Thermally induced local gain suppression in vertical-cavity surface-emitting lasers

Joule heating is one of the dominant mechanisms determining the transverse mode formation in vertical-cavity surface-emitting lasers at high injection currents. We give experimental evidence that in this operation regime, str ong heating results in local gain suppression in the center of the laser, w hich overbalances the confining effect of thermal lensing, and thus favors the formation of high order modes. From our investigations df small apertur e devices, we conclude that efficient heat removal is crucial for achieving single mode emission at high injection currents. (C) 2000 American Institu te of Physics. [S0003-6951(00)03123-5].