OPTICAL NONLINEARITIES AND CARRIER RELAXATION IN CDTE CDMNTE MULTIPLE-QUANTUM WELLS/

Nonlinear changes in transmission at the exciton resonance of CdTe/CdM nTe multiple quantum wells were measured at room temperature with a ti me resolution of 300 fs. For one sample, the observed nonlinearity sat urates when the photogenerated carrier density is between 2.5 and 5.0 x 10(12) cm-2. This result is explained by considering the optical non linear effects resulting from band-filling. Time dependent measurement s of the nonlinear transmission show that carrier transfer from the ba rriers to the wells and carrier relaxation in the wells occur in less than 300 fs. The latter value corresponds to an electron relaxation ra te of at least 2.6 x 10(11) eV s-1.