论文部分内容阅读
为克服长距离光纤有线电视(CATV)系统中采用高增益掺铒光纤放大器(EDFA)所带来的非线性损伤,对在残留边带调幅(AM-VSB)外调制光纤有线电视系统中采用光纤分布拉曼放大时的组合二阶失真(CSO)进行了理论研究。根据拉曼放大对信号光强的增益作用,导出了分布拉曼放大条件下的薛定谔方程,并采用微扰法解出了存在拉曼分布放大时,残留边带调幅外调制有线电视系统中,自相位调制(SPM)导致的组合二阶失真的解析表达式。相应数值计算结果表明,相对于采用掺铒光纤放大器功放,采用相同放大倍数的分布拉曼放大可使长距离系统中自相位调制导致的组合二阶失真性能改善10 dB以上。因此可以得出结论:在长距离残留边带调幅调制的有线电视系统中,采用分布式光纤拉曼放大可以较好地改善由自相位调制导致的组合二阶失真恶化。
In order to overcome the nonlinear damage caused by the high-gain erbium-doped fiber amplifier (EDFA) in the long-distance optical fiber cable television (CATV) system, optical fiber The second order distortion (CSO) in distributed Raman amplification is studied theoretically. According to the gain effect of Raman amplification on signal light intensity, the Schrödinger equation under the condition of distributed Raman amplification is deduced and the perturbation method is used to solve the problem that, in the presence of Raman distribution amplification, Analytic Expression of Combined Second Order Distortion Due to Self Phase Modulation (SPM). The corresponding numerical results show that, compared with the EDFA with EDFA, the Raman amplification with the same gain can improve the combined second-order distortion performance caused by the self-phase modulation in long-haul systems by more than 10 dB. Therefore, it can be concluded that distributed optical fiber Raman amplification can significantly improve the combined second-order distortion degradation caused by self-phase modulation in cable systems with long-distance residual sideband AM modulation.