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Ruchi Gupta, Nick J Goddard
Broadband absorption spectroscopy integrated with microfluidics is widely used to measure the pH of samples available in small volumes. Single pass absorption spectroscopy, however, suffers from poor minimum detectable absorption coefficient because the optical path length is determined by the physical dimensions of microchannels. As a result, either large amounts of indicator dyes are added or instrumentally complex techniques are used to determine sample pH. This work addresses these limitations by the integration of metal-clad leaky waveguide (MCLW) with microfluidics to perform broadband absorption spectroscopy...
December 5, 2016: Analyst
Meng Zou, Yutang Dai, Xian Zhou, Ke Dong, Minghong Yang
A composite microstructure in fiber Bragg grating (FBG) with film deposition for hydrogen detection is presented. Through ablated to FBG cladding by a femtosecond laser, straight-trenches and spiral micro-pits are formed. A Pd-Ag film is sputtered on the surface of the laser processed FBG single mode fiber, and acts as hydrogen sensing transducer. The demonstrated experimental outcomes show that a composite structure produced the highest sensitivity of 26.3 pm/%H, nearly sevenfold more sensitive compared with original standard FBG...
December 1, 2016: Sensors
Maoxiang Hou, Feng Zhu, Ying Wang, Yiping Wang, Changrui Liao, Shen Liu, Peixiang Lu
A gas pressure sensor based on an antiresonant reflecting guidance mechanism in a hollow-core fiber (HCF) with an open microchannel is experimentally demonstrated for gas pressure sensing. The microchannel was created on the ring cladding of the HCF by femtosecond laser drilling to provide an air-core pressure equivalent to the external environment. The HCF cladding functions as an antiresonant reflecting waveguide, which induces sharp periodic lossy dips in the transmission spectrum. The proposed sensor exhibits a high pressure sensitivity of 3...
November 28, 2016: Optics Express
A El Amili, M C M M Souza, F Vallini, N C Frateschi, Y Fainman
We experimentally investigate the application of magnetic fluids (MFs) on integrated silicon photonics. Using a ferrofluid-clad silicon microring resonator, we demonstrate active control of resonances by applying an external magnetic field. Relatively high loaded quality factors on the order of 6000 are achieved, despite the optical losses introduced by the magnetic nanoparticles. We demonstrate resonance shifts of 185 pm in response to a 110 Oe strong magnetic field, corresponding to an overall refractive index change of -3...
December 1, 2016: Optics Letters
Biqiang Jiang, Guolu Yin, Kaiming Zhou, Changle Wang, Xuetao Gan, Jianlin Zhao, Lin Zhang
By exploiting the polarization-sensitive coupling effect of graphene with the optical mode, we investigate the polarization modulation properties of a hybrid waveguide of graphene-integrated excessively tilted fiber grating (Ex-TFG). The theoretical analysis and experimental results demonstrate that the real and imaginary parts of complex refractive index of few-layer graphene exhibit different effects on transverse electric (TE) and transverse magnetic (TM) cladding modes of the Ex-TFG, enabling stronger absorption in the TE mode and more wavelength shift in the TM mode...
December 1, 2016: Optics Letters
Karima Chah, Damien Kinet, Christophe Caucheteur
New dual temperature and strain sensor has been designed using eccentric second-order fiber Bragg gratings produced in standard single-mode optical fiber by point-by-point direct writing technique with tight focusing of 800 nm femtosecond laser pulses. With thin gold coating at the grating location, we experimentally show that such gratings exhibit a transmitted amplitude spectrum composed by the Bragg and cladding modes resonances that extend in a wide spectral range exceeding one octave. An overlapping of the first order and second order spectrum is then observed...
November 30, 2016: Scientific Reports
Oscar E Zazueta, Sara E Preston, Anna Moniodis, Sabrina Fried, Miae Kim, Keri Townsend, Isabelle Wood, Steve Boukedes, Indira Guleria, Phillip Camp, Souheil El-Chemaly, Ivan O Rosas, Anil Chandraker, Edgar Milford, Hilary J Goldberg
BACKGROUND: Development of Donor-specific Antibodies (DSA) after lung transplantation is associated with antibody mediated rejection (AMR), acute cellular rejection, and bronchiolitis obliterans syndrome (BOS); however, the significance of circulating antibodies before transplant remains unclear. METHODS: We performed a retrospective cohort study including recipients of primary lung transplants between 2008 and 2012.We assessed the impact of circulating human leukocyte (HLA) and noncytotoxic Donor Specific antibodies (DSA) detected before transplant on development of Chronic Lung Allograft Dysfunction (CLAD) or CLAD related death...
November 23, 2016: Transplantation
Adriana Dubbeldam, Caroline Barthels, Johan Coolen, Johny A Verschakelen, Stijn E Verleden, Robin Vos, Geert M Verleden, Walter De Wever
OBJECTIVES: To describe the CT changes in patients with restrictive allograft syndrome (RAS) after lung transplantation, before and after clinical diagnosis. METHODS: This retrospective study included 22 patients with clinical diagnosis of RAS. Diagnosis was based on a combination of forced expiratory volume (FEV1) decline (≥20 %) and total lung capacity (TLC) decline (≥10 %). All available CT scans after transplantation were analyzed for the appearance and evolution of lung abnormalities...
November 22, 2016: European Radiology
Basha Khan, Lianne G Singer, Cecilia Chaparro, Tereza Martinu, Stephen Juvet, Mauricio Pipkin, Thomas K Waddell, Shaf Keshavjee, Atul Humar, Marcelo Cypel
Lung Transplantation using RNA+ hepatitis C (HCV+) donors to seronegative recipients is not currently performed due to the very high risk of transmission. Previous reports have shown poor survival when this practice was applied. The emergence of new direct-acting antiviral drugs (DAA) suggests a high chance of sustained virologic response (SVR) in immunocompetent patients. We report here successful transplantation of lungs from HCV+ donor to HCV- recipient. The recipient was an HCV- patient with chronic lung allograft dysfunction (CLAD)...
November 22, 2016: American Journal of Transplantation
Wafaa A Kaf, Kelly M Lewis, Erdem Yavuz, Samantha M Dixon, Mark Van Ess, Abdullah M Jamos, Rafael E Delgado
OBJECTIVES: Using the continuous loop averaging deconvolution (CLAD) technique for conventional electrocochleography (ECochG) and auditory brainstem response (ABR) recordings, the effects of testing at high stimulus rates may have the potential to diagnose disorders of the inner ear and auditory nerve. First, a body of normative data using the CLAD technique must be established. DESIGN: Extratympanic click ECochG and ABR to seven stimulus rates using CLAD were measured simultaneously from a tympanic membrane electrode and surface electrodes on the forehead and mastoid of 42 healthy individuals...
November 16, 2016: Ear and Hearing
David Ruttens, Stijn E Verleden, Esmée M Bijnens, Ellen Winckelmans, Jens Gottlieb, Gregor Warnecke, Federica Meloni, Monica Morosini, Wim Van Der Bij, Erik A Verschuuren, Urte Sommerwerck, Gerhard Weinreich, Markus Kamler, Antonio Roman, Susana Gomez-Olles, Cristina Berastegui, Christian Benden, Are Martin Holm, Martin Iversen, Hans Henrik Schultz, Bart Luijk, Erik-Jan Oudijk, Johanna M Kwakkel-van Erp, Peter Jaksch, Walter Klepetko, Nikolaus Kneidinger, Claus Neurohr, Paul Corris, Andrew J Fisher, James Lordan, Gerard Meachery, Davide Piloni, Elly Vandermeulen, Hannelore Bellon, Barbara Hoffmann, Danielle Vienneau, Gerard Hoek, Kees de Hoogh, Benoit Nemery, Geert M Verleden, Robin Vos, Tim S Nawrot, Bart M Vanaudenaerde
Air pollution from road traffic is a serious health risk, especially for susceptible individuals. Single-centre studies showed an association with chronic lung allograft dysfunction (CLAD) and survival after lung transplantation, but there are no large studies.13 lung transplant centres in 10 European countries created a cohort of 5707 patients. For each patient, we quantified residential particulate matter with aerodynamic diameter ≤10 µm (PM10) by land use regression models, and the traffic exposure by quantifying total road length within buffer zones around the home addresses of patients and distance to a major road or freeway...
November 11, 2016: European Respiratory Journal: Official Journal of the European Society for Clinical Respiratory Physiology
Christophe Caucheteur, Tuan Guo, Fu Liu, Bai-Ou Guan, Jacques Albert
Surface plasmon polaritons (SPP) can be excited on metal-coated optical fibres, enabling the accurate monitoring of refractive index changes. Configurations reported so far mainly operate in liquids but not in air because of a mismatch between permittivities of guided light modes and the surrounding medium. Here we demonstrate a plasmonic optical fibre platform that overcomes this limitation. The underpinning of our work is a grating architecture-a gold-coated highly tilted Bragg grating-that excites a spectral comb of narrowband-cladding modes with effective indices near 1...
November 11, 2016: Nature Communications
Linan Ma, Yang Tan, Shavkat Akhmadaliev, Shengqiang Zhou, Feng Chen
We demonstrate a tunable hybrid Graphene-Nd:YAG cladding waveguide laser exploiting the electro-optic and the Joule heating effects of Graphene. A cladding Nd:YAG waveguide was fabricated by the ion irradiation. The multi-layer graphene were transferred onto the waveguide surface as the saturable absorber to get the Q-switched pulsed laser oscillation in the waveguide. Composing with appropriate electrodes, graphene based capacitance and heater were formed on the surface of the Nd:YAG waveguide. Through electrical control of graphene, the state of the hybrid waveguide laser was turned on or off...
November 11, 2016: Scientific Reports
Matthew Loren Robinson, Timothy M DeBey, Jack F Higginbotham
A criticality analysis was benchmarked to sub-criticality measurements of the hexagonal fuel storage racks at the United States Geological Survey TRIGA MARK I reactor in Denver. These racks, which hold up to 19 fuel elements each, are arranged at 0.61m (2 feet) spacings around the outer edge of the reactor. A 3-dimensional model was created of the racks using MCNP5, and the model was verified experimentally by comparison to measured subcritical multiplication data collected in an approach to critical loading of two of the racks...
January 2017: Applied Radiation and Isotopes
Robin Guay-Lord, Xavier Attendu, Kristen L Lurie, Lucas Majeau, Nicolas Godbout, Audrey K Ellerbee Bowden, Mathias Strupler, Caroline Boudoux
No abstract text is available yet for this article.
November 1, 2016: Journal of Biomedical Optics
Shidong Jiang, Jun Lai
There has been increasing interest in making photonic devices more and more compact in the integrated photonics industry, and one of the important questions for manufacturers and design engineers is how to quantify the effect of the finite cladding thickness on the modal confinement loss of photonic waveguides. This requires at least six to seven digits of accuracy for the computation of propagation constant β since the modal confinement loss is proportional to the imaginary part of β that is six to seven orders of magnitude smaller than its real part by the industrial standard...
October 31, 2016: Optics Express
Yujia Li, Lei Gao, Wei Huang, Cong Gao, Min Liu, Tao Zhu
We report an all-fiber passively mode-locked laser based on a saturable absorber fabricated by filling short single-wall carbon nanotubes into cladding holes of grapefruit-type photonic crystal fiber. The single-wall carbon nanotube is insensitive to polarization of light for its one-dimensional structure, which suppresses the polarization dependence loss. Carbon nanotubes interact with photonic crystal fiber with ultra-weak evanescent field, which enhances the damage threshold of the saturable absorber and improves the operating stability...
October 3, 2016: Optics Express
Yuguang Zhang, Penghao Liu, Senlin Zhang, Weixi Liu, Jingye Chen, Yaocheng Shi
We present the design, fabrication and characterization of a high sensitivity temperature sensor based on cascaded silicon photonic crystal (PhC) nanobeam cavities. Two PhC nanobeam cavities, one with stack width modulated structure and the other one with parabolic-beam structure are utilized to increase the sensitivity. Most of the light is designed to be confined in the cladding and the core for these two cavities, respectively. Due to the positive thermo-optic (TO) coefficient of silicon and the negative TO coefficient of SU-8 cladding, the wavelength responses red shift for parabolic-beam cavity and blue shift for stack width modulated cavity as the increase of the ambient temperature, respectively...
October 3, 2016: Optics Express
J Soler Penades, A Ortega-Moñux, M Nedeljkovic, J G Wangüemert-Pérez, R Halir, A Z Khokhar, C Alonso-Ramos, Z Qu, I Molina-Fernández, P Cheben, G Z Mashanovich
We present several fundamental photonic building blocks based on suspended silicon waveguides supported by a lateral cladding comprising subwavelength grating metamaterial. We discuss the design, fabrication, and characterization of waveguide bends, multimode interference devices and Mach-Zehnder interferometers for the 3715 - 3800 nm wavelength range, demonstrated for the first time in this platform. The waveguide propagation loss of 0.82 dB/cm is reported, some of the lowest loss yet achieved in silicon waveguides for this wavelength range...
October 3, 2016: Optics Express
Chun-Ta Wang, Hao-Hsiang Hou, Ping-Chien Chang, Cheng-Chang Li, Hung-Chang Jau, Yung-Jr Hung, Tsung-Hsien Lin
This work proposes a tunable reflective guided-mode resonant (GMR) filter that incorporates a 90° twisted nematic liquid crystal (TNLC). The GMR grating acts as an optical resonator that reflects strongly at the resonance wavelength and as an alignment layer for LC. The 90° TNLC functions as an achromic polarization rotator that alters the polarization of incident light. The resonance wavelength and reflectance of such a filter can be controlled by setting the angle of incidence and driving the 90° TNLC, respectively...
October 3, 2016: Optics Express
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