Analysis of the composite response of a polygonal array of chiral slab resonators via superposition of transverse modes at the centroid

Abstract

In this paper, we design arrays of chiral slab resonators (Fabry-Perot-type (FP)) aligned polygonally and illuminated by a linear, p-polarized plane wave incident normally on the array slabs. Each such slab is analyzed using standard chiral slab resonance analyses developed recently [1]; evaluating the corresponding mode spectra for the right- and left-circular polarization ((RCP and LCP) modes for variable chirality coefficients, considering the slab thickness and substrate placement conditions as a function of the (monochromatic) mode frequency. In the polygonal array configuration, photodetectors (PDs) are added to convert the light into photocurrents (related to optical intensity); the intensities from the PDs are superposed at a single spatial point (chosen to be the centroid of the polygon). Hence, in this approach, a net intensity is generated at the centroid in response to a normally illuminated polygonal array. The array design is numerically analyzed, and the overall frequency and parametric properties evaluated. The spectral and resulting intensity behavior vis-à-vis mode frequencies for M slabs is determined under (1) matched resonator (with identical material parameters including thickness (d) and chirality coefficient (𝜅̃)) illumination with maximal transmission (which gives maximum superposed intensity) given by M times each individual intensity; and (2) unmatched resonators with a spread of d and K, such that the overall superposed array intensity pattern becomes adjustable and controllable, resulting in wideband or narrowband modal responses as desired or attainable by design. Both types of composite behavior for the two types of polygonal arrays are examined in detail and results discussed.