Aluminum for nonlinear plasmonics: Methods Section Marta Castro-Lopez, † Daan Brinks, † Riccardo Sapienza, † and Niek F. van Hulst ∗,† ICFO - Institut de Ciencies Fotoniques , and ICREA - Institució Catalana de Recerca i Estudis Avançats E-mail: Niek.vanHulst@ICFO.es Fabrication All antennas presented in this study were nanorod metallic structures made by e-beam lithography using PMMA as positive photo-resist and depositing the metals by thermal evaporation. The height of these nanorods was fixed at 40 nm for all the experiments described in this paper. In the first experiment the width was kept constant at 40 nm while the length was varied from 50 nm to 540 nm in steps of 10 nm. Rods with increasing length were arranged on a single line with a separation of 2 μ m between consecutive rods. Four copies of this line were placed on the same matrix to check the reproducibility of the lithography process. Scanning electron microscope (SEM) images were taken to check surface and shape features of the rods. In following experiments the length and the width of the rods were both varied in steps of 10 nm from 50 nm to 300 nm. The rods were arranged in a matrix where the length increased in ∗ To whom correspondence should be addressed † ICFO - Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain ‡ ICREA - Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain 1