OSE Seminar by Professor Roman Sobolewski on Terahertz Photonics

Departmental News

Roman Sobolewski

Posted: February 10, 2024

Date: Thursday, February 22nd, 2024

Time:  12:45 PM - 1:45 PM MST

Location: CHTM, Room 103 and Zoom



The field of Terahertz (THz) science and technology is still in its infancy but has already gained a very large international interest due to its numerous applications ranging from security screening, e.g., at airports, through ultrafast communications, radioastronomy, to nonionizing biomedical spectroscopy, medical imaging and diagnostics, and industrial food quality control. The THz radiation is situated between the infrared and microwave regions in the electromagnetic spectrum with a bandwidth ranging from 0.3 to 30 THz and in conventional terms, we can talk about the “THz gap,” i.e., a region of electromagnetic radiation spectrum where it is very difficult to successfully operate “classical” either electronic or photonic devices. For even the fastest FET-type transistor structures, the THz frequency of operation is extremely high, while THz quanta have the energy much smaller than the thermal energy background at room temperature. One of the most interesting forms of THz radiation are subpicosecond in duration bursts of electromagnetic waves. These, so- called, THz transients are, typically, characterized by approx. a single picosecond time duration and a 0.1 to 6 THz spectral range. We present a novel, integrated-optoelectronics approach that combines femtosecond laser pulses with materials and devices exhibiting sub- picosecond photoresponse times. We review our current THz photonics research, aimed towards generation and subsequent detection of sub-picosecond electrical transients for time- resolved (THz-bandwidth) spectroscopy studies of novel materials, nanostructured devices, and, most recently, ex-vivo imaging of pancreatic normal and tumor tissues. Spintronic nanostructures manipulate simultaneously electron’s charge and spin and emerge as a new direction in generation of THz transients, due to their robust and simple thin-film technology, low cost, and emission of ultra-broadband signals. The inverse spin Hall effect is the core emission mechanism of THz transients from spintronic nanostructures, such as ferromagnet/heavy metal nanobilayers. Future prospects of THz photonics will complete our presentation.



Roman Sobolewski is a Professor of Electrical and Computer Engineering, Physics, and Materials Science, as well as a Senior Scientist of Laser Energetics at the University of Rochester, Rochester, NY, USA. He received his PhD and DSc (Habilitation) degrees in Physics from the Polish Academy of Sciences, in 1983 and 1992, respectively. In 2006, he was granted the State Professorship of the Republic of Poland. In 2011, he received the Spanish Government Research Scholarship and spent a semester at University of Salamanca, Spain. In 2015, he was named a Distinguished Fellow of the Kosciuszko Foundation Collegium of Eminent Scientists of Polish Origin and Ancestry. His research interests are focused on ultrafast phenomena in condensed matter, novel nanostructured spintronics materials and devices, single-photon detection and quantum communications, and on generation and detection of THz radiation transients and time-resolved THz spectroscopy. He has published over 430 peer-reviewed publications and presented over 200 invited lectures, and colloquia worldwide.