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Photonic crystals

Na Sai, Yuntang Wu, Guangui Yu, Zhong Sun, Guowei Huang
A novel photonic crystal (PC) for the enrichment and detection of trace chloramphenicol (Cm) was constructed based on the combination of the imprinted crystalline colloidal array (ICCA) and the enrichment effect induced by wettability differences. The enrichment ICCA (E-ICCA) material had a highly ordered opal structure consisted of hydrophilic molecular imprinting polymer (MIP) spheres and the surrounding hydrophobic polydimethylsiloxane (PDMS) matrix, thus showing the desired structural color but also possessing the large hydrophilicity/hydrophobicity (HP) interaction area to enable efficient enrichment of the target Cm molecules from a highly dilute solution to the MIP sphere surface...
December 1, 2016: Talanta
Abel Santos, Cheryl Suwen Law, Dominique Wong Chin Lei, Taj Pereira, Dusan Losic
In this study, we present an advanced nanofabrication approach to produce gradient-index photonic crystal structures based on nanoporous anodic alumina. An apodization strategy is for the first time applied to a sinusoidal pulse anodisation process in order to engineer the photonic stop band of nanoporous anodic alumina (NAA) in depth. Four apodization functions are explored, including linear positive, linear negative, logarithmic positive and logarithmic negative, with the aim of finely tuning the characteristic photonic stop band of these photonic crystal structures...
October 21, 2016: Nanoscale
Nobuo Kimizuka, Nobuhiro Yanai, Masa-Aki Morikawa
Self-assembly of functional molecules into ordered molecular assemblies and fulfillment of potentials unique to their nano-to-mesoscopic structures have been one of the central challenges in chemistry. This Feature Article provides an overview of recent progress in the field of molecular self-assembly with the focus on the triplet-triplet annihilation-based photon upconversion (TTA-UC) and supramolecular storage of photon energy. Based on the integration of molecular self-assembly and photon energy harvesting, triplet energy migration-based TTA-UC has been achieved in varied molecular systems...
October 19, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Andreas Vetter, Simone Ferrari, Patrik Rath, Rasoul Alaee, Oliver Kahl, Vadim Kovalyuk, Silvia Diewald, Gregory N Goltsman, Alexander Korneev, Carsten Rockstuhl, Wolfram Hp Pernice
Ultrafast single-photon detectors with high efficiency are of utmost importance for many applications in the context of integrated quantum photonic circuits. Detectors based on superconductor nanowires attached to optical waveguides are particularly appealing for this purpose. However, their speed is limited because the required high absorption efficiency necessitates long nanowires deposited on top of the waveguide. This enhances the kinetic inductance and makes the detectors slow. Here, we solve this problem by aligning the nanowire, contrary to usual choice, perpendicular to the waveguide to realize devices with a length below 1 µm...
October 19, 2016: Nano Letters
Jin-Hui Wu, M Artoni, G C La Rocca
In optical experiments one-sided reflectionless (ORL) and coherent perfect absorption (CPA) are unusual scattering properties yet fascinating for their fundamental aspects and for their practical interest. Although these two concepts have so far remained separated from each other, we prove that the two phenomena are indeed strictly connected. We show that a CPA-ORL connection exists between pairs of points lying along lines close to each other in the 3D space-parameters of a realistic lossy atomic photonic crystal...
October 19, 2016: Scientific Reports
Annabel Mikosch, Sibel Ciftci, Alexander J C Kuehne
The potential of colloidal crystals for applications in optics and photonics has been recognized since the description of spontaneous self-assembly of monodisperse colloids into periodic opaline geometries. Provided with a laser gain medium, these direct assemblies generate optical feedback and have prospective use as lasers, frequency converters and optical transistors; however, problems associated with crystal integrity and low loading capacities for the gain medium have pre-vented their realization to date...
October 18, 2016: ACS Nano
M Pang, W He, P St J Russell
We report a Tm-doped soliton fiber laser passively mode-locked by intense optoacoustic interactions in a short length of solid-core silica photonic crystal fiber (PCF) with a nanobore in core-center. A repetition rate of 1.446 GHz pulse is achieved, corresponding to the 52nd harmonic of the 27.8 MHz cavity round-trip frequency. Strong optoacoustic interactions in this PCF-based, Tm-doped fiber laser ensure stable and repeatable gigahertz-rate pulse train generation at 1.85 μm wavelength, with a high supermode noise suppression ratio and low pulse timing jitter...
October 1, 2016: Optics Letters
Alexei Smolyaninov, Mu-Han Yang, Lin Pang, Yeshaiahu Fainman
A high-density array of plasmonic coaxial nanoantennas is used to enhance the two-photon absorption (TPA) process in a conventional silicon photodetector from a mode-locked 76 MHz Ti:sapphire laser over a spectral range from 1340 to 1550 nm. This enhanced TPA was used to generate an interferometric autocorrelation trace of a 150 fs laser pulse. Unlike second-harmonic generation, this technique does not require phase matching or a bulky crystal and can be used on a low-cost integrated silicon platform over a wide range of near-IR wavelengths compatible with modern commercial tunable femtosecond sources...
October 1, 2016: Optics Letters
H Kim, C-T Chen, N Eclov, A Ronzhin, P Murat, E Ramberg, S Los, C-M Kao
A strip-line and waveform sampling based readout is a signal multiplexing method that can efficiently reduce the readout channels while fully exploiting the fast time characteristics of photo-detectors such as the SiPM. We have applied this readout method for SiPM-based time-of-flight (TOF) positron emission tomography (PET) detectors. We have prototyped strip-line boards in which 8 SiPMs (pitch 5.2 mm) are connected by using a single strip-line, and the signals appearing at the ends of the strip-line are acquired by using the DRS4 waveform sampler at a nominal sampling frequency of 1-5 GS/s...
September 11, 2016: Nuclear Instruments & Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment
Haiyang Wang, Xin Yan, Shuguang Li, Guowen An, Xuenan Zhang
A refractive index sensor based on dual-core photonic crystal fiber (PCF) with hexagonal lattice is proposed. The effects of geometrical parameters of the PCF on performances of the sensor are investigated by using the finite element method (FEM). Two fiber cores are separated by two air holes filled with the analyte whose refractive index is in the range of 1.33-1.41. Numerical simulation results show that the highest sensitivity can be up to 22,983 nm/RIU(refractive index unit) when the analyte refractive index is 1...
October 8, 2016: Sensors
M V Rasna, K P Zuhail, U V Ramudu, R Chandrasekar, Surajit Dhara
We study the dynamics of electric field driven multiaxis electro-orientation of birefringent microsheets in both the isotropic and nematic phases of a liquid crystal. For a fixed direction of applied field in the isotropic phase, there are two critical fields above which the microsheets show two orientations. In the nematic phase, it shows three rotations in both planar and homeotropic cells. These orientations are observed at varying voltages and wide time scales and are explained based on the competing effect of the electric, elastic, and viscous torques...
September 2016: Physical Review. E
Na Li, Xiuhong Li, Yuzhu Wang, Guangfeng Liu, Ping Zhou, Hongjin Wu, Chunxia Hong, Fenggang Bian, Rongguang Zhang
The beamline BL19U2 is located in the Shanghai Synchrotron Radiation Facility (SSRF) and is its first beamline dedicated to biological material small-angle X-ray scattering (BioSAXS). The electrons come from an undulator which can provide high brilliance for the BL19U2 end stations. A double flat silicon crystal (111) monochromator is used in BL19U2, with a tunable monochromatic photon energy ranging from 7 to 15 keV. To meet the rapidly growing demands of crystallographers, biochemists and structural biologists, the BioSAXS beamline allows manual and automatic sample loading/unloading...
October 1, 2016: Journal of Applied Crystallography
A Sipahigil, R E Evans, D D Sukachev, M J Burek, J Borregaard, M K Bhaskar, C T Nguyen, J L Pacheco, H A Atikian, C Meuwly, R M Camacho, F Jelezko, E Bielejec, H Park, M Lončar, M D Lukin
Efficient interfaces between photons and quantum emitters form the basis for quantum networks and enable optical nonlinearities at the single-photon level. We demonstrate an integrated platform for scalable quantum nanophotonics based on silicon-vacancy (SiV) color centers coupled to diamond nanodevices. By placing SiV centers inside diamond photonic crystal cavities, we realize a quantum-optical switch controlled by a single color center. We control the switch using SiV metastable states and observe optical switching at the single-photon level...
October 13, 2016: Science
Kyosuke Sakai, Kensuke Nomura, Takeaki Yamamoto, Tatsuya Omura, Keiji Sasaki
We report a scheme to exploit low radiative loss plasmonic resonance by combining a dark (subradiant) mode and a lattice resonance. We theoretically demonstrate that such dark-mode lattice resonances in periodic arrays of nanodisks or plasmonic crystals can be excited by vertically incident light beams. We investigate the excitation of lattice resonances in a finite sized, square-lattice plasmonic crystal by two types of cylindrical vector beams and a linearly polarized Gaussian beam. Quadrupole lattice resonances are excited by all three beams, and the largest peak intensity is obtained by using a specific type of cylindrical vector beam...
October 13, 2016: Scientific Reports
Ekaterina Rostova, Carine Ben Adiba, Giovanni Dietler, Sergey K Sekatskii
Optical biosensors based on photonic crystal surface waves (PC SWs) offer a possibility to study binding interactions with living cells, overcoming the limitation of rather small evanescent field penetration depth into a sample medium that is characteristic for typical optical biosensors. Besides this, simultaneous excitation of s- and p-polarized surface waves with different penetration depths is realized here, permitting unambiguous separation of surface and volume contributions to the measured signal. PC-based biosensors do not require a bulk signal correction, compared to widely used surface plasmon resonance-based devices...
October 11, 2016: Biosensors
Xiaofang Li, Changqian Wang, Bo Li, Yu Shao, Danzhen Li
Efficient light harvesting was observed over CdS photodeposited on In2O3 photonic crystals during the photocatalytic hydrogenation of 4-nitroaniline to p-phenylenediamine. The highest conversion of 4-nitroaniline and selectivity of p-phenylenediamine over the In2O3 photonic crystal supported CdS were ∼93% and ∼99%, respectively, which were better than that achieved for commercial hexagonal CdS. The existence of the photonic crystal structure was responsible for the higher efficiency of In2O3 photonic crystal supported CdS...
October 12, 2016: Physical Chemistry Chemical Physics: PCCP
Sejeong Kim, Hyojin Ko, Chulwon Lee, MinKwan Kim, Ki Soo Kim, Yong-Hee Lee, Kwanwoo Shin, Yong-Hoon Cho
Direct integration of semiconductor photonic nanocavities with paper substrates is demonstrated for the first time. 1D photonic crystal nanocavities successfully show lasing action on paper substrates. The device has great synergy as a sensor because paper has good wicking ability while a photonic crystal cavity has high figure of merit. The research provides a platform for eco-friendly and sustainable devices.
September 22, 2016: Advanced Materials
Li Tao, Henry M Daghighian, Craig S Levin
Using conventional scintillation detection, the fundamental limit in positron emission tomography (PET) time resolution is strongly dependent on the inherent temporal variances generated during the scintillation process, yielding an intrinsic physical limit for the coincidence time resolution of around 100 ps. On the other hand, modulation mechanisms of the optical properties of a material exploited in the optical telecommunications industry can be orders of magnitude faster. In this paper we borrow from the concept of optics pump-probe measurement to for the first time study whether ionizing radiation can produce modulations of optical properties, which can be utilized as a novel method for radiation detection...
October 7, 2016: Physics in Medicine and Biology
L Witthauer, M Dieterle, S Abt, P Achenbach, F Afzal, Z Ahmed, J R M Annand, H J Arends, M Bashkanov, R Beck, M Biroth, N S Borisov, A Braghieri, W J Briscoe, F Cividini, S Costanza, C Collicott, A Denig, E J Downie, P Drexler, M I Ferretti-Bondy, S Gardner, S Garni, D I Glazier, D Glowa, W Gradl, M Günther, G M Gurevich, D Hamilton, D Hornidge, G M Huber, A Käser, V L Kashevarov, S Kay, I Keshelashvili, R Kondratiev, M Korolija, B Krusche, A B Lazarev, J M Linturi, V Lisin, K Livingston, S Lutterer, I J D MacGregor, J Mancell, D M Manley, P P Martel, V Metag, W Meyer, R Miskimen, E Mornacchi, A Mushkarenkov, A B Neganov, A Neiser, M Oberle, M Ostrick, P B Otte, D Paudyal, P Pedroni, A Polonski, S N Prakhov, A Rajabi, G Reicherz, G Ron, T Rostomyan, A Sarty, C Sfienti, M H Sikora, V Sokhoyan, K Spieker, O Steffen, I I Strakovski, Th Strub, I Supek, A Thiel, M Thiel, A Thomas, M Unverzagt, Yu A Usov, S Wagner, N K Walford, D P Watts, D Werthmüller, J Wettig, M Wolfes, L Zana
The double polarization observable E and the helicity dependent cross sections σ_{1/2} and σ_{3/2} were measured for η photoproduction from quasifree protons and neutrons. The circularly polarized tagged photon beam of the A2 experiment at the Mainz MAMI accelerator was used in combination with a longitudinally polarized deuterated butanol target. The almost 4π detector setup of the Crystal Ball and TAPS is ideally suited to detect the recoil nucleons and the decay photons from η→2γ and η→3π^{0}...
September 23, 2016: Physical Review Letters
H L Sørensen, J-B Béguin, K W Kluge, I Iakoupov, A S Sørensen, J H Müller, E S Polzik, J Appel
We present the first experimental realization of coherent Bragg scattering off a one-dimensional system-two strings of atoms strongly coupled to a single photonic mode-realized by trapping atoms in the evanescent field of a tapered optical fiber, which also guides the probe light. We report nearly 12% power reflection from strings containing only about 1000 cesium atoms, an enhancement of 2 orders of magnitude compared to reflection from randomly positioned atoms. This result paves the road towards collective strong coupling in 1D atom-photon systems...
September 23, 2016: Physical Review Letters
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