Research And Regulation Of Bound States In The Continuum Of Symmetry Breaking Nanohole Arrays

The bound states in the continuum(BIC)domain are located inside the continuum domain and coexist with the expansion wave,and are still completely restricted without any radiation.BIC in the field of photonics provides a simple way to obtain very large quality factor(Q-factor)for photonic crystals,subsurface and even subwavelength isolated resonators.Therefore,it has been widely used in the fields of micro-nano all-optical integrated circuits,biosensing,slow light and optical storage.In this paper,different types of micro-nano hole structures such as the photonic crystal(Ph C)plate rectangular micro-nano hole array structure are used as the research objects of BIC,and the finite difference time domain method(FDTD)and coupled mode theory(CMT)are used.The combined method regulates BIC.Specific research content:1.Research the BIC of the nanohole array structure(cross-shaped,T-shaped,7-shaped)by adjusting the lattice constant,the nanohole size,the refractive index of the insertion layer and the refractive index of the surrounding medium,and the Q-factor is greater than 10~5.2.By adjusting the size and asymmetry of the U-shaped nanohole,the effect of BIC can be studied.3.By adjusting the refractive index of one of the three rectangular nanoholes in the U-shaped symmetrical structure,to study the influence on BIC.4.Taking the double-layer Ph C board as the research object,the influence of the symmetry and asymmetry of the broken rectangular ring nanoholes on the number of BICs are adjusted.5.By adjusting the distance between the Ph C plates and the angle of incidence,study the effect on the broken rectangular ring nanohole array structure BIC.Results of this research:1.The cross-shaped nanohole array structure can obtain BIC due to symmetry incompatibility,the T-shaped nanohole array structure can not obtain BIC because the symmetry plane of the symmetric structure is parallel to the oscillation direction of the incident light,the 7-shaped nanohole array structure does not have the characteristics of mirror symmetry,and BIC cannot be obtained.2.The size of the U-shaped nanohole can control the position of the at-?BIC and the way the structure is asymmetry is different,and the Q-factor is not on the same order of magnitude.3.The symmetry and asymmetry between the double-layer Ph C plate symmetry breaking the rectangular ring nanohole array structure can obtain multiple BICs at the same time.4.Tunable BIC can be realized at any incident angle.5.The double-layer Ph C plate breaks the rectangular ring nanohole array structure and provides a simple platform for studying the interaction resonance between the plates.This research aims to provide a theoretical basis for the design of elements based on the bound states in the optical continuum in various applications such as novel tunable biosensors,perfect filters,and waveguides.