Few-Cycle Laser Pulses: The Carrier-Envelope Phase, Its Role in the THz Emission from Laser-Generated Plasmas and a New Way to Measure It |
M. Kress a, T. Löffler a, M.D. Thomson a, H.G. Roskos a, R. Dörner b, H. Gimpel c, K. Zrost c, T. Ergler c, R. Moshammer c, U. Morgner c and J. Ullrich c
a Physikalisches Institut, Johann Wolfgang Goethe-Universität, Max-von-Laue-Str. 1, D-60438 Frankfurt (M), Germany b Institut fűr Kernphysik, Johann Wolfgang Goethe-Universität, Max-von-Laue-Str. 1, D-60438 Frankfurt (M), Germany c Max-Planck-Institut fűr Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany |
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Received: 26 08 2007; |
Terahertz emission from laser-generated air plasmas has recently been identified as an interesting source for THz radiation. High intensities and a large bandwidth of the THz pulses can be achieved. We briefly review several mechanisms which were employed to generate the quasi-static dipole moment needed for the optical rectification process. This leads us to a discussion of a specific application of THz emission from an air plasma, namely the investigation of the carrier-envelope phase of few-cycle optical pulses. Such pulses of a duration of less than 10 fs induce a spatial charge asymmetry in the plasma directly via non-linear tunneling ionization. The asymmetry, and with it the emission of the THz radiation from the plasma, depend on the carrier-envelope phase, with the consequence that one can determine the phase by measurement of the amplitude and polarity of the THz pulse. |
DOI: 10.12693/APhysPolA.113.769 PACS numbers: 42.65.Re, 72.30.+q, 78.47.-p |