Bent Inline Fiber Mach-Zehnder Interferometer Used for Refractive Index Sensing

An inline fiber Mach-Zehnder interferometer used for refractive index sensing was investigated in this paper. The sensing probe was fabricated by splicing two single mode core- offset fiber attenuators sandwiched a tapered single mode fiber. It is found that the straight probe was not sensitive enough for RI measurement. After bending it, the sensitivity was improved markedly, and the maximum RI sensitivity of 196.99 nm/RIU was achieved. The result showed that bending the inline Mach-Zehnder interferometer could enhance its RI sensing performance, and as the curvature radius deceased, the RI sensitivity increased.