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A C Cordeiro, J L Fabris, G H Couto, H J Kalinowski, E Bertogna
In this paper a method to evaluate the presence of microorganisms of the coliform group in water samples using the ultra-weak bioluminescence (UWB) is proposed. A series of UWB measurements and optical density measurements from cultures of both a set of standard E. coli strain samples, and a set of water samples from a river near Curitiba City in Brazil were performed. All samples were previously incubated at 37°C for 11h in nutritive medium before the temporal UWB emission profiles data were acquired for a period of 24h inside a dark chamber of an especially implemented instrumentation capable of doing photon counting measurements...
October 10, 2017: Journal of Photochemistry and Photobiology. B, Biology
Huadong Yang, Xinglin Tong, Zhang Cui, Chengwei Deng, Qian Guo, Pan Hu
The demodulation algorithm is very important to improving the measurement accuracy of a sensing system. In this paper, the variable step size hill climbing search method will be initially used for the optical fiber Fabry-Perot (F-P) sensing demodulation algorithm. Compared with the traditional discrete gap transformation demodulation algorithm, the computation is greatly reduced by changing step size of each climb, which could achieve nano-scale resolution, high measurement accuracy, high demodulation rates, and large dynamic demodulation range...
September 10, 2017: Applied Optics
Tingting Gang, Manli Hu, Yongxin Hao, Ruixiang Zhou, Rongxin Tong, Xueguang Qiao, Qiangzhou Rong
An integrated ultrasonic detection system that consists of emission and detection has been proposed and demonstrated experimentally. The proposed emission source is based on plastic optical fiber (POF). In order to promote the coupling of ultrasound-to-POF, and the end of the POF is heated to form a circular pedestal. A homemade fiber Fabry-Perot interferometer is employed to evaluate the coupling efficiency of ultrasound-to-POF. The sensing head is spliced with a short section of hollow-core fiber and single-mode fiber, resulting in an air microbubble formation by discharging...
August 20, 2017: Applied Optics
Abbas Ghasempour Ardakani, Marzieh Sedaghatnejad
We first investigate a graphene based 1D plasmonic photonic crystal (PPC) composed of a graphene sheet deposited on an SiO2 grating whose grooves are filled with air by using finite-element method (FEM) software (COMSOL Multiphysics). The dispersion effect of SiO2 is considered in the simulation, and we show that this effect significantly affects the transmission spectrum of the proposed PPC. The transmission spectrum shows a stop band in the mid-infrared region, which is blueshifted by increasing the Fermi energy level of the graphene sheet...
September 1, 2017: Applied Optics
Andre Van Rynbach, George Schwartz, Robert F Spivey, James Joseph, Geert Vrijsen, Jungsang Kim
We have fabricated and characterized laser-ablated micromirrors on fused silica substrates for constructing stable Fabry-Perot optical cavities. We highlight several design features which allow these cavities to have lengths in the 250-300 μm range and be integrated directly with surface ion traps. We present a method to calculate the optical mode shape and losses of these micromirror cavities as functions of cavity length and mirror shape, and confirm that our simulation model is in good agreement with experimental measurements of the intracavity optical mode at a test wavelength of 780 nm...
August 10, 2017: Applied Optics
A A Ryzhov
A multilayer GaAs/AlAs heterostructure forming a Fabry-Perot microcavity with a narrow resonance at 1.1 μm was produced by molecular-beam epitaxy. Under nanosecond pulsed laser radiation, a blueshift of the resonant line, associated with a photo-induced negative change in refractive index in GaAs, was experimentally registered by using an optical parametric oscillator. The spectral shift was accompanied by a reduction in peak transmittance, associated with nonlinear intracavity absorption. Such a cavity can be used as an optical limiter at the resonant wavelength when both the spectral shift and the transmittance reduction contribute to the limiting effect...
July 20, 2017: Applied Optics
Site Zhang, Christian Hellmann, Frank Wyrowski
We investigate the propagation of general electromagnetic fields through optical layer structures made of either isotropic or anisotropic media, by using the spectrum-of-plane-waves analysis together with the S-matrix method. We also develop an algorithm based on the fast Fourier transform technique, with a numerically efficient sampling rule. By using this algorithm in combination with other system modeling techniques, we present a few simulation examples, such as field propagation through an isotropic Fabry-Perot etalon, as well as uniaxial crystal slabs with arbitrary orientation and optic axis direction...
May 20, 2017: Applied Optics
Qiuling Zhao, Tsz Kit Yung, Xia Wang, Wing Yim Tam
We propose a method for the measurement of the reflection phase using a thick-gap Fabry-Perot (FP) etalon interferometry technique with correction for the numerical aperture effect of the optical setup. The setup is first calibrated using a known sample by comparing the reflectance from a two-beam interference model for the FP etalon with experimental data. We then apply the correction to a sample of interest and obtain the reflection phase of the sample. Our method can be used to measure the reflection phase of a small sample and could lead to practical applications in optical characterization of metamaterials...
May 20, 2017: Applied Optics
Yaxin Wang, Haihong Bao, Zengling Ran, Jingwei Huang, Shuang Zhang
An integrated sensor via overlapping a micro Fabry-Perot (MFP) cavity with a micro-channel on a regenerated fiber Bragg grating (RFBG) is constructed for dual-parameter sensing of temperature, strain, and gas pressure under a high temperature (600°C). The MFP is fabricated by using a 157 nm micro-machining on H2-loaded bendinsensitive fiber. A fiber Bragg grating (FBG) is inscribed at the same position of the MFP using 248 nm laser exposure, and then successfully regenerated after a required annealing process which enhances the strain sensitivity of MFP more than three times...
May 20, 2017: Applied Optics
Chee-Wei Lee, Doris Keh-Ting Ng, Min Ren, Yuan-Hsing Fu, Anthony Yew Seng Kay, Vivek Krishnamurthy, Jing Pu, Ai Ling Tan, Soo Bin Choo, Qian Wang
Electrically pumped heterogeneously integrated III-V/SiO2 semiconductor on-chip lasers with different types of etched facet reflectors are designed and fabricated and their lasing performances are characterized and compared. The III-V quantum-well-based epitaxial layers are bonded on silica-on-silicon substrates and fabricated to form Fabry-Perot lasers with dry-etched rear facets. Three types of reflectors are demonstrated, which are etched facets terminated by air, benzocyclobutene, and metal with a thin layer of SiO2 insulator in-between...
June 10, 2017: Applied Optics
Jens Buchmann, James Guggenheim, Edward Zhang, Chris Scharfenorth, Bastian Spannekrebs, Claus Villringer, Jan Laufer
A Fabry-Perot ultrasound sensor with nonhygroscopic dielectric mirrors made out of Ta2O5 and SiO2 for use in photoacoustic tomography is described. The sensor offers flat frequency response up to 36 MHz, low noise-equivalent pressure (70 Pa), and near-omnidirectional response up to 20 MHz as well as optical transparency for near-infrared illumination. A numerical model was developed to predict its frequency response, and the results were validated experimentally. An image of the human palm was acquired to demonstrate in vivo imaging capabilities...
June 10, 2017: Applied Optics
Kazem Jamshidi-Ghaleh, Fatemeh Moslemi
All-optical-diode tunability with externally applied voltage in a one-dimensional photonic crystal structure of arrangement (BA)(5)/AgLiNbO3Ag/(AB)(5)(AABB)(5) was investigated. It is an asymmetric hybrid Fabry-Perot resonator which is composed of distributed Bragg reflector segments (AB(5)) containing the linear (B layers) and nonlinear (A layers) optical materials. The LiNbO3, (LNO) sandwiched with two pairs Ag layers, is employed as a defect. The electro-optical (EO) effect and optical nonlinear response (Kerr effect) of LNO is considered...
May 10, 2017: Applied Optics
Kiwamu Izumi, Koji Arai, Daisuke Tatsumi, Ryutaro Takahashi, Osamu Miyakawa, Masa-Katsu Fujimoto
Lock acquisition of a suspended optical cavity can be a highly stochastic process and is therefore nontrivial. Guided lock is a method to make lock acquisition less stochastic by decelerating the motion of the cavity length based on an extrapolation of the motion from an instantaneous velocity measurement. We propose an improved scheme that is less susceptible to seismic disturbances by incorporating the acceleration as a higher-order correction in the extrapolation. We implemented the new scheme in a 300-m suspended Fabry-Perot cavity and improved the success rate of lock acquisition by a factor of 30...
July 1, 2017: Applied Optics
Julius de Hond, Nataly Cisternas, Graham Lochead, N J van Druten
We describe the design, construction, and characterization of a medium-finesse Fabry-Perot cavity for simultaneous frequency stabilization of two lasers operating at 960 and 780 nm wavelengths, respectively. The lasers are applied in experiments with ultracold rubidium Rydberg atoms, for which a combined laser linewidth similar to the natural Rydberg linewidth (≈10  kHz) is desired. The cavity, with a finesse of ≈1500, is used to reduce the linewidth of the lasers to below this level. By using a spacer made of ultra low expansion (ULE) glass with active temperature stabilization, the residual frequency drift is limited to ≲1  MHz/day...
July 1, 2017: Applied Optics
Shanat Baig, Nicky C Edward, Dipak Kotecha, Boyang Liu, Sabrina Nordin, Rebecca Kozor, James C Moon, Tarekegn Geberhiwot, Richard P Steeds
Fabry disease (FD) is an X-linked lysosomal storage disorder caused by deficiency of α-galactosidase A enzyme. Cardiovascular (CV) disease is a common cause of mortality in FD, in particular as a result of heart failure and arrhythmia, with a significant proportion of events categorized as sudden. There are no clear models for risk prediction in FD. This systematic review aims to identify the risk factors for ventricular arrhythmia (VA) and sudden cardiac deaths (SCD) in FD. A systematic search was performed following PRISMA guidelines of EMBASE, Medline, PubMed, Web of Science, and Cochrane from inception to August 2016, focusing on identification of risk factors for the development of VA or SCD...
October 17, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
Monica Allen, Oles Shtanko, Ion Cosma Fulga, Joel I-Jan Wang, Daniyar Nurgaliev, Kenji Watanabe, Takashi Taniguchi, Anton Akhmerov, Pablo Jarillo-Herrero, Leonid Levitov, Amir Yacoby
Electron surface states in solids are typically confined to the outermost atomic layers and, due to surface disorder, have negligible impact on electronic transport. Here we demonstrate a very different behavior for surface states in graphene. We probe the wavelike character of these states by Fabry-Perot (FP) interferometry and find that, in contrast to theoretical predictions, these states can propagate ballistically over micron-scale distances. This is achieved by embedding a graphene resonantor formed by gate-defined p-n junctions within a graphene SNS structure...
October 18, 2017: Nano Letters
Gilson Biagini, Ana Clara Simões Flórido Almeida, Tammy Vernalha Rocha Almeida, Cassiano Augusto Braga Silva, Bruna Fernanda de Castro, Tais Cristina Reche, Ana Cláudia Dabinski, Fellype Carvalho Barreto
Fabry disease is an X-linked lysosomal storage disease due to alpha-galactosidase A (α-Gal A) deficient activity which leads to the accumulation of glucoesphingolipids, such as globotriaosilceramide. There are over 700 known mutations of the enzyme gene, and most of them cause Fabry Disease. This case report describes a hemodialysis patient with a rare and controversial GLA gene mutation, the D313Y. The medecial investigation confirmed that D313Y is an alpha-galactosidase A sequence variant that causes pseudo deficient enzyme activity in plasma but not Fabry disease...
July 2017: Jornal Brasileiro de Nefrologia: ʹorgão Oficial de Sociedades Brasileira e Latino-Americana de Nefrologia
Riccardo Manenti, Anton F Kockum, Andrew Patterson, Tanja Behrle, Joseph Rahamim, Giovanna Tancredi, Franco Nori, Peter J Leek
The experimental investigation of quantum devices incorporating mechanical resonators has opened up new frontiers in the study of quantum mechanics at a macroscopic level. It has recently been shown that surface acoustic waves (SAWs) can be piezoelectrically coupled to superconducting qubits, and confined in high-quality Fabry-Perot cavities in the quantum regime. Here we present measurements of a device in which a superconducting qubit is coupled to a SAW cavity, realising a surface acoustic version of cavity quantum electrodynamics...
October 17, 2017: Nature Communications
Erika Janitz, Maximilian Ruf, Yannik Fontana, Jack Sankey, Lilian Childress
Fiber-based optical microcavities exhibit high quality factor and low mode volume resonances that make them attractive for coupling light to individual atoms or other microscopic systems. Moreover, their low mass should lead to excellent mechanical response up to high frequencies, opening the possibility for high bandwidth stabilization of the cavity length. Here, we demonstrate a locking bandwidth of 44 kHz achieved using a simple, compact design that exploits these properties. Owing to the simplicity of fiber feedthroughs and lack of free-space alignment, this design is inherently compatible with vacuum and cryogenic environments...
August 21, 2017: Optics Express
Zhengrui Tu, Dingshan Gao, Meiling Zhang, Daming Zhang
High-sensitivity complex refractive index sensing is proposed and experimentally demonstrated, favoring with sharp Fano resonance at 1550 nm wavelength based on subwavelength grating waveguide (SWG) micro-ring resonator. The micro-ring is composed by trapezoidal silicon pillars with subwavelength period to enhance the light-analyte overlap and get high quality factor as well. One straight SWG waveguide is side coupled with the micro-ring, which is specially designed to produce partial Fabry-Perot (FP) effect...
August 21, 2017: Optics Express
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