Determination of internal loss in nitride lasers from first principles

Nitride laser diodes are pivotal for optical data storage and laser projection but their performance is limited by large internal absorption losses. Here we quantify the internal loss due to free-carrier absorption using first-principles calculations and show that indirect free-carrier absorption is an important loss mechanism in nitride lasers. The dominant loss process is the phonon-assisted absorption by holes in the p-type layers. Parameters for the absorption coefficients have been extracted for use in device modeling. This work constitutes an important step towards the understanding of the efficiency problems in lasers and may assist the design of future devices.