100-W power InP-based CW bars have been available in bar format around 1500-nm for some time, as required for eye-safe illuminators and for pumping Er-YAG crystals. There is increasing demand for sources at longer wavelengths. Specifically, 1900-nm sources can be used to pump Holmium doped YAG crystals, to produce 2100-nm emission. Emission near 2100-nm is attractive for free-space communications and range-finding applications as the atmosphere has little absorption at this wavelength. Diode lasers that emit at 2100-nm could eliminate the need for the use of a solid-state laser system, at significant cost savings. 2100-nm sources can also be used as pump sources for Thulium doped solid-state crystals to reach even longer wavelengths. In addition, there are several promising medical applications including dental applications such as bone ablation and medical procedures such as opthamology. These long wavelength sources are also key components in infra-red-counter-measure systems. We have extended our high performance 1500-nm material to longer wavelengths through optimization of design and epitaxial growth conditions and report peak CW output powers from single 1-cm diode laser bars of 37W at 1910-nm and 25W at 2070-nm. 1-cm bars with 20% fill factor were tested under step-stress conditions up to 110-A per bar without failure, confirming reasonable robustness of this technology. Stacks of such bars deliver high powers in a collimated beam suitable for pump applications. We demonstrate the natural spectral width of ~ 18nm of these laser bars can be reduced to < 3-nm with use of an external Volume Bragg Grating, as required for pump applications. We review the developments required to reach these powers, latest advances and prospects for longer wavelength, higher power and higher efficiency.

The regeneration of thermal wound on mice skin (Mus Musculus) after Q-Switch Nd: YAG laser irradiation for cancer therapy candidate

NASA Astrophysics Data System (ADS)

Apsari, R.; Nahdliyatun, E.; Winarni, D.

2017-09-01

The aims of this study are to investigate the regeneration of mice skin tissue (Mus Musculus) irradiated by Q-Switch Nd: YAG laser and morphological change due to Q-Switch Nd: YAG laser irradiation compared to conventional heating (hairdryer). The 2-3 month of twenty-seven mice were used for experimental animals. Mice were incised in the dorsum by the damage effect of laser energy dose (therapeutic dose) of 29.5 J/cm2 with 10 seconds of exposure time, 10 Hz of repetition rate, and 100 pulses of the given single pulse energy. The mice skin tissue was injuried by hairdryer to get burned effect. Mice were divided into three groups, Group I (control) were not treated by anything, Group II were treated by Q-Switch Nd: YAG laser irradiation and sacrificed on (0, 1, 3, 5) days, and Group III were treated by hairdryer then sacrificed on (0, 1, 3, 5) days. Pathology examination showed that the energy of 29,5 J/cm2 dose produced the hole effect (ablation) through the hypodermic layer caused by optical breakdown and collagen coagulation. Thus, the 60 °C temperature of burn showed coagulation necrosis because piknosis discovered in the injured area. The regeneration process showed that the mice skin tissue's ability to regenerate was irradiated by fast laser because of the focus of Q-Switch Nd: YAG laser. It was showed by the scab releases on third day and completely reepithelialization formation on the fifth day. The collagen fibers distribution was same as normal skin tissue on day 5 and so did angiogenesis. Therefore, Q-Switch Nd: YAG laser can be applied for problems of dermatology medical therapies, especially melasma, nevus of ota and tatto therapy. For skin cancer therapy application, energy dose of unregenerated skin tissue is chosen because the death expected effect is permanent.

Laser-induced cartilage damage: an ex-vivo model using confocal microscopy

NASA Astrophysics Data System (ADS)

Frenz, Martin; Zueger, Benno J.; Monin, D.; Weiler, C.; Mainil-Varlet, P. M.; Weber, Heinz P.; Schaffner, Thomas

1999-06-01

Although there is an increasing popularity of lasers in orthopedic surgery, there is a growing concern about negative side effects of this therapy e.g. prolonged restitution time, radiation damage to adjacent cartilage or depth effects like bone necrosis. Despite case reports and experimental investigations over the last few years little is known about the extent of acute cartilage damage induced by different lasers types and energies. Histological examination offers only limited insights in cell viability and metabolism. Ho:YAG and Er:YAG lasers emitting at 2.1 micrometer and 2.94 micrometer, respectively, are ideally suited for tissue treatment because these wavelengths are strongly absorbed in water. The Purpose of the present study is to evaluate the effect of laser type and energy on chondrocyte viability in an ex vivo model. Free running Er:YAG (E equals 100 and 150 mJ) and Ho:YAG (E equals 500 and 800 mJ) lasers were used at different energy levels using a fixed pulse length of 400 microseconds. The energy was delivered at 8 Hz through optical fibers. Fresh bovine hyaline cartilage samples were mounted in a water bath at room temperature and the fiber was positioned at 30 degree and 180 degree angles relative to the tissue surface. After laser irradiation the samples were assessed by a life-dead cell viability test using a confocal microscope and by standard histology. Thermal damage was much deeper with Ho:YAG (up to 1800 micrometer) than with the Er:YAG laser (up to 70 micrometer). The cell viability test revealed a damage zone about twice the one determined by standard histology. Confocal microscopy is a powerful tool for assessing changes in tissue structure after laser treatment. In addition this technique allows to quantify these alterations without necessitating time consuming and expensive animal experiments.

Resonantly pumped high efficiency Ho:YAG laser.

PubMed

Shen, Ying-Jie; Yao, Bao-Quan; Duan, Xiao-Ming; Dai, Tong-Yu; Ju, You-Lun; Wang, Yue-Zhu

2012-11-20

High-efficient CW and Q-switched Ho:YAG lasers resonantly dual-end-pumped by two diode-pumped Tm:YLF lasers at 1908 nm were investigated. A maximum slope efficiency of 74.8% in CW operation as well as a maximum output power of 58.7 W at 83.2 W incident pump power was achieved, which corresponded to an optical-to-optical conversion efficiency of 70.6%. The maximum pulse energy of 2.94 mJ was achieved, with a 31 ns FWHM pulse width and a peak power of approximately 94.7 kW.

Effect of CO2, Nd:YAG, and Er:YAG lasers on dentin and pulp tissues in dogs

NASA Astrophysics Data System (ADS)

Abt, Elliot; Wigdor, Harvey A.; Walsh, Joseph T., Jr.; Brown, Joseph D.

1992-06-01

Although there has been interest in lasers in dentistry since lasers were first developed in the early 1960's, this interest was limited until recently. Over the past five years there has been a flurry of interest to find the most effective wavelength and parameters of treatment. With this interest has come clinical and experimental reports. This project is a pilot study to investigate laser effects on dogs teeth. Multiple teeth from 2 dogs (n equals 40) were treated using either a CO2, Nd:YAG, or an Er:YAG laser, or slow-speed rotary instrumentation. One dog died after treatment and was not used in this study. The second dog was sacrificed four days after treatment with the lasers and the teeth were decalcified and processed for light microscopy. The dentin and pulpal tissues were then evaluated for changes from their normal histologic patterns. The purpose of this study was to first determine if the dog would be a good model for in-vivo histologic testing of lasers and second to evaluate the histologic effects of different lasers on dog's teeth. Our findings suggest that each laser causes a different degree of effect to the treated teeth. The specifics of these effects are discussed herein.

CTE:YAG laser applications in dentistry

NASA Astrophysics Data System (ADS)

Shori, Ramesh K.; Fried, Daniel; Featherstone, John D. B.; Kokta, Milan R.; Duhn, Clifford W.

1998-04-01

The suitability of CTE:YAG laser radiation was investigated for caries preventive laser treatments and caries ablation. Although, CTE:YAG laser radiation at 2.69 micrometer is less highly absorbed by dental hard tissues than other erbium laser wavelengths, namely 2.79 and 2.94 micrometer, it can readily be transmitted through a conventional low hydroxyl fiber with minimal loss. These studies show that reasonable ablation rates and efficiencies are obtainable with both free running (200 microseconds) and Q-switched (100 ns) laser pulses on both dentin and enamel with the application of a relatively thick layer of water to the tissue surface. The water served to remove tissue char and debris from the ablation site leaving a clean crater. However, mechanical forces produced during the energetic ablative process resulted in peripheral mechanical damage to the tissue. Surface dissolution studies on enamel indicated that CTE:YAG radiation inhibited surface dissolution by organic acid by 60 - 70% compared to unirradiated controls, albeit, at fluences an order of magnitude higher than those required for CO2 laser radiation. This layer system may be suitable for dental hard tissue applications if mechanical damage can be mitigated. This work was supported by NIH/NIDR Grants R29DE12091 and R01DE09958.

Response of feline intradental nerve fibers to tooth cutting by Er:YAG laser.

PubMed

Chaiyavej, S; Yamamoto, H; Takeda, A; Suda, H

2000-01-01

The aim of this study was to investigate the response of intradental A- and C-fibers during tooth cutting by Er:YAG laser. Bipolar electrical stimulation was applied to the cat's canine to identify functional single nerve fibers of the inferior alveolar nerve. The tip of the canine tooth was cut in 0.5-mm steps until the pulp was exposed. Teeth were alternately cut by using Er:YAG laser (50 mJ, 5 pps) and micromotor under water cooling. The nerve response recorded from the single nerve fibers during laser cutting was compared with that during micromotor cutting. All 26 A-fibers responded to laser cutting with high frequency of nerve firings. The nerve firing rate was significantly higher during laser cutting compared with that during micromotor cutting of superficial dentin (Chi(2) test, P < 0.05) but was not significantly different at deep dentin (P > or = 0. 05). Nine of 11 C-fibers responded to laser cutting when the deep dentin was cut. Among those nine nerve fibers, three also showed a low frequency response to laser cutting of the superficial dentin. During the tooth cutting, Er:YAG laser was more effective in activating intradental A-fibers compared with micromotor and also caused the activation of intradental C-fibers. Copyright 2000 Wiley-Liss, Inc.