A new Ni/Bi Co-doping rare earth iron garnet crystal with high transmittance, low temperature and wavelength coefficients

Bi-doped rare earth iron garnet (Bi:RIG) crystal is an ideal magneto-optical material for optical isolators in the near-infrared band, which has been widely used in optical communication applications. In this paper, centimeter-sized and good-quality Ni2+-doped Bi:RIG crystals were successfully grown by top-seeded solution growth (TSSG). The transmittance reaches 72.6% at 1550 nm, which is higher than commercial Bi:TbIG crystal and close to the theoretical values of RIG crystals. Doping Ni can not only greatly improve the transmittance, magnetic, and magneto-optical properties, but also decrease the Faraday rotation temperature (FTC) and wavelength coefficients (FWC) of the Bi:RIG crystal. The FTC and FWC of (Bi0.37Ho1.18Eu0.83Gd0.62)(Fe4.20Ni0.25Ga0.55)O12 crystal reduced to − 6.3 × 10−4 K−1 and 8.0 × 10−4 nm−1, which are about 30% and 80% of commercial Bi:TbIG crystal, respectively. (Bi0.37Ho1.18Eu0.83Gd0.62)(Fe4.20Ni0.25Ga0.55)O12 exhibits potential for utilization in new high-performance, wideband magneto-optical isolators, and is expected to find application in the field of wavelength division multiplexing fiber communication.