1988 年 12 巻 2 号 p. 179-182
Optical absorption and Faraday rotation of bulk single crystals of R3-xBixFe5O12 (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 Lu2.2Bi0.8Fe5O12 is 13 deg/dB at 0.83μm, and that of Gd2.2Bi0.8Fe5O12 is 24 deg/dB at 0.78μm.