Creating shadows: physicists have discovered an unusual property of lasers and its significance (photo).

Light particles, or photons, move until they encounter an object they cannot pass through. This blockage creates a shadow, resulting in darkness where the light has been obstructed. Physicists have discovered something unusual. A laser passing through a transparent material can cause its surroundings to become opaque, almost as if it is casting its own shadow. When two beams of laser light intersect in a specific manner, the primary beam cannot pass through the secondary one, creating a shadowed line in the light that falls onto the opposing surface. According to scientists, demonstrating this optical effect prompts a reevaluation of the concept of shadow. The research findings have been accepted for publication in the journal Optica, reports ScienceAlert.

Photons do not interact with each other except under special circumstances. When two light beams cross, they pass through one another as if nothing is there. Physicists have studied how light beams interact with nonlinear materials. These materials exhibit interactions with light that do not scale linearly, resulting in effects such as amplification, absorption, self-focusing, and frequency replication.

The scientists decided to conduct an experiment to demonstrate that lasers can block light and create shadows. They used ruby, a popular material for studying nonlinear optics. Ruby served as the meeting point for two lasers—a blue one and a green one.

The blue laser was directed at one side of the ruby, where it passed through and cast a cool glow onto a screen, while the green laser approached perpendicular to the first beam of laser light from the other side.

Wherever the line of green light struck the ruby molecules, a complex movement of electrons occurred, rising and falling. As a result, the slightly shorter wavelength of the blue laser light was disrupted by the movement of electrons, blocking its path through the otherwise translucent material.

Thus, the green laser beam created a dark line in the blue light reaching the screen on the opposite side of the ruby. This dark line met all the criteria to be classified as a shadow. The shadow was visible to the naked eye, matched the contours of the screen onto which it was cast, and moved along with the green laser beam as the light source was adjusted.

According to the physicists, this discovery expands the understanding of the interaction between light and matter and opens up new possibilities for utilizing light in ways previously unconsidered. The researchers believe that this new finding could be beneficial for applications in optical technologies.