MOTT TRANSITION FOR PICOSECOND ALL-OPTICAL NOR GATE IN CDSE

Using picosecond time resolved spectroscopy, we study the extinction kinetics of the optical transmission of CdSe platelets induced by strong optical pumping. We investigate the all-optical gate capabilities (resulting from the bandgap shrinkage due to the Mott transition) for laser beams the wavelength of which ranges from 676 to 678 nm. The electron-hole plasma density necessary to enable the optical switching is determined ( rho approx. 2 multiplied by 10**1**7 cm** minus **3 at 20 K). The switch-off time (i. e. the transparency recovery time) is also studied at different wavelengths by picosecond spectroscopy.