Terahertz science and technology:
A passion for long waves
During the past 25 years science and technology in the terahertz spectral range of the electromagnetic spectrum has been revolutionized. In this inaugural lecture I will discuss technology and applications within spectroscopy and sensing in the terahertz range in a historical perspective, and outline current and future research at DTU in this exciting area.
Professor Peter Uhd Jepsen received the MSc. Degree in physics from Odense University in 1994, and the PhD Degree in Natural Sciences (Physics and Chemistry) from Aarhus University in 1996. His PhD work was focused on fundamental properties of terahertz-frequency wave generation and detection and included the first demonstration of free-space electro-optic sampling, a technique which since then has become one of the few standard techniques for detection of ultrashort terahertz (THz) signals.
In the period 1996-2004 Peter Uhd Jepsen was at Freiburg University, Germany, where he built up a small research unit focused on terahertz spectroscopy of condensed matter systems. During this period he was among the first to document fingerprint THz vibrational modes in a wide range of solid-state materials such drugs, explosives and pharmaceutical compounds. This work lead to the award of the Habilitation and Venia Legendi Degrees from Freiburg University in 2002/2003.
In 2005 Peter Uhd Jepsen moved to the Technical University of Denmark, and started a THz research team at COM, now DTU Fotonik. Since 2008 he has been Head of the Terahertz Technologies & Biophotonics research group which now focuses on advanced, time-resolved THz spectroscopy, high-intensity THz pulses, nonlinear THz spectroscopy, and THz imaging/sensing.
Peter Uhd Jepsen has published >60 original experiment-based research papers which have attracted >2250 citations (H-index 24). He was awarded Elektrofondets Elektropris in 2007, and a guest professorship at Osaka University in 2008/2009. He is Associate Editor for Optics Express, Topic Editor for IEEE Transactions on Terahertz Science and Technology, and on the Editorial Board of Journal of Infrared, Millimeter and Terahertz Waves.
Peter Uhd Jepsen leads a team of passionate researchers exploring the THz frequency range. The team pushes experimental optical technologies in this exciting frequency range towards higher bandwidth, faster response time, and higher intensities. One special focus area is the development of nonlinear technology in the THz range. Similar to the huge impact that nonlinear optics has had on present-day telecommunication systems, it can be expected that nonlinear optics will have a disruptive impact on future technologies in the terahertz range.
The THz technology available at DTU allows a glimpse into the first femtoseconds following optical excitation of a material. The group explores this technology for investigations of ultrafast photodynamics of material systems such as novel solar cells, graphene, nonlinear glasses, and liquids.
Light in the THz range is also known for its capability to see through a wide range of materials. The group uses this capability for the development of novel non-destructive testing and evaluation methods (NDT/NDE) which can be employed in very diverse fields, including industry, safety and security, and cultural heritage conservation and restoration.