Coupled optoelectronic oscillator based strain sensor with extended measurement range

Abstract

We have proposed and experimentally demonstrated optical fiber strain sensor with a extended dynamic range based on a coupled optoelectronic oscillator (COEO). The oscillation frequency equals to the mode spacing of the laser that is affected by the axial strain applied to the cavity. Thus, we can evaluate the strain by measuring the oscillation frequency shift. A proof-of-concept experiment is carried out. The dynamic range is up to 10000 μ. The sensitivity is 13.8 Hz/μ for 2700 MHZ. The COEO has a maximum frequency drift range of ±303.907 Hz for 2700 MHz within 90 minutes, and the corresponding measurement error is ±20 μ . The scheme has the advantages of high precision and high speed.