Frequency-shifted feedback laser based on acousto-optic modulation was one research hotspot in the current,and it can produce a string of harmonic wave with same interval frequency. In order to generate multi-frequency laser,the frequency-shifted feedback laser method was adopted to design an all-fiber frequency-shifted amplified feedback loop. A theoretical model of laser heterodyne correlation was established and the numerical simulation was carried out. At the same time,a fiber amplifier was introduced into the loop,and the influence of gain coefficient on the corresponding intensity of each harmonic was studied. The selection of different gain parameters for each order frequency was verified. The results show that, frequency-shifted feedback loop could be used to achieve the high-frequency modulation,several times of the fundamental frequency modulation. The highest modulation frequency is up to 4GHz. The study lays the theoretical and experimental foundation for the research of the new system of high-frequency modulation laser.%基于声光调制的频移反馈激光器是目前研究的热点,它可以生成一串频率间隔相同的谐波.为了生成多频激光,采用移频反馈激光器的方法,设计了一种全光纤式移频-放大反馈环路,建立了基于频移反馈腔的激光外差相关理论模型,并进行了数值仿真.同时,在环路中引入光纤放大器,研究了增益系数对各阶次谐波相应强度的影响,验证了不同增益系数对各阶次频率的选择作用.结果表明,利用频移反馈回路,实现了数倍于基频的高频调制,最高调制频率可达4GHz.这为新体制高频调制激光的研究奠定了理论及实验基础.
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