No abstract

Changes in the absorption and refractive index caused by laser absorption in CdS and GaSe are investigated and used to produce absorptive resonatorless bistability in CdS and to explain dispersive optical bistability in a GaSe Fabry-Perot cavity.Durch Laserabsorption hervorgerufene hderungen von Absorptions-und Brechungsindex wurden in CdS und GaSe untersucht. Mit ihrer Hilfe wird resonatorlose Bistabilitiit in CdS erreicht und dispersive optische Bistabilitiit in einem Fabry-Perot-Resonator in GaSe erklart.

The increase of transmission at discrete frequencies (bleaching bands) is observed in porous silicon platelets pumped by picosecond laser pulses. It is attributed lo a saturation of optical transitions between the energy levels of electrons and holes spatially confined within quasi-zero-dimensional (quantum dots) and quasi-one-dimensional (quantum wires) nanostructures. The results of independent measurements using transmission and reflection electron and scanning tunneling microscopy have confirmed the existence of quantum dots and wires of corresponding size. A considerable slowing of energy relaxation from upper to lower levels of size quantization compared with intraband relaxation in the bulk has been observed in the cooled (80 K) platelets of porous silicon.

Fast and slow types of nonlinear absorption and resonatorless optical bistability of electronic? and thermal origin is observed.Schnelle und langsame Arten der nichtlinearen Absorption und resonatorlosen optiechen Bistabilitiit mit elektronischem und thermischem Ursprung werden beobachtet.

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