Data are presented on the 300 K photopumped (pulsed) laser operation of a visible‐spectrum (&lgr;=650 nm) AlAs–AlGaAs/InAlP–InGaP quantum‐well heterostructure (QWH) crystal that utilizes high‐index‐contrast AlAs‐native‐oxide/Al0.6Ga0.4As distributed Bragg reflector mirrors. The mirrors are formed by the lateral oxidation (H2O+N2, 425 °C) of two sets of four ‘‘buried’’ AlAs layers that are separated by Al0.6Ga0.4As. These mirrors, which create a high‐Qcavity in the vertical direction, ‘‘sandwich’’ a one‐wavelength InAlP–InGaP QW active region, thus forming a compact microcavity that ‘‘tunes’’ the carrier scattering and recombination into a narrow spectrum (∼25 A˚) and supports laser operation in the vertical direction. ©1995 American Institute of Physics.