Abstract
Optical gain is calculated for a strained quantum well grown on a ternary In1−xGaxAs substrate which is now being developed. Using an In0.26Ga0.74As substrate we can design a strained quantum well for 1.3 μm laser with a large band gap InGaP or InGaAsP barrier layer. This gives a much deeper potential well when compared with that on an InP substrate and results in a high optical gain owing to the large subband energy separation provided by the deep well. The optical gain of the strained quantum well on the ternary substrate is shown to be higher by about 750 cm−1 when compared with that on an InP substrate.