Lithium niobate on insulator (LNOI) for micro-photonic devices

The state-of-the-art of high-refractive-index-contrast single-crystalline thin lithium niobate (LiNbO3) films as a new platform for high-density integrated optics is reviewed. Sub-micrometer thin LiNbO3 films are obtained by ion-slicing. They can be bonded by two different techniques to a low-index substrate to obtain lithium niobate on insulator (LNOI) even as wafer of 3 diameter. Different micro-and nano-structuring techniques have been used to successfully develop micro-photonic devices. To be specific, the fabrication and characterization of LNOI photonic wires with cross-section < 1 mu m(2), periodically poled LNOI photonic wires for second harmonic generation, electro-optically tunable microring resonators, free standing microrings for hybrid integration, and photonic crystal structures are described.