Preparation of GdIG:Bi Single Crystals by Crucible Rotation Flux Method

GdIG single crystals with Bi substituted were grown by the crucible rotation flux method to reduce the optical absorption loss in the near infrared range. This loss is a serious problem with rare earth iron garnets used for optical isolators. The grown crystals have extremely few carriers, and the resistances are in the range 10⁹ to 10¹² ¿-cm as compared with 10⁶ ¿-cm for crystals prepared by the conventional technique. It is thought that the oxygen defects, ie, amount of resultant Fe²⁺, in the GdIG:Bi single crystals grown by this method will be significantly lower than that in similar crystals prepared by the conventional method. The optical absorption loss was one third that of the optical loss in crystals grown by the conventional flux method.