Inspired by iridoplasts, which are small, periodic, photonic multilayered chloroplasts, I create a simplified optical model to investigate their unusual characteristics. The properties of interest are their thin layers, narrowly peaked absorption spectra, and uncertain refractive index properties, which make them quite different from a standard Bragg reflector. The simple optical model, termed a Lorentz Oscillator-based Photonic Crystal, captures the essential features of resonant absorption and associated dispersion, in compliance with the Kramers-Kronig relations. I study in depth the relation of its optical properties to its structural parameters, including positional disorder of the layers. The lessons learned from the optical model are synthesised with the biological and ecological context in order to evaluate four hypotheses on the function of iridoplasts, two of which are novel proposals.
Optical modelling of resonantly absorbing multilayers: Implications for leaf iridescence and lamellar chloroplasts
Qiu, A. W. X. (Author). 19 Mar 2024
Student thesis: Doctoral Thesis › Doctor of Philosophy (PhD)