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Journal of Electromagnetic Waves and Applications

Coherent and incoherent manipulation of optical bistability and group velocity in a dielectric slab with a monolayer of quantized graphene

Masoud Jabbari

Published May 29, 2017• 2 citations
Publisher

Abstract

A new model is suggested for controlling the optical bistability (OB) and group velocity of transmitted light via coherent and incoherent control of applied fields. Our proposed structure is studied theoretically based on quantum coherence and interference mechanism in a defect dielectric slab with a monolayer of quantized four-level graphene system. Our results show that the manipulation of OB by adjusting the controllable parameters can be possible at one or more points of the bistable spectrum. Moreover, our investigations on the transmitted and reflected pulses show that the subluminal and superluminal light propagation can be possible in a specific situation of parametric conditions.

DOI
10.1080/09205071.2017.1323016

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A new model is suggested for controlling the optical bistability (OB) and group velocity of transmitted light via coherent and incoherent control of applied fields. Our proposed structure is studied theoretically based on quantum coherence and interference mechanism in a defect dielectric slab with a monolayer of quantized four-level graphene system. Our results show that the manipulation of OB by adjusting the controllable parameters can be possible at one or more points of the bistable spectrum. Moreover, our investigations on the transmitted and reflected pulses show that the subluminal and superluminal light propagation can be possible in a specific situation of parametric conditions.
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Abstract In this article, we discuss the dynamic and steady-state features of the absorption-dispersion of a graphene monolayer system, interacting with an elliptically polarized control and coherent pumping fields. We find that, under a proper condition of parameters selection, the absorption, dispersion and group index of the weakly probe field in a monolayer graphene system can be adjusted. We show that, under optimal conditions, the controlling of the group velocity can be possible to achieve the subluminal and superluminal light propagation. Moreover, we realize that the amplification of the probe light due to the presence and absence of population inversion can be obtained by the proper choice of controllable parameters. Our findings may be useful for high-speed optical communications based on a graphene monolayer system.
Abstract We investigate the behavior of optical bistability (OB) and optical multistability (OM) based on quantum coherence in a Landau-quantized graphene structure. Such a tunable four-level system is driven coherently by two coherent fields and an incoherent pumping field inside the unidirectional ring cavity. The influence of system parameters on the threshold of the onset of OB and OM is studied. It is found that one can efficiently control the OB/OM threshold intensity and the hysteresis loop by using the system parameters. The results obtained may be used in real experiments for the development of new types of nanoelectronic devices for realizing an all-optical switching process.
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Abstract We investigate the coherent manipulation of certain optical properties in graphene under Raman excitation by using a density-matrix approach. It is shown that the absorption and dispersion, the group velocity, and the transmission coefficient of the probe field can be efficiently controlled through proper adjustment of the intensity and frequency detuning of the control field. In addition, the optical bistability (OB) behavior is explored for the proposed system. It is found that the bistable threshold intensity and related hysteresis loop of OB can be controlled by the parameters of the system. The results obtained may be used in real experiments for the development of new types of nanoelectronic devices used for the realization of all-optical switching processes.
Propagation of an electromagnetic pulse through a dielectric slab doped with three-level ladder-type atomic systems is discussed. It is shown that the group velocity of the reflected and transmitted pulses can be switched from subluminal to superluminal light propagation by the thickness of the slab or the intensity of the coupling field. Furthermore, it is found that, in the presence of quantum interference, the reflected and transmitted pulses are completely phase dependent. So, the group velocity of the reflected and transmitted pulses can only be switched from subluminal to superluminal by adjusting the relative phase of the applied fields.