Picosecond all-optical modulation in CdTe/CdZnTe multi-quantum wells under an applied electric field

We present single shot transmission experiments with 20 ps laser pulses. When a 10/sup 5/ V/cm static electric field is applied on a CdTe/Cd/sub 0.62/Zn/sub 0.38/Te multiple quantum well, the optical transmission increases. At a 804 nm wavelength the enhancement factor is equal to 1.6. For a pulse intensity higher than 0.7 fJ /spl mu/m/sup -2/, screening of the applied electric field occurs, restoring a zero-field transmission. These experiments imply that the screening rise time is shorter than 10 ps which results from weak confinement of the holes within the quantum wells.