Recent Colloquium

Metamaterials (MM) and Photonic Crystals (PC) are artificial materials that are characterized by an array of repeating unit cell structures in one- or more dimensions.  These materials exhibit novel properties when interacting with waves.  For example, negative refractive index behavior and designer band gaps can be realized for a working wave frequency.  The unit cell structure that constitutes a MM/PC typically renders a static response of the material to interacting waves.  However, adding a plasma discharge within a unit cell provides capability for dynamically tuning the MM/PC properties.  For example, the dynamic tuning of effective dielectric properties/refractive index of the MM, band gap tuning of PCs can be achieved.  Depending on the working frequency, the requirements on the plasma discharge properties can be challenging to achieve.

This talk will provide an introduction to basic concepts of MM/PC.  Plasma-based MMs and PCs will then be discussed.   The main discussion of the talk will be on the computational modeling of plasma-wave interactions in the MM/PC context.  We will present details of the modeling approach and examples of plasma tuned MM/PC wave interactions and plasma breakdown in a resonant all-dielectric structure.

Dr. Laxminarayan Raja is Professor in the Department of Aerospace Engineering and Engineering Mechanics at The University of Texas at Austin.  He holds the Robert L. Parker Sr. Endowed Professorship in Engineering.  He has a Ph.D in Mechanical Engineering (UT-Austin), M.S. in Nuclear Engineering (Texas A&M), and a B. Tech in Aerospace Engineering (IIT-Madras). 

Dr. Raja’s research is in the area of low-temperature, non-equilibrium, plasmas.  His research emphasizes both fundamental studies of plasma phenomena and the study of plasma applications in spacecraft electric propulsion, aerodynamic flow control, and materials processing.  Current research topics include 1) plasma-based metamaterials and photonic crystals, 2) plasma flow control, 3) plasma reforming of hydrocarbon fuels, 4) plasma combustion ignition, 5) semiconductor-process plasmas.  The above research is conducted primarily through computational modeling involving multidimensional chemically reactive plasma models and particle models.  His research is is largely based on the use high-performance computing approaches to address the computational modeling problems of interest.  The research has been funded by the National Science Foundation (NSF), Air Force Office of Scientific Research (AFOSR), Army Research Office (ARO).

Dr. Raja teaches in the area of fluid mechanics and plasma dynamics and has taught undergraduate and graduate classes in these areas at The University of Texas at Austin.

Dr. Raja received the prestigious National Science Foundation CAREER award in 2001.  He serves on the AIAA Plasma Dynamics and Lasers (PDL) Technical Committee and was the Technical Program Chair for the AIAA SciTech 2014 PDL meeting held in National Harbor, Washington DC in Jan 2014.   He is was the Secretary for the 65th Gaseous Electronics Conference of the American Physical Society held in Austin, Texas in Oct. 2012.