A novel all-optical modulation-format conversion from nonreturn-to-zero on–off keying (NRZ-OOK) to return-to-zero binary phase-shift keying (RZ-BPSK) is proposed. A Mach–Zehnder interferometric (MZI) wavelength converter consisting of integrated semiconductor optical amplifiers (SOAs) is utilized to implement the proposed format conversion. Error-free operation at a bit rate of 10.7 Gb/s is experimentally demonstrated in order to show the feasibility of the proposed scheme. The received sensitivity of the converted signal is improved by 2.9 dB compared with a back-to-back NRZ-OOK signal at BER = 10<sup>-9</sup>. In addition, a reasonable dispersion tolerance of the converted signal up to ±500 ps/nm is observed. The numerical simulation based upon the carrier-rate equation verifies the experimental results.
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