基于瑞利散射和受激布里渊散射(RS-SBS)的被动调Q掺铒光纤(EDF)激光器的输出脉冲序列具有重复频率低、脉宽窄、功率高的特点,适合光时域反射(OTDR)系统对脉冲光源的基本要求,但是输出的脉冲序列不够稳定。提出在被动调Q激光腔中插入声光调制器(AOM)构成主被动混合调Q激光器。实验结果证明,这种混合调Q的方法既保持了声光调制器主动调Q激光器输出脉冲序列重复频率低而且稳定的特点,又发挥了瑞利散射和受激布里渊散射被动调Q机制动态速度快、输出脉冲宽度窄的优势。在120～200 mW的抽运功率条件下,得到的脉冲序列重复频率从30 Hz～90 kHz连续可调,脉冲宽度最小可达20 ns,峰值功率最高可达200 W,脉冲重复频率稳定度优于5%,脉冲幅度起伏不大于10%。脉冲峰值功率和脉冲宽度受抽运功率的影响不大,但随着调制频率增加,脉冲峰值功率降低而脉冲宽度加宽。

Rayleigh scattering-stimulated Brillouin scattering (RS-SBS) passive Q switched Er-doped fiber (EDF) laser has the potential to achieve low repetition, short pulse duration and high peak power, which satisfy the requirement for the optical pulse source of optical time domain reflection (OTDR) system, but the repetition frequency is not stable enough for real application. So, a hybrid Q-switched Er-doped fiber laser by inserting an acousto-optic modulator (AOM) into the RS-SBS passive Q cavity was proposed and studied. For the pump level of 120～200 mW, the repetition frequency of the output pulse strain can be continuously adjusted from 30 Hz to 90 kHz. The peak power can be about 200 W and the pulse duration can be about 20 ns. The stability of the repetition frequency is better than 5% and the amplitude fluctuation is less than 10%. The peak power and pulse duration are almost independent on the pump level, but the peak power will reduce and the pulse duration will increase as the modulation frequency increases.