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This work is devoted to the visualization and evolution of κ1-phase particles in annealed proton exchange (PE) waveguides. It is well-known that the presence of κ1-phase particles in optical waveguides leads to an increase in their optical losses and instability of operation. It has been found that precipitated κ1-phase particles propagate through the whole waveguide depth and have perpendicular orientation to the surface of the lithium niobate crystal. These results are important for fast quality control of annealed PE waveguides. [ABSTRACT FROM AUTHOR]

Domain growth and shape evolution during local switching under the action of biased conductive tip of scanning probe microscope were studied in Z + cut lithium niobate on insulator (LNOI) with 1 µm-thick SiO2 layer between LN film and grounded electrode. Piezoresponse force microscopy and confocal Raman microscopy were used for domain imaging. The domain shape evolution during switching was qualitatively reconstructed. The crucial role of discrete switching on the kinetics of domain growth was revealed. The stability of the switched domains was confirmed. The obtained knowledge will be used for creation of the periodical domain structures by local switching. [ABSTRACT FROM AUTHOR]

The creation of the periodical domain patterns with a submicron period in lithium niobate on insulator (LNOI) wafers is a key problem for nonlinear-optical applications, including second harmonic generation, backscattering optical parametric oscillator, etc. We have experimentally studied the domain formation and evolution during local polarization reversal in Zþ LNOI wafers with a metal bottom electrode. It has been shown that domain growth occurs by the formation of the spikes at the charged domain wall (CDW). The complicated shape of isolated domains with a jagged CDW has been revealed. The obtained weak domain-domain interaction has been attributed to effective bulk screening by charge injection. The revealed dependence of the domain sizes on humidity caused by the adsorbed water layer should be taken into account during periodical poling. [ABSTRACT FROM AUTHOR]