Magneto-optical Goose-Hansen Effect And Its Application Research

When a light beam is incident to the interface of two different transparent media,the reflection process follows the Snell's law.However,in the actual situation the reflected beam will undergo a non-specular reflection in the geometric space.That is,the reflection point has a slight displacement in the incident plane and in the direction perpendicular to the incident plane,which called Goos-H?nchen(GH)shift and Imbert-Fedorov(IF)shift,respectively.The essence of IF shift is the spin Hall effect of light(SHEL).In order to realize the practical applications of GH shift and SHEL,it is particularly important to modulate them flexibly.Previous studies have used different materials or structures for the modulation of GH shift and SHEL.Once the structure is fixed,it is difficult to regulate it anymore.The main purpose of this paper is to realize the magneto-optical modulation of GH shift and SHEL by applied magnetic field.Tunable GH shift and SHEL under the applied magnetic field is obtained,which can be called magneto-optical Goos-H?nchen(MOGH)shift and magneto-optical spin Hall effect of light(MOSHEL).(1)MOGH: Firstly,the magneto-optical surface plasmon resonance(MOSPR)waveguide based on Au-Ni nano-film is designed to realize the magneto-optical enhancement and modulation of GH shift.By changing the angle of incidence and the direction of the magnetic field,tunable GH shift is observed.We found that the MOGH spectrum obtained by the difference between the two GH spectrum under opposite magnetic field is narrower and is more sensitive to changes of structural parameters.The GH shift after weak amplification in the above structure was measured using a weak measurement,and refractive index sensing was realized by changing the solution concentration under the Au film.Then the GH shift is extended from the visible light band to terahertz band,and the magnetic field can be used to control the GH shift with the magnetic-doping characteristics of monolayer graphene.At the same time,both analytic and numerical methods are used for simulation,and results of them are in good agreement.(2)MOSHEL: We obtain the formula for calculating the spin dependent splitting of reflected light with a magnetically induced optical rotation.Three different structures are designed to realize the magneto-optical modulation of spin Hall effect of light.The first structure is a dielectric magneto-optical thin film(cerium-substituted yttrium iron garnet,Ce:YIG)with a double-negative(DNG)metamaterial substrate.In the second structure,we use a defective photonic crystal with graphene to modulate SHEL.The third structure is a Ce:YIG film with silica substrate.In the first structure,the magneto-optic Kerr effect and SHEL of reflected light from Ce:YIG film are greatly enhanced due to the presence of the double-negative metamaterial.Spin splitting is asymmetry in the case of polar and longitudinal magnetic fields but symmetry in a transverse magnetic field.In the second structure,greatly enhanced and tunable spin-dependent splitting of reflected light beam can be observed due to nonreciprocity of graphene and field localization of defect mode.In particular,light reflected at the surface of the photonic crystal appears a Kerr rotation close to 90 degrees.At the same time,the spin dependent splitting of left and right circularly polarized light is about 7 times the wavelength.The refractive index sensing characteristics were discussed later.Finally,we use weak measurement method to measure SHEL in the third structure,and the relevant conclusions obtained in the third structure were verified.