High sensitivity refractometer based on long-period fiber gratings with high diffraction order mode at turning point

摘要

We demonstrated fabrication of a long-period fiber grating (LPFG) in B-Ge co-doped single-mode fiber near the turning point, which coupled light from fundamental mode to high diffraction order cladding mode, and high refractive index sensitivities up to 853 nm/RIU in 1.337-1.427 and 3970.3 nm/RIU in 1.427-1.451 were achieved.