Growth and characterization of holmium-doped yttrium iron garnet single crystal

Yttrium iron garnet (YIG) crystals are the primary candidate for non-reciprocal device. With the miniaturization and integration of optical communication devices, the modified YIG crystals with excellent comprehensive performances are highly desired. To explore the possible mechanism of rare earth ions doping on Faraday effect, holmium oxide-doped YIG (Ho0.6Y2.4Fe5O12, abbreviated as HYIG) crystal was grown by molten salt method. Its structure, optical transparency, magnetic, magneto-optical properties and oxygen atmosphere annealing processes were first investigated systematically. The HYIG crystal wafers annealed at 800 °C for 2 hours can achieve the large Faraday rotation angle (186 deg/cm at 1310 nm; 148 deg/cm at 1550 nm) and good optical transparency (73.64% at 1310 nm; 74.83% at 1550 nm), which is increased by approximately 10% compared to the unannealed sample. This result may provide a new insight into the investigation of rare earth doped YIG crystals and their atmosphere annealing processes.