The present invention discloses a transparent nanostructured glass-ceramic obtained from the thermal treatment of a bulk precursor glass based on SiO2 and LaF3 doped with three rare-earth ions (Yb3+, Er3+, and Tm3+) prepared by the sol-gel technique. The resulting nano-glass-ceramic contains nanometer-sized LaF3 crystals precipitated after the thermal treatment and dispersed in a SiO2 matrix, with the rare-earth ions incorporated within them. Using infrared excitation at 980 nm and a luminescent up-conversion process (conversion of infrared energy to visible light), white light is generated through the additive synthesis of red, green, and blue emissions. By controlling the incident excitation power, the emitted color can be tuned, with applications in three-dimensional photonic devices: image generators, solid-state lasers, novel three-dimensional optical memories, and on-chip integrated circuits.