Luminescent Fe:ZnSe Doped As-S-Se Optical Composites for the Mid-infrared

Active transition metal ion (TM) doped infrared transparent chalcogenide glasses are a promising class of solid-state materials which can be drawn into a new generation of optical fibers for efficient sources of mid-infrared (MIR) lasers. This work evaluates a candidate glass matrix system of As-S-Se chalcogenide glass as a host for iron (Fe) doped ZnSe crystals. Despite good refractive index match between the chalcogenide glass and the Fe2+:ZnSe particles, the stability of the dopant is critically impacted by the melt temperature conditions. To address this issue, Fe2+:ZnSe particles were coated with a conformal shell of Al2O3, via Atomic Layer Deposition (ALD), to improve the stability of the dopant in the chalcogenide glass matrix melt environment. An ozone pretreatment of the ZnSe powders prior to ALD also improved particle stability, resulting in significant reduction in dissolution of coated powders. Moreover, an improvement in the drying protocol of the glass resulted in significantly lower impurity concentrations. The broadband optical emission of the composites in the 3520-5200 nm region was measured using Er (III):YAG pump laser. Improved ALD coating and drying protocol resulted in a bulk optical composite with higher emission signal compared to previous composite fabricated without these protocols, for the same loading levels.