Fabrication Of Temperature And Strain Sensor Based On Long-Period Fiber Grating And Its Experimental Study

In this paper,long-period fiber gratings are fabricated according to the filament heating method.The fiber gratings with different structures were fabricated by adjusting the parameters of the tapered taper.The long-period fiber gratings are fabricated by cascading with fiber-optic cones coating in metal and nonmetallic materials by using different methods.The long-period fiber gratings were fabricated with fiber bitaper and micro-taper to fabricate the MZI.Then the parameters of temperature and stress were measured for the long-period fiber grating sensors fabricated by the above-mentioned structures.Firstly,a long-period fiber grating was fabricated by the fused taper method.By adjusting the tapered parameters,a non-equal period long-period fiber grating was fabricated,and its temperature and strain sensing properties were measured.The strain sensitivity was as high as-9.8 pm/??,75.4 times of that of the ordinary CO₂-laser-notched long-period fiber grating.At the same time,an over-coupled long-period fiber grating with two loss peaks at 1534.2 nm and 1546.7 nm was fabricated by increasing the number of taper,and the two interfering peaks had different temperature sensitivity and strain sensitivity can be used for temperature and strain measurements simultaneously.Secondly,a long-period fiber grating was fabricated by the fused taper method.The effects of coating thicknesses of 50 nm,100 nm and 200 nm on the temperature sensitivity of long-period fiber gratings were studied.The results show that the temperature sensitivity of the LPFG decreases first and then increases and then decreases with the increase of gold film thickness,which is higher than the temperature sensitivity before coating.In this section,we also study the influence of the temperature of PDMS-coated on the gate region of long-period fiber gratings.The experimental results show that the temperature sensitivity can be effectively improved by coating the PDMS of LPFG.The temperature sensitivity of the LPFG is increased from 7 pm/°C to 191 pm/°C,which is increased about 27.3 times.Finally,we fabricated the Mach-Zehnder interferometer by using the long-period fiber gratings fabricated by the laboratory with the fiber bitaper and micro-taper,and use it for sensing.In the LPFG and fiber cone cascade process,there is only one interfering peak in the LPFG before cascade.After the cascade,there are many interference peaks.We select two interfering peaks for temperature and stress sensing.The experimental results show that the MZI can be used to measure the temperature and strain simultaneously.The temperature sensitivity is 83 pm/°C and the strain sensitivity is-2.6 pm/??.At the same time,we prepared the long-period fiber gratings and fiber bitaper cascade,the fiber bitaper made by the optical fiber welding machine,the method for the construction of MZI we also carried out temperature and strain sensitivity measurement,all obtained good experimental results.