Large size rare earth iron garnet single crystals grown by the flux-Bridgman method

Rare earth garnet (R3Fe5O12, RIG) single crystals are the most ideal magneto-optical medium for optical isolators for wavelength longer than 1.1 mu m, which has been commercially used in optical fiber communications. However, it is still a great challenge to grow large size RIG single crystals. In this work, high-quality Y3Fe5O12 (YIG) and Bi0.9Tb2.1Fe5O12 (Bi:TIG) single crystals were successfully grown by the flux-Bridgman method for the first time. The as-grown crystals up to 20 mm in diameter was obtained using the PbO-B2O3 flux. The transmittance of YIG crystals is over 75% in the region of 1100-2500 nm. TIG crystals also have good transmittance in the range of 1100-1700 nm, and show typical Tb absorption from 1700 to 2500 nm. The specific Faraday rotations of YIG and Bi0.9Tb2.1Fe5O12 crystals are 185 (degrees)/cm and -1250 (degrees)/cm at 1550 nm, which are comparable to the commercial RIG crystals grown by LPE method. The present results indicate that flux-Bridgman method shows great potential to grow large size and high-quality RIG magneto-optical crystals. (C) 2021 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.

Automated summary

This study successfully grew high-quality YIG and Bi:TIG single crystals for the first time using the flux-Bridgman method, showing potential for solving the challenge of growing large size RIG crystals. YIG and TIG crystals demonstrated good transmittance and specific Faraday rotations in certain wavelength ranges.