微片激光器由于自身的内应力会输出频率分裂的正交偏振的两个模式。研究了回馈对微片激光器频差的影响。研究发现：在回馈的作用下微片激光器的频差大小呈现出以初始频差为中心的类正弦的频差调制，周期为λ/2；频差调制曲线的幅度与回馈水平成正比，但是当回馈水平过强时会出现偏振态跳变，从而使频差消失；在一定的回馈外腔范围内，频差调制曲线的幅度与初始频差亦成正比。并利用复合腔模型和激光器的自洽理论进行了理论分析和模拟，所得结果与实验结果相符。此调制现象在精密测量领域有潜在应用。%Microchip laser can output two orthogonal frequency splitting modes due to its own internal residual stress. In this paper it is found that the frequency difference of microchip laser is modulated by laser feedback. The modulation is a sinusoid-like curve whose center is the original frequency difference and period is half-wavelength. The amplitude of the modulation curve is proportional to feedback level. But when the feedback is too strong, so that the polarization switching occurs and only one polarization exists sometimes. In a range of external cavity, the amplitude of the modulation curve is also proportional to original frequency difference. The theoretical analysis and simulation based on the composite laser cavity theory and self-consistent theory are in good agreement with the experimental results. The potential applications of this phenomenon in precision measurement are discussed.
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