Simultaneous measurement of strain and temperature with a few mode fiber

A novel detection scheme for simultaneous measurement of strain and temperature based on a few mode fiber (FMF) is proposed in this paper. The FMF is designed to support only LP01 and LP02 modes. The propagation constant difference between LP01 and LP02 mode, Δβ, has a maximum, which corresponding to the critial wavelength (CWL) in the transmission spectrum. The two peaks that closest to the CWL from both sides, Left Peak 1 and Right Peak 1, response with different sensitivities to strain and temperature variations. Therefore, the FMF can simultaneously demodulate the strain and temperature using these two peaks and the calculated value of strain and temperature using the sensor matrix agrees well with the actual values in the experiment. This dual-parameter sensor has advantages of simple and stable configuration, easy fabrication, compact size and relative high sensitivities, which can be widely used in practical applications.