Terahertz Time-Domain Spectroscopic Polarimetry: The Pursuit of Terahertz Optical Activity

Date(s) - Mar 31 2015
11:00 AM - 12:00 PM

Shasta Room, Bldg. 40, Room 361


Dan Aschaffenburg

Department of Chemistry, Yale University

Terahertz (THz) time-domain spectroscopy is a powerful tool for studies in the far-infrared. The limits and capabilities of the technique are constantly being pushed further and in new directions. For instance, while vibrational circular dichroism (VCD) is becoming a standard tool for studying molecular chirality in the infrared, the goal of our research is to extend this analysis into the THz region of the electromagnetic spectrum. We have developed a technique for measuring the polarization state of all spectral components in a broadband THz pulse using a continuously rotating polarizer and standard THz time-domain spectrometer. Measuring a broadband THz VCD spectrum of a molecular system is a challenging task given that the ratio of VCD to linear absorption is on the order of 10‑4 to 10‑6 in the infrared. However, unlike molecules, metamaterials can be designed to have strong optical activity in the far-IR and can provide ideal structures for developing THz VCD techniques and data analyses. We are current studying metamaterials that are comprised of arrays of Archimedean spirals.