High-Power Monolithically Integrated Diode-Laser, Preamplifier, And Coherent Beam Expander

An integrated coherent beam expander utilizing a transverse leaky mode waveguide has been integrated with a single mode distributed Bragg reflector laser and a preamplifier producing powers in excess of 70 mW cw in a single spectral and spatial mode across an aperture over 100 mum wide. The far-field pattern in the direction parallel to the plane of the p-n junction, consists of one main lobe 0.45-degrees wide, indicating that the beam is coherent over the full emitting aperture. The expanded beam is suitable as an injection source for an integrated broad area amplifier.