设计出一种基于级联非线性频率变换的634,644,655 nm多波长激光器。该复合变频过程由磷酸钛氧钾(KTP)和砷酸钛氧钾(KTA)晶体共同完成。首先由沿x轴切割的KTP晶体的光参量振荡将波长为1064 nm的激光变频为1572 nm,然后基于(θ=90°,φ=20.9°)切割KTA晶体完成1064 nm与1572 nm的和频过程,获得波长为634 nm的激光输出,进一步利用前述沿x轴切割KTP晶体的拉曼变频,将634 nm激光变频为644 nm的一阶拉曼光及655 nm的二阶拉曼光,实现634,644,655 nm多波长激光同时输出。该复合变频多波长激光器的最大平均输出功率为1.7 W,相应的脉冲宽度为19.3 ns,重复频率为6 kHz。

In this study, we describe a multi-wavelength laser at wavelengths of 634, 644, and 655 nm based on cascaded nonlinear frequency conversion. The cascaded frequency conversion process is jointly performed using the KTiOPO4 (KTP) and KTiOAsO4 (KTA) crystals. First, optical parametric oscillation is conducted in an x-cut KTP crystal to convert the 1064-nm laser into a 1572-nm laser. Sum frequency generation is subsequently achieved in a (θ=90° and φ=20.9°)-cut KTA crystal for the sum frequency mixing of 1064 and 1572 nm, generating a 634-nm laser output. Raman frequency conversion is further utilized in the x-cut KTP crystal to convert the 634-nm laser into first-order Raman radiation at 644 nm and second-order Raman radiation at 655 nm, simultaneously achieving multi-wavelength emissions at 634, 644, and 655 nm. The cascaded frequency multi-wavelength laser has a maximum average output power of 1.7 W, a pulse width of 19.3 ns, and a repetition rate of 6 kHz.