Low-delay, high-bandwidth frequency-locking loop of resonator integrated optic gyro with triangular phase modulation

Abstract

A frequency-locking loop affects the bandwidth and output of the resonator integrated optic gyro (RIOG). A low-delay, high-bandwidth frequency-locking loop is implemented on a single field-programmable gate array with triangular phase modulation. The signal processing delay is reduced to less than 1 μs. The loop model is set up, and the influences of loop parameters on the bandwidth and unit step response are analyzed; the bandwidth of 10 kHz is obtained with the optimized loop parameters. As a result, the accuracy of the frequency-locking loop is reduced to 1.37 Hz (10 s integrated time). It is equivalent to a rotation rate of 0.005 deg/s, which is close to the ultimate sensitivity of the RIOG. Moreover, the bias stability of the RIOG is improved to 0.45 deg/s (10 s integrated time) based on the frequency-locking loop.

Integrated photonic chips based on Sagnac interference

“…By using a trapezoidal phase modulation technique to achieve real-time compensation for the output of the gyroscope, another PROG based on a silica RR with a diameter of ~6 cm has also been reported [134] (Figure 12(c)). The experimental demonstration verified that the deviation induced by noise and short-term drift was significantly reduced after the compensation, yielding a bias stability of ~0.09 deg/s with an integration time of 10 s over 3000 s. Other modulation techniques have also been investigated, either to improve the output from signal detection modules [146][147][148][149], or to reduce the backscattering [145,150,151] and backreflection [145,[152][153][154] noise.…”

Reduction of backscattering noise in a resonator integrated optic gyro by double triangular phase modulation

“…10, a bias stability of 0.22 deg ∕s (10 s integrated time) is achieved for 1 h. Compared the best long-term bias stability of 0.41 deg ∕s reported by our group based on the STPM [16], the long-term bias stability of the RIOG is greatly improved, demonstrating the effectiveness of the DTPM in backscattering noise reduction and performance improvement of the RIOG. However, a bias stability of 0.22 deg ∕s is still far from the theoretical accuracy of the RIOG [17]. It is mainly limited by polarization noise and backreflection noise.…”

Progress of Waveguide Ring Resonators Used in Micro-Optical Gyroscopes

“…When the laser frequency is locked to the CW frequency, the output of PD1 is a constant offset. However, the amplitude of the output of PD2 is proportional to the rotation rate [12]. Different phase modulation techniques have already been studied, such as the single-phase modulation technique [13][14][15], the double-phase modulation technique [16][17][18], and the hybrid-phase modulation technique [19,20].…”