利用光纤偏振分束器和3 dB耦合器搭建偏振分集90°光学混频器,采用单端接收实现了偏振分集的相干接收机。实现了10 Gb/s偏振复用差分相移键控(DPSK)光信号,经过280 km普通单模光纤(SSMF)和掺铒光纤放大器(EDFA)传输后的数字相干接收,测量无误码。研究了数字相干光接收中的各种信号处理算法。采用数字信号处理算法完成载波相位估计,数字滤波器补偿光纤色散,恒模算法进行自适应数字偏振解复用等。研究了90°光学混频器的非理想正交特性,运用统计方法补偿了光学混频器偏离90°的误差,此算法和信号格式以及光纤色散等因素无关。使用恒模算法实现数字偏振解复用,该算法收敛时间小于0.5 μs。

Polarization beam splitters and 3 dB couplers are used to construct a home-made 90° optical hybrid,by which a polarization diversity optical coherent receiver is carried out with single-ended detection. A 10 Gb/s polarization multiplexed differential phase shift keying (DPSK) signal is transmitted through 280 km standard single-mode fiber (SSMF) using erbium-doped fiber amplifier (EDFA) amplification,and no error bits are measured in the result. The various digital signal processing algorithms in coherent detection are discussed. Carrier phase estimation,optical chromatic dispersion compensation and digital polarization demultiplexing are carried out. The phase error offset from the 90° of the optical hybrid is compensated by using statistical method. The algorithm is irrelevant with signal modulation format and fiber chromatic dispersion. Digital polarization demultiplexing is carried out by using constant modulus algorithm,and the convergence time of the algorithm is less than 0.5 μs