NOVEL BULK IRON GARNETS FOR MAGNETOOPTIC MAGNETIC-FIELD SENSING

We report measurements of the magneto-optic response Function and frequency response for three bulk iron garnet crystals grown by a flux technique. The samples were the product of an intensive effort to develop iron garnet compositions with properties specifically optimized for magnetic field sensing. Sensitivity enhancement was achieved through both bismuth substitution (for increasing the saturation Faraday rotation) and gallium substitution (for reducing the saturation magnetization). One sample exhibited a value of magneto-optic sensitivity of 25 degrees/mT for 1.3 mu m light. Frequency response measurements indicate that bismuth substitution actually improves performance (compared to unsubstituted yttrium iron garnet) in contrast with gallium, which causes substantial degradation.