Hongchen Jiao

Suppression of backreflection error in resonator integrated optic gyro by the phase difference traversal method

The phase difference traversal (PDT) method is proposed to suppress the backreflection-induced error in resonator integrated optic gyro (RIOG). Theoretical analysis shows that the backreflection-induced zero-bias fluctuation is periodical and sine/cosine-like. By forcing the phase difference between the CW and CCW incident light to traverse the interval [0, 2π] repeatedly and rapidly enough, the fluctuation can be low-pass filtered and, hence, the backreflection-induced error can be effectively suppressed. A RIOG apparatus is built up, with multi-wave hybrid phase modulation to traverse the phase difference and in-phase modulation to set the operation point. A short-term bias stability of 0.0055 deg/s and a long-term bias stability of 0.013 deg/s are successfully demonstrated which, to the best of our knowledge, are the best results reported to date for the buried-type silica waveguide ring resonator-based RIOG.

Reduction of angle random walk by in-phase triangular phase modulation technique for resonator integrated optic gyro

In a resonator integrated optic gyro (RIOG) employing a planar optical waveguide ring, the interference between backreflected light and signal light will not only cause nonreciprocal drift of cw and ccw resonance frequencies, but also deteriorate the original signal waveform of the resonator output. If contra-phase triangular phase modulation (CPM) were applied, a cosine-like ripple, whose initial phase varies randomly, would superpose upon the quasi-square waveform of the resonator output, resulting in increment of noise and the gyros angle random walk (ARW). Therefore, in-phase triangular phase modulation (IPM) technique is proposed and used to eliminate the ripple and improve the waveform quality of the resonator output, and the gyros ARW is obviously reduced from 3 to 0.8 deg/h1/2 compared to that of CPM. This enlightens a new way to design the scheme of backreflection/backscattering suppression.

Analysis of polarization noise in transmissive single-beam-splitter resonator optic gyro based on hollow-core photonic-crystal fiber

We realize a transmissive single-beam-splitter resonator optic gyro based on a hollow-core photonic-crystal fiber (HCPCF), utilizing a micro-optical coupler formed by pairs of lenses and one filter, which is a new type of resonator fiber optic gyro based on the HCPCF (HC-RFOG). We build a mathematical model of the polarization noise based on the transfer function of this novel transmissive single-beam-splitter resonator. We construct a HC-RFOG and simulate and validate the effects of polarization noise on the gyro system. In addition, we apply an effective method to suppress the polarization noise and prove its efficacy through experiments. The bias stability of the gyro system is successfully improved from 25 °/h to 2 °/h, which indicates a remarkable advance of performance of HC-RFOG.

Research on polarization noise of hollow-core photonic crystal fiber resonator optic gyroscope

Hollow-core photonic crystal fiber (HCPCF) resonator optic gyroscope is an important direction of high accuracy fiber optic gyroscope. The development and application of HCPCF has provided broad prospect for the research of resonator fiber optic gyroscope (RFOG). The HCPCF can restrict light to propagate in the fiber core filled with air/vacuum based on photonic band-gap effect. Compared with conventional polarization maintaining fiber based RFOG (PM-RFOG), the HCPCF based RFOG (HC-RFOG) has great potential to achieve lower nonreciprocal bias and better environment adaptability. The polarization noise, which is one of the main noise sources in the RFOG, is modeled and simulated in this paper. The resonance curves of RFOG with two polarization modes excited are presented, and the polarization noises caused by fiber parameters are calculated. The comparison of polarization noises between HCPCF resonator and polarization maintaining optical fiber (PMF) resonator are carried out by numerical simulation. The polarization features of the HCPCF resonator and conventional PMF resonator are experimentally characterized. The analysis result shows that the polarization stability of HCPCF resonator can be two orders of magnitude lower than that of the conventional PMF resonator. Therefore, the HCPCF resonator has evidently superiority in reducing polarization noise and improving gyro performance. The captive tests based on the HCPCF RFOG system are realized, and a bias stability in the range of 2.5°/s is successfully demonstrated.

Transmissive single-beam-splitter resonator optic gyro based on a hollow-core photonic-crystal fiber

We propose a transmissive single-beam-splitter resonator optic gyro based on a hollow-core photonic-crystal fiber (HCPCF), which is a new regime of resonator fiber optical gyro based on an HCPCF, a hollow-core resonator fiber optical gyro (HC-RFOG), for the first time, to the best of our knowledge. We evaluate the transfer function of this novel transmissive single-beam-splitter resonator, and the resonance characteristics are simulated to optimize the element parameters. We utilize a micro-optical coupler formed by pairs of lenses and one filter to realize this novel resonator. Our approach yields a fineness of 12 and a transmittance of about 5%. Based on this novel resonator, we construct a HC-RFOG, and we simulate and analyze the effects of polarization noise on the gyro system. In addition, an effective method to suppress polarization noise is employed, and the efficacy of this method is confirmed by experiments. A bias stability of 1.3°/h is successfully demonstrated, which is the best result reported to date, to the best of our knowledge, for RFOGs based on an HCPCF resonator.

Research of single-polarization hollow-core photonic crystal fiber active resonator

A feasible program of single-polarization active resonator using hollow-core photonic crystal fiber is proposed in this paper. The basic structure of HCPCF active resonator is designed, and the influence of polarization mode dispersion on the detection accuracy is analyzed with a solution being put forward using single-polarization HCPCF. Then the cross structure of photonic crystal fiber is designed, modeled and simulated by finite element method (FEM) at the wavelength of 632.8nm, and the mode field distribution in the cross-section is obtained. By designing the core size of photonic crystal fiber properly, a polarization extinction ratio of 8.4dB is achieved; therefore single-polarization propagation can be realized in the HCPCF, resulting in suppression of polarization mode dispersion of resonator and improving the theoretical gyroscope detection limit. This research is of great guiding significance to the development of HCPCF RLG.