Open AccessEnhancement of femtosecond laser-induced plasma fluorescence using a nanosecond laser
Author(s) -
Xiaofeng Li,
Bo Li,
Jixu Liu,
Zhifeng Zhu,
Dayuan Zhang,
Yifu Tian,
Qiang Gao,
Zhongshan Li
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.005755
Subject(s) - femtosecond , nanosecond , laser , materials science , optics , fluorescence , laser induced fluorescence , plasma , atomic physics , physics , quantum mechanics
We demonstrate the enhancement of femtosecond (fs) laser-induced filaments in air and nitrogen flow fields using a nanosecond (ns) laser. With the ns laser being imposed on the filaments, the length and the emission intensity of the filaments were largely increased. Temporally resolved spectra of the enhanced filaments were obtained. The results show that the ns laser enhanced the short-lifetime fluorescence of nitrogen, which comes from the transition processes of N 2 + (B 2 Σ u + - X 2 Σ g + ), N 2 (B 3 П g - A 3 Σ u + ) and N 2 (C 3 П u - B 3 П g ). However, it had little effect on the long-lifetime chemiluminescence, which mainly comes from reactions such as N 2 (A 3 Σ u + ) + N 2 (A 3 Σ u + ) → N 2 (X 1 Σ g + , v = 0) + N 2 (B 3 П g ). A possible explanation of this phenomenon is given, and this phenomenon might have potential applications in instantaneous one-dimensional measurements of various species in gas flow fields.