The 3-5 μm mid-infrared laser can be used in infrared countermeasures, biomedicine, atmospheric remote sensing and environmental monitoring. All solid-state lasers using LD directly pumped laser materials become a main output method for mid infrared lasers due to their advantages like simple system, high conversion efficiency, and good beam quality. Polycrystalline transparent ceramics are commonly used as laser materials due to their preparation easiness, superior thermal and mechanical properties as well as the ability to achieve high doping concentrations. However, the development of high-power lasers requires overcoming the inevitable thermal effects during laser operation, i.e., thermal birefringence, thermal lensing, and depolarization, which arise from the temperature gradient inside the laser material. It is crucial to use laser materials with a high thermal conductivity to alleviate thermal effects and ensure the quality and stability of laser output. Moreover, laser host materials must also have a lower phonon energy to suppress non-radiative transition processes that compete with the luminescence processes. It is thus difficult for materials to simultaneously possess all of these properties.

In recent years, a large number of reports have claimed that Y₂O₃-MgO nanocomposite ceramics have ideal properties required for laser host materials, including high infrared transmittance, low phonon energy, high thermal conductivity, and good mechanical properties. The microstructure and properties of Y₂O₃-MgO nanocomposite ceramics doped with rare-earth activation ions are investigated, indicating that nanocomposite ceramics can be used as potential host materials for mid infrared lasers.

This review summarized the existing research results of Y₂O₃-MgO nanocomposite ceramics as a laser host material and also represented recent technologies and methods for preparing Y₂O₃-MgO nanocomposite ceramics.

The existing studies by theoretical models and experiments indicate that Y₂O₃-MgO nanocomposite ceramics have a high thermal conductivity, compared with Y₂O₃ ceramics, and a low maximum phonon energy (591cm^-1). This is due to a synergistic effect of composite properties, combined with a high thermal conductivity of the second phase MgO and a low phonon energy of Y₂O₃. However, the optical transmittance of Y₂O₃-MgO nanocomposite ceramics is mainly affected by grain size, porosity, and phase domain distribution, which makes it imperative to improve their microstructure. Therefore, some technologies and methods for preparing ceramics are emerged, i.e., colloidal forming, two-step sintering, high-pressure sintering, and reducing a difference in refractive index between the two phases. Moreover, the research results of rare-earth ion doped nanocomposite ceramics, such as Er: Y₂O₃-MgO and Ho:Y₂O₃-MgO, also confirm that the introduction of high thermal conductivity MgO can effectively improve the thermal conductivity of ceramics without affecting the photoluminescence properties of the luminescent components, indicating that Y₂O₃-MgO nanocomposite ceramics can be used as promising laser host materials.