Superfast domain walls in KTP single crystals

Abstract

Potassium titanyl phosphate KTiOPO4 (KTP) crystals with periodical ferroelectric domain structures are one of the most promising materials for nonlinear optics, in which the main types of nonlinear optical interactions have been demonstrated. Despite the crucial importance of the in situ visualization of domain structure kinetics for creation of high quality periodical domain gratings, there are only a few works concerning KTP. We present the results of in situ visualization of domain kinetics in KTP with the time resolution down to 12.5 μs and simultaneous recording of the switching current data. The wide range of wall velocities with two orders of magnitude difference was observed for switching in a uniform electric field. The kinetic maps allowed analyzing the spatial distribution of wall motion velocities and classifying the walls by velocity ranges. The distinguished slow, fast, and superfast types of domain walls differed by their orientation. It was shown that the fast and slow domain walls provided the smooth input to the switching current, whereas the short-lived superfast walls resulted in short current peaks. The mobility and the threshold fields for all types of domain walls were estimated. The revealed increase in the wall velocity with deviation from low-index crystallographic planes for slow and fast walls was considered in terms of determined step generation and anisotropic kink motion. The obtained results are important for further development of domain engineering in KTP required for creation of high power, reliable, and effective coherent light sources.

Influence of Humidity on Local Polarization Reversal in a Rb:KTP Single Crystal

“…All the domains were elongated along the Y axis of the crystal. Moreover, the same orientation of the elongated domains was obtained for switching in the uniform electric field using a solid electrode . This domain shape corresponds to the crystal symmetry C 2 .…”

“…The in situ imaging of the domain kinetics was realized for the first time by a complicated experimental method of digital holography . Recently, the in situ optical imaging with high temporal resolution accompanied by simultaneous recording of the switching current has been applied for a detailed study of the domain evolution in KTP. − It has been shown that the polygonal isolated domains in KTP have symmetrically nonequivalent slow, fast, and super-fast domain walls, which differ in velocity by several orders of magnitude. , …”

Mobile and immobile boundaries in ferroelectric films

“…However, between the jumps, the effect of pinning still holds, slowing the DW1 down at each CB. The resulting average speeds of DW1 and DW2 are therefore comparable in the voltage range 2.5–3 V. We note that in practice, there often exists a threshold electric field for DW motion 36 , which is zero in our case. DW speeds are determined by the balance of the driving force associated with the electric field on one hand and dissipative forces, which can be generally decomposed to “dry” and “viscous” friction mechanisms on the other hand 37 .…”

In Situ Imaging of Domain Structure Evolution in LaBGeO5 Single Crystals

“…Liquid electrodes (LiCl saturated aqueous solution) were used for field application. An LBGO plate was glued over the 1-mm-in-diameter round hole in a supporting glass and sandwiched between two glass plates covered by transparent ITO electrodes [27] (Figure 1a). Artificial straight scratches at the sample surface were used as the nucleation centers for the creation of the stripe domains with various orientations.…”