ASYMMETRIC CONTROL CHARACTERISTICS OF DYE BDN ON THE TWO TRAVELLING WAVES IN A RING YAG LASER

It is discovered experimentally that, when placing a plate of dye BDN in a ring YAG laser cavity, the dye shows asymmetric control actions on the clockwise and counter-clockwise travelling waves. Unidirectional dye Q-switched operation is realized in a ring cavity based on this property without the use of Faraday rotator, polarizer and half-wave plate. A simplified theoretical analysis of this phenomenon is presented.     

全固态三基色激光大屏幕投影显示实验

三基色激光显示具有亮度高、色彩鲜艳、清晰度高、功耗低等优点，文章介绍了激光显示原理，并报道了用全固态非线性频率转换技术获得波长分别为671nm，532nm，和473nm的红绿蓝三基色激光，在国内首次实现全固态激光全色投影显示实验，同时提出了今后全固态激光显示的发展方向。     

High power single-mode large-mode-area photonic crystal fiber laser with improved Fabry-Perot cavity

An Yb3 -doped double-clad large-mode-area photonic crystal fiber (LMA PCF) laser with 103-W single-mode continuous-wave output power is demonstrated using an improved Fabry-Perot (F-P) configuration. The slope efficiency of 83.2% and good beam quality (M2 = 1.2±0.1) are achieved without any thermo-optical problems, dichroic mirror surface damage, and drop of the slope efficiency in this system.     

EFFECTS OF THE QUALITY OF SUBSTRATE ON THE STRUCTURE AND SUPERCONDUCTING PROPERTIES OF Yba2Cu3O7-x THIN FILM

We have systematically investigated the structures, morphologies, microwave surface resistance, DC performances and the substrate qualities of three YBa₂Cu₃O_7-x(YBCO) thin films 30mm in diameter. The three samples deposited by the same process have been proved of different properties. It has been shown that the structure and superconducting properties of the thin film depend strongly on the quality of substrate.     

NORMAL-INCIDENCE QUANTUM WELL INFRARED PHOTODETECTOR WITHOUT GRATING COUPLER

The n-type GaAs/Al_xGa_1-xAs multiple quantum well infrared photodetectors have been demonstrated without any grating couplers. We have achieved a responsivity R_v of 1.7×10⁵V/W and a detectivity D_λ^* of 4.0×10¹⁰ cm (Hz)^1/2/W for a wavelength of 8.4 μm at a temperature T = 77 K in normal incidence.     

High-Efficiency High-Power Nd：YAG Laser under 885 nm Laser Diode Pumping

A high-efficiency high-power Nd：YAG laser under 885 nm laser diode （LD） pumping is demonstrated. The laser crystal is carefully designed, and the overlapping between the pump modes and the laser modes is optimized. The maximum output power at 1064 nm is 87W under the absorbed pump power 127.7 W, corresponding to a slope efficiency of 72.4% and an optical-optical efficiency of 68.1%. The optical-optical efficiency is 58.4% for the pump power emitted directly from the LD. To our best knowledge, this is the maximal optical-optical conversion efficiency obtained for the LD end-pumped Nd：YAG lasers so far.     

光抽运垂直扩展腔面发射激光器腔内倍频理论研究

建立了计入光波在非线性晶体中走离和相位失配情况下的光泵面发射激光器腔内倍频的速率方程理论模型,采用循环数值逼近的方法对该速率方程进行求解.以BBO,LBO,PPLN等非线性晶体为例,研究了晶体长度以及抽运功率等因素对倍频输出功率的影响,模拟结果与实验结果符合得较好. 关键词： 光抽运 垂直扩展腔面发射激光器 腔内倍频 数值模拟     

High-power ultraviolet 278-nm laser from fourth-harmonic generation of an Nd:YAG amplifier in CsB_3O_5 crystal

We report on the experimental investigation and theoretical analysis of a nanosecond pulse high power ultraviolet(UV) 278 nm laser by fourth-harmonic generation(FHG) of a 1112-nm Nd:YAG amplifier in LiB_3O_5(LBO) and CsB_3O_5(CBO) crystals. The UV laser delivers a maximum average power of 10.3 W at 278 nm with peak power of 36.8 k W under input pump power of 41 W at 556 nm. This is, to the best of our knowledge, the highest output power at the specific UV wavelength of 278 nm. We also performed the theoretical investigation on the FHG with a model in the Gaussian approximation of both spatial and temporal profiles, especially accounting for the two-photon absorption effect in CBO crystal for the first time. The average output power, pulse width, and beam spatial distribution of the UV laser were simulated. The theoretical calculations are in close agreement with the experimental results.     

2277-W continuous-wave diode-pumped heat capacity laser

A high power continuous-wave (CW) diode-pumped Nd:YAG laser operated in heat capacity mode is demonstrated by use of two identical highly efficient diode-pumped laser heads placed in a plane-plane resonator.The laser heads are uniformly pumped with a five-fold symmetrical side-pumping configuration, and each head is able to output maximum output power of 2200 W at 808 nm.Under a total pump power of 4290 W,the output power of the laser at 1064 nm is up to 2277 W,corresponding to an optical-to-optical efficiency of 53.1%.     

连续钛宝石激光器最佳输出透射率的测量

在连续钛宝石激光器中，在一定泵浦功率下通过直接测量腔内熔融石英片在不同入射角时的反射耦合输出，得到了激光器的最佳输出透射率。在两个不同的输出透射率条件下，测量激光器的泵浦阈值，经计算求得了不同泵浦功率下激光器最佳输出透射率的理论值。对浓度不同的钛宝石棒均作了测量和计算，测量值与理论值基本符合。