Robustness of subwavelength devices: a case study of cochlea-inspired rainbow sensors

Abstract

The aim of this work is to derive precise formulas which describe how the properties of subwavelength devices are changed by the introduction of errors and imperfections. As a demonstrative example, we study a class of cochlea-inspired rainbow sensors. These are devices based on a graded array of subwavelength resonators which have been designed to mimic the frequency separation performed by the cochlea. We show that the device's properties (including its role as a signal filtering device) are stable with respect to small imperfections in the positions and sizes of the resonators. Additionally, if the number of resonators is sufficiently large, then the device's properties are stable under the removal of a resonator.

Asymptotic characterisation of localised defect modes: Su-Schrieffer-Heeger and related models

“…As a demonstrative example, we would like to design a simple rainbow filtering device that localises specific frequencies at different positions, thereby separating a wave into its corresponding frequency components. These devices have been used for many significant applications including energy harvesting [7], machine hearing [1,10] and metamaterial spectrometry [31].…”