Localized active-cladding optical fiber bend sensor

We present the design and fabrication of a novel fiber optic multiparameter bend sensor. Unlike current intrinsic fiber optic multiparameter bend sensors that depend on multiple cores or multiple fibers, the new sensor is based on three circumferential active-cladding point modifications on a single optical fiber at specific axial locations along the length of the fiber. A commercial 30-W CO2 laser is used to cut three point modifications in the plastic cladding of the fiber. Each of the three defects is filled with fluorophores (quantum dots) with different peak emission wavelengths. A 405-nm laser (operating at 10-mW) is used to excite the quantum dots, while a spectrometer, coupled to the fiber, measures the emission signals of each of the three fluorophores simultaneously. Results show that bending direction and degree of curvature at a single localized modification region can be expressed as a function of the three fluorescence intensities. © 2010 SPIE