基于SOA全光偏振调制的双信道PolSK光传输系统

Dual-Channel PolSK Optical Transmissions Using SOA-Based All-Optical Polarization Modulations

提出一个新颖的采用两个级联半导体光放大器(SOA)作为独立全光偏振调制器实现双信道偏振态位移键控(PolSK)光传输系统方案,并进行了实验验证。从发射机端输出的PolSK光信号具有四个偏振态,构成了两个独立的二进制数据信道。各信道数据可以采用不同的码制,码率以及不同的时钟信号。该系统方案,提高了通信系统的比特-符号比以及频谱利用率;又由于PolSK光信号功率恒定,减小了光纤链路中非线性效应对光信号的影响提高了通信系统长距离数据传输能力;在接收机端实现了光信号的直接偏振检测,简化了接收机的设计和成本;又由于采用了稳偏接收模块使接收系统能够实现稳定信号接收。构成了基于本方案的实验系统,进行了一系列基础实验和性能测试。分别进行了50 km,80 km以及100 km长距离光纤数据传输实验,实验结果表明所提出的系统方案是有效的。

We propose and experimentally demonstrate a novel dual-channel polarization shift-keying （PolSK） optical transmission system, in which two semiconductor amplifiers （SOAs） are cascaded as two individual all-optical polarization modulators for each channel. The formed PolSK signals have four states of polarization （SOP）, constituting two orthogonal binary data channels. Each channel can independently transmit data streams with different formats, bit rates and clock signals. The transmitted PolSK signals can be directly detected, it greatly simplifies the design of the receiver and eventually reduces the system cost. With this scheme, the system capacity for data transmissions can be doubled. Furthermore, due to the constant optical power of PolSK signals, the transmission system can enhance its tolerance to nonlinear effects in the fiber link, increase its long-distance transmission capacity. The SOPs of received signals are easily tracked by using two polarization stabilizers in each branch of the receiver, respectively, in order to achieve a stable signal receiving. The experimental setup based on the proposed scheme was constituted and several basic experiments were carried out for investigating the system＇s performance. The long-distance data transmissions over 50 km, 80 km and 100 km fiber links, respectively, are carried out and the experimental results prove that the feasibility of our proposed scheme is validated.