Significantly enhanced fiber optic code-division multiple-access system using a novel optical decoder with an AND-gate logic element

We propose a novel optical decoder for a fiber-optic code-division multiple-access communication system. In particular, we discuss a means of reducing the effective multiple-access interference signal by inserting an optical hard limiter (optical thyristor). The optical decoder employs an AND gate logic element (AGLE) composed of a 1×M splitter, optical delay lines, an M×1 combiner, and the optical hard limiter. It is found that the AGLE suppresses the interference signal, so that the autocorrelation sidelobe and the cross-correlation peaks can be fully eliminated for any two users.