An optical fiber curvature sensor based on a twisted multimode fiber (MMF) sandwiched between two single-mode fibers (SMF) is proposed and investigated theoretically and experimentally. The measured transmission spectrum exhibits good agreement with theoretical predictions. Compared with a traditional single-mode–multimode–single-mode fiber structure sensor, the proposed configuration offers a higher average curvature sensitivity of –2.42 nm/m–1 over a curvature measurement range of 0–1.7390 m–1 and –7.09 dB/m–1 at an operating wavelength of 1537 nm. The temperature sensitivity of this sensor has been determined as 0.01 nm/°C over a wavelength range of 1535–1550 nm and circa 0.007 dB/°C at the wavelength of 1537 nm, over a measured temperature range of 21–121 °C.
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