报道了基于磷酸钛氧铷(RTP)晶体的内腔式级联拉曼激光输出特性。采用半导体激光端面抽运声光调Q Nd:YAG晶体产生的1 064 nm激光作为基频光, 尺寸为4 ×4 ×20 mm3、沿x轴切割的RTP晶体作为拉曼增益介质。分别对X(ZZ)X和X(YY)X几何配置的RTP拉曼激光系统进行实验研究。X(YY)X几何配置的拉曼增益相对较低, 导致腔内不同非线性频率变换过程的竞争, 只测量到对应光参量振荡激光的输出。在X(ZZ)X几何配置下成功获得了271 cm-1和687 cm-1两个拉曼频移共同参与级联拉曼激光输出。高阶Stokes光随着抽运功率的增加而依次出现。在10 W入射抽运功率和15 kHz脉冲重复频率下, 获得了总平均输出功率480 mW, 转化效率4.8%的多波长激光输出。波长涵盖了1 000~1 200 nm之间各阶Stokes光。

The intracavity cascaded Raman laser output characteristics based on potassium titanyle phosphate (RbTiOPO4, RTP) crystal were reported. A diode end-pumped acousto-optic Q-switched Nd:YAG laser at 1 064 nm was adopted as the fundamental light. A 4 ×4 ×20 mm3 in size and along x-axis cut RTP crystal was used as the Raman gain medium. The RTP Raman laser systems with X(ZZ)X and X(YY)X configurations according to the Porto notations were designed for experimental study. The relatively low Raman gain of X(YY)X geometry configuration leads to the competition of different nonlinear frequency conversion processes in the cavity, and only the corresponding optical parametric oscillation output was measured. The cascaded Raman laser output with the Raman shifts of 271 cm-1 and 687 cm-1 was successfully achieved in the X(ZZ)X configuration. The high-order Stokes lines appeared successively with the increase of incident pump power. Total average output power of 480 mW and conversion efficiency of 4.8% were obtained under an incident pump power of 10 W and a pulse repetition frequency of 15 kHz. The laser wavelength includes different order Stokes ranging from 1 000 to 1 200 nm.