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报道了采用自行研制的全光纤主振荡功率放大(MOPA)结构1064nm单频Yb光纤激光器抽运掺氧化镁的周期性极化铌酸锂(PPMgLN)晶体实现3.81μm输出的中红外连续波(cw)单谐振光学参变振荡器(OPO)。单谐振OPO通过e→e+e相位匹配,基于50mm长,28.5～31.5μm多周期的PPMgLN晶体(MgO掺杂摩尔分数为5%),选用其中29.5μm的周期,采用了两镜线性腔结构。在30℃的工作温度下,通过49 W的线偏振激光抽运,获得了最大功率4.25W,波长为3.81μm的闲频光输出,抽运阈值为5W,其对应量子转换效率为31.1%。实验还通过改变PPMgLN晶体的工作温度21℃～170℃,获得了中红外波长3.65～3.82μm激光输出,测量了相应OPO的输出光谱。通过对比实验所测得中红外光输出波长与两组不同的理论计算结果,发现当晶体工作温度大于110℃后,实验测量结果与理论计算结果有一定的偏差,这和实验中晶体在高温区控温精度有一定的关系。
This paper reports the use of MOPA 1064nm single-frequency Yb fiber laser to pump periodically polarized lithium niobate (PPMgLN) doped with MgO to achieve 3.81μm output of mid-infrared continuous wave (cw ) Single Resonance Optical Parametric Oscillator (OPO). The single-resonant OPO is based on a phase matching of e → e + e based on a 50 mm long, 28.5-31.5 μm multi-period PPMgLN crystal (5% molar MgO doping) with a period of 29.5 μm and a two mirror linear cavity structure . At a working temperature of 30 ℃, a 49 W linearly polarized laser was pumped to obtain an idler output of 4.25W and a wavelength of 3.81μm with a pumping threshold of 5W and a corresponding quantum conversion efficiency of 31.1%. The experiment also changed the working temperature of PPMgLN crystal from 21 ℃ to 170 ℃ and obtained the laser output of 3.65 ~ 3.82μm with mid-infrared wavelength. The output spectrum of the corresponding OPO was measured. The experimental results show that when the working temperature of the crystal is more than 110 ℃, the experimental measurement results deviate from the theoretical calculation. This is in agreement with the experimental results of the crystal in the high temperature region Temperature control accuracy has a certain relationship.