对基于周期极化掺氧化镁的铌酸锂(PPMgO:CLN)晶体的光参量放大器(OPA)进行了理论分析和实验研究。模拟了PPMgO:CLN晶体准相位匹配(QPM)波长-温度调谐曲线和OPA中各光波平均功率随晶体长度的变化曲线，并进一步分析了最佳晶体长度的影响因素。当常温极化周期为31.3 μm的PPMgO:CLN晶体工作在150 ℃时,用平均功率为44 W的调Q NdYAG激光器抽运OPA,注入OPA内的2.765 μm激光的功率由4 W定标放大至13.3 W,转换效率为21.14%。

对基于周期极化钽酸锂(PPLT)晶体的光参变振荡器（OPO）技术进行了理论分析和实验研究，通过三波混频耦合波方程组，计算了PPLT-OPO的波长调谐曲线。分别研究了信号光单谐振结构（SSRO）和闲频光单谐振结构（ISRO）下，PPLT-OPO的中红外激光输出特性。当NdYAG激光器输出的1.064 μm激光抽运功率为48 W，重复频率为5 kHz时，SSRO和ISRO输出的3.9 μm中红外激光功率分别为5.78 W和5.07 W，相应的转换效率分别为12%和10.6%，ISRO输出的3.9 μm激光的近场光斑分布和光束质量优于SSRO的输出结果。

We present a 3~5 \mum optical parametric oscillator (OPO) based on ZGP pumped by KTP OPO 2.1-\mum laser. The tuning curves of ZGP OPO are calculated. The 8 \times 6 \times 18 (mm) ZGP crystal, whose end faces are antireflection coated at 2.1 and 3.7~4.6 \mum, is cut as \theta =53.5o, \phi =0o. When the pump power of 2.1-\mu m polarized laser is 15 W at 8 kHz, 5.7-W output power and 46.6% slope efficiency are obtained with a ZGPtype I phase match. Central wavelengths of the signal and idler lasers are 4.10 and 4.32 μm, respectively. Pulse duration is about 27 ns. Beam quality factor M2 is better than 1.8. The tunability of 3~5 \mu m can be achieved by changing the angle of the ZGP crystal.

报道了采用1064 nm激光抽运周期极化掺杂氧化镁的铌酸锂(PPMgO\:CLN)晶体光参变振荡器(OPO)实现高效率2.7 μm可调谐激光输出的实验结果，理论计算了PPMgO\:CLN晶体准相位匹配(QPM)温度调谐曲线。在1064 nm激光抽运功率为182 W，声光Q开关工作频率为10 kHz和PPMgO:CLN晶体工作温度为150 ℃条件下，获得了平均功率为36.7 W、波长为2.73 μm中红外激光输出，斜率效率为23.7％。通过改变周期为31.3 μm PPMgO\:CLN 晶体的工作温度30 ℃～200 ℃，获得了中红外波长3.0～2.6 μm激光输出，波长温度调谐实验结果与理论分析结果有大约10 ℃的差异。

The theoretical analysis and experimental results of the wavelength tunability of a tandem optical parametric oscillator (TOPO) based on a single nonlinear crystal are presented. TOPO is a configuration wherein the signal laser is used as a pump laser to generate secondary optical parametric oscillator (OPO). The cascaded parametric interactions are achieved synchronously in a single-grating-period MgO doped periodically poled lithium niobate (PPMgOLN). Tunable multiple-wavelength mid-infrared (mid-IR) lasers are obtained by changing the temperature of the crystal. When the PPMgOLN crystal with a grating period of 31.2 μm is operated at 148 oC, the dual OPOs generate an identical mid-IR laser of 2.83 \mum. The secondary OPO transforms into an optical parametric amplifier, in which different frequency mixing from the signal laser results in the amplification of the idler laser in the first OPO. TOPO is a useful configuration for multiple laser output, broad tuning range, and high-efficiency mid-IR lasers.

报道了一台高单脉冲能量的光参量振荡(OPO)2 μm固体激光器。采用电光调Q, Nd:YAG激光器输出的1064 nm激光, 抽运腔内两块光轴方向相向放置的KTP晶体, 通过双谐振光参量振荡(DROPO)技术获得2 μm激光输出。OPO谐振腔由2 μm反射镜、两块走离补偿的KTP晶体和2 μm输出镜组成。KTP晶体尺寸为8 mm×8 mm×15 mm, 切割角θ=53°, φ=0°。OPO采用Ⅱ类相位匹配(o→o+e)。当激光二极管单脉冲能量为1.02 J, 电光Q开关频率为30 Hz时, 获得了单脉冲能量107 mJ的简并波长2.1 μm激光输出, 808 nm激光二极管到2.1 μm光光转换效率为10.5 %, 光束质量因子分别为M2x=2.38, M2y=1.56。

通过1064 nm激光抽运KTP晶体内腔光参量振荡(OPO)技术获得了近衍射极限的2.68 μm激光输出,对实验结果开展了详细的分析。抽运源为声光调Q Nd:YAG激光器,光参量振荡器谐振腔采用双谐振结构,将两块相同的KTP晶体光轴相向放置以补偿走离效应,KTP晶体按φ=0°,θ=62°切割以获得波长2.7 μm激光输出,采用Ⅱ类相位匹配(o→o+e)以利用较大的非线性系数。在808 nm激光二极管抽运功率为330 W,声光Q开关工作频率为7 kHz的条件下,获得平均功率7.6 W,波长2.68 μm激光输出,光束质量因子M2小于1.6,对应信号光1.765 μm激光输出功率约14 W。