Wavelength division multiplex based on fiber optical vibration sensor array

An array sensing technique of fiber grating for the dynamic strain measurement is demonstrated in this paper. The technique is based on unbalanced Mach-Zehnder interferometer which use a 3 × 3 coupler. Wavelength division multiplex (WDM) technique is introduced to multiplex fiber grating sensors. The cross talk among the different channels is measured, and vibration signals from 3 serious FBGs is obtained at same time. The reasons why the changes of environment and changes of power intensity do not influence the measurement are discussed. And signals with high frequency can also be measured. Not only high-frequency, high-sensitivity measurement can be achieved, and the measurement is not affected by power intensity, but also the phase relationships among the different sensing position can be obtained.