A Spectrally Interrogated Polarimetric Optical Fiber Sensor for Current Measurement with Temperature Correction

We report on a study of the temperature dependence of the response of a BSO crystal based polarimetric current sensor with spectral interrogation. Two possible interrogation schemes are discussed. The spectral dependence of the optical rotation along the crystal caused by temperature and current changes is investigated, and approximate dependences for the sensitivities to current and temperature are derived. A mixed term in the response with spectral interrogation is revealed, the elimination of which is achieved by tracking wavelength shifts Δλ and Δλ of two distinct extrema in the polarimetric response. A temperature independent second degree equation for the current changes Δ as a function of the measured spectral shifts is derived and tested.