[1] [1] Zhou Jinlong, Dong Xiaopeng, Shi Zhidong. Theoretical and experimental investigation of bending sensitivity of the D-shape fiber Bragg gratings[J]. Acta Photonica Sinica, 2006, 35(11): 1734-1737.

[2] [2] Jiang Haili, Sun Weimin, Dong Mingwei, et al.. The theory of measuring bend-curvature based on three-core fiber Bragg grating[J].Applied Science and Technology, 2011, 38(6): 50-53.

[3] [3] Shao Liyang, Albane Laronche, Mateusz Smietana, et al.. Highly sensitive bend sensor with hybrid long-period and tilted fiber Bragg grating[J]. Optics Communications, 2010, 283: 2690-2694.

[4] [4] Shao Liyang, Xiong Lingyun, Chen Chengkun, et al.. Directional bend sensor based on re-grown tilted fiber Bragg grating[J]. Journal of Lightwave Technology, 2010, 28(18): 2681-2687.

[5] [5] Wang Yiping, Rao Yunjiang, Zeng Xiangkai. Bending characteristics analysis of long period fiber gratings using coupled mode theory[J]. Acta Photonica Sinica, 2002, 31(10): 1205-1208.

[6] [6] Cao Ye, Pei Yongwei, Tong Zhengrong. Simultaneous measurement of temperature and bending-curvature using a single local micro structured long period fiber grating[J]. Acta Physica Sinica 2014, 63(2): 024206.

[7] [7] Wang Yiping, Rao Yunjiang. A novel long period fiber grating sensor measuring curvature and determining bend-direction simultaneously[J]. IEEE Sensor Journal, 2005, 5(5): 839-843.

[8] [8] Guo Xinchun, Ning Tigang, Li Jing, et al.. Fiber-optic curvature sensor based on a core-offset structure[J]. Journal of Optoelectronics·Laser, 2014, 25(8): 1476-1450.

[9] [9] Gong Yuan, Zhao Tian, Rao Yunjiang, et al.. All-fiber curvature sensor based on multimode interference[J]. IEEE Photonics Technology Letters, 2011, 23(11): 679-681.

[10] [10] D Monzon-Hernandez, A Martinez-Rios, I Torres-Gomez, et al.. Compact optical fiber curvature sensor based on concatenating two tapers[J]. Optics Letters, 2011, 36(22): 4380-4382.

[11] [11] J R Guzman-Sepulveda, D A May-Arrioja. In-fiber directional coupler for high-sensitivity curvature measurement[J]. Optics Express,2013, 21(10): 11853-11861.

[12] [12] G L Yin, S Q Lou, W L Lu, et al.. A high-sensitive fiber curvature sensor using twin core fiber-based filter[J]. Applied Physics B-Lasers and Optics, 2013, 115(1): 99-104.

[13] [13] Geng Kaisheng, Guan Jianfei. Coupling characteristics of dual-core photonic crystal fiber with rectangular lattice[J]. Chinese J Lasers,2013, 40(3): 0305007.

[14] [14] Shi Weihua, Wu Jing. Photonic crystal fiber sensor based on surface plasmonic and directional resonance coupling[J]. Acta Optica Sinica,2015, 35(2): 0206002.

[15] [15] Wang Ying, Yang Minwei, D N Wang, et al.. Selectively infiltrated photonic crystal fiber with ultrahigh temperature sensitivity[J]. IEEE Photonics Technology Letters, 2011, 23(20): 1520-1522.

[16] [16] Darran K C Wu, Boris T Kuhlmey, Benjamin J Eggleton. Ultrasensitive photonic crystal fiber refractive index sensor[J]. Optics Letters,2009, 34(3): 322-324.

[17] [17] Zhang Chengdong, Zhou Xuanfeng, Chen Zilun, et al.. Low loss fusion splicing for seven-core photonic crystal fiber by selected air hole collapse technique[J]. Chinese J Lasers, 2014, 41(10): 1005004.

[18] [18] Chen H F, Wang Y, Wang D N. Selectively infiltrated photonic crystal fiber for directional bend sensing with large bending range[J]. IEEE Photonics Technology Letters, 2015, 27(5): 502-505.

[19] [19] D Chen, G Hu, X A Liu, et al.. Bending analysis of a dual-core photonic crystal fiber[J]. Progress in Electromagnetics, 2011, 120: 293-307.

[20] [20] T A Birks, F Luan, G J Pearce, et al.. Bend loss in all-solid bandgap fibres[J]. Optics Express, 2006, 14(12): 5688-5698.