All-Optical Format Conversion from NRZ to CSRZ and between RZ and CSRZ Using SOA-Based Fiber Loop Mirror

A 10-Gb/s all-optical format conversion from nonreturn-to-zero (NRZ) to carrier-suppressed return-to-zero (CSRZ) and conversion between return-to-zero (RZ) and CSRZ are demonstrated, in this letter, using a semiconductor optical amplifier-based fiber loop mirror. The converter utilizes a control light composed of a 5-GHz sinusoidal optical clock signal and a continuous-wave light. The optical power ratio of the control light is optimized to obtain proper phase modulation for high performance format conversion. The power penalty of the proposed format converter is measured for NRZ to CSRZ, RZ to CSRZ, and CSRZ to RZ conversions. In NRZ to CSRZ conversion, the dynamic range of the input NRZ signal power is also investigated.