Lasers, Terahertz light and more

Prof. Dr. Clara Saraceno, Ruhr-Universität Bochum

Ultrafast lasers are coherent light sources producing pulses with femtosecond duration (10–15 s) and – during this short time – to generate powers routinely exceeding the gigawatt (109 W) level. To put these parameters into perspective: a femtosecond is
to a second what a hair width is to the distance between the earth and the sun; and a gigawatt is the equivalent power produced by 1000 nuclear power plants – and this can be nowadays routinely achieved at the table-top of most ultrafast laser labs. The correspondingly extremely high intensities reachable in these very short timescales are comparable to the forces binding atoms to electrons and are thus an incredibly powerful tool to understand and modify the properties and processes involved in all states of matter spanning all states, liquid, solid, gas, and plasma, and all scales, nano, meso, and macro. This makes the application fields of ultrafast lasers extremely wide: they allow us on the one hand to process and functionalize virtually any material; and on the other hand, to understand the dynamics of the smallest bricks of our universe. They also enable us to reach extreme pressure and temperature conditions comparable to those present in stars, and to routinely access material nonlinearities to generate inaccessible “colors” in our spectrum – from X-rays to terahertz (THz). In this presentation, we will give an overview of the immense possibilities open by lasers and more particularly ultrafast lasers. We will focus on the generation of powerful Terahertz light, and its applications in spectroscopy – one example of areas currently fuelled by advances in laser technology–and will present future directions and challenges in laser 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.

Prof. Saraceno’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.

She 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), an ERC Starting Grant (2018) and the SPIE Harold E. Edgerton Award for High-speed Optics (2024). She was elected Fellow of Optica (formerly the Optical Society) in the 2022 class.