Rough Fabry-Perot cavity: a vastly multi-scale numerical problem

TL;DR

This paper addresses the complex numerical challenge of modeling a Fabry-Perot cavity with highly disproportionate dimensions and roughened mirrors, crucial for advancing photonic devices and understanding optical properties.

Contribution

It introduces numerical methods to analyze multi-scale Fabry-Perot cavities with roughened mirrors, addressing a gap where statistical approaches are insufficient.

Findings

Roughness affects spectral properties of cavity modes

Numerical methods can handle multi-scale optical problems

First step towards designing photonic devices with rough cavities

Abstract

A commercial Fabry-Perot laser diode is characterized by highly disproportionate dimensions, which poses a significant numerical challenge, even for state-of-the-art tools. This challenge is exacerbated when one of the cavity mirrors is rough-ened, as is the case when fabricating random laser diodes. Such a system involves length scales from several hundred mi-crometres (length) to a few nanometres (roughness) all of which are relevant when studying optical properties in the visi-ble. While involving an extreme range of dimensions, these cavities cannot be treated through statistical approaches such as those used with self-similar fractal structures known to show well-studied properties. Here we deploy numerical meth-ods to compute cavity modes and show how random corrugations of the Fabry-Perot cavity wall affect statistical proper-ties of their spectral features. Our study constitutes a necessary first step in developing technologically essential devices for photonic computation and efficient speckle-free illumination.