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Sample records for grating devices based

  1. Fiber Bragg grating based arterial localization device

    Science.gov (United States)

    Ho, Siu Chun Michael; Li, Weijie; Razavi, Mehdi; Song, Gangbing

    2017-06-01

    A critical first step to many surgical procedures is locating and gaining access to a patients vascular system. Vascular access allows the deployment of other surgical instruments and also the monitoring of many physiological parameters. Current methods to locate blood vessels are predominantly based on the landmark technique coupled with ultrasound, fluoroscopy, or Doppler. However, even with experience and technological assistance, locating the required blood vessel is not always an easy task, especially with patients that present atypical anatomy or suffer from conditions such as weak pulsation or obesity that make vascular localization difficult. With recent advances in fiber optic sensors, there is an opportunity to develop a new tool that can make vascular localization safer and easier. In this work, the authors present a new fiber Bragg grating (FBG) based vascular access device that specializes in arterial localization. The device estimates the location towards a local artery based on the bending of a needle inserted near the tissue surrounding the artery. Experimental results obtained from an artificial circulatory loop and a mock artery show the device works best for lower angles of needle insertion and can provide an approximately 40° range of estimation towards the location of a pulsating source (e.g. an artery).

  2. Fiber Bragg grating sensor-based communication assistance device

    Science.gov (United States)

    Padma, Srivani; Umesh, Sharath; Pant, Shweta; Srinivas, Talabattula; Asokan, Sundarrajan

    2016-08-01

    Improvements in emergency medicine in the form of efficient life supporting systems and intensive care have increased the survival rate in critically injured patients; however, in some cases, severe brain and spinal cord injuries can result in a locked-in syndrome or other forms of paralysis, and communication with these patients may become restricted or impossible. The present study proposes a noninvasive, real-time communication assistive methodology for those with restricted communication ability, employing a fiber Bragg grating (FBG) sensor. The communication assistive methodology comprises a breath pattern analyzer using an FBG sensor, which acquires the exhalation force that is converted into strain variations on a cantilever. The FBG breath pattern analyzer along with specific breath patterns, which are programmed to give specific audio output commands, constitutes the proposed fiber Bragg grating sensor-based communication assistive device. The basic communication can be carried out by instructing the patients with restricted communication ability to perform the specific breath patterns. The present approach is intended to be an alternative to the common approach of brain-computer interface in which an instrument is utilized for learning of brain responses.

  3. Grating-based guided-mode resonance devices and degradation of their performance in real-life conditions

    DEFF Research Database (Denmark)

    Ivinskaya, Aliaksandra; Bergmann, René; Kafka, Jan Robert

    2014-01-01

    Guided-mode resonances in structures having periodicity along at least one dimension were widely employed in the last decade in various optical devices. Initially it was shown that at frequencies close to the second order band gap periodic structures can feature total reflection of light due...... to the guided modes propagating along the surface of the grating. As an application, this allows to substitute a thick multilayer Bragg mirror in VCSELs by a thin grating-based mirror. Most devices utilizing guided-mode resonances were theoretically and numerically investigated with the idealized model...... of an infinite periodic structure illuminated by a plane wave. To see how grating-based components can perform in real life we take into account two critical factors: the finite size of the grating and the Gaussian shape of the light source replacing a plane wave. These factors can significantly change...

  4. WDM-Coherent OCDMA over one single device based on short chip Super Structured Fiber Bragg Gratings.

    Science.gov (United States)

    Amaya, Waldimar; Pastor, Daniel; Baños, Rocio; Garcia-Munoz, Victor

    2011-11-21

    We theoretically propose and demonstrate experimentally a Coherent Direct Sequence OCDMA en/decoder for multi-channel WDM operation based on a single device. It presents a broadband spectral envelope and a periodic spectral pattern that can be employed for en/decoding multiple sub-bands simultaneously. Multi-channel operation is verified experimentally by means of Multi-Band Super Structured Fiber Bragg Gratings with binary phase encoded chips fabricated with 1mm inter-chip separation that provides 4x100 GHz ITU sub-band separation at 1.25 Gbps. The WDM-OCDMA system verification was carried out employing simultaneous encoding of four adjacent sub-bands and two different OCDMA codes. © 2011 Optical Society of America

  5. Optical Fiber Grating based Sensors

    DEFF Research Database (Denmark)

    Michelsen, Susanne

    2003-01-01

    In this thesis differenct optical fiber gratings are used for sensor purposes. If a fiber with a core concentricity error (CCE) is used, a directional dependent bend sensor can be produced. The CCE direction can be determined by means of diffraction. This makes it possible to produce long......-period gratings in a fiber with a CCE direction parallel or perpendicular to the writing direction. The maximal bending sensitivity is independent on the writing direction, but the detailed bending response is different in the two cases. A temperature and strain sensor, based on a long-period grating and two...... sampled gratings, was produced and investigated. It is based on the different temperature and strain response of these gratings. Both a transfer matrix method and an overlap calculation is performed to explain the sensor response. Another type of sensor is based on tuning and modulation of a laser...

  6. A Novel MOS Nanowire Gas Sensor Device (S3 and GC-MS-Based Approach for the Characterization of Grated Parmigiano Reggiano Cheese

    Directory of Open Access Journals (Sweden)

    Veronica Sberveglieri

    2016-12-01

    Full Text Available To determine the originality of a typical Italian Parmigiano Reggiano cheese, it is crucial to define and characterize its quality, ripening period, and geographical origin. Different analytical techniques have been applied aimed at studying the organoleptic and characteristic volatile organic compounds (VOCs profile of this cheese. However, most of the classical methods are time consuming and costly. The aim of this work was to illustrate a new simple, portable, fast, reliable, non-destructive, and economic sensor device S3 based on an array of six metal oxide semiconductor nanowire gas sensors to assess and discriminate the quality ranking of grated Parmigiano Reggiano cheese samples and to identify the VOC biomarkers using a headspace SPME-GC-MS. The device could clearly differentiate cheese samples varying in quality and ripening time when the results were analyzed by multivariate statistical analysis involving principal component analysis (PCA. Similarly, the volatile constituents of Parmigiano Reggiano identified were consistent with the compounds intimated in the literature. The obtained results show the applicability of an S3 device combined with SPME-GC-MS and sensory evaluation for a fast and high-sensitivity analysis of VOCs in Parmigiano Reggiano cheese and for the quality control of this class of cheese.

  7. POF based glucose sensor incorporating grating wavelength filters

    DEFF Research Database (Denmark)

    Hassan, Hafeez Ul; Aasmul, Søren; Bang, Ole

    2014-01-01

    AND RESEARCH IN POLYMER OPTICAL DEVICES; TRIPOD. Within the domain of TRIPOD, research is conducted on "Plastic Optical Fiber based Glucose Sensors Incorporating Grating Wavelength Filters". Research will be focused to optimized fiber tips for better coupling efficiency, reducing the response time of sensor...

  8. Feasibility evaluation of a neutron grating interferometer with an analyzer grating based on a structured scintillator

    Science.gov (United States)

    Kim, Youngju; Kim, Jongyul; Kim, Daeseung; Hussey, Daniel. S.; Lee, Seung Wook

    2018-03-01

    We introduce an analyzer grating based on a structured scintillator fabricated by a gadolinium oxysulfide powder filling method for a symmetric Talbot-Lau neutron grating interferometer. This is an alternative way to analyze the Talbot self-image of a grating interferometer without using an absorption grating to block neutrons. Since the structured scintillator analyzer grating itself generates the signal for neutron detection, we do not need an additional scintillator screen as an absorption analyzer grating. We have developed and tested an analyzer grating based on a structured scintillator in our symmetric Talbot-Lau neutron grating interferometer to produce high fidelity absorption, differential phase, and dark-field contrast images. The acquired images have been compared to results of a grating interferometer utilizing a typical absorption analyzer grating with two commercial scintillation screens. The analyzer grating based on the structured scintillator enhances interference fringe visibility and shows a great potential for economical fabrication, compact system design, and so on. We report the performance of the analyzer grating based on a structured scintillator and evaluate its feasibility for the neutron grating interferometer.

  9. Ultra-broadband and wide-angle perfect absorber based on composite metal-semiconductor grating

    Science.gov (United States)

    Li, Xu; Wang, Zongpeng; Hou, Yumin

    2018-01-01

    In this letter, we present an ultra-broadband and wide-angle perfect absorber based on composite Ge-Ni grating. Near perfect absorption above 90% is achieved in a wide frequency range from 150 nm to 4200 nm, which covers almost the full spectrum of solar radiation. The absorption keeps robust in a wide range of incident angle from 0º to 60º. The upper triangle Ge grating works as an antireflection coating. The lower Ni grating works as a reflector and an effective energy trapper. The guided modes inside Ge grating are excited due to reflection of the lower Ni grating surface. In longer wavelength band, gap surface plasmons (GSPs) in the Ni grating are excited and couple with the guided modes inside the Ge grating. The coupled modes extend the perfect absorption band to the near-infrared region (150 nm-4200 nm). This design has potential application in photovoltaic devices and thermal emitters.

  10. Optically controlled tunable dispersion compensators based on pumped fiber gratings.

    Science.gov (United States)

    Shu, Xuewen; Sugden, Kate; Bennion, Ian

    2011-08-01

    We demonstrate optically tunable dispersion compensators based on pumping fiber Bragg gratings made in Er/Yb codoped fiber. The tunable dispersion for a chirped grating and also a uniform-period grating was successfully demonstrated in the experiment. The dispersion of the chirped grating was tuned from 900 to 1990 ps/nm and also from -600 to -950 ps/nm in the experiment. © 2011 Optical Society of America

  11. Water Vapor Sensors Based on the Swelling of Relief Gelatin Gratings

    Directory of Open Access Journals (Sweden)

    Sergio Calixto

    2015-01-01

    Full Text Available We report on a novel device to measure relative humidity. The sensor is based on surface diffraction gratings made of gelatin. This material swells and shrinks according to the content of water vapor in air. By sending a light beam to the grating, diffracted orders appear. Due to the gelatin swelling or shrinking, first order intensity changes according to the relative humidity. Calibration curves relating intensity versus relative humidity have been found. The fabrication process of diffraction gratings and the testing of the prototype sensing devices are described.

  12. An optical tunable filter array based on LCOS phase grating

    Science.gov (United States)

    Feng, Dong; Wan, Zhujun; Chen, Xu; Yan, Shijia; Luo, Zhixiang

    2018-01-01

    This paper reports an optical tunable filter array (TFA) based on a LCOS (liquid crystal on silicon) chip. The input broadband optical beam is first dispersed by a bulk grating and then incident on the LCOS chip. The LCOS chip is phase-only modulated and constructed as a dynamic reflective phase grating. The phase modulation is adjusted to meet the Littrow angle for a specified passband wavelength and thus the optical beam corresponding to this wavelength is steered to the output. The input/output optical beams are coupled to optical fibers with a dual-fiber collimator. Four dualfiber collimators are vertically aligned as the inputs/outputs and the pixels of the LCOS chip are vertically allocated as four independent zones. Thus the device can act as a 4-channel TFA, which is assembled and functionally demonstrated.

  13. Enhancement of Light Absorption in Silicon Nanowire Photovoltaic Devices with Dielectric and Metallic Grating Structures.

    Science.gov (United States)

    Park, Jin-Sung; Kim, Kyoung-Ho; Hwang, Min-Soo; Zhang, Xing; Lee, Jung Min; Kim, Jungkil; Song, Kyung-Deok; No, You-Shin; Jeong, Kwang-Yong; Cahoon, James F; Kim, Sun-Kyung; Park, Hong-Gyu

    2017-12-13

    We report the enhancement of light absorption in Si nanowire photovoltaic devices with one-dimensional dielectric or metallic gratings that are fabricated by a damage-free, precisely aligning, polymer-assisted transfer method. Incorporation of a Si 3 N 4 grating with a Si nanowire effectively enhances the photocurrents for transverse-electric polarized light. The wavelength at which a maximum photocurrent is generated is readily tuned by adjusting the grating pitch. Moreover, the electrical properties of the nanowire devices are preserved before and after transferring the Si 3 N 4 gratings onto Si nanowires, ensuring that the quality of pristine nanowires is not degraded during the transfer. Furthermore, we demonstrate Si nanowire photovoltaic devices with Ag gratings using the same transfer method. Measurements on the fabricated devices reveal approximately 27.1% enhancement in light absorption compared to that of the same devices without the Ag gratings without any degradation of electrical properties. We believe that our polymer-assisted transfer method is not limited to the fabrication of grating-incorporated nanowire photovoltaic devices but can also be generically applied for the implementation of complex nanoscale structures toward the development of multifunctional optoelectronic devices.

  14. Multiple infrared bands absorber based on multilayer gratings

    Science.gov (United States)

    Liu, Xiaoyi; Gao, Jinsong; Yang, Haigui; Wang, Xiaoyi; Guo, Chengli

    2018-03-01

    The present study offers an Ag/Si multilayer-grating microstructure based on an Si substrate. The microstructure exhibits designable narrowband absorption in multiple infrared wavebands, especially in mid- and long-wave infrared atmospheric windows. We investigate its resonance mode mechanism, and calculate the resonance wavelengths by the Fabry-Perot and metal-insulator-metal theories for comparison with the simulation results. Furthermore, we summarize the controlling rules of the absorption peak wavelength of the microstructure to provide a new method for generating a Si-based device with multiple working bands in infrared.

  15. Design of a Label-Free, Distributed Bragg Grating Resonator Based Dielectric Waveguide Biosensor

    Directory of Open Access Journals (Sweden)

    Florian Kehl

    2015-01-01

    Full Text Available In this work, we present a resonant, dielectric waveguide device based on distributed Bragg gratings for label-free biosensing applications. The refractive index sensitive optical transducer aims at improving the performance of planar waveguide grating sensor systems with limited Q-factor and dynamic range by combing the advantages of resonant cavities, such as a multitude of resonance peaks with high finesse, with the manageable complexity of waveguide grating couplers. The general sensor concept is introduced and supported by theoretical considerations as well as numerical simulations based on Coupled Mode Theory. In contrast to a single Bragg grating reflector, the presented Fabry-Pérot type distributed Bragg resonator exhibits an extended measurement range as well as relaxed fabrication tolerances. The resulting, relatively simple sensor structure can be fabricated with standard lithographic means and is independent of expensive light-sources and/or detectors, making an affordable but sensitive device, potentially suitable for point-of-care applications.

  16. Photonic Hilbert transformers based on laterally apodized integrated waveguide Bragg gratings on a SOI wafer.

    Science.gov (United States)

    Bazargani, Hamed Pishvai; Burla, Maurizio; Chrostowski, Lukas; Azaña, José

    2016-11-01

    We experimentally demonstrate high-performance integer and fractional-order photonic Hilbert transformers based on laterally apodized Bragg gratings in a silicon-on-insulator technology platform. The sub-millimeter-long gratings have been fabricated using single-etch electron beam lithography, and the resulting HT devices offer operation bandwidths approaching the THz range, with time-bandwidth products between 10 and 20.

  17. Nanoporous Polymeric Grating-Based Biosensors

    KAUST Repository

    Gao, Tieyu

    2012-05-02

    We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays. Copyright © 2010 by ASME.

  18. Nanoporous Polymeric Grating-Based Biosensors

    KAUST Repository

    Gao, Tieyu; Hsiao, Vincent; Zheng, Yue Bing; Huang, Tony Jun

    2012-01-01

    We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays. Copyright © 2010 by ASME.

  19. Spherical grating based x-ray Talbot interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Cong, Wenxiang, E-mail: congw@rpi.edu, E-mail: xiy2@rpi.edu, E-mail: wangg6@rpi.edu; Xi, Yan, E-mail: congw@rpi.edu, E-mail: xiy2@rpi.edu, E-mail: wangg6@rpi.edu; Wang, Ge, E-mail: congw@rpi.edu, E-mail: xiy2@rpi.edu, E-mail: wangg6@rpi.edu [Biomedical Imaging Center, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2015-11-15

    Purpose: Grating interferometry is a state-of-the-art x-ray imaging approach, which can acquire information on x-ray attenuation, phase shift, and small-angle scattering simultaneously. Phase-contrast imaging and dark-field imaging are very sensitive to microstructural variation and offers superior contrast resolution for biological soft tissues. However, a common x-ray tube is a point-like source. As a result, the popular planar grating imaging configuration seriously restricts the flux of photons and decreases the visibility of signals, yielding a limited field of view. The purpose of this study is to extend the planar x-ray grating imaging theory and methods to a spherical grating scheme for a wider range of preclinical and clinical applications. Methods: A spherical grating matches the wave front of a point x-ray source very well, allowing the perpendicular incidence of x-rays on the grating to achieve a higher visibility over a larger field of view than the planer grating counterpart. A theoretical analysis of the Talbot effect for spherical grating imaging is proposed to establish a basic foundation for x-ray spherical gratings interferometry. An efficient method of spherical grating imaging is also presented to extract attenuation, differential phase, and dark-field images in the x-ray spherical grating interferometer. Results: Talbot self-imaging with spherical gratings is analyzed based on the Rayleigh–Sommerfeld diffraction formula, featuring a periodic angular distribution in a polar coordinate system. The Talbot distance is derived to reveal the Talbot self-imaging pattern. Numerical simulation results show the self-imaging phenomenon of a spherical grating interferometer, which is in agreement with the theoretical prediction. Conclusions: X-ray Talbot interferometry with spherical gratings has a significant practical promise. Relative to planar grating imaging, spherical grating based x-ray Talbot interferometry has a larger field of view and

  20. Spherical grating based x-ray Talbot interferometry

    International Nuclear Information System (INIS)

    Cong, Wenxiang; Xi, Yan; Wang, Ge

    2015-01-01

    Purpose: Grating interferometry is a state-of-the-art x-ray imaging approach, which can acquire information on x-ray attenuation, phase shift, and small-angle scattering simultaneously. Phase-contrast imaging and dark-field imaging are very sensitive to microstructural variation and offers superior contrast resolution for biological soft tissues. However, a common x-ray tube is a point-like source. As a result, the popular planar grating imaging configuration seriously restricts the flux of photons and decreases the visibility of signals, yielding a limited field of view. The purpose of this study is to extend the planar x-ray grating imaging theory and methods to a spherical grating scheme for a wider range of preclinical and clinical applications. Methods: A spherical grating matches the wave front of a point x-ray source very well, allowing the perpendicular incidence of x-rays on the grating to achieve a higher visibility over a larger field of view than the planer grating counterpart. A theoretical analysis of the Talbot effect for spherical grating imaging is proposed to establish a basic foundation for x-ray spherical gratings interferometry. An efficient method of spherical grating imaging is also presented to extract attenuation, differential phase, and dark-field images in the x-ray spherical grating interferometer. Results: Talbot self-imaging with spherical gratings is analyzed based on the Rayleigh–Sommerfeld diffraction formula, featuring a periodic angular distribution in a polar coordinate system. The Talbot distance is derived to reveal the Talbot self-imaging pattern. Numerical simulation results show the self-imaging phenomenon of a spherical grating interferometer, which is in agreement with the theoretical prediction. Conclusions: X-ray Talbot interferometry with spherical gratings has a significant practical promise. Relative to planar grating imaging, spherical grating based x-ray Talbot interferometry has a larger field of view and

  1. Modeling fiber Bragg grating device networks in photomechanical polymer optical fibers

    Science.gov (United States)

    Lanska, Joseph T.; Kuzyk, Mark G.; Sullivan, Dennis M.

    2015-09-01

    We report on the modeling of fiber Bragg grating (FBG) networks in poly(methyl methacrylate) (PMMA) polymer fibers doped with azo dyes. Our target is the development of Photomechanical Optical Devices (PODs), comprised of two FBGs in series, separated by a Fabry-Perot cavity of photomechanical material. PODs exhibit photomechanical multi-stability, with the capacity to access multiple length states for a fixed input intensity when a mechanical shock is applied. Using finite-difference time-domain (FDTD) numerical methods, we modeled the photomechanical response of both Fabry-Perot and Bragg-type PODs in a single polymer optical fiber. The polymer fiber was modeled as an instantaneous Kerr-type nonlinear χ(3) material. Our model correctly predicts the essential optical features of FBGs as well as the photomechanical multi-stability of nonlinear Fabry-Perot cavity-based PODs. Networks of PODs may provide a framework for smart shape-shifting materials and fast optical computation where the decision process is distributed over the entire network. In addition, a POD can act as memory, and its response can depend on input history. Our models inform and will accelerate targeted development of novel Bragg grating-based polymer fiber device networks for a variety of applications in optical computing and smart materials.

  2. Perturbative modeling of Bragg-grating-based biosensors in photonic-crystal fibers

    DEFF Research Database (Denmark)

    Burani, Nicola; Lægsgaard, Jesper

    2005-01-01

    We present a modeling study carried out to support the design of a novel, to our knowledge, kind of photonic-crystal fiber (PCF)-based sensor. This device, based on a PCF Bragg grating, detects the presence of selected single-stranded DNA molecules, hybridized to a biofilm in the air holes of the...

  3. Palladium coated fibre Bragg grating based hydrogen sensor

    International Nuclear Information System (INIS)

    Kasinathan, M.; Sosamma, S.; Kishore, S.; Elumalai, V.; Krishnan, R.; Babu Rao, C.; Dash, Sitaram; Murali, N.; Jayakumar, T.

    2011-01-01

    Detection of steam generator leaks in fast nuclear reactors is carried out by monitoring hydrogen in argon cover-gas. Hydrogen released during sodium cleaning of fast reactor components is required to be monitored. Hydrogen sensors with good sensitivity, stability and response time are required for all the above applications. We report a new type of hydrogen sensor with a Fibre Bragg Grating (FBG) coated with palladium thin film which is used to detect the leak of hydrogen gas in the Steam Generator (SG) module of the Fast Breeder Reactor (FBR). If water leaks into sodium, it results in sodium-water reaction. In this reaction hydrogen and sodium hydroxide are formed. Due to the explosive risk of hydrogen system, hydrogen sensors are of great interest in this case. It is known that hydrogen forms an explosive mixture with air once its concentration exceeds beyond the explosion limit of four percent. The advantages of FBG based hydrogen sensor over the other hydrogen sensors are its inherent property of safety from sparking, immunity to ambient electromagnetic interference. The sensing mechanism in this device is based on mechanical strain that is induced in the palladium coating when it absorbs hydrogen. This process physically stretches the grating and causes the grating period and grating's refractive index, to change. The Bragg wavelength shift is directly proportional to the strain induced and can be directly related to the percentage of hydrogen exposure. The online monitoring of palladium thin film coating on FBG is carried out and recorded the wavelength change and strain induced on the FBG. A hydrogen sensor set up have been fabricated which consists of SS vessel of capacity 10 litres, provided with pressure gauge, Argon filling line with a valve, Hydrogen injection line with flange, a vent line with valve and Hydrogen sensor fixing point. The Palladium coated FBG based Hydrogen sensor is tested in this experimental facility in the exposure of hydrogen in

  4. Grating geophone signal processing based on wavelet transform

    Science.gov (United States)

    Li, Shuqing; Zhang, Huan; Tao, Zhifei

    2008-12-01

    Grating digital geophone is designed based on grating measurement technique benefiting averaging-error effect and wide dynamic range to improve weak signal detected precision. This paper introduced the principle of grating digital geophone and its post signal processing system. The signal acquisition circuit use Atmega 32 chip as core part and display the waveform on the Labwindows through the RS232 data link. Wavelet transform is adopted this paper to filter the grating digital geophone' output signal since the signal is unstable. This data processing method is compared with the FIR filter that widespread use in current domestic. The result indicates that the wavelet algorithm has more advantages and the SNR of seismic signal improve obviously.

  5. Angle-resolved diffraction grating biosensor based on porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Changwu; Li, Peng [School of Physical Science and Technology, Xinjiang University, Urumqi 830046 (China); Jia, Zhenhong, E-mail: jzhh@xju.edu.cn; Liu, Yajun; Mo, Jiaqing; Lv, Xiaoyi [College of Information Science and Engineering, Xinjiang University, Urumqi 830046 (China)

    2016-03-07

    In this study, an optical biosensor based on a porous silicon composite structure was fabricated using a simple method. This structure consists of a thin, porous silicon surface diffraction grating and a one-dimensional porous silicon photonic crystal. An angle-resolved diffraction efficiency spectrum was obtained by measuring the diffraction efficiency at a range of incident angles. The angle-resolved diffraction efficiency of the 2nd and 3rd orders was studied experimentally and theoretically. The device was sensitive to the change of refractive index in the presence of a biomolecule indicated by the shift of the diffraction efficiency spectrum. The sensitivity of this sensor was investigated through use of an 8 base pair antifreeze protein DNA hybridization. The shifts of the angle-resolved diffraction efficiency spectrum showed a relationship with the change of the refractive index, and the detection limit of the biosensor reached 41.7 nM. This optical device is highly sensitive, inexpensive, and simple to fabricate. Using shifts in diffraction efficiency spectrum to detect biological molecules has not yet been explored, so this study establishes a foundation for future work.

  6. Application of a long-period fibre grating-based transducer in the fuel industry

    International Nuclear Information System (INIS)

    Possetti, G R C; De Arruda, L V R; Muller, M; Fabris, J L; Côcco, L C; Yamamoto, C I; Falate, R

    2009-01-01

    This work shows prospects of long-period fibre grating applications as transducers for fuel conformity analysis. The proposed long-period grating transducer was employed to assess the gasoline conformity in commercial gas stations. Grating responses were used to train and validate a radial base function topology of an artificial neural network. The obtained results show that fibre optic sensors supervised by artificial neural networks can integrate systems for smart sensing with high applicability in the petrochemical field. The radial base function had reached a correct classification probability of approximately 94%. The device applicability in the analysis of hydrated ethanol fuel was also investigated by measuring the concentration of ethanol in ethanol–water mixtures. The results showed that the developed transducer can be used to infer the ethanol–water concentration with a resolution of up to 0.23%

  7. Polarization-selective infrared bandpass filter based on a two-layer subwavelength metallic grating

    Science.gov (United States)

    Hohne, Andrew J.; Moon, Benjamin; Baumbauer, Carol L.; Gray, Tristan; Dilts, James; Shaw, Joseph A.; Dickensheets, David L.; Nakagawa, Wataru

    2017-08-01

    We present the design, fabrication, and characterization of a polarization-selective infrared bandpass filter based on a two-layer subwavelength metallic grating for use in polarimetric imaging. Gold nanowires were deposited via physical vapor deposition (PVD) onto a silicon surface relief grating that was patterned using electron beam lithography (EBL) and fabricated using standard silicon processing techniques. Optical characterization with a broad-spectrum tungsten halogen light source and a grating spectrometer showed normalized peak TM transmission of 53% with a full-width at half-maximum (FWHM) of 122 nm, which was consistent with rigorous coupled-wave analysis (RCWA) simulations. Simulation results suggested that device operation relied on suppression of the TM transmission caused by surface plasmon polariton (SPP) excitation at the gold-silicon interface and an increase in TM transmission caused by a Fabry-Perot (FP) resonance in the cavity between the gratings. TE rejection occurred at the initial air/gold interface. We also present simulation results of an improved design based on a two-dielectric grating where two different SPP resonances allowed us to improve the shape of the passband by suppressing the side lobes. This newer design resulted in improved side-band performance and increased peak TM transmission.

  8. Grating-based tomography applications in biomedical engineering

    Science.gov (United States)

    Schulz, Georg; Thalmann, Peter; Khimchenko, Anna; Müller, Bert

    2017-10-01

    For the investigation of soft tissues or tissues consisting of soft and hard tissues on the microscopic level, hard X-ray phase tomography has become one of the most suitable imaging techniques. Besides other phase contrast methods grating interferometry has the advantage of higher sensitivity than inline methods and the quantitative results. One disadvantage of the conventional double-grating setup (XDGI) compared to inline methods is the limitation of the spatial resolution. This limitation can be overcome by removing the analyser grating resulting in a single-grating setup (XSGI). In order to verify the performance of XSGI concerning contrast and spatial resolution, a quantitative comparison of XSGI and XDGI tomograms of a human nerve was performed. Both techniques provide sufficient contrast to allow for the distinction of tissue types. The spatial resolution of the two-fold binned XSGI data set is improved by a factor of two in comparison to XDGI which underlies its performance in tomography of soft tissues. Another application for grating-based X-ray phase tomography is the simultaneous visualization of soft and hard tissues of a plaque-containing coronary artery. The simultaneous visualization of both tissues is important for the segmentation of the lumen. The segmented data can be used for flow simulations in order to obtain information about the three-dimensional wall shear stress distribution needed for the optimization of mechano-sensitive nanocontainers used for drug delivery.

  9. Multipoint sensor based on fiber Bragg gratings

    International Nuclear Information System (INIS)

    Mendez-Zepeda, O; Munoz-Aguirre, S; Beltran-Perez, G; Castillo-Mixcoatl, J

    2011-01-01

    In some control and industrial measurement systems of physical variables (pressure, temperature, flow, etc) it is necessary one system and one sensor to control each process. On the other hand, there are systems such as PLC (Programmable Logic Control), which can process several signals simultaneously. However it is still necessary to use one sensor for each variable. Therefore, in the present work the use of a multipoint sensor to solve such problem has been proposed. The sensor consists of an optical fiber laser with two Fabry-Perot cavities constructed using fiber Bragg gratings (FBG). In the same system is possible to measure changes in two variables by detecting the intermodal separation frequency of each cavity and evaluate their amplitudes. The intermodal separation frequency depends on each cavity length. The sensor signals are monitored through an oscilloscope or a PCI card and after that acquired by PC, where they are analyzed and displayed. Results of the evaluation of the intermodal frequency separation peak amplitude behavior with FBG stretching are presented.

  10. Model based control of grate combustion; Modellbaserad roststyrning

    Energy Technology Data Exchange (ETDEWEB)

    Broden, Henrik; Kjellstroem, Bjoern; Niklasson, Fredrik; Boecher Poulsen, Kristian

    2006-12-15

    An existing dynamic model for grate combustion has been further developed. The model has been used for studies of possible advantages that can be gained from utilisation of measurements of grate temperatures and fuel bed height for control of a boiler after disturbances caused by varying fuel moisture and fuel feeding. The objective was to asses the possibilities to develop a control system that would adjust for such disturbances quicker than measurements of steam output and oxygen in the exhaust. The model is based on dividing the fuel bed into three layers, where the different layers include fuel being dried, fuel being pyrolysed and char reacting with oxygen. The grate below the fuel bed is also considered. A mass balance, an energy balance and a volume balance is considered for each layer in 22 cells along the grate. The energy balances give the temperature distribution and the volume balances the bed height. The earlier version of the model could not handle layers that are consumed. This weakness has now been eliminated. Comparisons between predicted grate temperatures and measurements in a 25 MW boiler fuelled with biofuel have been used for validation of the model. The comparisons include effects of variations in primary air temperature, fuel moisture and output power. The model shows good agreement with observations for changes in the air temperature but the ability of the model to predict effects of changed fuel moisture is difficult to judge since the steam dome pressure control caused simultaneous changes of the primary air flow, which probably had a larger influence on the grate temperature. A linearised, tuned and reduced version of the model was used for design of a linear quadratic controller. This was used for studies of advantages of using measurements of grate temperatures and bed height for control of pusher velocity, grate speed, primary air flow and air temperature after disturbances of fuel moisture and fuel flow. Measurements of the grate

  11. Fiber Bragg Grating Based System for Temperature Measurements

    Science.gov (United States)

    Tahir, Bashir Ahmed; Ali, Jalil; Abdul Rahman, Rosly

    In this study, a fiber Bragg grating sensor for temperature measurement is proposed and experimentally demonstrated. In particular, we point out that the method is well-suited for monitoring temperature because they are able to withstand a high temperature environment, where standard thermocouple methods fail. The interrogation technologies of the sensor systems are all simple, low cost and effective as well. In the sensor system, fiber grating was dipped into a water beaker that was placed on a hotplate to control the temperature of water. The temperature was raised in equal increments. The sensing principle is based on tracking of Bragg wavelength shifts caused by the temperature change. So the temperature is measured based on the wavelength-shifts of the FBG induced by the heating water. The fiber grating is high temperature stable excimer-laser-induced grating and has a linear function of wavelength-temperature in the range of 0-285°C. A dynamic range of 0-285°C and a sensitivity of 0.0131 nm/°C almost equal to that of general FBG have been obtained by this sensor system. Furthermore, the correlation of theoretical analysis and experimental results show the capability and feasibility of the purposed technique.

  12. All-silicon nanorod-based Dammann gratings.

    Science.gov (United States)

    Li, Zile; Zheng, Guoxing; He, Ping'An; Li, Song; Deng, Qiling; Zhao, Jiangnan; Ai, Yong

    2015-09-15

    Established diffractive optical elements (DOEs), such as Dammann gratings, whose phase profile is controlled by etching different depths into a transparent dielectric substrate, suffer from a contradiction between the complexity of fabrication procedures and the performance of such gratings. In this Letter, we combine the concept of geometric phase and phase modulation in depth, and prove by theoretical analysis and numerical simulation that nanorod arrays etched on a silicon substrate have a characteristic of strong polarization conversion between two circularly polarized states and can act as a highly efficient half-wave plate. More importantly, only by changing the orientation angles of each nanorod can the arrays control the phase of a circularly polarized light, cell by cell. With the above principle, we report the realization of nanorod-based Dammann gratings reaching diffraction efficiencies of 50%-52% in the C-band fiber telecommunications window (1530-1565 nm). In this design, uniform 4×4 spot arrays with an extending angle of 59°×59° can be obtained in the far field. Because of these advantages of the single-step fabrication procedure, accurate phase controlling, and strong polarization conversion, nanorod-based Dammann gratings could be utilized for various practical applications in a range of fields.

  13. Multichannel photonic Hilbert transformers based on complex modulated integrated Bragg gratings.

    Science.gov (United States)

    Cheng, Rui; Chrostowski, Lukas

    2018-03-01

    Multichannel photonic Hilbert transformers (MPHTs) are reported. The devices are based on single compact spiral integrated Bragg gratings on silicon with coupling coefficients precisely modulated by the phase of each grating period. MPHTs with up to nine wavelength channels and a single-channel bandwidth of up to ∼625  GHz are achieved. The potential of the devices for multichannel single-sideband signal generation is suggested. The work offers a new possibility of utilizing wavelength as an extra degree of freedom in designing radio-frequency photonic signal processors. Such multichannel processors are expected to possess improved capacities and a potential to greatly benefit current widespread wavelength division multiplexed systems.

  14. Dense Wavelength Division (De Multiplexers Based on Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    S. BENAMEUR

    2014-05-01

    Full Text Available This study is to measure the impact of demultiplexers based on Fiber Bragg Grating (FBG filter on performance of DWDM system for optical access network. An optical transmission link has been established in which we have inserted a demultiplexer based on four different FBG filters. The first step will be the characterization of FBG’s filters (i.e. uniform FBG, Gaussian apodized Grating, chirped FBG to explain their behavior in the optical link. The simulations were conducted for different fiber’s lengths, filter bandwidth and different received power to get the best system performance. This helped to assess their impact on the link performance in terms of Bit Error Rate (BER.

  15. High efficiency diffractive grating coupler based on transferred silicon nanomembrane overlay on photonic waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Tapas Kumar; Zhou Weidong [University of Texas at Arlington, Department of Electrical Engineering, NanoFAB Center, Arlington, TX 76019-0072 (United States)

    2009-04-21

    We report here the design of a new type of high efficiency grating coupler, based on single crystalline Si nanomembrane overlay and stacking. Such high efficiency diffractive grating couplers are designed for the purpose of coupling light between single mode fibres and nanophotonic waveguides, and for the coupling between multiple photonic interconnect layers for compact three-dimensional vertical integration. Two-dimensional model simulation based on eigenmode expansion shows a diffractive power-up efficiency of 81% and a fibre coupling efficiency of 64%. With nanomembrane stacking, it is feasible to integrate the side-distributed Bragg reflector and bottom reflector, which can lead to the diffractive power-up efficiency and the fibre coupling efficiency of 97% and 73.5%, respectively. For a negatively detuned coupler, the bottom reflector is not needed, and the diffractive power-up efficiency can reach 98% over a large spectral range. The device is extremely tolerant to fabrication errors.

  16. Elastomeric polymer resonant waveguide grating based pressure sensor

    International Nuclear Information System (INIS)

    Song, Fuchuan; Xie, Antonio Jou; Seo, Sang-Woo

    2014-01-01

    In this paper, we demonstrate an elastomeric polymer resonant waveguide grating structure to be used as a pressure sensor. The applied pressure is measured by optical resonance spectrum peak shift. The sensitivity—as high as 86.74 pm psi −1 or 12.58 pm kPa −1 —has been experimentally obtained from a fabricated sensor. Potentially, the sensitivity of the demonstrated sensor can be tuned to different pressure ranges by the choices of elastic properties and layer thicknesses of the waveguide and cladding layers. The simulation results agree well with experimental results and indicate that the dominant effect on the sensor is the change of grating period when external pressure is applied. Based on the two-dimensional planar structure, the demonstrated sensor can be used to measure applied surface pressure optically, which has potential applications for optical ultrasound imaging and pressure wave detection/mapping

  17. Optical Fiber Thermometer Based on Fiber Bragg Gratings

    Science.gov (United States)

    Rosli, Ekbal Bin; Mohd. Noor, Uzer

    2018-03-01

    Fiber Bragg grating has generated much interest in use as sensors to measure strain, temperature, and other physical parameters. It also the most common component used to develop this sensor with the advantages of simple, intrinsic sensing elements, electrically passive operation, EMI immunity, high sensitivity, compact size and potentially low cost [6]. This paper reports the design of an optical fiber thermometer based on fiber Bragg gratings. The system was developed for detecting temperature and strain by monitoring the shift of Bragg wavelength. The shifting of Bragg wavelength is used to indicate the temperature and strain due to the change in the surrounding temperature and strain. When the temperature and strain reach the exact wavelength level of the system, the temperature and strain value will display on the Arduino liquid crystal display (LCD). The optical fiber will provide the broadband light source and after passing the FBG the Bragg wavelength into the optical spectrum analyzer (OSA). The system is based on FBG as a physical quantity sensor. The temperatures measured is taken from the water bath and that of the strain is provided by amount of slotted mass used. The outcome of this project is to characterize the Bragg wavelength shifting from the fiber Bragg grating output. As the conclusion, this project provides an efficient optical fiber thermometer in measuring temperature and strain in order to replace the use of conventional electrical instruments.

  18. Overview of diffraction gratings technologies for spaceflight satellites and ground-based telescopes

    Science.gov (United States)

    Cotel, A.; Liard, A.; Desserouer, F.; Pichon, P.

    2017-11-01

    The diffraction gratings are widely used in Space-flight satellites for spectrograph instruments or in ground-based telescopes in astronomy. The diffraction gratings are one of the key optical components of such systems and have to exhibit very high optical performances. HORIBA Jobin Yvon S.A.S. (part of HORIBA Group) is in the forefront of such gratings development for more than 40 years. During the past decades, HORIBA Jobin Yvon (HJY) has developed a unique expertise in diffraction grating design and manufacturing processes for holographic, ruled or etched gratings. We will present in this paper an overview of diffraction grating technologies especially designed for space and astronomy applications. We will firstly review the heritage of the company in this field with the space qualification of different grating types. Then, we will describe several key grating technologies developed for specific space or astronomy projects: ruled blazed low groove density plane reflection grating, high-groove density holographic toroidal and spherical grating, and finally transmission Fused Silica Etched (FSE) grism-assembled grating. We will not present the Volume Phase Holographic (VPHG) grating type which is used in Astronomy.

  19. Design of a sensitive grating-based phase contrast mammography prototype (Conference Presentation)

    Science.gov (United States)

    Arboleda Clavijo, Carolina; Wang, Zhentian; Köhler, Thomas; van Stevendaal, Udo; Martens, Gerhard; Bartels, Matthias; Villanueva-Perez, Pablo; Roessl, Ewald; Stampanoni, Marco

    2017-03-01

    Grating-based phase contrast mammography can help facilitate breast cancer diagnosis, as several research works have demonstrated. To translate this technique to the clinics, it has to be adapted to cover a large field of view within a limited exposure time and with a clinically acceptable radiation dose. This indicates that a straightforward approach would be to install a grating interferometer (GI) into a commercial mammography device. We developed a wave propagation based optimization method to select the most convenient GI designs in terms of phase and dark-field sensitivities for the Philips Microdose Mammography (PMM) setup. The phase sensitivity was defined as the minimum detectable breast tissue electron density gradient, whereas the dark-field sensitivity was defined as its corresponding signal-to-noise Ratio (SNR). To be able to derive sample-dependent sensitivity metrics, a visibility reduction model for breast tissue was formulated, based on previous research works on the dark-field signal and utilizing available Ultra-Small-Angle X-ray Scattering (USAXS) data and the outcomes of measurements on formalin-fixed breast tissue specimens carried out in tube-based grating interferometers. The results of this optimization indicate the optimal scenarios for each metric are different and fundamentally depend on the noise behavior of the signals and the visibility reduction trend with respect to the system autocorrelation length. In addition, since the inter-grating distance is constrained by the space available between the breast support and the detector, the best way we have to improve sensitivity is to count on a small G2 pitch.

  20. Underwater Acoustic Sensors Based on Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Giuseppe Parente

    2009-06-01

    Full Text Available We report on recent results obtained with a fiber optic hydrophone based on the intensity modulation of the laser light in a FBG (Fiber Bragg Grating under the influence of the sound pressure. In order to control the behavior of the hydrophone in terms of sensitivity and bandwidth, FBGs have been coated with proper materials, characterized by different elastic modulus and shapes. In particular, new experiments have been carried out using a cylindrical geometry with two different coating, showing that the sensitivity is not influenced by the shape but by the transversal dimension and the material characteristics of the coating.

  1. Microfiber-Based Bragg Gratings for Sensing Applications: A Review

    Directory of Open Access Journals (Sweden)

    Jun-Long Kou

    2012-06-01

    Full Text Available Microfiber-based Bragg gratings (MFBGs are an emerging concept in ultra-small optical fiber sensors. They have attracted great attention among researchers in the fiber sensing area because of their large evanescent field and compactness. In this review, the basic techniques for the fabrication of MFBGs are introduced first. Then, the sensing properties and applications of MFBGs are discussed, including measurement of refractive index (RI, temperature, and strain/force. Finally a summary of selected MFBG sensing elements from previous literature are tabulated.

  2. Graphene based silicon–air grating structure to realize electromagnetically-induced-transparency and slow light effect

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Buzheng; Liu, Huaiqing [Key Lab of All Optical Network & Advanced Telecommunication Network of EMC, Beijing Jiaotong University, Beijing 100044 (China); Institute of Lightwave Technology, Beijing Jiaotong University, Beijing 100044 (China); Ren, Guobin, E-mail: gbren@bjtu.edu.cn [Key Lab of All Optical Network & Advanced Telecommunication Network of EMC, Beijing Jiaotong University, Beijing 100044 (China); Institute of Lightwave Technology, Beijing Jiaotong University, Beijing 100044 (China); Yang, Yuguang; Ye, Shen; Pei, Li; Jian, Shuisheng [Key Lab of All Optical Network & Advanced Telecommunication Network of EMC, Beijing Jiaotong University, Beijing 100044 (China); Institute of Lightwave Technology, Beijing Jiaotong University, Beijing 100044 (China)

    2017-01-23

    Highlights: • The EIT and slow light effect are achieved by our novel graphene based structure. • Excellent tunability of wide wavelength range can be obtained only by a small change in Fermi energy level. • The group velocity of incident light is reduced to more than 1/600 of that in vacuum. • Position control is realized by designing a graded period grating. - Abstract: A broad band tunable graphene based silicon–air grating structure is proposed. Electromagnetically-induced-transparency (EIT) window can be successfully tuned by virtually setting the desired Fermi energy levels on graphene sheets. Carrier mobility plays an important role in modulating the resonant depth. Furthermore, by changing the grating periods, light can be trapped at corresponding resonant positions where slow down factor is relatively larger than in the previous works. This structure can be used as a highly tunable optoelectronic device such as optical filter, broad-band modulator, plasmonic switches and buffers.

  3. Effectiveness of X-ray grating interferometry for non-destructive inspection of packaged devices

    Science.gov (United States)

    Uehara, Masato; Yashiro, Wataru; Momose, Atsushi

    2013-10-01

    It is difficult to inspect packaged devices such as IC packages and power modules because the devices contain various components, such as semiconductors, metals, ceramics, and resin. In this paper, we demonstrated the effectiveness of X-ray grating interferometry (XGI) using a laboratory X-ray tube for the industrial inspection of packaged devices. The obtained conventional absorption image showed heavy-elemental components such as metal wires and electrodes, but the image did not reveal the defects in the light-elemental components. On the other hand, the differential phase-contrast image obtained by XGI revealed microvoids and scars in the encapsulant of the samples. The visibility contrast image also obtained by XGI showed some cracks in the ceramic insulator of power module sample. In addition, the image showed the silicon plate surrounded by the encapsulant having the same X-ray absorption coefficient. While these defects and components are invisible in the conventional industrial X-ray imaging, XGI thus has an attractive potential for the industrial inspection of the packaged devices.

  4. Electron cyclotron emission measurements by means of a grating polychromator on the large helical device

    International Nuclear Information System (INIS)

    Vries, P.C. de; Kawahata, K.; Nagayama, Y.; Inagaki, S.; Sasao, H.; Ito, Y.

    2001-01-01

    The electron cyclotron emission (ECE) spectrum at the large helical device (LHD) is measured by a 14-channel grating polychromator. During standard operation, the polychromator monitors second harmonic frequencies (100-150 GHz). At sufficient high density, the second harmonic X-mode polarisation is optically thick and can be used to determine the temperature profile. However, the large magnetic field shear in LHD affects the ECE polarisation. This effect has been studied numerically. The wave polarisation was found to rotate in the laboratory frame. Experiments have been carried out by means of a polarisation rotator in the diagnostic waveguide system, which confirmed the calculations. By a proper setting of the polarisation rotator, the rotation can be corrected and pure X-mode is detected. Temperature profiles have been measured successfully by the polychromator

  5. Electron cyclotron emission measurements by means of a grating polychromator on the Large Helical Device

    Energy Technology Data Exchange (ETDEWEB)

    Vries, P.C. de; Kawahata, K.; Nagayama, Y.; Inagaki, S.; Sasao, H.; Ito, Y. [National Inst. for Fusion Science, Toki, Gifu (Japan)

    2000-03-01

    The electron cyclotron emission (ECE) spectrum at the Large Helical Device (LHD) is measured by a 14-channel grating polychromator. During standard operation the polychromator monitors 2nd harmonic frequencies (100-150 GHz) with a spectral resolution of 1.5 GHz. At sufficient high density the 2nd harmonic X-mode polarization is optically thick and can be used to determine the temperature profile. However, the large magnetic field shear in LHD affects the ECE polarization. This effect has been studied numerically. The wave polarization was found to rotate in the laboratory frame. Experiments have been carried out by means of a polarization rotator in the diagnostic waveguide system, which confirmed the calculations. By a proper setting of the polarization rotator, the rotation can be corrected and pure X-mode is detected. Temperature profiles have been measured successfully by the polychromator. (author)

  6. Electron cyclotron emission measurements by means of a grating polychromator on the Large Helical Device

    International Nuclear Information System (INIS)

    Vries, P.C. de; Kawahata, K.; Nagayama, Y.; Inagaki, S.; Sasao, H.; Ito, Y.

    2000-01-01

    The electron cyclotron emission (ECE) spectrum at the Large Helical Device (LHD) is measured by a 14-channel grating polychromator. During standard operation the polychromator monitors 2nd harmonic frequencies (100-150 GHz) with a spectral resolution of 1.5 GHz. At sufficient high density the 2nd harmonic X-mode polarization is optically thick and can be used to determine the temperature profile. However, the large magnetic field shear in LHD affects the ECE polarization. This effect has been studied numerically. The wave polarization was found to rotate in the laboratory frame. Experiments have been carried out by means of a polarization rotator in the diagnostic waveguide system, which confirmed the calculations. By a proper setting of the polarization rotator, the rotation can be corrected and pure X-mode is detected. Temperature profiles have been measured successfully by the polychromator. (author)

  7. 16 channel 200 GHz arrayed waveguide grating based on Si nanowire waveguides

    International Nuclear Information System (INIS)

    Zhao Lei; An Junming; Zhang Jiashun; Song Shijiao; Wu Yuanda; Hu Xiongwei

    2011-01-01

    A 16 channel arrayed waveguide grating demultiplexer with 200 GHz channel spacing based on Si nanowire waveguides is designed. The transmission spectra response simulated by transmission function method shows that the device has channel spacing of 1.6 nm and crosstalk of 31 dB. The device is fabricated by 193 nm deep UV lithography in silicon-on-substrate. The demultiplexing characteristics are observed with crosstalk of 5-8 dB, central channel's insertion loss of 2.2 dB, free spectral range of 24.7 nm and average channel spacing of 1.475 nm. The cause of the spectral distortion is analyzed specifically. (semiconductor devices)

  8. Bite force measurement based on fiber Bragg grating sensor

    Science.gov (United States)

    Padma, Srivani; Umesh, Sharath; Asokan, Sundarrajan; Srinivas, Talabattula

    2017-10-01

    The maximum level of voluntary bite force, which results from the combined action of muscle of mastication, joints, and teeth, i.e., craniomandibular structure, is considered as one of the major indicators for the functional state of the masticatory system. Measurement of voluntary bite force provides useful data for the jaw muscle function and activity along with assessment of prosthetics. This study proposes an in vivo methodology for the dynamic measurement of bite force employing a fiber Bragg grating (FBG) sensor known as bite force measurement device (BFMD). The BFMD developed is a noninvasive intraoral device, which transduces the bite force exerted at the occlusal surface into strain variations on a metal plate. These strain variations are acquired by the FBG sensor bonded over it. The BFMD developed facilitates adjustment of the distance between the biting platform, which is essential to capture the maximum voluntary bite force at three different positions of teeth, namely incisor, premolar, and molar sites. The clinically relevant bite forces are measured at incisor, molar, and premolar position and have been compared against each other. Furthermore, the bite forces measured with all subjects are segregated according to gender and also compared against each other.

  9. High efficiency grating couplers based on shared process with CMOS MOSFETs

    International Nuclear Information System (INIS)

    Qiu Chao; Sheng Zhen; Wu Ai-Min; Wang Xi; Zou Shi-Chang; Gan Fu-Wan; Li Le; Albert Pang

    2013-01-01

    Grating couplers are widely investigated as coupling interfaces between silicon-on-insulator waveguides and optical fibers. In this work, a high-efficiency and complementary metal—oxide—semiconductor (CMOS) process compatible grating coupler is proposed. The poly-Si layer used as a gate in the CMOS metal—oxide—semiconductor field effect transistor (MOSFET) is combined with a normal fully etched grating coupler, which greatly enhances its coupling efficiency. With optimal structure parameters, a coupling efficiency can reach as high as ∼ 70% at a wavelength of 1550 nm as indicated by simulation. From the angle of fabrication, all masks and etching steps are shared between MOSFETs and grating couplers, thereby making the high performance grating couplers easily integrated with CMOS circuits. Fabrication errors such as alignment shift are also simulated, showing that the device is quite tolerant in fabrication. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  10. Nanoporous Polymeric Grating-Based Optical Biosensors (Preprint)

    National Research Council Canada - National Science Library

    Hsiao, Vincent K; Waldeisen, John R; Lloyd, Pamela F; Bunning, Timothy J; Huang, Tony J

    2007-01-01

    .... The fabrication process of the nanoporous polymeric grating involves holographic interference patterning and a functionalized pre-polymer syrup that facilitates the immobilization of biomolecules...

  11. Spherical grating spectrometers

    Science.gov (United States)

    O'Donoghue, Darragh; Clemens, J. Christopher

    2014-07-01

    We describe designs for spectrometers employing convex dispersers. The Offner spectrometer was the first such instrument; it has almost exclusively been employed on satellite platforms, and has had little impact on ground-based instruments. We have learned how to fabricate curved Volume Phase Holographic (VPH) gratings and, in contrast to the planar gratings of traditional spectrometers, describe how such devices can be used in optical/infrared spectrometers designed specifically for curved diffraction gratings. Volume Phase Holographic gratings are highly efficient compared to conventional surface relief gratings; they have become the disperser of choice in optical / NIR spectrometers. The advantage of spectrometers with curved VPH dispersers is the very small number of optical elements used (the simplest comprising a grating and a spherical mirror), as well as illumination of mirrors off axis, resulting in greater efficiency and reduction in size. We describe a "Half Offner" spectrometer, an even simpler version of the Offner spectrometer. We present an entirely novel design, the Spherical Transmission Grating Spectrometer (STGS), and discuss exemplary applications, including a design for a double-beam spectrometer without any requirement for a dichroic. This paradigm change in spectrometer design offers an alternative to all-refractive astronomical spectrometer designs, using expensive, fragile lens elements fabricated from CaF2 or even more exotic materials. The unobscured mirror layout avoids a major drawback of the previous generation of catadioptric spectrometer designs. We describe laboratory measurements of the efficiency and image quality of a curved VPH grating in a STGS design, demonstrating, simultaneously, efficiency comparable to planar VPH gratings along with good image quality. The stage is now set for construction of a prototype instrument with impressive performance.

  12. Optical spatial differentiator based on subwavelength high-contrast gratings

    Science.gov (United States)

    Dong, Zhewei; Si, Jiangnan; Yu, Xuanyi; Deng, Xiaoxu

    2018-04-01

    An optical spatial differentiator based on subwavelength high-contrast gratings (HCGs) is proposed experimentally. The spatial differentiation property of the subwavelength HCG is analyzed by calculating its spatial spectral transfer function based on the periodic waveguide theory. By employing the FDTD solutions, the performance of the subwavelength HCG spatial differentiator was investigated numerically. The subwavelength HCG differentiator with the thickness at the nanoscale was fabricated on the quartz substrate by electron beam lithography and Bosch deep silicon etching. Observed under an optical microscope with a CCD camera, the spatial differentiation of the incident field profile was obtained by the subwavelength HCG differentiator in transmission without Fourier lens. By projecting the images of slits, letter "X," and a cross on the subwavelength HCG differentiator, edge detections of images were obtained in transmission. With the nanoscale HCG structure and simple optical implementation, the proposed optical spatial differentiator provides the prospects for applications in optical computing systems and parallel data processing.

  13. Optimization of top coupling grating for very long wavelength QWIP based on surface plasmon

    Science.gov (United States)

    Wang, Guodong; Shen, Junling; Liu, Xiaolian; Ni, Lu; Wang, Saili

    2017-09-01

    The relative coupling efficiency of two-dimensional (2D) grating based on surface plasmon for very long wavelength quantum well infrared detector is analyzed by using the three-dimensional finite-difference time domain (3D-FDTD) method algorithm. The relative coupling efficiency with respect to the grating parameters, such as grating pitch, duty ratio, and grating thickness, is analyzed. The calculated results show that the relative coupling efficiency would reach the largest value for the 14.5 μm incident infrared light when taking the grating pitch as 4.4 μm, the duty ratio as 0.325, and the grating thickness as 0.07 μm, respectively.

  14. Bandwidth-Tunable Fiber Bragg Gratings Based on UV Glue Technique

    Science.gov (United States)

    Fu, Ming-Yue; Liu, Wen-Feng; Chen, Hsin-Tsang; Chuang, Chia-Wei; Bor, Sheau-Shong; Tien, Chuen-Lin

    2007-07-01

    In this study, we have demonstrated that a uniform fiber Bragg grating (FBG) can be transformed into a chirped fiber grating by a simple UV glue adhesive technique without shifting the reflection band with respect to the center wavelength of the FBG. The technique is based on the induced strain of an FBG due to the UV glue adhesive force on the fiber surface that causes a grating period variation and an effective index change. This technique can provide a fast and simple method of obtaining the required chirp value of a grating for applications in the dispersion compensators, gain flattening in erbium-doped fiber amplifiers (EDFAs) or optical filters.

  15. Study on temperature sensitivity of topological insulators based on long-period fiber grating

    Science.gov (United States)

    Luo, Jianhua; Zhao, Chenghai; Li, Jianbo; He, Mengdong

    2017-06-01

    Based on a long-period fiber grating, we conducted experimental research on the temperature sensitivity of topological insulators. The long-period fiber grating and topological insulators solution were encapsulated in a capillary tube using UV glue, and the temperature response was measured. Within a range of 35 to 75 centigrade, one resonance dip of a long-period fiber grating exhibits a redshift of 1.536 nm. The temperature sensitivity is about 7.7 times of an ordinary long-period fiber grating's sensitivity (0.005 nm/°C). A numerical simulation is also performed on the basis of the experiments.

  16. Simple design of slanted grating with simplified modal method.

    Science.gov (United States)

    Li, Shubin; Zhou, Changhe; Cao, Hongchao; Wu, Jun

    2014-02-15

    A simplified modal method (SMM) is presented that offers a clear physical image for subwavelength slanted grating. The diffraction characteristic of the slanted grating under Littrow configuration is revealed by the SMM as an equivalent rectangular grating, which is in good agreement with rigorous coupled-wave analysis. Based on the equivalence, we obtained an effective analytic solution for simplifying the design and optimization of a slanted grating. It offers a new approach for design of the slanted grating, e.g., a 1×2 beam splitter can be easily designed. This method should be helpful for designing various new slanted grating devices.

  17. Fibre Bragg grating based accelerometer with extended bandwidth

    International Nuclear Information System (INIS)

    Basumallick, Nandini; Biswas, Palas; Dasgupta, Kamal; Bandyopadhyay, Somnath; Chakraborty, Rajib; Chakraborty, Sushanta

    2016-01-01

    We have shown experimentally that the operable bandwidth of a fibre Bragg grating (FBG) based accelerometer can be extended significantly, without compromising its sensitivity, using a post-signal processing technique which involves frequency domain weighting. It has been demonstrated that using the above technique acceleration can be correctly interpreted even when the operating frequency encroaches on the region where the frequency response of the sensor is non-uniform. Two different excitation signals, which we often encounter in structural health monitoring applications, e.g. (i) a signal composed of multi-frequency components and (ii) a sinusoidal excitation with a frequency sweep, have been considered in our experiment. The results obtained have been compared with a piezo accelerometer. (paper)

  18. The cross waveguide grating: proposal, theory and applications.

    Science.gov (United States)

    Muñoz, Pascual; Pastor, Daniel; Capmany, José

    2005-04-18

    In this paper a novel grating-like integrated optics device is proposed, the Cross Waveguide Grating (XWG). The device is based upon a modified configuration of a traditional Arrayed Waveguide Grating (AWG). The Arrayed Waveguides part is changed, as detailed along this document, giving the device both the ability of multi/demultiplexing and power splitting/coupling. Design examples and transfer function simulations show good agreement with the presented theory. Finally, some of the envisaged applications are outlined.

  19. Temperature-independent fiber-Bragg-grating-based atmospheric pressure sensor

    Science.gov (United States)

    Zhang, Zhiguo; Shen, Chunyan; Li, Luming

    2018-03-01

    Atmospheric pressure is an important way to achieve a high degree of measurement for modern aircrafts, moreover, it is also an indispensable parameter in the meteorological telemetry system. With the development of society, people are increasingly concerned about the weather. Accurate and convenient atmospheric pressure parameters can provide strong support for meteorological analysis. However, electronic atmospheric pressure sensors currently in application suffer from several shortcomings. After an analysis and discussion, we propose an innovative structural design, in which a vacuum membrane box and a temperature-independent strain sensor based on an equal strength cantilever beam structure and fiber Bragg grating (FBG) sensors are used. We provide experimental verification of that the atmospheric pressure sensor device has the characteristics of a simple structure, lack of an external power supply, automatic temperature compensation, and high sensitivity. The sensor system has good sensitivity, which can be up to 100 nm/MPa, and repeatability. In addition, the device exhibits desired hysteresis.

  20. Measurement of a discontinuous object based on a dual-frequency grating

    Institute of Scientific and Technical Information of China (English)

    Qiao Nao-Sheng; Cai Xin-Hua; Yao Chun-Mei

    2009-01-01

    The dual-frequency grating measurement theory is proposed in order to carry out the measurement of a discontinuous object. Firstly, the reason why frequency spectra are produced by low frequency gratings and high frequency gratings in the field of frequency is analysed, and the relationship between the wrapped-phase and the unwrappingphase is discussed. Secondly, a method to combine the advantages of the two kinds of gratings is proposed: one stripe is produced in the mutation part of the object measured by a suitable low frequency grating designed by MATLAB, then the phase produced by the low frequency grating need not be unfolded. The integer series of stripes is produced by a high frequency grating designed by MATLAB based on the frequency ratio of the two kinds of gratings and the high frequency wrapped-phase, and the high frequency unwrapping-phase is then obtained. In order to verify the correctness of the theoretical analysis, a steep discontinuous object of 600×600 pixels and 10.00 mm in height is simulated and a discontinuous object of ladder shape which is 32.00 mm in height is used in experiment. Both the simulation and the experiment can restore the discontinuous object height accurately by using the dual-frequency grating measurement theory.

  1. All-optical switching based on optical fibre long period gratings modified bacteriorhodopsin

    Science.gov (United States)

    Korposh, S.; James, S.; Partridge, M.; Sichka, M.; Tatam, R.

    2018-05-01

    All-optical switching using an optical fibre long-period gating (LPG) modified with bacteriorhodopsin (bR) is demonstrated. The switching process is based on the photo-induced RI change of bR, which in turn changes the phase matching conditions of the mode coupling by the LPG, leading to modulation of the propagating light. The effect was studied with an LPG immersed into a bR solution and with LPGs coated with the bR films, deposited onto the LPGs using the layer-by-layer electrostatic self-assembly (LbL) method. The dependence of the all-optical switching efficiency upon the concentration of the bR solution and on the grating period of the LPG was also studied. In addition, an in-fibre Mach-Zehnder interferometer (MZI) composed of a cascaded LPG pair separated by 30 mm and modified with bR was used to enhance the wavelength range of all-optical switching. The switching wavelength is determined by the grating period of the LPG. Switching efficiencies of 16% and 35% were observed when an LPG and an MZI were immersed into bR solutions, respectively. The switching time for devices coated with bR-films was within 1 s, 10 times faster than that observed for devices immersed into bR solution.

  2. Tunable and reconfigurable multi-tap microwave photonic filter based on dynamic Brillouin gratings in fibers.

    Science.gov (United States)

    Sancho, J; Primerov, N; Chin, S; Antman, Y; Zadok, A; Sales, S; Thévenaz, L

    2012-03-12

    We propose and experimentally demonstrate new architectures to realize multi-tap microwave photonic filters, based on the generation of a single or multiple dynamic Brillouin gratings in polarization maintaining fibers. The spectral range and selectivity of the proposed periodic filters is extensively tunable, simply by reconfiguring the positions and the number of dynamic gratings along the fiber respectively. In this paper, we present a complete analysis of three different configurations comprising a microwave photonic filter implementation: a simple notch-type Mach-Zehnder approach with a single movable dynamic grating, a multi-tap performance based on multiple dynamic gratings and finally a stationary grating configuration based on the phase modulation of two counter-propagating optical waves by a common pseudo-random bit sequence (PRBS).

  3. Two-port connecting-layer-based sandwiched grating by a polarization-independent design.

    Science.gov (United States)

    Li, Hongtao; Wang, Bo

    2017-05-02

    In this paper, a two-port connecting-layer-based sandwiched beam splitter grating with polarization-independent property is reported and designed. Such the grating can separate the transmission polarized light into two diffraction orders with equal energies, which can realize the nearly 50/50 output with good uniformity. For the given wavelength of 800 nm and period of 780 nm, a simplified modal method can design a optimal duty cycle and the estimation value of the grating depth can be calculated based on it. In order to obtain the precise grating parameters, a rigorous coupled-wave analysis can be employed to optimize grating parameters by seeking for the precise grating depth and the thickness of connecting layer. Based on the optimized design, a high-efficiency two-port output grating with the wideband performances can be gained. Even more important, diffraction efficiencies are calculated by using two analytical methods, which are proved to be coincided well with each other. Therefore, the grating is significant for practical optical photonic element in engineering.

  4. Terahertz bandwidth photonic Hilbert transformers based on synthesized planar Bragg grating fabrication.

    Science.gov (United States)

    Sima, Chaotan; Gates, J C; Holmes, C; Mennea, P L; Zervas, M N; Smith, P G R

    2013-09-01

    Terahertz bandwidth photonic Hilbert transformers are proposed and experimentally demonstrated. The integrated device is fabricated via a direct UV grating writing technique in a silica-on-silicon platform. The photonic Hilbert transformer operates at bandwidths of up to 2 THz (~16 nm) in the telecom band, a 10-fold greater bandwidth than any previously reported experimental approaches. Achieving this performance requires detailed knowledge of the system transfer function of the direct UV grating writing technique; this allows improved linearity and yields terahertz bandwidth Bragg gratings with improved spectral quality. By incorporating a flat-top reflector and Hilbert grating with a waveguide coupler, an ultrawideband all-optical single-sideband filter is demonstrated.

  5. Near-infrared light-controlled tunable grating based on graphene/elastomer composites

    Science.gov (United States)

    Wang, Fei; Jia, Shuhai; Wang, Yonglin; Tang, Zhenhua

    2018-02-01

    A near-infrared (nIR) light actuated tunable transmission optical grating based on graphene nanoplatelet (GNP)/polydimethylsiloxane (PDMS) and PDMS is proposed. A simple fabrication protocol is studied that allows integration of the grating with the actuation mechanism; both components are made from soft elastomers, and this ensure the tunability and the light-driven operation of the grating. The resulting grating structure demonstrates continuous period tunability of 2.7% under an actuation power density of 220 mW cm-2 within a period of 3 s and also demonstrates a time-independent characteristic. The proposed infrared activated grating can be developed for wireless remote light splitting in bio/chemical sensing and optical telecommunications applications.

  6. Grating-based X-ray phase contrast for biomedical imaging applications

    International Nuclear Information System (INIS)

    Pfeiffer, Franz; Willner, Marian; Chabior, Michael; Herzen, Julia; Helmholtz-Zentrum Geesthacht, Geesthacht; Auweter, Sigrid; Reiser, Maximilian; Bamberg, Fabian

    2013-01-01

    In this review article we describe the development of grating-based X-ray phase-contrast imaging, with particular emphasis on potential biomedical applications of the technology. We review the basics of image formation in grating-based phase-contrast and dark-field radiography and present some exemplary multimodal radiography results obtained with laboratory X-ray sources. Furthermore, we discuss the theoretical concepts to extend grating-based multimodal radiography to quantitative transmission, phase-contrast, and dark-field scattering computed tomography. (orig.)

  7. Modeling optical transmissivity of graphene grate in on-chip silicon photonic device

    Directory of Open Access Journals (Sweden)

    Iraj S. Amiri

    2018-06-01

    Full Text Available A three-dimensional (3-D finite-difference-time-domain (FDTD analysis was used to simulate a silicon photonic waveguide. We have calculated power and transmission of the graphene used as single or multilayers to study the light transmission behavior. A new technique has been developed to define the straight silicon waveguide integrated with grate graphene layer. The waveguide has a variable grate spacing to be filled by the graphene layer. The number of graphene atomic layers varies between 100 and 1000 (or 380 nm and 3800 nm, the transmitted power obtained varies as ∼30% and ∼80%. The ∼99%, blocking of the light was occurred in 10,000 (or 38,000 nm atomic layers of the graphene grate. Keywords: Optical waveguide, Silicon waveguide, Grate, Graphene, Optical transmissivity

  8. Uniquely identifiable tamper-evident device using coupling between subwavelength gratings

    Science.gov (United States)

    Fievre, Ange Marie Patricia

    Reliability and sensitive information protection are critical aspects of integrated circuits. A novel technique using near-field evanescent wave coupling from two subwavelength gratings (SWGs), with the input laser source delivered through an optical fiber is presented for tamper evidence of electronic components. The first grating of the pair of coupled subwavelength gratings (CSWGs) was milled directly on the output facet of the silica fiber using focused ion beam (FIB) etching. The second grating was patterned using e-beam lithography and etched into a glass substrate using reactive ion etching (RIE). The slightest intrusion attempt would separate the CSWGs and eliminate near-field coupling between the gratings. Tampering, therefore, would become evident. Computer simulations guided the design for optimal operation of the security solution. The physical dimensions of the SWGs, i.e. period and thickness, were optimized, for a 650 nm illuminating wavelength. The optimal dimensions resulted in a 560 nm grating period for the first grating etched in the silica optical fiber and 420 nm for the second grating etched in borosilicate glass. The incident light beam had a half-width at half-maximum (HWHM) of at least 7 microm to allow discernible higher transmission orders, and a HWHM of 28 microm for minimum noise. The minimum number of individual grating lines present on the optical fiber facet was identified as 15 lines. Grating rotation due to the cylindrical geometry of the fiber resulted in a rotation of the far-field pattern, corresponding to the rotation angle of moire fringes. With the goal of later adding authentication to tamper evidence, the concept of CSWGs signature was also modeled by introducing random and planned variations in the glass grating. The fiber was placed on a stage supported by a nanomanipulator, which permitted three-dimensional displacement while maintaining the fiber tip normal to the surface of the glass substrate. A 650 nm diode laser was

  9. Analytic models of spectral responses of fiber-grating-based interferometers on FMC theory.

    Science.gov (United States)

    Zeng, Xiangkai; Wei, Lai; Pan, Yingjun; Liu, Shengping; Shi, Xiaohui

    2012-02-13

    In this paper the analytic models (AMs) of the spectral responses of fiber-grating-based interferometers are derived from the Fourier mode coupling (FMC) theory proposed recently. The interferometers include Fabry-Perot cavity, Mach-Zehnder and Michelson interferometers, which are constructed by uniform fiber Bragg gratings and long-period fiber gratings, and also by Gaussian-apodized ones. The calculated spectra based on the analytic models are achieved, and compared with the measured cases and those on the transfer matrix (TM) method. The calculations and comparisons have confirmed that the AM-based spectrum is in excellent agreement with the TM-based one and the measured case, of which the efficiency is improved up to ~2990 times that of the TM method for non-uniform-grating-based in-fiber interferometers.

  10. Summary of theoretical and experimental investigation of grating type, silicon photovoltaic cells. [using p-n junctions on light receiving surface of base crystal

    Science.gov (United States)

    Chen, L. Y.; Loferski, J. J.

    1975-01-01

    Theoretical and experimental aspects are summarized for single crystal, silicon photovoltaic devices made by forming a grating pattern of p/n junctions on the light receiving surface of the base crystal. Based on the general semiconductor equations, a mathematical description is presented for the photovoltaic properties of such grating-like structures in a two dimensional form. The resulting second order elliptical equation is solved by computer modeling to give solutions for various, reasonable, initial values of bulk resistivity, excess carrier concentration, and surface recombination velocity. The validity of the computer model is established by comparison with p/n devices produced by alloying an aluminum grating pattern into the surface of n-type silicon wafers. Current voltage characteristics and spectral response curves are presented for cells of this type constructed on wafers of different resistivities and orientations.

  11. The vertical-cavity surface-emitting laser incorporating a high contrast grating mirror as a sensing device

    Science.gov (United States)

    Marciniak, Magdalena; Gebski, Marcin; Piskorski, Łukasz; Dems, Maciej; Wasiak, M.; Panajotov, Krassimir; Lott, James A.; Czyszanowski, Tomasz

    2018-02-01

    We propose a novel optical sensing system based on one device that both emits and detects light consisting of a verticalcavity surface-emitting laser (VCSEL) incorporating an high contrast grating (HCG) as a top mirror. Since HCGs can be very sensitive to the optical properties of surrounding media, they can be used to detect gases and liquid. The presence of a gas or a liquid around an HCG mirror causes changes of the power reflectance of the mirror, which corresponds to changes of the VCSEL's cavity quality factor and current-voltage characteristic. By observation of the current-voltage characteristic we can collect information about the medium around the HCG. In this paper we investigate how the properties of the HCG mirror depend on the refractive index of the HCG surroundings. We present results of a computer simulation performed with a three-dimensional fully vectorial model. We consider silicon HCGs on silica and designed for a 1300 nm VCSEL emission wavelength. We demonstrate that our approach can be applied to other wavelengths and material systems.

  12. Fiber-optical accelerometers based on polymer optical fiber Bragg gratings

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Stefani, Alessio; Bang, Ole

    2010-01-01

    Fiber-optical accelerometers based on polymer optical fiber Bragg gratings (FBGs) are reported. We have written 3mm FBGs for 1550nm operation, characterized their temperature and strain response, and tested their performance in a prototype accelerometer.......Fiber-optical accelerometers based on polymer optical fiber Bragg gratings (FBGs) are reported. We have written 3mm FBGs for 1550nm operation, characterized their temperature and strain response, and tested their performance in a prototype accelerometer....

  13. Microfiber Bragg grating hydrogen sensor base on co-sputtered Pd/Ni composite film

    Science.gov (United States)

    Wang, Gaopeng; Yang, Minghong; Dai, Jixiang; Cheng, Cheng; Yuan, Yinqian

    2015-07-01

    A novel hydrogen sensor based on Pd/Ni co-sputtered coating on micro fiber Bragg grating (MFBG) is proposed and experimentally demonstrated. The microfiber is stretched uniformly and the Bragg grating is directly inscribed on the microfiber without hydrogen loading using 193 nm ArF excimer laser and a phase mask. Palladium and nickel coatings are co-sputtered on the micro fiber Bragg grating for hydrogen sensing. The MFBG hydrogen sensors are characterized concerning their response to the hydrogen, ambient temperature and ambient refractive index, respectively. The performance of the proposed MFBG hydrogen sensor is obviously enhanced, especially when compared to standard FBG hydrogen sensors.

  14. Excitation of surface electromagnetic waves in a graphene-based Bragg grating.

    Science.gov (United States)

    Sreekanth, Kandammathe Valiyaveedu; Zeng, Shuwen; Shang, Jingzhi; Yong, Ken-Tye; Yu, Ting

    2012-01-01

    Here, we report the fabrication of a graphene-based Bragg grating (one-dimensional photonic crystal) and experimentally demonstrate the excitation of surface electromagnetic waves in the periodic structure using prism coupling technique. Surface electromagnetic waves are non-radiative electromagnetic modes that appear on the surface of semi-infinite 1D photonic crystal. In order to fabricate the graphene-based Bragg grating, alternating layers of high (graphene) and low (PMMA) refractive index materials have been used. The reflectivity plot shows a deepest, narrow dip after total internal reflection angle corresponds to the surface electromagnetic mode propagating at the Bragg grating/air boundary. The proposed graphene based Bragg grating can find a variety of potential surface electromagnetic wave applications such as sensors, fluorescence emission enhancement, modulators, etc.

  15. Performance enhancement of thin film silicon solar cells based on distributed Bragg reflector & diffraction grating

    Directory of Open Access Journals (Sweden)

    R. S. Dubey

    2014-12-01

    Full Text Available The influence of various designing parameters were investigated and explored for high performance solar cells. Single layer grating based solar cell of 50 μm thickness gives maximum efficiency up to 24 % whereas same efficiency is achieved with the use of three bilayers grating based solar cell of 30 μm thickness. Remarkably, bilayer grating based solar cell design not only gives broadband absorption but also enhancement in efficiency with reduced cell thickness requirement. This absorption enhancement is attributed to the high reflection and diffraction from DBR and grating respectively. The obtained short-circuit current were 29.6, 32.9, 34.6 and 36.05 mA/cm2 of 5, 10, 20 and 30 μm cell thicknesses respectively. These presented designing efforts would be helpful to design and realize new generation of solar cells.

  16. Terahertz bandwidth all-optical Hilbert transformers based on long-period gratings.

    Science.gov (United States)

    Ashrafi, Reza; Azaña, José

    2012-07-01

    A novel, all-optical design for implementing terahertz (THz) bandwidth real-time Hilbert transformers is proposed and numerically demonstrated. An all-optical Hilbert transformer can be implemented using a uniform-period long-period grating (LPG) with a properly designed amplitude-only grating apodization profile, incorporating a single π-phase shift in the middle of the grating length. The designed LPG-based Hilbert transformers can be practically implemented using either fiber-optic or integrated-waveguide technologies. As a generalization, photonic fractional Hilbert transformers are also designed based on the same optical platform. In this general case, the resulting LPGs have multiple π-phase shifts along the grating length. Our numerical simulations confirm that all-optical Hilbert transformers capable of processing arbitrary optical signals with bandwidths well in the THz range can be implemented using feasible fiber/waveguide LPG designs.

  17. Optical fiber pressure sensor based on fiber Bragg grating

    Science.gov (United States)

    Song, Dongcao

    In oil field, it is important to measure the high pressure and temperature for down-hole oil exploration and well-logging, the available traditional electronic sensor is challenged due to the harsh, flammable environment. Recently, applications based on fiber Bragg grating (FBG) sensor in the oil industry have become a popular research because of its distinguishing advantages such as electrically passive operation, immunity to electromagnetic interference, high resolution, insensitivity to optical power fluctuation etc. This thesis is divided into two main sections. In the first section, the design of high pressure sensor based on FBG is described. Several sensing elements based on FBG for high pressure measurements have been proposed, for example bulk-modulus or free elastic modulus. But the structure of bulk-modulus and free elastic modulus is relatively complex and not easy to fabricate. In addition, the pressure sensitivity is not high and the repeatability of the structure has not been investigated. In this thesis, a novel host material of carbon fiber laminated composite (CFLC) for high pressure sensing is proposed. The mechanical characteristics including principal moduli in three directions and the shape repeatability are investigated. Because of it's Young's modulus in one direction and anisotropic characteristics, the pressure sensor made by CFLC has excellent sensitivity. This said structure can be used in very high pressure measurement due to carbon fiber composite's excellent shape repetition even under high pressure. The experimental results show high pressure sensitivity of 0.101nm/MPa and high pressure measurement up to 70MPa. A pressure sensor based on CFLC and FBG with temperature compensation has been designed. In the second section, the design of low pressure sensor based on FBG is demonstrated. Due to the trade off between measurement range and sensitivity, a sensor for lower pressure range needs more sensitivity. A novel material of carbon

  18. Modeling optical transmissivity of graphene grate in on-chip silicon photonic device

    Science.gov (United States)

    Amiri, Iraj S.; Ariannejad, M. M.; Jalil, M. A.; Ali, J.; Yupapin, P.

    2018-06-01

    A three-dimensional (3-D) finite-difference-time-domain (FDTD) analysis was used to simulate a silicon photonic waveguide. We have calculated power and transmission of the graphene used as single or multilayers to study the light transmission behavior. A new technique has been developed to define the straight silicon waveguide integrated with grate graphene layer. The waveguide has a variable grate spacing to be filled by the graphene layer. The number of graphene atomic layers varies between 100 and 1000 (or 380 nm and 3800 nm), the transmitted power obtained varies as ∼30% and ∼80%. The ∼99%, blocking of the light was occurred in 10,000 (or 38,000 nm) atomic layers of the graphene grate.

  19. Optical image hiding based on chaotic vibration of deformable moiré grating

    Science.gov (United States)

    Lu, Guangqing; Saunoriene, Loreta; Aleksiene, Sandra; Ragulskis, Minvydas

    2018-03-01

    Image hiding technique based on chaotic vibration of deformable moiré grating is presented in this paper. The embedded secret digital image is leaked in a form of a pattern of time-averaged moiré fringes when the deformable cover grating vibrates according to a chaotic law of motion with a predefined set of parameters. Computational experiments are used to demonstrate the features and the applicability of the proposed scheme.

  20. Fiber Optic Long Period Grating Based Sensor for Coconut Oil Adulteration Detection

    Directory of Open Access Journals (Sweden)

    T. M. Libish

    2010-03-01

    Full Text Available We report the development and demonstration of a Long-Period Grating (LPG based optical fiber sensor for determining the adulteration of coconut oil by palm oil. The fundamental principle of detection is the sensitive dependence of the resonance peaks of LPG on the changes of the refractive index of the environmental medium around the cladding surface of the grating. Refractive index sensing with LPGs employs light coupling between core and cladding modes in the grating section. The transmittance spectra of a long period grating element immersed in different mixtures of coconut oil and palm oil were recorded. Results show that resonance wavelengths and transmission intensities varied as a function of the adulteration level of coconut oil. Detection limit of adulteration was found to be 2 % for coconut oil–palm oil binary mixture.

  1. Beam-splitter switches based on zenithal bistable liquid-crystal gratings.

    Science.gov (United States)

    Zografopoulos, Dimitrios C; Beccherelli, Romeo; Kriezis, Emmanouil E

    2014-10-01

    The tunable optical diffractive properties of zenithal bistable nematic liquid-crystal gratings are theoretically investigated. The liquid-crystal orientation is rigorously solved via a tensorial formulation of the Landau-de Gennes theory and the optical transmission properties of the gratings are investigated via full-wave finite-element frequency-domain simulations. It is demonstrated that by proper design the two stable states of the grating can provide nondiffracting and diffracting operation, the latter with equal power splitting among different diffraction orders. An electro-optic switching mechanism, based on dual-frequency nematic materials, and its temporal dynamics are further discussed. Such gratings provide a solution towards tunable beam-steering and beam-splitting components with extremely low power consumption.

  2. Optical fibres sensor based in the intensity switch of a linear laser with two Bragg gratings

    International Nuclear Information System (INIS)

    Basurto P, M.A.; Kuzin, E.A.; Archundia B, C.; Marroquin, E.; May A, M.; Cerecedo N, H.H.; Sanchez M, J.J.; Tentori S, D.; Marquez B, I.; Shliagin, M.; Miridonov, S.

    2000-01-01

    In this work we propose a new configuration for an optical fiber temperature sensor, based on a linear type Er-doped fiber laser. The laser cavity consists of an Er-doped fiber and two identical Bragg gratings at the fiber ends (working as reflectors). Temperature changes are detected by measuring, through one of the gratings, the intensity variations at the system's output. When the temperature of one of the Bragg gratings is modified, a wavelength shift of its spectral reflectivity is observed. Hence, the laser emission intensity of the system is modified. We present experimental results of the intensity switch observed when the temperature difference between the gratings detunes their spectral reflectance. Making use of this effect it is possible to develop limit comparators to bound the temperature range for the object under supervision. This limiting work can be performed with a high sensitivity using a very simple interrogation procedure. (Author)

  3. Encapsulation process for diffraction gratings.

    Science.gov (United States)

    Ratzsch, Stephan; Kley, Ernst-Bernhard; Tünnermann, Andreas; Szeghalmi, Adriana

    2015-07-13

    Encapsulation of grating structures facilitates an improvement of the optical functionality and/or adds mechanical stability to the fragile structure. Here, we introduce novel encapsulation process of nanoscale patterns based on atomic layer deposition and micro structuring. The overall size of the encapsulated structured surface area is only restricted by the size of the available microstructuring and coating devices; thus, overcoming inherent limitations of existing bonding processes concerning cleanliness, roughness, and curvature of the components. Finally, the process is demonstrated for a transmission grating. The encapsulated grating has 97.5% transmission efficiency in the -1st diffraction order for TM-polarized light, and is being limited by the experimental grating parameters as confirmed by rigorous coupled wave analysis.

  4. Multi-resonance peaks fiber Bragg gratings based on largely-chirped structure

    Science.gov (United States)

    Chen, Chao; Zhang, Xuan-Yu; Wei, Wei-Hua; Chen, Yong-Yi; Qin, Li; Ning, Yong-Qiang; Yu, Yong-Sen

    2018-04-01

    A composite fiber Bragg grating (FBG) with multi-resonance peaks (MRPs) has been realized by using femtosecond (fs) laser point-by-point inscription in single-mode fiber. This device contains a segment of largely-chirped gratings with the ultrahigh chirp coefficients and a segment of uniform high-order gratings. The observed MRPs are distributed in an ultra-broadband wavelength range from 1200 nm to 1700 nm in the form of quasi-period or multi-peak-group. For the 8th-order MRPs-FBG, we studied the axial strain and high-temperature sensing characteristics of different resonance peaks experimentally. Moreover, we have demonstrated a multi-wavelength fiber lasers with three-wavelength stable output by using a 9th-order MRPs-FBG as the wavelength selector. This work is significant for the fabrication and functionalization of FBGs with complicated spectra characteristics.

  5. Long period grating based refractometer with polarization-sensitive interrogation

    International Nuclear Information System (INIS)

    Eftimov, T; Bock, W; Mikulic, P; Nikolova, K

    2010-01-01

    We propose a new scheme for the interrogation of long-period fiber gratings (LPGs) which makes use of their polarization properties. Polarization-sensitive interrogation was applied to detect changes due to changes of the external refractive index by using three wavelengths on the International Telecommunication Union (ITU) grid. We show that the new approach can allow for a greater sensitivity and can be used in combination with spectral multiplexing schemes

  6. Geometrical tuning art for entirely subwavelength grating waveguide based integrated photonics circuits.

    Science.gov (United States)

    Wang, Zheng; Xu, Xiaochuan; Fan, Donglei; Wang, Yaguo; Subbaraman, Harish; Chen, Ray T

    2016-05-05

    Subwavelength grating (SWG) waveguide is an intriguing alternative to conventional optical waveguides due to the extra degree of freedom it offers in tuning a few important waveguide properties, such as dispersion and refractive index. Devices based on SWG waveguides have demonstrated impressive performances compared to conventional waveguides. However, the high loss of SWG waveguide bends jeopardizes their applications in integrated photonic circuits. In this work, we propose a geometrical tuning art, which realizes a pre-distorted refractive index profile in SWG waveguide bends. The pre-distorted refractive index profile can effectively reduce the mode mismatch and radiation loss simultaneously, thus significantly reduce the bend loss. This geometry tuning art has been numerically optimized and experimentally demonstrated in present study. Through such tuning, the average insertion loss of a 5 μm SWG waveguide bend is reduced drastically from 5.43 dB to 1.10 dB per 90° bend for quasi-TE polarization. In the future, the proposed scheme will be utilized to enhance performance of a wide range of SWG waveguide based photonics devices.

  7. Low-loss curved subwavelength grating waveguide based on index engineering

    Science.gov (United States)

    Wang, Zheng; Xu, Xiaochuan; Fan, D. L.; Wang, Yaoguo; Chen, Ray T.

    2016-03-01

    Subwavelength grating (SWG) waveguide is an intriguing alternative to conventional optical waveguides due to its freedom to tune a few important waveguide properties such as dispersion and refractive index. Devices based on SWG waveguide have demonstrated impressive performances compared to those of conventional waveguides. However, the large loss of SWG waveguide bends jeopardizes their applications in integrated photonics circuits. In this work, we propose that a predistorted refractive index distribution in SWG waveguide bends can effectively decrease the mode mismatch noise and radiation loss simultaneously, and thus significantly reduce the bend loss. Here, we achieved the pre-distortion refractive index distribution by using trapezoidal silicon pillars. This geometry tuning approach is numerically optimized and experimentally demonstrated. The average insertion loss of a 5 μm SWG waveguide bend can be reduced drastically from 5.58 dB to 1.37 dB per 90° bend for quasi-TE polarization. In the future, the proposed approach can be readily adopted to enhance performance of an array of SWG waveguide-based photonics devices.

  8. [Research on demodulation system for human body temperature measurement of intelligent clothing based on arrayed waveguide grating].

    Science.gov (United States)

    Yu, Xiao-gang; Miao, Chang-yun; Li, Hong-qiang; Li, En-bang; Liu, Zhi-hui; Wei, Ke-jia

    2012-08-01

    A system for demodulating distributed fiber Bragg grating sensors of the intelligent clothing was researched and realized, which is based on arrayed waveguide grating. The principle of demodulation method based on arrayed waveguide grating was analyzed, intensity--demodulating method was used to interrogate the wavelength of the fiber Bragg grating based on the building up of an experimental platform, and demodulation experiment of pre and post series of fiber Bragg grating was completed. The results show that the wavelength demodulation of the system has high linearity for fiber Bragg grating, the system gives a wavelength accuracy of 0.001 nm, and demodulation error caused by crosstalk between different sensors is 0.0005 nm. The measurement error of human body temperature is +/- 0.16 degrees C. It can be applied to the human body temperature measurement.

  9. Reflectors and tuning elements for widely-tunable GaAs-based sampled grating DBR lasers

    Science.gov (United States)

    Brox, O.; Wenzel, H.; Della Case, P.; Tawfieq, M.; Sumpf, B.; Weyers, M.; Knigge, A.

    2018-02-01

    Widely-tunable lasers without moving parts are attractive light sources for sensors in industry and biomedicine. In contrast to InP based sampled grating (SG) distributed Bragg reflector (DBR) diode lasers which are commercially available, shorter wavelength GaAs SG-DBR lasers are still under development. One reason is the difficulty to integrate gratings with coupling coefficients that are high enough for functional grating bursts with lengths below 10 μm. Recently we have demonstrated > 20 nm wide quasi-continuous tuning with a GaAs based SG-DBR laser emitting around 975 nm. Wavelength selective reflectors are realized with SGs having different burst periods for the front and back mirrors. Thermal tuning elements (resistors) which are placed on top of the SG allow the control of the spectral positions of the SG reflector combs and hence to adjust the Vernier mode. In this work we characterize subsections of the developed SG-DBR laser to further improve its performance. We study the impact of two different vertical structures (with vertical far field FWHMs of 41° and 24°) and two grating orders on the coupling coefficient. Gratings with coupling coefficients above 350 cm-1 have been integrated into SG-DBR lasers. We also examine electronic tuning elements (a technique which is typically applied in InP based SG-DBR lasers and allows tuning within nanoseconds) and discuss the limitations in the GaAs material system

  10. Scatter measurement and correction method for cone-beam CT based on single grating scan

    Science.gov (United States)

    Huang, Kuidong; Shi, Wenlong; Wang, Xinyu; Dong, Yin; Chang, Taoqi; Zhang, Hua; Zhang, Dinghua

    2017-06-01

    In cone-beam computed tomography (CBCT) systems based on flat-panel detector imaging, the presence of scatter significantly reduces the quality of slices. Based on the concept of collimation, this paper presents a scatter measurement and correction method based on single grating scan. First, according to the characteristics of CBCT imaging, the scan method using single grating and the design requirements of the grating are analyzed and figured out. Second, by analyzing the composition of object projection images and object-and-grating projection images, the processing method for the scatter image at single projection angle is proposed. In addition, to avoid additional scan, this paper proposes an angle interpolation method of scatter images to reduce scan cost. Finally, the experimental results show that the scatter images obtained by this method are accurate and reliable, and the effect of scatter correction is obvious. When the additional object-and-grating projection images are collected and interpolated at intervals of 30 deg, the scatter correction error of slices can still be controlled within 3%.

  11. Interrogation of weak Bragg grating sensors based on dual-wavelength differential detection.

    Science.gov (United States)

    Cheng, Rui; Xia, Li

    2016-11-15

    It is shown that for weak Bragg gratings the logarithmic ratio of reflected intensities at any two wavelengths within the spectrum follows a linear relationship with the Bragg wavelength shift, with a slope proportional to their wavelength spacing. This finding is exploited to develop a flexible, efficient, and cheap interrogation solution of weak fiber Bragg grating (FBGs), especially ultra-short FBGs, in distributed sensing based on dual-wavelength differential detection. The concept is experimentally studied in both single and distributed sensing systems with ultra-short FBG sensors. The work may form the basis of new and promising FBG interrogation techniques based on detecting discrete rather than continuous spectra.

  12. 1-D grating based SPR biosensor for the detection of lung cancer biomarkers using Vroman effect

    Science.gov (United States)

    Teotia, Pradeep Kumar; Kaler, R. S.

    2018-01-01

    Grating based surface plasmon resonance waveguide biosensor have been reported for the detection of lung cancer biomarkers using Vroman effect. The proposed grating based multilayered biosensor is designed with high detection accuracy for Epidermal growth factor receptor (EGFR) and also analysed to show high detection accuracy with acceptable sensitivity for both cancer biomarkers. The introduction of periodic grating with multilayer metals generates a good resonance that make it possible for early detection of cancerous cells. Using finite difference time domain method, it is observed wavelength of biosensor get red-shifted on variations of the refractive index due to the presence of both the cancerous bio-markers. The reported detection accuracy and sensitivity of proposed biosensor is quite acceptable for both lung cancer biomarkers i.e. Carcinoembryonic antigen (CEA) and Epidermal growth factor receptor (EGFR) which further offer us label free early detection of lung cancer using these biomarkers.

  13. Salinity measurement in water environment with a long period grating based interferometer

    International Nuclear Information System (INIS)

    Possetti, G R C; Kamikawachi, R C; Muller, M; Fabris, J L; Prevedello, C L

    2009-01-01

    In this work, a comparative study of the behaviour of an in-fibre Mach–Zehnder interferometer for salinity measurement in a water solution is presented. The fibre transducer is composed of two nearly identical long period gratings forming an in-series 7.38 cm long device written in the same fibre optic. Two inorganic and one organic salts (NaCl, KCl, NaCOOH) were characterized within the concentration range from 0 to 150 g L −1 . For the long period grating interferometer, the average obtained sensitivities were −6.61, −5.58 and −3.83 pm/(g L −1 ) for the above salts, respectively, or equivalently −40.8, −46.5 and −39.1 nm RIU −1 . Salinity measured by means of fibre refractometry is compared with measurements obtained using an Abbe refractometer as well as via electrical conductivity. For the long period grating refractometer, the best resolutions attained were 1.30, 1.54 and 2.03 g of salt per litre for NaCl, KCl and NaCOOH, respectively, about two times better than the resolutions obtained by the Abbe refractometer. An average thermal sensitivity of 53 pm °C −1 was measured for the grating transducer immersed in water, indicating the need for the thermal correction of the sensor. Resolutions for the same ionic constituent in different salts are also analysed

  14. Fluoride contamination sensor based on optical fiber grating technology

    Science.gov (United States)

    Jadhav, Mangesh S.; Laxmeshwar, Lata S.; Akki, Jyoti F.; Raikar, P. U.; Kumar, Jitendra; Prakash, Om; Raikar, U. S.

    2017-11-01

    A number of distinct advantages of the optical fiber technology in the field of sensors and communications which leads to enormous applications. Fiber Bragg grating (FBG) developed from the fabrication of photosensitive fiber through phase mask technique is used in the present report. The designed fiber sensor used for the detection and determination of contaminants in drinking water at ppm & ppb level and it is considered as a special type of concentration sensor. The test samples of drinking water have been collected from different regions. In this paper we have calibrated the FBG sensor to detect Flouride concentration in drinking water in the range of 0.05-8 ppm. According to WHO, the normal range of fluoride content in drinking water is about 0.7 ppm to 1.5 ppm. The results for resultant spectral shifts for test samples are closely agree with standard values.

  15. Optical microwave filter based on spectral slicing by use of arrayed waveguide gratings.

    Science.gov (United States)

    Pastor, Daniel; Ortega, Beatriz; Capmany, José; Sales, Salvador; Martinez, Alfonso; Muñoz, Pascual

    2003-10-01

    We have experimentally demonstrated a new optical signal processor based on the use of arrayed waveguide gratings. The structure exploits the concept of spectral slicing combined with the use of an optical dispersive medium. The approach presents increased flexibility from previous slicing-based structures in terms of tunability, reconfiguration, and apodization of the samples or coefficients of the transversal optical filter.

  16. A high spatial resolution distributed optical fiber grating sensing system based on OFDR

    Science.gov (United States)

    Dong, Ke; Xiong, Yuchuan; Wen, Hongqiao; Tong, Xinlin; Zhang, Cui; Deng, Chengwei

    2017-10-01

    A distributed optical fiber grating sensing system with large capacity and high spatial resolution is presented. Since highdensity identical weak grating array was utilized as sensing fiber, the multiplexing number was greatly increased, meanwhile, optical frequency domain reflectometry (OFDR) technology was used to implement high resolution distributed sensing system. In order to eliminate the nonlinear effect of tunable light source, a windowed FFT algorithm based on cubic spline interpolation was applied. The feasibility of the algorithm was experimentally testified, ultimately, the spatial resolution of system can reach mm-level. The influence of the crosstalk signal in the grating array on the OFDR system was analyzed. A method that a long enough delay fiber was added before the first FBG to remove crosstalk signal was proposed. The experiment was verified using an optical fiber with 113 uniform Bragg gratings at an interval of 10cm whose reflectivity are less than 1%. It demonstrates that crosstalk signal and measurement signal can be completely separated in the distance domain after adding a long enough delay fiber. Finally, the temperature experiment of distributed grating sensing system was carried out. The results display that each raster's center wavelength in the fiber link is independent of each other and the center wavelength drift has a good linear relationship with the temperature. The sensitivity of linear fitting is equal to 11.1pm/°C.

  17. Intensity liquid level sensor based on multimode interference and fiber Bragg grating

    International Nuclear Information System (INIS)

    Oliveira, Ricardo; Aristilde, Stenio; Osório, Jonas H; Cordeiro, Cristiano M B; Franco, Marcos A R; Bilro, Lúcia; Nogueira, Rogério N

    2016-01-01

    In this paper an intensity liquid level sensor based on a single-mode—no-core—single-mode (SMS) fiber structure together with a Bragg grating inscribed in the later single mode fiber is proposed. As the no-core fiber is sensitive to the external refractive index, the SMS spectral response will be shifted related to the length of no-core fiber that is immersed in a liquid. By positioning the FBG central wavelength at the spectral region of the SMS edge filter, it is possible to measure the liquid level using the reflected FBG peak power through an intensity-based approach. The sensor is also self-referenced using the peak power of another FBG that is placed before and far from the sensing part. The temperature error analysis was also studied revealing that the sensor can operate in environments where the temperature changes are minimal. The possibility to use a second setup that makes the whole device temperature insensitive is also discussed. (paper)

  18. Quantitative measurement of phase variation amplitude of ultrasonic diffraction grating based on diffraction spectral analysis

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Meiyan, E-mail: yphantomohive@gmail.com; Zeng, Yingzhi; Huang, Zuohua, E-mail: zuohuah@163.com [Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou, Guangdong 510006 (China)

    2014-09-15

    A new method based on diffraction spectral analysis is proposed for the quantitative measurement of the phase variation amplitude of an ultrasonic diffraction grating. For a traveling wave, the phase variation amplitude of the grating depends on the intensity of the zeroth- and first-order diffraction waves. By contrast, for a standing wave, this amplitude depends on the intensity of the zeroth-, first-, and second-order diffraction waves. The proposed method is verified experimentally. The measured phase variation amplitude ranges from 0 to 2π, with a relative error of approximately 5%. A nearly linear relation exists between the phase variation amplitude and driving voltage. Our proposed method can also be applied to ordinary sinusoidal phase grating.

  19. Monte Carlo simulation of grating-based neutron phase contrast imaging at CPHS

    International Nuclear Information System (INIS)

    Zhang Ran; Chen Zhiqiang; Huang Zhifeng; Xiao Yongshun; Wang Xuewu; Wie Jie; Loong, C.-K.

    2011-01-01

    Since the launching of the Compact Pulsed Hadron Source (CPHS) project of Tsinghua University in 2009, works have begun on the design and engineering of an imaging/radiography instrument for the neutron source provided by CPHS. The instrument will perform basic tasks such as transmission imaging and computerized tomography. Additionally, we include in the design the utilization of coded-aperture and grating-based phase contrast methodology, as well as the options of prompt gamma-ray analysis and neutron-energy selective imaging. Previously, we had implemented the hardware and data-analysis software for grating-based X-ray phase contrast imaging. Here, we investigate Geant4-based Monte Carlo simulations of neutron refraction phenomena and then model the grating-based neutron phase contrast imaging system according to the classic-optics-based method. The simulated experimental results of the retrieving phase shift gradient information by five-step phase-stepping approach indicate the feasibility of grating-based neutron phase contrast imaging as an option for the cold neutron imaging instrument at the CPHS.

  20. Angle transducer based on fiber Bragg gratings able for tunnel auscultation

    Science.gov (United States)

    Quintela, A.; Lázaro, J. M.; Quintela, M. A.; Mirapeix, J.; Muñoz-Berti, V.; López-Higuera, J. M.

    2010-09-01

    In this paper an angle transducer based on Fiber Bragg Grating (FBG) is presented. Two gratings are glued to a metallic platen, one in each side. It is insensitive to temperature changes, given that the temperature shifts affect equally to both FBG. When the platen is uniformly bent an uniform strain appears in both sides of the platen. It depends on the bend angle and the platen length and thickness. The transducer has been designed to be used in the auscultation of tunnels during their construction process and during their live time. The transducer design and its characterization are presented.

  1. Optical double-image cryptography based on diffractive imaging with a laterally-translated phase grating.

    Science.gov (United States)

    Chen, Wen; Chen, Xudong; Sheppard, Colin J R

    2011-10-10

    In this paper, we propose a method using structured-illumination-based diffractive imaging with a laterally-translated phase grating for optical double-image cryptography. An optical cryptosystem is designed, and multiple random phase-only masks are placed in the optical path. When a phase grating is laterally translated just before the plaintexts, several diffraction intensity patterns (i.e., ciphertexts) can be correspondingly obtained. During image decryption, an iterative retrieval algorithm is developed to extract plaintexts from the ciphertexts. In addition, security and advantages of the proposed method are analyzed. Feasibility and effectiveness of the proposed method are demonstrated by numerical simulation results. © 2011 Optical Society of America

  2. Fiber-optical microphones and accelerometers based on polymer optical fiber Bragg gratings

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Stefani, Alessio; Bang, Ole

    2010-01-01

    Polymer optical fibers (POFs) are ideal for applications as the sensing element in fiber-optical microphones and accelerometers based on fiber Bragg gratings (FBGs) due to their reduced Young’s Modulus of 3.2GPa, compared to 72GPa of Silica. To maximize the sensitivity and the dynamic range...... of the device the outer diameter and the length of the sensing fiber segment should be as small as possible. To this end we have fabricated 3mm FBGs in single-mode step-index POFs of diameter 115 micron, using 325nm UV writing and a phase-mask technique. 6mm POF sections with FBGs in the center have been glued...... to standard Silica SMF28 fibers. These POF FBGs have been characterized in terms of temperature and strain to find operating regimes with no hysteresis. Commercial fast wavelength interrogators (KHz) are shown to be able to track the thin POF FBGs and they are finally applied in a prototype accelerometer...

  3. Contextual Multivariate Segmentation of Pork Tissue from Grating-Based Multimodal X-Ray Tomography

    DEFF Research Database (Denmark)

    Einarsdottir, Hildur; Nielsen, Mikkel S.; Ersbøll, Bjarne Kjær

    2013-01-01

    have made novel X-ray image modalities available, where the refraction and scattering of X-rays is obtained simultaneously with the absorption properties, providing enhanced contrast for soft biological tissues. This paper demonstrates how data obtained from grating-based imaging can be segmented...

  4. Grating-based X-ray tomography of 3D food structures

    DEFF Research Database (Denmark)

    Miklos, Rikke; Nielsen, Mikkel Schou; Einarsdottir, Hildur

    2016-01-01

    A novel grating based X-ray phase-contrast tomographic method has been used to study how partly substitution of meat proteins with two different types of soy proteins affect the structure of the formed protein gel in meat emulsions. The measurements were performed at the Swiss synchrotron radiati...

  5. HF-based clad etching of fibre Bragg grating and its utilization in ...

    Indian Academy of Sciences (India)

    2014-02-09

    Feb 9, 2014 ... Abstract. This paper presents a fiber Bragg grating (FBG) based sensor to study the concentration of laser dye in dye–ethanol solution. The FBG used in this experiment is indigenously developed using 255 nm UV radiations from copper vapour laser. The cladding of the FBG was partially removed using ...

  6. Design of an ultrafast all-optical differentiator based on a fiber Bragg grating in transmission.

    Science.gov (United States)

    Preciado, Miguel A; Muriel, Miguel A

    2008-11-01

    We propose and analyze a first-order optical differentiator based on a fiber Bragg grating (FBG) in transmission. It is shown in the examples that a simple uniform-period FBG in a very strong coupling regime (maximum reflectivity very close to 100%) can perform close to ideal temporal differentiation of the complex envelope of an arbitrary-input optical signal.

  7. Ultrafast all-optical integrator based on a fiber Bragg grating: proposal and design.

    Science.gov (United States)

    Preciado, Miguel A; Muriel, Miguel A

    2008-06-15

    We demonstrate a simple technique for the implementation of an all-optical integrator based on a uniform-period fiber Bragg grating (FBG) in reflection that is designed to present a decreasing exponential impulse response. The proposed FBG integrator is readily feasible and can perform close to ideal integration of few-picosecond and subpicosecond pulses.

  8. Polymer PCF Bragg grating sensors based on poly(methyl methacrylate) and TOPAS cyclic olefin copolymer

    DEFF Research Database (Denmark)

    Johnson, Ian P; Webb, David J; Kalli, Kyriacos

    2011-01-01

    mode PCF with a core diameter of 6μm based on TOPAS cyclic olefin copolymer. Bragg grating inscription was achieved using a 30mW continuous wave 325nm helium cadmium laser. Both TOPAS and PMMA fibre have a large attenuation of around 1dB/cm in the 1550nm spectral region, limiting fibre lengths...

  9. Study of gain-coupled distributed feedback laser based on high order surface gain-coupled gratings

    Science.gov (United States)

    Gao, Feng; Qin, Li; Chen, Yongyi; Jia, Peng; Chen, Chao; Cheng, LiWen; Chen, Hong; Liang, Lei; Zeng, Yugang; Zhang, Xing; Wu, Hao; Ning, Yongqiang; Wang, Lijun

    2018-03-01

    Single-longitudinal-mode, gain-coupled distributed feedback (DFB) lasers based on high order surface gain-coupled gratings are achieved. Periodic surface metal p-contacts with insulated grooves realize gain-coupled mechanism. To enhance gain contrast in the quantum wells without the introduction of effective index-coupled effect, groove length and depth were well designed. Our devices provided a single longitudinal mode with the maximum CW output power up to 48.8 mW/facet at 971.31 nm at 250 mA without facet coating, 3dB linewidth (39 dB). Optical bistable characteristic was observed with a threshold current difference. Experimentally, devices with different cavity lengths were contrasted on power-current and spectrum characteristics. Due to easy fabrication technique and stable performance, it provides a method of fabricating practical gain-coupled distributed feedback lasers for commercial applications.

  10. Revisiting Bragg's X-ray microscope: scatter based optical transient grating detection of pulsed ionising radiation.

    Science.gov (United States)

    Fullagar, Wilfred K; Paganin, David M; Hall, Chris J

    2011-06-01

    Transient optical gratings for detecting ultrafast signals are routine for temporally resolved photochemical investigations. Many processes can contribute to the formation of such gratings; we indicate use of optically scattering centres that can be formed with highly variable latencies in different materials and devices using ionising radiation. Coherent light scattered by these centres can form the short-wavelength-to-optical-wavelength, incoherent-to-coherent basis of a Bragg X-ray microscope, with inherent scope for optical phasing. Depending on the dynamics of the medium chosen, the way is open to both ultrafast pulsed and integrating measurements. For experiments employing brief pulses, we discuss high-dynamic-range short-wavelength diffraction measurements with real-time optical reconstructions. Applications to optical real-time X-ray phase-retrieval are considered. Copyright © 2010 Elsevier B.V. All rights reserved.

  11. Asphaltene based photovoltaic devices

    Science.gov (United States)

    Chianelli, Russell R.; Castillo, Karina; Gupta, Vipin; Qudah, Ali M.; Torres, Brenda; Abujnah, Rajib E.

    2016-03-22

    Photovoltaic devices and methods of making the same, are disclosed herein. The cell comprises a photovoltaic device that comprises a first electrically conductive layer comprising a photo-sensitized electrode; at least one photoelectrochemical layer comprising metal-oxide particles, an electrolyte solution comprising at least one asphaltene fraction, wherein the metal-oxide particles are optionally dispersed in a surfactant; and a second electrically conductive layer comprising a counter-electrode, wherein the second electrically conductive layer comprises one or more conductive elements comprising carbon, graphite, soot, carbon allotropes or any combinations thereof.

  12. Research on robot navigation vision sensor based on grating projection stereo vision

    Science.gov (United States)

    Zhang, Xiaoling; Luo, Yinsheng; Lin, Yuchi; Zhu, Lei

    2016-10-01

    A novel visual navigation method based on grating projection stereo vision for mobile robot in dark environment is proposed. This method is combining with grating projection profilometry of plane structured light and stereo vision technology. It can be employed to realize obstacle detection, SLAM (Simultaneous Localization and Mapping) and vision odometry for mobile robot navigation in dark environment without the image match in stereo vision technology and without phase unwrapping in the grating projection profilometry. First, we research the new vision sensor theoretical, and build geometric and mathematical model of the grating projection stereo vision system. Second, the computational method of 3D coordinates of space obstacle in the robot's visual field is studied, and then the obstacles in the field is located accurately. The result of simulation experiment and analysis shows that this research is useful to break the current autonomous navigation problem of mobile robot in dark environment, and to provide the theoretical basis and exploration direction for further study on navigation of space exploring robot in the dark and without GPS environment.

  13. Subwavelength Gold Grating as Polarizers Integrated with InP-Based InGaAs Sensors.

    Science.gov (United States)

    Wang, Rui; Li, Tao; Shao, Xiumei; Li, Xue; Huang, Xiaqi; Shao, Jinhai; Chen, Yifang; Gong, Haimei

    2015-07-08

    There are currently growing needs for polarimetric imaging in infrared wavelengths for broad applications in bioscience, communications and agriculture, etc. Subwavelength metallic gratings are capable of separating transverse magnetic (TM) mode from transverse electric (TE) mode to form polarized light, offering a reliable approach for the detection in polarization way. This work aims to design and fabricate subwavelength gold gratings as polarizers for InP-based InGaAs sensors in 1.0-1.6 μm. The polarization capability of gold gratings on InP substrate with pitches in the range of 200-1200 nm (fixed duty cycle of 0.5) has been systematically studied by both theoretical modeling with a finite-difference time-domain (FDTD) simulator and spectral measurements. Gratings with 200 nm lines/space in 100-nm-thick gold have been fabricated by electron beam lithography (EBL). It was found that subwavelength gold gratings directly integrated on InP cannot be applied as good polarizers, because of the existence of SPP modes in the detection wavelengths. An effective solution has been found by sandwiching the Au/InP bilayer using a 200 nm SiO2 layer, leading to significant improvement in both TM transmission and extinction ratio. At 1.35 μm, the improvement factors are 8 and 10, respectively. Therefore, it is concluded that the Au/SiO2/InP trilayer should be a promising candidate of near-infrared polarizers for the InP-based InGaAs sensors.

  14. Revisiting Bragg's X-ray microscope: Scatter based optical transient grating detection of pulsed ionising radiation

    International Nuclear Information System (INIS)

    Fullagar, Wilfred K.; Paganin, David M.; Hall, Chris J.

    2011-01-01

    Transient optical gratings for detecting ultrafast signals are routine for temporally resolved photochemical investigations. Many processes can contribute to the formation of such gratings; we indicate use of optically scattering centres that can be formed with highly variable latencies in different materials and devices using ionising radiation. Coherent light scattered by these centres can form the short-wavelength-to-optical-wavelength, incoherent-to-coherent basis of a Bragg X-ray microscope, with inherent scope for optical phasing. Depending on the dynamics of the medium chosen, the way is open to both ultrafast pulsed and integrating measurements. For experiments employing brief pulses, we discuss high-dynamic-range short-wavelength diffraction measurements with real-time optical reconstructions. Applications to optical real-time X-ray phase-retrieval are considered. -- Research highlights: → It is timely that the concept of Bragg's X-ray microscope be revisited. → Transient gratings can be used for X-ray all-optical information processing. → Applications to optical real-time X-ray phase-retrieval are considered.

  15. Fiber-laser-based, green-pumped, picosecond optical parametric oscillator using fan-out grating PPKTP.

    Science.gov (United States)

    Chaitanya Kumar, S; Parsa, S; Ebrahim-Zadeh, M

    2016-01-01

    We report a stable, Yb-fiber-laser-based, green-pumped, picosecond optical parametric oscillator (OPO) for the near-infrared based on periodically poled potassium titanyl phosphate (PPKTP) nonlinear crystal, using fan-out grating design and operating near room temperature. The OPO is continuously tunable across 726-955 nm in the signal and 1201-1998 nm in the idler, resulting in a total signal plus idler wavelength coverage of 1026 nm by grating tuning at a fixed temperature. The device generates up to 580 mW of average power in the signal at 765 nm and 300 mW in the idler at 1338 nm, with an overall extraction efficiency of up to 52% and a pump depletion >76%. The extracted signal at 765 nm and idler at 1746 nm exhibit excellent passive power stability better than 0.5% and 0.8% rms, respectively, over 1 h with good beam quality in TEM00 mode profile. The output signal pulses have a Gaussian temporal duration of 13.2 ps, with a FWHM spectral bandwidth of 3.4 nm at 79.5 MHz repetition rate. Power scaling limitations of the OPO due to the material properties of PPKTP are studied.

  16. Phasor analysis of binary diffraction gratings with different fill factors

    International Nuclear Information System (INIS)

    MartInez, Antonio; Sanchez-Lopez, Ma del Mar; Moreno, Ignacio

    2007-01-01

    In this work, we present a simple analysis of binary diffraction gratings with different slit widths relative to the grating period. The analysis is based on a simple phasor technique directly derived from the Huygens principle. By introducing a slit phasor and a grating phasor, the intensity of the diffracted orders and the grating's resolving power can be easily obtained without applying the usual Fourier transform operations required for these calculations. The proposed phasor technique is mathematically equivalent to the Fourier transform calculation of the diffraction order amplitude, and it can be useful to explain binary diffraction gratings in a simple manner in introductory physics courses. This theoretical analysis is illustrated with experimental results using a liquid crystal device to display diffraction gratings with different fill factors

  17. Phasor analysis of binary diffraction gratings with different fill factors

    Energy Technology Data Exchange (ETDEWEB)

    MartInez, Antonio [Departamento de Ciencia de Materiales, Optica y TecnologIa Electronica, Universidad Miguel Hernandez, 03202 Elche (Spain); Sanchez-Lopez, Ma del Mar [Instituto de BioingenierIa y Departamento de Fisica y Arquitectura de Computadores, Universidad Miguel Hernandez, 03202 Elche (Spain); Moreno, Ignacio [Departamento de Ciencia de Materiales, Optica y TecnologIa Electronica, Universidad Miguel Hernandez, 03202 Elche (Spain)

    2007-09-11

    In this work, we present a simple analysis of binary diffraction gratings with different slit widths relative to the grating period. The analysis is based on a simple phasor technique directly derived from the Huygens principle. By introducing a slit phasor and a grating phasor, the intensity of the diffracted orders and the grating's resolving power can be easily obtained without applying the usual Fourier transform operations required for these calculations. The proposed phasor technique is mathematically equivalent to the Fourier transform calculation of the diffraction order amplitude, and it can be useful to explain binary diffraction gratings in a simple manner in introductory physics courses. This theoretical analysis is illustrated with experimental results using a liquid crystal device to display diffraction gratings with different fill factors.

  18. Fine-filter method for Raman lidar based on wavelength division multiplexing and fiber Bragg grating.

    Science.gov (United States)

    Wang, Jun; Zheng, Jiao; Lu, Hong; Yan, Qing; Wang, Li; Liu, Jingjing; Hua, Dengxin

    2017-11-01

    Atmospheric temperature is one of the important parameters for the description of the atmospheric state. Most of the detection approaches to atmospheric temperature monitoring are based on rotational Raman scattering for better understanding atmospheric dynamics, thermodynamics, atmospheric transmission, and radiation. In this paper, we present a fine-filter method based on wavelength division multiplexing, incorporating a fiber Bragg grating in the visible spectrum for the rotational Raman scattering spectrum. To achieve high-precision remote sensing, the strong background noise is filtered out by using the secondary cascaded light paths. Detection intensity and the signal-to-noise ratio are improved by increasing the utilization rate of return signal form atmosphere. Passive temperature compensation is employed to reduce the temperature sensitivity of fiber Bragg grating. In addition, the proposed method provides a feasible solution for the filter system with the merits of miniaturization, high anti-interference, and high stability in the space-based platform.

  19. Method for Measurement of Multi-Degrees-of-Freedom Motion Parameters Based on Polydimethylsiloxane Cross-Coupling Diffraction Gratings

    Science.gov (United States)

    Duan, Junping; Zhu, Qiang; Qian, Kun; Guo, Hao; Zhang, Binzhen

    2017-08-01

    This work presents a multi-degrees-of-freedom motion parameter measurement method based on the use of cross-coupling diffraction gratings that were prepared on the two sides of a polydimethylsiloxane (PDMS) substrate using oxygen plasma processing technology. The laser beam that travels pass the cross-coupling optical grating would be diffracted into a two-dimensional spot array. The displacement and the gap size of the spot-array were functions of the movement of the laser source, as explained by the Fraunhofer diffraction effect. A 480 × 640 pixel charge-coupled device (CCD) was used to acquire images of the two-dimensional spot-array in real time. A proposed algorithm was then used to obtain the motion parameters. Using this method and the CCD described above, the resolutions of the displacement and the deflection angle were 0.18 μm and 0.0075 rad, respectively. Additionally, a CCD with a higher pixel count could improve the resolutions of the displacement and the deflection angle to sub-nanometer and micro-radian scales, respectively. Finally, the dynamic positions of hovering rotorcraft have been tracked and checked using the proposed method, which can be used to correct the craft's position and provide a method for aircraft stabilization in the sky.

  20. Carbon based prosthetic devices

    Energy Technology Data Exchange (ETDEWEB)

    Devlin, D.J.; Carroll, D.W.; Barbero, R.S.; Archuleta, T. [Los Alamos National Lab., NM (US); Klawitter, J.J.; Ogilvie, W.; Strzepa, P. [Ascension Orthopedics (US); Cook, S.D. [Tulane Univ., New Orleans, LA (US). School of Medicine

    1998-12-31

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project objective was to evaluate the use of carbon/carbon-fiber-reinforced composites for use in endoprosthetic devices. The application of these materials for the metacarpophalangeal (MP) joints of the hand was investigated. Issues concerning mechanical properties, bone fixation, biocompatibility, and wear are discussed. A system consisting of fiber reinforced materials with a pyrolytic carbon matrix and diamond-like, carbon-coated wear surfaces was developed. Processes were developed for the chemical vapor infiltration (CVI) of pyrolytic carbon into porous fiber preforms with the ability to tailor the outer porosity of the device to provide a surface for bone in-growth. A method for coating diamond-like carbon (DLC) on the articulating surface by plasma-assisted chemical vapor deposition (CVD) was developed. Preliminary results on mechanical properties of the composite system are discussed and initial biocompatibility studies were performed.

  1. Fabry-Pérot cavity based on chirped sampled fiber Bragg gratings.

    Science.gov (United States)

    Zheng, Jilin; Wang, Rong; Pu, Tao; Lu, Lin; Fang, Tao; Li, Weichun; Xiong, Jintian; Chen, Yingfang; Zhu, Huatao; Chen, Dalei; Chen, Xiangfei

    2014-02-10

    A novel kind of Fabry-Pérot (FP) structure based on chirped sampled fiber Bragg grating (CSFBG) is proposed and demonstrated. In this structure, the regular chirped FBG (CFBG) that functions as reflecting mirror in the FP cavity is replaced by CSFBG, which is realized by chirping the sampling periods of a sampled FBG having uniform local grating period. The realization of such CSFBG-FPs having diverse properties just needs a single uniform pitch phase mask and sub-micrometer precision moving stage. Compared with the conventional CFBG-FP, it becomes more flexible to design CSFBG-FPs of diverse functions, and the fabrication process gets simpler. As a demonstration, based on the same experimental facilities, FPs with uniform FSR (~73 pm) and chirped FSR (varying from 28 pm to 405 pm) are fabricated respectively, which shows good agreement with simulation results.

  2. Impurity analysis of NSTX using a transmission grating-based imaging spectrometer

    International Nuclear Information System (INIS)

    Kumar, Deepak; Finkenthal, Michael; Stutman, Dan; Clayton, Daniel J; Tritz, Kevin; Bell, Ronald E; Diallo, Ahmed; LeBlanc, Ben P; Podesta, Mario

    2012-01-01

    A transmission grating-based imaging spectrometer has recently been installed and operated on the National Spherical Torus Experiment (NSTX) at PPPL. This paper describes the spectral and spatial characteristics of impurity emission under different operating conditions of the experiment—neutral beam heated, ohmic heated and RF heated plasma. A typical spectrum from each scenario is analyzed to provide quantitative estimates of impurity fractions in the plasma. (paper)

  3. Transducer-based fiber Bragg grating high-temperature sensor with enhanced range and stability

    Science.gov (United States)

    Mamidi, Venkata Reddy; Kamineni, Srimannarayana; Ravinuthala, Lakshmi Narayana Sai Prasad; Tumu, Venkatappa Rao

    2017-09-01

    Fiber Bragg grating (FBG)-based high-temperature sensor with enhanced-temperature range and stability has been developed and tested. The sensor consists of an FBG and a mechanical transducer, which furnishes a linear temperature-dependent tensile strain on FBG by means of differential linear thermal expansion of two different ceramic materials. The designed sensor is tested over a range: 20°C to 1160°C and is expected to measure up to 1500°C.

  4. Flat-top pulse generation based on a fiber Bragg grating in transmission.

    Science.gov (United States)

    Preciado, Miguel A; Muriel, Miguel A

    2009-03-15

    We propose and analyze a flat-top pulse generator based on a fiber Bragg grating (FBG) in transmission. As is shown in the examples, a uniform period FBG properly designed can exhibit a spectral response in transmission close to sinc function (in amplitude and phase) in a certain bandwidth, because of the logarithm Hilbert transform relations, which can be used to reshape a Gaussian-like input pulse into a flat-top pulse.

  5. Unified design of sinusoidal-groove fused-silica grating.

    Science.gov (United States)

    Feng, Jijun; Zhou, Changhe; Cao, Hongchao; Lu, Peng

    2010-10-20

    A general design rule of deep-etched subwavelength sinusoidal-groove fused-silica grating as a highly efficient polarization-independent or polarization-selective device is studied based on the simplified modal method, which shows that the device structure depends little on the incident wavelength, but mainly on the ratio of groove depth to incident wavelength and the ratio of wavelength to grating period. These two ratios could be used as the design guidelines for wavelength-independent structure from deep ultraviolet to far infrared. The optimized grating profile with a different function as a polarizing beam splitter, a polarization-independent two-port beam splitter, or a polarization-independent grating with high efficiency of -1st order is obtained at a wavelength of 1064 nm, and verified by using the rigorous coupled-wave analysis. The performance of the sinusoidal grating is better than a conventional rectangular one, which could be useful for practical applications.

  6. High-energy x-ray grating-based phase-contrast radiography of human anatomy

    Science.gov (United States)

    Horn, Florian; Hauke, Christian; Lachner, Sebastian; Ludwig, Veronika; Pelzer, Georg; Rieger, Jens; Schuster, Max; Seifert, Maria; Wandner, Johannes; Wolf, Andreas; Michel, Thilo; Anton, Gisela

    2016-03-01

    X-ray grating-based phase-contrast Talbot-Lau interferometry is a promising imaging technology that has the potential to raise soft tissue contrast in comparison to conventional attenuation-based imaging. Additionally, it is sensitive to attenuation, refraction and scattering of the radiation and thus provides complementary and otherwise inaccessible information due to the dark-field image, which shows the sub-pixel size granularity of the measured object. Until recent progress the method has been mainly limited to photon energies below 40 keV. Scaling the method to photon energies that are sufficient to pass large and spacious objects represents a challenging task. This is caused by increasing demands regarding the fabrication process of the gratings and the broad spectra that come along with the use of polychromatic X-ray sources operated at high acceleration voltages. We designed a setup that is capable to reach high visibilities in the range from 50 to 120 kV. Therefore, spacious and dense parts of the human body with high attenuation can be measured, such as a human knee. The authors will show investigations on the resulting attenuation, differential phase-contrast and dark-field images. The images experimentally show that X-ray grating-based phase-contrast radiography is feasible with highly absorbing parts of the human body containing massive bones.

  7. Optical multiple-image hiding based on interference and grating modulation

    International Nuclear Information System (INIS)

    He, Wenqi; Peng, Xiang; Meng, Xiangfeng

    2012-01-01

    We present a method for multiple-image hiding on the basis of interference-based encryption architecture and grating modulation. By using a modified phase retrieval algorithm, we can separately hide a number of secret images into one arbitrarily preselected host image associated with a set of phase-only masks (POMs), which are regarded as secret keys. Thereafter, a grating modulation operation is introduced to multiplex and store the different POMs into a single key mask, which is then assigned to the authorized users in privacy. For recovery, after an appropriate demultiplexing process, one can reconstruct the distributions of all the secret keys and then recover the corresponding hidden images with suppressed crosstalk. Computer simulation results are presented to validate the feasibility of our approach. (paper)

  8. Multi-dimensional grating interferometer based on fibre-fed measurement heads arranged in Littrow configuration

    Science.gov (United States)

    Šiaudinytė, Lauryna; Molnar, Gabor; Köning, Rainer; Flügge, Jens

    2018-05-01

    Industrial application versatility of interferometric encoders increases the urge to measure several degrees of freedom. A novel grating interferometer containing a commercially available, minimized Michelson interferometer and three fibre-fed measurement heads is presented in this paper. Moreover, the arrangement is designed for simultaneous displacement measurements in two perpendicular planes. In the proposed setup, beam splitters are located in the fibre heads, therefore the grating is separated from the light source and the photo detector, which influence measurement results by generated heat. The operating principle of the proposed system as well as error sources influencing measurement results are discussed in this paper. Further, the benefits and shortcomings of the setup are presented. A simple Littrow-configuration-based design leads to a compact-size interferometric encoder suitable for multidimensional measurements.

  9. Optical authentication based on moiré effect of nonlinear gratings in phase space

    International Nuclear Information System (INIS)

    Liao, Meihua; He, Wenqi; Wu, Jiachen; Lu, Dajiang; Liu, Xiaoli; Peng, Xiang

    2015-01-01

    An optical authentication scheme based on the moiré effect of nonlinear gratings in phase space is proposed. According to the phase function relationship of the moiré effect in phase space, an arbitrary authentication image can be encoded into two nonlinear gratings which serve as the authentication lock (AL) and the authentication key (AK). The AL is stored in the authentication system while the AK is assigned to the authorized user. The authentication procedure can be performed using an optoelectronic approach, while the design process is accomplished by a digital approach. Furthermore, this optical authentication scheme can be extended for multiple users with different security levels. The proposed scheme can not only verify the legality of a user identity, but can also discriminate and control the security levels of legal users. Theoretical analysis and simulation experiments are provided to verify the feasibility and effectiveness of the proposed scheme. (paper)

  10. Response of fiber Bragg gratings to longitudinal ultrasonic waves.

    Science.gov (United States)

    Minardo, Aldo; Cusano, Andrea; Bernini, Romeo; Zeni, Luigi; Giordano, Michele

    2005-02-01

    In the last years, fiber optic sensors have been widely exploited for several sensing applications, including static and dynamic strain measurements up to acoustic detection. Among these, fiber Bragg grating sensors have been indicated as the ideal candidate for practical structural health monitoring in light of their unique advantages over conventional sensing devices. Although this class of sensors has been successfully tested for static and low-frequency measurements, the identification of sensor performances for high-frequency detection, including acoustic emission and ultrasonic investigations, is required. To this aim, the analysis of feasibilty on the use of fiber Bragg grating sensors as ultrasonic detectors has been carried out. In particular, the response of fiber Bragg gratings subjected to the longitudinal ultrasonic (US) field has been theoretically and numerically investigated. Ultrasonic field interaction has been modeled, taking into account the direct deformation of the grating pitch combined with changes in local refractive index due to the elasto-optic effect. Numerical results, obtained for both uniform and Gaussian-apodized fiber Bragg gratings, show that the grating spectrum is strongly influenced by the US field in terms of shape and central wavelength. In particular, a key parameter affecting the grating response is the ratio between the US wavelength and the grating length. Normal operation characterized by changes in wavelength of undistorted Bragg peak is possible only for US wavelengths longer than the grating length. For US wavelengths approaching the grating length, the wavelength change is accompanied by subpeaks formation and main peak amplitude modulation. This effect can be attributed to the nonuniformity of the US perturbation along the grating length. At very high US frequencies, the grating is not sensitive any longer. The results of this analysis provide useful tools for the design of grating-based ultrasound sensors for

  11. Optical power-based interrogation of plasmonic tilted fiber Bragg grating biosensors

    Science.gov (United States)

    González-Vila, Á.; Lopez-Aldaba, A.; Kinet, D.; Mégret, P.; Lopez-Amo, M.; Caucheteur, C.

    2017-04-01

    Two interrogation techniques for plasmonic tilted fiber Bragg grating sensors are reported and experimentally tested. Typical interrogation methods are usually based on tracking the wavelength shift of the most sensitive cladding mode, but for biosensing applications, spectrometer-based methods can be replaced by more efficient solutions. The proposed techniques thus rely on the measurement of the induced changes in optical power. The first one consists of a properly polarized tunable laser source set to emit at the wavelength of the sensor most sensitive mode and an optical power meter to measure the transmitted response. For the second method, a uniform fiber Bragg grating is photo-inscribed beyond the sensor in such a way that its central wavelength matches the sensor most sensitive mode, acting as an optical filter. Using a LED source, light reflected backwards by this grating is partially attenuated when passing through the sensor due to plasmon wave excitation and the power changes are quantified once again with an optical power meter. A performance analysis of the techniques is carried out and they both result competitive interrogation solutions. The work thus focuses on the development of cost-effective alternatives for monitoring this kind of biosensors in practical situations.

  12. Multi-wavelength laser based on an arrayed waveguide grating and Sagnac loop reflectors monolithically integrated on InP

    NARCIS (Netherlands)

    Muñoz, P.; García-Olcina, R.; Doménech, J.D.; Rius, M.; Capmany, J.; Chen, L.R.; Habib, C.; Leijtens, X.J.M.; Vries, de T.; Heck, M.J.R.; Augustin, L.M.; Nötzel, R.; Robbins, D.J.

    2010-01-01

    In this paper, a multi-wavelength laser monolithically integrated on InP is presented. A linear laser cavity is built between two integrated Sagnac loop reflectors, with an Arrayed Waveguide Grating (AWG) as frequency selective device, and Semiconductor Optical Amplifiers (SOA) as gain sections. The

  13. Design of a Fused-Silica Subwavelength Polarizing Beam Splitter Grating Based on the Modal Method

    International Nuclear Information System (INIS)

    Hua-Jun, Zhao; Dai-Rong, Yuan; Pei, Wang; Yong-Hua, Lu; Hai, Ming

    2010-01-01

    A polarizing beam splitter (PBS) design based on a fused-silica lamellar subwavelength transmission grating is demonstrated with the modal method, where TE- and TM-polarized waves are mainly diffracted in the −1 st and 0 th orders, respectively. The physical explanation of the grating diffraction is illustrated by the interference of the corresponding parts of the two propagating modes, which is very similar to a Mach–Zehnder interferometer. It is shown that diffraction efficients over 99% for a TM-polarized wave in the −1 st order and 90% for a TE-polarized wave in the 0 th order are obtained at the wavelength of 1.053 μm. The polarization transmission extinction ratios are better than 33 dB and 51 dB for the order 0 th and the −1 st order, respectively. The splitting properties of the PBS grating designed by the modal method are in good agreement with the results simulated by the rigorous coupled wave analysis method. (fundamental areas of phenomenology(including applications))

  14. Simultaneous measurement of refractive index and temperature based on intensity demodulation using matching grating method.

    Science.gov (United States)

    Qi, Liang; Zhao, Chun-Liu; Kang, Juan; Jin, Yongxing; Wang, Jianfeng; Ye, Manping; Jin, Shangzhong

    2013-07-01

    A solution refractive index (SRI) and temperature simultaneous measurement sensor with intensity-demodulation system based on matching grating method were demonstrated. Long period grating written in a photonic crystal fiber (LPG-PCF), provides temperature stable and wavelength dependent optical intensity transmission. The reflective peaks of two fiber Bragg gratings (FBGs), one of which is etched then sensitive to both SRI and temperature, another (FBG2) is only sensitive to temperature, were located in the same linear range of the LPG-PCF's transmission spectrum. An identical FBG with FBG2 was chosen as a matching FBG. When environments (SRI and temperature) change, the wavelength shifts of the FBGs are translated effectively to the reflection intensity changes. By monitoring output lights of unmatching and matching paths, the SRI and temperature were deduced by a signal processing unit. Experimental results show that the simultaneous refractive index and temperature measurement system work well. The proposed sensor system is compact and suitable for in situ applications at lower cost.

  15. Integrated optical electric field sensor based on a Bragg grating in lithium niobate

    Science.gov (United States)

    Runde, D.; Brunken, S.; Rüter, C. E.; Kip, D.

    2007-01-01

    We demonstrate a new sensor concept for the measurement of oscillating electric fields that is based on Bragg gratings in LiNbO3:Ti channel waveguides. This miniaturized sensor that works in a retroreflective scheme does not require metallic electrodes and can be directly immersed in an oscillating electric field. The electric field induces a shift of the Bragg wavelength of the reflection grating that is due to the electro-optic effect. The operating point of the sensor is chosen by adjusting the laser wavelength to the slope of the spectral reflectivity function of the grating. In this way the magnitude of an external electric field is measured precisely as the amplitude of modulated reflected light intensity by using a lock-in amplifier. The sensor principle is demonstrated by detecting low-frequency electric fields ranging from 50 V/cm to 5 kV/cm without any conducting parts of the sensor head. Furthermore, the ability of the sensor to determine the three-dimensional orientation of an external electric field by a single rotation along the waveguide direction is demonstrated.

  16. Fiber Bragg Grating Based pH Sensor

    Science.gov (United States)

    Yulianti, Ian; Sahmah, Abu; Supa'at, M.; Idrus, M.; Kassim, Norazan M.; Al-hetar, Abdulaziz M.

    2011-05-01

    This paper demonstrates the modeling of pH sensor based on pH sensitive hydrogel coated FBG. The modeling was done by simulating the hydrogel swelling behavior, then calculating the strain induced by hydrogel expansion. Meshless numerical method was adopted to solve the Poison Nernst Planck equation coupled to mechanical equation to simulate the hydrogel swelling. The strain induced in the FBG due to mechanical expansion of hydrogel was calculated analytically. Strain of more than 10 μɛ was obtained at pH> 5. At pH of 5, λB shift of more than 10 pm was achieved.

  17. Streamline-based microfluidic device

    Science.gov (United States)

    Tai, Yu-Chong (Inventor); Zheng, Siyang (Inventor); Kasdan, Harvey (Inventor)

    2013-01-01

    The present invention provides a streamline-based device and a method for using the device for continuous separation of particles including cells in biological fluids. The device includes a main microchannel and an array of side microchannels disposed on a substrate. The main microchannel has a plurality of stagnation points with a predetermined geometric design, for example, each of the stagnation points has a predetermined distance from the upstream edge of each of the side microchannels. The particles are separated and collected in the side microchannels.

  18. Enhancement of the sensitivity of a temperature sensor based on fiber Bragg gratings via weak value amplification.

    Science.gov (United States)

    Salazar-Serrano, L J; Barrera, D; Amaya, W; Sales, S; Pruneri, V; Capmany, J; Torres, J P

    2015-09-01

    We present a proof-of-concept experiment aimed at increasing the sensitivity of Fiber-Bragg-gratings temperature sensors by making use of a weak-value-amplification scheme. The technique requires only linear optics elements for its implementation and appears as a promising method for increasing the sensitivity than state-of the-art sensors can currently provide. The device implemented here is able to generate a shift of the centroid of the spectrum of a pulse of ∼0.035  nm/°C, a nearly fourfold increase in sensitivity over the same fiber-Bragg-grating system interrogated using standard methods.

  19. Wide wavelength range tunable one-dimensional silicon nitride nano-grating guided mode resonance filter based on azimuthal rotation

    Directory of Open Access Journals (Sweden)

    Ryoji Yukino

    2017-01-01

    Full Text Available We describe wavelength tuning in a one dimensional (1D silicon nitride nano-grating guided mode resonance (GMR structure under conical mounting configuration of the device. When the GMR structure is rotated about the axis perpendicular to the surface of the device (azimuthal rotation for light incident at oblique angles, the conditions for resonance are different than for conventional GMR structures under classical mounting. These resonance conditions enable tuning of the GMR peak position over a wide range of wavelengths. We experimental demonstrate tuning over a range of 375 nm between 500 nm˜875 nm. We present a theoretical model to explain the resonance conditions observed in our experiments and predict the peak positions with show excellent agreement with experiments. Our method for tuning wavelengths is simpler and more efficient than conventional procedures that employ variations in the design parameters of structures or conical mounting of two-dimensional (2D GMR structures and enables a single 1D GMR device to function as a high efficiency wavelength filter over a wide range of wavelengths. We expect tunable filters based on this technique to be applicable in a wide range of fields including astronomy and biomedical imaging.

  20. Relative humidity sensor based on surface plasmon resonance of D-shaped fiber with polyvinyl alcohol embedding Au grating

    Science.gov (United States)

    Yan, Haitao; Han, Daofu; Li, Ming; Lin, Bo

    2017-01-01

    This paper presents the design, fabrication, and characterization of a D-shaped fiber coated with polyvinyl alcohol (PVA) embedding an Au grating-based relative humidity (RH) sensor. The Au grating is fabricated on a D-shaped fiber to match the wave-vector and excite the surface plasmon, and the PVA is embedded in the Au grating as a sensitive cladding film. The refractive index of PVA changes with the ambient humidity. Measurements in a controlled environment show that the RH sensor can achieve a sensitivity of 5.4 nm per relative humidity unit in the RH range from 0% to 70% RH. Moreover, the surface plasmon resonance can be realized and used for RH sensing at the C band of optical fiber communication instead of the visible light band due to the metallic grating microstructure on the D-shaped fiber.

  1. Low-cost vibration sensor based on dual fiber Bragg gratings and light intensity measurement.

    Science.gov (United States)

    Gao, Xueqing; Wang, Yongjiao; Yuan, Bo; Yuan, Yinquan; Dai, Yawen; Xu, Gang

    2013-09-20

    A vibration monitoring system based on light intensity measurement has been constructed, and the designed accelerometer is based on steel cantilever frame and dual fiber Bragg gratings (FBGs). By using numerical simulations for the dual FBGs, the dependence relationship of the area of main lobes on the difference of initial central wavelengths is obtained and the most optimal choice for the initial value and the vibration amplitude of the difference of central wavelengths of two FBGs is suggested. The vibration monitoring experiments are finished, and the measured data are identical to the simulated results.

  2. Magnetic field sensor based on double-sided polished fibre-Bragg gratings

    International Nuclear Information System (INIS)

    Tien, Chuen-Lin; Hwang, Chang-Chou; Liu, Wen-Feng; Chen, Hong-Wei

    2009-01-01

    A new magnetic field sensor based on double-sided polished fibre-Bragg gratings (FBGs) coated with an iron thin film for measuring magnetic flux density was experimentally demonstrated with the sensitivity of 25.6 nm T −1 . The sensing mechanism is based on the Bragg wavelength shift as the magnetic field is measured by the proposed sensing head. Results of this study present the intensity of the reflected optical signal as a function of the applied strain on the FBG. This paper shows that an improved method for sensing the wavelength shift with changes in external magnetic field is developed by use of the double-sided polished FBGs

  3. TM grating coupler on low-loss LPCVD based Si3N4 waveguide platform

    Science.gov (United States)

    Dabos, G.; Manolis, A.; Giesecke, A. L.; Porschatis, C.; Chmielak, B.; Wahlbrink, T.; Pleros, N.; Tsiokos, D.

    2017-12-01

    We demonstrate, for the first time to our knowledge, a fully etched TM grating coupler for low-loss Low-Pressure-Chemical-Vapor-Deposition (LPCVD) based silicon nitride platform with a coupling loss of 6.5 dB at 1541 nm and a 1 dB bandwidth of 55 nm, addressing applications where TM polarization is a pre-requisite. The proposed GC and the 360 nm × 800 nm strip based Si3N4 waveguides have been fabricated by optical projection lithography using an i-line stepper tool enabling low-cost and mass manufacturing of photonic-integrated-circuits.

  4. Reconfiguring waveguide-gratings-based M-signature codecs to enhance OCDMA network confidentiality

    Science.gov (United States)

    Huang, Jen-Fa; Chen, Kai-Sheng; Lin, Ying-Chen; Li, Chung-Yu

    2014-02-01

    A reconfiguration scheme based on composite signature codes over waveguide-gratings-based optical code-division multiple-access (OCDMA) network coder/decoders (codecs) is proposed in the paper. By using central control node to monitor network traffic condition and reconfigure the composite signature codes made up of maximal-length sequence (M-sequence) component codes and random changing the signature codes assigned for each user to improve the confidentiality performance in an OCDMA system. The proposed scheme is analyzed with some practical eavesdroppers' attacks.

  5. Neutral network and fuzzy logic based grate control; Roststyrning med neutrala naetverk och fuzzy logic

    Energy Technology Data Exchange (ETDEWEB)

    Ramstroem, Erik [TPS Termiska Processer AB, Nykoeping (Sweden)

    2002-04-01

    Grate-control is a complex task in many ways. The relations between controlled variables and the values they depend on are mostly unknown. Research projects are going on to create grate models based on physical laws. Those models are too complex for control implementation. The evaluation time is to long for control use. Another fundamental difficulty is that the relationships are none linear. That is, for a specific change in control value, the change in controlled value depends on the original size of control value, process disturbances and controlled values. There are extensive theories for linear process control. Non-linear control theory is used in robotic applications, but not in process and combustion control. The aim of grate control is to use as much of the grate area as possible, without having unburned material in ash. The outlined strategy is: To keep the position of the final bum out zone constant and its extension controlled. The control variables should be primary airflow, distribution of primary air, and fuel flow. Disturbances that should be measured are the fuel moisture content, the temperature of primary air and the grate temperature under the fuel bed. Technologies used are, fuzzy-logic and neural networks. A combination of booth could be used as well as any of them separately. A Fuzzy-logic controller acts as a computerised operator. Rules are specified with 'if - then' thesis. An example of that is: - if temperature is low, then close the valve The boundaries between the rules are made fuzzy. That makes it possible for the temperature to be just a bit low, which makes the valve open a bit. A lot of rules are created so that the controller knows what to do in every situation. Neural networks are sort of multi dimensional curves, with arbitrary degrees of freedom. The nets are used to predict future process values from measured ones. The model is evaluated from collected data. Parameters are adjusted for best correspondence between

  6. Development of a Novel Spectrophotometer for Biochemical Analyzer Based on Volume Holography Transmissive Grating and Linear CCD

    International Nuclear Information System (INIS)

    Ren Zhong; Liu Guodong; Huang Zhen; Zeng Lvming; Dai Longmin

    2011-01-01

    The classical surface-embossed plane and concave grating are usually used as the diffraction grating in some spectrophotometers. But the minute cracks are produced on the surface of the gratings' grooves, which leads to generate the stray-light and decrease the efficiency of instrument. Therefore, a novel custom-built spectrophotometer for BCA is developed in this paper. Meanwhile, the volume holography transmissive (VHT) grating is used as the diffraction grating in this spectrophotometer. Additionally, a high resolution CCD and data acquisition (DAQ) card with combined the virtual software platform based on LabVIEW are used to design the spectral acquisition and analysis system. Experimental results show that the spectral range and the diffraction efficiency of the spectrophotometer for BCA are greatly increased. The spectral range of the spectrophotometer for BCA can reach 300-1000 nm, its wavelength resolution can reach 1nm. And, it uses the back-splitting-light technology and multi-channel parallel analysis. Compared with other same types, this spectrophotometer has many advantages, such as, higher efficiency, simpler algorithm, higher accuracy, cheaper cost and fewer stray-light and higher imaging quality, etc. Therefore, this spectrophotometer for BCA based on VHT grating will has the greatly potential values in the fields of the biochemical or medical research.

  7. Design Parameter Optimization of a Silicon-Based Grating Waveguide for Performance Improvement in Biochemical Sensor Application.

    Science.gov (United States)

    Hong, Yoo-Seung; Cho, Chun-Hyung; Sung, Hyuk-Kee

    2018-03-05

    We performed numerical analysis and design parameter optimization of a silicon-based grating waveguide refractive index (RI) sensor. The performance of the grating waveguide RI sensor was determined by the full-width at half-maximum (FWHM) and the shift in the resonance wavelength in the transmission spectrum. The transmission extinction, a major figure-of-merit of an RI sensor that reflects both FWHM and resonance shift performance, could be significantly improved by the proper determination of three major grating waveguide parameters: duty ratio, grating period, and etching depth. We analyzed the transmission characteristics of the grating waveguide under various design parameter conditions using a finite-difference time domain method. We achieved a transmission extinction improvement of >26 dB under a given bioenvironmental target change by the proper choice of the design procedure and parameters. This design procedure and choice of appropriate parameters would enable the widespread application of silicon-based grating waveguide in high-performance RI biochemical sensor.

  8. Tilted Bragg grating multipoint sensor based on wavelength-gated cladding-modes coupling.

    Science.gov (United States)

    Caucheteur, Christophe; Mégret, Patrice; Cusano, Andrea

    2009-07-10

    In recent years, tilted fiber Bragg gratings (TFBGs) have been demonstrated to be a promising technological platform for sensing applications such as the measurement of axial strain, bending, vibration, and refractive index. However, complex spectral measurements combined with the difficulty of using TFBGs in a quasi-distributed sensors network limit the practical exploitation of this assessed technology. To address this issue, we propose a hybrid configuration involving uniform and TFBGs working in reflection, which makes the demodulation technique easier and allows multipoint sensing. This configuration provides a narrowband reflection signal that is modulated by the wavelength selective losses associated with some TFBG's cladding-modes resonances. We report here the operating principle of the proposed device. An experimental validation is presented for refractive-index sensing purposes.

  9. Development of at-wavelength metrology using grating-based shearing interferometry at Diamond Light Source

    International Nuclear Information System (INIS)

    Wang, Hongchang; Berujon, Sebastien; Sawhney, Kawal

    2013-01-01

    The grating-based shearing interferometer has been established and further developed on B16 at Diamond Light Source. The beamline performances of both an X-ray plane mirror and a compound refractive lens (CRL) have been investigated using this technique. The slope error of the X-ray mirror was retrieved from the wavefront phase gradient, which was measured using two different processing schemes: phase stepping and moiré fringe analysis. The interferometer has demonstrated a high sensitivity with sub-microradian accuracy. Some of the advantages, disadvantages and limitations for the two approaches will also be presented.

  10. Development of at-wavelength metrology using grating-based shearing interferometry at Diamond Light Source

    Science.gov (United States)

    Wang, Hongchang; Berujon, Sebastien; Sawhney, Kawal

    2013-03-01

    The grating-based shearing interferometer has been established and further developed on B16 at Diamond Light Source. The beamline performances of both an X-ray plane mirror and a compound refractive lens (CRL) have been investigated using this technique. The slope error of the X-ray mirror was retrieved from the wavefront phase gradient, which was measured using two different processing schemes: phase stepping and moiré fringe analysis. The interferometer has demonstrated a high sensitivity with sub-microradian accuracy. Some of the advantages, disadvantages and limitations for the two approaches will also be presented.

  11. A flexible, highly sensitive catheter for high resolution manometry based on in-fibre Bragg gratings

    International Nuclear Information System (INIS)

    Bueley, Christopher; Wild, Peter M

    2013-01-01

    This work presents a fibre optic-based flexible catheter for high resolution manometry (HRM), with sensing pods located at a pitch of 10 mm and an overall diameter of 2.8 mm. In-fibre Bragg gratings act as the sensing elements within these sensing pods. Hydrodynamic pressure resolution of 0.2 mmHg is demonstrated in conjunction with insensitivity to occlusion pressure. This result is significant in the context of HRM where independent measurement of hydrodynamic pressure is clinically relevant. The sensing system is compact, robust and flexible. Crosstalk between individual sensors is characterized and a compensation scheme is developed and validated. (paper)

  12. Fiber Bragg grating sensor based on cantilever structure embedded in polymer 3D printed material

    Science.gov (United States)

    Lima, Rita; Tavares, R.; Silva, S. O.; Abreu, P.; Restivo, Maria T.; Frazão, O.

    2017-04-01

    A cantilever structure in 3D printed based on a fiber Bragg grating (FBG) sensor embedded in polymer material is proposed. The FBG sensor was embedded in 3D printed coating and was tested under three physical parameters: displacement, temperature and vibration. The sensor was tested in displacement in two different regions of the cantilever, namely, on its midpoint and end point. The maximum displacement sensitivity achieved was (3 +/- 0.1) pm/mm for end point displacement, and a temperature sensitivity of (30 +/- 1) pm/°C was also attained. In the case of vibration measurements it was possible to obtain a 10.23Hz-low frequency oscillation.

  13. Design of cross-sensitive temperature and strain sensor based on sampled fiber grating

    Directory of Open Access Journals (Sweden)

    Zhang Xiaohang

    2017-02-01

    Full Text Available In this paper,a cross-sensitive temperature and strain sensor based on sampled fiber grating is designed.Its temperature measurement range is -50-200℃,and the strain measurement rangeis 0-2 000 με.The characteristics of the sensor are obtained using simulation method.Utilizing SPSS software,we found the dual-parameter matrix equations of measurement of temperature and strain,and calibrated the four sensing coefficients of the matrix equations.

  14. Fast tunable blazed MEMS grating for external cavity lasers

    Science.gov (United States)

    Tormen, Maurizio; Niedermann, Philippe; Hoogerwerf, Arno; Shea, Herbert; Stanley, Ross

    2017-11-01

    Diffractive MEMS are interesting for a wide range of applications, including displays, scanners or switching elements. Their advantages are compactness, potentially high actuation speed and in the ability to deflect light at large angles. We have designed and fabricated deformable diffractive MEMS grating to be used as tuning elements for external cavity lasers. The resulting device is compact, has wide tunability and a high operating speed. The initial design is a planar grating where the beams are free-standing and attached to each other using leaf springs. Actuation is achieved through two electrostatic comb drives at either end of the grating. To prevent deformation of the free-standing grating, the device is 10 μm thick made from a Silicon on Insulator (SOI) wafer in a single mask process. At 100V a periodicity tuning of 3% has been measured. The first resonant mode of the grating is measured at 13.8 kHz, allowing high speed actuation. This combination of wide tunability and high operating speed represents state of the art in the domain of tunable MEMS filters. In order to improve diffraction efficiency and to expand the usable wavelength range, a blazed version of the deformable MEMS grating has been designed. A key issue is maintaining the mechanical properties of the original device while providing optically smooth blazed beams. Using a process based on anisotropic KOH etching, blazed gratings have been obtained and preliminary characterization is promising.

  15. All-optical fiber anemometer based on laser heated fiber Bragg gratings.

    Science.gov (United States)

    Gao, Shaorui; Zhang, A Ping; Tam, Hwa-Yaw; Cho, L H; Lu, Chao

    2011-05-23

    A fiber-optic anemometer based on fiber Bragg gratings (FBGs) is presented. A short section of cobalt-doped fiber was utilized to make a fiber-based "hot wire" for wind speed measurement. Fiber Bragg gratings (FBGs) were fabricated in the cobalt-doped fiber using 193 nm laser pulses to serve as localized temperature sensors. A miniature all-optical fiber anemometer is constructed by using two FBGs to determine the dynamic thermal equilibrium between the laser heating and air flow cooling through monitoring the FBGs' central wavelengths. It was demonstrated that the sensitivity of the sensor can be adjusted through the power of pump laser or the coating on the FBG. Experimental results reveal that the proposed FBG-based anemometer exhibits very good performance for wind speed measurement. The resolution of the FBG-based anemometer is about 0.012 m/s for wind speed range between 2.0 m/s and 8.0 m/s.

  16. Variations on a theme: novel immersed grating based spectrometer designs for space

    Science.gov (United States)

    Agócs, T.; Navarro, R.; Venema, L.

    2017-11-01

    We present novel immersed grating (IG) based spectrometer designs that can be used in space instrumentation. They are based on the design approach that aims to optimize the optical design using the expanded parameter space that the IG technology offers. In principle the wavefront error (WFE) of any optical system the most conveniently can be corrected in the pupil, where in the case of the IG based spectrometer, the IG itself is positioned. By modifying existing three-mirror based optical systems, which can form the main part of double pass spectrometer designs, a large portion of the WFE of the optical system can be transferred to the pupil and to the IG. In these cases the IG can compensate simple low order aberrations of the system and consequently the main benefit is that the mirrors that tend to be off-axis conical sections can be substituted by spherical mirrors. The WFE budget of such designs has only a minor contribution from the very high quality spherical mirrors and the majority of the WFE can be then allocated to the most complex part of the system, the IG. The latter can be designed so that the errors are compensated by a special grating pattern that in turn can be manufactured using the expertise and experience of the semiconductor industry.

  17. DeviceNet-based device-level control in SSRF

    CERN Document Server

    Leng Yong Bin; Lu Cheng Meng; Miao Hai Feng; Liu Song Qiang; Shen Guo Bao

    2002-01-01

    The control system of Shanghai Synchrotron Radiation Facility is an EPICS-based distributed system. One of the key techniques to construct the system is the device-level control. The author describes the design and implementation of the DeviceNet-based device controller. A prototype of the device controller was tested in the experiments of magnet power supply and the result showed a precision of 3 x 10 sup - sup 5

  18. Grating exchange system of independent mirror supported by floating rotary stage

    Science.gov (United States)

    Zhang, Jianhuan; Tao, Jin; Liu, Yan; Nan, Yan

    2015-10-01

    The performance of The Grating Exchange System can satisfy the Thirty Meter Telescope - TMT for astronomical observation WFOS index requirements and satisfy the requirement of accuracy in the grating exchange. It is used to install in the MOBIE and a key device of MOBIE. The Wide Field Optical Spectrograph (WFOS) is one of the three first-light observing capabilities selected by the TMT Science Advisory Committee. The Multi-Object Broadband Imaging Echellette (MOBIE) instrument design concept has been developed to address the WFOS requirements as described in the TMT Science-Based Requirements Document (SRD). The Grating Exchange System uses a new type of separate movement way of three grating devices and a mirror device. Three grating devices with a mirror are able to achieve independence movement. This kind of grating exchange system can effectively solve the problem that the volume of the grating change system is too large and that the installed space of MOBIE instruments is too limit. This system adopts the good stability, high precision of rotary stage - a kind of using air bearing (Air bearing is famous for its ultra-high precision, and can meet the optical accuracy requirement) and rotation positioning feedback gauge turntable to support grating device. And with a kind of device which can carry greater weight bracket fixed on the MOBIE instrument, with two sets of servo motor control rotary stage and the mirror device respectively. And we use the control program to realize the need of exercising of the grating device and the mirror device. Using the stress strain analysis software--SolidWorks for stress and strain analysis of this structure. And then checking the structure of the rationality and feasibility. And prove that this system can realize the positioning precision under different working conditions can meet the requirements of imaging optical grating diffraction efficiency and error by the calculation and optical performance analysis.

  19. Graphene-based energy devices

    CERN Document Server

    Yusoff, A Rashid bin Mohd

    2015-01-01

    This first book dedicated to the topic provides an up-to-date account of the many opportunities graphene offers for robust, workable energy generation and storage devices. Following a brief overview of the fundamentals of graphene, including the main synthesis techniques, characterization methods and properties, the first part goes on to deal with graphene for energy storage applications, such as lithium-ion batteries, supercapacitors and hydrogen storage. The second part is concerned with graphene-based energy-generation devices, in particular conventional as well as microbial and enzymatic f

  20. Towards a Uniform Metrological Assessment of Grating-Based Optical Fiber Sensors: From Refractometers to Biosensors.

    Science.gov (United States)

    Chiavaioli, Francesco; Gouveia, Carlos A J; Jorge, Pedro A S; Baldini, Francesco

    2017-06-21

    A metrological assessment of grating-based optical fiber sensors is proposed with the aim of providing an objective evaluation of the performance of this sensor category. Attention was focused on the most common parameters, used to describe the performance of both optical refractometers and biosensors, which encompassed sensitivity, with a distinction between volume or bulk sensitivity and surface sensitivity, resolution, response time, limit of detection, specificity (or selectivity), reusability (or regenerability) and some other parameters of generic interest, such as measurement uncertainty, accuracy, precision, stability, drift, repeatability and reproducibility. Clearly, the concepts discussed here can also be applied to any resonance-based sensor, thus providing the basis for an easier and direct performance comparison of a great number of sensors published in the literature up to now. In addition, common mistakes present in the literature made for the evaluation of sensor performance are highlighted, and lastly a uniform performance assessment is discussed and provided. Finally, some design strategies will be proposed to develop a grating-based optical fiber sensing scheme with improved performance.

  1. High sensitivity phase retrieval method in grating-based x-ray phase contrast imaging

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zhao; Gao, Kun; Chen, Jian; Wang, Dajiang; Wang, Shenghao; Chen, Heng; Bao, Yuan; Shao, Qigang; Wang, Zhili, E-mail: wangnsrl@ustc.edu.cn [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029 (China); Zhang, Kai [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Zhu, Peiping; Wu, Ziyu, E-mail: wuzy@ustc.edu.cn [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China and Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

    2015-02-15

    Purpose: Grating-based x-ray phase contrast imaging is considered as one of the most promising techniques for future medical imaging. Many different methods have been developed to retrieve phase signal, among which the phase stepping (PS) method is widely used. However, further practical implementations are hindered, due to its complex scanning mode and high radiation dose. In contrast, the reverse projection (RP) method is a novel fast and low dose extraction approach. In this contribution, the authors present a quantitative analysis of the noise properties of the refraction signals retrieved by the two methods and compare their sensitivities. Methods: Using the error propagation formula, the authors analyze theoretically the signal-to-noise ratios (SNRs) of the refraction images retrieved by the two methods. Then, the sensitivities of the two extraction methods are compared under an identical exposure dose. Numerical experiments are performed to validate the theoretical results and provide some quantitative insight. Results: The SNRs of the two methods are both dependent on the system parameters, but in different ways. Comparison between their sensitivities reveals that for the refraction signal, the RP method possesses a higher sensitivity, especially in the case of high visibility and/or at the edge of the object. Conclusions: Compared with the PS method, the RP method has a superior sensitivity and provides refraction images with a higher SNR. Therefore, one can obtain highly sensitive refraction images in grating-based phase contrast imaging. This is very important for future preclinical and clinical implementations.

  2. High sensitivity phase retrieval method in grating-based x-ray phase contrast imaging

    International Nuclear Information System (INIS)

    Wu, Zhao; Gao, Kun; Chen, Jian; Wang, Dajiang; Wang, Shenghao; Chen, Heng; Bao, Yuan; Shao, Qigang; Wang, Zhili; Zhang, Kai; Zhu, Peiping; Wu, Ziyu

    2015-01-01

    Purpose: Grating-based x-ray phase contrast imaging is considered as one of the most promising techniques for future medical imaging. Many different methods have been developed to retrieve phase signal, among which the phase stepping (PS) method is widely used. However, further practical implementations are hindered, due to its complex scanning mode and high radiation dose. In contrast, the reverse projection (RP) method is a novel fast and low dose extraction approach. In this contribution, the authors present a quantitative analysis of the noise properties of the refraction signals retrieved by the two methods and compare their sensitivities. Methods: Using the error propagation formula, the authors analyze theoretically the signal-to-noise ratios (SNRs) of the refraction images retrieved by the two methods. Then, the sensitivities of the two extraction methods are compared under an identical exposure dose. Numerical experiments are performed to validate the theoretical results and provide some quantitative insight. Results: The SNRs of the two methods are both dependent on the system parameters, but in different ways. Comparison between their sensitivities reveals that for the refraction signal, the RP method possesses a higher sensitivity, especially in the case of high visibility and/or at the edge of the object. Conclusions: Compared with the PS method, the RP method has a superior sensitivity and provides refraction images with a higher SNR. Therefore, one can obtain highly sensitive refraction images in grating-based phase contrast imaging. This is very important for future preclinical and clinical implementations

  3. A novel capacitive absolute positioning sensor based on time grating with nanometer resolution

    Science.gov (United States)

    Pu, Hongji; Liu, Hongzhong; Liu, Xiaokang; Peng, Kai; Yu, Zhicheng

    2018-05-01

    The present work proposes a novel capacitive absolute positioning sensor based on time grating. The sensor includes a fine incremental-displacement measurement component combined with a coarse absolute-position measurement component to obtain high-resolution absolute positioning measurements. A single row type sensor was proposed to achieve fine displacement measurement, which combines the two electrode rows of a previously proposed double-row type capacitive displacement sensor based on time grating into a single row. To achieve absolute positioning measurement, the coarse measurement component is designed as a single-row type displacement sensor employing a single spatial period over the entire measurement range. In addition, this component employs a rectangular induction electrode and four groups of orthogonal discrete excitation electrodes with half-sinusoidal envelope shapes, which were formed by alternately extending the rectangular electrodes of the fine measurement component. The fine and coarse measurement components are tightly integrated to form a compact absolute positioning sensor. A prototype sensor was manufactured using printed circuit board technology for testing and optimization of the design in conjunction with simulations. Experimental results show that the prototype sensor achieves a ±300 nm measurement accuracy with a 1 nm resolution over a displacement range of 200 mm when employing error compensation. The proposed sensor is an excellent alternative to presently available long-range absolute nanometrology sensors owing to its low cost, simple structure, and ease of manufacturing.

  4. Scalable Inkjet-Based Structural Color Printing by Molding Transparent Gratings on Multilayer Nanostructured Surfaces.

    Science.gov (United States)

    Jiang, Hao; Kaminska, Bozena

    2018-04-24

    To enable customized manufacturing of structural colors for commercial applications, up-scalable, low-cost, rapid, and versatile printing techniques are highly demanded. In this paper, we introduce a viable strategy for scaling up production of custom-input images by patterning individual structural colors on separate layers, which are then vertically stacked and recombined into full-color images. By applying this strategy on molded-ink-on-nanostructured-surface printing, we present an industry-applicable inkjet structural color printing technique termed multilayer molded-ink-on-nanostructured-surface (M-MIONS) printing, in which structural color pixels are molded on multiple layers of nanostructured surfaces. Transparent colorless titanium dioxide nanoparticles were inkjet-printed onto three separate transparent polymer substrates, and each substrate surface has one specific subwavelength grating pattern for molding the deposited nanoparticles into structural color pixels of red, green, or blue primary color. After index-matching lamination, the three layers were vertically stacked and bonded to display a color image. Each primary color can be printed into a range of different shades controlled through a half-tone process, and full colors were achieved by mixing primary colors from three layers. In our experiments, an image size as big as 10 cm by 10 cm was effortlessly achieved, and even larger images can potentially be printed on recombined grating surfaces. In one application example, the M-MIONS technique was used for printing customizable transparent color optical variable devices for protecting personalized security documents. In another example, a transparent diffractive color image printed with the M-MIONS technique was pasted onto a transparent panel for overlaying colorful information onto one's view of reality.

  5. Preliminary Investigation of an SOI-based Arrayed Waveguide Grating Demodulation Integration Microsystem

    Science.gov (United States)

    Li, Hongqiang; Zhou, Wenqian; Liu, Yu; Dong, Xiaye; Zhang, Cheng; Miao, Changyun; Zhang, Meiling; Li, Enbang; Tang, Chunxiao

    2014-05-01

    An arrayed waveguide grating (AWG) demodulation integration microsystem is investigated in this study. The system consists of a C-band on-chip LED, a 2 × 2 silicon nanowire-based coupler, a fiber Bragg grating (FBG) array, a 1 × 8 AWG, and a photoelectric detector array. The coupler and AWG are made from silicon-on-insulator wafers using electron beam exposure and response-coupled plasma technology. Experimental results show that the excess loss in the MMI coupler with a footprint of 6 × 100 μm2 is 0.5423 dB. The 1 × 8 AWG with a footprint of 267 × 381 μm2 and a waveguide width of 0.4 μm exhibits a central channel loss of -3.18 dB, insertion loss non-uniformity of -1.34 dB, and crosstalk level of -23.1 dB. The entire system is preliminarily tested. Wavelength measurement precision is observed to reach 0.001 nm. The wavelength sensitivity of each FBG is between 0.04 and 0.06 nm/dB.

  6. Distributed fiber optic interferometric geophone system based on draw tower gratings

    Science.gov (United States)

    Xu, Ruquan; Guo, Huiyong; Liang, Lei

    2017-09-01

    A distributed fiber optic interferometric geophone array based on draw tower grating (DTG) array is proposed. The DTG geophone array is made by the DTG array fabricated based on a near-contact exposure through a phase mask during the fiber drawing process. A distributed sensing system with 96 identical DTGs in an equal separation of 20 m and an unbalanced Michelson interferometer for vibration measurement has been experimentally validated compared with a moving-coil geophone. The experimental results indicate that the sensing system can linearly demodulate the phase shift. Compared with the moving coil geophone, the fiber optic sensing system based on DTG has higher signal-to-noise ratio at low frequency.

  7. Flextensional fiber Bragg grating-based accelerometer for low frequency vibration measurement

    Institute of Scientific and Technical Information of China (English)

    Jinghua Zhang; Xueguang Qiao; Manli Hu; Zhongyao Feng; Hong Gao; Yang Yang; Rui Zhou

    2011-01-01

    @@ The intelligent structural health monitoring method,which uses a fiber Bragg grating(FBG)sensor,is a new approach in the field of civil engineering.However,it lacks a reliable FBG-based accelerometer for taking structural low frequency vibration measurements.In this letter,a flextensional FBG-based accelerometer is proposed and demonstrated.The experimental results indicate that the natural frequency of the developed accelerometer is 16.7 Hz,with a high sensitivity of 410.7 pm/g.In addition,it has a broad and flat response over low frequencies ranging from 1 to 10 Hz.The natural frequency and sensitivity of the accelerometer can be tuned by adding mass to tailor the sensor performance to specific applications.Experimental results are presented to demonstrate the good performance of the proposed FBG-based accelerometer.These results show that the proposed accelerometer is satisfactory for low frequency vibration measurements.%The intelligent structural health monitoring method, which uses a fiber Bragg grating {FBG} sensor, ie a new approach in the field of civil engineering. However, it lacks a reliable FBG-based accelerometer for taking structural low frequency vibration measurements. In this letter, a flextensional FBG-based accelerometer is proposed and demonstrated. The experimental results indicate that the natural frequency of the developed accelerometer is 16.7 Hz, with a high sensitivity of 410.7 pm/g. In addition, it has a broad and flat response over low frequencies ranging from 1 to 10 Hz. The natural frequency and sensitivity of the accelerometer can be tuned by adding mass to tailor the sensor performance to specific applications. Experimental results are presented to demonstrate the good performance of the proposed FBG-based accelerometer. These results show that the proposed accelerometer is satisfactory for low frequency vibration measurements.

  8. Low-dose multiple-information retrieval algorithm for X-ray grating-based imaging

    International Nuclear Information System (INIS)

    Wang Zhentian; Huang Zhifeng; Chen Zhiqiang; Zhang Li; Jiang Xiaolei; Kang Kejun; Yin Hongxia; Wang Zhenchang; Stampanoni, Marco

    2011-01-01

    The present work proposes a low dose information retrieval algorithm for X-ray grating-based multiple-information imaging (GB-MII) method, which can retrieve the attenuation, refraction and scattering information of samples by only three images. This algorithm aims at reducing the exposure time and the doses delivered to the sample. The multiple-information retrieval problem in GB-MII is solved by transforming a nonlinear equations set to a linear equations and adopting the nature of the trigonometric functions. The proposed algorithm is validated by experiments both on conventional X-ray source and synchrotron X-ray source, and compared with the traditional multiple-image-based retrieval algorithm. The experimental results show that our algorithm is comparable with the traditional retrieval algorithm and especially suitable for high Signal-to-Noise system.

  9. THz-bandwidth photonic Hilbert transformers based on fiber Bragg gratings in transmission.

    Science.gov (United States)

    Fernández-Ruiz, María R; Wang, Lixian; Carballar, Alejandro; Burla, Maurizio; Azaña, José; LaRochelle, Sophie

    2015-01-01

    THz-bandwidth photonic Hilbert transformers (PHTs) are implemented for the first time, to the best of our knowledge, based on fiber Bragg grating (FBG) technology. To increase the practical bandwidth limitation of FBGs (typically <200  GHz), a superstructure based on two superimposed linearly-chirped FBGs operating in transmission has been employed. The use of a transmission FBG involves first a conversion of the non-minimum phase response of the PHT into a minimum-phase response by adding an anticipated instantaneous component to the desired system temporal impulse response. Using this methodology, a 3-THz-bandwidth integer PHT and a fractional (order 0.81) PHT are designed, fabricated, and successfully characterized.

  10. Graphene-based absorber exploiting guided mode resonances in one-dimensional gratings.

    Science.gov (United States)

    Grande, M; Vincenti, M A; Stomeo, T; Bianco, G V; de Ceglia, D; Aközbek, N; Petruzzelli, V; Bruno, G; De Vittorio, M; Scalora, M; D'Orazio, A

    2014-12-15

    A one-dimensional dielectric grating, based on a simple geometry, is proposed and investigated to enhance light absorption in a monolayer graphene exploiting guided mode resonances. Numerical findings reveal that the optimized configuration is able to absorb up to 60% of the impinging light at normal incidence for both TE and TM polarizations resulting in a theoretical enhancement factor of about 26 with respect to the monolayer graphene absorption (≈2.3%). Experimental results confirm this behavior showing CVD graphene absorbance peaks up to about 40% over narrow bands of a few nanometers. The simple and flexible design points to a way to realize innovative, scalable and easy-to-fabricate graphene-based optical absorbers.

  11. CENTRAL WAVELENGTH ADJUSTMENT OF LIGHT EMITTING SOURCE IN INTERFEROMETRIC SENSORS BASED ON FIBER-OPTIC BRAGG GRATINGS

    Directory of Open Access Journals (Sweden)

    A. S. Aleynik

    2015-09-01

    Full Text Available The paper is focused on the investigation of fiber-optic interferometric sensor based on the array of fiber Bragg gratings. Reflection spectra displacement mechanism of the fiber Bragg gratings under the external temperature effects and the static pressure is described. The experiment has shown that reflection spectra displacement of Bragg gratings reduces the visibility of the interference pattern. A method of center wavelength adjustment is proposed for the optical radiation source in accord ance with the current Bragg gratings reflection spectra based on the impulse relative modulation of control signal for the Peltier element controller. The semiconductor vertical-cavity surface-emitting laser controlled by a pump driver is used as a light source. The method is implemented by the Peltier element controller regulating and stabilizing the light source temperature, and a programmable logic-integrated circuit monitoring the Peltier element controller. The experiment has proved that the proposed method rendered possible to regulate the light source temperature at a pitch of 0.05 K and adjust the optical radiation source center wavelength at a pitch of 0.05 nm. Experimental results have revealed that the central wavelength of the radiation adjustment at a pitch of 0.005 nm gives the possibility for the capacity of the array consisting of four opticalfiber sensors based on the fiber Bragg gratings. They are formed in one optical fiber under the Bragg grating temperature change from 0° C to 300° C and by the optical fiber mechanical stretching by the force up to 2 N.

  12. Biosensing with optical fiber gratings

    Science.gov (United States)

    Chiavaioli, Francesco; Baldini, Francesco; Tombelli, Sara; Trono, Cosimo; Giannetti, Ambra

    2017-06-01

    Optical fiber gratings (OFGs), especially long-period gratings (LPGs) and etched or tilted fiber Bragg gratings (FBGs), are playing an increasing role in the chemical and biochemical sensing based on the measurement of a surface refractive index (RI) change through a label-free configuration. In these devices, the electric field evanescent wave at the fiber/surrounding medium interface changes its optical properties (i.e. intensity and wavelength) as a result of the RI variation due to the interaction between a biological recognition layer deposited over the fiber and the analyte under investigation. The use of OFG-based technology platforms takes the advantages of optical fiber peculiarities, which are hardly offered by the other sensing systems, such as compactness, lightness, high compatibility with optoelectronic devices (both sources and detectors), and multiplexing and remote measurement capability as the signal is spectrally modulated. During the last decade, the growing request in practical applications pushed the technology behind the OFG-based sensors over its limits by means of the deposition of thin film overlays, nanocoatings, and nanostructures, in general. Here, we review efforts toward utilizing these nanomaterials as coatings for high-performance and low-detection limit devices. Moreover, we review the recent development in OFG-based biosensing and identify some of the key challenges for practical applications. While high-performance metrics are starting to be achieved experimentally, there are still open questions pertaining to an effective and reliable detection of small molecules, possibly up to single molecule, sensing in vivo and multi-target detection using OFG-based technology platforms.

  13. Biosensing with optical fiber gratings

    Directory of Open Access Journals (Sweden)

    Chiavaioli Francesco

    2017-06-01

    Full Text Available Optical fiber gratings (OFGs, especially long-period gratings (LPGs and etched or tilted fiber Bragg gratings (FBGs, are playing an increasing role in the chemical and biochemical sensing based on the measurement of a surface refractive index (RI change through a label-free configuration. In these devices, the electric field evanescent wave at the fiber/surrounding medium interface changes its optical properties (i.e. intensity and wavelength as a result of the RI variation due to the interaction between a biological recognition layer deposited over the fiber and the analyte under investigation. The use of OFG-based technology platforms takes the advantages of optical fiber peculiarities, which are hardly offered by the other sensing systems, such as compactness, lightness, high compatibility with optoelectronic devices (both sources and detectors, and multiplexing and remote measurement capability as the signal is spectrally modulated. During the last decade, the growing request in practical applications pushed the technology behind the OFG-based sensors over its limits by means of the deposition of thin film overlays, nanocoatings, and nanostructures, in general. Here, we review efforts toward utilizing these nanomaterials as coatings for high-performance and low-detection limit devices. Moreover, we review the recent development in OFG-based biosensing and identify some of the key challenges for practical applications. While high-performance metrics are starting to be achieved experimentally, there are still open questions pertaining to an effective and reliable detection of small molecules, possibly up to single molecule, sensing in vivo and multi-target detection using OFG-based technology platforms.

  14. Embedded high-contrast distributed grating structures

    Science.gov (United States)

    Zubrzycki, Walter J.; Vawter, Gregory A.; Allerman, Andrew A.

    2002-01-01

    A new class of fabrication methods for embedded distributed grating structures is claimed, together with optical devices which include such structures. These new methods are the only known approach to making defect-free high-dielectric contrast grating structures, which are smaller and more efficient than are conventional grating structures.

  15. Real time transverse-force sensor based on polarization properties of fiber Bragg grating and cross-sensitivity compensation

    International Nuclear Information System (INIS)

    Su, Yang; Zhu, Yong; Zhang, Baofu; Peng, Hui; Ye, Zhenxing

    2013-01-01

    We present a new method for real-time transverse force sensor based on the measurement of the polarization properties of a uniform fiber Bragg grating (FBG) written into standard single mode fiber. Unlike the usual spectral analysis of FBG sensors, we demonstrate here that the amplitude of the first Stokes parameters of a uniform FBG in transmission can be used to obtain transverse force value. The influences of incident angle of linear polarized light launched into FBG on sensor performance are analyzed. Experimental results measured by means of a tunable laser source and a polarimeter are presented. We also propose a kind of grating structure with triangular-shaped transmission spectrum to reduce the influences of cross-sensitivity. The compensation effect can satisfy the requirements of the practical application with optimized grating parameters. (paper)

  16. Grating-based phase contrast tomosynthesis imaging: Proof-of-concept experimental studies

    International Nuclear Information System (INIS)

    Li, Ke; Ge, Yongshuai; Garrett, John; Bevins, Nicholas; Zambelli, Joseph; Chen, Guang-Hong

    2014-01-01

    Purpose: This paper concerns the feasibility of x-ray differential phase contrast (DPC) tomosynthesis imaging using a grating-based DPC benchtop experimental system, which is equipped with a commercial digital flat-panel detector and a medical-grade rotating-anode x-ray tube. An extensive system characterization was performed to quantify its imaging performance. Methods: The major components of the benchtop system include a diagnostic x-ray tube with a 1.0 mm nominal focal spot size, a flat-panel detector with 96 μm pixel pitch, a sample stage that rotates within a limited angular span of ±30°, and a Talbot-Lau interferometer with three x-ray gratings. A total of 21 projection views acquired with 3° increments were used to reconstruct three sets of tomosynthetic image volumes, including the conventional absorption contrast tomosynthesis image volume (AC-tomo) reconstructed using the filtered-backprojection (FBP) algorithm with the ramp kernel, the phase contrast tomosynthesis image volume (PC-tomo) reconstructed using FBP with a Hilbert kernel, and the differential phase contrast tomosynthesis image volume (DPC-tomo) reconstructed using the shift-and-add algorithm. Three inhouse physical phantoms containing tissue-surrogate materials were used to characterize the signal linearity, the signal difference-to-noise ratio (SDNR), the three-dimensional noise power spectrum (3D NPS), and the through-plane artifact spread function (ASF). Results: While DPC-tomo highlights edges and interfaces in the image object, PC-tomo removes the differential nature of the DPC projection data and its pixel values are linearly related to the decrement of the real part of the x-ray refractive index. The SDNR values of polyoxymethylene in water and polystyrene in oil are 1.5 and 1.0, respectively, in AC-tomo, and the values were improved to 3.0 and 2.0, respectively, in PC-tomo. PC-tomo and AC-tomo demonstrate equivalent ASF, but their noise characteristics quantified by the 3D NPS

  17. Grating-based phase contrast tomosynthesis imaging: Proof-of-concept experimental studies

    Science.gov (United States)

    Li, Ke; Ge, Yongshuai; Garrett, John; Bevins, Nicholas; Zambelli, Joseph; Chen, Guang-Hong

    2014-01-01

    Purpose: This paper concerns the feasibility of x-ray differential phase contrast (DPC) tomosynthesis imaging using a grating-based DPC benchtop experimental system, which is equipped with a commercial digital flat-panel detector and a medical-grade rotating-anode x-ray tube. An extensive system characterization was performed to quantify its imaging performance. Methods: The major components of the benchtop system include a diagnostic x-ray tube with a 1.0 mm nominal focal spot size, a flat-panel detector with 96 μm pixel pitch, a sample stage that rotates within a limited angular span of ±30°, and a Talbot-Lau interferometer with three x-ray gratings. A total of 21 projection views acquired with 3° increments were used to reconstruct three sets of tomosynthetic image volumes, including the conventional absorption contrast tomosynthesis image volume (AC-tomo) reconstructed using the filtered-backprojection (FBP) algorithm with the ramp kernel, the phase contrast tomosynthesis image volume (PC-tomo) reconstructed using FBP with a Hilbert kernel, and the differential phase contrast tomosynthesis image volume (DPC-tomo) reconstructed using the shift-and-add algorithm. Three inhouse physical phantoms containing tissue-surrogate materials were used to characterize the signal linearity, the signal difference-to-noise ratio (SDNR), the three-dimensional noise power spectrum (3D NPS), and the through-plane artifact spread function (ASF). Results: While DPC-tomo highlights edges and interfaces in the image object, PC-tomo removes the differential nature of the DPC projection data and its pixel values are linearly related to the decrement of the real part of the x-ray refractive index. The SDNR values of polyoxymethylene in water and polystyrene in oil are 1.5 and 1.0, respectively, in AC-tomo, and the values were improved to 3.0 and 2.0, respectively, in PC-tomo. PC-tomo and AC-tomo demonstrate equivalent ASF, but their noise characteristics quantified by the 3D NPS

  18. Development and evaluation of a digital dental modeling method based on grating projection and reverse engineering software.

    Science.gov (United States)

    Zhou, Qin; Wang, Zhenzhen; Chen, Jun; Song, Jun; Chen, Lu; Lu, Yi

    2016-01-01

    For reasons of convenience and economy, attempts have been made to transform traditional dental gypsum casts into 3-dimensional (3D) digital casts. Different scanning devices have been developed to generate digital casts; however, each has its own limitations and disadvantages. The purpose of this study was to develop an advanced method for the 3D reproduction of dental casts by using a high-speed grating projection system and noncontact reverse engineering (RE) software and to evaluate the accuracy of the method. The methods consisted of 3 main steps: the scanning and acquisition of 3D dental cast data with a high-resolution grating projection system, the reconstruction and measurement of digital casts with RE software, and the evaluation of the accuracy of this method using 20 dental gypsum casts. The common anatomic landmarks were measured directly on the gypsum casts with a Vernier caliper and on the 3D digital casts with the Geomagic software measurement tool. Data were statistically assessed with the t test. The grating projection system had a rapid scanning speed, and smooth 3D dental casts were obtained. The mean differences between the gypsum and 3D measurements were approximately 0.05 mm, and no statistically significant differences were found between the 2 methods (P>.05), except for the measurements of the incisor tooth width and maxillary arch length. A method for the 3D reconstruction of dental casts was developed by using a grating projection system and RE software. The accuracy of the casts generated using the grating projection system was comparable with that of the gypsum casts. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  19. A novel biomimetic whisker technology based on fiber Bragg grating and its application

    Science.gov (United States)

    Zhao, Chenlu; Jiang, Qi; Li, Yibin

    2017-09-01

    The paper describes a novel, biomimetic whisker-based sensing technology following the basic design of the facial whiskers of animals such as rats and mice. The sensor consists of a 3× 2 whisker array on each side of a robot. In experiments with the artificial whiskers, the motor drives rotating whiskers, and the center wavelength of a fiber Bragg grating pasted on the whisker will shift when the whisker touches an obstacle. The distance will be obtained by processing the wavelength shift data with algorithms. Then the shape recognition can be realized by postprocessing the distance data. The experimental results prove that the whisker array is capable of accurately gathering the distance and shape information of an object.

  20. Phase sensitive distributed vibration sensing based on ultraweak fiber Bragg grating array using double-pulse

    Science.gov (United States)

    Liu, Tao; Wang, Feng; Zhang, Xuping; Zhang, Lin; Yuan, Quan; Liu, Yu; Yan, Zhijun

    2017-08-01

    A distributed vibration sensing technique using double-optical-pulse based on phase-sensitive optical time-domain reflectometry (ϕ-OTDR) and an ultraweak fiber Bragg grating (UWFBG) array is proposed for the first time. The single-mode sensing fiber is integrated with the UWFBG array that has uniform spatial interval and ultraweak reflectivity. The relatively high reflectivity of the UWFBG, compared with the Rayleigh scattering, gains a high signal-to-noise ratio for the signal, which can make the system achieve the maximum detectable frequency limited by the round-trip time of the probe pulse in fiber. A corresponding experimental ϕ-OTDR system with a 4.5 km sensing fiber integrated with the UWFBG array was setup for the evaluation of the system performance. Distributed vibration sensing is successfully realized with spatial resolution of 50 m. The sensing range of the vibration frequency can cover from 3 Hz to 9 kHz.

  1. Terahertz polarizing beam splitter based on copper grating on polyimide substrate

    Science.gov (United States)

    Zhang, Mengen; Li, Xiangjun; Wang, Wentao; Liu, Jianjun; Hong, Zhi

    2012-12-01

    A terahertz polarizing beam splitter, based on a copper grating on polyimide (PI) substrate, was fabricated by the way of laser induced and non-electrolytic plating. The good polarization characteristics of the splitter in the range of 0°-180°polarization are verified experimentally using backward wave oscillator at fixed frequency of 300GHz, and the insertion losses of 0.13dB and 0.32dB are measured for the transmitted and reflected beams, respectively. The broadband transmission of TM wave of the splitter was also measured by terahertz time-domain spectroscopy, and the extinction ratio larger than 22dB is obtained in the frequency range of 0.2-1.5THz. The experiment results are in good agreement with finite element simulation results.

  2. Optical Sensor of Thermal Gas Flow Based on Fiber Bragg Grating

    Directory of Open Access Journals (Sweden)

    Xu Jiang

    2017-02-01

    Full Text Available This paper aims at solving the problem of explosion proof in measurement of thermal gas flow using electronic sensor by presenting a new type of flow sensor by optical fiber heating. A measuring unit based on fiber Bragg grating (FBG for fluid temperature and a unit for heat dissipation are designed to replace the traditional electronic sensors. The light in C band from the amplified spontaneous emission (ASE light source is split, with one part used to heat the absorbing coating and the other part used in the signal processing unit. In the heating unit, an absorbing coating is introduced to replace the traditional resistance heating module to minimize the risk of explosion. The measurement results demonstrate a fine consistency between the flow and temperature difference in simulation. The method to enhance the measurement resolution of flow is also discussed.

  3. A simple self-restored fiber Bragg grating (FBG)-based passive sensing ring network

    International Nuclear Information System (INIS)

    Yeh, Chien-Hung; Chow, Chi-Wai; Wang, Chia-Husan; Shih, Fu-Yuan; Wu, Yu-Fu; Chi, Sien

    2009-01-01

    In this investigation, we propose and experimentally investigate a simple self-restored fiber Bragg grating (FBG)-based sensor ring system. This proposed multi-ring passive sensing architecture does not require active components in the network. In this experiment, the network survivability and capacity for the multi-point sensor systems are also enhanced. Besides, the tunable laser source (TLS) is adopted in a central office (CO) for FBG sensing. The survivability of an eight-point FBG sensor is examined and analyzed. It is cost effective since the sensing system is entirely centralized in the CO. Experimental results show that the proposed system can enhance the reliability of the FBG sensing network for large-scale and multi-point architecture. (rapid communication)

  4. Temperature-referenced high-sensitivity point-probe optical fiber chem-sensors based on cladding etched fiber Bragg gratings

    OpenAIRE

    Zhou, Kaiming; Chen, Xianfeng F.; Zhang, Lin; Bennion, Ian

    2004-01-01

    Point-probe optical fiber chem-sensors have been implemented using cladding etched fiber Bragg gratings. The sensors possess refractive index sensing capability that can be utilized to measure chemical concentrations. The Bragg wavelength shift reaches 8 nm when the index of surrounding medium changes from 1.33 to 1.44, giving maximum sensitivity more than 10 times higher than that of previously reported devices. More importantly, the dual-grating configuration of the point-probe sensors offe...

  5. Optical fiber Bragg gratings. Part II. Modeling of finite-length gratings and grating arrays.

    Science.gov (United States)

    Passaro, Vittorio M N; Diana, Roberto; Armenise, Mario N

    2002-09-01

    A model of both uniform finite-length optical fiber Bragg gratings and grating arrays is presented. The model is based on the Floquet-Bloch formalism and allows rigorous investigation of all the physical aspects in either single- or multiple-periodic structures realized on the core of a monomodal fiber. Analytical expressions of reflectivity and transmittivity for both single gratings and grating arrays are derived. The influence of the grating length and the index modulation amplitude on the reflected and transmitted optical power for both sinusoidal and rectangular profiles is evaluated. Good agreement between our method and the well-known coupled-mode theory (CMT) approach has been observed for both single gratings and grating arrays only in the case of weak index perturbation. Significant discrepancies exist there in cases of strong index contrast because of the increasing approximation of the CMT approach. The effects of intragrating phase shift are also shown and discussed.

  6. A new method for information retrieval in two-dimensional grating-based X-ray phase contrast imaging

    International Nuclear Information System (INIS)

    Wang Zhi-Li; Gao Kun; Chen Jian; Ge Xin; Tian Yang-Chao; Wu Zi-Yu; Zhu Pei-Ping

    2012-01-01

    Grating-based X-ray phase contrast imaging has been demonstrated to be an extremely powerful phase-sensitive imaging technique. By using two-dimensional (2D) gratings, the observable contrast is extended to two refraction directions. Recently, we have developed a novel reverse-projection (RP) method, which is capable of retrieving the object information efficiently with one-dimensional (1D) grating-based phase contrast imaging. In this contribution, we present its extension to the 2D grating-based X-ray phase contrast imaging, named the two-dimensional reverse-projection (2D-RP) method, for information retrieval. The method takes into account the nonlinear contributions of two refraction directions and allows the retrieval of the absorption, the horizontal and the vertical refraction images. The obtained information can be used for the reconstruction of the three-dimensional phase gradient field, and for an improved phase map retrieval and reconstruction. Numerical experiments are carried out, and the results confirm the validity of the 2D-RP method

  7. Bolometric Device Based on Fluxoid Quantization

    Science.gov (United States)

    Bonetti, Joseph A.; Kenyon, Matthew E.; Leduc, Henry G.; Day, Peter K.

    2010-01-01

    The temperature dependence of fluxoid quantization in a superconducting loop. The sensitivity of the device is expected to surpass that of other superconducting- based bolometric devices, such as superconducting transition-edge sensors and superconducting nanowire devices. Just as important, the proposed device has advantages in sample fabrication.

  8. Low-Cost Interrogation Technique for Dynamic Measurements with FBG-Based Devices.

    Science.gov (United States)

    Díaz, Camilo A R; Leitão, Cátia; Marques, Carlos A; Domingues, M Fátima; Alberto, Nélia; Pontes, Maria José; Frizera, Anselmo; Ribeiro, Moisés R N; André, Paulo S B; Antunes, Paulo F C

    2017-10-23

    Fiber Bragg gratings are widely used optical fiber sensors for measuring temperature and/or mechanical strain. Nevertheless, the high cost of the interrogation systems is the most important drawback for their large commercial application. In this work, an in-line Fabry-Perot interferometer based edge filter is explored in the interrogation of fiber Bragg grating dynamic measurements up to 5 kHz. Two devices an accelerometer and an arterial pulse wave probe were interrogated with the developed approach and the results were compared with a commercial interrogation monitor. The data obtained with the edge filter are in agreement with the commercial device, with a maximum RMSE of 0.05 being able to meet the requirements of the measurements. Resolutions of 3.6 pm and 2.4 pm were obtained, using the optical accelerometer and the arterial pulse wave probe, respectively.

  9. A Control and Detecting System of Micro-Near-Infrared Spectrometer Based on a MOEMS Scanning Grating Mirror

    Directory of Open Access Journals (Sweden)

    Haitao Liu

    2018-03-01

    Full Text Available Based on the scanning grating mirror we developed, this paper presents a method of the precise control of a scanning grating mirror and of high-speed spectrum data detection. In addition, the system circuit of the scanning grating mirror control and spectrum signal detecting is designed and manufactured in this paper. The mirror control system includes a drive generator module, an amplitude detection module, a feedback control module, and a variable gain amplification (VGA module; the detecting system includes a field programmable gate array (FPGA main control module, a synchronous trigger module, an analog-digital conversion (ADC module, and a universal serial bus (USB interface module. The final results of the experiment show that the control system has successfully realized the precision control of the swing of the scanning grating mirror and that the detecting system has successfully realized the high-speed acquisition and transmission of the spectral signal and the angle signals. The spectrum has been reconstructed according to the mathematical relationship between the wavelength λ and the angle β of the mirror. The resolution of the spectrometer reaches 10 nm in the wavelength range of 800–1800 nm, the signal-to-noise ratio (SNR of the spectrometer is 4562 at full scale, the spectrum data drift is 0.9% in 24 h, and the precision of the closed loop control is 0.06%.

  10. High-speed two-dimensional laser scanner based on Bragg gratings stored in photothermorefractive glass.

    Science.gov (United States)

    Yaqoob, Zahid; Arain, Muzammil A; Riza, Nabeel A

    2003-09-10

    A high-speed free-space wavelength-multiplexed optical scanner with high-speed wavelength selection coupled with narrowband volume Bragg gratings stored in photothermorefractive (PTR) glass is reported. The proposed scanner with no moving parts has a modular design with a wide angular scan range, accurate beam pointing, low scanner insertion loss, and two-dimensional beam scan capabilities. We present a complete analysis and design procedure for storing multiple tilted Bragg-grating structures in a single PTR glass volume (for normal incidence) in an optimal fashion. Because the scanner design is modular, many PTR glass volumes (each having multiple tilted Bragg-grating structures) can be stacked together, providing an efficient throughput with operations in both the visible and the infrared (IR) regions. A proof-of-concept experimental study is conducted with four Bragg gratings in independent PTR glass plates, and both visible and IR region scanner operations are demonstrated.

  11. Study on the weighing system based on optical fiber Bragg grating

    Science.gov (United States)

    Wang, Xiaona; Yu, Qingxu; Li, Yefang

    2010-10-01

    The optical fiber sensor based on wavelength demodulation such as fiber Bragg grating(FBG), with merits of immunity to electromagnetic interference, low drift and high precision, has been widely used in many areas, such as structural health monitoring and smart materials, and the wavelength demodulation system was also studied widely. In the paper, a weighing system based on FBG was studied. The optical source is broadband Erbium-doped fiber ring laser with a spectral range of 1500~1600nm and optical power of 2mW; A Fabry-Perot Etalon with orientation precision of 1pm was adopted as real-time wavelength calibration for the swept laser; and multichannel high resolution simultaneous sampling card was used in the system to acquire sensing signals simultaneously, thus high-resolution and real-time calibration of sweep-wavelength can be achieved. The FBG was adhered to a cantilever beam and the Bragg wavelength was demodulated with the system. The weighing system was done after calibrated with standard weight. Experimental results show that the resolution of the weighing system is 0.5 g with a full scale of 2Kg.

  12. Quantitative breast tissue characterization using grating-based x-ray phase-contrast imaging

    Science.gov (United States)

    Willner, M.; Herzen, J.; Grandl, S.; Auweter, S.; Mayr, D.; Hipp, A.; Chabior, M.; Sarapata, A.; Achterhold, K.; Zanette, I.; Weitkamp, T.; Sztrókay, A.; Hellerhoff, K.; Reiser, M.; Pfeiffer, F.

    2014-04-01

    X-ray phase-contrast imaging has received growing interest in recent years due to its high capability in visualizing soft tissue. Breast imaging became the focus of particular attention as it is considered the most promising candidate for a first clinical application of this contrast modality. In this study, we investigate quantitative breast tissue characterization using grating-based phase-contrast computed tomography (CT) at conventional polychromatic x-ray sources. Different breast specimens have been scanned at a laboratory phase-contrast imaging setup and were correlated to histopathology. Ascertained tumor types include phylloides tumor, fibroadenoma and infiltrating lobular carcinoma. Identified tissue types comprising adipose, fibroglandular and tumor tissue have been analyzed in terms of phase-contrast Hounsfield units and are compared to high-quality, high-resolution data obtained with monochromatic synchrotron radiation, as well as calculated values based on tabulated tissue properties. The results give a good impression of the method’s prospects and limitations for potential tumor detection and the associated demands on such a phase-contrast breast CT system. Furthermore, the evaluated quantitative tissue values serve as a reference for simulations and the design of dedicated phantoms for phase-contrast mammography.

  13. Intensity-based readout of resonant-waveguide grating biosensors: Systems and nanostructures

    Science.gov (United States)

    Paulsen, Moritz; Jahns, Sabrina; Gerken, Martina

    2017-09-01

    Resonant waveguide gratings (RWG) - also called photonic crystal slabs (PCS) - have been established as reliable optical transducers for label-free biochemical assays as well as for cell-based assays. Current readout systems are based on mechanical scanning and spectrometric measurements with system sizes suitable for laboratory equipment. Here, we review recent progress in compact intensity-based readout systems for point-of-care (POC) applications. We briefly introduce PCSs as sensitive optical transducers and introduce different approaches for intensity-based readout systems. Photometric measurements have been realized with a simple combination of a light source and a photodetector. Recently a 96-channel, intensity-based readout system for both biochemical interaction analyses as well as cellular assays was presented employing the intensity change of a near cut-off mode. As an alternative for multiparametric detection, a camera system for imaging detection has been implemented. A portable, camera-based system of size 13 cm × 4.9 cm × 3.5 cm with six detection areas on an RWG surface area of 11 mm × 7 mm has been demonstrated for the parallel detection of six protein binding kinetics. The signal-to-noise ratio of this system corresponds to a limit of detection of 168 M (24 ng/ml). To further improve the signal-to-noise ratio advanced nanostructure designs are investigated for RWGs. Here, results on multiperiodic and deterministic aperiodic nanostructures are presented. These advanced nanostructures allow for the design of the number and wavelengths of the RWG resonances. In the context of intensity-based readout systems they are particularly interesting for the realization of multi-LED systems. These recent trends suggest that compact point-of-care systems employing disposable test chips with RWG functional areas may reach market in the near future.

  14. Semiconductor-based, large-area, flexible, electronic devices

    Science.gov (United States)

    Goyal, Amit [Knoxville, TN

    2011-03-15

    Novel articles and methods to fabricate the same resulting in flexible, large-area, triaxially textured, single-crystal or single-crystal-like, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  15. A shape-adaptive thin-film-based approach for 50% high-efficiency energy generation through micro-grating sliding electrification.

    Science.gov (United States)

    Zhu, Guang; Zhou, Yu Sheng; Bai, Peng; Meng, Xian Song; Jing, Qingshen; Chen, Jun; Wang, Zhong Lin

    2014-06-18

    Effectively harvesting ambient mechanical energy is the key for realizing self-powered and autonomous electronics, which addresses limitations of batteries and thus has tremendous applications in sensor networks, wireless devices, and wearable/implantable electronics, etc. Here, a thin-film-based micro-grating triboelectric nanogenerator (MG-TENG) is developed for high-efficiency power generation through conversion of mechanical energy. The shape-adaptive MG-TENG relies on sliding electrification between complementary micro-sized arrays of linear grating, which offers a unique and straightforward solution in harnessing energy from relative sliding motion between surfaces. Operating at a sliding velocity of 10 m/s, a MG-TENG of 60 cm(2) in overall area, 0.2 cm(3) in volume and 0.6 g in weight can deliver an average output power of 3 W (power density of 50 mW cm(-2) and 15 W cm(-3)) at an overall conversion efficiency of ∼ 50%, making it a sufficient power supply to regular electronics, such as light bulbs. The scalable and cost-effective MG-TENG is practically applicable in not only harvesting various mechanical motions but also possibly power generation at a large scale. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Development of a high resolution plantar pressure monitoring pad based on fiber Bragg grating (FBG) sensors.

    Science.gov (United States)

    Suresh, R; Bhalla, S; Hao, J; Singh, C

    2015-01-01

    High importance is given to plantar pressure monitoring in the field of biomedical engineering for the diagnosis of posture related ailments associated with diseases such as diabetes and gonarthrosis. This paper presents the proof-of-concept development of a new high resolution plantar pressure monitoring pad based on fiber Bragg grating (FBG) sensors. In the proposed configuration, the FBG sensors are embedded within layers of carbon composite material (CCM) in turn conforming to an arc shape. A total of four such arc shaped sensors are instrumented in the pad at the locations of the forefoot and the hind foot. As a test of the pad, static plantar pressure is monitored on normal subjects under various posture conditions. The pad is evaluated both as a standalone platform as well as a pad inserted inside a standard shoe. An average pressure sensitivity of 1.2 pm/kPa and a resolution of approximately 0.8 kPa is obtained in this special configuration. The pad is found to be suitable in both configurations- stand-alone pad as well as an insert inside a standard shoe. The proposed set up offers a cost-effective high resolution and accurate plantar pressure measurement system suitable for clinical deployment. The novelty of the developed pressure pad lies in its ability to be used both as platform type as well as inserted in-sole type sensor system.

  17. A Fiber Bragg Grating-Based Monitoring System for Roof Safety Control in Underground Coal Mining

    Directory of Open Access Journals (Sweden)

    Yiming Zhao

    2016-10-01

    Full Text Available Monitoring of roof activity is a primary measure adopted in the prevention of roof collapse accidents and functions to optimize and support the design of roadways in underground coalmines. However, traditional monitoring measures, such as using mechanical extensometers or electronic gauges, either require arduous underground labor or cannot function properly in the harsh underground environment. Therefore, in this paper, in order to break through this technological barrier, a novel monitoring system for roof safety control in underground coal mining, using fiber Bragg grating (FBG material as a perceived element and transmission medium, has been developed. Compared with traditional monitoring equipment, the developed, novel monitoring system has the advantages of providing accurate, reliable, and continuous online monitoring of roof activities in underground coal mining. This is expected to further enable the prevention of catastrophic roof collapse accidents. The system has been successfully implemented at a deep hazardous roadway in Zhuji Coal Mine, China. Monitoring results from the study site have demonstrated the advantages of FBG-based sensors over traditional monitoring approaches. The dynamic impacts of progressive face advance on roof displacement and stress have been accurately captured by the novel roadway roof activity and safety monitoring system, which provided essential references for roadway support and design of the mine.

  18. An optomechatronic curvature measurement array based on fiber Bragg gratings

    International Nuclear Information System (INIS)

    Chang, Hsing-Cheng; Lin, Shyan-Lung; Hung, San-Shan; Chang, I-Nan; Chen, Ya-Hui; Lin, Jung-Chih; Liu, Wen-Fung

    2014-01-01

    This study investigated an optomechatronic array-integrated signal processing module and a human–machine interface based on fiber Bragg grating sensing elements embedded in an elastic support matrix that involves using a self-located electromagnetic mechanism for curvature sensing and solid contour reconstruction. Using bilinear interpolation and average calculation methods, the smooth and accurate surface contours of convex and concave lenses are reconstructed in real-time. The elastic supporting optical sensing array is self-balanced to reduce operational errors. Compared with our previous single-head sensor, the sensitivity of the proposed array is improved by more than 15%. In the curvature range from −20.15 to +27.09 m −1 , the sensitivities are 3.53 pm m for the convex measurement and 2.15 pm m for the concave measurement with an error rate below 8.89%. The curvature resolutions are 0.283 and 0.465 m −1 for convex and concave lenses, respectively. This array could be applied in the curvature measurement of solar collectors to monitor energy conversion efficiency or could be used to monitor the wafer-level thin-film fabrication process. (paper)

  19. Load Identification for a Cantilever Beam Based on Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    Xuegang Song

    2017-07-01

    Full Text Available Load identification plays an important role in structural health monitoring, which aims at preventing structural failures. In order to identify load for linear systems and nonlinear systems, this paper presents methods to identify load for a cantilever beam based on dynamic strain measurement by Fiber Bragg Grating (FBG sensors. For linear systems, the proposed inverse method consists of Kalman filter with no load terms and a linear estimator. For nonlinear systems, the proposed inverse method consists of cubature Kalman filter (CKF with no load terms and a nonlinear estimator. In the process of load identification, the state equations of the beam structures are constructed by using the finite element method (FEM. Kalman filter or CKF is used to suppress noise. The residual innovation sequences, gain matrix, and innovation covariance generated by Kalman filter or CKF are used to identify a load. To prove the effectiveness of the proposed method, numerical simulations and experiments of the beam structures are employed and the results show that the method has an excellent performance.

  20. An armored-cable-based fiber Bragg grating sensor array for perimeter fence intrusion detection

    Science.gov (United States)

    Hao, Jianzhong; Dong, Bo; Varghese, Paulose; Phua, Jiliang; Foo, Siang Fook

    2012-01-01

    In this paper, an armored-cable-based optical fiber Bragg grating (FBG) sensor array, for perimeter fence intrusion detection, is demonstrated and some of the field trial results are reported. The field trial was conducted at a critical local installation in Singapore in December 2010. The sensor array was put through a series of both simulated and live intrusion scenarios to test the stability and suitability of operation in the local environmental conditions and to determine its capabilities in detecting and reporting these intrusions accurately to the control station. Such a sensor array can provide perimeter intrusion detection with fine granularity and preset pin-pointing accuracy. The various types of intrusions included aided or unaided climbs, tampering and cutting of the fence, etc. The unique sensor packaging structure provides high sensitivity, crush resistance and protection against rodents. It is also capable of resolving nuisance events such as rain, birds sitting on the fence or seismic vibrations. These sensors are extremely sensitive with a response time of a few seconds. They can be customized for a desired spatial resolution and pre-determined sensitivity. Furthermore, it is easy to cascade a series of such sensors to monitor and detect intrusion events over a long stretch of fence line. Such sensors can be applied to real-time intrusion detection for perimeter security, pipeline security and communications link security.

  1. Impact Localization Method for Composite Plate Based on Low Sampling Rate Embedded Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    Zhuo Pang

    2017-01-01

    Full Text Available Fiber Bragg Grating (FBG sensors have been increasingly used in the field of Structural Health Monitoring (SHM in recent years. In this paper, we proposed an impact localization algorithm based on the Empirical Mode Decomposition (EMD and Particle Swarm Optimization-Support Vector Machine (PSO-SVM to achieve better localization accuracy for the FBG-embedded plate. In our method, EMD is used to extract the features of FBG signals, and PSO-SVM is then applied to automatically train a classification model for the impact localization. Meanwhile, an impact monitoring system for the FBG-embedded composites has been established to actually validate our algorithm. Moreover, the relationship between the localization accuracy and the distance from impact to the nearest sensor has also been studied. Results suggest that the localization accuracy keeps increasing and is satisfactory, ranging from 93.89% to 97.14%, on our experimental conditions with the decrease of the distance. This article reports an effective and easy-implementing method for FBG signal processing on SHM systems of the composites.

  2. Temperature Compensation Fiber Bragg Grating Pressure Sensor Based on Plane Diaphragm

    Science.gov (United States)

    Liang, Minfu; Fang, Xinqiu; Ning, Yaosheng

    2018-03-01

    Pressure sensors are the essential equipments in the field of pressure measurement. In this work, we propose a temperature compensation fiber Bragg grating (FBG) pressure sensor based on the plane diaphragm. The plane diaphragm and pressure sensitivity FBG (PS FBG) are used as the pressure sensitive components, and the temperature compensation FBG (TC FBG) is used to improve the temperature cross-sensitivity. Mechanical deformation model and deformation characteristics simulation analysis of the diaphragm are presented. The measurement principle and theoretical analysis of the mathematical relationship between the FBG central wavelength shift and pressure of the sensor are introduced. The sensitivity and measure range can be adjusted by utilizing the different materials and sizes of the diaphragm to accommodate different measure environments. The performance experiments are carried out, and the results indicate that the pressure sensitivity of the sensor is 35.7 pm/MPa in a range from 0 MPa to 50 MPa and has good linearity with a linear fitting correlation coefficient of 99.95%. In addition, the sensor has the advantages of low frequency chirp and high stability, which can be used to measure pressure in mining engineering, civil engineering, or other complex environment.

  3. Temperature Compensation Fiber Bragg Grating Pressure Sensor Based on Plane Diaphragm

    Science.gov (United States)

    Liang, Minfu; Fang, Xinqiu; Ning, Yaosheng

    2018-06-01

    Pressure sensors are the essential equipments in the field of pressure measurement. In this work, we propose a temperature compensation fiber Bragg grating (FBG) pressure sensor based on the plane diaphragm. The plane diaphragm and pressure sensitivity FBG (PS FBG) are used as the pressure sensitive components, and the temperature compensation FBG (TC FBG) is used to improve the temperature cross-sensitivity. Mechanical deformation model and deformation characteristics simulation analysis of the diaphragm are presented. The measurement principle and theoretical analysis of the mathematical relationship between the FBG central wavelength shift and pressure of the sensor are introduced. The sensitivity and measure range can be adjusted by utilizing the different materials and sizes of the diaphragm to accommodate different measure environments. The performance experiments are carried out, and the results indicate that the pressure sensitivity of the sensor is 35.7 pm/MPa in a range from 0 MPa to 50 MPa and has good linearity with a linear fitting correlation coefficient of 99.95%. In addition, the sensor has the advantages of low frequency chirp and high stability, which can be used to measure pressure in mining engineering, civil engineering, or other complex environment.

  4. Reconstruction of structural damage based on reflection intensity spectra of fiber Bragg gratings

    International Nuclear Information System (INIS)

    Huang, Guojun; Wei, Changben; Chen, Shiyuan; Yang, Guowei

    2014-01-01

    We present an approach for structural damage reconstruction based on the reflection intensity spectra of fiber Bragg gratings (FBGs). Our approach incorporates the finite element method, transfer matrix (T-matrix), and genetic algorithm to solve the inverse photo-elastic problem of damage reconstruction, i.e. to identify the location, size, and shape of a defect. By introducing a parameterized characterization of the damage information, the inverse photo-elastic problem is reduced to an optimization problem, and a relevant computational scheme was developed. The scheme iteratively searches for the solution to the corresponding direct photo-elastic problem until the simulated and measured (or target) reflection intensity spectra of the FBGs near the defect coincide within a prescribed error. Proof-of-concept validations of our approach were performed numerically and experimentally using both holed and cracked plate samples as typical cases of plane-stress problems. The damage identifiability was simulated by changing the deployment of the FBG sensors, including the total number of sensors and their distance to the defect. Both the numerical and experimental results demonstrate that our approach is effective and promising. It provides us with a photo-elastic method for developing a remote, automatic damage-imaging technique that substantially improves damage identification for structural health monitoring. (paper)

  5. Fiber Bragg Grating Sensors Based Monitoring System for Superconducting Accelerator Magnets

    CERN Document Server

    Chiuchiolo, A; Perez, J C; Bajas, H; Consales, M; Giordano, M; Breglio, G; Cusano, A

    2014-01-01

    New generation of accelerator magnets for high energy applications currently designed, manufactured and tested at the European Organization for Nuclear Research (CERN) require the implementation of precise cryogenic sensors with long-term robustness and reliability able to withstand cryogenic temperature and to monitor the mechanical stresses affecting the winding during all the stages of his service life, assembly, cool down and powering. Monitoring the mechanical behavior of the magnet from assembly to operation is a critical task which aims to assure the integrity of the magnet and to safely handle the coils made of new brittle material. This contribution deals with the first successful embedding of Fiber Bragg Grating sensors in a subscale Nb$_{3}$Sn dipole magnet in order to monitor the strain developed in the coil during the cool down to 1.9 K, the powering up to 15.8 kA and the warm up, offering new perspectives for the development of a complementary sensing technology based on fiber optic sensors.

  6. A volatile-solvent gas fiber sensor based on polyaniline film coated on superstructure fiber Bragg gratings

    International Nuclear Information System (INIS)

    Ai, L; Chen, T C; Su, W K; Mau, J C; Liu, W F

    2008-01-01

    A fiber sensor based on a polyaniline (PANI) film that is coated on the surface of an etched superstructure fiber grating to detect volatile solvent vapors is experimentally demonstrated. This sensing mechanism is based on the interaction of the testing gas with the polyaniline coating film, which changes the film index, resulting in a shift in the Bragg wavelength. The sensitivity of this sensor to ammonia (NH 3 ) gas is about 0.073 pm ppm −1 , which depends on the optical characteristics of the fiber grating, the diameter of the fiber cladding and the constituents of the sensing film. Methanol concentrations can also be measured using this sensing scheme. The sensitivity of this sensor must be improved to provide a simple, reliable, repeatable and non-destructive method for sensing various chemical gases. (technical design note)

  7. Quantitative Analysis of Micro-Structure in Meat Emulsions from Grating-Based Multimodal X-Ray Tomography

    DEFF Research Database (Denmark)

    Einarsdottir, Hildur; Nielsen, Mikkel Schou; Miklos, Rikke

    2013-01-01

    Using novel X-ray techniques, based on grating-interferometry, new imaging modalities can be obtained simultaneously with absorption computed tomography (CT). These modalities, called phase contrast and dark field imaging, measure the electron density and the diffusion length of the sample....... Enhanced contrast capabilities of this X-ray technique makes studies on materials with similar attenuation properties possible. In this paper the focus is set on processing grating-based X-ray tomograms of meat emulsions to quantitatively measure micro-structural changes due to heat treatment. The emulsion...... samples were imaged both in a raw and cooked state. Additionally, different fat types were used in the emulsions in order to compare micro-structural differences when either pork fat or sunflower oil was used. From the reconstructed tomograms the different ingredients in the emulsions were segmented using...

  8. Polymer optical fiber bragg grating sensors

    DEFF Research Database (Denmark)

    Stefani, Alessio; Yuan, Scott Wu; Andresen, Søren

    2010-01-01

    Fiber-optical accelerometers based on polymer optical fiber Bragg gratings are reported. We have written fiber Bragg gratings for 1550 nm and 850 nm operations, characterized their temperature and strain response, and tested their performance in a prototype accelerometer....

  9. A study of AFM-based scratch process on polycarbonate surface and grating application

    International Nuclear Information System (INIS)

    Choi, Chul Hyun; Lee, Dong Jin; Sung, Jun-Ho; Lee, Min Woo; Lee, Seung-Gol; Park, Se-Geun; Lee, El-Hang; O, Beom-Hoan

    2010-01-01

    We report on the possibility of applying atomic force microscope (AFM) lithography to draw micro/nano-structures on the surface of a polycarbonate (PC) substrate. We also fabricated a grating structure on the PC surface using the scratch method. An AFM silicon tip coated with a diamond layer was utilized as a cutting tool to scratch the surface of the sample. In order to obtain pattern depth deeper than the control method of interaction force, we used a scanner movement method which the sample scanner moves along the Z-axis. A grating of 100 μm x 150 μm was fabricated by the step and repeat method wherein the sample stage is moved in the direction of the XY-axis. The period and the depth of the grating are 500 and 50 nm, respectively. Light of 632.8 nm wavelength was diffracted on the surface of the PC substrate.

  10. Optical fiber refractometer based on tapered tilted-fiber Bragg grating

    Science.gov (United States)

    Wang, Tao; Liu, Tiegen; Liu, Kun; Jiang, Junfeng; Yu, Zhe; Xue, Meng

    2016-11-01

    Tilted fiber Bragg gratings (TFBGs) have been demonstrated to be accurate refractometers as they couple light from the fiber core to the cladding. In our experiment, we changed the physical structure of the TFBGs to improve the refractive index sensing ability. One way is to stretch the grating section 5 mm longer. The result showed that not only the number of the cladding mode of the TFBG decreases but also the full width half-maximum (FWHM) of the cladding modes and core mode changes. The FWHM of the cladding mode of the tapered TFBG is more than twice than that of the original. However, the refractive index sensitivity of the tapered TFBG has no obvious improvement. Another way is to etch the grating section with 20% hydrofluoric acid solution. We find that the smaller the clad diameter, the higher the refractive index sensitivity of the TFBG.

  11. Application of Notched Long-Period Fiber Grating Based Sensor for CO2 Gas Sensing

    Science.gov (United States)

    Wu, Chao-Wei; Chiang, Chia-Chin

    2016-01-01

    An inductively coupled plasma etching process to fabricate notched long-period fiber gratings for CO2 gas sensing is proposed in this article. In the gas sensing test, the 15% mixed CO2 gas was used for characterization of CO2 adsorption by the amine-modified nanoporous silica foams of the notched long-period fiber grating sensor. The results shows the spectra were changed with the CO2 gas flow within 13 min. During the absorption process, the transmission of the resonant dip was decreased by 2.884 dB. Therefore, the proposed notched long-period fiber grating gas sensor shows good performance and is suitable as a gas sensor for monitoring the CO2 adsorption process.

  12. Refractive index sensing based on higher-order mode reflection of a microfiber Bragg grating.

    Science.gov (United States)

    Zhang, Yu; Lin, Bo; Tjin, Swee Chuan; Zhang, Han; Wang, Guanghui; Shum, Ping; Zhang, Xinliang

    2010-12-06

    A fiber Bragg grating written in a photosensitive microfiber using KrF excimer laser via a uniform phase mask is demonstrated. We have successfully fabricated two Bragg gratings in microfibers having different diameters. In the reflection spectrum of a microfiber Bragg grating (MFBG), we observed two reflection peaks,which agrees with our numerical simulation results. Compared with the fundamental mode reflection, the higher-order reflection mode is more sensitive to the refractive index (RI) variation of the surrounding fluid due to its larger evanescent field. The measured maximum sensitivity is ~102 nm/RIU (RI unit) at an RI value of 1.378 in an MFBG with a diameter of 6 μm.

  13. Electrically modulated transparent liquid crystal-optical grating projection

    DEFF Research Database (Denmark)

    Buss, Thomas; Smith, Cameron; Kristensen, Anders

    2013-01-01

    A transparent, fully integrated electrically modulated projection technique is presented based on light guiding through a thin liquid crystal layer covering sub-wavelength gratings. The reported device operates at 10 V with response times of 4.5 ms. Analysis of the liquid crystal alignment shows...

  14. Bragg Grating Based Sensors in Microstructured Polymer Optical Fibers: Accelerometers and Microphones

    DEFF Research Database (Denmark)

    Stefani, Alessio

    With the growing interest towards fiber Bragg grating sensors and the growing ability in manufacturing polymer optical fibers, the development of polymer fiber Bragg sensors has catched the attention of industries with the goal of developing high performance sensors. This thesis presents...... and in microstructured fibers made of PMMA and TOPAS is reported. The gratings have been written at both 1550 nm, to take advantage of components made for telecommunications, and 850 nm, to exploit the lower loss of polymers and the fast acquisition electronics at this wavelength. A technique for writing multiplexed...

  15. Tunable dispersion compensator based on uniform fiber Bragg grating and its application to tunable pulse repetition-rate multiplication.

    Science.gov (United States)

    Han, Young-Geun; Lee, Sang

    2005-11-14

    A new technique to control the chromatic dispersion of a uniform fiber Bragg grating based on the symmetrical bending is proposed and experimentally demonstrated. The specially designed two translation stages with gears and a sawtooth wheel can simultaneously induce the tension and compression strain corresponding to the bending direction. The tension and compression strain can effectively control the chirp ratio along the fiber grating attached on a flexible cantilever beam and consequently the dispersion value without the center wavelength shift. We successfully achieve the wide tuning range of chromatic dispersion without the center wavelength shift, which is less than 0.02 nm. We also reduce the group delay ripple as low as ~+/-5 ps. And we also demonstrate the application of the proposed tunable dispersion compensation technique to the tunable pulse repetition-rate multiplication and obtain high-quality pulses at repetition rates of 20 ~ 40 GHz.

  16. Design of high-order all-optical temporal differentiators based on multiple-phase-shifted fiber Bragg gratings.

    Science.gov (United States)

    Kulishov, Mykola; Azaña, José

    2007-05-14

    A simple and general approach for designing practical all-optical (all-fiber) arbitrary-order time differentiators is introduced here for the first time. Specifically, we demonstrate that the Nth time derivative of an input optical waveform can be obtained by reflection of this waveform in a single uniform fiber Bragg grating (FBG) incorporating N &pi-phase shifts properly located along its grating profile. The general design procedure of an arbitrary-order optical time differentiator based on a multiple-phase-shifted FBG is described and numerically demonstrated for up to fourth-order time differentiation. Our simulations show that the proposed approach can provide optical operation bandwidths in the tens-of-GHz regime using readily feasible FBG structures.

  17. Measurements and simulations analysing the noise behaviour of grating-based X-ray phase-contrast imaging

    Energy Technology Data Exchange (ETDEWEB)

    Weber, T., E-mail: thomas.weber@physik.uni-erlangen.de [University of Erlangen-Nuremberg, ECAP - Erlangen Center for Astroparticle Physics, Erwin-Rommel-Str. 1, 91058 Erlangen (Germany); Bartl, P.; Durst, J. [University of Erlangen-Nuremberg, ECAP - Erlangen Center for Astroparticle Physics, Erwin-Rommel-Str. 1, 91058 Erlangen (Germany); Haas, W. [University of Erlangen-Nuremberg, ECAP - Erlangen Center for Astroparticle Physics, Erwin-Rommel-Str. 1, 91058 Erlangen (Germany); University of Erlangen-Nuremberg, Pattern Recognition Lab, Martensstr. 3, 91058 Erlangen (Germany); Michel, T.; Ritter, A.; Anton, G. [University of Erlangen-Nuremberg, ECAP - Erlangen Center for Astroparticle Physics, Erwin-Rommel-Str. 1, 91058 Erlangen (Germany)

    2011-08-21

    In the last decades, phase-contrast imaging using a Talbot-Lau grating interferometer is possible even with a low-brilliance X-ray source. With the potential of increasing the soft-tissue contrast, this method is on its way into medical imaging. For this purpose, the knowledge of the underlying physics of this technique is necessary. With this paper, we would like to contribute to the understanding of grating-based phase-contrast imaging by presenting results on measurements and simulations regarding the noise behaviour of the differential phases. These measurements were done using a microfocus X-ray tube with a hybrid, photon-counting, semiconductor Medipix2 detector. The additional simulations were performed by our in-house developed phase-contrast simulation tool 'SPHINX', combining both wave and particle contributions of the simulated photons. The results obtained by both of these methods show the same behaviour. Increasing the number of photons leads to a linear decrease of the standard deviation of the phase. The number of used phase steps has no influence on the standard deviation, if the total number of photons is held constant. Furthermore, the probability density function (pdf) of the reconstructed differential phases was analysed. It turned out that the so-called von Mises distribution is the physically correct pdf, which was also confirmed by measurements. This information advances the understanding of grating-based phase-contrast imaging and can be used to improve image quality.

  18. Faster diffraction-based overlay measurements with smaller targets using 3D gratings

    Science.gov (United States)

    Li, Jie; Kritsun, Oleg; Liu, Yongdong; Dasari, Prasad; Volkman, Catherine; Hu, Jiangtao

    2012-03-01

    Diffraction-based overlay (DBO) technologies have been developed to address the overlay metrology challenges for 22nm technology node and beyond. Most DBO technologies require specially designed targets that consist of multiple measurement pads, which consume too much space and increase measurement time. The traditional empirical approach (eDBO) using normal incidence spectroscopic reflectometry (NISR) relies on linear response of the reflectance with respect to overlay displacement within a small range. It offers convenience of quick recipe setup since there is no need to establish a model. However it requires three or four pads per direction (x or y) which adds burden to throughput and target size. Recent advances in modeling capability and computation power enabled mDBO, which allows overlay measurement with reduced number of pads, thus reducing measurement time and DBO target space. In this paper we evaluate the performance of single pad mDBO measurements using two 3D targets that have different grating shapes: squares in boxes and L-shapes in boxes. Good overlay sensitivities are observed for both targets. The correlation to programmed shifts and image-based overlay (IBO) is excellent. Despite the difference in shapes, the mDBO results are comparable for square and L-shape targets. The impact of process variations on overlay measurements is studied using a focus and exposure matrix (FEM) wafer. Although the FEM wafer has larger process variations, the correlation of mDBO results with IBO measurements is as good as the normal process wafer. We demonstrate the feasibility of single pad DBO measurements with faster throughput and smaller target size, which is particularly important in high volume manufacturing environment.

  19. Wearable sensors in intelligent clothing for measuring human body temperature based on optical fiber Bragg grating.

    Science.gov (United States)

    Li, Hongqiang; Yang, Haijing; Li, Enbang; Liu, Zhihui; Wei, Kejia

    2012-05-21

    Measuring body temperature is considerably important to physiological studies as well as clinical investigations. In recent years, numerous observations have been reported and various methods of measurement have been employed. The present paper introduces a novel wearable sensor in intelligent clothing for human body temperature measurement. The objective is the integration of optical fiber Bragg grating (FBG)-based sensors into functional textiles to extend the capabilities of wearable solutions for body temperature monitoring. In addition, the temperature sensitivity is 150 pm/°C, which is almost 15 times higher than that of a bare FBG. This study combines large and small pipes during fabrication to implant FBG sensors into the fabric. The law of energy conservation of the human body is considered in determining heat transfer between the body and its clothing. The mathematical model of heat transmission between the body and clothed FBG sensors is studied, and the steady-state thermal analysis is presented. The simulation results show the capability of the material to correct the actual body temperature. Based on the skin temperature obtained by the weighted average method, this paper presents the five points weighted coefficients model using both sides of the chest, armpits, and the upper back for the intelligent clothing. The weighted coefficients of 0.0826 for the left chest, 0.3706 for the left armpit, 0.3706 for the right armpit, 0.0936 for the upper back, and 0.0826 for the right chest were obtained using Cramer's Rule. Using the weighting coefficient, the deviation of the experimental result was ± 0.18 °C, which favors the use for clinical armpit temperature monitoring. Moreover, in special cases when several FBG sensors are broken, the weighted coefficients of the other sensors could be changed to obtain accurate body temperature.

  20. The in-focus variable line spacing plane grating monochromator

    International Nuclear Information System (INIS)

    Reininger, R.

    2011-01-01

    The in-focus variable line spacing plane grating monochromator is based on only two plane optical elements, a variable line spacing plane grating and a plane pre-mirror that illuminates the grating at the angle of incidence that will focus the required photon energy. A high throughput beamline requires only a third optical element after the exit slit, an aberration corrected elliptical toroid. Since plane elements can be manufactured with the smallest figure errors, this monochromator design can achieve very high resolving power. Furthermore, this optical design can correct the deformations induced by the heat load on the optics along the dispersion plane. This should allow obtaining a resolution of 10 meV at 1 keV with currently achievable figure errors on plane optics. The position of the photon source when an insertion device center is not located at the center of the straight section, a common occurrence in new insertion device beamlines, is investigated.

  1. Curved VPH gratings for novel spectrographs

    Science.gov (United States)

    Clemens, J. Christopher; O'Donoghue, Darragh; Dunlap, Bart H.

    2014-07-01

    The introduction of volume phase holographic (VPH) gratings into astronomy over a decade ago opened new possibilities for instrument designers. In this paper we describe an extension of VPH grating technology that will have applications in astronomy and beyond: curved VPH gratings. These devices can disperse light while simultaneously correcting aberrations. We have designed and manufactured two different kinds of convex VPH grating prototypes for use in off-axis reflecting spectrographs. One type functions in transmission and the other in reflection, enabling Offnerstyle spectrographs with the high-efficiency and low-cost advantages of VPH gratings. We will discuss the design process and the tools required for modelling these gratings along with the recording layout and process steps required to fabricate them. We will present performance data for the first convex VPH grating produced for an astronomical spectrograph.

  2. All-optical wavelength converter based on fiber cross-phase modulation and fiber Bragg grating

    Czech Academy of Sciences Publication Activity Database

    Honzátko, Pavel

    2010-01-01

    Roč. 283, č. 9 (2010), s. 1744-1749 ISSN 0030-4018 R&D Projects: GA AV ČR 1ET300670502 Institutional research plan: CEZ:AV0Z20670512 Keywords : Wavelength conversion * Fiber cross phase modulation * Fiber Bragg grating Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.517, year: 2010

  3. Time-dependent variation of fiber Bragg grating reflectivity in PMMA-based polymer optical fibers

    DEFF Research Database (Denmark)

    Saez-Rodriguez, D.; Nielsen, Kristian; Bang, Ole

    2015-01-01

    the material photosensitivity. After the inscription, the strain was released, and the FBGs spectra were monitored. We initially observed a decrease of the reflection down to zero after which it began to increase. After that, strain tests were carried out to confirm the results, and finally the gratings were...

  4. Optical fiber grating based technologies and their applications: from nuclear fusion to medical

    NARCIS (Netherlands)

    Cheng, L.K.; Vliegenhart, W.A.; Habisreuther, T.

    2012-01-01

    In the last decades, Fiber Optic (FO) sensor has gained increasing acceptance. Among the different FO sensor types, Fiber Bragg Grating is most widely used due to its commercial availability and the unique multiplexing potential. The latter feature enables the development of large sensor array

  5. Fiber-optic anemometer based on single-walled carbon nanotube coated tilted fiber Bragg grating.

    Science.gov (United States)

    Zhang, Yang; Wang, Fang; Liu, Zigeng; Duan, Zhihui; Cui, Wenli; Han, Jie; Gu, Yiying; Wu, Zhenlin; Jing, Zhenguo; Sun, Changsen; Peng, Wei

    2017-10-02

    In this work, a novel and simple optical fiber hot-wire anemometer based on single-walled carbon nanotubes (SWCNTs) coated tilted fiber Bragg grating (TFBG) is proposed and demonstrated. For the hot-wire wind speed sensor design, TFBG is an ideal in-fiber sensing structure due to its unique features. It is utilized as both light coupling and temperature sensing element without using any geometry-modified or uncommon fiber, which simplifies the sensor structure. To further enhance the thermal conversion capability, SWCNTs are coated on the surface of the TFBG instead of traditional metallic materials, which have excellent thermal characteristics. When a laser light is pumped into the sensor, the pump light propagating in the core will be easily coupled into cladding of the fiber via the TFBG and strongly absorbed by the SWCNTs thin film. This absorption acts like a hot-wire raising the local temperature of the fiber, which is accurately detected by the TFBG resonance shift. In the experiments, the sensor's performances were investigated and controlled by adjusting the inherent angle of the TFBG, the thickness of SWCNTs film, and the input power of the pump laser. It was demonstrated that the developed anemometer exhibited significant light absorption efficiency up to 93%, and the maximum temperature of the local area on the fiber was heated up to 146.1°C under the relatively low pump power of 97.76 mW. The sensitivity of -0.3667 nm/(m/s) at wind speed of 1.0 m/s was measured with the selected 12° TFBG and 1.6 μm film.

  6. Dual fiber Bragg gratings configuration-based fiber acoustic sensor for low-frequency signal detection

    Science.gov (United States)

    Yang, Dong; Wang, Shun; Lu, Ping; Liu, Deming

    2014-11-01

    We propose and fabricate a new type fiber acoustic sensor based on dual fiber Bragg gratings (FBGs) configuration. The acoustic sensor head is constructed by putting the sensing cells enclosed in an aluminum cylinder space built by two Cband FBGs and a titanium diaphragm of 50 um thickness. One end of each FBG is longitudinally adhered to the diaphragm by UV glue. Both of the two FBGs are employed for reflecting light. The dual FBGs play roles not only as signal transmission system but also as sensing component, and they demodulate each other's optical signal mutually during the measurement. Both of the two FBGs are pre-strained and the output optical power experiences fluctuation in a linear relationship along with a variation of axial strain and surrounding acoustic interference. So a precise approach to measure the frequency and sound pressure of the acoustic disturbance is achieved. Experiments are performed and results show that a relatively flat frequency response in a range from 200 Hz to 1 kHz with the average signal-to-noise ratio (SNR) above 21 dB is obtained. The maximum sound pressure sensitivity of 11.35mV/Pa is achieved with the Rsquared value of 0.99131 when the sound pressure in the range of 87.7-106.6dB. It has potential applications in low frequency signal detection. Owing to its direct self-demodulation method, the sensing system reveals the advantages of easy to demodulate, good temperature stability and measurement reliability. Besides, performance of the proposed sensor could be improved by optimizing the parameters of the sensor, especially the diaphragm.

  7. Design of all-optical high-order temporal integrators based on multiple-phase-shifted Bragg gratings.

    Science.gov (United States)

    Asghari, Mohammad H; Azaña, José

    2008-07-21

    In exact analogy with their electronic counterparts, photonic temporal integrators are fundamental building blocks for constructing all-optical circuits for ultrafast information processing and computing. In this work, we introduce a simple and general approach for realizing all-optical arbitrary-order temporal integrators. We demonstrate that the N(th) cumulative time integral of the complex field envelope of an input optical waveform can be obtained by simply propagating this waveform through a single uniform fiber/waveguide Bragg grating (BG) incorporating N pi-phase shifts along its axial profile. We derive here the design specifications of photonic integrators based on multiple-phase-shifted BGs. We show that the phase shifts in the BG structure can be arbitrarily located along the grating length provided that each uniform grating section (sections separated by the phase shifts) is sufficiently long so that its associated peak reflectivity reaches nearly 100%. The resulting designs are demonstrated by numerical simulations assuming all-fiber implementations. Our simulations show that the proposed approach can provide optical operation bandwidths in the tens-of-GHz regime using readily feasible photo-induced fiber BG structures.

  8. Enhanced Raman scattering in porous silicon grating.

    Science.gov (United States)

    Wang, Jiajia; Jia, Zhenhong; Lv, Changwu

    2018-03-19

    The enhancement of Raman signal on monocrystalline silicon gratings with varying groove depths and on porous silicon grating were studied for a highly sensitive surface enhanced Raman scattering (SERS) response. In the experiment conducted, porous silicon gratings were fabricated. Silver nanoparticles (Ag NPs) were then deposited on the porous silicon grating to enhance the Raman signal of the detective objects. Results show that the enhancement of Raman signal on silicon grating improved when groove depth increased. The enhanced performance of Raman signal on porous silicon grating was also further improved. The Rhodamine SERS response based on Ag NPs/ porous silicon grating substrates was enhanced relative to the SERS response on Ag NPs/ porous silicon substrates. Ag NPs / porous silicon grating SERS substrate system achieved a highly sensitive SERS response due to the coupling of various Raman enhancement factors.

  9. Point-by-point written fiber-Bragg gratings and their application in complex grating designs.

    Science.gov (United States)

    Marshall, Graham D; Williams, Robert J; Jovanovic, Nemanja; Steel, M J; Withford, Michael J

    2010-09-13

    The point-by-point technique of fabricating fibre-Bragg gratings using an ultrafast laser enables complete control of the position of each index modification that comprises the grating. By tailoring the local phase, amplitude and spacing of the grating's refractive index modulations it is possible to create gratings with complex transmission and reflection spectra. We report a series of grating structures that were realized by exploiting these flexibilities. Such structures include gratings with controlled bandwidth, and amplitude- and phase-modulated sampled (or superstructured) gratings. A model based on coupled-mode theory provides important insights into the manufacture of such gratings. Our approach offers a quick and easy method of producing complex, non-uniform grating structures in both fibres and other mono-mode waveguiding structures.

  10. Ultra-Low Loss, Chip-Based Hollow-Core Waveguide Using High-Contrast Grating

    Science.gov (United States)

    2011-09-28

    AND ADDRESS(ES) 10. SPONSORIMONITQR’S ACR.ONYM(S> DARPA/CMO Michael Blackstone 3701 N. Fairfax Drive 11. SPONSORING.IM.ONITORING Arlington, VA 22203...Scale-up of basic waveguides and devices into a delay-based processor whose performance is commensurate with a realistic military environment ...fundamental mode scattering into high order modes, which have much higher propagation losses. The noise is due to environmental vibration and defects along

  11. Organic Nonvolatile Memory Devices Based on Ferroelectricity

    NARCIS (Netherlands)

    Naber, Ronald C. G.; Asadi, Kamal; Blom, Paul W. M.; de Leeuw, Dago M.; de Boer, Bert

    2010-01-01

    A memory functionality is a prerequisite for many applications of electronic devices. Organic nonvolatile memory devices based on ferroelectricity are a promising approach toward the development of a low-cost memory technology. In this Review Article we discuss the latest developments in this area

  12. Organic nonvolatile memory devices based on ferroelectricity

    NARCIS (Netherlands)

    Naber, R.C.G.; Asadi, K.; Blom, P.W.M.; Leeuw, D.M. de; Boer, B. de

    2010-01-01

    A memory functionality is a prerequisite for many applications of electronic devices. Organic nonvolatile memory devices based on ferroelectricity are a promising approach toward the development of a low-cost memory technology. In this Review Article we discuss the latest developments in this area

  13. Building blocks of Collagen based biomaterial devices

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Building blocks of Collagen based biomaterial devices. Collagen as a protein. Collagen in tissues and organs. Stabilizing and cross linking agents. Immunogenicity. Hosts (drugs). Controlled release mechanisms of hosts. Biodegradability, workability into devices ...

  14. Ultra-sensitive quasi-distributed temperature sensor based on an apodized fiber Bragg grating.

    Science.gov (United States)

    Mohammed, Nazmi A; El Serafy, Hatem O

    2018-01-10

    This work targets a remarkable quasi-distributed temperature sensor based on an apodized fiber Bragg grating. To achieve this, the mathematical formula for a proposed apodization function is carried out and tested. Then, an optimization parametric process required to achieve the remarkable accuracy that is based on coupled mode theory (CMT) is done. A detailed investigation for the side lobe analysis, which is a primary judgment factor, especially in quasi-distributed configuration, is investigated. A comparison between elite selection of apodization profiles (extracted from related literatures) and the proposed modified-Nuttal profile is carried out covering reflectivity peak, full width half maximum (FWHM), and side lobe analysis. The optimization process concludes that the proposed modified-Nuttal profile with a length (L) of 15 mm and refractive index modulation amplitude (Δn) of 1.4×10 -4 is the optimum choice for single-stage and quasi-distributed temperature sensor networks. At previous values, the proposed profile achieves an acceptable reflectivity peak of 10 -0.426   dB, acceptable FWHM of 0.0808 nm, lowest side lobe maximum (SL max) of 7.037×10 -12   dB, lowest side lobe average (SL avg) of 3.883×10 -12   dB, and lowest side lobe suppression ratio (SLSR) of 1.875×10 -11   dB. These optimized characteristics lead to an accurate single-stage sensor with a temperature sensitivity of 0.0136 nm/°C. For the quasi-distributed scenario, a noteworthy total isolation of 91 dB is achieved without temperature, and an isolation of 4.83 dB is achieved while applying temperature of 110°C for a five-stage temperature-sensing network. Further investigation is made proving that consistency in choosing the apodization profile in the quasi-distributed network is mandatory. If the consistency condition is violated, the proposed profile still survives with a casualty of side lobe level rise of -73.2070  dB when adding uniform apodization and

  15. Wavelength interrogation of fiber Bragg grating sensors based on crossed optical Gaussian filters.

    Science.gov (United States)

    Cheng, Rui; Xia, Li; Zhou, Jiaao; Liu, Deming

    2015-04-15

    Conventional intensity-modulated measurements require to be operated in linear range of filter or interferometric response to ensure a linear detection. Here, we present a wavelength interrogation system for fiber Bragg grating sensors where the linear transition is achieved with crossed Gaussian transmissions. This unique filtering characteristic makes the responses of the two branch detections follow Gaussian functions with the same parameters except for a delay. The substraction of these two delayed Gaussian responses (in dB) ultimately leads to a linear behavior, which is exploited for the sensor wavelength determination. Beside its flexibility and inherently power insensitivity, the proposal also shows a potential of a much wider operational range. Interrogation of a strain-tuned grating was accomplished, with a wide sensitivity tuning range from 2.56 to 8.7 dB/nm achieved.

  16. Design of fused-silica rectangular transmission gratings for polarizing beam splitter based on modal method.

    Science.gov (United States)

    Zhao, Huajun; Yuan, Dairong

    2010-02-10

    Examples of optimal designs for a fused-silica transmitted grating with high-intensity tolerance are discussed. It has the potential of placing up to 99% incident polarized light in a single diffraction order. The modal method has been used to analyze the effective indices for TE and TM polarization propagating through the grating region, and the eigenvalue equation of the modal method is transformed to a new form. It is shown that the effective indices of the first two modes depend on the value of the period under Littrow mounting with filling factor f=0.5. The polarization properties of the polarizing beam splitter are analyzed by rigorous coupled-wave analysis (RCWA) at the wavelength of 1.064 microm. The optimal design perfectly matches the RCWA simulation result.

  17. All-Si photodetector for telecommunication wavelength based on subwavelength grating structure and critical coupling

    Directory of Open Access Journals (Sweden)

    Alireza Taghizadeh

    2017-09-01

    Full Text Available We propose an efficient planar all-Si internal photoemission photodetector operating at the telecommunication wavelength of 1550 nm and numerically investigate its optical and electrical properties. The proposed polarization-sensitive detector is composed of an appropriately engineered subwavelength grating structure topped with a silicide layer of nanometers thickness as an absorbing material. It is shown that a nearly-perfect light absorption is possible for the thin silicide layer by its integration to the grating resonator. The absorption is shown to be maximized when the critical coupling condition is satisfied. Simulations show that the external quantum efficiency of the proposed photodetector with a 2-nm-thick PtSi absorbing layer at the center wavelength of 1550 nm can reach up to ∼60%.

  18. Characterization of imprinted gratings based on transparent materials by transmission scatterometry

    KAUST Repository

    Pietroy, David; Gereige, Issam; Gourgon, Cé cile

    2013-01-01

    Transmission scatterometry is studied as a characterization tool for gratings nanoimprinted in a resist layer spincoated on the top of a transparent substrate. In this case, the larger part of the incident signal is transmitted which can make the reflection analysis harder. Although the backward reflections in the substrate induce an error which is difficult to correct, results are shown to be in good agreement with SEM measurements and reflection mode scatteromerty. © 2013 Elsevier B.V. All rights reserved.

  19. Characterization of imprinted gratings based on transparent materials by transmission scatterometry

    KAUST Repository

    Pietroy, David

    2013-06-01

    Transmission scatterometry is studied as a characterization tool for gratings nanoimprinted in a resist layer spincoated on the top of a transparent substrate. In this case, the larger part of the incident signal is transmitted which can make the reflection analysis harder. Although the backward reflections in the substrate induce an error which is difficult to correct, results are shown to be in good agreement with SEM measurements and reflection mode scatteromerty. © 2013 Elsevier B.V. All rights reserved.

  20. Ontology-Based Device Descriptions and Device Repository for Building Automation Devices

    Directory of Open Access Journals (Sweden)

    Dibowski Henrik

    2011-01-01

    Full Text Available Device descriptions play an important role in the design and commissioning of modern building automation systems and help reducing the design time and costs. However, all established device descriptions are specialized for certain purposes and suffer from several weaknesses. This hinders a further design automation, which is strongly needed for the more and more complex building automation systems. To overcome these problems, this paper presents novel Ontology-based Device Descriptions (ODDs along with a layered ontology architecture, a specific ontology view approach with virtual properties, a generic access interface, a triple store-based database backend, and a generic search mask GUI with underlying query generation algorithm. It enables a formal, unified, and extensible specification of building automation devices, ensures their comparability, and facilitates a computer-enabled retrieval, selection, and interoperability evaluation, which is essential for an automated design. The scalability of the approach to several ten thousand devices is demonstrated.

  1. Fabrication of large area plasmonic nanoparticle grating structure on silver halide based transmission electron microscope film and its application as a surface enhanced Raman spectroscopy substrate

    International Nuclear Information System (INIS)

    Sudheer,; Tiwari, P.; Singh, M. N.; Sinha, A. K.; Rai, V. N.; Srivastava, A. K.; Bhartiya, S.; Mukherjee, C.

    2015-01-01

    The plasmonic responses of silver nanoparticle grating structures of different periods made on silver halide based electron microscope film are investigated. Raster scan of the conventional scanning electron microscope (SEM) is used to carry out electron beam lithography for fabricating the plasmonic nanoparticle grating (PNG) structures. Morphological characterization of the PNG structures, carried out by the SEM and the atomic force microscope, indicates that the depth of the groove decreases with a decrease in the grating period. Elemental characterization performed by the energy dispersive spectroscopy and the x-ray diffraction shows the presence of nanoparticles of silver in the PNG grating. The optical characterization of the gratings shows that the localized surface plasmon resonance peak shifts from 366 to 378 nm and broadens with a decrease in grating period from 10 to 2.5 μm. The surface enhanced Raman spectroscopy of the Rhodamine-6G dye coated PNG structure shows the maximum enhancement by two orders of magnitude in comparison to the randomly distributed silver nanoparticles having similar size and shape as the PNG structure

  2. Fiber-Optic Refractometer Based on an Etched High-Q ?-Phase-Shifted Fiber-Bragg-Grating

    OpenAIRE

    Zhang, Qi; Ianno, Natale J.; Han, Ming

    2013-01-01

    We present a compact and highly-sensitive fiber-optic refractometer based on a high-Q p-phase-shifted fiber-Bragg-grating (pFBG) that is chemically etched to the core of the fiber. Due to the p phase-shift, a strong pFBG forms a high-Q optical resonator and the reflection spectrum features an extremely narrow notch that can be used for highly sensitivity refractive index measurement. The etched pFBG demonstrated here has a diameter of ~9.3 μm and a length of only 7 mm, leading to a refractive...

  3. Fiber Optic Bragg Gratings

    National Research Council Canada - National Science Library

    Battiato, James

    1998-01-01

    Coupled mode theory was used to model reflection fiber gratings. The effects of experimental parameters on grating characteristics were modeled for both uniform and non-uniform grating profiles using this approach...

  4. A user-friendly LabVIEW software platform for grating based X-ray phase-contrast imaging.

    Science.gov (United States)

    Wang, Shenghao; Han, Huajie; Gao, Kun; Wang, Zhili; Zhang, Can; Yang, Meng; Wu, Zhao; Wu, Ziyu

    2015-01-01

    X-ray phase-contrast imaging can provide greatly improved contrast over conventional absorption-based imaging for weakly absorbing samples, such as biological soft tissues and fibre composites. In this study, we introduced an easy and fast way to develop a user-friendly software platform dedicated to the new grating-based X-ray phase-contrast imaging setup at the National Synchrotron Radiation Laboratory of the University of Science and Technology of China. The control of 21 motorized stages, of a piezoelectric stage and of an X-ray tube are achieved with this software, it also covers image acquisition with a flat panel detector for automatic phase stepping scan. Moreover, a data post-processing module for signals retrieval and other custom features are in principle available. With a seamless integration of all the necessary functions in one software package, this platform greatly facilitate users' activities during experimental runs with this grating based X-ray phase contrast imaging setup.

  5. All-optical LAN architectures based on arrayed waveguide grating multiplexers

    Science.gov (United States)

    Woesner, Hagen

    1998-10-01

    The paper presents optical LAN topologies which are made possible using an Arrayed Waveguide Grating Multiplexer (AWGM) instead of a passive star coupler to interconnect stations in an all-optical LAN. Due to the collision-free nature of an AWGM it offers the n-fold bandwidth compared to the star coupler. Virtual ring topologies appear (one ring on each wavelength) if the number of stations attached to the AWGM is a prime number. A method to construct larger networks using Cayley graphs is shown. An access protocol to avoid collisions on the proposed network is outlined.

  6. Simulation of path delay multiplexing-based Fourier transform spectrometer for fiber Bragg grating interrogation.

    Science.gov (United States)

    Chelliah, Pandian; Sahoo, Trilochan; Singh, Sheela; Sujatha, Annie

    2015-10-20

    A Fourier transform spectrometer (FTS) used for interrogating a fiber Bragg grating (FBG) consists of a scanning-type interferometer. The FTS has a broad wavelength range of operation and good multiplexing capability. However, it has poor wavelength resolution and interrogation speed. We propose a modification to the FTS using path delay multiplexing to improve the same. Using this method, spatial resolution and interrogation time can be improved by n times by using n path delays. In this paper, simulation results for n=2, 5 are shown.

  7. Progress of Terahertz Devices Based on Graphene

    Institute of Scientific and Technical Information of China (English)

    Mai-Xia Fu; Yan Zhang

    2013-01-01

    Graphene is a one-atom-thick planar sheet of sp2-hybridized orbital bonded honeycomb carbon crystal. Its gapless and linear energy spectra of electrons and holes lead to the unique carrier transport and optical properties, such as giant carrier mobility and broadband flat optical response. As a novel material, graphene has been regarded to be extremely suitable and competent for the development of terahertz (THz) optical devices. In this paper, the fundamental electronic and optic properties of graphene are described. Based on the energy band structure and light transmittance properties of graphene, many novel graphene based THz devices have been proposed, including modulator, generator, detector, and imaging device. This progress has been reviewed. Future research directions of the graphene devices for THz applications are also proposed.

  8. Graphene devices based on laser scribing technology

    Science.gov (United States)

    Qiao, Yan-Cong; Wei, Yu-Hong; Pang, Yu; Li, Yu-Xing; Wang, Dan-Yang; Li, Yu-Tao; Deng, Ning-Qin; Wang, Xue-Feng; Zhang, Hai-Nan; Wang, Qian; Yang, Zhen; Tao, Lu-Qi; Tian, He; Yang, Yi; Ren, Tian-Ling

    2018-04-01

    Graphene with excellent electronic, thermal, optical, and mechanical properties has great potential applications. The current devices based on graphene grown by micromechanical exfoliation, chemical vapor deposition (CVD), and thermal decomposition of silicon carbide are still expensive and inefficient. Laser scribing technology, a low-cost and time-efficient method of fabricating graphene, is introduced in this review. The patterning of graphene can be directly performed on solid and flexible substrates. Therefore, many novel devices such as strain sensors, acoustic devices, memory devices based on laser scribing graphene are fabricated. The outlook and challenges of laser scribing technology have also been discussed. Laser scribing may be a potential way of fabricating wearable and integrated graphene systems in the future.

  9. Fiber-optic refractometer based on an etched high-Q π-phase-shifted fiber-Bragg-grating.

    Science.gov (United States)

    Zhang, Qi; Ianno, Natale J; Han, Ming

    2013-07-10

    We present a compact and highly-sensitive fiber-optic refractometer based on a high-Q π-phase-shifted fiber-Bragg-grating (πFBG) that is chemically etched to the core of the fiber. Due to the p phase-shift, a strong πFBG forms a high-Q optical resonator and the reflection spectrum features an extremely narrow notch that can be used for highly sensitivity refractive index measurement. The etched πFBG demonstrated here has a diameter of ~9.3 μm and a length of only 7 mm, leading to a refractive index responsivity of 2.9 nm/RIU (RIU: refractive index unit) at an ambient refractive index of 1.318. The reflection spectrum of the etched πFBG features an extremely narrow notch with a linewidth of only 2.1 pm in water centered at ~1,550 nm, corresponding to a Q-factor of 7.4 × 10(5), which allows for potentially significantly improved sensitivity over refractometers based on regular fiber Bragg gratings.

  10. Fiber-Optic Refractometer Based on an Etched High-Q π-Phase-Shifted Fiber-Bragg-Grating

    Directory of Open Access Journals (Sweden)

    Ming Han

    2013-07-01

    Full Text Available We present a compact and highly-sensitive fiber-optic refractometer based on a high-Q p-phase-shifted fiber-Bragg-grating (pFBG that is chemically etched to the core of the fiber. Due to the p phase-shift, a strong pFBG forms a high-Q optical resonator and the reflection spectrum features an extremely narrow notch that can be used for highly sensitivity refractive index measurement. The etched pFBG demonstrated here has a diameter of ~9.3 μm and a length of only 7 mm, leading to a refractive index responsivity of 2.9 nm/RIU (RIU: refractive index unit at an ambient refractive index of 1.318. The reflection spectrum of the etched pFBG features an extremely narrow notch with a linewidth of only 2.1 pm in water centered at ~1,550 nm, corresponding to a Q-factor of 7.4 ´ 105, which allows for potentially significantly improved sensitivity over refractometers based on regular fiber Bragg gratings.

  11. Ultra-sensitive bio-sensor based on GMR in self-suspended-membrane-type germanium grating

    International Nuclear Information System (INIS)

    Ma, Jianyong; Zhang, Dawei

    2012-01-01

    In this paper, an ultra-sensitive bio-sensor based on the GMR effect in self-suspended-membrane-type gratings (SSGs) is proposed using multilayer plane waveguide theory. It is demonstrated from our calculations that the sensitivity of our bio-sensor is near the theoretical limit compared with a conventional GMR sensor. Based on the normalized eigenfunction of a single-layer homogeneous grating, the resonance curves with respect to different refractive indices of surrounding media are calculated, which confirm the estimated sensitivity. In addition, we design a highly sensitive bio-sensor in the near- and mid-IR wavelength region for liquid and gas detection respectively, the sensor can deliver a resolution over 1 × 10 −5 in the near-IR region in a large refractive index (1.3–1.7) range and provide better than 1 × 10 −6 in the mid-IR region, which is enough for various bio-material detections. Therefore, the bio-sensor we proposed is one or two orders more sensitive than conventional GMR sensors. (paper)

  12. Value-based purchasing of medical devices.

    Science.gov (United States)

    Obremskey, William T; Dail, Teresa; Jahangir, A Alex

    2012-04-01

    Health care in the United States is known for its continued innovation and production of new devices and techniques. While the intention of these devices is to improve the delivery and outcome of patient care, they do not always achieve this goal. As new technologies enter the market, hospitals and physicians must determine which of these new devices to incorporate into practice, and it is important these devices bring value to patient care. We provide a model of a physician-engaged process to decrease cost and increase review of physician preference items. We describe the challenges, implementation, and outcomes of cost reduction and product stabilization of a value-based process for purchasing medical devices at a major academic medical center. We implemented a physician-driven committee that standardized and utilized evidence-based, clinically sound, and financially responsible methods for introducing or consolidating new supplies, devices, and technology for patient care. This committee worked with institutional finance and administrative leaders to accomplish its goals. Utilizing this physician-driven committee, we provided access to new products, standardized some products, decreased costs of physician preference items 11% to 26% across service lines, and achieved savings of greater than $8 million per year. The implementation of a facility-based technology assessment committee that critically evaluates new technology can decrease hospital costs on implants and standardize some product lines.

  13. Laser confocal measurement system for curvature radius of lenses based on grating ruler

    Science.gov (United States)

    Tian, Jiwei; Wang, Yun; Zhou, Nan; Zhao, Weirui; Zhao, Weiqian

    2015-02-01

    In the modern optical measurement field, the radius of curvature (ROC) is one of the fundamental parameters of optical lens. Its measurement accuracy directly affects the other optical parameters, such as focal length, aberration and so on, which significantly affect the overall performance of the optical system. To meet the demand of measurement instruments for radius of curvature (ROC) with high accuracy in the market, we develop a laser confocal radius measurement system with grating ruler. The system uses the peak point of the confocal intensity curve to precisely identify the cat-eye and confocal positions and then measure the distance between these two positions by using the grating ruler, thereby achieving the high-precision measurement for the ROC. The system has advantages of high focusing sensitivity and anti-environment disturbance ability. And the preliminary theoretical analysis and experiments show that the measuring repeatability can be up to 0.8 um, which can provide an effective way for the accurate measurement of ROC.

  14. Torsion based universal MEMS logic device

    KAUST Repository

    Ilyas, Saad; Carreno, Armando Arpys Arevalo; Bayes, Ernesto; Foulds, Ian G.; Younis, Mohammad I.

    2015-01-01

    In this work we demonstrate torsion based complementary MEMS logic device, which is capable, of performing INVERTER, AND, NAND, NOR, and OR gates using one physical structure within an operating range of 0-10 volts. It can also perform XOR and XNOR with one access inverter using the same structure with different electrical interconnects. The paper presents modeling, fabrication and experimental calculations of various performance features of the device including lifetime, power consumption and resonance frequency. The fabricated device is 535 μm by 150 μm with a gap of 1.92 μm and a resonant frequency of 6.51 kHz. The device is capable of performing the switching operation with a frequency of 1 kHz.

  15. Torsion based universal MEMS logic device

    KAUST Repository

    Ilyas, Saad

    2015-10-28

    In this work we demonstrate torsion based complementary MEMS logic device, which is capable, of performing INVERTER, AND, NAND, NOR, and OR gates using one physical structure within an operating range of 0-10 volts. It can also perform XOR and XNOR with one access inverter using the same structure with different electrical interconnects. The paper presents modeling, fabrication and experimental calculations of various performance features of the device including lifetime, power consumption and resonance frequency. The fabricated device is 535 μm by 150 μm with a gap of 1.92 μm and a resonant frequency of 6.51 kHz. The device is capable of performing the switching operation with a frequency of 1 kHz.

  16. Polarization-Insensitive Tunable Optical Filters based on Liquid Crystal Polarization Gratings

    Science.gov (United States)

    Nicolescu, Elena

    Tunable optical filters are widely used for a variety of applications including spectroscopy, optical communication networks, remote sensing, and biomedical imaging and diagnostics. All of these application areas can greatly benefit from improvements in the key characteristics of the tunable optical filters embedded in them. Some of these key parameters include peak transmittance, bandwidth, tuning range, and transition width. In recent years research efforts have also focused on miniaturizing tunable optical filters into physically small packages for compact portable spectroscopy and hyperspectral imaging applications such as real-time medical diagnostics and defense applications. However, it is important that miniaturization not have a detrimental effect on filter performance. The overarching theme of this dissertation is to explore novel configurations of Polarization Gratings (PGs) as simple, low-cost, polarization-insensitive alternatives to conventional optical filtering technologies for applications including hyperspectral imaging and telecommunications. We approach this goal from several directions with a combination of theory and experimental demonstration leading to, in our opinion, a significant contribution to the field. We present three classes of tunable optical filters, the first of which is an angle-filtering scheme where the stop-band wavelengths are redirected off axis and the passband is transmitted on-axis. This is achieved using a stacked configuration of polarization gratings of various thicknesses. To improve this class of filter, we also introduce a novel optical element, the Bilayer Polarization Grating, exhibiting unique optical properties and demonstrating complex anchoring conditions with high quality. The second class of optical filter is analogous to a Lyot filter, utilizing stacks of static or tunable waveplates sandwiched with polarizing elements. However, we introduce a new configuration using PGs and static waveplates to replace

  17. MEMS Bragg grating force sensor

    DEFF Research Database (Denmark)

    Reck, Kasper; Thomsen, Erik Vilain; Hansen, Ole

    2011-01-01

    We present modeling, design, fabrication and characterization of a new type of all-optical frequency modulated MEMS force sensor based on a mechanically amplified double clamped waveguide beam structure with integrated Bragg grating. The sensor is ideally suited for force measurements in harsh...... environments and for remote and distributed sensing and has a measured sensitivity of -14 nm/N, which is several times higher than what is obtained in conventional fiber Bragg grating force sensors. © 2011 Optical Society of America....

  18. A Fiber Bragg grating based tilt sensor suitable for constant temperature room

    International Nuclear Information System (INIS)

    Tang, Guoyu; Wei, Jue; Zhou, Wei; Wu, Mingyu; Yang, Meichao; Xie, Ruijun; Xu, Xiaofeng

    2015-01-01

    Constant-temperature rooms have been widely used in industrial production, quality testing, and research laboratories. This paper proposes a high-precision tilt sensor suitable for a constant- temperature room, which has achieved a wide-range power change while the fiber Bragg grating (FBG) reflection peak wavelength shifted very little, thereby demonstrating a novel method for obtaining a high-precision tilt sensor. This paper also studies the effect of the reflection peak on measurement precision. The proposed sensor can distinguish the direction of tilt with an excellent sensitivity of 403 dBm/° and a highest achievable resolution of 2.481 × 10 −5 ° (that is, 0.08% of the measuring range). (paper)

  19. Sensing Characteristics of Side-Hole Fiber-Based Long-Period Grating

    Directory of Open Access Journals (Sweden)

    Yi Xin

    2013-01-01

    Full Text Available Long-period gratings (LPGs have been fabricated in a side-hole fiber (SHF by using a pulsed CO2 laser. Sensing characteristics of this SHF-LPG to temperature surrounding refractive index and bend have been investigated. Experimental results show that resonant wavelength of the SHF-LPG has a blue shift with temperature with sensitivity of −0.11 nm/°C, a blue shift with increasing sensitivity with surrounding refractive index ranging from 1.335 to 1.44 (the maximum sensitivity is achieved when the surrounding refractive index reaches the effective index of the fiber cladding, and a red shift with bend-direction-dependent sensitivity up to 9.36 nm/m−1.

  20. Simple and polarization-independent Dammann grating based on all-dielectric nanorod array

    Science.gov (United States)

    Yang, Sen; Li, Chuang; Liu, Tongming; Da, Haixia; Feng, Rui; Tang, Donghua; Sun, Fangkui; Ding, Weiqiang

    2017-09-01

    In this work, we comprehensively investigate a Dammann grating (DG) that can generate a 5 × 5 diffraction spot array with an extending angle of 18^\\circ × 18^\\circ around the fiber communication wavelength of 1550 {nm}. The DG is a simple metasurface structure composed of a silicon cuboid nanorod array on a silica substrate, and only two different sizes of nanorods with square cross-sections and uniform spatial orientations are used. These simple units and this configuration are favorable in practice, and the C4 symmetry cross section of the nanorods ensures the polarization-independent operation of the DG. The phase modulation of the nanorods is achieved by the guiding mode propagating in them rather than electric or magnetic Mie-type resonance, which makes the design of the cuboid nanorods easy and robust. More importantly, the two-dimensional nanorod array is generated from a one-dimensional array, which further decreases the design and fabrication complexity.

  1. Effective refractive index modulation based optical fiber humidity sensor employing etched fiber Bragg grating

    Science.gov (United States)

    Mundendhar, Pathi; Khijwania, Sunil K.

    2015-09-01

    Relative humidity (RH) sensor employing etched fiber Bragg grating (FBG) is reported where RH variations are captured using effective-index-modulation, rather than traditional strain-modulation. Additionly, linear sensor response over wide dynamic range with optimum characteristics is focused. Comprehensive experimental investigation is carried out for the sensor that comprises uniformly etched cladding in the FBG region. Obtained results are observed to be in agreement with the theoretical analysis. Sensor response is observed to be linear over dynamic range 3-94%RH with ~ 0.082 pm/%RH sensitivity, ~0.6%RH resolution, ~ +/-2.5%RH accuracy, ~ +/-0.2 pm average discrepancy and ~ 0.2s response time during humidification/desiccation.

  2. Simultaneous measurement of strain, temperature and refractive index based on multimode interference, fiber tapering and fiber Bragg gratings

    International Nuclear Information System (INIS)

    Oliveira, Ricardo; Osório, Jonas H; Aristilde, Stenio; Cordeiro, Cristiano M B; Bilro, Lúcia; Nogueira, Rogerio N

    2016-01-01

    We report the development of an optical fiber sensor capable of simultaneously measuring strain, temperature and refractive index. The sensor is based on the combination of two fiber Bragg gratings written in a standard single-mode fiber, one in an untapered region and another in a tapered region, spliced to a no-core fiber. The possibility of simultaneously measuring three parameters relies on the different sensitivity responses of each part of the sensor. The results have shown the possibility of measuring three parameters simultaneously with a resolution of 3.77 με , 1.36 °C and 5  ×  10 −4 , respectively for strain, temperature and refractive index. On top of the multiparameter ability, the simple production and combination of all the parts involved on this optical-fiber-based sensor is an attractive feature for several sensing applications. (paper)

  3. Analytical investigation of response of birefringent fiber Bragg grating sensors in distributed monitoring system based on optical frequency domain reflectometry

    Science.gov (United States)

    Wada, D.; Murayama, H.

    2014-01-01

    When Fiber Bragg gratings (FBGs) are used as strain sensors, both longitudinal and lateral strain can be applied uniformly or non-uniformly over the length of the FBGs. In order for the demodulation of such FBG signal, this paper investigates the response of birefringent FBGs which are monitored by distributed measurement system based on optical frequency domain reflectometry. A numerical model of the distributed measurement system is built based on piece-wise uniform approach, which considers polarization states of propagating lights. The numerical model simulates analytical response of birefringent FBGs especially when birefringence induces power fluctuations in the distributed spectra, which can be noise or new opportunity for sensitive monitoring of birefringence. Simulation results show the relationships between the power fluctuations and the polarization states of the propagating lights. Consequently, appropriate methods of polarization control for sensitive distributed birefringent FBG monitoring are discussed.

  4. Refractive index and temperature sensors based on no-core fiber cascaded with long period fiber grating

    Science.gov (United States)

    Zhang, Jianming; Pu, Shengli; Rao, Jie; Yao, Tianjun

    2018-05-01

    A kind of compact fibre-optic sensor based on no-core fibre (NCF) cascaded with a strong coupling long-period fibre grating (LPFG) is proposed and experimentally demonstrated. The sensing mechanism is based on the Mach-Zehnder-like interference between the core fundamental mode and cladding mode of the fibre structure. The NCF and LPFG are used as the mode exciter and combiner, respectively. Due to the particular properties of the strong coupling LPFG, the measurements of refractive index (RI) and temperature with high sensitivity are realized by monitoring the transmission spectrum with intensity and wavelength interrogation techniques, respectively. The achieved RI sensitivity reaches -580.269 dB/RIU in the range of 1.436-1.454 and the temperature sensitivity reaches 27.2 pm/°C.

  5. Improvement of insertion loss and quality factor of flexural plate-wave-based alpha-fetoprotein biosensor using groove-type reflective grating structures

    Science.gov (United States)

    Lin, Chang-Yu; Huang, I.-Yu; Lan, Je-Wei

    2013-01-01

    Conventional flexural plate-wave (FPW) transducers have limited applications in biomedical sensing due to their disadvantages such as high insertion loss and low quality factor. To overcome these shortcomings, we propose a FPW transducer on a low phase velocity insulator membrane (5-μm-thick SiO2) with a novel groove-type reflective grating structure design. Additionally, a cystamine self-assembly monolayer and a glutaraldehyde cross-linking layer are implemented on the backside of the FPW device to immobilize alpha-fetoprotein (AFP) antibody. A FPW-based AFP biosensor with low detection limit (5 ng/mL) can be achieved and used to measure the extreme low concentration of AFP antigen in human serum for early detection of hepatocellular carcinoma. The proposed FPW-based AFP biosensor also demonstrates a very high quality factor (206), low insertion loss (-40.854 dB), low operating frequency (6.388 MHz), and high sensing linearity (90.7%).

  6. Waveguide silicon nitride grating coupler

    Science.gov (United States)

    Litvik, Jan; Dolnak, Ivan; Dado, Milan

    2016-12-01

    Grating couplers are one of the most used elements for coupling of light between optical fibers and photonic integrated components. Silicon-on-insulator platform provides strong confinement of light and allows high integration. In this work, using simulations we have designed a broadband silicon nitride surface grating coupler. The Fourier-eigenmode expansion and finite difference time domain methods are utilized in design optimization of grating coupler structure. The fully, single etch step grating coupler is based on a standard silicon-on-insulator wafer with 0.55 μm waveguide Si3N4 layer. The optimized structure at 1550 nm wavelength yields a peak coupling efficiency -2.6635 dB (54.16%) with a 1-dB bandwidth up to 80 nm. It is promising way for low-cost fabrication using complementary metal-oxide- semiconductor fabrication process.

  7. Heterodyne grating interferometer based on a quasi-common-optical-path configuration for a two-degrees-of-freedom straightness measurement

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ju-Yi; Hsieh, Hung-Lin; Lerondel, Gilles; Deturche, Regis; Lu, Mini-Pei; Chen, Jyh-Chen

    2011-03-20

    We present a heterodyne grating interferometer based on a quasi-common-optical-path (QCOP) design for a two-degrees-of-freedom (DOF) straightness measurement. Two half-wave plates are utilized to rotate the polarizations of two orthogonally polarized beams. The grating movement can be calculated by measuring the phase difference variation in each axis. The experimental results demonstrate that our method has the ability to measure two-DOF straightness and still maintain high system stability. The proposed and demonstrated method, which relies on heterodyne interferometric phase measurement combined with the QCOP configuration, has the advantages of high measurement resolution, relatively straightforward operation, and high system stability.

  8. Large-area full field x-ray differential phase-contrast imaging using 2D tiled gratings

    Science.gov (United States)

    Schröter, Tobias J.; Koch, Frieder J.; Kunka, Danays; Meyer, Pascal; Tietze, Sabrina; Engelhardt, Sabine; Zuber, Marcus; Baumbach, Tilo; Willer, Konstantin; Birnbacher, Lorenz; Prade, Friedrich; Pfeiffer, Franz; Reichert, Klaus-Martin; Hofmann, Andreas; Mohr, Jürgen

    2017-06-01

    Grating-based x-ray differential phase-contrast imaging (DPCI) is capable of acquiring information based on phase-shift and dark-field signal, in addition to conventional x-ray absorption-contrast. Thus DPCI gives an advantage to investigate composite materials with component wise similar absorption properties like soft tissues. Due to technological challenges in fabricating high quality gratings over a large extent, the field of view (FoV) of the imaging systems is limited to a grating area of a couple of square centimeters. For many imaging applications (e.g. in medicine), however, a FoV that ranges over several ten centimeters is needed. In this manuscript we propose to create large area gratings of theoretically any extent by assembling a number of individual grating tiles. We discuss the precision needed for alignment of each microstructure tile in order to reduce image artifacts and to preserve minimum 90% of the sensitivity obtainable with a monolithic grating. To achieve a reliable high precision alignment a semiautomatic assembly system consisting of a laser autocollimator, a digital microscope and a force sensor together with positioning devices was built. The setup was used to tile a first four times four analyzer grating with a size of 200 mm  ×  200 mm together with a two times two phase grating. First imaging results prove the applicability and quality of the tiling concept.

  9. Grating-based X-ray phase-contrast tomography of atherosclerotic plaque at high photon energies

    Energy Technology Data Exchange (ETDEWEB)

    Hetterich, Holger; Fill, Sandra [Klinikum der Ludwig-Maximilians-Univ., Muenchen (Germany). Inst. fuer Klinische Radiologie; Herzen, Julia [Technische Univ. Muenchen, Garching (Germany). Physik-Dept. und Inst. fuer Medizintechnik; Helmholtz-Zentrum Geesthacht, Geesthacht (Germany). Zentrum fuer Materialforschung] [and others

    2013-10-01

    Background: Tissue characterization of atherosclerosis by absorption-based imaging methods is limited due to low soft-tissue contrast. Grating-based phase-contrast computed tomography (PC-CT) may become an alternative for plaque assessment if the phase signal can be retrieved at clinically applicable photon energies. The aims of this feasibility study were (i) to characterize arterial vessels at low and high photon energies, (ii) to extract qualitative features and (iii) quantitative phase-contrast Hounsfield units (HU-phase) of plaque components at 53 keV using histopathology as gold standard. Materials and methods: Five human carotid artery specimens underwent grating-based PC-CT using synchrotron radiation of either 23 keV or 53 keV and histological work-up. Specimens without advanced atherosclerosis were used to extract signal criteria of vessel layers. Diseased specimens were screened for important plaque components including fibrous tissue (FT), lipid (LIP), necrotic core (NEC), intraplaque hemorrhage (IPH), inflammatory cell infiltration (INF) and calcifications (CA). Qualitative features as well as quantitative HU-phase were analyzed. Results: Thirty-three regions in 6 corresponding PC-CT scans and histology sections were identified. Healthy samples had the same signal characteristics at 23 keV and 53 keV with bright tunica intima and adventitia and dark media. Plaque components showed differences in signal intensity and texture at 53 keV. Quantitative analysis demonstrated the highest HU-phase of soft plaque in dense FT. Less organized LIP, NEC and INF were associated with lower HU-phase values. The highest HU-phase were measured in CA. Conclusion: PC-CT of atherosclerosis is feasible at high, clinically relevant photon energies and provides detailed information about plaque structure including features of high risk vulnerable plaques. (orig.)

  10. Gravitational Grating

    Science.gov (United States)

    Rahvar, Sohrab

    2018-05-01

    In this work, we study the interaction of the electromagnetic wave (EW) from a distant quasar with the gravitational wave (GW) sourced by the binary stars. While in the regime of geometric optics, the light bending due to this interaction is negligible, we show that the phase shifting on the wavefront of an EW can produce the diffraction pattern on the observer plane. The diffraction of the light (with the wavelength of λe) by the gravitational wave playing the role of gravitational grating (with the wavelength of λg) has the diffraction angle of Δβ ˜ λe/λg. The relative motion of the observer, the source of gravitational wave and the quasar results in a relative motion of the observer through the interference pattern on the observer plane. The consequence of this fringe crossing is the modulation in the light curve of a quasar with the period of few hours in the microwave wavelength. The optical depth for the observation of this phenomenon for a Quasar with the multiple images strongly lensed by a galaxy where the light trajectory of some of the images crosses the lensing galaxy is τ ≃ 0.2. By shifting the time-delay of the light curves of the multiple images in a strong lensed quasar and removing the intrinsic variations of a quasar, our desired signals, as a new method for detection of GWs can be detected.

  11. Cellphone-based devices for bioanalytical sciences

    Science.gov (United States)

    Vashist, Sandeep Kumar; Mudanyali, Onur; Schneider, E.Marion; Zengerle, Roland; Ozcan, Aydogan

    2014-01-01

    During the last decade, there has been a rapidly growing trend toward the use of cellphone-based devices (CBDs) in bioanalytical sciences. For example, they have been used for digital microscopy, cytometry, read-out of immunoassays and lateral flow tests, electrochemical and surface plasmon resonance based bio-sensing, colorimetric detection and healthcare monitoring, among others. Cellphone can be considered as one of the most prospective devices for the development of next-generation point-of-care (POC) diagnostics platforms, enabling mobile healthcare delivery and personalized medicine. With more than 6.5 billion cellphone subscribers worldwide and approximately 1.6 billion new devices being sold each year, cellphone technology is also creating new business and research opportunities. Many cellphone-based devices, such as those targeted for diabetic management, weight management, monitoring of blood pressure and pulse rate, have already become commercially-available in recent years. In addition to such monitoring platforms, several other CBDs are also being introduced, targeting e.g., microscopic imaging and sensing applications for medical diagnostics using novel computational algorithms and components already embedded on cellphones. This manuscript aims to review these recent developments in CBDs for bioanalytical sciences along with some of the challenges involved and the future opportunities. PMID:24287630

  12. Tunable and reconfigurable microwave filter by use of a Bragg-grating-based acousto-optic superlattice modulator.

    Science.gov (United States)

    Delgado-Pinar, M; Mora, J; Díez, A; Andrés, M V; Ortega, B; Capmany, J

    2005-01-01

    We present an all-optical novel configuration for implementing multitap transversal filters by use of a broadband source sliced by fiber Bragg grating arrays generated by propagating an acoustic wave along a strong uniform fiber Bragg grating. The tunability and reconfigurability of the microwave filter are demonstrated.

  13. Noise analysis of grating-based x-ray differential phase-contrast imaging with angular signal radiography

    International Nuclear Information System (INIS)

    Faiz, Wali; Gao Kun; Wu Zhao; Wei Chen-Xi; Zan Gui-Bin; Tian Yang-Chao; Bao Yuan; Zhu Pei-Ping

    2017-01-01

    X-ray phase-contrast imaging is one of the novel techniques, and has potential to enhance image quality and provide the details of inner structures nondestructively. In this work, we investigate quantitatively signal-to-noise ratio (SNR) of grating-based x-ray phase contrast imaging (GBPCI) system by employing angular signal radiography (ASR). Moreover, photon statistics and mechanical error that is a major source of noise are investigated in detail. Results show the dependence of SNR on the system parameters and the effects on the extracted absorption, refraction and scattering images. Our conclusions can be used to optimize the system design for upcoming practical applications in the areas such as material science and biomedical imaging. (paper)

  14. Study of distributed fiber-optic laser-ultrasound generation based on ghost-mode of tilted fiber Bragg gratings

    Science.gov (United States)

    Tian, Jiajun; Zhang, Qi; Han, Ming

    2013-05-01

    Fiber-optic ultrasonic transducers are an important component of an active ultrasonic testing system for structural health monitoring. Fiber-optic transducers have several advantages such as small size, light weight, and immunity to electromagnetic interference that make them much more attractive than the current available piezoelectric transducers, especially as embedded and permanent transducers in active ultrasonic testing for structural health monitoring. In this paper, a distributed fiber-optic laser-ultrasound generation based on the ghost-mode of tilted fiber Bragg gratings is studied. The influences of the laser power and laser pulse duration on the laser-ultrasound generation are investigated. The results of this paper are helpful to understand the working principle of this laser-ultrasound method and improve the ultrasonic generation efficiency.

  15. Control over the resonance wavelength of fibre Bragg gratings using resistive coatings based on single-wall carbon nanotubes

    Science.gov (United States)

    Gladush, Yu. G.; Medvedkov, O. I.; Vasil'ev, S. A.; Kopylova, D. S.; Yakovlev, V. Ya.; Nasibulin, A. G.

    2016-10-01

    We demonstrate that a thin resistive coating based on single-wall carbon nanotubes applied to the lateral surface of an optical fibre allows it to be uniformly heated up to a temperature of ∼ 400 \\circ{\\text{C}} without damage to the coating. Using a fibre Bragg grating (FBG) as an example, we assess the efficiency of resonance wavelength thermal tuning and examine frequency characteristics that can be achieved using such coating. In particular, we show that the resonance wavelength of the FBG can be tuned over 3.2 {\\text{nm}} with an efficiency of 8.7 {\\text{nm}} {\\text{W}}-1 and time constant of ∼ 0.4 {\\text{s}}.

  16. 10th order laterally coupled GaN-based DFB laser diodes with V-shaped surface gratings

    Science.gov (United States)

    Kang, J. H.; Wenzel, H.; Hoffmann, V.; Freier, E.; Sulmoni, L.; Unger, R.-S.; Einfeldt, S.; Wernicke, T.; Kneissl, M.

    2018-02-01

    Single longitudinal mode operation of laterally coupled distributed feedback (DFB) laser diodes (LDs) based on GaN containing 10th-order surface Bragg gratings with V-shaped grooves is demonstrated using i-line stepper lithography and inductively coupled plasma etching. A threshold current of 82 mA, a slope efficiency of 1.7 W/A, a single peak emission at 404.5 nm with a full width at half maximum of 0.04 nm and a side mode suppression ratio of > 23 dB at an output power of about 46 mW were achieved under pulsed operation. The shift of the lasing wavelength of DFB LDs with temperature was around three times smaller than that of conventional ridge waveguide LDs.

  17. Development and Testing of an Integrated Rotating Dynamometer Based on Fiber Bragg Grating for Four-Component Cutting Force Measurement.

    Science.gov (United States)

    Liu, Mingyao; Bing, Junjun; Xiao, Li; Yun, Kang; Wan, Liang

    2018-04-18

    Cutting force measurement is of great importance in machining processes. Hence, various methods of measuring the cutting force have been proposed by many researchers. In this work, a novel integrated rotating dynamometer based on fiber Bragg grating (FBG) was designed, constructed, and tested to measure four-component cutting force. The dynamometer consists of FBGs that are pasted on the newly designed elastic structure which is then mounted on the rotating spindle. The elastic structure is designed as two mutual-perpendicular semi-octagonal rings. The signals of the FBGs are transmitted to FBG interrogator via fiber optic rotary joints and optical fiber, and the wavelength values are displayed on a computer. In order to determine the static and dynamic characteristics, many tests have been done. The results show that it is suitable for measuring cutting force.

  18. System and technique for characterizing fluids using ultrasonic diffraction grating spectroscopy

    Science.gov (United States)

    Greenwood, Margaret S [Richland, WA

    2008-07-08

    A system for determining property of multiphase fluids based on ultrasonic diffraction grating spectroscopy includes a diffraction grating on a solid in contact with the fluid. An interrogation device delivers ultrasound through the solid and a captures a reflection spectrum from the diffraction grating. The reflection spectrum exhibits peaks whose relative size depends on the properties of the various phases of the multiphase fluid. For example, for particles in a liquid, the peaks exhibit dependence on the particle size and the particle volume fraction. Where the exact relationship is know know a priori, data from different peaks of the same reflection spectrum or data from the peaks of different spectra obtained from different diffraction gratings can be used to resolve the size and volume fraction.

  19. Carbon Based Transistors and Nanoelectronic Devices

    Science.gov (United States)

    Rouhi, Nima

    Carbon based materials (carbon nanotube and graphene) has been extensively researched during the past decade as one of the promising materials to be used in high performance device technology. In long term it is thought that they may replace digital and/or analog electronic devices, due to their size, near-ballistic transport, and high stability. However, a more realistic point of insertion into market may be the printed nanoelectronic circuits and sensors. These applications include printed circuits for flexible electronics and displays, large-scale bendable electrical contacts, bio-membranes and bio sensors, RFID tags, etc. In order to obtain high performance thin film transistors (as the basic building block of electronic circuits) one should be able to manufacture dense arrays of all semiconducting nanotubes. Besides, graphene synthesize and transfer technology is in its infancy and there is plenty of room to improve the current techniques. To realize the performance of nanotube and graphene films in such systems, we need to economically fabricate large-scale devices based on these materials. Following that the performance control over such devices should also be considered for future design variations for broad range of applications. Here we have first investigated carbon nanotube ink as the base material for our devices. The primary ink used consisted of both metallic and semiconducting nanotubes which resulted in networks suitable for moderate-resistivity electrical connections (such as interconnects) and rfmatching circuits. Next, purified all-semiconducting nanotube ink was used to fabricate waferscale, high performance (high mobility, and high on/off ratio) thin film transistors for printed electronic applications. The parameters affecting device performance were studied in detail to establish a roadmap for the future of purified nanotube ink printed thin film transistors. The trade of between mobility and on/off ratio of such devices was studied and the

  20. Fiber Bragg Grating-Based Performance Monitoring of Piles Fiber in a Geotechnical Centrifugal Model Test

    Directory of Open Access Journals (Sweden)

    Xiaolin Weng

    2014-01-01

    Full Text Available In centrifugal tests, conventional sensors can hardly capture the performance of reinforcement in small-scale models. However, recent advances in fiber optic sensing technologies enable the accurate and reliable monitoring of strain and temperature in laboratory geotechnical tests. This paper outlines a centrifugal model test, performed using a 60 g ton geocentrifuge, to investigate the performance of pipe piles used to reinforce the loess foundation below a widened embankment. Prior to the test, quasidistributed fiber Bragg grating (FBG strain sensors were attached to the surface of the pipe piles to measure the lateral friction resistance in real time. Via the centrifuge actuator, the driving of pipe piles was simulated. During testing, the variations of skin friction distribution along the pipe piles were measured automatically using an optical fiber interrogator. This paper represents the presentation and detailed analysis of monitoring results. Herein, we verify the reliability of the fiber optic sensors in monitoring the model piles without affecting the integrity of the centrifugal model. This paper, furthermore, shows that lateral friction resistance developed in stages with the pipe piles being pressed in and that this sometimes may become negative.

  1. Distributed Weak Fiber Bragg Grating Vibration Sensing System Based on 3 × 3 Fiber Coupler

    Science.gov (United States)

    Li, Wei; Zhang, Jian

    2018-06-01

    A novel distributed weak fiber Bragg gratings (FBGs) vibration sensing system has been designed to overcome the disadvantages of the conventional methods for optical fiber sensing networking, which are: low signal intensity in the usually adopted time-division multiplexing (TDM) technology, insufficient quantity of multiplexed FBGs in the wavelength-division multiplexing (WDM) technology, and that the mixed WDM/TDM technology measures only the physical parameters of the FBG locations but cannot perform distributed measurement over the whole optical fiber. This novel system determines vibration events in the optical fiber line according to the intensity variation of the interference signals between the adjacent weak FBG reflected signals and locates the vibration points accurately using the TDM technology. It has been proven by tests that this system performs vibration signal detection and demodulation in a way more convenient than the conventional methods for the optical fiber sensing system. It also measures over the whole optical fiber, therefore, distributed measurement is fulfilled, and the system locating accuracy is up to 20 m, capable of detecting any signals of whose drive signals lower limit voltage is 0.2 V while the frequency range is 3 Hz‒1 000 Hz. The system has the great practical significance and application value for perimeter surveillance systems.

  2. Grating-coupled surface plasmon resonance gas sensing based on titania anatase nanoporous films

    Science.gov (United States)

    Gazzola, Enrico; Cittadini, Michela; Brigo, Laura; Brusatin, Giovanna; Guglielmi, Massimo; Romanato, Filippo; Martucci, Alessandro

    2015-08-01

    Nanoporous TiO2 anatase film has been investigated as sensitive layer in Surface Plasmon Resonance sensors for the detection of hydrogen and Volatile Organic Compounds, specifically methanol and isopropanol. The sensors consist of a TiO2 nanoporous matrix deposited above a metallic plasmonic grating, which can support propagating Surface Plasmon Polaritons. The spectral position of the plasmonic resonance dip in the reflectance spectra was monitored and correlated to the interaction with the target gases. Reversible blue-shifts of the resonance frequency, up to more than 2 THz, were recorded in response to the exposure to 10000 ppm of H2 in N2 at 300°C. This shift cannot be explained by the mere refractive index variation due to the target gas filling the pores, that is negligible. Reversible red-shifts were instead recorded in response to the exposure to 3000 ppm of methanol or isopropanol at room temperature, of magnitudes up to 14 THz and 9 THz, respectively. In contrast, if the only sensing mechanism was the mere pores filling, the shifts should have been larger during the isopropanol detection. We therefore suggest that other mechanisms intervene in the analyte/matrix interaction, capable to produce an injection of electrons into the sensitive matrix, which in turn induces a decrease of the refractive index.

  3. Elimination of drift in a fiber-Bragg-grating-based multiplexed Michelson interferometer measurement system.

    Science.gov (United States)

    Ren, Junyu; Xie, Fang; Chen, Zhimin

    2010-02-01

    Random phase drift in single-mode optical fiber interferometers used with measurement systems, which is resulted from various types of environmental disturbances, should be eliminated in order to obtain high measurement precision. We propose an optical fiber interferometric measurement system which has the function of self-eliminating the random phase drift and is stable and robust enough for real-time precision measurement. By employing the characteristics of fiber Bragg gratings, the system interleaves two fiber Michelson interferometers together that share the common-interferometric-optical path. The signal of one of the interferometers is used to stabilize the system while the signal of the other interferometer is used for measurement. An electronic feedback loop for the stabilizing action is designed. The bandwidth of the feedback loop is 5 kHz, sufficiently wide to eliminate random phase drift resulted from various environmental disturbances. The system is endowed with high stability and therefore suitable for real-time precision measurement. By means of an active phase tracking technique to measure displacement, the linear regression coefficient of the displacement measurement results is 0.9998.

  4. Carbon Nanotube Paper-Based Electroanalytical Devices

    Directory of Open Access Journals (Sweden)

    Youngmi Koo

    2016-04-01

    Full Text Available Here, we report on carbon nanotube paper-based electroanalytical devices. A highly aligned-carbon nanotube (HA-CNT array, grown using chemical vapor deposition (CVD, was processed to form bi-layered paper with an integrated cellulose-based Origami-chip as the electroanalytical device. We used an inverse-ordered fabrication method from a thick carbon nanotube (CNT sheet to a thin CNT sheet. A 200-layered HA-CNT sheet and a 100-layered HA-CNT sheet are explored as a working electrode. The device was fabricated using the following methods: (1 cellulose-based paper was patterned using a wax printer, (2 electrical connection was made using a silver ink-based circuit printer, and (3 three electrodes were stacked on a 2D Origami cell. Electrochemical behavior was evaluated using electrochemical impedance spectroscopy (EIS and cyclic voltammetry (CV. We believe that this platform could attract a great deal of interest for use in various chemical and biomedical applications.

  5. A new deflection solution and application of a fiber Bragg grating-based inclinometer for monitoring internal displacements in slopes

    Science.gov (United States)

    Zheng, Yong; Huang, Da; Shi, Lin

    2018-05-01

    Landslide monitoring is critical for predicting the stability of slopes to ensure the safety of life and property. Considering the potential advantages of fiber Bragg gratings (FBGs), such as immunity to electromagnetic interference, resistance to hostile environments, light weight, and high measurement precision and real time response, a self-designed, FBG-based in situ inclinometer combining a traditional inclinometer and FBG technology was designed to monitor the inner deformation of a slope. In practical landslide monitoring, the inclinometer can be regarded as a cantilever beam with one end fixed. Based on the deflection curve equation of a normal beam and the composite Simpson integral equation, a theoretical deflection equation of the FBG-based inclinometer versus longitudinal strain was established. A FBG-based inclinometer was fabricated and calibrated in the laboratory and a calibration strain sensitivity coefficient was obtained. The results of calibration tests show that the displacements measured by dial indicators are in good agreement with the theoretical displacements calculated using the proposed equation. A series of FBG-based inclinometers were installed into three vertical boreholes located at different points on the profile of an actual reinforced slope. The in situ monitoring results show that the FBG-based inclinometer can effectively capture the real-time internal displacements and potential sliding surface of the slope, proving the validity of the proposed theoretical equation as well the reliability and practicality of the proposed FBG-based inclinometer in engineering applications.

  6. The spectral combination characteristic of grating and the bi-grating diffraction imaging effect

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper reports on a new property of grating, namely spectral combination, and on bi-grating diffraction imaging that is based on spectral combination. The spectral combination characteristic of a grating is the capability of combining multiple light beams of different wavelengths incident from specific angles into a single beam. The bi-grating diffraction imaging is the formation of the image of an object with two gratings: the first grating disperses the multi-color light beams from the object and the second combines the dispersed light beams to form the image. We gave the conditions necessary for obtaining the spectral combination. We also presented the equations that relate the two gratings’ spatial frequencies, diffraction orders and positions necessary for obtaining the bi-grating diffraction imaging.

  7. An Optical Fiber Viscometer Based on Long-Period Fiber Grating Technology and Capillary Tube Mechanism

    Directory of Open Access Journals (Sweden)

    Jian-Neng Wang

    2010-12-01

    Full Text Available This work addresses the development and assessment of a fiber optical viscometer using a simple and low-cost long-period fiber grating (LPFG level sensor and a capillary tube mechanism. Previous studies of optical viscosity sensors were conducted by using different optical sensing methods. The proposed optical viscometer consists of an LPFG sensor, a temperature-controlled chamber, and a cone-shaped reservoir where gravitational force could cause fluid to flow through the capillary tube. We focused on the use of LPFGs as level sensors and the wavelength shifts were not used to quantify the viscosity values of asphalt binders. When the LPFG sensor was immersed in the constant volume (100 mL AC-20 asphalt binder, a wavelength shift was observed and acquired using LabVIEW software and GPIB controller. The time spent between empty and 100 mL was calculated to determine the discharge time. We simultaneously measured the LPFG-induced discharge time and the transmission spectra both in hot air and AC-20 asphalt binder at five different temperatures, 60, 80, 100, 135, and 170 Celsius. An electromechanical rotational viscometer was also used to measure the viscosities, 0.15–213.80 Pa·s, of the same asphalt binder at the above five temperatures. A non-linear regression analysis was performed to convert LPFG-induced discharge time into viscosities. Comparative analysis shows that the LPFG-induced discharge time agreed well with the viscosities obtained from the rotational viscometer.

  8. Fiber Bragg grating-based performance monitoring of a slope model subjected to seepage

    Science.gov (United States)

    Zhu, Hong-Hu; Shi, Bin; Yan, Jun-Fan; Zhang, Jie; Zhang, Cheng-Cheng; Wang, Bao-Jun

    2014-09-01

    In the past few years, fiber optic sensing technologies have played an increasingly important role in the health monitoring of civil infrastructures. These innovative sensing technologies have recently been successfully applied to the performance monitoring of a series of geotechnical structures. Fiber optic sensors have shown many unique advantages in comparison with conventional sensors, including immunity to electrical noise, higher precision and improved durability and embedding capabilities; fiber optic sensors are also smaller in size and lighter in weight. In order to explore the mechanism of seepage-induced slope instability, a small-scale 1 g model test of the soil slope has been performed in the laboratory. During the model’s construction, specially fabricated sensing fibers containing nine fiber Bragg grating (FBG) strain sensors connected in a series were horizontally and vertically embedded into the soil mass. The surcharge load was applied on the slope crest, and the groundwater level inside of the slope was subsequently varied using two water chambers installed besides the slope model. The fiber optic sensing data of the vertical and horizontal strains within the slope model were automatically recorded by an FBG interrogator and a computer during the test. The test results are presented and interpreted in detail. It is found that the gradually accumulated deformation of the slope model subjected to seepage can be accurately captured by the quasi-distributed FBG strain sensors. The test results also demonstrate that the slope stability is significantly affected by ground water seepage, which fits well with the results that were calculated using finite element and limit equilibrium methods. The relationship between the strain measurements and the safety factors is further analyzed, together with a discussion on the residual strains. The performance evaluation of a soil slope using fiber optic strain sensors is proved to be a potentially effective

  9. Fiber Bragg grating-based performance monitoring of a slope model subjected to seepage

    International Nuclear Information System (INIS)

    Zhu, Hong-Hu; Shi, Bin; Yan, Jun-Fan; Zhang, Cheng-Cheng; Wang, Bao-Jun; Zhang, Jie

    2014-01-01

    In the past few years, fiber optic sensing technologies have played an increasingly important role in the health monitoring of civil infrastructures. These innovative sensing technologies have recently been successfully applied to the performance monitoring of a series of geotechnical structures. Fiber optic sensors have shown many unique advantages in comparison with conventional sensors, including immunity to electrical noise, higher precision and improved durability and embedding capabilities; fiber optic sensors are also smaller in size and lighter in weight. In order to explore the mechanism of seepage-induced slope instability, a small-scale 1 g model test of the soil slope has been performed in the laboratory. During the model’s construction, specially fabricated sensing fibers containing nine fiber Bragg grating (FBG) strain sensors connected in a series were horizontally and vertically embedded into the soil mass. The surcharge load was applied on the slope crest, and the groundwater level inside of the slope was subsequently varied using two water chambers installed besides the slope model. The fiber optic sensing data of the vertical and horizontal strains within the slope model were automatically recorded by an FBG interrogator and a computer during the test. The test results are presented and interpreted in detail. It is found that the gradually accumulated deformation of the slope model subjected to seepage can be accurately captured by the quasi-distributed FBG strain sensors. The test results also demonstrate that the slope stability is significantly affected by ground water seepage, which fits well with the results that were calculated using finite element and limit equilibrium methods. The relationship between the strain measurements and the safety factors is further analyzed, together with a discussion on the residual strains. The performance evaluation of a soil slope using fiber optic strain sensors is proved to be a potentially effective

  10. All-optical Hilbert transformer based on a single phase-shifted fiber Bragg grating: design and analysis.

    Science.gov (United States)

    Asghari, Mohammad H; Azaña, José

    2009-02-01

    A simple all-fiber design for implementing an all-optical temporal Hilbert transformer is proposed and numerically demonstrated. We show that an all-optical Hilbert transformer can be implemented using a uniform-period fiber Bragg grating (FBG) with a properly designed amplitude-only grating apodization profile incorporating a single pi phase shift in the middle of the grating length. All-optical Hilbert transformers capable of processing arbitrary optical waveforms with bandwidths up to a few hundreds of gigahertz can be implemented using feasible FBGs.

  11. Topological Material-Based Spin Devices

    Science.gov (United States)

    Zhang, Minhao; Wang, Xuefeng

    Three-dimensional topological insulators have insulating bulk and gapless helical surface states. One of the most fascinating properties of the metallic surface states is the spin-momentum helical locking. The giant current-driven torques on the magnetic layer have been discovered in TI/ferromagnet bilayers originating from the spin-momentum helical locking, enabling the efficient magnetization switching with a low current density. We demonstrated the current-direction dependent on-off state in TIs-based spin valve devices for memory and logic applications. Further, we demonstrated the Bi2Se3 system will go from a topologically nontrivial state to a topologically trivial state when Bi atoms are replaced by lighter In atoms. Here, topologically trivial metal (BixIny)2 Se3 with high mobility also facilitates the realization of its application in multifunctional spintronic devices.

  12. Modeling, simulation, and design of SAW grating filters

    Science.gov (United States)

    Schwelb, Otto; Adler, E. L.; Slaboszewicz, J. K.

    1990-05-01

    A systematic procedure for modeling, simulating, and designing SAW (surface acoustic wave) grating filters, taking losses into account, is described. Grating structures and IDTs (interdigital transducers) coupling to SAWs are defined by cascadable transmission-matrix building blocks. Driving point and transfer characteristics (immittances) of complex architectures consisting of gratings, transducers, and coupling networks are obtained by chain-multiplying building-block matrices. This modular approach to resonator filter analysis and design combines the elements of lossy filter synthesis with the transmission-matrix description of SAW components. A multipole filter design procedure based on a lumped-element-model approximation of one-pole two-port resonator building blocks is given and the range of validity of this model examined. The software for simulating the performance of SAW grating devices based on this matrix approach is described, and its performance, when linked to the design procedure to form a CAD/CAA (computer-aided design and analysis) multiple-filter design package, is illustrated with a resonator filter design example.

  13. Development of a Cloud Computing-Based Pier Type Port Structure Stability Evaluation Platform Using Fiber Bragg Grating Sensors.

    Science.gov (United States)

    Jo, Byung Wan; Jo, Jun Ho; Khan, Rana Muhammad Asad; Kim, Jung Hoon; Lee, Yun Sung

    2018-05-23

    Structure Health Monitoring is a topic of great interest in port structures due to the ageing of structures and the limitations of evaluating structures. This paper presents a cloud computing-based stability evaluation platform for a pier type port structure using Fiber Bragg Grating (FBG) sensors in a system consisting of a FBG strain sensor, FBG displacement gauge, FBG angle meter, gateway, and cloud computing-based web server. The sensors were installed on core components of the structure and measurements were taken to evaluate the structures. The measurement values were transmitted to the web server via the gateway to analyze and visualize them. All data were analyzed and visualized in the web server to evaluate the structure based on the safety evaluation index (SEI). The stability evaluation platform for pier type port structures involves the efficient monitoring of the structures which can be carried out easily anytime and anywhere by converging new technologies such as cloud computing and FBG sensors. In addition, the platform has been successfully implemented at “Maryang Harbor” situated in Maryang-Meyon of Korea to test its durability.

  14. Glow discharge based device for solving mazes

    Energy Technology Data Exchange (ETDEWEB)

    Dubinov, Alexander E., E-mail: dubinov-ae@yandex.ru; Mironenko, Maxim S.; Selemir, Victor D. [Russian Federal Nuclear Center − All-Russian Scientific and Research Institute of Experimental Physics (RFNC-VNIIEF), Sarov, Nizhni Novgorod region 607188 (Russian Federation); Sarov Institute of Physics and Technology (SarFTI) of National Research Nuclear University “MEPhI,” Sarov, Nizhni Novgorod region 607188 (Russian Federation); Maksimov, Artem N.; Pylayev, Nikolay A. [Russian Federal Nuclear Center − All-Russian Scientific and Research Institute of Experimental Physics (RFNC-VNIIEF), Sarov, Nizhni Novgorod region 607188 (Russian Federation)

    2014-09-15

    A glow discharge based device for solving mazes has been designed and tested. The device consists of a gas discharge chamber and maze-transformer of radial-azimuth type. It allows changing of the maze pattern in a short period of time (within several minutes). The device has been tested with low pressure air. Once switched on, a glow discharge has been shown to find the shortest way through the maze from the very first attempt, even if there is a section with potential barrier for electrons on the way. It has been found that ionization waves (striations) can be excited in the maze along the length of the plasma channel. The dependancy of discharge voltage on the length of the optimal path through the maze has been measured. A reduction in discharge voltage with one or two potential barriers present has been found and explained. The dependency of the magnitude of discharge ignition voltage on the length of the optimal path through the maze has been measured. The reduction of the ignition voltage with the presence of one or two potential barriers has been observed and explained.

  15. Distributed-phase OCDMA encoder-decoders based on fiber Bragg gratings

    OpenAIRE

    Zhang, Zhaowei; Tian, C.; Petropoulos, P.; Richardson, D.J.; Ibsen, M.

    2007-01-01

    We propose and demonstrate new optical code-division multiple-access (OCDMA) encoder-decoders having a continuous phase-distribution. With the same spatial refractive index distribution as the reconfigurable optical phase encoder-decoders, they are inherently suitable for the application in reconfigurable OCDMA systems. Furthermore, compared with conventional discrete-phase devices, they also have additional advantages of being more tolerant to input pulse width and, therefore, have the poten...

  16. Development of Smartphone based Optical Device

    Science.gov (United States)

    Jung, Youngkee

    Due to the economy of scale, smartphones are becoming more affordable while their computing powers are increasing dramatically every year. Here we propose a ubiquitous and portable instrument for analyte quantitation by utilizing the characteristics of typical smartphone imaging system and specific design of transducers for different applications. Three testbeds included in this work are: quantitative colorimetric analysis, ultra-low radiant flux detection, and portable spectrometer. As a proof-of-principle for each device, 3-D printed cradle and theoretical simulation with MATLAB have been implemented. First example utilizes the native CMOS camera with their respective RGB channel data and perform an analyte quantitation for typical lateral flow devices (LFD). Histogram analysis method has been employed to detect the analyte concentration and calibration results show good correlation between perceived color change and analyte concentration. The second example shows the possibility of using a conventional CMOS camera for pico Watt level photon flux detection. Since most of consumer grade CMOS cameras cannot detect this level of light intensity and their dark current are relatively higher, a new algorithm called NREA (Noise Reduction by Ensemble Averaging) algorithm was developed to effectively reduce the noise level and increase the SNR (signal to noise ratio). This technique is effective for bioanalytical assays that has lower flux intensity such as fluorescence and luminescence. As a proof-of-principle, we tested the device with Pseudomonas fluorescens M3A and achieved a limit of detection of high 10? CFU/ml. In addition to basic schematic of detection model, another experiment with a silicon photomultiplier (SiPM) has been studied for more sensitive light detectability. Based on both the laser experiment and tw bioluminescent experiments, named Pseudomonas fluorescens M3A and NanoLuc, we found that the miniSM based device has a superior ability than the

  17. A new capacitive long-range displacement nanometer sensor with differential sensing structure based on time-grating

    Science.gov (United States)

    Yu, Zhicheng; Peng, Kai; Liu, Xiaokang; Pu, Hongji; Chen, Ziran

    2018-05-01

    High-precision displacement sensors, which can measure large displacements with nanometer resolution, are key components in many ultra-precision fabrication machines. In this paper, a new capacitive nanometer displacement sensor with differential sensing structure is proposed for long-range linear displacement measurements based on an approach denoted time grating. Analytical models established using electric field coupling theory and an area integral method indicate that common-mode interference will result in a first-harmonic error in the measurement results. To reduce the common-mode interference, the proposed sensor design employs a differential sensing structure, which adopts a second group of induction electrodes spatially separated from the first group of induction electrodes by a half-pitch length. Experimental results based on a prototype sensor demonstrate that the measurement accuracy and the stability of the sensor are substantially improved after adopting the differential sensing structure. Finally, a prototype sensor achieves a measurement accuracy of  ±200 nm over the full 200 mm measurement range of the sensor.

  18. Multiparametric electronic devices based on nuclear tracks

    Energy Technology Data Exchange (ETDEWEB)

    Fink, D. [HMI Berlin, Glienicker Str. 100, 14109 Berlin (Germany)], E-mail: FINK@HMI.DE; Saad, A. [HMI Berlin, Glienicker Str. 100, 14109 Berlin (Germany); Basic Science Department, Faculty of Science, Al Balqa University, Salt (Jordan); Dhamodaran, S. [HMI Berlin, Glienicker Str. 100, 14109 Berlin (Germany); School of Physics, University of Hyderabad, Hyderabad 500 046 (India); Chandra, A. [HMI Berlin, Glienicker Str. 100, 14109 Berlin (Germany); Department of Physics and Astrophysics, University of Delhi, Delhi 110 007 (India); Fahrner, W.R. [Chair of Electronic Devices, Institute of Electrotechnique, Fernuniversitaet, Hagen (Germany); Hoppe, K. [South Westfalia University of Applied Sciences, Hagen (Germany); Chadderton, L.T. [Institute of Advanced Studies, ANU Canberra, GPO Box 4, ACT (Australia)

    2008-08-15

    An overview is given on a family of novel electronic devices consisting of an insulating layer containing conducting or semiconducting nuclear tracks, deposited on a semiconducting substrate, and connected by at least one back and two surface contacts. Conducting and semiconducting latent tracks may emerge directly from swift heavy ion irradiation. Etched tracks in insulators can be filled with adequate materials to make them conducting or semiconducting. For this purpose metallic or semiconducting nanoclusters were deposited. We have denoted termed these devices made with latent tracks as 'tunable electronic anisotropic material on semiconductor' (TEAMS), if based on latent ion tracks, and as 'tunable electronic material in pores in oxide on semiconductor' (TEMPOS), if based on etched tracks. Depending on the band-to-band transition between tracks and substrate and on the ratio of surface to track conductivity, the current/voltage characteristics of TEAMS and TEMPOS structures can be modified in many different ways leading to tunable resistors, capacitors and diodes. Both devices show negative differential resistances. This should enable tunable tunneldiodes. TEAMS or TEMPOS structures can be controlled by various external physical and/or chemical parameters leading to sensors. It is even possible to combine different input currents and/or external parameters according to AND/OR logics. The currents through a clustered layer on a TEMPOS structure can be described by the Barbasi-Albert model of network theory enabling to calculate a 'radius of influence'r{sub ROI} around each surface contact, beyond which neighboring contacts do not influence each other. The radius of influence can be well below 1{mu}m leading to nanometric TEMPOS structures.

  19. Multiparametric electronic devices based on nuclear tracks

    International Nuclear Information System (INIS)

    Fink, D.; Saad, A.; Dhamodaran, S.; Chandra, A.; Fahrner, W.R.; Hoppe, K.; Chadderton, L.T.

    2008-01-01

    An overview is given on a family of novel electronic devices consisting of an insulating layer containing conducting or semiconducting nuclear tracks, deposited on a semiconducting substrate, and connected by at least one back and two surface contacts. Conducting and semiconducting latent tracks may emerge directly from swift heavy ion irradiation. Etched tracks in insulators can be filled with adequate materials to make them conducting or semiconducting. For this purpose metallic or semiconducting nanoclusters were deposited. We have denoted termed these devices made with latent tracks as 'tunable electronic anisotropic material on semiconductor' (TEAMS), if based on latent ion tracks, and as 'tunable electronic material in pores in oxide on semiconductor' (TEMPOS), if based on etched tracks. Depending on the band-to-band transition between tracks and substrate and on the ratio of surface to track conductivity, the current/voltage characteristics of TEAMS and TEMPOS structures can be modified in many different ways leading to tunable resistors, capacitors and diodes. Both devices show negative differential resistances. This should enable tunable tunneldiodes. TEAMS or TEMPOS structures can be controlled by various external physical and/or chemical parameters leading to sensors. It is even possible to combine different input currents and/or external parameters according to AND/OR logics. The currents through a clustered layer on a TEMPOS structure can be described by the Barbasi-Albert model of network theory enabling to calculate a 'radius of influence'r ROI around each surface contact, beyond which neighboring contacts do not influence each other. The radius of influence can be well below 1μm leading to nanometric TEMPOS structures

  20. Fiber Bragg gratings-based sensing for real-time needle tracking during MR-guided brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Borot de Battisti, Maxence, E-mail: M.E.P.Borot@umcutrecht.nl; Maenhout, Metha; Lagendijk, Jan J. W.; Vulpen, Marco van; Moerland, Marinus A. [Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, Utrecht 3584 CX (Netherlands); Denis de Senneville, Baudouin [Imaging Division, University Medical Center Utrecht, Heidelberglaan 100, Utrecht 3584 CX, The Netherlands and IMB, UMR 5251 CNRS/University of Bordeaux, Talence 33400 (France); Hautvast, Gilion; Binnekamp, Dirk [Philips Group Innovation Biomedical Systems, Eindhoven 5656 AE (Netherlands)

    2016-10-15

    Purpose: The development of MR-guided high dose rate (HDR) brachytherapy is under investigation due to the excellent tumor and organs at risk visualization of MRI. However, MR-based localization of needles (including catheters or tubes) has inherently a low update rate and the required image interpretation can be hampered by signal voids arising from blood vessels or calcifications limiting the precision of the needle guidance and reconstruction. In this paper, a new needle tracking prototype is investigated using fiber Bragg gratings (FBG)-based sensing: this prototype involves a MR-compatible stylet composed of three optic fibers with nine sets of embedded FBG sensors each. This stylet can be inserted into brachytherapy needles and allows a fast measurement of the needle deflection. This study aims to assess the potential of FBG-based sensing for real-time needle (including catheter or tube) tracking during MR-guided intervention. Methods: First, the MR compatibility of FBG-based sensing and its accuracy was evaluated. Different known needle deflections were measured using FBG-based sensing during simultaneous MR-imaging. Then, a needle tracking procedure using FBG-based sensing was proposed. This procedure involved a MR-based calibration of the FBG-based system performed prior to the interventional procedure. The needle tracking system was assessed in an experiment with a moving phantom during MR imaging. The FBG-based system was quantified by comparing the gold-standard shapes, the shape manually segmented on MRI and the FBG-based measurements. Results: The evaluation of the MR compatibility of FBG-based sensing and its accuracy shows that the needle deflection could be measured with an accuracy of 0.27 mm on average. Besides, the FBG-based measurements were comparable to the uncertainty of MR-based measurements estimated at half the voxel size in the MR image. Finally, the mean(standard deviation) Euclidean distance between MR- and FBG-based needle position

  1. Image grating metrology using phase-stepping interferometry in scanning beam interference lithography

    Science.gov (United States)

    Li, Minkang; Zhou, Changhe; Wei, Chunlong; Jia, Wei; Lu, Yancong; Xiang, Changcheng; Xiang, XianSong

    2016-10-01

    Large-sized gratings are essential optical elements in laser fusion and space astronomy facilities. Scanning beam interference lithography is an effective method to fabricate large-sized gratings. To minimize the nonlinear phase written into the photo-resist, the image grating must be measured to adjust the left and right beams to interfere at their waists. In this paper, we propose a new method to conduct wavefront metrology based on phase-stepping interferometry. Firstly, a transmission grating is used to combine the two beams to form an interferogram which is recorded by a charge coupled device(CCD). Phase steps are introduced by moving the grating with a linear stage monitored by a laser interferometer. A series of interferograms are recorded as the displacement is measured by the laser interferometer. Secondly, to eliminate the tilt and piston error during the phase stepping, the iterative least square phase shift method is implemented to obtain the wrapped phase. Thirdly, we use the discrete cosine transform least square method to unwrap the phase map. Experiment results indicate that the measured wavefront has a nonlinear phase around 0.05 λ@404.7nm. Finally, as the image grating is acquired, we simulate the print-error written into the photo-resist.

  2. Linear information retrieval method in X-ray grating-based phase contrast imaging and its interchangeability with tomographic reconstruction

    Science.gov (United States)

    Wu, Z.; Gao, K.; Wang, Z. L.; Shao, Q. G.; Hu, R. F.; Wei, C. X.; Zan, G. B.; Wali, F.; Luo, R. H.; Zhu, P. P.; Tian, Y. C.

    2017-06-01

    In X-ray grating-based phase contrast imaging, information retrieval is necessary for quantitative research, especially for phase tomography. However, numerous and repetitive processes have to be performed for tomographic reconstruction. In this paper, we report a novel information retrieval method, which enables retrieving phase and absorption information by means of a linear combination of two mutually conjugate images. Thanks to the distributive law of the multiplication as well as the commutative law and associative law of the addition, the information retrieval can be performed after tomographic reconstruction, thus simplifying the information retrieval procedure dramatically. The theoretical model of this method is established in both parallel beam geometry for Talbot interferometer and fan beam geometry for Talbot-Lau interferometer. Numerical experiments are also performed to confirm the feasibility and validity of the proposed method. In addition, we discuss its possibility in cone beam geometry and its advantages compared with other methods. Moreover, this method can also be employed in other differential phase contrast imaging methods, such as diffraction enhanced imaging, non-interferometric imaging, and edge illumination.

  3. Grating-Coupled Waveguide Cloaking

    International Nuclear Information System (INIS)

    Wang Jia-Fu; Qu Shao-Bo; Ma Hua; Wang Cong-Min; Wang Xin-Hua; Zhou Hang; Xu Zhuo; Xia Song

    2012-01-01

    Based on the concept of a grating-coupled waveguide (GCW), a new strategy for realizing EM cloaking is presented. Using metallic grating, incident waves are firstly coupled into the effective waveguide and then decoupled into free space behind, enabling EM waves to pass around the obstacle. Phase compensation in the waveguide keeps the wave-front shape behind the obstacle unchanged. Circular, rectangular and triangular cloaks are presented to verify the robustness of the GCW cloaking. Electric field animations and radar cross section (RCS) comparisons convincingly demonstrate the cloaking effect

  4. Fiber Bragg grating based notch filter for bit-rate-transparent NRZ to PRZ format conversion with two-degree-of-freedom optimization

    International Nuclear Information System (INIS)

    Cao, Hui; Zuo, Jun; Xiong, Bangyun; Cheng, Jianqun; Shu, Xuewen; Shen, Fangcheng; Liu, Xin; Atai, Javid

    2015-01-01

    We propose a novel notch-filtering scheme for bit-rate transparent all-optical NRZ-to-PRZ format conversion. The scheme is based on a two-degree-of-freedom optimally designed fiber Bragg grating. It is shown that a notch filter optimized for any specific operating bit rate can be used to realize high-Q-factor format conversion over a wide bit rate range without requiring any tuning. (paper)

  5. Conducting polymer based biomolecular electronic devices

    Indian Academy of Sciences (India)

    Conducting polymers; LB films; biosensor microactuators; monolayers. ... have been projected for applications for a wide range of biomolecular electronic devices such as optical, electronic, drug-delivery, memory and biosensing devices.

  6. Strain and temperature characteristics of the LP11 mode based on a few-mode fiber Bragg grating and core-offset splicing

    Science.gov (United States)

    Jin, Wenxing; Xu, Yao; Jiang, Youchao; Wu, Yue; Yao, Shuzhi; Xiao, Shiying; Qi, Yanhui; Ren, Wenhua; Jian, Shuisheng

    2018-02-01

    We propose and demonstrate a ring fiber laser based on a few-mode fiber Bragg grating for strain and temperature sensing using only the LP11 mode. The core-offset splicing method is used to ensure effective coupling from the fundamental mode to the LP11 mode. A stable erbium-doped fiber laser operating as a single LP11 mode with a 3 dB linewidth of about 0.02 nm and an optical signal-to-noise ratio over 42 dB is achieved by appropriately adjusting the polarization controller between the optical circulator and the few-mode fiber Bragg grating. A high axial strain sensitivity of 0.8778 pm μ\\varepsilon-1 and a temperature sensitivity of 9.9214 pm °C-1 are achieved with the advantages of all-fiber, simple construction and easy control.

  7. Design of a 50/50 splitting ratio non-polarizing beam splitter based on the modal method with fused-silica transmission gratings

    Science.gov (United States)

    Zhao, Huajun; Yuan, Dairong; Ming, Hai

    2011-04-01

    The optical design of a beam splitter that has a 50/50 splitting ratio regardless of the polarization is presented. The non-polarizing beam splitter (NPBS) is based on the fused-silica rectangular transmission gratings with high intensity tolerance. The modal method has been used to estimate the effective index of the modes excited in the grating region for TE and TM polarizations. If a phase difference equals an odd multiples of π/2 for the first two modes (i.e. modes 0 and 1), the incident light will be diffracted into the 0 and -1 orders with about 50% and 50% diffraction efficiency for TM and TE polarizations, respectively.

  8. Fabrication update on critical-angle transmission gratings for soft x-ray grating spectrometers

    Science.gov (United States)

    Heilmann, Ralf K.; Bruccoleri, Alex; Mukherjee, Pran; Yam, Jonathan; Schattenburg, Mark L.

    2011-09-01

    Diffraction grating-based, wavelength dispersive high-resolution soft x-ray spectroscopy of celestial sources promises to reveal crucial data for the study of the Warm-Hot Intergalactic Medium, the Interstellar Medium, warm absorption and outflows in Active Galactic Nuclei, coronal emission from stars, and other areas of interest to the astrophysics community. Our recently developed critical-angle transmission (CAT) gratings combine the advantages of the Chandra high and medium energy transmission gratings (low mass, high tolerance of misalignments and figure errors, polarization insensitivity) with those of blazed reflection gratings (high broad band diffraction efficiency, high resolution through use of higher diffraction orders) such as the ones on XMM-Newton. Extensive instrument and system configuration studies have shown that a CAT grating-based spectrometer is an outstanding instrument capable of delivering resolving power on the order of 5,000 and high effective area, even with a telescope point-spread function on the order of many arc-seconds. We have fabricated freestanding, ultra-high aspect-ratio CAT grating bars from silicon-on-insulator wafers using both wet and dry etch processes. The 200 nm-period grating bars are supported by an integrated Level 1 support mesh, and a coarser external Level 2 support mesh. The resulting grating membrane is mounted to a frame, resulting in a grating facet. Many such facets comprise a grating array that provides light-weight coverage of large-area telescope apertures. Here we present fabrication results on the integration of CAT gratings and the different high-throughput support mesh levels and on membrane-frame bonding. We also summarize recent x-ray data analysis of 3 and 6 micron deep wet-etched CAT grating prototypes.

  9. Fabrication of Optical Fiber Devices

    Science.gov (United States)

    Andres, Miguel V.

    In this paper we present the main research activities of the Laboratorio de Fibras Opticas del Instituto de Ciencia de los Materiales de la Universidad de Valencia. We show some of the main results obtained for devices based on tapered fibers, fiber Bragg gratings, acousto-optic effects and photonic crystal fibers.

  10. A glucose concentration and temperature sensor based on long period fiber gratings induced by electric-arc discharge

    Science.gov (United States)

    Du, Chao; Wang, Qi

    2017-10-01

    As one of the key parameters in biological and chemical reactions, glucose concentration objectively reflects the characteristics of reactions, so the real-time monitoring of glucose concentration is important in the field of biochemical. Meanwhile, the influence from temperature should be considered. The fiber sensors have been studied extensively for decades due to the advantages of small size, immunity to electromagnetic interference and high sensitivity, which are suitable for the application of biochemical sensing. A long period fiber grating (LPFG) sensor induced by electric-arc discharge has been fabricated and demonstrated for simultaneous measurement of glucose concentration and temperature. The proposed sensor was fabricated by inscribing a sing mode fiber (SMF) with periodic electric-arc discharge technology. During the fabrication process, the electric-arc discharge technology was produced by a commercial fusion splicer, and the period of inscribed LPFG was determined by the movement of translation stages. A serials of periodic geometrical deformations would be formed in SMF after the fabrication, and the discharge intensity and discharge time can be adjusted though the fusion splicer settings screen. The core mode can be coupled into the cladding modes at certain wavelength when they satisfy the phase-matching conditions, and there will be several resonance dips in the transmission spectrum in LPFG. The resonance dips formed by the coupling between cladding modes and core mode have different sensitivity responses, so the simultaneous measurement for multi-parameter can be realized by monitoring the wavelength shifts of the resonance dips. Compared with the LPFG based on conventional SMF, the glucose concentration sensitivity has been obviously enhanced by etching the cladding with hydrofluoric acid solution. Based on the independent measured results, a dual-parameter measurement matrix has been built for signal demodulation. Because of the easy

  11. Alternative technique for biodiesel quality control using an optical fiber long-period grating sensor

    International Nuclear Information System (INIS)

    Falate, Rosane; Nike, Karen; Costa Neto, Pedro Ramos da; Cacao Junior, Eduardo; Muller, Marcia; Kalinowski, Hypolito Jose; Fabris, Jose Luis

    2007-01-01

    We report the use of an optical fiber sensor to measure the soybean oil concentration in samples obtained from the mixture of pure biodiesel and commercial soybean oil. The operation of the device is based on the long-period grating sensitivity to the surrounding medium refractive index, which leads to measurable modifications in the grating transmission spectrum. The proposed analysis method results in errors in the oil concentration of 0.4% and 2.6% for pure biodiesel and commercial soybean oil, respectively. Techniques of total glycerol, dynamic viscosity, density, and hydrogen nuclear magnetic resonance spectroscopy were also employed to validate the proposed method. (author)

  12. Alternative technique for biodiesel quality control using an optical fiber long-period grating sensor

    Energy Technology Data Exchange (ETDEWEB)

    Falate, Rosane [Universidade Estadual de Ponta Grossa, PR (Brazil). Dept. de Informatica; Nike, Karen; Costa Neto, Pedro Ramos da [Universidade Tecnologica Federal do Parana, Curitiba (Brazil). Dept. de Quimica; Cacao Junior, Eduardo; Muller, Marcia; Kalinowski, Hypolito Jose; Fabris, Jose Luis [Universidade Tecnologica Federal do Parana, Curitiba (Brazil). Dept. de Fisica]. E-mail: fabris@utfpr.edu.br

    2007-07-01

    We report the use of an optical fiber sensor to measure the soybean oil concentration in samples obtained from the mixture of pure biodiesel and commercial soybean oil. The operation of the device is based on the long-period grating sensitivity to the surrounding medium refractive index, which leads to measurable modifications in the grating transmission spectrum. The proposed analysis method results in errors in the oil concentration of 0.4% and 2.6% for pure biodiesel and commercial soybean oil, respectively. Techniques of total glycerol, dynamic viscosity, density, and hydrogen nuclear magnetic resonance spectroscopy were also employed to validate the proposed method. (author)

  13. Synthesis of 1D Bragg gratings by a layer-aggregation method.

    Science.gov (United States)

    Capmany, José; Muriel, Miguel A; Sales, Salvador

    2007-08-15

    We present what we believe to be a novel method for the synthesis of complex 1D (fiber and waveguide) Bragg gratings, which is based on an impedance reconstruction layer aggregation technique. The main advantage brought by the method is the possibility of synthesizing structures containing defects or discontinuities of the size of the local period, a feature that is not possible with prior reported methods. In addition, this enhanced spatial resolution allows the synthesis of very strong fiber Bragg grating devices providing convergent solutions. The method directly renders the refractive index profile n(z) as it does not rely on the coupled-mode theory.

  14. A phase mask fiber grating and sensing applications

    Directory of Open Access Journals (Sweden)

    Preecha P. Yupapin

    2003-09-01

    Full Text Available This paper presents an investigation of a fabricated fiber grating device characteristics and its applications, using a phase mask writing technique. The use of a most common UV phase laser (KrF eximer laser, with high intensity light source was focussed to the phase mask for writing on a fiber optic sample. The device (i.e. grating characteristic especially, in sensing application, was investigated. The possibility of using such device for temperature and strain sensors is discussed.

  15. Compact multichannel high-resolution micro-electro-mechanical systems-based interrogator for Fiber Bragg grating sensing

    DEFF Research Database (Denmark)

    Ganziy, Denis; Rose, Bjarke; Bang, Ole

    2017-01-01

    We propose a novel type of compact high-resolution multichannel micro-electro-mechanical systems (MEMS)-based interrogator, where we replace the linear detector with a digital micromirror device (DMD). The DMD is typically cheaper and has better pixel sampling than an InGaAs detector used...

  16. Moiré volume Bragg grating filter with tunable bandwidth.

    Science.gov (United States)

    Mokhov, Sergiy; Ott, Daniel; Divliansky, Ivan; Zeldovich, Boris; Glebov, Leonid

    2014-08-25

    We propose a monolithic large-aperture narrowband optical filter based on a moiré volume Bragg grating formed by two sequentially recorded gratings with slightly different resonant wavelengths. Such recording creates a spatial modulation of refractive index with a slowly varying sinusoidal envelope. By cutting a specimen at a small angle, to a thickness of one-period of this envelope, the longitudinal envelope profile will shift from a sine profile to a cosine profile across the face of the device. The transmission peak of the filter has a tunable bandwidth while remaining at a fixed resonant wavelength by a transversal shift of incidence position. Analytical expressions for the tunable bandwidth of such a filter are calculated and experimental data from a filter operating at 1064 nm with bandwidth range 30-90 pm is demonstrated.

  17. Quadratic grating apodized photon sieves for simultaneous multiplane microscopy

    Science.gov (United States)

    Cheng, Yiguang; Zhu, Jiangping; He, Yu; Tang, Yan; Hu, Song; Zhao, Lixin

    2017-10-01

    We present a new type of imaging device, named quadratic grating apodized photon sieve (QGPS), used as the objective for simultaneous multiplane imaging in X-rays. The proposed QGPS is structured based on the combination of two concepts: photon sieves and quadratic gratings. Its design principles are also expounded in detail. Analysis of imaging properties of QGPS in terms of point-spread function shows that QGPS can image multiple layers within an object field onto a single image plane. Simulated and experimental results in visible light both demonstrate the feasibility of QGPS for simultaneous multiplane imaging, which is extremely promising to detect dynamic specimens by X-ray microscopy in the physical and life sciences.

  18. Laser formation of Bragg gratings in polymer nanocomposite materials

    Energy Technology Data Exchange (ETDEWEB)

    Nazarov, M M; Khaydukov, K V; Sokolov, V I; Khaydukov, E V [Institute on Laser and Information Technologies, Russian Academy of Sciences, Shatura, Moscow Region (Russian Federation)

    2016-01-31

    The method investigated in this work is based on the laser-induced, spatially inhomogeneous polymerisation of nanocomposite materials and allows control over the motion and structuring of nanoparticles. The mechanisms of nanoparticle concentration redistribution in the process of radical photopolymerisation are studied. It is shown that under the condition of spatially inhomogeneous illumination of a nanocomposite material, nanoparticles are diffused from the illuminated areas into the dark fields. Diffraction gratings with a thickness of 8 μm and a refractive index modulation of 1 × 10{sup -2} are written in an OCM-2 monomer impregnated by silicon nanoparticles. The gratings may be used in the development of narrowband filters, in holographic information recording and as dispersion elements in integrated optical devices. (interaction of laser radiation with matter. laser plasma)

  19. Critical components for diamond-based quantum coherent devices

    International Nuclear Information System (INIS)

    Greentree, Andrew D; Olivero, Paolo; Draganski, Martin; Trajkov, Elizabeth; Rabeau, James R; Reichart, Patrick; Gibson, Brant C; Rubanov, Sergey; Huntington, Shane T; Jamieson, David N; Prawer, Steven

    2006-01-01

    The necessary elements for practical devices exploiting quantum coherence in diamond materials are summarized, and progress towards their realization documented. A brief review of future prospects for diamond-based devices is also provided

  20. Resonant transmission and mode modulation of acoustic waves in H-shaped metallic gratings

    International Nuclear Information System (INIS)

    Deng, Yu-Qiang; Fan, Ren-Hao; Zhang, Kun; Peng, Ru-Wen; Qi, Dong-Xiang

    2015-01-01

    In this work, we demonstrate that resonant full transmission of acoustic waves exists in subwavelength H-shaped metallic gratings, and transmission peaks can be efficiently tuned by adjusting the grating geometry. We investigate this phenomenon through both numerical simulations and theoretical calculations based on rigorous-coupled wave analysis. The transmission peaks are originated from Fabry-Perot resonances together with the couplings between the diffractive wave on the surface and the multiple guided modes in the slits. Moreover, the transmission modes can be efficiently tuned by adjusting the cavity geometry, without changing the grating thickness. The mechanism is analyzed based on an equivalent circuit model and verified by both the theoretical calculations and the numerical simulations. This research has potential application in acoustic-device miniaturization over a wide range of wavelengths

  1. Operational verification of a blow out preventer utilizing fiber Bragg grating based strain gauges

    Science.gov (United States)

    Turner, Alan L.; Loustau, Philippe; Thibodeau, Dan

    2015-05-01

    Ultra-deep water BOP (Blowout Preventer) operation poses numerous challenges in obtaining accurate knowledge of current system integrity and component condition- a salient example is the difficulty of verifying closure of the pipe and shearing rams during and after well control events. Ascertaining the integrity of these functions is currently based on a manual volume measurement performed with a stop watch. Advances in sensor technology now permit more accurate methods of BOP condition monitoring. Fiber optic sensing technology and particularly fiber optic strain gauges have evolved to a point where we can derive a good representation of what is happening inside a BOP by installing sensors on the outside shell. Function signatures can be baselined to establish thresholds that indicate successful function activation. Based on this knowledge base, signal variation over time can then be utilized to assess degradation of these functions and subsequent failure to function. Monitoring the BOP from the outside has the advantage of gathering data through a system that can be interfaced with risk based integrity management software and/or a smart monitoring system that analyzes BOP control redundancies without the requirement of interfacing with OEM control systems. The paper will present the results of ongoing work on a fully instrumented 13-½" 10,000 psi pipe ram. Instrumentation includes commonly used pressure transducers, accelerometers, flow meters, and optical strain gauges. Correlation will be presented between flow, pressure, acceleration signatures and the fiber optic strain gauge's response as it relates to functional verification and component level degradation trending.

  2. Bragg-grating-based rare-earth-ion-doped channel waveguide lasers and their applications

    NARCIS (Netherlands)

    Bernhardi, Edward

    2012-01-01

    The research presented in this thesis concerns the investigation and development of Bragggrating-based integrated cavities for the rare-earth-ion-doped Al2O3 (aluminium oxide) waveguide platform, both from a theoretical and an experimental point of view, with the primary purpose of realizing

  3. Microfiber devices based on carbon materials

    OpenAIRE

    Gengzhi Sun; Xuewan Wang; Peng Chen

    2015-01-01

    Microfiber devices are able to extend the micro/nano functionalities of materials or devices to the macroscopic scale with excellent flexibility and weavability, promising a variety of unique applications and, sometimes, also improved performance as compared with bulk counterparts. The fiber electrodes in these devices are often made of carbon materials (e.g. carbon nanotubes and graphene) because of their exceptional electrical, mechanical, and structural properties. Covering the latest deve...

  4. Deep-etched sinusoidal polarizing beam splitter grating.

    Science.gov (United States)

    Feng, Jijun; Zhou, Changhe; Cao, Hongchao; Lv, Peng

    2010-04-01

    A sinusoidal-shaped fused-silica grating as a highly efficient polarizing beam splitter (PBS) is investigated based on the simplified modal method. The grating structure depends mainly on the ratio of groove depth to grating period and the ratio of incident wavelength to grating period. These ratios can be used as a guideline for the grating design at different wavelengths. A sinusoidal-groove PBS grating is designed at a wavelength of 1310 nm under Littrow mounting, and the transmitted TM and TE polarized waves are mainly diffracted into the zeroth order and the -1st order, respectively. The grating profile is optimized by using rigorous coupled-wave analysis. The designed PBS grating is highly efficient (>95.98%) over the O-band wavelength range (1260-1360 nm) for both TE and TM polarizations. The sinusoidal grating can exhibit higher diffraction efficiency, larger extinction ratio, and less reflection loss than the rectangular-groove PBS grating. By applying wet etching technology on the rectangular grating, which was manufactured by holographic recording and inductively coupled plasma etching technology, the sinusoidal grating can be approximately fabricated. Experimental results are in agreement with theoretical values.

  5. A Flexible Microcontroller-Based Data Acquisition Device

    OpenAIRE

    Hercog, Darko; Gergič, Bojan

    2014-01-01

    This paper presents a low-cost microcontroller-based data acquisition device. The key component of the presented solution is a configurable microcontroller-based device with an integrated USB transceiver and a 12-bit analogue-to-digital converter (ADC). The presented embedded DAQ device contains a preloaded program (firmware) that enables easy acquisition and generation of analogue and digital signals and data transfer between the device and the application running on a PC via USB bus. This d...

  6. Real-time Cure Monitoring of Composites Using a Guided wave-based System with High Temperature Piezoelectric Transducers, Fiber Bragg Gratings, and Phase-shifted Fiber Bragg Gratings

    Science.gov (United States)

    Hudson, Tyler Blake

    An in-process, in-situ cure monitoring technique utilizing a guided wave-based concept for carbon fiber reinforced polymer (CFRP) composites was investigated. Two automated cure monitoring systems using guided-wave ultrasonics were developed for characterizing the state of the cure. In the first system, surface mounted high-temperature piezoelectric transducer arrays were employed for actuation and sensing. The second system motivated by the success of the first system includes a single piezoelectric disc, bonded onto the surface of the composite for excitation; fiber Bragg gratings (FBGs) and/or phase-shifted fiber Bragg gratings (PSFBGs) were embedded in the composite for distributed cure sensing. Composite material properties (viscosity and degree of cure) evolved during cure of the panels fabricated from HexcelRTM IM7/8552 prepreg correlated well to the amplitude, time of arrival, and group velocity of the guided wave-based measurements during the cure cycle. In addition, key phase transitions (gelation and vitrification) were clearly identified from the experimental data during the same cure cycle. The material properties and phase transitions were validated using cure process modeling software (e.g., RAVENRTM). The high-temperature piezoelectric transducer array system demonstrated the feasibility of a guided wave-based, in-process, cure monitoring and provided the framework for defect detection during cure. Ultimately, this system could provide a traceable data stream for non-compliance investigations during serial production and perform closed-loop process control to maximize composite panel quality and consistency. In addition, this system could be deployed as a "smart" caul/tool plate to existing production lines without changing the design of the aircraft/structure. With the second system, strain in low frequency (quasi-static) and the guided wavebased signals in several hundred kilohertz range were measured almost simultaneously using the same FBG or PS

  7. Grating-based X-ray Dark-field Computed Tomography of Living Mice.

    Science.gov (United States)

    Velroyen, A; Yaroshenko, A; Hahn, D; Fehringer, A; Tapfer, A; Müller, M; Noël, P B; Pauwels, B; Sasov, A; Yildirim, A Ö; Eickelberg, O; Hellbach, K; Auweter, S D; Meinel, F G; Reiser, M F; Bech, M; Pfeiffer, F

    2015-10-01

    Changes in x-ray attenuating tissue caused by lung disorders like emphysema or fibrosis are subtle and thus only resolved by high-resolution computed tomography (CT). The structural reorganization, however, is of strong influence for lung function. Dark-field CT (DFCT), based on small-angle scattering of x-rays, reveals such structural changes even at resolutions coarser than the pulmonary network and thus provides access to their anatomical distribution. In this proof-of-concept study we present x-ray in vivo DFCTs of lungs of a healthy, an emphysematous and a fibrotic mouse. The tomographies show excellent depiction of the distribution of structural - and thus indirectly functional - changes in lung parenchyma, on single-modality slices in dark field as well as on multimodal fusion images. Therefore, we anticipate numerous applications of DFCT in diagnostic lung imaging. We introduce a scatter-based Hounsfield Unit (sHU) scale to facilitate comparability of scans. In this newly defined sHU scale, the pathophysiological changes by emphysema and fibrosis cause a shift towards lower numbers, compared to healthy lung tissue.

  8. Semiconductor-based, large-area, flexible, electronic devices on {110} oriented substrates

    Science.gov (United States)

    Goyal, Amit

    2014-08-05

    Novel articles and methods to fabricate the same resulting in flexible, oriented, semiconductor-based, electronic devices on {110} textured substrates are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  9. [100] or [110] aligned, semiconductor-based, large-area, flexible, electronic devices

    Science.gov (United States)

    Goyal, Amit

    2015-03-24

    Novel articles and methods to fabricate the same resulting in flexible, large-area, [100] or [110] textured, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  10. {100} or 45.degree.-rotated {100}, semiconductor-based, large-area, flexible, electronic devices

    Science.gov (United States)

    Goyal, Amit [Knoxville, TN

    2012-05-15

    Novel articles and methods to fabricate the same resulting in flexible, {100} or 45.degree.-rotated {100} oriented, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  11. Plasmonic Transmission Gratings – Fabrication and Characterization

    DEFF Research Database (Denmark)

    Sierant, Aleksandra; Jany, Benedykt; Bartoszek-Bober, Dobrosława

    Surface plasmon polaritons (SPPs) are collective electron oscillations, confined at metal-dielectric interfaces. Coupling incident photons to SPPs may lead to spectrally broad field enhancement and confinement below the diffraction limit [1]. This phenomenon facilitates various applications......, including highly sensitive refractive index sensing [2], and plasmonic dipole mirrors for cold atoms [3]. Key to a successful application is a strong photon-to-SPP coupling. To this end, prism-based coupling is classically used, but this method contradicts compact device applications. An alternative...... the proposed plasmonic transmission gratings via near-field optical scanning microscopy (NSOM) and goniometric far field measurements. We support the evidence of our analyses with numerical calculations, carried out via rigorous coupled wave analysis (RCWA) and finite-difference in time-domain (FDTD...

  12. Vaginal rejuvenation using energy-based devices

    Directory of Open Access Journals (Sweden)

    Cheryl Karcher, MD

    2016-09-01

    Full Text Available Physiologic changes in a woman’s life, such as childbirth, weight fluctuations, and hormonal changes due to aging and menopause, may alter the laxity of the vaginal canal, damage the pelvic floor, and devitalize the mucosal tone of the vaginal wall. These events often lead to the development of genitourinary conditions such as stress urinary incontinence; vaginal atrophy; dryness; and physiologic distress affecting a woman’s quality of life, self-confidence, and sexuality. Various treatment modalities are currently available to manage these indications, varying from invasive vaginal surgery to more benign treatments like topical vaginal hormonal gels or hormone-replacement therapy. A new trend gaining momentum is the advent of energy-based devices for vaginal rejuvenation that apply thermal or nonthermal energy to the various layers of the vaginal tissue, stimulating collagen regeneration contracture of elastin fibers, neovascularization, and improved vaginal lubrication. This review aims to present the available technologies offering vaginal rejuvenation and the scientific evidence that underlines their safety and efficacy for this indication.

  13. Corrugated grating on organic multilayer Bragg reflector

    Science.gov (United States)

    Jaquet, Sylvain; Scharf, Toralf; Herzig, Hans Peter

    2007-08-01

    Polymeric multilayer Bragg structures are combined with diffractive gratings to produce artificial visual color effects. A particular effect is expected due to the angular reflection dependence of the multilayer Bragg structure and the dispersion caused by the grating. The combined effects can also be used to design particular filter functions and various resonant structures. The multilayer Bragg structure is fabricated by spin-coating of two different low-cost polymer materials in solution on a cleaned glass substrate. These polymers have a refractive index difference of about 0.15 and permit multilayer coatings without interlayer problems. Master gratings of different periods are realized by laser beam interference and replicated gratings are superimposed on the multilayer structure by soft embossing in a UV curing glue. The fabrication process requires only polymer materials. The obtained devices are stable and robust. Angular dependent reflection spectrums for the visible are measured. These results show that it is possible to obtain unexpected reflection effects. A rich variety of color spectra can be generated, which is not possible with a single grating. This can be explained by the coupling of transmission of grating orders and the Bragg reflection band. A simple model permits to explain some of the spectral vs angular dependence of reflected light.

  14. Multiwavelength optical scatterometry of dielectric gratings

    KAUST Repository

    Yashina, Nataliya P.; Melezhik, Petr N.; Sirenko, Kostyantyn; Granet, Gerard

    2012-01-01

    is based on rigorous solutions of 2-D initial boundary value problems of the gratings theory. The quintessence and advantage of the method is the possibility to perform an efficient analysis simultaneously and interactively both for steady state

  15. An elastomeric grating coupler

    NARCIS (Netherlands)

    Kocabas, A.; Ay, F.; Dana, A.; Aydinli, A.

    We report on a novel nondestructive and reversible method for coupling free space light to planar optical waveguides. In this method, an elastomeric grating is used to produce an effective refractive index modulation on the surface of the optical waveguide. The external elastomeric grating binds to

  16. Bragg gratings in Topas

    DEFF Research Database (Denmark)

    Zhang, C.; Webb, D.J.; Kalli, K.

    We report for the first time fibre Bragg grating inscription in microstructured optical fibre fabricated from Topas® cyclic olefin copolymer. The temperature sensitivity of the grating was studied revealing a positive Bragg wavelength shift of approximately 0.8 nmK-1,the largest sensitivity yet...

  17. Invited Article: An active terahertz polarization converter employing vanadium dioxide and a metal wire grating in total internal reflection geometry

    Science.gov (United States)

    Liu, Xudong; Chen, Xuequan; Parrott, Edward P. J.; Han, Chunrui; Humbert, Georges; Crunteanu, Aurelian; Pickwell-MacPherson, Emma

    2018-05-01

    Active broadband terahertz (THz) polarization manipulation devices are challenging to realize, but also of great demand in broadband terahertz systems. Vanadium dioxide (VO2) shows a promising phase transition for active control of THz waves and provides broadband polarization characteristics when integrated within grating-type structures. We creatively combine a VO2-based grating structure with a total internal reflection (TIR) geometry providing a novel interaction mechanism between the electromagnetic waves and the device, to realize a powerful active broadband THz polarization-controlling device. The device is based on a Si-substrate coated with a VO2 layer and a metal grating structure on top, attached to a prism for generating the TIR condition on the Si-VO2-grating interface. The grating is connected to electrodes for electrically switching the VO2 between its insulating and conducting phases. By properly selecting the incident angle of the THz waves, the grating direction, and the incident polarization state, we first achieved a broadband intensity modulator under a fused silica prism with an average modulation depth of 99.75% in the 0.2-1.1 THz region. Additionally, we realized an active ultra-broadband quarter-wave converter under a Si prism that can be switched between a 45° linear rotator and a quarter wave converter in the 0.8-1.5 THz region. This is the first demonstration of an active quarter-wave converter with ultra-broad bandwidth performance. Our work shows a highly flexible and multifunctional polarization-controlling device for broadband THz applications.

  18. Optical fibres sensor based in the intensity switch of a linear laser with two Bragg gratings; Sensor de fibra optica basado en el salto de intensidad de un laser lineal con dos rejillas de Bragg

    Energy Technology Data Exchange (ETDEWEB)

    Basurto P, M.A.; Kuzin, E.A.; Archundia B, C.; Marroquin, E.; May A, M.; Cerecedo N, H.H.; Sanchez M, J.J. [Departamento de Fotonica y Fisica Optica, Instituto Nacional de Astrofisica, Optica y Electronica (INAOE). Apartado Postal 51 y 216, 72000 Puebla (Mexico); Tentori S, D.; Marquez B, I.; Shliagin, M.; Miridonov, S. [Centro de Investigacion CESE (Mexico)

    2000-07-01

    In this work we propose a new configuration for an optical fiber temperature sensor, based on a linear type Er-doped fiber laser. The laser cavity consists of an Er-doped fiber and two identical Bragg gratings at the fiber ends (working as reflectors). Temperature changes are detected by measuring, through one of the gratings, the intensity variations atthe system's output. When the temperature of one of the Bragg gratings is modified, a wavelength shift of its spectral reflectivity is observed. Hence, the laser emission intensity of the system is modified. We present experimental results of the intensity switch observed when the temperature difference between the gratings detunes their spectral reflectance. Making use of this effect it is possible to develop limit comparators to bound the temperature range for the object under supervision. This limiting work can be performed with a high sensitivity using a very simple interrogation procedure. (Author)

  19. Integrating Sphere-based Weathering Device

    Data.gov (United States)

    Federal Laboratory Consortium — Description:In the artificial ultraviolet (UV) weathering of materials, a need exists for weathering devices that can uniformly illuminate test specimens with a high...

  20. Toward biomaterial-based implantable photonic devices

    Directory of Open Access Journals (Sweden)

    Humar Matjaž

    2017-03-01

    Full Text Available Optical technologies are essential for the rapid and efficient delivery of health care to patients. Efforts have begun to implement these technologies in miniature devices that are implantable in patients for continuous or chronic uses. In this review, we discuss guidelines for biomaterials suitable for use in vivo. Basic optical functions such as focusing, reflection, and diffraction have been realized with biopolymers. Biocompatible optical fibers can deliver sensing or therapeutic-inducing light into tissues and enable optical communications with implanted photonic devices. Wirelessly powered, light-emitting diodes (LEDs and miniature lasers made of biocompatible materials may offer new approaches in optical sensing and therapy. Advances in biotechnologies, such as optogenetics, enable more sophisticated photonic devices with a high level of integration with neurological or physiological circuits. With further innovations and translational development, implantable photonic devices offer a pathway to improve health monitoring, diagnostics, and light-activated therapies.

  1. Pyridine Based Polymer Light-Emitting Devices

    National Research Council Canada - National Science Library

    Wang, Y

    1997-01-01

    ...) as a hole transporting/electron blocking layer. This improves the device efficiency and brightness significantly due to the charge confinement and exciplex emission at the PVK/emitting polymer interface...

  2. Fiber Bragg Grating Sensors for Harsh Environments

    Directory of Open Access Journals (Sweden)

    Stephen J. Mihailov

    2012-02-01

    Full Text Available Because of their small size, passive nature, immunity to electromagnetic interference, and capability to directly measure physical parameters such as temperature and strain, fiber Bragg grating sensors have developed beyond a laboratory curiosity and are becoming a mainstream sensing technology. Recently, high temperature stable gratings based on regeneration techniques and femtosecond infrared laser processing have shown promise for use in extreme environments such as high temperature, pressure or ionizing radiation. Such gratings are ideally suited for energy production applications where there is a requirement for advanced energy system instrumentation and controls that are operable in harsh environments. This paper will present a review of some of the more recent developments.

  3. Undergraduate experiment with fractal diffraction gratings

    International Nuclear Information System (INIS)

    Monsoriu, Juan A; Furlan, Walter D; Pons, Amparo; Barreiro, Juan C; Gimenez, Marcos H

    2011-01-01

    We present a simple diffraction experiment with fractal gratings based on the triadic Cantor set. Diffraction by fractals is proposed as a motivating strategy for students of optics in the potential applications of optical processing. Fraunhofer diffraction patterns are obtained using standard equipment present in most undergraduate physics laboratories and compared with those obtained with conventional periodic gratings. It is shown that fractal gratings produce self-similar diffraction patterns which can be evaluated analytically. Good agreement is obtained between experimental and numerical results.

  4. The grating projection system: a laser light pattern projection technique for long distance illumination based on the Talbot effect

    International Nuclear Information System (INIS)

    Castagner, J L; Jones, A R

    2003-01-01

    Inspired by the Talbot effect, a grating projection system was designed. Periodic patterns were produced from a projection of a diffraction grating illuminated by a spherical wave of monochromatic coherent light. The diffracted light was collimated by a lens, the focal distance of which was at the centre of the incident spherical wave. Experiments demonstrated that the diffracted orders were also spherical waves centred on the same transverse plane as the incident light. The periodic illumination observed at different locations along the optic axis was proven to be the result of interference between the diffracted orders. It was demonstrated that this system could be used to measure velocities up to 20 m s -1 of particles crossing the fringes at distances up to 3 m

  5. Metallic-packaging fiber Bragg grating sensor based on ultrasonic welding for strain-insensitive temperature measurement

    Science.gov (United States)

    Zhu, Lianqing; Yang, Runtao; Zhang, Yumin; Dong, Mingli; Lou, Xiaoping

    2018-04-01

    In this paper, a metallic-packaging fiber Bragg grating temperature sensor characterized by a strain insensitive design is demonstrated. The sensor is fabricated by the one-step ultrasonic welding technique using type-II fiber Bragg grating combined with an aluminum alloy substrate. Finite element analysis is used to perform theoretical evaluation. The result of the experiment illustrates that the metallic-packaging temperature sensor is insensitive to longitudinal strain. The sensor's temperature sensitivity is 36 pm/°C over the range of 50-110 °C, with the correlation coefficient (R2) being 0.999. The sensor's temporal response is 40 s at a sudden temperature change from 21 °C to 100 °C. The proposed sensor can be applied on reliable and precise temperature measurement.

  6. Integrated mechano-optical hydrogen gas sensor using cantilever bending readout with a Si3N4 grated waveguide.

    NARCIS (Netherlands)

    Pham Van So, P.V.S.; Dijkstra, Mindert; van Wolferen, Hendricus A.G.M.; Pollnau, Markus; Krijnen, Gijsbertus J.M.; Hoekstra, Hugo

    We demonstrate a proof of concept of a novel and compact integrated mechano-optical sensor for H2 detection based on a microcantilever suspended above a Si3N4 grated waveguide. The fabricated devices are mechanically and optically modeled and characterized. Sensing operation of the sensor is

  7. Toward flexible polymer and paper-based energy storage devices

    Energy Technology Data Exchange (ETDEWEB)

    Nyholm, Leif [Department of Materials Chemistry, The Aangstroem Laboratory, Uppsala University, Box 538, SE-751 21 Uppsala (Sweden); Nystroem, Gustav; Mihranyan, Albert; Stroemme, Maria [Nanotechnology and Functional Materials, Department of Engineering Sciences, The Aangstroem Laboratory, Uppsala University, Box 534, SE-751 21 Uppsala (Sweden)

    2011-09-01

    All-polymer and paper-based energy storage devices have significant inherent advantages in comparison with many currently employed batteries and supercapacitors regarding environmental friendliness, flexibility, cost and versatility. The research within this field is currently undergoing an exciting development as new polymers, composites and paper-based devices are being developed. In this report, we review recent progress concerning the development of flexible energy storage devices based on electronically conducting polymers and cellulose containing composites with particular emphasis on paper-based batteries and supercapacitors. We discuss recent progress in the development of the most commonly used electronically conducting polymers used in flexible device prototypes, the advantages and disadvantages of this type of energy storage devices, as well as the two main approaches used in the manufacturing of paper-based charge storage devices. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. A packaged, low-cost, robust optical fiber strain sensor based on small cladding fiber sandwiched within periodic polymer grating.

    Science.gov (United States)

    Chiang, Chia-Chin; Li, Chein-Hsing

    2014-06-02

    In the present study, a novel packaged long-period fiber grating (PLPFG) strain sensor is first presented. The MEMS process was utilized to fabricate the packaged optical fiber strain sensor. The sensor structure consisted of etched optical fiber sandwiched between two layers of thick photoresist SU-8 3050 and then packaged with poly (dimethylsiloxane) (PDMS) polymer material to construct the PLPFG strain sensor. The PDMS packaging material was used to prevent the glue effect, wherein glue flows into the LPFG structure and reduces coupling strength, in the surface bonding process. Because the fiber grating was packaged with PDMS material, it was effectively protected and made robust. The resonance attenuation dip of PLPFG grows when it is loading. This study explored the size effect of the grating period and fiber diameter of PLPFG via tensile testing. The experimental results found that the best strain sensitivity of the PLPFG strain sensor was -0.0342 dB/με, and that an R2 value of 0.963 was reached.

  9. Humidity Sensor Based on Bragg Gratings Developed on the End Facet of an Optical Fiber by Sputtering of One Single Material

    Directory of Open Access Journals (Sweden)

    Joaquin Ascorbe

    2017-04-01

    Full Text Available The refractive index of sputtered indium oxide nanocoatings has been altered just by changing the sputtering parameters, such as pressure. These induced changes have been exploited for the generation of a grating on the end facet of an optical fiber towards the development of wavelength-modulated optical fiber humidity sensors. A theoretical analysis has also been performed in order to study the different parameters involved in the fabrication of this optical structure and how they would affect the sensitivity of these devices. Experimental and theoretical results are in good agreement. A sensitivity of 150 pm/%RH was obtained for relative humidity changes from 20% to 60%. This kind of humidity sensors shows a maximum hysteresis of 1.3% relative humidity.

  10. Defect grating modes as superimposed grating states

    NARCIS (Netherlands)

    van Groesen, Embrecht W.C.; Sopaheluwakan, A.; Andonowati, A.; de Ridder, R.M; de Ridder, R.M.; Altena, G; Altena, G.; Geuzebroek, D.H.; Geuzenboek, D.; Dekker, R.; Dekker, R

    2003-01-01

    For a symmetric grating structure with a defect, we show that a fully transmitted defect mode in the band gap can be obtained as a superposition of two steady states: an amplified and an attenuated defect state. Without scanning the whole band gap by transmission calculations, this simplifies the

  11. Diffraction study of duty-cycle error in ferroelectric quasi-phase-matching gratings with Gaussian beam illumination

    Science.gov (United States)

    Dwivedi, Prashant Povel; Kumar, Challa Sesha Sai Pavan; Choi, Hee Joo; Cha, Myoungsik

    2016-02-01

    Random duty-cycle error (RDE) is inherent in the fabrication of ferroelectric quasi-phase-matching (QPM) gratings. Although a small RDE may not affect the nonlinearity of QPM devices, it enhances non-phase-matched parasitic harmonic generations, limiting the device performance in some applications. Recently, we demonstrated a simple method for measuring the RDE in QPM gratings by analyzing the far-field diffraction pattern obtained by uniform illumination (Dwivedi et al. in Opt Express 21:30221-30226, 2013). In the present study, we used a Gaussian beam illumination for the diffraction experiment to measure noise spectra that are less affected by the pedestals of the strong diffraction orders. Our results were compared with our calculations based on a random grating model, demonstrating improved resolution in the RDE estimation.

  12. Pemodelan Tapis Fabry-perot pada Serat Optik dengan Menggunakan Fiber Bragg Grating

    OpenAIRE

    Pramuliawati, Septi; ', Saktioto; ', Defrianto

    2015-01-01

    Fabry-perot filter was successfully developed by a uniform Fiber Bragg Grating in fiber optic. A characterization of Bragg Grating was analyzed by using computational model with second-order of Transfer Matrix Method based on Coupled Mode Theory. The reflectivity, length of grating, and bandwidth were parametrics to determine the performance of single Bragg Grating. The transmission spectrum showed the longer grating is designed, the larger the reflectivity was produced, so that the transmiss...

  13. Microscopic observation of zenithal bistable switching in nematic devices with different surface relief structures

    International Nuclear Information System (INIS)

    Uche, C; Elston, S J; Parry-Jones, L A

    2005-01-01

    Nematic liquid crystals have been shown to exhibit zenithal electro-optic bistability in devices containing sinusoidal and deformed sinusoidal gratings. Recently it has been shown that zenithal bistable states can also be supported at isolated edges of square gratings. In this paper, we present microscopic observations of bistability in cells containing sinusoidal gratings and long-pitch square gratings. We have also investigated a novel display based on square wells. High frame-rate video microscopy was used to obtain time-sequenced images when the devices were switched with monopolar pulses. These show that zenithal bistable switching can occur by two different processes: (i) domain growth (observed in cells containing sinusoidal gratings) and (ii) homogenous switching (observed in cells containing isolated edges

  14. Characterization of Early Age Curing and Shrinkage of Metakaolin-Based Inorganic Binders with Different Rheological Behavior by Fiber Bragg Grating Sensors.

    Science.gov (United States)

    Palumbo, Giovanna; Iadicicco, Agostino; Messina, Francesco; Ferone, Claudio; Campopiano, Stefania; Cioffi, Raffaele; Colangelo, Francesco

    2017-12-22

    This paper reports results related to early age temperature and shrinkage measurements by means fiber Bragg gratings (FBGs), which were embedded in geopolymer matrices. The sensors were properly packaged in order to discriminate between different shrinkage behavior and temperature development. Geopolymer systems based on metakaolin were investigated, which dealt with different commercial aluminosilicate precursors and siliceous filler contents. The proposed measuring system will allow us to control, in a very accurate way, the early age phases of the binding systems made by metakaolin geopolymer. A series of experiments were conducted on different compositions; moreover, rheological issues related to the proposed experimental method were also assessed.

  15. CW 50W/M2 = 10.9 diode laser source by spectral beam combining based on a transmission grating.

    Science.gov (United States)

    Zhang, Jun; Peng, Hangyu; Fu, Xihong; Liu, Yun; Qin, Li; Miao, Guoqing; Wang, Lijun

    2013-02-11

    An external cavity structure based on the -1st transmission grating is introduced to spectral beam combining a 970 nm diode laser bar. A CW output power of 50.8 W, an electro-optical conversion efficiency of 45%, a spectral beam combining efficiency of 90.2% and a holistic M(2) value of 10.9 are achieved. This shows a way for a diode laser source with several KW power and diffraction-limited beam quality at the same time.

  16. Model-based engineering for medical-device software.

    Science.gov (United States)

    Ray, Arnab; Jetley, Raoul; Jones, Paul L; Zhang, Yi

    2010-01-01

    This paper demonstrates the benefits of adopting model-based design techniques for engineering medical device software. By using a patient-controlled analgesic (PCA) infusion pump as a candidate medical device, the authors show how using models to capture design information allows for i) fast and efficient construction of executable device prototypes ii) creation of a standard, reusable baseline software architecture for a particular device family, iii) formal verification of the design against safety requirements, and iv) creation of a safety framework that reduces verification costs for future versions of the device software. 1.

  17. Fibre Bragg grating for flood embankment monitoring

    Science.gov (United States)

    Markowski, Konrad; Nevar, Stanislau; Dworzanski, Adam; Hackiewicz, Krzysztof; Jedrzejewski, Kazimierz

    2014-11-01

    In this article we present the preliminary studies for the flood embankment monitoring system based on the fibre Bragg gratings. The idea of the system is presented. The Bragg resonance shift is transformed to the change of the power detected by the standard InGaAs photodiode. The discrimination of the received power was executed by another fibre Bragg grating with different parameters. The project of the fully functional system is presented as well.

  18. New Development of Membrane Base Optoelectronic Devices

    Directory of Open Access Journals (Sweden)

    Leon Hamui

    2017-12-01

    Full Text Available It is known that one factor that affects the operation of optoelectronic devices is the effective protection of the semiconductor materials against environmental conditions. The permeation of atmospheric oxygen and water molecules into the device structure induces degradation of the electrodes and the semiconductor. As a result, in this communication we report the fabrication of semiconductor membranes consisting of Magnesium Phthalocyanine-allene (MgPc-allene particles dispersed in Nylon 11 films. These membranes combine polymer properties with organic semiconductors properties and also provide a barrier effect for the atmospheric gas molecules. They were prepared by high vacuum evaporation and followed by thermal relaxation technique. For the characterization of the obtained membranes, Fourier-transform infrared spectroscopy (FT-IR, scanning electron microscopy (SEM, and energy dispersive spectroscopy (EDS were used to determine the chemical and microstructural properties. UV-ViS, null ellipsometry, and visible photoluminescence (PL at room temperature were used to characterize the optoelectronic properties. These results were compared with those obtained for the organic semiconductors: MgPc-allene thin films. Additionally, semiconductor membranes devices have been prepared, and a study of the device electronic transport properties was conducted by measuring electrical current density-voltage (J-V characteristics by four point probes with different wavelengths. The resistance properties against different environmental molecules are enhanced, maintaining their semiconductor functionality that makes them candidates for optoelectronic applications.

  19. Enhanced direct-modulated bandwidth of 37 GHz by a multi-section laser with a coupled-cavity-injection-grating design

    DEFF Research Database (Denmark)

    Bach, L.; Kaiser, W.; Reithmaier, J.P.

    2003-01-01

    Using a new multi-section laser concept based on a coupled-cavity-injection-grating design, the material related intrinsic 3 dB modulation bandwidth can be enhanced up to 37 GHz for a 1.5 mm long device.......Using a new multi-section laser concept based on a coupled-cavity-injection-grating design, the material related intrinsic 3 dB modulation bandwidth can be enhanced up to 37 GHz for a 1.5 mm long device....

  20. Increasing the darkfield contrast-to-noise ratio using a deconvolution-based information retrieval algorithm in X-ray grating-based phase-contrast imaging.

    Science.gov (United States)

    Weber, Thomas; Pelzer, Georg; Bayer, Florian; Horn, Florian; Rieger, Jens; Ritter, André; Zang, Andrea; Durst, Jürgen; Anton, Gisela; Michel, Thilo

    2013-07-29

    A novel information retrieval algorithm for X-ray grating-based phase-contrast imaging based on the deconvolution of the object and the reference phase stepping curve (PSC) as proposed by Modregger et al. was investigated in this paper. We applied the method for the first time on data obtained with a polychromatic spectrum and compared the results to those, received by applying the commonly used method, based on a Fourier analysis. We confirmed the expectation, that both methods deliver the same results for the absorption and the differential phase image. For the darkfield image, a mean contrast-to-noise ratio (CNR) increase by a factor of 1.17 using the new method was found. Furthermore, the dose saving potential was estimated for the deconvolution method experimentally. It is found, that for the conventional method a dose which is higher by a factor of 1.66 is needed to obtain a similar CNR value compared to the novel method. A further analysis of the data revealed, that the improvement in CNR and dose efficiency is due to the superior background noise properties of the deconvolution method, but at the cost of comparability between measurements at different applied dose values, as the mean value becomes dependent on the photon statistics used.

  1. An optical fiber Bragg grating and piezoelectric ceramic voltage sensor

    Science.gov (United States)

    Yang, Qing; He, Yanxiao; Sun, Shangpeng; Luo, Mandan; Han, Rui

    2017-10-01

    Voltage measurement is essential in many fields like power grids, telecommunications, metallurgy, railways, and oil production. A voltage-sensing unit, consisting of fiber Bragg gratings (FBGs) and piezoelectric ceramics, based on which an optical over-voltage sensor was proposed and fabricated in this paper. No demodulation devices like spectrometer or Fabry-Perot filter were needed to gain the voltage signal, and a relatively large sensing frequency range was acquired in this paper; thus, the cost of the sensing system is more acceptable in engineering application. The voltage to be measured was directly applied to the piezoelectric ceramic, and deformation of the ceramics and the grating would be caused because of the inverse piezoelectric effect. With a reference grating, the output light intensity change will be caused by the FBG center wavelength change; thus, the relationship between the applied voltage and the output light intensity was established. Validation of the sensor was accomplished in the frequency range from 50 Hz to 20 kHz and switching impulse waves with a test platform; good linearity of the input-output characteristic was achieved. A temperature validation test was completed, showing that the sensor maintains good temperature stability. Experimental results show that the optical over-voltage sensor can be used for voltage monitoring, and if applied with a voltage divider, the sensor can be used to measure high voltage.

  2. An optical fiber Bragg grating and piezoelectric ceramic voltage sensor.

    Science.gov (United States)

    Yang, Qing; He, Yanxiao; Sun, Shangpeng; Luo, Mandan; Han, Rui

    2017-10-01

    Voltage measurement is essential in many fields like power grids, telecommunications, metallurgy, railways, and oil production. A voltage-sensing unit, consisting of fiber Bragg gratings (FBGs) and piezoelectric ceramics, based on which an optical over-voltage sensor was proposed and fabricated in this paper. No demodulation devices like spectrometer or Fabry-Perot filter were needed to gain the voltage signal, and a relatively large sensing frequency range was acquired in this paper; thus, the cost of the sensing system is more acceptable in engineering application. The voltage to be measured was directly applied to the piezoelectric ceramic, and deformation of the ceramics and the grating would be caused because of the inverse piezoelectric effect. With a reference grating, the output light intensity change will be caused by the FBG center wavelength change; thus, the relationship between the applied voltage and the output light intensity was established. Validation of the sensor was accomplished in the frequency range from 50 Hz to 20 kHz and switching impulse waves with a test platform; good linearity of the input-output characteristic was achieved. A temperature validation test was completed, showing that the sensor maintains good temperature stability. Experimental results show that the optical over-voltage sensor can be used for voltage monitoring, and if applied with a voltage divider, the sensor can be used to measure high voltage.

  3. Grating-based x-ray differential phase contrast imaging with twin peaks in phase-stepping curves—phase retrieval and dewrapping

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yi; Xie, Huiqiao; Tang, Xiangyang, E-mail: xiangyang.tang@emory.edu [Imaging and Medical Physics, Department of Radiology and Imaging Sciences, Emory University School of Medicine, 1701 Uppergate Dr., C-5018, Atlanta, Georgia 30322 (United States); Cai, Weixing [Department of Radiation Oncology, Brigham and Women’s Hospital Harvard Medical School, 75 Francis Street, Boston, Massachusetts 02115 (United States); Mao, Hui [Laboratory of Functional and Molecular Imaging and Nanomedicine, Department of Radiology and Imaging Sciences, Emory University School of Medicine, 1841 Clifton Road NE, Atlanta, Georgia 30329 (United States)

    2016-06-15

    Purpose: X-ray differential phase contrast CT implemented with Talbot interferometry employs phase-stepping to extract information of x-ray attenuation, phase shift, and small-angle scattering. Since inaccuracy may exist in the absorption grating G{sub 2} due to an imperfect fabrication, the effective period of G{sub 2} can be as large as twice the nominal period, leading to a phenomenon of twin peaks that differ remarkably in their heights. In this work, the authors investigate how to retrieve and dewrap the phase signal from the phase-stepping curve (PSC) with the feature of twin peaks for x-ray phase contrast imaging. Methods: Based on the paraxial Fresnel–Kirchhoff theory, the analytical formulae to characterize the phenomenon of twin peaks in the PSC are derived. Then an approach to dewrap the retrieved phase signal by jointly using the phases of the first- and second-order Fourier components is proposed. Through an experimental investigation using a prototype x-ray phase contrast imaging system implemented with Talbot interferometry, the authors evaluate and verify the derived analytic formulae and the proposed approach for phase retrieval and dewrapping. Results: According to theoretical analysis, the twin-peak phenomenon in PSC is a consequence of combined effects, including the inaccuracy in absorption grating G{sub 2}, mismatch between phase grating and x-ray source spectrum, and finite size of x-ray tube’s focal spot. The proposed approach is experimentally evaluated by scanning a phantom consisting of organic materials and a lab mouse. The preliminary data show that compared to scanning G{sub 2} over only one single nominal period and correcting the measured phase signal with an intuitive phase dewrapping method that is being used in the field, stepping G{sub 2} over twice its nominal period and dewrapping the measured phase signal with the proposed approach can significantly improve the quality of x-ray differential phase contrast imaging in both

  4. Magnesium-based methods, systems, and devices

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yufeng; Ban, Chunmei; Ruddy, Daniel; Parilla, Philip A.; Son, Seoung-Bum

    2017-12-12

    An aspect of the present invention is an electrical device, where the device includes a current collector and a porous active layer electrically connected to the current collector to form an electrode. The porous active layer includes MgB.sub.x particles, where x.gtoreq.1, mixed with a conductive additive and a binder additive to form empty interstitial spaces between the MgB.sub.x particles, the conductive additive, and the binder additive. The MgB.sub.x particles include a plurality of boron sheets of boron atoms covalently bound together, with a plurality of magnesium atoms reversibly intercalated between the boron sheets and ionically bound to the boron atoms.

  5. Plasmonically enhanced hot electron based photovoltaic device.

    Science.gov (United States)

    Atar, Fatih B; Battal, Enes; Aygun, Levent E; Daglar, Bihter; Bayindir, Mehmet; Okyay, Ali K

    2013-03-25

    Hot electron photovoltaics is emerging as a candidate for low cost and ultra thin solar cells. Plasmonic means can be utilized to significantly boost device efficiency. We separately form the tunneling metal-insulator-metal (MIM) junction for electron collection and the plasmon exciting MIM structure on top of each other, which provides high flexibility in plasmonic design and tunneling MIM design separately. We demonstrate close to one order of magnitude enhancement in the short circuit current at the resonance wavelengths.

  6. [Effectivity of an occlusion-supporting PC-based visual training programme by horizontal drifting sinus gratings in children with amblyopia].

    Science.gov (United States)

    Bau, V; Rose, K; Pollack, K; Spoerl, E; Pillunat, L E

    2012-10-01

    The studies of Kämpf et al. suggested an efficiency of a computer-based stimulation therapy by drifting sinus gratings in patients with anisometropic and/or strabismic amblyopia but provided no clear evidence. This is the first trial with amblyopic patients without previous treatment at the beginning of amblyopia therapy. A prospective, randomised, single-blinded, placebo-controlled study of n = 15 patients with anisometropic and/or strabismic amblyopia without previous treatment was performed. Age of the patients was between 4 and 10 years, mean 6.3 years (± 2.0), all after full correction of refraction errors and refractive adaptation. Stimulation therapy was performed 5 times a week over 4 weeks, respectively 2 × 20 min, a drifting sinus grating of constant spatial and temporal frequency was combined with computer games (n = 8). Control group had only computer games with a neutral background (n = 7). In both groups patching was only done in stimulation times. Stimulation and control group did not differ due to age, gender, and cause of amblyopie, baseline visual acuity, and time of wearing glasses. There was no significant difference in the development of visual acuity over the stimulation period between stimulation and control groups. Stimulation therapy with drifting sinus gratings did not improve the development of visual acuity in the first phase of amblyopia treatment combined with minimal occlusion therapy. Accordingly, the stimulation therapy is not adequate to replace sufficient occlusion therapy. Whether this therapy could support patching therapy and improve acuity development in later therapy phases cannot be assumed from this trial. Georg Thieme Verlag KG Stuttgart · New York.

  7. Thermal stress modification in regenerated fiber Bragg grating via manipulation of glass transition temperature based on CO₂-laser annealing.

    Science.gov (United States)

    Lai, Man-Hong; Lim, Kok-Sing; Gunawardena, Dinusha S; Yang, Hang-Zhou; Chong, Wu-Yi; Ahmad, Harith

    2015-03-01

    In this work, we have demonstrated thermal stress relaxation in regenerated fiber Bragg gratings (RFBGs) by using direct CO₂-laser annealing technique. After the isothermal annealing and slow cooling process, the Bragg wavelength of the RFBG has been red-shifted. This modification is reversible by re-annealing and rapid cooling. It is repeatable with different cooling process in the subsequent annealing treatments. This phenomenon can be attributed to the thermal stress modification in the fiber core by means of manipulation of glass transition temperature with different cooling rates. This finding in this investigation is important for accurate temperature measurement of RFBG in dynamic environment.

  8. Design of an optical temporal integrator based on a phase-shifted fiber Bragg grating in transmission.

    Science.gov (United States)

    Quoc Ngo, Nam

    2007-10-15

    We present a theoretical study of a new application of a simple pi-phase-shifted fiber Bragg grating (PSFBG) in transmission mode as a high-speed optical temporal integrator. The PSFBG consists of two concatenated identical uniform FBGs with a pi phase shift between them. When the reflectivities of the FBGs are extremely close to 100%, the transmissive PSFBG can perform the time integral of the complex envelope of an arbitrary input optical signal with high accuracy. As an example, the integrator is numerically shown to be able to convert an input Gaussian pulse into an optical step signal.

  9. Value-based procurement of medical devices: Application to devices for mechanical thrombectomy in ischemic stroke.

    Science.gov (United States)

    Trippoli, Sabrina; Caccese, Erminia; Marinai, Claudio; Messori, Andrea

    2018-03-01

    In the acute ischemic stroke, endovascular devices have shown promising clinical results and are also likely to represent value for money, as several modeling studies have shown. Pharmacoeconomic evaluations in this field, however, have little impact on the procurement of these devices. The present study explored how complex pharmacoeconomic models that evaluate effectiveness and cost can be incorporated into the in-hospital procurement of thrombectomy devices. As regards clinical modeling, we extracted outcomes at three months from randomized trials conducted for four thrombectomy devices, and we projected long-term results using standard Markov modeling. In estimating QALYs, the same model was run for the four devices. As regards economic modeling, we firstly estimated for each device the net monetary benefit (NMB) per patient (threshold = $60,000 per QALY); then, we simulated a competitive tender across the four products by determining the tender-based score (on a 0-to-100 scale). Prices of individual devices were obtained from manufacturers. Extensive sensitivity testing was applied to our analyses. For the four devices (Solitaire, Trevo, Penumbra, Solumbra), QALYs were 1.86, 1.52, 1,79, 1.35, NMB was $101,824, $83,546, $101,923, $69,440, and tender-based scores were 99.70, 43.43, 100, 0, respectively. Sensitivity analysis confirmed findings from base-case. Our results indicate that, in the field of thrombectomy devices, incorporating the typical tools of cost-effectiveness into the processes of tenders and procurement is feasible. Bridging the methodology of cost-effectiveness with the every-day practice of in-hospital procurement can contribute to maximizing the health returns that are generated by in-hospital expenditures for medical devices. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Highly air stable passivation of graphene based field effect devices.

    Science.gov (United States)

    Sagade, Abhay A; Neumaier, Daniel; Schall, Daniel; Otto, Martin; Pesquera, Amaia; Centeno, Alba; Elorza, Amaia Zurutuza; Kurz, Heinrich

    2015-02-28

    The sensitivity of graphene based devices to surface adsorbates and charge traps at the graphene/dielectric interface requires proper device passivation in order to operate them reproducibly under ambient conditions. Here we report on the use of atomic layer deposited aluminum oxide as passivation layer on graphene field effect devices (GFETs). We show that successful passivation produce hysteresis free DC characteristics, low doping level GFETs stable over weeks though operated and stored in ambient atmosphere. This is achieved by selecting proper seed layer prior to deposition of encapsulation layer. The passivated devices are also demonstrated to be robust towards the exposure to chemicals and heat treatments, typically used during device fabrication. Additionally, the passivation of high stability and reproducible characteristics is also shown for functional devices like integrated graphene based inverters.

  11. Silicon based light-emitting materials and devices

    International Nuclear Information System (INIS)

    Chen Weide

    1999-01-01

    Silicon based light-emitting materials and devices are the key to optoelectronic integration. Recently, there has been significant progress in materials engineering methods. The author reviews the latest developments in this area including erbium doped silicon, porous silicon, nanocrystalline silicon and Si/SiO 2 superlattice structures. The incorporation of these different materials into devices is described and future device prospects are assessed

  12. Fiber Bragg grating based spatially resolved characterization of flux-pinning induced strain of rectangular-shaped bulk YBCO samples

    International Nuclear Information System (INIS)

    Latka, Ines; Habisreuther, Tobias; Litzkendorf, Doris

    2011-01-01

    Highlights: → Fiber Bragg gratings (FBG) act as strain sensors, also at cryogenic temperatures. → FBGs are not sensitive to magnetic fields. → Local, shape dependent magnetostriction was detected on rectangular samples. → Magnetostrictive effects of the top surface and in a gap between two samples are different. - Abstract: We report on measurements of the spatially resolved characterization of flux-pinning induced strain of rectangular-shaped bulk YBCO samples. The spatially resolved strain measurements are accomplished by the use 2 fiber Bragg grating arrays, which are with an included angle of 45 o fixed to the surface. In this paper first attempts to confirm the shape distortions caused by the flux-pinning induced strain as predicted in will be presented. Two sample setups, a single bulk and a 'mirror' arrangement, will be compared. This mirror setup represents a model configuration for a measurement inside the superconductor, where demagnetization effects can be neglected and the magnetic field merely has a z-component.

  13. Mechanical design optimization of a single-axis MOEMS accelerometer based on a grating interferometry cavity for ultrahigh sensitivity

    Science.gov (United States)

    Lu, Qianbo; Bai, Jian; Wang, Kaiwei; Lou, Shuqi; Jiao, Xufen; Han, Dandan; Yang, Guoguang

    2016-08-01

    The ultrahigh static displacement-acceleration sensitivity of a mechanical sensing chip is essential primarily for an ultrasensitive accelerometer. In this paper, an optimal design to implement to a single-axis MOEMS accelerometer consisting of a grating interferometry cavity and a micromachined sensing chip is presented. The micromachined sensing chip is composed of a proof mass along with its mechanical cantilever suspension and substrate. The dimensional parameters of the sensing chip, including the length, width, thickness and position of the cantilevers are evaluated and optimized both analytically and by finite-element-method (FEM) simulation to yield an unprecedented acceleration-displacement sensitivity. Compared with one of the most sensitive single-axis MOEMS accelerometers reported in the literature, the optimal mechanical design can yield a profound sensitivity improvement with an equal footprint area, specifically, 200% improvement in displacement-acceleration sensitivity with moderate resonant frequency and dynamic range. The modified design was microfabricated, packaged with the grating interferometry cavity and tested. The experimental results demonstrate that the MOEMS accelerometer with modified design can achieve the acceleration-displacement sensitivity of about 150μm/g and acceleration sensitivity of greater than 1500V/g, which validates the effectiveness of the optimal design.

  14. Finite element analysis-based study of fiber Bragg grating sensor for cracks detection in reinforced concrete

    Science.gov (United States)

    Wang, Lili; Xin, Xiangjun; Song, Jun; Wang, Honggang; Sai, Yaozhang

    2018-02-01

    Fiber Bragg sensor is applied for detecting and monitoring the cracks that occur in the reinforced concrete. We use the three-dimensional finite element model to provide the three-axial stresses along the fiber Bragg sensor and then converted the stresses as a wavelength deformation of fiber Bragg grating (FBG) reflected spectrum. For the crack detection, an FBG sensor with 10-mm length is embedded in the reinforced concrete, and its reflection spectrum is measured after loading is applied to the concrete slab. As a result, the main peak wavelength and the ratio of the peak reflectivity to the maximal side-mode reflectivity of the optic-fiber grating represent the fracture severity. The fact that the sharp decreasing of the ratio of the peak reflectivity to the maximal side-mode reflectivity represents the early crack is confirmed by the theoretical calculation. The method can be used to detect the cracks in the reinforced concrete and give safety evaluation of large-scale infrastructure.

  15. Fibre Bragg Grating and Long Period Grating Sensors in Polymer Optical Fibres

    DEFF Research Database (Denmark)

    Bundalo, Ivan-Lazar

    mechanisms in polymer fibres using a CO2 laser. One is etching and the other one is perturbation of the microstructured region. After inscription of LPGs, the concept of a biocompatible distributed medical endoscope is presented, where an all-plastic LPG based device is produced. A transducer pod is made...... of applications and pushing the limits. The first part of the work focuses on the fabrication of FBGs in polymer optical fibres. FBGs are a periodic perturbation of the refractive index of the optical fibre core which act as a wavelength specific reflector. The fibres used are made of Polymethyl methacrylate....... In this system a high power CO2 laser is used for the inscription. An LPG is also a periodic perturbation of the guided core mode in fibre, but unlike FBG which reflects the core mode, the LPG couples the core mode to a cladding mode outside the core. We have shown that the LPG grating can be formed through two...

  16. Evaluation of polymer based third order nonlinear integrated optics devices

    NARCIS (Netherlands)

    Driessen, A.; Hoekstra, Hugo; Blom, F.C.; Horst, F.; Horst, F.; Krijnen, Gijsbertus J.M.; van Schoot, J.B.P.; van Schoot, J.B.P.; Lambeck, Paul; Popma, T.J.A.; Diemeer, Mart

    Nonlinear polymers are promising materials for high speed active integrated optics devices. In this paper we evaluate the perspectives polymer based nonlinear optical devices can offer. Special attention is directed to the materials aspects. In our experimental work we applied mainly Akzo Nobel DANS

  17. Ambient Sound-Based Collaborative Localization of Indeterministic Devices

    NARCIS (Netherlands)

    Kamminga, Jacob Wilhelm; Le Viet Duc, L Duc; Havinga, Paul J.M.

    2016-01-01

    Localization is essential in wireless sensor networks. To our knowledge, no prior work has utilized low-cost devices for collaborative localization based on only ambient sound, without the support of local infrastructure. The reason may be the fact that most low-cost devices are indeterministic and

  18. A microfluidic device based on an evaporation-driven micropump

    NARCIS (Netherlands)

    Nie, C.; Frijns, A.J.H.; Mandamparambil, R.; Toonder, J.M.J. den

    2015-01-01

    In this paper we introduce a microfluidic device ultimately to be applied as a wearable sweat sensor. We show proof-of-principle of the microfluidic functions of the device, namely fluid collection and continuous fluid flow pumping. A filter-paper based layer, that eventually will form the interface

  19. Secure-Network-Coding-Based File Sharing via Device-to-Device Communication

    OpenAIRE

    Wang, Lei; Wang, Qing

    2017-01-01

    In order to increase the efficiency and security of file sharing in the next-generation networks, this paper proposes a large scale file sharing scheme based on secure network coding via device-to-device (D2D) communication. In our scheme, when a user needs to share data with others in the same area, the source node and all the intermediate nodes need to perform secure network coding operation before forwarding the received data. This process continues until all the mobile devices in the netw...

  20. Analysis for reflection peaks of multiple-phase-shift based sampled fiber Bragg gratings and application in high channel-count filter design.

    Science.gov (United States)

    Wen, Kun Hua; Yan, Lian Shan; Pan, Wei; Luo, Bin; Zou, Xi Hua; Ye, Jia; Ma, Ya Nan

    2009-10-10

    An analytical expression for calculating the reflection-peak wavelengths (RPWs) of a uniform sampled fiber Bragg grating (SFBG) with the multiple-phase-shift (MPS) technique is derived through Fourier transform of the index modulation. The new expression can accurately depict the RPWs incorporating various parameters such as the duty cycle and the DC index change. The effectiveness of the derived expression is further confirmed by comparing the RPWs estimated from the expression with the simulated reflective spectra using the piecewise uniform method. And the reflective spectrum has been well optimized by introducing the Gaussian apodization function to suppress the sidelobes without any wavelength shift on the RPWs. Then, a high-channel-count comb filter based on MPS is proposed by cascading two or more SFBGs with different Bragg periods but with the same RPWs. Noticeably, the RPWs of the new structured SFBG can also be accurately calculated through the expression. Furthermore, the number of spectral channels can be controlled by choosing gratings with specified difference Bragg periods.

  1. Polymeric flat focal field arrayed waveguide grating using electron-beam direct writing

    Science.gov (United States)

    Lu, Si; Yan, Yingbai; Jin, Guofan; Wong, W. H.; Pun, E. Y. B.

    2004-06-01

    A four-channel 400-GHz spacing flat focal field arrayed waveguide grating (AWG) demultiplexer is designed based on polymeric optical waveguide. The waveguide core-layer material is a newly developed negative tone epoxy Novolak resin (ENR) polymer with ultravoilet (UV) cured resin Norland optical adhesive 61 (NOA61) as the cladding layer. The device is fabricated using electron-beam direct writing, which has less processing steps than the reported polymeric AWGs. The experimental result is presented.

  2. Performance of the diffraction grating on a bank note: the experience with the Australian Commemorative note

    Science.gov (United States)

    Hardwick, Bruce A.

    1990-04-01

    In January 1988, we at the Note Printing Branch first released to the Reserve Bank a polymer based banknote containing an Optically Variable Device (OVD), a diffraction grating. This banknote was the culmination of many years of Research and Development effort, and represented a very significant departure from conventional banknote technology in many ways. It was a test bed. We are very pleased with its performance.

  3. Implementation of all-optical reversible logic gate based on holographic laser induced grating using azo-dye doped polymers

    Science.gov (United States)

    Forsati, Rana; Valipour Ebrahimi, Sara; Navi, Keivan; Mohajerani, Ezeddin; Jashnsaz, Hossein

    2013-02-01

    Increasing demand for power reduction in computer systems has led to new trends in computations and computer design including reversible computing. Its main aim is to eliminate power dissipation in logical elements but can have some other advantages such as data security and error prevention. Because of interesting properties of reversible computing, implementing computing devices with reversible manner is the only way to make the reversible computing a reality. In recent years, reversible logic has turned out to be a promising computing paradigm having application in CMOS, nanotechnology, quantum computing and optical computing. In this paper, we propose and realize a novel implementation of Toffoli gate in all-optical domain. We have explained its principle of operations and described an actual experimental implementation. The all-optical reversible gate presented in this paper will be useful in different applications such as arithmetic and logical operations in the domain of reversible logic-based computing.

  4. Product-based Safety Certification for Medical Devices Embedded Software.

    Science.gov (United States)

    Neto, José Augusto; Figueiredo Damásio, Jemerson; Monthaler, Paul; Morais, Misael

    2015-01-01

    Worldwide medical device embedded software certification practices are currently focused on manufacturing best practices. In Brazil, the national regulatory agency does not hold a local certification process for software-intensive medical devices and admits international certification (e.g. FDA and CE) from local and international industry to operate in the Brazilian health care market. We present here a product-based certification process as a candidate process to support the Brazilian regulatory agency ANVISA in medical device software regulation. Center of Strategic Technology for Healthcare (NUTES) medical device embedded software certification is based on a solid safety quality model and has been tested with reasonable success against the Class I risk device Generic Infusion Pump (GIP).

  5. A Fiber Bragg Grating Sensor Interrogation System Based on a Linearly Wavelength-Swept Thermo-Optic Laser Chip

    Science.gov (United States)

    Lee, Hyung-Seok; Lee, Hwi Don; Kim, Hyo Jin; Cho, Jae Du; Jeong, Myung Yung; Kim, Chang-Seok

    2014-01-01

    A linearized wavelength-swept thermo-optic laser chip was applied to demonstrate a fiber Bragg grating (FBG) sensor interrogation system. A broad tuning range of 11.8 nm was periodically obtained from the laser chip for a sweep rate of 16 Hz. To measure the linear time response of the reflection signal from the FBG sensor, a programmed driving signal was directly applied to the wavelength-swept laser chip. The linear wavelength response of the applied strain was clearly extracted with an R-squared value of 0.99994. To test the feasibility of the system for dynamic measurements, the dynamic strain was successfully interrogated with a repetition rate of 0.2 Hz by using this FBG sensor interrogation system. PMID:25177803

  6. Simulation and experimental study of a three-axis fiber Bragg grating accelerometer based on the pull-push mechanism

    Science.gov (United States)

    Jiang, Qi; Yang, Meng

    2013-11-01

    A three-axis fiber Bragg grating accelerometer, which has uniform sensitivities to three axes, has been developed for seismic application. This paper presents the design, simulation and calibration of the three-axis accelerometer. A series of experiments were performed to measure harmonic vibration and shock vibration. The precise acceleration was measured by a PZT accelerometer which provided high sensitivity. The fully described dynamic sensitivity of three-axis accelerometers represented by a 3-by-3 matrix is given. The results indicate that the accelerometer has a sensitivity of 0.068 V g-1 in a measured full scale of ±2.5 m s-2. The cross-axis sensitivity was measured as -75.5 dB, -75.5 dB and -78.2 dB, respectively.

  7. Tunable superstructure fiber Bragg grating with chirp-distribution modulation based on the effect of external stress.

    Science.gov (United States)

    Huang, Yize; Li, Yi; Zhu, Huiqun; Tong, Guoxiang; Fang, Baoying; Li, Liu; Shen, Yujian; Zheng, Qiuxin; Liang, Qian; Yan, Meng; Wang, Feng; Qin, Yuan; Ding, Jie; Wang, Xiaohua

    2012-09-15

    We report an external stress modulation method for producing a superstructure fiber Bragg grating (FBG) with approximate cascaded resonant cavities composed of different index chirp distributions. The 15 mm uncoated apodized uniform-period FBG is pressed by the vertical stress from the upper 11 pieces of the pattern plate controlled by a piezoelectric ceramic actuator. The piece length is 1 mm, and the interval of the adjacent pieces is 0.4 mm. The reflectivity of the modulated FBG gradually shows six obvious multichannel 75%-85% reflection peaks with the increase of the vertical stress of each pattern-plate piece from 0 to 30 N. The channel spacing is steady at about 10 GHz for a C-band wavelength division multiplexing system.

  8. Simulation and experimental study of a three-axis fiber Bragg grating accelerometer based on the pull–push mechanism

    International Nuclear Information System (INIS)

    Jiang, Qi; Yang, Meng

    2013-01-01

    A three-axis fiber Bragg grating accelerometer, which has uniform sensitivities to three axes, has been developed for seismic application. This paper presents the design, simulation and calibration of the three-axis accelerometer. A series of experiments were performed to measure harmonic vibration and shock vibration. The precise acceleration was measured by a PZT accelerometer which provided high sensitivity. The fully described dynamic sensitivity of three-axis accelerometers represented by a 3-by-3 matrix is given. The results indicate that the accelerometer has a sensitivity of 0.068 V g −1 in a measured full scale of ±2.5 m s −2 . The cross-axis sensitivity was measured as −75.5 dB, −75.5 dB and −78.2 dB, respectively. (paper)

  9. Energy-Based Devices in Treatment of Acne Vulgaris.

    Science.gov (United States)

    Handler, Marc Z; Bloom, Bradley S; Goldberg, David J

    2016-05-01

    Acne vulgaris is a chronic dermatologic complaint with a multifactorial cause. Traditionally, antibiotics and retinoids have been used to manage the condition; patient compliance has been an ongoing issue. A variety of energy-based devices have been reported to be effective in the treatment of acne vulgaris. To review and summarize the current literature specific to treatment of acne vulgaris with energy-based devices. A review of the current literature of energy-based devices used for the treatment of acne vulgaris. Although limited randomized controlled trials for the treatment of acne have been performed, significant clinical improvement of acne vulgaris, especially of inflammatory lesions, has been demonstrated with a variety of energy-based devices. Newer approaches may lead to even better results.

  10. Negative luminescence and devices based on this phenomenon

    International Nuclear Information System (INIS)

    Ivanov-Omskii, V. I.; Matveev, B. A.

    2007-01-01

    Recent publications concerned with infrared emitters whose electrical modulation results in absorption of radiation detected as negative luminescence are reviewed. The main properties of the devices based on this phenomenon are analyzed

  11. Negative luminescence and devices based on this phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov-Omskii, V I; Matveev, B. A. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)], E-mail: bmat@iropt3.ioffe.rssi.ru

    2007-03-15

    Recent publications concerned with infrared emitters whose electrical modulation results in absorption of radiation detected as negative luminescence are reviewed. The main properties of the devices based on this phenomenon are analyzed.

  12. Resonant quantum efficiency enhancement of midwave infrared nBn photodetectors using one-dimensional plasmonic gratings

    International Nuclear Information System (INIS)

    Nolde, Jill A.; Kim, Chul Soo; Jackson, Eric M.; Ellis, Chase T.; Abell, Joshua; Glembocki, Orest J.; Canedy, Chadwick L.; Tischler, Joseph G.; Vurgaftman, Igor; Meyer, Jerry R.; Aifer, Edward H.; Kim, Mijin

    2015-01-01

    We demonstrate up to 39% resonant enhancement of the quantum efficiency (QE) of a low dark current nBn midwave infrared photodetector with a 0.5 μm InAsSb absorber layer. The enhancement was achieved by using a 1D plasmonic grating to couple incident light into plasmon modes propagating in the plane of the device. The plasmonic grating is composed of stripes of deposited amorphous germanium overlaid with gold. Devices with and without gratings were processed side-by-side for comparison of their QEs and dark currents. The peak external QE for a grating device was 29% compared to 22% for a mirror device when the illumination was polarized perpendicularly to the grating lines. Additional experiments determined the grating coupling efficiency by measuring the reflectance of analogous gratings deposited on bare GaSb substrates

  13. Remote media vision-based computer input device

    Science.gov (United States)

    Arabnia, Hamid R.; Chen, Ching-Yi

    1991-11-01

    In this paper, we introduce a vision-based computer input device which has been built at the University of Georgia. The user of this system gives commands to the computer without touching any physical device. The system receives input through a CCD camera; it is PC- based and is built on top of the DOS operating system. The major components of the input device are: a monitor, an image capturing board, a CCD camera, and some software (developed by use). These are interfaced with a standard PC running under the DOS operating system.

  14. A quantum computer based on recombination processes in microelectronic devices

    International Nuclear Information System (INIS)

    Theodoropoulos, K; Ntalaperas, D; Petras, I; Konofaos, N

    2005-01-01

    In this paper a quantum computer based on the recombination processes happening in semiconductor devices is presented. A 'data element' and a 'computational element' are derived based on Schokley-Read-Hall statistics and they can later be used to manifest a simple and known quantum computing process. Such a paradigm is shown by the application of the proposed computer onto a well known physical system involving traps in semiconductor devices

  15. 2-D tiles declustering method based on virtual devices

    Science.gov (United States)

    Li, Zhongmin; Gao, Lu

    2009-10-01

    Generally, 2-D spatial data are divided as a series of tiles according to the plane grid. To satisfy the effect of vision, the tiles in the query window including the view point would be displayed quickly at the screen. Aiming at the performance difference of real storage devices, we propose a 2-D tiles declustering method based on virtual device. Firstly, we construct a group of virtual devices which have same storage performance and non-limited capacity, then distribute the tiles into M virtual devices according to the query window of 2-D tiles. Secondly, we equably map the tiles in M virtual devices into M equidistant intervals in [0, 1) using pseudo-random number generator. Finally, we devide [0, 1) into M intervals according to the tiles distribution percentage of every real storage device, and distribute the tiles in each interval in the corresponding real storage device. We have designed and realized a prototype GlobeSIGht, and give some related test results. The results show that the average response time of each tile in the query window including the view point using 2-D tiles declustering method based on virtual device is more efficient than using other methods.

  16. A Flexible Microcontroller-Based Data Acquisition Device

    Directory of Open Access Journals (Sweden)

    Darko Hercog

    2014-06-01

    Full Text Available This paper presents a low-cost microcontroller-based data acquisition device. The key component of the presented solution is a configurable microcontroller-based device with an integrated USB transceiver and a 12-bit analogue-to-digital converter (ADC. The presented embedded DAQ device contains a preloaded program (firmware that enables easy acquisition and generation of analogue and digital signals and data transfer between the device and the application running on a PC via USB bus. This device has been developed as a USB human interface device (HID. This USB class is natively supported by most of the operating systems and therefore any installation of additional USB drivers is unnecessary. The input/output peripheral of the presented device is not static but rather flexible, and could be easily configured to customised needs without changing the firmware. When using the developed configuration utility, a majority of chip pins can be configured as analogue input, digital input/output, PWM output or one of the SPI lines. In addition, LabVIEW drivers have been developed for this device. When using the developed drivers, data acquisition and signal processing algorithms as well as graphical user interface (GUI, can easily be developed using a well-known, industry proven, block oriented LabVIEW programming environment.

  17. A flexible microcontroller-based data acquisition device.

    Science.gov (United States)

    Hercog, Darko; Gergič, Bojan

    2014-06-02

    This paper presents a low-cost microcontroller-based data acquisition device. The key component of the presented solution is a configurable microcontroller-based device with an integrated USB transceiver and a 12-bit analogue-to-digital converter (ADC). The presented embedded DAQ device contains a preloaded program (firmware) that enables easy acquisition and generation of analogue and digital signals and data transfer between the device and the application running on a PC via USB bus. This device has been developed as a USB human interface device (HID). This USB class is natively supported by most of the operating systems and therefore any installation of additional USB drivers is unnecessary. The input/output peripheral of the presented device is not static but rather flexible, and could be easily configured to customised needs without changing the firmware. When using the developed configuration utility, a majority of chip pins can be configured as analogue input, digital input/output, PWM output or one of the SPI lines. In addition, LabVIEW drivers have been developed for this device. When using the developed drivers, data acquisition and signal processing algorithms as well as graphical user interface (GUI), can easily be developed using a well-known, industry proven, block oriented LabVIEW programming environment.

  18. Theoretical Investigation of Subwavelength Gratings and Vertical Cavity Lasers Employing Grating Structures

    DEFF Research Database (Denmark)

    Taghizadeh, Alireza

    This thesis deals with theoretical investigations of a newly proposed grating structure, referred to as hybrid grating (HG) as well as vertical cavity lasers based on the grating reflectors. The HG consists of a near-subwavelength grating layer and an unpatterned high-refractive-index cap layer...... directions, which is analogous to electronic quantum wells in conduction or valence bands. Several interesting configurations of heterostructures have been investigated and their potential in fundamental physics study and applications are discussed. For numerical and theoretical studies, a three...... feasibility than the HCG-based ones. Furthermore, the concept of cavity dispersion in vertical cavities is introduced and its importance in the modal properties is numerically investigated. The dispersion curvature of a cavity mode is interpreted as the effective photon mass of the cavity mode. In a vertical...

  19. Switchable Bragg gratings

    DEFF Research Database (Denmark)

    Marckmann, Carl Johan

    2003-01-01

    Research Center (MIC) at the Technical University of Denmark. The Bragg gratings were fabricated at COM using UV irradiation of the planar waveguides using the phase mask method. The induction of a frozen-in DC electric field into the samples was performed by thermal poling of the Bragg gratings...... layers, it becam possible to investigate the symmetry properties of the third-order nonlinearities. Contrary to the expectations for an amorphous material, the measurements indicated an almost polarization independent third-order nonlinearity - the most probable explanation being electrostriction......The subject of this ph.d. thesis was the development of an electrically switchable Bragg grating made in an optical waveguide using thermal poling to be applied within optical telecommunication systems. The planar waveguides used in this thesis were fabricated at the Micro- and Nanotechnology...

  20. Innovative energy absorbing devices based on composite tubes

    Science.gov (United States)

    Tiwari, Chandrashekhar

    Analytical and experimental study of innovative load limiting and energy absorbing devices are presented here. The devices are based on composite tubes and can be categorized in to two groups based upon the energy absorbing mechanisms exhibited by them, namely: foam crushing and foam fracturing. The device based on foam crushing as the energy absorbing mechanism is composed of light weight elastic-plastic foam filling inside an angle ply composite tube. The tube is tailored to have a high Poisson’s ratio (>20). Upon being loaded the device experiences large transverse contraction resulting in rapid decrease in diameter. At a certain axial load the foam core begins to crush and energy is dissipated. This device is termed as crush tube device. The device based upon foam shear fracture as the energy absorbing mechanism involves an elastic-plastic core foam in annulus of two concentric extension-twist coupled composite tubes with opposite angles of fibers. The core foam is bonded to the inner and outer tube walls. Upon being loaded axially, the tubes twist in opposite directions and fracture the core foam in out of plane shear and thus dissipate the energy stored. The device is termed as sandwich core device (SCD). The devices exhibit variations in force-displacement characteristics with changes in design and material parameters, resulting in wide range of energy absorption capabilities. A flexible matrix composite system was selected, which was composed of high stiffness carbon fibers as reinforcements in relatively low stiffness polyurethane matrix, based upon large strain to failure capabilities and large beneficial elastic couplings. Linear and non-linear analytical models were developed encapsulating large deformation theory of the laminated composite shells (using non-linear strain energy formulation) to the fracture mechanics of core foam and elastic-plastic deformation theory of the foam filling. The non-linear model is capable of including material and

  1. Packaged mode multiplexer based on silicon photonics

    NARCIS (Netherlands)

    Chen, H.; Koonen, A.M.J.; Snyder, B.; Raz, O.; Boom, van den H.P.A.; Chen, X.

    2012-01-01

    A silicon photonics based mode multiplexer is proposed. Four chirped grating couplers structure can support all 6 channels in a two-mode fiber and realize LP01 and LP11 mode selective exciting. The packaged device is tested.

  2. Grateful Med: getting started.

    Science.gov (United States)

    Shearer, B; McCann, L; Crump, W J

    1990-01-01

    When a local medical library is not available, it is often necessary for physicians to discover alternate ways to receive medical information. Rural physicians, particularly, can make use of a computer program called Grateful Med that provides access to the same literature available to physicians in large cities. This program permits the user to perform database searches on the National Library of Medicine database (MEDLINE), corresponding to the primary index to medical literature, Index Medicus. In this article, we give the procedure for procuring a National Library of Medicine password and for making efficient use of the Grateful Med program.

  3. Nanotube devices based crossbar architecture: toward neuromorphic computing

    International Nuclear Information System (INIS)

    Zhao, W S; Gamrat, C; Agnus, G; Derycke, V; Filoramo, A; Bourgoin, J-P

    2010-01-01

    Nanoscale devices such as carbon nanotube and nanowires based transistors, memristors and molecular devices are expected to play an important role in the development of new computing architectures. While their size represents a decisive advantage in terms of integration density, it also raises the critical question of how to efficiently address large numbers of densely integrated nanodevices without the need for complex multi-layer interconnection topologies similar to those used in CMOS technology. Two-terminal programmable devices in crossbar geometry seem particularly attractive, but suffer from severe addressing difficulties due to cross-talk, which implies complex programming procedures. Three-terminal devices can be easily addressed individually, but with limited gain in terms of interconnect integration. We show how optically gated carbon nanotube devices enable efficient individual addressing when arranged in a crossbar geometry with shared gate electrodes. This topology is particularly well suited for parallel programming or learning in the context of neuromorphic computing architectures.

  4. Substrate structures for InP-based devices

    International Nuclear Information System (INIS)

    Wanlass, M.W.; Sheldon, P.

    1990-01-01

    A substrate structure for an InP-based semiconductor device having an InP based film is described. The substrate structure includes a substrate region having a lightweight bulk substrate and an upper GaAs layer. An interconnecting region is disposed between the substrate region and the InP-based device. The interconnecting region includes a compositionally graded intermediate layer substantially lattice-matched at the opposite end to the InP=based film. The interconnecting region further includes a dislocation mechanism disposed between the GaAs layer and the InP-based film in cooperation with the graded intermediate layer, the buffer mechanism blocking and inhibiting propagation of threading dislocations between the substrate region, and the InP-based device

  5. Birefringence Bragg Binary (3B) grating, quasi-Bragg grating and immersion gratings

    Science.gov (United States)

    Ebizuka, Noboru; Morita, Shin-ya; Yamagata, Yutaka; Sasaki, Minoru; Bianco, Andorea; Tanabe, Ayano; Hashimoto, Nobuyuki; Hirahara, Yasuhiro; Aoki, Wako

    2014-07-01

    A volume phase holographic (VPH) grating achieves high angular dispersion and very high diffraction efficiency for the first diffraction order and for S or P polarization. However the VPH grating could not achieve high diffraction efficiency for non-polarized light at a large diffraction angle because properties of diffraction efficiencies for S and P polarizations are different. Furthermore diffraction efficiency of the VPH grating extinguishes toward a higher diffraction order. A birefringence binary Bragg (3B) grating is a thick transmission grating with optically anisotropic material such as lithium niobate or liquid crystal. The 3B grating achieves diffraction efficiency up to 100% for non-polarized light by tuning of refractive indices for S and P polarizations, even in higher diffraction orders. We fabricated 3B grating with liquid crystal and evaluated the performance of the liquid crystal grating. A quasi-Bragg (QB) grating, which consists long rectangle mirrors aligned in parallel precisely such as a window shade, also achieves high diffraction efficiency toward higher orders. We fabricated QB grating by laminating of silica glass substrates and glued by pressure fusion of gold films. A quasi-Bragg immersion (QBI) grating has smooth mirror hypotenuse and reflector array inside the hypotenuse, instead of step-like grooves of a conventional immersion grating. An incident beam of the QBI grating reflects obliquely at a reflector, then reflects vertically at the mirror surface and reflects again at the same reflector. We are going to fabricate QBI gratings by laminating of mirror plates as similar to fabrication of the QB grating. We will also fabricate silicon and germanium immersion gratings with conventional step-like grooves by means of the latest diamond machining methods. We introduce characteristics and performance of these gratings.

  6. Medical Device Integration Model Based on the Internet of Things

    Science.gov (United States)

    Hao, Aiyu; Wang, Ling

    2015-01-01

    At present, hospitals in our country have basically established the HIS system, which manages registration, treatment, and charge, among many others, of patients. During treatment, patients need to use medical devices repeatedly to acquire all sorts of inspection data. Currently, the output data of the medical devices are often manually input into information system, which is easy to get wrong or easy to cause mismatches between inspection reports and patients. For some small hospitals of which information construction is still relatively weak, the information generated by the devices is still presented in the form of paper reports. When doctors or patients want to have access to the data at a given time again, they can only look at the paper files. Data integration between medical devices has long been a difficult problem for the medical information system, because the data from medical devices are lack of mandatory unified global standards and have outstanding heterogeneity of devices. In order to protect their own interests, manufacturers use special protocols, etc., thus causing medical decices to still be the "lonely island" of hospital information system. Besides, unfocused application of the data will lead to failure to achieve a reasonable distribution of medical resources. With the deepening of IT construction in hospitals, medical information systems will be bound to develop towards mobile applications, intelligent analysis, and interconnection and interworking, on the premise that there is an effective medical device integration (MDI) technology. To this end, this paper presents a MDI model based on the Internet of Things (IoT). Through abstract classification, this model is able to extract the common characteristics of the devices, resolve the heterogeneous differences between them, and employ a unified protocol to integrate data between devices. And by the IoT technology, it realizes interconnection network of devices and conducts associate matching

  7. Electro-optic diffraction grating tuned laser

    International Nuclear Information System (INIS)

    Hughes, R.S.

    1975-01-01

    An electro-optic diffraction grating tuned laser comprising a laser medium, output mirror, retro-reflective grating and an electro-optic diffraction grating beam deflector positioned between the laser medium and the reflective diffraction grating is described. An optional angle multiplier may be used between the electro-optic diffraction grating and the reflective grating. (auth)

  8. High-accuracy measurement and compensation of grating line-density error in a tiled-grating compressor

    Science.gov (United States)

    Zhao, Dan; Wang, Xiao; Mu, Jie; Li, Zhilin; Zuo, Yanlei; Zhou, Song; Zhou, Kainan; Zeng, Xiaoming; Su, Jingqin; Zhu, Qihua

    2017-02-01

    The grating tiling technology is one of the most effective means to increase the aperture of the gratings. The line-density error (LDE) between sub-gratings will degrade the performance of the tiling gratings, high accuracy measurement and compensation of the LDE are of significance to improve the output pulses characteristics of the tiled-grating compressor. In this paper, the influence of LDE on the output pulses of the tiled-grating compressor is quantitatively analyzed by means of numerical simulation, the output beams drift and output pulses broadening resulting from the LDE are presented. Based on the numerical results we propose a compensation method to reduce the degradations of the tiled grating compressor by applying angular tilt error and longitudinal piston error at the same time. Moreover, a monitoring system is setup to measure the LDE between sub-gratings accurately and the dispersion variation due to the LDE is also demonstrated based on spatial-spectral interference. In this way, we can realize high-accuracy measurement and compensation of the LDE, and this would provide an efficient way to guide the adjustment of the tiling gratings.

  9. A Rhythm-Based Authentication Scheme for Smart Media Devices

    Directory of Open Access Journals (Sweden)

    Jae Dong Lee

    2014-01-01

    Full Text Available In recent years, ubiquitous computing has been rapidly emerged in our lives and extensive studies have been conducted in a variety of areas related to smart devices, such as tablets, smartphones, smart TVs, smart refrigerators, and smart media devices, as a measure for realizing the ubiquitous computing. In particular, smartphones have significantly evolved from the traditional feature phones. Increasingly higher-end smartphone models that can perform a range of functions are now available. Smart devices have become widely popular since they provide high efficiency and great convenience for not only private daily activities but also business endeavors. Rapid advancements have been achieved in smart device technologies to improve the end users’ convenience. Consequently, many people increasingly rely on smart devices to store their valuable and important data. With this increasing dependence, an important aspect that must be addressed is security issues. Leaking of private information or sensitive business data due to loss or theft of smart devices could result in exorbitant damage. To mitigate these security threats, basic embedded locking features are provided in smart devices. However, these locking features are vulnerable. In this paper, an original security-locking scheme using a rhythm-based locking system (RLS is proposed to overcome the existing security problems of smart devices. RLS is a user-authenticated system that addresses vulnerability issues in the existing locking features and provides secure confidentiality in addition to convenience.

  10. A rhythm-based authentication scheme for smart media devices.

    Science.gov (United States)

    Lee, Jae Dong; Jeong, Young-Sik; Park, Jong Hyuk

    2014-01-01

    In recent years, ubiquitous computing has been rapidly emerged in our lives and extensive studies have been conducted in a variety of areas related to smart devices, such as tablets, smartphones, smart TVs, smart refrigerators, and smart media devices, as a measure for realizing the ubiquitous computing. In particular, smartphones have significantly evolved from the traditional feature phones. Increasingly higher-end smartphone models that can perform a range of functions are now available. Smart devices have become widely popular since they provide high efficiency and great convenience for not only private daily activities but also business endeavors. Rapid advancements have been achieved in smart device technologies to improve the end users' convenience. Consequently, many people increasingly rely on smart devices to store their valuable and important data. With this increasing dependence, an important aspect that must be addressed is security issues. Leaking of private information or sensitive business data due to loss or theft of smart devices could result in exorbitant damage. To mitigate these security threats, basic embedded locking features are provided in smart devices. However, these locking features are vulnerable. In this paper, an original security-locking scheme using a rhythm-based locking system (RLS) is proposed to overcome the existing security problems of smart devices. RLS is a user-authenticated system that addresses vulnerability issues in the existing locking features and provides secure confidentiality in addition to convenience.

  11. Secure-Network-Coding-Based File Sharing via Device-to-Device Communication

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2017-01-01

    Full Text Available In order to increase the efficiency and security of file sharing in the next-generation networks, this paper proposes a large scale file sharing scheme based on secure network coding via device-to-device (D2D communication. In our scheme, when a user needs to share data with others in the same area, the source node and all the intermediate nodes need to perform secure network coding operation before forwarding the received data. This process continues until all the mobile devices in the networks successfully recover the original file. The experimental results show that secure network coding is very feasible and suitable for such file sharing. Moreover, the sharing efficiency and security outperform traditional replication-based sharing scheme.

  12. [INVITED] Tilted fiber grating mechanical and biochemical sensors

    Science.gov (United States)

    Guo, Tuan; Liu, Fu; Guan, Bai-Ou; Albert, Jacques

    2016-04-01

    The tilted fiber Bragg grating (TFBG) is a new kind of fiber-optic sensor that possesses all the advantages of well-established Bragg grating technology in addition to being able to excite cladding modes resonantly. This device opens up a multitude of opportunities for single-point sensing in hard-to-reach spaces with very controllable cross-sensitivities, absolute and relative measurements of various parameters, and an extreme sensitivity to materials external to the fiber without requiring the fiber to be etched or tapered. Over the past five years, our research group has been developing multimodal fiber-optic sensors based on TFBG in various shapes and forms, always keeping the device itself simple to fabricate and compatible with low-cost manufacturing. This paper presents a brief review of the principle, fabrication, characterization, and implementation of TFBGs, followed by our progress in TFBG sensors for mechanical and biochemical applications, including one-dimensional TFBG vibroscopes, accelerometers and micro-displacement sensors; two-dimensional TFBG vector vibroscopes and vector rotation sensors; reflective TFBG refractometers with in-fiber and fiber-to-fiber configurations; polarimetric and plasmonic TFBG biochemical sensors for in-situ detection of cell, protein and glucose.

  13. Mobile device-based optical instruments for agriculture

    Science.gov (United States)

    Sumriddetchkajorn, Sarun

    2013-05-01

    Realizing that a current smart-mobile device such as a cell phone and a tablet can be considered as a pocket-size computer embedded with a built-in digital camera, this paper reviews and demonstrates on how a mobile device can be specifically functioned as a portable optical instrument for agricultural applications. The paper highlights several mobile device-based optical instruments designed for searching small pests, measuring illumination level, analyzing spectrum of light, identifying nitrogen status in the rice field, estimating chlorine in water, and determining ripeness level of the fruit. They are suitable for individual use as well as for small and medium enterprises.

  14. Electrochemical model of the polyaniline based organic memristive device

    International Nuclear Information System (INIS)

    Demin, V. A.; Erokhin, V. V.; Kashkarov, P. K.; Kovalchuk, M. V.

    2014-01-01

    The electrochemical organic memristive device with polyaniline active layer is a stand-alone device designed and realized for reproduction of some synapse properties in the innovative electronic circuits, including the neuromorphic networks capable for learning. In this work, a new theoretical model of the polyaniline memristive is presented. The developed model of organic memristive functioning was based on the detailed consideration of possible electrochemical processes occuring in the active zone of this device. Results of the calculation have demonstrated not only the qualitative explanation of the characteristics observed in the experiment but also the quantitative similarities of the resultant current values. It is shown how the memristive could behave at zero potential difference relative to the reference electrode. This improved model can establish a basis for the design and prediction of properties of more complicated circuits and systems (including stochastic ones) based on the organic memristive devices

  15. Bragg grating rogue wave

    Energy Technology Data Exchange (ETDEWEB)

    Degasperis, Antonio [Dipartimento di Fisica, “Sapienza” Università di Roma, P.le A. Moro 2, 00185 Roma (Italy); Wabnitz, Stefan, E-mail: stefan.wabnitz@unibs.it [Dipartimento di Ingegneria dell' Informazione, Università degli Studi di Brescia and INO-CNR, via Branze 38, 25123 Brescia (Italy); Aceves, Alejandro B. [Southern Methodist University, Dallas (United States)

    2015-06-12

    We derive the rogue wave solution of the classical massive Thirring model, that describes nonlinear optical pulse propagation in Bragg gratings. Combining electromagnetically induced transparency with Bragg scattering four-wave mixing may lead to extreme waves at extremely low powers.

  16. Silicon graphene Bragg gratings.

    Science.gov (United States)

    Capmany, José; Domenech, David; Muñoz, Pascual

    2014-03-10

    We propose the use of interleaved graphene sections on top of a silicon waveguide to implement tunable Bragg gratings. The filter central wavelength and bandwidth can be controlled changing the chemical potential of the graphene sections. Apodization techniques are also presented.

  17. Surface wave photonic device based on porous silicon multilayers

    International Nuclear Information System (INIS)

    Guillermain, E.; Lysenko, V.; Benyattou, T.

    2006-01-01

    Porous silicon is widely studied in the field of photonics due to its interesting optical properties. In this work, we present theoretical and first experimental studies of a new kind of porous silicon photonic device based on optical surface wave. A theoretical analysis of the device is presented using plane-wave approximation. The porous silicon multilayered structures are realized using electrochemical etching of p + -type silicon. Morphological and optical characterizations of the realized structures are reported

  18. Reduce the start current of Smith-Purcell backward wave oscillator by sidewall grating

    International Nuclear Information System (INIS)

    Li, D.; Imasaki, K.; Gao, X.; Yang, Z.; Park, Gun-Sik

    2007-01-01

    A sidewall grating for the Smith-Purcell device is proposed to enhance the coupling of the optical mode with the electron beam and, consequently, relax the stringent requirements to the electron beam. With the help of three-dimensional particle-in-cell simulations, it has been shown that, comparing with the general grating, the usage of a sidewall grating improves the growth rate and dramatically shortens the time for the device to reach saturation. It is also found that the sidewall grating holds the potential to reduce the start current for the operation of a Smith-Purcell backward wave oscillator

  19. Running gratings in photoconductive materials

    DEFF Research Database (Denmark)

    Kukhtarev, N. V.; Kukhtareva, T.; Lyuksyutov, S. F.

    2005-01-01

    Starting from the three-dimensional version of a standard photorefractive model (STPM), we obtain a reduced compact Set of equations for an electric field based on the assumption of a quasi-steady-state fast recombination. The equations are suitable for evaluation of a current induced by running...... gratings at small-contrast approximation and also are applicable for the description of space-charge wave domains. We discuss spatial domain and subharmonic beam formation in bismuth silicon oxide (BSO) crystals in the framework of the small-contrast approximation of STPM. The experimental results...

  20. At-wavelength metrology using the moiré fringe analysis method based on a two dimensional grating interferometer

    International Nuclear Information System (INIS)

    Wang, Hongchang; Berujon, Sebastien; Pape, Ian; Rutishauser, Simon; David, Christian; Sawhney, Kawal

    2013-01-01

    A two-dimensional (2D) grating interferometer was used to perform at-wavelength metrology. A Fast Fourier Transform (FFT) of the interferograms recovers the differential X-ray beam phase in two orthogonal directions simultaneously. As an example, the X-ray wavefronts downstream from a Fresnel Zone plate were measured using the moiré fringe analysis method, which requires only a single image. The rotating shearing interferometer technique for moiré fringe analysis was extended from one dimension to two dimensions to carry out absolute wavefront metrology. In addition, the 2D moiré fringes were extrapolated using Gerchberg's method to reduce the boundary artifacts. The advantages and limitations of the phase-stepping method and the moiré fringe analysis method are also discussed. -- Highlights: ► A rapid and sensitive strip test for CPPU (forchlorfenuron) detection is reported. ► Carbon nanoparticles were used for antibody labelling. ► A common flatbed scanner was employed to the quantitate strip spots. ► The new method was successfully applied to the analysis of the field samples

  1. A Highly Sensitive Two-Dimensional Inclinometer Based on Two Etched Chirped-Fiber-Grating Arrays †

    Science.gov (United States)

    Chang, Hung-Ying; Chang, Yu-Chung; Liu, Wen-Fung

    2017-01-01

    We present a novel two-dimensional fiber-optic inclinometer with high sensitivity by crisscrossing two etched chirped fiber Bragg gratings (CFBG) arrays. Each array is composed of two symmetrically-arranged CFBGs. By etching away most of the claddings of the CFBGs to expose the evanescent wave, the reflection spectra are highly sensitive to the surrounding index change. When we immerse only part of the CFBG in liquid, the effective index difference induces a superposition peak in the refection spectrum. By interrogating the peak wavelengths of the CFBGs, we can deduce the tilt angle and direction simultaneously. The inclinometer has a resolution of 0.003° in tilt angle measurement and 0.00187 rad in tilt direction measurement. Due to the unique sensing mechanism, the sensor is temperature insensitive. This sensor can be useful in long term continuous monitoring of inclination or in real-time feedback control of tilt angles, especially in harsh environments with violent temperature variation. PMID:29244770

  2. Optical single sideband modulation radio over fiber system by using a fiber-Bragg-grating-based acousto-optic filter

    Science.gov (United States)

    Gao, Song; Pei, Li; Li, Zhuoxuan; Liu, Chao; Wang, Yiqun; Weng, Sijun

    2013-03-01

    An optical single sideband (OSSB) modulation radio over a fiber system, by using an acousto-optic filter (AOF), is proposed and demonstrated. In the AOF, a uniform fiber Bragg grating is etched and modulated by an axially propagating acoustic wave. Due to the acousto-optic superlattice modulation, two secondary reflection peaks, centered on the primary reflection peak, are generated. In the scheme, an optical double-sideband signal passes though the AOF to realize OSSB modulation. Because the reflect depth of the primary peak is much deeper than those of the secondary peaks, the carrier experiences higher attenuation than the upper sideband, which means the carrier-to-sideband ratio (CSR) can be optimized at the same time. We demonstrate this scheme via simulations, and successfully reduce the CSR from 9.73 to 2.9 dB. As a result, the receiving sensitivity improved from -23.43 to -31.18 dBm at BER of 10-9 with 30 km long SMF.

  3. Holographic gratings in photorefractive polymers without external electric field

    DEFF Research Database (Denmark)

    Kukhtarev, N.; Lyuksyutov, S.; Buchhave, Preben

    1997-01-01

    Using anomalous large diffusion we report a recording of reflection type gratings in a PVK-based photorefractive polymer without any external electric field. The diffraction efficiency of the gratings was measured to be 7%. An efficient modulation of beams during two-beam coupling up to 12...

  4. 3D Printed Photoresponsive Devices Based on Shape Memory Composites.

    Science.gov (United States)

    Yang, Hui; Leow, Wan Ru; Wang, Ting; Wang, Juan; Yu, Jiancan; He, Ke; Qi, Dianpeng; Wan, Changjin; Chen, Xiaodong

    2017-09-01

    Compared with traditional stimuli-responsive devices with simple planar or tubular geometries, 3D printed stimuli-responsive devices not only intimately meet the requirement of complicated shapes at macrolevel but also satisfy various conformation changes triggered by external stimuli at the microscopic scale. However, their development is limited by the lack of 3D printing functional materials. This paper demonstrates the 3D printing of photoresponsive shape memory devices through combining fused deposition modeling printing technology and photoresponsive shape memory composites based on shape memory polymers and carbon black with high photothermal conversion efficiency. External illumination triggers the shape recovery of 3D printed devices from the temporary shape to the original shape. The effect of materials thickness and light density on the shape memory behavior of 3D printed devices is quantified and calculated. Remarkably, sunlight also triggers the shape memory behavior of these 3D printed devices. This facile printing strategy would provide tremendous opportunities for the design and fabrication of biomimetic smart devices and soft robotics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. The significant role of plasmonic effects in femtosecond laser-induced grating fabrication on the nanoscale

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Min; Zhao, Fuli [State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou, 510275 (China); Cheng, Ya; Xu, Zhizhan [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai, 201800 (China)

    2013-02-15

    Nowadays, plasmonics aiming at manipulating light beyond the diffraction limit has aroused great interest on account of the promise of nanoscale optical devices. Generally, the ability to break diffraction barrier is achieved via controlling surface plasmons (SPs) on artificial structures as products of human ingenuity. Here, nevertheless, it is demonstrated that in short-pulse laser ablation ultrafast active plasmonic structures spontaneously generate by virtue of plasmonic effects rather than human will. First, with the experimental results on ZnO, Si, and GaAs, explicit evidence is provided for the grating-splitting phenomenon that acts as a direct route for the formation of laser-induced deep-subwavelength gratings. The splitting mechanism can break through the diffraction limit and push laser-induced structures towards the nanoscale. Then, through comprehensive numerical studies based on the viewpoint of plasmonics, it can be confirmed that the grating-splitting phenomenon originates in the conversion of SP modes from the resonant to the nonresonant mode and further to the inphase or antiphase asymmetric mode. In short, plasmonic effects play an important role in ultrafast laser-induced grating splitting towards the nanoscale, which will provide new insights into the mechanisms of ultrafast laser-induced nanostructures. (copyright 2012 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. The significant role of plasmonic effects in femtosecond laser-induced grating fabrication on the nanoscale

    International Nuclear Information System (INIS)

    Huang, Min; Zhao, Fuli; Cheng, Ya; Xu, Zhizhan

    2013-01-01

    Nowadays, plasmonics aiming at manipulating light beyond the diffraction limit has aroused great interest on account of the promise of nanoscale optical devices. Generally, the ability to break diffraction barrier is achieved via controlling surface plasmons (SPs) on artificial structures as products of human ingenuity. Here, nevertheless, it is demonstrated that in short-pulse laser ablation ultrafast active plasmonic structures spontaneously generate by virtue of plasmonic effects rather than human will. First, with the experimental results on ZnO, Si, and GaAs, explicit evidence is provided for the grating-splitting phenomenon that acts as a direct route for the formation of laser-induced deep-subwavelength gratings. The splitting mechanism can break through the diffraction limit and push laser-induced structures towards the nanoscale. Then, through comprehensive numerical studies based on the viewpoint of plasmonics, it can be confirmed that the grating-splitting phenomenon originates in the conversion of SP modes from the resonant to the nonresonant mode and further to the inphase or antiphase asymmetric mode. In short, plasmonic effects play an important role in ultrafast laser-induced grating splitting towards the nanoscale, which will provide new insights into the mechanisms of ultrafast laser-induced nanostructures. (copyright 2012 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Noise and its reduction in graphene based nanopore devices

    International Nuclear Information System (INIS)

    Kumar, Ashvani; Park, Kyeong-Beom; Kim, Hyun-Mi; Kim, Ki-Bum

    2013-01-01

    Ionic current fluctuations in graphene nanopore devices are a ubiquitous phenomenon and are responsible for degraded spatial and temporal resolution. Here, we descriptively investigate the impact of different substrate materials (Si and quartz) and membrane thicknesses on noise characteristics of graphene nanopore devices. To mitigate the membrane fluctuations and pin-hole defects, a SiN x membrane is transferred onto the substrate and a pore of approximately 70 nm in diameter is perforated prior to the graphene transfer. Comprehensive noise study reveals that the few layer graphene transferred onto the quartz substrate possesses low noise level and higher signal to noise ratio as compared to single layer graphene, without deteriorating the spatial resolution. The findings here point to improvement of graphene based nanopore devices for exciting opportunities in future single-molecule genomic screening devices. (paper)

  8. The Reusable Load Cell with Protection Applied for Online Monitoring of Overhead Transmission Lines Based on Fiber Bragg Grating

    Directory of Open Access Journals (Sweden)

    Guoming Ma

    2016-06-01

    Full Text Available Heavy ice coating of high–voltage overhead transmission lines may lead to conductor breakage and tower collapse causing the unexpected interrupt of power supply. The optical load cell applied in ice monitoring systems is immune to electromagnetic interference and has no need of a power supply on site. Therefore, it has become a hot research topic in China and other countries. In this paper, to solve the problem of eccentric load in measurement, we adopt the shearing structure with additional grooves to improve the strain distribution and acquire good repeatability. Then, the fiber Bragg grating (FBG with a permanent weldable package are mounted onto the front/rear groove of the elastic element by spot welding, the direction deviation of FBGs is 90° from each other to achieve temperature compensation without an extra FBG. After that, protection parts are designed to guarantee high sensitivity for a light load condition and industrial safety under a heavy load up to 65 kN. The results of tension experiments indicate that the sensitivity and resolution of the load cell is 0.1285 pm/N and 7.782 N in the conventional measuring range (0–10 kN. Heavy load tension experiments prove that the protection structure works and the sensitivity and resolution are not changed after several high load (65 kN cycles. In addition, the experiment shows that the resolution of the sensor is 87.79 N in the large load range, allowing the parameter to be used in heavy icing monitoring.

  9. Multiwavelength optical scatterometry of dielectric gratings

    KAUST Repository

    Yashina, Nataliya P.

    2012-08-01

    Modern scatterometry problems arising in the lithography production of periodic gratings are in the focus of the work. The performance capabilities of a novel theoretical and numerical modeling oriented to these problems are considered. The approach is based on rigorous solutions of 2-D initial boundary value problems of the gratings theory. The quintessence and advantage of the method is the possibility to perform an efficient analysis simultaneously and interactively both for steady state and transient processes of the resonant scattering of electromagnetic waves by the infinite and compact periodic structures. © 2012 IEEE.

  10. Detection of premature browning in ground beef with an integrated optical-fibre based sensor using reflection spectroscopy and fibre Bragg grating technology

    International Nuclear Information System (INIS)

    O'Farrell, M; Sheridan, C; Lewis, E

    2007-01-01

    This paper reports on an optical fibre based sensor system to detect the occurrence of premature browning in ground beef. Premature browning (PMB) occurs when, at a temperature below the pasteurisation temperature of 71 deg. C, there are no traces of pink meat left in the patty. PMB is more frequent if poorer quality beef or beef that has been stored under imperfect conditions. The experimental work pertaining to this paper involved cooking fresh meat and meat that has been stored in a freezer for, 1 week, 1 month and 3 months and recording the reflected spectra and temperature at the core of the product, during the cooking process, in order to develop a classifier based on the spectral response and using a Self-Organising Map (SOM) to classify the patties into one of four categories, based on their colour. Further tests were also carried out on developing an all-optical fibre sensor for measuring both the temperature and colour in a single integrated probe. The integrated probe contains two different sensor concepts, one to monitor temperature, based on Fibre Bragg Grating (FBG) technology and a second for meat quality, based on reflection spectroscopy in the visible wavelength range

  11. Underwater unidirectional acoustic transmission through a plate with bilateral asymmetric gratings

    Science.gov (United States)

    Song, Ailing; Chen, Tianning; Wang, Xiaopeng; Xi, Yanhui; Liang, Qingxuan

    2018-04-01

    In this paper, a novel underwater unidirectional acoustic transmission (UAT) device consisting of a plate with bilateral asymmetric gratings is proposed and numerically investigated. The transmission spectra, the acoustic intensity field distributions, and the displacement field distributions are numerically calculated based on the finite element method. The transmission spectra show that the proposed device exhibits different UAT effects in three bands. The acoustic intensity field distributions demonstrate that the proposed device can realize UAT, which agree well with the transmission spectra. The mechanism is discussed by analyzing the displacement field distributions, and the UAT is attributed to the symmetric mode excited in brass plate. Furthermore, the effects of the lattice constant, the upper slit width, and the lower slit width on bands are discussed. Our design provides a good reference for designing underwater UAT devices and has potential applications in some fields, such as medical ultrasonic devices, acoustic barrier, and noise insulation.

  12. Efficient Signature Based Malware Detection on Mobile Devices

    Directory of Open Access Journals (Sweden)

    Deepak Venugopal

    2008-01-01

    Full Text Available The threat of malware on mobile devices is gaining attention recently. It is important to provide security solutions to these devices before these threats cause widespread damage. However, mobile devices have severe resource constraints in terms of memory and power. Hence, even though there are well developed techniques for malware detection on the PC domain, it requires considerable effort to adapt these techniques for mobile devices. In this paper, we outline the considerations for malware detection on mobile devices and propose a signature based malware detection method. Specifically, we detail a signature matching algorithm that is well suited for use in mobile device scanning due to its low memory requirements. Additionally, the matching algorithm is shown to have high scanning speed which makes it unobtrusive to users. Our evaluation and comparison study with the well known Clam-AV scanner shows that our solution consumes less than 50% of the memory used by Clam-AV while maintaining a fast scanning rate.

  13. Electrochromic Devices Based on Porous Tungsten Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Y. Djaoued

    2012-01-01

    Full Text Available Recent developments in the synthesis of transition metal oxides in the form of porous thin films have opened up opportunities in the construction of electrochromic devices with enhanced properties. In this paper, synthesis, characterization and electrochromic applications of porous WO3 thin films with different nanocrystalline phases, such as hexagonal, monoclinic, and orthorhombic, are presented. Asymmetric electrochromic devices have been constructed based on these porous WO3 thin films. XRD measurements of the intercalation/deintercalation of Li+ into/from the WO3 layer of the device as a function of applied coloration/bleaching voltages show systematic changes in the lattice parameters associated with structural phase transitions in LixWO3. Micro-Raman studies show systematic crystalline phase changes in the spectra of WO3 layers during Li+ ion intercalation and deintercalation, which agree with the XRD data. These devices exhibit interesting optical modulation (up to ~70% due to intercalation/deintercalation of Li ions into/from the WO3 layer of the devices as a function of applied coloration/bleaching voltages. The obtained optical modulation of the electrochromic devices indicates that, they are suitable for applications in electrochromic smart windows.

  14. Development of induction current acquisition device based on ARM

    Science.gov (United States)

    Ji, Yanju; Liu, Xiyang; Huang, Wanyu; Yao, Jiang; Yuan, Guiyang; Hui, Luan; Guan, Shanshan

    2018-03-01

    We design an induction current acquisition device based on ARM in order to realize high resolution and high sampling rate of acquisition for the induction current in wire-loop. Considering its characteristics of fast attenuation and small signal amplitude, we use the method of multi-path fusion for noise suppression. In the paper, the design is carried out from three aspects of analog circuit and device selection, independent power supply structure and the electromagnetic interference suppression of high frequency. DMA and ping-pong buffer, as a new data transmission technology, solves real time storage problem of massive data. The performance parameters of ARM acquisition device are tested. The comparison test of ARM acquisition device and cRIO acquisition device is performed at different time constants. The results show that it has 120dB dynamic range, 47kHz bandwidth, 96kHz sampling rate, 5μV the smallest resolution, and its average error value is not more than 4%, which proves the high accuracy and stability of the device.

  15. Two-dimensional grating guided-mode resonance tunable filter.

    Science.gov (United States)

    Kuo, Wen-Kai; Hsu, Che-Jung

    2017-11-27

    A two-dimensional (2D) grating guided-mode resonance (GMR) tunable filter is experimentally demonstrated using a low-cost two-step nanoimprinting technology with a one-dimensional (1D) grating polydimethylsiloxane mold. For the first nanoimprinting, we precisely control the UV LED irradiation dosage and demold the device when the UV glue is partially cured and the 1D grating mold is then rotated by three different angles, 30°, 60°, and 90°, for the second nanoimprinting to obtain 2D grating structures with different crossing angles. A high-refractive-index film ZnO is then coated on the surface of the grating structure to form the GMR filter devices. The simulation and experimental results demonstrate that the passband central wavelength of the filter can be tuned by rotating the device to change azimuth angle of the incident light. We compare these three 2D GMR filters with differential crossing angles and find that the filter device with a crossing angle of 60° exhibits the best performance. The tunable range of its central wavelength is 668-742 nm when the azimuth angle varies from 30° to 90°.

  16. Spintronic materials and devices based on antiferromagnetic metals

    OpenAIRE

    Wang, Y.Y.; Song, C.; Zhang, J.Y.; Pan, F.

    2017-01-01

    In this paper, we review our recent experimental developments on antiferromagnet (AFM) spintronics mainly comprising Mn-based noncollinear AFM metals. IrMn-based tunnel junctions and Hall devices have been investigated to explore the manipulation of AFM moments by magnetic fields, ferromagnetic materials and electric fields. Room-temperature tunneling anisotropic magnetoresistance based on IrMn as well as FeMn has been successfully achieved, and electrical control of the AFM exchange spring i...

  17. Review on microfluidic paper-based analytical devices towards commercialisation.

    Science.gov (United States)

    Akyazi, Tugce; Basabe-Desmonts, Lourdes; Benito-Lopez, Fernando

    2018-02-25

    Paper-based analytical devices introduce an innovative platform technology for fluid handling and analysis, with wide range of applications, promoting low cost, ease of fabrication/operation and equipment independence. This review gives a general overview on the fabrication techniques reported to date, revealing and discussing their weak points as well as the newest approaches in order to overtake current mass production limitations and therefore commercialisation. Moreover, this review aims especially to highlight novel technologies appearing in literature for the effective handling and controlling of fluids. The lack of flow control is the main problem of paper-based analytical devices, which generates obstacles for marketing and slows down the transition of paper devices from the laboratory into the consumers' hands. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Grating stimulated echo

    International Nuclear Information System (INIS)

    Dubetsky, B.; Berman, P.R.; Sleator, T.

    1992-01-01

    A theory of a grating simulated echo (GTE) is developed. The GSE involves the sequential excitation of atoms by two counterpropagating traveling waves, a standing wave, and a third traveling wave. It is shown that the echo signal is very sensitive to small changes in atomic velocity, much more sensitive than the normal stimulated echo. Use of the GSE as a collisional probe or accelerometer is discussed

  19. Reconfigurable terahertz grating with enhanced transmission of TE polarized light

    Directory of Open Access Journals (Sweden)

    J. W. He

    2017-07-01

    Full Text Available We demonstrate an optically reconfigurable grating with enhanced transmission of TE-polarized waves in the terahertz (THz waveband. This kind of grating is realized by projecting a grating image onto a thin Si wafer with a digital micromirror device (DMD. The enhanced transmission is caused by a resonance of the electromagnetic fields between the photoexcited strips. The position of the transmission peak shifts with the variation of the period and duty cycle of the photoinduced grating, which can be readily controlled by the DMD. Furthermore, a flattened Gaussian model was applied to describe the distribution of the photoexcited free carriers in the Si wafer, and the simulated transmittance spectra are shown to be in good agreement with the experimental results. In future, the photoexcited carriers could also be used to produce THz diffractive elements with reconfigurable functionality.

  20. Grated waveguide-based optical cavities as compact sensors for sub-nanometre cantilever deflections, and small refractive-index changes

    NARCIS (Netherlands)

    Kauppinen, L.J.; Hoekstra, Hugo; Dijkstra, Mindert; de Ridder, R.M.; Krijnen, Gijsbertus J.M.; MacCraith, B; McDonagh, C.

    2008-01-01

    The paper reports on theoretical and experimental results of integrated optical (IO) cavities defined by grated waveguides in $Si_3N_4$ and Si, for the accurate detection of cantilever deflection and bulk index changes.

  1. Focused-ion beam patterning of organolead trihalide perovskite for subwavelength grating nanophotonic applications

    KAUST Repository

    Alias, Mohd Sharizal

    2015-07-30

    The coherent amplified spontaneous emission and high photoluminescence quantum efficiency of organolead trihalide perovskite have led to research interest in this material for use in photonic devices. In this paper, the authors present a focused-ion beam patterning strategy for methylammonium lead tribromide (MAPbBr3) perovskite crystal for subwavelength grating nanophotonic applications. The essential parameters for milling, such as the number of scan passes, dwell time, ion dose, ion current, ion incident angle, and gas-assisted etching, were experimentally evaluated to determine the sputtering yield of the perovskite. Based on our patterning conditions, the authors observed that the sputtering yield ranged from 0.0302 to 0.0719 μm3/pC for the MAPbBr3 perovskite crystal. Using XeF2 for the focused-ion beam gas-assisted etching, the authors determined that the etching rate was reduced to between 0.40 and 0.97, depending on the ion dose, compared with milling with ions only. Using the optimized patterning parameters, the authors patterned binary and circular subwavelength grating reflectors on the MAPbBr3 perovskite crystal using the focused-ion beam technique. Based on the computed grating structure with around 97% reflectivity, all of the grating dimensions (period, duty cycle, and grating thickness) were patterned with nanoscale precision (>±3 nm), high contrast, and excellent uniformity. Our results provide a platform for utilizing the focused-ion beam technique for fast prototyping of photonic nanostructures or nanodevices on organolead trihalide perovskite.

  2. Long term carrier envelope phase stabilization of a grating based high power femtosecond laser using the direct locking method

    International Nuclear Information System (INIS)

    Lee, Jae Hwan; Lee, Youg Soo; Park, Juyun; Nam, Chang Hee; Yu, Tae Jun

    2008-01-01

    The carrier envelope phase (CEP)stabilization of femtosecond laser pulses has been intensively investigated for ultrafast science as well as for frequency metrology. In the case of few cycle pulses stabilization and control of the CEP is an important issue, since the electric field profile changes with CEP variation. We have developed the direct locking method to stabilize the CEP for the investigation of attosecond physics. The direct locking method uses the beating signal itself, measured using an f to 2f interferometer, as an error signal to a feedback loop. The direct locking method quenches the beating signal so that the CEP variation between successive pulses become zero and every pulses from the oscillator ts identical. Due to the direct use of the beating signal, the signal processing is simple and complex equipment, used in the case of the phase locked loop (PLL)method operating in the frequency domain, are not required. For long term stability, we have proposed and implemented a double feedback technique, and achieved CEP stabilization of the oscillator for 24 hours, as shown in Fig. 1. This long term CEP stabilization was achieved without realignment of any optical components. The CEP stabilization for a whole day is a clear demonstration of the robustness of the direct locking method. The amplification of CEP stabilized laser pulses induces additional CEP variation. Even though the CEP of an oscillator is stabilized, the CEP drift is generated again during amplification due to external perturbations, such as pumping power fluctuation and beam pointing fluctuation. To measure the CEP drift of the amplified pulses, a spectral interferometer (SI)was employed. The CEP drift obtained from SI was used as the error signal of another feedback loop installed in the amplifier chain. To compensate for the large CEP drift induced during amplification, the grating separation of the pulse compressor was adjusted. Figure 2 shows the result of CEP stabilization of

  3. Device-independent bit commitment based on the CHSH inequality

    International Nuclear Information System (INIS)

    Aharon, N; Massar, S; Pironio, S; Silman, J

    2016-01-01

    Bit commitment and coin flipping occupy a unique place in the device-independent landscape, as the only device-independent protocols thus far suggested for these tasks are reliant on tripartite GHZ correlations. Indeed, we know of no other bipartite tasks, which admit a device-independent formulation, but which are not known to be implementable using only bipartite nonlocality. Another interesting feature of these protocols is that the pseudo-telepathic nature of GHZ correlations—in contrast to the generally statistical character of nonlocal correlations, such as those arising in the violation of the CHSH inequality—is essential to their formulation and analysis. In this work, we present a device-independent bit commitment protocol based on CHSH testing, which achieves the same security as the optimal GHZ-based protocol, albeit at the price of fixing the time at which Alice reveals her commitment. The protocol is analyzed in the most general settings, where the devices are used repeatedly and may have long-term quantum memory. We also recast the protocol in a post-quantum setting where both honest and dishonest parties are restricted only by the impossibility of signaling, and find that overall the supra-quantum structure allows for greater security. (paper)

  4. Proton irradiation effects on gallium nitride-based devices

    Science.gov (United States)

    Karmarkar, Aditya P.

    Proton radiation effects on state-of-the-art gallium nitride-based devices were studied using Schottky diodes and high electron-mobility transistors. The device degradation was studied over a wide range of proton fluences. This study allowed for a correlation between proton irradiation effects between different types of devices and enhanced the understanding of the mechanisms responsible for radiation damage in GaN-based devices. Proton irradiation causes reduced carrier concentration and increased series resistance and ideality factor in Schottky diodes. 1.0-MeV protons cause greater degradation than 1.8-MeV protons because of their higher non-ionizing energy loss. The displacement damage in Schottky diodes recovers during annealing. High electron-mobility transistors exhibit extremely high radiation tolerance, continuing to perform up to a fluence of ˜1014 cm-2 of 1.8-MeV protons. Proton irradiation creates defect complexes in the thin-film structure. Decreased sheet carrier mobility due to increased carrier scattering and decreased sheet carrier density due to carrier removal by the defect centers are the primary damage mechanisms. Interface disorder at either the Schottky or the Ohmic contact plays a relatively unimportant part in overall device degradation in both Schottky diodes and high electron-mobility transistors.

  5. Mini array of quantum Hall devices based on epitaxial graphene

    International Nuclear Information System (INIS)

    Novikov, S.; Lebedeva, N.; Hämäläinen, J.; Iisakka, I.; Immonen, P.; Manninen, A. J.; Satrapinski, A.

    2016-01-01

    Series connection of four quantum Hall effect (QHE) devices based on epitaxial graphene films was studied for realization of a quantum resistance standard with an up-scaled value. The tested devices showed quantum Hall plateaux R H,2 at a filling factor v = 2 starting from a relatively low magnetic field (between 4 T and 5 T) when the temperature was 1.5 K. The precision measurements of quantized Hall resistance of four QHE devices connected by triple series connections and external bonding wires were done at B = 7 T and T = 1.5 K using a commercial precision resistance bridge with 50 μA current through the QHE device. The results showed that the deviation of the quantized Hall resistance of the series connection of four graphene-based QHE devices from the expected value of 4×R H,2  = 2 h/e 2 was smaller than the relative standard uncertainty of the measurement (<1 × 10 −7 ) limited by the used resistance bridge.

  6. Surface Fluctuation Scattering using Grating Heterodyne Spectroscopy

    DEFF Research Database (Denmark)

    Edwards, R. V.; Sirohi, R. S.; Mann, J. A.

    1982-01-01

    Heterodyne photon spectroscopy is used for the study of the viscoelastic properties of the liquid interface by studying light scattered from thermally generated surface fluctuations. A theory of a heterodyne apparatus based on a grating is presented, and the heterodyne condition is given in terms...

  7. Undergraduate Experiment with Fractal Diffraction Gratings

    Science.gov (United States)

    Monsoriu, Juan A.; Furlan, Walter D.; Pons, Amparo; Barreiro, Juan C.; Gimenez, Marcos H.

    2011-01-01

    We present a simple diffraction experiment with fractal gratings based on the triadic Cantor set. Diffraction by fractals is proposed as a motivating strategy for students of optics in the potential applications of optical processing. Fraunhofer diffraction patterns are obtained using standard equipment present in most undergraduate physics…

  8. Numerical analysis of a polysilicon-based resistive memory device

    KAUST Repository

    Berco, Dan; Chand, Umesh

    2018-01-01

    This study investigates a conductive bridge resistive memory device based on a Cu top electrode, 10-nm polysilicon resistive switching layer and a TiN bottom electrode, by numerical analysis for $$10^{3}$$103 programming and erase simulation cycles

  9. Rapid development of paper-based fluidic diagnostic devices

    CSIR Research Space (South Africa)

    Smith, S

    2014-11-01

    Full Text Available We present a method for rapid and low-cost development of microfluidic diagnostic devices using paper-based techniques. Specifically, the implementation of fluidic flow paths and electronics on paper are demonstrated, with the goal of producing...

  10. Device with pivoting base for the storage of nuclear fuel

    International Nuclear Information System (INIS)

    Raymond, T.E.

    1978-01-01

    A storage rack for nuclear fuel assemblies comprising lower and upper bearers to support and hold fuel assemblies in their vertical position is described. The feature of this rack is the lower supporting device which comprises a pivoting base on which rests each fuel assembly, thereby enabling the fuel assembly not be subjected to any fatigue during storage [fr

  11. Broadband illusion optical devices based on conformal mappings

    Science.gov (United States)

    Xiong, Zhan; Xu, Lin; Xu, Ya-Dong; Chen, Huan-Yang

    2017-10-01

    In this paper, we propose a simple method of illusion optics based on conformal mappings. By carefully developing designs with specific conformal mappings, one can make an object look like another with a significantly different shape. In addition, the illusion optical devices can work in a broadband of frequencies.

  12. Microcomputer based test system for charge coupled devices

    International Nuclear Information System (INIS)

    Sidman, S.

    1981-02-01

    A microcomputer based system for testing analog charge coupled integrated circuits has been developed. It measures device performance for three parameters: dynamic range, baseline shift due to leakage current, and transfer efficiency. A companion board tester has also been developed. The software consists of a collection of BASIC and assembly language routines developed on the test system microcomputer

  13. In plane optical sensor based on organic electronic devices

    NARCIS (Netherlands)

    Koetse, M.M; Rensing, P.A.; Heck, G.T. van; Sharpe, R.B.A.; Allard, B.A.M.; Wieringa, F.P.; Kruijt, P.G.M.; Meulendijks, N.M.M.; Jansen, H.; Schoo, H.F.M.

    2008-01-01

    Sensors based on organic electronic devices are emerging in a wide range of application areas. Here we present a sensor platform using organic light emitting diodes (OLED) and organic photodiodes (OPD) as active components. By means of lamination and interconnection technology the functional foils

  14. Modern Theory of Gratings Resonant Scattering: Analysis Techniques and Phenomena

    CERN Document Server

    Sirenko, Yuriy K

    2010-01-01

    Diffraction gratings are one of the most popular objects of analysis in electromagnetic theory. The requirements of applied optics and microwave engineering lead to many new problems and challenges for the theory of diffraction gratings, which force us to search for new methods and tools for their resolution. In Modern Theory of Gratings, the authors present results of the electromagnetic theory of diffraction gratings that will constitute the base of further development of this theory, which meet the challenges provided by modern requirements of fundamental and applied science. This volume covers: spectral theory of gratings (Chapter 1) giving reliable grounds for physical analysis of space-frequency and space-time transformations of the electromagnetic field in open periodic resonators and waveguides; authentic analytic regularization procedures (Chapter 2) that, in contradistinction to the traditional frequency-domain approaches, fit perfectly for the analysis of resonant wave scattering processes; paramet...

  15. Diffraction efficiency calculations of polarization diffraction gratings with surface relief

    Science.gov (United States)

    Nazarova, D.; Sharlandjiev, P.; Berberova, N.; Blagoeva, B.; Stoykova, E.; Nedelchev, L.

    2018-03-01

    In this paper, we evaluate the optical response of a stack of two diffraction gratings of equal one-dimensional periodicity. The first one is a surface-relief grating structure; the second, a volume polarization grating. This model is based on our experimental results from polarization holographic recordings in azopolymer films. We used films of commercially available azopolymer (poly[1-[4-(3-carboxy-4-hydroxyphenylazo) benzenesulfonamido]-1,2-ethanediyl, sodium salt]), shortly denoted as PAZO. During the recording process, a polarization grating in the volume of the material and a relief grating on the film surface are formed simultaneously. In order to evaluate numerically the optical response of this “hybrid” diffraction structure, we used the rigorous coupled-wave approach (RCWA). It yields stable numerical solutions of Maxwell’s vector equations using the algebraic eigenvalue method.

  16. Field-Based Experiential Learning Using Mobile Devices

    Science.gov (United States)

    Hilley, G. E.

    2015-12-01

    Technologies such as GPS and cellular triangulation allow location-specific content to be delivered by mobile devices, but no mechanism currently exists to associate content shared between locations in a way that guarantees the delivery of coherent and non-redundant information at every location. Thus, experiential learning via mobile devices must currently take place along a predefined path, as in the case of a self-guided tour. I developed a mobile-device-based system that allows a person to move through a space along a path of their choosing, while receiving information in a way that guarantees delivery of appropriate background and location-specific information without producing redundancy of content between locations. This is accomplished by coupling content to knowledge-concept tags that are noted as fulfilled when users take prescribed actions. Similarly, the presentation of the content is related to the fulfillment of these knowledge-concept tags through logic statements that control the presentation. Content delivery is triggered by mobile-device geolocation including GPS/cellular navigation, and sensing of low-power Bluetooth proximity beacons. Together, these features implement a process that guarantees a coherent, non-redundant educational experience throughout a space, regardless of a learner's chosen path. The app that runs on the mobile device works in tandem with a server-side database and file-serving system that can be configured through a web-based GUI, and so content creators can easily populate and configure content with the system. Once the database has been updated, the new content is immediately available to the mobile devices when they arrive at the location at which content is required. Such a system serves as a platform for the development of field-based geoscience educational experiences, in which students can organically learn about core concepts at particular locations while individually exploring a space.

  17. Technology for Polymer Optical Fiber Bragg Grating Fabrication and Interrogation

    DEFF Research Database (Denmark)

    Ganziy, Denis

    The aim of this project is to develop a new, high-quality interrogator for FBG sensor systems, which combines high performance with costeffectiveness. The work includes the fields of optical system design, signal processing, and algorithm investigation. We present an efficient and fast peak...... analyze and investigate errors and drawbacks, which are typical for spectrometer-based interrogators: undersampling, grating internal reflection, photo response nonuniformity, pixel crosstalk and temperature and long term drift. We propose a novel type of multichannel Digital Micromirror Device (DMD......) based interrogator, where the linear detector is replaced with a commercially available DMD, which leads to cost reduction and better performance. Original optical design, which utilizes advantages of a retro-reflect optical scheme, has been developed in Zemax. We test the presented interrogator...

  18. Multi-Device to Multi-Device (MD2MD Content-Centric Networking Based on Multi-RAT Device

    Directory of Open Access Journals (Sweden)

    Cheolhoon Kim

    2017-11-01

    Full Text Available This paper proposes a method whereby a device can transmit and receive information using a beacon, and also describes application scenarios for the proposed method. In a multi-device to multi-device (MD2MD content-centric networking (CCN environment, the main issue involves searching for and connecting to nearby devices. However, if a device can’t find another device that satisfies its requirements, the connection is delayed due to the repetition of processes. It is possible to rapidly connect to a device without repetition through the selection of the optimal device using the proposed method. Consequently, the proposed method and scenarios are advantageous in that they enable efficient content identification and delivery in a content-centric Internet of Things (IoT environment, in which multiple mobile devices coexist.

  19. Carbon-Nanotube-Based Thermoelectric Materials and Devices

    Energy Technology Data Exchange (ETDEWEB)

    Blackburn, Jeffrey L. [Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden CO 80401-3305 USA; Ferguson, Andrew J. [Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden CO 80401-3305 USA; Cho, Chungyeon [Department of Mechanical Engineering, Texas A& M University, College Station TX 77843-3003 USA; Grunlan, Jaime C. [Department of Mechanical Engineering, Texas A& M University, College Station TX 77843-3003 USA

    2018-01-22

    Conversion of waste heat to voltage has the potential to significantly reduce the carbon footprint of a number of critical energy sectors, such as the transportation and electricity-generation sectors, and manufacturing processes. Thermal energy is also an abundant low-flux source that can be harnessed to power portable/wearable electronic devices and critical components in remote off-grid locations. As such, a number of different inorganic and organic materials are being explored for their potential in thermoelectric-energy-harvesting devices. Carbon-based thermoelectric materials are particularly attractive due to their use of nontoxic, abundant source-materials, their amenability to high-throughput solution-phase fabrication routes, and the high specific energy (i.e., W g-1) enabled by their low mass. Single-walled carbon nanotubes (SWCNTs) represent a unique 1D carbon allotrope with structural, electrical, and thermal properties that enable efficient thermoelectric-energy conversion. Here, the progress made toward understanding the fundamental thermoelectric properties of SWCNTs, nanotube-based composites, and thermoelectric devices prepared from these materials is reviewed in detail. This progress illuminates the tremendous potential that carbon-nanotube-based materials and composites have for producing high-performance next-generation devices for thermoelectric-energy harvesting.

  20. Carbon-Nanotube-Based Thermoelectric Materials and Devices.

    Science.gov (United States)

    Blackburn, Jeffrey L; Ferguson, Andrew J; Cho, Chungyeon; Grunlan, Jaime C

    2018-03-01

    Conversion of waste heat to voltage has the potential to significantly reduce the carbon footprint of a number of critical energy sectors, such as the transportation and electricity-generation sectors, and manufacturing processes. Thermal energy is also an abundant low-flux source that can be harnessed to power portable/wearable electronic devices and critical components in remote off-grid locations. As such, a number of different inorganic and organic materials are being explored for their potential in thermoelectric-energy-harvesting devices. Carbon-based thermoelectric materials are particularly attractive due to their use of nontoxic, abundant source-materials, their amenability to high-throughput solution-phase fabrication routes, and the high specific energy (i.e., W g -1 ) enabled by their low mass. Single-walled carbon nanotubes (SWCNTs) represent a unique 1D carbon allotrope with structural, electrical, and thermal properties that enable efficient thermoelectric-energy conversion. Here, the progress made toward understanding the fundamental thermoelectric properties of SWCNTs, nanotube-based composites, and thermoelectric devices prepared from these materials is reviewed in detail. This progress illuminates the tremendous potential that carbon-nanotube-based materials and composites have for producing high-performance next-generation devices for thermoelectric-energy harvesting. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Second Law based definition of passivity/activity of devices

    Science.gov (United States)

    Sundqvist, Kyle M.; Ferry, David K.; Kish, Laszlo B.

    2017-10-01

    Recently, our efforts to clarify the old question, if a memristor is a passive or active device [1], triggered debates between engineers, who have had advanced definitions of passivity/activity of devices, and physicists with significantly different views about this seemingly simple question. This debate triggered our efforts to test the well-known engineering concepts about passivity/activity in a deeper way, challenging them by statistical physics. It is shown that the advanced engineering definition of passivity/activity of devices is self-contradictory when a thermodynamical system executing Johnson-Nyquist noise is present. A new, statistical physical, self-consistent definition based on the Second Law of Thermodynamics is introduced. It is also shown that, in a system with uniform temperature distribution, any rectifier circuitry that can rectify thermal noise must contain an active circuit element, according to both the engineering and statistical physical definitions.

  2. Switching dynamics of TaOx-based threshold switching devices

    Science.gov (United States)

    Goodwill, Jonathan M.; Gala, Darshil K.; Bain, James A.; Skowronski, Marek

    2018-03-01

    Bi-stable volatile switching devices are being used as access devices in solid-state memory arrays and as the active part of compact oscillators. Such structures exhibit two stable states of resistance and switch between them at a critical value of voltage or current. A typical resistance transient under a constant amplitude voltage pulse starts with a slow decrease followed by a rapid drop and leveling off at a low steady state value. This behavior prompted the interpretation of initial delay and fast transition as due to two different processes. Here, we show that the entire transient including incubation time, transition time, and the final resistance values in TaOx-based switching can be explained by one process, namely, Joule heating with the rapid transition due to the thermal runaway. The time, which is required for the device in the conducting state to relax back to the stable high resistance one, is also consistent with the proposed mechanism.

  3. New memory devices based on the proton transfer process

    International Nuclear Information System (INIS)

    Wierzbowska, Małgorzata

    2016-01-01

    Memory devices operating due to the fast proton transfer (PT) process are proposed by the means of first-principles calculations. Writing  information is performed using the electrostatic potential of scanning tunneling microscopy (STM). Reading information is based on the effect of the local magnetization induced at the zigzag graphene nanoribbon (Z-GNR) edge—saturated with oxygen or the hydroxy group—and can be realized with the use of giant magnetoresistance (GMR), a magnetic tunnel junction or spin-transfer torque devices. The energetic barriers for the hop forward and backward processes can be tuned by the distance and potential of the STM tip; this thus enables us to tailor the non-volatile logic states. The proposed system enables very dense packing of the logic cells and could be used in random access and flash memory devices. (paper)

  4. New memory devices based on the proton transfer process

    Science.gov (United States)

    Wierzbowska, Małgorzata

    2016-01-01

    Memory devices operating due to the fast proton transfer (PT) process are proposed by the means of first-principles calculations. Writing information is performed using the electrostatic potential of scanning tunneling microscopy (STM). Reading information is based on the effect of the local magnetization induced at the zigzag graphene nanoribbon (Z-GNR) edge—saturated with oxygen or the hydroxy group—and can be realized with the use of giant magnetoresistance (GMR), a magnetic tunnel junction or spin-transfer torque devices. The energetic barriers for the hop forward and backward processes can be tuned by the distance and potential of the STM tip; this thus enables us to tailor the non-volatile logic states. The proposed system enables very dense packing of the logic cells and could be used in random access and flash memory devices.

  5. Silicon nano crystal-based non-volatile memory devices

    International Nuclear Information System (INIS)

    Ng, C.Y.; Chen, T.P.; Sreeduth, D.; Chen, Q.; Ding, L.; Du, A.

    2006-01-01

    In this work, we have investigated the performance and reliability of a Flash memory based on silicon nanocrystal synthesized with very-low energy ion beams. The devices are fabricated with a conventional CMOS process and the size of the nanocrystal is ∼ 4 nm as determined from TEM measurement. Electrical properties of the devices with a tunnel oxide of either 3 nm or 7 nm are evaluated. The devices exhibit good endurance up to 10 5 W/E cycles even at the high operation temperature of 85 deg. C for both the tunnel oxide thicknesses. For the thicker tunnel oxide (i.e., the 7-nm tunnel oxide), a good retention performance with an extrapolated 10-year memory window of ∼ 0.3 V (or ∼ 20% of charge lose after 10 years) is achieved. However, ∼ 70% of charge loss after 10 years is expected for the thinner tunnel oxide (i.e., the 3-nm tunnel oxide)

  6. Proton irradiation of liquid crystal based adaptive optical devices

    International Nuclear Information System (INIS)

    Buis, E.J.; Berkhout, G.C.G.; Love, G.D.; Kirby, A.K.; Taylor, J.M.; Hannemann, S.; Collon, M.J.

    2012-01-01

    To assess its radiation hardness, a liquid crystal based adaptive optical element has been irradiated using a 60 MeV proton beam. The device with the functionality of an optical beam steerer was characterised before, during and after the irradiation. A systematic set of measurements on the transmission and beam deflection angles was carried out. The measurements showed that the transmission decreased only marginally and that its optical performance degraded only after a very high proton fluence (10 10 p/cm 2 ). The device showed complete annealing in the functionality as a beam steerer, which leads to the conclusion that the liquid crystal technology for optical devices is not vulnerable to proton irradiation as expected in space.

  7. Proton irradiation of liquid crystal based adaptive optical devices

    Energy Technology Data Exchange (ETDEWEB)

    Buis, E.J., E-mail: ernst-jan.buis@tno.nl [cosine Science and Computing BV, Niels Bohrweg 11, 2333 CA Leiden (Netherlands); Berkhout, G.C.G. [cosine Science and Computing BV, Niels Bohrweg 11, 2333 CA Leiden (Netherlands); Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden (Netherlands); Love, G.D.; Kirby, A.K.; Taylor, J.M. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Hannemann, S.; Collon, M.J. [cosine Research BV, Niels Bohrweg 11, 2333 CA Leiden (Netherlands)

    2012-01-01

    To assess its radiation hardness, a liquid crystal based adaptive optical element has been irradiated using a 60 MeV proton beam. The device with the functionality of an optical beam steerer was characterised before, during and after the irradiation. A systematic set of measurements on the transmission and beam deflection angles was carried out. The measurements showed that the transmission decreased only marginally and that its optical performance degraded only after a very high proton fluence (10{sup 10}p/cm{sup 2}). The device showed complete annealing in the functionality as a beam steerer, which leads to the conclusion that the liquid crystal technology for optical devices is not vulnerable to proton irradiation as expected in space.

  8. Nanotechnology based devices and applications in medicine: An overview

    Directory of Open Access Journals (Sweden)

    Elvis A Martis

    2012-01-01

    Full Text Available Nanotechnology has been the most explored and extensively studied area in recent times. Many devices which were earlier impossible to imagine, are being developed at a lightning speed with the application of nanotechnology. To overcome the challenges offered by the most dreaded diseases, such as cancer or any disease involving the central nervous system or other inaccessible areas of the human body, nanotechnology has been proved to be a boon in making the treatment more target specific and minimizing the toxicities. This review describes a handful of important devices and applications based on nanotechnology in medicine made in recent times. This article also describes in brief the regulatory concerns and the ethical issues pertaining to nanomedical devices.

  9. An implantable thermoresponsive drug delivery system based on Peltier device.

    Science.gov (United States)

    Yang, Rongbing; Gorelov, Alexander V; Aldabbagh, Fawaz; Carroll, William M; Rochev, Yury

    2013-04-15

    Locally dropping the temperature in vivo is the main obstacle to the clinical use of a thermoresponsive drug delivery system. In this paper, a Peltier electronic element is incorporated with a thermoresponsive thin film based drug delivery system to form a new drug delivery device which can regulate the release of rhodamine B in a water environment at 37 °C. Various current signals are used to control the temperature of the cold side of the Peltier device and the volume of water on top of the Peltier device affects the change in temperature. The pulsatile on-demand release profile of the model drug is obtained by turning the current signal on and off. The work has shown that the 2600 mAh power source is enough to power this device for 1.3 h. Furthermore, the excessive heat will not cause thermal damage in the body as it will be dissipated by the thermoregulation of the human body. Therefore, this simple novel device can be implanted and should work well in vivo. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Optical sensor array platform based on polymer electronic devices

    Science.gov (United States)

    Koetse, Marc M.; Rensing, Peter A.; Sharpe, Ruben B. A.; van Heck, Gert T.; Allard, Bart A. M.; Meulendijks, Nicole N. M. M.; Kruijt, Peter G. M.; Tijdink, Marcel W. W. J.; De Zwart, René M.; Houben, René J.; Enting, Erik; van Veen, Sjaak J. J. F.; Schoo, Herman F. M.

    2007-10-01

    Monitoring of personal wellbeing and optimizing human performance are areas where sensors have only begun to be used. One of the reasons for this is the specific demands that these application areas put on the underlying technology and system properties. In many cases these sensors will be integrated in clothing, be worn on the skin, or may even be placed inside the body. This implies that flexibility and wearability of the systems is essential for their success. Devices based on polymer semiconductors allow for these demands since they can be fabricated with thin film technology. The use of thin film device technology allows for the fabrication of very thin sensors (e.g. integrated in food product packaging), flexible or bendable sensors in wearables, large area/distributed sensors, and intrinsically low-cost applications in disposable products. With thin film device technology a high level of integration can be achieved with parts that analyze signals, process and store data, and interact over a network. Integration of all these functions will inherently lead to better cost/performance ratios, especially if printing and other standard polymer technology such as high precision moulding is applied for the fabrication. In this paper we present an optical transmission sensor array based on polymer semiconductor devices made by thin film technology. The organic devices, light emitting diodes, photodiodes and selective medium chip, are integrated with classic electronic components. Together they form a versatile sensor platform that allows for the quantitative measurement of 100 channels and communicates wireless with a computer. The emphasis is given to the sensor principle, the design, fabrication technology and integration of the thin film devices.

  11. High speed and high resolution interrogation of a fiber Bragg grating sensor based on microwave photonic filtering and chirped microwave pulse compression.

    Science.gov (United States)

    Xu, Ou; Zhang, Jiejun; Yao, Jianping

    2016-11-01

    High speed and high resolution interrogation of a fiber Bragg grating (FBG) sensor based on microwave photonic filtering and chirped microwave pulse compression is proposed and experimentally demonstrated. In the proposed sensor, a broadband linearly chirped microwave waveform (LCMW) is applied to a single-passband microwave photonic filter (MPF) which is implemented based on phase modulation and phase modulation to intensity modulation conversion using a phase modulator (PM) and a phase-shifted FBG (PS-FBG). Since the center frequency of the MPF is a function of the central wavelength of the PS-FBG, when the PS-FBG experiences a strain or temperature change, the wavelength is shifted, which leads to the change in the center frequency of the MPF. At the output of the MPF, a filtered chirped waveform with the center frequency corresponding to the applied strain or temperature is obtained. By compressing the filtered LCMW in a digital signal processor, the resolution is improved. The proposed interrogation technique is experimentally demonstrated. The experimental results show that interrogation sensitivity and resolution as high as 1.25 ns/με and 0.8 με are achieved.

  12. Photovoltaic dependence of photorefractive grating on the externally applied dc electric field

    Science.gov (United States)

    Maurya, M. K.; Yadav, R. A.

    2013-04-01

    Photovoltaic dependence of photorefractive grating (i.e., space-charge field and phase-shift of the index grating) on the externally applied dc electric field in photovoltaic-photorefractive materials has been investigated. The influence of photovoltaic field (EPhN), diffusion field and carrier concentration ratio r (donor/acceptor impurity concentration ratio) on the space-charge field (SCF) and phase-shift of the index grating in the presence and absence of the externally applied dc electric field have also been studied in details. Our results show that, for a given value of EPhN and r, the magnitude of the SCF and phase-shift of the index grating can be enhanced significantly by employing the lower dc electric field (EONphotovoltaic-photorefractive crystal and higher value of diffusion field (EDN>40). Such an enhancement in the magnitude of the SCF and phase-shift of the index grating are responsible for the strongest beam coupling in photovoltaic-photorefractive materials. This sufficiently strong beam coupling increases the two-beam coupling gain that may be exceed the absorption and reflection losses of the photovoltaic-photorefractive sample, and optical amplification can occur. The higher value of optical amplification in photovoltaic-photorefractive sample is required for the every applications of photorefractive effect so that technology based on the photorefractive effect such as holographic storage devices, optical information processing, acousto-optic tunable filters, gyro-sensors, optical modulators, optical switches, photorefractive-photovoltaic solitons, biomedical applications, and frequency converters could be improved.

  13. Light programmable organic transistor memory device based on hybrid dielectric

    Science.gov (United States)

    Ren, Xiaochen; Chan, Paddy K. L.

    2013-09-01

    We have fabricated the transistor memory devices based on SiO2 and polystyrene (PS) hybrid dielectric. The trap states densities with different semiconductors have been investigated and a maximum 160V memory window between programming and erasing is realized. For DNTT based transistor, the trapped electron density is limited by the number of mobile electrons in semiconductor. The charge transport mechanism is verified by light induced Vth shift effect. Furthermore, in order to meet the low operating power requirement of portable electronic devices, we fabricated the organic memory transistor based on AlOx/self-assembly monolayer (SAM)/PS hybrid dielectric, the effective capacitance of hybrid dielectric is 210 nF cm-2 and the transistor can reach saturation state at -3V gate bias. The memory window in transfer I-V curve is around 1V under +/-5V programming and erasing bias.

  14. Overview of diffraction gratings technologies for space-flight satellites and astronomy

    Science.gov (United States)

    Cotel, Arnaud; Liard, Audrey; Desserouer, Frédéric; Bonnemason, Francis; Pichon, Pierre

    2014-09-01

    The diffraction gratings are widely used in Space-flight satellites for spectrograph instruments or in ground-based telescopes in astronomy. The diffraction gratings are one of the key optical components of such systems and have to exhibit very high optical performances. HORIBA Jobin Yvon S.A.S. (part of HORIBA Group) is in the forefront of such gratings development for more than 40 years. During the past decades, HORIBA Jobin Yvon (HJY) has developed a unique expertise in diffraction grating design and manufacturing processes for holographic, ruled or etched gratings. We will present in this paper an overview of diffraction grating technologies especially designed for space and astronomy applications. We will firstly review the heritage of the company in this field with the space qualification of different grating types. Then, we will describe several key grating technologies developed for specific space or astronomy projects: ruled blazed low groove density plane reflection grating, holographic blazed replica plane grating, high-groove density holographic toroidal and spherical grating and transmission Fused Silica Etched (FSE) grismassembled grating.

  15. Optical microphone with fiber Bragg grating and signal processing techniques

    Science.gov (United States)

    Tosi, Daniele; Olivero, Massimo; Perrone, Guido

    2008-06-01

    In this paper, we discuss the realization of an optical microphone array using fiber Bragg gratings as sensing elements. The wavelength shift induced by acoustic waves perturbing the sensing Bragg grating is transduced into an intensity modulation. The interrogation unit is based on a fixed-wavelength laser source and - as receiver - a photodetector with proper amplification; the system has been implemented using devices for standard optical communications, achieving a low-cost interrogator. One of the advantages of the proposed approach is that no voltage-to-strain calibration is required for tracking dynamic shifts. The optical sensor is complemented by signal processing tools, including a data-dependent frequency estimator and adaptive filters, in order to improve the frequency-domain analysis and mitigate the effects of disturbances. Feasibility and performances of the optical system have been tested measuring the output of a loudspeaker. With this configuration, the sensor is capable of correctly detecting sounds up to 3 kHz, with a frequency response that exhibits a top sensitivity within the range 200-500 Hz; single-frequency input sounds inducing an axial strain higher than ~10nɛ are correctly detected. The repeatability range is ~0.1%. The sensor has also been applied for the detection of pulsed stimuli generated from a metronome.

  16. Biomedical device prototype based on small scale hydrodynamic cavitation

    Directory of Open Access Journals (Sweden)

    Morteza Ghorbani

    2018-03-01

    Full Text Available This study presents a biomedical device prototype based on small scale hydrodynamic cavitation. The application of small scale hydrodynamic cavitation and its integration to a biomedical device prototype is offered as an important alternative to other techniques, such as ultrasound therapy, and thus constitutes a local, cheap, and energy-efficient solution, for urinary stone therapy and abnormal tissue ablation (e.g., benign prostate hyperplasia (BPH. The destructive nature of bubbly, cavitating, flows was exploited, and the potential of the prototype was assessed and characterized. Bubbles generated in a small flow restrictive element (micro-orifice based on hydrodynamic cavitation were utilized for this purpose. The small bubbly, cavitating, flow generator (micro-orifice was fitted to a small flexible probe, which was actuated with a micromanipulator using fine control. This probe also houses an imaging device for visualization so that the emerging cavitating flow could be locally targeted to the desired spot. In this study, the feasibility of this alternative treatment method and its integration to a device prototype were successfully accomplished.

  17. Biomedical device prototype based on small scale hydrodynamic cavitation

    Science.gov (United States)

    Ghorbani, Morteza; Sozer, Canberk; Alcan, Gokhan; Unel, Mustafa; Ekici, Sinan; Uvet, Huseyin; Koşar, Ali

    2018-03-01

    This study presents a biomedical device prototype based on small scale hydrodynamic cavitation. The application of small scale hydrodynamic cavitation and its integration to a biomedical device prototype is offered as an important alternative to other techniques, such as ultrasound therapy, and thus constitutes a local, cheap, and energy-efficient solution, for urinary stone therapy and abnormal tissue ablation (e.g., benign prostate hyperplasia (BPH)). The destructive nature of bubbly, cavitating, flows was exploited, and the potential of the prototype was assessed and characterized. Bubbles generated in a small flow restrictive element (micro-orifice) based on hydrodynamic cavitation were utilized for this purpose. The small bubbly, cavitating, flow generator (micro-orifice) was fitted to a small flexible probe, which was actuated with a micromanipulator using fine control. This probe also houses an imaging device for visualization so that the emerging cavitating flow could be locally targeted to the desired spot. In this study, the feasibility of this alternative treatment method and its integration to a device prototype were successfully accomplished.

  18. Numerical modelling of a straw-fired grate boiler

    DEFF Research Database (Denmark)

    Kær, Søren Knudsen

    2004-01-01

    The paper presents a computational fluid dynamics (CFD) analysis of a 33 MW straw-fired grate boiler. Combustion on the grate plays akey-role in the analysis of these boilers and in this work a stand-alone code was used to provide inlet conditions for the CFD analysis. Modelpredictions were...... compared with available gas temperature and species concentration measurements showing good agreement. Combustionof biomass in grate-based boilers is often associated with high emission levels and relatively high amounts of unburnt carbon in the fly ash.Based on the CFD analysis, it is suggested that poor...

  19. Low crosstalk Arrayed Waveguide Grating with Cascaded Waveguide Grating Filter

    International Nuclear Information System (INIS)

    Deng Yang; Liu Yuan; Gao Dingshan

    2011-01-01

    We propose a highly compact and low crosstalk arrayed waveguide grating (AWG) with cascaded waveguide grating (CWGF). The side lobes of the silicon nanowire AWG, which are normally introduced by fabrication errors, can be effectively suppressed by the CWGF. And the crosstalk can be improved about 15dB.

  20. Fabrication of advanced Bragg gratings with complex apodization profiles by use of the polarization control method

    DEFF Research Database (Denmark)

    Deyerl, Hans-Jürgen; Plougmann, Nikolai; Jensen, Jesper Bo Damm

    2004-01-01

    The polarization control method offers a flexible, robust, and low-cost route for the parallel fabrication of gratings with complex apodization profiles including several discrete phase shifts and chirp. The performance of several test gratings is evaluated in terms of their spectral response...... and compared with theoretical predictions. Short gratings with sidelobe-suppression levels in excess of 32 dB and transmission dips lower than 80 dB have been realized. Finally, most of the devices fabricated by the polarization control method show comparable quality to gratings manufactured by far more...

  1. Diagnosing and mapping pulmonary emphysema on X-ray projection images: incremental value of grating-based X-ray dark-field imaging.

    Science.gov (United States)

    Meinel, Felix G; Schwab, Felix; Schleede, Simone; Bech, Martin; Herzen, Julia; Achterhold, Klaus; Auweter, Sigrid; Bamberg, Fabian; Yildirim, Ali Ö; Bohla, Alexander; Eickelberg, Oliver; Loewen, Rod; Gifford, Martin; Ruth, Ronald; Reiser, Maximilian F; Pfeiffer, Franz; Nikolaou, Konstantin

    2013-01-01

    To assess whether grating-based X-ray dark-field imaging can increase the sensitivity of X-ray projection images in the diagnosis of pulmonary emphysema and allow for a more accurate assessment of emphysema distribution. Lungs from three mice with pulmonary emphysema and three healthy mice were imaged ex vivo using a laser-driven compact synchrotron X-ray source. Median signal intensities of transmission (T), dark-field (V) and a combined parameter (normalized scatter) were compared between emphysema and control group. To determine the diagnostic value of each parameter in differentiating between healthy and emphysematous lung tissue, a receiver-operating-characteristic (ROC) curve analysis was performed both on a per-pixel and a per-individual basis. Parametric maps of emphysema distribution were generated using transmission, dark-field and normalized scatter signal and correlated with histopathology. Transmission values relative to water were higher for emphysematous lungs than for control lungs (1.11 vs. 1.06, pemphysema provides color-coded parametric maps, which show the best correlation with histopathology. In a murine model, the complementary information provided by X-ray transmission and dark-field images adds incremental diagnostic value in detecting pulmonary emphysema and visualizing its regional distribution as compared to conventional X-ray projections.

  2. Preliminary comparison of grating-based and in-line phase contrast X-ray imaging with synchrotron radiation for mouse kidney at TOMCAT

    International Nuclear Information System (INIS)

    Sun, J; Liu, P; Xu, L X; Irvine, S; Pinzer, B; Stampanoni, M

    2013-01-01

    Phase contrast imaging has been demonstrated to be advantageous in revealing detailed structures inside biological specimens without contrast agents. Grating-based differential phase contrast (DPC) and in-line phase contrast (ILPC) X-ray imaging are the two modalities frequently used at the beamline of TOmographic Microscopy and Coherent rAdiology experimenTs (TOMCAT) at the Swiss Light Source (SLS). In this paper, we preliminarily compared the abilities of two types of phase contrast imaging in distinguishing micro structures in mouse kidneys. The 3D reconstructions showed that the microstructures in kidney, such as micro vessels and renal tubules, were displayed clearly with both imaging modalities. The two techniques may be viewed as complementary. For larger features with very small density variations DPC is the desirable method. In cases where dose and time limits may prohibit the multiple steps required for DPC, and when the focus is on finer features, the ILPC method may be considered as a more viable alternative. Moreover, high resolution ILPC images are comparable with histological results.

  3. A new JPEG-based steganographic algorithm for mobile devices

    Science.gov (United States)

    Agaian, Sos S.; Cherukuri, Ravindranath C.; Schneider, Erik C.; White, Gregory B.

    2006-05-01

    Currently, cellular phones constitute a significant portion of the global telecommunications market. Modern cellular phones offer sophisticated features such as Internet access, on-board cameras, and expandable memory which provide these devices with excellent multimedia capabilities. Because of the high volume of cellular traffic, as well as the ability of these devices to transmit nearly all forms of data. The need for an increased level of security in wireless communications is becoming a growing concern. Steganography could provide a solution to this important problem. In this article, we present a new algorithm for JPEG-compressed images which is applicable to mobile platforms. This algorithm embeds sensitive information into quantized discrete cosine transform coefficients obtained from the cover JPEG. These coefficients are rearranged based on certain statistical properties and the inherent processing and memory constraints of mobile devices. Based on the energy variation and block characteristics of the cover image, the sensitive data is hidden by using a switching embedding technique proposed in this article. The proposed system offers high capacity while simultaneously withstanding visual and statistical attacks. Based on simulation results, the proposed method demonstrates an improved retention of first-order statistics when compared to existing JPEG-based steganographic algorithms, while maintaining a capacity which is comparable to F5 for certain cover images.

  4. Novel Opportunistic Network Routing Based on Social Rank for Device-to-Device Communication

    Directory of Open Access Journals (Sweden)

    Tong Wang

    2017-01-01

    Full Text Available In recent years, there has been dramatic proliferation of research concerned with fifth-generation (5G mobile communication networks, among which device-to-device (D2D communication is one of the key technologies. Due to the intermittent connection of nodes, the D2D network topology may be disconnected frequently, which will lead to failure in transmission of large data files. In opportunistic networks, in case of encountering nodes which never meet before a flood message blindly to cause tremendous network overhead, a novel opportunistic network routing protocol based on social rank and intermeeting time (SRIT is proposed in this paper. An improved utility approach applied in utility replication based on encounter durations and intermeeting time is put forward to enhance the routing efficiency. Meanwhile, in order to select better candidate nodes in the network, a social graph among people is established when they socially relate to each other in social rank replication. The results under the scenario show an advantage of the proposed opportunistic network routing based on social rank and intermeeting time (SRIT over the compared algorithms in terms of delivery ratio, average delivery latency, and overhead ratio.

  5. Electrochromic device based on electrospun WO{sub 3} nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Dulgerbaki, Cigdem; Maslakci, Neslihan Nohut; Komur, Ali Ihsan; Oksuz, Aysegul Uygun, E-mail: ayseguluygun@sdu.edu.tr

    2015-12-15

    Highlights: • WO{sub 3} electrochromic nanofibers were prepared by electrospinning technique. • WO{sub 3} nanofibers switched reversibly from transparent to blue color. • Electrochromic device was assembled using ionic liquid based gel electrolyte. • Significant optical modulation and excellent cycling stability were achieved for ECD. - Abstract: The tungsten oxide (WO{sub 3}) nanofibers were grown directly onto an ITO-coated glass via an electrospinning method for electrochromic applications. The electrochromic properties of WO{sub 3} nanofibers were investigated in the presence of different electrolytes including a series of ionic liquids and classic LiClO{sub 4}-PC system. A significant optical modulation of 20.82% at 760 nm, reversible coloration with efficiency of 64.58 cm{sup 2}/C and excellent cycling stability were achieved for the nanofiber electrochromic device (ECD) with ionic liquid based gel electrolyte.

  6. Chemically modified graphene based supercapacitors for flexible and miniature devices

    Science.gov (United States)

    Ghosh, Debasis; Kim, Sang Ouk

    2015-09-01

    Rapid progress in the portable and flexible electronic devises has stimulated supercapacitor research towards the design and fabrication of high performance flexible devices. Recent research efforts for flexible supercapacitor electrode materials are highly focusing on graphene and chemically modified graphene owing to the unique properties, including large surface area, high electrical and thermal conductivity, excellent mechanical flexibility, and outstanding chemical stability. This invited review article highlights current status of the flexible electrode material research based on chemically modified graphene for supercapacitor application. A variety of electrode architectures prepared from chemically modified graphene are summarized in terms of their structural dimensions. Novel prototypes for the supercapacitor aiming at flexible miniature devices, i.e. microsupercapacitor with high energy and power density are highlighted. Future challenges relevant to graphene-based flexible supercapacitors are also suggested. [Figure not available: see fulltext.

  7. Protein sequencing via nanopore based devices: a nanofluidics perspective

    Science.gov (United States)

    Chinappi, Mauro; Cecconi, Fabio

    2018-05-01

    Proteins perform a huge number of central functions in living organisms, thus all the new techniques allowing their precise, fast and accurate characterization at single-molecule level certainly represent a burst in proteomics with important biomedical impact. In this review, we describe the recent progresses in the developing of nanopore based devices for protein sequencing. We start with a critical analysis of the main technical requirements for nanopore protein sequencing, summarizing some ideas and methodologies that have recently appeared in the literature. In the last sections, we focus on the physical modelling of the transport phenomena occurring in nanopore based devices. The multiscale nature of the problem is discussed and, in this respect, some of the main possible computational approaches are illustrated.

  8. The Biological Responses to Magnesium-Based Biodegradable Medical Devices

    Directory of Open Access Journals (Sweden)

    Lumei Liu

    2017-11-01

    Full Text Available The biocompatibility of Magnesium-based materials (MBMs is critical to the safety of biodegradable medical devices. As a promising metallic biomaterial for medical devices, the issue of greatest concern is devices’ safety as degrading products are possibly interacting with local tissue during complete degradation. The aim of this review is to summarize the biological responses to MBMs at the cellular/molecular level, including cell adhesion, transportation signaling, immune response, and tissue growth during the complex degradation process. We review the influence of MBMs on gene/protein biosynthesis and expression at the site of implantation, as well as throughout the body. This paper provides a systematic review of the cellular/molecular behavior of local tissue on the response to Mg degradation, which may facilitate a better prediction of long-term degradation and the safe use of magnesium-based implants through metal innovation.

  9. Internet-Based Device-Assisted Remote Monitoring of Cardiovascular Implantable Electronic Devices

    Science.gov (United States)

    Pron, G; Ieraci, L; Kaulback, K

    2012-01-01

    Executive Summary Objective The objective of this Medical Advisory Secretariat (MAS) report was to conduct a systematic review of the available published evidence on the safety, effectiveness, and cost-effectiveness of Internet-based device-assisted remote monitoring systems (RMSs) for therapeutic cardiac implantable electronic devices (CIEDs) such as pacemakers (PMs), implantable cardioverter-defibrillators (ICDs), and cardiac resynchronization therapy (CRT) devices. The MAS evidence-based review was performed to support public financing decisions. Clinical Need: Condition and Target Population Sudden cardiac death (SCD) is a major cause of fatalities in developed countries. In the United States almost half a million people die of SCD annually, resulting in more deaths than stroke, lung cancer, breast cancer, and AIDS combined. In Canada each year more than 40,000 people die from a cardiovascular related cause; approximately half of these deaths are attributable to SCD. Most cases of SCD occur in the general population typically in those without a known history of heart disease. Most SCDs are caused by cardiac arrhythmia, an abnormal heart rhythm caused by malfunctions of the heart’s electrical system. Up to half of patients with significant heart failure (HF) also have advanced conduction abnormalities. Cardiac arrhythmias are managed by a variety of drugs, ablative procedures, and therapeutic CIEDs. The range of CIEDs includes pacemakers (PMs), implantable cardioverter-defibrillators (ICDs), and cardiac resynchronization therapy (CRT) devices. Bradycardia is the main indication for PMs and individuals at high risk for SCD are often treated by ICDs. Heart failure (HF) is also a significant health problem and is the most frequent cause of hospitalization in those over 65 years of age. Patients with moderate to severe HF may also have cardiac arrhythmias, although the cause may be related more to heart pump or haemodynamic failure. The presence of HF, however

  10. Steering and filtering white light with resonant waveguide gratings

    Science.gov (United States)

    Quaranta, Giorgio; Basset, Guillaume; Martin, Olivier J. F.; Gallinet, Benjamin

    2017-08-01

    A novel thin-film single-layer structure based on resonant waveguide gratings (RWGs) allows to engineer selective color filtering and steering of white light. The unit cell of the structure consists of two adjacent finite-length and cross-talking RWGs, where the former acts as in-coupler and the latter acts as out-coupler. The structure is made by only one nano-imprint lithography replication and one thin film layer deposition, making it fully compatible with up-scalable fabrication processes. We characterize a fabricated optical security element designed to work with the flash and the camera of a smartphone in off-axis light steering configuration, where the pattern is revealed only by placing the smartphone in the proper position. Widespread applications are foreseen in a variety of fields, such as multifocal or monochromatic lenses, solar cells, biosensors, security devices and seethrough optical combiners for near-eye displays.

  11. Cylinder and metal grating polarization beam splitter

    Science.gov (United States)

    Yang, Junbo; Xu, Suzhi

    2017-08-01

    We propose a novel and compact metal grating polarization beam splitter (PBS) based on its different reflected and transmitted orders. The metal grating exhibits a broadband high reflectivity and polarization dependence. The rigorous coupled wave analysis is used to calculate the reflectivity and the transmitting spectra and optimize the structure parameters to realize the broadband PBS. The finite-element method is used to calculate the field distribution. The characteristics of the broadband high reflectivity, transmitting and the polarization dependence are investigated including wavelength, period, refractive index and the radius of circle grating. When grating period d = 400 nm, incident wavelength λ = 441 nm, incident angle θ = 60° and radius of circle d/5, then the zeroth reflection order R0 = 0.35 and the transmission zeroth order T0 = 0.08 for TE polarization, however, T0 = 0.34 and R0 = 0.01 for TM mode. The simple fabrication method involves only single etch step and good compatibility with complementary metal oxide semiconductor technology. PBS designed here is particularly suited for optical communication and optical information processing.

  12. Network-based Fingerprint Authentication System Using a Mobile Device

    OpenAIRE

    Zhang, Qihu

    2016-01-01

    Abstract— Fingerprint-based user authentication is highly effective in networked services such as electronic payment, but conventional authentication solutions have problems in cost, usability and security. To resolve these problems, we propose a touch-less fingerprint authentication solution, in which a mobile device's built-in camera is used to capture fingerprint image, and then it is sent to the server to determine the identity of the user. We designed and implemented a prototype as an a...

  13. Broadband back grating design for thin film solar cells

    KAUST Repository

    Janjua, Bilal; Jabbour, Ghassan E.

    2013-01-01

    In this paper, design based on tapered circular grating structure was studied, to provide broadband enhancement in thin film amorphous silicon solar cells. In comparison to planar structure an absorption enhancement of ~ 7% was realized.

  14. Aviation Fuel Gauging Sensor Utilizing Multiple Diaphragm Sensors Incorporating Polymer Optical Fiber Bragg Gratings

    DEFF Research Database (Denmark)

    Marques, C. A. F.; Pospori, A.; Saez-Rodriguez, D.

    2016-01-01

    A high-performance fuel gauging sensor is described that uses five diaphragm-based pressure sensors, which are monitored using a linear array of polymer optical fiber Bragg gratings. The sensors were initially characterized using water, revealing a sensitivity of 98 pm/cm for four of the sensors...... of sensors manufactured with a polyurethane-based diaphragm showed no measurable deterioration over a three month period immersed in fuel. These sensors exhibited a sensitivity of 39 pm/cm, which is less than the silicone rubber devices due to the stiffer nature of the polyurethane material used....

  15. WE-AB-BRA-10: Assessment of Fiber Bragg Grating (FBG)-Based Sensing for Real-Time Needle Tracking During MR-Guided Brachytherapy

    International Nuclear Information System (INIS)

    Borot de Battisti, M; Maenhout, M; Lagendijk, J J W; Van Vulpen, M; Moerland, M A; Denis de Senneville, B; Hautvast, G; Binnekamp, D

    2016-01-01

    Purpose: This study assesses the potential of Fiber Bragg Grating (FBG)-based sensing for real-time needle (including catheter or tube) tracking during MR-guided HDR brachytherapy. Methods: The proposed FBG-based sensing tracking approach involves a MR-compatible stylet composed of three optic fibers with nine sets of embedded FBG sensors each. When the stylet is inserted inside the lumen of the needle, the FBG sensing system can measure the needle’s deflection. For localization of the needle in physical space, the position and orientation of the stylet base are mandatory. For this purpose, we propose to fix the stylet base and determine its position and orientation using a MR-based calibration as follows. First, the deflection of a needle inserted in a phantom in two different configurations is measured during simultaneous MR-imaging. Then, after segmentation of the needle shapes on the MR-images, the position and orientation of the stylet base is determined using a rigid registration of the needle shapes on both MR and FBG-based measurements. The calibration method was assessed by measuring the deflection of a needle in a prostate phantom in five different configurations using FBG-based sensing during simultaneous MR-imaging. Any two needle shapes were employed for the calibration step and the proposed FGB-tracking approach was subsequently evaluated on the other three needles configurations. The tracking accuracy was evaluated by computing the Euclidian distance between the 3D FBG vs. MR-based measurements. Results: Over all needle shapes tested, the average(standard deviation) Euclidian distance between the FBG and MR-based measurements was 0.79mm(0.37mm). The update rate and latency of the FBG-based measurements were 100ms and 300ms respectively. Conclusion: The proposed FBG-based protocol can measure the needle position with an accuracy, precision, update rate and latency eligible for accurate needle steering during MR-guided HDR brachytherapy. M. Borot de

  16. An UV photochromic memory effect in proton-based WO3 electrochromic devices

    International Nuclear Information System (INIS)

    Zhang Yong; Lee, S.-H.; Mascarenhas, A.; Deb, S. K.

    2008-01-01

    We report an UV photochromic memory effect on a standard proton-based WO 3 electrochromic device. It exhibits two memory states, associated with the colored and bleached states of the device, respectively. Such an effect can be used to enhance device performance (increasing the dynamic range), re-energize commercial electrochromic devices, and develop memory devices

  17. An UV photochromic memory effect in proton-based WO3 electrochromic devices

    Science.gov (United States)

    Zhang, Yong; Lee, S.-H.; Mascarenhas, A.; Deb, S. K.

    2008-11-01

    We report an UV photochromic memory effect on a standard proton-based WO3 electrochromic device. It exhibits two memory states, associated with the colored and bleached states of the device, respectively. Such an effect can be used to enhance device performance (increasing the dynamic range), re-energize commercial electrochromic devices, and develop memory devices.

  18. The potential of diffraction grating for spatial applications

    Science.gov (United States)

    Jourlin, Y.; Parriaux, O.; Pigeon, F.; Tischenko, A. V.

    2017-11-01

    Diffraction gratings are know, and have been fabricated for more than one century. They are now making a come back for two reasons: first, because they are now better understood which leads to the efficient exploitation of what was then called their "anomalies"; secondly, because they are now fabricable by means of the modern manufacturing potential of planar technologies. Novel grating can now perform better than conventional gratings, and address new application fields which were not expected to be theirs. This is the case of spatial applications where they can offer multiple optical functions, low size, low weight and mechanical robustness. The proposed contribution will briefly discuss the use of gratings for spatial applications. One of the most important applications is in the measurement of displacement. Usual translation and rotation sensors are bulky devices, which impose a system breakdown leading to cumbersome and heavy assemblies. We are proposing a miniaturized version of the traditional moving grating technique using submicron gratings and a specific OptoASIC which enables the measurement function to be non-obtrusively inserted into light and compact electro-mechanical systems. Nanometer resolution is possible with no compromise on the length of the measurement range. Another family of spatial application is in the field of spectrometers where new grating types allow a more flexible processing of the optical spectrum. Another family of applications addresses the question of inter-satellite communications: the introduction of gratings in laser cavities or in the laser mirrors enables the stabilization of the emitted polarization, the stabilization of the frequency as well as wide range frequency sweeping without mobile parts.

  19. A cloud-based multimodality case file for mobile devices.

    Science.gov (United States)

    Balkman, Jason D; Loehfelm, Thomas W

    2014-01-01

    Recent improvements in Web and mobile technology, along with the widespread use of handheld devices in radiology education, provide unique opportunities for creating scalable, universally accessible, portable image-rich radiology case files. A cloud database and a Web-based application for radiologic images were developed to create a mobile case file with reasonable usability, download performance, and image quality for teaching purposes. A total of 75 radiology cases related to breast, thoracic, gastrointestinal, musculoskeletal, and neuroimaging subspecialties were included in the database. Breast imaging cases are the focus of this article, as they best demonstrate handheld display capabilities across a wide variety of modalities. This case subset also illustrates methods for adapting radiologic content to cloud platforms and mobile devices. Readers will gain practical knowledge about storage and retrieval of cloud-based imaging data, an awareness of techniques used to adapt scrollable and high-resolution imaging content for the Web, and an appreciation for optimizing images for handheld devices. The evaluation of this software demonstrates the feasibility of adapting images from most imaging modalities to mobile devices, even in cases of full-field digital mammograms, where high resolution is required to represent subtle pathologic features. The cloud platform allows cases to be added and modified in real time by using only a standard Web browser with no application-specific software. Challenges remain in developing efficient ways to generate, modify, and upload radiologic and supplementary teaching content to this cloud-based platform. Online supplemental material is available for this article. ©RSNA, 2014.

  20. A reconfigurable optofluidic Michelson interferometer using tunable droplet grating.

    Science.gov (United States)

    Chin, L K; Liu, A Q; Soh, Y C; Lim, C S; Lin, C L

    2010-04-21

    This paper presents a novel optofluidic Michelson interferometer based on droplet microfluidics used to create a droplet grating. The droplet grating is formed by a stream of plugs in the microchannel with constant refractive index variation. It has a real-time tunability in the grating period through varying the flow rates of the liquids and index variation via different combinations of liquids. The optofluidic Michelson interferometer is highly sensitive and is suitable for the measurement of biomedical and biochemical buffer solutions. The experimental results show that it has a sensitivity of 66.7 nm per refractive index unit (RIU) and a detection range of 0.086 RIU.