Study On Optical Fiber For Surface Acoustic Wave

Fiber optic sensor technology is one of the forefronts of key technologies ofindustrialization and information technology. On the one hand, due to frequent naturaldisasters, there is growing emphasis on infrastructure security issues. On the other hand,petrochemical, automobile, shipbuilding, aircraft manufacturing industry is rapidly growing;they urgently need an effective means to detect a variety of equipment, the security situation.Purpose of this paper is to find a way, the fiber optic sensor technology combined with surfaceacoustic wave theory, to detect the material properties.This article describes the basic principles of surface acoustic wave; surface acousticwave spread in isotropic media and anisotropic media, the underlying nature is elaborated.The model is build by using the finite element method which fiber and surface acoustic waveinteract each other, Buried within the tested material for optical fiber sensing element straincharacteristics is analyzed through the theory, is calculated by the finite element simulation.Optical detection of surface acoustic wave output signal to interfere with the mathematicalform is derived by Bessel functions; the output signal is divided into two time-invariant andtime-varying part, and output the results were to start. Impacting fiber optic sensor for surfaceacoustic wave signal measurement factors are explained from a theoretical point of view.SAW frequency is measured with a Sagnac, Michelson, and Mach-Zehnder interferometer ofthree typical fiber optic sensors. And signal is simulated. From the experimental point of view,the theoretical derivation of the conclusion is verified.Finally, the elastic modulus of solid material nature is described; some typical solidelastic modulus of the range is summarized. According to the principle of sound wavepropagation in solids, the relationship between the elastic coefficient and the speeds iscalculated, including the Young’s modulus, shear modulus, bulk modulus, and Poisson’s ratio.Two experimental systems, including dual-Sagnac fiber-optic sensors and fiber opticMichelson sensor is established, surface acoustic wave and longitudinal wave velocity ismeasured with a fiber-optic sensors spread in solid materials. Then the parameters to bemeasured are calculated. Preliminary experimental results proved that the solid material withoptical fiber sensors for measuring the elastic constants is entirely feasible. This paperprovides a new approach for the detection of surface acoustic wave signal by fiber-optic sensor.