Four-Channel Mode (de)Multiplexer Based on Y-Propagation Hybrid Silicon and Lithium Niobate Thin Films Waveguides

The hybridization of mono-crystalline silicon and lithium niobate thin films (Si-LNOI) combines the remarkable electrical properties and mature micro-nano processing technologies of Si, as well as the excellent optical properties of LN, which provides a new material platform for integrated photonics. Mode (de)multiplexers is one of the key passive components in photonic integrated circuits, and can significantly improve the transmission capacity. In this study, four-channel mode (de)multiplexer was demonstrated on Si-LNOI, which was based on cascade asymmetrical directional coupler structure along the Y-axis of LN (for various applications access the large electric-optic coefficient and χ⁽²⁾ nonlinear-optical coefficient). At 1500–1600 nm, the fabricated mode (de)multiplexer had a low excess loss (EL) of less than 1.5 dB and a low inter-modal crosstalk (CT) of less than −13.6 dB. The clear eye diagrams at 14 Gbps demonstrated excellent data communication capability of mode (de)multiplexer. This study provides guidelines for the development of multimode photonics on Si-LNOI.