稳定的窄脉冲光源、高性能编解码器和具有旁瓣/噪声抑制功能的接收机是光码分多址(OCDMA)系统设计实现的3个关键模块。实验中利用增益开关脉冲光源,63位等效相移超结构布拉格光栅(EPS-SSFBG)相位编解码器和接收机门限调整技术实现了2.5 Gbit/s 60 km传输并得到了相应的误码曲线,系统在误码率(BER)等于10-9时的灵敏度为-22.5 dBm。实验结果表明,等效相移超结构布拉格光栅编解码器兼具高性能和可实现性,可用于实用化的光码分多址系统,而综合利用光域和电域的手段抑制旁瓣和噪声的影响是提高系统性能的重要手段。

There are three key modules in coherent optical code division multiple access (OCDMA) system: ultra-short optical pulse source, en/decoder and receiver. Equivalent phase shift super structured fiber Bragg grating (EPS-SSFBG) OCDMA en/decoders were experimentally demonstrated. 2.5 Gbit/s OCDMA experiment is shown to achieve 60 km error free transmission using gain switch laser diode, 63-chip EPS-SSFBG phase en/decoder and threshold adjustable receiver. The receiver sensitivity is -22.5 dBm at 10-9 bit error rate (BER). The experimental results prove that EPS-SSFBG en/decoder could be used in practical OCDMA system due to its high performance and realizability. It is a very important method to improve system performance by using optical and electrical processing to restrict noise and side lobe.