Generation of dual-wavelength picosecond pulses with close wavelength separation from a self-seeded Fabry-Perot laser diode

We present a simple and low-cost technique for the generation of dual-wavelength picosecond laser pulses with a close wavelength separation. The technique is based on the selection of two close wavelengths from one of the modes of a self-seeded Fabry-Perot laser diode (FP-LD) with a fiber Bragg grating (FBG) that has a slightly split reflection spectrum. With this technique, the intensities of the pulses at the two wavelengths can be equalized by adjusting the temperature of the FP-LD, and the wavelength separation can be changed continuously without changing the repetition rate of the output pulses by tuning the separation of the reflection peaks of the FBG. Generation of stable dual-wavelength pulses with a pulsewidth of 36.0-50.0 ps and a tunable wavelength separation from 0.21 to 0.44 nm at a pulse rate of 2 GHz was demonstrated.