NOVELTY - Two- or three-dimensional photonic crystal comprises: first dielectric component comprising fluorinated polymer, where the first dielectric component has a refractive index n1; and second component having a refractive index n2 different from n1, where the first dielectric component comprises fluorinated polymers comprising alicyclic structures in the polymer main chain or elastomers comprising fluoropolyether chains. The crystal comprises many monodisperse spheres made of the second component regularly arranged in a two- or three-dimensional crystalline structure defining interstices.    USE - The photonic crystal is useful in a device (claimed) comprising optical filters, waveguides, lasers, solar cells, sensor and biosensor devices and chromatic stimuli-responsive devices.    ADVANTAGE - The photonic crystal has infiltrated opal or inverse opal structures.    DETAILED DESCRIPTION - Two- or three-dimensional photonic crystal comprises: at least a first dielectric component comprising at least one fluorinated polymer, where the first dielectric component has a refractive index n1; and at least a second component having a refractive index n2 different from n1, where the first dielectric component comprises fluorinated polymers comprising alicyclic structures in the polymer main chain or elastomers comprising fluoropolyether chains. The crystal comprises many monodisperse spheres made of the second component regularly arranged in a two- or three-dimensional crystalline structure defining interstices and the first dielectric component fills the interstices or many monodisperse spheres made of the first dielectric component regularly arranged in a two- or three-dimensional crystalline structure defining interstices and the second component fills the interstices. An INDEPENDENT CLAIM is also included for preparing the two- or three-dimensional photonic crystal comprising: providing many monodisperse spheres made of the first dielectric component or the second component regularly arranged in a two- or three-dimensional crystalline structure, where the monodisperse spheres defines interstices; and infiltrating the crystalline structure with the second component or the first dielectric component or its precursor to fill the interstices between the monodisperse spheres, when the monodisperse spheres are made of the first dielectric component then the interstices are filled with the second component and vice versa to obtain a photonic stop-band.