TITLE: Eikonal Methods and Non-Paraxial Vector Solutions for Focused Radiation *PHYS 798E and ENEE 698D: Problems in Advanced Physics; Electrophysics
Speaker: Dr. Daniel Gordon, Naval Research Laboratory, Plasma Physics Division
ABSTRACT: The eikonal approximation can be used to describe radiation fields when feature sizes are much larger than a wavelength. Ray tracing can be viewed as a solution technique for the eikonal wave equation, which yields phase and amplitude information. Unlike paraxial methods, eikonal methods make no assumption regarding the directional content of the wavenumber spectrum, which is an important requirement for correct treatment of tightly focused radiation, and for characterizing spherical aberrations in an optical system. On the other hand, ray tracing suffers from catastrophic failure in the region of a caustic, which is often precisely the region of interest. We will discuss an efficient method for matching eikonal fields with exact solutions of Maxwell’s equations in the caustic region. This method may be used to compute the non-paraxial vector fields produced at the focus of a realistic optical system, or to develop a theory of non-paraxial Gaussian beams. NRL is developing a new eikonal wave code “SeaRay” which utilizes these techniques.
Bio. Dr. Daniel Gordon received the Ph.D. in electrical engineering from the University of California, Los Angeles in 1999. He has been with the Plasma Physics Division at the Naval Research Laboratory, in various capacities, since graduating. He is currently the head of the Laser Physics Section in the Beam Physics Branch. He has worked on experiments with various ultra-intense laser systems, including the Mars/Neptune laser at UCLA, the Vulcan laser at Rutherford-Appleton Laboratories, and the TFL laser at NRL. He has been involved with recent experiments and simulations on laser acceleration of electrons and protons at NRL and Brookhaven National Laboratory, and is currently leading an effort to construct a terawatt class carbon dioxide laser for AFRL. His interests include laser-plasma interaction, strong-field physics of atoms, hydrodynamics, radiation generation, and numerical simulation