Bi-modal resonance and spectral characteristics of a thin chiral slab resonator on an achiral substrate using Fresnel coefficients

摘要

Recently, some work involving investigation of polarization states and Fresnel coefficients (FCs) at an achiral/chiral(ACC) interface indicated that depending on specific chiral bands and also the density (or phase index) of the twodielectrics, certain types of anomalous behavior would result. These anomalies included Brewster effects for s-polarizedincident light, and total internal reflection (TIR) for propagation from lower to higher phase index. Analog time signals aswell as 2-dimensional stationary images were propagated across the ACC boundary to determine the effect of chiralityand parameters such as permittivity and permeability under dispersion. Extensions to the case of two interfacescomprised of an ACC on the front end and a chiral/achiral (CAC) on the back will be considered in this work. We notethat a slab resonator is amenable to analyses similar to a Fabry-Perot (FP) resonator. Analysis is carried out here for thechiral slab (say with thickness d) having both ACC and CAC boundaries; here multiple reflections and transmissions areexpected. Matlab simulations are carried out by incorporating boundary conditions and deriving the effective transmittedand reflected fields relative to the slab. The results are examined for a thin chiral slab with thickness d (sandwichedbetween achiral surface and substrate layers) in the range 10-100 nm. The transmission characteristics (which areexamined to study the resonance behavior of a typical FP etalon) are investigated as functions of wavelength or frequencyin the thick and thin film limits, and results are compared from resonance, resolution and polarization perspectives.