Study of lithium niobate with periodically reversed domains

Abstract
Periodical domain structure on various surfaces of LiNbO3 crystals doped with Mg and Y or Dy was studied by scanning electron microscopy (SEM) and optical microscopy. A bright contrast of domain boundaries on both surfaces with P, lying in the plane (X-face) and on surfaces nearly normal to Ps was observed by SEM in the secondary electron emission mode. The domain structure periodicity of 5.5 μm was found on the X-face, whereas the domain periodicity of about 2.8 μm is visible on the surface nearly perpendicular to P. The second and third harmonic generation conditions were discussed.