Enhanced light absorption in Tamm metasurface with a bound state in the continuum

TL;DR

This paper demonstrates how a Tamm state in a germanium grating on a photonic substrate can be engineered to achieve near-perfect light absorption at telecom wavelengths, useful for optical devices.

Contribution

It introduces a novel design leveraging a bound state in the continuum to create an ultra-narrow, highly efficient light absorber in a semiconductor grating.

Findings

Achieved 100% absorption in the germanium grating.

Enabled narrow absorption resonances within the photonic band gap.

Applicable at both normal and oblique incidence at telecom wavelengths.

Abstract

We consider light absorption in a germanium grating placed on top of photonic-crystalline substrate. Such a system supports an optical Tamm state decoupled from the continuous spectrum with its frequency within the photonic band gap. We have demonstrated that application of the Tamm state makes in possible to engineer extremely narrow absorber which provides a 100% absorption in a semiconductor grating in the critical coupling regime. The proposed design may be used at both normal and oblique incidence at the telecom wavelength.