理论分析和模拟仿真了双单边带离散多音频(Twin-SSB-DMT)信号经全光波长变换(AOWC)实现的多路传输。从理论方面研究双单边带信号的产生原理, 并对转换光与原始信号光之间的关系进行了分析。通过设置推挽式调制器双臂射频信号, 得到左单边带为离散多音频-正交幅度调制(DMT-4QAM)、右单边带为DMT-16QAM的双单边带信号。传输速率为20 Gbit·s-1的双单边带信号经过半导体光放大器中四波混频效应产生了1~8路高质量的转换光, 且转换光携带原始信号光数据, 从而实现高阶信号的多播传输。模拟结果表明: 双单边带DMT信号在低成本下提高了频谱效率和波长带宽的利用率, 改善了整个AOWC系统的性能。从星座图和误码率曲线可以看出, 接收端可对8路偏振不敏感的多播信号实现无串扰直接接收, 信噪比代价低, 进而有利于实现高质量的多播系统。

The multichannel transmission of dual single sideband discrete multitone (Twin-SSB-DMT) signal based on all-optical wavelength conversion (AOWC) is investigated theoretically and simulated. The generation principle of the dual single sideband signal is studied theoretically, and the relationship between the converted signal and the original signal is analyzed. The dual single sideband signal, which is with the left single sideband modulated by discrete multitone-quadrature amplitude modulation (DMT-4QAM) and the right single sideband modulated by DMT-16QAM, is obtained when we set the radio-frequency signal in the push-pull modulator. High-quality converted signals of 1-8 channels are generated through the four-wave mixing of 20 Gbit·s-1 dual single-sideband signal in the semiconductor optical amplifier. The converted signal contains the original data, and the multicast transmission of high-order signal can be achieved. The simulation results show that the dual single sideband DMT signal improves the spectral efficiency and the utilization of wavelength bandwidth, reduces the cost, and improves the performance of the whole AOWC system. In addition, according to the constellation and bit error rate curves, 8-channel polarization-insensitive multicasting signals can be directly received without crosstalk, and the cost of signal to noise ratio is low, which is good for achieving the high-quality multicast system.