Photonic crystal type structures of biological origin: Structural and spectral characterization

Photonic crystal type structures of biological origin were investigated by scanning electron microscopy (SEM) and UV–VIS reflectance measurements. It was demonstrated that despite the moderate refractive index contrast between chitin and air, biological evolution developed in the wing scale nanostructures of butterflies representing various families, numerous structures with different hues of blue and very different degrees of directionality. Furthermore, for illustrating the variety of purposes for which nature may use photonic structures, the UV protection mechanism of the high altitude flower Edelweiss has been investigated. We present fully supportive data that the protection mechanism is based on coupling by nanostructured, highly selective couplers the harmful UV radiation in propagating modes along fibers containing UV absorbing pigment.