| The Goos-H(?)nchen shift(GH shift)is an interesting optical phenomenon,which refers to a transverse displacement relative to the geometrically optically predicted position and it occurs when a beam is illuminated at the interface of two media.Since its discovery,this phenomenon has attracted great attention and has been investigated theoretically and experimentally.It is widely used in practical applications,such as sensing,precision instrumentation measurements and imaging.However,the amplitude of GH shift is usually small and difficult to adjust in the structures with the conventional material,how to enhance or adjust the GH shift has become a hot topic in this field.As a new type of two-dimensional material,monolayer graphene has excellent optical and electrical properties,such as the chemical potential and temperature controlled optical conductivity of monolayer graphene,which is benefit for the modulation of the GH shift.In this paper,the GH shifts in the composite structures with monolayer graphene are investigated using the rigorous coupled-wave analysis,the transmission matrix method and the stationary phase method.The main researches of this paper are as follows:First,the GH shift in a BK7(glass)grating structure based on monolayer graphene is theoretically studied.It is found that there are two GH shift peaks with magnitude of 2564 and 1993times of the incident wavelength in the GH spectrum of the structure,respectively.Meanwhile,its reflectances at the wavelengths where the GH peaks occur are also high.The enhanced GH shift can be ascribed to the excitation of the guide mode resonance in the waveguide dielectric layer below BK7 grating structure and their high reflectances are granted by the constructive interferences between the reflected waves.In addition,the GH shift of this structure can be regulated by varying the temperature of BK7,the chemical potential of the monolayer graphene and the geometric parameters of the composite structure.a temperature sensor based on the GH shifts in this structure is designed,which has a maximum temperature sensitivity of 5.0017×10~4μm/℃.The results provide a possible way to design the various sensors such as temperature sensors and optical sensors.Second,the GH shift in a composite structure consisting of two monolayers of graphene,BK7film and photonic crystal is investigated.It is found that the GH shift in this structure can be enhanced to 3708 times of the incident wavelength.At the same time,the effects of the variation of the GH shift in this structure with the temperature of BK7,the chemical potential and the relaxation time of monolayer graphene,the geometrical parameters such as the thickness and the number of periods of the photonic crystal are also discussed.The designed structure here not only achieves the enhancement of the GH shift amplitude but also its switching of the sign of the GH shift,which provides a practical solution for the study of photodetectors and optical switches.Finally,the GH shift in a Thue-Morse(TM)sequence quasi-periodic photonic crystal composite structure consisting of monolayer graphene,quasi-periodic photonic crystal and defects is investigated.It is found that the GH shift peak value in this structure can reach 951 times of the incident wavelength,whose enhancement originates from the localized defect modes in the defective layers of the photonic crystal structure enhancing the interaction between light and the monolayer graphene-based hybrid structure.In addition,the peak amplitude and peak position of the GH shift in the structure can be modulated by changing the chemical potential of the monolayer graphene,the geometric parameters of the photonic crystal structure and the different sequences of Thue-Morse.This work demonstrates the role of quasi-periodic photonic crystal structures with Thue-Morse sequence in enhancing the GH shift and provides a new platform for investigating the GH shift. |
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