Optical Response Characteristics Of Thin Metal Nanostructures

This paper combines the Goos-H?nchen shifts with the general Snell's law,and theoretically presents the analytical solution of the GH shifts with phase gradient metasurfaces under TE and TM polarization.This gives a different method to control GH shifts.The extraordinary optical transmission characteristics of tilted silver nanohole arrays are also studied in this paper.This extraordinary optical transmission feature of silver nanoholes can be used for optical detection,filtering and so on.When the holes are tilted,the relationship of the transmission properties with angle changes were studied less in the past,so it is worthy of discussion.The main content of the paper is as follows:1.Based on the combination of the Goos-H?nchen shifts and the generalized Snell's law,the analytical solution of the GH shifts with surface phase gradient under TE and TM polarization is theoretically given.When the phase gradient value gradually increases from a negative value to a positive value,the GH shifts always decreases as the phase gradient increases.At low frequencies,the GH shift decreases faster but eventually flattens.For a fixed phase gradient value,the GH shift value under TM polarization is always less than the GH shift under TE polarization.On the whole,the negative phase gradient brings more obvious changes to the GH shift.Therefore,the GH shifts can be controlled by adjusting the phase gradient on the interface.2.Using the numerical simulation method,the transmission characteristics of the hexagonal periodic inclined silver nanoholes were studied.The simulated wavelength range is 200-1000 nm.Under normal incidence,the relationship between the transmission and the tilt angle of the aperture is given for the P and S polarizations,and the mechanism of this light transmission is qualitatively explained by the distribution of the electric field and the energy flow density in the cross section.As a result of the fact that the Ag nanoholes has a tilting angle and symmetry break in a certain direction in the structure,the transmission changes with the corresponding angle by mimicking a fixed-angle oblique incident and a fixed tilting angle under angular incident.It was found that when the Ag layer is thin,the transmission results have good symmetry for 0 degree angles at both symmetrical incidence and symmetrical tilt angle,but when the Ag layer is thick,the symmetry of the transmission result is destroyed.This is mainly because the thickness of the Ag layer affects the efficiency of the localized plasmon oscillation.