All-Optical Format Conversion from RZ-DPSK to NRZ-DPSK at 40Gbit/s

All-optical format conversion from return-to-zero differential phase shift keying (RZ-DPSK) to non-return-to-zero DPSK (NRZ-DPSK) is demonstrated by using a delay interferometer and a 1-nm-bandwidth filter at 40 Gbit/s. The operation principle is theoretically analyzed and numerically simulated with the help of VPI Transmission Maker 8.5. The simulated results are in agreement well with the experimental results. The conversion can be achieved with power penalty of 0.7 dB.