We have found the cross‐phase modulation (XPM) for cross‐polarized beams to be equal to the self‐phase modulation (SPM) in bulk AlGaAs semiconductor waveguide at photon energies lower than half the band gap. For multiple quantum well (MQW) waveguide the ratio of the cross‐phase modulation coefficient to the self‐phase modulation coefficient is approximately one for the pump polarized perpendicular to the well plane (TM) and one‐half for pump beams in the plane of the wells (TE). ©1995 American Institute of Physics.