Ultra-fast YBa2Cu3O7-x direct detectors for the THz frequency range

Infrared radiation up to terahertz wavelengths is extensively used in many different research areas such as spectroscopy, wireless communication and cosmology. In recent years, the development of electron storage rings emitting ultra-short, brilliant pulses in the terahertz frequency range made significant progress. For the analysis and optimization of the pulsed terahertz radiation generated by electron storage rings or other pulsed sources, ultra-fast detectors are required which are able to resolve picosecond dynamic processes directly in the time domain. In this thesis, a new direct terahertz detector technology based on the high-temperature superconductor YBa2Cu3O7-x has been developed which opens new routes in the analysis of ultra-fast, picosecond time-domain processes over a broad terahertz frequency range (0.07 - 2 THz) with a wide dynamic range of more than 30 dB. This was successfully demonstrated by the recording of a 17 ps wide coherent synchrotron radiation terahertz pulse at ANKA, the electron storage ring of the Karlsruhe Institute of Technology. Furthermore, for the first time clear evidences for a vortex-assisted detection mechanism in YBa2Cu3O7-x thin-film detectors for pulsed photon excitations below the superconducting energy gap were found which are presented and are discussed in this work.