Demodulation of wavelength-encoded optical fiber sensor signals using fiber modal interferometers

摘要

Abstract: We propose the use of modal interferometers to detect changes in the transmitted signal in high-finesse extrinsic Fabry-Perot interferometric cavities for real-time, absolute strain and temperature measurements. The short length of the cavity ensures a large free spectral range of the resulting output Airy pattern and by tracking the wavelength shift of one peak, the applied perturbation may be completely characterized. The same principle is also proposed to detect the signal reflected from fiber Bragg gratings for strain and temperature sensing. The relative merits and demerits of this demodulation scheme are discussed and preliminary experimental results are presented.!12