Research On The Integration Of Mechanical Microbending Preparation Of Long-period Fiber Grating And Composite Material Packagin

Long-period fiber grating has a wide range of applications in communication and sensing,and can be used as filters,fiber couplers,temperature and bending sensors,etc.However,some of its preparation technologies are expensive or difficult to accurately control.Mechanical micro-bending is the fastest and most practical method,but it is easy to bounce back in modulation depth.To solve the above problems,this paper combines plain braided prepreg with mechanical micro-bending technology,and proposes a synthesis method of long period fiber grating grating and packaging,focusing on the research of its pressure sensing characteristics.The main contents of the paper are as follows:Firstly,the fabrication method and application of long-period fiber grating were reviewed,the coupling mode of optical properties was discussed,the optical signal transmission model of mechanical micro-bending method was established,an analytical formula for optical information propagation in long-period fiber gratings based on micro-bending was derived.Secondly,design and manufacture glass fiber-long period fiber grating sensor.The general scheme of glass fiber-long period fiber grating was designed,the geometric and physical properties of glass fiber-long period grating prepreg were analyzed,and the mechanical template of long period grating was designed considering geometric parameters matching.The influences of the curing characteristics of glass fiber-prepreg,the position of fiber laying,the alignment form of glass fiber-upper template,pressure and temperature on the stability of grating were studied.Then,the resonance peak characterization and optimization of long period fiber grating were studied.The geometric and physical models of two mechanical templates with rectangular teeth and circular teeth were established respectively.The finite element simulation was carried out on the fiber grating process under the same displacement load.The stress curves corresponding to different grooving modulation depths on the fiber surface and the grooving surface topography were extracted and compared with the high-magnification microscopic images of actual bare fiber grooving.The results show that there are fewer stress cracks around the grooves of the glass fiber-long period fiber grating fabricated by the circular arc tooth template and it can withstand greater pressure load.Finally,the pressure sensing performance and temperature cross sensitivity of glass fiberlong period fiber grating were investigated.At constant temperature(room temperature),the pressure sensing coefficient of the prepared glass fiber-long period fiber grating was calibrated by different lateral pressure loading,and the range of the pressure sensor was obtained by experimental test.Based on the heat insulation function of nanoporous materials,the temperature of the glass fiber-long period fiber grating pressure sensor was inhibited by the method of nano indium tin oxide(ITO)with paste sheet structure,and the accurate measurement of pressure in a certain temperature range can be achieved by optimizing the technical parameters of coating.