A new Bi-substituted compounded rare-earth–iron garnet of (TbYbBi)3Fe5O12 with wideband and temperature-stabilized properties

A new Bi-substituted compounded rare-earth–iron garnet bulk single crystal of (TbYbBi)3Fe5O12 has been obtained by using Bi2O3–B2O3 as main flux and the accelerated crucible rotation technique for single-crystal growth, giving the formula of Tb2.06Yb0.46Bi0.48Fe5O12 and a single-crystal dimension large enough for device application. According to series of magneto-optical (MO) measurements in the near-infrared region, the (TbYbBi)3Fe5O12 single crystal exhibits a small magnetic field for saturation (1.2×106 A m−1), a low optical absorption loss (6.58 cm−1), a large Faraday magneto-optical figure of merit (18° dB−1), a very small Faraday rotation temperature coefficient (FTC; 2.1%) and a very small Faraday rotation wavelength coefficient (FWC; 0.021%) at wavelength λ=1.55 μm. The integrated Faraday magneto-optical properties of (TbYbBi)3Fe5O12 are much superior to those of the conventional Y3Fe5O12 material. Through compounding two kinds of rare-earth–iron garnets with opposite wavelength and temperature coefficients signs, wideband and temperature-stabilized Faraday rotation properties are achieved, indicating a theoretical and technical improvement for preparing of advanced Faraday rotator materials. A new optical isolator using (TbYbBi)3Fe5O12 as Faraday rotator material is therefore proposed, which features high-performance for wavelength division multiplexing fiber optics communication.