Anomalous spectral behaviour of high power laser diodes

Generally the spectrum of a laser diode shifts to long wavelength with increasing temperature. An anomalous shift to short wavelength has been observed for some high power (~4 W) laser diodes at higher temperatures and current. Experimental results and an analysis are reported which show that this anomalous shift is due to a change in the nature of the laser transition from n=1 levels to that from n=2 levels. Such anomalous shifts are less likely in lasers with thin quantum wells