SEMINAR

Topic: Negative Refraction of Ultrashort Electromagnetic Pulses

Speaker: Dr. Michael Scalora U.S. Army RDECOM

Date & Time: Thursday, April 13, 2006, 1:00 PM

Place: Room 140 VMC (Chambers Hall)

I will first discuss pulse propagation effects across a boundary that separates an ordinary medium from a medium with simultaneously negative dielectric permittivity and magnetic permeability, i.e. negative index material or NIM. Solving Maxwell's equations with two spatial coordinates (one longitudinal, one transverse) and time we find negative refraction as the wave packet undergoes significant and unusual shape distortions. Both a direct calculation of the spatial derivative of the instantaneous, local phase of the pulse and a Fourier analysis of the signal reveal that inside a negative index material, a transmitted, forward-moving wave packet is indeed a superposition of purely negative wave vectors. Causality is not violated in the short pulse regime, and energy and group velocities do not exceed the speed of light in vacuum. I will then briefly discuss a new generalized nonlinear Schrödinger equation for negative index materials, as well as second harmonic generation and second order gap solitons in structure of finite length.

Dr. Micheal Scalora graduated from Rensselaer Polytechnic Institute in 1990. He came to redstone Arsenal in 1991 to work with professor Chuck Bowden as a National Research Council research associate in 1991. Since 2001 Dr. Scalora has been a Physicist for US Army RDEC.