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

Nonlinear changes in transmission at the exciton resonance of CdTe/CdMnTe multiple quantum wells were measured at room temperature with a time resolution of 300 fs. For one sample, the observed nonlinearity saturates 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 nonlinear effects resulting from band-filling. Time dependent measurements of the nonlinear transmission show that carrier transfer from the barriers to the wells and carrier relaxation in the wells occur in less than 300 fs. The latter value corresponds to an electron relaxation rate of at least 2.6 x 10(11) eV s-1.