A phase-change nanolithography technique is developed to fabricate up to millions of two-/three-dimensional nanostructures (∼50nm) over a large area at a high speed by combining femtosecond laser, microlens array, and wet etching process. Near-field scanning optical microscopy, electrical force microscopy, and atomic force microscopy were used to characterize optical and electrical properties of crystalline and amorphous states, respectively. Different reactions of both amorphous and crystalline areas in phase-change film to alkaline solution are demonstrated. Multiphoton absorption and ultrashort pulse contribute to nanostructure generation. This method opens up a route for nanodevice fabrication with phase-change material.

Carbon nanoparticle colloids were prepared by Nd:YAG laser ablation of a carbon target immersed in water. The nanoparticles were collected on substrates and analyzed with micro-Raman spectroscopy and electron microscopy. Optical limiting properties of the carbon nanoparticle colloids towards 532 nm wavelength were characterized using a nanosecond Nd:YAG laser. A strong optical limiting response was detected for the carbon nanoparticle colloids with C 60 as reference at input laser fluence above 0.6 J/cm 2 . The effects of carbon nanoparticle concentrations upon the optical limiting behavior were also investigated. A convenient method for preparing carbon nanoparticle based optical limiters is proposed in this investigation.

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