Ultrathin Semiconductor Perfect Light Absorbers with High Spectral, Polarization, and Angle Selectivity for Arbitrary Wavelengths

TL;DR

This paper introduces novel design strategies for ultrathin semiconductor perfect light absorbers that achieve high spectral, polarization, and angle selectivity across arbitrary wavelengths, surpassing limitations of existing materials.

Contribution

It presents an intuitive model and coupled leaky mode theory to design ultrathin semiconductor absorbers with extraordinary absorption and selectivity, including at wavelengths with weak intrinsic absorption.

Findings

Achieved near-perfect absorption in ultrathin semiconductors

Demonstrated high selectivity for wavelength, polarization, and incident angle

Enabled development of flexible, lightweight optoelectronic devices

Abstract

Enabling perfect light absorption in ultrathin materials promises the development of exotic photonic devices. Here we demonstrate new strategies that can provide capabilities to rationally design ultrathin (thickness < {\lambda}/10~{\lambda}/5) semiconductor perfect absorbers for arbitrary wavelengths, including those at which the intrinsic absorption of the semiconductor is weak, e.g. Si for near-IR wavelengths. This is in stark contrast with the existing studies on ultrathin perfect absorbers, which have focused on metallic materials or highly-absorptive semiconductors. Our design strategies are built upon an intuitive model, coupled leaky mode theory that we recently developed and can turn the design for perfect absorbers to the design for leaky modes. The designed absorber is featured with extraordinary absorption enhancement, miniaturized dimension, and high selectivity for the wavelength, polarization, and angle of incident light. It can enable the development of flexible, light-weight, high-performance, cost-effective, and multifunctional optoelectronic devices that are difficult with current light absorbers.