高重复率半导体激光抽运Nd：YAG放大器激光特性的实验研究

实验研究了高重复率、大功率半导体激光二极管阵列（LDA）侧面环绕抽运的Nd：YAG激光放大器的放大特性、热焦距变化和热致双折射效应引起的退偏特性。偏振光绎千赫兹高功率单通激光放大器，获得约3倍的光脉冲能量放大，脉冲宽度基本保持不变，其输出的P分量与S分量的能量比趋于常数3：1，实验测得的能量放大倍率及放大光束的椭圆偏振度与理论预期吻合很好。

大功率线阵激光二极管侧面抽运Nd：YAG激光器特性研究

对激光二极管（LD）抽运固体激光器中大功率线阵激光二极管三向对称侧面抽运的漫反射腔结构进行了研究。激光器使用Nd：YAG作为激光晶体，电光器件材料为KD^＊P晶体，漫反射体为陶瓷材料。实验表明，抽运光的利用率和均匀性有较大提高。在重复频率为10Hz下，实现了脉冲宽度8ns，最大平均功率为近2W的1064nm红外激光输出，激光器的效率有显著提高。

激光二极管侧面抽运调Q倍频Nd:YAG激光器

对高平均功率输出的激光二极管侧面抽运电光调Q倍频 Nd:YAG激光器进行了研究，当采用90个60W的脉冲激光二极管阵列抽运时，在重复频率为10Hz下，实现了最大平均功率为1180mW的1064nm红外激光输出，光-光转换效率为11%。腔外倍频获得600mW的532nm绿光输出，倍频效率达到50%以上。

A Q-swicthed all-solid-state single-longitudinal-mode laser with adjustable pulse-width and high repetition rate

A single-longitudinal-mode (SLM) laser-diode pumped Nd: YAG laser with adjustable pulse width is developed by using the techniques of pre-lasing and changing polarization of birefingent crystal. The Q-switching voltage is triggered by the peak of the pre-lasing pulse to achieve the higher stability of output pulse energy. The output energy of more than 1 mJ is obtained with output energy stability of 3% (rms) at 100 Hz. The pulse-width can be adjusted from 30 ns to 300 ns by changing the Q-switching voltage. The probability of putting out single-longitudinal-mode pulses is almost 100%. The laser can be run over four hours continually without mode hopping.

Dynamic analysis of V-folded cavity for TEM00 operation of end-pumped solid-state laser

Based on graphic analysis design method of optical resonator, a simple design expression of V-folded cavity of end-pumped solid-state lasers with TEM00 operation is described, which satisfies two criterias of the resonator design. We give numerical simulation of spot size as a function of thermal focal length using this design approach whose advantages are validated experimentally.

Numerical research of heat generation in flashlamp-pumped Nd : glass disk amplifiers

The heat generation in a flashlamp-pumped Nd:glass disk amplifier is studied by the simulation of the whole pumping process, which is based on the ray-tracing method. The results of temperature rise distribution as well as gain distribution are presented. The evolution of heat generation in disk during the pumping process is discussed in detail. Some main factors related with the thermal effect, such as the quantum efficiency, fluorescence lifetime, and pulse duration, are investigated through studying the ratio of the heat generation to energy storage in the gain medium. The influence of each parameter on heat generation is studied carefully, and the results provide ways to decrease the heat generation during the pumping process. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Depolarization loss compensated resonator for electro-optic Q-switched solid-state laser

A novel laser resonator for compensating depolarization loss that is due to thermally induced birefringence in active rod is reported. As this new structure being applied to an electro-optic Q-switched LIDA side-pumped Nd:YAG laser operating at a repetition rate of 1000 Hz, substantial reduction in depolarization loss has been observed, the output pulse energy is improved about 56% from that of a traditional resonator without compensation structure. With incident pump energy of 450 mJ per pulse, linearly polarized output energy of 30 mJ per pulse is achieved, the pulse duration is less than 15 ns, and the peak power of pulse is about 2 MW. The extinction ratio of laser beam is better than 10:1, and the beam divergence is 1.3 mrad with beam diameter of around 2.5 mm. (c) 2006 Published by Elsevier B.V.

Passively Q-switched Nd:YVO4 laser with a Cr4+:YAG crystal saturable absorber

We demonstrate, for the first time as far as Re known, a passively Q-switched operation of a Nd:YVO4 laser in which a Cr4+:YAG crystal and a laser-diode bar are used as the saturable absorber and the pump source, respectively. Stable laser pulses as short as 28 ns with 20-mu J energy can be generated with this laser, which has the advantages of simplicity, high efficiency, and good long-term stability. (C) 1997 Optical Society of America.

Efficient diode-pumped Yb : Gd2SiO5 laser

An efficient diode-pumped laser was demonstrated by using an ytterbium-doped laser crystal, Yb:Gd2SiO5 (Yb:GSO), wherein Yb3+ ions exhibit the largest ground-state splitting among all the ytterbium-doped crystals. The Yb:GSO laser can be operated at a low pumping threshold, and the most efficient laser occurs around 1088 nm since the corresponding emission band has the largest emission cross section and the lowest thermal population. A slope efficiency of 75% was demonstrated for a continuous-wave Yb:GSO laser at 1094 nm, and self-pulsed lasers were achieved within the tunable range of 1091-1105 nm, which are the longest laser wavelengths achieved for Yb3+ lasers. (c) 2006 American Institute of Physics.

Efficient tunable diode-pumped Yb : LYSO laser

We demonstrated efficient laser action of a new ytterbium-doped oxyorthosilicate crystal Yb:LuYSiO5 ( Yb: LYSO) under high-power diode-pumping. The spectroscopic features and laser performance of the alloyed oxyorthosilicate crystal are compared with those of ytterbium-doped lutetium and yttrium oxyorthosilicates. In the continuous-wave laser operation of Yb: LYSO, a maximal slope efficiency of 96% and output power of 7.8 W were respectively achieved with different pump sources. The Yb: LYSO laser exhibits not only little sensitivity to the pump wavelength drift but also a broad tunability. By using a dispersive prism as the intracavity tuning element, we demonstrated that the continuous-wave Yb: LYSO laser exhibit a continuous tunability in the spectral range of 1014-1091 nm. (c) 2006 Optical Society of America.

Room-temperature cw and pulsed operation of a diode-end-pumped Tm:YAP laser

We report the continuous-wave and acousto-optical Q-switched operation of a diode-end-pumped Tm:YAP laser. Continuous-wave output power of 3.5 W at 1.99 mu m was obtained under the absorbed pump power of 14 W. Under Q-switched laser operation, the average output power increased from 1.57 W to 2.0 W, with an absorbed pump power of 12.6 W, as the repetition rate increased from 1 kHz to 10 kHz. The maximum Q-switched pulse energy was 1.57 mJ with a repetition rate of 1 kHz. The minimum pulse width was measured to be about 80 ns, corresponding to a peak power of 19.6 kW.

Damage on HfO2/SiO2 high-reflecting coatings under single and multiple Nd:YAG laser pulse irradiation

The single- and multi-shot damage behaviors of HfO2/SiO2 high-reflecting (HR) coatings under Nd:YAG laser exposure were investigated. Fundamental aspects of multi-shot laser damage, such as the instability due to pulse-to-pulse accumulation of absorption defect and structural defect effect, and the mechanism of laser induced defect generation, are considered. It was found in multi-shot damage, the main factors influencing laser-induced damage threshold (LIDT) are accumulation of irreversible changes of structural defects and thermal stress that induced by thermal density fluctuations.

Laser-induced damage of Ta2O5/S1O2 narrow-band interference filters under different 1064 nm Nd : YAG laser modes

The laser-induced damage (LID) behavior of narrow-band interference filters was investigated with a Nd:YAG laser at 1064 nm under single-pulse mode and free-running mode. The absorption measurement of such coatings was performed with surface thermal lensing (STL) technique. The damage morphologies under the two different laser modes were also studied in detail. It was found that all the filters exhibited a pass-band-center-dependent absorption and laser-induced damage threshold (LIDT) behavior, but the damage morphologies were diverse. The explanation was given with the analysis of the electric field distribution and the operational behavior of the irradiation laser. (c) 2005 Elsevier B.V. All rights reserved.

High repetition rate Q-switched microchip Nd:YVO4 laser with pulse duration as short as 1.1 ns

We have demonstrated a compact and an efficient passively Q-switched microchip Nd:YVO4 laser by using a composite semiconductor absorber as well as an output coupler. The composite semiconductor absorber was composed of an LT (low-temperature grown) In0.25Ga0.75As absorber and a pure GaAs absorber. To our knowledge, it was the first demonstration of the special absorber for Q-switching operation of microchip lasers. Laser pulses with durations of 1.1 ns were generated with a 350 mu m thick laser crystal and the repetition rate of the pulses was as high as 4.6 MHz. The average output power was 120 mW at the pump power of 700 mW. Pulse duration can be varied from 1.1 to 15.7 ns by changing the cavity length from 0.45 to 5 mm. Pulses with duration of 1.67 and 2.41 ns were also obtained with a 0.7 mm, thick laser crystal and a 1 mm thick laser crystal, respectively. (C) 2007 Elsevier GmbH. All rights reserved.