In-Line Abrupt Taper Optical Fiber Mach–Zehnder Interferometric Strain Sensor

A Mach–Zehnder interferometer with two abrupt single-mode fiber tapers is simulated, constructed, and demonstrated. The interferometer has an insertion loss of 5 dB and an extinction ratio over 15 dB. The interferometer is tested as a strain sensor based on the maximum attenuation wavelength shift with a comparable sensitivity (slope: 2000 nm/ $varepsilon, R^{2} =0.996$) with long-period-grating-type sensor and promises low fabrication cost.