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Laser Physics

Dynamical and steady-state properties of absorption-dispersion curves in a monolayer graphene system

E Haji Ali, F. Abbasi Davani, F Ziaie

Published Sep 18, 2019• 1 citation
Publisher

Abstract

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.

DOI
10.1088/1555-6611/ab3da9

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In recent years, control of group velocity of light has attracted enormous interest. One of the main challenges is to realize an absorption-free fast or slow light propagation. Here, we study dispersion and absorption properties of a weak probe field in a Landau-quantized graphene and report a gain-assisted superluminal light propagation. Moreover, an attempt is made to develop an analytical expression and necessary parameters for switching the group velocity of the probe field from subluminal to superluminal. It’s worth mentioning that large dephasing rate in graphene offers feasibility of superluminal propagation of ultrashort light pulses. Additionally, dynamical behavior of dispersion and absorption of a weak probe field in a closed-type graphene system is investigated, and it is found that the absorption and dispersion can be dramatically affected by both the relative phase of applied fields and the Rabi frequencies in such a way that a large transient gain can be achieved and a transient absorption can be completely eliminated.
The dispersive-absorptive optical properties of a weak probe field are investigated based on quantum coherence and interference in a Landau-quantized graphene structure. It is found that an enhanced refractive index with vanishing absorption can be obtained in this structure through proper adjusting the controlling parameters of the system. The switching between superluminal and subluminal light propagation is also discussed. Our scheme can be employed in real experiments to develop new types of nanoelectronic devices for realizing all-optical switching process and can have practical application in dispersion compensation and solid-state quantum communication.
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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.
Abstract The optical properties of a weak probe light by applying coupling fields in Landau-quantized graphene nanostructure is investigated. In this structure the electromagnetic field of terahertz-infrared radiations interfere with the electromagnetic field of the short-wavelength probe field and this effect changes the absorption and dispersion characteristics of the probe field. The linear dynamical properties of the graphene by means of perturbation theory and density matrix method are discussed. We show that the group velocity of a light pulse can be switched from superluminal to subluminal or vice versa by controlling the coupling field’s intensities and relative phase of the applied fields. Therefore, this model can be used as an all-optical switch which is suitable for next generation of future all optical quantum communicational system and networks.