High temperature performance of strained quaternary quantum well lasers

We describe spectroscopic measurements carried out on a variety of InGaAsP window lasers with bulk and quantum well active layer structures in order to better understand their high temperature operation. While all the lasers show the same characteristic T₀:50-55°C, a wide and systematic variation is seen in the maximum operating temperature and the temperature dependence of the slope efficiency. The most stable high temperature operation is obtained in compressively strained multi-quantum-well lasers with wide wells and high barrier layers. We show that significant recombination in the barriers correlates well with poor high temperature performance. We are also able to eliminate hot carrier effects as a significant process, even at elevated temperatures