磁気光学ガーネット : 酸化物(<特集>21世紀を担うバルク単結晶)

抄録

The liquid-phase epitaxial (LPE) growth of magneto-optic garnets for optical communication devices is reviewed.The main compositions of these garnets are oxides of rare earth, Bi, and Fe. Production of optical isolators using these garnets is now expanding Such isolators are used laser diode modules and optical fiber amplifiers m optical communication networks The magneto-optic properties of the garnets depend on the rare earth element used. For example, the temperature dependency of the Faraday rota tion is minimized when Tb is used. Partial substitution of Ga and/or Al for the Fe reduces the saturation magnetization field and induces magnetic hysteresis. LPE (liquid phase epitaxial) crystal growth of garnets with large diameters requires precise control of the crystal-lattice parameters of the LPE film because of the difference in thermal expansion coefficients between the substrate and film . Harmful optical absorption in the garnets overlapping the wavelength of the optical signals occurs if Pb or Pt is incorporated into the crystal. This absorption can be suppressed by growing the crystals at high temperature and/or by doping with an element such as Ti.