Periodically poled lithium niobate with submicrometer periodicity using electric-field poling technique
A series of monocrystalline lithium niobate (LN) thin films on low-resistivity silicon (LNOS) substrates, with thicknesses ranging from micrometers down to tens of nanometers, were prepared through chemical-mechanical polishing of pristine crystal films. By employing the electric-field poling technique, high-quality periodically poled lithium niobate (PPLN) structures with submicrometer periodicity were fabricated in these LNOSs, and full-thickness polarization reversal beneath the poling electrodes with a well-defined depth profile was achieved. The coercive field was found to follow the Kay-Dunn scaling law, while the lateral domain broadening generally increased with increasing film thickness, and it remained approximately constant across different electrode linewidths at a given film thickness. PPLN structures with periods ranging from 6 $μ$m down to 200 nm were demonstrated. These findings provide guidance for poling electrode design and lateral domain broadening pre-compensation, offering a practical route toward scalable domain engineering in LN thin films with promising potential for compact and highly integrated nonlinear photonic devices.