Integration of semiconductor laser amplifiers with sampled grating tunable lasers for WDM applications

A semiconductor laser amplifier is integrated with a sample grating distributed Bragg reflector (SGDBR) laser to act as an external modulator. The fabrication, characterization, and device characteristics of this integrated tunable transmitter are reported. The integrated tunable laser can have up to 75 nm of tuning range and more than 30 dB of side-mode suppression ratio (SMSR). The integrated amplifier can provide at most 8 dB of gain and more than 25 dB of contrast ratio for all the channels. Its RF modulation bandwidth can achieve 1.5 GHz, and the dynamic chirp is as good as a directly modulated laser. A simple model is proposed to explain the measured modulation responses and gain saturation is found to be the main cause of the resonant peaks in the dynamics.