Study On Spectral Characteristics And Sensing Characteristics Of Graded Index Tilted Fiber Bragg Grating

Because of its own characteristics,Tilted Fiber Bragg Grating（TFBG）play a very important role in optical fiber sensing and other fields,making up for some shortcomings of ordinary fiber gratings,especially in terms of temperature,stress,etc.showing high sensitivity and high resolution.With the rapid development of fiber-optic sensing technology,it is of great significance for the research of tilted gratings.Especially for fiber gratings with special structures,refractive index-graded multimode fibers have been proposed^[1],but their research mainly stops.In terms of theory,etc.spectral characteristics and sensing characteristics have not yet been involved.Based on this paper,the theoretical properties,spectral characteristics and sensing characteristics of Graded Index Tilted Fiber Bragg Grating（GITFBG）are studied.The main research contents are as follows:1.The theory of the coupled mode of tilted fiber bragg grating is studied,including the structure of tilted fiber bragg grating,the preparation of tilted fiber bragg grating and the spectral coupling theory of tilted fiber bragg grating.2.Based on the tilted fiber bragg grating,the spectral characteristics of Graded Index Tilted Fiber Bragg Grating are theoretically analyzed using the coupled-mode theory of tilted fiber bragg grating.Changing the grating parameters such as tilt angle,grating period,grating length,refractive index modulation depth,core radius,cladding radius,and air layer radius.The spectral characteristics of GITFBG were studied in detail.The spectral characteristics of common tilted fiber bragg gratings were compared to analyze the advantages of GITFBG spectral characteristics.The results showed that the spectral characteristics of GITFBG were relatively There are certain advantages to ordinary tilted fiber bragg gratings.3.Study the temperature sensing characteristics of GITFBG.Based on the thermal response principle of temperature sensing,theoretically study the temperature sensing of TFBG.Research shows that the effective refractive index of the core is an important factor influencing the thermo-optic coefficient.Therefore,the GITFBG pair is studied.It is of great significance to improve the temperature sensing characteristics of TFBG.The research results show that the sensitivity of GITFBG temperature sensing is higher than that of TFBG,which improves the sensitivity of TFBG temperature sensing and has important research significance.