Ultralow threshold VCSEL´s for application to smart pixels

Recent technology developments in which the oxides of AlGaAs are employed as current apertures and in Bragg reflectors have created dramatic improvements in vertical cavity laser performance. The design approach for low threshold VCSEL´s relies on the reduction of optical loss in the device structure to define an optimum operating regime in which both low threshold and high efficiency are achieved. Using this approach we have been able to achieve threshold current densities as low as 140 A/cm2 in VCSEL´s. Based on these results and recent assessments of the efficacy of small oxide apertures to confine current and carrier injection in these structures, we describe a technology path to achieving threshold currents less than 1 /spl mu/A in optimized VCSEL structures. We also describe the use of the native oxide as a component of Bragg mirrors that produce high reflectance, electrically isolated device structures that are suitable for electrical integration with electronic devices. The integrability of these devices arises from the relatively thin epitaxial structures that can be employed with the high contrast Al/sub x/O/sub y//semiconductor DBR components while still achieving the necessary high reflectivity and from the use of intracavity contacted design that is isolated from the substrate by oxide used in the Bragg mirrors.