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 (similar to4W) 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.