The spatial sensitivity of an erbium doped optical fibre distributed feedback (DFB) laser to an external magnetic field is
reported. Intrinsic birefringence of the laser cavity allows lasing in two orthogonal modes. The polarisation beat frequency
between these modes is sensitive to magnetic fields aligned along the axis of the optical fibre due to the Faraday effect. The
interaction of magnetic field, generated by a permanent magnet, with the spatial mode profile of the laser is investigated.
Experimental measurements show a 3.82 MHz change in the beat frequency when a permanent magnet is scanned along
the fibre laser.
In this paper, a novel Fiber Bragg gratings (FBGs) high alternating current sensor is proposed to measure alternating
current. The principle and sensing structure are introduced. The sensitivity of the high alternating current sensor is
13.8pm/A when the current is 1000A. The trend shows a good linearity between the wavelength shift and the square of
the current value which is consistent well with the principle and indicates that the proposed sensor is capable of
measuring high alternating current.
Current sensor is the core device for the electric energy measurement. Fiber Bragg grating (FBG) sensing technology has
many applications with anti-electromagnetic interference, good insulation, high reliability, small size, distributed
measurement. Fiber brag grating based current sensing becomes an important direction of research and exploration. The
principle of fiber Bragg grating current sensor based on electromagnetic force has analyzed. The structure of fiber Bragg
grating current sensor has designed. Huge current measurement has achieved with high-speed demodulation equipment.
The demodulation range of fiber Bragg grating center wavelength is 2.7nm when DC (0-700A, step 100A, 50Hz) current
Current sensors always play a very important role in the power industry. For example, current sensors can provide the
key information for measurement, control and relay protection. However, when the economic further develops and the
level of current increases year by year, it is very difficult to meet the demand for current sensors based on conventional
technology which is still the main stream. Novel current sensors always are pursued. A research focusing on the current
sensor is the technology of fiber optic current sensor, because there is high resistance to electromagnetic interference in
fiber optic sensors. Fiber Bragg grating (FBG) sensors have been applied in many fields and have gained great
achievements. It is of great help to the current measurement if FBG current sensors are realized. In this paper, a novel
FBG high-current sensor is developed based on magnetic coupling. The principle is described, such as the magnetic
coupling, the structure of the sensor and the sensing data processing. Experiments are carried out, and the results show at
least 60 pm wavelength shift with the change of 100A and 2563 pm wavelength shift when the current is 750A and a
good repeatability. The results are in agreement with the principle and indicate that the proposed sensor is capable of
measuring both dc and ac current.
The measurement of alternating current (AC) is realized by using fiber Bragg grating (FBG), giant magnetostriction
material (GMM), and the technology of fiber coupler demodulation (fiber wavelength division multiplexing filter,
FWDMF). The magnetostrictive effect of GMM, the theoretical analysis of the FBG current measurement and the
interrogation technology of FWDMF are introduced as well. The sensing unit of AC current measurement is constructed
with magnetostrictive material and FBG. The feasibility of AC current measurement by using this method is proved, when
the AC exciting current is in the scope of 0~2A.