报道了利用声光振幅调制锁模的方法,在激光二极管端面抽运Nd∶YVO4激光器上获得320 MHz高重复频率脉冲列的实验结果。实验采用平平腔结构,腔长452 mm,耦合输出镜透过率为3.6%。所用声光介质为熔融石英晶体,以铌酸锂作换能器,在驱动功率4.5 W时,对1064 nm波长衍射效率为5%,相应的调制深度为0.31。在最佳锁模状态下,激光二极管抽运功率为3.5 W,此时激光平均输出功率为15 mW,示波器记录脉冲宽度680 ps,实测光束质量因子M2小于1.5。并在实验基础上对激光器工作的稳定性进行了分析,结果表明在腔长变化不超过±100 μm时,输出波形仍是稳定的。

The experimental results of an active mode-locked Nd∶YVO4 laser end-pumped by a laser diode (LD) are reported. Laser pulses at repetation rate of 320 MHz are gained. The curvature radii of two cavity mirrors are both infinite, the cavity length is 452 mm, and coupling-out mirror transmittance is 3.6%. A high frequency melted quartz acousto-optic modulator (AOM) is used as inner modulator. With the LiNbO4 crystal as energy transducer and driving power of 4.5 W, the diffractive efficiency at 1064 nm wavelength and modulating depth are 5% and 0.31, respectively. The laser average output is 15 mW at optimal mode-locking status (the pumping power is 3.5 W), and pulse width is 680 ps. The measured beam quality factor M2 is less than 1.5. Moreover, this laser pulse train is stable when cavity length deviates no more than ±100 μm.