Study On Giant Magnetic Kerr Effect And Ultraslow Magnetic Solitons Via Plasmon Induced Transparency

In recent years,much attention has been paid to the research on metamaterials,which are artificial electromagnetic media structured on subwavelength scales.With the extensive development of relevant theoretical and experimental work,the metamaterial research now becomes a paradigm for designing a new generation of metadevices that may control the propagation properties of electromagnetic waves with many desired,exotic properties and unprecedented functionalities.It is well known that conventional atoms and molecules are rather restrictive for building an effective magnetic material,which is particularly true at frequencies at or above gigahertz.The major reason for this is that the magnetic component of electromagnetic radiations in this frequency region couples to atoms or molecules much more weakly than the electric component.Thus for a long time it is a challenging issue to acquire a large magnetic response in microwave frequencies and higher.At the end of the last century,British scholar J.B.Pendry et al.suggested that large magnetic response may be achieved by using a metamaterial consisting of an array of artificially fabricated photonic atoms(meta-atoms),e.g.,split ring resonators(SRRs).On the other hand,it is one of dreams for scientists and engineers to obtain novel materials with nonlinearity that can outperform naturally available materials.Pendry et al.suggested that a metamaterial with enhanced nonlinearity could be realized through doping nonlinear elements at some positions of meta-atoms where radiation field is strong.Based on such idea,many authors have presented different schemes to enhance metamaterial nonlinearity through the insertion of nonlinear elements,by the use of nonlinear host materials,etc.However,the results of the linear and nonlinear magnetic response studies reported so far have several serious problems,including large radiation losses and high input power requirements.In addition,it is difficult to obtain a significant,purely nonlinear magnetic response using these schemes.While studying for a master's degree,the author conducted a systematic andin-depth study on the above issues.Its main purpose is to propose a new metamaterial design scheme,using the plasmon induced transparency(PIT)effect to achieve effective suppression of electromagnetic radiation losses,and obtain a pure magnetic response in the metamaterial.Its nonlinear magnetic response is significantly enhanced.The results achieved by the institute are as follows:1.Proposed a scheme to realize nonlinear magnetic metamaterials via plasmon induced transparency.In this work,we propose a scheme to realize strong magnetic responses by using a metamaterial constructed by an array of magnetic meta-atoms consisting of two coupled VLSRRs working under the condition of plasmon-induced transparency(PIT).Through proper coupling of the two notched ring resonators,destructive interference between the motion of the bright oscillator and the dark oscillator can be achieved in the system.This phenomenon is a metamaterial simulation of electromagnetic induction-induced transparency in a three-level atomic system.In order to obtain magnetic nonlinearity,nonlinear elements such as varactor diodes are embedded in the gap of each split ring resonator,so that superatoms have nonlinear characteristics.Our research results show that the PIT transparent window can be well adjusted by parameters such as the distance between the notched ring resonators,and the magnetic nonlinear strength of the system can also be controlled by the parameters of the varactor diode embedded in the superatoms and the superatomic density of the system.2.Enhanced magnetic Kerr nonlinearity can be achieved via PIT.Based on the proposed metamaterial scheme,the nonlinear coupling equations satisfied by the nonlinear superatomic array and the electromagnetic field of the system are solved in detail from the analytical and numerical simulation aspects.The research results show that third-order nonlinear magnetization can be obtained in this metamaterial is greatly enhanced,and it has very low radiation loss.Theoretically clarified that the giant magnetic Kerr effect comes from the resonance characteristics of bright and dark oscillators in the superatom,and the nonlinear effect provided by the varactor diode;The bright oscillator and the dark oscillator destructively interfere,so that the linear and nonlinear radiationloss of the magnetic material is greatly suppressed.Therefore,with this magnetic metamaterial,a low-loss,giant magnetic Kerr nonlinearity that is not normally found in nonlinear magnetic materials can be obtained.3.Ultraslow magnetic solitons via PIT.Based on the obtained nonlinear effect of giant magnetic Kerr,the possibility of stably propagating a nonlinear magnetic pulse in this metamaterial was studied.Using the singular perturbation method,the nonlinear envelope equation satisfied by the nonlinear magnetic pulse is derived.Studies have shown that based on the balance of magnetic Kerr effect and dispersion effect,magnetic solitons can be generated in this metamaterial.These nonlinear magnetic pulses can not only propagate stably in the system,but also have extremely low power generation and very slow propagation speed.The research results of this paper not only broaden the research field of nonlinear metamaterials,but also provide a strong theoretical basis for obtaining significant,low-loss,actively adjustable pure nonlinear magnetic response metamaterials.Obtain important practical applications in processing and transmission.