Liquid core fiber interferometer for simultaneous measurement of refractive index and temperature

Abstract

A simple fiber sensor for simultaneous measurement of refractive index (RI) and temperature is proposed and experimentally demonstrated. The sensor head consists of a section of liquid-filled hollow core fiber spliced between single mode fibers. An interference fringe is observed from the transmission spectrum of the sensor, which is originated from the modal interference within the liquid core fiber. A temperature sensitivity of -42.7 pm/°C is experimentally obtained between room temperature and 80 °C. The sensor also exhibits a wavelength shift response to the ambient liquid RI with a sensitivity of 141 nm/RIU. Due to different sensitivities of the dips at separate wavelengths, it is possible to monitoring environment temperature and RI variation simultaneously by tracing two transmission dips. The sensor structure is simple, easy to fabricate, and cost-effective, which has potential applications in biological and chemical sensing.