Nanostructures for photonic applications

This thesis focuses on the fabrication and optical properties of the different nanostructures, namely silver nanoparticles, nanolaminates, and silicon nanostrip and slot waveguides. In the first part, two different silver nanoparticle fabrication techniques into glass are introduced and their surface-enhanced Raman scattering (SERS) properties are studied. A silver ion exchange with a heat treatment is a very simple way to produce SERS substrates. The benefit of the two-step ion exchange is the possibility to fabricate silver nanoparticles only at specific areas with desired shapes and sizes. In the second part, ZnO/Al2O3 and TiO2/Al2O3 nanolaminates are fabricated by atomic layer deposition (ALD). About 1 nm thick amorphous Al2O3 layer between the crystalline material (in this study, ZnO and TiO2) is used to limit the size of the crystals in the nanolaminate. In the ZnO/Al2O3 nanolaminates, the third order optical nonlinearity is enhanced using thin ZnO intermediate layers. In the TiO2/Al2O3 nanolaminates, the slab waveguide propagation loss as low as 2 dB/cm is achieved using very thin TiO2 intermediate layers. In the third part, silicon slot and strip waveguides combined with ALD materials are studied. ALD is used to fully fill the silicon slot waveguides and Al2O3 filled slot waveguides are shown to be suitable for applications where low nonlinearity and low-loss waveguides are needed. The multiple slot waveguide for both TE- and TM-polarizations is demonstrated by growing a 50 nm thick ALD Al2O3 layer upon the silicon slot waveguide and then covering the structure with a 130 nm thick ALD TiO2. Broad-bandwidth polarization independent operation of a silicon nanostrip waveguide ring resonator is achieved using a 150 nm thick ALD TiO2 cover layer.