Abstract
The ultra-short duration of electron bunches is attributed to the micrometer-scale length of the
accelerating plasma waves. Characterization of such a small accelerating structure must be achieved with
high spatial and temporal resolution. A few-cycle laser pulse, which is ultra-wideband and ultra-short,
could be an ideal optical tool for plasma diagnostics with high temporal and spatial resolution. We have
developed a few-cycle optical probe-pulse system to investigate the laser-plasma interaction. The probepulse
is seeded in a hollow-core fiber filled with helium gas to broaden the pulse spectrum, which is later
temporally compressed to a few optical cycles via chirped mirrors. The few-cycle probe pulse can be
used for interferometry and shadowgraphy of the interaction region with an unprecedented level of
temporal resolution at a few femtoseconds.
