THE USE IN PRINTING OF THE PHOTONIC BAND GAP AS A PARTICULAR FEATURE OF PHOTONIC CRYSTALS
The photonic crystals are macroscopic structures. They exhibit many properties over which numerous tests are conducted. These crystals, thanks to the presence of so-called photonic band gap, cause conscious control of the course of electromagnetic waves. This property allows the conscious design of colors, because the color is not created by additive or subtractive synthesis, such as RGB or CMY, but through photonic changes taking place in the structure. The change in color may change due to changes in the viewing angle of the print or other external stimuli applied to the printed substrate.
Photonic crystals, thanks to their introduction to pigments, are used in printing mainly as a kind of security for documents or product brand. It is difficult to fake such documents because they can not be scanned or copied. After some time, the possibility of producing photonic paper, which would solve the problem of environmental pollution, was also considered. The recorded image would disappear after some time and the paper could be re-used.
Conducting experiments related to acquiring knowledge about the properties of photonic crystals is very expensive. The conditions for mass production have not yet been developed. It is expected that the structure of these crystals provides a new approach to light issues.