Thermal lensing effects in small oxide confined vertical-cavity surface-emitting lasers

The thickness and position of an oxide layer inside a vertical-cavity surfa ce-emitting laser structure have been optimized for minimum optical scatter ing loss. In the resulting structure, the index guiding provided by the oxi de aperture is very small. Consequently, for an oxide aperture radius < 2 m u m, the optical mode is only weakly confined. In devices using such small apertures, the formation of a thermal lens has a strong influence on optica l guiding. The thermal lens leads to lower threshold currents and increased differential efficiency with continuous wave as compared to pulsed injecti on operation in devices with small apertures. (C) 2000 American Institute o f Physics. [S0003-6951(00)01101-3].