采用中心波长为888 nm的激光二极管作为抽运源，减轻了Nd:YVO4晶体中的热效应。通过合理的谐振腔设计，扩大激光晶体处的基模尺寸和振荡光在凹面腔镜处的入射角，减轻了激光晶体内部的热效应和谐振腔像散，提高了激光器的输出功率。采用四镜环形腔选模的办法，获得稳定的高功率单频激光输出。在吸收的抽运功率为67.5 W时，实现了最高功率为21.5 W的532 nm单频激光输出，其8 h功率稳定性优于±1%，光束质量M2<1.1，光光转换效率为31.9%。

A laser diode with the central wavelength of 888 nm is used as the pump source to mitigate the thermal load in the pumping progress. Through the optimization of the ring cavity, the mode size in the Nd:YVO4 crystal is enlarged, and the astigmatism of the cavity is minished. A figure "8" shaped ring cavity is employed to enforce the single-frequency operation. As a result, a stable, high-power, single-frequency green laser (M2<1.1) of 21.5 W is obtained with the optical-optical conversion efficiency of 31.9%, and power stability of ±1% for 8 h.