Search

We propose and experimentally investigate a spiral-polished single-multi-single-mode (SP-SMS) fiber sensor for the simultaneous measurement of strain and temperature. This special spiral shape on a multimode fiber is fabricated by a high-frequency CO2 laser, which excites higher order cladding modes in the interference process and leads to high strain sensitivity. Experimental results show that the strain sensitivity for the proposed structure in the transmission spectrum of two marked interference dips is − 17 pm/με and − 1 pm/με in the range of 0–600 με. Moreover, temperature sensitivities of 10 pm/℃ and 13.3 pm/℃ are obtained in the range of 30–150 ℃. Furthermore, the proposed sensor is inexpensive, is easy to fabricate and has a compact structure. [ABSTRACT FROM AUTHOR]

• A new type of waved core fiber structure is proposed and experimentally demonstrated. • The highest sensitivity of the sensor reaches 125.5 pm/με within the measuring range of 0–200 με. • Simultaneous measurement for strain and temperature can be achieved. • Compact in length and high mechanical strength. Strain and temperature, as two important parameters to evaluate structural health, is increasingly paid numerous attentions for years. In this article, we developed and experimentally tested a highly sensitive strain sensor based on SMS structure with waved core multi-mode fiber (MMF), which has ability to monitor temperature simultaneously. By introducing a section of bent-core fiber into the portion of MMF, the higher-order cladding mode is excited to enhance the sensitivity. Furthermore, the portion of bent-core displays significant influence on effective refractive index (ERI) of the MMF section as strain applied, which brings about higher strain sensitivity. The experimental results display that the highest sensitivity of the sensor reaches 125.5 pm/με within 0–200 με and the measuring range achieves 0–1200 με. By demodulating two dips, simultaneous measurement for strain and temperature is achieved by solving the equation matrix. This simple method displays minor influence on mechanical property and enhances the strain sensitivity considerably. It is strongly believed the proposed sensor brings about a competitive choice in engineering fields. [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]