Buried Tunnel Junction VCSEL with High Contrast Grating Top Reflector

Abstract

Emerging applications of optical sensing in consumer products, such as facial recognition based on structured light and time of flight proximity sensing, create high volume demand for low-cost illumination sources in the infrared wavelength range. Vertical Cavity Surface Emitting Lasers (VCSELs), manufactured into arrays of tens to thousands of elements, show superior beam quality compared to LEDs and edge emitter lasers and sufficient power for most applications. In this paper we present a high contrast grating enabled VCSEL with a buried tunnel junction emitting in the 980 nm wavelength range. The presented architecture with lithographically defined current aperture promises potential for highly uniform and dense VCSEL arrays. In our work we describe an epitaxial regrowth process for VCSELs incorporating a GaAs tunnel junction. Prototype single emitter devices with aperture sizes from $6-12 \mu \mathrm{m}$ where fabricated. Devices with $6-8 \mu \mathrm{m}$ apertures achieved submilliamp thresholds, while devices with $12 \mu \mathrm{m}$ apertures demonstrated 1.4 mW peak power and a thermal resistance of 1.21 K/mW.