Flexoelectric Fracture-Ratchet Effect in Ferroelectrics.

The propagation front of a crack generates large strain gradients and it is therefore a strong source of gradient-induced polarization (flexoelectricity). Herein, we demonstrate that, in piezoelectric materials, a consequence of flexoelectricity is that crack propagation is helped or hindered depending on whether it is parallel or antiparallel to the piezoelectric polar axis. The discovery of crack propagation asymmetry proves that fracture physics cannot be assumed to be symmetric in polar materials, and indicates that flexoelectricity should be incorporated in any realistic model.

Quasi-phase matched second harmonic generation in periodically poled Rb-doped KTiOPO ridge waveguide.

A 10.8 µm wide ridge waveguide was fabricated by diamond-blade dicing in an ion-exchanged periodically poled Rb-doped KTiOPO sample. The waveguide was used to generate blue second harmonic light at 468.

Contact poling of Rb:KTiOPO(4) using a micro-structured silicon electrode.

A contact poling technique for domain engineering of ferroelectrics using a micro-structured silicon electrode is demonstrated on Rb:KTiOPO. High quality QPM gratings were reproducibly fabricated. The silicon electrode is reusable and the technique potentially suitable when complex structures with sub-μm features are to be domain engineered, which otherwise is incompatible with conventional photolithography.