A 320-Gb/s Capacity (32-User × 10 Gb/s) SPECTS O-CDMA Network Testbed With Enhanced Spectral Efficiency Through Forward Error Correction

Abstract—This paper demonstrates a high-performance optical-code-division-multiple-access (O-CDMA) network testbed using the spectral phase encoded time spreading (SPECTS) method. Through additional time and polarization multiplexing, a total of 32 10-Gb/s users are supported while sharing eight O-CDMA spreading codes. User detection is achieved with time gating and nonlinear thresholding to suppress the multiaccess interference of other users. Incorporation of forward error correction success-fully reduces the performance loss imposed by coherent beat in-terference, resulting in error-free performance (BER < 10−11), significant per-user power penalty reduction, and the elimination of a bit-error-rate noise floor. The testbed also applies bandwidth suppression within the encoders and decoders, yielding a 52% increase in spectral efficiency. Index Terms—Forward error correction (FEC), multiaccess communication, optical code division multiaccess (O-CDMA), optical fiber communication, phase coding. I