Nanowerk December 30, 2019
An international team of researchers (Lawrence Berkeley National Laboratory, UC Berkeley, Columbia University, Italy, Kazakhstan) found that when an infrared laser excites thulium-doped nanoparticles coated on the surface of the beads, the light emitted by the nanoparticles bounces around the inner surface of the bead. When the intensity of light traveling around these beads reaches a certain threshold, the light can stimulate the emission of more light with the exact same color producing intense light at a very narrow range of wavelengths in the beads. When the team exposed the beads to an infrared laser with enough power, the beads turned into upconverting lasers, with higher frequencies than the original laser. The beads also produce laser light at the lowest powers ever recorded for upconverting nanoparticle-based lasers. The innovation opens the possibilities for imaging or controlling biological activity with infrared light and for the fabrication of light-based computer chips…read more. TECHNICAL ARTICLE
A tiny bead struck by a laser produces optical modes that circulate around the interior of the bead. At right, a simulation of how the optical field inside a 5-micron bead is distributed. (Image: Berkeley Lab)