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.