Tunable all-optical NOR gate at 10 Gb/s based on SOA fiber ring laser

A novel scheme for a tunable all-optical logic NOR gate is presented that is based on a semiconductor fiber ring laser. In this new configuration a semiconductor optical amplifier is employed not only as the operational medium for cross-gain modulation effect to form a logic gate, but also as the active medium for a fiber ring laser that is designed to replace the continuous-wave light required in many other schemes. Alloptical logic NOR operation is successfully demonstrated experimentally by use of 10 Gb/s nonreturn-to-zero (NRZ) signals. An output extinction ratio higher than 10.3 dB can be obtained over the 40 nm tuning range except for a 4 nm gap around the input wavelength.