DOPED SILLENITE CRYSTALS APPLICABLE FOR FIBEROPTIC MAGNETIC SENSORS

The spectral dependencies of the optical rotatory power (ORP-rho) and the Verdet coefficient (V) of undoped and Fe- and Cr-doped Bi12SiO20 ( BSO) crystals are studied in the spectral range of 440-800 nm. The res ults show that Cr decreases rho about 4-5% in the range 600-700 nm, bu t below 560 nm rho strongly increases up to 180-200% compared to the O RP of undoped BSO, which could be related to the earlier observed abso rption spectra. Like the ORP, the values of V are lower by about 1-3% at 700-600 nm, whereas below 590 nm V increases about 2%. The influenc e of Fe on rho and V strongly depends on the dopant concentration. For example, at larger concentrations (2.2 mol%) rho and V decrease up to 4% and 12%, respectively, whereas at 0.9 mol% Fe rho and V increase 3 % and 9%, respectively. The influence of the annealing and the illumin ation on the gyrotropy of undoped BSO are also studied. Some assumptio n about the nature of the sillenite optical and magneto-optical rotati on are made. The possibilities to use these materials for fiber optic magnetic field sensors or to improve their characteristics for photore fractive applications are discussed, too.