相位偏移和分束比对八倍频光毫米波产生及传输的影响分析

nalysis of influence of phase shift drift and splitting ratio on octupling-frequency optical millimeterwave generation and distribution

相位偏移和分束比极大地影响了产生光毫米波信号的边带抑制比以及光纤无线(ROF)系统的BER。针对串联两个马赫-曾德尔调制器产生八倍频光毫米波信号的方案,利用贝塞耳级数展开的方法,推导了相位偏移和分束比影响下,光毫米波信号的严格通用解析解,当分束比偏离0.001,相位偏移1°时,边带抑制比可达35.9 dB,能够忽略谐波分量的影响。仿真结果表明,在BER=10-10的条件下,当八倍频光毫米波信号背靠背传输时,分束比偏离0.001和相位偏移1°的功率代价仅为0.001dB,经20 km标准单模光纤传输后的功率代价为0.145 dB,系统性能良好。

The influence of phase shift drift and splitting ratio on sidebands suppression ratio of optical millimeterwave and bit error rate （BER） of radio over fiber （ROF） system are great. For the scheme of optical millimeterwave generation with octupling-frequency using two cascaded Mach-Zehnder modulators, with the method of expanding Bessel series, an exact analytical solution for optical millimeterwave affected by phase shift drift and splitting ratio was derived. It followed that the undesired sidebands suppression ratio was 35.9 dB when the splitting ratio deviation was 0.001 and phase shift drift was 1°. The harmonic influence could be neglected in this case. Simulation results show that for 0.001 splitting ratio deviation and 1°phase shift drift, the power penalty value is 0.001 dB at BER of 10^-10 in back-to-back signal transmission. The power penalty value is 0.145 dB after 20 km transmission. The system performance is good.