Dissertations / Theses: 'Photonic crystal fibers'

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Azabi, Y. O. "Spiral photonic crystal fibers." Thesis, City, University of London, 2017. http://openaccess.city.ac.uk/19372/.

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This thesis is concerned with the study of special types of photonic crystal fibers (spiral) and their optical properties. The work is carried out using simulation techniques to obtain the modal field profile and properties for the designs. The method used in solving the Maxwell’s equations is the full vectorial finite element method with the implementation of penalty function and perfectly matched layer. The penalty function is used to eliminate nonphysical solutions. The perfectly matched layer is integrated to absorb rays of light traveling away from the core. These rays are absorbed by the layer and do not reflect back to negatively influence the results. The spiral shapes are implemented in the distribution of the holes in the cladding region of the photonic crystal fiber to determine the photonic crystal fiber properties. Three different spirals have been introduced which are equiangular, Archimedean and Fermat’s spiral. The study of the effective refractive index, effective area and dispersion with varying spiral parameters have been carried out and the results are analyzed to understand the effect of each parameter. The variation of similar parameters in the spirals leads to similar variation in the optical properties under consideration. Furthermore, the equiangular spiral photonic crystal fibers (ES-PCF) have been investigated in two different dimensional scales. The scales are in comparison with the wavelength of operation in the first case when core size is larger than the operating wavelength. In this case the total dispersion of the fiber has slightly higher values than the material dispersion but similar curve and slope. On the other hand, when the core size is comparable with the wavelength of operation, the dispersion is varying significantly with varying the spiral parameters. The effective area can be made very small and therefore the nonlinearity of the fiber very large to facilitate non-linear applications such as super continuum generation. The equiangular spiral photonic crystal fiber has been modified slightly where the position of holes in the third ring are shifted further from the center and their size is much bigger. This manipulation is proposed in an algorithm in this thesis to facilitate the fabrication of ES-PCF using an adaptive stack and draw technique. The design shows similar optical behavior to an ideal spiral and its dispersion has been tailored for supercontinuum generation.

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Pfeiffenberger, Neal Thomas. "Single Crystal Sapphire Photonic Crystal Fibers." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/77179.

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A single crystal sapphire optical fiber has been developed with an optical cladding that is used to reduce the number of modes that propagate in the fiber. This fiber is the first single crystal sapphire photonic crystal fiber ever produced. Fabrication of the optical cladding reduces the number of modes in the fiber by lowering the effective refractive index around the core, which limits the amount of loss. Different fiber designs were analyzed using Comsol Multiphysics to find the modal volumes of each. The MIT Photonic Bands modeling program was used to see if the first photonic band gap fiber could be achieved theoretically. The fibers were qualified using far field pattern and photodetector measurements as well as gas sensing experiments. The fibers were then exposed to a harsh environment of 1000 °C with a coating of alumina to test the resistance to scattering of the fiber. The fibers were also examined using materials characterization equipment to see how the harsh environments impacted the optical and mechanical stability of the bundled fiber.
Ph. D.

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Haakestad, Magnus W. "Optical fibers with periodic structures." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1494.

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This thesis concerns some experimental and theoretical issues in fiber optics. In particular, properties and devices based on photonic crystal fibers (PCFs) are investigated.

The work can be grouped into three parts. In the first part we use sound to control light in PCFs. The lowest order flexural acoustic mode of various PCFs is excited using an acoustic horn. The acoustic wave acts as a traveling long-period grating. This is utilized to couple light from the lowest order to the first higher order optical modes of the PCFs. Factors affecting the acoustooptic coupling bandwidth are also investigated. In particular, the effect of axial variations in acoustooptic phase-mismatch coefficient are studied.

In the second part of the thesis we use an electric field to control transmission properties of PCFs. Tunable photonic bandgap guidance is obtained by filling the holes of an initially index-guiding PCF with a nematic liquid crystal and applying an electric field. The electric field introduces a polarization-dependent change of transmission properties above a certain threshold field. By turning the applied field on/off, an electrically tunable optical switch is demonstrated.

The third part consists of two theoretical works. In the first work, we use relativistic causality, i.e. that signals cannot propagate faster than the vacuum velocity of light, to show that Kramers-Kronig relations exist for waveguides, even when material absorption is negligible in the frequency range of interest. It turns out that evanescent modes enter into the Kramers-Kronig relations as an effective loss term. The Kramers-Kronig relations are particularly simple in weakly guiding waveguides as the evanescent modes of these waveguides can be approximated by the evanescent modes of free space. In the second work we investigate dispersion properties of planar Bragg waveguides with advanced cladding structures. It is pointed out that Bragg waveguides with chirped claddings do not give dispersion characteristics significantly different from Bragg waveguides with periodic claddings.

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Ademgil, Huseyin. "Optical properties of novel photonic crystal fibers." Thesis, University of Kent, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.509653.

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Bethge, Jens. "Novel designs and applications of photonic crystal fibers." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2012. http://dx.doi.org/10.18452/16470.

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Zuerst wird die Idee einer gechirpten photonischen Kristallfaser vorgestellt. Aus einem stark vereinfachten Modell, die qualitativen Eigenschaften dieses neuen Fasertyps abgeleitet. Hier gelingt es, alle wichtigen Designparameter zu bestimmen. Die hervorragenden Leitungseigenschaften dieser Fasern werden dann in Experimenten demonstriert. Ohne jegliche Dispersionskompensation wird die Übertragung eines 25 fs Impulses in einer 1 Meter langen Faser gezeigt. Wird zusätzlich eine Dispersionskompensation verwendet, lassen sich sogar Impulse mit weniger als 20 fs Dauer übertragen. Im Anschluss daran wird eine photonische Kristallfaser untersucht, die mit einer Flüssigkeit gefüllt ist. Die hergestellte Faser ist dahingehend optimiert, einen hoch effizienten Soliton-Fission Mechanismus zu ermöglichen, der zur Erzeugung von Weißlicht genutzt wird. Diese Weißlicht-Impulse haben eine mit Soliton-Fission bisher noch nie erreichte Energie von 390 nJ. Auf Grundlage einer guten Übereinstimmung mit den experimentellen Resultaten lässt sich aus numerischen Simulationen der zugrunde liegende Effekt bestimmen. Abschließend wird über ein Experiment berichtet, das die nichtlineare Wechselwirkung zwischen zwei Impulsen verschiedener Wellenlänge ausnutzt, um einen optischen Schalter zu verwirklichen. Dieses Experiment erfordert genaueste Kontrolle der Dispersion und der Nichtlinearität in der Faser. Bei der gleichzeitigen Propagation von zwei Impulsen wird ein neuartiger Schalteffekt beobachtet. Beide Impulse haben nahezu die gleiche Gruppengeschwindigkeit, und ihre nichtlineare Wechselwirkung basierend auf Kreuz-Phasen-Modulation wird dadurch deutlich verstärkt. Hiermit wird ein voll funktionsfähiger optischer Transistor mit gutem Schaltkontrast experimentell demonstriert, der insbesondere einen schwachen Impuls einen stärkeren Impuls schalten lässt.
First, the concept of a novel chirped photonic crystal fiber is introduced. The qualitative dispersion and loss properties of this new fiber are theoretically derived. The calculated results agree excellently with experimental data obtained from fabricated fiber samples. The superior guiding properties of this new photonic fiber are demonstrated in two experiments. The delivery of 25 fs pulses over a 1 meter distance is realized without any dispersion compensation. Moreover, using dispersion compensation, the delivery of even sub-20-fs pulses becomes possible. Subsequently, a photonic crystal fiber with a liquid core is investigated, work presents effective methods for the preparation and explains a scheme for successfully reducing the insertion loss. The fiber is optimized to support the highly efficient soliton-fission mechanism at unprecedented pulse energies in white-light supercontinuum generation. Because of the liquid core, the supercontinuum generation scheme can be scaled beyond the peak-power limitations of solid-core fibers. The generation of a two-octave spanning supercontinuum with 390 nJ pulse energy is demonstrated. The experimental results are compared to a numerical simulation and the underlying mechanism is identified. Finally, an experiment is presented that exploits strong nonlinear interaction of two pulses inside a photonic crystal fiber for all-optical switching. A novel effect is observed during the co-propagation of two ultrashort pulses with different wavelengths. Because of the dispersion properties in the chosen fiber, these pulses are propagating at nearly identical group velocities, which dramatically increases the nonlinear interaction via cross-phase modulation between the two pulses. Based on this interaction, a fully functional optical transistor is experimentally demonstrated with good switching contrast. In particular, the demonstrated optical transistor enables switching of a strong pulse by a much weaker pulse.

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Albandakji, Mhd Rachad. "Modeling and Analysis of Photonic Crystal Waveguides." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/27474.

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In this work, we investigate several aspects of photonic crystal waveguides through modeling and simulation. We introduce a one-dimensional model for two-dimensional photonic crystal fibers (PCFs), analyze tapered PCFs, analyze planar photonic crystal waveguides and one-dimensional PCFs with infinite periodic cladding, and investigate transmission properties of a novel type of fiber, referred to as Fresnel fiber. A simple, fast, and efficient one-dimensional model is proposed. It is shown that the model is capable of predicting the normalized propagation constant, group-velocity dispersion, effective area, and leakage loss for PCFs of hexagonal lattice structure with a reasonable degree of accuracy when compared to published results that are based on numerical techniques. Using the proposed model, we investigate tapered PCFs by approximating the tapered section as a series of uniform sections along the axial direction. We show that the total field inside the tapered section of the PCF can be evaluated as a superposition of local normal modes that are coupled among each other. Several factors affecting the adiabaticity of tapered PCFs, such as taper length, taper shape, and number of air hole rings are investigated. Adiabaticity of tapered PCFs is also examined. A new type of fiber structure, referred to as Fresnel fiber, is introduced. This fiber can be designed to have attractive transmission properties. We present carefully designed Fresnel fiber structures that provide shifted or flattened dispersion characteristics, large negative dispersion, or large or small effective area, making them very attractive for applications in fiber-optic communication systems. To examine the true photonic crystal modes, for which the guidance mechanism is not based on total internal reflection, photonic crystal planar waveguides with infinite periodic cladding are studied. Attention will be focused on analytical solutions to the ideal one-dimensional planar photonic crystal waveguides that consist of infinite number of cladding layers based on an impedance approach. We show that these solutions allow one to distinguish clearly between light guidance due to total internal reflection and light guidance due to the photonic crystal effect. The analysis of one-dimensional PCFs with infinite periodic cladding is carried out in conjunction with an equivalent T-circuits method to model the rings that are close to the core of the fiber. Then, at sufficiently large distance from the core, the rest of the cladding rings are approximated by planar layers. This approach can successfully estimate the propagation constants and fields for true photonic crystal modes in both solid-core and hollow-core PCFs with a high accuracy. Original file (released May 10, 2007) replaced Oct. 3, 2012 GMc per DePauw]
Ph. D.

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Lombardini, Alberto. "Nonlinear optical endoscopy with micro-structured photonic crystal fibers." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4377.

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Dans cette thèse, nous proposons l'utilisation d'un nouveau type de fibre à cristal photonique, la fibre Kagomé à coeur creux, pour la livraison d'impulsions ultra-courtes en endoscopie non linéaire. Ces fibres permettent la livraison d'impulsions sans distorsion sur une large bande spectrale, avec un faible bruit de fond, grâce à la propagation dans le cœur creux. Nous avons résolu le problème de la résolution spatiale, à l'aide d'une microbille en silice, insérée dans le cœur de la fibre Kagomé. Nous avons développé un système d'imagerie compacte, qui utilise un tube piézo-électrique pour le balayage du faisceau, un système achromatiques de microlentilles et une fibre Kagomé double gaine, spécialement conçue pour l'endoscopie. Avec ce système, nous avons réussi à imager des tissus biologiques, à l'extrémité distale de la fibre (endoscopie), en utilisant des différentes techniques tels que TPEF, SHG et CARS, un résultat qui ne trouve pas d'égal dans la littérature actuelle. L'intégration dans une sonde portable (4,2 mm de diamètre) montre le potentiel de ce système pour de futures applications en endoscopie multimodale in-vivo
In this thesis, we propose the use of a novel type of photonic crystal fiber, the Kagomé lattice hollow core fiber, for the delivery of ultra-short pulses in nonlinear endoscopy. These fibers allow undistorted pulse delivery, over a broad transmission window, with minimum background signal generated in the fiber, thanks to the propagation in a hollow-core. We solved the problem of spatial resolution, by means of a silica micro-bead inserted in the Kagomé fiber large core. We have developed a miniature imaging system, based on a piezo-electric tube scanner, an achromatic micro-lenses assembly and a specifically designed Kagomé double-clad fiber. With this system we were able to image biological tissues, in endoscope modality, activating different contrasts such as TPEF, SHG and CARS, at the distal end of the fiber, a result which finds no equal in current literature. The integration in a portable probe (4.2 mm in diameter) shows the potential of this system for future in-vivo multimodal endoscopy

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Zhang, Rui. "Propagation of ultrashort light pulses in tapered fibers and photonic crystal fibers." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=981255191.

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Shen, Linping Huang Wei-Ping. "Modeling and design of photonic crystal waveguides and fibers /." *McMaster only, 2003.

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Хайдер, А. М., and Ю. П. Мачехин. "Photonic crystal fibers technology development opprtunities in communications systems." Thesis, ХНУРЭ, 2016. http://openarchive.nure.ua/handle/document/8908.

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Sangam, Ramyaa Ramesh. "Development of Polychromatic Laser Beacon Fiber Coupling System Based on Photonic Crystal Fibers." University of Dayton / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1386943018.

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Zheng, Juanjuan. "Design and fabrication of photonic crystal fibers for nonlinear microscopy /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?ECED%202008%20ZHENG.

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Amsanpally, Abhilash. "Linear properties of inhibited coupling hollow-core photonic crystal fibers." Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0028/document.

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Cette thèse a porté sur les principes de guidage, les propriétés linéaires et les outils de conception autour des fibres à cristal photonique à coeur creux (HC-PCF) à couplage inhibé (IC). Le guidage IC a été démontré comme une manifestation photonique de Q-BiC (état quasi lié dans un continuum) en étudiant des profils asymétriques et dépendants en polarisation dit Fano présentant une bande passante spectrale de 30 GHz. En utilisant le concept de IC, nous reportons la caractérisation linéaire de fibres IC HC-PCF supérieures à l’état de l’art. Par une optimisation de la forme du coeur, une fibre Kagome IC HC-PCF a démontré des pertes très faibles de 8,5 dB/km à 1030 nm associées à une bande passante à 3 dB de 225 nm. Une autre conception avec des entretoises de silice amincies à 300 nm a permis d’atteindre des pertes de 30 dB/km à 780 nm avec une bande de transmission fondamentale record décalée à 670 nm et capable de couvrir toutes les gammes spectrales du Ti:Sa, Yb et Er. Nous avons également travaillé sur la conception et la fabrication de IC HC-PCF présentant une gaine dont la structure est un réseau unique de tubes fins isolés. Une de ces fibres a permis de démontrer une transmission jusqu'à 220 nm avec des pertes records de 7,7 dB/km à ~ 750 nm, tandis qu’une seconde réalisation s’est traduit par une bande fondamentale de plus d’une octave allant de 600 à 1200 nm avec des pertes de 10-20 dB/km. Finalement, cette dernière fibre a été étudiée plus en détail pour déterminer les sources à l’origine des pertes due à la rugosité de surface présente à l’interface du contour du coeur
This thesis reported on guiding principles, linear properties and conceptual design tools of inhibited coupling (IC) guiding hollow-core photonic crystal fibers (HC-PCF). IC guidance was proved as photonic manifestation of Q-BiC (quasi bound-state-in-a-continuum) by investigating asymmetric and polarization dependent Fano profiles with bandwidth of 30 GHz in high resolution transmission spectra. By using IC design concept, we reported on linear characterization of state-of-the-art IC HC-PCFs. Based on core shaping optimization, a Kagome IC HC-PCF demonstrated ultra-low loss down to 8.5 km/km at 1030 nm associated with a 225 nm wide 3-dB bandwidth. Another Kagome design with thinner silica struts of 300 nm exhibited lowest loss of 30 dB/km at 780 nm along with record level fundamental bandwidth spreading down to 670 nm and able to cover the entire Ti:Sa, Yb and Er laser spectral ranges. We also reported on design and fabrication of single-ring tubular lattice IC HC-PCFs. One of these fibers demonstrated transmission down to 220 nm with a record transmission loss of 7.7 dB/km at ~750 nm, while the second one exhibited ultra-broad fundamental band with loss range of 10-20 dB/km over one octave spanning from 600 to 1200 nm. Finally, the second tubular fiber was further investigated for fundamental loss sources due to surface roughness around its core-contour

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Jiang, Rui. "Parametric band translation using highly-nonlinear and photonic crystal fibers." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3330316.

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Thesis (Ph. D.)--University of California, San Diego, 2008.
Title from first page of PDF file (viewed November 17, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 234-247).

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Xu, Shengbo. "Characterizing and controlling extreme optical nonlinearities in photonic crystal fibers." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0013817.

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Issa, Nader. "Modes and propagation in microstructured optical fibres." University of Sydney. Physics and Optical Fibre Technology Centre, 2005. http://hdl.handle.net/2123/613.

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Microstructured optical fibres (MOFs), also commonly called photonic crystal fibres or holey fibres, describe a type of optical fibre in which continuous channels of (typically) air run their entire length. These `holes' serve to both confine electromagnetic waves within the core of the fibre and to tailor its transmission properties. In order to understand and quantify both of these functions, a new computational algorithm was developed and implemented. It solves for the eigenvalues of Maxwell's wave equations in the two-dimensional waveguide cross-section, with radiating boundary conditions imposed outside the microstructure. This yields the leaky modes supported by the fibre. The boundary conditions are achieved exactly using a novel refinement scheme called the Adjustable Boundary Condition (ABC) method. Two implementations are programmed and their computational efficiencies are compared. Both use an azimuthal Fourier decomposition, but radially, a finite difference scheme is shown to be more efficient than a basis function expansion. The properties of the ABC method are then predicted theoretically using an original approach. It shows that the method is highly efficient, robust, automated and generally applicable to any implementation or to other radiating problems. A theoretical framework for the properties of modes in MOFs is also presented. It includes the use of the Bloch-Floquet theorem to provide a simpler and more efficient way to exploit microstructure symmetry. A new, but brief study of the modal birefringence properties in straight and spun fibres is also included. The theoretical and numerical tools are then applied to the study of polymer MOFs. Three types of fibres are numerically studied, fabricated and characterised. Each is of contemporary interest. Firstly, fabrication of the first MOFs with uniformly oriented elliptical holes is presented. A high degree of hole ellipticity is achieved using a simple technique relying on hole deformation during fibre draw. Both form and stress-optic birefringence are characterized over a broad scaled-wavelength range, which shows excellent agreement with numerical modelling. Secondly, an analysis of leaky modes in real air core MOFs, fabricated specifically for photonic band gap guidance, is then used to identify alternative guiding mechanisms. The supported leaky modes exhibit properties closely matching a simple hollow waveguide, weakly influenced by the surrounding microstructure. The analysis gives a quantitative determination of the wavelength dependent confinement loss of these modes and illustrates a mechanism not photonic band gap in origin by which colouration can be observed in such fibres. Finally, highly multimode MOFs (also called `air-clad' fibres) that have much wider light acceptance angles than conventional fibres are studied. An original and accurate method is presented for determining the numerical aperture of such fibres using leaky modes. The dependence on length, wavelength and various microstructure dimensions are evaluated for the first time for a class of fibres. These results show excellent agreement with published measurements on similar fibres and verify that bridge thicknesses much smaller than the wavelength are required for exceptionally high numerical apertures. The influence of multiple layers of holes on the numerical aperture and capture efficiency are then presented. It shows that a substantial increase in both these parameters can be achieved for some bridge thicknesses. Simple heuristic expressions for these quantities are given, which are based on the physical insight provided by the full numerical models. The work is then supported by the first fabrication attempts of large-core polymer MOFs with thin supporting bridges. These fibres exhibit relatively high numerical apertures and show good agreement with theoretical expectations over a very wide scaled-wavelength range.

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Kim, Jeong I. "Analysis and Applications of Microstructure and Holey Optical Fibers." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/29089.

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Microstructure and photonic crystal fibers with periodic as well as random refractive-index distributions are investigated. Two cases corresponding to fibers with one-dimensional (1D) radial index distributions and two-dimensional (2D) transverse index distributions are considered. For 1D geometries with an arbitrary number of cladding layers, exact analytical solutions of guided modes are obtained using a matrix approach. In this part, for random index distributions, the average transmission properties are calculated and the influence of glass/air ratio on these properties is assessed. Important transmission properties of the fundamental mode, including normalized propagation constant, chromatic dispersion, field distributions, and effective area, are evaluated. For 2D geometries, the numerical techniques, FDTD (Finite-Difference Time-Domain) method and FDM (Finite Difference Method), are utilized. First, structures with periodic index distributions are examined. The investigation is then extended to microstructure optical fibers with random index distributions. Design of 2D microstructure fibers with random air-hole distributions is undertaken with the aim of achieving single-mode guiding property and small effective area. The former is a unique feature of the holey fiber with periodic air-hole arrangement and the latter is a suitable property for nonlinear fiber devices. Measurements of holey fibers with random air-hole distributions constitute an important experimental task of this research. Using a section of a holey fiber fabricated in the draw tower facility at Virginia Tech, measurements of transmission spectra and fiber attenuation are performed. Also, test results for far-field pattern measurements are presented. Another objective of this dissertation is to explore new applications for holey fibers with random or periodic hole distributions. In the course of measuring the holey fibers, it was noticed that robust temperature-insensitive pressure sensors can be made with these fibers. This offers an opportunity for new low-cost and reliable pressure fiber-optic sensors. Incorporating gratings into holey fibers in conjunction with the possibility of dynamic tuning offers desirable characteristics with potential applications in communications and sensing. Injecting gases or liquids in holey fibers with gratings changes their transmission characteristics. These changes may be exploited in designing tunable optical filters for communication applications or making gas/liquid sensor devices.
Ph. D.

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Wu, Darran Kin Chun. "Photonic crystal fibre directional coupler : ultrasensitive refractive index sensing." Thesis, The University of Sydney, 2010. https://hdl.handle.net/2123/28912.

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We present a new photonic crystal fibre sensor for label—free refractive index sensing. The refractive index sensor is based on a directional coupler within a photonic crystal fibre. The analyte forms a waveguide in the fibre and it possesses strong modal overlap with the core waveguide, yielding strong light-sample interaction and extreme sensitivities (104 nm per refractive index units). The performance of the sensor is strongly dependent on the fraction of the mode that overlaps with the analyte, the coupling length, and the coupling wavelength. The device is operational for a broad range of refractive indices (An=0.02) above silica, but requires the analyte to be carefully filled over a timescale of several minutes via capillary forces. We present a calibrated temperature compensated dip sensor to minimise the effect of ambient temperature fluctuations, and imperfect holes in the photonic crystal fibre. We propose a fibre structure with an enhanced detection limit of 6.66x10'8 RIU, and demonstrate experimentally a measured detection limit of 1.77x10'7 RIU with commercial fibre.

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Zhang, Yuji. "Coherence properties of supercontinuum generated in highly nonlinear photonic crystal fibers." Thesis, Tufts University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3684584.

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In this dissertation, experimentally measured spectral and coherence evolution of supercontinuum (SC) is presented. Highly nonlinear soft-glass photonic crystal fibers (PCF) were used for SC generation, including lead-silicate (Schott SF6) PCFs of a few different lengths: 10.5 cm, 4.7 mm, and 3.9 mm, and a tellurite PCF of 2.7 cm. The pump is an optical parametric oscillator (OPO) at 1550 nm with pulse energy in the order of nanojoule (nJ) and pulse duration of 105 femtosecond (fs). The coherence of SC was measured using the delayed-pulse method, where the interferometric signal was sent into an optical spectrum analyzer (OSA) and spectral fringes were recorded. By tuning the pump power, power-dependent evolution of spectrum and coherence was obtained. Numerical simulations based on the generalized nonlinear Schrodinger equation (GNLSE) were performed. To match the measured data, the simulated spectral evolution was optimized by iteratively tuning parameters and comparing features. To further match the simulated coherence evolution with the measurement, shot noise and pulse-to-pulse power fluctuation were added in the pump, and the standard deviation of the fluctuation was tuned. Good agreement was obtained between the simulated and the measured spectral evolution, in spite of the unavailability of some physical parameters for simulation. It is demonstrated in principle that, given a measured spectral evolution, the fiber length, and the average power of SC, all other parameters can be determined unambiguously, and the spectral evolution can be reproduced in the simulations. Most importantly, the soliton fission length can be simulated accurately. The spectral evolution using the 4.7- and the 3.9-mm SF6 PCFs shows a pattern dominated by self phase modulation (SPM). This indicates that, these fiber lengths are close to the soliton fission length at the maximum power. The spectral evolution using the 10.5-cm SF6 PCF and the 2.7-cm tellurite PCF shows a soliton-fission-dominated pattern, indicating these lengths are much longer than the soliton fission length at the maximum power. For the coherence evolution using the SF6 PCFs, the simulations and the measurements show qualitative agreement, confirming the association between coherence degradation and soliton fission. For the case of the tellurite PCF, nearly quantitative agreement is shown, and it is shown that the solitonic coherence degrades slower than the overall coherence. Fluctuation of coherence occurs at the regime where the coherence starts to degrade, in the measurement and the simulations of the SF6-PCF case. It is shown that the cause is the pulse-to-pulse power fluctuation in the pump. The pulse-to-pulse stability of spectral intensity is another characterization of SC stability, other than the coherence. It is shown by simulations that these two exhibit different dynamics, and have low correlation.

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Santos, Eliane Moura dos. "Processos relacionados a inserção de fluidos para sensoriamento com fibras de cristal fotônico." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278251.

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Orientadores: Luiz Carlos Barbosa, Cristiano Monteiro de Barros Cordeiro
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: Este trabalho apresenta estudos de como inserir fluidos (líquidos e gases) em fibras ópticas microestruturadas, especialmente fibras de cristal fotônico, também conhecidas como PCF¿s (do inglês Photonic Crystal Fibers). Estas fibras possuem buracos de ar que percorrem todo seu comprimento. Elas podem ser divididas em dois grandes grupos: as de núcleo sólido que guiam luz por reflexão interna total e as de núcleo oco que guiam luz por um mecanismo conhecido como photonic bandgap. Ambos os tipos de fibras permitem várias aplicações em áreas como óptica e fotônica e nos dedicamos aqui à área de sensoriamento a fibra. Nesta área, usamos os microburacos para inserir fluido e dessa maneira manipular as propriedades de guiamento (em fibras de núcleo líquido), deixar a fibra mais sensível a algum parâmetro externo ou para sensoriar o fluido em questão. Nos três casos, precisamos estudar os processos de preenchimentos de fibras microestruturadas. Para este fim, estudamos e desenvolvemos maneiras de inserir fluidos em fibras de núcleos sólidos ou ocos. Usando preenchimento seletivo, produzimos fibras com núcleo líquido, criando uma região de alta interação entre luz e material. Neste trabalho, estudamos diferentes técnicas de preenchimento. A primeira, para fibras de núcleo líquido, é um preenchimento seletivo que pode ser feito usando uma máquina de emendas (splicer) ou um polímero para bloquear os microburacos. O outro consiste em manter as pontas das fibras livres (para medidas ópticas) enquanto o preenchimento é feito. Por fim, usamos o conhecimento desses processos em aplicações como sensoriamento de fluidos ou parâmetros externos e manipulação de propriedades de guiamento da luz
Abstract: This work presents studies of how to insert fluids (liquid and gas) into microstructured optical fibers, especially photonic crystal fibers, also known as PCF¿s. These optical fibers possess air holes that run along its entire length. They can be divided into two major groups: solid core fibers that guide light by total internal reflection and hollow core fibers that guide light by photonic bandgap. Both types of fibers allow several applications in areas such as optics and photonics and we dedicated this work to the fiber-sensing field. In this area we use the micro holes to insert fluids and in this way to manipulate the guidance properties in liquid core fibers, to leave the fiber more sensitive to some external parameter or to sensing the fluid. In these three cases we need to study the filling procedures in microstructured fibers. For this purpose, we studied and developed ways of inserting fluids in hollow and solid core fibers. We produced liquid core fibers, creating a high light-material overlap, using a selective filling technique. In this work we studied different filling techniques. The first one, for liquid core fibers, is a selective filling, which can be done by using a splicer machine or a polymer to block the fiber micro holes. The last one consists of keeping the fiber tips free (for optical measurements) while the filling is done. And finally we used the filling process knowledge in applications like sensing of fluids or external parameters and manipulation of guidance properties
Mestrado
Física Geral
Mestre em Física

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Husakou, Anton. "Nonlinear phenomena of ultrabroadband radiation in photonic crystal fibers and hollow waveguides." [S.l. : s.n.], 2002. http://www.diss.fu-berlin.de/2002/246/index.html.

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Nahar, Niru Kamrun. "Photonic Crystal Fibers and Optical True Time Delay Engines for Wideband Arrays." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1213624105.

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Beravat, Ramin [Verfasser], Klaus [Akademischer Betreuer] Mecke, Bernhard [Akademischer Betreuer] Schmauß, and Philip [Gutachter] Russell. "Twisted Photonic Crystal Fibers / Ramin Beravat ; Gutachter: Philip Russell ; Klaus Mecke, Bernhard Schmauß." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2018. http://d-nb.info/118142819X/34.

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McElhenny, John E. "Acoustic waves in small-core photonic crystal fibers : An investigation through Brillouin scattering." Diss., [Free access to full dissertation available to Lehigh users only.], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3360490.

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Chesini, Giancarlo. "Dispositivos óticos baseados em fibras de cristal fotônico com eletrodos integrados." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277529.

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Orientador: Cristiano Monteiro de Barros Cordeiro
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica "Gleb Wataghin"
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Resumo: Neste trabalho de mestrado apresentamos o estudo e desenvolvimento de dispositivos óticos totalmente à fibra. Para isso, exploramos as novas possibilidades trazidas pelo advento das fibras de cristal fotônico (PCF's, do inglês Photonic Crystal Fibers). As PCF's são uma classe especial de fibras óticas que apresentam uma estrutura regular de buracos de ar na sua seção transversal, semelhante a um cristal fotônico. As fibras de cristal fotônico, além de apresentarem as vantagens inerentes às fibras óticas tradicionais, possuem novos graus de liberdade intrínsecos. Entre eles, o mais importante é a possibilidade de alterar fortemente as características da fibra através, apenas, do arranjo de buracos. Aqui, desenvolvemos uma fibra de cristal fotônico com dois buracos externos à microestrutura para integração de eletrodos. Posteriormente, um desses eletrodos foi exposto, polindo-se a lateral da fibra, e contato elétrico foi realizado. O elemento de controle do dispositivo ótico é a corrente elétrica que, aplicada ao eletrodo, o esquenta e o faz expandir via efeito Joule. O aumento de temperatura e a compressão causada pela expansão do eletrodo alteram o índice de refração e, portanto, a birrefringência da fibra. Foram realizadas, ainda, simulações utilizando o software comercial Comsol Multiphysics com o objetivo de entender a influência da temperatura e da compressão mecânica no modo ótico guiado pela fibra, bem como encontrar maneiras de otimizar o dispositivo em questã
Abstract: In this work we present a study and the development of all-fiber optical devices. For this purpose we exploited the new possibilities brought by the development of Photonic Crystal Fibers. PCF's are special kind of optical fibers with a regular pattern of air holes in their transverse section, resembling a photonic crystal. Photonic Crystal Fibers not only have the inherent advantages of traditional optical fibers but they have new intrinsic degrees of freedom. Among them, we can quote the possibility of strongly altering the fiber characteristics through the design of the air holes pattern. Here, we developed a photonic crystal fiber with two extra holes for electrode integration. One of these electrodes was exposed by side polishing the fiber and electrical contact to an external circuit was made. The contrai element of the optical device is the electrical current which, when applied to the electrode, heats it up and make it expand by Joule effect. The temperature increase and the compression caused by the electrode expansion alter the refractive index and, consequently, the fiber birefringence. We algo numerically studied the problem through Com sol software. The objective here was to understand the influence of temperature and stress on the light guided mode. In conclusion, we demonstrated in this work the creation of an all-fiber device based on the integration of electrodes to photonic crystal fibers where the element of contrai is the electrical current applied to the electrodes. We algo studied how to improve the parameters concerning the device operation
Mestrado
Física Geral
Mestre em Física

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Santos, Alexandre Bozolan dos. "Geração de supercontínuo em fibra óptica de cristal fotônico com núcleo de água." Universidade Presbiteriana Mackenzie, 2008. http://tede.mackenzie.br/jspui/handle/tede/1484.

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Photonic crystal fibers (PCFs) are optical fibers whose core is surrounded by a regular matrix of holes that is responsible for light confinement and guidance. This new architecture opens new perspectives in the development of nonlinear applications, many of which are based upon the high efficiency with which nonlinearity-driven spectral broadening known supercontinuum generation is obtained in solid-core PCFs. Another asset of PCFs is that their structure can be filled with liquids or gases, which then efficiently interact with the guided light. The possibility of obtaining supercontinuum generation in a PCF whose core is filled with highly nonlinear liquids has been recently theoretically studied. The insertion of liquids in PCFs introduces a new degree of freedom with which the efficiency of nonlinear effects can be maximized. This dissertation describes experimental work, in which the generation of a supercontinuum spectrum is demonstrated in a PCF whose hollow core was selectively filled with distilled water. A maximum broadening of 503nm, measured at -20dB, was obtained with femtosecond pulse pumping at λ=976nm. The comparison with spectra obtained with a 800nm pump and with bulk samples demonstrate that both a low dispersion at the pump wavelength and pump guidance are crucial for the broad output spectrum obtained. Numerical simulations and analyses were also undertaken to complement the study.
Fibras de cristal fotônico (PCF s) são fibras ópticas cujo núcleo é cercado por uma matriz regular de buracos, responsável pelo confinamento e guiamento da luz. Esta nova arquitetura abre novas perspectivas no desenvolvimento de aplicações não-lineares, muitas das quais são baseadas na alta eficiência com que o alargamento espectral não-linear conhecido como geração de supercontínuo é obtido em PCF s de núcleo sólido. Outra característica das fibras de cristal fotônico é que sua estrutura pode ser preenchida com líquidos e gases, que então interagem eficientemente com a luz guiada. A possibilidade de se obter a geração de supercontínuo em uma fibra de cristal fotônico cujo núcleo é preenchido com líquidos altamente não-lineares foi teoricamente estudado recentemente. A inserção de líquidos nas PCF s introduz um novo grau de liberdade, aumentando a eficiência com que os efeitos não-lineares podem ser gerados. Esta dissertação descreve um trabalho experimental no qual é demonstrada a geração de supercontínuo em uma PCF cujo núcleo foi preenchido seletivamente com água destilada. Obteve-se um alargamento máximo de 503nm medido, a -20dB, com o bombeio de pulsos de femtossegundos em 976nm. A comparação com o espectro obtido com o bombeio em 800nm e em amostras volumétricas demonstram que tanto a baixa dispersão no comprimento de onda de bombeio quanto o guiamento dos pulsos são cruciais para a obtenção do largo espectro observado. Simulações e análises numéricas foram também realizadas para complementar o estudo.

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Xi, Xiaoming [Verfasser], Philip [Akademischer Betreuer] Russell, and Markus [Akademischer Betreuer] Schmidt. "Helically twisted solid-core photonic crystal fibers / Xiaoming Xi. Gutachter: Philip Russell ; Markus Schmidt." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2015. http://d-nb.info/1076912060/34.

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Vieweg, Marius [Verfasser], and Harald [Akademischer Betreuer] Giessen. "Nonlinear optics in selectively fluid-filled photonic crystal fibers / Marius Vieweg. Betreuer: Harald Giessen." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2012. http://d-nb.info/1025256271/34.

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Harner, Mary. "Characterization of the mid-infrared wavelength dependent loss in hollow core photonic crystal fibers." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/18928.

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Master of Science
Department of Physics
Brian Washburn
This research sought to characterize the length dependent loss of hollow core photonic crystal fibers (HC-PCF) in the mid-infrared. These fibers are used in gas-filled fiber lasers that operate in the mid-infrared range. A black body source which provided a broad mid-infrared spectrum was coupled into a HC-PCF and a fiber cut-back method was implemented to make the length dependent loss measurement. A monochromator was used to observe narrow bands of the broad spectrum provided by the black body source and the loss as a function of wavelength was constructed. The loss for four unique HC-PCF fibers was characterized across the wavelength range [lambda] =1754 nm to [lambda] =3220 nm. The best fibers demonstrated a loss of less than 2 dB/m across this range, with some fibers even exhibiting loss below 1 dB/m.

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Apriyanto, Haris. "Study, analysis and experimental validation of fiber refractometers based on single-mode, multimode and photonic crystal fibers for refractive index measurements with application for the detection of methane." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0022.

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La mesure de l'indice de réfraction a été étudiée depuis qu'Ernest Abbé aie initialement conçu un réfractomètre en 1869, appelé le réfractomètre d'Abbé. Depuis lors, de nombreux réfractomètres ont été développés tels que le réfractomètre à prisme optique ainsi que le réfractomètre à fibre optique, en raison de leurs applications étendues pour la détection de divers paramètres physiques, biologiques et chimiques. Récemment, un grand nombre de chercheurs ont mis au point des réfractomètres basés sur des fibres optiques, exploitant des mécanismes tels que la résonance des plasmons de surface (SPR), les interférences multimodes, les fibres à réseaux de Bragg (FBG), les fibres à réseaux à longues périodes (LPG), les fibres optiques coniques et la fibre multimode à gaine dénudée. Les capteurs fibrés sont avantageux grâce à leur immunité contre les interférences électromagnétiques, passivité électrique au niveau de la sonde de détection et potentiel de mesure in situ à long terme. Cette thèse concerne le développement de modèles complets fonctionnels et précis pour les réfractomètres à fibres optiques basés sur la modulation d'intensité optique, en particulier la réfractométrie à fibre multimode à gaine dénudée ainsi que les systèmes hybrides associant fibres monomode et multimode, et un réfractomètre hybride tout fibré utilisant des fibres à cristaux photoniques. L'objectif clé de ce travail est de caractériser les performances de ces réfractomètres à fibres optiques basés sur la modulation d'intensité en termes de réponse en puissance, de sensibilité, de résolution et de dynamique de mesure. Les résultats de simulation qui sont corroborés expérimentalement démontrent que la très grande sensibilité obtenue dans la zone II (c'est-à-dire le régime de détection typiquement utilisé pour mesurer l'indice du milieu supérieur à l'indice de gaine mais inférieur ou égal à l'indice du coeur) pour tous les trois réfractomètres. Cependant, la sensibilité dans la Zone (c’est-à-dire le régime de détection pour lequel l’indice du milieu à mesurer est supérieur à celui du coeur) est très faible. Ainsi, un refractomètre fibré hybride monomode-multimode est utilisé pour améliorer la sensibilité dans la Zone III. D'autre part, la sensibilité pour la zone I (c'est-à-dire le régime de détection pour mesurer l’indice du milieu inférieur à l'indice de la gaine) a été améliorée en augmentant l'absorption des ondes évanescentes à l'aide du réfractomètre hybride tout fibré à base de fibres à cristaux photoniques à coeur solide. En termes d'application réelle du réfractomètre à fibre pour la détection biochimique, une preuve de concept pour un capteur du gaz méthane a été démontrée en utilisant les supramolécules de cryptophane-A qui permettent de piéger les molécules du méthane. Le cryptophane-A incorporé dans un film hôte à base de styrène acrylonitrile (SAN) est appliqué sur la zone dénudée du capteur comme une région fonctionnalisée. L'indice de réfraction de cette couche sensible augmente proportionnellement avec l'augmentation de la concentration du méthane, ce qui induit une variation de la puissance optique transmise dans le capteur fibré
Refractive index measurement has been studied since Ernest Abbé initially designed a refractometer in 1869, which is named the Abbé refractometer. Since then, numerous types of refractometers have been developed by employing either the optical prism-based refractometer or the optical fiber-based refractometer, due to their wide-ranging applications such as for sensingvarious physical, biological and chemical parameters. Recently, a large number of researchers have been developing refractometers based on optical fibers, exploiting mechanisms such as surface plasmon resonance (SPR), multimode interference, fiber Bragg gratings (FBG), long period gratings (LPG), tapered optical fibers, and striped-cladding multimode fibers (MMF), for their advantages in immunity against electromagnetic interference, electrical passivity at the sensing probe, and capability to long term in-situ measurement. This thesis concerns the development of comprehensively functional and accurate models for optical fiber refractometers based on optical intensity modulation, in particular for stripped-cladding MMF refractometry as well as hybrid systems involving a combination of single-mode-multimode fiber refractometery and the all-fiber hybrid refractometer using photonic crystal fibers. A key objective of this work is to characterize the performance of these intensity-based optical fiber refractometers in terms of their power response, sensitivity, resolution, and dynamic range. The simulation results which are corroborated experimentally demonstrate very high sensitivity being obtained in Zone II (i.e. the sensing regime typically employed for measuring a sensing medium index higher than the cladding index but less than or equal to the core index) for all three types of refractometers. However, the sensitivity in Zone III (i.e. the sensing regime for which the sensing medium index is higher than the core index) is very low. A hybrid single-mode fiber - multimode fiber configuration is used to improve the sensitivity in Zone III. On other hand, the sensitivity for Zone I (i.e. the sensing regime typically employed for measuring a sensing medium index lower than the cladding index) has been improved by increasing evanescent wave absorption using the all-fiber hybrid refractometer based on solid-core photonic crystal fibers. As a further potential of the fiber refractometer for applications in biochemical sensing, the proof-of-concept for a methane gas sensor has been demonstrated using supramolecular cryptophane-A which enables to trap the methane molecules. Cryptophane-A incorporated into a functionalized film of StyreneAcrylonitrile (SAN) host is applied to a de-cladded region of the sensor as the sensitive region. The refractive index of this functionalized layer increases proportionally with increasing methane concentration, subsequently inducing variations in the transmitted optical power along the fiber sensor

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Upendar, Swaathi [Verfasser], and Thomas [Akademischer Betreuer] Weiss. "Perturbation and manipulation of leaky modes in photonic crystal fibers / Swaathi Upendar ; Betreuer: Thomas Weiss." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2020. http://d-nb.info/1222976331/34.

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Pricking, Sebastian [Verfasser], and Harald [Akademischer Betreuer] Giessen. "Soliton dynamics and supercontinuum generation in complex-shaped tapered fibers and liquid-filled photonic crystal fibers / Sebastian Pricking. Betreuer: Harald Giessen." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2011. http://d-nb.info/1014785588/34.

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Heidt, Alexander Matthias. "Novel coherent supercontinuum light sources based on all-normal dispersion fibers." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17780.

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Thesis (PhD)--Stellenbosch University, 2011.
ENGLISH ABSTRACT: The concept of broadband coherent supercontinuum (SC) generation in all-normal dispersion (ANDi) fibers in the near-infrared, visible and ultraviolet (UV) spectral regions is introduced and investigated in detail. In numerical studies, explicit design criteria are established for ANDi photonic crystal fiber (PCF) designs that allow the generation of flat and smooth ultrabroad spectral profiles without significant fine structure and with excellent stability and coherence properties. The key benefit of SC generation in ANDi fibers is the conservation of a single ultrashort pulse in the time domain with smooth and recompressible phase distribution. In the numerical investigation of the SC generation dynamics self-phase modulation and optical wave breaking are identified as the dominant nonlinear effects responsible for the nonlinear spectral broadening. It is further demonstrated that coherence properties, spectral bandwidth and temporal compressibility are independent of input pulse duration for constant peak power. The numerical predictions are in excellent agreement with experimental results obtained in two realizations of ANDi PCF optimized for the near-infrared and visible spectral region. In these experiments, the broadest SC spectrum generated in the normal dispersion regime of an optical fiber to date is achieved. The exceptional temporal properties of the generated SC pulses are verified experimentally and their applicability for the time-resolved study of molecular dynamics in ultrafast transient absorption spectroscopy is demonstrated. In an additional nonlinear pulse compression experiment, the SC pulses obtained in a short piece of ANDi PCF could be temporally recompressed to sub-two cycle durations by linear chirp compensation. Numerical simulations show that even shorter pulse durations with excellent quality can be achieved by full phase compensation. The concept is further extended into the UV spectral regime by considering tapered optical fibers with submicron waist diameter. It is shown that coherent SC spectra with considerable spectral power densities in the usually hard to reach wavelength region below 300 nm can be generated using these freestanding photonic nanowires. Although technological difficulties currently prevent the fabrication of adequate nanofibers, the concept could be experimentally verified by coherent visible octave-spanning SC generation in tapered suspended core fibers with ANDi profile. The work contained in this thesis therefore makes important contributions to the availability and applicability of fiber-based broadband coherent SC sources with numerous high-impact applications in fundamental science and modern technology.
AFRIKAANSE OPSOMMING: Die konsep van breëband koherente superkontinuum (SK) in alles-normaal dispersiewe (ANDi) vesels in die naby-infrarooi, sigbare en ultraviolet (UV) spektrale gebiede word voorgestel en in detail ondersoek. In numeriese studies word eksplisiete ontwerpskriteria vasgestel vir ANDi fotoniese kristal vesel (FKV) ontwerpe wat dit moontlik maak om plat en gladde ultra-breë spektrale profiele te genereer sonder noemenswaardige fynstruktuur en met uitstekende stabiliteit en koherensie eienskappe. Die sleutel voordeel van SK genering in ANDi vesels is die behoud van ’n enkele ultrakort puls in tyd met ’n gladde en saamdrukbare fase distribusie. In die numeriese ondersoek van die SK generering is die dinamika van fase selfmodulering geïdentifiseer as die dominante nie-lineêre effek wat verantwoordelik is vir die nie-lineêre spektrale verbreding. Daar word voorts aangetoon dat die koherensie eienskappe, spektrale bandwydte en saamdrukbaarheid in tyd onafhanklik is van die inset pulsduur vir konstante drywing. Die numeriese voorspellings stem uitstekend ooreen met die eksperimentele resultate wat verkry is met twee ANDi FKVÕs wat optimeer is vir die naby-infrarooi en sigbare spektrale gebied. In hierdie eksperimente is die breedste SK spektrum gegenereer wat tot hede in die normaal dispersiewe regime met ’n optiese vesel behaal is. Die besondere eienskappe van die genereerde SK pulse is eksperimenteel bevestig en die toepasbaarheid vir tyd opgelosde studie van molekulêre dinamika is gedemonstreer. In ’n addisionele nie-lineêre puls kompressie eksperiment is SK pulse verkry in ’n kort stuk ANDi FKV wat in tyd saamgedruk kon word tot sub-twee siklus tydsduur deur liniêre tjirp kompensering. Numeriese simulasies toon aan dat selfs korter pulse met uitstekende kwaliteit behaalbaar is met volledige fase kompensasie. Die konsep is verder uitgebrei na die UV spektrale gebied deur ’n koniese vesel te beskou met sub-mikron diameter. Daar is aangetoon dat koherente SK spektra met noemenswaardige spektrale drywing in die golflengte gebied onder 300 nm, wat gewoonlik as moeilik toeganklik beskou word, bereik kan word deur hierdie vrystaande fotoniese nano-vesels aan te wend. Alhoewel tegnologiese probleme die vervaardiging van voldoende nano-vesels verhinder, kon die konsep eksperimenteel bewys word deur koherente sigbare oktaafspannende SK te genereer in koniese gesuspendeerde kern vesels met ’n ANDi profiel aan te wend. Die werk wat in die tesis vervat is, maak dus belangrike bydraes tot die beskikbaarheid en toepasbaarheid van vesel gebaseerde breëband koherente SK bronne met verskeie hoë impak toepassings in fundamentele wetenskap en moderne tegnologie.

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Mak, Ka Fai [Verfasser], and Philip [Akademischer Betreuer] Russell. "Nonlinear optical effects in gas-filled hollow-core photonic-crystal fibers / Ka Fai Mak. Gutachter: Philip Russell." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2015. http://d-nb.info/1075479037/34.

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Bethge, Jens Verfasser], Thomas [Akademischer Betreuer] Elsässer, Fedor Manuel [Akademischer Betreuer] [Mitschke, and Oliver [Akademischer Betreuer] Benson. "Novel designs and applications of photonic crystal fibers / Jens Bethge. Gutachter: Thomas Elsässer ; Fedor Mitschke ; Oliver Benson." Berlin : Humboldt Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2012. http://d-nb.info/1020229985/34.

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Abdolvand, Amir [Verfasser], and Philip St J. [Akademischer Betreuer] Russell. "Coherent Raman Interaction in Gas-Filled Hollow-Core Photonic Crystal Fibers / Amir Abdolvand. Betreuer: Philip St.J. Russell." Erlangen : Universitätsbibliothek der Universität Erlangen-Nürnberg, 2011. http://d-nb.info/1016377207/34.

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Epple, Georg [Verfasser], and Philip St J. [Gutachter] Russell. "Spectroscopy of Rydberg Atoms in Hollow-Core Photonic Crystal Fibers / Georg Epple ; Gutachter: Philip St. J. Russell." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2018. http://d-nb.info/1153203324/34.

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Bethge, Jens Lutz [Verfasser], Thomas Akademischer Betreuer] Elsässer, Fedor Manuel [Akademischer Betreuer] [Mitschke, and Oliver [Akademischer Betreuer] Benson. "Novel designs and applications of photonic crystal fibers / Jens Bethge. Gutachter: Thomas Elsässer ; Fedor Mitschke ; Oliver Benson." Berlin : Humboldt Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2012. http://nbn-resolving.de/urn:nbn:de:kobv:11-100199638.

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Li, Jun. "REFRACTIVE INDICES OF LIQUID CRYSTALS AND THEIR APPLICATIONS IN DISPLAY AND PHOTONIC DEVICES." Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2200.

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Liquid crystals (LCs) are important materials for flat panel display and photonic devices. Most LC devices use electrical field-, magnetic field-, or temperature-induced refractive index change to modulate the incident light. Molecular constituents, wavelength, and temperature are the three primary factors determining the liquid crystal refractive indices: ne and no for the extraordinary and ordinary rays, respectively. In this dissertation, we derive several physical models for describing the wavelength and temperature effects on liquid crystal refractive indices, average refractive index, and birefringence. Based on these models, we develop some high temperature gradient refractive index LC mixtures for photonic applications, such as thermal tunable liquid crystal photonic crystal fibers and thermal solitons. Liquid crystal refractive indices decrease as the wavelength increase. Both ne and no saturate in the infrared region. Wavelength effect on LC refractive indices is important for the design of direct-view displays. In Chapter 2, we derive the extended Cauchy models for describing the wavelength effect on liquid crystal refractive indices in the visible and infrared spectral regions based on the three-band model. The three-coefficient Cauchy model could be used for describing the refractive indices of liquid crystals with low, medium, and high birefringence, whereas the two-coefficient Cauchy model is more suitable for low birefringence liquid crystals. The critical value of the birefringence is deltan~0.12. Temperature is another important factor affecting the LC refractive indices. The thermal effect originated from the lamp of projection display would affect the performance of the employed liquid crystal. In Chapter 3, we derive the four-parameter and three-parameter parabolic models for describing the temperature effect on the LC refractive indices based on Vuks model and Haller equation. We validate the empirical Haller equation quantitatively. We also validate that the average refractive index of liquid crystal decreases linearly as the temperature increases. Liquid crystals exhibit a large thermal nonlinearity which is attractive for new photonic applications using photonic crystal fibers. We derive the physical models for describing the temperature gradient of the LC refractive indices, ne and no, based on the four-parameter model. We find that LC exhibits a crossover temperature To at which dno/dT is equal to zero. The physical models of the temperature gradient indicate that ne, the extraordinary refractive index, always decreases as the temperature increases since dne/dT is always negative, whereas no, the ordinary refractive index, decreases as the temperature increases when the temperature is lower than the crossover temperature (dno/dT<0 when the temperature is lower than To) and increases as the temperature increases when the temperature is higher than the crossover temperature (dno/dT>0 when the temperature is higher than To ). Measurements of LC refractive indices play an important role for validating the physical models and the device design. Liquid crystal is anisotropic and the incident linearly polarized light encounters two different refractive indices when the polarization is parallel or perpendicular to the optic axis. The measurement is more complicated than that for an isotropic medium. In Chapter 4, we use a multi-wavelength Abbe refractometer to measure the LC refractive indices in the visible light region. We measured the LC refractive indices at six wavelengths, lamda=450, 486, 546, 589, 633 and 656 nm by changing the filters. We use a circulating constant temperature bath to control the temperature of the sample. The temperature range is from 10 to 55 oC. The refractive index data measured include five low-birefringence liquid crystals, MLC-9200-000, MLC-9200-100, MLC-6608 (delta_epsilon=-4.2), MLC-6241-000, and UCF-280 (delta_epsilon=-4); four middle-birefringence liquid crystals, 5CB, 5PCH, E7, E48 and BL003; four high-birefringence liquid crystals, BL006, BL038, E44 and UCF-35, and two liquid crystals with high dno/dT at room temperature, UCF-1 and UCF-2. The refractive indices of E7 at two infrared wavelengths lamda=1.55 and 10.6 um are measured by the wedged-cell refractometer method. The UV absorption spectra of several liquid crystals, MLC-9200-000, MLC-9200-100, MLC-6608 and TL-216 are measured, too. In section 6.5, we also measure the refractive index of cured optical films of NOA65 and NOA81 using the multi-wavelength Abbe refractometer. In Chapter 5, we use the experimental data measured in Chapter 4 to validate the physical models we derived, the extended three-coefficient and two-coefficient Cauchy models, the four-parameter and three-parameter parabolic models. For the first time, we validate the Vuks model using the experimental data of liquid crystals directly. We also validate the empirical Haller equation for the LC birefringence delta_n and the linear equation for the LC average refractive index . The study of the LC refractive indices explores several new photonic applications for liquid crystals such as high temperature gradient liquid crystals, high thermal tunable liquid crystal photonic crystal fibers, the laser induced 2D+1 thermal solitons in nematic crystals, determination for the infrared refractive indices of liquid crystals, comparative study for refractive index between liquid crystals and photopolymers for polymer dispersed liquid crystal (PDLC) applications, and so on. In Chapter 6, we introduce these applications one by one. First, we formulate two novel liquid crystals, UCF-1 and UCF-2, with high dno/dT at room temperature. The dno/dT of UCF-1 is about 4X higher than that of 5CB at room temperature. Second, we infiltrate UCF-1 into the micro holes around the silica core of a section of three-rod core PCF and set up a highly thermal tunable liquid crystal photonic crystal fiber. The guided mode has an effective area of 440 ƒÝm2 with an insertion loss of less than 0.5dB. The loss is mainly attributed to coupling losses between the index-guided section and the bandgap-guided section. The thermal tuning sensitivity of the spectral position of the bandgap was measured to be 27 nm/degree around room temperature, which is 4.6 times higher than that using the commercial E7 LC mixture operated at a temperature above 50 degree C. Third, the novel liquid crystals UCF-1 and UCF-2 are preferred to trigger the laser-induced thermal solitons in nematic liquid crystal confined in a capillary because of the high positive temperature gradient at room temperature. Fourth, we extrapolate the refractive index data measured at the visible light region to the near and far infrared region basing on the extended Cauchy model and four-parameter model. The extrapolation method is validated by the experimental data measured at the visible light and infrared light regions. Knowing the LC refractive indices at the infrared region is important for some photonic devices operated in this light region. Finally, we make a completely comparative study for refractive index between two photocurable polymers (NOA65 and NOA81) and two series of Merck liquid crystals, E-series (E44, E48, and E7) and BL-series (BL038, BL003 and BL006) in order to optimize the performance of polymer dispersed liquid crystals (PDLC). Among the LC materials we studied, BL038 and E48 are good candidates for making PDLC system incorporating NOA65. The BL038 PDLC cell shows a higher contrast ratio than the E48 cell because BL038 has a better matched ordinary refractive index, higher birefringence, and similar miscibility as compared to E48. Liquid crystals having a good miscibility with polymer, matched ordinary refractive index, and higher birefringence help to improve the PDLC contrast ratio for display applications. In Chapter 7, we give a general summary for the dissertation.
Ph.D.
Optics and Photonics
Optics

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Elser, Wenjia [Verfasser], Christoph [Akademischer Betreuer] Marquardt, and Nicolas [Gutachter] Joly. "Application of Hollow Core Photonic Crystal Fibers in Quantum Optics / Wenjia Elser ; Gutachter: Nicolas Joly ; Betreuer: Christoph Marquardt." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2021. http://d-nb.info/1226428207/34.

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Wang, Chenchen. "Optical frequency references in acetylene-filled hollow-core optical fiber and photonic microcells." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/18831.

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Doctor of Philosophy
Department of Physics
Kristan L. Corwin
Optical frequency references have been widely used in applications such as navigation, remote sensing, and telecommunication industry. For stable frequency references in the near-infrared (NIR), lasers can be locked to narrow absorption features in gases such as acetylene. Currently, most Near NIR references are realized in free space setups. In this thesis, a low-loss hollow-core optical fiber with a diameter of sub millimeters is integrated into the reference setup to provide long interaction lengths between the filling gas and the laser field, also facilitate the optical interaction with low power levels. To make portable NIR reference, gas can be sealed inside the hollow-core fiber, by creating a photonic microcell. This work has demonstrated all-fiber optical frequency references in the Near IR by fabricating and integrating gas sealed photonic microcells in the reference setup. Also, a thoughtful study regarding the lineshape of the fiber-based reference has been accomplished. According the proper modeling of a shift due to lineshape, a correction was applied to our previous absolute frequency measurement of an NIR optical frequency reference. Furthermore, effects of the hollow-core fibers, including mode-dependence frequency shift related to surface modes are explored. In addition, angle splicing techniques, which will improve the performance of the fiber-based frequency reference have been created. Low transmission and return loss angle splices of photonic bandgap fiber, single mode PCF, and large core kagome to SMF-28 are developed and those fibers are demonstrated to be promising for photonic microcell based optical frequency references. Finally, a potentially portable optical metrology system is demonstrated by stabilizing a fiber-laser based frequency comb to an acetylene-filled optical fiber frequency reference. Further work is necessary to fabricate an all-fiber portable optical metrology system with high optical transmission and low molecular contamination.

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Romagnoli, Priscila. "Modelamento, fabricação e caracterização de seções polarizadoras em fibras de cristal fotônico altamente birrefringentes." Universidade Presbiteriana Mackenzie, 2013. http://tede.mackenzie.br/jspui/handle/tede/1426.

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Made available in DSpace on 2016-03-15T19:37:43Z (GMT). No. of bitstreams: 1 Priscila Romagnoli.pdf: 2103605 bytes, checksum: 61f6314f8d7400988a432b7a4793d4be (MD5) Previous issue date: 2013-01-24
Photonic crystal fibers have been proposed as single-polarization (or polarizing) fibers with important applications being demonstrated, for example, in telecommunications, sensing and georeferencing. Although the vast majority of reported studies have focused on the numerical analysis of the performance of PCFs with specific and unconventional designs, post-processing PCFs also allows for great flexibility in altering the characteristics of guidance. In this work, the structure of a commercial, highly birefringent, PCF, with different holes diameters, has been locally changed using a tapering technique, which reduces the transverse dimensions of the fiber, with the application of pressure in the holes. This process was implemented to create 1-cm-long sections with a 66% reduction in their cross-sectional dimensions, through the application of pressure using two different schemes. It is numerically and experimentally shown that the two resulting structures are polarizing. In the first scheme, the same pressure is applied to all holes, resulting in a polarizing PCF at a wavelength of 633 nm, with an experimentally obtained polarization extinction ratio (PER) of 6.44 dB. In the second scheme, the applied pressure was different for the large and small holes, resulting in a polarizing PCF for the 1510-1590 nm wavelength range, with an experimentally obtained PER of more than 30 dB. Both the simplicity of the method and the resulting PER compares favorably with alternative methods to create polarizing conventional and photonic crystal fibers.
Fibras de cristal fotônico (PCFs, do inglês photonic crystal fibers) vêm sendo propostas como fibras polarizadoras, com importantes aplicações sendo demonstradas, por exemplo, em telecomunicações, sensoriamento e georreferenciamento. Apesar da vasta maioria dos trabalhos reportados analisarem numericamente o desempenho de PCFs com designs específicos e não convencionais, o pós-processamento em PCFs comerciais permite grande flexibilidade na alteração das características de guiamento. Neste trabalho, a estrutura de uma PCF altamente birrefringente comercial, com capilares de diferentes diâmetros, foi alterada localmente utilizando uma técnica de afilamento (tapering), que reduz as dimensões transversais da fibra, com aplicação de pressão nos capilares. Este processo foi implementado para criar seções de 1 �� de extensão com uma redução nas dimensões transversais de 66%, aplicando-se pressão de duas formas diferentes. Demonstra-se numérica e experimentalmente que as duas estruturas resultantes são polarizadoras. Na primeira forma, aplicou-se uma única pressão em todos os capilares, resultando em uma PCF polarizadora no comprimento de onda de 633 ��, com uma razão de extinção de polarização (PER) experimentalmente obtida de 6,44 ��. Já na segunda forma aplicaram-se pressões diferentes nos capilares grandes e pequenos, o que resultou em uma PCF polarizadora para a faixa de comprimentos de onda que se estende de 1510 �� a 1590 ��, com uma PER experimentalmente obtida superior a 30 ��. Tanto a simplicidade do método quanto a PER resultante possuem resultados positivos em comparação a métodos alternativos para a produção de fibras convencionais e fibras de cristal fotônico polarizadoras.

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Tyagi, Hemant Kumar [Verfasser], and Philip St J. [Akademischer Betreuer] Russell. "Germanium and gold wore arrays embedded in silica photonic crystal fibers / Hemant Kumar Tyagi. Betreuer: Philip St. J. Russell." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2011. http://d-nb.info/1077582501/34.

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Ziemieńczuk, Marta [Verfasser], and Philip [Akademischer Betreuer] Russell. "Coherent Gas-Laser Interactions via Stimulated Raman Scattering in Hollow-Core Photonic Crystal Fibers / Marta Ziemieńczuk. Betreuer: Philip Russell." Erlangen : Universitätsbibliothek der Universität Erlangen-Nürnberg, 2012. http://d-nb.info/1023597489/34.

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Schmidt, Oliver [Verfasser], Philip St J. [Akademischer Betreuer] Russell, and Ben [Akademischer Betreuer] Fabry. "Dynamics of Optically Trapped Microparticles in Hollow-Core Photonic Crystal Fibers / Oliver Schmidt. Gutachter: Philip St. J. Russell ; Ben Fabry." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2014. http://d-nb.info/1075477735/34.

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Luzi, Giovanni [Verfasser], Antonio [Akademischer Betreuer] Delgado, and Philipp [Akademischer Betreuer] Epple. "Thermo-Fluid-Dynamic Modeling and Simulations of the Drawing Process of Photonic Crystal Fibers / Giovanni Luzi. Gutachter: Antonio Delgado ; Philipp Epple." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2014. http://d-nb.info/1075475686/34.

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Zeltner, Richard [Verfasser], Philip St J. [Akademischer Betreuer] Russell, and Philip St J. [Gutachter] Russell. "Optical Trapping in Liquid-Filled Hollow-Core Photonic Crystal Fibers / Richard Zeltner ; Gutachter: Philip St J. Russell ; Betreuer: Philip St. J. Russell." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2018. http://d-nb.info/1168474388/34.

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Günendi, Mehmet Can [Verfasser], Philip St J. [Akademischer Betreuer] Russell, Philip St J. [Gutachter] Russell, and Markus [Gutachter] Schmidt. "Numerical Modelling of Hollow-Core Photonic Crystal Fibers / Mehmet Can Günendi ; Gutachter: Philip St. J. Russell, Markus Schmidt ; Betreuer: Philip St. J. Russell." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2018. http://d-nb.info/1169913210/34.

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Roth, Paul [Verfasser], Philip St J. [Akademischer Betreuer] Russell, Philip St J. [Gutachter] Russell, Fabio [Gutachter] Biancalana, and Markus A. [Gutachter] Schmidt. "Helical Bloch Modes in Twisted Photonic Crystal Fibers / Paul Roth ; Gutachter: Philip St.J. Russell, Fabio Biancalana, Markus A. Schmidt ; Betreuer: Philip St.J. Russell." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2021. http://d-nb.info/1228627622/34.

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Kao, Chia-Lung, and 高嘉隆. "Band-Structure Analysis of Liquid-Crystal Photonic Crystal Fibers." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/3jn95n.

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碩士
國立中山大學
光電工程學系研究所
97
Filling the liquid crystals (LCs) into the air holes of the photonic crystal fibers (PCFs), we can obtain the liquid-crystal photonic crystal fibers (LCPCFs). Due to the tunable optical properties of the LCs, we can fabricate tunable optical devices based on the LCPCFs. In this thesis, we investigate the photonic bandgap (PBG) properties and find out the effective modal index curves of the LCPCFs by the finite-difference frequency-domain (FDFD) method. The effects of the operation temperature and the alignment of the LCs are discussed. When the alignment of the LC is in the transverse plane of the PCF, we can observe the blue shift and the splitting of the PBGs as we increase the operation temperature. As the LC is aligned along the PCF, the red shift occurs and the splitting disappears. The shift and the splitting of the PBGs are due to the high anisotropic property of the LCs. Besides, we can rotate the alignment of the LCs by the external electric field, and the effects of the alignment on the propagation properties of the LCPCFs are larger than those of the operation temperature. In the experiment, we successfully fabricate the LCPCFs by using the vacuum method. In the measurement of the LCPCF at different operation temperatures,the red shift of the spectra can be observed with the increasing operation temperatures, which has a very good agreement with the simulation results. As we vary the alignment of the LCs with the external electric field, the transmission bands are almost the same as the voltage is less than 200V. During the range of 200V to 400V, the PBGs demonstrate obvious variations and the deep appears at 1050nm. When the external electric field is raised to 400V, the shapes of the spectra are almost the same and the red shift of the PBGs can be observed. The results of our simulation and the experiment measurement can help us to design and fabricate optical devices based on the LCPCFs.

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Dissertations / Theses on the topic 'Photonic crystal fibers'

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