High-sensitivity Refractive Index Sensing Based On A Metal-Cladding Resonant Cavity And Research Of Spin Hall Effect Of Light

This paper demonstrates a refractive index sensing technique by a metal-cladding resonant cavity and explores spin Hall effect of light（SHEL）in the cavity.Based on ultra-high order modes（UOMs）and surface plasmon resonance mode（SPR mode）,the paper analyzes the optical characters of the resonant cavity and the mechanism of generating surface plasmon resonance and standing wave,and brings forward the concept of high-sensitivity detection.SPR mode and UOMs are both highly sensitive to the optical characters of cavity structure,such as refractive index.Based on this,we integrate prism and resonant cavity and propose a refractive index sensing approach,which combines SPR and UOMs.The mechanism of this approach is as follows-The SPR approach can first measure RI in a rather rough range and then measuring UOMs can obtain a more accurate value.Experimental results prove that the detection limit for this RI sensor can reach 10^-6 RIU and the sensitivity is 700°/RIU.The UOMs in resonant cavity possess strong coupling effect,which can enhance spin Hall effect of light（SHEL）.Light coupled into the resonant cavity will be separated into left-handed part and right-handed part,causing a transverse shift.This paper calculates the spin Hall effect of light in the proposed resonant cavity.And the results show that on certain conditions,the spin shift for resonant cavity can reach 0.786 mm.After thorough analysis,the enhancing effect stems from two factors of resonant cavity–dividing the reflective coefficient of TE mode and TM mode,and small incident angle.These two factors make it possible to directly detect the separation of left-handed and right-handed lights.On this basis,the paper explores the relationship between SHEL in resonant cavity and the parameters of the cavity and illustrates its potential in metal,chiral molecules sensing.