Gain analysis for surface emission by optical pumping of wurtzite GaN

Abstract

We analyzed optically pumped surface emissions by calculating the optical gain in bulk GaN. We found that GaN has a large gain of over 104 cm−1 and no gain saturation up to 25 000 cm−1 . This high optical gain is generated by the high joint-density of states due to the three valence bands close to band edge and the large effective mass of the conduction band. As a result, although the gain required for lasing in the vertical direction is very high, the high excitation of carriers can achieve this without an intentional high reflection structure.