ABSTRACT
The concept of a magneto-optic current sensor that employs a fiber-optic Fabry-Perot resonator shaped into a single-turn helix is presented. The helical shape permits construction of a compact device that has the required polarization properties. Compared with a single-pass sensor, a large increase in sensitivity is obtained as a result of the finesse of the resonator. Experimental results confirm the theory and show that for a finesse of F = 6 the sensitivity is four times larger than for a single-pass sensor.
ABSTRACT
A novel polarimetric Fabry-Perot sensor concept, based on the phase detection of the transmitted light, is presented in detail. This concept has been successfully applied to measure static force by stress induced birefringence in an optical fiber with high sensitivity. The detection scheme consists of locking the optical frequency of a laser diode to a resonance peak, where the sensitivity is highest, and using heterodyne detection to measure the phase difference between the eigenpolarizations.
ABSTRACT
The effect of birefringence induced in a single-mode fiber pressed into a V groove is investigated theoretically and experimentally. To determine the groove angle for which no birefringence is induced in the fiber core, the important parameters are the groove angle and the coefficient of static friction between the fiber and the groove wall. Experimental data show that for hard steel grooves the optimal angle is approximately 55 degrees .