IEM Distinguished Lecturers Seminar: High-power ultrafast THz moves into the Terahertz domain


Event details

Date 13.10.2023
Hour 13:1514:00
Speaker Prof. Clara Saraceno
Photonics and Ultrafast Laser Science Group, Electrical Engineering and Information Technology, Ruhr University Bochum, Germany
Location Online
Category Conferences - Seminars
Event Language English
The seminar will take place in ELA 2 and will be simultaneously broadcasted in the main auditorium in Neuchâtel Campus (MC A1 272).

Coffee and cookies will be served at 13:00 before the seminar, in front of the two auditoriums. 


Terahertz Time Domain Spectroscopy (THz-TDS) has become a ubiquitous tool in many scientific fields and is also increasingly deployed in industrial settings. While these systems become more and more mature, efficient and lab-based THz generation methods combining broad bandwidth and high dynamic range (e.g., as provided by high THz average power and correspondingly high repetition rate) remain rare. Most industrial THz-TDS systems make use of semiconductor-based photoconductive emitters and receivers. These systems offer record-high dynamic range operation at very high repetition rates of hundreds of MHz, and the corresponding emitters provide high conversion efficiencies with low power excitation, driven by compact ultrafast fiber-lasers. For applications where strong-fields are desired, the most commonly used technique is optical rectification in nonlinear crystals, for instance zinc telluride (ZnTe), gallium phosphide (GaP), lithium niobate (LiNbO3) or organic crystals (e.g., BNA, DAST, DSTMS). Whereas all these techniques have seen continuous performance progress in the last few years driven by different application fields, their average power has mostly remained low. A promising yet poorly explored route is simply to increase the average power of the driving lasers using state-of-the-art, high-average power ultrafast Yb-gain based lasers providing multi-100-W to kilowatt average-power levels as excitation sources, which are increasingly available both in laboratory setting and commercially. This new excitation regime for THz generation in various schemes has become an active area of research in the last few years, and current results have allowed to reach power levels in the THz domain in the multi-ten to multi-hundred milliwatts in different repetition rate regions – which was previously restricted to accelerator facility-type THz sources. This progress opens the door to a multiplicity of new and old research areas to be re-visited. In this presentation, we review recent progress in the generation of high-average power THz for TDS. We will present the state-of-the-art of high-power ultrafast laser sources with potential for driving THz sources, current technological challenges in scaling THz average power, and applications areas that could potentially benefit from these novel lab-based sources.

Clara Saraceno is a full professor at the Ruhr University Bochum, Germany. She was born in 1983 in Argentina.  In 2007 she completed a Diploma in Engineering and an MSc at the Institut d’Optique Graduate School, Paris France. She first worked as an engineering trainee at Coherent Inc. Santa Clara, California, until 2008. She then completed a PhD in Physics at ETH Zürich in 2012 where she carried out research on high-power ultrafast disk lasers. From 2013-2014, she worked as a Postdoctoral Fellow at the University of Neuchatel and ETH Zürich, Switzerland, where she worked on high-flux XUV generation via high harmonics generation. In 2016, she received a Sofja Kovalevskaja Award of the Alexander von Humboldt Foundation and became Associate Professor of Photonics and Ultrafast Science in the Electrical Engineering Faculty at the Ruhr University Bochum, Germany, followed by a full professorship in the same university since 2020.

Research Interests: Clara’s research interests are in the development of high-power ultrafast laser systems and their application in driving secondary sources via nonlinear optics. One of her current main research areas is THz technology and spectroscopy, where her group aims to achieve high average power level broadband THz radiation.

Professional Activities and Awards: Clara has co-authored more than 60 journal publications in highly ranked journals and given numerous invited, keynote and plenary talks at international conferences. She served in numerous committees for international conferences, including general chair for CLEO US 2023, ASSL 2022 and Ultrafast Optics Conference in Argentina in 2023. She was previously an associate editor for Optics Express in 2019 – 2021 and is now associate Editor at APL Photonics.
Clara has received a number of prizes and awards including the ETH Medal for Outstanding PhD thesis (2013), the European Physical Society Quantum Electronics and Optics Division PhD prize in applied aspects (2013), the Sofja Kovalevskaja Award of the Alexander von Humboldt (2016) and an ERC Starting Grant (2018). She was elected Optica Fellow in the 2022 class.