An eight-user time-slotted SPECTS O-CDMA testbed: demonstration and simulations

This paper demonstrates an eight-user 9 Gb/s/user time-slotted spectral phase-encoded time-spreading (SPECTS) optical code division multiple access (O-CDMA) testbed. Experimentally measured performance is compared to numerical simulations. The testbed employs a novel compact fiber-pigtailed bulk-optics setup that utilizes a single two-dimensional (2-D) phase modulator for encoding multiple channels, each with a unique 64-chip Walsh code. The time-gated receiver is composed of a nonlinear optical loop mirror (NOLM) and a nonlinear thresholder each utilizing a highly nonlinear fiber (HNLF) as the nonlinear element. The testbed operates error free with up to six users and at a bit error rate BER<10^-9 for eight simultaneous users. Careful modeling of each component in the testbed allows a close match between simulated and experimentally measured testbed performance.