Domain Structure Analyses of Tetragonal BaTiO3 Single Crystal by Scanning Second-Harmonic Generation Microscopy: Birefringence Effect on Second-Harmonic Generation Polarization Diagram

The effects of birefringence on polarization dependences of the second-harmonic generation (SHG) measured with a focused optical system are examined experimentally and theoretically for tetragonal domain structures of ferroelectric BaTiO 3 . Polar diagram shapes of the SHG intensity are modified owing to the phase difference of mutually perpendicular waves due to birefringence, but no essential change in the spontaneous polarization direction is observed.