NONLINEAR PHOTOLUMINESCENCE IN GAAS ALXGA1-X QUANTUM-WELLS/

have measured the nonlinear photoluminescence (PL) spectra of GaAs/Alx Ga1-xAs quantum wells at low temperatures using a continuous wave tech nique that is based on low-power excitation and phase-locked detection . For nonresonant excitation we find a significant change of the emiss ion energy and linewidth with increasing excitation intensity. We attr ibute the energy shift to the optical modulation of the internal elect ric fields that results in the modulation of the exciton energy via th e quantum confined Stark effect, while the line broadening is due to t he interaction of excitons with free carriers. [S0163-1829(98)07704-2] .