Helicity-selective phase-matching and quasi-phase matching of circularly polarized high-order harmonics: Towards chiral attosecond pulses

Ofer Kfir, Patrik Grychtol, Emrah Turgut, Ronny Knut, Dmitriy Zusin, Avner Fleischer, Eliyahu Bordo, Tingting Fan, Dimitar Popmintchev, Tenio Popmintchev, Henry Kapteyn, Margaret Murnane, Oren Cohen

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

Phase matching of circularly polarized high-order harmonics driven by counter-rotating bi-chromatic lasers was recently predicted theoretically and demonstrated experimentally. In that work, phase matching was analyzed by assuming that the total energy, spin angular momentum and linear momentum of the photons participating in the process are conserved. Here we propose a new perspective on phase matching of circularly polarized high harmonics. We derive an extended phase matching condition by requiring a new propagation matching condition between the classical vectorial bi-chromatic laser pump and harmonics fields. This allows us to include the influence of the laser pulse envelopes on phase matching. We find that the helicity dependent phase matching facilitates generation of high harmonics beams with a high degree of chirality. Indeed, we present an experimentally measured chiral spectrum that can support a train of attosecond pulses with a high degree of circular polarization. Moreover, while the degree of circularity of the most intense pulse approaches unity, all other pulses exhibit reduced circularity. This feature suggests the possibility of using a train of attosecond pulses as an isolated attosecond probe for chiral-sensitive experiments.

Original languageEnglish
Article number123501
JournalJournal of Physics B: Atomic, Molecular and Optical Physics
Volume49
Issue number12
DOIs
StatePublished - 23 May 2016
Externally publishedYes

Keywords

  • attosecond pulses
  • circularly polarized high harmonic generation
  • phase matching
  • ultrafast chiral physics

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