Light-induced domain engineering in ferroelectrics

Abstract

Fabrication of periodically inverted domain patterns in ferroelectric materials such as lithium niobate has been widely researched for the realisation of applications as diverse as quasi-phase-matched (QPM) non-linear devices, electro-optic Bragg deflectors, photonic band-gap structures, and piezoelectric devices such as micro-resonators, atom traps and micro-cavities. In order to overcome the limitations associated with E-field poling, we have been investigating the feasibility of a relatively simple single-step technique, which exploits the interaction of intense laser light with ferroelectric lithium niobate to engineer domains at micron and sub-micron scale-lengths. Some light-assisted poling experiments which take advantage of the ultraviolet light-induced transient change in the coercive field of the illuminated ferroelectric material to transfer a patterned light distribution into an equivalent domain structure in bulk crystals have already been reported for lithium tantalate and lithium niobate crystals. In this letter we report a direct optical poling technique that employs pulsed ultraviolet laser light to induce surface domain inversion in undoped lithium niobate in a single step. We further characterize the laser modified domain manipulated crystals using differential chemical etching and scanning force microscopy (SFM)