Green vertical-cavity surface-emitting lasers (VCSELs) were fabricated with two different kinds of gain medium, a green-emitting InGaN quantum dot (QD) active region and a normally blue-emitting quantum well (QW) active region. The VCSELs have dual dielectric DBRs and room temperature (RT) continuous wave (CW) lasing was observed in both type VCSELs. For the QD VCSELs, lasing at different wavelengths from 491.8 to 565.7 nm was obtained, covering most of the “green gap”. The lasing wavelength could be controlled by adjusting the cavity length, and the devices were featured with low threshold current of less than 1 kA/cm<sup>2</sup>. For the QW VCSELs, the emission peak of active layer is around 445nm, dominantly in the blue. However, lasing was observed at around 493 nm, locating at the emission edge and approaching to the green region. The green emission comes from the fluctuation-induced localization centers. And the cavity-enhanced recombination played an important role in realization of lasing action. These results open up opportunities to design and fabricate semiconductor green VCSELs that are useful for wide-gamut, low consumption power and compact displays and projectors.
In recent decades, literatures about visible vertical cavity surface emitting lasers (VCSELs) have been reported. However, due to high optical loss in the cavity, lasing from deep ultraviolet (DUV) VCSEL was still rarely achieved. The optical loss in nitride DUV microcavity was analyzed in detail. DUV nitride vertical Fabry–Pérot microcavity with active layer of AlGaN-based quantum dots and double-side HfO2 / SiO2 distributed bragger reflectors was fabricated. Optical losses with of the order of 103 cm − 1 were deduced from the Q value of the cavity modes. The main origination of optical loss in DUV cavity was calculated and ascribed to the interface scattering. The interface roughness appearing after laser lift-off process and overlap between rough interface and standing optical wave were two key parameters that contributed to interface scattering loss. We believe that our results will provide useful information for improving DUV VCSEL devices.