Device comprising a photonic-crystal structure

A device (D) which can be used in combination with a source of electromagnetic waves comprises a photonic-crystal structure (1) formed by an orderly and periodic series of nanoparticles (2) made of a material which is deformable following upon application of an external stress, preferably a piezoelectric material. The deformation of the nanoparticles (2) is designed to bring about change in the optical characteristics of the structure (1), by modulating its period such as the intensity of the reflected and transmitted beams and the direction of the transmitted beam.