We study the interaction of two parallel-launched femtosecond filaments at their fundamental-wave and second-harmonic frequencies in air. Besides the Kerr effect within the pulse duration, the impulsive alignment of the diatomic molecules in the fundamental-wave filament leads to controllable and field-free achievable attraction, fusion, or repulsion of the second-harmonic filament. The molecular-alignment-assisted filament interaction is further confirmed by the fluorescence intensity variation and spectral modulation of the second-harmonic filament at various molecular alignment revivals.
© 2009 Optical Society of America
Original Manuscript: July 16, 2009
Revised Manuscript: September 18, 2009
Manuscript Accepted: September 18, 2009
Published: October 13, 2009
Jian Wu, Yuqi Tong, Xuan Yang, Hua Cai, Peifen Lu, Haifeng Pan, and Heping Zeng, "Interaction of two parallel femtosecond filaments at different wavelengths in air," Opt. Lett. 34, 3211-3213 (2009)