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Shuai Wen, Yun Meng, Minghui Jiang, Yang Wang
Quickly switching among different states (levels) is crucial for reconfigurable metamaterials and devices. In this study, the dynamics of establishment and transformation of five amorphous or near-amorphous intermediate states with obvious optical contrasts on Ge2 Sb2 Te5 phase-change thin films driven by ultrashort laser pulses were investigated using real-time reflectivity measurements. The reversible coding-recoding among the five optical levels was realized by using single-shot picosecond laser pulses with designed fluences...
March 21, 2018: Scientific Reports
Andrea Castelli, Joost de Graaf, Sergio Marras, Rosaria Brescia, Luca Goldoni, Liberato Manna, Milena P Arciniegas
Colloidal nanocrystals can self-assemble into highly ordered superlattices. Recent studies have focused on changing their morphology by tuning the nanocrystal interactions via ligand-based surface modification for simple particle shapes. Here we demonstrate that this principle is transferable to and even enriched in the case of a class of branched nanocrystals made of a CdSe core and eight CdS pods, so-called octapods. Through careful experimental analysis, we show that the octapods have a heterogeneous ligand distribution, resembling a cone wrapping the individual pods...
March 20, 2018: Nature Communications
Andrea Knöller, Stefan Kilper, Achim Diem, Marc Widenmeyer, Tomce Runcevski, Robert E Dinnebier, Joachim Bill, Zaklina Burghard
The demand to outperform current technologies pushes scientists to develop novel strategies to enable fabricating materials with exceptional properties. Along this line, lightweight structural materials are of great interest due to their versatile applicability as sensors, catalysts, battery electrodes and acoustic or mechanical dampers. Here we report a strategy to design ultralight (ρ = 3 mg/cm3) and hierarchically structured ceramic scaffolds of macroscopic size. Such scaffolds exhibit mechanical reversibility comparable to that of microscopic metamaterials, leading to a macroscopically remarkable dynamic mechanical performance...
March 20, 2018: Nano Letters
Shinpei Ogawa, Masafumi Kimata
Electromagnetic wave absorbers have been investigated for many years with the aim of achieving high absorbance and tunability of both the absorption wavelength and the operation mode by geometrical control, small and thin absorber volume, and simple fabrication. There is particular interest in metal-insulator-metal-based plasmonic metamaterial absorbers (MIM-PMAs) due to their complete fulfillment of these demands. MIM-PMAs consist of top periodic micropatches, a middle dielectric layer, and a bottom reflector layer to generate strong localized surface plasmon resonance at absorption wavelengths...
March 20, 2018: Materials
Wei Jiang, Leilei Yan, Hua Ma, Ya Fan, Jiafu Wang, Mingde Feng, Shaobo Qu
Lightweight structures with multi-functions such as electromagnetic wave absorption and excellent mechanical properties are required in spacecraft. A three-dimensional metamaterial absorber consisting of honeycomb and resistive films was proposed and fabricated through 3D printing and silk-screen printing technology. According to simulation and experiment results, the present three-dimensional metamaterial absorber can realize an absorptivity of more than 90% in a wide band of 3.53-24.00 GHz, and improve absorbing efficiency for transverse magnetic (TM) waves of oblique incidence angle from 0° to 70°...
March 19, 2018: Scientific Reports
Arash Ahmadivand, Burak Gerislioglu, Asahi Tomitaka, Pandiaraj Manickam, Ajeet Kaushik, Shekhar Bhansali, Madhavan Nair, Nezih Pala
Engineered terahertz (THz) plasmonic metamaterials have emerged as promising platforms for quick infection diagnosis, cost-effective and real-time pharmacology applications owing to their non-destructive and harmless interaction with biological tissues in both in vivo and in vitro assays. As a recent member of THz metamaterials family, toroidal metamaterials have been demonstrated to be supporting high-quality sharp resonance modes. Here we introduce a THz metasensor based on a plasmonic surface consisting of metamolecules that support ultra-narrow toroidal resonances excited by the incident radiation and demonstrate detection of an ultralow concertation targeted biomarker...
February 1, 2018: Biomedical Optics Express
Thomas Mulkey, Jimmy Dillies, Maxim Durach
We formulate and solve the inverse problem of quartic photonics, or photonics of metamaterials, whose k-surfaces (also known as iso-frequency surfaces or Fresnel surfaces) are quartic surfaces. This provides an approach to engineer the effective parameters of metamaterials starting from the desired plane waves. We apply our method to the design of the high-k limit of metamaterials, extreme non-reciprocity, and complex bi-anisotropic media.
March 15, 2018: Optics Letters
Yang Shen, Jieqiu Zhang, Yongqiang Pang, Lin Zheng, Jiafu Wang, Hua Ma, Shaobo Qu
Distilled water has frequency dispersive characteristic and high value of imaginary part in permittivity, which can be seen as a good candidate of broadband metamaterial absorbers(MAs) in microwave. Here, an interesting idea based on the combination of water-substrate and metallic metamaterial in the three-dimensional construction is proposed, which can achieve outstanding broadband absorption. As a proof, the distilled water is filled into the dielectric reservoir as ultra-thin water-substrate, and then the water-substrates are arranged on the metal backplane periodically as three-dimensional water-substrate array(TWA)...
March 13, 2018: Scientific Reports
Devin Powell
No abstract text is available yet for this article.
March 13, 2018: Proceedings of the National Academy of Sciences of the United States of America
Hai Lin, Wenguo Zhu, Jianhui Yu, Mengjiang Jiang, Linqing Zhuo, Wentao Qiu, Jiangli Dong, Yongchun Zhong, Zhe Chen
The angular Goos-Hänchen shift of vortex beam is investigated theoretically when a Laguerre-Gaussian (LG) beam is reflected by an air-metamaterial interface. The upper limit of the angular GH shift is found to be half of the divergence angle of the incident beam, i.e., |Θup| = (|ℓ| + 1)1/2 /k0 w0 , with ℓ, k0 , and w0 being the vortex charge, wavenumber in vacuum, and beam waist, respectively. Interestingly, the upper limited angular GH shift is accompanied by the upper-limited spatial IF shift. A parameter F is introduced to compare the total beam shift with the beam size...
March 5, 2018: Optics Express
Jing Wang, Hao Tian, Yu Wang, Xueyan Li, Yujie Cao, Li Li, Jianlong Liu, Zhongxiang Zhou
An electrically tunable terahertz (THz) modulator with large modulation depth and low insertion loss is performed with liquid crystal (LC) metamaterial. The modulation depth beyond 90% and insertion loss below 0.5 dB are achievable at normal incidence by exploiting plasmon-induced transparency (PIT) effect. The PIT spectra can be manipulated by actively controlling the interference between dipole mode and nonlocal surface-Bloch mode with LC. The incident angle tuning effect on PIT spectra shows that the large modulation depth and low insertion loss can remain over a wide range of working angles...
March 5, 2018: Optics Express
Lei Lei, Shun Li, Haixuan Huang, Keyu Tao, Ping Xu
We propose a design of an ultra-broadband absorber based on a thin metamaterial nanostructure composed of a periodic array of titanium-silica (Ti-SiO2 ) cubes and an aluminum (Al) bottom film. The proposed structure can achieve nearly perfect absorption with an average absorbance of 97% spanning a broad range from visible to near-infrared (i.e., from 354 nm to 1066 nm), showing a 90% absorption bandwidth over 712 nm, and the peak absorption is up to 99.8%. The excitation of superior surface plasmon resonance combined with the resonance induced by the metal-insulator-metal Fabry-Perot (FP) cavity leads to this broadband perfect absorption...
March 5, 2018: Optics Express
Shinpei Ogawa, Masaaki Shimatani, Shoichiro Fukushima, Satoshi Okuda, Kazuhiko Matsumoto
Metal-insulator-metal-based plasmonic metamaterial absorbers (MIM-PMAs) generate strong localized surface plasmon resonance (LSPR) on their surfaces. Therefore, MIM-PMAs are expected to enhance the absorption of graphene coated on their surfaces. Graphene-coated MIM-PMAs (GMIM-PMAs) were developed and their optical properties were investigated both experimentally and numerically at infrared wavelengths. Significant modification of the absorption of GMIM-PMAs was achieved only in the main LSPR wavelength region, where the insulator is lossless...
March 5, 2018: Optics Express
Zhigang Li, Liliana Stan, David A Czaplewski, Xiaodong Yang, Jie Gao
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...
March 5, 2018: Optics Express
Xianglian Song, Zizhuo Liu, Yuanjiang Xiang, Koray Aydin
Most of hyperbolic metamaterials (HMMs) investigated to date are based on isotropic materials resulting in uniaxial HMMs in which dielectric permittivities perpendicular to the propagation direction are the same. Using an anisotropic material constituent to form a HMM is a promising research direction providing opportunities to control the dielectric permittivity in all three directions independently. Herein, we propose and theoretically demonstrate novel biaxial HMMs composed of multilayer stacks of few-layer black phosphorus (BP) and Au thin films...
March 5, 2018: Optics Express
Miller Eaton, Alessandra Catellani, Arrigo Calzolari
VO2 is a unique phase change material with strongly anisotropic electronic properties. Recently, samples have been prepared that present a co-existence of phases and thus form metal-insulator junctions of the same chemical compound. Using first principles calculations, the optical properties of metallic and semiconducting VO2 are here discussed to design self-contained natural optical metamaterials, avoiding coupling with other dielectric media. The analysis of the optical properties complements the experiments in the description of the vast change in reflectance and metallicity for both disordered and planar compounds...
March 5, 2018: Optics Express
Okan Yurduseven, Daniel L Marks, Thomas Fromenteze, David R Smith
We present a reconfigurable, dynamic beam steering holographic metasurface aperture to synthesize a microwave camera at K-band frequencies. The aperture consists of a 1D printed microstrip transmission line with the front surface patterned into an array of slot-shaped subwavelength metamaterial elements (or meta-elements) dynamically tuned between "ON" and "OFF" states using PIN diodes. The proposed aperture synthesizes a desired radiation pattern by converting the waveguide-mode to a free space radiation by means of a binary modulation scheme...
March 5, 2018: Optics Express
Zohreh Vafapour
Recently reported metamaterial (MM) analogs of electromagnetically induced reflectance (EIR) enable a unique route to endow classical optical structures with aspects of quantum optical systems. This method opens up many fascinating prospects on novel optical components, such as slow light units, highly sensitive sensors, and nonlinear devices. Here we designed and simulated a microwave MM made from aluminum thin film to mimic the EIR system. High reflectance of about 99 percent and also a large group index at the reflectance window of about 243 are demonstrated, which mainly arise from the enhanced coupling between radiative and nonradiative elements...
March 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Hailong Huang, Hui Xia, Wenke Xie, Zhibo Guo, Hongjian Li, Ding Xie
In this paper, a tunable broadband metamaterial absorber (MA) based on graphene is investigated theoretically and numerically at mid-infrared regions. Compared with the previously reported multiband graphene-based MAs, a broad bandwidth of 11.7 THz with the absorption over 90% is obtained in the proposed MA, which is composed of a Jerusalem cross (JC) metal encrusting into the slot graphene layer in the top layer. The results show that the origin of broadband absorption is caused by coupling effect between metal and graphene, and this effect is explained by the two-mode waveguide coupling theory...
March 8, 2018: Scientific Reports
Hongbin Fang, Shih-Cheng A Chu, Yutong Xia, Kon Well Wang
Developing mechanical metamaterials with programmable properties is an emerging topic receiving wide attention. While the programmability mainly originates from structural multistability in previously designed metamaterials, here it is shown that nonflat-foldable origami provides a new platform to achieve programmability via its intrinsic self-locking and reconfiguration capabilities. Working with the single-collinear degree-4 vertex origami tessellation, it is found that each unit cell can self-lock at a nonflat configuration and, therefore, possesses wide design space to program its foldability and relative density...
March 7, 2018: Advanced Materials
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