The Ultrafast Infrared and Terahertz Science group works with generation, handling, manipulation and spectroscopic applications of femtosecond ultrafast light pulses in the infrared and terahertz part of the electromagnetic spectrum. Our interests are within ultrafast nonlinear optics such as soliton formation and supercontinuum generation motivated by development of novel infrared ultrafast light sources, and using these pulses for linear and nonlinear spectroscopy of semiconductors, metals, crystalline materials and liquids. We use ultrafast terahertz pulses for imaging in industrial as well as cultural heritage applications.
Light pulses are a perfect tool for studies of ultrafast dynamic processes in nature. In our laboratories state-of-the-art femtosecond laser technology allows us to generate laser pulses that are short enough to resolve these processes, broadband enough to cover a wide range of frequencies in one go, and with the right wavelength to study dynamics at their true resonance frequencies. The majority of these wavelengths lie in the infrared and terahertz range, unfortunately in ranges where femtosecond laser technology is not very efficient yet.
We have therefore implemented state-of-the-art technology to convert the ultrafast near-infrared laser pulses to the mid to far-infrared and terahertz range, and are continuously conducting research in new improved generation and manipulation methods, as well as new spectroscopic techniques for coherent, phase-sensitive spectroscopy and imaging across the spectrum.
The Ultrafast Nonlinear Optics team works with improved frequency conversion processes exploiting solitons, in particular in quadratic nonlinear crystals and hollow core gas-filled fibers, which allows to generate single-pumped tunable broadband pulses in the mid-infrared and octave-spanning energetic mid-infrared supercontinua.
Visit the webpage for the Ultrafast Nonlinear Optics team for more information about us.
The Terahertz team uses ultrashort pulses of terahertz radiation to study the behavior of materials on a very fast time scale – vibrations in covalently bonded molecules in crystalline environments, motion of electrons in semiconductors, and behavior of electrons in aqueous liquids. Terahertz waves are useful for nondestructive analysis in advanced materials, including modern composites and layered structures, but also in historically important cultural heritage artifacts such as easel paints and wooden panels. We are developing intense, pulsed THz sources for nonlinear spectroscopy, with special emphasis on energetic couplings and other nonlinearities in the vibrational response of molecular systems and exploration of the electrostatic limit of nonlinear optics in metals, exemplified by ultrafast THz-induced electron emission from metal surfaces.
Visit the webpage for the Terahertz team or our website terahertz.dk to read the fresh news and learn about our research projects.