Study On The Control Of Goos-Hanchen Shift Based On Graphene-Medium Composite Structure

The Goos-H?nchen shift refers to the lateral displacement of the reflected beam from the geometric optical path in the incident plane when reflection occurs.It plays an important role in the fields of near-field optical detection,integrated optics,optoelectronic devices and so on.Generally,the Goos-H?nchen shift in optical frequency band is only on the order of micrometers,which limits its practical application in optoelectronic devices such as optical sensors.Therefore,the enhancement and regulation of the Goos-H?nchen shift has become one of the research hotspots in this field.At present,the scheme of controlling Goos-H?nchen shift based on graphene-medium composite structure has been extensively studied in the visible light and optical communication band,which can achieve flexible control of Goos-H?nchen shift by adjusting the conductivity of graphene.However,there are few reports on the study of controlling Goos-H?nchen shift in mid-infrared band.In mid-infrared band,graphene-hexagonal boron nitride supercrystals have hyperbolic adjustable properties.The Goos-H?nchen shift of the reflected beam on the surface of the structure can not only be controlled,but also be enhanced due to resonance characteristics of hexagonal boron nitride.In this paper,we study the modulation of the Goos-H?nchen shift of the TM-polarized beam in mid-infrared band reflected from graphene-SiO₂structure and graphene-hexagonal boron nitride structure.The specific work is as follows:1.The Goos-H?nchen shift control based on graphene-SiO₂structure.The Goos-H?nchen shift of the reflected beam on graphene-SiO₂ structure is analyzed by stationary-phase method and transfer matrix theory.The effect of Fermi level,the number of graphene layer and relaxation time on the Goos-H?nchen shift is studied.The results show that the Goos-H?nchen shift decreases with the increase of Fermi level,the number of graphene layer.The Fermi level increases from 0.2 eV to 0.5 eV,and the shift is reduced by only 17 times wavelength.The number of graphene layers is increased from 1 to 4,and the shift is reduced by 21.3 times wavelength.The relaxation time can regulate the magnitude of the Goos-H?nchen shift,but cannot change the sign.2.The Goos-H?nchen shift control based on graphene-hexagonal boron nitride structure.The Goos-H?nchen shift of reflected beam on graphene-hexagonal boron nitride structure is theoretically analyzed.The effects of Fermi level,the number of graphene layer,relaxation time and the thickness of hexagonal boron nitride on Goos-H?nchen shift are studied.The results show that the Goos-H?nchen shift also decreases with the increase of Fermi level and the number of graphene layer.When the Fermi level increases from 0.2eV to 0.5eV,the shift decreases by 48.6times wavelength,and the shift decreases by 51.8 times wavelength when the number of graphene layers increases from 1 to 4,and the control effect is more obvious.Controlling the relaxation time and the thickness of hexagonal boron nitride can chang the size but and the symbol of Goos-H?nchen shift.Compared with the graphene-SiO₂ structure,the Goos-H?nchen shift of the beam reflected from the surface of graphene-hexagonal boron nitride structure is enhanced.