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Laser Physics Letters

Slow light propagation and bistable switching in a graphene under an external magnetic field

Seyyed Hossein Asadpour, Hamid Reza Hamedi, HAMID RAHIMPOUR SOLEIMANI

Published Mar 6, 2015• 71 citations
Publisher

Abstract

In this letter, we show the possibility of controlling the optical bistability and group index switching in graphene under the action of strong magnetic and infrared laser fields. By using quantum-mechanical density matrix formalism, we obtain the equations of motion that govern the optical response of graphene in strong magnetic and optical fields. We found that by properly choosing the parameters of the system, the bistable behaviors and group velocity can be controlled. These results may have potential applications in telecommunication and optical information processing.

DOI
10.1088/1612-2011/12/4/045202

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In this letter, we show the possibility of controlling the optical bistability and group index switching in graphene under the action of strong magnetic and infrared laser fields. By using quantum-mechanical density matrix formalism, we obtain the equations of motion that govern the optical response of graphene in strong magnetic and optical fields. We found that by properly choosing the parameters of the system, the bistable behaviors and group velocity can be controlled. These results may have potential applications in telecommunication and optical information processing.
Abstract In this letter, the phase control of optical bistability and multistability in a ring cavity doped with a four-level graphene nanostructure in infrared regions are discussed. Due to the unusual dispersion relation in graphene nanoribbons, electrons can lead to an exceptionally strong optical response in the infrared and terahertz regions. We show that by adjusting the intensities and relative phase of infrared laser fields, the threshold intensity and hysteresis loop can be manipulated efficiently. The effect of the electronic cooperation parameter, which is directly proportional to the electron concentration and the length of the graphene sample, is also discussed. Our proposed model may be useful for the next generation of all-optical systems and information processing in nanoscale devices.
The solution of input-output curves in an optical ring cavity containing Landau-quantized graphene is theoretically investigated taking the advantage of density-matrix method. It is found that under the action of strong magnetic and infrared laser fields, one can efficiently reduce the threshold of the onset of optical bistability (OB) at resonance condition. At non-resonance condition, we observed that graphene metamaterial can support the possibility to obtain optical multistability (OM), which is more practical in all-optical switching or coding elements. We present an analytical approach to elucidate our simulations. Due to very high infrared optical nonlinearity of graphene stemming from very unique and unusual properties of quantized Landau levels near the Dirac point, such controllability on OB and OM may provide new technological possibilities in solid state quantum information science.
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.
Electrons in graphene nanoribbons can lead to exceptionally strong optical responses in the infrared and terahertz regions owing to their unusual dispersion relation. Therefore, on the basis of quantum optics and solid-material scientific principles, we show that optical bistability and multistability can be generated in graphene nanostructure under strong magnetic field. We also show that by adjusting the intensity and detuning of infrared laser field, the threshold intensity and hysteresis loop can be manipulated efficiently. The effects of the electronic cooperation parameter which are directly proportional to the electronic number density and the length of the graphene sample are discussed. Our proposed model may be useful for the nextgeneration all-optical systems and information processing based on nano scale devices.
In this paper, we propose an optical bistable structure based on a single graphene layer sandwiched between two magnetooptical layers which are located between two photonic crystals. It is indicated that such structure shows optical bistability behaviors, in the near infrared range, which can be efficiently controlled with small external magnetic fields lower than 1.5 mT. Such weak external magnetic fields cannot affect the graphene layer and the dependence of bistability phenomenon on the magnetic field results from the presence of magnetooptical layers and their influences on the resonance frequency of the structure. Both switch-up and switch-down thresholds can be significantly adjusted by variation of the external magnetic field. Furthermore, the width of hysteresis loop enhances with increasing the magnetic field. To obtain a high tunability of bistability with external magnetic fields, the thickness of magnetooptical layers should be larger than a special value. It is also found that the increase of the Fermi energy level of graphene leads to the enhancement of both switch-up and switch-down thresholds as well as the width of the hysteresis loop. Finally, it is confirmed that optical bistability can be manipulated by changing the incident illumination angle.
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.