Abstract

Magnetic field sensors have been constructed from two pieces of polarizing optical fiber fusion spliced to a single piece of low birefringence optical fiber [Fig, 1(a)]. This configuration was mounted on a quartz bar for good geometric stability. A 780-ntn laser diode pigtailed with polarizing fiber is used as the optical source for the sensor and light at the output is detected with a standard silicon detector. This device has been tested as a magnetic field sensor by placing it within a solenoid. The solenoid was excited with an ac current and a proportional ac optical signal was observed using a lock-in amplifier. The sensor was cycled in temperature from −40 to +80°C with a change in the measured field of less than + /−0.5% of the applied field. The change in measured field can be entirely attributed to the change in the Verdet constant of fused silica with temperature.¹

© 1996 Optical Society of America