Tunable infrared asymmetric light transmission and absorption via graphene-hBN metamaterials

Abstract

We theoretically prove in this paper that using planar multilayer graphene-hexagonal boron nitride (hBN) metamaterials (GhMMs) can yield ultrabroadband and high-contrast asymmetric transmission (AT) and asymmetric absorption (AA) of light. The AA and AT features are obtained in the far-infrared (FIR) and mid-infrared (MIR) regions for normally incident light with transverse magnetic polarization. Here, the GhMMs are integrated with two asymmetric gratings of Ge and are composed of alternating multilayers of graphene (11 multilayers) and hBN layers (10 layers). Moreover, the total subwavelength thickness of the hybrid structures is about 3 μm, being less than half of the free-space wavelength up to nearly 50 THz. This approach-which is similar to the one introduced by Xu and Lezec [Nat. Commun. 5, 4141 (2014)] for a passive hyperbolic metamaterial operating in the visible range-is based on the excitation of high-β modes of the GhMM with different transmission characteristics. In addition to being ultrabroadband and high-contrast, AT and AA features of the proposed GhMMs can be actively tuned by varying the chemical potential of graphene. Furthermore, it is shown that an onoff switching of AT factor at FIR and selective tunability at MIR frequencies can be obtained via varying μ. Due to its subwavelength and planar configuration and active operation, these multilayer graphene-hBN metamaterials with AT and AA characteristics hold promise for integration with compact optical systems operating in the MIR and FIR ranges and are suitable for applications such as optical diodes, sensors, and thermal emitters.

A Dual‐Mode Infrared Asymmetric Photonic Structure for All‐Season Passive Radiative Cooling and Heating

“…From a future perspective, intelligent designs are promising in improving their practicability, in which the APM can be based on thermos-responsive smart material and the dynamic optical modulation dismisses the mechanical flipping. [37,42] The proposed APM can be extensively applied in plenty of energy-saving thermoregulating systems, such as for automobile interior, electronic equipment, and smart buildings. By this approach, wide range of optical asymmetry, and broadband optical manipulation can be systematically designed and fabricated with versatility in material choice.…”

“…Electromagnetic asymmetry can be referred to as asymmetric optical properties for forward and backward electromagnetic incidences. [37][38][39] Metamaterial, non-linear system, and periodic structures have been widely employed with applications in linear polarization rotators, optical diodes, sensors, thermal emitters, infrared camouflaging, and others. [40][41][42][43][44] Among all, asymmetric infrared transmission and reflection is the promising breakthrough required for an all-season and all-terrain sustainable passive cooling/heating technology.…”

Adaptive multi-spectral mimicking with 2D-material nanoresonator networks

“…As shown in figure 1, the network consists of optically coupled nanoribbons whose response depends on parameters set during fabrication (such as element size and arrangement in the network) and parameters that can be tuned post-fabrication (such as voltage). Graphene, being a 2D semi-metal, has optical properties that can be strongly influenced by electric fields, leading to its use in tunable applications such as electronic modulation of emission [28][29][30][31] infrared absorption [32,33], tunable scattering [34,35], and amplitude and phase modulation [36][37][38], among others.…”