Fiber Loop Mirror Using a Small Core Microstructured Fiber for Strain and Temperature Discrimination

In this work, a fiber loop mirror for the simultaneous measurement of strain and temperature is presented. The loop mirror contains a section of a small core microstructured fiber characterized for strain and temperature sensing. Due to the small core geometry and using a small section length, the structure presents high birefringence and also intermodal interference. The spectral response of this configuration shows the presence of three interferometers. One of them corresponds to the interference of light that propagates in the fast and slow axes (group birefringence) and the others are associated with the interference of light in the two lowest order spatial modes in each of the fiber eigenaxis. These interferometers present distinct sensitivities to strain and temperature for different wavelengths.