  Synchronous extreme ultraviolet (XUV) and single-cycle terahertz (THz) bursts
are generated in argon plasma induced by intense two-color femtosecond laser
pulses. Correlations between the intensity of the even and odd high-harmonics
and the THz radiation are found by studying the phase-delay between the
excitation pulses at 800 and 400 nm as well as the degree of polar asymmetry in
the incident electric field. Experiments in both the weak- and strong- polar
asymmetric regimes show remarkable agreement with a simple analytical model
based on classical electron trajectories in an arbitrary synthetic electric
field.
