News
Welcome to XTreme Photonics Labs
Our research program focuses on the dynamic visualization of ultrafast electronic processes of matter with light. To this end, we develop and utilize intense, ultrashort, laser pulses whose field-waveform is controlled with sub-cycle precision. Under such fields, the interaction of laser and matter becomes extremely nonlinear and offers the possibility to devise new methodologies of probing the fundamental properties of electrons in a wide range of materials ranging from atoms to complex solids. Understanding and controlling the microcosm at the level of electrons may turn essential in future photonic and electronic technologies whose building blocks size is gradually reducing from the mesoscopic to the atomic and molecular scales.
News
Santanu Mandal defends PhD
Rostock, Germany: Santanu Mandal defended his PhD thesis - Single-cycle probing of the dynamics of the insulator-to-metal phase transition in VO2.
Santanu’s thesis pioneers the use of ultrashort, high-power femtosecond laser pulses to probe two fundamental questions in condensed matter and strong-field physics. The first part resolves the mechanism of the insulator-to-metal transition (IMT) in monoclinic M1 vanadium dioxide (VO₂). With single-cycle visible light pulses lasting just 2.4 fs, the research shows that photoexcitation first drives VO₂ into an excited rutile metallic state. Subsequent electron and lattice dynamics play out on sub-100 fs timescales, revealing that the vanadium–vanadium bond rearrangement is stepwise and highly anharmonic—contradicting theories attributing IMT to purely electronic processes.
Its second part develops a high harmonic generation (HHG) platform for solids, enabling precise, broadband detection of nonlinear optical responses. Studies across crystals like diamond, MgO, and fluorides reveal that the transition to nonperturbative nonlinear optics cannot be captured by the standard Keldysh parameter but fits better with an effective potential model.
The thesis thus provides ground-breaking, phase-resolved visualization of ultrafast phase transitions and fundamentally advances experimental methods for strong-field studies in solids, laying a robust foundation for probing correlated oxides and complex light–matter interactions in future research.
Farewell to Hee-Yong Kim: From Attoseconds to Semiconductors
After 11 years in our group, Hee-Yong is off to his next adventure at KLA Semiconductors!
He joined us as a master’s student, tackled a PhD on attosecond field emission, and then stayed on for three more years as a postdoc - driving experiments forward, solving problems no one else wanted to touch, and somehow keeping both his plants and his old laptops alive in the process.
While we’ll miss having him around, we’re excited to see what he builds (or repairs!) next at KLA. If history is any guide, it’ll work beautifully, even if it’s running on a laptop from the early 2000s. XTreme Photonics Labs wishes Hee-Yong every success in his next chapter!
The Physicist from Crete Who Excels Internationally
Mister Pi und der 2,5-Millionen-Preis
(Click on the image to view the Süd Stern newspaper report)
