[1] [1] KOO K P, KERSEY A D. Bragg grating-based laser sensors systems with interferometric interrogation and wavelength division multiplexing［J］. Journal of Lightwave Technology, 1995, 13(7): 1243-1249.

[2] [2] KIM Y J, PAEK U C, LEE B H. Measurement of refractive index variation with temperature by use of long-period fiber gratings［J］. Optics Letters, 2002, 27(15): 1297-1299.

[3] [3] WANG Dong-yuan, SUN Ming-ming, JIN Yong-xing, et al. Simultaneous measurement of curvature and temperature based on optical fiber sensor［J］. Acta Photonica Sinica, 2015, 44(11): 1106004

[4] [4] FENG Ding-yi, QIAO Xue-guang, ALBERT J. Off-axis ultraviolet written fiber Bragg gratings for directional bending measurements［J］. Optics Letters, 2016, 41(6): 1201-1204.

[5] [5] ZHOU Quan, ZHANG Wei-gang, CHEN Lei, et al. Bending vector sensor based on a sector-shaped long-period grating［J］. IEEE Photonics Technology Letters, 2015, 27(7): 713-716.

[6] [6] JIN Yong-xing, CHAN C C, DONG Xin-yong, et al. Temperature-independent bending sensor with tilted fiber Bragg grating interacting with multimode fiber［J］. Optics Communications, 2009, 282(19): 3905-3907.

[7] [7] FRAZAO O, VIEGAS J, CALDAS P, et al. All-fiber Mach-Zehnder curvature sensor based on multimode interference combined with a long-period grating［J］. Optics Letters, 2007, 32(21): 3074-3076.

[8] [8] GONG Hua-ping, YANG Xiao, NI Kai, et al. An optical fiber curvature sensor based on two peanut-shape structures modal interferometer［J］. IEEE Photonics Technology Letters, 2014, 26(1): 22-24.

[9] [9] MONZON H D, MARTINEZ R A. Compact optical fiber curvature sensor based on concatenating two tapers［J］. Optics Letters, 2011, 36(22): 4380-4382.

[10] [10] LIN Qiao, CHEN Liu-hua, LI Shu, et al. Optical fiber bending sensor based on Michelson interferometer［J］. Acta Photonica Sinica, 2011, 40(2): 251-254.

[11] [11] SALCEDA D G, VAN N A, ANTONIO L J E, et al. Compact fiber-optic curvature sensor based on super-mode interference in a seven-core fiber［J］. Optics Letters, 2015, 40(7): 1468-1471.

[12] [12] HARHIRA A, LAPOINTE J, KASHYAP R. High sensitivity inline fiber Mach-Zehnder interferometer bend sensor using a twin core fiber［C］. SPIE, 2010, 7653: 765315.

[13] [13] RONG Qiang-zhou, QIAO Xue-guang, ZHANG Jing, et al. Simultaneous measurement for displacement and temperature using fiber Bragg grating cladding mode based on core diameter mismatch［J］. Journal of Lightwave Technology, 2012, 30(11): 1645-1650.

[14] [14] ZHOU Wen-jun, ZHOU Yan, DONG Xin-yong, et al. Fiber-optic curvature sensor based on cladding-mode Bragg grating excited by fiber multimode interferometer［J］. IEEE Photonics Journal, 2012, 4(3): 1051-1057.

[15] [15] YANG Shen, SUN Hao, YUAN Liu-tong, et al. Refractive index and temperature sensor based on cladding-mode Bragg grating excited by abrupt taper interferometer［J］. Chinese Optics Letters, 2013, 11(12): 120604.

[16] [16] HAN Ming, GUO Fa-wen, LU Yong-feng. Optical fiber refractometer based on cladding-mode Bragg grating［J］. Optics Letters, 2010, 35(3): 399-401.

[17] [17] WANG Yi-ping, RICHARDSON D, BRAMBILLA G, et al. Intensity measurement bend sensors based on periodically tapered soft glass fibers［J］. Optics Letters, 2011, 36(4): 558-560

[18] [18] GIINDER M J, MACPHERSON W N, MCBIDE R, et al. Bend measurement using Bragg gratings in multicore fiber［J］. Electronics Letters, 2000, 36(2): 120-121.