Tunable Raman Gain in Transparent Nanostructured Glass-Ceramic Based on Ba₂NaNb₅O₁₅ †

Stimulated Raman scattering in transparent glass-ceramics (TGCs) based on bulk nucleating phase Ba₂NaNb₅O₁₅ were investigated with the aim to explore the influence of micro- and nanoscale structural transformations on Raman gain. Nanostructured TGCs were synthesized, starting with 8BaO·15Na₂O·27Nb₂O₅·50SiO₂ (BaNaNS) glass, by proper nucleation and crystallization heat treatments. TGCs are composed of nanocrystals that are 10-15 nm in size, uniformly distributed in the residual glass matrix, with a crystallinity degree ranging from 30 up to 50% for samples subjected to different heat treatments. A significant Raman gain improvement for both BaNaNS glass and TGCs with respect to SiO₂ glass is demonstrated, which can be clearly related to the nanostructuring process. These findings show that the nonlinear optical functionalities of TGC materials can be modulated by controlling the structural transformations at the nanoscale rather than microscale.