Asymmetric Twin-Waveguide 1.55- m Wavelength Laser with a Distributed Bragg Reflector

We demonstrate a single frequency, 1.55 m wavelength laser based on an asymmetric twin-waveguide structure using a single growth step and a simple fabrication process. The external Bragg grating is formed on the passive ridge waveguide, optically coupled to the twin-guide gain section using a low loss, tapered mode transformer. The grating is produced by near-field holographic printing using a phase mask. Output powers 11 mW in a small-spot waveguide with a side-mode suppression ratio 40 dB and a slope efficiency of 0.11 W/A are obtained under pulsed operation. These performance characteristics are comparable to conventional, nonintegrated, conventional discrete DBR lasers, although the twin-waveguide design is compatible with photonic integrated circuits such as monolithic transmitters and WDM coherent receivers.