This seminar will explore the development of advanced photonic materials based on glasses, glass-ceramics and carbon nanostructures, emphasizing their role as model platforms for complex-system behavior in light–matter interactions. The first part will focus on rare-earth-doped tellurite and germanate glasses engineered for random laser emission, discussing how disorder, scattering mechanisms and energy-transfer processes give rise to replica symmetry breaking, ultrametricity and other signatures of complex photonic phases. The second part will address luminescent materials for sensing and photonics, including thermometric systems based on Er³?/Nd³? emission, sol-gel-derived resonators for whispering-gallery-mode applications, and carbon dots tailored for optical microcavities. Together, these results illustrate how structural disorder, nonlinear optical responses and nanoscale design can be harnessed to build multifunctional light sources and probes for next-generation photonic devices.