Research Projects

Terahertz waves (100 GHz-10 THz), the electromagnetic waves located between radio waves and optical waves, have wavelengths that allow them to probe material properties not easily accessible with other wavelengths. The Terahertz Devices and Systems laboratory develops Terahertz devices based on rectifying field effect transistors as well as photoconductors for both pulsed and continuous-wave (CW)generation and detection. When operated as a source, a photomixer converts an optical signal that contains THz difference frequencies to a THz signal. In the CW case, two laser signals, differing by the THz frequency are heterodyned on the photoconductor. The absorbed laser power generates a conductance modulation at THz frequencies and at DC. The THz modulation is converted to a THz current withg the aid of a DC bias. An on-chip antenna converts the THz current to THz radiation. For pulsed operation, an optical pulse with a wide spectrum of several THz is converted to a THz pulse. The scheme can be inverted in order to serve as receiver: An antenna receives a THz wave and biases the photoconductor at a THz frequency. The insident laser beam generates a conductance modulation at the same time. Both signals are mixed, generating a DC current component that is read out. Besides development of sources and receivers we apply our outstanding devices for a range of applications, including THz spectrum analysis, photonic THz vector network analysers, spectroscopy and many more. The actual topic for the project will be extracted from ongoing projects and will be defined upon request. Almost all projects contain a practical part with hands-on in the laboratory, e.g. at an optical or THz setup or even in a semiconductor clean room.

This project is supervised by Prof. Dr. rer. nat. Sascha Preu.