Fabrication And Sensing Characteristics Research Of Microstructured Fiber-based Long Period Gratings

The microstructure fiber long period grating(MF-LPG) is a fiber device, which realize the core mode coupling to the cladding modes by introducing periodic refractive index modulation along the fiber length direction. The research based on the production and application of the MFLPG has attracted a greet attention of many scientists in recent years as the development of the microstructure fiber(MF). The transmission and sensing characteristics of the MF-LPG is defferent as the designment difference of the MF. By reading and researching a large number of relevant papers on MF-LPG, we carried out a detailed research on the MF-LPG production technology and sensing properties, successfully made long period fiber grating(LPG) on the Grapefruit and side-hole MF, and proved the sensing properties on the temperature, refractive index and bending. The concrete content of the pepar is as follows:1, In this paper, the development process and the research status of MFLPG is described by refering to the relevant literature and papers. Then, the MFLPG sensing characteristics is detailed descriped.2, The basic theory of MFLPG is analyzed. Considering the high power of the CO2 laser pulse when inscribering LPG into the MF, the cladding air hole of the MF would collapse. We shuld use the lacal coupled-mode theory to supplement the correction mode coupling theory. The coupling equation under the strong refraction index modulation is concluded and the resonance wavelength of the LPG is corrected, this section provides a theoretical basis for MF-LPG sensor application.3, The specific method especially CO2 laser pulse writing method for making MFLPG is described. In accordance with the CO2 laser pulse writing method, we successfully made lots of MFLPG on the grapefruit microstructure fiber and side-hole microstructure fiber, provide the experimental basis for the subsequent production of sensors.4, The sensing of temperature, refractive index and bending based on the grapefruit microstructure fiber LPG and the side-hole microstructure fiber LPG is experimented in this paper. We described the experimental methods, experiment principles, and the results we obtained.In this paper, the fiber sensors based on the MFLPG were studied by theory, grating producting and Characteristics study. The work carried out can improve the MF-LPG producting technology, and have a great significance on the sensors application of the MF-LPG.