Driving system for Mach–Zehnder electro-optic modulators in microwave photonics

Abstract

In order to obtain a modulation signal with high bandwidth and highly stable output power without distortion, an electro-optic modulator driving system with quick response to the input signal is designed in this paper. The system mainly includes three parts: power supply module, microwave signal generation module, and automatic gain control (AGC) module. The power supply module provides appropriate voltage and current for other two modules. The microwave signal generation module is used to generate microwave signals. The AGC module adopts the digital AGC control structure and the PID control principle to achieve stable control of the output power of the microwave signal. The hardware is developed, and the software algorithm is integrated into the driving system to verify the effectiveness and stability. The experimental results show that the bandwidth of the AGC module reaches 20 GHz. The proposed AGC module can effectively stabilize the output power of the microwave signal at 10 dBm with fluctuations less than ±1.5 dB, and its stability is improved by 74.95% compared to existing instrument. When the input power changes at 10 KHz, the system can still achieve stable control performance and has exhibited excellent dynamic response characteristics.