温度补偿角度相位失配355nm紫外激光器

355nm ultraviolet laser with angle phase mismatch compensated by temperature

为研制高稳定、高转换效率的实用化小型紫外激光器,采用LD端面泵浦Nd:YVO4激光晶体,Ⅰ类角度相位匹配LiB3O5(LBO)晶体进行腔内倍频,Ⅱ类角度相位匹配LBO晶体进行腔内和频,基于比例微分积分(PID,proportion integration differentiation)补偿方式的数字温控模块精确温度调节,补偿非线性晶体角度相位匹配误差,研制了一台输出波长为355nm的小型紫外激光器。研制的激光器在重复频率为15kHz、LD泵浦功率为13.33 W时,355nm激光平均输出功率为1.24 W,LD输出波长为804nm,不在Nd:YVO4晶体吸收峰(808nm),但LD泵浦光到紫外激光的转换效率仍达到9.3%;激光器的输出脉冲宽度为9.8ns,光束质量因子M2x和M2y分别为1.8和1.7,2h内输出功率不稳定度为0.45%。通过调节温度补偿非线性晶体角度相位失配,为实现高稳定、高转换效率的实用化紫外激光器提供了技术参考。

To research and develop a compact ultraviolet laser with high stability and high efficiency, a mini type all-solid-state ultraviolet laser device at 355 nm is obtained with laser-diode end-pumped Nd： YVO4 crystal, intracavity frequency doubling and tripling employing two LiB3 05 （LBO） crystals with angle phase matching between of type Ⅰ and type Ⅱ, respectively. To enhance conversion efficiency in the experiment,the temperature of the frequency conversion crystals is accurately adjusted by employing proportion integration differentiation （PtD） digital temperature control modules with resolution of ±0. 01 ℃ to compensate the angle phase mismatch, which are led in by the fixed crystal clamps. Output performance of the 355 nm laser is as follows：at repetition frequency of 15 kHz, the average output power is 1.24 W at the pump power of 13.33 W,output wavelength of the pump source is 804 nm not at the absorption peak of Nd：YVO4 crystal of 808 nm, the conversion efficiency from diode laser to ultraviolet la- ser is about 9.3 %, pulse duration is of 9.8 ns, beam quality factors are Mx^2 = 1.8,My^2 = 1.7 and the power instability is 0.45 G within 2 h operation. By adjusting the temperature to compensate for the angle phase mismatch of the nonlinear crystals,a compact no-water-cooling ultraviolet laser with high stability and high conversion efficiency can be obtained.