  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 $Q\approx$ 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 $P_{\rm th}$ = 10 mW
($\lambda_{\rm p}$ = 808 nm). The laser linewidth was found to be $\approx$3
GHz at $P_{\rm p}\approx$ 5 $P_{\rm th}$.
