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Title: New routes to single attosecond pulses

Speaker: J. Meyer-ter-Vehn, Max-Planck-Institute for Quantum Optics, D-85748 Garching, Germany

Time and place: 2:00pm-3:00pm, Oct 30 (Tuesday), 2012, Room 111, Physics Building

Abstract:

The generation of attosecond light pulses depends on beams of high laser harmonics which represent trains of attosecond spikes in the time domain. Presently, high harmonics from gas cells are used in attosecond physics. Here the attosecond time scale is obtained by ionization and coherent rescattering of electrons on ions. This method is restricted to drive pulses of sub-relativistic intensities. In this talk, we explore a very different route to attosecond pulses, making use of relativistic effects. Relativistic mirrors moving at high g may compress femtosecond pulse to attosecond duration and shift frequencies by factors of 4g 2 due to relativistic Doppler effect. This occurs at solid surfaces due to oscillating electron layers, when reflecting laser pulses with amplitudes a_0 >> 1 [1]. Surface harmonics have been observed up to keV photon energies. Another way to produce relativistic mirrors is to drive out electron layers from nanometer-thick foils [2]. Most promising are two foils separated by a few wavelengths, where the second serves to divert the drive light from the electron layer [3]. Different options are discussed related to this configuration [4].

[1] G.D. Tsakiris, K. Eidmann, J. Meyer-ter-Vehn, and F. Krausz. Route to intense single attosecond pulses. New J. Phys. 8, 19 (2006)]

[2] J. Meyer-ter-Vehn and H.-C. Wu. Coherent Thomson backscattering from laser-driven relativistic ultra-thin electon layers. Eur. Phys. J. D55, 433 (2009)]

[3] H.-C. Wu, J. Meyer-ter-Vehn, J. Fernandez, and B.M. Hegelich. Uniform laser-driven relativistic electron layers for coherent Thomson Scattering. Phys. Rev. Letters 104, 234801 (2010).