Fabrication and characterization of cascaded tapered Mach-Zehnder interferometer for refractive index sensing

A highly sensitive glucose detection refractometer based on Mach- Zehnder Interferometer (MZI) formed by two cascaded tapered joints by using a fusion splicer was proposed and experimentally demonstrated. A section of 40 mm single mode fiber is spliced by arcing function with cascaded tapered joint between two single mode fibers to construct MZI. Experimental results show that the transmission spectrum of the proposed cascaded device has a blue shift with the decreasing concentration of glucose. The sensitivity coefficient of 380 nm/RIU was acquired within the refractive index range from 1.333 RIU to 1.349 RIU. This result shows that the proposed structure can be used as a sensor to detect glucose concentration, which enables its importance in physiological and biomedical applications. Its ease of fabrication makes this device itself a low-cost alternative to existing sensing applications.