Optical fiber magnetic field sensors with TbDyFe magnetostrictive thin films as sensing materials

Abstract

Different from usually-used bulk magnetostrictive materials, magnetostrictive TbDyFe thin films were firstly proposed as sensing materials for fiber-optic magnetic field sensing characterization. By magnetron sputtering process, TbDyFe thin films were deposited on etched side circle of a fiber Bragg Grating (FBG) as sensing element. There exists more than 45pm change of FBG wavelength when magnet field increase up to 50 mT. The response to magnetic field is reversible, and could be applicable for magnetic and current sensing.

Characterisation and performance of a Terfenol-D coated femtosecond laser inscribed optical fibre Bragg sensor with a laser ablated microslot for the detection of static magnetic fields

“…Whilst this is not as sensitive as some reported results elsewhere, where minimum detectable magnetic fields of 0.10nTHz -1/2 and sensitivities of up to 1.08pmmT −1 [10,13] were presented, however, the asymmetry of the device enables it to be sensitive to the direction of the magnetic field which is highly novel in the case of fibre sensors. The device also does not rely on high frequency AC magnetic fields, multilayer coatings, mumetals or expensive Fabry-Perot filters to work.…”

“…It has been shown that the sensitivity of magnetostrictive fibre sensors is increased by removing the cladding through chemical etching thus reducing the ratio between the fibre and Terfenol-D coating [13]. However, the use of chemical processing using HF is slow and has numerous related health and safety issues.…”

Optical Current Sensors for High Power Systems: A Review

“…In 2009 and for the first time, a fiber optic magnetic field sensor with a thin film of Terfenol-D instead of the bulk magnetostrictive materials was reported by Yang et al [71] as shown in Figure 15.…”

Femtosecond laser inscribed Bragg sensor in Terfenol-D coated optical fibre with ablated microslot for the detection of static magnetic fields

“…Here we develop a static magnetic field sensor, exploiting the properties of Terfenol-D, which in the presence of magnetic fields changes dimensions through magnetostriction. [6] Below the Curie temperature, as in this work, the dimensional change is linearly proportional to the magnetic field strength. We utilise the alloying of Dy and Tb, specifically DyFe 2 and TbFe 2 having the form Tb x Dy 1-x Fe 2 , as this gives the highest known magnetostrictive compound, exhibiting a strain of 2,000με in a field of 2 kOe (160 kA/m) at room temperature.…”