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Abstract The circular dichroism (CD) of photoelectrons generated by near-infrared (NIR) laser pulses using multiphoton ionization of excited He+ions in the 3p(m= +1) state is investigated. The ions were prepared by circularly polarized extreme ultraviolet (XUV) pulses. For circularly polarized NIR pulses co- and counter-rotating relative to the polarization of the XUV pulse, a complex variation of the CD is observed as a result of intensity- and polarization-dependent Freeman resonances, with and without additional dichroic AC-Stark shifts. The experimental results are compared with numerical solutions of the time-dependent Schrödinger equation to identify and interpret the pronounced variation of the experimentally observed CD.
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Constant intensity conical diffraction in discrete one-dimensional lattices with charge-conjugation symmetry
We engineer anomalous conical diffraction (CD), occurring in discrete one-dimensional lattices with charge-conjugation symmetry when an exceptional point is in the proximity of the modes that compose the initial excitation. The evolving waveform propagates ballistically, acquiring aconstantintensity profile within the boundaries of the spreading cone. The linear increase in the total intensity along the propagation direction is responsible for the generation of constant intensity CD.
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- Award ID(s):
- 1641109
- PAR ID:
- 10133390
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Letters
- Volume:
- 45
- Issue:
- 1
- ISSN:
- 0146-9592; OPLEDP
- Format(s):
- Medium: X Size: Article No. 101
- Size(s):
- Article No. 101
- Sponsoring Org:
- National Science Foundation
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