DyBi garnet films with improvement temperature dependence of Faraday rotation.

Abstract

To improve temperature dependence of the isolation value of magneto-optic Bi-substituted garnet films for use in an optical isolator, temperature dependence of Farady rotation coefficient was measured for (RBi)3Fe5O12(R=Dy, Gd, Yb) and (GdBi)3(FeAlGa)5O12 films in 1.3 and 1.5 μm wavelength bands. Among the Bi-substituted garnet films with various composition examined, Dy2.5Bi0.5Fe5O12 films showed a 2% shift in Faraday rotation from that measured at 25°C and assured isolation of 36 dB in the temperature range of 0-50°C. Isolation of 29 dB is assured, even if incident light wavelength fluctuates due to ambient temperature and manufacturing lot. These values correspond to those of Y3Fe5O12 bulk single crystal. From the viewpoint of material designing, temperature dependence of Faraday rotation for Bisubstituted garnets is improved by employing a solidsolution with the rare-earth garnet which has a positive Faraday rotation with negative temperature coefficient of Faraday rotation at room temperature.