Universal Preparation of Novel Metal and Semiconductor Nanoparticle-Glass Composites with Excellent Nonlinear Optical Properties

We report on a simple and universal method for fabricating various kinds of metal and semiconductor (Si, Ge, Bi, and Cu) nanoparticle-glass composites by using metallic Al as a reducing agent in the raw materials of the glass batches. By taking advantage of the redox equilibrium that sets up between the Al reducing agent and various oxides, crystal nuclei such as Si and Ge atom clusters are already formed during the melt-quenching stage. During the subsequent heat-treatment stage, the nanoparticles grow on the nuclei by a process of diffusion. The nanoparticle size can be controlled by heat-treatment temperature and holding time. The fabricated nanoparticle- glass composites exhibit large third-order optical nonlinearities (Χ up to 10 esu) and an ultrafast response time (within picoseconds), which makes them possible to manufacture ultrafast all-optical switches.