The structural design with the largest net galn is presenteti for commonly-used InGaAsP separate-confinement-heterostruc (SCH) strained quantum-well lasers.The best wavelength and width of SCH layer are 1.24 μm and 1 00 nm for 1.55 μm unstrained single quantum-sell lasers.When compressive strain is introduced into the active layer,the best wavelength of SCH layer will be shorter because of the strain-induced reduction of state density and the enhancement of differential gain in quantum-well lasers.