All-Optical Signal Regenerator for Differential Phase-Shift Keying Format Employing a Differential Encoding Circuit With SOA-MZIs

We propose and demonstrate the all-optical differential phase-shift keying (DPSK) signal regenerator with differential encoder employing a newly proposed all-optical T-type flip-flop (T-FF). The proposed configuration of an all-optical T-FF employs a counter-faced configuration of two semiconductor optical amplifier Mach–Zehnder interferometers (SOA-MZIs) to realize a short feedback path without loopback waveguide for high-speed operation. Numerical simulation reveals that it can operate as a T-FF at a bit-rate of 10-Gb/s under the condition of a carrier life time of 10 ps. We also experimentally demonstrate the operation of the proposed all-optical T-FF at a bit-rate of 2 Gb/s with a fiber-based experimental setup. Finally, we demonstrate the possibility of a DPSK signal regenerator with the combination of the proposed all-optical T-FF and the standard SOA-MZI by numerical simulations, which can drastically improve the quality of a DPSK signal degraded in transmission. We believe that the proposed configuration of an all-optical DPSK regenerator is promising for future optical networks.