Novel Insights into Orbital Angular Momentum Beams: From Fundamentals, Devices to Applications

It is well-known by now that the angular momentum carried by elementary particles can be categorized as spin angular momentum (SAM) and orbital angular momentum (OAM). In the early 1900s, Poynting recognized that a particle, such as a photon, can carry SAM, which has only two possible states, i.e., clockwise and anticlockwise circular polarization states. However, only fairly recently, in 1992, Allen et al. discovered that photons with helical phase fronts can carry OAM, which has infinite orthogonal states. In the past two decades, the OAM-carrying beam, due to its unique features, has gained increasing interest from many different research communities, including physics, chemistry, and engineering. Its twisted phase front and intensity distribution have enabled a variety of applications, such as micromanipulation, laser beam machining, nonlinear matter interactions, imaging, sensing, quantum cryptography and classical communications. This book aims to explore novel insights of OAM beams. It focuses on state-of-the-art advances in fundamental theories, devices and applications, as well as future perspectives of OAM beams

Microwave Photonic Applications - From Chip Level to System Level

Die Vermischung von Mikrowellen- und optischen Technologien – Mikrowellenphotonik – ist ein neu aufkommendes Feld mit hohem Potential. Durch die Nutzung der Vorzüge beider Welten hat die Mikrowellenphotonik viele Anwendungsfälle und ist gerade erst am Beginn ihrer Erfolgsgeschichte. Der Weg für neue Konzepte, neue Komponenten und neue Anwendungen wird dadurch geebnet, dass ein höherer Grad an Integration sowie neue Technologien wie Silicon Photonics verfügbar sind. In diesem Werk werden zuerst die notwendigen grundlegenden Basiskomponenten – optische Quelle, elektro-optische Wandlung, Übertragungsmedium und opto-elektrische Wandlung – eingeführt. Mithilfe spezifischer Anwendungsbeispiele, die von Chipebene bis hin zur Systemebene reichen, wird der elektrooptische Codesign-Prozess veranschaulicht. Schließlich werden zukünftige Ausrichtungen wie die Unterstützung von elektrischen Trägern im Millimeterwellen- und THz-Bereich sowie Realisierungsoptionen in integrierter Optik und Nanophotonik diskutiert.The hybridization between microwave and optical technologies – microwave photonics – is an emerging field with high potential. Benefitting from the best of both worlds, microwave photonics has many use cases and is just at the beginning of its success story. The availability of a higher degree of integration and new technologies such as silicon photonics paves the way for new concepts, new components and new applications. In this work, first, the necessary basic building blocks – optical source, electro-optical conversion, transmission medium and opto-electrical conversion – are introduced. With the help of specific application examples ranging from chip level to system level, the electro-optical co-design process for microwave photonic systems is illustrated. Finally, future directions such as the support of electrical carriers in the millimeter wave and THz range and realization options in integrated optics and nanophotonics are discussed

The NASA SBIR product catalog

The purpose of this catalog is to assist small business firms in making the community aware of products emerging from their efforts in the Small Business Innovation Research (SBIR) program. It contains descriptions of some products that have advanced into Phase 3 and others that are identified as prospective products. Both lists of products in this catalog are based on information supplied by NASA SBIR contractors in responding to an invitation to be represented in this document. Generally, all products suggested by the small firms were included in order to meet the goals of information exchange for SBIR results. Of the 444 SBIR contractors NASA queried, 137 provided information on 219 products. The catalog presents the product information in the technology areas listed in the table of contents. Within each area, the products are listed in alphabetical order by product name and are given identifying numbers. Also included is an alphabetical listing of the companies that have products described. This listing cross-references the product list and provides information on the business activity of each firm. In addition, there are three indexes: one a list of firms by states, one that lists the products according to NASA Centers that managed the SBIR projects, and one that lists the products by the relevant Technical Topics utilized in NASA's annual program solicitation under which each SBIR project was selected

Microwave apparatus for gravitational waves observation

In this report the theoretical and experimental activities for the development of superconducting microwave cavities for the detection of gravitational waves are presented.Comment: 42 pages, 28 figure

ATS F and G /phases B and C/, volume 1 Final report

Design parameters and program objectives of Applications Technology Satellites 7 and

Design, Fabrication, and Demonstration of Square Holey Dielectric THZ Waveguides

A variety of novel dielectric THz waveguides were demonstrated to increase a channel capacity in a chip-to-chip communication system. Square holey cladding dielectric THz waveguides were designed, fabricated, and characterized. The single material holey cladding waveguide is low loss and easy to fabricate compared to doped core fibers. The square geometry supports two states of polarization with minimum cross-talk for polarization division multiplexing applications. Simulations show the waveguide supports two states of polarization across the frequency range of 180 GHz to 360 GHz. In addition, simulations show good mode isolation and low bending losses. Holey cladding square waveguide was fabricated using a custom-built draw tower to preserve the square geometry. TOPAS was chosen from several studied dielectrics for its low material loss and fabrication capabilities. Fabricated waveguides were shown to support the mode despite manufacturing defects. Fiber loss measurements showed a 24 dB/m loss that approach the accepted material loss of TOPAS (22 dB/m). THz vortex waveguides were demonstrated for space division multiplexing applications for the first time. The holey cladding TOPAS-based vortex waveguide was designed to preserve orbital angular momentum for l=1 and 2 at 280 GHz. The output power of the waveguide for different l and core sizes were studied. The waveguide was fabricated with the custom-built draw tower. Transmission of a first order OAM beam at 280 GHz was experimentally demonstrated. The first order, l=1, Laguerre-Gaussian beam was generated with a custom-made spiral phase plate. Inspired by the vortex waveguide design, several low-loss square holey core/cladding waveguides were designed and simulated for polarization division multiplexing. The waveguides combine the benefits of low loss and broadband transmission, while supporting two states of polarization. The boundary conditions created by the holey cladding confine the beam to the holey core for a low loss transmission. Three square holey core/cladding designs were proposed. These designs include a single-hole core, a nine-hole core, and a core comprised of four square capillary tubes. The square capillary tubes exhibits 7 dB/m, which is significantly lower than the material loss of TOPAS (22 dB/m)

Single and Multi-photon Laser Induced Fluorescence for Electric Thruster and Fusion Applications

Single and Multi-photon Laser Induced Fluorescence for Electric Thruster and Fusion Applications Thomas Edward Steinberger Laser-based diagnostics are increasingly sought after to investigate a variety of plasmas due to their non-perturbative capabilities. Specifically, laser induced fluorescence (LIF) provides a highly localized and precise spectroscopic technique to measure absolute density, temperature, and bulk flow. In this work, LIF and two-photon absorption laser induced fluorescence (TALIF) are used to investigate electric propulsion and fusion-relevant plasmas, respectively. Ion velocity distribution functions (IVDF) of singly ionized atomic iodine (I II) are measured for the first time and lineshape characteristics are presented for the diagnosis of Hall thrusters with iodine as a propellant. A non-perturbative technique of determining external magnetic field from Zeeman split iodine spectra is also discussed and results are shown. Fusion-relevant plasmas are investigated in the Prototype Material Plasma Exposure eXperiment (Proto-MPEX) using TALIF. Ground state neutral deuterium velocity distribution functions are measured during Proto-MPEX operation. Absolute neutral density, neutral temperature, and neutral bulk flow are determined. Absolute neutral deuterium densities are calculated by calibrating measured deuterium velocity distributions with xenon and krypton. Calibrated density values from the two gases are compared. This work presents, for the first time, deuterium absolute densities calibrated using xenon, first proposed by Elliot et al. Temporal evolution of deuterium signal is shown over the entirety of a Proto-MPEX plasma pulse. Neutral density, temperature, and bulk flow dependence on radio frequency (rf) power and radial location is presented. Lastly, a novel three photon laser induced fluorescence (3pLIF) scheme is shown for krypton