Method of fabricating an expanded beam optical waveguide device

Abstract

A method of fabricating an expanded beam optical waveguide device (e.g., a laser), comprises the steps of (a) forming a first semiconductor waveguide region having first and second sections of different thickness and an intermediate vertical taper section of varying thickness coupling the first and second sections to one another, the first waveguide region being effective to expand the size of the beam as it propagates from the first section to the second section, (b) forming a second semiconductor region (e.g., a laser active region) on the first waveguide region, (c) etching the second region so as to form an essentially vertical first surface of length A-B which extends obliquely across the propagation axis of the device, (d) forming a third semiconductor region (e.g., a cladding region) on the second region and over the first surface, and (e) etching an elongated mesa along the axis, the mesa extending through at least the second region and the first surface so as to form a second waveguide region having an oblique, essentially second vertical surface which has a length a-b<A-B and which is a subsection of the first surface, the second surface forming an asymmetric horizontal taper effective to optically couple the beam between the second waveguide region and the first waveguide region. Also described is a monolithically integrated optical amplifier and electroabsorption modulator with a dual waveguide expanded beam device fabricated by the inventive method.