Fiber-optic magnetic-field and electric-current sensors based on the Faraday effect in Bi12GeO20 and Bi12SiO20 crystals

Fiber-optic sensors (FOSs) of the magnetic field and electric current are developed and studied. The sensors are based on the Faraday effect in Bi12GeO20 and Bi12SiO20 crystals. The possibility of an increased sensitivity of such FOSs that is due to the application of multipass sensitive elements is considered. The limits for an increase in the optical-path length in a crystal with multiple passing of light are determined. Temperature drifts of the conversion coefficients are presented for various structures of sensitive elements.