Water-window high harmonic generation with 0.8-μm and 2.2-μm OPCPAs at 100 kHz
Abstract
We compare the generation of high-order harmonics in the water window (283-543 eV) with 0.8-µm and 2.2-µm few-cycle lasers at a pulse repetition rate of 100 kHz. Using conventional phase matching with the 2.2-µm driver and what we attribute to nonadiabatic self-phase-matching with the 0.8-µm driver, photons up to 0.6 keV (2 nm) are generated in both cases. Special attention is paid to the understanding of the generation mechanism with the 0.8-µm laser amplifier system. We use the same beamline and pump laser for both drivers, which allows for a direct flux comparison at the two driving wavelengths. For photon energies around 280 eV, a 10-100 times higher flux is obtained from the 2.2-µm versus the 0.8-µm laser system in helium and neon. The crossover at which the 2.2-µm yields a higher flux compared to the 0.8-µm driver is found to be as high as 0.2 keV. Our study supports the common approach of using long-wavelength lasers in a phase-matched regime for efficient generation of water-window harmonics, but also shows that the more widespread 0.8-µm wavelength can be used to generate water-window harmonics with an efficiency close to the one of a less common 2.2-µm source. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000507267Publication status
publishedExternal links
Journal / series
Optics ExpressVolume
Pages / Article No.
Publisher
OSA PublishingSubject
LASER PULSES, SHORT-TIME PHENOMENA (LASER ENGINEERING); High harmonic generationOrganisational unit
03371 - Keller, Ursula / Keller, Ursula
08733 - Gallmann, Lukas (Tit.-Prof.) / Gallmann, Lukas (Tit.-Prof.)
Funding
200416 - High repetition rate attosecond pulse generation (SNF)
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Is supplemented by: https://doi.org/10.3929/ethz-b-000510574
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