Multimode fiber Mach-Zehnder interferometer for measurement of refractive index

A novel class of multimode optical fiber Mach-Zehnder interferometer suited for refractive index measurement is presented. The Mach-Zehnder interferometer was constructed by making two coupling points in a multimode optical fiber at localized regions with an electric arc system. The Mach-Zehnder interferometer as a high sensitive refractive-index sensor to detect changes in the surrounding refractive index was studied. The results for different concentrations of sucrose solution show that a resolution of 3.07×10^-5 - 7.47×10^-5 RIU is achieved for refractive indices in the range of 1.333 to 1.370, suggesting that the Mach-Zehnder interferometer are attractive for chemical, biological, and biochemical sensing with aqueous solutions.