Abstract
We numerically study the influence of chirping and delaying several ionizing two-color light pulses in order to engineer terahertz (THz) wave generation in air. By means of comprehensive 3D simulations, it is shown that two chirped pulses can increase the THz yield when they are separated by a suitable time delay for the same laser energy in focused propagation geometry. To interpret these results, the local current theory is revisited and we propose an easy, accessible all-optical criterion that predicts the laser-to-THz conversion efficiencies given any input laser spectrum. In the filamentation regime, numerical simulations display evidence that a chirped pulse is able to produce more THz radiation due to propagation effects, which maintain the two colors of the laser field more efficiently coupled over long distances. A large delay between two pulses promotes multi-peaked THz spectra as well as conversion efficiencies above 10−4.
Highlights
29 March 2018Original content from this work may be used under the terms of the Creative Abstract
Terahertz (THz) time-domain spectroscopy is a promising way to analyze various complex materials, the molecular transitions of which possess unique fingerprints in this spectral range [1,2,3]
A two-color ultrashort laser field composed of a fundamental harmonic (FH) frequency and its second harmonic (SH) ionizes the gas, which creates a plasma acting as frequency converter towards the THz range
Summary
Original content from this work may be used under the terms of the Creative Abstract. By means of comprehensive 3D simulations, this work must maintain attribution to the it is shown that two chirped pulses can increase the THz yield when they are separated by a suitable author(s) and the title of time delay for the same laser energy in focused propagation geometry. To interpret these results, the the work, journal citation and DOI. Numerical simulations display evidence that a chirped pulse is able to produce more THz radiation due to propagation effects, which maintain the two colors of the laser field more efficiently coupled over long distances. A large delay between two pulses promotes multi-peaked THz spectra as well as conversion efficiencies above 10−4
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