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Spectral splitting in phase mismatched harmonics
Optics Express
|February 1, 2024
Summary
Spectral splitting of high harmonic radiation occurs with chirped laser pulses. This phenomenon, driven by evolving phase-matching conditions, is observed using multi-terawatt laser systems.
Area of Science:
- Atomic, Molecular, and Optical Physics
- Nonlinear Optics
- Laser Physics
Background:
- High harmonic generation (HHG) is a key process for producing extreme ultraviolet (XUV) and soft X-ray radiation.
- The spectral properties of HHG are strongly influenced by phase-matching conditions within the generation medium.
- Frequency chirp in high-energy laser pulses can significantly alter the temporal dynamics of nonlinear optical processes.
Purpose of the Study:
- To investigate the phenomenon of spectral splitting in high harmonic radiation.
- To understand the role of frequency chirp in high-energy laser pulses on HHG.
- To elucidate the underlying physics of evolving phase-matching conditions in the spectral domain.
Main Methods:
- Irradiation of a gas target with a high-energy, frequency-chirped laser pulse from a multi-terawatt (multi-TW) laser system.
- Detailed spectral analysis of the generated high harmonic radiation.
- Development and application of a theoretical model to describe the temporal evolution of phase-matching conditions.
Main Results:
- Observation of distinct spectral splitting in the high harmonic radiation.
- Demonstration that spectral splitting is a direct consequence of the temporal evolution of phase-matching conditions.
- Experimental results are in excellent agreement with the developed theoretical model.
Conclusions:
- Spectral splitting of high harmonic radiation is a measurable phenomenon directly linked to frequency chirp in high-energy laser pulses.
- The temporal dynamics of phase-matching conditions play a crucial role in shaping the spectrum of HHG.
- The presented model provides a robust framework for understanding and predicting this spectral splitting effect.
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