Many proposals have been suggested for achieving giant Kerr nonlinearity in different medium [1,2]. In this study we propose a new model for achieving giant Kerr nonlinearity in a single layer of graphene nanostructure. The properties of electron near the Dirac points make it possible for interacting by electromagnetical fields [3]. The nonlinear optical features of graphene nanostructure in the presence of strong magnetic field have been discussed very recently in four-wave mixing [4]. To the best of our knowledge, the giant Kerr nonlinearity of graphene with zero linear and nonlinear absorption has not been reported theoretically or experimentally. The enhanced Kerr nonlinearity with zero linear absorption is very interested in nonlinear optics and quantum information science.
Many proposals have been suggested for achieving giant Kerr nonlinearity in different medium [1,2]. In this study we propose a new model for achieving giant Kerr nonlinearity in a single layer of graphene nanostructure. The properties of electron near the Dirac points make it possible for interacting by electromagnetical fields [3]. The nonlinear optical features of graphene nanostructure in the presence of strong magnetic field have been discussed very recently in four-wave mixing [4]. To the best of our knowledge, the giant Kerr nonlinearity of graphene with zero linear and nonlinear absorption has not been reported theoretically or experimentally. The enhanced Kerr nonlinearity with zero linear absorption is very interested in nonlinear optics and quantum information science.
In this paper, a new model is proposed for manipulating the Kerr nonlinearity of right-hand circular probe light in a monolayer of graphene nanostructure. By using the density matrix equations and quantum optical approach, the third-order susceptibility of probe light is explored numerically. It is realized that the enhanced Kerr nonlinearity with zero linear absorption can be provided by selecting the appropriate quantities of controllable parameters, such as Rabi frequency and elliptical parameter of elliptical polarized coupling field. Our results may be useful applications in future all-optical system devices in nanostructures.
Abstract We propose monolayer graphene system and analyze the effects of giant Kerr nonlinearity and Doppler broadening. The focus is to construct and design experimentally viable model by which we can enhance the group index of the medium so that we have slow group velocity. For obtaining the desired goal, we consider Landau level of graphene monolayer placed perpendicular to magnetic field M Tokman et al (2013, Phys. Rev. lett. 110, 077404). Giant Kerr nonlinearity and Doppler broadening enhance the medium group index greatly, resulting in a slow group velocity that has uses in storage devices, optical buffering, quantum memory, and data processing. We also investigate the behavior exhibited by the weak probe’s transmission spectrum, which can change when the terahertz signal frequency is turned on and off. Advantages of under consideration model are its a 2D material whereas other materials are semiconductor or gaseous state. Also, Landau level of graphene has domains tuneable in tera hertz and infra-red region while we cannot tune the semiconductor and atomic media once the transition is chosen. Therefore, the proposed magnetized graphene system offers a tremendous opportunity for incorporating quantum interference into the development of optical solid-state devices.
Hybrid nanocomposites can provide a promising platform for integrated optics. Optical nonlinearity can significantly widen the range of applications of such structures. In the present paper, a theoretical investigation is carried out by solving the density matrix equations derived for a metal nanoparticles-graphene nanodisks-quantum dots hybrid system interacting with weak probe and strong control fields, in the steady state. We derive analytical expressions for linear and third-order nonlinear susceptibilities of the probe field. A giant self-Kerr nonlinear index of refraction is obtained in the optical region with relatively low light intensity. The optical absorption spectrum of the system demonstrates electromagnetically induced transparency and amplification without population inversion in the linear optical response arising from the negative real part of the polarizabilities for the plasmonic components at the energy of the localized surface plasmon resonance of the graphene nanodisks induced by the probe field. We find that the self-Kerr nonlinear optical properties of the system can be controlled by the geometrical features of the system, the size of metal nanoparticles and the strength of the control field. The controllable self-Kerr nonlinearities of hybrid nanocomposites can be employed in many interesting applications of modern integrated optics devices allowing for high nonlinearity with relatively low light intensity.
This article presents an exclusive study of the linear and higher-order susceptibilities, as well as the reduction in group index of a weak probe pulse in a three-level Landau-quantized graphene (LQG) system, under the influence of a strong control field, utilizing the phenomenon of electromagnetically induced transparency. The influence of the magnetic field on the higher-order nonlinearities (Kerr, quintic, and septic) leads to observable changes in amplitudes and shifts in probe frequencies. The LQG system exhibits giant values for these nonlinear susceptibilities with χ(3), χ(5), χ(7) reaching magnitudes approximately ∼10−18m3/V2, ∼10−30m5/V4, and ∼10−42m7/V6, respectively, in the mid-infrared range. The magnetic field also induces asymmetric absorption peaks and modifies dispersion profiles. The study also demonstrates a reduction in the group velocity of the probe, under the effect of the magnetic field, by 1000-fold compared to the speed of light in free space. These giant higher-order nonlinearities, coupled with significantly reduced group velocity, suggest that the LQG system is a quick responder, revealing it as an excellent candidate for terahertz modulation. This also highlights the potential of the system as a promising material for generating and detecting coherent nonlinear signals in the mid-infrared range.
A scheme for giant enhancement of the Kerr nonlinearity in linear triple quantum dot molecules is proposed. In such a system, the tunneling-induced transparency window obtained in double quantum dot molecules splits into two windows, due to the coupling with the third quantum dot. And most important, the Kerr nonlinearity can be enhanced by several orders of magnitude, compared with that generated in double quantum dot molecules. With proper detuning of the tunneling, giant Kerr nonlinearity accompanied by vanishing absorption can be realized, which opens the possibility to enhance self-phase modulation in tunneling controllable semiconductor nanostructures under conditions of low light levels. Quantitative analysis shows that the giant Kerr nonlinearity is attributed to the interacting double dark resonances induced by the tunneling between the triple quantum dots, therefore no extra laser fields are required.
A theoretical investigation is carried out into the effect of applied coherent fields on electromagnetically induced transparency(EIT) and Kerr nonlinearity in the four-level Y-type energy atom system.It is found that the Absorption curve of the atom system changes from one EIT window to a gain interval which has two transparency points when the intensity of coupling field and pumping field changes from equality to inequality.The position of transparency points,the magnitude of gain value together with the width of gain interval are all closely connected with the changed Rabi frequency of applied fields.It is also found that Kerr nonlinearity is enhanced but accompanied by linear Absorption when applied fields are all weak and their relative intensity reduces.When the intensity of applied fields is enlarged,Kerr nonlinearity is enhanced significantly and its peak moves to the position of transparency point with the enlargement of their relative intensity.That is to say,giant Kerr nonlinearity accompanied by vanishing linear Absorption is obtained.Finally,we find that the effect of the intensity variation of the pumping field on the enhancement of Kerr nonlinearity is more remarkable than that of the coupling field.