Miniature Fiber-Optic Magnetic Field Sensor Based on Ampere Force and Fiber Laser

A compact fiber-optic magnetic field sensor is proposed by packaging an orthogonal dual-frequency fiber grating laser and a copper wire with alternating electrical current together inside epoxy resin. The alternating current generates Ampere force in a magnetic field, which changes the birefringence of the fiber laser and hence tunes the frequency of the beat signal after photodetection. The magnetic field magnitude can then be detected by measuring the frequency change of the beat signal. The sensitivity of the sensor can be tuned with a maximum response of 35.21 kHz/kGs demonstrated. Moreover, the sensor shows good immunity to environment interference.

Designing and analyzing two non-invasive current sensors using Ampere Force Law (AFL)

Here two different non-invasive current sensors are proposed, modeled and analyzed. The current sensors are based on the Ampere Force Law (AFL), defining the magnetic force between two parallel wire carrying currents. These current sensors can be used for detecting/sensing DC and AC currents as well as their combination in a single wire or multiple wires, and they do not rely on any permanent magnets for operation. In the first configuration, there are two microbeams, in which one of them is at the vicinity of the wire and undergoes the mechanical vibrations due to the magnetic force between the wire and the microbeam. The movement of the microbeam while it is generating a magnetic field induces a current inside another microbeam, which is stationary, as the output signal of the current sensor. In the second configuration, a single composite piezoelectric microbeam is used. The magnetic force between the wire and the piezoelectric microbeam leads the piezoelectric microbeam to move, thus it produces a voltage. Both configurations present extremely low power consumption, which is not dependent on the sensitivity of the current sensors. The dynamic response, sensitivity and power consumption of the current sensors are investigated, compared and discussed.