Refined Bridging of Microfiber Plugs in Hollow Core Fiber for Sensing Acoustic Vibrations

This letter develops a novel, ultracompact, insulated, and refined fiber-optic device that is based on a pair of tapered fiber plugs that are bridged in a tiny section of a hollow-core fiber (HCF). The proposed fiber plugs are fabricated by a single-mode fiber taper and are inserted into the HCF. Two taper plugs are bridged with each other inside the section of HCF by fusion splicing. The two ends of the HCF are fused to close the hollow core and form a rigid structure. When the fabricated sensor is utilized to sense acoustic vibrations, the tiny vibration sensing element is insulated and protected against the robust HCF, so it not easily damaged or polluted. The experimental results demonstrated favorable responses to vibrations.