High sensitivity temperature sensor based on polymer-liquid modified anti-resonant reflecting guidance in silica capillary

A high sensitivity temperature sensor based on polymer and liquid modified anti-resonant reflection principle is proposed. The sensor is made of a section of liquid-filled and UV-curable adhesive coated silica capillary, sandwiched between single mode fibers. The guiding mechanism of the waveguide is affected by both the liquid inside the hollow core, and the adhesive outside the silica cladding. The location of the resonant dips are influenced by the refractive index (RI) of the liquid, while the fringe visibility (resonant strength) is tuned by the both the liquid and the adhesive. By carefully selecting the refractive index value of the infiltrated liquid, and controlling the curing time of the adhesive, sharp resonant dips can be obtained. The sensor exhibits very high temperature sensitivity against temperature. A high sensitivity of 3.369 nm/°C is achieved with an infiltration index of 1.39, in the temperature range from 25 °C to 60 °C. The detection limit of the proposed sensors are 0.04 °C. Moreover, the temperature sensitivity of the sensor is found to be decreasing with the order of resonance. The sensor is easy to fabricate and cost effective, and is applicable in both dry and wet environments, which can find wide applications in biochemical and pharmaceutical industry.