| Title |
Fine 3D control of THz emission in air with dual femtosecond laser pre-pulses at tunnelling ionisation regime / |
| Authors |
Huang, Hsin-Hui ; Nagashima, Takeshi ; Kumagai, Kota ; Hayasaki, Yoshio ; Juodkazis, Saulius ; Tikhonchuk, Vladimir T ; Hatanaka, Koji |
| DOI |
10.37188/lam.2024.030 |
| Full Text |
|
| Is Part of |
Light: advanced manufacturing.. Changchun : Light Publishing Group. 2024, vol. 5, iss. 3, art. no. 30, p. 342-354.. ISSN 2689-9620. eISSN 2831-4093 |
| Keywords [eng] |
Air breakdown ; Femtosecond laser induced breakdown ; spatio-temporal control ; THz radiation |
| Abstract [eng] |
Emission of THz radiation from air breakdown at focused ultra-short fs-laser pulses (800 nm/35 fs) was investigated for the 3D spatio-temporal control where two pre-pulses are used before the main-pulse. The laser pulse induced air breakdown forms a ~ 120 μm-long focal volume generate shockwaves which deliver a denser air into the focal region of the main pulse for enhanced generation of THz radiation at 0.1–2.5 THz spectral window. The intensity of pre- and main-pulses was at the tunnelling ionisation intensities (1 –3) × 1016 W/cm2 and corresponded to sub-critical (transparent) plasma formation in air. Polarisation analysis of THz radiation revealed that orientation of the air density gradients generated by pre-pulses and their time-position locations defined the ellipticity of the generated THz electrical field. The rotational component of electric current is the origin of THz radiation. |
| Published |
Changchun : Light Publishing Group |
| Type |
Journal article |
| Language |
English |
| Publication date |
2024 |
| CC license |
|
