Current Sensing Through an Optical Sensor Based on an Etched Side-Hollow Fiber Interferometer and Terfenol-D

This work presents a current sensor based on an in-fiber interferometer and Terfenol-D. The in-fiber interferometer was fabricated by etching the tip of a single-mode optical fiber (doped with germanium in its core) using hydrofluoric acid. After etching, the etched optical fiber was fused with another unetched fiber, resulting in a junction between the two fibers with a hollow region. This configuration created a Fabry-Perot interferometer within the optical fiber. After manufacturing the sensor, it was affixed to a piece of Terfenol-D using adhesive. Subsequently, the sensor underwent characterization with a DC magnetic field and an AC current ranging from 100 A to 800 A. The results showed that the sensor exhibited a sensitivity to a DC magnetic field of 8.5 pm/mT and a sensitivity of 35.8 1–1V/Arms for AC current. This sensitivity was found to be three times higher than that of a commercial Fiber Bragg Grating (FBG) sensor.