38 research outputs found
Fusion splicing soft-glass suspended core fibers to solid silica fibers for optical fiber sensing
No full textWe report fusion splicing of soft-glass suspended small-core fibers to conventional silica single-mode fibers for integration with conventional fiber systems. Heat-induced damage to the microstructured fiber region is minimized by using a low-power iridium filament.Florian V. Englich, Erik P. Schartner, Dominic F. Murphy, Heike Ebendorff-Heidepriem, and Tanya M. Monr
Detection of molecular oxygen by magnetic field interaction with guided light within an optical fiber
No full textExtent: 4p.We report a novel fiber-optic sensing architecture for the detection of paramagnetic gases that exploits the interaction of a magnetic field with guided light to detect an active gaseous medium within a hollow-core photonic bandgap fiber. This first demonstration of a fiber-based Faraday Rotation Spectroscopy (FRS) sensor operates at 762.309 nm for the detection of molecular oxygen. The optical fiber sensor has a 14.8 cm long sensing region and 4.2 nL detection volume. A measured FRS spectrum with a signal-to-noise ratio of 9.5 proves the principle of this new gas sensor architecture.Florian V. Englich and Tanya M. Monr
Magnetic field interaction with guided light for detection of an active gaseous medium within an optical fiber
No full textLink to a related website: http://pdfs.semanticscholar.org/04fc/a944490d6b18d0104358fe85193c48acb092.pdf, Open Access via UnpaywallWe report a novel fiber-optic sensing architecture for the detection of paramagnetic gases. By interacting a modulated magnetic field with guided light within a microstructured optical fiber, it is possible to exploit Faraday Rotation Spectroscopy (FRS) within unprecedentedly small sample volumes. This approach, which utilizes magnetic circularbirefringence and magnetic circular dichroism effects, is applied to a photonic bandgap fiber to detect molecular oxygen and operates at a wavelength of 762.309 nm. The optical fiber sensor has a 4.2 nL detection volume and 14.8 cm long sensing region. The observed FRS spectra are compared with a theoretical model that provides a first nderstanding of guided-mode FRS signals. This FRS guided-wave sensor offers the prospect of new compact sensing schemes.Florian V. Englich, Michal Grabka, David G. Lancaster, and Tanya M. Monr
Simultaneous multi-laser, multi-species trace-level sensing of gas mixtures by rapidly swept continuous-wave cavity-ringdown spectroscopy
No full textThe greenhouse-gas molecules CO2, CH4, and H2O are detected in air within a few ms by a novel cavity-ringdown laser-absorption spectroscopy technique using a rapidly swept optical cavity and multi-wavelength coherent radiation from a set of pre-tuned near-infrared diode lasers. The performance of various types of tunable diode laser, on which this technique depends, is evaluated. Our instrument is both sensitive and compact, as needed for reliable environmental monitoring with high absolute accuracy to detect trace concentrations of greenhouse gases in outdoor air.Yabai He, Ruifeng Kan, Florian V. Englich, Wenqing Liu and Brian J. Or
A microstructured optical fiber sensor for ion-sensing based on the photoinduced electron transfer effect
No full textWe employ the photoinduced electron transfer (PET) effect within suspended-core microstructured optical fiber to authenticate a new type of fluorescence based sensor for ion detection. A sensor design based on a simple model PET-fluoroionophore system and small core microstructured optical fiber is shown and the operational performance of the sensor to different concentrations of sodium is investigated. Future approaches to improving the sensor’s signal stability and sensitivity are discussed.Andrew C. Richardson, Tze Cheung Foo, Florian V. Englich, Heike Ebendorff-Heidepriem, Christopher J. Sumby and Tanya M. Monr
Ammonia detection using near infrared diode laser based overtone spectroscopy
No full textWe describe a portable diode-laser-based sensor for NH3 detection using vibrational overtone absorption spectroscopy at 1.53 mm. Use of fiber-coupled optical elements makes such a trace gas sensor rugged and easy to align. On-line data acquisition and processing requiring ,30 s can be performed with a laptop PC running LabVIEW software. The gas sensor was used primarily for NH3 concentration measurements with a sensitivity of 0.7 parts per million ~signal-to-noise ratio of 3! over a two-week period in a bioreactor being developed at the NASA Johnson Space Center for water treatment technologies to support long-duration space missions. The feasibility of simultaneous, real-time measurements of NH3 and CO2 concentrations is also reported.Ricardo Claps, Florian V. Englich, Darrin P. Leleux, Dirk Richter, Frank K. Tittel, and Robert F. Cur
Nízkoteplotní polarizovaný terč protonů pro studium struktury nukleonů v experimentu COMPASS
No full textNázev práce: Nízkoteplotní protonový polarizovaný terč pro studium struktury nukleonů v experimentu COMPASS Autor: Michael Pešek Katedra / Ústav: Katedra fyziky nízkých teplot Vedoucí bakalářské práce: prof. Ing. Miroslav Finger, DrSc., Katedra fyziky nízkých teplot Abstrakt: V této práci jsou prezentovány základní přehledy hlubokého nepružného rozptylu a procesu dynamické jaderné polarizace. Je kladen důraz na důležidost určení polarizace pro studium spinové struktury nukleonu. Následuje popis experimentu COMPASS s důrazem na popis nízkoteplotního polarizovaného terče. Je popsána obecná procedura pro určení polarizace a určena polarizace a relaxační doby pro běh experimentu v roce 2010. Klíčová slova: struktura nukleonu, polarizovaný protonový terč, nízké teploty, metoda NMRTitle: Low temperature proton polarized target for nucleon structure studies at COMPASS Author: Michael Pešek Department / Institute: Department of Low temperature Physics Supervisor of the bachelor thesis: prof. Ing. Miroslav Finger, DrSc., Department of Low Temperature Physics Abstract: Overview of basics of deep inelastic scattering and process of dynamic nuclear polarization with emphasis to importance of precise polarization determination for nucleon spin structure studies are given. This is followed by description of COMPASS experiment with emphasis given to low temperature polarized target. General procedure of NMR data analysis is given and finally polarization for run 2010 and relaxations rates are determined. Keywords: nucleon structure, polarized proton target, low temperatures, NMR techniqueKatedra fyziky nízkých teplotDepartment of Low Temperature PhysicsMatematicko-fyzikální fakultaFaculty of Mathematics and Physic
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Measurements of NH3 and CO2 with distributed-feedback diode lasers near 2.0 µm in bioreactor vent gases
No full textWhen this research was performed, M. E. Webber, J. B. Jeffries and R. K. Hanson were with the
High Temperature Gasdynamics Laboratory, Department of Mechanical
Engineering, Stanford University. M. E. Webber is now with Pranalytica, Inc.
When this research was performed, R. Claps, F. V. Englich, and
F. K. Tittel were with the Laser Science Group, Rice Quantum
Institute, Department of Electrical and Computer Engineering,
Rice University. R. Claps is now
with Radiant Photonics, Inc.Measurements of NH3 and CO2 were made in bioreactor vent gases with distributed-feedback diode-laser
sensors operating near 2 um. Calculated spectra of NH3 and CO2 were used to determine the optimum
transitions for interrogating with an absorption sensor. For ammonia, a strong and isolated absorption
transition at 5016.977 cm-1 was selected for trace gas monitoring. For CO2, an isolated transition at
5007.787 cm-1 was selected to measure widely varying concentrations [500 parts per million (ppm) to
10%], with sufficient signal for low mole fractions and without being optically thick for high mole
fractions. Using direct absorption and a 36-m total path-length multipass flow-through cell, we achieved
a minimum detectivity of 0.25 ppm forNH3 and 40 ppm for CO2. We report on the quasi-continuous field
measurements of NH3 and CO2 concentration in bioreactor vent gases that were recorded at NASA
Johnson Space Center with a portable and automated sensor system over a 45-h data collection window.Mechanical Engineerin
Theoretical modeling of the Faraday effect within a gas-filled photonic bandgap fiber
No full textAlso published as a book chapter: Fifth European Workshop on Optical Fibre Sensors / L. R. Jaroszewicz (ed.):87942MRecently we have demonstrated that conventional (free-space) Faraday rotation spectroscopy (FRS) can be successfully transitioned into optical fiber-based sensing architectures using paramagnetic gas-filled hollow-core photonic bandgap fibers (HC-PCFs)1. Our measurements revealed that due to the birefringence properties of the HC-PCFs, behavior of the fiber-optic FRS signals is substantially different compared to free-space FRS systems. Furthermore, magnetic circular dichroism tends to have much higher influence on the FRS signals than in other systems. To explain this behavior we have developed a theoretical model, and shown that close agreement with the experimental data can be achieved. In this paper we focus attention on the detailed explanation and the in-depth discussion of the model and assumptions incorporated within it. This approach can be easily extended to account for parasitic effects that take place in real-world FRS sensor systems such as imperfect polarizers or birefringent gas cell windows. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.Michal Grabka, Florian V. Englich, David G. Lancaster, Wojciech Gawlik, and Tanya M. Monr
Guided-mode based Faraday rotation spectroscopy within a photonic bandgap fiber
No full textAlso published as a book chapter: Photonic and Phononic Properties of Engineered Nanostructures III, 2013 / Ali Adibi, Shawn-Yu Lin, Axel Scherer (eds.): 86320LMicrostructured optical fibers provide a unique environment for new compact sensing of gases as they offer advantages including long optical pathlengths, strong confinement of high power light and extremely small sample volumes compared to free-space gas sensing architectures. Here we investigate the interaction of a modulated magnetic field with guided light to detect a paramagnetic active gaseous medium within a hollow-core photonic bandgap fiber (HC-PCF). This novel fiber-optic approach to Faraday Rotation Spectroscopy (FRS) demonstrates the detection of molecular oxygen at 762.309 nm with nano-liter detection volume. By using a differential detection scheme for improved sensitivity, guided-mode FRS spectra were recorded for different coupling conditions of the light (i.e., different light polarization angles) and various gas sample pressures. The observed FRS signal amplitudes and shapes are influenced by the structural properties of the fiber, and magneto-optical properties of the gas sample including the magnetic circular birefringence (MCB) and the magnetic circular dichroism (MCD). A theoretical model has been developed to simulate such FRS signals, which are in good agreement with the observed experimental results and provide a first understanding of guided-mode FRS signals and dynamics of the magneto-optical effects inside the optical fiber. The results show that microstructured optical fibers can offer a unique platform for studies concerning the propagation of light in linearly and circularly birefringent media.Florian V. Englich, Michal Grabka, David G. Lancaster, Tanya M. Monr
