Role of incoherent substrate reflections in photonic crystal spectroscopy

TL;DR

This paper introduces a modeling method for photonic crystal structures on thick substrates, highlighting how incoherent substrate reflections significantly influence spectral features and peak positions.

Contribution

It presents a novel approach to account for incoherent substrate reflections in the optical modeling of photonic structures, affecting spectral analysis.

Findings

Incoherent reflections can dominate the spectral response.

Substrate reflections can shift spectral peak positions.

The method applies to multilayer microcavities and opal photonic crystals.

Abstract

A method is presented for modelling the optical properties of a photonic crystal structure mounted on a substrate which is thick enough that the light reflected from the back is incoherent with reflections from the front. Transmission and reflection spectra are presented for the cases where the structure is a multilayer planar microcavity and an opal photonic crystal. The contributions from the incoherent reflections can be very large, and in the photonic crystal case, change the positions of the spectral peaks.