Spatial absorptive and phase shift filter layer to reduce modal reflectivity for higher order modes in a vertical cavity surface emitting laser

摘要

A first, thicker, annular gallium arsenide semiconductor layer surrounds a second, thinner, circular gallium arsenide semiconductor layer in a vertical cavity surface emitting laser. The thinner circular gallium arsenide layer defines the output window for the laser cavity which matches the TEM.sub.00 fundamental mode of the light beam emitted by the active region of the VCSEL. The thicker annular gallium arsenide layer outside the output window of the thinner circular gallium arsenide layer provides modal reflectivity discrimination against high order transverse modes of the light beam emitted by the active region of the VCSEL.