针对外调制星间微波光子链路输出信噪比优化问题，建立了基于双电极马赫-曾德尔调制器的强度调制直接探测星间微波光子链路模型，通过优化调制器调制方式来提高链路性能。用数值模拟方法得到了单边带、双边带和推挽式3种调制方式下链路输出信噪比，利用曲面投影法求得了最优调制方式时一定信噪比要求下发射端所需最小光放大器增益和对应的调制器直流偏置相位。结果表明：相同输入射频信号功率和发射光功率情况下，双边带调制输出信噪比比单边带调制高3 dB，低直流偏置相位推挽调制可以进一步优化输出信噪比。输入射频信号功率为-20 dBm，输出信噪比为17.3 dB时，所需最小光放大器增益为43.9 dB，对应的直流偏置相位为0.87π。

To the output signal-to-noise ratio (SNR) optimization of inter-satellite microwave photonic link, the direct intensity modulation detection inter-satellite microwave photonic link based on dual-electrode Mach-Zehnder modulator (DE-MZM) was modeled, the link performance was improved by optimizing the modulation mode. The link output SNR under single-sideband (SSB), double-sideband (DSB) and push-pull modulation was derived by numerical analysis. The minimum optical amplifier gain of the transmitter and the corresponding optical modulator DC bias point with the given output SNR were obtained by curved surface projection method. The results show that, when the input signal power and the optical emission power remain unchanged, the SNR of DSB modulation is 3 dB higher than SSB modulation, and the optimum SNR is obtained with low DC bias of push-pull modulation. When the input signal power is -20 dBm and the output SNR is 17.3 dB, the needed minimum optical amplifier gain is 43.9 dB, and the corresponding DC bias phase is 0.87 π.