Photonic crystal structures in ion-sliced LiNbO3 thin films

In these studies, annealed proton exchanged waveguides were used to confine the light to two dimensions and the photonic bandgap structures were fabricated by focused ion beam milling. These planar waveguides have a thickness of about 2 microns and a rather low refractive index contrast with respect to the bulk crystal, thus a high aspect ratio of air holes is required. In our approach we use 600-nm thick ion-sliced LiNbO₃ films bonded to a LiNbO₃ handling substrate using an adhesive polymer. Such LiNbO₃ films enable substantially stronger optical confinement and are ideally suited for the fabrication of photonic crystal slabs.