Near-field imaging of the multi-resonant mode induced broadband tunable metamaterial absorber

Abstract

Metamaterial absorbers with tunability have broad prospects for mid-infrared absorption applications.

Review of Broadband Metamaterial Absorbers: From Principles, Design Strategies, and Tunable Properties to Functional Applications

“…[ 487 ] The GST‐based active tunable BMA achieves a covered wide operating band in the MIR range from 7.7 to 8.5 µm. [ 488 ] The introduction of new computer techniques, such as machine learning, has made it possible to predict the absorption performance. [ 489 ]…”

“…[93,96,[476][477][478][479][480] Importantly, VO 2 has two outstanding advantages: [93,96,[476][477][478][479][480] First, the conductivity of VO 2 is capable of multiple orders of magnitude variation; Second, its phase transition is reversible that could offer a new path to adjust the spectral properties of metamaterials. Therefore, this section first presents the dynamic modulation of VO 2 -based BMAs and then discusses BMAs with thermally tunable properties based on GST, [481][482][483][484][485][486][487][488][489] indium antimonide (InSb), [490,491] strontium titanate (STO), [492,493] nanocomposites, [494] and water. [452,[495][496][497][498][499] A thermally tuned BMA based on the phase transition properties of VO 2 was developed.…”

“…As a result, GST-based thermally tunable BMAs have been developed and presented. [481][482][483][484][485][486][487][488][489] For example, a thermally tunable visible BMA composed of a thin Au square array placed on a continuous Au film separated by a GST layer was demonstrated, which could achieve nearly perfect broadband, and flat absorption with polarization insensitive and large angle tolerable, [481] and the broadband absorption is firmly temperature dependent. A four-layer metasurface structure consisting of GST and patterned Jerusalem-shaped metallic arrays was proposed at visible regime, [482] which could achieve a broadband absorption covering almost the visible region from 500 to 740 THz having the average absorbance of up to 94.34%.…”

Imaging of THz Photonic Modes by Scattering Scanning Near-Field Optical Microscopy

“…Despite vivid interest in the applications of THz s-SNOM, so far, to the best of our knowledge, only one study focused on photonic resonators [43]. On the contrary, in the infrared (IR) domain, successful s-SNOM imaging of these systems have been already reported through the literature [44,45,46,47,48,49,50,51]. When applied to photonic resonators, in addition to material-related contrast, s-SNOM imaging reveals the localized electric fields scattered by the tip at sub-λ scale and is therefore a promising technique to probe single micro-resonators with high spatial resolution.…”

“…Indeed, despite vivid interest in the applications of THz s-SNOM, so far, to the best of our knowledge, only two studies focused on photonic resonators, , and similarly to shape-dependent contrast, interpretation of the recorded features is a recent subject of matter in the field of THz studies. On the contrary, in the infrared (IR) domain, successful s-SNOM imaging of these systems have been already reported through the literature. − Disregarding the challenge of traditional bulky THz sources and detectors, the current state-of-the-art is rather intriguing since THz resonators are larger and thus relatively easier to manufacture than their IR counterparts.…”