Improving long-term temperature bias stability of an integrated optical gyroscope employing a Si₃N₄ resonator

Abstract

The presence of polarization noise generated by the waveguide resonator limits the performance of a resonant integrated optical gyroscope (RIOG). Using silicon nitride ( Si 3 N 4 ) to fabricate a waveguide with an ultralow-aspect-ratio can result in a resonator that only supports light transmission in a single-polarization state, suppressing polarization noise. We successfully fabricated a Si 3 N 4 resonator with a bending radius of 17.5 mm, a finesse ( F ) of 150, a quality factor ( Q ) of 1.54 × 10 7 , and a propagation loss of 1.2 dB/m. The Si 3 N 4 resonator was used to construct a double closed-loop RIOG that showed long-term bias stability (3600 s) of 13.2°/h at room temperature, 14.8°/h at 40°C, 21.2°/h at 50°C, and 23.6°/h at 60°C. We believe this to be the best performance reported to date for a Si 3 N 4 resonator-based RIOG. This advancement paves the way for the wider application of RIOGs.

Research progress of integrated optical gyroscope

“…Therefore, achieving a high Q value optical microcavity is essential for realizing highperformance IROGs. The preparation of the resonant cavity's materials and structures influences the Q value with commonly used materials, including SiO 2 [26][27][28][29][30] , SOI, CaF 2 , polymer and SIN [31][32][33] , and popular resonant cavity structures, including the optical waveguide ring resonator (WRR) and the whispering-gallery mode resonator (WGMR). The research progress on optical resonant cavities is presented in Table 2.…”

“…5(c)] are a promising alternative due to their high electro-optic coefficients, which can improve the modulation efficiency and overall performance of IROGs. In addition, long-range surface plasmon-polariton-doped [35,41] gain media can compensate for the propagation loss while reducing the pump noise compared to conventional optical waveguides, 2013 NIST 0.28 290 SIN [31] 2022 Beihang University 3.5 15.4 1.2 dB/m SIN [32] 2021 Beihang University 1.6 2.64 dB/m…”

Directions of development of optical gyroscopes based on passive ring resonators

“…Prototypes of optical resonator gyroscopes, constructed according to the described approach, allow to achieve a sufficiently high -higher than in micromechanics -accuracy of angular velocity measurement when using relatively compact resonators. For example, on the basis of a waveguide resonator made of silicon nitride with a diameter of 35 mm, a random wander value of 13.2 °/h, obtained as a result of Allan's dispersion analysis, was achieved with an integration time of 1 h [43], and with a resonator diameter of 60 mm -10.4 °/h at 2 h [34]. The best characteristics are achieved on the basis of fiber resonators: with a resonator diameter of 60 mm, the random wander value is 2.0 °/h with an integration time of 1 s and 1.23 °/h at 5 s [44]; if diameter is increased up to 120 mm, 0.37 °/h is achieved with an integration time of 1 s and 0.06 °/h in case of 370 s [21].…”

“…Also, the shape of the resonance curve is distorted by cross-polarization interference [5,61]. To reduce the magnitude of the error caused by polarization fluctuations, either stabilization of the position of the eigenfrequencies of one of the orthogonal polarizations in the middle of the intermode interval of the other polarization [14,[62][63][64] is required, or passive ring resonators with polarization-dependent losses, i.e., supporting only one polarization state, are used [28,35,43,65,66].…”

Design of ultra-compact thin-film lithium niobate edge coupler based on micro–nano structure

“…Typical mode field diameter (MFD) of a standard single-mode fiber (SMF) at 1550 nm is ∼10.4 µm [13], whereas the MFD of a single-mode TFLN waveguide is ∼1 µm, leading to large mismatches in mode sizes and mode effective indices. Due to the inherent mismatch, direct butt-coupling brings about high insertion loss and then the deterioration of device performance which will hinder TFLN devices from replacing conventional LN counterparts in practical applications especially for where the high on-chip optical power is considered as a priority such as integrated optical gyroscopes [14,15] and nonlinear optics [7,16]. Tapered lensed fibers are utilized to reduce this mismatch, however, the coupling loss is still as high as 5 dB/facet [10].…”