Ultra-Narrow Band Mid-Infrared Perfect Absorber Based on Hybrid Dielectric Metasurface.

Chen Chen,Liu Liu,Zhou Zhou,Cheng Cheng,Xiao Xiao

doi:10.3390/nano9101350

Abstract

Mid-infrared perfect absorbers (PAs) based on metamaterials have many applications in material analysis and spectral detection thanks to the associated strong light–matter interaction. Most of the PAs are built as ‘metal nanostructure’-insulator-metals (MIM). In this paper, we propose an ultra-narrow band absorber based on dielectric metasurface with a metal film substrate. The absorptance comes from the plasmonic absorption in the metal film, where the absorption is enhanced (while the band of that is compressed) by the super cavity effect of the dielectric metasurface. Based on our numerical calculation, the full-width at half-maximum (FWHM) can reach 67 nm at 8 μm (8‰), which is more than two orders of magnitude smaller than the resonance wavelength and much narrower than the theoretical FWHMs of MIM absorbers. Moreover, we studied their application in infrared thermal imaging, which also has more benefits than MIM absorbers. This kind of hybrid dielectric metasurface provides a new route to achieve ultra-narrow band perfect absorbers in the mid-infrared regime and can be broadly applied in detectors, thermal emitters and bio-spectroscopy.

Highlights

Infrared (IR) spectroscopy can accurately detect chemical and biological species by characterizing the absorption bands of the chemical bonds they consist of, which are traditionally called the “fingerprints” of the molecules
In this paper, inspired by the super-cavity mode [29], we developed a new type of perfect absorber based on the hybridization of a dielectric metasurface and a metal film substrate
The absorption band could be tuned from 4 μm to 16 μm based on different complementary metal-oxide-semiconductor (CMOS)-compatible dielectric materials and technology, which could serve as a guideline for future research on hyper-spectrally selective infrared detectors and SEIRA chips

Summary

Introduction

Infrared (IR) spectroscopy can accurately detect chemical and biological species by characterizing the absorption bands of the chemical bonds they consist of, which are traditionally called the “fingerprints” of the molecules. As the coating or the environment near the structure changes, their spectral response will vary They have been widely employed for ultrasensitive detection of proteins, other functional molecules, or their structural changes [10,11,12,13,14,15,16] via the so-called “surface-enhanced infrared absorption spectroscopy (SEIRA)” technique. Nanoresonators based on high-index dielectric materials exhibit low intrinsic loss and most of them are CMOS compatible They provide a new box of tools at subwavelength scale to manipulate the propagation and localization of electromagnetic waves. The absorption band could be tuned from 4 μm to 16 μm based on different CMOS-compatible dielectric materials and technology, which could serve as a guideline for future research on hyper-spectrally selective infrared detectors and SEIRA chips

Methods

Mode Analysis

Tunability

Potential Applications