ArsTechnica: "Peacock feathers can emit laser beams." They are famous for their iridescent colors, irrespective of an observer's viewing angle. But they can also emit laser light when dyed multiple times, according to a paper published in the journal Scientific Reports. Iridescent colors in peacock feathers + butterfly wings arise not from pigment molecules but rather nanostructure. "The scales of chitin (a polysaccharide common in insects) in butterfly wings, for example...are arranged like roof tiles, forming a diffraction grating, except photonic crystals only produce certain colors, or wavelengths, of light, while a diffraction grating will produce the entire spectrum, much like a prism." 'In feathers, it's the regular, periodic nanostructures of the barbules—fiber-like components composed of ordered melanin rods coated in keratin—that produce the iridescent colors...different colors correspond to different spacing of the barbules.  Photonic crystals, [also known as photonic bandgap materials] are "tunable," or precisely ordered to block certain wavelengths of light while letting others through. "Applications could include iridescent windows, self-cleaning surfaces for cars + buildings, even waterproof textiles; paper currency could incorporate encrypted iridescent patterns to foil counterfeiters." There have been prior examples of random laser emissions in everything from stained bovine bones and blue coral skeletons to insect wings, parrot feathers, and human tissue, as well as salmon iridiphores. The researchers dyed peacock feathers multiple times, then observed emissions in 2 distinct wavelengths for all color regions of the feathers' eyespots, with the green color regions emitting the most intense laser light. I can just see the next superhero—Peacock—emitting laserbeams in multiple directions at once. Biff, boom, zap.
