  The reflection and transmission of a few-cycle Ti:Sa laser pulse iminging on
a thin plasma layer have been analysed on the basis of classical
electrodynamics. An approximate analytic solution has been given for the
coupled Maxwell-Lorentz equations describing the dynamics of the surface
current and the composite radiation field. The nonlinearities stemming from the
relativistics kinematics of free electrons lead to the appearance of
higher-harmonics in the scattered spectra. In our analysis particular attention
has been paid to the effect of the carrier-envelope phase difference of the
incoming laser pulse. For the fourth harmonic peak we calculated almost 25
percent modulation. In general, the harmonic peaks are down-shifted due to
presence of the intensity-dependent factors by an order of 15-65 percent in
case of an incoming field of intensity we have discussed. The spectrum of the
high-harmonics has a long tail where the heights of the peaks vary within one
order of magnitude forming a quasi-continuum. By Fourier synthetising the field
components of this plateau region attosecond pulses have been obtained.
