Design of a New Type of Optical Fiber Infrasound Sensor and Its Usage in Karst Geological Exploration

Abstract

In this study, the demand of optical fiber (OF) sonic sensor is analyzed, and a composite OF infrasound sensor is proposed aiming at the detection demand of low-frequency infrasound waves in specific occasions. With this sensor, the polymer thin film and the aluminum soil can be combined to form a kind of composite film, the ECF/P interferometer can be formed between the end faces of the ferrule of the OF FC contact, the sensor head of the OF ECF/P infrasound sensor system is fabricated and then packaged. The designed OF infrasound sensor is used in the construction of a wireless sensor network (WSN) for karst geological exploration. The structure of the WSN includes the SimpliciTI communication network protocol, ADF7021 RF transceiver chip, STM32 processor chip, etc. New types of environment from karst can be sampled with this WSN. During the test, the performance of the composite OF infrasound sensor is analyzed at the beginning. The acoustic sensitivity of up to –136.73 dB re 1 V/μPa can be obtained in the low frequency infrasound range (1–20 Hz); the WSN based on the composite OF infrasound sensor has lower power consumption and faster networking speed. In addition, it can realize signal cover in karst areas without public mobile cellular networks, and send the information collected by the sensor to the data center, thus proving the fiber optic sound wave sensor designed in this study is successful and helpful for the geological prospectors to monitor the environment.