Qu Shiliang

Influence of Femtosecond Laser Irradiation and Heat Treatment on Precipitation of Silver Nanoparticles in Glass

Silver nanoparticles were precipitated inside an Ag2O-doped glass by femtosecond laser irradiation and successive heat treatment. The influence of heat treatment temperature on the precipitation of silver nanoparticles was investigated. Absorption spectra show that the femtosecond laser irradiation results in an apparent decrease of the treatment temperature for the precipitation of Ag nanoparticles. We demonstrate the control of precipitation, dissolution and growth of silver nanoparticles inside glass by changing the heat treatment temperature or using further femtosecond laser irradiation.

Preparation and nonlinear optical properties of Au colloid

Colloidal Au less than 20 nm was prepared in an aqueous solution of HAuCl4 by irradiation with a near-infrared femtosecond laser. The absorption peak around 526 nm in the absorption spectra and the peaks 2θ = 38.3° and 2θ = 44.3° in the x-ray diffraction (XRD) pattern indicated the formation of Au colloid. Nonlinear optical properties of Au colloid were investigated by using the Z-scan technique with 8 ns pulses at 532 nm. The transition characteristics from self-defocusing to self-focusing and from saturable absorption (SA) to reverse saturable absorption (RSA) were observed for the Au colloid.

Properties and stability of nanosecond optical limiting of gold nanoclusters

Optical limitation (OL) performances of the gold nanoclusters protected by C60-tpy have been investigated with 8 ns pulses at 532 nm. The experimental results show that the nanocomposite possesses OL effects superior to C60 in toluene. The main mechanism of OL is attributed to the nonlinear absorption and subsequently induced nonlinear scattering during excitation of the pulse. Ageing of the nanocomposite chloroform solution in air lowers the OL performances by a factor of 2.4, which can be due to the formation of aggregates of large gold particles.