High-density integrated optics in ion-sliced lithium niobate thin films

Abstract

We report on the fabrication of ion-sliced single-crystalline lithium niobate thin films and realization of electro-optically tunable microring resonators and photonic bandgap structures for high-density integrated optics devices. Using a home-built high-resolution laser lithography system we structured microring resonators with a free spectral range of > 7 nm, a quality factor of up to 10'000, and a tunability of 1 pm/V at wavelengths around 1.55 μm. Moreover, we show that the fabricated microrings can be detached from the original substrate and transferred onto any host substrate. This opens new possibilities for building hybrid integrated optics devices based on lithium niobate microrings and laterally or vertically coupled waveguides of different materials. Combining the laser lithography patterning and focused ion beam milling we have also fabricated planar photonic crystals structures. Triangular lattices of holes with a diameter of 240 nm and a separation of 500 nm exhibit a photonic bandgap in the wavelength range from 1390 and 1500 nm with an extinction ratio of up to 15 dB.