All in-fiber interferometric strain sensor based on cantilever Mach-Zehnder interferometer

A cantilever Mach-Zehnder interferometer (CMZI) strain sensor is proposed and its strain sensing characteristics are experimental demonstrated through investigating the dip wavelength and fringe visibility (FV) of its interference spectrum with the strain changing. While the strain increasing, the interference intensity dip wavelength appears blue shift, its FV shows increasing at the beginning, after achieves a maximin point, then decreases. At the range of its VF maximum, the wavelength versus strain presents the highest sensitivity. Therefore, using this CMZI sensor, high-sensitivity strain sensing can be obtained by controlling the sensing range near the maximum point of VF, and more large strain sensor range can be achieved by increasing the mismatching ratio of fiber cores. This device also can be applied to displacement, liquid level, refractive index and bending sensing.