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David R Thompson, Joseph W Boardman, Michael L Eastwood, Robert O Green
The intrinsic spectral dimensionality indicates the observable degrees of freedom in Earth's solar-reflected light field, quantifying the diversity of spectral content accessible by visible and infrared remote sensing. The solar-reflected regime spans the 0.38 - 2.5 μm interval, and is captured by a wide range of current and planned instruments on both airborne and orbital platforms. To date there has been no systematic study of its spectral dimensionality as a function of space, time, and land cover. Here we report a multi-site, multi-year statistical survey by NASA's "Classic" Airborne Visible Near InfraRed Spectrometer (AVIRIS-C)...
April 17, 2017: Optics Express
A Pospori, C A F Marques, O Bang, D J Webb, P André
We experimentally demonstrate the first polymer optical fiber Bragg grating inscribed with only one krypton fluoride laser pulse. The device has been recorded in a single-mode poly(methyl methacrylate) optical fiber, with a core doped with benzyl dimethyl ketal for photosensitivity enhancement. One laser pulse with a duration of 15 ns, which provide energy density of 974 mJ/cm<sup>2</sup>, is adequate to introduce a refractive index change of 0.74×10<sup>-4</sup> in the fiber core. After the exposure, the reflectivity of the grating increases for a few minutes following a second order exponential saturation...
April 17, 2017: Optics Express
Tianyu Tu, Fufei Pang, Shan Zhu, Jiajing Cheng, Huanhuan Liu, Jianxiang Wen, Tingyun Wang
We have theoretically and experimentally demonstrated a novel approach to excite Bloch surface wave (BSW) on tapered optical fibers, which are coated with one-dimensional photonic crystal (1DPC) consisting of periodic TiO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub> by atomic layer deposition technology. Two resonant dips are found in transmission spectra that are originated from the excitation of BSW for p-polarized light and s-polarized light, respectively. For the first time, we have demonstrated the developed device for refractive index (RI) sensing...
April 17, 2017: Optics Express
Abdul Khaleque, Evgeny G Mironov, Jonas H Osório, Ziyuan Li, Cristiano M B Cordeiro, Liming Liu, Marcos A R Franco, Jong-Leng Liow, Haroldo T Hattori
In this article, a new and flexible approach to control the electric field enhancement of bow-tie nano-antennas by integrating them on the lateral of a tapered optical fiber is proposed. The device is driven by a Q-switched laser and the performance of a fabricated nano-antenna in a quartz slide is tested by a Surface Enhanced Raman Scattering (SERS) experiment. A refractive index sensing experiment is also performed and a sensitivity of (240 ± 30) nm/RIU is found in the 1.33-1.35 index range.
April 17, 2017: Optics Express
Honghao Yu, Jun Chang, Xin Liu, Chuhan Wu, Yifan He, Yongjian Zhang
Herein, we propose a new security enhancing method that employs wavefront aberrations as optical keys to improve the resistance capabilities of conventional double-random phase encoding (DRPE) optical cryptosystems. This study has two main innovations. First, we exploit a special beam-expander afocal-reflecting to produce different types of aberrations, and the wavefront distortion can be altered by changing the shape of the afocal-reflecting system using a deformable mirror. Then, we reconstruct the wavefront aberrations via the surface fitting of Zernike polynomials and use the reconstructed aberrations as novel asymmetric vector keys...
April 17, 2017: Optics Express
Chen Wei, Hongyu Luo, Hongxia Shi, YanJia Lyu, Han Zhang, Yong Liu
In this paper, we demonstrate a wavelength widely tunable gain-switched Er<sup>3+</sup>-doped ZBLAN fiber laser around 2.8 μm. The laser can be tuned over 170 nm (2699 nm~2869.9 nm) for various pump power levels, while maintaining stable μs-level single-pulse gain-switched operation with controllable output pulse duration at a selectable repetition rate. To the best of our knowledge, this is the first wavelength tunable gain-switched fiber laser in the 3 μm spectral region with the broadest tuning range (doubling the record tuning range) of the pulsed fiber lasers around 3 μm...
April 17, 2017: Optics Express
Haritz Iribas, Alayn Loayssa, Florian Sauser, Miguel Llera, Sébastien Le Floch
We study the performance limits of mono-color cyclic coding applied to Brillouin optical time-domain analysis (BOTDA) sensors that use probe wave dithering. BOTDA analyzers with dithering of the probe use a dual-probe-sideband setup in which an optical frequency modulation of the probe waves along the fiber is introduced. This avoids non-local effects while keeping the Brillouin threshold at its highest level, thus preventing the spontaneous Brillouin scattering from generating noise in the deployed sensing fiber...
April 17, 2017: Optics Express
Xian Zhou, Yutang Dai, Joseph Muna Karanja, Fufei Liu, Minghong Yang
Hydrogen gas sensing properties of Pt-WO<sub>3</sub> films on spiral microstructured fiber Bragg grating (FBG) has been demonstrated. Pt-WO<sub>3</sub> film was prepared by hydrothermal method. The spiral microsturctured FBG was fabricated using femtosecond laser. Spiral microstructure FBG hydrogen sensor can detect hydrogen concentration from 0.02% H<sub>2</sub> to 4% H<sub>2</sub> at room temperature, and the response time is shortened from a few minutes to 10~30 s...
April 17, 2017: Optics Express
Borwen You, Ching-Yu Chen, Chin-Ping Yu, Tze-An Liu, Toshiaki Hattori, Ja-Yu Lu
A terahertz artificial material composed of metal rod array is experimentally investigated on its transmission spectral property and successfully incorporated into microfluidics as a miniaturized terahertz waveguide with an extended optical-path-length for label-free fluidic sensing. Theoretical and experimental characterizations of terahertz transmission spectra show that the wave guidance along the metal rod array originates from the resonance of transverse-electric-polarized waves within the metal rod slits...
April 17, 2017: Optics Express
Mengdi Lu, Wei Peng, Qiang Liu, Yun Liu, Lixia Li, Yuzhang Liang, Jean-Francois Masson
We present a novel multilayer-coated surface plasmon resonance sensor for dual refractive index range measurements based on a capillary structure. The sensing elements include an internally coated Ag layer and an externally coated bilayer of Au with an overlayer of thin indium tin oxide (ITO). The internal Ag layer was sensitive to higher refractive index (RI) medium while the external Au/ITO layer was sensitive to lower refractive index medium. We evaluated the sensor performance by measuring RI changes in two channels, RI sensitivities were -1951 nm/RIU and 2496 nm/RIU, respectively...
April 17, 2017: Optics Express
Benjamin Crooke, Lachlan I W McKinna, Ivona Cetinić
Fowler's Sneaker Depth (FSD), analogous to the well known Secchi disk depth (Zsd), is a visually discerned citizen scientist metric used to assess water clarity in the Patuxent River estuary. In this study, a simple remote sensing algorithm was developed to derive FSD from space-borne spectroradiometric imagery. An empirical model was formed that estimates FSD from red-end remote sensing reflectances at 645 nm, Rrs(645). The model is based on a hyperbolic function relating water clarity to Rrs(645) that was established using radiative transfer modeling and fine tuned using in-water FSD measurements and coincident Rrs(645) data observed by NASA's Moderate Resolution Imaging Spectroradiometer aboard the Aqua spacecraft (MODISA)...
April 17, 2017: Optics Express
Yongfeng Wu, Yundong Zhang, Jing Wu, Ping Yuan
We experimentally demonstrate transverse load and strain sensing based on a fiber optic Fabry-Perot interferometer (FPI) with special air cavity, which was created by fusion splicing single mode fiber (SMF), hollow core fiber (HCF) and several electrical arc discharges. The cavity height of this structure is higher than the cladding diameter of SMF so that it can sense transverse load with high sensitivity. The transverse load sensitivity of this air cavity FPI sensor is 1.31 nm∕N and about 5 times more sensitive compared to the current fiber tip interferometer (0...
April 17, 2017: Optics Express
J Ma, H H Yu, X Jiang, D S Jiang
A high-performance temperature sensor based on mode-coupling principle is proposed using a selectively filled, solid-core photonic crystal fiber with a central air-bore. The fibers are fabricated using the "stack-and-draw" method, with a micro scale central bore deliberately kept during the drawing procedure. The addition of the central air-bore enhances the mode-coupling efficiency between the fundamental core mode and modes in the high-index liquid-filled holes in the fiber cladding, therefore, the fiber can be used for a novel sensing architecture, when cladding holes are selectively filled with temperature sensitive liquids...
April 17, 2017: Optics Express
Sylvain Pinet, Jean-Michel Martinez, Sylvain Ouillon, Bruno Lartiges, Raul Espinoza Villar
We investigated the relationships between inherent and apparent optical properties (IOP and AOP, respectively) and suspended sediment concentrations (SSC) in the main Amazonian river waters. In situ measurements of SSC, remote sensing reflectance (R<sub>rs</sub>), the diffuse light attenuation coefficient (K<sub>d</sub>) and the total and non-algal particle (NAP) absorption coefficients (a<sub>TOT</sub> and a<sub>NAP</sub>, respectively) were conducted during three sampling trips along different streams of the Amazon River catchment (104 stations)...
April 17, 2017: Optics Express
Orit Nuttman-Shwartz
There is extensive research evidence indicating that children and youth are the most vulnerable population for developing psychological symptoms relating to war and terror. Although studies have documented a wide range of detrimental emotional and behavioral effects of such exposure, much less is known about the effects of exposure to a continuous security threat for children and adolescents. Against this background, the current article examined the implications of continuous exposure to missile attacks among 1096 children and adolescents enrolled in public schools near the Israeli border with Gaza...
April 21, 2017: Child Abuse & Neglect
Kokulnathan Thangavelu, Nehru Raja, Shen-Ming Chen, Wei-Cheng Liao
Amalgamation of noble metal nanomaterials on graphene flakes potentially paves one way to improve their physicochemical properties. This paper deals with the simultaneous electrochemical deposition of gold and palladium nanoparticles on graphene flakes (Au/PdNPs-GRF) for the sensitive determination of caffeic acid (CA). The physiochemical properties of the prepared Au/PdNPs-GRF was characterized by using numerous analytical techniques such as scanning electron microscopy, electron dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction, Raman spectroscopy and electrochemical impedance spectroscopy...
April 13, 2017: Journal of Colloid and Interface Science
Mehboobali Pannipara, Abdullah G Al-Sehemi, Abul Kalam, Abdullah M Asiri, Muhammad Nadeem Arshad
A novel AIE active Schiff base compound (receptor 1) has been designed, synthesized and characterized spectroscopically. Receptor 1 show weak emission in solution state but emit strongly in solid state. The investigation on the AIE behavior of receptor 1 using solvent-non-solvent (THF-Water) interaction reveals a maximum PL intensity on reaching the water fraction 90% (fw=90) due to nanoaggregation. Furthermore, demonstration of metal ion sensing application of receptor 1 unravel that it could act as selective and sensitive sensor for Cu(2+) ions in aqueous solution via fluorescence "turn-off" manner...
April 20, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Yuedan Wang, Xing Qing, Quan Zhou, Yang Zhang, Qiongzhen Liu, Ke Liu, Wenwen Wang, Mufang Li, Zhentan Lu, Yuanli Chen, Dong Wang
Novel woven fiber organic electrochemical transistors based on polypyrrole (PPy) nanowires and reduced graphene oxide (rGO) have been prepared. SEM revealed that the introduction of rGO nanosheets could induce the growth and increase the amount of PPy nanowires. Moreover, it could enhance the electrical performance of fiber transistors. The hybrid transistors showed high on/off ratio of 10(2), fast switch speed, and long cycling stability. The glucose sensors based on the fiber organic electrochemical transistors have also been investigated, which exhibited outstanding sensitivity, as high as 0...
April 14, 2017: Biosensors & Bioelectronics
Cuiping Ma, Chao Liang, Yifan Wang, Mei Pan, Qianqian Jiang, Chao Shi
Combinatorial approaches in directed evolution were proven to be more efficient for exploring sequence space and innovating the function of protein. We presented modular assembly of secondary structures (MASS) for constructing a combinatorial library. In this approach, secondary structure elements were extracted from natural existing proteins, the common linkers were flanking secondary structure elements, then digested by Hinf I restriction endonuclease that was used in the construction of combinatorial library for the first time...
April 24, 2017: ACS Combinatorial Science
Wen-Yu Huang, Yi-Chen Wu, Hsin-Yi Pu, Ying Wang, Geng-Jen Jang, Shu-Hsing Wu
Light controls vegetative and reproductive development of plants. For a plant, sensing the light input properly ensures coordination with the ever-changing environment. Previously, we found that LIGHT-REGULATED WD1 (LWD1) and LWD2 regulate the circadian clock and photoperiodic flowering. Here we identified Arabidopsis YET ANOTHER KINASE1 (AtYAK1), an evolutionarily conserved protein and a member of dual-specificity tyrosine phosphorylation-regulated kinases (DYRKs), as an interacting protein of LWDs. Our study revealed that AtYAK1 is an important regulator for various light responses, including the circadian clock, photomorphogenesis and reproductive development...
April 24, 2017: Plant, Cell & Environment
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