Production of dichroitic 3D structures by fs laser irradiation in composite glass containing Ag nanoparticles

By irradiating glass containing spherical Ag nanoparticles successively with fs laser pulses at different wavelengths, we were able to produce three-dimensional, permanent anisotropic modifications based on shape deformations of the natioparticles in this nanocomposite material. This novel method is able to create dichroism in the visible and near IR part of the spectrum by deformation of nanoparticles to oblong shapes oriented parallel to the laser polarization. Using samples with a vertical gradient of the fill factor of Ag nanoparticles in the glass substrate and an accordingly inhomogeneous broadening of the surface plasmon band, modifications in various depths can be made using different excitation wavelengths. The induced modifications are reversible: heating to approximate to 600 degrees C restores the spherical shape of Ag nanoparticles. This technique can be useful for manufacturing of different, 3D, polarization and wavelength selective micro-devices such as polarizers, filters, gratings, display and rewriting optical 3D data storage devices. As examples, we will demonstrate in this paper how (i) three areas of different color can be produced in three different depths of the sample and (ii) how a series of multicolor irradiations can be used to produce dichroic structures of high polarization contrast.