Laser Intensity Scaling through Stimulated Scattering in Optical Fibers

The influence of stimulated scattering on laser intensity in fiber optic waveguides is examined. Stimulated Brillouin scattering (SBS) in long, multimode optical waveguides is found to generate a Stokes beam that propagates in the fiber LP01 mode. Additionally, the same process is found to combine multiple laser beams into a single spatially coherent source. Limitations in beam cleanup and combining are also investigated to identify ways to overcome them. The last portion of the dissertation theoretically examines suppression of stimulated Raman scattering in fibers to eliminate the restriction this imposes on the power of a fiber laser or amplifier. The suppression was modeled using both a holmium dopant and adding a long period grating to the fiber. Both methods were shown to have a significant effect on the SRS threshold

Laser Systems for Applications

This book addresses topics related to various laser systems intended for the applications in science and various industries. Some of them are very recent achievements in laser physics (e.g. laser pulse cleaning), while others face their renaissance in industrial applications (e.g. CO2 lasers). This book has been divided into four different sections: (1) Laser and terahertz sources, (2) Laser beam manipulation, (3) Intense pulse propagation phenomena, and (4) Metrology. The book addresses such topics like: Q-switching, mode-locking, various laser systems, terahertz source driven by lasers, micro-lasers, fiber lasers, pulse and beam shaping techniques, pulse contrast metrology, and improvement techniques. This book is a great starting point for newcomers to laser physics

Novel Specialty Optical Fibers and Applications

Novel Specialty Optical Fibers and Applications focuses on the latest developments in specialty fiber technology and its applications. The aim of this reprint is to provide an overview of specialty optical fibers in terms of their technological developments and applications. Contributions include:1. Specialty fibers composed of special materials for new functionalities and applications in new spectral windows.2. Hollow-core fiber-based applications.3. Functionalized fibers.4. Structurally engineered fibers.5. Specialty fibers for distributed fiber sensors.6. Specialty fibers for communications

Recent Progress in Optical Fiber Research

This book presents a comprehensive account of the recent progress in optical fiber research. It consists of four sections with 20 chapters covering the topics of nonlinear and polarisation effects in optical fibers, photonic crystal fibers and new applications for optical fibers. Section 1 reviews nonlinear effects in optical fibers in terms of theoretical analysis, experiments and applications. Section 2 presents polarization mode dispersion, chromatic dispersion and polarization dependent losses in optical fibers, fiber birefringence effects and spun fibers. Section 3 and 4 cover the topics of photonic crystal fibers and a new trend of optical fiber applications. Edited by three scientists with wide knowledge and experience in the field of fiber optics and photonics, the book brings together leading academics and practitioners in a comprehensive and incisive treatment of the subject. This is an essential point of reference for researchers working and teaching in optical fiber technologies, and for industrial users who need to be aware of current developments in optical fiber research areas

Ion-exchange in Glasses and Crystals: from Theory to Applications

Since its first observation in 1850, ion-exchange (IEx) has become a fundamental process in many applications involving water treatment, catalysis, chromatography, and the food and pharmaceutical industries. Starting from the early 1900s, another relevant application of IEx has been in the glass industry, with the surface tempering of glass produced by a K+–Na+ ion exchange. Nowadays, photonics has greatly exploited IEx technology: graded-index microlenses, graded-index fibers and integrated optical waveguides and devices are examples of achievements made possible by the IEx process. Moreover, ion-exchange is possible in ferroelectric crystals, too, and has been fundamental for the development of many linear and nonlinear integrated optical devices in lithium niobate and tantalate.This volume collects articles published in the corresponding Special Issue of the Applied Sciences journal. Four review articles, written by internationally renowned experts in this field, provide complementary overviews of the history, fundamental aspects, designs and fabrications of devices, and technological achievements. Three articles describe original research in the fields of diffraction grating, photo-thermo-refractive glasses, and Yb-doped lithium niobate. This volume constitutes a valuable and updated reference for all students and researchers wishing to improve their knowledge and/or make use of ion-exchange technology and its applications

Construction of a caesium quantum gas microscope

In dieser Arbeit beschreibe ich den Aufbau eines neues Quantengasmikroskops. Das Ziel des Experiments ist die Simulation von topologischen Vielteilchensystemen in optischen Gittern. Als Atomspezies wurde aufgrund einer leicht zugänglichen Feshbach Resonanz bei niedrigem magnetischem Feld und seiner großen Feinstrukturaufspaltung Cäsium gewählt. Die Feshbach Resonanz erlaubt die Änderung der Wechselwirkung zwischen den Atomen. Die große Feinstrukturaufspaltung ermöglicht es die Atome in ein anti-magisches Gitter zu laden ohne in der experimentellen Versuchsdauer durch die Photonstreurate limitiert zu sein. Durch Ramanübergänge zwischen unterschiedlichen Hyperfeinzuständen von Cäsium kann dann ein künstliches Magnetfeld simuliert werden, eine essenzielle Methode für die Realisierung von Chernisolatoren. Die hohe numerische Apertur die für ein Quantengasmikroskop benötigt wird beschränkt den optischen Zugang zu den Atomen. Dies erschwert den Aufbau der optischen Laserstrahlen zum Kühlen und Manipulieren der Atome. Wir verwenden optischen Transport mithilfe eines laufenden optischen Gitters um die Atome nach einer Vorkühlphase in einen anderen Teil der Vakuumkammer, einer Glaszelle, zu schieben. Dies erlaubt es, die Laserstrahlen die fürs Vorkühlen benötigt werden unabhängig vom Mikroskopobjektiv auf die Atome auszurichten. Das Transportgitter wird durch die Interferenz zwischen einem Gauß-förmigen Laserstrahl und einem Bessel-förmigen Laserstrahl erzeugt. Der Besselstrahl, ein nahezu beugungsfreier Laserstrahl, erlaubt es die Atome über eine \SI{43}{cm} lange Transportdistanz gegen Gravitation zu halten. Wir transportieren \SI{3e6}{Atome} von der MOT Kammer in die Glasszelle in weniger als \SI{26}{ms}, ohne dabei die Temperatur zu erhöhen. Die Transporteffizienz ist etwa 75\% und durch Gravitation und Atomverluste am Anfang des Transports limitiert. Sobald die Atome in der Glaszelle ankommen, werden sie in eine gekreuzte Dipolfalle umgeladen. Wir evaporieren indem die Fallentiefe reduziert und die Falle gekippt wird. Nach der Kondensation wird das BEC in eine einzelne Ebene eines vertikalen Gitters und darauf folgend in ein horizontales Gitter geladen. Um die Atome durch das Mikroskopobjektiv abzubilden wird Fluoreszenzlicht verwendet. Während der Fluoreszenzabbildung werden die Atome durch optische Molasse gekühlt und die optischen Gitter auf etwa 120\,µK vertieft damit die Atome in 1\,s um die 25.000 Fluoreszenzphotonen streuen können ohne im Gitter zu tunneln. Der in dieser Arbeit beschriebene experimentelle Aufbau wird es uns ermöglichen den Einfluss von Wechselwirkungen auf topologische Phasen mit Einteilchenauflösung zu untersuchen. Dies erlaubt es, Annahmen über die mikroskopische Dynamik in diesen Phasen zu testen und unser Verständnis zu vertiefen.In this work I describe the setup of a new quantum gas microscope. The goal of the experiment is the simulation of topological many-body systems in lattices. Caesium was picked as atomic species, because of its easily accessible Feshbach resonance at low magnetic fields and its large fine-structure splitting. The Feshbach resonance allows changing the interaction between atoms. The large fine-structure splitting enables loading the atoms into an anti-magic lattice without limiting the experiment duration via scattering of lattice photons. Using Raman transitions between different hyperfine states of caesium, an artificial magnetic field can be simulated, an essential method for the realization of Chern insulators. The high numerical aperture necessary for a quantum gas microscope limits the optical access to the atoms. This complicates the setup of the optical laser beams for cooling and manipulating the atoms. We use optical transport based on a running wave optical lattice to transfer the atoms after pre-cooling into a different section of the vacuum system, a glass cell. This allows alignment of the pre-cooling laser beams independent of the microscope objective. The transport lattice is created via interference between a Gaussian laser beam and a Bessel beam. The Bessel beam, a diffractionless laser beam, enables us to hold the atoms against gravity over the transport distance of \SI{43}{cm}. We transport \SI{3e6}{atoms} from the MOT chamber to the glass cell in less than \SI{26}{ms} without any temperature increase. The transport efficiency is around 75\%, limited by gravity and loss at the start of transport. After the atoms have arrived in the glass cell they are transferred into a crossed dipole trap. We evaporate the atoms by reducing the trap depth and tilting the trap. After condensation we trap the BEC in a single plane of a vertical lattice. The BEC is subsequently loaded into a 2D horizontal lattice. Fluorescence light is used to image the atoms through the microscope objective. During fluorescence imaging, the atoms are cooled using an optical molasses and the optical lattice depth is increased to around 120\,µK to allow the atoms to scatter up to 25.000 fluorescence photons in 1\,s without tunneling in the lattice. The experimental setup detailed in this thesis will allow us to study the effects of interactions on topological phases of matter with single particle resolution. This paves the way to testing our assumptions and extending understanding of the microscopic dynamics in these phases