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考虑到星间微波光子链路中信号经远距离传输损耗大,利用前置光放大来提高链路的信噪比.建立了带前置光放大的星间微波光子链路模型,利用Bessel函数展开和Graf加法定理推导出了信噪比(SNR)的解析表达式.确定了对链路影响最大的主要噪声成分,在不同前置放大器增益的条件下,对调制器直流偏置相移进行了优化,使得在给定SNR要求下所需激光器输出光功率最小,并进一步分析了前置放大器增益对最小激光器输出功率和最优直流偏置相移的影响.数值仿真结果表明:随着前置放大器增益的增加,达到指定SNR所需的激光器输出功率变小,相应的最优直流偏置相移先减小后增大.对于QPSK调制信号,未加前置放大器时,SNR要达到15.56 dB(BER=10-9),激光器输出光功率至少为45 dBm,而前置放大器增益为15 dB时,只需要22.57 dBm.
Taking into account the large inter-satellite microwave photonic link signal transmission loss through the long-distance, the use of pre-light amplification to improve the link signal to noise ratio.A pre-light amplification with the establishment of inter-microwave microwave photon chain model, the use of Bessel function And the Graf addition theorem, the analytical expression of signal-to-noise ratio (SNR) is deduced. The main noise component that has the most influence on the link is determined. Under different preamplifier gain, the DC offset phase shift of the modulator The optimization results in the minimum required laser output power for a given SNR and further analyzes the effect of preamplifier gain on the minimum laser output power and optimal DC offset phase shift.The numerical simulation results show that with the increase of When the gain of the amplifier is increased, the output power of the laser required to reach the specified SNR becomes smaller, the corresponding optimal DC offset phase shift decreases first and then increases, and for the QPSK modulation signal, the SNR needs to reach 15.56 without the preamplifier dB (BER = 10-9), the laser output optical power is at least 45 dBm, whereas the preamplifier gain is only 15 dB at 22.57 dBm.