Bright Red Upconversion Luminescence of Thulium Ion-Doped GeS2−In2S3−CsI Glasses

In this paper, we report a novel phenomenon in GeS2−In2S3−CsI chalcohalide glasses doped with Tm3+ ions. Under irradiation with an 808 nm laser diode, a bright red emission centered at 700 nm is observed for the first time. By codoping with different concentration of Er3+ ions, emission can be tuned from monochromatic red to green. The Er3+ ions codopant and higher concentration of Tm3+ ions are favoring the 700 nm red emission. Meanwhile, the indium (In) contents plays a significant role on the enhanced upconversion and near-IR emissions. These observations are interesting and may enable the device based on the chalcohalide glass to meet the specific color demands, which have potential applications in the fields of optical and solid state lasers.