二维光正交码编码光码分多址系统研究

利用光纤布拉格光栅（FBG）阵列，每用户在时间和波长上进行二维光正交（OOC）码编码，传输速率从70Mbps到1．4Gbps，在2个发送用户和1个接收用户的条件下，实现了光码分多址（OCDMA）通信。研究了FBG编码器所决定的系统用户传输速率对系统性能的影响，结果表明，在并发用户数小于OOC码码重，系统用户速率超过限制速率3倍以内时，对系统性能的影响不大。当码重大于9时．随着用户地址码码长的增加，速率超过限制速率对系统性能的影响相对较小。在相同误码率要求前提下，地址码较长系统可以突破限制速率的2～3倍。理论分析和实验研究表明，FBG间距条件所决定的速率限制，并非不可逾越的必要条件。

The Characteristics of Two-dimension Optical Othrogonal Code Encoding OCDMA Communication with Bragg Gragting Arrays

Optical code-dimension multiple-access(OCDMA) system,can provide very attractive features,such as asynchronous access,privacy and security in transmission,ability to support variable bit rate and scalability of the network.In this paper,a time/frequency optical orthogonal encoding(OOC) OCDMA system with fiber Bragg grating(FBG) arrays is developed,and the transmission rates up to 1.4 Gbps per user can be achieved.The effects of data rate on the performance of the system are studied theoretically and experimentally.It is proved that even if the data rate is beyond the critical value determined by the distance between FBG essential for the prevention of code overlapping,the performance of the system can still be satisfied;if the user number is lower than the weight of the OOC code or the code weight is larger than 9,the system's error rate will not increase obviously when the data rate exceeds the critical value.