A team at Boston College has fabricated structures of agglomerated silver nanoparticles using multiphoton absorption laser fabrication, with potential applications in optics.To produce the structures, the researchers illuminated polymer and silver nitrate films with 250-fs pulses of 780-nm radiation from a Coherent Inc. Ti:sapphire laser operating at a repetition rate of 76 MHz. Following laser exposure, the samples were washed to remove the polymer. Using the laser technique, the researchers created concentric diffraction gratings of silver. © OSA.Although the metal deposition process is not yet fully understood, the technique yields silver features on the order of 5 µm across, composed of nanoparticles that are tens to hundreds of nanometers in diameter.In a demonstration of possible practical uses of the method, the investigators fabricated concentric diffraction gratings with a line spacing of 20 µm in various geometries. Further research will examine the ability of the laser technique to deposit silver on 3-D microstructures fabricated using multiphoton polymerization and to produce patterns that are electrically conductive.