Fabrication and testing of a nickel-coated single-mode fibre magnetometer

A single-mode optical fibre was coated with nickel over its cladding using CVD. The thickness of nickel was greater than 90 ¿m along a 15 cm span. The phase sensitivity of light in the fibre was measured interferometrically and found to be 1.5 × 10¿7 radian Oe¿1 after a thermal anneal. The measured sensitivity is within an order of magnitude of values obtained using bulk nickel mandrels. A frequency roll-off of sensitivity was in evidence beyond several hundred hertz.