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基于电光晶体马赫-曾德(M-Z)干涉仪的载波包络相位偏移频率(carrier-envelop offset frequency, f 0)调节方法是一种新颖的 f 0调节方法. 该方法通过改变脉冲包络而不改变载波频率实现对 f 0信号的调节. 本文对该方法所涉及的偏振控制装置进行了仿真, 分析了其中波片光轴偏差对输出激光偏振方向和偏振度的影响. 在实验上提出了一种光轴校准方法以减小波片光轴偏差带来的影响, 并对比了抽运电流调节方法和基于电光晶体M-Z干涉仪的 f 0调节方法对 f 0信号和光梳与激光拍频信号(beat note, f b)的影响. 实验结果表明改变抽运电流, 在 f 0调节量为9 MHz的情况下, 对 f b影响为7 MHz. 而在相同 f 0调节量下, 电光晶体M-Z干涉仪 f 0调节方法对 f b的影响为0.2 MHz, 仅为抽运电流对 f b影响的1/35, 从而验证了基于电光晶体M-Z干涉仪的 f 0调节方法可以有效降低对 f b的干扰, 为利用 f b锁定重复频率(repetition rate, f r), 进而实现光梳梳齿线宽的压窄提供了一种技术手段.Electro-optic-modulator (EOM) based Mach-Zehnder (M-Z) interferometer is a novel method of controlling the carrier envelope offset frequency ( f 0). It is achieved by adjusting the envelop of the pulse, while keeping the carrier frequency unchanged. In this paper, the polarization control device involved in this method is simulated, and the influences caused by the deviation of the optical axis of the wave plate on the polarization direction and the degree of output laser are analyzed. An optical axis calibration method is proposed to reduce the influence caused by the deviation of optical axis of wave plate. The effects of pump current and EOM based M-Z interferometer on f 0and the beat note ( f b) between the comb and the laser are compared with each other. The experimental results show that the effect of changing the pump current on f bis 7 MHz, when the f 0adjustment quantity is 9 MHz. Under the same f 0adjustment quantity, the influence of EOM based M-Z interferometer on f bis 0.2 MHz, which is only 1/35 of the influence of pump current. Therefore, it is verified that EOM based M-Z interferometer can effectively reduce the interference to f b. It provides a technical means to narrow the line width of optical comb by using f bto lock repetition rate ( f r) .
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中国物理学会期刊
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