Optical properties modification of gold doped glass induced by nanosecond laser radiation and annealing

In this work the effects of laser radiation and annealing process on the change of the optical properties of gold doped borosilicate glass are presented. The glass is fabricated by conventional melt quenching method as samples with three different concentrations of gold are produced. The laser irradiation is performed by a Nd:YAG system that generates nanosecond pulses at wavelengths of 1064, 532, 355, and 266 nm. The optical properties of the glass samples are studied on the basis of their transmission spectra in the UV- near IR spectral range. The results indicate that irradiation at wavelength of 266 nm induces color changes assigned to formation of defects (color centers). Annealing of the samples results in formation of red colored zones which positions correspond to the irradiated ones. The optical properties and TEM observation indicate that this effect is related to formation of gold nanoparticles. The optical spectra of the areas irradiated by laser pulses and annealed are studied for different processing parameters - pulse number, laser fluence, annealing temperature, annealing time, and the gold concentration in the glass. Processing parameters that ensure efficient tuning of the optical spectra are defined. The presented study can be a basis for a method for surface modification of glass samples that can lead to formation of nanoparticle composed layer with tunable optical properties for applications as novel optical elements.