V. Ya. Shur

Nanoscale backswitched domain patterning in lithium niobate

We demonstrate a promising method of nanoscale domain engineering, which allows us to fabricate regular nanoscale domain patterns consisting of strictly oriented arrays of nanodomains (diameter down to 30 nm and density up to 100 μm−2) in lithium niobate. We produce submicron domain patterns through multiplication of the domain spatial frequency as compared with the electrode one. The fabrication techniques are based on controlled backswitched poling.

Formation and evolution of charged domain walls in congruent lithium niobate

We present experimental evidence of the formation of stable charged domain walls (CDWs) in congruent lithium niobate during switching. CDW evolution under the action of field pulses was in situ visualized. CDW boundary motion velocity is about 60 μm/s at 20 kV/mm. Relief of CDW strongly depends on applied field. Dielectric response in the presence of CDW demonstrates the pronounced frequency dependence in the range 50–150 °C. We propose the mechanism of CDW self-maintained propagation governed by self-consistent electrostatic interaction between the wall’s steps.

Investigation of the nanodomain structure formation by piezoelectric force microscopy and Raman confocal microscopy in LiNbO3 and LiTaO3 crystals

Piezoelectric force microscopy (PFM) and Raman confocal microscopy have been used for studying the nanodomain structures in congruent LiNbO3 and LiTaO3 crystals. The high-resolution nanodomain images at the surface were observed via PFM. Raman confocal microscopy has been used for the visualization of the nanodomain structures in the bulk via layer-by-layer scanning at various depths. It has been shown experimentally that the nanodomain images obtained at different depths correspond to domain images at the polar surface obtained at different moments: the deeper the nanodomain, the earlier the moment. Such a correlation was applied for the reconstruction of the evolution of the domain structures with charged domain walls. The studied domain structures were obtained in highly non-equilibrium switching conditions realized in LiNbO3 and LiTaO3 via pulse laser irradiation and the electric field poling of LiNbO3, with the surface layer modified by ion implantation. The revealed main stages of the domain structu...

Regular Ferroelectric Domain Array in Lithium Niobate Crystals for Nonlinear Optic Applications

Abstract We present our experimental investigations of the domain evolution in lithium niobate. Particular attention is paid to the short-pitch and nanoscale domain patterning. We demonstrate the production of domain patterns with period down to 2.6 μ.m in 0.5-mm-thick LiNbO3wafers by backswitched poling using lithographic stripe electrodes and nanoscale domain patterns consisting of strictly oriented arrays of nanodomains (diameter down to 30 nm, density up to 100 μm−2).

Rearrangement of ferroelectric domain structure induced by chemical etching

The rearrangement of the domain structure induced by chemical etching has been observed in periodically poled MgO-doped stoichiometric lithium tantalate single crystals. Topographic and piezoresponse scanning probe microscopy have been used for measuring the etching relief height and domain wall position after etching. The considerable shift of the domain wall during etching by pure hydrofluoric acid has been revealed by analysis of the experimental data. We have found that the wall motion proceeded after the termination of the etching procedure. We have shown that the whole consequence of the domain wall positions during etching is recorded in the etching relief height and can be extracted with high spatial and temporal resolution.

Domain engineering in lithium niobate and lithium tantalate : Domain wall motion

The main aspects of domain engineering in LiNbO 3 and LiTaO 3 representing field induced formation of the tailored domains are discussed. The special attention is paid to sideways domain wall motion. Experimentally observed wall motion scenarios have been classified. It is discovered that the realization of the given scenario is defined by degree of deviation of the switching conditions from equilibrium characterized by ratio between switching and screening rates. It has been proved that the domain growth acceleration after merging is due to formation of super-fast X-oriented walls. The loss of wall shape stability and formation of nano-domains have been considered.

Micro- and nano-domain engineering in lithium niobate

The physical basis of the domain engineering in ferroelectrics and its application to lithium niobate crystals were reviewed. The unified kinetic approach to the domain structure evolution in electric field was formulated and its validity for understanding the variety of observed domain evolution scenarios was demonstrated. The kinetics and statics of the domain structure in the crystals of lithium niobate family including congruent, stoichiometric, and MgO doped ones have been discussed. The main stages of the periodical poling process and related problems have been pointed out. The basic poling techniques applied for creation of the periodical domain structures in bulk crystals and waveguides were compared. The recent applications of the periodically poled lithium niobate for light frequency conversion using second harmonic generation and optical parametric oscillation, excitation of the surface acoustic waves, and generation of terahertz radiation have been discussed. The special attention has been paid for achievements in fabrication of high-power optical parametric oscillation and integrated optical devices with periodically poled lithium niobate. The future trends in periodical poling and development of the nanodomain engineering which will allow to create the nanoscale domain patterns necessary for utilization of the new nonlinear interactions were reviewed.

Polarization reversal in congruent and stoichiometric lithium tantalate

Switching kinetics has been compared in congruent (CLT) and stoichiometric (SLT) lithium tantalate by simultaneous recording of instantaneous domain patterns and switching current. A mechanism of fast domain kinetics in CLT driven by domain merging was revealed. The important information about the domain kinetics has been obtained by the statistical analysis of current noise in SLT. A model of jerky domain wall motion is proposed.

Kinetics of ferroelectric domain structure: Retardation effects

We review the experimental and theoretical investigations of the kinetics of ferroelectric domain structure in single crystals and thin films. The significant influence of the retardation of screening process on the evolution of the domain structure is pointed out and is demonstrated in various experimental situations.

Formation of Self-Similar Surface Nano-Domain Structures in Lithium Niobate Under Highly Nonequilibrium Conditions

Formation of the nanoscale domain structure in the surface layer as a result of pulsed UV laser irradiation has been studied experimentally in congruent single crystalline lithium niobate LiNbO3. The self-assembled structures have been classified and statistically analyzed. The structure is formed by growth, turning, and branching of domain rays strictly oriented along three Y+ directions. High-resolution microscopy shows that the rays represent the chains of individual needle-like nano-domains. The results of computer simulation of the domain structure formation using experimentally revealed rules are in good agreement with the experimental ones.