scholarly journals Split-cube-resonator-based metamaterials for polarization-selective asymmetric perfect absorption

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Odysseas Tsilipakos ◽  
Angelos Xomalis ◽  
George Kenanakis ◽  
Maria Farsari ◽  
Costas M. Soukoulis ◽  
...  
Keyword(s):  
Thermal Emission ◽  
Cost Effective ◽  
Infrared Region ◽  
Transparency Window ◽  
Electromagnetic Properties ◽  
Perfect Absorber ◽  
Metamaterial Structure ◽  
Perfect Absorption ◽  
Atmospheric Transparency ◽  
Direct Laser

Abstract A split-cube-resonator-based metamaterial structure that can act as a polarization- and direction-selective perfect absorber for the infrared region is theoretically and experimentally demonstrated. The structure, fabricated by direct laser writing and electroless silver plating, is comprised of four layers of conductively-coupled split-cube magnetic resonators, appropriately rotated to each other to bestow the desired electromagnetic properties. We show narrowband polarization-selective perfect absorption when the structure is illuminated from one side; the situation is reversed when illuminating from the other side, with the orthogonal linear polarization being absorbed. The absorption peak can be tuned in a wide frequency range by a sparser or denser arrangement of the split cube resonators, allowing to cover the entire atmospheric transparency window. The proposed metamaterial structure can find applications in polarization-selective thermal emission at the IR atmospheric transparency window for radiative cooling, in cost-effective infrared sensing devices, and in narrowband filters and linear polarizers in reflection mode.

scholarly journals Ultrathin and Electrically Tunable Metamaterial with Nearly Perfect Absorption in Mid-Infrared

2019 ◽  
Vol 9 (16) ◽  
pp. 3358 ◽  
Author(s):  
Yuexin Zou ◽  
Jun Cao ◽  
Xue Gong ◽  
Ruijie Qian ◽  
Zhenghua An
Keyword(s):  
Resonant Mode ◽  
Infrared Region ◽  
Perfect Absorber ◽  
Geometrical Structures ◽  
Material Loss ◽  
Absorption Region ◽  
Perfect Absorption ◽  
Mid Infrared ◽  
Wide Range ◽  
Metal Insulator Metal

Metamaterials integrated with graphene exhibit tremendous freedom in tailoring their optical properties, particularly in the infrared region, and are desired for a wide range of applications, such as thermal imaging, cloaking, and biosensing. In this article, we numerically and experimentally demonstrate an ultrathin (total thickness < λ 0 / 15 ) and electrically tunable mid-infrared perfect absorber based on metal–insulator–metal (MIM) structured metamaterials. The Q-values of the absorber can be tuned through two rather independent parameters, with geometrical structures of metamaterials tuning radiation loss (Qr) of the system and the material loss (tanδ) to further change mainly the intrinsic loss (Qa). This concise mapping of the structural and material properties to resonant mode loss channels enables a two-stage optimization for real applications: geometrical design before fabrication and then electrical tuning as a post-fabrication and fine adjustment knob. As an example, our device demonstrates an electrical and on-site tuning of ~5 dB change in absorption near the perfect absorption region. Our work provides a general guideline for designing and realizing tunable infrared devices and may expand the applications of perfect absorbers for mid-infrared sensors, absorbers, and detectors in extreme spatial-limited circumstances.

scholarly journals Multiple-patterning colloidal lithography-implemented scalable manufacturing of heat-tolerant titanium nitride broadband absorbers in the visible to near-infrared

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Dasol Lee ◽  
Myeongcheol Go ◽  
Minkyung Kim ◽  
Junho Jang ◽  
Chungryong Choi ◽  
...  
Keyword(s):  
Titanium Nitride ◽  
Large Scale ◽  
Near Infrared ◽  
Infrared Region ◽  
Absorption Efficiency ◽  
Perfect Absorber ◽  
Colloidal Lithography ◽  
Perfect Absorption ◽  
Broadband Absorber ◽  
Heat Tolerant

AbstractBroadband perfect absorbers have been intensively researched for decades because of their near-perfect absorption optical property that can be applied to diverse applications. Unfortunately, achieving large-scale and heat-tolerant absorbers has been remained challenging work because of costly and time-consuming lithography methods and thermolability of materials, respectively. Here, we demonstrate a thermally robust titanium nitride broadband absorber with >95% absorption efficiency in the visible and near-infrared region (400–900 nm). A relatively large-scale (2.5 cm × 2.5 cm) absorber device is fabricated by using a fabrication technique of multiple-patterning colloidal lithography. The optical properties of the absorber are still maintained even after heating at the temperatures >600 ∘C. Such a large-scale, heat-tolerant, and broadband near-perfect absorber will provide further useful applications in solar thermophotovoltaics, stealth, and absorption controlling in high-temperature conditions.

scholarly journals MULTI-BAND PERFECT ABSORPTION INDUCED BY BREAKING THE SYMMETRY OF METAMATERIAL STRUCTURE

2019 ◽  
Vol 57 (4) ◽  
pp. 477
Author(s):  
Dinh Hoang Tiep ◽  
Bui Son Tung ◽  
Bui Xuan Nguyen ◽  
Vu Dinh Lam
Keyword(s):  
Geometrical Structure ◽  
Absorption Peak ◽  
Perfect Absorber ◽  
Metamaterial Structure ◽  
Perfect Absorption ◽  
Efficient Approach ◽  
Symmetric Geometry ◽  
Breaking Symmetry ◽  
Metamaterial Perfect Absorber ◽  
Multi Band

In this work, a multi-band metamaterial perfect absorber is demonstrated numerically and experimentally in the microwave region based on the breaking symmetry of geometrical structure. Initially, when the structure, which is designed in the X shape, is in the symmetric geometry, only one absorption peak is observed. By breaking the symmetry of structure, new absorption peaks emerge, leading to the multi-band perfect absorption. In addition, the separations of absorption peaks are proportional to the degree of geometrical asymmetry. Our work presents a simple and efficient approach to create multi-band metamaterial perfect absorbers.

scholarly journals Spectroscopic detection of forest diseases: a review (1970–2020)

2021 ◽  
Author(s):  
Lorenzo Cotrozzi
Keyword(s):  
Early Detection ◽  
Optical Sensors ◽  
Near Infrared ◽  
Sustainable Forest Management ◽  
Visible Spectrum ◽  
Cost Effective ◽  
Infrared Region ◽  
Forest Disturbances ◽  
Effective Manner ◽  
Forest Diseases

AbstractSustainable forest management is essential to confront the detrimental impacts of diseases on forest ecosystems. This review highlights the potential of vegetation spectroscopy in improving the feasibility of assessing forest disturbances induced by diseases in a timely and cost-effective manner. The basic concepts of vegetation spectroscopy and its application in phytopathology are first outlined then the literature on the topic is discussed. Using several optical sensors from leaf to landscape-level, a number of forest diseases characterized by variable pathogenic processes have been detected, identified and quantified in many country sites worldwide. Overall, these reviewed studies have pointed out the green and red regions of the visible spectrum, the red-edge and the early near-infrared as the spectral regions most sensitive to the disease development as they are mostly related to chlorophyll changes and symptom development. Late disease conditions particularly affect the shortwave-infrared region, mostly related to water content. This review also highlights some major issues to be addressed such as the need to explore other major forest diseases and geographic areas, to further develop hyperspectral sensors for early detection and discrimination of forest disturbances, to improve devices for remote sensing, to implement long-term monitoring, and to advance algorithms for exploitation of spectral data. Achieving of these goals will enhance the capability of vegetation spectroscopy in early detection of forest stress and in managing forest diseases.

Simple metamaterial structure enabling triple-band perfect absorber

2015 ◽  
Vol 48 (37) ◽  
pp. 375103 ◽  
Author(s):  
Nguyen Van Dung ◽  
Bui Son Tung ◽  
Bui Xuan Khuyen ◽  
Young Joon Yoo ◽  
Young Ju Kim ◽  
...  
Keyword(s):  
Perfect Absorber ◽  
Metamaterial Structure ◽  
Triple Band

scholarly journals Quad-Band Plasmonic Perfect Absorber for Visible Light with a Patchwork of Silicon Nanorod Resonators

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1954 ◽  
Author(s):  
Can Cao ◽  
Yongzhi Cheng
Keyword(s):  
Visible Light ◽  
Transverse Electric ◽  
Transverse Magnetic ◽  
Localized Surface Plasmon ◽  
Perfect Absorber ◽  
Absorption Properties ◽  
Perfect Absorption ◽  
Potential Applications ◽  
Polarization Insensitive ◽  
Band Absorption

In this paper, a plasmonic perfect absorber (PPA) based on a silicon nanorod resonator (SNRR) for visible light is proposed and investigated numerically. The proposed PPA is only a two-layer nanostructure consisting of a SNRR periodic array and metal substrate. The perfect absorption mainly originates from excitation of the localized surface plasmon resonance (LSPR) mode in the SNRR structure. The absorption properties of this design can be adjusted by varying the radius (r) and height (h) of the SNRR structure. What is more, the stronger quad-band absorption can be achieved by combing four different radius of the SNRR in one period as a super unit-cell. Numerical simulation indicates that the designed quad-band PPA can achieve the absorbance of 99.99%, 99.8%, 99.8%, and 92.2% at 433.5 THz, 456 THz, 482 THz, and 504.5 THz, respectively. Further simulations show that the proposed PPA is polarization-insensitive for both transverse electric (TE) and transverse magnetic (TM) modes. The proposed PPA can be a desirable candidate for some potential applications in detecting, sensing, and visible spectroscopy.

scholarly journals Hybrid Metamaterials Perfect Absorber and Sensitive Sensor in Optical Communication Band

2021 ◽  
Vol 9 ◽  
Author(s):  
Xuehan Liu ◽  
Keyang Li ◽  
Zhao Meng ◽  
Zhun Zhang ◽  
Zhongchao Wei
Keyword(s):  
Optical Communication ◽  
Electromagnetic Waves ◽  
Incident Angle ◽  
Silicon Layer ◽  
Resonance Wavelength ◽  
Metamaterial Absorber ◽  
Absorption Peak ◽  
Dual Band ◽  
Perfect Absorber ◽  
Perfect Absorption

A subwavelength metamaterial perfect absorber (MPA) in optical communication band was proposed and tested using the finite-difference time-domain method. The absorber is periodic and comprises a top layer of diamond silicon surrounded by L-shaped silicon and a gold layer on the substrate. It can achieve dual-band perfect absorption, and one of the peaks is in the optical communication band. By changing the gap (g) between two adjacent pieces of L-shaped silicon, and the thickness (h) of the silicon layer, the resonance wavelength of absorption peak can be tuned. When the incident electromagnetic wave entered the absorber, the metamaterial absorber could almost completely consume the incident electromagnetic waves, thereby achieving more than 99% perfect absorption. The absorption peak reaches 99.986% at 1310 nm and 99.421% at 1550 nm. Moreover, the MPA exposed to different ambient refraction indexes can be applied as plasma sensors, and can achieve multi-channel absorption with high figure of merit (FOM*) value and refractive index (RI) sensitivity. The FOM* values at 1310 nm and 1550 nm are 6615 and 168, respectively, and both resonance peaks have highly RI sensitivity. The results confirm that the MPA is a dual-band, polarization-independent, wide-angle absorber and insensitive to incident angle. Thence it can be applied in the fields of optical communication, used as a light-wave filter and plasma sensor, and so on.

scholarly journals Research on Perfect and Tunable Metamaterial Absorber Based on Crosshair-shaped Graphene

2021 ◽  
Vol 2109 (1) ◽  
pp. 012015
Author(s):  
Yiran Guo ◽  
Yunping Qi ◽  
Chuqin Liu ◽  
Weiming Liu ◽  
Xiangxian Wang
Keyword(s):  
Relaxation Time ◽  
Chemical Potential ◽  
Incident Angle ◽  
Fdtd Method ◽  
Reference Value ◽  
Metamaterial Absorber ◽  
Selective Absorption ◽  
Perfect Absorber ◽  
Wide Angle ◽  
Perfect Absorption

Abstract Graphene, as a new nano-material, according to the physical properties of electric field localization and selective absorption on light of surface plasmon resonance (SPR), a tunable, multi-band and wide-angle perfect absorber based on crosshair-shaped graphene is devised by using the Finite Difference in Time Domain (FDTD) method. In this paper, the effects of chemical potential, relaxation time, and incident angle of light on the absorptivity of graphene are systematically discussed. The simulation experiment shows that there are two absorption peaks with perfect absorption rate appeared in the study range, and the maximum modulation index can be obtained by changing the relaxation time. Finally, it proves that the absorber is insensitive to wide-angle of light. Thus, it is able to be concluded that the absorber has a great reference value to sensor, wireless communication, biomedical and other fields.

scholarly journals Optical Properties of CaF2 Anti-Reflection Coating On ZnS for 8~12 µm Infrared Region

2020 ◽  
Vol 58 (6) ◽  
pp. 433-438
Author(s):  
Ill-Joo Lee ◽  
Seung-Chan Hong ◽  
Byung-Sam Kim ◽  
Jae-Kyung Cheon
Keyword(s):  
Vision System ◽  
Single Layer ◽  
Cost Effective ◽  
Autonomous Driving ◽  
Infrared Region ◽  
Substrate Material ◽  
Night Vision ◽  
High Price ◽  
Thermal Camera ◽  
Quarter Wavelength

Technologies for pedestrian safety are increasingly emphasized by Automakers in advance of autonomous driving vehicles. A Night Vision System attached behind the front grille can reduce fatal accidents, especially during the nighttime, however, consumers may hesitate to adopt such systems on account of their high price. High-cost Germanium is used in commercial Night Vision System windows, and therefore replacing it with a cheaper infrared window material can lead to a more affordable system. To achieve this, Zinc Sulfide (ZnS), which has about 70% transmittance in the Long-Wavelength Infrared region of 8~12 μm, was selected for the window substrate material. In this study, we designed, fabricated and characterized a single layer cost-effective anti-reflection coating on a ZnS window substrate using Calcium Fluoride (CaF2). The CaF2 coating was fabricated by E-beam evaporation technique, with Quarter wavelength anti-reflection thickness (QAR). It was characterized by FT-IR, SEM and a thermal camera test module. We found that CaF2 both side coated the ZnS window and exhibited about 10~15% higher transmittance than the ZnS window substrate. In addition the CaF2 coating stably bonded to the ZnS substrate without any internal defects. A thermal camera based window test also showed better detection performance with the CaF2 Coating than a bare ZnS substrate window, which was calculated using the output voltage of the microbolometer thermal sensor.

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