Intensity-modulated fiber-optic refractive index and strain sensor based on miniaturized modal interferometer

摘要

A novel intensity-modulated fiber-optic refractive index (RI) and strain sensor based on modal interferometer (MMI) is proposed. The sensing mechanism is mainly based on the Mach-Zehnder interferometer (MZI) constructed by one down taper spliced between dual up tapers on the single mode fiber (SMF). High-order cladding modes are efficiently excited owing to the mismatch of the mode filed diameter (MFD). Experimental investigations achieve a RI sensitivity of −22.437dBm/RIU and a strain sensitivity of 0.0008dBm/µε with R2 of 0.9972 and 0.9962 respectively. It has to be noted that this MMI is only made of single SMF and is of low cost and easy fabrication.