Highly sensitive curvature sensor based on a multicladding fiber sandwiched dual no-core fibers structure.

In this paper, we present a simple, compact, and highly sensitive optical fiber curvature sensor. It consists of dual no-core fibers for coupling energy from the lead-in single-mode fiber (SMF), and recoupling the energy into the lead-out SMF. The sensing section is constituted by multicladding fiber with a length of 5 cm. In the experiment, the spectrum shows a blueshift, and the energy corresponding to the resonant wavelength shows a cosine series with a bending of the sensing segment. The curvature sensitivity around the wavelength of 1550 nm shows -39.02 nm/m(-1) within the curvature range from 0.3 to 2.14 m(-1). The temperature sensitivity is 78.2 pm/°C in the temperature range of 10 °C-60 °C. It implies the possibility of temperature measurement.