Study On Vibration Signal Measurement Based On DBR Fiber Laser

Distributed Bragg Reflector fiber lasers’ sensitivity in beat frequency change makes it widely used in the sensing area,such as temperature,stress,ultrasound,magnetic field,bending and vibration measurement.At present,when DBR fiber laser is used as a sensing device,most of the researches are about the measurement of static physical quantities such as pressure,current,bending and so on.Few researches have been done on the measurement of dynamic signals like vibration.Therefore,this dissertation extends the beat frequency characteristics of DBR fiber lasers from the measurement of static signals to the dynamic signals based on the previous research results and proposes a new vibration measurement method based on DBR fiber lasers.Firstly,this dissertation reviews the research status of the measurement of vibration in the field of optics at home and abroad,and discusses the vibration measurement methods commonly used in optical field;Secondly,this dissertation studies the principle of the beat frequency detection of DBR fiber laser,and discusses the theory of DBR fiber laser in measuring static physical quantity(temperature,pressure,ultrasound,bending,etc.)and the common vibration measurement methods in optical field.Finally,based on the work of previous chapters,a new scheme of vibration measurement based on DBR fiber laser is proposed in this dissertation.The scheme directly packaged the DBR fiber laser as a sensor to suffer the vibration,with the advantages of simple structure,convenient measurement,easy demodulation,accurate measurement results and a series of experiments were carried out to demonstrate the correctness of the program.The results show that the vibration measurement scheme based on DBR fiber laser proposed in this paper has good vibration measurement capability.The frequency measured by this method almost equals to the actual vibration frequency,with the error less than 1Hz.It also has a good distinction in vibration amplitude and the sensitivity is up to 60kHz/μm.The DBR fiber laser can be directly used to measure the low-frequency vibration signal after proper encapsulation.The scheme provides a new idea for vibration detection and measurement.