The invention discloses a near-field terahertz
nonlinear optical effect excitation detection method and
system. A
femtosecond laser space-time shaping technology is combined, a strong
terahertz pulse is generated based on a
femtosecond laser filament, the strong
terahertz pulse is coupled with a tapping mode atomic force
microscope, and space-time matching of probe vibration and the
terahertz pulse is accurately controlled by using a synchronous sampling method, so that the time-space matching of the probe vibration and the terahertz pulse is realized. Mismatch between the low-repetition-frequency strong-field terahertz pulse and the vibration frequency of the near-field
microscope probe is overcome, and strong-field terahertz near-field
coupling and detection are achieved. The
local field enhancement effect of the tip of the
nanoprobe can realize nanoscale focusing (peak
field intensity reaches MV / cm magnitude) of a terahertz field at a probe-sample gap, the near-field nonlinear interaction is remarkably enhanced, the
diffraction limit is broken through, and the nanoscale spatial resolution is realized. According to the method, the excitation detection efficiency and the spatial resolution of the terahertz nonlinear effect are remarkably improved, and accurate excitation, characterization and regulation of the
nonlinear optical effect of the sample can be realized.