  The temporal contrast is one of the most important parameters of an
ultra-high intense laser pulse. Third-order auto-correlator or cross-correlator
have been widely used to characterize the temporal contrast of an ultra-intense
laser pulse in the past decades. Here, a novel and simple single-shot
fourth-order auto-correlator to characterize the temporal contrast with higher
time resolution and better pulse contrast fidelity in comparison to third-order
correlators is proposed. The single-shot fourth-order autocorrelation consists
of a frequency degenerate four-wave mixing process and a sum-frequency mixing
process. The proof-of-principle experiments show that a dynamic range of
approximately 10^11 compared with the noise level, a time resolution of
approximately 160 fs, and a time window of 65 ps can be successfully obtained
using the novel single-shot fourth-order auto-correlator, which is the highest
dynamic range with simultaneous high time resolution for single-shot temporal
contrast measurement so far. Furthermore, the temporal contrast of laser pulse
from a PW laser system is successfully measured in single-shot with a dynamic
range of about 2*10^10 and simultaneous a time resolution of 160 fs.
