Intracavity contacts for low-threshold oxide-confined vertical-cavity surface-emitting lasers

Very low threshold vertical-cavity surface-emitting lasers are demonstrated using intracavity contacts, an upper dielectric Bragg reflector, and an undoped lower AlAs-GaAs Bragg reflector. The undoped lower mirror allows the demonstration of the highest differential efficiency yet achieved for sub-100-μA threshold, which is 60% for a 67-μA threshold. Devices with smaller output coupling show threshold current densities as low 98 A/cm
²
, and a minimum threshold current of 23 μA for a small aperture.