Evolution of the nonlinear Raman-Nath diffraction from near field to far field.

In this Letter, we studied the near-field effect of the nonlinear Raman-Nath diffraction experimentally in a 1D periodically poled LiTaO crystal and established a theoretical relationship between the nonlinear effect in the near field and the corresponding effect in the far field. The interference of far-field spots in the near field constitutes the nonlinear Talbot self-imaging effect. Our results not only enhance our understanding of the nonlinear Talbot effect, but they also indicate potential applications of this effect in domain inspection and domain design.