A Self-Started Laser Diode Pulsation Based Synthesizer-Free Optical Return-to-Zero On–Off-Keying Data Generator

A synthesizer-free return-to-zero on-off-keying (RZ-OOK) data generator is demonstrated by gain-switching a Fabry-Perot laser diode (FPLD) and driving a data-stream generator with a self-started opto-electronic oscillator (OEO). By self-feedback triggering the FPLD with the OEO, the FPLD with a modulation bandwidth of only 4 GHz can be self-pulsating to generate clock signal and return-to-zero (RZ) carrier at a repetition frequency of 10 GHz. The self-pulsated FPLD exhibits a pulsewidth of 19 ps associated with a pulse on/off extinction ratio of 7.7 dB and a timing jitter as low as 424 fs. Under self-started pulsation, the spectral linewidth enhancement factor of such a gain-switching FPLD is 12.8, which induces a dynamic frequency chirp ranging from + 6 to - 5 GHz within 30-ps duration. The corresponding chirp parameter of -0.22 is reported for such an OEO driven FPLD based RZ-OOK data generator. The lowest phase noise of -131.8 dBc/Hz at 10-MHz offset from 10-GHz carrier, and the maximum output power of 23 dBm is obtained after amplification. The generated RZ pulsed carrier exhibits a carrier-to-noise ratio of 53 dB and a harmonic suppression ratio up to 52 dB. Such a self-started OEO triggered FPLD is a new approach to the synthesizer-free optical clock and RZ-OOK data generation.