  The resonant generation of relativistic plasma waves and plasma wave guiding
by two co-propagating laser pulses has been studied. By proper timing between
guiding and driver pulses, a resonant interaction occurs, which generates a
high-amplitude plasma wave over a longer length than is possible with either of
the laser pulses individually. The growth of the plasma wave is inferred by the
measurement of monoenergetic electron beams with low divergence that are not
measured by using either of the pulses individually. This scheme can be easily
implemented, and allows more control of the interaction than is available to
the single pulse scheme.
