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A: Fachverband Atomphysik

A 2: Attosecond physics I

A 2.2: Vortrag

Montag, 9. März 2020, 11:30–11:45, f107

Generation of elliptically polarized high-harmonics: towards chiral isolated attosecond pulses — •Ulrich Bengs and Nickolai Zhavoronkov — Max-Born Institut Berlin

High harmonic generation (HHG) is the fundamental process underlying the generation of attosecond pulses, which allow to study the electronic structure of matter on its natural timescale. However, until recently, HHG was limited to linear polarization. A promising way to overcome this limitation is offered by bicircular HHG [1] which is known to produce circularly polarized pairs of harmonics with opposite helicity. We demonstrate an implementation of bicircular HHG with few-cycle driving fields consisting of a 5 fs, circularly polarized pulse centered around 800 nm and its counter-rotating second harmonic with 8 fs duration. Utilizing the propensity rules that govern the contrast between harmonics of opposite helicity [2, 3] we are able to shape the harmonic spectrum to be dominated by harmonics of only one helicity over a broad spectral range and measure the ellipticity by means of XUV-polarimetry showing, that the harmonics are indeed elliptically polarized. Additionaly, we report the generation of a continuous spectrum spanning 32-55 eV, which lays the foundation for isolated attosecond pulses with elliptical polarization, making the technique a powerful tool in the development of a lightsource for ultrafast chiral-sensitive studies.

[1] D.B. Milosevic et al, Phys. Rev. A 61, 063403 (2000)

[2] A. Jimenez-Galan et al, Phys. Rev. A 97, 023409 (2018)

[3] N. Zhavoronkov and M. Ivanov, Opt. Lett. 42, 4720-4723 (2017)