Ann Emrick Deputy Director for Operations | Brookhaven National Laboratory
Ann Emrick Deputy Director for Operations | Brookhaven National Laboratory
Scientists have discovered that laser light can cast a shadow, challenging traditional notions of shadows and opening up new technological possibilities. Under certain conditions, a laser beam can act like an opaque object, casting a shadow due to a nonlinear optical process.
Raphael A. Abrahao, from Brookhaven National Laboratory and previously at the University of Ottawa, led the research team. "Laser light casting a shadow was previously thought impossible since light usually passes through other light without interacting," said Abrahao. The findings were published in Optica, Optica Publishing Group’s journal for high-impact research.
The researchers used a ruby crystal and specific laser wavelengths to demonstrate that a laser beam could block light and create a visible shadow. This effect occurs when light interacts with material in an intensity-dependent way, influencing another optical field.
"Our understanding of shadows has developed hand-in-hand with our understanding of light and optics," said Abrahao. He added that this discovery could be useful in applications such as optical switching or technologies requiring precise control of light transmission.
The idea originated during a lunch conversation about experimental schematics depicting the shadow of a laser beam using 3D visualization software. This sparked curiosity among scientists about replicating it in the lab. "What started as a funny discussion over lunch led to a conversation on the physics of lasers and the nonlinear optical response of materials," said Abrahao.
To test their hypothesis, researchers directed a high-power green laser through a cube made of ruby crystal while illuminating it with a blue laser from the side. The interaction created a visible shadow where the green laser blocked the blue light.
"This discovery expands our understanding of light-matter interactions and opens up new possibilities for utilizing light in ways we hadn’t considered before," said Abrahao. Experimentally measured results showed maximum contrast similar to that of natural shadows.
The researchers plan to explore other materials and wavelengths for similar effects. Their paper titled “The shadow of a laser beam” was authored by R.A. Abrahao et al., published in Optica (2024).
Optica Publishing Group is known for its extensive collection of peer-reviewed content in optics and photonics, advancing research worldwide.
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