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Proceedings Paper

Visualization of ultrafast dynamics of laser pulse propagation in the atmosphere using a novel measurement method: FTOP (femtosecond time-resolved optical polarigraphy)
Author(s): Shin-Ichiro Aoshima; M. Fujimoto; M. Hosoda; Yutaka Tsuchiya
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Paper Abstract

In the field of laser processing, it is important to monitor the beam quality such as the spatial- and time-distribution. A novel time-resolved imaging technique named FTOP (Femtosecond Time-resolved Optical Polarigraphy) for visualizing the ultrafast propagation dynamics of intense light pulses in a medium has been proposed and demonstrated. FTOP is used to monitor the 3D intensity distribution of the pump pulse focused in a medium by the probe pulse. Femtosecond snapshot images can be created with a high spatial resolution by imaging only the polarization components of the probe pulse; these polarization components change due to the instantaneous birefringence induced by the pump pulse in the medium. Ultrafast temporal changes in the 2D spatial distribution of the optical pulse intensity were clearly visualized in consecutive images by changing the delay between the pump and probe. We observe that several filaments appear and then come together before the vacuum focus due to nonlinear effects in air. We also prove that filamentation dynamics such as the formation position and the propagation behavior are complex and are strongly affected by the pump energy. The results collected clearly show that this method FTOP succeeds for the first time in directly visualizing the ultrafast dynamics of the self- modulated nonlinear propagation of light.

Paper Details

Date Published: 1 February 2000
PDF: 10 pages
Proc. SPIE 3885, High-Power Laser Ablation II, (1 February 2000); doi: 10.1117/12.376997
Show Author Affiliations
Shin-Ichiro Aoshima, Hamamatsu Photonics K.K. (Japan)
M. Fujimoto, Hamamatsu Photonics K.K. (Japan)
M. Hosoda, Hamamatsu Photonics K.K. (Japan)
Yutaka Tsuchiya, Hamamatsu Photonics K.K. (Japan)


Published in SPIE Proceedings Vol. 3885:
High-Power Laser Ablation II
Claude R. Phipps; Masayuki Niino, Editor(s)

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