We compare detailed spatio-temporal propagation simulations with experiments on generation of terahertz (THz) pulses in single filaments with two-color optical excitation, which elucidates the mechanism whereby positively chirped optical pulses lead to the maximum THz yield. The long-wavelength components in the leading edge of the positively chirped 2ω-pulse preserve the overlap with the ω-pulse. The THz yield is extremely sensitive to the temporal overlap: for a 35-fs ω-pulse, the yield decreases by an order of magnitude upon a ω–2ω pulse shift of only 5 fs.
Optimum chirp for efficient terahertz generation from two-color femtosecond pulses in air
Zhen Zhang, N. Panov, V. Andreeva, Zhelin Zhang, A. Slepkov, D. Shipilo, M. D. Thomson, Tie-Jun Wang, I. Babushkin, A. Demircan, U. Morgner, Yanping Chen, O. Kosareva, A. Savel'ev; Optimum chirp for efficient terahertz generation from two-color femtosecond pulses in air. Appl. Phys. Lett. 10 December 2018; 113 (24): 241103. https://doi.org/10.1063/1.5053893
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