RETRACTED: Study of a novel distributed vibration sensing system based on weak fiber Bragg gratings

Abstract

A novel vibration sensing system based on distributed weak fiber Bragg gratings is demonstrated to overcome the drawbacks of the conventional methods used in optical fiber sensing networking, such as insufficient quantity of multiplexed fiber Bragg gratings in wavelength-division multiplexing systems and low signal intensity in conventional time-division multiplexing systems. By mixing wavelength-division multiplexing technology and time-division multiplexing technology, the physical parameters of the fiber Bragg grating locations can be measured, but the distributed measurement along the whole optical fiber cannot be realized. The proposed novel sensing system detects the vibration events along the optical fiber link according to the signal’s intensity interference variation caused by the reflected signals with the adjacent weak fiber Bragg gratings. The position of the vibration events can be accurately determined by using time-division multiplexing technology. The experimental results verify that this novel system is more convenient for realizing vibration detection and demodulation along the whole optical fiber than before, and the system locating accuracy can be up to 20.5 m, with the capability of detecting various signals with 0.2 V of the driven signals as the bottom limit of voltage and a frequency range from 3 to 1000 Hz.