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Now showing items 1 - 16 of 43657

  • Terahertz Hollow Core Antiresonant Fiber with Metamaterial Cladding

    Sultana, Jakeya   Islam, Md. Saiful   Cordeiro, Cristiano M. B.   Dinovitser, Alex   Kaushik, Mayank   Ng, Brian W.-H.   Abbott, Derek  

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  • Agarose-based structured optical fibre

    Fujiwara, Eric   Cabral, Thiago D.   Sato, Miko   Oku, Hiromasa   Cordeiro, Cristiano M. B.  

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  • A Hi-Bi Ultra-Sensitive Surface Plasmon Resonance Fiber Sensor

    Islam, Md. Saiful   Cordeiro, Cristiano M. B.   Sultana, Jakeya   Aoni, Rifat Ahmmed   Feng, Shilun   Ahmed, Rajib   Dorraki, Mohsen   Dinovitser, Alex   Ng, Brian W.-H.   Abbott, Derek  

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  • All-Optical Fiber Anemometer Based on the Pitot-Static Tube

    Fujiwara, Eric   Delfino, Tiago S.   Cabral, Thiago D.   Cordeiro, Cristiano M. B.  

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  • Optical Fiber Anemometer Based on a Multi-FBG Curvature Sensor

    Fujiwara, Eric   Hayashi, Juliano G.   Delfino, Tiago S.   Jorge, Pedro A. S.   Cordeiro, Cristiano M. B.  

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  • Optical sensing with antiresonant capillary fibers

    Osorio, Jonas H.   Marques, Thiago H. R.   Figueredo, Igor C.   Serrao, Valdir A.   Franco, Marcos A. R.   Cordeiro, Cristiano M. B.  

    Herein, we present a study of the use of polymer capillary optical fibers in sensing measurements. In particular, we approach the application of these fibers for temperature sensing. To do this, an analytical model for describing the spectral characteristics of the light transmitted through the capillaries was employed. Thermal expansion and thermooptic effect influences on the transmitted spectrum were evaluated. Moreover, a 140 +/- 6 pm/degrees C temperature sensitivity was measured, which is in good resemblance to simulated data and is around 14 times higher than the sensitivity attained in conventional Bragg gratings sensors.
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  • Vibration and Magnetic Field Sensing Using a Long-Period Grating

    Nascimento, Ivo M.   Chesini, Giancarlo   Baptista, Jose Manuel   Cordeiro, Cristiano M. B.   Jorge, Pedro A. S.  

    A long-period grating (LPG) written on a standard single mode fiber is investigated as a fiber optic sensor for vibration and magnetic field sensing. It is demonstrated the high sensitivity of the device to applied curvature and the possibility to monitor vibration in a wide range of frequencies from 30 Hz to 2000 Hz. The system was tested using intensity-based interrogation scheme, providing a frequency discrimination of 913 mHz. The goal of these tests was to evaluate the sensor as a passive vibration monitor in the detection of changes in resonant vibration frequencies of support infrastructures can provide information on its degradation. Furthermore, taking advantage of the intrinsic sensitivity to micro strain, alternating magnetic fields were also measured using an intensity-based interrogation scheme by coupling a Terfenol-D magnetostrictive rod to a pre-strained LPG sensor, providing a resolution below 5.61 mu T-rms/root Hz from 1.22 mT(rms) up to 2.53 mT(rms).
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  • Simplifying the design of microstructured optical fibre pressure sensors

    Osorio, Jonas H.   Chesini, Giancarlo   Serrao, Valdir A.   Franco, Marcos A. R.   Cordeiro, Cristiano M. B.  

    In this paper, we propose a way to simplify the design of microstructured optical fibres with high sensitivity to applied pressure. The use of a capillary fibre with an embedded core allows the exploration of the pressure-induced material birefringence due to the capillary wall displacements and the photoelastic effect. An analytical description of pressure-induced material birefringence is provided, and fibre modal characteristics are explored through numerical simulations. Moreover, a capillary fibre with an embedded core is fabricated and used to probe pressure variations. Even though the embedded-core fibre has a non-optimized structure, measurements showed a pressure sensitivity of (1.04 +/- 0.01(nm/bar, which compares well with more complex, specially designed fibre geometries reported in the literature. These results demonstrate that this geometry enables a novel route towards the simplification of microstructured fibre-based pressure sensors.
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  • Bragg Gratings Inscription in Highly Birefringent Microstructured POFs

    Oliveira, Ricardo   Bilro, Lucia   Marques, Thiago H. R.   Napierala, Marek   Tenderenda, Tadeusz   Mergo, Pawel   Nasilowski, Tomasz   Cordeiro, Cristiano M. B.   Nogueira, Rogerio  

    We report for the first time, the fast inscription of high-quality Bragg gratings in highly birefringent microstructured polymer optical fibers by the phase mask method using 248-nm UV radiation. The fibers birefringence is created through a special design of the structure of holes through the fiber. A Bragg grating in these type of fibers allows the creation of two reflection peaks, where the peak separation is related to the phase birefringence.
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  • Dual-environment pressure sensor using a photonic-crystal fiber

    Osorio, Jonas H.   Hayashi, Juliano G.   Espinel, Yovanny A. V.   Franco, Marcos A. R.   Andres, Miguel V.   Cordeiro, Cristiano M. B.  

    In this paper, we report the development of a side-hole photonic-crystal fiber (SH-PCF) based dual-environment pressure sensor. SH-PCF sensitivity to pressure variations was measured and compared to simulated data. SH-PCF sensitivity was found to be 2.8 times higher than the one presented by the commercial PM-1550-01 fiber. For probing two environments, one spliced two sections of the studied SH-PCF with different lengths in a solc-filter-like configuration. Individual responses of the first and second fiber can be independently obtained in this setup. Therefore, making use of SH-PCF sensitivity to pressure variations, a pressure sensor for dual environment monitoring is build up.
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  • Tapered GRIN fiber microsensor

    Beltran-Mejia, Felipe   Biazoli, Claudecir R.   Cordeiro, Cristiano M. B.  

    The sensitivity of an optical fiber microsensor based on inter-modal interference can be considerably improved by tapering a short extension of the multimode fiber. In the case of Graded Index fibers with a parabolic refractive index profile, a meridional ray exhibits a sinusoidal path. When these fibers are tapered, the period of the propagated beam decrease down-taper and increase up-taper. We take advantage of this modulation -along with the enhanced overlap between the evanescent field and the external medium- to substantially increase the sensitivity of these devices by tuning the sensor's maximum sensitivity wavelength. Moreover, the extension of this device is reduced by one order of magnitude, making it more propitious for reduced space applications. Numerical and experimental results demonstrate the success and feasibility of this approach. (C) 2014 Optical Society of America
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  • Optical sensor based on two in-series birefringent optical fibers

    Osorio, Jonas H.   Cordeiro, Cristiano M. B.  

    An optical fiber sensor based on the combination of two spliced birefringent optical fiber sections is proposed in this paper. The sensor is built up in a Solc-filter-like configuration and a simple theoretical model based on Jones matrices is employed to predict experimental results. By choosing the suitable birefringent optical fibers (e.g., photonic crystal fibers, birefringent microfibers, elliptical core fibers, PANDA fibers, etc.), the sensor described herein allows for probing of two physical parameters (e.g., refractive index and temperature, hydrostatic pressure and temperature) or sensing the same parameter in two disconnected environments. In order to demonstrate the sensor performance, the system response was evaluated in a temperature-sensing measurement. (C) 2013 Optical Society of America
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  • Novel Sealing Technique for Practical Liquid-Core Photonic Crystal Fibers

    Gerosa, Rodrigo M.   Bozolan, Alexandre   de Matos, Christiano J. S.   Romero, Murilo A.   Cordeiro, Cristiano M. B.  

    In this letter, we describe a simple and effective technique to prevent evaporation in liquid-core photonic crystal fibers (PCFs). The technique consists of using a micropipette to deploy a micro-droplet of an ultraviolet curable polymer adhesive in both core inputs. After it is cured, the adhesive creates sealing polymer plugs with quite satisfactory insertion loss (overall optical transmission of about 15%). Processed fibers remained liquid-filled for at least six weeks. From a practical point of view, we conducted a supercontinuum generation experiment in a water-core PCF to demonstrate a 120-minute spectral width stability and the ability to withstand at least 3-mW average power at the sealed fiber input. Similar experiments carried out with nonsealed fibers produced supercontinuum spectra lasting no longer than 10 minutes, with average powers kept below 0.5 mW to avoid thermally induced evaporation.
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  • Multiparameter POF Sensing Based on Multimode Interference and Fiber Bragg Grating

    Oliveira, Ricardo   Marques, Thiago H. R.   Bilro, Lucia   Nogueira, Rogerio   Cordeiro, Cristiano M. B.  

    We report the fabrication of a multimode interferometer (MMI), based on a multimode polymer optical fiber (POF), sandwiched between two single-mode silica fibers. The POF used in this work is a step-index fiber with core and cladding composed of a cycloolefin polymer (COP) and PMMA, respectively. The low moisture absorption of the COP material and the benefit of having an exposed core for refractive indexmeasurements in MMI devices lead us to perform an etching of the PMMAlayer. Additionally, we report the inscription of a Bragg grating in the COP core material of an etched single-mode-multimode-single-mode (SMS) structure. The two fiber structures were simultaneously characterized to strain, temperature, humidity, and refractive index. The ability to detect refractive index by using a POF-based SMS structure is reported for the first time in this paper. Additionally, the capability for dual parameter measurement was discussed using both FBG and SMS structures.
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  • High sensitivity LPG Mach-Zehnder sensor for real-time fuel conformity analysis

    Osorio, Jonas H.   Mosquera, L.   Gouveia, Carlos J.   Biazoli, Claudecir R.   Hayashi, Juliano G.   Jorge, Pedro A. S.   Cordeiro, Cristiano M. B.  

    A high sensitivity refractive index sensor based on the combination of mechanically induced long period gratings (LPG) and fiber tapers was developed for real-time fuel quality analysis. The sensor was built in a Mach-Zehnder configuration by employing a pair of in-series gratings. In order to enhance sensor sensitivity, the region between both LPGs was tapered down from 125 to 10 mu m. The system was tested by measuring water concentration in ethanol and ethanol concentration in commercial gasoline. The tapered sensor has shown an average sensitivity of 930 nm/RIU, 18 times higher than the non-tapered version. The resolution limit of the system using spectral interrogation was estimated to be 0.06% of ethanol dissolved in gasoline. For the purpose of real-time monitoring, an interrogation system based on white light interferometry (WLI) and virtual instrumentation was employed to evaluate ethanol evaporation in water, avoiding the use of spectral analysis. The WLI system, using phase tracking techniques, enabled us to record the evolution of the ethanol concentration in water with a resolution of 0.005% (v/v).
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  • Side-hole Photonic Crystal Fibers

    Cordeiro, Cristiano M. B.   Espinel, Yovanny A. V.   Hayashi, Juliano G.   Chesini, Giancarlo   Franco, Marcos A. R.  

    A new class of photonic crystal fiber, namely side-hole PCF, is analyzed and demonstrated. The presence of massive holes surrounding a microstructured cladding allows the realization of devices based on PCFs with integrated electrodes and fibers with high pressure sensitivity. The side holes can also be used to produce ultrahigh birefringence fibers based on squeezed-lattice structures and tunable single-polarization single-mode polymeric microstructured fibers.
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