Low-Threshold Surface-Emitting Whispering-Gallery Mode Microlasers

Abstract: We report on microlasers based on high-quality micropillars with lasing on whispering-gallery modes. Usage of low-absorbing Al$\scriptsize 0.2$Ga$\scriptsize 0.8$As\Al$\scriptsize 0.9$Ga$\scriptsize 0.1$As distributed Bragg reflectors as well as the smooth pillar sidewalls allows us to realize whispering-gallery modes lasing by excitation and collection of emission in the pillar axis direction. As a result, simultaneous whispering gallery modes lasing (comb-like structure) in the wavelength range of 930-970 nm is observed for 3-7 $\mu$m pillar diameters. Increase the temperature up to 130 K results single-mode lasing for 5 $\mu$m pillars with about 8000 cold cavity quality-factor and 240 $\mu$W estimated threshold excitation power.