Scanning electron microscopy was used to study the mobility of domain walls in vapor-transport equilibrated stoichiometric LiTaO3. By using low-acceleration voltage, switching occurs solely for polarization pointing up domains, resulting in fast domain-wall motion. When the incoming electron beam was more energetic with larger penetration depth, the switching instead occurred for polarization pointing down domains. Our results are discussed in terms of the interaction of the scanning electron beam with the polarization-screening charges at the crystal surface.

Scanning electron microscopy was used to study the mobility of domain walls in vapor-transport equilibrated stoichiometric LiTaO₃. By using low-acceleration voltage, switching occurs solely for polarization pointing-up domains, resulting in fast domain-wall motion. When the incoming electron beam was more energetic with larger penetration depth, the switching instead occurred for polarization pointing down domains. Our results are discussed in terms of the interaction of the scanning electron beam with the polarization-screening charges at the crystal surface.

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.

A way to stabilize the domain structure in periodically poled Rb-doped KTiOPO 4 samples at high-temperatures is presented. The domain contraction along the b-crystallographic axis that is observed when crystals are annealed at high temperatures is suppressed when the ends of the domains along the b-axis are diced away. Additionally, the thermal stability of self-assembled domain gratings with a sub-μm average periodicity of 650 ± 200 nm and a domain-width of 225 ± 75 nm in mm-thick samples is investigated, and it is shown that the key factor for the domain stability is the domain width rather than the interdomain distance.

Nonlinear optics in waveguides provide means for efficient nonlinear interactions as this platform permits high confinement over long interaction lengths, and it has been a field of intense research since the early days of nonlinear optics. With the development of electric field poling and novel waveguide fabrication methods, waveguide devices have become of interest again and exploited in several contemporary applications like spectroscopy, metrology, sensing and quantum optics. The challenge that drives the field in the present days is the development of waveguides with small modal cross section, high transverse overlap between interacting modes, and low propagation loss. Rubidium-doped KTP (RKTP) is an attractive material as it has high nonlinear coefficients, strong resistance to optical damage, and a wide transparency range. Furthermore, it presents lower ionic conductivity, compared with its isomorph KTP, allowing fabrication of high quality ferroelectric domain gratings. Waveguide fabrication techniques combined with periodically poled structures allows to obtain quasi-phase matching (QPM) of Type I for RKTP so the strong d ₃₃ coefficient can be exploited.

Nonlinear optics in waveguides provide means for efficient nonlinear interactions as this platform permits high confinement over long interaction lengths, and it has been a field of intense research since the early days of nonlinear optics [1]. With the development of electric field poling [2] and novel waveguide fabrication methods, waveguide devices have become of interest again and exploited in several contemporary applications like spectroscopy, metrology, sensing and quantum optics. The challenge that drives the field in the present days is the development of waveguides with small modal cross section, high transverse overlap between interacting modes, and low propagation loss. Rubidium-doped KTP (RKTP) is an attractive material as it has high nonlinear coefficients, strong resistance to optical damage, and a wide transparency range. Furthermore, it presents lower ionic conductivity, compared with its isomorph KTP, allowing fabrication of high quality ferroelectric domain gratings [3]. Waveguide fabrication techniques combined with periodically poled structures allows to obtain quasi-phase matching (QPM) of Type I for RKTP so the strong d33 coefficient can be exploited [4].

A 10.8 mu m wide ridge waveguide was fabricated by diamond-blade dicing in an ion-exchanged periodically poled Rb-doped KTiOPO4 sample. The waveguide was used to generate blue second harmonic light at 468.8 nm in the TM(00 )mode through first order Type I quasi-phase matching, exploiting the large d(33) coefficient of the crystal. It was evaluated using a cw Ti:Sapphire laser, and 6.7 mu W of blue light was generated with 5.8 mW of fundamental radiation at 933.8 nm coupled through the waveguide. The results presented here pave the way for efficient nonlinear processes in a waveguide format. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

The effect of chemical etching on the stability of domains in periodically poled stoichiometric lithium tantalate is studied by on-line second harmonic generation and microscopy. It is found that wet etching directly after poling leads to domain-wall movement, resulting in back-switching or domain merging. Head-to-head domains tend to backswitch, while tail-to-tail domains merge. For samples where the domain structure stabilized for longer time, no domain motion is observed when etched.