2023/07/03 by Dimitar Popmintchev, Popmintchev, Dimitar, Aref Imani +27
Physics and Astronomy · #Advanced Fiber Laser Technologies #FOS: Physical sciences #Laser-Matter Interactions and Applications #Laser-Plasma Interactions and Diagnostics #Optics (physics.optics)
paper · pdf · doi:10.48550/arxiv.2307.01182
openalex publication_date 2023/07/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
We demonstrate a novel technique for producing high-order harmonics with designer spectral combs in the extreme ultraviolet-soft X-ray range for resonance applications using spectrally controlled visible lasers. Our approach enables continuous tunability of the harmonic peaks while maintaining superb laser-like features such as coherence, narrow bandwidth, and brightness. The harmonics are conveniently shifted towards lower or higher energies by varying the infrared pulse parameters, second harmonic generation phase-matching conditions, and gas density inside a spectral-broadening waveguide. In the time domain, the X-rays are estimated to emerge as a train of sub-300 attosecond pulses, making this source ideal for studying dynamic processes in ferromagnetic nanostructures and other materials through resonant multidimensional coherent diffractive imaging or other X-ray absorption spectroscopy techniques. Moreover, the visible driving laser beams exhibit an ultrashort sub-10 fs pulse dues to nonlinear self-compression with a more than 30-fold enhancement in peak intensity that also extends the tunability of the linewidth of the harmonic combs.