| In recent years,with the continuous research of fiber grating,the application range of fiber grating is more and more widely used in the field of optical fiber communication and sensing.Optical fiber sensors have many advantages,including: anti-electromagnetic interference ability,reusability and small size,light weight,suitable for a variety of applications.In this paper,linear array six core fiber is taken as the research object.Based on the grating fabrication and the analysis of the sensing characteristics,a bending sensor that can be applied to the bending direction identification is proposed.The main contents are as follows:The use of phase mask method is briefly introduced in the writing of linear array six core fiber grating.The cores of the grating resonant wavelength show that: for similar size core,closer to the exposure direction,the greater the refractive index modulation and the larger the center wavelength of the grating.For different size of the core,the larger the core diameter is,the greater the center of the grating wavelength.Axial stress,temperature and bending measurements were performed on the array fiber gratings.The experimental results show that the sensitivity of array six-core fiber grating core is about 1.0pm/με and the sensitivity to temperature is ~ 10pm/°С,which are similar to that of standard single-mode fiber grating.Bending characteristics are direction-dependent and are limited by experimental devices that measure bending sensitivity are carried out only in two directions of 0° and 90°.The 0° direction is the vertical alignment of the core and the 90° direction is the core horizontal arrangement.When the bending direction is 90°,the difference of the bending sensitivity of different cores is small.When the bending direction is 0°,the Bragg resonance peaks in different cores show blue shift and red shift in the meantime.The theoretical simulation of the supermodes properties of the array six-core fiber is carried out,and the theoretical simulation and experimental analysis of the excitation coefficients between the single mode fiber and each core of the fiber are carried out.The results show that the energy of the core of the transmission supermode is higher and the match with the theoretical result is better.And the matching degree of smaller core size,which transport the supermode,is larger than that of larger size core,the maximum possibility may be the influence of the core size.Array five core fiber grating core sensitivity of the stress is also about 1.0pm/με or so.Sensitivity to temperature measurements of the two processes of heating and cooling is also presented,the results show that the sensitivity of the heating process slightly larger than the cooling process. |
