Magneto-optic current sensor using a helical-fiber Fabry–Perot resonator

Abstract

The concept of a magneto-optic current sensor that employs a fiber-optic Fabry-Perot resonator shaped into a single-turn helix is presented. The helical shape permits construction of a compact device that has the required polarization properties. Compared with a single-pass sensor, a large increase in sensitivity is obtained as a result of the finesse of the resonator. Experimental results confirm the theory and show that for a finesse of F = 6 the sensitivity is four times larger than for a single-pass sensor.

Novel electro-optic and magneto-optic properties of monomode optical fibres

“…(7)), these authors show (using results from Tang [13]) that the bend-induced birefringence is which satisfies the inequality required for equation (3). A measurement was made by the authors [12] of the phase difference between the circular eigenmodes as a function of current through the conductor, by measuring the shift in the Fabry-Perot rsonance peak. The measured finesse of the resonator was 6 and the current sensitivity was 1 .4.…”

“…This method for measuring PH and thus also the electric current which produces it, has been used recently in a Fabry-Perot arrangement [12]. Using a single-turn spiral with an end reflection, ( fig.…”

Design principle for sensing coil of fiber-optic current sensor based on geometric rotation effect

“…When the light propagates along the forward direction of the sensing coil, the Jones matrix of the element is given by the following [20]:…”

“…Therefore, how to suppress the scale factor error caused by the LB is a key issue to the design of the sensing coil of the FOCS. The current solutions to overcome the LB problem include the following: reducing the LB in the sensing coil by using the thermal annealing fiber coil [14,15] or flint glass fiber having low elastic-optic constant fiber [16]; adding the reciprocal circular birefringence (CB) to the sensing coil to suppress the effects of the LB, e.g., spun elliptically birefringent fiber [17,18], twisted fiber [19], or fiber alignment along a helical path [20,21]. In fact, winding the optical fiber in a helix path is a method producing the reciprocal CB by the geometric rotation effect.…”

Alternating current sensor with second-harmonic detection

“…[1][2][3][4][5][6][7][8][9][10][11] Current sensors based on the Faraday effect have been successfully demonstrated with both interferometric [5][6][7][8][9] and polarimetric configurations 1,2,10,11 ͑for a review see, e.g., Ref. 4͒.…”