Chinese Journal of Lasers, Volume. 51, Issue 7, 0701004(2024)
Advances in High-Order Harmonic Generation from Laser-Produced Low-Density Plasmas
Fig. 1. Schematic illustration of semi-classical “three-step” model for HHG from atoms or molecules
Fig. 3. HHG obtained in experiment with femtosecond intense laser-produced plasmas from Sn solid target and nanoparticles. (a), (b) HHG raw images obtained from Sn solid target and Sn nanoparticles; (c) spectra
Fig. 4. Photoabsorption cross-section spectra of Sn Ⅱ (top), Sn Ⅲ (middle), and Sn Ⅲ* (bottom)[63]
Fig. 5. “ Four-step ” model of plasma HHG includes 1) ionization, 2) free-electronic motion in electric field, 3*) recombination in gas HHG being replaced by 3) radiationless transition to autoionizing state, and 4) relaxation with EUV emission[65]
Fig. 6. Plasma and nonresonant harmonic spectra. (a) Raw images of plasma (upper panels) and HHG (bottom panels) spectra obtained from Ag and Au targets with 810 nm femtosecond pulses; (b) raw images of HHG (upper panel) and plasma (bottom panel) spectra obtained from Mg target with 1340 nm femtosecond pulses; (c) raw images of plasma (upper panel), plasma+HHG (middle panel), and HHG (bottom panel) spectra obtained from C target with 1340 nm+670 nm femtosecond pulses[72]
Fig. 7. Harmonic spectra comparison between solid target and nanoparticles. (a) Harmonic spectra obtained using In2O3 solid target (blue) and In2O3 nanoparticles (red), where inset shows intensities of nonresonant H11 harmonic of In2O3 nanoparticles (red) and resonant H13 harmonic of In2O3 solid target (blue) varying with delay between HP and DP pulses; (b) harmonic spectra obtained using Sn solid target (blue) and Sn nanoparticles (red)[60]
Fig. 8. Tuning of H15 and H17 of Sn plasma harmonics by different laser chirps[63]
Fig. 9. Harmonic spectra from Sn plasma in cases of single-color and two-color pump schemes. (a) Single-color pump scheme; (b) two-color pump scheme[63]
Fig. 10. Harmonic spectra from Sn plasma in cases of 800 nm and 400 nm pump schemes. (a) 800 nm pump scheme; (b) 400 nm pump scheme[109]
Fig. 11. Comparison of HHG generated using Gaussian driving field and vortex driving field. (a) HHG spectrum generated using Gaussian driving field; (b) HHG spectrum generated using vortex driving field; (c) vertically integrated spectra of two driving fields[102]
Fig. 12. Regulating HHG radiation by using special target configurations. (a) Scheme for HHG in plasmas produced from mixed targets; (b) scheme for HHG in plasmas using multi-slit mask
Fig. 14. Improving repetition rate of HHG using rotating cylindrical target. (a) Schematic diagram of rotating target; (b) stability of HHG from Al plasmas using rotating target[116]
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Jian Gao, Jian Wu. Advances in High-Order Harmonic Generation from Laser-Produced Low-Density Plasmas[J]. Chinese Journal of Lasers, 2024, 51(7): 0701004
Category: laser devices and laser physics
Received: Dec. 19, 2023
Accepted: Feb. 2, 2024
Published Online: Mar. 29, 2024
The Author Email: Jian Gao (jgao@lps.ecnu.edu.cn)
CSTR:32183.14.CJL231546