Novel photonics materials for broadband lightwave processing

Abstract

Our status of glass-based photonics materials research for practical functional devices in future optical networks is presented in this paper. New candidates for metal-doped broadband gain media and fiber Raman gain media are presented. Bi-doped lithium alumino silicate glasses have been comprehensively investigated as a candidate of new broadband band gain medium. It was found that the peak wavelength and width of the emission from Bi-doped lithium alumino silicate glasses can be controlled by the excitation wavelength. The emission spectrum had the broadest full width of half maximum (FWHM) of more than 500 nm under the 900 nm excitation. The emission covered a spectral range from 920 to wavelengths over 2000 nm. The bandwidth exceeded 1000 nm. The lifetime was almost independent of temperature up to 350 K, indicating that the emission from the Bi-doped lithium alumino silicate glass has strong resistance to the thermal quenching. The quantum efficiency of the emission was obtained as 11 % when the glass was excited at 974 nm. As new fiber Raman gain media, TeO₂-BaO-SrO-Nb₂O₅ (TBSN) glass system containing WO₃ and P₂O₅ was systematically studied. The TBSN glass doped with WO₃ and P₂O₅ showed high stability against crystallization. New Raman bands due to WO₄ and PO₄ tetrahedra occurred and broadened the Raman spectrum of the glass system. The Raman gain coefficient and bandwidth of the TBSN tellurite glass have been tailored by systematically adding WO₃ and P₂O₅. The glass system showed the broadest gain bandwidth so far achieved in tellurite glasses while maintaining higher gain coefficients. The gain bandwidths of these glasses were more than twice that of a conventional tellurite-based glass and 70% larger than that of the silica glass. These glasses developed are promising candidates for photonics devices in future photonic systems.