We discuss multiband coupling effects on electronic intersubband single particle excitations (SPE) of infrared (IR) and Raman processes in type I quantum wells (QWs). Interband couplings between &Ggr;c1‐&Ggr;v15, &Ggr;c1‐&Ggr;c15, and &Ggr;c15‐&Ggr;v15bulk band edges are treated within 14‐bandk⋅pfirst‐order perturbation theory. Enhanced band‐mixing effects are observed at Brillouin zone center (k∥=0) because of quantization effects (kz≠0). For zinc‐blende‐type QWs, &Ggr;c15‐&Ggr;v15band‐mixing effects at high‐lying &Ggr;c1conduction subbands contribute (x,y)‐polarized IR andz(x,x)z¯‐ andz(x,y)z¯‐polarized Raman intersubband SPE. Intersubband polarization splittings occur when the QWs are under biaxial strains. ©1995 American Institute of Physics.