Thin Film Lithium Niobate Microring Modulators for Analog Photonics
Lithium niobate (LiNbO3) has been long regarded as the most attractive material for electro-optic modulation for high-performance optical communication systems of up to 100 GHz, as well as for its superior second-order optical non-linearity. The weakly confined LiNbO3 waveguides formed by diffusion or implantation of dopants do not lend themselves to high-level chip integration. One key novel technology proposed here, and supported by preliminary results, is developing submicron LiNbO3 films on silicon substrates using ion implantation, surface activation and wafer bonding. The technology allows to make optical waveguides with high index-contrast of ~2.2/1.5. To avoid direct etching of the hard LiNbO3 material, a loaded ridge waveguide formation is proposed. Based on these two technologies, LiNbO3 microring modulators with wide modulation bandwidth and compact size are proposed for analog photonics applications. The modulators can achieve good linearity, high power and wide modulation bandwidth simultaneously and have a very small size.