Turning up the THz frequencies for molecular fingerprinting

Researchers from the group of Prof. Krausz, including our doctoral candidate Max Koch, have advanced molecular fingerprinting into the THz range.

Researchers from the group of Prof. Ferenc Krausz have extended molecular fingerprinting deep into the THz regime. The THz waves open up new window into molecular dynamics that could help reveal diseases much earlier than symptoms appear. The work, led by former group member Dr. Daiki Okazaki and co-authored by our PhD candidate Max Koch, has been published in Optics Express in the paper “1-THz-to-mid-infrared field-resolved spectrometer driven by a Cr:ZnS oscillator”. 

Molecular fingerprinting offers a promising approach for detecting diseases at an early stage. By irradiating blood samples with an ultra-short laser pulse and analyzing the resulting optical response, the technique captures a detailed molecular signature, the “molecular fingerprint", that reflects the sample’s molecular composition and dynamic processes. These fingerprints – analyzed with the help of artificial intelligence – could reveal subtle biochemical changes associated with an early onset of diseases, long before any symptoms appear. 

Until now, molecular fingerprinting was limited to the mid-infrared regime. By employing organic nonlinear crystals, the team was able to overcome this limitation and demonstrate the generation and detection of broadband THz pulses spanning from one to 39 THz (7.7 to 300 micrometers). “If you want to feel more of your music, you turn up the bass,” Max explains. “If you want biomolecules to feel more of your laser, you turn up the THz frequencies.”

The THz spectral range is particularly valuable because longer-wavelength light couples to collective molecular motions, such as backbone vibrations, large-scale structural fluctuations, and intermolecular interactions in solution, that are invisible to conventional infrared spectroscopy. Accessing these modes opens up a whole new array of possibilities for studying whole-molecule arrangements and structural flexibility, with potential implications for early disease detection.  

Max is continuing Daiki´s work in the team. In his PhD, he is pushing time-domain THz spectroscopy by rethinking the detection of the THz pulses with organic crystals. Once validated through measurements in relevant organic samples, he plans to apply his collected knowledge to the analysis of patient´s blood sample. "I am already looking forward to the day where I can test the first blood sample with my spectrometer, seeing all the hard work coming to fruition,” Max says.

Original publication:

1-THz-to-mid-infrared field-resolved spectrometer driven by a Cr:ZnS oscillator

Daiki Okazaki, Max Koch, Mojtaba Aghakasiri, Philipp Steinleitner, Wolfgang Schweinberger, Dionysios Potamianos, Yang Gui, Aleksandar Sebesta, Behnam Jahedi Abbasvand, Vipulkumar Bhaliya, Shigeki Tokita, Ferenc Krausz, and Alexander Weigel

Optics Express 34, 28928-28942 (2026)

Pictures: Nina Beier