Femtosecond Laser Makes Color Images in Glass

Researchers at Japan Science and Technology Corp. in Kyoto have demonstrated the space-selective precipitation of metal nanoparticles inside glass. The technique, which they described in the Oct. 14 issue of Applied Physics Letters, can be used to create 3-D multicolor images inside transparent glass and to make integrated micro-optical switches.

In the demonstration, they focused mode-locked 120-fs pulses from a regeneratively amplified, 800-nm Ti:sapphire laser through a 10X objective lens onto the interior of Ag⁺-doped silicate glass. After irradiation at room temperature, a portion of the silver ions reduced to silver atoms, and a 10-µm spot with a 40-µm-diameter gray area formed in the focused area of the laser beam. After the scientists annealed the glass at 550 °C for 10 minutes, the silver atoms gathered to form nanoparticles, and the spot turned yellow.