Research and Development of OCDM system using 128 chip orthogonal sequence SSFBG Encoder/decoder

光码分复用（0CDM）是一种具有吸引力的技术，用于光子路径网络或下一代多媒体接入网，因为在发送端和接收端使用唯一的编码，并且用户共享相同的传输介质。与OTDM和WDM相比，它提供了更简单的光器件和网络控制，可以方便地构建复杂灵活的网络。近年来，一种具有相移的超结构光纤布拉格光栅（SSFBG）因其相关性能好、紧凑性高、与光纤系统兼容以及潜在的低成本而被提出用于相干OCDM。但是，相干OCDM系统除了存在非相干多重干扰问题外，还存在严重的相干信号干扰和噪声问题。由于热噪声增加了信号的功率，因此信噪比不随光接收功率的变化而变化。因此，需要超长芯片和极短脉冲的en/解码器通过码增益来提高信噪比。在本研究中，我们首次成功实现了将128片正交序列En/Decoder在OCDM系统中使用SSFBG的实验结果。正交码降低了互相关噪声，降低了相干信号干扰的拍噪声。实验上实现了17个用户以上的625mbps信号复用的可能性。

Optical code division multiplexing (0CDM) is an attractive technology for photonic path networks or for next generation multimedia access networks, since unique codes are used at the transmitter and receiver, and users share the same transmission media. It can facilitate the construction of a complex and flexible network because it provides simpler optical components and network control than OTDM and WDM. Recently, a super-structured fiber Bragg grating (SSFBG) with phase shift was proposed for coherent OCDM because of its good correlation property, high compactness, compatibility with fiberoptic systems, and potential low cost. However, the coherent OCDM systems have a serious problem of the coherent signal interference beat noise besides the incoherent multiple interferences issues. Because the beat-noise increases the power of signal, SNR is not changed with optical received power. So en/decoder with ultra long chips and extremely short pulses were required to increase SNR by the code gain.In this research, we successfully achieved the first time the experimental results using 128-chip orthogonal sequence En/Decoder in the OCDM system using SSFBG. Orthogonal codes reduce the cross-correlation noise, and the coherent signal interference beat noise. Over 17 users in 625 Mbps signal multiplex possibility is achieved experimentally.