Wavelength tuning in self-seeded gain-switched Fabry-Perot laser diode with Moire grating

The authors propose a simple method for generating wavelength-tunable singlemode picosecond pulses at a fixed repetition rate. This method is based on self-seeding a Fabry-Perot (FP) laser diode having a fibre external cavity formed by a Moire grating with a proper channel spacing. Stepwise wavelength tuning over a large range can be achieved by changing the FP cavity roundtrip phase shift, and fast electrical tuning is possible by incorporating a phase-control section into the FP cavity. By using a two-channel Moire grating and a temperature-controlled FP laser diode, tuning of picosecond pulses at a repetition rate of approximately 2 GHz between two wavelengths approximately 11 nm apart is demonstrated. A sidemode suppression ratio of >25 dB has been achieved.