MICROOPTICS IN CENTRIC DIATOMS

Diatoms are microalgae provided with an external wall, the frustule, made of amorphous hydrated silica and consisting of two valves. Valve surfaces exhibit regular arrays of pores with sub-micrometric dimensions. More than 100000 species of diatoms, characterized by different shapes and dimensions, have been discovered and classified. Diatoms frustules are very intriguing model systems to exploit material and morphological features at the micro and the nanoscale without facing the technological difficulties due to the fabrication processes. Due to their chemical composition and geometries, frustules are photoluminescent and on exposure to bio-chemical compounds the light emission strongly changes. The symmetry of these microshells reveals some unpredictable optical properties, such as light focusing.