基于超结构光纤光栅的正交四相光码分多址编／解码器

Orthogonal Quaternary Phase OCDMA En/Decoder Based on Super Structured Fiber Bragg Gratings

正交四相序列编码相比于二相序列具有更大的码字容量和更好的互相关特性,因此更适用于光码分多址(OCDMA)无源光接入网。提出并实现了一种基于超结构光纤光栅的正交四相光码分多址编/解码器。该编/解码器采用A族四相序列作为地址码,在制作的过程中仅需一个均匀相位掩模板即可实现编码功能,并且在性能上与传统工艺制作的编码器相当。为了与不同波长信道相匹配,提出了变信道编码技术,仿真结果表明采用该技术的编码器具有更高频谱效率,因此得到更好的编/解码性能。对一个码长63,长度4.1cm的正交四相编/解码器进行了信息速率为2.5Gb/s,码片速率为156Gchip/s的编/解码实验,取得了较好的编/解码效果。

Compared to bipolar sequences, orthogonal quaternary phase sequences are more suitable for optical code devision multiple access （OCDMA） passive optical network （PON） with multi-users for its larger capacity and better cross-correlation character. A orthogonal quaternary phase OCDMA en/decoder based on superstructured fiber Bragg grating is proposed and realized. The proposed en/decoder adopts family A four phase sequences as its address codes and obtain equivalent performance compared to the traditional en-decoder while it needs only one uniform phase board during its fabrication. In order to be compatible to different channels, a novel coding technology is proposed which can encode the user＇s data with a changed channel. Simulation results show that the en/deconders have higher frequency spectrum efficiency and therefore better en/decoding performance. A 2.5 Gb/s, 156 Gchip/s en-decoding experiment is performed using an en-decoder with its code length 63 and length 4. 1 cm, and good en/deconding results are achieved.