Ultrashort Molecules of Light – From internal Interactions to external Control (Fintec)

• Applicant: Professor Dr. Georg Herink
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas ; Experimental Condensed Matter Physics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 461131168

Ultrashort pulses from modelocked oscillators form the basis of ultrafast science. Advanced laser applications rely on composing, modulating and manipulating complex pulse patterns providing frequency-swept excitation, low-noise detection or tailored light-matter interactions. Yet, femtosecond multi-pulses and complex dynamic sequences are being reported for virtually every modelocked source and the underlying physics currently present a central theme in the active field of microresonators, ranging from phenomena of multi-pulse modelocking, multi-frequency-comb generation or “soliton crystallization”. Still, the dynamics of multi-pulse behavior even in macroscopic mode-locked cavities remain barely accessed, understood nor practically exploited. Recently, however, we could experimentally demonstrate rapid all-optical and deterministic control of femtosecond pulse sequences for the first time - an observation that bears the potential for fundamentally new realizations of ultrafast spectroscopy and nonlinear imaging. Key findings are currently not predicted from established models - such as temporal separations of bound pulses, phase relationships, pattern stability and optimal means of their control - and applications are essentially unexplored. Contrary to microresonators, modelocked lasers admit time-resolved access to femtosecond binding separations on the natural timescale of the oscillator, the single roundtrip, by virtue of recently introduced real-time spectral detection.In this project, we plan to employ our previously introduced real-time spectroscopy to entangle dynamic soliton interactions in mode-locked oscillators synchronous to rapid external perturbations. The experimental approach allows for tracking bound-state motion with femtosecond resolution on a wide range of timescales from the single-shot to the millisecond range. Specifically, our latest experimental data reveal that impulsive stimulation of coherent optical phonons present a key driver of the interaction between temporal solitons. Thus, we plan to investigate the impact of Raman stimulation and feedback onto multi-soliton states. Particulary, we utilize fast external modulations of the pump power on the one hand, and ultrafast injection of single solitons into the cavity on the other hand. Guided by numerical simulations, we want to resolve the underlying interaction mechanisms and explore future capabilities to deterministically control multi-soliton motion. Harnessing soliton interactions may directly contribute to a novel class of ultrafast instruments providing unprecedented speed, flexibility and sensitivity via multi-pulse pattern generation for applications in spectral Terhahertz (THz) imaging, stimulated Raman scattering (SRS) microscopy, pump/probe spectroscopy and rapid schemes of coherent control. As a proof-of-concept application, we plan to demonstrate rapid tuning of Terahertz pulses for dual-color imaging via modulated soliton pairs.

• DFG Programme: Research Grants
• Major Instrumentation: Real-Time Gigahertz Oscilloscope
• Instrumentation Group: 6210 Speicheroszilloskope