Peacocks have a secret hidden in their brightly colored tail feathers: tiny reflective structures that can amplify light into a laser beam. After dyeing the feathers and energizing them with an external light source, researchers discovered they emitted narrow beams of yellow-green laser light. They say the study, published in July 2025 in Scientific Reports, offers the first example of a laser cavity in the animal kingdom.
Matjaž Humar, a Biophotonics researcher at the University of Ljubljana who recently published a study on edible lasers, calls the study “novel and inspiring.” He says it “is a fascinating and elegant example of how complex biological structures can support the generation of coherent light.”
Lasers are created when a so-called gain medium, often a dye, is “pumped” with energy, which excites the medium’s electrons to higher energy levels. When those electrons fall back to lower energy states, they release their energy by emitting photons of specific wavelengths. Those photons, in turn, can trigger neighboring excited atoms to relax and release photons of their own.
The light is further amplified and ordered into a coherent beam by having it bounce back and forth within a reflective cavity. In a conventional laser, the beam eventually passes through a partial mirror. However, in a natural laser, microscopic reflective textures can function as cavities that amplify and release light in different ways.
Scientists have long known that peacock feathers also exhibit “structural color” — nature’s pigment-free way to create dazzling hues. Ordered microstructures within the feathers reflect light at specific frequencies, leading to their vivid blues and greens and iridescence. However, Florida Polytechnic University physicist Nathan Dawson and his colleagues wanted to go a step further and see whether those microstructures could also function as a laser cavity.
After staining the feathers with a common dye and pumping them with soft pulses of light, they used laboratory instruments to detect beams of yellow-green laser light that were too faint to see with the naked eye. They emerged from the feathers’ eyespots, at two distinct wavelengths. Surprisingly, differently colored parts of the eyespots emitted the same wavelengths of laser light, even though each region would presumably vary in its microstructure. If this were mere coincidence, it “would be like rolling two 100-sided dice and always getting 74 from one die and 83 from the other,” Dawson says.
Marco Giraldo, a Biophysicist at the University of Antioquia who studies structural color, points out that the study does not identify the exact microstructures that are doing the lasing. To explain the consistency of the signal, the cavities throughout the feathers would need to have sizes and shapes that are identical to subnanometer precision. That precludes the hollow parts of the feather, which are too varied, as well as the rod-shaped microstructures known to give peacock feathers their structural color. Dawson hypothesizes that some other distinctive and small structures within the feathers — possibly protein granules — are working as the laser cavity.
Just because peacock feathers emit laser light does not mean the birds are somehow using this emission. However, there are still ramifications, Dawson says. He suggests that looking for laser light in biomaterials could help identify arrays of regular microstructures within them. In medicine, for example, certain foreign objects — viruses with distinct geometric shapes, perhaps — could be classified and identified based on their ability to be lasers, he says.
The work also demonstrates how biological materials could one day yield lasers that could be put safely into the human body to emit light for biosensing, medical imaging, and therapeutics. “I always like to think that for many technological achievements that benefit humans,” Dawson says, “some organism somewhere has already developed it through some evolutionary process.”
REFERENCE: Science; 28 JUL 2025; Rachel Berkowitz