连续调谐输出的多周期极化铌酸锂晶体光学参量振荡器

对基于多周期极化铌酸锂晶体(PPLN)的信号光单谐振准相位匹配光学参量振荡器(QPM—OPO)，进行了温度调谐的理论和实验研究。以激光二极管(LD)端面抽运的声光调Q Nd：YVO4全固态激光器为抽运源，获得了1369．7～1678．8nm无重叠波段连续可调谐输出。给出了1064nm Nd：YVO4激光器抽运下，由PPLN的极化周期和温度直接计算输出信号光波长的公式，以及由信号光波长和极化周期计算相应的晶体温度的公式。这样就可直接计算实现无重叠波段连续可调谐输出时不同极化周期所对应的温度调谐范围，而不必联立能量守恒和动量守恒公式，逐点进行尝试。另外，周期极化晶体的极化周期不可避免地较理想值有一定的偏移，且具有不均匀性，给出了利用实验获得的温度调谐曲线，对极化周期进行修正计算的方法。

Continuously Tunable Optical Parametric Oscillator Based on Multi-Grating Periodically Poled Lithium Niobate

Theoretical and experimental study is presented on temperature-tuned signal-resonated quasi-phase-matched optical parametric oscillator (OPO) in multi-grating periodically poled lithium niobate (PPLN) pumped by an acousto-optically Q-switched cw-diode-end-pumped Nd∶YVO4 laser. The continuously tunable signal output from 1369.7 nm to 1678.8 nm without wavelength overlap is demonstrated. The formula of calculating the signal wavelength as a function of the grating period and the temperature is given. The formula of calculating the temperature as a function of the signal wavelength and the grating period is also given. Based on those work, the relative temperature tuning ranges for each grating period to realize continuously tunable signal output without wavelength overlap can be calculated directly. So it does not need to solve simultaneous equations of energy and momentum conservation through point-by-point computation. In addition, the uniform deviation of the grating period in the whole periodically poled crystal from the ideal length is usually inevitable, as well as the random variation in the length of the domain. The method of correction computation on grating period is given by using the temperature tuning curve got in the experiment.