Generation of Tunable Carrier-Suppressed Optical Pulses From a Mode-Locked DBR Laser Diode Operating With Two Carrier-Wavelengths

We proposed a method to generate pulsewidth-tunable carrier-suppressed (CS) optical pulsetrain from a mode-locked distributed Bragg reflector (DBR) laser diode (LD) operating with two carrier wavelengths. Our new method made it possible to generate the CS pulsetrains with widely tunable duty ratios of both more and less than 0.5 from a single chip of semiconductor device. With theoretical explanation and suggestion on the operation principle, we experimentally demonstrated the tunable CS pulse generation using a monolithic 40-GHz actively mode-locked DBR LD integrated with an electroabsorption modulator. Wide tunability in the pulsewidth from 3 to 16 ps was successfully achieved retaining almost chirp-free conditions. We also succeeded in the asymmetric pulse generation with different rise and fall times by fine tuning of the operating conditions.