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 LiNbO3 and the second one is a combination of FIB milling on a dep
osited 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 LiNbO3 substrates.
Nanostructures have become an attractive subject due to many applications, particularly the photonic bandgap effect observed in photonic crystals. Nevertheless, the fabrication of such structures remains a challenge because of accurate requirement co
ncerning regularity, shape, hole depth etc. of the structure. E-beam lithography permits a good control of dimensional parameters but needs a 1-step fabrication process. In our work, we have to combine traditional strip-load waveguides (SiO2/SiON/SiO2 on Si) and nanostructures whose dimension are totally different. This imposes a 2-step process where waveguides and nanostructures are successively fabricated. We have at our disposal different ways to characterize these nanostructures. A direct aspect control during and after FIB treatment can be achieved by FIB and SEM imaging. Scanning near-field optical microscopy (SNOM) is currently the most effective way to test guiding confinement in such surface structures by detecting the evanescent field.
