Research on the Vibration Sensor Based on Microfiber Loop Resonator

The aim of this article is to present the manufacturing and characterization possibilities of a vibration sensor based on a microfiber loop resonator, chosen in the context of developing low-cost sensor systems. The technological part of the article includes a description of the process for producing a microfiber loop resonator using the Fiber Optic Taper Element Technology setup, and the optimization of parameters, such as the diameter of the tapered optical fiber and the number of loop twists (ranging from 1 to 3). The experiments carried out included testing the sensors’ responses to vibrations and performing spectral analysis, during which the time responses of the proposed sensors were presented and analyzed. The Q-factors were calculated as 2.4 × 10³ for one twist, 3.8 × 10³ for two twists, and 4.1 × 10³ for three twists. The best results for sensing applications were obtained using a microfiber loop produced on a tapered optical fiber with a diameter of approximately 11 μm and two, three twists. The test results confirmed that the sensitivity (the highest power differences) of the microfiber loop resonator to vibrations was higher than a straight tapered optical fiber and increased with the decreasing fiber diameter and a higher number of twists. The main conclusion is that microfiber loop structures have potential in optical fiber sensor applications.