We propose a thin, single-layered circular dichroic filter with Au nanospiral structures on a polydimethylsiloxane (PDMS) thin film that has strong circular dichroism at visible wavelengths. Au nanospiral structures with a diameter of 70 nm were fabricated by cryogenic glancing angle deposition on a substrate with a nanodot array template patterned with the block copolymer PS-PDMS. The Au nanospiral structures were transferred onto a transparent and flexible PDMS thin film to fabricate a thin, single-layered circular dichroic filter. The filter had a very large circular dichroism peak of -830 mdeg at 630 nm. The results show that the Au nanospiral structures transferred onto PDMS thin film exhibit large circular dichroism at visible wavelengths.
Keywords: chirality; circular dichroism; metamaterial; optical filter.