We've all seen before. A beautifully painted butterfly that appears when two sheets of paper is open after covering them with paint and pushing them together. Geometrically shaped turtle shell models, or snail shell construction; the leaves of a tasty plant, which repeat over and over, to create a complex pattern; or an ice pattern on the windshield of a car after standing outside during the winter.
These patterns are examples of fractals, the geometry of nature. Fractals are complex forms that we see every day in nature. They have a characteristic feature of repetitive geometry with the structure of multiple scales and are found everywhere – from the Romanesque broccoli to ferns, and even on a larger scale, such as salt, mountains, coastlines and clouds. The shape of the trees and mountains is self-similar, so the branch looks like a small tree and a rocky belt like a small mountain.
In the past two decades, scientists predict that you can also create a fractal laser light. With its high-polished spherical mirrors, the laser is almost precisely the opposite of nature, so it was a surprise when, in 1998, light-emitting lasers were predicted to be fractals. Now the team from South Africa and Scotland have shown that the fractal light can be created by a laser, confirming the prediction of two decades.
Apply this month to Physical examination A, the team provides the first experimental evidence for a fractal light from simple lasers and adds a new prediction that the fractal light should exist in 3D, and not just 2D as previously thought.
Fractals are complex objects with a "pattern within the pattern" so that the structure appears to repeat as you zoom in or out of it. Nature creates such "models in models" from many recursions to a simple rule, for example, to create a snowflake. Computer programs are also used to do so with a cycle through rule over and over, famously making the abstract Mandelbrot kit.
The light inside the lasers also does this: cycles back and forth, jumping between the mirrors of each pass, which can be set to capture the light in itself on every round trip. This looks just like a recursive cycle, repeating a simple rule over and over again. The picture means that every time the light returns to the plane of the picture, it is a smaller (or greater) version of what was: a template within the model within the model.
Fractals have found applications in images, networks, antennas and even medicine. The team expects that the discovery of fractal forms of light that can be made directly from a laser should open up new applications and technologies based on these exotic conditions of structured light.
"Fractals is a truly fascinating phenomenon and is related to what is known as" Chaos, "said Professor Andrew Forbes of the University of Witwatersrand, who led the project together with Professor Johannes Cortial of the University of Glasgow." In the world of popular science, Chaos is called a "butterfly effect," where a slight change in one place makes a big change elsewhere, for example, a butterfly that strikes its wings in Asia causes a hurricane in the United States. proven to be true. "
In explaining the discovery of the fractal light, Forbes explains that his team has realized the importance of looking for fractals in a laser. "Look at the wrong place in the laser and you see only a blotched capsule of light. Look at the right place where the picture is going, and you see fractals."
The project combines the theoretical expertise from the Glasgow team with experimental validation in South Africa from Wits and CSIR (Council for Scientific and Industrial Research). The initial version of the experiment was built by Dr. Darrill Naidu (from CSIR and Wits) and completed by Hend's Sears (Wats) as part of her doctorate.
"What's incredible is that, as predicted, the only condition for demonstrating the effect is a simple laser with two polished spherical mirrors. It was constantly there, it's just hard to see if you do not see the right place," said Sudski.
Materials provided by University of Witwatersrand. Note: The content can be edited for style and length.