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宽带波导型电光调制器(EOM)可以施加多个频率射频信号,通过3个频率的合成,在激光载波上调制出3对边带。利用这3对边带某一侧的3个频率信号进行Pound-Drever-Hall(PDH)频率锁定实验,通过调整其中某一个频率信号的相位,可以实现对频率锁定误差信号基线的调整。频率锁定系统中的剩余幅度调制(RAM)噪声同样造成误差信号基线的漂移,通过主动反馈控制系统调制频率信号的相位,实现了对剩余幅度调制噪声的抑制。实验表明,在主动反馈系统闭环后,对剩余幅度调制噪声的抑制程度达到30 d B以上,并有效地抑制了噪声漂移。
The wideband waveguide electro-optic modulator (EOM) can apply multiple frequency RF signals and synthesize three pairs of sidebands on the laser carrier by synthesizing three frequencies. Pound-Drever-Hall (PDH) frequency locking experiment is carried out by using the three frequency signals of one side of the three pairs of sidebands. By adjusting the phase of one of the frequency signals, the baseline of the frequency locking error signal can be adjusted. Remaining amplitude modulation (RAM) noise in the frequency-locked system also causes a drift of the baseline of the error signal. By actively controlling the phase of the system frequency signal, the residual amplitude modulation noise is suppressed. Experiments show that after the closed loop of the active feedback system, the residual amplitude modulation noise is more than 30 d B, and the noise drift is effectively suppressed.