Research On Mach-Zehnder Interferometer Sensor Based On All Single Mode And All Panda Fibers

Compared with traditional electrical sensors,optical fiber sensors have attracted much attention and research in recent years due to their advantages of high temperature resistance,electromagnetic radiation resistance,small size and light weight.The optical fiber Mach-Zehnder?M-Z?interferometer is a very important fiber sensor because of its novel structure and high sensitivity.Previous methods for fabricating optical fiber M-Z interferometers are:fiber tapering,femtosecond laser writing,and CO₂ laser writing and so on.These methods can produce fiber optic sensors with very delicate structures and different characteristics,but they often require very expensive writing equipment,such as femtosecond lasers and CO₂ lasers,or the mechanical strength of the fabricated devices is weakened,such as fiber tapering.Therefore,in this paper,we mainly used the melt discharge technology to prepare all-fiber M-Z interferometer.First,we used a fiber fusion splicer to prepare an all single-mode fiber M-Z interferometer sensor based on"peanut"and"J"type structure cascaded.The preparation of the device only requires a fiber fusion splicer,and the preparation efficiency is high;at the same time,the diameter of device is maintained at the original fiber diameter,and the high mechanical strength is retained.Then the temperature and strain response characteristics of the device were studied.The experimental results showed that the interference peak wavelength and intensity were sensitive to both temperature and strain.The wavelength of the interference peak shifted toward the long wave direction as the temperature increases,showing a red-shift characteristic.The temperature sensitivity of the wavelength was 52.9pm/?in the range of temperature from 40?to 80?,and the temperature sensitivity corresponding to the intensity was-0.0125dB/?.The interference peak wavelength shifted toward the short wave direction as the strain increases,showing a blue-shift characteristic.The wavelength strain sensitivity was-11.44pm/??in the strain range from 113.23??to 792.64??,and the strain sensitivity corresponding to the intensity was 0.0152dB/??.Experiments have shown that an all single-mode fiber M-Z interferometer can simultaneously measure temperature and strain using a single resonant peak.Afterwards,the refractive index response characteristic of the device was studied.It was found that the wavelength and intensity of the interference peak varied with the change of the refractive index.The corresponding refractive index sensitivities in the range of RI from 1.3451 to 1.3806 were-15.479nm/RIU and-121.24dB/RIU,respectively.Based on the above results,we prepared an all Panda fiber M-Z interferometer based on a misaligned structure cascaded using a special fiber.Studying the response characteristics of temperature and strain sensing,the experimental results showed that the interference peak wavelength of the all Panda fiber M-Z interferometer changed linearly with temperature and strain,but the intensity did not change linearly with temperature and strain.The temperature sensitivity corresponding to the wavelength in the range of 40?to 90?was 29.13pm/?;the strain sensitivity corresponding to the wavelength in the range of strain from 113.23??to 792.64??was-9.82pm/??.Therefore,the all Panda fiber M-Z interferometer cannot achieve simultaneous measurement of temperature and strain using a single resonant peak.