Abstract-Wavelength Scaling of Terahertz Generation by Gas Ionization

Matteo Clerici^1,2,*, Marco Peccianti^3,1, Bruno E. Schmidt¹, Lucia Caspani¹, Mostafa Shalaby¹, Mathieu Giguère¹,Antonio Lotti^4,5, Arnaud Couairon⁵, François Légaré¹, Tsuneyuki Ozaki¹, Daniele Faccio^2,†, and Roberto Morandotti^1 
1INRS-EMT, 1650 Boulevard Lionel-Boulet, Varennes, Québec J3X 1S2, Canada
²School of Engineering and Physical Sciences, Heriot-Watt University, SUPA, Edinburgh EH14 4AS, United Kingdom
³Institute for Complex Systems (ISC), CNR, via dei Taurini 19, 00185 Rome, Italy
⁴Dipartimento di Scienza e Alta Tecnologia, Università degli Studi dell’Insubria, via Valleggio 11, 22100 Como, Italy
⁵Centre de Physique Théorique CNRS, École Polytechnique, F-91128 Palaiseau, France
http://prl.aps.org/abstract/PRL/v110/i25/e253901

Low-frequency currents induced by ultrashort laser-driven ionization can emit extremely broadband, single-cycle terahertz pulses. We present a model that predicts a strong wavelength dependence of the THz emission in good agreement with our experimental study. This reveals that the combined effects of plasma currents rising proportionally to the square of the pump wavelength and wavelength-dependent focusing conditions lead to 30 times higher THz emission at 1800 nm compared to an 800 nm wavelength. Unrivaled single-cycle electric field strengths of 4.4  MV/cm are achieved with this compact table-top setup.

© 2013 American Physical Society