Paralleled Sagnac interferometer and Mach-Zehnder interferometer for enhanced measurements sensitivity based on Vernier effect

In this paper, Vernier effect was experimentally excited through paralleling Sagnac interferometer (SI) and Mach-Zehnder interferometer (MZI). SI was fabricated using a 38 cm long panda-shaped polarization maintaining fiber in the Sagnac loop, while MZI was made through tapering a single mode fiber. Experimental results showed that the measurement sensitivities of strain and temperature based on the paralleled SI and MZI were 51.97 pm mu epsilon -1 and 2.94 nm degrees C-1 respectively, which were enhanced by about three times than based on an individual SI whose measurement sensitivities of strain and temperature were 18.24 pm mu epsilon -1 and 0.98 nm degrees C-1 correspondingly. Theoretical analysis of the single interference and paralleled interferences were verified by the experimental results. The proposed sensor shows the advantages of simple in fabrication, high sensitivity, and good hysteresis, is a strong competitor in monitoring the strain and temperature.