Monolithically integrated InGaAs-AlGaAs master oscillator power amplifier with grating outcoupler

A monolithically integrated master oscillator power amplifier with a grating outcoupler, fabricated using a simple process without regrowth and emitting a collimated output beam, is proposed and demonstrated using an InGaAs-AlGaAs strained single-quantum-well gradient-index separate-confinement-heterostructure. Stable single-mode lasing up to 124-mW output power was obtained under continuous-wave operation. An increase of the output beam divergence, due to a wavefront distortion produced in the power amplifier, was observed with increasing power amplifier injection current. The wavefront distortion can be compensated by an appropriate design of the grating outcoupler.