Observation of enhanced spontaneous emission coupling factor in nitride-based vertical-cavity surface-emitting laser

We demonstrate an enhancement of spontaneous emission coupling factor $\beta$ in a nitride-based vertical-microcavity surface-emitting laser. The 2.5λ vertical microcavity, the quality factor of which reaches 740, is sandwiched between a nitride and an oxide distributed Bragg reflector. From input–output measurements and analyses of the rate equations, the $\beta$ of the lasing mode at a wavelength of 396.1 nm is estimated to be ${\text{1.6×10}}^{\text{−2}}.$ The estimated $\beta$ can be well accounted for by a simple theoretical model.