Based on energyband engineering theory

the influences of tensile strain and quantum-well width on the gain polarization dependence of quantum-well Semiconductor Optical Amplifiers（SOA） are investigated.A 1.55μm gain polarization-insensitive SOA with tensile strained quantum-well as the active region is designed

which has very low polarization sensitivity in a wide range of carrier density and optical wavelengths.Also designed is a 1.31μm gain polarization-insensitive SOA with mixed tensile and compressively strained wells as the active region.