Looking at the literature of the last years is evident that glass-based rare-earth-activated optical structures represent the technological pillar of a huge of photonic applications covering Health and Biology, Structural Engineering, Environment Monitoring Systems and Quantum Technologies. Among different glass-based systems, a strategic place is assigned to transparent glass-ceramics, nanocomposite materials, which offer specific characteristics of capital importance in photonics. These two-phase materials are constituted by nanocrystals or nanoparticles dispersed in a glassy matrix. The respective composition and volume fractions of crystalline and amorphous phase determine the properties of the glass-ceramics. The key to make the spectroscopic properties of the glass-ceramics very attractive for photonic applications is to activate the nanocrystals by luminescent species as rare earth ions. From a spectroscopic point of view the more appealing feature of glass-ceramic systems is that the presence of the crystalline environment for the rare earth ions allows high absorption and emission cross sections, reduction of the non-radiative relaxation thanks to the lower phonon cut-off energy and tailoring of the ion-ion interaction by the control of the rare earth ion partition. Although the systems have been investigated since several years, chemical and physical effects, mainly related to the synthesis and to the ions interactions, which are detrimental for the efficiency of active devices, are subject of several scientific and technological investigations. Here we focus on fabrication and assessment of glass-ceramic photonic systems based on rare earth activated SiO2-SnO2 glasses produced by sol-gel route.