In-well pumped blue GaN-based vertical-external-cavity surface-emitting lasers
We describe the properties of in-well pumped blue InGaN/GaN vertical-external-cavity surface-emitting lasers. The laser hetero-structures were deposited on bulk GaN substrates by using metal-organic vapor phase epitaxy near atmospheric pressure. The active zones are comprised of up to 20 InGaN quantum wells distributed in a resonant periodic gain configuration. High-reflectivity dielectric distributed Bragg-reflectors were used as mirrors. Lasing was achieved at a wavelength of about 440-445 nm by exclusively exciting the quantum wells with the 384 nm emission line of a dye-/N2-laser. The laser threshold was about 240 kW/cm2. The small pump spot diameter of about 20 μm and the usage of dielectric mirrors result in a rather high thermal resistance of about 173 K/W, which was experimentally determined by using an all optical measurement technique based on the temperature-dependent change of the refractive index of the device.
Wunderer, T.; Northrup, J. E.; Yang, Z.; Teepe, M. R.; Johnson, N. M.; Rotella, P.; Wraback, M. In-well pumped blue GaN-based vertical-external-cavity surface-emitting lasers. International Workshop on Nitride Semiconductors; 2012 October 14-19; Sapporo, Japan.