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Keynote Lectures

Ludger Wöste, Freie Universität Berlin, Germany
          Title: Fundamentals and Applications of Plasma Filaments

Orlando Frazão, INESC Porto, Portugal
          Title: New Advances in Fabry-perot Cavity for Sensing Applications

Klaus Petermann, Technische Universität Berlin, Germany
          Title: Nonlinear Optics in Silicon Photonics

 

Fundamentals and Applications of Plasma Filaments
Ludger Wöste
Freie Universität Berlin
Germany


Brief Bio
Available Soon


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


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.