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Enhancing High-Order Harmonic Generation in Light Molecules by Using Chirped Pulses.
M Lara-Astiaso1, R E F Silva1, A Gubaydullin1
1Departamento de Química, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Physical Review Letters
|September 10, 2016
Summary
Extending high-harmonic generation to higher energies is challenging. This study shows down-chirped pulses and nuclear dynamics in molecules can boost harmonic emission efficiency and control the plateau extension.
Area of Science:
- Quantum optics
- Attosecond science
- Molecular physics
Background:
- High-harmonic generation (HHG) is a key process for producing ultrashort extreme ultraviolet (XUV) and X-ray light pulses.
- A major limitation in HHG is extending the harmonic cutoff to higher photon energies while maintaining emission efficiency.
- Controlling nuclear dynamics within molecules during HHG is crucial for optimizing light emission.
Purpose of the Study:
- To investigate the combined effects of down-chirped laser pulses and molecular nuclear dynamics on high-harmonic generation.
- To achieve extended harmonic cutoff energies with enhanced emission efficiency.
- To demonstrate control over the harmonic plateau extension using pulse duration and isotopic substitution.
Main Methods:
- Utilizing theoretically modeled down-chirped infrared (IR) laser pulses.
- Simulating the interaction of these pulses with light molecules, considering nuclear motion.
- Analyzing the generated high-harmonic spectra and their cutoff energies.
- Investigating the influence of varying pulse durations and isotopic compositions.
Main Results:
- The combined effect of down-chirped pulses and nuclear dynamics enables extension of the harmonic cutoff to higher energies.
- Sufficiently long IR pulse durations are required to allow significant nuclear motion beyond the Franck-Condon region.
- Varying the down-chirped pulse duration or performing isotopic substitution allows for controlled extension of the harmonic plateau.
- High harmonic emission efficiency can be maintained or increased under these conditions.
Conclusions:
- Down-chirped pulses coupled with molecular nuclear dynamics offer a viable pathway to overcome current limitations in high-harmonic generation.
- This approach provides a method for generating higher-energy photons with improved efficiency.
- Tunable control over the harmonic plateau extension is achievable, opening possibilities for tailored attosecond light sources.
