FZ Growth of Iron Garnet Crystals

The floating zone (FZ) growth technique and characterization of yttrium-iron garnet single crystals (FZ YIG) for magneto-optical devices in fiber optical communication systems are described. FZ YIG crystals of high quality and sizes suitable for practical application were grown using an apparatus of the infrared radiation convergence type. The measured transmittance at a wavelength of 1.3 ¿m was 71-73 percent, compared with the theoretical value of 75 percent, throughout most of the YIG ingots, which were 100 mm in length and 8 mm in diameter. The near-infrared Faraday rotation angles in FZ YIG were larger than in YIG grown by the flux method. Finally, the fundamental properties of an isolator designed and fabricated by the authors, and utilizing the FZ YIG, are presented.