Raman scattering characteristics of WO 3 and P 2 O 5 doped TBSN glasses: a new gain medium for broadband fiber Raman amplifiers

Abstract

We systematically doped WO 3 (up to 10 mol%) and P 2 O 5 (up to 16 mol%) in TeO 2 -BaO-SrO-Nb 2 O 5 (TBSN) glass system and studied thermal and optical properties of the doped glasses. The dependence of the dopant concentration on glass transition (T g ) and crystallization (T x ) temperatures are presented. The TBSN glass doped with ≥4 mol% WO 3 and P 2 O 5 showed high stability against crystallization. The dependence of optical band gap energy due to WO 3 and P 2 O 5 doping, studied using UV-Vis-NIR absorption spectrometry, is presented. The WO 3 doping shifted the optical band gap to longer wavelength side, whereas P 2 O 5 doping shifted that to shorter wavelength side. Structural details of the doped glasses are studied using Raman spectrometry. New Raman bands due to WO 4 and PO 4 tetrahedra are observed in the Raman spectrum of the doped glasses that broadened the Raman spectrum. The Raman gain coefficient and bandwidth of tellurite glasses has been tailored by systematically adding WO 3 and P 2 O 5 in a TeO 2 -BaO-SrO-Nb 2 O 5 glass system. The Raman gain coefficients of the resultant glasses were obtained from spontaneous Raman scattering experiments using a 633 nm laser. The glasses here developed showed the widest gain bandwidth so far achieved in tellurite glasses while maintaining higher gain coefficients. The gain bandwidths of these glasses are more than twice that of a conventional tellurite-based glass and 70% larger than that of the silica glass. Present glasses developed are promising candidates for fiber amplifiers in photonic systems.