Phd defense by Christian Buhl Sørensen (Online event)
Compact array emitters for terahertz spectroscopy and imaging
23.03.2020 kl. 14.30 - 16.00
The PhD defense will be streamed live on Youtube here
Terahertz radiation is a useful tool for many security and material science applications, but the technique’s most distinct drawback is the absence of intense compact sources. This thesis presents significant steps toward an integrated array of discrete antennas, by employing an etched substrate lens array with an array pitch similar to the free space wavelength. Key results include a peak 10 dB increase in the SNR near 0.5 THz, and a doubling of the power between 0.4 THz and 0.75 THz. It was further demonstrated that the echoes from the flat substrate interfaces were reduced.
Fundamental work on the spatial emission profile of terahertz radiation from two-color air plasma filaments has been characterized. This generation method is widely adopted in high-field THz research. It is common practice to apply a silicon filter to remove forward-propagating waste light from the process, but it will be dmonstrated that significant care is required in proper filter selection. When using a silicon filter, a conical emission pattern was induced, but when the silicon filter was preceded by a high bandgap ceramic filter, a Gaussian-like emission pattern was observed. The observed conical emission pattern was consistent with previous reports claiming an intrinsic conical emission profile from similar plasma filaments.
- Associate professor Vladimir Popok (chairman), Department of Materials and Production, Aalborg University, Denmark
- Professor Peter Uhd Jepsen, DTU Fotonik, Denmark
- Professor Daniel Mittleman, Brown University, USA
- Associate professor Esben Skousen, Department of Materials and Production, Aalborg University
The PhD defense will be hosted by Moderator Vladimir Popok . The lecture constitutes a 45 minutes presentation by Christian Buhl Sørensen followed by a short break and a discussion session with questions from the opponents and the auditorium.
Department of Materials and Production