Fano Resonance Between Mie and Bragg Scattering in Photonic Crystals

TL;DR

This paper demonstrates a tunable Fano resonance in photonic crystals caused by interference between Mie and Bragg scattering, with experimental and theoretical analysis revealing the role of dielectric contrast and disorder.

Contribution

It introduces a quasi-3D model explaining Fano resonance in photonic crystals and links the resonance to dielectric contrast and disorder effects.

Findings

Fano resonance causes asymmetric transmission spectra in photonic crystals.

Resonance can be reversibly tuned from dip to rise in transmission.

Theoretical model matches experimental observations accurately.

Abstract

We report the observation of a Fano resonance between continuum Mie scattering and a narrow Bragg band in synthetic opal photonic crystals. The resonance leads to a transmission spectrum exhibiting a Bragg dip with an asymmetric profile, which can be tunably reversed to a Bragg rise. The Fano asymmetry parameter is linked with the dielectric contrast between the permittivity of the filler and the specific value determined by the opal matrix. The existence of the Fano resonance is directly related to disorder due to non-uniformity of a-SiO2 opal spheres. Proposed theoretical "quasi-3D" model produces results in excellent agreement with the experimental data.