The authors demonstrate how slow group velocities that are easily attainable at the band edge of photonic crystals can drastically enhance the electro-optical effect on tunable photonic crystal components. This property opens up the possibility of microsized nonlinear devices with low power requirement. In this letter we show how these possibilities for enhancement of nonlinear effects have been used to fabricate a 13×13 µm2 sized lithium niobate photonic crystal intensity modulator that shows an enhanced electro-optic effect 312 times bigger than the one predicted by the classical Pockels effect for an equivalent device in bulk material

We report on two novel ways for patterning Lithium Niobate (LN) at submicronic scale by means of focused ion beam (FIB) bombardment. The first method consists of direct FIB milling on LiN bO3 and the second one is a combination of FIB milling on a deposited metallic layer and subsequent RIE (Reactive Ion Etching) etching. FIB images show in both cases homogeneous structures with well reproduced periodicity. These methods open the way to the fabrication of photonic crystals on LiN bO3 substrates.

http://link.aip.org/link/?APPLAB/87/241101/1In this letter, we investigate the feasibility of tunable lithium niobate (LiNbO3) photonic crystals. The optical response through a LiNbO3 photonic structure is theoretically determined in order to obtain a photonic band gap with optimal tunability. We show by means of a finite difference time domain simulation that the optimal lattice parameters can provide a Deltalambda=7 nm shift in the photonic band gap for a Deltan=0.01 variation of the refractive index with an extinction ratio of –22.5 dB. The fabrication process and the optical characterization of these novel photonic crystal structures are also reported. The extinction ratio of the measured photonic band gap is lower than –12 d

We report an electro-optically tunable photonic crystal linear cavity etched on a 200 nm lithium niobate waveguide ridge. The photonic crystal cavity and the ridge are both fabricated on a 1 μm thin film of lithium niobate obtained by smart-cut technology. The photonic crystal, of area 4x0.8 μm2, has been engineered to work in a slow light configuration so that the electro-optic effect is 20 times more important than in bulk material.

In this paper, the development of piezoelectric transducers based on periodically poled ferroelectric domains is investigated. Optical quality Z-cut LiNbO3 wafers have been used for the fabrication of test devices operating in the range of 10–100 MHz. The fabrication process is detailed and the characterization results are reported. A very good agreement between theoretical predictions achieved by periodic finite element analysis and experiments is observed, allowing for a precise identification of the excited modes. Elliptically polarized modes as well as quasipure longitudinal waves are pointed out. The robustness of the devices to lapping and polishing operations has also been tested. The possible utilizations of such transducers are discussed to conclude the paper. ©2007 American Institute of Physic

International audienceWe report on an active two-dimensional lithium niobate photonic crystal (PhC) driven by stationary Rayleigh surface acoustic waves. The configuration relies on two interdigital transducers that modulate the refractive index through the acousto-optical effect. Highly efficient, compact acousto-optical PhCs with an active length of only 13 μm and a driving electrical power of 20 mW have been fabricated and characterized. Experiments show that an enhancement factor of the elasto-optical interaction of the order of 61 is obtained thanks to slow light effects in the PhC

We report the development of a quick process for fabricating lithium niobate ridge waveguides with smooth walls, aspect ratios larger than 500 and side wall verticality of 88°. The method is based on optical grade dicing, and allows the fabrication of ridges with a top width of 1µm and a depth of more than 500µm. Smart-cut ridge waveguides and strongly confined proton exchanged ridge waveguides are demonstrated. We show that the method enables the fabrication of ridge waveguides with propagation losses as low as 0.5dB/cm. A new fabrication process is thus proposed for the fabrication of optical components with enhanced acousto-optic, electro-optic or nonlinear interactions. The high aspect ratios open opportunities toward the development of 3D photonic components in thin films of LiNbO 3 , and toward hybrid integration of LiNbO 3 components.

International audienceWe report an electro-optically tunable filter using a lithium niobate photonic crystalcavity configuration with an efficient optical guiding geometry. The compact device (5.5 μm × 2.8 μm) was made on a hybrid waveguide combining an annealed proton exchange waveguide and a ridge waveguide realized by focused ion beam with vertically deposited electrodes. Due to the slow light and nonlinear effect in lithium niobate photonic crystal, experimental results show an enhanced tunability of ∼0.56 nm/V. This compact tunable photonic crystalcavity demonstration opens the path for the development of micro and nano-scale low-power driving active photonic devices