2,275 research outputs found
Sensitivity enhancement of integrated optics sensors by thin high index films
No full textExperimental measurements on waveguide Mach-Zehnder interferometers are presented which show that order of magnitude improvements in the sensitivity of planar waveguide sensors can be achieved by incorporating thin high index overlays
Sensitivity enhancement of integrated optical sensors by use of thin high-index films
No full textThe proportion of power carried in the superstrate medium by the guided modes of integrated optical waveguides can be increased by the addition of a thin high index film. Enhanced refractive index sensing is demonstrated using channel waveguide Mach-Zehnder interferometers with Ta2O5 overlayers. Sensitivity increases by a factor greater than 50, and a detection limit better than 5x10-7 are obtained. This approach is broadly applicable to sensing at waveguide surfaces where the strength of evanescent fields dictates performance
Integrated optical dual Mach-Zehnder interferometer sensor
No full textThe fabrication and operation of robust integrated optical refractometers, suitable for precise measurements of small changes without ambiguity over a wide range of refractive indices, is described. The design primarily uses an optical fibre coupled dual-sensitivity integrated optical Mach-Zehnder Interferometer sensor chip incorporating 3x3 directional coupler combiners and internal referencing. High-index Ta2O5 films were deposited on the waveguide surface in order to increase sensitivity and measurements of their response to liquid analyte index have been carried out by passing aqueous sucrose solutions over the sensor surface. These devices are intended for application as high-sensitivity multi-purpose chemical sensors and biosensors
Autograph of Jimmy Elaine Wilkinson Meyer in "Any Friend of the Movement"
No full textThe title page and an autograph by the author, Jimmy Elaine Wilkinson Meyer, in their work ""Any Friend of the Movement: Networking for Birth Control 1920-1940"" with an inscription.Gloria- Kudos and thanks for your labors and inspiration. Looking to better days ahead. Jimmy Meye
Crystal Wilkinson: 48th Annual ODU Literary Festival
No full textCrystal Wilkinson, a recent recipient of a Writing Freedom fellowship, is the award-winning author of Praisesong for the Kitchen Ghosts, a national-bestselling culinary memoir, Perfect Black, a collection of poems, and three works of fiction—The Birds of Opulence, Water Street and Blackberries, Blackberries. She is the recipient of an NAACP Image Award for Outstanding Poetry, an O. Henry Prize, an Academy of American Poets Fellowship, a USA Artists Fellowship, and an Ernest J. Gaines Prize for Literary Excellence. She has received recognition from the Yaddo Foundation, Hedgebrook, The Vermont Studio Center for the Arts, The Hermitage Foundation and others. Her short stories, poems and essays have appeared in numerous journals and anthologies including most recently in The Atlantic, The Kenyon Review, STORY, Agni Literary Journal, Emergence, Oxford American and Southern Cultures. She was Poet Laureate of Kentucky from 2021 to 2023. She currently teaches creative writing at the University of Kentucky where she is a Bush-Holbrook Endowed Professor and Director of the Division of Creative Writing. Her memoir Heartsick is forthcoming from Crown
Crystal Wilkinson
No full textPublicity photo submitted by author/presenter for ODU\u27s Annual Literary Festival 2025.https://digitalcommons.odu.edu/litfest_images/1018/thumbnail.jp
Ti-diffusion in sapphire for active and passive waveguide devices
No full textFollowing the recent realisation of a Ti:sapphire waveguide laser by Ti-indiffusion, the relation between diffusion conditions, waveguide properties and Ti spectroscopy is discussed in depth with a view to developing a next-generation device
Waveguide immunofluorescence sensor for water pollution analysis
No full textA regenerable channel waveguide fluorescence sensor for environmental monitoring is reported. The sensor has been characterised as a detector of the pesticide 2,4 dichlorophenoxyacetic acid. A binding inhibition assay, using fluorescent Cy5.5 dye-labelled antibodies, was monitored at the modified surface of the glass waveguide to detect the target analyte. Three calibration curves were determined and averaged. The averaged calibration curve has a mid-point of 0.68 ppb and a calculated detection limit of 0.28 ppb. Incorporation of a 20 nm thick tantalum pentoxide film at the waveguide surface enhanced the peak fluorescence signal by a factor of approximately 6 compared with an uncoated sensor. Due to the high optical field strengths at the surface of the waveguide, which is approximately 10µm wide, significant photobleaching of the dye molecules occurs. The rate of photobleaching will be reduced if the power density of the excitation radiation at the surface of the waveguide is reduced, offering the potential for enhanced device sensitivity. This may be achieved, without reducing the total power, by broadening the 10µm wide optical waveguide through a tapered region to a final width in excess of 50µm. A distinct advantage of this broadening is to improve the signal to noise ratio of the sensor as the number of bound fluorophores at the waveguide surface increases linearly with the waveguide width. Theoretical modelling of tapered waveguides, using a beam propagation method package, has indicated that the peak field intensity of radiation in the 10µm guide may be reduced by 85% if the guide is broadened through a taper to a final width of 50µm
UV-written channel waveguides in ion-exchanged Pyrex
No full textIn this paper we demonstrate that a positive change in refractive index can be induced by UV radiation in bulk Pyrex, an inexpensive, commercially available glass that is not specifically designed to be photosensitive. We describe the fabrication of channel waveguides in Pyrex by direct UV writing and show that a potassium-ion exchanged layer can be used to host single mode waveguides. The change in refractive index due to the UV writing is found to be 2x10-3
Immunofluorescence sensor for water analysis
No full textWe demonstrated a bulk optical fluorescence based immunosensor capable for multianalyte water analysis. Calibration curves obtained for 2,4-dichlorophenoxyacetic acid (2,4-D) and simazine had detection limits of 0.035 µg/l and 0.026 µg/1 respectively. The sensor is reusable due to its regenerability and cost effective due to the use of components customary in the trade. Ways to further enhance device sensitivity by means of a high index film deposited on the sensor surface or by employing an integrated optical waveguide as transducer are presented. A concept for the detection of a varying range of analytes on the same transducer is discussed
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