Numerical Analysis Of Biased Mach-Zehnder Fiber Sensing Characteristics And Experimental Research

Biased Mach-Zehnder fiber optic sensors are phase-modulated fiber optic sensors.It not only have the characteristics of corrosion resistance,electromagnetic interference resistance,low cost,etc.,but also have the advantages of simple production and high sensitivity.This article introduces common phase-modulation fiber-optic sensor interference principles,and elaborates on the principle of biased Mach-Zehnder type interference.The expression of the wavelength under the minimum interference condition is deduced by interference theory,and the characteristic parameters affecting the position of the trough are obtained.In this paper,the beam propagation method is used to numerically analyze the transmission modes in the biased open-cavity single-mode Mach-Zehnder optical fiber sensor,the distribution of the internal light fields in each mode,and the structural characteristic parameters that affect the position of the transmission trough.The loss has a sinusoidal relationship,the offset depth has a linear relationship with the energy loss,the external refractive index has a linear relationship with the interference wavelength,and the sensitivity to the refractive index is 1050 nm / RIU.A cascaded double-biased Mach-Zehnder fiber-optic sensor model was established,and the influence of the offset length and external refractive index on its sensing characteristics was analyzed.Three types of biased Mach-Zehde fiber optic sensors,offset closed-cavity fine-core Mach-Zehnder fiber sensors,biased open-cavity multi-mode Mach-Zehnder fiber sensors,and biased open-cavity single-mode Mach-Zehnder fiber sensors were designed and fabricated using fiber fusion technology.Zengde fiber-optic sensors were tested for temperature and refractive index sensing characteristics.The sensitivity of the biased closed-cavity fine-core Mach-Zehnder fiber optic sensor to temperature is 65.76pm/ ?,and it is concluded that the sensitivity of the fiber-optic sensor to temperature is not related to the length of the fine-core fiber in the biased part,and the refractive index Sensing characteristic experiment,the sensitivity of the sensor to the refractive index is 234.69nm/RIU;The temperature sensitivity of the biased open-cavity multimode Mach-Zehnder optical fiber sensor is 56.03pm/?,and the refractive index is 518.09nm/RIU.The biased open-cavity single-mode Mach-Zehnder optical fiber sensor has a temperature sensitivity in aqueous solution is 162.86pm/?.The sensor's sensitivity to refractive index is 1043.09nm/RIU.