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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 15 of 15 for “"long-period gratings"”.
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Long-Period Gratings as Immuno-Diagnostic biosensors
… refractive index sensitivity of a fiber optic long-period grating. The long period grating couples light from the forward propagating guided core mode of a single-mode fiber into discrete circularly symmetric cladding modes. Due to imperfections in the cladding surface, loss bands are seen in …
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Properties and sensing applications of long-period gratings
A long-period grating is obtained by introducing a periodic refractive index modulation in the core of a hydrogen-sensitized germanosilicate fiber. The phase-matching condition causes light from the fundamental guided mode to couple to discrete, forward-propagating cladding modes. These cladding …
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Fabrication of intensity-based Long-Period-Gratings fiber sensor with CO2 Laser
… technique and procedures for producing long period grating (LPG) fiber sensors with point-by-point irradiation under a CO2 laser beam. The type of fiber sensor under examination is desirable to be highly sensitive to the variation of the thickness and refractive index of a thin film …
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Sensitivity control of optical fiber biosensors utilizing turnaround point long period gratings with self-assembled polymer coatings
… Self-Assembled Multilayers (ISAMs) adsorbed on Long Period Gratings (LPGs) can serve as a highly sensitive, robust, inexpensive optical-based biosensor platform. The ISAM technique is a layer-by-layer deposition method that builds nanometer-thick films based on the principle of Coulomb …
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Beiträge zur Dispersionskompensation basierend auf der Modenkonversion in höhere Moden und der Ausbreitung dieser Moden in Lichtwellenleitern
… of a higher order mode (HOM). In this work long-period gratings (LPG) were considered as mode converters (chapter 4) as they can excite selective and nearly lossless a higher order mode. The modeling und calculation of these gratings, based on the fiber calculation of chapter 3, is presented …
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Long Period Grating-Based pH Sensors for Corrosion Monitoring
… health evaluation of the infrastructure. The long period grating (LPG) element is highly sensitive to refractive index changes and with appropriate design geometry a variety of target molecules can be detected. Optical fiber long period gratings are designed to act as spectral loss elements …
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Fibre gratings in novel optical fibres for applications in sensing
This thesis presents the fabrication of fibre gratings in novel optical fibres for sensing applications. Long period gratings have been inscribed into photonic crystal fibre using the electric-arc technique. The resulting sensing characteristics were found to depend on the air-hole geometry of the …
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Advanced fibre gratings and their applications
… fibre grating devices using Bragg (FBG) and long-period (LPG) structures and their applications in optical communications and sensing. The major contributions presented in this thesis are summarised below. One of the most important contributions from the research work presented in this thesis …
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Sapphire Fiber Based Sensing Technologies for High Temperature Applications
… Fabry-Perot interferometers, fiber Bragg gratings and long period gratings inscribed in sapphire fibers. Lacking the cladding, sapphire fiber is highly multi-moded which renders sapphire fiber based sensor fabrication much more difficult than those based on silica fibers. Among all the …
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Design and characterisation of long period grating (LPG) - based optical fibre sensors for acoustic wave detection
… Representing one type of optical fibre sensors, long period gratings (LPGs) have shown a high sensitivity to a number of parameters, including temperature, strain, refractive index and bending, therefore they have been explored widely for a range of potential sensing applications. This thesis is …
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Composite Films for Modifying Evanescent Wave Characteristics in Long-Period Grating Biosensors
… response. Fiber optical immunosensors based on long-period gratings have limited sensitivity at the refractive index of ordinary aqueous solutions (~1.33). A composite film was designed to raise the local refractive index of the sensor, thus increasing sensitivity. Titanium dioxide deposition …
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Long period fibre grating as gas sensor for environmental pollution monitoring.
… of utilising the inherent properties of long-period gratings (LPGs) to detect the existence and concentration of a given gas in the region immediately surrounding the fibre cladding. The principle and the viability of using LPGs for sensor applications is supported by the preliminary …
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Development of an Optical Fiber Biosensor with Nanoscale Self-Assembled Affinity Layer
Optical sensor systems that integrate Long-Period-Gratings (LPG) as the detection arm have been proven to be highly sensitive and reliable in many applications. With increasing public recognition of threats from bacteria-induced diseases and their potential outbreak among densely populated …
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Ionic Self-Assembled Multilayers in a Long Period Grating Sensor for Bacteria and as a Source of Second-Harmonic Generation Plasmonically Enhanced by Silver Nanoprisms
… The sensor was based on a turn-around point long period fiber grating (TAP-LPG). Unlike conventional LPGs, in which the attenuation peaks shift wavelength in response to environmental changes, TAP-LPGs have a highly sensitive single wavelength peak with variable attenuation. ISAMs were …