Self-compression leads to laser pulses below one femtosecond
A new research paper in Nature Photonics has been published.
A team of IMPRS-APS scientists at the Max Planck Institute of Quantum Optics in collaboration with the University of Lille and the Max Planck Institute for the Science of Light (MPL), have guided ultrashort laser pulses to compress themselves below one femtosecond, and directly recorded their electric field.
This gives a simple way to make attosecond pulses with spectral content from the near-infrared to the deep-ultraviolet (DUV), and resolve the electric field as it oscillates at frequencies significantly higher than 1 petahertz. The waveforms that emerge are dominated by a single half-cycle of the oscillating light field, trailed by a so-called resonant dispersive wave of DUV light. Our former graduate student Amelie Heinzerling performed the experiment during her PhD studies at IMPRS-APS in the research group of Nicholas Karpowicz, which she successfully completed in 2024. By focusing a 3 femtosecond pulse in a hollow-core fiber filled with helium gas, she could control the balance between linear and nonlinear optical propagation effects to achieve soliton self-compression. The pulse continuously shortened, broadening its spectrum, until its trailing edge became so sharp that it emitted an intense ultraviolet wave, right before the end of the fiber.
Measuring such a rapidly-oscillating electric field is not easy. Using nonlinear photoconductive sampling in a new spectral regime, she could simultaneously show that the technique works in the DUV, and measure the temporal structure that emerged from the fiber.
This new source of intense attosecond pulses and ultrashort DUV pulses, combined with electric field metrology, are the foundation of a new direction for attosecond physics: finding hints of fast dynamics carried by subtle changes in the waveform of light.
Original publication:
Amelie M. Heinzerling, Francesco Tani, Manoram Agarwal, Vladislav S. Yakovlev, Ferenc Krausz & Nicholas Karpowicz
Field-resolved attosecond solitons
Nature Photonics, 13 June 2025