Effects of lateral heat and carrier diffusion on thermal runaway of cw DH semiconductor lasers

Effects of lateral heat and carrier diffusion on the maximum output intensity, above which thermal runaway takes place, are determined for cw semiconductor lasers. The effects are depicted by an aspect ratio of cavity length to stripe width and a dimensionless quantity representing the efficiency of heat transfer. A concise criterion for no thermal runaway is given. The results show that the output intensity can be increased by an order of magnitude by reducing the stripe width sufficiently but that only about a twofold increase in the output power can be realized. However, a laser with a smaller stripe width can be operated at a higher temperature for the same output power. An optimization with respect to the aspect ratio and the dimensionless quantity should result in a three-to-fourfold increase even in the output power