Researchers from the University of Illinois in Urbana-Champaign have induced 610-nm laser emissions in aggregates of silicon as small as 8 µm in diameter. The aggregates were formed by dispersing nanoparticles of silicon from a bulk form through catalyzed electrochemical etching and allowing colloidal aggregates of the silicon to form in water. These were encapsulated in a polymer and then deposited onto a glass substrate.The researchers, who reported their results in the Jan. 7 issue of Applied Physics Letters, used 550- to 570-nm mercury lamps to excite the nanoparticles, which manifest emissions in the form of Gaussian beams. The team also detected line narrowing and speckle patterns, indicating spatial coherence within the aggregates.