Electrically-injected VCSELs incorporating monolithic high-index contrast grating mirrors (Conference Presentation)

Abstract

Monolithically grown, electrically-injected VCSELs of a generic design - a short cavity, sandwiched between two distributed Bragg reflectors (DBRs) - can only be realized easily in a gallium arsenide (GaAs) material system which restricts the emission wavelength to ~600 - 1100 nm range. The smartphones market and emerging applications such as LIDAR (light detection and ranging), free space communication and face recognition create a demand for VCSELs emitting outside of this range. We demonstrate electrically-injected VCSELs incorporating a monolithic high contrast grating (MHCG) - a special case of a subwavelength high contrast grating mirror (HCG). MHCG can be made of most of the common materials used in optoelectronics and provides reflectivity close to 100% at a wavelength of interest in range from ultraviolet to infrared. In contrast to the HCG, the MHCG doesn't have to be surrounded by a low refractive index material and hence, can be monolithically integrated with the rest of the VCSEL cavity. In our design the greater part of the top DBR is substituted by an MHCG mirror which reduces the amount of required material and growth time by about 20%. We show continuous wave emission around 980 nm up to 75 °C ambient temperature. Our devices are quasi-single- and double-mode from threshold to rollover for 13.5 μm and 16.5 μm oxide aperture diameters respectively. Our MHCG VCSEL concept can be produced using material systems where lattice-matched and high reflectivity DBRs are not available to create devices emitting at wavelengths from ultraviolet to infrared.