室温工作的连续可调谐相干光源在痕量气体检测技术中有着重要应用价值,光学非线性变换是获得室温运转中红外相干光源的有效途径,是对传统激光技术的有效补充。研究了基于准相位匹配原理的差频激光系统的温度和信号光波长调谐特性,从准相位匹配技术的一般位相匹配关系出发,推导了PPLN晶体差频准相位匹配的温度和信号光波长匹配带宽解析表达式; 建立了基于PPLN晶体准相位匹配原理的宽调谐差频中红外激光系统,实现了3.2～3.7 μm中红外相干光输出,最大输出功率约为1 μW; 对系统温度和信号光波长调谐特性进行实验研究,并与理论结果进行了比较和分析。

The room-temperature continuous-wave tunable narrow band coherent light source in the mid-infrared region is valuable for trace gas sensing. Nonlinear optical difference-frequency generation (DFG) scheme has been used as a useful way to meet the requirement, and complementarity for traditional laser technology. The temperature and signal light wavelength tuning characteristics of quasi-phasematching (QPM) based DFG system were theoretically studied, the analytical expressions of temperature and signal light wavelength tuning bandwidths of periodically poled LiNbO3(PPLN) were deduced based on the general theory of QPM. A widely tunable room-temperature mid-infrared laser source system based on QPM in PPLN crystal has been developed, and the mid-infrared coherent radiation is produced from 3.2 to 3.7 μm with a maximum output power of about 1 μW. The temperature and signal wavelength tuning characteristics of the system were experimentally studied, and the experimental results were compared and analyzed with the theory.