Continuous wave operation of current injected GaN vertical cavity surface emitting lasers at room temperature

Abstract

We report the demonstration of the continuous wave laser action on GaN-based vertical cavity surface emitting lasers at room temperature. The laser structure consists of a ten-pair ${\text{Ta}}_2{\text{O}}_5/{\text{SiO}}_2$ distributed Bragg reflector (DBR), a $7\lambda$ -thick optical cavity, ten-pairs InGaN/GaN multiquantum wells with an AlGaN electron blocking layer, and a 29-pair AlN/GaN DBR. The laser has a threshold current of about 9.7 mA corresponding to the current density of about $12.4\text{kA}/{\text{cm}}^2$ and a turn-on voltage about 4.3 V at 300 K. The lasing wavelength was 412 nm with a linewidth of about 0.5 nm. A spontaneous emission coupling efficiency factor of about $5\times {10}^{-3}$ and the degree of polarization of about 55% were measured, respectively. The laser beam has a narrow divergence angle of about 8°.