Shine a flashlight into a murky pond water and the beam won't penetrate very far. Absorption and scattering rapidly diminishes the intensity of the light beam, which loses a fixed percentage of energy per unit distance traveled. That decline—known as exponential decay—holds true for light traveling through any fluid or solid that readily absorbs and scatters electromagnetic energy.
But that's not what researchers at the National Institute of Standards and Technology (NIST) found when they studied a miniature light-scattering system—an ultrathin layer of silicon nitride fabricated atop a chip and etched with a series of closely spaced, periodic grooves. The grooves create a grating—a device that scatters different colors of light at different angles—while the silicon nitride acts to confine and guide incoming light as far as possible along the 0.2-centimeter length of the grating.
Read more: https://phys.org/news/2022-04-unexpected-behavior-harnessed-optical-sensors.html
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