High sensitivity strain sensors based on single-mode-fiber core-offset Mach-Zehnder interferometers

Mach-Zehnder interferometers make highly sensitive sensors of physical quantities based on the accumulated phase difference between two or more optical paths. In this work, the application of single-mode-fiber core-offset Mach-Zehnder interferometers as strain sensors is reported. Three in-line modal Mach-Zehnder interferometers were manufactured by splicing three pieces of single mode fiber with well-defined offset and orientation of the cores and a well-defined length of its middle section. These interferometers were characterized as strain sensors, and a maximum sensitivity of 7.46 pm/µε was obtained over the linear range 0-1754 µε. Compared to other strain sensors, the ones reported in this work achieve a high sensitivity using inexpensive single mode fiber and an easy manufacturing process.