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انجمن اپتیک و فوتونیک ایران

Tunable control phase for superluminal to subluminal light propagation in a ladder three-level quantum dot molecule

Mozhgan Momeni Demne, Mostafa Sahrai

Published Mar 15, 2015• 0 citations
OpenAlex

Abstract

In this paper, the effect of relative phase of applied fields on probe field dispersion and absorption for a laddershaped three level quantum dot molecule is investigated. The results show that the relative phase of applied fields can be affected on the probe beam propagation, and thus its absorption, dispersion and group velocity. The dispersion and the absorption may change with the relative phase of applied fields. By adjusting relative phase of applied fields light propagation from superluminal to subluminal and absorption to gain can be switched.

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Journal of the Optical Society of America B•May 14, 2015•5 citations

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TUNNELING EFFECT IN DOUBLE QUANTUM DOTS NANOSTRUCTURE

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In this working, we introduce a Q-DD composed of two QDs. We find that the absorption and dispersion spectra of the light pulse can be changed via the effect of and inter-dot tunnel couplings and probe pumping field of QDs. Then, we employ the steady state and dynamical state in the four-level double QDs system. The slope of dispersion switches from positive to negative. Therefore, both superluminal and Subluminal light propagations can be achieved by simply applying a gate voltage to the double inter dot tunnel coupling. It is also demonstrated that by applying the indirect pump probe field to the probe transition the absorption-free superluminal light propagation is obtained. The results show that by proper tuning of the bias voltage. This structure also indicates that a wide range of linearity from negative to positive can be simply adjusted via a bias voltage, which would result in wide control of signal beam.

Advanced Physical Research•Jun 4, 2024•0 citations
In this paper, the effect of relative phase of applied fields on probe field dispersion and absorption for a laddershaped three level quantum dot molecule is investigated. The results show that the relative phase of applied fields can be affected on the probe beam propagation, and thus its absorption, dispersion and group velocity. The dispersion and the absorption may change with the relative phase of applied fields. By adjusting relative phase of applied fields light propagation from superluminal to subluminal and absorption to gain can be switched.
The dynamical behaviour of the dispersion and the absorption in a nearly equispaced ladder-type three-level atomic system is investigated. It is shown that in the presence of decay-induced interference the probe dispersion and absorption are phase dependent. The required switching times for switching the group velocity of a probe field from subluminal to superluminal pulse propagation is then discussed. We find that applying an incoherent pumping field provides an additional control parameter for switching the probe absorption to probe gain.
Abstract Based on a GaAs/AlGaAs quadruple-coupled quantum dot heterostructure, an optical switch for controlling superluminal and subluminal light propagation is suggested. The transient and steady state behaviour of the absorption and dispersion of a probe pulse laser field through a quadruple quantum dot molecule are studied. We show that the group velocity of a light pulse can be controlled from superluminal to subluminal, or vice versa, by controlling the tunnelling rates between the quantum dots. The required switching time is calculated and we find it to be about 8 ps. We also investigated a method for the all-optical switching of probe field absorption from a large amount to nearly zero just by applying an incoherent pumping field. We estimated the required switching time for this case to be between 3 and 14 ps.
A switch is proposed for controlling the subluminal and superluminal light propagation through the triple coupled quantum dots system. The steady-state and transient behavior of the absorption and the dispersion of a probe pulse through a triple quantum dots molecule are investigated. We demonstrate that the group velocity of a light pulse can be controlled from subluminal to superluminal or vice versa by controlling the rates of incoherent pumping and tunneling between electronic levels. Switching time is calculated by discussing the dependency of optical transient properties on the incoherent pumping and inter-dot tunneling rates. We introduce three controlling parameters that make it possible to control the wave propagation electrically or even optically in such coupled quantum dot systems.
We theoretically analyze the transient properties of a probe field absorption and dispersion in a coupled semiconductor double-quantum-dot nanostructure. We show that in the presence of the Gaussian laser beams, absorption and dispersion of the probe field can be dramatically influenced by the relative phase between applied fields and intensity of the Gaussian laser beams. Transient and steady-state behaviors of the probe field absorption and dispersion are discussed to estimate the required switching time. The estimated range is between 5–8 ps for subluminal to superluminal light propagation .
In this working, we introduce a Q-DD composed of two QDs. We find that the absorption and dispersion spectra of the light pulse can be changed via the effect of and inter-dot tunnel couplings and probe pumping field of QDs. Then, we employ the steady state and dynamical state in the four-level double QDs system. The slope of dispersion switches from positive to negative. Therefore, both superluminal and Subluminal light propagations can be achieved by simply applying a gate voltage to the double inter dot tunnel coupling. It is also demonstrated that by applying the indirect pump probe field to the probe transition the absorption-free superluminal light propagation is obtained. The results show that by proper tuning of the bias voltage. This structure also indicates that a wide range of linearity from negative to positive can be simply adjusted via a bias voltage, which would result in wide control of signal beam.