Fundamentals and Applications of Plasma Filaments
Ludger Wöste, Freie Universität Berlin, Germany
New Advances in Fabry-perot Cavity for Sensing Applications
Orlando Frazão, INESC Porto, Portugal
Nonlinear Optics in Silicon Photonics
Klaus Petermann, Technische Universität Berlin, Germany
Varying Speed of Light, Cosmic Structure and the Quest for Quantum Gravity
João Magueijo, Imperial College London, United Kingdom
FiberLab – A Multi-sensing Approach in a Single Optical Fiber
Wolfgang Schade, Clausthal University of Technology, Germany
Fundamentals and Applications of Plasma Filaments
Ludger Wöste
Freie Universität Berlin
Germany
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Brief Bio
Studies of physics and electro-techniques at the Technical University, Aachen, 1965 -1968; Study of physics at the University of Bonn, 1968–1970; Diploma thesis with Prof. Dr. H. Walther at the Universities of Bonn und Cologne, Topic: “Deflection of a sodium atomic beam in the radiation field of a dye laser”; 1970–1972; Research assistant with Prof. Dr. E. Schumacher at the Institute of Chemistry, University of Bern, 1973-1978; Promotion at the University of Bern with the grade‚ summa cum laude’;
Topic: "Mass-selective laser spectroscopy of metal atom clusters“, 1978; Full professor of Experimental Physics at the Freie Universität Berlin since 1989. He has held the following positions: Research stage with Prof. R. N. Zare at the Department of Chemistry, Stanford University, Research topic: Reactions of optically oriented molecules, 1978-1980; Project leader and lecturer at the ETH Lausanne, Research topic: Optical and dynamic properties of metal clusters“, 1989-1987; Guest professor at the Laboratoire Aimé Cotton, Orsay, Research topic: Non-metal metal transition in mercury clusters, 1984; Founder and director of the Laser Application Centre, Lausanne, Research topic: "Industrial, medical, and analytical laser applications", 1987-1989; Dean of the physics department at the Free University of Berlin, 2007-2009. Honoured with Innovation-Award of the lands Berlin and Brandenburg, 1995; Smoluchowski-Warburg award of the German and Polish Physical Societies, 1999, Concurrent Professor of the University Nanjing/China, 2004; Doctor honoris causa of the University Claude Bernard, Lyon/France, 2005; Doctor honoris causa of the West University, Timisoara/Romania, 2006; Gay-Lussac–Humboldt Award of the French Minister of Sciences, 2006; Ordre National du Merite per decrete of the President of the French Republic, 2007. His main research areas include Femtosecond Spectroscopy and Coherent Control, Structure and Dynamics of Metal Clusters; White-Light Plasma Channels in Air and Optical Remote Sensing, where he has 316 scientific publications, 14 patents and 3 books.
Abstract
When sufficiently powered femtosecond laser pulses are launched into the atmosphere, white light emitting plasma filaments or even bundles of those are generated along the beam. Under well chosen pulse conditions these bundles may extend even over kilometre lengths. Their formation is based on a fascinating interplay of non-linear optical processes like Kerr lensing, plasma defocusing and self phase modulation. Filaments exhibit along their trajectory extraordinary properties, from which fascinating applications emerge. They emit, for example, directional white light in a wide spectral range from the IR to the UV, which can efficiently (> 60%) be extracted to produce ultra-short pulses (< 5fs). Further they allow the remote and simultaneous analysis of a rich variety of gaseous atmospheric constituents (fs-LIDAR), and when they hit solid or liquid targets, they emit intensive characteristic plasma light, which allows the remote identification of soil, vegetation, waters, etc. (F-LIBS). Until energy levels of 5mJ single filaments are formed. Their diameter is about 100 µ and their length reaches up to 100 metres. So at sufficient repetition rates (> 100 kHz) they cut materials or tissue at meters distance, without focussing the beam and without melting or burning the material. Most interesting properties result from the plasma character of such filament bundles in air. Amazingly they can even be heard by ear, which provides a good and simple plasma monitor. More important, however, is the phenomenon, that the air along filament bundles becomes electrically conductive. The effect allows not only to guide and control electric discharges and currents, it provides a realistic chance to control lightings. With the advent of non-metallic airplanes this aspect has become most important for air traffic safety, namely for situations, when airplanes are obliged to land across thunderclouds. We have successfully demonstrated an influence of fs-laser induced filaments on a lightning. We are, however, still far off from reliably controlling them. So, in the future we wish to explore all critical parameters and develop concepts, how the requirements be met. Another still fully unexplored, but quite relevant effect resulting from the plasma character of filaments is the formation of fog traces and droplets along their path in humid air. The basic effect is quite similar to the formation of charge traces in a Wilson-type fog chamber; but there are also striking differences: As our recent laboratory and field measurements clearly showed, laser-induced water condensation and droplet formation was not only observed in super saturated air but even when the air humidity was the below its saturation threshold. The effect is very promising and can well become a new and important tool in atmospheric research, namely the better understanding and possibly even local control of cloud formation. First, however, the effect must fully be characterized and understood.
New Advances in Fabry-perot Cavity for Sensing Applications
Orlando Frazão
INESC Porto
Portugal
Brief Bio
Orlando Frazão graduated in Physical Engineering from the University of Aveiro, Portugal. He received his Ph. D. in Physics from University of Porto, Portugal. From 1997 to 1998, he was with the Institute of Telecommunications, Aveiro. Presently, he is an invited Assistant Professor at Dept. Physics and Astronomy of Faculty of Science at University of Porto and he is also a Senior Researcher at Optoelectronics and Electronic Systems Unit, INESC Porto. His present research interests included optical fiber sensors and optical communications. He has more than 300 papers in international journals and conferences. He participated as organized committee of several International conferences. He has three scientific awards. He is senior member of the SPIE and OSA.
Abstract
An overview of optical fiber sensors based on Fabry-Perot interferometers with a focus on sensing applications applications. The next generation of these fiber types interferometers are based in photonic crystal fibers, microfabrication as well as by chemical etching of special structures. High temperature measurements with linear behavior are observed namely in pure silica fibers. New configurations are presented as possible solutions to be considered in extreme or special conditions.
Nonlinear Optics in Silicon Photonics
Klaus Petermann
Technische Universität Berlin
Germany
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Brief Bio
Dr. Petermann was born in Mannheim, Germany, on October 02, 1951. He received the Dipl.-Ing. degree in 1974 and the Dr.-Ing. degree in 1976, both in electrical engineering from the Technische Universität Braunschweig, Germany. From 1974 to 1976 Dr. Petermann was a Research Associate at the Institut für Hochfrequenztechnik, Technische Universität Braunschweig, where he worked on optical waveguide theory. From 1977 to 1983 he was with AEG-Telefunken, Forschungsinstitut Ulm, Germany, where he was engaged in research work on semiconductor lasers, optical fibers, and optical fiber sensors. In 1983 he became a full professor at the Technische Universität Berlin, where his research interests are concerned with optical fiber communications and integrated optics. In 1993 Dr. Petermann was awarded with the the Leibniz-award from the ‘Deutsche Forschungsgemeinschaft’. In 1999/2000 he did receive the “distinguished lecturer”-award from the Laser and Electro-Optics Society within the IEEE. From 1999 – 2004 he was an associate editor for IEEE Photonics Technology Letters and from 1996 – 2004 he was a member of the board of the VDE. From 2004 until 2006 he was Vice President for research at the Technische Universität Berlin and from 2001 – 2008 he was member of the Senate of the Deutsche Forschungsgemeinschaft (German research council). Dr. Petermann is a fellow of the IEEE and a member of the Berlin-Brandenburg Academy of Science as well as of acatech, the German Academy of Science and Engineering.
Abstract
Silicon is a mature material not only for micro-electronics but also for photonic applications, which is expressed in the term “Silicon Photonics”. Within “Silicon Photonics” it is not only possible to realize passive components like optical waveguides, couplers, filters etc. but also high speed modulators and photo-receivers ready to use for optical fibre communication at either 1.3 or 1.55 µm. Silicon also exhibits high 3rd order optical nonlinearities which, in combination with the extremely tiny cross section of Si-nanowires, enables very efficient optical signal processing also in the 1.55 µm telecommunication window. Taking into account also “two photon absorption” and avoiding losses due to the generation of free carriers, methods will be presented for applications of optical nonlinear signal processing like wavelength conversion for high speed data signals and parametric optical amplification including phase-sensitive parametric amplification for the regeneration of phase-encoded signals. It will be shown, that Silicon Photonics thus enables the realization of integrated circuits for both electronic and photonic signal processing.
Varying Speed of Light, Cosmic Structure and the Quest for Quantum Gravity
João Magueijo
Imperial College London
United Kingdom
Brief Bio
Joao Magueijo was born in Évora, Portugal, in 1967. He got his PhD at Cambridge University in 1993, following which he became a Research Fellow at St. John's College. Since 1996 he has been at Imperial College, first as a Royal Society Fellow, then as staff, becoming a Professor in 2006. His work includes an attempt to build cosmology upon theories permitting the variation of the fundamental constants of nature. More recently he has worked on quantum gravity theories, and how cosmology may be used to test them.
Abstract
Varying constants theories in several guises may be essential for the resolution of a number of impasses in cosmology and quantum gravity. Perhaps the most radical of them all -- varying speed of light theories -- may be the clue to extracting phenomenology from quantum gravity theories, finally rendering the field properly a branch of science. I will review this possibility, with particular emphasis on the issue of the generation of cosmic structure and primordial gravitational waves.
FiberLab – A Multi-sensing Approach in a Single Optical Fiber
Wolfgang Schade
Clausthal University of Technology
Germany
Brief Bio
Wolfgang Schade is a full Professor of physics at Clausthal University of Technology in Germany and also head of the department Fiber Optical Sensor Systems at Fraunhofer Heinrich Hertz Insititute (HHI) in Goslar/Germany. He is author or co-author of more than 120 papers in journals and books and holds more than 20 patents. His research interests are laser spectroscopy, femtosecond laser materials processing and applications of fiber optical sensors to industrial process control, battery security and medical. Very recently he developed with his team a fiber optical 3D shape and tracking system on the basis of fiber Bragg gratings processed in a single mode optical fiber by point to point femtosecond laser direct writing.
Abstract
Femtosecond laser technology allows a new approach for direct writing of waveguides and periodic modulation of the index of refraction in optical transparent materials such as fibers. This technique can be used for processing Bragg grating structures in the core or in the cladding of an optical fiber but also in combination with chemical etching for processing well defined microstructures that offer interesting and up to now unknown possibilities for designing chemical fiber sensors. The combination of both approaches is the basis for the novel FiberLab concept that will find interesting application in fiber based 3D-shape sensing devices used in medicine for catheter navigation or in oil and gas exploration for downhole monitoring. Both, the technology and various very recent applications will be discussed.