We introduce a highly compact fiber-optic Fabry-Pérot refractive index sensor integrated with a fluid channel that is fabricated directly near the tip of a 32 μm in diameter single-mode fiber taper. The focused ion beam technique is used to efficiently mill the microcavity from the fiber side and finely polish the end facets of the cavity with a high spatial resolution. It is found that a fringe visibility of over 15 dB can be achieved and that the sensor has a sensitivity of ∼1731 nmRIU (refractive index units) and a detection limit of ∼5.78 × 10-6 RIU. This miniature integrated all-in-fiber optofludic sensor may find use in minimal-invasive biomedical applications.
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