Length dependence of polarization in spontaneous edge emissions from InGaN/AlGaN MQWs laser diodes

Abstract

The polarization of spontaneous edge-emitting electroluminescence from near-UV LDs with different cavity lengths (from 400 µm to 1000 µm) was studied. It was found that TE mode dominates in InGaN/AlGaN MQWs LDs, which is consistent with the theoretical calculation results of similar MQWs. An obvious polarization decrease from P = 0.57 to 0.42 as the LD cavity length changed from 400 µm to 1000 µm was also observed, corresponding to a ratio r changing from 3.67 to 2.43, which indicated that, the TE mode attenuated more grievously than the TM mode with increasing cavity length. This is due to the inherent property of polarization selective emission from the alloys. The optical loss coefficient of TE mode was determined to be 35 cm -1 , while, 10 cm -1 for TM mode, which is in good agreement with the results obtained from other methods.