Linear and non-linear optical properties of bimetallic heterodimers
36th Progress in Electromagnetics Research Symposium (PIERS), Prague, July, 5-9, 2015
Metal nanoparticles have attracted great scientific and technological interest in biomolecular detection and clinical diagnostic application due to their specific physical and chemical characteristics. Several reported experimental results illustrated that nanomaterial based non-linear optics assay can be used for monitoring chemical processes, biological and chemical toxins with excellent sensitivity and selectivity [1-4]. Linear optical properties and plasmon resonances of metallic nanoparticles or nano-antennas are well described in the literature by extinction and/or scattering spectroscopies and by radiation patterns in direct or in Fourier space. However, much less is known on their non-linear optical properties, and in the role of plasmon resonances in the enhancement of these effects. Two-photon luminescence (TPL) and second harmonic generation (SHG) both are prominent examples of non linear effects observed on metallic nanoparticles. In this study, we focused on the linear and non linear optical characterization of Au-Al heterodimers. These dimers have been fabricated by a two-step electron-beam lithography process and the diameters of the Au and Al nanoparticles have been independently varied, as for the gap distance. The linear optical properties (single dimer scattering spectra) and the non-linear optical properties (SHG images and TPL spectra) have been compared to understand the main physical phenomena involved.