Browsing by Author "Jarzebinska, Renata"

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    Multiplexing a serial array of tapered optical fibre sensors using coherent optical frequency domain reflectometry
    (Iop Publishing Ltd, 2012-08-01T00:00:00Z) Jarzebinska, Renata; Chehura, Edmon; James, Stephen W.; Tatam, Ralph P.
    The use of high spatial resolution optical frequency domain reflectometry (OFDR) to facilitate the multiplexing of a serial array of tapered optical fibre sensors is presented. Changes in the attenuation of the Rayleigh backscattered signal from the tapered regions are used to monitor the refractive index of the surrounding medium. The use of an array of five tapered regions to monitor liquid flow is demonstrated. An analysis of the performance of the system shows that, for tapers of diameter 50µm, up to nine tapers could be multiplexed using commercial OFDR instrumentation.
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    Optical Gas Sensor Fabrication Based on Porphyrin-Anchored Electrostatic Self-Assembly onto Tapered Optical Fibers
    (Taylor & Francis, 2012-07-31T00:00:00Z) Jarzebinska, Renata; Korposh, Sergiy; James, Stephen W.; Batty, William J.; Tatam, Ralph P.; Lee, Seung-Woo
    Tapered optical fibers with nano-assembled coatings of thicknesses of order tens of nanometres were used for the detection of ammonia gas. The film coating was composed of alternate layers of tetrakis-(4-sulfophenyl) porphine (TSPP) and poly(allylamine hydrochloride) (PAH), which were deposited using the electrostatic self-assembly process (ESA). Exposure of a PAH/TSPP nano-assembled non-adiabatic tapered optical fiber with a waist diameter of 10µm to ammonia induced significant optical changes in the transmission spectrum of the optical fiber. The fiber optic sensor showed a linear sensitivity to the concentration of ammonia in the range of 10-100ppm, with response and recovery times less than 100 and 240sec, respectively. The 3σ limit of detection (LOD) was estimated to be ca. 2ppm.
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    Tapered optical fibre sensors employing nanostructured coatings
    (Cranfield University, 2010-05) Jarzebinska, Renata; James, Stephen W.; Tatam, Ralph P.
    Tapered optical fibres have been manufactured, characterised and studied. These are compact devices made from single-mode optical fibre. A system for producing tapers has been developed, employing flame heating of the optical fibre and computer controlled rotation stages to stretch the fibre in a controlled and repeatable fashion. Subsequently tapered fibres were coated with nanostructured films of materials that change their optical properties in response to an external stimulus. An investigation of the effect of depositing chemically sensitive nano-scale films onto tapered optical fibres has been undertaken. Three different methods of deposition were applied: Langmuir-Blodgett technique, electrostatic-self-assembly and – for the first time - chemical grafting. Six different films of materials were deposited onto tapered fibres: 4-[2-(4-dimethylamino- naphtalen-1-yl)-vinyl]-1-octadecyl-quinolinium iodide (merocyanine dye), calix[4]resorcinarene, bilayers of poly(allyamine hydrochloride) (PAH) and anionic tetrakis(4-sulfophenyl)porphine (TSPP), PAH and cyclodextrine, TiO2 nanoparticles imprinted with ((1-(4-Nitrophenylazo)-2-naphthol (NPAN) compound), polyaniline (PANI). During the deposition process the light was launched into each fibre and the evolution of the transmission spectrum observed. The coated tapers were subsequently investigated for their potential application as chemical sensors: pH, red-ox, ammonia sensors. The response to a stimulus was investigated by immersing the coated tapered fibre in an environment containing the measurand. The properties of these devices were also used in combination other photonics concepts, such as fibre Bragg gratings written in the tapered region of a fiber, under investigation within the Engineering Photonics Group to develop new sensor elements.