A miniature integrated optical beam splitter in AlGaAs/GaAs ridge waveguides.

Typical directional couplers in semiconductor waveguides require long (several millimeter) interaction lengths, potentially limiting their use in future opto-electronic integrated circuits (OEICs). We report on the fabrication and operation of a newly designed integrable waveguide beamsplitter device only microns in size, consisting of a groove at the intersection of two perpendicular AlGaAs/GaAs ridge waveguides which was milled with a micro focused gallium ion beam. Single-mode propagation of both transmitted and reflected beams was observed and the power ratio between both beams was adjustable by varying the groove depth.