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Updated: Jun 25, 2026

Direct Imaging of Laser-driven Ultrafast Molecular Rotation
Published on: February 4, 2017
Elliptically polarized high-order harmonic emission from molecules in linearly polarized laser fields
Xibin Zhou1, Robynne Lock, Nick Wagner
1JILA and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA. Xibin.Zhou@colorado.edu
High-order harmonic emission from nitrogen molecules (N2) can be strongly elliptically polarized, even with linear laser fields. This finding challenges existing theories and offers new ways to control light-matter interactions.
Area of Science:
- Atomic, Molecular, and Optical Physics
- Quantum Optics
- Strong Field Physics
Background:
- High-order harmonic generation (HHG) is a key process in strong field physics.
- Understanding the polarization dynamics of HHG is crucial for advanced applications.
- Current models often simplify the complex electron dynamics in molecules.
Purpose of the Study:
- To accurately measure the polarization of high-order harmonic emission from aligned molecules.
- To investigate the influence of molecular alignment on harmonic polarization.
- To challenge and refine existing theoretical frameworks for HHG.
Main Methods:
- Precise polarimetry measurements of high-order harmonic emission.
- Utilizing aligned molecular ensembles (specifically N2).
- Driving the system with linearly polarized laser fields.
Main Results:
- Observed strong elliptical polarization in harmonic emission from N2, despite linear driving fields.
- Demonstrated that simple strong field approximation and single active electron models fail to explain these results.
- Showcased the ability to engineer polarization properties by controlling the molecular medium.
Conclusions:
- Molecular HHG exhibits complex polarization behavior not captured by basic theories.
- Accurate polarimetry is essential for probing electron dynamics in strong fields.
- Tailoring molecular media offers a pathway to control harmonic emission polarization.
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