Compact mode expanders using resonant coupling between a tapered active region and an underlying coupling waveguide

摘要

A novel technique for enhanced laser-fiber coupling, based on resonant power coupling between a tapered active waveguide and an underlying coupling waveguide, is presented. Spot-sizes are transformed from 2.0/spl times/1.1 /spl mu/m in the active region to 6.0/spl times/3.1 /spl mu/m in the coupling waveguide, over a length of 200 /spl mu/m, with a mode transformation loss of only 0.36 dB. Butt-coupling efficiencies of 55% (2.6 dB loss) are estimated to standard cleaved single-mode fibers at 1.55 /spl mu/m. The proposed device requires a single epitaxial growth and conventional processing techniques, making it amenable for low-cost manufacturing.