Low-Threshold Surface-Emitting Whispering-Gallery Mode Microlasers

TL;DR

This paper demonstrates high-quality micropillar microlasers with whispering-gallery modes lasing in the 930-970 nm range, achieving single-mode lasing at 130 K with high Q-factors and low threshold power.

Contribution

It introduces a new design of micropillar microlasers utilizing low-absorbing Bragg reflectors and smooth sidewalls to enable whispering-gallery mode lasing with high quality factors.

Findings

Simultaneous whispering-gallery modes lasing observed in 3-7 μm pillars.

Single-mode lasing achieved at 130 K with Q-factor of about 8000.

Threshold excitation power estimated at 240 μW.

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.