Selectable dual-wavelength pulses generated from a laser diode using external feedback from a two-chromatic fiber grating

A simple, robust, and easily integrable external cavity is demonstrated for the generation of self-seeded dual-wavelength pulses at about 1550 nm. The key component for wavelength selection is a two-chromatic fiber grating. Dual-wavelength pulses with equal intensities at the wavelengths and side-mode-suppression ratio of about 18 dB are obtained. By controlling the bias current and the polarization state, the laser can also be switched into single wavelength oscillation. Discrete tuning of the dual-wavelength pulses has also been demonstrated over a total range of 12.1 nm while maintaining a constant spacing of 6.3 nm.