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Proceedings Paper

Highly sensitive rotation sensing based on orthogonal fiber-optic structures
Author(s): Yi Yang; Zi-nan Wang; Lian-yu Xu; Cui-yun Wang; Lei Jia; Xiao-qi Yu; Shan Shao; Zheng-bin Li
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Paper Abstract

In traditional fiber-optic gyroscopes (FOG), the polarization state of counter propagating waves is critically controlled, and only the mode polarized along one particular direction survives. This is important for a traditional single mode fiber gyroscope as the requirement of reciprocity. However, there are some fatal defects such as low accuracy and poor bias stability in traditional structures. In this paper, based on the idea of polarization multiplexing, a double-polarization structure is put forward and experimentally studied. In highly birefringent fibers or standard single mode fibers with induced anisotropy, two orthogonal polarization modes can be used at the same time. Therefore, in polarization maintaining fibers (PMF), each pair of counter propagating beams preserve reciprocity within their own polarization state. Two series of sensing results are gotten in the fast and slow axes in PMF. The two sensing results have their own systematic drifts and the correlation of random noise in them is approximately zero. So, beams in fast and slow axes work as two independent and orthogonal gyroscopes. In this way, amount of information is doubled, providing opportunity to eliminate noise and improve sensitivity. Theoretically, this double-polarization structure can achieve a sensitivity of 10-18 deg/h. Computer simulation demonstrates that random noise and systematic drifts are largely reduced in this novel structure. In experiment, a forty-hour stability test targeting the earth's rotation velocity is carried out. Experiment result shows that the orthogonal fiber-optic structure has two big advantages compared with traditional ones. Firstly, the structure gets true value without any bias correction in any axis and even time-varying bias does not affect the acquisition of true value. The unbiasedness makes the structure very attractive when sudden disturbances or temperature drifts existing in working environment. Secondly, the structure lowers bias for more than two orders and enhances bias stability for an order higher (compared with single axis result), achieving a bias stability of 0.01 deg/h. The evidences from all aspects convincingly show that the orthogonal fiber-optic structure is robust against environmental disturbance and material defects, achieving high stability and sensitivity.

Paper Details

Date Published: 8 September 2011
PDF: 7 pages
Proc. SPIE 8191, International Symposium on Photoelectronic Detection and Imaging 2011: Sensor and Micromachined Optical Device Technologies, 81910A (8 September 2011); doi: 10.1117/12.897122
Show Author Affiliations
Yi Yang, Peking Univ. (China)
Zi-nan Wang, Peking Univ. (China)
Lian-yu Xu, Peking Univ. (China)
Cui-yun Wang, Peking Univ. (China)
Lei Jia, Peking Univ. (China)
Xiao-qi Yu, Peking Univ. (China)
Shan Shao, Peking Univ. (China)
Zheng-bin Li, Peking Univ. (China)
State Key Lab. on Integrated Optoelectronics (China)

Published in SPIE Proceedings Vol. 8191:
International Symposium on Photoelectronic Detection and Imaging 2011: Sensor and Micromachined Optical Device Technologies
Yuelin Wang; Huikai Xie; Yufeng Jin, Editor(s)

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