Laser pulse frequency up-shifts by relativistic ionization frontsN. C. Lopes1, G. Figueira1, J. M. Dias1, L. O. Silva1, J. T. Mendonça1, Ph. Balcou2, G. Rey2 and C. Stenz3
1 GoLP-Instituto Superior Tecnico - Complexo I Av. Rovisco Pais, 1049-001 Lisboa, Portugal
2 Laboratoire d'Optique Appliquée, Ensta-Ecole Polytechnique, CNRS UMR 7639 F-91761 Palaiseau Cedex, France
3 Laboratoire CELIA, CNRS-Université Bordeaux 1, UMR 5107 33405 Talence, France
(Received 3 September 2003; accepted in final form 2 March 2004)
A multi-terawatt, ultra-short laser pulse was used to create a large, well-defined relativistic ionization front, and the collision of a probe laser pulse with it was studied. Due to the good definition of the ionization front it was also possible to isolate the probe frequency up-shift due to the collision, unlike in previous experiments. A good agreement with the theoretical model for photon acceleration was found. Furthermore, we report novel measurements of ionization front velocities, based on the photon acceleration effect, in excess of 0.99c.
52.38.-r - Laser-plasma interactions.
52.59.-f - Intense particle beams and radiation sources.
52.70.Kz - Optical (ultraviolet, visible, infrared) measurements.
© EDP Sciences 2004