论文部分内容阅读
考虑发射机和接收机对准误差引起的信号衰落,推导出带前置光放大的星间微波光子链路输出信噪比(SNR)的解析表达式,并建立了基于平均SNR原则的链路优化模型。在给定SNR要求及对准误差条件下,对Mach-Zehnder调制器(MZM)直流偏置相移进行了优化,使所需激光器(LD)输出功率最小,并进一步分析了前置放大器参数对最小LD输出功率和最优直流偏置相移的影响。数值仿真结果表明,与增益相比,前置放大器噪声系数决定了指定SNR所需的最小LD输出功率。当对准误差角标准差为0.4μrad时,噪声系数加倍会使SNR达到15.56dB时所需的最小LD输出功率增加6.73dB。然而,前置放大器噪声系数对最优的直流偏置相移几乎无影响,噪声系数加倍后最优直流偏置相移的变化不会超过0.003π。
Considering the signal fading caused by the alignment errors of the transmitter and the receiver, an analytical expression for the output signal-to-noise ratio (SNR) of the intermicriferous microwave photonic chain with pre-light amplification is derived and the link based on the average SNR principle is established Optimize the model. The DC-offset phase shift of the Mach-Zehnder modulator (MZM) is optimized under the condition of SNR requirement and alignment error so as to minimize the output power of the required laser (LD) and further analyze the preamplifier parameter pair Effect of minimum LD output power and optimal DC offset phase shift. The numerical simulation results show that the preamplifier noise figure determines the minimum LD output power required for a given SNR compared to the gain. When the standard deviation of the alignment error is 0.4μrad, doubling the noise figure will increase the minimum LD output power required for SNR to 15.56dB by 6.73dB. However, the preamplifier noise figure has almost no effect on the optimal DC offset phase shift, and the best DC offset phase shift does not change more than 0.003π after doubling the noise figure.