A unique all-fiber interferometric sensor was proposed and successfully demonstrated efficient low-refractive-index liquid sensing in the range from 1.33 to 1.37, which is compatible with those of bio-liquids. A special silica coreless optical fiber with an open V-groove was used as an optical sensing medium, which provided a high sensitivity for a minute liquid volume in the nanoliter scale. The V-groove fiber (VGF) was serially concatenated between two single-mode fibers (SMFs). The LP01 mode guided along the input SMF excited the higher-order modes in the VGF to generate multimode interference, whose spectrum was transmitted through the output SMF. A single liquid droplet with volume of
Quan Chai, Hyeonwoo Lee, Seongjin Hong, Yongsoo Lee, Junbum Park, Jianzhong Zhang, Kyunghwan Oh. Nanoliter liquid refractive index sensing using a silica V-groove fiber interferometer[J]. Photonics Research, 2019, 7(7): 792