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Colloquia & Guest Speakers


An introduction to ultrafast nonlinear refraction and absorption.

David Hagan

Interim Dean & Director; Pegasus Professor of Optics & Photonics

CREOL, The College of Optics & Photonics, University of Central Florida,

Orlando, FL 32816, USA

Monday, September 21, 2020
3 p.m.–4 p.m.
Zoom Virtual Setting


One reason for using electromagnetic waves (radio, light. etc.) in communication is that photons do not directly interact with each other.  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 go about characterizing materials and resolving the various contributions to irradiance-dependent refractive index (nonlinear refraction) and absorption (nonlinear 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 and complimentary methods for characterization of nonlinear optical properties. I will provide an overview of our techniques in nonlinear refraction and absorption characterization. For this talk, I will focus on how we characterize the nonlinear optical properties of the atmosphere.


Dave HaganBiography

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 Photonics and also serves as the Interim Dean of the College. He was the founding Editor-in-Chief of Optical Materials Express and also served as Executive Editor-in-Chief of Chinese Optics Letters. 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.