Wide measurement range vector curvature sensor based on single stress applying fiber

To solve the limited measurement range of existing optical fiber curvature sensors, a vector curvature sensor, constructed using the single stress applying fiber (SSAF)-based Sagnac interferometer is presented and experimentally validated. The experiment results demonstrate that the sensor enables curvature measurement over a wide measuring range from 11
$\mathrm{m}^{-1}$
to 26.8
$\mathrm{m}^{-1}$
with the sensitivity of -2.6 nm/ m -1 in upward direction and 1.6
$\text{nm}/\mathrm{m}^{-1}$
in downward direction. Compared with existing sensors, the measurement range has been greatly improved.