Surface domain inversion in LiNbO₃ by direct UV writing

Abstract

Ferroelectric domain inversion has been achieved on the +z and the -z faces of congruent undoped lithium niobate (LiNbO₃) single crystals by direct UV writing using a continuous wave (c.w.) frequency doubled argon ion laser (lambda = 244 nm). The width and the depth of the domains were observed to depend on the intensity and the spot size of the laser beam as well as the writing speed. The inverted domain structures were investigated by scanning electron microscopy (SEM), after HF acid differential etching, and piezoresponse force microscopy (PFM) [1]. UV laser inverted domains directly written on a multi domain crystal (PPLN) show that the PFM contrast of the UV written domains is lower as compared to the bulk domains (Fig. 1b). This indicates that the UV written domains are shallower than 1 micron because any domain depth exceeding ~ 1 micron in LiNbO3 would appear as bulk in PFM imaging. This is consistent with the extremely small absorption depth of << 1 micron at lambda = 244 nm [2].

Although shallow these UV laser written domains can be also remarkably narrow and also they can be fabricated onto any surface independent of the crystal orientation. Driving these surface domains deeper in the crystal by optical or electric field post processing is currently under investigation.

More information

Identifiers

ORCID for S. Mailis: orcid.org/0000-0001-8100-2670

ORCID for R.W. Eason: orcid.org/0000-0001-9704-2204

Catalogue record

Export record