Study of Multi-Channel Mode-Division Multiplexing Based on a Chalcogenide-Lithium Niobate Platform

A multi-channel mode-division multiplexing based on a chalcogenide-lithium niobate platform using chalcogenide films with adjustable refractive index is proposed, with the aim of overcoming issues with narrow bandwidth and large crosstalk in conventional multiplexers. An asymmetric directional coupler, employing chalcogenide-based thin-film modulation, was designed to realize the multiplexing and separation of TE1, TE2, and TE3 modes. Simulations show that the device is capable of obtaining an insertion loss of between 0.03 dB and 0.7 dB and a crosstalk of between -21.66 dB and -28.71 dB at 1550 nm. The crosstalk of the TE1, TE2, and TE3 modes is below -20.1 dB when accessing the waveguide output port in the 1500-1600 nm band. The proposed multiplexer is a promising approach to enhance the transmission capability of thin-film lithium-niobate-integrated optical paths.