Light-emitting biological photonic crystals: the bioengineering of metamaterials

Diatoms can be regarded as self-reproducing photonic crystal slab waveguides due to their silica cell walls that exhibit periodic pore patterns. The algae thus offer possibilities for biotechnological production of photonic crystals. Two techniques for incorporating organic laser dyes into the structures are demonstrated. First, Rhodamine B was covalently attached to the silica by an aminoalkylsilane linker. Second, highly fluorescent Rhodamine derivatives added to the culture medium were successfully taken up by the diatoms and deposited into the shell. By this techniques, it is possible to cultivate dye functionalized diatoms with emission behaviour adapted to photonic resonances.