Image of near-field second-harmonic generation for inversely poled mesoscopic LiNbO3 domains

A theoretical investigation is presented for the image of near-field second-harmonic generation (SHG) from inversely poled LiNbO₃ domains. Self-consistent integral equation formalism and Euler rotation matrix are applied to investigate the optical intensity distribution of this kind of near-field SHG. The numerical simulations show that the calculated images of the near-field second-harmonic wave in both transmission and collection modes of scanning near-field optical microscopy (SNOM) at the same dip-sample distance can well be used to distinguish domain structures. The image patterns strongly depend on the polarization mode and the incident angle of the illumination light.