The invention ofthe laser 25years ago resulted in powerfullight sources which led to the observation of unexpected and striking phenomena. New fields of science such as holography and nonlinear optics developed constituting the basis of this volume. The classical principle of linear superposition of light wavesdoes not hold anymore. Two laser beams crossing in a suitable material may produce a set of new beams with different directions and frequencies. The interaction of light waves can be understood by considering the optical grating structures which develop in the overlap region. The optical properties of matter become spatially modulated in the interference region of two light waves. Permanent holographic gratings have been produced in this way by photographic processes for many years. In contrast, dynamic or transient gratings disappear after the inducing light source, usually a laser, has been switched off. The grating amplitude is controlled by the light intensity. Dynamic gratings have been induced in a large number ofsolids, liquids, and gases, and are detected by diffraction, 'forced light scattering' of a third probing beam, or by self-diffraction of the light waves inducing the grating. The combined interference and diffraction effect corresponds to four-wave mixing (FWM) in the language of nonlinear optics. The process is called degenerate ifthe frequenciesofthe three incident wavesand the scattered wave are equal. Degenerate four-wave mixing (DFWM) is a simple method to achieve phase conjugation, i.e. to generate a wave which propagates time reversed with respect to an incident wave.

Autorentext

Prof. Dr.-Ing. Hans Joachim Eichler has been full professor and director of the Laser Group at the Institute of Optics and Atomic Physics (IOAP) of the Technical University of Berlin since 1972. He was project officer on behalf of the Federal Ministry of Education and Science BMBF and from 1980 to 1983 guest Member of Technical Staff at the Bell Laboratories in New Jersey/USA. In addition, he served as Vice Dean of the Faculty of Mathematics and Natural Sciences at the TUB. In 1998, he joined the Supervisory Board of Laser Medicine Technology GmbH Berlin and worked as CTO and CEO from 2003 to 2013. Together with his coworkers, he developed new diode-pumped solid state and Raman lasers, elaborated diffraction at dynamic gratings as a new topic of nonlinear optics, and used light scattering and spectroscopy with ultrashort laser pulses for medical diagnostics and biophotonics. In 1982 he became chairman of the Quantum Optics association of the German Physical and Society and the Society of Applied Optics. Projects with industrial applications include the preparation and characterization of multilayer systems for mirrors and filters, fiber optics and silicon nanophotonics. His worldwide cooperation is documented in more than 500 journal publications, 10 patents and several books in German, English and Russian language. Prof. Dr. Jürgen Eichler graduated at the Technical University of Berlin in atomic physics and got his PhD at the University of Karlsruhe in nuclear physics. He joined Bosch company where he worked several years on optical memories. 1975 he became Professor of physics at the University of Applied Sciences Berlin and later at the Universidade Federal do Rio de Janeiro. He performed research on atomic and laser physics in Germany, Brazil and the United States. His teaching activities were related mainly on medical physics, especially laser technology in medicine. He published numerous scientific papers and 8 books on basic physics, lasers and holography. In the last years he produced holograms for applications in design, graphics and art. He is cofounder of the Academy of Laser Safety in Berlin which offers services to laser users. Dr. Oliver Lux received his diploma in physics from the Technical University of Berlin in 2009, where he also earned his PhD in 2013 under the supervision of Prof. Hans Joachim Eichler. His doctoral research focused on stimulated Raman scattering in crystalline materials as well as on high-power and frequency-stable solid-state lasers for trace gas detection. As a postdoctoral research fellow at the Institute of Optics and Atomic Physics, he was also concerned with the development of fiber-optic sensors for spectroscopic applications. In 2015, he was awarded a fellowship by the German Research Foundation to pursue postdoctoral research on diamond Raman lasers at the MQ Photonics Research Centre, Macquarie University in Sydney. Afterwards, he joined the Institute of AtmosphericPhysics of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt) in Oberpfaffenhofen, Germany where he is currently involved in the validation of the spaceborne wind lidar mission Aeolus of the European Space Agency. Dr. Lux has co-authored more than 40 publications in peer-reviewed journals and was a recipient of the Green Photonics Young Scientist Award by the Fraunhofer Society in 2014.

Inhalt

1. Introduction.- 2. Production and Detection of Dynamic Gratings.- 3. Mechanisms of Grating Formation and Grating Materials.- 4. Diffraction and Four-Wave Mixing Theory.- 5. Investigation of Physical Phenomena by Forced Light Scattering.- 6. Real-Time Holography and Phase Conjugation.- 7. Gratings in Laser Devices and Experiments.- 8. Conclusion and Outlook.- List of Symbols.- Units, Mathematical Symbols.- References.- Additional References.