Dissertations / Theses on the topic 'Tapered Fibre'
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1
Mortimore, David Bryan. "Tapered fibre devices for optical fibre communication systems." Thesis, University of Essex, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296363.
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Farwell, Selina Gail. "Fused tapered fibre optic devices." Thesis, University of Southampton, 1997. https://eprints.soton.ac.uk/394564/.
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This thesis is concerned with the realisation of an all-fibre acousto-optic device which can be used as a switch, filter, frequency shifter, polarisation controller or amplitude modulator, depending on the configuration. The devices are based on the acousto-optic interaction in fused tapered couplers and as such are completely compatible with fibre networks. For the first time polarisation insensitive devices have been realised by precisely controlling the degree of fibre fusion in an asymmetric coupler. This thesis details the theoretical considerations required to fabricate and operate all-fibre acousto-optic devices. The acousto-optic theory of circular cross-section devices is developed and extended to non-circular cross-sections. In this way all practical devices with non-circular cross-sections can be accurately modelled, and the optical bandwidth, switching speed and polarisation dependence can be tailored to a specific requirement. Polarisation independent operation is a serious obstacle in the development of practical photonic devices. This issue was resolved in this device by using geometric birefringence in the interaction region, produced by fusing the fibres of the null coupler to a precise degree of fusion. Polarisation independent operation is achieved with this technique without compromising other device parameters such as drive power. In order to fabricate these devices with the required uniformity, the tolerance on the manufacturing process was theoretically and experimentally studied. A new coupler rig was designed to operate within these tolerances. The coupler rig was capable of the manufacture of uniform devices both in the degree of fibre fusion and in the area of the device cross-section. The rig was optimised to produce low excess loss devices with high isolation between the output ports. In addition, it was possible to manufacture the length of the uniform tapered region over three times longer than previously possible. The incorporation of the non-circular operational theory enables non-destructive measurements of both the degree of fibre fusion and the device cross-sectional area, anywhere along the tapered region. Unlike competing technologies, geometric birefringence produces polarisation insensitive devices without compromising device parameters. This technique allows the following characteristics to be simultaneously achieved: 1) lower drive power, < 0.25 mW, 2) improved polarisation insensitivity, < 0.01 dB, 3) improved crosstalk, < -40 dB, 4) better excess loss, < 0.001 dB, 5) switching speeds of < 40 µs for a 25 mm long device, and 6) only one fabrication step.
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Hale, Zoe Miranda. "Fibre optic sensors using adiabatically tapered single mode fibres." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320155.
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Lefrançois, Marcel. "Aspects of tapered optical fibre polarizers." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26720.
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This thesis proves that it is possible in principle to make in line optical fibre polarizers from tapered optical fibres surrounded by a quartz cladding. The theory of light propagation and polarization in fibres was reviewed as background information and several fabrication processes were evaluated and tried experimentally. The best results are obtained by heating a quartz tube in an oxy-propane flame, so that it collapses onto the fibre. Unfortunately, due to residues remaining between fibre and quartz tube, and due to large differences in melting points the results are quite irreproducible, and routine fabrication of polarizers with predictable properties is not yet feasible by the methods described in this thesis.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Jarzebinska, Renata. "Tapered optical fibre sensors employing nanostructured coatings." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/5585.
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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.
6
Yerolatsitis, Stephanos. "Adiabatically tapered all-fibre devices for mode manipulation." Thesis, University of Bath, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707578.
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In this thesis we describe all-fibre devices that can be used for manipulating modes in a range of applications. The devices comprise an input and an output system and rely on fibre transitions. If the transition is gradual enough to be adiabatic, we can predict the behaviour of the output system depending only on the characteristics of the input system. Some of these devices work in a mode-selective regime where each input of the device excites a different mode at the output. These devices can be used to increase the data capacity of fibre networks where each mode can be used as an independent data channel. We also demonstrate mode converters that convert light to different higher-order modes of a ribbon fibre and can be used to increase the peak power transmitted in fibre lasers. Finally we describe devices that are non-mode-selective and have several cores. These devices convert the modes of a multimode core to the modes of a rectangular core made from individual fibres. These can be used as a diffraction-limited input to a spectrograph to eliminate modal noise from astronomical measurements.
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Ross, Steven. "Development of a novel gradient-force tapered fibre optical tweezers system for 3D optical trapping at near horizontal fibre insertion angles." Thesis, Liverpool John Moores University, 2015. http://researchonline.ljmu.ac.uk/4461/.
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The use of optical fibre as a mechanism for the delivery of the trapping laser beam to the sample chamber significantly reduces both the size and the build costs of “Optical Tweezers”. Furthermore, the use of fibre facilitates the decoupling of the optical trapping beam from the microscope optics, which provides further scope for the development of a portable optical trapping system, and the potential for uncomplicated integration with other advanced microscopy systems such as an atomic force microscope (AFM) for example. For use with an AFM, the optical fibre must be inserted at an angle of 10° with respect to the sample chamber floor. However, previous literature suggests that 3D optical trapping with a single fibre inserted at an angle ≤20° is not feasible. This thesis presents the design, development, build and test of a single beam optical fibre based gradient force optical tweezers system and its associated software. An investigation is conducted to ascertain why optical trapping, using single fibre systems, cannot be achieved at sub 20° insertion angles, the result of which formed the basis of a hypothesis that explains this limitation. This finding led to the development of tapered optical fibre tips that are cable of 3D optical trapping at an insertion angle of ≤10°. The optimised optical fibre tapers are presented and their ability to trap both organic and inanimate material in 3D at an insertion angle of 10° is demonstrated. The near-horizontal insertion angle introduced a maximum trapping range (MTR). The MTR of the tips is determined empirically, evaluated against simulated data, and found to be tuneable through taper optimisation. Optical trap characterisation has been undertaken in terms of the optical trapping forces acting on the trapping subjects. Finally, the fibre tapering devices ability to reproduce identical tapers, or not, using the same device parameters, was investigated and the results in terms of geometric profile and optical performance are presented.
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Pennetta, Riccardo [Verfasser], Philip St J. [Akademischer Betreuer] Russell, and Gustavo [Gutachter] Wiederhecker. "Tapered Glass-Fibre Nanospike Optomechanics / Riccardo Pennetta ; Gutachter: Gustavo Wiederhecker ; Betreuer: Philip St.J. Russell." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2019. http://d-nb.info/1180028376/34.
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LORENZI, ROBERTO. "Silica based functional materials: - Charge transport in nanostructured SnO2: SiO2 thin films. - Second harmonic generation in niobium potassium silicate glasses. - Tapered silica optical microfibres for gas sensors." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2010. http://hdl.handle.net/10281/10933.
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"Charge transport in nanostructured
SnO2:SiO2 thin films":
Silica based nanostructured thin films grown on silicon substrates are promising materials for novel light emitter devices. In particular, tin dioxide is a wide band gap n-type semiconductor (Eg=3.6 eV) with an expected band-to-band emission centered in the ultraviolet (344 nm) region of the electromagnetic spectrum. Our group succesfully demonstrated UV emission from such systems, but at the beginning of my work many issues in charge transport processes needed to be explained.
Aim of this project was to clarify electric transport and charge trapping mechanisms. As a result of a materials science approach we can now interpret the experimental data through specific relationships between synthesis conditions, clustering morphology (nanoparticle (NP) size distribution and volumic concetration, interphase substoichiometry, film thickness), and electric response.
The observed phenomena have been analyzed within the percolation theory. Main results concern: electric transport of both holes and electrons is sustained by NP-to-NP hopping events and dielectric enhancement results from oscillating charges (holes) on NPs. "Second Harmonic Generation in potassium niobium silicate glasses": Second harmonic generation (SHG) is a non linear optical process largely employed in current laser technology and photonics. However in almost every application the material employed for these purposes are single crystals. Therefore the possibility to achieve large SHG in amorphous systems may lead to devices with innovative configurations. SHG may occur only if the system is non-centrosymmetric, therefore for glasses it is forbidden due to intrinsic isotropy. The inversion symmetry can be broken up with poling treatments. They consist in applying strong electrostatic field while the sample is stressed by external perturbation (typically heat, electron beam or laser light).
We have explored the effect of thermal poling treatment on potassium niobium silicate glasses on inducing non linear optical properties. The results have revealed a strong SHG associated with structural modifications.
The proposed mechanism involves a rearrangement of niobium oxide groups mediated by non bridging oxygen and potassium ion transport across the glass. These new charge arrangements form a non-centrosymmetric region underneath the anodic contact responsible of the detected SH signal. "Tapered silica optical microfibres for gas sensors": In the last years, tapered silica fibres have attracted much interest in photonic research, because of peculiar properties emerging in waveguides with lateral dimensions of the same order of the guided modes. In particular, in these structures the large evanescent field enables some interesting properties, such as microfluidic sensors and high Q optical resonators (coiling the tapered fibre), non-linear effects and supercontinuum generation. In this project, carried out at the University of Southampton (UK) in the group of Dr. Gilberto Brambilla, we have explored the feasibility of an innovative optical absorption device, based on ring down spectroscopy.
In this case we are interested in a sensor for in-line application: a fluidic channel wrapped with tapered fibre in which the analyte can flow. The large power fraction outside the fibre interacts with the flowing medium and any change in the surrounding optical properties (refractive index or absorption coefficient) leads to a modification of the recorded light intensity propagating in the fibre.
The idea is to exploit ring down time of a silica tapered microcoil resonator as an indicator of the absorption coefficient of a gas (or a liquid) flowing in the channel.
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Greenhalgh, Andrew Bryce. "Tapered polymer optical fibres for biosensing." Thesis, Manchester Metropolitan University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423074.
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Klvaňa, Jakub. "Kombinované struktury v optickém vlákně." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-316924.
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The aim of this master’s thesis is familiar with the problems of optical fibers and possi- bilities creating functional optical structures in optical fibers. first section focuses on the optical fibers and their properties. Another chapter deals with the functional structures of optical fiber and their production. Next section is devoted to the analysis of combinations of these functional structures and their potential applications in sensors. Subsequently, a combined structure is proposed, which is later produced, measured and evaluated for possible use in the sensors
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King, Branden Joel. "Tapered Optical Fiber Platform for Biosensing Applications." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1398708775.
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Mouchel, Paul. "Fonctions optiques basées sur des composants fibrés passifs : Collimation du signal issu d’une fibre optique et verrouillage de mode." Thesis, Angers, 2018. http://www.theses.fr/2018ANGE0055.
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Le développement de composants fibrés passifs est un enjeu crucial dans le domaine des lasers à fibre car ils permettent de répondre aux besoins de marchés critiques. Cette thèse s’intéresse à deux types de composants : les collimateurs qui servent à réduire la divergence du signal en sortie de laser et les absorbants saturables réels qui permettent d’obtenir des impulsions ultracourtes (ordre de la picoseconde). Le travail sur les collimateurs fibrés a mené dans un premier temps à la conception d’un composant compact capable de transmettre jusqu’à 20 W de puissance continue. Un second collimateur plus complexe qui permet de contrôler également l’axe optique (déviation angulaire et centrage) par rapport à la mécanique a été développé. La simulation du composant, la procédure d’assemblage et le banc d’alignement mis en place spécifiquement pour répondre à ce besoin sont détaillés. Le second composant est un absorbant saturable réel fibré : un taper sur lequel du graphène est déposé. Le choix des caractéristiques de réduction de la fibre, sa fabrication et la technique de dépôt du graphène sont détaillés. Une étude de son intégration dans la cavité résonante d’un laser est présentée. Le laser émet des impulsions d’énergie 1 nJ, de durée 4 ps et a une puissance moyenne de 520 mW. Les limitations en puissance du composant sont également évoquéesThe development of fiber-based passive components is at stakes in the industry of fiber lasers.They are key components in order to meet the needs of critical markets. Two kinds of components are studied: collimators and real saturable absorbers. The former’s goal is to reduce the divergence of the output signal of a laser. When inserted in a cavity, the latter allows the generation of ultrashort pulses (order of the picosecond). We first developed a compact fiber collimator capable of transmitting up to 20 W of continuous optical signal. A more complex collimator was then developed. We are able to control the deviation and centring of the optical axes thanks to its design. The simulation of the component, the process of fabrication and the optical bench we specifically created for the alignment are discussed. The second component that we worked on is a real saturable absorber : a taper with graphene deposited on its waist. The reduction of the fiber diameter, the fabrication of the component and the process of deposition of graphene are described. We also studied the way the component behaves in the resonant cavity of a laser. The laser generated ultrashort pulses with an energy of 1 nJ and a duration of 4 ps. The average power of the laser is 520 mW. The limitations of the component are also discussed
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Gao, Song. "Fabrication of Tapered Dual-core As2Se3-PMMA Fiber and Its Applications." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/38697.
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Fiber optical temperature and strain sensors have been extensively investigated for applications in the civil structures to ensure safety and prevent disasters in advance. Most of the demonstrated fiber sensors are based on the silica fibers to form an interferometer by measuring the spectrum wavelength shift caused by the change of the refractive index and fiber length, and the sensitivities, defined as the rate of wavelength shift with respect to temperature or strain, are limited by the small values of thermal-expansion coefficient and thermo-optic effect of the silica materials. To improve the sensitivity, we designed the dual-core As2Se3-PMMA fiber with the PMMA cladding diameter 56.5 times larger than that of the As2Se3 cores, which brings out many interesting sensing applications.
Nonlinear devices have a variety of practical applications including parametric amplification, all-optical switching, super-continuum generation, and sensing applications. Tapered chalcogenide-polymer fiber structures composed of an As2Se3 core and a polymethyl methacrylate (PMMA) cladding are a promising platform for nonlinear applications because the As2Se3 core provides high nonlinearity over the near- and mid-infrared spectral ranges for compact nonlinear devices with low power consumption and the PMMA cladding provides high mechanical strength for easy handling. Advanced As2Se3-PMMA fiber structures such as dual-core fibers that support guided propagation of an even mode and an odd mode will open the way for a variety of novel devices in the near- and mid-IR wavelength range.
In my work I utilized two As2Se3 fibers and a polymethyl methacrylate (PMMA) tube for the fabrication of dual-core As2Se3-PMMA tapers and demonstration of the sensing applications and nonlinear optical effects.
The thesis mainly consists of three parts: the fabrication process, the sensing applications, and the nonlinear applications in the tapered dual-core As2Se3-PMMA fiber.
In the first part, the fabrication process of the tapered dual-core As2Se3-PMMA fiber is introduced. The dual-core As2Se3-PMMA fibers are fabricated using a rod-in-tube method. The images of the setups and fibers in process are listed.
In the second part, a theoretical model for temperature and strain measurement and four sensing applications are introduced. Firstly, we demonstrate an approach for high-sensitivity simultaneous temperature and strain measurement in a dual-core As2Se3-PMMA taper with As2Se3 core diameter of 0.55 μm. High measurement sensitivities are observed for both principal polarization axes of the tapered dual-core As2Se3-PMMA fiber with temperature sensitivities of -115 pm/ºC for axis-1, -35.5 pm/ºC for axis-2, and strain sensitivities of -4.21 pm/με for axis-1 and -3.16 pm/με for axis-2. Secondly, the thermal forces in a dual-core As2Se3-PMMA taper are investigated. A temperature-insensitive strain sensor is proposed and demonstrated based on the thermal forces. Finally, two approaches for temperature and strain sensitivity enhancement are investigated. The first approach is by reducing the value of the variation of the difference between phases of the even and odd modes with respect to wavelength (∂ϕd(λ)/∂λ) and increasing thermal-forces in a dual-core As2Se3-PMMA taper with As2Se3 core diameter of 2.5 μm. The value of ∂ϕd(λ)/∂λ decreases with the As2Se3 core diameter and thermal-forces on the As2Se3 cores are enhanced in the fibers with large PMMA cladding, which work together to enhance the measurement sensitivity. The second approach is based on effective group-velocity matching between the even and odd modes of a dual-core As2Se3-PMMA taper on which an antisymmetric long-period grating is inscribed. The variation of the difference between phases of the even and odd modes with respect to wavelength tends to 0 (∂ϕd(λ)/∂λ→0) near the resonance wavelength of the grating due to the effective group-velocity matching between the two modes, and consequently, thermally-induced change of the difference between phases of the two modes ϕd (λ) leads to a large wavelength shift indicating enhancement of the temperature measurement sensitivity.
In the third part, I study the nonlinear optical effects in the hybrid fibers. Firstly, I demonstrate modulation instability within the normal-dispersion regime in a dual-core As2Se3-PMMA fiber. Then I review the work about the forward stimulated Brillouin scattering and its sensing applications. The radial and torsional-radial guided acoustic modes of silica fibers and tapered dual-core As2Se3-PMMA fibers are investigated experimentally and the preliminary results are presented.
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Riou, Fabienne. "Modélisation et caractérisation d'un amplificateur optique à semiconducteurs avec adaptateurs de mode." Saint-Etienne, 1994. http://www.theses.fr/1994STET4002.
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Ce mémoire traite de la conception et de la caractérisation d'un amplificateur optique à semiconducteurs dans lequel sont inclus des adaptateurs de mode. L'idée est ici de modifier la structure guidante afin de faciliter le couplage entre le mode guide de l'amplificateur et celui d'une fibre standard. Pour cela, le guide est affiné, dans ses parties terminales, au moyen de marches gravées. Ainsi, le mode guide est déconfiné, ce qui lui permet de s'élargir et d'être plus adapté au mode guide de la fibre. Dans un premier temps, un modèle décrivant la propagation du mode le long d'un guide plan présentant des marches abruptes a permis de définir une structure optimisée du point de vue des pertes induites par l'adaptateur de mode. Cette première étape a conduit à la spécification puis a la réalisation par A. A. R. D'un composant à ruban large démontrant la validité de l'idée. D'autre part, le modèle conçu a servi de référence pour la mise au point d'une analyse en mode propage (BPM) implantée dans le laboratoire, utilisant des techniques de différences finies. Puis, une structure à ruban étroit a été conçue à l'aide de cette dernière modélisation. Une fois réalisée, une caractérisation fine des dimensions modales a montré que l'élargissement du mode guide a bien été obtenu. Par ailleurs, la présence d'un rayonnement parasite le long de l'adaptateur a été mis en évidence et une modélisation utilisant ce rayonnement a conduit à l'interprétation des champs lointains mesurés. D'autre part, les pertes internes dues aux transitions ont été mesurées : ces pertes sont élevées du fait du nombre insuffisant de marches dans la zone active. Enfin, des caractérisations complémentaires prouvent que le composant présente des tolérances de positionnement assouplies, une relative insensibilité à la polarisation et une réflectivité résiduelle très faible
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Mullaney, Kevin. "The fabrication of micro-tapered optical fibres for sensing applications." Thesis, Cranfield University, 2016. http://dspace.lib.cranfield.ac.uk/handle/1826/11066.
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This thesis describes the processes used to manufacture optical fibre tapers and tapered long period gratings (TLPGs) using a CO2 laser. A semi-automated system for fabricating adiabatic and non-adiabatic tapers with repeatable physical dimensions has been developed. The tapers had waist diameters which were reproducible to within ± 0.5 μm. This system has also been used to fabricate TLPGs with periods ranging from 378 μm to 650 μm. Novel techniques to monitor the process of fabricating tapers were also explored. These techniques included; monitoring the transmission of the fibre using a spectrophotometer, using an in-line fibre Bragg grating (FBG) to measure the strain experienced by the optical fibre and the use of a near infra-red (NIR) camera to aid fibre alignment and laser power optimisation. The spectrophotometer allowed the optical properties of the tapers to be tailored for specific applications and the FBG provided strain data for process optimisation. The use of a NIR camera and an FBG as an in-line strain sensor are a novel use of these devices in a fibre tapering process. Tapers were also thin-film coated using sputtering techniques to form surface plasmon resonance sensors and their refractive index sensitivity was measured. A novel protein sensor based on gold nanoparticles deposited on a fibre taper is also reported, together with a lossy mode resonance taper sensor. The TLPGs which were fabricated, comprised of between 6 to 18 periods. The refractive index sensitivity of a 6 period TPLG was measured and was 372 nm/ RI. Their resonance bands had twice the bandwidth and exhibited a higher extinction, compared to UV-written long period gratings of a similar number of periods.
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Ding, Ming. "Nanostructured optical fibre tapers and related applications." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/353817/.
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In the last decade, optical fibre tapers have attracted considerable interest because they offer a variety of enabling properties, including large evanescent fields, flexibility, configurability, high confinement, robustness and compactness. These distinctive features have been exploited in a wealth of applications ranging from telecommunication devices to sensors, from optical manipulation to high-Q resonators. Nanostructures on the optical fibre tapers are very promising since the size of the device can be extremely small. With the development of nanostructuring methods, sub-wavelength feature sizes have been achieved. In this thesis, nanostructured optical fibre tapers and some related applications are discussed. Light confinement is limited by diffraction and the minimum spot size is related to the light wavelength. In this thesis, light confinement in two and three dimensions is proposed and achieved with two typologies of nanostructured optical fibre tapers. The first group of devices exploits plasmons excited at the optical fibre tips to obtain high transmissivity, and confine light to a sub-wavelength dimension. Optical fibre tips were designed according to numerical simulations and coated by a layer of gold; an extremely small aperture was then opened at the tip apex. The experimental characterization and simulation results showed their improved transmission efficiency (higher than 10^-2) and thermal expansion measurements showed no shape changes could be detected within the accuracy of the system (~2 nm) for 9 mW injected powers. Effective confinements to 10 nm or smaller can be envisaged by decreasing the aperture size and slope angle. Application of this small spot size source can include scanning near-field optical microscope, optical recording, photolithography and bio-sensing. The second group achieves three dimensional light confinement exploiting a Fabry-Perot microcavity formed by a microfibre grating similar to those used in distributed feedback lasers. Microfibres were patterned using a Focused Ion Beam (FIB) system. In this structure, the microcavity provides longitudinal light confinement, whereas air dielectric guiding by the microfibre provides diffraction limited confinement in the other two dimensions. Due to the high refractive index contrast between silica and air, strong reflection can be obtained by only dozens of notches. This device can be used for a wide range of applications, e.g. sensing and triggered single-photon sources. Light confinement in nanostructured optical fibre tapers was exploited in a micrometric thermometer. A compact thermometer based on a broadband microfibre coupler tip showed a dynamic range spanning from room temperature to 1511ºC with a response time of tens of microseconds. This is the highest temperature measured with a silica optical fibre device. An average sensitivity of 11.96 pm/ºC was achieved for a coupler tip with ~2.5 μm diameter. A resolution of 0.66ºC was achieved for a coupler tip diameter of ~12.6 μm. Better resolution can be achieved with smaller size microfibre coupler tips. Optical fibre tapers are commonly used to couple light to selected resonator modes. Here FIB was used to inscribe microgrooves on optical Bottleneck Microresonator (BMR) surfaces to excite selected whispering gallery modes. By monitoring the transmission spectrum of the optical fibre taper, substantial spectral clean-up was obtained in appropriately scarred BMRs. Single high-Q mode operation can be achieved by either using two asymmetrical perpendicular scars or placing the grooves closer to the BMR centre, providing the potential for high performance sensors and other optical devices. Finally, strong three dimensional localization has been achieved in Plasmonic Slot Nano-Resonators (PSNRs) embedded in a gold-coated optical fibre tapers. Different shapes PSNRs, embedded in thin gold metal film coated plasmonic microfibre, were numerically investigated. The intensity enhancement (in excess of 10^6) and the resonance wavelength depend on both the PSNR and microfibre dimensions. Theoretically and experimentally, the transversal excitation of a rectangular PSNR embedded in a thin gold film coated plasmonic fibre tip was discussed for the first time, and showed high localization and strong enhancement (7.24×10^3). This device can find a wide range of applications such as surface-enhanced Raman scattering, optical filtering, spectroscopy and bio-sensing.
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Ben, Harush Negari Amit. "Tapered Optical Fiber Platform for High Sensitivity Refractive Index Sensing Applications." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1417644120.
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Yataki, M. S. "Fused taper single mode fibre couplers." Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383498.
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Hernandez, Felipe Bueno. "Sensor de força utilizando Fiber taper." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18149/tde-27072016-074912/.
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Este trabalho teve por objetivo desenvolver e caracterizar um sensor de força utilizando uma fibra óptica modificada pelo processo conhecido como Fiber tapering. A fibra quando modificada deixa exposto o campo evanescente, o que a torna sensível a influências externas, e a luz guiada na fibra pode vir a sofrer reflexão interna total frustrada ao entrar em contato com materiais. Ao envolver a região modificada por um material elastomérico, a área de contato e consequentemente a atenuação torna-se uma função da intensidade da força aplicada, possibilitando então relacionar a força a atenuação da luz. Baseando-se nesse efeito, foi criado um sensor de dimensões reduzidas, de rápida resposta, linear, altamente sensível e de boa repetibilidade. Foi criado também um circuito eletrônico utilizando amplificadores operacionais para a aquisição e processamento do sinal proveniente da fibra e selecionado um sensor comercial comum para a realização de experimentos e comparações. Ambos os sensores foram posicionados sobre uma balança de precisão e submetidos a diversos esforços obtendo-se dados sobre a resposta estática. Em seguida utilizando um shaker eletrodinâmico foram medidos os tempos de resposta a uma entrada degrau, e realizando esforços repetitivos foram analisados os desvios das medidas lidas pelos sensores.The aim of this research was to develop and characterize a force sensor using a modified optical fiber by a process known as Fiber tapering. The modified fiber leaves the evanescent field exposed and prone to external influences and the guided light may suffer frustration of total internal reflection upon contact with materials. When covering the modified fiber section with an elastomeric material, the contact area and therefore the attenuation becomes a function of the applied pressure, making it possible to relate force to attenuation in light intensity. Based on this effect, a small sensor was created, having a quick response time, with high linearity, high sensitivity and good repeatability. Along with the sensor, an electronic circuit using operational amplifiers was designed for acquisition and processing of the signal obtained from the optical fiber. In addition, in order to perform experiments and comparisons, a standard force sensor was chosen. Both sensors were placed over a precision weighing scale and had different intensities of force applied on them, and after that, data regarding static measurements was gathered. The response time was obtained using an electrodynamic shaker and applying a step input. Furthermore, data was gathered about the deviations on the measurements by performing a repetitive set of compressions.
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Vukovic, Natasha Trivunac. "Optical properties of long photonic crystal fibre tapers." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/301300/.
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In this thesis I investigate optical properties of metre - long tapers. Microstructured optical fibre technology has created new opportunities in a broad range of science and technology. In the work presented in this thesis I have combined the microstructured optical fibre technology with a novel tapering facility in order to develop new applications in the field of nonlinear optics. This thesis concerns development of a novel tapering facility, capable of achieving intermediate length (few tens of cm to ˜10 m) tapers. In comparison with systems presented to date, the novel system has the advantage of the increased control over the desired taper profile and enables efficient fabrication of intermediate taper lengths of potentially arbitrary profiles. During the fabrication the fibre diameter exhibits significant variations, due to various disturbances. A design of the feedback loop for the enhanced control of the output diameter variation is proposed. The system capabilities have been tested and demonstrated in many different examples. The presented results show that the variation of the fibre diameter is within ~1%, which offers possibilities to use the system in various applications. As an example of the intermediate taper length design and application, parabolic pulse generation was investigated. It represents a very attractive pulse shape, since it can propagate at high peak powers while avoiding wave-breaking effect and have a flat and broad spectrum, which could lead to pulse compression applications. This thesis presents numerical modelling and experimental results (restricted to a set of parameters of fibres available from ’stock’) concerning this phenomena. Supercontinuum generation is an area of research that has been attracting scientific interest over several decades. This thesis shows results of a study of supercontinuum generation in intermediate length tapered microstructured optical fibres. A simulation tool has been developed and the procedure to efficiently determine optimum conditions for improving flatness of the supercontinuum spectra has been proposed. The proposed method concerns a ’standard’ microstructured optical fibre, but generally can be extended to different fibre designs.
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Garcia, Mina Diego Felipe. "Bi-tapered Fiber Sensor Using a Supercontinuum Light Source for a Broad Spectral Range." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1492001857501804.
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Wang, Xiaozhen. "Characterization of Fiber Tapers for Fiber Devices and Sensors." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23330.
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Fiber tapers have attracted much attention and have been successfully employed in various applications, ranging from resonators, filters, interferometers to sensors. This thesis studies the properties of fiber tapers for the purpose of making tapered-based devices and sensors in aerospace related application where small size and light weight are critical. This thesis includes theoretical derivation and experimental verifications of distributed mode coupling in tapered single-mode fibers (SMFs) with high-resolution optical frequency-domain reflectometry (OFDR) technique. The studies are realized with OFDR through phase detection of a Mach-Zehnder interferometer (MZI), which measures local refractive index change relative to the reference arm. The wavelength shifts converted by the phase change give the group index differences between the fundamental mode and higher-order modes of fiber tapers. The energy re-distribution is observed in Rayleigh backscatter amplitude as a function of fiber length with a ~13µm resolution over the entire fiber taper, and group index difference between core and cladding modes is measured with a spatial resolution of ~2cm by using autocorrelation data processing. The thermal and mechanical properties of fiber tapers have also been characterized with OFDR. The cross-correlation wavelength shift is related to the refractive index change of the modes. It is shown that residual stress induced by the tapering process results in the inhomogeneous thermal property, which can be significantly reduced by an annealing treatment. A fiber taper with a waist diameter of ~6µm has a force sensitivity of ~620.83nm/N, ~500 times higher than that of SMF. Furthermore, polarization-preserving character of tapered polarization-maintaining fibers (PMFs) is evaluated by OFDR-based distributed birefringence along tapered PMFs. Three tapered-based micro-fiber devices have been used as effective mode selecting components to build narrow-linewidth tunable Erbium-doped fiber ring lasers. The fabrication is easy and at a low cost. 1) a tapered fiber tip forms multimode interference mechanism; 2) a two-taper MZI has been demonstrated by splitting/combining the fundamental mode and higher-order modes through fiber tapers and is tuned by bending one taper waist; 3) a novel tunable fiber Fabry-Perot filter, consisting of a hollow-core photonic bandgap fiber and a micro-fiber, is employed in the reflection mode.
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Gamez, Jimmy Ray. "The Effects of Diameter Fluctuations and Coiling on the Sensitivity of Sapphire Single Crystal Optical Fiber Evanescent Wave Fluorescence Sensors." Scholar Commons, 2009. https://scholarcommons.usf.edu/etd/1980.
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The purpose of this research was to determine the effect of diameter fluctuations on the sensitivity of sapphire multimode optical fibers used as evanescent wave fluorescence sensors. It was predicted that fluctuations in the diameter of the fiber would act as a series of bi-tapers converting lower order modes to higher order modes increasing the evanescent wave penetration depth thereby increasing the excitation of a cladding of fluorescent fluid. Induced fluorescence from the fluid cladding would then couple back into the fiber more efficiently increasing the sensitivity of the sensor.
The effect of coiling the fiber on the sensitivity of the sensor was also explored. Coiling the fiber converts lower order modes into higher order modes and increases the sensing length while maintaining a small probe size. However, coiling experiments produced unexpected results and in the course of studying these results a layer of material was discovered coating the surface of the sapphire fibers.
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Ding, Wei. "Properties and applications of structured optical fiber tapers." Thesis, University of Bath, 2006. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436884.
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Eissa, Rania Hamdi. "An optical fibre beam expanding element : an up-taper in the refractive index of the fibre cladding." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613874.
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Ren, Yundong. "Specially Shaped Optical Fiber Probes: Understanding and Their Applications in Integrated Photonics, Sensing, and Microfluidics." Digital WPI, 2019. https://digitalcommons.wpi.edu/etd-dissertations/569.
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Thanks to their capability of transmitting light with low loss, optical fibers have found a wide range of applications in illumination, imaging, and telecommunication. However, since the light guided in a regular optical fiber is well confined in the core and effectively isolated from the environment, the fiber does not allow the interactions between the light and matters around it, which are critical for many sensing and actuation applications. Specially shaped optical fibers endow the guided light in optical fibers with the capability of interacting with the environment by modifying part of the fiber into a special shape, while still preserving the regular fiber’s benefit of low-loss light delivering. However, the existing specially shaped fibers have the following limitations: 1) limited light coupling efficiency between the regular optical fiber and the specially shaped optical fiber, 2) lack special shape designs that can facilitate the light-matter interactions, 3) inadequate material selections for different applications, 4) the existing fabrication setups for the specially shaped fibers have poor accessibility, repeatability, and controllability. The overall goal of this dissertation is to further the fundamental understanding of specially shaped fibers and to develop novel specially shaped fibers for different applications. In addition, the final part of this dissertation work proposed a microfluidic platform that can potentially improve the light-matter interactions of the specially shaped fibers in fluidic environments. The contributions of this dissertation work are summarized as follows: 1) An enhanced fiber tapering system for highly repeatable adiabatic tapered fiber fabrications. An enhanced fiber tapering system based on a novel heat source and an innovative monitoring method have been developed. The novel heat source is a low-cost ceramic housed electric furnace (CHEF). The innovative monitoring method is based on the frequency-domain optical transmission signal from the fiber that is being tapered. The enhanced fiber tapering system can allow highly repeatable fabrication of adiabatically tapered fibers. 2) A lossy mode resonance (LMR) sensor enabled by SnO2 coating on a novel specially shaped fiber design has been developed. The developed LMR sensor has a D-shape fiber tip with SnO2 coating. It has the capability of relative humidity and moisture sensing. The fiber-tip form factor can allow the sensor to be used like a probe and be inserted into/removed from a tight space. 3) Specially shaped tapered fibers with novel designs have been developed for integrated photonic and microfluidic applications. Two novel specially tapered fibers, the tapered fiber loop and the tapered fiber helix have been developed. The tapered fiber loop developed in this work has two superiority that differentiated itself from previous works: a) the mechanical stability of the tapered fiber loop in this work is significantly better. b) the tapered fiber loops in this work can achieve a diameter as small as 15 ?m while still have a high intrinsic optical quality factor of 32,500. The tapered fiber helix developed in this work has a 3D structure that allows it to efficiently deliver light to locations out of the plane defined by its two regular fiber arms. Applications of the tapered fiber helices in both integrated photonic device characterizations and microparticle manipulations have been demonstrated. 4) Developed an acrylic-tape hybrid microfluidic platform that can allow function reconfiguration and optical fiber integration. A low-cost, versatile microfluidic platform based on reconfigurable acrylic-tape hybrid microfluidic devices has been developed. To the best of the author’s knowledge, this is the first time that the fabrication method of sealing the acrylic channel with a reconfigurable functional tape has been demonstrated. The tape-sealing method is compatible with specially shaped fiber integrations.
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Daengngam, Chalongrat. "Second-Order Nonlinear Optical Responses in Tapered Optical Fibers with Self-Assembled Organic Multilayers." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/77068.
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Owing to its centrosymmetric structure, the critical optical component of a silica fiber cannot to possess a second-order nonlinear optical susceptibility, Χ(²), preventing a silica fiber from many potential applications. Here, we theoretically and experimentally demonstrate a new technique to generate large and thermodynamically stable second-order nonlinearity into silica optical tapered fibers without breaking the centrosymmetry of the silica glass. The nonlinearity is introduced by surface layers with high polar-ordering fabricated by a novel hybrid covalent/ionic self-assembly multilayer technique. Despite the overall rotational symmetry of the nonlinear fiber, we observe significant second harmonic generation with ~ 400–500 fold enhancement of the SHG power compared to the traditional tapers. Phase matching for a SHG process in second-order nonlinear tapered fibers is also realized by the compensation of waveguide modal dispersion with material chromatic dispersion, which occurs only for submicron tapers where the modal dispersion is large. In addition, quasi-phase-matching for a nonlinear taper can be accomplished by introducing a periodic pattern into the nonlinear film coating. We use UV laser ablation for the controlled removal of particular nonlinear film segments on a taper surface in order to produce a Χ(²) grating structure. A resulting SHG enhancement from quasi-phase-matching is observed over a broadband spectrum of the pump light mainly due to the non-uniform shape of a taper waveguide. The laser ablation is a clean and fast technique able to produce well-define patterns of polymer films on either flat or curved substrate geometry. With surface layers containing reactive functional groups e.g. primary amines, we demonstrate that the resulting patterned film obtained from the laser ablation can be used as a template for further self-assembly of nanoparticles with high selectivity. A pattern feature size down to ~ 2μm or smaller can be fabricated using this approach. We also discuss preliminary results on a novel technique to further improve spatial accuracy for selective self-assembly of nanoparticles at an unprecedented level. Different types of nanoparticles are joined in order to form well-defined, molecular-like superstructures with nanoscale accuracy and precision. The technique is based on a selective surface functionalization of photosensitive molecules coated on metallic nanoparticles utilizing enhanced two-photon photocleavage at the plasmonically-active sites (hot spots) of the nanoparticles in resonance with an applied electromagnetic wave. As a result, the surface functional groups at the nanoparticle hot spots are different from the the other areas, allowing other kinds of nanoparticles to self-assemble at the hot spots with high degree of selectivity.Ph. D.
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Cui, Ziruo. "Wet Etching Optical Fibers to Sub-micron Diameters for Sensing Application." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1397801129.
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Belhadj, Taher Aymen. "Etude théorique et expérimentale de composants innovants à fibres optiques multiples." Thesis, Limoges, 2016. http://www.theses.fr/2016LIMO0036/document.
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Les travaux de recherche présentés dans ce manuscrit ont pour but de concevoir, simuler, fabriquer et caractériser un convertisseur modal à base de canne microstructurée air-silice (CMAS). Cette fonction représente un élément clé pour les multiplexeurs modaux et les compensateurs de dispersion chromatique. Le composant proposé est basé sur une CMAS effilée dite « taper » qui constitue une transition entre les deux fibres différentes. La conversion se fait à travers l’excitation d’un mode particulier dans une fibre multimode à partir d’une fibre standard. Dans les structures à diamètre évolutif, la compréhension des différentes théories régissant le couplage entre les différents modes est nécessaire. Une étude approfondie est réalisée pour analyser le phénomène de couplage et étudier le critère d’adiabaticité. Ce composant est élaboré autour d’une technologie de fabrication existante à XLIM qui se base sur la technique fusion-étirage. Enfin, nous validons numériquement et expérimentalement ce principe. Nous réussissons à exciter le mode fondamental et d’autres modes d’ordre supérieur dans une fibre multimodeThese research works presented in this manuscript aim at designing, simulate, manufacture and characterizing the modal converter based microstructured air-silica cane. This function represents a key element for modal multiplexers and chromatic dispersion compensators. The proposed component is based on a tapered microstructured air-silica cane « taper » which constitutes a transition between the two different fibers. The conversion is done through the excitation of a particular mode in a multimode or few mode fibers from a standard fiber. In the tapered structures, the understanding of the different theories involving the coupling between the different modes was yet necessary. A thorough study is carried to analyze the phenomenon of coupling and study the adiabatic criterion. This component is developed around an existing manufacturing technology at XLIM which based in the technique « stack and draw». Finally, we validate numerically and experimentally that principle. We succeed to excite the fundamental mode and higher order modes in a multimode fiber
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Nguyen, Minh-Hoang. "PROPELA - procédé de perçage laser pour l'aéronautique." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0577/document.
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Le perçage est un procédé de fabrication répandu dans le milieu industriel. Le secteur aéronautique a recours à ce procédé pour usiner de nombreuses pièces. Les chambres de combustions en sont un exemple. Exposées à des cycles thermiques sévères, elles sont percées d’une multitude de trous de refroidissement. Chez Safran Helicopter Engines, motoriste spécialisé dans la conception de turbines à gaz pour hélicoptères, ce perçage est réalisé à l’aide d’un procédé d’usinage unique : le perçage par percussion laser à la volée. Ce procédé phare leur permet de réaliser des milliers de trous inclinés dans des tôles en matériaux réfractaires. Safran Helicopter Engines cherche à maintenir son avance dans la production de turbines en s’appuyant sur les innovations constantes du procédé de perçage. Ce travail de thèse s’est articule autour du développement d’un nouveau procédé de perçage laser. De manière à définir un procédé fiable et efficace, plusieurs stratégies de perçage sont étudiées via les possibilités offertes par un laser à fibre milliseconde de haute puissance. Les résultats obtenus laissent entrevoir des perspectives intéressantes en termes d’augmentation de cadence de production à qualité d’usinage équivalente. L’amélioration des performances a été démontrée expérimentalement sur un banc d’essais représentatif des machines de production. Des trous de 400 μm de diamètre incliné à 60o ont pu être réalisés avec un cycle de perçage raccourci au minimum d’un facteur 2. Cette thèse présente également des éléments de compréhension des phénomènes de formation d’un trou. Pour cela, une modélisation des processus thermo hydrodynamiques impliqués dans le procédé de perçage laser a été développée. Ce modèle basé sur une approche par éléments finis repose sur l’étude thermique au cours de l’interaction entre le faisceau laser et la matière. Une partie du modèle inclut les phénomènes de propagation du faisceau dans la cavité en cours de formation afin de traduire de manière plus réaliste le dépôt d’énergieDrilling is a well-known manufacturing process. The aeronautic industry uses this process to machine a lot of elements. Among them, we can mention turbine blades, fuel injectors, combustion chambers. The latter are exposed to serious thermal stresses. To limit their impacts, combustion chambers are drilled with multiples cooling holes. At Safran Helicopter Engines, engines manufacturer specialized in engines design for helicopters, drilling is performed with a unique machining process : on the fly laser percussion drilling. This flagship process allows drilling thousands of tilted holes on refractory materials. Safran Helicopter Engines seeks to preserve its leading position in turbo engines manufacturing by looking for steady innovative drilling process. This thesis is structured around the development of a new laser drilling process. To define a reliable and efficient process, several drilling strategies were studied through the possibilities offered by a high-power millisecond fiber laser. The presented results allow catching a glimpse of the possibilities of production improvement. The performance enhancement was established through experimentation with a test bench. Holes of 400 μm diameter with an angle of 60o were drilled with a reduced processing time thanks to this new drilling process. In this thesis, we also propose a theoretical approach describing the hole formation. A mathematical model, accounting for all the physical process taking place during the drilling process is introduced. This model is based on finite elements method and considers the laser beam propagation within the drilled holes by solving Maxwell equations
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Gao, Bo. "FRP strengthened RC beams : taper design and theoretical analysis /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?MECH%202005%20GAO.
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Tian, Zhaobing. "In-line optical fiber interferometric refractive index sensors." Thesis, Kingston, Ont. : [s.n.], 2008. http://hdl.handle.net/1974/1358.
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Henrique, Franciele Renata. "Conexão óptica de microestruturas poliméricas através de nanofibras." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-25042016-093740/.
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O desenvolvimento da fotônica integrada vem recebendo muita atenção nos últimos anos. Sua alta funcionalidade e velocidade de transmissão de sinais possibilitam a aplicação em diversas áreas, que vão desde comunicações até biologia. O uso de polímeros em circuitos fotônicos integrados tem se mostrado interessante, pois compostos orgânicos podem ser facilmente incorporados a matrizes poliméricas. Isso faz com que as propriedades físicas do polímero possam ser modificadas de acordo com os materiais incorporados. Além disso, a técnica da fotopolimerização por absorção de dois fótons torna possível a produção de microestruturas poliméricas tridimensionais com alta resolução. A incorporação dessas microestruturas a circuitos fotônicos pode trazer um novo ramo de funcionalidades devido à facilidade de modificação das propriedades dos polímeros. Além disso, a tridimensionalidade das estruturas permite a realização de conexões ópticas em três dimensões, o que colabora para o aumento da compacticidade dos dispositivos fotônicos. No entanto, para que estas microestruturas possam ser efetivamente incorporadas aos circuitos fotônicos é necessário desenvolver formas de conectá-las a fontes externas de excitação, bem como a instrumentos de análise de sinais. Os tapers de fibras ópticas, também conhecidos como microfibras ou nanofibras, são bons candidatos para realizar essa tarefa devido a suas dimensões reduzidas, as quais são compatíveis com o tamanho das microestruturas. Neste trabalho desenvolvemos métodos para realizar a conexão óptica entre microestruturas poliméricas e tapers de fibras ópticas. As microestruturas foram produzidas através da técnica de fotopolimerização por absorção de dois fótons e corantes orgânicos foram incorporados à matriz polimérica para conferir propriedades fluorescentes às estruturas. Os tapers foram produzidos a partir de fibras ópticas convencionais por uma técnica de aquecimento e estiramento. Para realizar a conexão óptica, dois métodos foram desenvolvidos. No primeiro deles as microestruturas foram excitadas através de uma lente objetiva e sua emisão foi coletada por um taper. No segundo método, tanto a excitação quanto a coleta foram realizadas por tapers de fibras ópticas. Em ambos os casos as fibras foram posicionadas através de micromanipuladores. Os resultados obtidos indicam que os tapers são ferramentas adequadas para realizar tanto a excitação quando a coleta da emissão de microestruturas, pois permitem excitação individual e coleta localizada. Produzimos microestruturas com múltiplas dopagens e pudemos concluir que a excitação localizada de diferentes partes da estrutura, bem como a correta escolha do comprimento de onda de excitação, são mecanismos que levam a alterações no espectro de emissão, o que torna estas estruturas candidatas a fontes de luz sintonizáveis que podem ser incorporadas a dispositivos on-chip. Por fim, desenvolvemos um método de produção de microestruturas conectadas a tapers. Este trabalho abre caminho para a incorporação de microestruturas poliméricas a circuitos fotônicos e demonstra que tapers de fibras ópticas são ferramentas eficientes para a realização de microconexões ópticas.The development of integrated photonics has received a great deal of attention in the last few years. Its high functionality and signal transmission speed allow applications in several fields, from telecommunications to biology. The use of polymeric platforms in integrated photonic circuits is interesting because organic compounds can be easily incorporated to polymeric matrixes, which makes it easy to change the physical properties of the polymer according to the embed materials. Furthermore, the two-photon polymerization technique allows the production of three-dimensional polymeric microstructures with high resolution. The incorporation of these microstructures to photonic circuits paves the way for a new field of funcionalities due to the ease of modification of the polymers properties. Besides that, the structures three-dimensionality allows the performance of optical connections in three dimensions, which can improve the compacticity of the photonic devices. However, for the effective incorporation of these microstructures to photonic circuits, it is necessary to develop ways to connect them to external excitation sources, as well as analysis instruments. Optical fiber tapers, also known as microfibers or nanofibers, are good candidates for this task due to their reduced dimensions that are compatible with the size of the microstructures. In this work we developed methods for the performance of optical connections of polymeric microstructures through fiber tapers. The microstrutures were produced through the two-photon polymerization technique and organic dyes were incorporated to the polymeric matrix in order to introduce fluorescent properties. The fiber tapers were produced from conventional optical fibers through a heat-and-draw approach. To perform the optical connections, two methods were developed. In the first one, the microestructures were excited through a microscope objective and emission collection was performed by a fiber taper. In the second approach, excitation and collection were performed by fiber tapers. In both methods, the tapers were set up by micromanipulators. The obtained results indicate that tapers are a suitable tool to perform optical excitation and emission collection in microstructures, as they allow individual excitation and localized collection. Multiple doped microstructures were produced and we could imply that the localized excitation of different parts of the structures, as well as the correct choice of the excitation wavelength, are tools that lead to changes in the emission spectrum, which makes these structures candidates to tunable light sources that can be incorporated to on-chip devices. At last, we developed a method for the production of microstructures connected to fiber tapers. This work paves the way for the incorporation of polymeric microstructures to photonics circuits and demonstrates that fiber tapers are efficient tools to perform optical microconnections.
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Godet, Adrien. "Spectroscopie Brillouin des micro et nanofils optiques de silice." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCD067/document.
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Cette thèse de doctorat porte sur la conception et la fabrication de microfils optiques de silice par la technique de fusion et d'étirage de fibres optiques standards, ainsi qu'une étude détaillée de leurs propriétés élastiques par spectroscopie Brillouin. Nous apportons une description complète, théorique et expérimentale, des spectres Brillouin rétro-diffusés par les microfils, révélant ainsi l'existence de plusieurs familles d'ondes élastiques, telles que les ondes hybrides et surfacique, ainsi que de nombreux anti-croisements. En exploitant l'ensemble de ces propriétés élastiques, nous démontrons ensuite une technique de mesure optique, simple et non-destructive, du diamètre des microfils et de leur uniformité, avec une très grande précision et une sensibilité de quelques nanomètres, comparable aux techniques conventionnelles comme la microscopie par balayage électronique. Nous réalisons en supplément une cartographie des ondes élastiques le long des microfils optiques par la technique de corrélation Brillouin de phase. Une autre étude majeure de cette thèse a porté sur la dépendance du spectre Brillouin en fonction d'une déformation axiale des microfils optiques qui présentent une très grande élasticité et des coefficients de contraintes élevés. Pour la première fois à notre connaissance, nous avons observé l’effet des non-linéaritiés des constantes élastiques de la silice dans un microfil optique fortement déformé sur les coefficients de contraintes. L'ensemble de ces travaux représente une étude fondamentale du processus de diffusion Brillouin dans les microfils optiques et permet également d'ouvrir la voie aux développements de dispositifs photoniques compacts dans le domaine des capteurs et des télécommunicationsThis thesis reports the design and fabrication of subwavelength-diameter silica optical fibers, also known as optical micro and nanowires. These hair-like slivers of glass, manufactured by tapering optical fibers down to a size hundred times smaller than a strand of human hair, have a number of optical and mechanical properties that make them very attractive for both fundamental physics and technological applications. In addition to providing strong light confinement and enhanced nonlinear optical effects, they exhibit a large evanescent field, enabling applications not currently possible with comparatively bulky optical fibers.We here explore their elastic properties through Brillouin spectroscopy. We specifically provide a complete description, both theoretically and experimentally, of the backward Brillouin spectra including the observation of both bulk hybrid and surface acoustic waves with many anti-crossings. A very good agreement is found between numerical simulations of the elastodynamics equation and the experimental Brillouin spectra for a wide range of wire diameters. From this study, we demonstrate a simple and non-destructive in-situ technique for measuring the diameter of these ultra-thin fibers and their uniformity with a high sensitivity of only a few nanometers. A distributed measurement of both the surface and hybrid acoustic waves along an optical microwire was then performed using Brillouin optical correlation technique. We further investigate the tensile strain dependence of Brillouin scattering in optical microwires and report, for the first time to our knowledge, evidence of a strong elasticity and non-linearity of the elastic constants of silica. This thesis therefore demonstrates that optical microwires can find various potential applications for strain optical sensing
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Semaan, Georges. "Soliton dynamics in fiber lasers : from dissipative soliton to dissipative soliton resonance." Thesis, Angers, 2017. http://www.theses.fr/2017ANGE0029/document.
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Dans cette thèse, nous étudions expérimentalement la génération d'impulsions carrées très énergétiques et accordable à l’échelle nanosecondes et d'impulsions ultracourtes à haute puissance moyenne de sortie dans les lasers à fibre utilisant les nanomatériaux comme absorbant saturable. Tout d'abord, puisque la dynamique des impulsions est dominée par l'interaction de la non linéarité et de la dispersion chromatique cubique de la fibre avec un mécanisme de discrimination d'intensité appelé absorbant saturable, la stabilité d'une distribution harmonique en mode verrouillé est étudiée par injection externe d'une onde continue.Enfin, nous avons utilisés des absorbant saturable à base de nanomatériaux déposés sur des tapers optiques dans les lasers à fibre pour générer des impulsions ultracourtes avec une puissance de sortie moyenne élevéeIn this thesis, we investigate experimentally the generation of high energy nanosecond tunable square pulses and high output power ultrashort pulses in fiber lasers. First, since pulse dynamics are dominated by the interaction of the fiber's cubic Kerr nonlinearity and chromatic dispersion with an intensity-discriminating mechanism referred to as a saturable absorber, the stability of a harmonic mode-locked distribution is studied by external injection of a continuous wave. Finally, we implemented nanomaterial based saturable absorbers in fiber laser configuration to generate ultrashort pulses with high average output power. Different techniques of achieving such components are explicitly detailed: ultrashort pulse generation in ring cavities where graphene and topological insulators are deposited on optical tapers to form a saturable absorber
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Kandas, Ishac Lamei Nagiub. "Silica Microspheres Functionalized with Self-assembled Nanomaterials." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/19232.
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A major limitation of silica-based high-Q microcavities is the lack of functionalities such as gain, plasmonic resonance, and second-order nonlinearity. Silica possesses third order nonlinearity but cannot produce second order nonlinearity, plasmonic resonances, or fluorescence emission. The key to overcome this deficiency is to develop versatile methods that can functionalize the surface of a silica microsphere with appropriate nanomaterials. The goal of this thesis is to present and characterize an electrostatic self-assembly based approach that can incorporate a large number of functional materials onto the surface of a silica resonator with nanoscale control. We consider several types of functional materials: polar ionic self-assembled multilayer (ISAM) films that possess second order nonlinearities, Au nanoparticles (NPs) that support plasmonic resonances, and fluorescent materials such as CdSe/ZnS core/shell QDs. A major part of this thesis is to investigate the relationship between cavity Q factors and the amount of nanomaterials deposited onto the silica microspheres. In particular, we fabricate multiple functional microspheres with different ISAM film thickness and Au NPs density. We find that the Q factors of these microspheres are mainly limited by optical absorption in the case of the ISAM film, and a combination of optical absorption and scattering in the case of the Au NPs. By controlling the number of polymer layers or the NPs density, we can adjust the Q factors of these functional microspheres in the range of 106 to 107. An agreement between theoretical prediction and experimental data was obtained. The results may also be generalized to other functional materials including macromolecules, dyes, and non-spherical plasmonic NPs.
We also study the adsorption of Au NPs onto spherical silica surface from quiescent particle suspensions. The surfaces consist of microspheres fabricated from optical fibers and were coated with a polycation, enabling irreversible nanosphere adsorption. Our results fit well with theory, which predicts that particle adsorption rates depend strongly on surface geometry. This is particularly important for plasmonic sensors and other devices fabricated by depositing NPs from suspensions onto surfaces with non-trivial geometries.
We use two additional examples to illustrate the potential applications of this approach. First, we explored the possibility of achieving quasi-phase-matching (QPM) in a silica fiber taper coated with nonlinear polymers. Next, we carry out a preliminary investigation of lasing in a silica fiber coated with CdSe/ZnS core/shell quantum dots (QDs).
Ph. D.
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Hofmann, Matthias Colin. "Second Order Nonlinear Silica-Based Fibers and Microspheres." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/76786.
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After decades of development, optical fiber technology has reached a high degree of sophistication and maturity, and currently serves as the backbone of today''s internet. Despite its technical versatility and capability, current silica fiber technology still has a significant flaw: since silica fibers only possess very weak second order nonlinearity, it has been impossible to develop a large number of important nonlinear optical devices and instruments, such as optical parametric amplifiers (OPA) and optical parametric oscillators (OPO). In this thesis,we show how to overcome this intrinsic limitation, and introduce second order nonlinearity into silica fiber devices.Master of Science
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CHIANG, CHIA-CHI, and 江嘉琪. "Multimode Tapered Fiber Sensor." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/23264534191282230961.
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碩士國立中正大學
物理學系暨研究所
100
In this thesis, fabrication of a multimode tapered fiber is presented. The coating and cladding of the fiber was first removed by using the CO2 laser. Afterward, while heating the uncladded fiber with the Bunsen burner, a tapered fiber was made by pulling the fiber to a desired length by a translational stage. The ability of the fabricated tapered fiber to detect the refractive index (RI) of surrounding media is investigated. It is found that the RI sensitivity of this type of tapered fiber increased with the decreasing of waist diameter of the tapered fiber. Further modification of the tapered fiber with colloidal gold nanoparticles show that the RI sensitivity can be enhanced based on the mechanism of localized surface plasma resonance.
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Chang, Ken-Haw, and 張耿豪. "Experimental Fabrication Of Tapered Fiber Device." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/bmv94p.
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碩士國立交通大學
光電工程所
92
In this thesis, we develop the required fabrication techniques for special tapered fiber devices including single — tapered fibers, super- tapered fiber couplers, and all-fiber optical add-drop multiplexers. Some preliminary experimental results are shown to demonstrate the feasibility of fabricating these devices with commercial fiber coupler fabrication stations.
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Li, Chia-Ming, and 李家銘. "Highly Sensitive Fiber Optic Sensors based on Smart Tapered Fiber Interferometers." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/he8848.
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碩士國立聯合大學
光電工程學系碩士班
101
We have developed two kinds of highly sensitive tapered fiber interferometers (TFI) sensing devices that have smart configurations and high sensitivity for parametric sensing applications. The first fiber sensor demonstrates a novel, directional and sensitive fiber anemometer based on tapered fiber Michelson interferometer configuration. The proposed anemometers based on an anisotropic flat-clad tapered fiber Michelson interferometer enables sensing the direction and magnitude of flowing air (wind) simultaneously. Wavelength shifts and fringes visibility of the measured interference fringes are correlated with the magnitude as well as the direction of the wind. Experimental results show that the proposed directional anemometer can simultaneously and effectively indicate the direction, and sensitively measure the magnitude of wind. Another tapered fiber sensor is based on a fiber Mach-Zehnder interferometer (FMZI) by cascading two fiber tapers. The FMZI can be as a twist fiber sensor to achieve a highly sensitive and in-line sensing. Spectral sensitivity of the proposed sensor strongly depends on taper waist and thinner waist possesses higher sensitivity. Experimental results show that wavelength shifts and spectral loss of the interference fringes depends on the twist angles.
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Lin, Kuan-Hao, and 林冠豪. "Abruptly-tapered fiber Mach-Zehnder interferometric temperature sensors." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/80348473229435776411.
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碩士國立聯合大學
光電工程學系碩士班
104
In this work, we demonstrate micro in-line fiber temperature sensors based on abrupt-tapered Mach-Zehnder interferometer with bimetal. Bimetal is known to be sensitive to ambient temperature variation with its structure automatically being curled. By doing so, the bimetal strip is mounted on abrupt-tapered Mach-Zehnder interferometer to bend the abrupt tapers and phase-shifters to enhance the accuracy and sensitivity of the temperature measurements. The influence of the physical positions for the bimetal is also investigated. This temperature sensor is simple, cost-effective, and is highly promising for many kinds of temperature sensing applications with non-contact requirements in the future.
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Su, Yong-Feng, and 蘇永豐. "1X3 Fused Tapered Sing-mode Fiber Polarization Beamsplitters." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/50911490252744104838.
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碩士逢甲大學
光電物理研究所
94
A 1X3 linearly arrayed fused tapered single-mode fiber polarization beamsplitter has been proposed. An unpolarized light launched its center fiber can be divided into three linearly polarized light at its three output ports. The first polarization modulation waist point in the two power transfer curves of the two side coupled fibers is chosen as the fabrication stopping point. At this coupler pulling point, one polarized component of the input unpolarized light distributes the same power to each coupled port, while the other polarized component keeps all power at the throughput port. We used the electric fusion method to fabricate this novel 1X3 single-mode fiber coupler. 35-nm polarization bandwidth and 25-dB maximum PDL were obtained at the two coupled ports, but the maximum PDL value at the throughput port was only 12 dB.
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Chang, Han-Pin, and 張漢斌. "Tapered Fiber Interferometer for Liquid-Level Sensing Application." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/39940113563273206790.
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碩士國立聯合大學
光電工程學系碩士班
101
In this thesis, the taper fibers, which can be fabricated by a commercial fusion splicer, are used to achieve liquid level sensors. Moreover, we investigate the sensor structure and measurement approaches. The interferometer based on a taper fiber is quite sensitive. For the interference spectra, the power and wavelength of the peak are varied intensely as the taper fiber senses a slight variation from external environment. Therefore, the taper fiber is suitable for a sensor to sense a slight variation in the surroundings. In the work, by using the taper fiber, we have designed two kinds of taper fiber interferometer with different interference scheme. They are reflection tapered fiber Michelson interferometer (RTFMI) and dual- tapered fiber Mach–Zehnder interferometer (DTFMZI). In this thesis, we will probe into these two kinds of interferometer, and compare the sensitivity and the degree of difficulty in fabrication between these two kinds of device. To understand the variation of light while it passes through the taper fiber and facilitate the analysis, we simulated the taper fibers by using a simulation tool firstly, and then tapered a single mode fiber, set up the measurement structure. Finally, the experimental results have been measured. The experimental results reveal that the length of the elastic- plastic and the taper fiber and the diameter of the taper waist relate to the sensitivity of spectral variation greatly. Therefore, a series of comparisons for the interference spectra affected by these parameters are made, and the reasonable explanations are brought up. Ultimately, the experiments of liquid level sensing are made by using different density of liquids. The experimental results show that the difference between the interference spectra of the liquids with very little density-difference is quite obvious. These results verify that the taper fiber interferometer has an outstanding sensitivity again.
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Jen, Li-Yu, and 任立宇. "Multi-Tapered Fiber Coupler with Graded-Index Layers." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/44540358100315615958.
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Liao, Guo Zhu, and 廖國助. "theoretical analysis of fused tapered 3X3 fiber couplers." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/63496926551398490087.
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Henry, Wanda Maree. "Tapered optical waveguides and metal-clad polarisers." Phd thesis, 1988. http://hdl.handle.net/1885/138532.
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Chen, Shan-Chien, and 陳善儉. "Multimode Tapered Fiber Sensor Modified With Nano-gold particle." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/33621002093647084434.
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碩士國立中正大學
物理所
97
A fiber biosensor modified by nano-gold particles is made according to the localized surface plasma resonance theorem. The nano-gold particles enhances the sensitivity of the sensor measuring the refractive index (RI) by absorbing and scattering the evanescent wave on the interface between the core and the liquid to be tested. Different research teams have used different approaches to achieve the same goal. In this study, we pursue our goal by modification of the fiber with nano-gold particles. This fiber is either tapered or non-tapered in advance. Note that taper of the fiber may result in the variations of numerical aperture of the fiber, normalized frequency, and the path of propagating light. In the practice of this work, we use an arc discharge system to pull and taper a multimode fiber (core: 400 μm and cladding: 430 μm, both in diameter) or simply remove the cladding. Afterwards, we modify the fiber with spherical nano-gold particles with a diameter of 15 nm. Consequently, when we measure refractive indices of different liquids with this tailored fiber, the light intensity variation with the refractive indices is enlarged. When pull and taper of the abovementioned fiber yield diameters of 300 μm and 200 μm, the latter shows a better sensitivity that the former. Besides, they are both superior to the uniform fiber which is not tapered. Keyword：nano-gold particle, refractive index, tapered fiber, evanescent wave and localized surface plasma resonance.
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Lin, Timmy, and 林庭伊. "Microfluidics for Tapered-Fiber Sensor to Test Refractive Index." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/14944599289406569317.
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碩士國立陽明大學
生醫光電研究所
100
To measure liquid refractive index is important in applications. The traditional method for the measurement of refractive index (RI) is measuring the critical angle or Brewster’s angle. In this experiment, the tapered fiber sensor adapting “End-etching method” was coated with hot melt glue for chemical etching, the capillary effect to form a sharp tip. The tip size was about 80 to 100 nanometers and with a rough surface when we observed by the SEM. The tapered fiber is a label-free and metal-free sensor. The test method is optical spot confined in the tip. The spot is found to greatly increase when the environmental RI changes from 1.3 to 1.4. The increase in spot size results in the narrowing of the angular intensity distribution. By using a low NA objective to collect the low angular components, the intensity sensitivity up to 8000%/RIU is achieved. This sensitivity indicates that the fiber tip can detect 2.5*10−5 RIU at 0.2% intensity stability. The medium affects the guiding properties and thus changes the optical transmission. The experimental results exhibit that the tapered fiber has a larger dynamic range for RI measurement. In the thesis, these fibers were for 1330 nm wavelength produced by 3M. We designed a method to combine fiber-on-chip for testing liquid refractive indices, to reduce the volume of system and decrease liquid amounts for testing. The liquid flow rates were controlled with syringe pumps. The advantages of tapered fiber systems include small sizes, high sensitivity, dynamic measurement and low cost.
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Fu-WenWu and 吳輔文. "Tapered Optical Fiber Sensors for FRET-Sensitive Nanoparticle Detection." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/wm8ncs.
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