Read by QxMD icon Read

Photonic crystals

Hyunseok Kim, Wook-Jae Lee, Alan Cervantes Farrell, Juan S D Morales, Pradeep Nuwan Senanayake, Sergey V Prikhodko, Tomasz Ochalski, Diana L Huffaker
Chip-scale integrated light sources are a crucial component in a broad range of photonics applications. III-V semiconductor nanowire emitters have gained attention as a fascinating approach due to their superior material properties, extremely compact size, and the capability to grow directly on lattice-mismatched silicon substrates. Although there have been remarkable advances in nanowire-based emitters, their practical applications are still in the early stages due to the difficulties in integrating nanowire emitters with photonic integrated circuits...
May 23, 2017: Nano Letters
Sukarno, Cheryl Suwen Law, Abel Santos
We present the first realisation of linear variable bandpass filters in nanoporous anodic alumina (NAA-LVBPFs) photonic crystal structures. NAA gradient-index filters (NAA-GIFs) are produced by sinusoidal pulse anodisation and used as photonic crystal platforms to generate NAA-LVBPFs. The anodisation period of NAA-GIFs is modified from 650 to 850 s to systematically tune the characteristic photonic stopband of these photonic crystals across the UV-visible-NIR spectrum. Then, the nanoporous structure of NAA-GIFs is gradually widened along the surface under controlled conditions by wet chemical etching using a dip coating approach aiming to create NAA-LVBPFs with finely engineered optical properties...
May 23, 2017: Nanoscale
Noriyuki Suzuki, Eiji Iwase, Hiroaki Onoe
We herein report the micropatterning of flexible multiple photonic colloidal crystal gels (PCCGs) using single-layered microchannel. These patterned PCCGs exhibit structural colors that can be tuned by adjustment of the diameter and concentration of the colloidal particles in precursor solutions of N-isopropylacrylamide (NIPAM) or polyethylene glycol diacrylate (PEGDA). The precursor solutions containing dispersed colloidal particles were selectively injected into single-layered microchannels where they polymerized rapidly...
May 23, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Koki Imamura, Hiroyuki Yoshida, Masanori Ozaki
Liquid crystal (LC) micro-particles are functional materials possessing anisotropies of LCs originating from their inner molecular alignment, and are fabricated by polymerizing pre-aligned rod-like molecules in the LC state. Here we demonstrate field strength and frequency tunable two-way rotation control of LC micro-particles in a LC host, and unravel its mechanism by theoretically calculating the contributing free energies. Cuboid-shaped micro-particles with inner molecular alignment along the long axis are fabricated via two-photon excited direct laser writing, and dispersed in a dual-frequency (DF) LC to be electrically driven by a voltage applied in the in-plane direction of the cell...
May 22, 2017: Soft Matter
Shivaraj R Maidur, Parutagouda Shankaragouda Patil, Anusha Ekbote, Tze Shyang Chia, Ching Kheng Quah
In the present work, the title chalcone, (2E)-3-(4-fluorophenyl)-1-(4-{[(1E)-(4-fluorophenyl) methylene]amino}phenyl)prop-2-en-1-one (abbreviated as FAMFC), was synthesized and structurally characterized by single-crystal X-ray diffraction. The compound is crystallized in the monoclinic system with non-centrosymmetric space group P21 and hence it satisfies the essential condition for materials to exhibit second-order nonlinear optical properties. The molecular structure was further confirmed by using FT-IR and (1)H NMR spectroscopic techniques...
May 9, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Sina Saravi, Thomas Pertsch, Frank Setzpfandt
We propose the use of nonlinear periodic waveguides for direct and fully integrated generation of counterpropagating photon pairs by spontaneous parametric down-conversion. Using the unique properties of Bloch modes in such periodic structures, we furthermore show that two counterpropagating phase-matching conditions can be fulfilled simultaneously, allowing for the generation of path-entangled Bell states in a single periodic waveguide. To demonstrate the feasibility of our proposal, we design a photonic crystal slab waveguide made of lithium niobate and numerically demonstrate Bell-state generation...
May 5, 2017: Physical Review Letters
Lianzhou Wang
BiVO4 films with (040) facet grown vertically on fluorine doped SnO2 (FTO) glass substrates are prepared by a seed-assisted hydrothermal method. A simple electrochemical treatment process drastically enhances the photocatalytic activity of BiVO4, exhibiting a remarkable photocurrent density of 2.5 mA cm-2 at 1.23 V vs. reversible hydrogen electrode (RHE) under AM 1.5 G illumination, which is approximately 10 folds higher than that of the pristine one. Loading cobalt borate (CoBi) as cocatalyst, the photocurrent density of the BiVO4 photoanode can be further improved to 3...
May 17, 2017: Angewandte Chemie
Wenping Hu, Lingjie Sun Sun, Weigang Zhu Zhu, Wei Wang Wang, Fangxu Yang Yang, Congcong Zhang Zhang, Shufeng Wang Wang, Xiaotao Zhang Zhang, Rongjin Li, Huanli Dong
A new cocrystal of 4-Styrylpyridine and 1,2,4,5-Tetracyanobenzene has been successfully achieved through supramolecular self-assembly, in which the donor-acceptor interactions as the main self-assembly driving force contribute to the intermolecular charge transfer (ICT). Attractively, interesting two-photon absorption (TPA) properties are generated from the co-crystals which does not find in their individual single components. It is found that the TPA properties are originated from the ICT interactions in the D-A system...
May 15, 2017: Angewandte Chemie
Kai-Han Chang, Vinay Joshi, Liang-Chy Chien
We demonstrate a fast-switching liquid-crystal mode with polymer-sustained twisted vertical alignment. By optimizing the polymerization condition, a polymer microstructure with controlled orientation is produced. The polymer microstructure not only synergistically suppresses the optical bounce during field-induced homeotropic-twist transition but also shortens the response time significantly. Theoretical analyses validate that the ground state free energy density is modified by the aligning field of the polymer microstructure, which affects the driving voltage of the device...
April 2017: Physical Review. E
Yihui He, Oleg Y Kontsevoi, Constantinos C Stoumpos, Giancarlo Trimarchi, Saiful M Islam, Zhifu Liu, Svetlana S Kostina, Sanjib Das, Bruce W Wessels, Mercouri G Kanatzidis, Joon-Il Kim, Wenwen Lin
The high Z chalcohalides Hg3Q2I2 (Q = S, Se and Te) can be regarded as anti-perovskite structure with ordered vacancies and are demonstrated to be very promising candidates for X- and γ-ray semiconductor detectors. Depending on Q the ordering of the Hg vacancies in these defect anti-perovskites varies and yields a rich family of distinct crystal structures ranging from zero-dimensional to three-dimensional, with a dramatic effect on the properties of each compound. All three Hg3Q2I2 compounds show very suitable optical, electrical, and good mechanical properties required for radiation detection at room temperature...
May 15, 2017: Journal of the American Chemical Society
Wu Liu, Jintao Fan, Chen Xie, Youjian Song, Chenlin Gu, Lu Chai, Chingyue Wang, Minglie Hu
A digital micromirror device (DMD)-based arbitrary spectrum amplitude shaper is incorporated into a large-mode-area photonic crystal fiber laser cavity. The shaper acts as an in-cavity programmable filter and provides large tunable dispersion from normal to anomalous. As a result, mode-locking is achieved in different dispersion regimes with watt-level high output power. By programming different filter profiles on the DMD, the laser generates femtosecond pulse with a tunable central wavelength and controllable bandwidth...
May 15, 2017: Optics Letters
Jingxing Shi, Michael E Pollard, Cesar A Angeles, Ruiqi Chen, J C Gates, M D B Charlton
Coupling between free space components and slab waveguides is a common requirement for integrated optical devices, and is typically achieved by end-fire or grating coupling. Power splitting and distribution requires additional components. Usually grating couplers are used in combination with MMI/Y-splitters to do this task. In this paper, we present a photonic crystal device which performs both tasks simultaneously and is able to couple light at normal incidence and near normal incidence. Our approach is scalable to large channel counts with little impact on device footprint...
May 12, 2017: Scientific Reports
Zongchen Liu, Irfan Ahmed, Garuma Abdisa, Zihai Jiang, Shuwei Fan, Hongxing Wang, Yanpeng Zhang
We report the generation of three-mode hybrid intensity-noise correlation and intensity-difference squeezing of spontaneous parametric four-wave mixing (SP-FWM) and fourth-order fluorescence (FL) signals in the heteronuclear-like (three-level Λ-type) molecular structure of a Pr(3+):Y2SiO5 (Pr(3+):YSO) crystal using the nonlinear cross-Kerr effect under a polarized dressing effect. In the semi-classical view of a Kerr nonlinear medium, the amplitude of two-mode hybrid correlations of this kind is subject to a limit determined by the hybrid maximally entangled state...
May 11, 2017: Scientific Reports
Sungwook Jung, Joonhyuck Park, Jiwon Bang, Jae-Yeol Kim, Cheolhee Kim, Yongmoon Jeon, Seung Hwan Lee, Ho Jin, Sukyung Choi, Bomi Kim, Woo Jin Lee, Chan-Gi Pack, Jong-Bong Lee, Nam Ki Lee, Sungjee Kim
Photo-switching or modulation of quantum dots (QDs) can be promising for many fields that include display, memory, and super-resolution imaging. However, such modulations have been mostly relied on photo-modulations of conjugated molecules in QD vicinity which typically require high power of high energy photons at UV. We report a visible light-induced facile modulation route for QD-dye conjugates. QD crystal violets conjugates (QD-CVs) were prepared and the crystal violet (CV) molecules on QD quenched the fluorescence efficiently...
May 11, 2017: Journal of the American Chemical Society
Hongyan Zhang, Jie Lv, Zhenhong Jia
A novel assembled biosensor was prepared for detecting 16S rRNA, a small-size persistent specific for Actinobacteria. The mechanism of the porous silicon (PS) photonic crystal biosensor is based on the fluorescence resonance energy transfer (FRET) between quantum dots (QDs) and gold nanoparticles (AuNPs) through DNA hybridization, where QDs act as an emission donor and AuNPs serve as a fluorescence quencher. Results showed that the photoluminescence (PL) intensity of PS photonic crystal was drastically increased when the QDs-conjugated probe DNA was adhered to the PS layer by surface modification using a standard cross-link chemistry method...
May 10, 2017: Sensors
Xianming Kong, Erwen Li, Kenny Squire, Ye Liu, Bo Wu, Li-Jing Cheng, Alan X Wang
Diatomite consists of fossilized remains of ancient diatoms and is a type of naturally abundant photonic crystal biosilica with multiple unique physical and chemical functionalities. In this paper, we explored the fluidic properties of diatomite as the matrix for on-chip chromatography and, simultaneously, the photonic crystal effects to enhance the plasmonic resonances of metallic nanoparticles for surface-enhanced Raman scattering (SERS) biosensing. The plasmonic nanoparticle-decorated diatomite biosilica provides a lab-on-a-chip capability to separate and detect small molecules from mixture samples with ultra-high detection sensitivity down to 1 ppm...
May 9, 2017: Journal of Biophotonics
Huimin Zhu, Mingao Pan, Malin B Johansson, Erik Johansson
In this report a lead-free silver-bismuth-iodide (AgI:BiI3) with a crystal structure with space group R3m is investigated for use in solar cells. Devices based on the silver-bismuth-iodide deposited from solution on top of TiO2, and the conducting polymer P3HT as a hole transport layer, are prepared and the photovoltaic performance is very promising with a power conversion efficiency over 2 %, which is higher than the performance of previously reported bismuth-halide materials for solar cells. Photocurrent generation is observed between 350 and 700 nm, and the maximum external quantum efficiency is around 45 %...
May 8, 2017: ChemSusChem
Huadong Chen, Rong Lou, Yanxiao Chen, Lili Chen, Jingya Lu, Qianqian Dong
Photonic crystal (PC) materials exhibit unique structural colors that originate from their intrinsic photonic band gap. Because of their highly ordered structure and distinct optical characteristics, PC-based biomaterials have advantages in the multiplex detection, biomolecular screening and real-time monitoring of biomolecules. In addition, PCs provide good platforms for drug loading and biomolecule modification, which could be applied to biosensors and biological carriers. A number of methods are now available to fabricate PC materials with variable structure colors, which could be applied in biomedicine...
November 2017: Drug Delivery
Yuxian Zhang, Weidong Zhao, Jiahui Wen, Jinming Li, Zhou Yang, Dong Wang, Hui Cao, Maohua Quan
A new type of electric- or thermal-responsive multilayer device composed of SiO2 bilayer inverse opal (IOP) and chiral nematic liquid crystals (N*LCs) was developed. Bilayer IOP was fabricated by layer-by-layer assembly of polystyrene (PS) spheres with two different sizes and showed a reflectance in an extended range of the near-infrared region. Furthermore, the electrically or thermally tunable reflectance of the bilayer-IOP-N*LC device was investigated. The device exhibited the photonic bandgap (PBG) of the N*LC-IOP composite structure with the application of an electric field (voltage-on), while it presented the reflectance of N*LCs without an electric field (voltage-off) and the electrically-responsive behaviour could be reversibly switched...
May 21, 2017: Physical Chemistry Chemical Physics: PCCP
Nikhil Parappurath, Filippo Alpeggiani, L Kuipers, Ewold Verhagen
We observe that the asymmetric transmission (AT) through photonic systems with a resonant chiral response is strongly related to the far-field properties of eigenmodes of the system. This understanding can be used to predict the AT for any resonant system from its complex eigenmodes. We find that the resonant chiral phenomenon of AT is related to, and is bounded by, the nonresonant scattering properties of the system. Using the principle of reciprocity, we determine a fundamental limit to the maximum AT possible for a single mode in any chiral resonator...
April 19, 2017: ACS Photonics
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"