Low-Threshold Surface-Emitting Whispering-Gallery Mode Microlasers

We report on microlasers based on high-quality micropillars with whispering-gallery modes lasing. The use of low-absorbing Al
_0.2
Ga
_0.8
As/Al
_0.9
Ga
_0.1
As distributed Bragg reflectors and smooth pillar sidewalls enables whispering-gallery modes lasing by excitation and collection of emission in the pillar axis direction. Simultaneous whispering gallery modes lasing (comb-like structure) is observed in the wavelength range of 930–970 nm for 3–7 μm pillar diameters. Increasing the temperature to 130 K leads to single-mode lasing for 5 μm pillars with a cold cavity quality-factor of about 8000 and an estimated threshold excitation power of 240 μW. Lasing in the thermoelectrical cooling range (up to 170 K) has been demonstrated.