Exciton–LO phonon interaction of the Fröhlich type is studied in the CdS/CdSe/CdS asymmetric double quantum well under an applied laser field. The intensity of laser effect on the exciton binding energy, oscillator strength, optical transition energies, and third-order harmonic generation are investigated by changing the right well sizes and barrier sizes. The laser-associated confined energies and their corresponding binding energies are brought out with the variation of well sizes. The position-dependent potential is altered by the laser-associated parameter. The laser-field-dependent third-order optical susceptibilities due to interband transitions in the asymmetric well are investigated. The effective Coulomb potential, using the Aldrich and Bajaj polaronic effect, is included in the Hamiltonian. The results show that the laser field considerably affects the confining potential of the quantum well and causes a drastic deformation of the confining potential profile. The obtained optical nonlinearities suffer a redshift in the asymmetric quantum well; also, their peak values are determined by the dipole matrix elements.