OPTIC FIBER CURRENT SENSOR, COMPRISING SEVERAL SENSING HEADS

The invention concerns an optic fiber current and magnetic field sensor, comprising several sensing heads (H), and a corresponding measurement method. Said sensor includes: a light source (1); N 2 sensing heads (H); at least a phase modulation unit (PME) including at least a phase modulator (PM); a detector (2) a control and evaluation unit (5). The phase modulation unit (PME) is optically connected to at least one of the sensing heads (H) and enables differential and non-reciprocal phase modulation of linearly polarized light waves. N modulation amplitudes¿0,n and N modulation frequencies ¿n are provided for the differential and non-reciprocal phase modulations. The modulation frequencies ¿n and two positive integers p, q with p q, capable of being pre-allocated, are selected such that, for all the positive integers n, m with n m and 1 ¿ n, m ¿ N: p. ¿n z. ¿m and q. ¿n ¿m.The modulation amplitudes ¿0,n and the modulation frequencies ¿n are selected on the basis of the modulation-relevant optical path lengths ln. The invention enables to obtain a better signal-to-noise ratio.