Analysis of Quasi-Periodic Structural Defects in H:LiNbO₃ Layers

Abstract

Quasi-periodic structural defects on X-cut lithium niobate proton exchange waveguides surface were investigated. The structural defects are indicated as parallel bulge strips protruding above the surface up to 70 nm. It was found that under certain conditions proton exchange in pure benzoic and succinic acids leads to the formation of lamellar phase inclusions with crystal lattice deformation from 9.6·10 −3 to 22.0·10 −3 in waveguide layer, which induce the arising of the surface structural defects. It was proved that interstitial protons play a dominant role in a formation of these phase inclusions.