Research on intrinsic nonreciprocal errors in integrated optical gyroscopes based on thin-film lithium niobate chips

Thin-film lithium niobate (TFLN) exhibits great potential for application in integrated optical gyroscopes (IOG) owing to its excellent material properties. In this study, a combination of theoretical analysis and numerical simulation is used to model and study the endogenous nonreciprocal errors that may occur in IOGs based on TFLN photonic integrated circuits. The analysis indicates that the recoupling of the higher-order radiation modes is the main source of error. A TFLN chip is designed and fabricated to verify the accuracy of the proposed theoretical error model. The measured error value of the chip (0.1135π) is nearly consistent with the theoretical nonreciprocity error (0.125π). Furthermore, the TFLN chip-based IOG achieved bias instability of 0.26°/h under phase error compensation based on equivalent speed modulation. This study provides an important theoretical reference for the on-chip nonreciprocal error suppression of IOGs.