A simple and high-resolution POF displacement sensor based on face-coupling method

A Various fiber-optics displacement sensor methods are presented yearly, and a high-resolution displacement sensor with cost-effective and straightforward operation is an essential demand. Here, we present a novel sensor structure for displacement measurement. The design is based on a hole in the one fiber's core, whereas a second fiber is utilized to move inside the hole made on the first fiber. The optical power coupling varies with the distance between the first and second fiber. The drilling length is investigated, and the four sensors are fabricated with different displacement ranges. The results show drilling length influences sensor's range, and the sensor has a nanometer resolution of about 8.647 nm with a sensitivity of 11.56 nW/µm in between 0 µm and 2500 µm. Moreover, a maximum range of 4 mm is achieved. The designed structure could be used not only for displacement, but also for vibration, angle, and pressure sensor.