We report a buried heterostructure vertical-cavity surface-emitting laser
fabricated by epitaxial regrowth over an InGaAs quantum well gain medium. The
regrowth technique enables microscale lateral confinement that preserves a high
cavity quality factor (loaded Q≈ 4000) and eliminates parasitic
charging effects found in existing approaches. Under optimal spectral overlap
between gain medium and cavity mode (achieved here at T = 40 K) lasing was
obtained with an incident optical power as low as Pth = 10 mW
(λp = 808 nm). The laser linewidth was found to be ≈3
GHz at Pp≈ 5 Pth