Fabrication and characterization of transparent nanocomposite ceramics for infrared eye-safe laser oscillation

Abstract

Transparent polycrystalline ceramics have been developed over several decades for use in many functional optical materials. For the past decade, researches have been actively conducted on the use of nanocomposites in transparent ceramics, and a representative material is the $Y_2O_3$-MgO nanocomposite ceramics. Mid-infrared transmittance is also superior that it is considered to be the advanced infrared transparent ceramics. Regardless of outstanding characteristics of this material, it has severe light scattering at the grain boundaries resulted from large difference in refractive index between two different phases. Therefore, there is a need to study improved and ameliorated sintering strategies that exceed existing limitations. As a robust approach, pressure-assisted two-step consolidation of $Y_2O_3$-MgO nanocomposite ceramics is in-vestigated to achieve full density while retaining domain size. By effectively suppressing grain growth and eliminating residual pores via two-step hot-pressing, outstanding mid- and near-infrared transmittance are achieved. An Er:$Y_2O_3$-MgO nanocomposite as a new host material candidate is prepared that excellent optical, mechanical and thermal properties are demonstrated. The fluorescence spectrum and cross-section values are also investigated to evaluate the possibility of using the $Y_2O_3$-MgO nanocomposite as a laser gain medium. Finally, based on the spectroscopic analysis of the nanocomposite for oscillation of infrared laser in chapter II, laser oscillation test is carried out. Also, to improve the absorption properies of the nanocomposite ceramics, target wavelength is changed with different activator ion ($Ho^{3+}$). Furthermore, random lasing effect of the nanocomposite ceramics is firstly reported using a severe scattering at the interfere of two phases in nanocomposite.