Application of Photonic Crystal Fiber in Optical Fiber Current Sensors

Optical fibers may be applied in the technique of measuring electric current, particularly as so-called optical current transducers. They are small in size, cheap, light and safe. Their sensitivity, however, connected with the Faraday effect, is rather poor, and they are also susceptible to considerable disturbances (deformations of the fibers). Their sensitivity can be increased by lengthening the path of effect, but this involves also an increase of noise and greater fluctuations of the measured signal due to changes of internal stresses induced by external factors. These negative phenomena can be reduced by applying fibers less sensitive to deformations. The author supposes that photonic crystal fiber with a glass core may display such properties. Orifices in the cladding can to some extent prevent the propagation of deformations from outside the core, and thus decrease the birefringence of the fiber induced by elastooptic effects. The paper presents preliminary measurements of typical photonic crystal fiber exposed to mechanical vibrations.