The Effect of the exposed length of a distributed fiber-optic polarisation sensor on the temperature measurement

This article analyses the effect of the exposed length of the fiber-optic polarisation sensor on the temperature change measurements. This type of sensor plays an important role in securing objects in dangerous environments where it is necessary to have a lightweight, sensitive, and highly reliable sensing element. However, for utilisation in prostheses and robotics systems, it is important to focus on exposing smaller parts of the sensor itself. The stretched-out sensor, situated in a laboratory with an ambient temperature of 24 °C, was tested by applying a container of water at different temperatures (0 and 48 °C) at lengths of 10, 20, 30, and 40 cm and recording the differences between the places of application and polarisation response. The results were processed with a polarimeter and Stokes parameters. The results follow the trend of exponential decay and step response, with different end values with respect to the exposed lengths. The most significant differences are observable at the ends of the fibers. The graph of statistics in terms of differences of overall Stokes parameters is plotted and confirms the possibility of using this type of sensor for measuring on smaller scales.