Using circuitry which is driven by ultrafast repetitive laser pulses, Dr. Grischkowsky has developed a complete optoelectronic THz beam system which can generate and detect 200 fsec pulses of freely propagating THz radiation with a time resolution of 65 fsec. Based on this optoelectronic THz beam system, he has pioneered the field of THz time- domain spectroscopy (TDS). In this proposal he seeks to explore the limits of THz-TDS with respect to both sensitivity and dynamic range. Transmission measurements requiring extreme dynamic range will be performed on samples such as semiconductors and normal and superconducting metal films as well as hot samples, flames and plasmas. The PI further plans the precise measurement of coherent THz transients from molecular vapors and the direct observation of THz propagation effects through dense vapors.
