Optical fiber magnetic field sensors with ceramic magnetostrictive jackets.
Optical fibers coated by magnetostrictive ceramic films were tested with a Mach-Zehnder interferometer in an open-loop mode. The sensors exhibited excellent linearity and good sensitivity. The response of ceramic-jacketed fibers was not affected by small dc fluctuations that are due to the linear behavior of tested ceramic coatings in low magnetic fields. Tested ceramic materials included magnetite, γ-Fe(2) O(3), nickel ferrite, and cobalt-doped nickel ferrite (NCF2) jackets. The latter showed the best performance. A minimum detectable field of 3.2 × 10(-3) A/m for optical fiber jacketed with 2-μm-thick and 1-m-long NCF2 material has been achieved. The capability of detecting magnetic fields as low as 2.6 × 10(-7) A/m with a 10-μm-thick cobalt-doped nickel ferrite jacket is proposed.
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Sedlar
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Paulicka
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Sayer