Double-pump technique – one step closer towards efficient liquid-based THz sources

Abstract

By irradiating a water jet with double pulses, we demonstrate 4-fold higher THz wave generation than for a single pump pulse. The dependence of the enhanced THz signal on the temporal delay between two collinear pulses reveals the optimal time for launching signal pulse is near 2-4 ps, which corresponds to the time needed to create the complete pre-ionization state when sufficient electron density is already induced, and there is no plasma reflection of the pump pulse radiation. The increase in THz waves generation efficiency corresponds to the case of water jet excitation by the pulses with an optimal duration for a certain jet thickness, which is determined by the spatial pulse size. Using a theoretical model of the interaction of a high-intensity sub-picosecond pulse with an isotropic medium, we held a numerical simulation, which well describes the experimental results when using 3 ps value of population relaxation time. Thus, in this work, double pump method allows not only to increase the energy of the generated THz waves, but also to determine the characteristic excited state lifetime of liquid water. The optical-to-terahertz conversion efficiency in case of double pulse excitation of water column is of the order of 0.5·10−3, which exceeds the typical values for THz waves generation during two-color filamentation in air and comparable with the achievable values due to the optical rectification in some crystals.

Publication DOI: https://doi.org/10.1364/OE.27.032855
Divisions: Engineering & Applied Sciences
Engineering & Applied Sciences > Aston Institute of Photonics Technology
Additional Information: © 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Uncontrolled Keywords: Atomic and Molecular Physics, and Optics
Full Text Link:
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
https://www.osa ... =oe-27-22-32855 (Publisher URL)
PURE Output Type: Article
Published Date: 2019-10-25
Accepted Date: 2019-10-20
Authors: Ponomareva, Evgenia A.
Tcypkin, Anton N.
Smirnov, Semen V. ( 0000-0002-8562-2452)
Putilin, Sergey E.
Yiwen, E.
Kozlov, Sergei A.
Zhang, Xi Cheng

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