All-Optical Generation of Optical BPSK/QPSK Signals Interleaved With Reference Light

In this letter, all-optical generation of multilevel modulated signals interleaved with reference light is proposed and experimentally demonstrated. Four Gbaud BPSK and QPSK signals interleaved with reference light are generated using a LiNbO3 based 2 x 2 optical switch, and the generated signals are demodulated by self-homodyne detection using an optical delay interferometer and a single photodetector. Moreover, we obtained negligible difference of error vector magnitude values between an external cavity laser with 100-kHz linewidth and a distributed-feedback laser with 6-MHz linewidth.