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Photonic crystals

Rikizo Ikuta, Toshiki Kobayashi, Tetsuo Kawakami, Shigehito Miki, Masahiro Yabuno, Taro Yamashita, Hirotaka Terai, Masato Koashi, Tetsuya Mukai, Takashi Yamamoto, Nobuyuki Imoto
Long-lifetime quantum storages accessible to the telecom photonic infrastructure are essential to long-distance quantum communication. Atomic quantum storages have achieved subsecond storage time corresponding to 1000 km transmission time for a telecom photon through a quantum repeater algorithm. However, the telecom photon cannot be directly interfaced to typical atomic storages. Solid-state quantum frequency conversions fill this wavelength gap. Here we report on the experimental demonstration of a polarization-insensitive solid-state quantum frequency conversion to a telecom photon from a short-wavelength photon entangled with an atomic ensemble...
May 21, 2018: Nature Communications
Soshu Kirihara, Koki Nonaka, Shoichiro Kisanuki, Hirotoshi Nozaki, Keito Sakaguchi
Three-dimensional (3D) microphotonic crystals with a diamond structure composed of titania microlattices were fabricated using ultraviolet laser lithography, and the bandgap properties in the terahertz (THz) electromagnetic-wave frequency region were investigated. An acrylic resin paste with titania fine particle dispersions was used as the raw material for additive manufacturing. By scanning a spread paste surface with an ultraviolet laser beam, two-dimensional solid patterns were dewaxed and sintered. Subsequently, 3D structures with a relative density of 97% were created via layer lamination and joining...
May 18, 2018: Materials
Lei Zhang, Nadiia Pasthukova, Yifan Yao, Xiaolan Zhong, Egon Pavlica, Gvido Bratina, Emanuele Orgiu, Paolo Samorì
Self-standing nanostructures are of fundamental interest in materials science and nanoscience and are widely used in (opto-)electronic and photonic devices as well as in micro-electromechanical systems. To date, large-area and self-standing nanoelectrode arrays assembled on flexible substrates have not been reported. Here the fabrication of a hollow nanomesh scaffold on glass and plastic substrates with a large surface area over 1 mm2 and ultralow leakage current density (≈1-10 pA mm-2 @ 2 V) across the empty scaffold is demonstrated...
May 21, 2018: Advanced Materials
Xiang Xi, Mi Lin, Wenbiao Qiu, Zhengbiao Ouyang, Qiong Wang, Qiang Liu
We propose a type of polarization-independent circulator based on ferrite and plasma materials in a two-dimensional photonic crystal (PhC) slab. First, on the basis of analyzing the wave equations in ferrite and plasma materials, TE and TM circulators are realized with ferrite and plasma in PhCs, respectively. Then, by properly combining these two types of circulators together, a polarization-independent circulator is achieved and investigated. The results show that, for both polarizations, the insertion loss and isolation for the polarization-independent circulator are less than 0...
May 18, 2018: Scientific Reports
Yiwen Zhang, Ang Chen, Wenzhe Liu, Chia Wei Hsu, Bo Wang, Fang Guan, Xiaohan Liu, Lei Shi, Ling Lu, Jian Zi
The vortex, a fundamental topological excitation featuring the in-plane winding of a vector field, is important in various areas such as fluid dynamics, liquid crystals, and superconductors. Although commonly existing in nature, vortices were observed exclusively in real space. Here, we experimentally observed momentum-space vortices as the winding of far-field polarization vectors in the first Brillouin zone of periodic plasmonic structures. Using homemade polarization-resolved momentum-space imaging spectroscopy, we mapped out the dispersion, lifetime, and polarization of all radiative states at the visible wavelengths...
May 4, 2018: Physical Review Letters
Debarghya Sarkar, Wei Wang, Matthew Mecklenburg, Andrew J Clough, Matthew Yeung, Chenhao Ren, Qingfeng Lin, Louis Blankemeier, Shanyuan Niu, Huan Zhao, Haotian Shi, Han Wang, Stephen B Cronin, Jayakanth Ravichandran, Mitul Luhar, Rehan Kapadia
The growth of crystalline compound semiconductors on amorphous and non-epitaxial substrates is a fundamental challenge for state-of-the-art thin-film epitaxial growth techniques. Direct growth of materials on technologically relevant amorphous surfaces, such as nitrides or oxides results in nanocrystalline thin-films, or nanowire type structures, preventing growth and integration of high-performance devices and circuits on these surfaces. Here we show crystalline compound semiconductors grown directly on technologically relevant amorphous and non-epitaxial substrates in geometries compatible with standard microfabrication technology...
May 18, 2018: ACS Nano
Wanjie Ren, Meng Qin, Xiaotian Hu, Fengyu Li, Yuanfeng Wang, Yu Huang, Meng Su, Wenbo Li, Xin Qian, Kang-Lai Tang, Yanlin Song
Benefiting from the integrated functions of cilia and glomeruli in the olfactory system, animals can discriminate various odors even in hostile environments. Inspired by this synergetic system of response and signal processing units, a sensor chip of graphene oxide (GO) and photonic crystals (PCs) is fabricated. The GO aerogel functions like the olfactory cilia, which effectively captures the analytes and generates abundant sensing signals for recognition; and the PCs act as the olfactory glomeruli, whose periodic structure enables selective enhancement of the fluorescent signals to realize further signal processing...
May 21, 2018: Analytical Chemistry
Gönül Yavuz, Andrea Zille, Necdet Seventekin, Antonio P Souto
The structural coloration of a chitosan-coated woven cotton fabric obtained by glutaraldehyde-stabilized deposition of electrostatic self-assembled monodisperse and spherically uniform (250 nm) poly (styrene-methyl methacrylate-acrylic acid) photonic crystal nanospheres (P(St-MMA-AA)) was investigated. Bright iridescent coatings displaying different colors in function of the viewing angle were obtained. The SEM, diffuse reflectance spectroscopy, TGA, DSC and FTIR analyses confirm the presence of structural color and the glutaraldehyde and chitosan ability to provide durable chemical bonding between cotton fabric and photonic crystal (PCs) coating with the highest degradation temperature and the lowest enthalpy...
August 1, 2018: Carbohydrate Polymers
Yunfeng Wang, Wenfei Zhang, Chao-Nan Lin, Pengpeng Ren, Ying-Jie Lu, Chongxin Shan, Siu Fung Yu
Room-temperature up-conversion emission up to eight-photon absorption is demonstrated from diamond single crystals under femtosecond laser excitation for the first time. The low concentration of defects and impurities is attributed to the support of free excitons emission at 235 nm. Nonlinear optical properties are also investigated by using an open aperture Z-scan technique. The corresponding three-, five- and eight-photon absorption coefficients of the diamonds are found to be 1.8×10-2 cm3/GW2, 5×10-9 cm7/GW4 and 1...
May 17, 2018: ACS Applied Materials & Interfaces
F Boschi, F De Sanctis, S Ugel, A E Spinelli
Cancer immunotherapy is a promising strategy based on the ability of the immune system to kill selected cells. In the development of an effective T-cell therapy the non-invasive cell tracking methods play a crucial role. Here we investigate the potentialities of T-cell marked with radionuclides in order to detect their localization with imaging techniques in small animal rodents. A protocol to label T-cells with 32 P-ATP was tested and evaluated. The homing of 32 P-ATP labeled T lymphocytes was investigated by Cerenkov luminescence imaging and radioluminescence imaging The first approach relies on the acquisition of Cerenkov photons produced by the beta particles emitted by the 32 P internalized by lymphocytes; the second one on the detection of photons coming from the conversion of radioactive energy in light done by scintillator crystals layered on the animals...
May 16, 2018: Journal of Biophotonics
Astam K Patra, Biplab Banerjee, Asim Bhaumik
Semiconduction nanoparticles are intensively studied due to their huge potential in optoelctronic applications. Here we report an efficient chemical route for hydrothermal synthesis of aggregated mesoporous cadmium sulfide (CdS) nanoparticles using supramolecular-assembly of ionic and water soluble sodium salicylate as the capping agent. The nanostructure, mesophase, optical property and photoconductivity of these mesoporous CdS materials have been characterized by using small and wide angle powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2-sorption, Raman analysis, Fourier transformed infrared (FT-IR), UV-Visible DSR spectroscopy, and photoconductivity measurement...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Kenneth Squire, Xianming Kong, Paul LeDuff, Gregory L Rorrer, Alan X Wang
Fluorescence biosensing is one of the most established biosensing methods, particularly fluorescence spectroscopy and microscopy. These are two highly sensitive techniques but require high grade electronics and optics to achieve the desired sensitivity. Efforts have been made to implement these methods using consumer grade electronics and simple optical setups for applications such as point-of-care diagnostics, but the sensitivity inherently suffers. Sensing substrates, capable of enhancing fluorescence are thus needed to achieve high sensitivity for such applications...
May 16, 2018: Journal of Biophotonics
Hui Cai, Bin Chen, Mark Blei, Shery L Y Chang, Kedi Wu, Houlong Zhuang, Sefaattin Tongay
Akin to the enormous number of discoveries made through traditional semiconductor alloys, alloying selected 2D semiconductors enables engineering of their electronic structure for a wide range of new applications. 2D alloys have been demonstrated when two components crystallized in the same phase, and their bandgaps displayed predictable monotonic variation. By stabilizing previously unobserved compositions and phases of GaSe1-x Te x at nanoscales on GaAs(111), we demonstrate abnormal band bowing effects and phase instability region when components crystallize in different phases...
May 15, 2018: Nature Communications
Minhaeng Cho
Parametric down-conversion is a second-order nonlinear optical process annihilating a pump photon and creating a pair of photons in the signal and idler modes. Then, by using two parametric down-converters and introducing a path indistinguishability for the two generated idler modes, a quantum coherence between two conjugate signal beams can be induced. Such a double spontaneous or stimulated parametric down-conversion scheme has been used to demonstrate quantum spectroscopy and imaging with undetected idler photons via measuring one-photon interference between their correlated signal beams...
May 14, 2018: Journal of Chemical Physics
Xiaopeng Wang, Xingyu Liu, Cameron Cook, Bohdan Schatschneider, Noa Marom
Singlet fission (SF), the spontaneous down-conversion of a singlet exciton into two triplet excitons residing on neighboring molecules, is a promising route to improve organic photovoltaic (OPV) device efficiencies by harvesting two charge carriers from one photon. However, only a few materials have been discovered that exhibit intermolecular SF in the solid state, most of which are acene derivatives. Recently, there has been a growing interest in rylenes as potential SF materials. We use many-body perturbation theory in the GW approximation and the Bethe-Salpeter equation to investigate the possibility of intermolecular SF in crystalline perylene and quaterrylene...
May 14, 2018: Journal of Chemical Physics
Qiwei Xu, Seyed Milad Mahpeykar, Ian Burgess, Xihua Wang
Most of reported optofluidic devices analyze the liquid by measuring its refractive index. Recently, the wettability of liquid on various substrates has also been used as an important key sensing parameter in optofluidic sensors. However, the above-mentioned techniques face challenges in the analysis of relative concentration of components in an alkane hydrocarbon mixture, since both refractive indices and wettabilities of alkane hydrocarbons are very close. Here we propose to apply volatility of liquid as the key sensing parameter and correlate it to the optical property of liquid inside inverse opal photonic crystals and construct powerful optofluidic sensors for alkane hydrocarbon identification and analysis...
May 15, 2018: ACS Applied Materials & Interfaces
Jesús Daniel Valenzuela-Sau, Raúl García-Llamas
We calculated the out-of-plane band structure of a two-dimensional dispersive photonic crystal (PC). To achieve this goal, the plane wave expansion method was implemented in conjunction with a numerical algorithm, the dispersive photonic crystal iterative method. The PC is an array of circular cross-sectional dispersive MgO Lorentz single-pole rods in a square lattice. The frequency bands are calculated starting at Γ as a function of the oblique component of the wave vector. For the lowest frequencies, it was found that the modes bend drastically to the horizon as the dielectric constant ϵ(ω) is increased to a very positive value...
May 15, 2018: Optics Letters
Joshua W Cates, Craig S Levin
Commercially available clinical positron emission tomography (PET) detectors employ scintillation crystals that are long (20 mm length) and narrow (4-5 mm width) optically coupled on their narrow end to a photosensor. The aspect ratio of this traditional crystal rod conguration and 511 keV photon attenuation properties yield signicant variances in scintillation light collection efficiency and transit time to the photodetector, due to variations in the 511 keV photon interaction depth in the crystal. These variances contribute significantly to coincidence time resolution degradation...
May 15, 2018: Physics in Medicine and Biology
Saman Jahani, Sangsik Kim, Jonathan Atkinson, Justin C Wirth, Farid Kalhor, Abdullah Al Noman, Ward D Newman, Prashant Shekhar, Kyunghun Han, Vien Van, Raymond G DeCorby, Lukas Chrostowski, Minghao Qi, Zubin Jacob
Ultra-compact, densely integrated optical components manufactured on a CMOS-foundry platform are highly desirable for optical information processing and electronic-photonic co-integration. However, the large spatial extent of evanescent waves arising from nanoscale confinement, ubiquitous in silicon photonic devices, causes significant cross-talk and scattering loss. Here, we demonstrate that anisotropic all-dielectric metamaterials open a new degree of freedom in total internal reflection to shorten the decay length of evanescent waves...
May 14, 2018: Nature Communications
Xinran Dong, Haifeng Du, Xiaoyan Sun, Zhi Luo, Ji'an Duan
We have proposed a high sensitive photonic crystal fiber (PCF) strain sensor based on the Mach-Zehnder interferometer (MZI). The sensing head is formed by all-fiber in-line single mode-multimode-photonic-crystal-single mode fiber (SMPS) structure, using only the splicing method. Such a strain sensor exhibited a high sensitivity of -2.21 pm/με within a large measurement range of up to 5000 με and a large fringe visibility of up to 24 dB. Moreover, it was found that the strain sensitivity was weekly dependent of the length of PCF or MMF...
May 14, 2018: Sensors
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