Broadband near-infrared emission from Cr4+-doped transparent glass–ceramics based on lithium silicate

Cr4+-doped transparent glass–ceramics containing Li4SiO4 nanocrystals were prepared by heat-treatment on as-made glasses. It was confirmed from absorption spectra that the energy levels of Cr4+-doped the glass–ceramics is close to the cross point 1E and 3T states. The broadband infrared emission centered at 1230 nm with the full width at half maximum (FWHM) of more than 240 nm was observed by exciting the glass–ceramics with excitation of an 808 nm laser diode. The lifetime was about 230 μs at room temperature. The observed infrared emission could be attributed to Cr4+ ions at low-field sites in Li4SiO4 glass–ceramics.