报道了利用国产半导体可饱和吸收镜(SESAM)实现端面抽运Nd∶YVO4激光器连续锁模(CWML)运转的实验结果。在V型腔结构的实验中观察到调Q锁模(QML)波形不稳并有较强的直流成份,通过选择小透过率输出镜和增加腔长,解决了这两个问题。在腔长从0.66m增至1.27m和1.86m过程中,直流分量从52%降到13.6%,0.3%,最终获得了重复频率约80 MHz的稳定连续锁模脉冲输出,光谱宽度为0.15 nm。在考虑晶体热效应基础上,利用ABCD矩阵方法设计了四镜Z型腔,获得了1 W左右的连续锁模输出,重复频率约150 MHz。分析和比较了V型腔和Z型腔的优缺点。

A diode end-pumped passively mode-locked Nd∶YVO4 picosecond laser with home made semiconductor saturable absorber mirror (SESAM) is presented. By choosing a low-transmission output coupler and extending the cavity length, the Q-switching mode-locked pulses are suppressed and the proportion of direct current is decreased in V shaped resonator. When the cavity length is increased from 0.66 m to 1.27 m and 1.86 m, the proportion of direct current is decreased from 52% to 13.6% and 0.3%. At last, a stable continuous mode-locked pulses are attained and the pulse repetition rate is 80 MHz. The spectral width is measured to be 0.15 nm. Considering the thermal effect of the crystal, a four-mirror Z-cavity is designed using the matrix method. Average output power of 1 W at a pulse repetition rate of 150 MHz is obtained. The benefit and disadvantage of the V-shaped cavity and the four-mirror Z-cavity are compared and analyzed.