Development of the photoconductive antenna-based THz pulsed spectrometer

Abstract

The methods for determining optical, dielectric and magnetic properties of different objects in terahertz (THz) range are widely used for solving various fundamental and applied problems in physics, medicine, biology and other fields. One of such methods is the THz pulsed spectroscopy, which is prospective for medical diagnostics of tissue lesions and tumors, nondestructive evaluation of materials, studying fundamental problems of condensed matter physics. Hence, there is a relevant problem of development and manufacturing the related instruments, i.e. THz pulsed spectrometers (TPS). We propose a design of TPS, which is based on a pair of photoconductive antennas (PCA) used as the THz source and the detector. It allows for measuring spectra in the range from 0.1 up to 4.5 THz. In this work, we demonstrate its scheme and discuss several problems that arose during its development. The first one is the ability to perform both reflection and transmission measurements along with a convenient switching between these modes. The second one is connected with distortion of THz spectra measured in air due to absorption of THz waves by water. This fact requires a reduction of humidity in the measurement chamber, for example, by pumping out the air (up to ~10-3 mbar). The latter poses a demand for the chamber to be sealed. The solution of the listed and some other issues made it possible to create a prototype of PCA-based TPS and to apply it for various research tasks.

Speaker

Kirill B. Dolganov
Prokhorov General Physics Institute of the Russian Academy of Sciences
Russia

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