Dissertations / Theses on the topic 'Sagnac interferometer'
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1
McConnell, Sean R. "Gas detection by use of Sagnac interferometer." Thesis, Queensland University of Technology, 2008. https://eprints.qut.edu.au/16701/1/Sean_McConnell_Thesis.pdf.
Full textAbstract:
Gas composition and analysis forms a large field of research whose requirements demand that measurement equipment be as affordable, uncomplicated and convenient as possible. The precise quantitative composition of an atmospheric, industrial or chemically synthesised sample of gas is of utmost importance when inferring the properties and nature of the environment from which the sample was taken, or for inferring how a prepared sample will react in its application. The most popular and widely used technique to achieve this is Gas Chromatography-Mass Spectrometry (GCMS) and, without a doubt, this technique has set the standard for gas analysis. Despite the accuracy of the GCMS technique, the equipment itself is bulky, expensive and cannot be applied readily to field work. Instead, most field work is conducted using a single gas detector, capable only of detecting one particular molecule or element at a time. Presented here is an interferometric technique that theoretically, has the ability to address all three issues of bulkiness, affordability and convenience, whilst not being limited to one particular element or molecule in its analysis. Identifying the unknown constituents of a gaseous mixture using the proposed method, employs the optical refractive properties of the mixture to determine its composition. A key aspect of this technique is that the refractive index of an arbitrary mixture of gases will vary depending on pressure and wavelength1. The Lorentz-Lorenz formula and the Sellmeier equations form the foundation of the theoretical background. The optical refractive properties of air and other atmospheric gases have been well established in the literature. The experimental investigations described here have been conducted based on this, insofar as no analysis has been conducted on gases that do not naturally occur in reasonable abundance in the atmosphere. However this does not in any way preclude the results and procedure developed from applying to a synthesised gas mixture. As mentioned, the platform of this technique relies on the pressure and wavelength dependence of the refractivity of the gas. The pressure dependence of the system is easily accounted for, in making this claim however it is still imperative the mixture be impervious to contamination from the wider atmosphere. Wavelength dependence however is perhaps slightly more difficult to accommodate. Multiple lasers, of differing wavelength form the radiative sources which underpin the method developed. Laser sources were chosen because of their coherence, making it easy to produce interference, when combined with the inherent stability of the Sagnac interferometer, provides for a very user friendly system that is able to quickly take results. The other key part of the experimental apparatus is the gas handling system, the gas(es) of interest need to be contained within an optical medium in the path of one of the beams of the interferometer. Precise manipulation of the pressure of the gas is critical in determining concentration, this has been achieved through the use of a gas syringe whose plunger is moved on a finely threaded screw, and measured on a digital manometer. The optical setup has also been explored, specifically in ruling out the use of such radiative sources as passing an incandescent source through a monochromator or the use of LED's to produce interference before settling on lasers to produce the required interference. Finally, a comprehensive theoretical background has been presented using classical electromagnetic theory as well as confirmation from a quantum perspective. The theoretical background for this study relies upon the Lorentz-Lorenz formula. It is commonly presented either from a classical or quantum perspective, in this work both classical and quantum mechanical treatments are given whilst also showing how each confirms the other. Furthermore, a thorough investigation into the dispersion functions of each of the major components of the atmosphere has been compiled from the study of refractivity on individual gases from other authors, in some cases, where no work has been done previously, this has been derived. The technique developed could be considered an ample addition to gas analysis techniques in certain circumstances in terms of expense, convenience and accuracy. The system can predict relative quantities of constituents of the atmosphere to at least 3%. The method described here would allow researchers more time to concentrate on actual results and more resources to allocate to broadening intellectual horizons. This would certainly justify further development.
2
McConnell, Sean R. "Gas detection by use of Sagnac interferometer." Queensland University of Technology, 2008. http://eprints.qut.edu.au/16701/.
Full textAbstract:
Gas composition and analysis forms a large field of research whose requirements demand that measurement equipment be as affordable, uncomplicated and convenient as possible. The precise quantitative composition of an atmospheric, industrial or chemically synthesised sample of gas is of utmost importance when inferring the properties and nature of the environment from which the sample was taken, or for inferring how a prepared sample will react in its application. The most popular and widely used technique to achieve this is Gas Chromatography-Mass Spectrometry (GCMS) and, without a doubt, this technique has set the standard for gas analysis. Despite the accuracy of the GCMS technique, the equipment itself is bulky, expensive and cannot be applied readily to field work. Instead, most field work is conducted using a single gas detector, capable only of detecting one particular molecule or element at a time. Presented here is an interferometric technique that theoretically, has the ability to address all three issues of bulkiness, affordability and convenience, whilst not being limited to one particular element or molecule in its analysis. Identifying the unknown constituents of a gaseous mixture using the proposed method, employs the optical refractive properties of the mixture to determine its composition. A key aspect of this technique is that the refractive index of an arbitrary mixture of gases will vary depending on pressure and wavelength1. The Lorentz-Lorenz formula and the Sellmeier equations form the foundation of the theoretical background. The optical refractive properties of air and other atmospheric gases have been well established in the literature. The experimental investigations described here have been conducted based on this, insofar as no analysis has been conducted on gases that do not naturally occur in reasonable abundance in the atmosphere. However this does not in any way preclude the results and procedure developed from applying to a synthesised gas mixture. As mentioned, the platform of this technique relies on the pressure and wavelength dependence of the refractivity of the gas. The pressure dependence of the system is easily accounted for, in making this claim however it is still imperative the mixture be impervious to contamination from the wider atmosphere. Wavelength dependence however is perhaps slightly more difficult to accommodate. Multiple lasers, of differing wavelength form the radiative sources which underpin the method developed. Laser sources were chosen because of their coherence, making it easy to produce interference, when combined with the inherent stability of the Sagnac interferometer, provides for a very user friendly system that is able to quickly take results. The other key part of the experimental apparatus is the gas handling system, the gas(es) of interest need to be contained within an optical medium in the path of one of the beams of the interferometer. Precise manipulation of the pressure of the gas is critical in determining concentration, this has been achieved through the use of a gas syringe whose plunger is moved on a finely threaded screw, and measured on a digital manometer. The optical setup has also been explored, specifically in ruling out the use of such radiative sources as passing an incandescent source through a monochromator or the use of LED's to produce interference before settling on lasers to produce the required interference. Finally, a comprehensive theoretical background has been presented using classical electromagnetic theory as well as confirmation from a quantum perspective. The theoretical background for this study relies upon the Lorentz-Lorenz formula. It is commonly presented either from a classical or quantum perspective, in this work both classical and quantum mechanical treatments are given whilst also showing how each confirms the other. Furthermore, a thorough investigation into the dispersion functions of each of the major components of the atmosphere has been compiled from the study of refractivity on individual gases from other authors, in some cases, where no work has been done previously, this has been derived. The technique developed could be considered an ample addition to gas analysis techniques in certain circumstances in terms of expense, convenience and accuracy. The system can predict relative quantities of constituents of the atmosphere to at least 3%. The method described here would allow researchers more time to concentrate on actual results and more resources to allocate to broadening intellectual horizons. This would certainly justify further development.
3
Schubert, Christian [Verfasser]. "Grossflächiges Sagnac Interferometer mit kalten Atomen / Christian Schubert." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2012. http://d-nb.info/1024389138/34.
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4
Kaufer, Henning [Verfasser]. "Opto-mechanics in a Michelson-Sagnac interferometer / Henning Kaufer." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2014. http://d-nb.info/1051038162/34.
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5
Dutta, Indranil. "Stability improvement of a sagnac cold atom interferometer : towards continuous operation." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066572/document.
Full textAbstract:
Cette thèse a pour objet de repousser les performances d'un interféromètre à atomes froids principalement sensible aux rotations selon un axe particulier. Des atomes de Cesium sont refroidis par laser, piégés, et lancés verticalement selon une configuration en fontaine. La sensibilité du gyromètre repose sur l'effet Sagnac et est proportionnelle à l'aire physique qu'entourent les deux bras de l'interféromètre. Nous utilisons des transitions Raman stimulées pour séparer les ondes atomiques et former une géométrie d'interféromètre de type Mach-Zehnder replié. Avec un temps d'interrogation de 800 ms, nous parvenons à une aire physique de 11 cm^2. Le manuscrit décrit les améliorations apportées au dispositif expérimental pour faire fonctionner le gyromètre avec une telle aire Sagnac. Une procédure d'alignement relatif des faisceaux Raman au niveau du microrad est présentée et est particulièrement importante pour permettre aux ondes de matière d'interférer. La caractérisation des bruits de vibration impactant la sensibilité du gyromètre, ainsi que sa réjection sont également décrites. Nous démontrons une sensibilité de 160 nrad/s à 1 s, et une stabilité long terme de 1.8 nrad/s après 10 000 s d'intégration. Ce niveau de stabilité représente une amélioration d'un facteur 5 par rapport à la précédente expérience de gyromètre du SYRTE de 2009, et d'un facteur 15 par rapport aux autres résultats publiés. Cette thèse présente également une nouvelle méthode d'interrogation des atomes pour opérer le gyromètre sans temps morts, un aspect important pour diverses applications des capteurs à atomes froids en navigation inertielle, en géophysique et en physique fondamentaleThis thesis aims at pushing the performances of a cold atom interferometer principally sensitive to rates of rotation in a particular axis. In our experiment, Cesium atoms are laser cooled, trapped and launched in a fountain configuration. According to the Sagnac effect, the sensitivity of the interferometer to rotation is proportional to the area enclosed by the interferometer arms. We use stimulated Raman transitions to split the atoms in two paths and to form a folded Mach-Zehnder-like interferometer architecture using four Raman pulses. With an interrogation time of the atoms of 800 ms, we achieve a Sagnac area as high as 11 cm^2. The thesis describes the improvements to the experimental setup to operate the gyroscope with such a high Sagnac area. A procedure for the relative alignment of the Raman beams at the microrad level is presented, which is critical to meet the interference condition of the cold atoms at the interferometer output. The characterization and mitigation of the vibration noise, affecting the gyroscope, is also demonstrated. We finally demonstrate a short term rotation stability of 160 nrad/s at 1 s and a long term stability of 1.8 nrad/s after 10 000 s of integration time. This stability level represents a factor 5 improvement compared to the previous SYRTE gyroscope experiment of 2009 and a factor 15 compared to other published results. The thesis work also presents a new method of interrogation to operate the gyroscope without dead times, which is important for various applications of cold atom sensors in inertial navigation, geophysics and in fundamental physics
6
Schreiber, Michael Stuart. "ADVANCES IN THE OPTO-MECHANICAL DESIGN AND ALIGNMENT OF THE HEHSI IMAGING SPECTROMETER BASED ON A SAGNAC INTERFEROMETER." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2463.
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The High Efficiency HyperSpectral Imager (HEHSI) is a Fourier Transform hyperspectral imager based on a Sagnac interferometer. This thesis research concentrates on the design upgrade and calibration of HEHSI from a proof of concept instrument to a prototype field instrument. Stability is enhanced by removing degrees of freedom and alignment is enhanced by providing for in-situ adjustments. The use of off the shelf components allows for reduced development time and cost constraints. HEHSI is capable of multiple configurations to accommodate sensors and optics with specialized capabilities for multiple wavelength ranges and viewing conditions. With a spectral response of 400 to 1000 nanometers in the visible and very near IR as well as 900 to 1700nm in the Near IR. Creation and use of a real time feedback alignment utility allow quantifiable signal comparison and image alignment. Advances allow for HEHSI to remain aligned during data collection sessions and confirmation of alignment through quantitative measures.M.S.M.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
7
Altorio, Matteo. "Novel atom interferometry techniques for a cold-atom gyroscope of large Sagnac area Atom interferometry with top-hat laser beams Improving the phase response of an atom interferometer by means of temporal pulse shaping." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS449.
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Cette thèse décrit la mise en œuvre de nouvelles techniques d'interférométrie atomique améliorant la stabilité et l’exactitude d'un gyromètre à atomes froids situé au laboratoire SYRTE. Des transitions Raman stimulées permettent de séparer et recombiner les ondes atomiques. Une séquence de quatre impulsions lumineuses génère un interféromètre avec une aire Sagnac de 11 cm2. Je présente la mise en œuvre d'un schéma d'interrogation entrelacé dans un interféromètre dont le temps d'interrogation est de 801 ms, dans lequel trois nuages atomiques sont interrogés simultanément résultant en une cadence de mesure de 3,75 Hz. Avec ce schéma, nous démontrons une sensibilité de 30 nrad/s/sqrt(Hz). Nous présentons ensuite des mesures de rotation dynamiques dans une plage jusqu'ici inexplorée pour un capteur à atomes froids. Un biais important du capteur provient d'un couplage entre un désalignement relatif des miroirs rétroréfléchissant les faisceaux Raman et la trajectoire de l'atome. Une technique est introduite pour réduire ce biais au niveau de 3 nrad/s et atteindre une stabilité à long terme de 0,3 nrad/s qui représente l'état de l'art des gyromètres atomiques. Le manuscrit décrit ensuite la première caractérisation du facteur d'échelle du gyromètre à l'aide de différentes techniques. En particulier, la mise en place d’une plateforme de rotation sous le capteur permet de faire varier la projection du vecteur rotation de la Terre sur l'interféromètre et donc de moduler le déphasage de rotation. Les techniques présentées dans cette thèse ouvrent la voie à un test de l'effet Sagnac pour les ondes de matière avec une précision relative inférieure à 100 parties par millionThis thesis describes the implementation of new atom interferometry techniques to improve the stability and accuracy of a cold-atom gyroscope located at the SYRTE laboratory. Stimulated Raman transitions are used to split and recombine the atomic waves. A sequence of four light pulses generates an interferometer with a Sagnac area of 11 cm2. I present the implementation of an interleaved interrogation scheme, where three atomic clouds are interrogated simultaneously in an atom interferometer featuring a sampling rate of 3.75 Hz and an interrogation time of 801 ms. With this scheme we demonstrate a short-term sensitivity of 30 nrad·s-1·Hz-1/2. We then present measurements of dynamic rotation rates in a so far unexplored range for a cold atom sensor. An important bias of the sensor originates from a coupling between a relative misalignment of the mirrors which retro-reflect the Raman beams and the trajectory of the atom. A technique is introduced to reduce this bias at the level of 3 nrad·s-1 and to achieve a long-term stability of 0.3 nrad·s-1 which represents the state of the art for atomic gyroscopes. The manuscript then describes the first characterization of the scale factor of the gyroscope using different techniques. In particular, the implementation of a rotation stage below the sensor enables us to vary the projection of the Erath rotation rate vector onto the interferometer area and therefore to modulate the rotation phase shift. The implementation of the techniques presented in this thesis pave paving the way to a test of the Sagnac effect for matter waves with a relative accuracy level below 100 parts per million
8
Secmen, Basak. "Simulation On Interferometric Fiber Optic Gyroscope With Amplified Optical Feedback." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1253657/index.pdf.
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Position and navigation of vehicle in two and three dimensions have been important as being advanced technology. Therefore, some system has been evaluated to get information of vehicle&rsquos position. Main problem in navigation is how to determine position and rotation in three dimensions. If position and rotation is determined, navigation will also be determined with respect to their initial point. There is a technology that vehicle velocity can be discovered, but a technology that rotation can be discovered is needed. Sensor which sense rotation is called gyroscope. If this instrument consists of optical and solid state material, it&rsquo
s defined by Fiber Optic Gyroscope (FOG). There are various studies in order to increase the sensitivity of fiber optic gyroscopes, which is an excellent vehicle for sensing rotation. One of them is interferometric fiber optic gyroscope with amplified optical feedback (FE_FOG). In this system, a feedback loop, which sent the output pulse through the input again, is used. The total output is the summation of each interference and it is in pulse state. The peak position of the output pulse is shifted when rotation occurs. Analyzing this shift, the rotation angle can be determined. In this study, fiber optic gyroscopes, their components and performance characteristics were reviewed. The simulation code was developed by VPIsystems and I used VPItransmissionMakerTM software in this work. The results getting from both rotation and nonrotation cases were analyzed to determine the rotation angle and sensitivity of the gyroscope.
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PLAZAS, ORTEGA Lucero. "Compressão de ruído quântico em um interferômetro Sagnac em fibra com laser pulsado em 1,55 microns." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/18323.
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Compressão de Ruído Quantico em um Interferometro Sagnac em Fibra com um Laser Pulsado em 1,55 Microns - Dissertação de Mestrado em Física - Lucero Plazas Ortega.pdf: 7191693 bytes, checksum: 4eba611a9cee045f7f06747bb63a80cb (MD5)Made available in DSpace on 2017-02-15T13:05:07Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Compressão de Ruído Quantico em um Interferometro Sagnac em Fibra com um Laser Pulsado em 1,55 Microns - Dissertação de Mestrado em Física - Lucero Plazas Ortega.pdf: 7191693 bytes, checksum: 4eba611a9cee045f7f06747bb63a80cb (MD5) Previous issue date: 2015-02-24
CAPES
Componentesemquadraturadocampoeletromagn´eticoobedecemaoprincipio de incerteza de Heisenberg. Como resultado a Mecˆanica Quˆantica prevˆe que estas componentes n˜ao podem ser especificadas simultaneamente com precis˜ao ilimitada. Estados de incerteza m´ınima (estados coerentes) permitem atingir o menor produto das incertezas em cada quadratura, ambas de mesma magnitude. Al´em disto ´e poss´ıvel construir estados quˆanticos comprimidos, para os quais uma das suas quadraturas atinge um valor menor para o desvio padr˜ao queaqueledefinidoparaumestadodem´ınimaincerteza,incrementandoconsequentemente a incerteza na outra quadratura. Nesta disserta¸c˜ao fazemos uma revis˜ao destes conceitos e apresentamos um esquema experimental com o qual geramosestadoscomprimidos(squeezedstates)daradia¸c˜ao. Este´ebaseadoem umlaserdefibrapulsado(comprimentodeondaλ = 1.56µm, taxaderepeti¸c˜ao fR = 146MHz, largura de pulso τp = 200fs) associado a um interferˆometro de Sagnac n˜ao linear em fibra. Al´em de uma descri¸c˜ao dos principais componentes ´opticos ser˜ao discutidos os mecanismos de gera¸c˜ao e caracteriza¸c˜ao dos estados comprimidos.
QuadraturecomponentsofthefieldobeyaHeisenberguncertaintyrelation. As a result, quantum mechanics predicts that these components cannot be specified simultaneously with unlimited accuracy. Minimum uncertainty states or coherent states, allow reaching the lowest value of the uncertainty in each quadrature component, both having the same magnitude. It is still possible to construct squeezed quantum states, for which, one of its quadrature components achieves a less value for standard deviation than one that have a state of minimum uncertainty, with the consequence of an increase in the uncertainty of the other quadrature. In this dissertation, these concepts are reviewed and we provide an experimental scheme in order to generate squeezed states of light. This design is based on a pulsed fiber laser (λ = 1.56µm, repetition rate fR = 146MHz, pulse width τp = 200fs) coupled with a nonlinear interferometer, which is composed by a fiber loop in a Sagnac configuration. In order to discuss the experimental results obtained with this scheme, will be carried out adescriptionofthemainopticalcomponents,takingintoaccounttheprincipal mechanisms of generating and measuring of squeezed states.
10
Shaddock, Daniel Anthony, and Daniel Shaddock@jpl nasa gov. "Advanced Interferometry for Gravitational Wave Detection." The Australian National University. Faculty of Science, 2001. http://thesis.anu.edu.au./public/adt-ANU20020227.171850.
Full textAbstract:
In this thesis we investigate advanced techniques for the readout and control of various interferometers. In particular, we present experimental investigations of interferometer configurations and control techniques to be used in second generation interferometric gravitational wave detectors. We also present a new technique, tilt locking, for the readout and control of optical interferometers.
¶
We report the first experimental demonstration of a Sagnac interferometer with resonant sideband extraction (RSE). We measure the frequency response to modulation of the length of the arms and demonstrate an increase in signal bandwidth of by a factor of 6.5 compared to the Sagnac with arm cavities only. We compare Sagnac interferometers based on optical cavities with cavity-based Michelson interferometers and find that the Sagnac configuration has little overall advantage in a cavity-based system.
¶
A system for the control and signal extraction of a power recycled Michelson interferometer with RSE is presented. This control system employs a frontal modulation scheme requiring a phase modulated carrier field and a phase modulated subcarrier field. The system is capable of locking all 5 length degrees of freedom and allows the signal cavity to be detuned over the entire range of possibilities, in principle, whilst maintaining lock. We analytically investigate the modulation/demodulation techniques used to obtain these error signals, presenting an introductory explanation of single sideband modulation/demodulation and double demodulation.
¶
This control system is implemented on a benchtop prototype interferometer. We discuss technical problems associated with production of the input beam modulation components and present several solutions. Operation of the interferometer is demonstrated for a wide range of detunings. The frequency response of the interferometer is measured for various detuned points and we observe good agreement with theoretical predictions. The ability of the control system to maintain lock as the interferometer is detuned is experimentally demonstrated.
¶
Tilt locking, a new technique to obtain an error signal to lock a laser to an optical cavity, is presented. This technique produces an error signal by efficient measurement of the interference between the TEM00 and TEM10 modes. We perform experimental and theoretical comparisons with the widely used Pound-Drever-Hall (PDH) technique. We derive the quantum noise limit to the sensitivity of a measurement of the beam position, and using this result calculate the shot noise limited sensitivity of tilt locking. We show that tilt locking has a quantum efficiency of 80%, compared to 82% for the PDH technique.
We present experimental demonstrations of tilt locking in several applications including frequency stabilisation, continuous-wave second harmonic generation, and injection locking of a Nd:YAG slab laser. In each of these cases, we demonstrate that the performance of tilt locking is not the limiting factor of the lock stability, and show that it achieves similar performance to the PDH based system.
¶
Finally, we discuss how tilt locking can be effectively applied to two beam interferometers. We show experimentally how a two beam interferometer typically gives excellent isolation against errors arising from changes in the photodetector position, and experimentally demonstrate the use of tilt locking as a signal readout system for a Sagnac interferometer.
11
Kurth, Martin Lyndon. "Scattering of guided waves in thick gratings at extreme angles." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16347/1/Martin_Kurth_Thesis.pdf.
Full textAbstract:
The aim of this project was to develop a passive optical compensating arrangement that would allow the formation and continued stability of interference patterns over a long timescale and also to investigate optical wave scattering in thick gratings at extreme angles of scattering. A novel passive arrangement based on a Sagnac interferometer is described that produces interference patterns more stable than those produced by a conventional arrangement. An analysis of the arrangement is presented that shows it to be an order of magnitude more stable than an equivalent conventional approach. The excellent fringe stability allowed holographic gratings with small periods (~ 0.5 μm) to be written in photorefractive lithium niobate with low intensity writing fields (~mW/cm2) produced by a He:Ne laser, despite long grating fabrication times (~ 1000 s). This was possible because the optical arrangement compensated for phase shifts introduced by translational and rotational mirror motion caused by environmental perturbations. It was shown that the rapid introduction of a phase shift in one of the writing fields can change the direction of energy flow in the two-wave mixing process. It was found that the improvement in stability of the modified Sagnac arrangement over a conventional interferometer decreased when the crossing angle was increased and that the point about which the mirrors are rotated greatly affects the stability of the arrangement. For a crossing angle of 12 degrees, the modified Sagnac arrangement is more than twice as stable when the mirrors are rotated about their midpoints, rather than their endpoints. Investigations into scattering in the extremely asymmetrical scattering (EAS) geometry were undertaken by scattering light from a 532nm Nd:YAG laser off gratings written in photorefractive barium titanate and lithium niobate. Despite the difficulties posed by background noise, there was very good agreement between the observed scattered field and that predicted by a previously established theoretical model. Thus, this work represents the first experimental observation of EAS in the optical part of the spectrum.
12
Kurth, Martin Lyndon. "Scattering of guided waves in thick gratings at extreme angles." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16347/.
Full textAbstract:
The aim of this project was to develop a passive optical compensating arrangement that would allow the formation and continued stability of interference patterns over a long timescale and also to investigate optical wave scattering in thick gratings at extreme angles of scattering. A novel passive arrangement based on a Sagnac interferometer is described that produces interference patterns more stable than those produced by a conventional arrangement. An analysis of the arrangement is presented that shows it to be an order of magnitude more stable than an equivalent conventional approach. The excellent fringe stability allowed holographic gratings with small periods (~ 0.5 μm) to be written in photorefractive lithium niobate with low intensity writing fields (~mW/cm2) produced by a He:Ne laser, despite long grating fabrication times (~ 1000 s). This was possible because the optical arrangement compensated for phase shifts introduced by translational and rotational mirror motion caused by environmental perturbations. It was shown that the rapid introduction of a phase shift in one of the writing fields can change the direction of energy flow in the two-wave mixing process. It was found that the improvement in stability of the modified Sagnac arrangement over a conventional interferometer decreased when the crossing angle was increased and that the point about which the mirrors are rotated greatly affects the stability of the arrangement. For a crossing angle of 12 degrees, the modified Sagnac arrangement is more than twice as stable when the mirrors are rotated about their midpoints, rather than their endpoints. Investigations into scattering in the extremely asymmetrical scattering (EAS) geometry were undertaken by scattering light from a 532nm Nd:YAG laser off gratings written in photorefractive barium titanate and lithium niobate. Despite the difficulties posed by background noise, there was very good agreement between the observed scattered field and that predicted by a previously established theoretical model. Thus, this work represents the first experimental observation of EAS in the optical part of the spectrum.
13
Yan, Wenhua. "Design of a magnetic guide for rotation sensing by on chip atom interferometry." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066548.
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Ce mémoire présente la conception et réalisation d'un montage expérimental pour le développement d'un interféromètre à atomes froids de 87Rb guidés sur un microcircuit à atomes, l'objectif final étant la réalisation d'un capteur inertiel de rotations. Nous avons ainsi étudié théoriquement le confinement magnétique des atomes dans un guide circulaire. Une telle étude nous a permis d'identifier les principales problématiques liées à la propagation sur une orbite stable d'un paquet d'onde atomique dans un guide magnétique, à savoir: la rugosité du potentiel de guidage, les défauts du potentiel associés au motif de micro fils employés pour créer ce potentiel, et les pertes par effet Majorana. Dans cette thèse nous proposons des solutions originales à ces problèmes basés sur des études précédentes et sur les résultats de nos calculs. Du point de vue expérimental, nous avons monté une nouvelle expérience d'atomes froids dont la principale caractéristique est d'être compacte et donc transportable pour des mesures locales de vitesses de rotations. Nous avons donc, au cours de ce travail, assemblé un système à ultra vide efficace, développé un banc optique très compacte comprenant des sources laser pour le refroidissement et piégeage des atomes, un laser de Bragg pour la réalisation de l'interféromètre atomique, ainsi que toute l'électronique de contrôle de cette expérienceThis manuscript present the design and realization of an experimental setup for the development of a cold atom interferometer using 87Rb atoms guided on an atom chip, the final goal being the realization of an inertial sensor for rotation measurements. We have therefore study theoretically the magnetic confinement of these atoms in a circular guide. Such a study allowed us to identify the main challenges linked to the atomic wave packet propagation along a stable circular orbit in a magnetic guide, namely: the roughness of the guiding potential, the magnetic potential defects associated to the pattern of the micro wires used to produce this potential, and the Majorana losses. In this thesis we propose original solutions to these questions based on preliminary studies and on the results of our calculations. From the experimental point of view, we have assembled a new cold atom experiment with the main feature of being compact and therefore transportable for in situ measurement of rotations. We have along this work put together an efficient ultra high vacuum system, developed a compact optical bench containing the laser sources for cooling and trapping, a Bragg laser for the atom interferometer, as well as all the needed electronics to control the experiment
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Ferreira, Vinícius Castro. "Espectroscopia ótica não linear em anel antirressonante." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/150054.
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Este trabalho abordará uma breve descrição de fenômenos óticos não lineares, apresentando resultados de caracterização ótica não linear para diferentes materiais, assim como resultados para uma nova técnica de caracterização. Serão apresentados aspectos básicos de determinação do índice de refração não linear através da técnica de varredura Z que é um método bem estabelecido e amplamente difundido. Esta técnica porém não é eficiente para filmes finos e amostras com baixa não linearidade. Com a utilização de uma montagem interferométrica é possível gerar um crescimento na sensibilidade da técnica, atenuando o oscilador local sem nenhuma perda no sinal não linear gerado, acarretando em uma melhoria da relação sinal-ruído.An introduction to nonlinear optics will be addressed in this work, presenting results of optical characterization to many different materials as well as results from a new characterization technique. Basic aspects to nonlinear index refraction measurement will be presented through Z-scan, which is a well-established method. This technique is not efficient for thin films or samples presenting low nonlinearity. Using a interferometric setup is possible to produce an increase in sensibility, attenuanting local oscillator without degrading the generated nonlinear signal, what establishes a better signal-noise relation.
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Queiroz, Alex Sander Barros. "Estudo do desempenho de componentes baseados em fibras Ãpticas especiais: fibras de cristal fotÃnico e de metamateriais e suas aplicaÃÃes em comunicaÃÃes." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=15842.
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nÃo hÃNeste trabalho foi realizado um estudo numÃrico do interferÃmetro de Sagnac baseado em cristais fotÃnicos e de acoplador Ãptico de metamaterial. Na simulaÃÃo do interferÃmetro foram analisados os efeitos da propagaÃÃo da luz, considerando-se a dispersÃo de velocidade de grupo (GVD) e de terceira ordem (TOD), espalhamento Raman intrapulso, auto-inclinaÃÃo (Self-steepening) e auto-modulaÃÃo de fase na equaÃÃo nÃo linear de SchrÃdinger generalizada. No primeiro momento foi realizado o estudo para quatro fatores de razÃo de divisÃo da potÃncia incidente em uma das portas do dispositivo e trÃs dimensÃes para o comprimento do anel do dispositivo. Para caracterizar o desempenho do sistema, foram analisadas as curvas de transmissÃo, taxa de extinÃÃo, crosstalk e fator de compressÃo do pulso transmitido. No segundo momento, foi verificada a performance do chaveamento nÃo-linear para obtenÃÃo de porta lÃgica sob ModulaÃÃo por Amplitude de Pulsos (PAM). Excitando-se as duas portas de entrada do dispositivo com nÃveis lÃgicos "0" e "1", observando o seu comportamento em uma das saÃdas do dispositivo. Inicialmente, variou-se o parÃmetro de ajuste da modulaÃÃo (|ε|), obtendo-se apenas a porta lÃgica OR. E, em uma segunda aplicaÃÃo, manteve-se o parÃmetro da modulaÃÃo fixa e variou-se a fase de uma das portas de entrada, de 0 a 2π rad, encontrando-se portas lÃgicas do tipo OR, AND e XOR. TambÃm foram estudadas as caracterÃsticas de um guia metamaterial que possui a parte real da permissividade elÃtrica e da permeabilidade magnÃtica negativas. Esse guia metamaterial à acoplado com um guia convencional, observando-se as caracterÃsticas de transmissÃo e potÃncia crÃtica desse tipo de acoplador e, comparando-se com um acoplador convencional. Para essa anÃlise foi utilizado um perfil de automodulaÃÃo decrescente linearmente com cinco valores mÃnimo, observando-se um comportamento de histerese.
In this paper we present a numerical study of the Sagnac interferometer based on photonic crystals and optical coupler metamaterial. In the simulation of the interferometer effects of light propagation were analyzed, considering the dispersion of the group velocity (GVD) and third order (TOD), intrapulse Raman scattering, self-slope (self-steepening) and self-modulation phase in the generalized non-linear SchrÃdinger equation. The first time the study was conducted for four power division ratio of factors incident in one of the device ports and three dimensions for the device ring length. To characterize the system performance, were analyzed the transmission curves, extinction ratio, crosstalk and compression factor of the transmitted pulse. In the second moment, the performance of the non-linear switching was observed for obtaining gate under Pulse Amplitude Modulation (PAM). Exciting the two device input ports with logical levels "0" and "1", observing their behavior in one of the device outputs. Initially, the modulation is varied adjustment parameter (| ε |), obtaining only the logical OR gate. And in a second application, the fixed modulation parameter remained and was varied the phase of the input ports 0 to 2π rad, lying type logic gate OR, AND and XOR. The characteristics of a metamaterial guide that has the real part of electrical permittivity and magnetic permeability negatives were also studied. This metamaterial guide is coupled to a conventional guide, observing the transmission characteristics and critical power of this type of coupler and compared with a conventional coupler. For this analysis we used a decreasing automodulation profile linearly with five minimum, observing a hysteresis behavior.
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Noble, Adam. "Sagnac interferometry and fundamental physics." Thesis, Lancaster University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441781.
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Kajari, Endre [Verfasser]. "Perspectives on Relativistic Sagnac Interferometry / Endre Kajari." München : Verlag Dr. Hut, 2011. http://d-nb.info/1018981160/34.
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Bogdanski, Jan. "Experimental multiuser secure quantum communications." Doctoral thesis, Stockholms universitet, Fysikum, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-26498.
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We are currently experiencing a rapid development of quantum information, a new branch of science, being an interdisciplinary of quantum physics, information theory, telecommunications, computer science, and many others. This new science branch was born in the middle of the eighties, developed rapidly during the nineties, and in the current decade has brought a technological breakthrough in creating secure quantum key distribution (QKD), quantum secret sharing, and exciting promises in diverse technological fields. Recent QKD experiments have achieved high rate QKD at 200 km distance in optical fiber. Significant QKD results have also been achieved in free-space. Due to the rapid broadband access deployment in many industrialized countries and the standing increasing transmission security treats, the natural development awaiting quantum communications, being a part of quantum information, is its migration into commercial switched telecom networks. Such a migration concerns both multiuser quantum key distribution and multiparty quantum secret sharing that have been the main goal of my PhD studies. They are also the main concern of the thesis. Our research efforts in multiuser QKD has led to a development of the five-user setup for transmissions over switched fiber networks in a star and in a tree configuration. We have achieved longer secure quantum information distances and implemented more nodes than other multi-user QKD experiments. The measurements have shown feasibility of multiuser QKD over switched fiber networks, using standard fiber telecom components. Since circular architecture networks are important parts of both intranets and the Internet, Sagnac QKD has also been a subject of our research efforts. The published experiments in this area have been very few and results were not encouraging, mainly due to the single mode fiber (SMF) birefringence. Our research has led to a development of a computer controlled birefringence compensation in Sagnac that open the door to both classical and quantum Sagnac applications. On the quantum secret sharing side, we have achieved the first quantum secret sharing experiment over telecom fiber in a five-party implementation using the "plug & play" setup and in a four-party implementation using Sagnac configuration. The setup measurements have shown feasibility and scalability of multiparty quantum communication over commercial telecom fiber networks.
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Yu, Aihua. "Application of optical fibre Sagnac interferometers in optical modulators and sensors." Thesis, University of Essex, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332807.
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Harvey, David. "Automatically phase-locked fibre optic electronic speckle pattern interferometry using laser vibrometry." Thesis, Heriot-Watt University, 1996. http://hdl.handle.net/10399/715.
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Xia, Jing. "Optical studies of broken time-reversal symmetry in solids using Sagnac interferometry /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Skalský, Michal. "Snímač úhlové rychlosti se Sagnacovým interferometrem." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-240886.
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This thesis deals with theoretical description of fiber-optic angular velocity sensors, or gyroscopes, and further with design and construction of own sensor of this type. The theoretical part describes problematics of interferometric and resonant fiber-optic gyroscopes. Basic principles and physical limits are described for both types. The main focus is then put on analysis of possible conceptions of these sensors. Solutions using different optical configurations as well as various modulation and signal processing schemes are discussed. The practical part deals with design and construction of own interferometric fiber-optic gyroscope in closed-loop configuration. The gyroscope utilizes all-fiber components including piezoelectric phase modulator and unexpensive single-mode fiber, which are commonly used only for open-loop configurations. To realize closed-loop operation, special modulation scheme based on fully harmonic signal was develeped, which yields linear output within wide dynamic range. This type of modulation requires high level of synchronization achieved by using a field-programmable gate array module. The gyroscope utilizes powerful broadband fiber source, polarizer and Lyot depolarizer which ensure good reciprocity of whole architecture. The parameters of the sensor, obtained by measurement, are even comparable to some sensors using PM fiber, which is much more expensive.
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Piani, Goffredo. "Sull'interferenza quantistica indotta dal potenziale gravitazionale." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19167/.
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Con l’avvento della meccanica quantistica è emerso un nuovo parametro che non ha alcun equivalente nella meccanica classica. La fase di un’onda di materia. Essa è direttamente influenzata dal potenziale cui l’onda è sottoposta, dunque anche dal potenziale gravitazionale.
Colella, Overhauser e Werner in uno storico esperimento del 1975 ne introdussero una modalità di verifica che prevede un’interferometria su di un fascio di neutroni. Infatti, i due rami dell’interferometro, se soggetti a un livello differente di potenziale, producono una figura di interferenza.
In questa tesi sono trattati i vari fattori che influenzano gli esperimenti COW. A fianco degli effetti gravitazionali, vi sono quelli causati dalla rotazione terrestre, quelli dovuti alla deformazione del cristallo interferometrico e quelli introdotti dalla teoria della dynamical diffraction.
Infine viene descritta, una tra le tante, l’applicazione di questa tipologia di esperimenti nella verifica del principio di equivalenza in ambito quantistico.
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Savoie, Denis. "Fonctionnements continu et entrelacé d'un gyromètre à atomes froids et amélioration de sa stabilité." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066585/document.
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Les gyromètres Sagnac atomiques ont un grand potentiel en raison de leur sensibilité élevée à la rotation. Le gyromètre atomique du SYRTE utilise des atomes de césium refroidis par lasers. À l'aide de transitions Raman stimulées, nous formons un interféromètre de type Mach-Zehnder replié. L'instrument permet d'atteindre un temps d'interrogation maximal de 800 ms, ce qui correspond à une aire Sagnac de 11 cm², la plus grande démontrée pour un interféromètre atomique. Les objectifs de ma thèse sont de tirer au mieux parti du potentiel de l'instrument, et d'étudier des modes d'interrogations jointif et jointif entrelacé. C'est une étape importante pour l'application de tels instruments entre autres en navigation inertielle. Je décris les méthodes mises en place pour pousser la sensibilité court terme et mené une première étude détaillée des effets systématiques. Nous avons démontré une stabilité à court terme de 30 nrad/s/Hz^1/2 en interrogation jointive triplement entrelacée, ce qui est une amélioration d'un facteur 3 de l'état de l'art pour les gyromètres à atomes froids. L'état de l'art a également été amélioré d'un facteur 4 à long terme avec une stabilité de 0,23 nrad/s en 30 000 sSagnac atomic gyroscopes have great potential due to their high sensitivity to rotation. The SYRTE atomic gyroscope uses laser cooled cesium atoms. Thank to stimulated Raman transitions, we form a folded Mach-Zehnder type interferometer. The instrument allows interrogation times up to 800~ms, which corresponds to a 11~cm$^2$ Sagnac area, the largest demonstrated for atom interferometers. This is a major step toward the use of such instruments in inertial navigation. I describe the methods implemented to push the short-term sensitivity and performed the first detailed study of systematics, such as those linked to light-shifts due to the preparation and the detection of the atoms and those linked to misalignment of parallelism of the mirrors and of the trajectories of the atoms. I demonstrated a short-term stability of 30~nrad.s$^{-1}$.Hz$^{-1/2}$ in triple interleaved joint interrogation which improves the state of the art by a factor 3. The state of the art has also been improved by a factor 5 in long-term with a 0,2~nrad.s$^{-1}$ stability in 30~000~s
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Cheng, Bi-Chang, and 鄭必章. "The Novel Sagnac Interferometer for Designing Hydrophones." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/75144243275733520673.
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碩士國立中山大學
電機工程學系研究所
92
The main purpose of the optical fiber sensing technology is to detect perturbation of physical fields. By means of some demodulating scheme, we can extract the real signal from those light beams which modified by physical fields. In the thesis, we proposed a configuration of modified Sagnac Interferometer as a sensing system. The optical sensing and demodulation system are exploited separately. Next, we study the advantages and disadvantages of the configuration. Besides, we are also measured the sensitivity and dynamic range. The sensing system used a low coherence light source to reduce cost. This system also improves the shortage of a Sagnac Interferometer which has a blind point in the middle position. In addition, the structure is easily implemented and can detect weak signal in a high noisy water environment. For matching the main structure, we make many kinds of sensing heads for detecting signals under water. We also use the mathematical model as the base of the theory. The dynamic range is 40 dB and the sensitivity is -231.47 dB re V/uPa.
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Ramana, Sree M. "New applications of geometric phase in optics using Sagnac interferometer." Thesis, 2003. http://hdl.handle.net/2009/1038.
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Chan, Hsin-Han, and 詹昕翰. "Study of Fiber Pulse Laser Using Sagnac Interferometer With PZT." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/7uv682.
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碩士國立清華大學
光電工程研究所
106
In this paper, we incorporate a Sagnac interferometer and a PZT in a fiber-optic linear-type laser cavity. We use the Sagnac interferometer and the PZT to generate periodic cavity loss and active mode-locking, and then generate pulses. We modify the length of the Sagnac interferometer to adjust the period of the optical pulse train, in generating optical pulses of several hundred nanoseconds in width. We then compare the influence of the square wave signal and the sine wave signal given by the signal generator on the light pulse. Finally, a discussion on the influence of the environment, which includes the sound, temperature and vibration, on pulse generation is given.
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LU, TING-CHIA, and 呂庭嘉. "WDM Optical Fiber Acoustic Sensor Array Based on Sagnac Interferometer." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/3bf54h.
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碩士國立高雄科技大學
電子工程系
107
In this thesis, the optical fiber Sagnac interferometer was used to design an optical fiber acoustic sensor and a sensor array system. The signal-channel and multi-channel acoustic sensors were investigated. In the signal-channel fiber Sagnac interferometer system, the influences of different light sources and length of delay fiber on the acoustic sensor were investigated. The wideband light source, which was filtered through an optical multiplexer, can be used in the fiber Sagnac acoustic sensor. The optimal length of delay fiber was about 4km to 6km. Using the 2×2 optical coupler, the fiber Sagnac acoustic sensor had a frequency response range from 1.2 kHz to 8.1 kHz, a sensitivity of -69.37 dBV/μbar, and a signal-to-noise ratio (SNR) of 50 dB. Using the 3×3 optical coupler, the fiber Sagnac acoustic sensor had a frequency response range from 1.1 kHz to 20.5 kHz, a sensitivity of -10.38 dBV/μbar, and an SNR of 60 dB. In the multi-channel fiber Sagnac interferometer, the optical multiplexers were inserted in the fiber loop and at the signal output ends to realize an eight-channel fiber acoustic sensor array system. There were four channels to implement the acoustic wave detection. For the four channels, the frequency response range all is from 1.2 kHz to 20 kHz; the sensitivity is from -137.46 to -154.28 dBV/μbar; and the SNR is from 25 to 33 dB. Using the same acoustic source, the interval between the sensor heads can be estimated.
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Chen, Han-Yang, and 陳漢揚. "The Promotion of the Performance Based on Dual Sagnac Interferometer Hydrophones." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/67131211720183324454.
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碩士國立中山大學
電機工程學系研究所
94
An interferometer is used for phase detection. Thus, the hydrophone which is based on interferometric optic fiber sensor has extremely high sensitivity. Sagnac interferometric hydrophone has low noise of marine environment, which is more suitably used to detect underwater acoustic signal than that of a Mach-Zehnder interferometer. In this paper, a configuration of dual Sagnac interferometer was proposed. The mathematical model was derived and analyzed. The fiber optic sensor head contains mandrel type and planar one. The acoustic window are made of silicon rubbers. It was should that we can increase their sensitivities by increase number of wrapping fiber coils. In our experiment, the result shows that among all the mandrel sensor heads, the most highest dynamic range is up to 37.6±1.4 dB, and its sensitivity is -223.3±1.7 dB re V/1µPa ; while the dynamic range of the planar sensor head is 42.1±1.5 dB, and its sensitivity is -213.8±1.3 dB re V/1µPa。 As for the configuration of the optical interferometers, the intensity of the dual Sagnac interferometer is 20 dB larger than its Sagnac counterpart. Its dynamic range is above 66 dB, which is 24 dB larger than that of the Sagnac interferometer with the sensitivity of -192.0 dB re V/1µPa. In addition, by using software simulation to design optimal lengths of delay fibers , we can increase interferometer’s the dynamic range of underwater acoustic detection. This paper verify that, by means of adjusting the length of these two delay fibers, we can actually increase the dynamic range of acoustic signal detection.
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Smith, Devin Hugh. "An Ultrafast Source of Polarization Entangled Photon Pairs based on a Sagnac Interferometer." Thesis, 2009. http://hdl.handle.net/10012/4259.
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This thesis describes the design, development, and implementation of a pulsed source of polarization-entangled photons using spontaneous parametric down-conversion in a Sagnac interferometer. A tangle of 0.9286 ± 0.0015, fidelity to the state (|10〉 + |01〉)/√2 of
0.9798 ± 0.0004 and a brightness of 597 pairs/s/mW were demonstrated.
Spontaneous parametric down-conversion is a nonlinear optical process in which one photon is split into two lower-frequency photons while conserving momentum and energy, in this
experiment nearly degenerate photons are produced. These photons are then interfered at the output beamsplitter of the interferometer, exchanging path entanglement for polarization entanglement and generating the desired polarization-entangled photon pairs.
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Jhuang, Tian-yi, and 莊田易. "The study of Fresnel lens in twisted-nematic liquid crystal fabricated by Sagnac interferometer." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/32qyse.
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碩士國立中山大學
物理學系研究所
105
This study presents a focusing efficiency and focal length tunable Fresnel lens with liquid crystals fabricated by a Sagnac interferometer. When the Fresnel-pattern green beam, formed by the Sagnac interferometer, is irradiated on the azo-dye doped liquid-crystal mixture, the azo-dye molecules will undergo the trans-cis photoisomerization and then generate photo-alignment effect in the bright (odd) zone, which results that the direction of liquid-crystal molecules will perpendicular to the linearly polarized pump beam. The various structures of liquid crystals in the odd and even zones will produce the phase difference, resulting in a Fresnel lens generated. The focusing efficiency of proposed Fresnel lens can be controlled by the external AC voltages. The experimental results show that the focusing efficiency can reach its maximum of 31.5 % under applied voltage of 3.1 V. In addition, the photo-alignment effect of azo dyes can be erased through the thermally method and rewritten by the pump beam with different Fresnel-like pattern, which leads to the Fresnel lens with various focal lengths.
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Mathew, Reuble. "Creating and Imaging Surface Acoustic Waves on GaAs." Thesis, 2009. http://hdl.handle.net/1974/5351.
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The versatility of surface acoustic wave (SAW) devices stems from the accessibility of the propagation path to modification and detection. This has led to the integration of SAWs in a variety of novel fields, including quantum information processing.
The development of technologically competitive devices requires the use of gigahertz frequency SAWs. This thesis develops fabrication processes for high frequency interdigital transducers on gallium arsenide. Optically lithography was used to create linear and stepped transducers, with a minimum feature size of 2 um, that were driven at their fifth harmonic. The highest frequency achieved was 1435 MHz, but the power absorbed was less than 3% and insertion losses were greater than -80 dB. Further improvements in the design and fabrication are required if optically fabricated transducers are to be an alternative to transducers with narrower finger widths. Electron-beam lithography techniques were developed and used to create transducers with finger widths of 500 and 400 nm, with fundamental resonance frequencies of 1387 and 1744 MHz, respectively. The power absorbed was 3 to 6% with insertion losses greater than -45 dB. The performance characteristics can be improved by the removal of residual resist on the surface of the transducer.
An indispensable tool for the characterization of one-port transducers is an all optical probe to measure the displacement field of a SAW. This work details the design and construction of a scanning Sagnac interferometer, that is capable of measuring the outward displacement of a surface. The spatial resolution of the interferometer was 2.4 +/- 0.2 um and the displacement sensitivity was determined to be 4 +/- 1 pm. The instrument was used to map the SAW displacement field from a 358 MHz transducer, with results showing the resonant cavity behaviour of the fingers due to Bragg reflections. It also allowed for the direct detection of the SAW amplitude as a function of the driving frequency of the transducer. The results showed good agreement with the related S21 scattering parameter. Lastly, the interferometer was used to image the attenuated propagation of SAWs through a phononic crystal. Results showed good agreement with theoretical simulations.Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-12-08 12:28:35.962
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Lin, Chia-Ju, and 林佳儒. "Study on Photo-annealing Effect of Super-fluorescent Fiber Source and Its Application in Sagnac Interferometer." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/d3y9v4.
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碩士國立臺灣科技大學
電子工程系
103
In this thesis, the characteristics of super-fluorescent fiber source (SFS), the recovery of photo-annealing effect and the application of fiber optic gyroscope (FOG) were discussed. The main scheme used here was a double-pass backward SFS (DPB-SFS) based on a broadband fiber Bragg grating (BFBG), which is temperature-compensated by carbon fiber reinforced plastic (CFRP). First, two types of Erbium-doped fiber (EDF), HG980 B1 and AG980H, in different lengths were used in the DPB-SFS. The properties of DPB-SFS using both types of EDFs were studied in their output power, mean-wavelength and 3 dB bandwidth. The best output power, mean-wavelength and 3 dB bandwidth were 10.65 dBm, 1549.3 nm and 16.92 nm, respectively, using 5 m EDF (HG980 B1). Then, we discussed the photo-annealing effect. The EDFs were exposed in 60Co gamma-radiation with a total dose of 200 krad. Because the molecular bonding of EDF would be damaged by the radiation, a 637 nm red light laser was used to recovery the radiation-induced loss. The properties of radiation-induced loss and recovery were characterized by measuring the absorption spectra of EDFs which were pumped by a 980 nm broadband light source. Results showed that both types of EDF could be photo-annealed by the 637 nm red light laser. The AG980H EDF suffered greater loss than the other, but the loss could be healed up to 12.71 dB after photo-annealed. After that, the thermal and real-time radiation stabilities of DPB-SFS were discussed. In this part, we discussed the thermal stability by using 5 m EDF (HG980B1) and the temperature ranging from 0 to 70 oC. The measured variation of output power, mean-wavelength and 3 dB bandwidth were 0.12 dB, 2 ppm/oC and 2.2 %, respectively. To verify real-time radiation stability, a 5 m HG980B1 EDF was set in the radiation chamber for 4.55-hour 60Co gamma-radiation exposure with a total dose of 200 krad. Again, a 637 nm red light laser was used to the DPB-SFS for in-time recovery of radiation-induced loss. The measured variation of output power, mean-wavelength and 3 dB bandwidth were 1.31 dB, 178.67 ppm and 0.7 %, respectively. Finally, for the investigation of Sagnac interferometer, the horizontal sensing based on Sagnac effect was introduced, and the DPB-SFS with 5 m HG980B1 EDF was used as sensing light source. Three interferometer schemes based on 2x2 fiber couplers in different lengths of EDF (3 m, 4 m and 5m) were investigated. The results showed that the variation of output power was periodic up and down in cosine function when the rotation angles varys from 0o to 90o both on clockwise and counter-clockwise direction. Taking 5 m interferometer for example; the slope on linear region is 0.05 mW power per rotation angle.
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黃渝瑄. "The study of multiwavelength fiber laser incorporating dual-pass in-line Sagnac interferometer and nonlinear polarization rotation effect." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/63468848428143981042.
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碩士高雄師範大學
光電與通訊工程學系
98
We present a multiwavelength fiber laser using nonlinear polarization rotation effect to suppress mode competition from the erbium doped fiber. The proposed new type of comb filter used in the multiwavelength fiber laser can produce more available and continuous operation wavelengths with better performances of FSR, SNR and linewidth. The fiber laser substitute dual pass in-line Sagnac interferometer for single pass in-line Sagnac interferometer . We use this new type of dual pass comb filters in our proposed fiber laser to successfully increase the SNR of lasing spectrum more than 30dB. The combination of the nonlinear polarization rotation effect devices and the dual pass comb filter can share an in-line fiber polarizer so as to simply the laser structure and reduce the cost. We properly adjust the phase of nonlinear polarization rotation effect, cavity length and pumping power respectively. The phase adjusting of the nonlinear polarization rotation effect can obtain three kinds of wavelength fiber laser spectra which bandwidth are 47 nm, 41 nm and 29 nm respectively. The optima cavity length is set at 2km to achieve the better laser performances. Various pumping powers injected into the multi-wavelength fiber laser can obtain different lasing spectra. The pumping power operating at 700mW can get the 6dB bandwidth of 47nm and SNR more than 20dB. When the pumping power operates at 200mW with fixed phase of nonlinear polarization rotation, an ultra broadband of lasing spectrum with 110 wavelength-lasing peaks periodically distributed from 1564nm to 1608nm accompanied with average lasing linewidth of 0.08nm, average FSR of 0.4nm and average SNR of 37dB. To the best of our knowledge, these results are the best performances than the previous references that ever announced in the field of multiwavelength fiber laser spectra more than 110 peaks.
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Shaddock, Daniel. "Advanced Interferometry for Gravitational Wave Detection." Phd thesis, 2000. http://hdl.handle.net/1885/48188.
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In this thesis we investigate advanced techniques for the readout and control of various interferometers. In particular, we present experimental investigations of interferometer configurations and control techniques to be used in second generation interferometric gravitational wave detectors. We also present a new technique, tilt locking, for the readout and control of optical interferometers. ¶ ...
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Huang, Guo-ting, and 黃國挺. "The Design and Demodulation of Fiber-optic Hydrophones Based on Dual Sagnac Interferometers." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/93231720852406794834.
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碩士國立中山大學
電機工程學系研究所
92
Because the acoustic wave is capable of propagating at a long-distance in water, the hydrophone plays a key role in the underwater acoustic sensing all the time. The hydrophone based on fiber optic interferometry has an extremely high sensitivity and large dynamic range. In addition, the electrically passive, immunity to electromagnetic interference, and multiplexing properties of fiber optic sensor offer great advantages over traditional piezoelectric hydrophone. Due to the complete path-balance between the two counterpropagating waves, a Sagnac interferometric configuration can employ a low-coherent light source to reduce the cost. This configuration can easily route optical paths and replace sensor heads to compare with each other. But, the sensitivity varying with frequency and the polarization-induced signal fading problem make it unsuitable for applications in need of detecting correct amplitude of signals. The Michelson interferometric configuration with Farady rotator mirror (FRM) has a constant sensitivity and solves the polarization-induced signal fading problem. But, this configuration uses a high-coherent light source and expensive FRMs, and be difficult to route. In this paper, we use the polarization-insensitive Michelson fiber optic sensor to adjust the demodulation circuits we design. In this paper, we establish the interferometric hydrophones. The fiber optic coil of the sensor head is embedded with the special materials in order to acoustic impedance matching and waterproofing. We employ phase generated carrier demodulation technology to get the acoustic signal of interest from the output of the interferometer. In our experiment, the dual Sagnac configuration has a dynamic range of 23 dB and a sensitivity of -226 dB re V/1uPa, the Michelson configuration with FRMs has a dynamic range of 25 dB and a sensitivity of -204 dB re V/1uPa.
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Azodi, Aval Golnaz. "Phononic Crystal Waveguiding in GaAs." Thesis, 2013. http://hdl.handle.net/1974/8492.
Full textAbstract:
Compared to the much more common photonic crystals that are used to manipulate light, phononic crystals (PnCs) with inclusions in a lattice can be used to manipulate sound. While trying to propagate in a periodically structured media, acoustic waves may experience geometries in which propagation forward is totally forbidden. Furthermore, defects in the periodicity can be used to confine acoustic waves to follow complicated routes on a wavelength scale. Using advanced fabrication methods, we aim to implement these structures to control surface acoustic wave (SAW) propagation on the piezoelectric surface and eventually interact SAWs with quantum structures.
To investigate the interaction of SAWs with periodic elastic structures, SAW interdigital transducers (IDTs) and PnC fabrication procedures were developed. GaAs is chosen as a piezoelectric substrate for SAWs propagation. Lift-off photolithography processes were used to fabricate IDTs with finger widths as low as 1.5 micron.
PnCs are periodic structures of shallow air holes created in GaAs substrate by means of a wet-etching process. The PnCs are square lattices with lattice constants of 8 and 4 micron. To predict the behavior of a SAW when interacting with the PnC structures, an FDTD simulator was used to calculate the band structures and SAW wave displacement on the crystal surface. The bandgap (BG) predicted for the 8 micron crystal ranges from 180 MHz to 220 MHz. Simulations show a shift in the BG position for 4 micron crystals ranging from 391 to 439 MHz.
Two main waveguide geometries were considered in this work: a simple line waveguide and a funneling entrance line waveguide. Simulations indicated an increase in acoustic power density for the funneling waveguides. Fabricated device evaluated with electrical measurements. In addition, a scanning Sagnac interferometer is used to map the energy density of the SAWs. The Sagnac interferometer is designed to measure the outward displacement of a surface due to the SAW. Interferometric measurements confirmed waveguiding in the modified funnel entrance waveguide embedded in the 4 micron PnC. However, they also revealed strong dissipation of the SAW in the waveguide due to the non-vertical sidewalls resulting from the wet-etch process.Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2013-11-29 15:53:46.369