超声脉冲导入光纤光栅的动态光谱特性研究

提出超声以矩形脉冲波的形式轴向导入光纤光栅,分析超声脉冲作用于光纤光栅的机理；在此基础上,设计超声脉冲发生电路以及超声换能器,用高电压脉冲驱动堆栈式压电陶瓷产生沿光纤轴向的压缩脉冲,并通过符合声阻抗匹配的铝锥结构将脉冲幅值放大,高效地耦合进光纤光栅；采用CCD成像法高速采集光纤光栅在时域上的动态反射光谱,分析其时域上的光谱变化规律。结果表明:超声脉冲波长远大于光纤光栅长度时,超声脉冲导入的光纤光栅可有效搬移光谱,在脉冲作用时刻中心波长发生漂移。为超声脉冲与波分复用解调技术相结合提供参考。

Study on dynamic spectral characteristics of ultrasonic pulse into fiber Bragg grating

It is proposed that ultrasonic wave is introduced into fiber Bragg grating axially in the form of rectangular pulse wave.The mechanism of ultrasonic pulse acting on fiber Bragg grating is analyzed.On this basis,the ultrasonic pulse generator circuit and ultrasonic transducer are designed to drive the stack piezoelectric ceramics with high voltage pulse to generate compression pulse along the fiber axis,and then the pulse amplitude is amplified through the aluminum cone structure matching the acoustic impedance,which is coupled into the fiber grating efficiently.The dynamic reflection spectra of FBG in time domain were collected by CCD imaging method and the spectral variation law in time domain was analyzed.The results show that when the ultrasonic pulse is longer than the length of the fiber Bragg grating,the fiber Bragg grating (FBG) introduced by ultrasonic pulse can shift the spectrum effectively and shift the center wavelength at the moment of pulse action.It provides reference for the combination of ultrasonic pulse and wavelength division multiplexing demodulation technology.