Feature

New Techniques in Wideband Terahertz Spectroscopy

Ajay Nahata and Tony F. Heinz, Columbia University, New York, N.Y.

In recent years, remarkable progress has been made in the development of spectroscopic capabilities for coherent terahertz (THz) measurements. This spectral region is one of great interest because of the abundance of excitations in molecular systems and condensed media. It also represents a region in which the dielectric properties of materials are of critical importance for high frequency electronics and optoelectronics. A key ingredient to the significant advances in this field is the development of broadband, optically driven sources and detectors of terahertz radiation. The ready availability of laser pulses with durations of ~10 fsec suggests the potential for extending the bandwidth of coherent spectroscopy to significantly higher frequencies. By using materials with an instantaneous nonlinear optical response for both emission and detection, we may be able to capture much of this enormous bandwidth.