A bent in-line Mach-Zehnder interferometer sensor to increase refractive index sensitivity

A refractive index sensor based on a bent in-line Mach-Zehnder interferometer is investigated via numerical analysis through the beam propagation method. Comparative results are presented for the conventional not bent sensor and for the cases in which this sensor is bent at certain radii of curvature. The results showed poor sensitivity for the not bent sensor presenting a wavelength shift ~75 nm/RIU within the refractive index range of 1.33 to 1.41 and 55 nm/RIU near the refractive index value of 1.41. In contrast, when the sensor was bent its sensitivity was greatly increased presenting the best response at a radius of curvature of 12 mm achieving ~1025 nm/RIU for values of refractive index from 1.33 to 1.41 and ~2000 nm/RIU near the refractive index value of 1.41.