Gouy phase shift for annular beam profiles in attosecond experiments
| Autor: | Ursula Keller, André Ludwig, Mikhail Volkov, Lukas Gallmann, Lamia Kasmi, Matteo Lucchini, Fabian Schlaepfer |
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| Rok vydání: | 2017 |
| Předmět: |
Physics
business.industry Attosecond Phase (waves) Physics::Optics 01 natural sciences Atomic and Molecular Physics and Optics Photon counting 010305 fluids & plasmas Wavelength Optics Extreme ultraviolet 0103 physical sciences Femtosecond Physics::Atomic and Molecular Clusters 010306 general physics business Beam (structure) Gaussian beam |
| Zdroj: | Optics Express. 25:3646 |
| ISSN: | 1094-4087 |
| DOI: | 10.1364/oe.25.003646 |
| Popis: | Attosecond pump-probe measurements are typically performed by combining attosecond pulses with more intense femtosecond, phase-locked infrared (IR) pulses because of the low average photon flux of attosecond light sources based on high-harmonic generation (HHG). Furthermore, the strong absorption of materials at the extreme ultraviolet (XUV) wavelengths of the attosecond pulses typically prevents the use of transmissive optics. As a result, pump and probe beams are typically recombined geometrically with a center-hole mirror that reflects the larger IR beam and transmits the smaller XUV, which leads to an annular beam profile of the IR. This modification of the IR beam can affect the pump-probe measurements because the propagation that follows the reflection on the center-hole mirror can strongly deviate from that of an ideal Gaussian beam. Here we present a detailed experimental study of the Gouy phase of an annular IR beam across the focus using a two-foci attosecond beamline and the RABBITT (reconstruction of attosecond beating by interference of two-photon transitions) technique. Our measurements show a Gouy phase shift of the truncated beam as large as 2π and a corresponding rate of 50 as/mm time delay change across the focus in a RABBITT measurement. These results are essential for attosecond pump-probe experiments that compare measurements of spatially separated targets. |
| Databáze: | OpenAIRE |
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