Abstract
We study the influence of the molecular alignment on the plasma channel length of femtosecond filament at 800 nm in air. The filament length is observed to be nearly doubled when the high-energy femtosecond laser pulse is properly tuned to match the perpendicular revivals of the molecular alignment, which is different from the low-energy femtosecond laser pulse where the filament is promoted for parallel molecular alignment revivals. These are understood to be the loosened or tightened focusing condition of the propagation of the femtosecond laser pulse by the cross-(de)focusing effect from the prealigned molecules.
Highlights
The self-guided propagation of infrared femtosecond laser pulses in transparent optical nonlinear media has sparked many interests and important applications [1,2,3,4,5,6,7] such as atmospheric remote sensing [4,5], trigger and guide electric discharges [6], and remote terahertz source [7]
When the high-energy femtosecond pulse was properly tuned to match the perpendicular revivals of the molecular alignment, the filament length was nearly doubled with respect to the randomly orientated molecules
At delay-B, the fluorescence intensity of the probe pulse at the position of 44 cm was increased about 15 times as compared with that of random orientation and the filament of the probe pulse was terminated at the position of 73 cm, which indicated that the filament length of the probe pulse was nearly doubled
Summary
The self-guided propagation of infrared femtosecond laser pulses in transparent optical nonlinear media has sparked many interests and important applications [1,2,3,4,5,6,7] such as atmospheric remote sensing [4,5], trigger and guide electric discharges [6], and remote terahertz source [7]. A long-distance filament is desired, and it was shown that, for constant input pulse energy, the length of the filament could be longest for an optimum pulse duration [8], which was shown to be sensitive to the temporal chirp [9] of femtosecond laser pulses. We have recently numerically demonstrated [10] that the length of the filament could be significantly increased by properly tuning the femtosecond laser pulse to match the molecular alignment revivals after an impulsive excitation of an ultrashort pump pulse. We experimentally demonstrate that the length of the filament channel could be significantly increased by propagating the energetic femtosecond laser pulse in prealigned diatomic molecules in air. When the high-energy femtosecond pulse was properly tuned to match the perpendicular revivals of the molecular alignment, the filament length was nearly doubled with respect to the randomly orientated molecules. The basic underlying physics is that the cross-(de)focusing effect of the prealigned molecules modulated the focusing condition and the filament dynamics
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
