Thermal and optical properties of TeO2–BaO–SrO–Nb2O5 based glasses: New broadband Raman gain media

We systematically added WO3 (up to 10 mol%) and P2O5 (up to 16 mol%) in TeO2–BaO–SrO–Nb2O5 (TBSN) glass system and studied thermal and optical properties of the resultant glasses. The dependences of the additive concentration on glass transition (Tg) and crystallization (Tx) temperatures are presented. The TBSN glass added with ⩾4 mol% WO3 and P2O5 showed high stability against crystallization. The changes in optical band gap energy due to WO3 and P2O5 addition was studied using UV–VIS–NIR absorption spectrometry. The WO3 addition shifted the optical band gap to longer wavelengths, whereas P2O5 addition shifted that to shorter wavelengths. Effects of the WO3 and P2O5 addition on the Raman spectra of TBSN glass are clarified. New Raman bands due to WO4 and PO4 tetrahedra formed in the resultant glasses broadened their Raman spectra. Present glasses are characterized by higher thermal stability and wider Raman spectra, therefore, they are promising candidates for fiber Raman amplifiers in photonics systems.