Electro-optic modulation with a constant modulation depth plays important roles in quantum metrology, microwave photonics, and optical precision measurement and sensing, etc. To compensate the continuous drift of the half-wave voltage and maintain the modulation depth, we incidentally generated a reference laser to make intermedia optical beatings with the carrier and +1st sideband, and tightly locked the carrier to sideband ratio by extracting the relative microwave power of those intermedia beat signals using a home-made electronic control module. Experiments of the short-term test for locking bandwidth, the anti-jamming capability, and the long-term stability were demonstrated. As is verified that, the locking bandwidth was estimated up to tens of kHz, and the anti-jamming capability was confirmed despite of a strong hair-dryer agitation. The long-term stability for the modulation depth stabilization showed that the peak-to-peak relative stability for 150-minute was 5.67 × 10 ⁻⁶ , and the Allan deviation reached a minimum of 2.19 × 10 ⁻⁷ at an averaging time of 400 s, which is improved by more than four orders of magnitude compared with the open-loop regime. We believe the reported method as well as the designed module is versatile and potential to precision measurement and sensing applications badly requiring a stable modulation depth, such as atom interferometry, optical interferometry and lidar detection.

中文翻译：

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通过中间光拍频稳定具有载波边带比的电光调制深度

具有恒定调制深度的电光调制在量子计量学、微波光子学、光学精密测量与传感等方面具有重要作用。为了补偿半波电压的连续漂移并保持调制深度，我们偶然产生了一个参考激光与载波和第+1边带进行中间光拍频，并通过使用自制电子控制模块提取这些中间拍频信号的相对微波功率来紧密锁定载波边带比。对锁定带宽、抗干扰能力和长期稳定性进行了短期测试。经验证，锁定带宽估计高达数十 kHz，并且在吹风机强烈搅动的情况下也证实了抗干扰能力。 ^-6 ，并且艾伦偏差在平均时间为 400 s 时达到最小值 2.19 × 10 ^-7，与开环机制相比提高了四个数量级以上。我们相信所报告的方法以及设计的模块是通用的，并且有可能用于急需稳定调制深度的精密测量和传感应用，例如原子干涉测量、光学干涉测量和激光雷达检测。