Inspired by the chameleon, scientists develop a laser that changes colors

What might be so special about a very small laser that can change the color of the light it emits? Well, Illinois-based researchers based their new nanolaser on the natural ability of the chameleon to alter the coloration of its skin at the nano-scale level, an article on News Wise stated.

The chameleon is best known for changing its skin color. Sometimes it does so to hide from predators and prey. Other times it is a reflexive reaction to the changing temperature. But mostly the color-changing abilities serve as a means of communication with other chameleons, either to attract females or to drive off rival males.

For the longest time, the reptile was thought to use pigments in its skin to change its colors, because that was what many other color-changing animals used. However, Swiss researchers showed that the chameleon has a layer of special guanine nanocrystals within their skin.

This lattice of special cells can reflect different wavelengths of light depending on the space between each cell. Red, orange, yellow, and green have long wavelengths. Meanwhile, blue, indigo, and violet have short wavelengths.

A chameleon can manipulate this layer of cells by exciting them to increase the distance between each cell. By rearranging these nanocrystals so that they are closer or further apart, the animal can change colors very quickly.

Researchers from Northwestern University (NU) took cues from the Swiss study and Nature’s playbook. Their recently-displayed nanolaser also changes the wavelength of the laser in the same way a chameleon’s skin does.

Among the possible uses for this laser are flexible optical displays for mobile devices and television sets, highly-sensitive sensors that can detect strain, and wearable electronics that use photonic devices. The NU researchers published their findings in the journal Nano Letters. (Related: New laser-based system can locate small methane leaks in an area of several square miles.)

New nanolaser mimics chameleon color-changing ability

“Chameleons can easily change their colors by controlling the spacing among the nanocrystals on their skin, which determines the color we observe,” explained NU professor and co-corresponding author Teri W. Odom, regarding the biological basis of her work. “This coloring based on surface structure is chemically stable and robust.”

Odom’s lab hosted the research group working on the nanolaser. Led by NU researcher Danqing Wang, they built the device on a stretchable matrix made from polymers.

Much like how the chameleon increases or decreases the space between guanine nanocrystals in its skin, the human researchers can do the same for the matrix. Stretching the matrix increased the distance between the nanoparticles.

This created very sharp lattice plasmon resonances with out-of-plane charge oscillations that can withstand a significant lateral strain. The wavelength of the resulting light becomes much longer.

On the other hand, causing the matrix to contract draws the particles together even closer than before. Corrspondingly, the wavelength of light becomes much shorter.

Odom claimed that the ability to stretch and release the elastomer substrate allows the laser to switch to the appropriate wavelength for the job at hand. She said the new NU nanolaser is much more flexible, enjoys high sensitivity to strain, can be reversed, and is very sturdy compared to conventional ones.

A compact laser that could adjust its wavelength would be perfect for the advanced electronic systems that are widely used. Optical displays could become more responsive to their users, tiny but capable photonic circuits could be installed on computer chips, and the multiplexing abilities of optimal communication equipment would be massively improved.

Find more articles about new technologies that borrow from nature’s repository of knowledge at Discoveries.news.

Sources include:

Newswise.com

Nature.com

Pubs.ACS.org