[1] [1] H. J. Patrick, C. Chang, and S. T. Vohra, “Long period fiber gratings for structural bending sensing,” Electronics Letters, 1998, 34(18): 1773–1775.

[2] [2] Y. Jin, C. Chan, X. Dong, and Y. Zhang, “Temperature-independent bending sensor with tilted fiber Bragg grating interacting with multimode fiber,” Optics Communications, 2009, 282(19): 3905–3907.

[3] [3] L. Shao, L. Xiong, C. Chen, A. Laronche, and J. Albert, “Directional bend sensor based on re-crown tilted fiber Bragg grating,” Journal of Lightwave Technology, 2010, 28(18): 2681–2687.

[4] [4] M. Deng, C. Tang, T. Zhu, and Y. Rao, “Highly sensitive bend sensor based on Mach-Zehnder interferometer using photonic crystal fiber,” Optics Communications, 2011, 284(12): 2849–2853.

[5] [5] D. Monzon-Hernandez, A. Martinez-Rios, I. Torres-Gomez, and G. Salceda-Delgado, “Compact optical fiber curvature sensor based on concatenating two tapers,” Optics Letters, 2011, 36(22): 4380–4382.

[6] [6] O. Fraz o, J. Viegas, P. Caldas, J. L. Santos, F. M. Araújo, L. A. Ferreira, et al., “All-fiber Mach-Zehnder curvature sensor based on multimode interference combined with a long-period grating,” Optics Letters, 2007, 32(21): 3074–3076.

[7] [7] S. Zhang, W. Zhang, S. Gao, P. Geng, and X. Xue, “Fiber-optic bending vector sensor based on Mach-Zehnder interferometer exploiting lateral-offset and up-taper,” Optics Letters, 2012, 37(21): 4480–4482.

[8] [8] Z. Ou, Y. Yu, P. Yan, J. Wang, Q. Huang, X. Chen, et al., “Ambient refractive index-independent bending vector sensor based on seven-core photonic crystal fiber using lateral offset splicing,” Optics Express, 2013, 21(20): 23812–23821.

[9] [9] J. Zheng, P. Yan, Y. Yu, Z. Ou, J. Wang, X. Chen, et al., “Temperature and index insensitive strain sensor based on a photonic crystal fiber in line Mach-Zehnder interferometer,” Optics Communications, 2013, 297(15): 7–11.

[10] [10] Y. Geng, X. Li, X. Tan, Y. Deng, and X. Hong, “Compact and ultrasensitive temperature sensor with a fully liquid-filled photonic crystal fiber Mach-Zehnder interferometer,” IEEE Sensors Journal, 2013, 14(1): 167–170.

[11] [11] T. Allsop, R. Reeves, D. J. Webb, I. Bennion, and R. Neal, “A high sensitivity refractometer based upon a long period grating Mach-Zehnder interferometer,” Review of Scientific Instruments, 2002, 73(4): 1702–1705.

[12] [12] J. Villatoro, V. Minkovich, V. Pruneri, and G. Badenes, “Simple all-microstructured-optical-fiber interferometer built via fusion splicing,” Optics Express, 2007, 15(4): 1491–1496.

[13] [13] O. Fraz o, S. F. O. Silva, J. Viegas, J. M. Baptista, J.L. Santos, J. Kobelke, et al., “All fiber Mach-Zehnder interferometer based on suspended twin-core fiber,” IEEE Photonics Technology Letters, 2010, 22(17): 1300–1302.

[14] [14] B. Dong, J. Hao, and Z. Xu, “Temperature insensitive curvature measurement with a core-offset polarization maintaining photonic crystal fiber based interferometer,” Optical Fiber Technology, 2011, 17(3): 233–235.

[15] [15] J. R. Guzman-Sepulveda and D. A. May-Arrioja, “In-fiber directional coupler for high-sensitivity curvature measurement,” Optics Express, 2013, 21(10): 11853–11861.

[16] [16] Z. Wu, Y. Liu, Z. Wang, T. Han, S. Li, M. Jiang, et al., “In-line Mach-Zehnder interferometer composed of microtaper and long-period grating in all-solid photonic bandgap fiber,” Applied Physics Letters, 2012, 101(14): 141106-1–141106-4.