Vertical cavity lasers with a metallic intracavity laser

Efficiency and maximum power obtainable from vertical cavity lasers (VCL) are low at present due to high series resistance. It is possible to circumvent this and maintain high cavity quality by using a highly conductive, extremely thin metallic layer located in a node (null) of the standing waves just above the active layer. The fabrication was as follows: Bottom mirror and active region were essentially the same as in previous VCLs, and n-doped Al x Ga1- x As/AlAs mirror with an active region about a quarterwave thick. After ~1000 Å of p-doped AlGaAs on top of the active region the epitaxial growth stopped. An ~50-Å Au layer was evaporated on top of this and a conventional dielectric mirror (TiO2/SiO2) completed the structure. Current is injected from thicker Au contacts just to the side of the cavity into the thin layer, then directly into the p-doped layer just above (~1000 Å) the active region. Optically pumped lasing occurred at 240-pj input to such a device. The l–V response of a separate similar device, 10 μm in diameter, showed a nearly constant ~100 ohm resistance. More precise fabrication should yield better performance, both optically and electrically and electrically, in a single device.