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High-order harmonic generation by subpicosecond KrF excimer laser pulses
Optics Letters
|October 30, 2009
Summary
Researchers generated high-order harmonics using a KrF excimer laser in various gases. The highest harmonic observed was 7.1 nm in helium and neon, suggesting ionized atoms are the source and free electrons may limit photon energy.
Area of Science:
- Atomic and Molecular Physics
- Laser Physics
- Nonlinear Optics
Background:
- High-order harmonic generation (HHG) is a crucial nonlinear optical process.
- Understanding HHG mechanisms is key to developing advanced light sources.
Purpose of the Study:
- Investigate high-order harmonic generation using a KrF excimer laser.
- Explore harmonic generation in different atomic and molecular gases.
- Identify factors limiting maximum harmonic photon energy.
Main Methods:
- Utilized a KrF excimer laser (80 mJ, 0.5 ps) as the driver.
- Experimented with rare gases (Helium, Neon) and molecular gases (Nitrogen, Oxygen).
- Analyzed the generated harmonic spectra to determine the highest observed order and wavelength.
Main Results:
- Observed the 35th harmonic (7.1 nm) in Helium and Neon.
- Observed the 29th harmonic (8.6 nm) in Nitrogen and Oxygen.
- Experimental data indicate that ionized atoms are the source of high-order harmonics.
Conclusions:
- The generation of high-order harmonics was successfully demonstrated in various gases.
- The maximum achievable photon energy appears to be limited by phase mismatching due to free electrons.
- Ionized atoms are confirmed as the emission source for these high-order harmonics.
