[1]sciencehabit shares a report from Science.org:

> Peacocks have a secret hidden in their brightly colored tail feathers: [2]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, [3]published this month in Scientific Reports , offers the first example of a laser cavity in the animal kingdom. [...]

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> 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. But 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.

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> Just because peacock feathers emit laser light doesn't mean the birds are somehow using this emission. But 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."



[1] https://slashdot.org/~sciencehabit

[2] https://www.science.org/content/article/peacock-feathers-can-be-lasers

[3] https://www.nature.com/articles/s41598-025-04039-8