Showing papers on "Quantum dot published in 1986"
TL;DR: A new type of mechanism for enhanced optical nonlinearities and intrinsic optical bistability that relies on the combination of intrinsic feedback due to local field effects and excitonic resonances in semiconductor crystallites is proposed.
Abstract: We propose a new type of mechanism for enhanced optical nonlinearities and intrinsic optical bistability that relies on the combination of intrinsic feedback due to local field effects and excitonic resonances in semiconductor crystallites. These effects will be further enhanced by quantum confinement in small crystallites.
86 citations
TL;DR: In this article, a variational calculation of the energy levels of an exciton confined to a CdTe quantum well by semimagnetic (Cd,Mn)Te potential barriers is presented.
Abstract: We present a variational calculation of the energy levels of an exciton confined to a CdTe quantum well by semimagnetic (Cd,Mn)Te potential barriers. The degeneracy of the top of the valence band is lifted by strain and quantum confinement effects, introducing a preferential axis of quantization for the heavy \ensuremath{\Vert}${m}_{j}$\ensuremath{\Vert}=(3/2) doublet. This results in strongly anisotropic magnetic field shifts of the levels. The shifts are greatly enhanced due to the penetration of the wave functions into the barriers, where they are subject to the exchange potential of the polarized Mn spins. Our results are in good qualitative agreement with recent photoluminescence data on CdTe-(Cd,Mn)Te superlattices.
28 citations
15 Sep 1986
TL;DR: In this article, the authors have made substantial progress in the understanding of both the linear and the nonlinear optical properties of direct gap semiconductors and in the implications for high speed, low power, non-linear optical signal processing.
Abstract: : During the two-year period of this contract, substantial progress was made in the understanding of both the linear and the nonlinear optical properties of direct gap semiconductors and in the implications for high speed, low power, nonlinear optical signal processing. In particular, the detuning and the temperature dependence of the damping of an exciton-polariton was obtained for the first time. The lowest single beam switching energy ( 4 pJ) and the fastest reported ON/OFF switching ( 1 ns) bistable device with clearly resolved stable states was demonstrated using the nonlinearity associated with bound excitons in CdS. Thermal effects on the millisecond and microsecond time scales were experimentally studied. Optical bistability due to induced absorption near the free and bound exciton was experimentally studied with and without a Fabry-Perot cavity. Large degenerate four-wave mixing signals were observed near free and bound excitons in CdS at cryogenic temperatures. Nonlinear transmission signals were studied at different detunings below the free exciton resonance and at temperatures up to 120 K. These signals were interpreted in terms of a broadening of the free exciton resonance by exciton-exciton collisions. The quantum confined stark shifting of a quantum dot was performed for the first time. A new generation of efficient optical modulators is envisioned. (Author)