Research On Enhancement Mechanism And Regulation Method Of Photonics Spin Hall Effect

In recent years,with the deepening of spin Hall effect research,a novel physical phenomenon,which is similar to the electron spin Hall effect--photonics spin Hall effect of light(SHEL)has gradually entered the field of researchers.The photonics spin Hall effect is that when a bundle of spatially constrained linearly polarized light is reflected and refracted at the interface through the inhomogeneous medium,the photons with opposite spin angular momentum(left and right circular polarization)are separated from each other in the transverse direction perpendicular to the incident surface,causing spin splitting of the incident beam.This paper will combine some typical physical principles,such as surface plasmon resonance(SPR),guide-wave surface plasmon resonance coupling(GW-SPR),resonant optical tunneling effect(ROTE),bound states in the continuum(BIC),to explore the enhancement and regulation method of photonics spin Hall effect.As a precision measurement tool,the photonics spin Hall effect of light can not only characterize the parameters changes of nanostructures materials,but also can be well applied to optical sensors to improve their sensitivity and measurement accuracy.The corresponding work and research results are as follows:1?The surface plasmon resonance(SPR)with the bimetallic film can achieve minimum reflectivity and higher evanescent field enhancement than the SPR configuration with the single gold film,which makes it be a much better option for enhancing the photonic spin Hall effect of light(SHEL).It is found that the thicknesses of silver and gold films have a major impact on the SHEL,and the maximal transverse shift of horizontal polarization state can reach to 5.34?m near the SPR resonant angle by optimizing the thicknesses of silver and gold films in the bimetallic film.Our results are far greater than the previously reported transverse shifts in the conventional SPR structure.In addition,we propose a method to enhance SHEL with the guided-wave surface-plasmon resonance(SPR).The maximum transverse shift of the horizontal polarization state with 11.5 ?m is obtained when the thickness of Si film is optimum.There is at least an order of magnitude enhancement in contrast with the transverse shift in the conventional SPR configuration.Our research is important for providing an effective way to improve the SHEL and may offer the opportunity to characterize the parameters of the dielectric layer with the help of weak measurements and development of sensors based on the SHEL.This novel phenomenon is attributed to the higher evanescent field enhancement and the larger refractive index variation gradient of silver/gold bimetallic film.These findings provide us an effective method to manipulate the SHEL,and therefore establish a strong foundation for developing photonic devices based on SHEL.The related researches published on “Plasmonics and Photonics Research”.2?Resonant optical tunneling effect(ROTE)has been proposed to investigate both the fundamental physics and the practical applications.ROTE is used to enhance the photonics spin Hall effect of transmitted light.It is demonstrated that sandwiching a layer of high refractiveindex media(boron nitride crystal)between two low refractive-index layers(silica)can effectively enhance the photonic SHE due to the larger refractive index gradient and the enhanced evanescent field near the interface between silica and boron nitride.The maximum transverse shift of the horizontal polarization state in the ROTE structure about 22.25?m has been obtained,which is at least three order of magnitude enhancements in contrast with the transverse shift in the frustrated total internal reflection(FTIR)structure.Moreover,SHEL can be manipulated by controlling the component materials and the thickness of the ROTE structure.These findings open the possibility for the future applications of photonic SHE in the precision metrology and the spin-based photonics.The related researches published on “Journal of Physics D: Applied Physics”.3?We have investigated theoretically the reflectivity,the transverse values produced by photonics spin Hall effect of light(SHEL),and sensitivity for the sandwich structure with epsilon near zero(ENZ)material when the bound states in the continuum(BICs)occur.Compared to conventional structures such as surface plasmon resonance(SPR),the transverse value and sensitivity of PSHE have been greatly enhanced due to the BIC phenomena in the ENZ material.Moreover,it is demonstrated that the transverse value,intensity sensitivity,and angle sensitivity are 21.74?m,15542?m/RIU and 220°/RIU when the reflectance ratio and the thickness are respectively optimized at the BIC position.Our results give such an optical system of the potential applications in lasers,biosensors,and optical waveguides.The related researches published on “Journal of Physics D: Applied Physics”.