Considered a major field of photonics, plasmonics offers the potential to confine and guide light below the diffraction limit and promises a new generation of highly miniaturized photonic devices. This book combines a comprehensive introduction with an extensive overview of the current state of the art. Coverage includes plasmon waveguides, cavities for field-enhancement, nonlinear processes and the emerging field of active plasmonics studying interactions of surface plasmons with active media.
Inhaltsangabe:Abstract: The ultimate miniaturization of optical devices requires structures that guide electromagnetic energy with a lateral confinement below the diffraction limit of light. In this thesis, the possibility of employing plasmon-polariton excitations in plasmon waveguides consisting of closely spaced metal nanoclusters for this purpose is examined. The feasibility of energy transport with mode sizes below the diffraction limit of visible light over distances of several hundred nanometers is demonstrated. As a macroscopic analogue to plasmon waveguides, the transport of electromagnetic energy in the microwave regime along closely spaced centimeter-scale metal rods is examined. Full-field electrodynamic simulations show that information transport occurs at a group velocity of 0.65c for fabricated structures consisting of copper rods excited at 8 GHz. A variety of passive routing structures and an all-optical modulator are demonstrated. The possibility of guiding electromagnetic energy at visible frequencies with mode sizes below the diffraction limit using plasmon waveguides is analyzed using a point-dipole model and finite-difference time-domain simulations. It is shown that energy transport occurs via near-field coupling between metal nanoparticles, which leads to coherent propagation of energy. For spherical gold particles in air, group velocities up to 0.06c are demonstrated, and a change in particle shape to spheroidal particles shows up to a threefold increase in group velocity. Pulses with transverse polarization are shown to propagate with negative phase velocities antiparallel to the energy flow. Plasmon waveguides consisting of gold and silver nanoparticles were fabricated using electron beam lithography. The key parameters that govern the energy transport are determined for various interparticle spacings and particle chain lengths using far-field measurements of the collective plasmon modes. Spherical gold nanoparticles with a diameter of 50 nm and an interparticle spacing of 75 nm show an energy attenuation of 6 dB/30 nm. This loss can be reduced by one order of magnitude by a geometry change to spheroidal particles. Using the tip of a near-field optical microscope as a local excitation source and fluorescent nanospheres as detectors, experimental evidence for energy transport over a distance of 0.5 μm is presented for plasmon waveguides consisting of silver rods with a 3:1 aspect ratio. Inhaltsverzeichnis:Table of [...]
This exciting new book delivers a comprehensive overview of the cellular network architecture, with focus on the positioning applications and emergency call services, and covers aspects brought by 5G, including the core virtualization and the network slicing to optimize cellular network deployments. Focus is given to the different positioning technologies used in cellular networks, divided in satellite positioning, terrestrial radio positioning, non-RF positioning and a brief introduction to sensor fusion and Bayesian theory. It provides an overview of all the positioning technologies used in cellular networks, from GSM to 5G, from RAT independent technologies, such as A-GNSS (including GNSS evolution, RTK and PPP), WiFi, Bluetooth and sensor fusion, to cellular network native technologies, such as OTDOA / DL-TDOA, ECID, multi-cell RTT and the Angle Of Arrival (AOA) based techniques that take advantage of 5G mmWave beamforming features. Different positioning protocols, especially the LTE Positioning Protocol (LPP), which is used for LTE and 5G NR and defines the communication between the user device (mobile phone, connected vehicle, etc.) and the base station are explained extensively, and compares it with other competing protocols such as OMA LPPE. Furthermore, it also explains the core network positioning protocols (LPPa, NRPPa), that describe the communication between the location server and the core network. Explanation of different signaling parameters will enable the reader to understand better how positioning works in a cellular network. The contents of this book are aimed at all types of users, from beginners to the concept of positioning to experts that are looking to enhance their knowledge of positioning in cellular networks.
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