分析了基于等效相移(EPS)技术的超结构光纤光栅(SSFBG)相位编/解码器的原理及特点, 提出并实现了一种双边带编/解码器。该编/解码器在不改变光纤光栅长度的前提下, 实现了+1级和+3级编解码谱的级联, 并很好地继承了等效相移技术所具有的设计灵活、制作精度低和与波分复用(WDM)系统兼容能力强等诸多的优点。理论及实测数据仿真结果均表明, 在光脉冲源匹配最佳的前提下, 双边带编/解码器较传统等效相移编/解码器而言, 使得基于该光纤光栅相位编/解码器的窄带相干光码分多址(OCDMA)系统的编解码性能提高了3 dB, 通过对比分析得到其本质原因在于双边带编/解码器结构提高了其单位长度内携带的相位信息量。

Principle and characteristic of super-structured fiber Bragg grating (SSFBG) en/decoder based on equivalent phase shift (EPS) are analyzed, and double band en/decoder is proposed. The +1st and +3rd spectra are successfully linked by designing grating structure with unchanging grating length. The new en/decoder well inherits the advantage of traditional equivalent phase shift, such as flexible design, low manufacture precision and strong wavelength-division-multiplex (WDM) compatible ability. The theoretical and experimental data indicate that double band en/decoder meliorates the en/decoder performance of coherent optical code division multiplex access (OCDMA) system by 3 dB. The essence is the improvement of phase information in unit grating length.