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Updated: Jun 22, 2026
09:23
Harmonic Nanoparticles for Regenerative Research
Published on: May 1, 2014
High harmonic generation in a semi-infinite gas cell
Optics Express
|June 2, 2009
Summary
Investigating high harmonic generation in helium and neon with femtosecond laser pulses revealed that an aperture significantly boosts harmonic brightness. Harmonics in neon are absorption-limited near the exit foil, while helium allows for longer generation distances.
Area of Science:
- Atomic, Molecular, and Optical Physics
- Quantum Optics
- Nonlinear Optics
Background:
- High harmonic generation (HHG) is a crucial process for producing extreme ultraviolet and X-ray light.
- Understanding the spatial dynamics of HHG is essential for optimizing light source performance.
- Previous studies have explored HHG in various media, but detailed spatial mapping remains an active area of research.
Purpose of the Study:
- To investigate the spatial characteristics of high harmonic generation in helium and neon.
- To determine the optimal conditions for maximizing harmonic brightness using an aperture.
- To spatially resolve the generation region of high-order harmonics within the laser focus.
Main Methods:
- Utilizing ten-millijoule, 35-femtosecond laser pulses interacting with helium or neon gas cells.
- Varying the focal position relative to an exit foil to study harmonic emission.
- Employing an aperture to enhance harmonic brightness.
- Using counter-propagating light to probe the harmonic generation region.
Main Results:
- An aperture placed before the focusing lens increased observed harmonic brightness by over an order of magnitude.
- In neon, high harmonic generation was confined to the last few millimeters before the exit foil, limited by absorption.
- In helium, harmonics were produced over a significantly longer distance compared to neon.
Conclusions:
- Spatial confinement and absorption play critical roles in limiting HHG efficiency in neon.
- Helium offers a longer interaction region for HHG, potentially enabling different applications.
- Aperture-based focusing is an effective technique for enhancing HHG brightness.
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