Application of a novel spatial non-reciprocal phase modulator in fiber optic gyroscope

doi:10.1016/j.yofte.2020.102258

Optical Fiber Technology

Volume 58, September 2020, 102258

https://doi.org/10.1016/j.yofte.2020.102258 Get rights and content

Highlights

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A new non-reciprocal modulator is proposed and developed.
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Phase modulation structure provides a new phase modulation solution for FOG system.
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Good temperature stability and test accuracy of the FOG system are demonstrated.

Abstract

Based on the primary electro-optic effect of lithium niobate crystal and combined with a polarizer and a Faraday rotator, a novel spatial non-reciprocal phase modulator design scheme suitable for Sagnac loop structure is proposed. On the one hand, this structure fundamentally eliminates the influence of eigenfrequency on the modulation mode of the system, and improves the sensitivity and accuracy of the system. On the other hand, experiments show that this phase modulator has good modulation characteristics and temperature stability. Applying this phase modulator to a fiber optic gyroscope (FOG), the experimental results are in good agreement with the theoretical analysis, which proves the correctness and feasibility of the structure. It provides new options for the use of phase modulators for test instrument such as fiber-optic gyroscopes and current transformers, and provides a way of thinking to promote the development of fiber-optic gyroscopes to high precision.

Introduction

The fiber-optic gyroscope is at the heart component of the inertial navigation system [1]. With the characteristics of large measurement range, high accuracy, small size, high reliability, and long life, it has been the object of inertial technology. In recent years, with the improvement of the measurement accuracy, volume and applicable scope of fiber-optic gyroscopes, experts and scholars have conducted in-depth research in many aspects such as optical devices, optical path structures, modulation circuits, noise and errors, and process design [2] to improve the working performance of fiber-optic gyroscopes. Among them, phase modulation [3] is an indispensable study object in the development of fiber-optic gyroscopes.

The original fiber-optic gyroscope used an all-fiber scheme and utilized a PZT phase modulator [4] for phase modulation. This phase modulator with poor amplitude-frequency characteristics, is difficult to control the volume, and cannot achieve modulation of high-frequency signals; Later, the double Y structure of the straight waveguide was developed [1], but due to the low reliability and high cost of this method, the Y waveguide phase modulator was born. At present, Y waveguides are widely used as phase modulators for fiber-optic gyroscopes and current transformers. However, the traditional Y waveguide can only propagate one mode of light, so the generation of the bias phase and the feedback phase is controlled by the transit time of the fiber loop. When there is a deviation between the intrinsic frequency of the fiber loop and the modulation frequency [5], [6], a modulation error will occur [7], resulting in a decrease in system accuracy [8]. When detecting signals, if the transit time is short, a high sampling frequency is required, which will make the system's noise bandwidth larger and more susceptible to interference. Generally, the parameters of the fiber-optic ring are set to ensure the required time delay, but this method will add extra volume and cost.

This paper presents a new type of phase modulator for fiber-optic gyroscope. It closely matches the characteristics of the optical rotation device and the lithium niobate crystal to reach the modulation effect in the same time domain and different spatial domains. In principle, the limitation of the intrinsic frequency on the system is avoided and a more free sensitivity and dynamic range are obtained [7]. At the same time, the signal demodulation method is simplified, and the system reliability is improved and reduced while simplifying the signal demodulation method, improving system reliability and reducing costs, making up for the shortcomings of traditional Y-waveguide phase modulators relying on system transit time for phase modulation. These advantages will drive phase modulators towards versatility and selectivity.

Section snippets

Principle analysis of novel spatial non-reciprocal phase modulator

The structure of the new phase modulator is shown in Fig. 1, which is composed of polarizer $P_{1}$ , Faraday rotator $F_{cw}$ (45° clockwise rotation), LiNbO₃ electro-optic crystal, Faraday rotator $F_{ccw}$ (45° counterclockwise rotation), polarizer $P_{2}$ . Among them, lithium niobate crystal adopts the scheme of applying voltage to the y direction and transmitting light in the z direction. The linearly polarized light transmitted in the forward direction travels along the lithium niobate crystal y to the

Modulation experiment and analysis

In order to verify the application effect of the new non-reciprocal phase modulator in fiber-optic gyroscope, the physical diagram of the experimental device is shown in Fig. 4. The experimental light source is a semiconductor laser with a wavelength of 1310 nm and an adjustable output power. The fiber ring used is made by the quadrupole winding symmetrical method, with an inner diameter of 26 mm, an outer diameter of 36 mm, and a length of 200 m. Designed a Labview host computer, using a light

Conclusions

This article introduces the new phase modulator in detail. Starting from the unique optical rotation structure of the phase modulator, it demonstrates that the phase modulator can simultaneously modulate the light waves transmitted in two different directions, which overcomes the modulation of traditional Y-waveguide phase modulator disadvantages of intrinsic frequency limitation. Theoretical analysis and experimental verification show that this phase modulator has the advantages of good

CRediT authorship contribution statement

Yuefeng Qi: Conceptualization, Writing - review & editing, Funding acquisition. Xin Zhang: Methodology, Data curation, Visualization, Writing - original draft. Yantao Wang: Supervision. Mingjun Wang: Investigation, Validation. Zimeng Liu: . Chenbo Gong: Formal analysis. Yanyan Liu: Project administration, Validation.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Grant Nos. 61735011), the Science and the Key Research and Development Program of Hebei Province (Grant Nos. 19251703D), and the Local Science and Technology Development Projects of the Central Committee (Grant Nos. 19941708G).

References (25)

P.Y. Chien et al.
Fiber sensor based on frequency tracking in a phase-modulated fiber-optic gyroscope
J. Opt. Commun.
(1995)
Y. Zhou et al.
Novel design of multiplier-less FFT processors
J. Signal Process.
(2007)
W. Li et al.
Photonic generation of microwave pulse using a phase-modulator-based sagnac interferometer and wavelength-to-time mapping
J. IEEE Photonics Journal.
(2014)
C.Y. Ge
Research on the Influence of Y Waveguide on the Performance of Fiber-optic Gyro
(2010)
W. Wang
Interferometric Fiber Optic Gyroscope Technology
(2010)
Y. F. Qi, Q. Feng, J Zhang, X. Zhang, M. J. Wang, D. S. Tian, W. Li, Design of fiber-optic current transformer based on...
C. Geng, W. Luo, Y. Tan, H. Liu, J. Mu, X. Li, Experimental demonstration of using divergence cost-function in SPGD...
H. Chen, S. Zhang, H. Fu, B. Zhou, N. Chen, Sensing interrogation technique for fiber-optic interferometer type of...
K. Ono, M. Nishikawa, Y. Nishiura, Phase-modulated fiber-optic gyroscope with wide dynamic range and linear scale...
H. Zhang et al.
High-current-sensitivity all-fiber current sensor based on fiber loop architecture
J. Opt. Express.
(2012)

J. Amet et al.

Experimental evidence of enhanced electro-optic control on a lithium niobate photonic crystal superprism

J. Appl. Opt.

(2010)

S. X. Shi, Physical Optics and Applied Optics. M. Xi’an: Xidian University Press, 2014, pp....

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View full text

Application of a novel spatial non-reciprocal phase modulator in fiber optic gyroscope

Highlights

Abstract

Introduction

Section snippets

Principle analysis of novel spatial non-reciprocal phase modulator

Modulation experiment and analysis

Conclusions

CRediT authorship contribution statement

Declaration of Competing Interest

Acknowledgements

J. Opt. Commun.

J. Signal Process.

J. IEEE Photonics Journal.

Research on the Influence of Y Waveguide on the Performance of Fiber-optic Gyro

Interferometric Fiber Optic Gyroscope Technology

High-current-sensitivity all-fiber current sensor based on fiber loop architecture

J. Opt. Express.

Experimental evidence of enhanced electro-optic control on a lithium niobate photonic crystal superprism

J. Appl. Opt.