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Abstract

We develop an analytical model for ultraintense attosecond pulse emission in
the highly relativistic laser-plasma interaction. In this model, the attosecond
pulse is emitted by a strongly compressed electron layer around the instant
when the layer transverse current changes the sign and its longitudinal
velocity approaches the maximum. The emitted attosecond pulse has a broadband
exponential spectrum and a stabilized constant spectral phase
$\psi(\omega)=\pm\pi/2-\psi_{A_m}$. The waveform of the attosecond pulse is
also given explicitly, to our knowledge, for the first time. We validate the
analytical model via particle-in-cell (PIC) simulations for both normal and
oblique incidence. Based on this model, we highlight the potential to generate
an isolated ultraintense phase-stabilized attosecond pulse