OSC Colloquium: Dave Hagan, "Ultrafast optical nonlinearities in semiconductors"

Title: "Ultrafast optical nonlinearities in semiconductors" 

Abstract: 

One reason for using electromagnetic waves (radio, light. etc.) in communication is that photons do not directly interact with each other, allowing multiple simultaneous channels of information to be transmitted. However, this property presents obstacles for tasks such as light-by-light switching or optical computing. Nonlinear optics, where intense light may change the properties of a material, in turn affecting the propagation of other light waves, provides a method where all-optical switching and related effects may be realized. I will describe some of the basic mechanisms for these effects, and how we characterize materials and resolving the various contributions to irradiance-dependent refractive index and absorption. Our understanding of nonlinear optical materials characterization has progressed sufficiently over the years to allow a reliable picture of the physical processes leading to the nonlinear optical properties of a material. This is largely thanks to the development of reliable, complimentary characterization methods. I will provide an overview of our techniques in nonlinear refraction and absorption characterization. Additionally, I will describe how nonlinear interactions can be strongly enhanced when two very different wavelengths are used. In addition to the obvious applications of this effect, I will describe applications in diverse applications as infrared detection and tunable mid-IR sources. Finally, I will present some rather amazing results in so-called “epsilon-near-zero” materials. 

Bio: 

Dr. David J. Hagan

Pegasus Professor of Optics and Physics 

Dean of the College of Optics and Photonics, CREOL 

University of Central Florida 

David J. Hagan received his PhD degree in Physics at Heriot-Watt University, Edinburgh, Scotland in 1985. After a brief spell as research scientist at the University of North Texas, he moved to UCF in 1987 as a founding member of the CREOL faculty. He is currently Pegasus Professor of Optics and Physics and serves as Dean of the College of Optics and Photonics. He has served on the Board of Directors of OSA and was recently elected to the SPIE Board of directors. He was the founding Editor-in-Chief of Optical Materials Express from 2010-2015. His current research interests include nonlinear optical materials, especially semiconductors and organics, applications of extremely nondegenerate nonlinear optics, and techniques for nonlinear optical characterization and spectroscopy. Dr. Hagan is a Fellow of OSA and SPIE.