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In this paper, a novel torsion sensor based on Mach-zehnder interferometer (MZI) is proposed and demonstrated. The proposed sensor is fabricated by the single-mode fiber (SMF) and multi-mode fiber (MMF) shear splicing, further employing CO 2 laser to modulate the MMF surface into triangular prism form. And compare the number of different triangular prism pairs structure on torsion sensitivity. By increasing the number of triangular prism pairs effectively improve the torsion sensitivity. The experimental results show that in the range of 0–9.617 rad/m, the highest sensitivity fiber sensor can be obtained with a sensitivity of 3.3133 nm/(rad/m). Meanwhile, the temperature characteristic of the sensor is investigated, which presents a sensitivity of 21.67 pm/℃ in the range from 30 ℃ to 100 ℃. Therefore, the temperature crosstalk is 0.0065 (rad/m)/℃, which results in a low temperature crosstalk. In addition, the structure also has the advantages of low cost and simple manufacturing process. [Display omitted] • A high sensitive torsion optical fiber sensor is achieved by using CO 2 laser polished method. • The highest torsion sensitivity of the UITP-SMS reaches 3.3133 nm/(rad/m). • A low-temperature crosstalk is obtained, which is 0.0065 (rad/m)/℃. • Low cost, simple structure and easy fabrication. [ABSTRACT FROM AUTHOR]

We propose and experimentally demonstrate an optical fiber torsion sensor based on symmetrically polished single-multi-single mode (SP-SMS) fiber structure. The polished structure enhances the torsion response effectively, which is fabricated by a high-frequency CO 2 laser. Experimental results show that the high sensitivity of the proposed torsion sensor reaches 1.032 nm/(rad m−1) in the range from − 10.261 rad/m to 10.261 rad/m. Meanwhile, the temperature response of the sensor is also investigated, which is 21 pm/°C in the range from 30 °C to 150 °C. Moreover, the structure has the features of low cost, simple fabricating method and small temperature crosstalk. Schematic diagram of the symmetrically polished SMS fiber structure (SP-SMS). The geometrical shape of the sensor is prepared by a high-frequency CO 2 laser, which enhances the torsion sensitivity of the structure. The structure achieves a high sensitivity of 1.032 nm/(rad m−1). Meanwhile, small temperature-torsion crosstalk of 0.03 (rad m−1)/°C is achieved. The fabricating method of the structure has the advantages of is non-contact and scalable. Hence, the proposed structure provides a new idea to the design of the fiber torsion sensor. [Display omitted] • The highest torsion sensitivity of the SP-SMS reaches to 1.032 nm/(rad m−1). • The low temperature-torsion crosstalk is obtained, which is 0.03 (rad m−1)/°C. • Low cost, compact structure and easy fabrication. [ABSTRACT FROM AUTHOR]

A simple fiber sensor for dual-parameters measurement of curvature and temperature is proposed and demonstrated, which is prepared by sandwiching a section of deformed multimode fiber (D -MMF) into two single-mode fibers (SMFs). This structure is processed by CO 2 laser etching and hydrogen-oxygen flame melting method. The micro-bent core of MMF constructs in-fiber composite interference, which effectively improves the bending sensitivity of the structure. It is found that the dips at 1310 nm and 1376 nm in the interference spectrum show different curvature and temperature responses. The curvature sensitivities of two dips are up to − 23.2 nm/m−1 and − 11.64 nm/m−1 in the range of 0–1.1733 m−1. Moreover, the temperature sensitivities of two monitored dips are − 52.1 pm/°C and − 19.7 pm/°C, respectively. [Display omitted] • A high sensitive curvature optical fiber sensor is achieved by using CO 2 laser polished method and hydrogen-oxygen flame heating stretching. • The highest curvature sensitivity of the D-MMF reaches to − 23.2 nm/m−1 • Dual parameters measurement of curvature and temperature. • Low cost, compact structure and easy fabrication. [ABSTRACT FROM AUTHOR]