Because a portion of the light is reflected, it combines with light of the exact same wavelength as it passes back through layer upon layer of chitin, becoming brighter and more intense. Ocean waves can exhibit the same behavior, combining to produce rare but powerful rogue waves. In the case of the beetles, this "perfect storm" of light amplification produces not only the same colors but also the striking sheen and glimmer that we normally associate with fine jewelry.
In the two beetle species, interference patterns are produced by slightly different wavelengths of light, thus producing either silver or gold colors. "For the golden-like beetle, the constructive interference is found for wavelengths larger than 515 nm, the red part of the visible wavelength range," Vargas says, "while for the silver-like beetle it happens for wavelengths larger than 400 nmthat is, for the entire visible wavelength range."
"The detailed understanding of the mechanism used by the beetles to produce this metallic appearance opens the possibility to replicate the structure used to achieve it," Vargas says, "and thus produce materials that, for example, might look like gold or silver but are actually synthesized from organic media."
This potentially could lead to new products or consumer electronics that can perfectly mimic the appearance of precious metals. Other products could be developed for architectural applications that require coatings with a metallic appearance. Vargas notes that in the solar industry, for example, chirped multilayer reflectors could be used as back layers supporting the active or light-absorbing medium, to improve the absorption of the back-reflected light.
|Contact: Angela Stark|
Optical Society of America