Broadband mid-infrared emission from Cr2+ in crystal-in-glass composite glasses by Hot Uniaxial Pressing

Cr2+-doped II-VI crystals have witnessed an excellent gain media for continuously tunable and femtosecond-pulsed lasers. Despite this, major challenges persist toward realizing ultrabroad emission bandwidth and efficient Cr2+-doped fiber due to the valence diversity of Cr, especially in chalcogenide glasses. Here, we propose to prepare Cr2+:ZnSe/As2S3-xSex composite glasses by Hot Uniaxial Pressing (HUP), a method that sinters uniformly mixed crystal and glass powders into geometrically designed composite chalcogenide glasses. The densification of the composite glasses reached 99.88%, indicating that a few or none pores remain. Our research shows that Cr2+:ZnSe crystals have good performance in chalcogenide glasses, and the composite glasses have the potential to be made into mid-infrared-doped fibers. It was demonstrated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) that the composite glasses have a uniform Cr2+:ZnSe distribution and no crystal disintegration. The transmittance of the composite glasses was significantly improved by tailoring the refraction index. The mid-infrared (MIR) fluorescence and decay of the glasses were measured. The lattice constant was measured, calculated, and discussed to reveal the influence of sintering process on lifetime.