Low Crosstalk Waveguide Crossing for Lithium Niobate Integration Application

With the development of thin-film lithium niobate (TFLN) in the field of integrated photonics, it has become particularly important to achieve large-scale integration. The multi-channel waveguide crossing which has low crosstalk and loss can enhance the integration density and routing flexibility. Due to the anisotropy of lithium niobate, we propose and demonstrate 2×2 waveguide crossing with different waveguide sizes based on the self-imaging. The waveguide crossing based on 600 nm X-cut TFLN. The crosstalk of those crossings are less than-33.31 and-30.81 dB, respectively, in C-band. The corresponding insertion loss minima are about 0.094 dB and 0.356 dB, respectively.