Optical fiber sensor has the advantages of high sensitivity,anti-electromagnetic interference,compact structure,corrosion resistance,small size,etc.It meets the needs of the intelligent era and is the appropriate choice for the future application of the Internet of Things system.With the further development of social intelligence,it has become the next research goal of optical fiber sensor to propose high sensitivity and high precision optical fiber sensor.This paper mainly studies several optical fiber multi-parameter sensors based on interference and anti-resonance,and describes the working principle,manufacturing process and corresponding experimental test results of the sensor.The main contents are as follows:(1)A sensor based on Michelson interferometer(MI)for simultaneous measurement of transverse load,refractive index(RI)and high temperature is proposed.The sensor is composed of a conical structure and an cap-shaped structure,where the conical structure serves as both the excitation unit and the coupling unit,and the cap-shaped structure is used to provide partial optical path difference and improve the spectral extinction ratio.The proposed sensor shows good stability in high temperature measurement.The transverse load,refractive index and temperature sensitivity are-1.412nm/N,200.07nm/RIU and 8.4 pm/℃ respectively.(2)A compact optical fiber sensor based on capillary silicon tube is proposed.A section of hollow silicon tube is fused at the end of the single-mode optical fiber,and then the end of the microtube is discharged to make it bubble,and then the two mechanisms of Fabry-Perot interferometer(FPI)and anti-resonance are combined in the hollow silicon tube.Because the FPI spectrum has a strong response to transverse load,while the anti-resonance structure spectrum has a strong response to temperature,two different sensing mechanisms lead to high contrast sensitivity values of temperature and transverse load(1.89pm/℃,190.48pm/N and24.93pm/℃,16.68pm/N).(3)An optical fiber sensor with cascaded anti-resonant reflecting waveguide(ARRW)and balloon structure for simultaneously measuring refractive index and temperature is proposed.The sensor is made by splicing the balloon structure based on Mach-Zehnder interferometer(MZI)and ARRW.The sensor also combines the MZI and anti-resonance mechanisms in the transmission spectrum.The spectra of the two mechanisms have different responses to the refractive index and temperature.Their response to refractive index and temperature is measured.The RI and temperature sensitivity of the sensor are 108.61 nm/RIU and 19pm/℃ respectively.Finally,the sensitivity coefficient matrix is established for demodulation.(4)An all-fiber MZI and FPI hybrid sensor for simultaneous temperature and transverse load sensing is proposed.The sensor consists of two single-mode fiber microspheres,one hollow fiber microsphere and two single-mode fibers.Two single-mode fiber microspheres in the sensor,one as the optical exciter and the other as the optical coupler,are made by arc discharge at the end of the fiber under the same conditions.An air cavity is formed in the hollow fiber microsphere,which can effectively measure the transverse load as FPI.The temperature sensitivity of the sensor in the range of 30~70℃ is 67pm/℃,and the transverse load sensitivity in the range of 0~3.92 N is 839.5nm/N.In short,the research in this paper can deepen people’s understanding of optical fiber sensing,especially multi-parameter sensing.These studies also have certain reference significance for the future development of optical fiber sensors. |