Electric-field-induced changes in the two-photon absorption spectrum of multiple-quantum-well structures

We have measured two-photon absorption spectra of quantum-well structures in static electric fields for photon energies close to half the band-gap energy, and found drastic static-field-induced changes in the spectra. Our experimental results agree with a theory based on an infinite-level model, the validity of which was previously established at zero bias, except that a field-induced growth of the two-photon absorption peak at half the lowest light-hole excitation energy is more drastic than the theoretical prediction. At high bias fields the peak height approaches a large value predicted by another simplified theory based on a two-level model.