fig1

Figure 1. (A) The relative dielectric permittivity (ε_r) vs. temperature at 1 kHz. T_O-T: the orthorhombic-to-tetragonal phase transition temperature; T_room: the room temperature; T_C: Curie temperature, the tetragonal-to-cubic phase transition temperature. (B) Different polarization states (left) of the fundamental light incident along the x-axis and the corresponding SHG spots (right). (C) Optical path diagram for investigating the polarization dependence of SHG. (D) Relative intensity of SHG spots in different polarization states.