论文信息 - Compact optical fiber curvature sensor based on concatenating two tapers.

Compact optical fiber curvature sensor based on concatenating two tapers.

A low-loss, compact, and highly sensitive optical fiber curvature sensor is presented. The device consists of two identical low-loss fused fiber tapers in tandem separated by a distance L. When the optical fiber is kept straight and fixed, no interference pattern appears in the transmitted spectrum. However, when the device is bent, the symmetry of the straight taper is lost and the first taper couples light into the cladding modes. In the second taper, a fraction of the total light guided by the cladding modes will be coupled back to the fundamental mode, producing an interference pattern in the transmitted spectrum. As the fiber device is bent, visibility of the interference fringes grows, reaching values close to 1. The dynamic range of the device can be tailored by the proper selection of taper diameter and separation between tapers. The effects of temperature and refractive index of the external medium on the response of the curvature sensor is also discussed.

[1] Xiaoyi Bao,et al. Double-Pass In-Line Fiber Taper Mach–Zehnder Interferometer Sensor , 2010, IEEE Photonics Technology Letters.

[2] Zhaobing Tian,et al. Refractive Index Sensing With Mach–Zehnder Interferometer Based on Concatenating Two Single-Mode Fiber Tapers , 2008, IEEE Photonics Technology Letters.

[3] P. Caldas,et al. All-fiber Mach-Zehnder curvature sensor based on multimode interference combined with a long-period grating. , 2007, Optics letters.

[4] T A Birks,et al. Low bend loss in tightly-bent fibers through adiabatic bend transitions. , 2009, Optics express.

[5] Richard J. Black,et al. Tapered single-mode fibres and devices. I. Adiabaticity criteria , 1991 .

[6] O. Frazão,et al. Optical inclinometer based on a single long-period fiber grating combined with a fused taper. , 2006, Optics letters.

[7] Hwa-Yaw Tam,et al. Long-period fiber grating bending sensors in laminated composite structures , 1998, Smart Structures.

[8] X. Gu,et al. Wavelength-division multiplexing isolation fiber filter and light source using cascaded long-period fiber gratings. , 1998, Optics letters.