Characteristics of Y3Fe5O12 ceramic at mid-infrared wavelengths and its Faraday isolator application

In this study, the Faraday effects of Y3Fe5O12 (YIG) magneto-optic (MO) ceramics synthesized by hot-press sintering were tested and compared with commercial YIG single crystals and Bi-doped iron garnet (BIG) films at mid-infrared wavelengths. Among them, YIG ceramics have shown Faraday rotation angles as large as 114 deg/cm and 60 deg/cm at 2.1 µm and 3.8 µm, respectively. The corresponding YIG ceramic-based Faraday isolators (FIs) exhibited an extinction ratio of 25.26 dB and an insertion loss of 1.01 dB at 2.1 µm, and an extinction ratio of 28.30 dB and an insertion loss of 1.17 dB at 3.8 µm. Under high repetition rate pulsed laser radiation, surface damage was observed for both YIG ceramic and YIG crystal at similar laser power density. Combining its advantage of size scalability, the further improvement of YIG ceramic optical quality is expected to provide a superior approach for realizing high power mid- infrared FIs.