Helicity Gets a New Twist: Straightforward Production of Polarization Sculpted Attosecond High-Harmonic Waveforms for Chiral Spectroscopies and Imaging
February 13th, 2018 KEVIN M. DORNEY University of Colorado Boulder

Since its discovery over thirty years ago, high-harmonic generation (HHG) has matured into a reliable, table-top-scale source of coherent, extreme ultraviolet (EUV) and soft X-ray radiation with pulse durations allowing for direct observation of nature’s fastest dynamical processes. The high brightness and full spatiotemporal coherence of HHG-based light sources has enabled new paradigms in nanoscale imaging, ultrafast metrology, and atomic, molecular, and materials spectroscopy, to name a few. The success of HHG as a versatile source of high-frequency radiation is a direct result from the laser-driven nature of the upconversion process; which allows for direct control over the full spatial, spectral, temporal, and (until recently) polarization properties of the emitted light. In particular, the recent re-discovery of circularly polarized HHG (CPHHG) has resulted in a renaissance of polarization-sculpted attosecond light sources capable of observing element-specific chiral dynamics. In this talk, I’ll discuss our recent progress on enhancing and extending the capabilities of CPHHG; ranging from fundamental light-science to novel chiral spectroscopies and imaging modalities. First, we show straightforward techniques for actively and passively controlling the structure of the underlying attosecond pulse trains; generating wavetrains of arbitrary polarization state and single-helicity CPHHG spectra and thus circularly polarized attosecond pulses. In a separate, but related thrust, we demonstrate a novel CPHHG source based on phase-locked, orthogonal HHG pulse pairs that enables chiral materials spectroscopy and imaging, without the need for expensive and lossy EUV and soft x-ray optics. These advances not only further the basic understandings of CPPHG, but also extend the capabilities and robustness of CPHHG-based light sources for attosecond spectroscopies of exotic systems such as spintronic devices, magneto-optical memory materials, and chiral molecular dynamics.

Seminar, February 13, 2018, 12:00. ICFO’s Seminar Room

Hosted by Jens Biegert