We describe a micromachined optical fiber current sensor. The sensing element consists of a squared silicon membrane (8 mm long and 20 μm thick) that has a cylindrical permanent magnet (NdFeB alloy, 3-mm diameter, 1.5 mm high) fixed on its central region. This structure allows the permanent magnet to vibrate in the presence of the magnetic field gradient generated by an ac. A linear relation between the electrical current and the magnet displacement was measured with white-light interferometry with an optical fiber low-finesse Fabry–Perot microcavity. A measurement range of 0–70 A and a minimum detectable intensity of 20 mA were obtained when distance <i>D</i> between the membrane and the electrical power line was 5 mm. The output signal directly shows a linear response with distance <i>D</i>.
© 1999 Optical Society of America
R. L. Heredero, Ramón Fernández de Caleya, Héctor Guerrero, Pere Los Santos, Mari Cruz Acero, and Jaume Esteve, "Micromachined Optical Fiber Current Sensor," Appl. Opt. 38, 5298-5305 (1999)