On chemiluminescent emission from an infiltrated chiral sculptured thin film

TL;DR

This paper develops a theoretical model for far-field emission from dipoles inside infiltrated chiral sculptured thin films, revealing polarization-dependent emission and how it shifts with infiltrant refractive index and particle size.

Contribution

It extends the Green function formalism and homogenization approach to account for infiltration effects in CSTFs, providing new insights into polarization-selective emission.

Findings

LCP and RCP emissions are preferentially emitted through opposite faces.

Red shift of emission wavelength occurs with increasing infiltrant refractive index.

Bandwidth of emission regime decreases as infiltrant refractive index increases.

Abstract

The theory describing the far-field emission from a dipole source embedded inside a chiral sculptured thin film (CSTF), based on a spectral Green function formalism, was further developed to allow for infiltration of the void regions of the CSTF by a fluid. In doing so, the extended Bruggeman homogenization formalism--which accommodates constituent particles that are small compared to wavelength but not vanishingly small--was used to estimate the relative permittivity parameters of the infiltrated CSTF. For a numerical example, we found that left circularly polarized (LCP) light was preferentially emitted through one face of the CSTF while right circularly polarized (RCP) light was preferentially emitted through the opposite face, at wavelengths within the Bragg regime. The centre wavelength for the preferential emission of LCP/RCP light was red shifted as the refractive index of the infiltrating fluid increased from unity, and this red shift was accentuated when the size of the constituent particles in our homogenization model was increased. Also, the bandwidth of the preferential LCP/RCP emission regime decreased as the refractive index of the infiltrating fluid increased from unity.