Multiple connections of fiber-optic polarization sensors with localization possibilities

This paper focuses on multiple connections of fiber optic polarization sensors with the aim of localization. The low-weight non-electric fiber optic sensor is suitable for use in hazardous environments due to its properties and high sensitivity to the measured quantities. Precise localization of the point of change in the measured quantity during multiple connections is technically challenging. This causes inefficiency for the direct evaluation method using optical power. A suitable solution is to divide the optical power into multiple branches in different ratios before reaching the sensor itself. Based on the magnitude of the power response, the change in the measured quantity as temperature and strain can be localized. This is achieved by using a combination of a power splitter and polarization beam splitter. Different optical fiber lengths ensure different power responses at individual points, which can also be used for localization in serial connection. This paper also addresses long-distance power-supplying via a single-mode fiber and solves the problem of polarization by an auxiliary circuit of a power and polarization stabilization. The technical solution is suitable for a single-fiber arrangement. Experimental verification was performed for temperature and tension changes, which are the primary sensed quantities for this type of sensor, and the evaluation was carried out using optical power. Another potential use for this sensor can be in speed measurement, used in military technology and robotics.