Location: Auditorium, ECE MP Building
ECE faculty colloquium
Date: 27 September 2019 (Friday)
Time: 4pm (coffee served at 3:45pm)
Venue: MP auditorium, ECE dept. (behind ECE main building)
Speaker: Varun Raghunathan, ECE dept.
Title: Resonant nonlinear optics with sub-wavelength dielectric structures
Abstract: Sub-wavelength sized dielectric structures made of high refractive materials are attractive as wavelength-dependent scatterers in the form of isolated units and as closely spaced arrays. Arrays of sub-wavelength scattering units can be used to build frequency-selective meta-surfaces which can be used to locally enhance electric-fields of the incident optical waves. Such resonant enhancement in optical fields can be used for multi-fold enhancement of nonlinear optical effects in these structures. This has motivated the study of nonlinear optical effects in artificially engineered dielectric surfaces to realize ultra-thin wavelength converters as a replacement for often bulky nonlinear optical crystals. This talk will give a quick introduction to nonlinear optics and scattering from dielectric nanostructures, followed by the design, electromagnetic simulations, fabrication and experimental characterization of silicon and silicon-nitride based sub-wavelength guided-mode resonance structures for enhancement of third-harmonic generation and four-wave mixing processes.
Biography: Varun Raghunathan is an Assistant Professor in the ECE department at IISc. His research group works in the areas of nonlinear optical microscopy studies of nanostructures and biological samples, and indoor visible light communication.