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arXiv · 1501.00658

CEP-stable Tunable THz-Emission Originating from Laser-Waveform-Controlled Sub-Cycle Plasma-Electron Bursts

T. Balčiūnas·D. Lorenc·M. Ivanov·O. Smirnova·A. M. Zheltikov·D. Dietze·J. Darmo·K. Unterrainer·T. Rathje·G. Paulus·A. Baltuška·S. Haessler
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Abstract

We study THz-emission from a plasma driven by an incommensurate-frequency two-colour laser field. A semi-classical transient electron current model is derived from a fully quantum-mechanical description of the emission process in terms of sub-cycle field-ionization followed by continuum-continuum electron transitions. For the experiment, a CEP-locked laser and a near-degenerate optical parametric amplifier are used to produce two-colour pulses that consist of the fundamental and its near-half frequency. By choosing two incommensurate frequencies, the frequency of the CEP-stable THz-emission can be continuously tuned into the mid-IR range. This measured frequency dependence of the THz-emission is found to be consistent with the semi-classical transient electron current model, similar to the Brunel mechanism of harmonic generation.

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T. Balčiūnas, D. Lorenc, M. Ivanov, O. Smirnova, A. M. Zheltikov, D. Dietze, J. Darmo, K. Unterrainer, T. Rathje, G. Paulus, A. Baltuška, S. Haessler. 2015-02-10. CEP-stable Tunable THz-Emission Originating from Laser-Waveform-Controlled Sub-Cycle Plasma-Electron Bursts. https://doi.org/10.1364/oe.23.015278

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