Magneto-Optical Properties of (RBi)₃Fe₅O₁₂ at 0.8μm Wavelength Band

Abstract

Optical absorption and Faraday rotation of bulk single crystals of R_3-xBi_xFe₅O₁₂ (R=Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu) were measured in the wavelength range of 0.7 to 1.1μm. The peak position of the broad absorption band located at ∼0.9μm shifts to the higher energy side with the increasing size of R ion, at the rate of -0.27μm/Å. Therefore, the absorption at a given wavelength near 0.8μm, the valley between two broad absorption bands located at ∼0.7μm and ∼0.9μm, can be minimized by the choice of R of a proper size. The magneto-optical figure of merit of Lu_2.2Bi_0.8Fe₅O₁₂ is 13 deg/dB at 0.83μm, and that of Gd_2.2Bi_0.8Fe₅O₁₂ is 24 deg/dB at 0.78μm.