Large CW power, very-low-threshold, single transverse mode operation of vertical cavity mushroom structure surface emitting lasers

Continuous-wave GaAs mushroom structure surface emitting laser (MSEL) operation at a threshold current as low as 1.6 mA, an output power >2.0 mW, and a single transverse mode up to three times threshold current is reported. The relatively large CW output power was achieved by reducing the series resistance using a selective zinc diffusion. The low threshold current and single-mode operation are attributed to good lateral current confinement in a small constricted region formed by mesa undercutting. The complete device was mounted junction-side up on a chip carrier and tested CW at room temperature. Some results are given.