| Optical fiber sensing is a new technology rising rapidly with the appearance of quartz fiber and the development of optical fiber communication technology.Compared with the traditional electrical acoustic sensor,the acoustic sensor made of optical fiber has the characteristics of high sensitivity,small size,wide working band and no electromagnetic interference.In this paper,according to the existing research results,the fiber optic acoustic sensor based on the structure of the extrinsic Fabry-Perot interferometer was designed and manufactured with the single layer graphene film for the first time,and the following work was completed:(1)In this paper,the structure and properties of graphene film were studied,several common methods of graphene preparation were summarized,and the applications of graphene in energy storage,textile and gas detection sensing fields were introduced.(2)We proposed a EFPI acoustic sensor using single graphene film and studied the influence of F-P cavity length on sensor performance,then measured the sound pressure sensitivity curve and signal-to-noise ratio curve of the sensor while it was applied in air.When the frequency is 8kHz,the signal-to-noise ratio of the sensor reaches 29.5dB,and the sound pressure sensitivity of it attains-53.5dB re V/p.Pa when the frequency is 14kHz.(3)Since the orthogonal working point of the sensor would drift,we designed a measurement system that can automatically find the orthogonal working point by using Lab VIEW programming language,and then built an acoustic sensing system based on the direct measurement method of the orthogonal working point.(4)The performance of the acoustic sensor in underwater measurerment was investigated.Firstly,the frequency,amplitude and signal-to-noise ratio specialties of the acoustic sensor was measured and analyzed.Then,a comparative experimental system of acoustic sensor and standard hydrophone was built in the laboratory environment.By measuring and analyzing their sound pressure sensitivity and noise characteristics,it is concluded that the acoustic sensor has higher sensitivity and better noise characteristics.When the signal frequency is 20kHz,the sound pressure sensitivity of the acoustic sensor and the standard hydrophone are-173.4dB re V/Pa and-194.9dB re V/Pa.Compared with the standard hydrophone,we explored the acoustic sensor reception of the pulse sound signal,the fixed frequency sound signal and the linear transformation ultrasonic modulation signal with frequency range from 27 to 33kHz.And the data analysis shows that the acoustic sensor can be used in underwater acoustic communication. |
PDF Full Text Request