Wavelength-selective mid-infrared metamaterial absorbers with multiple tungsten cross resonators

Abstract

Wavelength-selective metamaterial absorbers in the mid-infrared range are demonstrated by using multiple tungsten cross resonators. By adjusting the geometrical parameters of cross resonators in single-sized unit cells, near-perfect absorption with single absorption peak tunable from 3.5 µm to 5.5 µm is realized. The combination of two, three, or four cross resonators of different sizes in one unit cell enables broadband near-perfect absorption at mid-infrared range. The obtained absorption spectra exhibit omnidirectionality and weak dependence on incident polarization. The underlying mechanism of near-perfect absorption with cross resonators is further explained by the optical mode analysis, dispersion relation and equivalent RLC circuit model. Moreover, thermal analysis is performed to study the heat generation and temperature increase in the cross resonator absorbers, while the energy conversion efficiency is calculated for the thermophotovoltaic system made of the cross resonator thermal emitters and low-bandgap semiconductors.

Numerical Study of an Efficient Broadband Metamaterial Absorber in Visible Light Region

“…Furthermore, based on the equivalent RLC circuit model of the MIM three-layer structure, the input impedance of the MA is dependent on the intrinsic properties of both materials (metal and dielectric) and resonator shapes [2], [31], [38]. By tailoring the above parameters, the impedance matching band can be controlled, thus the tunable absorption band of the MA can be obtained.…”

Ultrabroadband Absorption Enhancement via Hybridization of Localized and Propagating Surface Plasmons

“…As shown in Figure 1 a, ultrabroadband absorption can be realized at wavelengths ranging from 380.0 to 2137.5 nm with absorptivity higher than 90% and average absorption of A av = 96.4%. The RAB of the Cr-based MA is 139.6%, which is larger than many types of MAs such as MIM-based MAs [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ], multi-sized MAs [ 21 , 22 , 23 , 24 , 25 , 26 ], and HMM-based MAs [ 42 , 43 , 44 , 45 , 46 ]. In addition, although only three metal/dielectric stacks are required, the RAB of the Cr-based MA is also comparable with those of the MAs such as multilayered-based nanocones [ 47 ] and pyramids [ 48 , 49 ].…”

“…To extend the bandwidth, multi-sized resonators with patterns such as strips [ 21 , 22 ], patches [ 23 , 24 ], ellipses [ 25 ], and crosses [ 26 ] can be integrated together to form a supercell, and the absorption bandwidth of the multi-sized MA can be effectively improved due to the blending of multiple resonant frequencies. Unfortunately, the achievable bandwidth is limited because the number of possible integrated resonators in a supercell is restricted.…”

Ultra-broadband metamaterial absorbers from long to very long infrared regime

“…Since Landy et al demonstrated the first metamaterial absorber with one perfect absorption peak in the microwave band through an experiment 19 , the control and engineering of the spectral absorption properties of MPAs has attracted significant interest. In their experiment, broadband perfect absorption was achieved with MPAs in microwave regime [20][21][22][23][24] and was extended from visible [25][26][27][28][29][30][31][32][33][34][35][36][37] , infrared [38][39][40][41][42][43][44][45][46][47][48][49][50][51] and THz [52][53][54][55][56][57] bands. This study will compare these representative theoretical and experimental works on the topic of broadband MPAs from visible to infrared bands in supplement document.…”

“…This study will compare these representative theoretical and experimental works on the topic of broadband MPAs from visible to infrared bands in supplement document. Research on broadband absorbers has led to the creation of a number of methods which are successfully used for expanding the absorption band using laminated structures 33,36,41 , coupling multi-sized metallic resonators 40,42,45,50 and inlaying metallic structures in the dielectric layer 25,27,29,31,49 . The common absorption mechanism of these traditional methods is coupling multiple resonances of broad wavelength bandwidth excited by multi-sized metallic resonators in the structures.…”