FEMTONANO · Femtosecond laser induced nanoclusters in glasses for photonic applications

Femtosecond laser induced nanoclusters in glasses for photonic applications

Glass composite with metallic nanoclusters (e.g. Ag, Ag) or oxide micro-crystals (e.g. LiNbO3) have attracted considerable attention for their ultrafast nonlinear response and large third-order nonlinear susceptibility. They are expected to be promising materials for ultrafast all-optical switches in the tera-hertz (THz) region. Many studies have been carried out on fabrication and characterisation of nanoparticle-doped glasses, but it's difficult to control the spatial and size distribution of nanoparticles in materials by the traditional fabrication method such as melting-quenching, sol-gel, ion exchange and ion implanting etc. For the applications in integrated optoelectronics, a well-defined assembly and spatial distribution of nanoparticles in materials is essential. Femtosecond laser (fs) pulses have shown predominant advantage in the space-selective microscopic processing and formation of the three-dimension (3D) modified microstructures, which is attribute to its ultrashort pulse and ultrahigh peak power, nonlinear optical effects are dominant in the process of femtosecond laser interaction with dielectrics, and this process is strictly limited by the threshold intensity of incident laser. Various kinds of integrated functional opto-devices including 3D optical waveguide, optical memory, grating, coupler, photonic crystal etc have been fabricated by the fs laser processing. In this project, we investigate fs laser induced nanoclusters in glasses for photonic applications. The content of this project consists of the following parts. The first part involves the experiment of modification of gold (silver) nanoparticles in Au3+(Ag+)-doped silicate glasses by the fs laser irradiation. The second part is investigation on the influence of irradiation conditions including laser energy, scanning direction etc., and the oxide glass matrix on the precipitation behaviours of nanoclusters. The possible mechanism of interaction of fs laser with nanoclusters contained glass is also discussed. The content of the third part include study on birefringence behaviour, and the successful laser-induced micro-crystallisation (LiNbO3 microcrystal) in the volume of silica-based glasses. A series of the achieved research results are summarised as follows: By irradiation of a Ti: Sapphire fs pulsed laser in gold nanoparticles doped glass, strong birefringence can be observed. A possible mechanism for the nanoclusters shaping is proposed. The influence of laser irradiation conditions on the precipitation behaviours of nanoclusters was investigated. We reveal the stress fields induced by femtosecond laser irradiation in investigating the surface relaxation topography of cleaved gold doped silicate glass plates in which irradiation were performed; varying intensity and writing direction effect are also described in this part. By femtosecond laser irradiation, we are now able to write crystalline (e.g. LiNbO3) lines inside multicomponent silica glass directly in volume. We identify the laser processing windows and the glass host matrix composition. Such crystallisation technique may pave the way towards 3D optical memories, integrated optical switches, integrated solid state displays and compact solid state laser etc. Due to its ultrashort pulse and ultrahigh peak power, nonlinear optical effects are dominant in the process of fs laser interaction with dielectrics. It appears as a powerful tool for writing optical waveguides, photonic crystals, non-linear materials and maybe also for integrated optic-electronic devices. As a matter of fact, it can be used thanks to some progress for inducing oriented crystallization (e.g. c-axis aligned with the scanning direction) in volume and with a space selection of the order of a few microns. But until now, there is no rational definition which can lead to an easy control of crystal growth orientation inside glasses. We are currently working in this direction towards a quantitative interpretation.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз