Magneto-optical Enhancement Of Monolayer Transition Metal Dichalcogenides Composite Structure

Magneto-optical effects describe the interaction between optic and magnetic materials,which plays a fundamental role in the technological applications,such as optical isolators,circulators,magneto-optical memories and magneto-optical modulators.Currently,magnetic materials in magneto-optical devices are mainly magneto-optical glass,doped yttrium iron garnet and magnetic liquid.In general,the conventional magnetic materials have weak magneto-optical effect,are hard to be miniaturized and difficult to be adjusted,which are disadvantage for new magneto-optical devices with high performance and miniaturization.Recently,transition metal sulfides(TMDCs)have attracted great attention due to their unique electrical and optical properties.In particular,monolayer TMDCs exhibit valley splitting and valley Zeeman behaviors upon the application of magnetic field,which provides new ultra-thin candidates for the design of new magneto-optical devices.In this paper,by using the low energy effective Hamiltonian and transfer matrix method,the magneto-optical effects of various monolayer TMDCs based configurations are studied.The main works of this article are listed as follows:First,we propose a heterostructure consisting of monolayer TMDCs and two one-dimensional photonic crystals.It is found that the structure achieves simultaneous enhancement of the Faraday rotation(FR)angle and transmittance by optimizing the component's thicknesses,,where the FR angle and transmittance are 2.1° and 0.91,respectively.The enhancement of the magnetooptical performance origins from the achievement of impedance matching conditions and strong electromagnetic field localization where monolayer TMDC stays.In addition,the chemical potential and the value of the magnetic exchange field can be applied to manipulate the magneto-optical effect of the hybrid structure.Our work here promotes the development of monolayer TMDCs-based magneto-optical devices and this strategy can be extended to other two-dimensional materials.Secondly,we study the feasibility of improving the magneto-optical effect in the dual-cavity photonic crystal structure consisting of two monolayer TMDCs.It is shown that the FR angle can reach 12.7° and its transmittance can still be as high as 0.72 for the appropriate period number of photonic crystal and the thicknesses of dielectric materials.In addition,we also find that the repetition number of the dual-cavity photonic crystal configuration can be used to control the appearance of single or double peaks in the spectrum of the FR angle,which is of great significance for the realization of multi-band filters and optical communications.Finally,we discuss the magneto-optical effects of three composite structures consisting of monolayer TMDCs and dielectric materials.It is found that the three structures can enhance the magneto-optical effect and maintain a large transmittance.In addition,the bandwidth of the improved FR angle is relatively wide.Under the same magneto-optical performance,the total thickness of the configuration is reduced from 1.87 ?m to 0.72 ?m compared to the case in the first work,which is of great significance for the miniaturization of magneto-optical devices.