SUPPORTING INFORMATION Wafer scale fabrication of porous three dimensional plasmonic metamaterials for the visible: chiral and beyond Johnson

Fabrication: The SiO2 helical films were fabricated in a commercial Glancing Angle Deposition System equipped with electron beam evaporation and thermal evaporation. We have also experimented with other dielectrics, such as MgF2 and TiO2, and although the results differ in details, the general conclusions of this manuscript remain the same. A glass substrate was placed at 84° angle to the source of incoming vapour and was rotated (clockwise or counter clockwise) at a speed of 0.05 – 0.1 rpm for film evaporation rates of 0.1 – 0.2 nm/second. The choice of the tilt angle and the rotation speed was based on the particular design of the helix, whose details are well described in the literature pertaining to glancing angle deposition. Subsequently, the substrate was tilted so that the normal to the substrate was at 5° to the incoming vapour and rotated at ~ 1.5 rpm while 1 – 20 nm of Ag or Au was evaporated. To prepare the isotropic solution of the helices, a known size of the film (1cm × 1cm) was sonicated in 400 μl of DI water (millipore) for about 1 minute. The solution (~ 250 μl) was transferred to a glass cuvette (5mm × 5mm) for the measurements. For the heating experiments, the glass substrates containing the chiro-plasmonic helical films were placed on a hot plate set at a particular temperature for about 5-30 minutes. During this time, the samples were covered such as to prevent any convective air flow. The CD measurements were performed after the samples were allowed to cool down to room temperature.