Magneto-optical properties of bi-substituted rare-earth iron garnets in 1.55-μn-wavelength band

Abstract

Bi-substituted rare-earth iron garnets, (REBi)3Fe 5O12 (REBiIG), are used in wide-band optical communication as Faraday rotators in an optical isolator. However, the influence of rare-earth ions on the magneto optical (MO) properties of REBiIG crystals, such as specific Faraday rotation (FR) and coercive force, is not clear. The aim of the present work is to compare the MO properties of garnets doped with different rare-earth ions. REBiIG (RE = Ho, Yb, or/and Tb) crystals were grown from Bi2O3 self-fluxed melts by the top-seeded solution growth method under the same conditions. It was found that both specific FR and coercive force decrease with an increase in rare-earth ion radius. The FR wavelength stability of HoYbBiIG is better than that of YbBiIG but worse than that of HoBiIG. However, the FR temperature stability of HoYbBiIG is worse than that of YbBiIG but better than that of HoBiIG. It is noted that HoYbBiIG crystal is a trade-off between HoBiIG and YbBiIG crystals in terms of MO properties.