Biography:

Shriganesh S. Prabhu received the B.Sc. degree in physics from Mumbai University, Mumbai, India, the M.Sc. degree in physics from Pune University, Pune, India, and the Ph.D. degree in physics from Tata Institute of Fundamental Research (TIFR), Mumbai, India. He completed his Postdoctoral work with Emory University, Atlanta, GA, USA. In 1998, he joined TIFR as a Fellow. He is currently an Associate Professor of physics with the Department of Condensed Matter Physics and Material Science, TIFR. He initially worked on ultrafast phenomena in semiconductors and heterostructures using ultrashort lasers (picosecond), and later he worked on THz spectroscopy using femtosecond lasers. He has authored or coauthored many papers in international journals, conferences, and several articles (popular and technical) in many magazines and few chapters in books. His research interests include ultrafast carrier dynamics in materials using THz spectroscopy, developing THz technology, THz optical components, such as lenses, wave plates, filters, metasurfaces or metamaterials, THz-waveguide-based chemical and biochemical sensors, and THz source-detector devices using plasmonic antenna designs.

Lecture: "Tera-Hertz (THz) Spectroscopy with Applications to Materials study"

Terahertz (THz) band of the electromagnetic wave spectrum offers lots of opportunities to study various phenomena hitherto unknown and unexplored. THz spectroscopy is a contact- free, non-destructive technique to measure photoconductivity on a sub-ps time scale. These measurements can be performed on single crystals, compound materials, sintered pellets and thin films grown on insulating substrates. The ultrafast time resolution offered by THz spectroscopy technique enables us to study trapping dynamics and reveals what physical processes limit the carrier lifetime in the material under study. The Static THz Spectroscopy, called Time Domain Spectroscopy (THz-TDS) gives information about the low frequency vibrrations in a material. Additionally, complex conductivity can be measured at THz frequencies using THz-TDS. THz-conductivity and photoconductivity shed light on scattering effects inside the material. The interpretation of THz-results is more challenging than other direct spectroscopies since they are well established. In this tutorial we will introduce and familiarize the students with the main THz TDS techniques used to explore materials and we will later explain OPTP (Optical Pump-THz Probe) technique to study temporal dynamics. We will illustrate how carrier lifetimes can be extracted from OPTP measurements. We will explain through the process of extracting n, k with accurate photoconductivities from time resolved THz spectroscopy measurements. We will then explain our Metamaterials research and Near Field THz results and what information and insight can be obtained using these state of the art techniques.