A near-IR transmitting “black glass” synthesized from 70%TeO2-25%ZnO-5%ZnS

A new type of tellurite glass has been synthesized with composition 70%TeO
₂
-25%ZnO-5%ZnS. The glass is of black color, indicating a high absorption in the visible range. However, transmittance measurements show the same glass to be transmitting in the near-IR range, between 2 mum and 6 mum. XPS data reveal the existence of Zn-O-S and a reduction of tellurium oxide with formation of Te-Te bonds in the glass. Our preliminary experiments indicate an increased third-order susceptibility chi
⁽³⁾
at 1.5 mum.