Room-temperature cw electrically pumped external-cavity surface-emitting laser diodes are reported. The external cavity provides a way to control the transverse modes of the surface-emitting laser diodes. Powers greater than 100 mW pulsed and 2.4 mW cw in the lowest order (TEM00) transverse mode are reported. The surface-emitting laser diode was grown on a p-doped substrate, resulting in uniform current injection in devices as large as 100 μm in diameter. To our knowledge, this is also the first report of a working surface-emitting laser diode grown on a p-type substrate.

High multimode CW powers have been achieved from vertical-cavity surface-emitting laser diodes (VCSEL's). However, due to the problems of thermal lensing and spatial hole burning, single mode powers have been limited to several mW. We show experimentally and with a simple model that, in weakly index guided VCSEL's, self focusing causes the fundamental mode width to decrease with increasing power in the mode, resulting in a rapid transition to multimode operation and limiting the maximum single fundamental mode power