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Researchers Spot New Phenomenon That Can Solve Wavelength Splitting Problem In Lasers

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Diffraction of a laser. Researchers were able to find a simple way to address the problem of splitting wavelengths in quantum dot lasers. By simply teaming up two quantum dots, they were able to create a singular wavelength free of the defect.   ( Wikimedia Commons )

Scientists have fashioned a way to eliminate the problem of splitting light from quantum dot lasers: by simply coupling two together.

A team from the University of Utah, Georgia Institute of Technology, Hongik University in South Korea, and the Air Force Research Laboratory banded together to find a way to find a way to correct the defect in quantum dots. Their work, if successful, can one day enable microchips that code information using light instead of electrons.

A paper on the effort was published in the journal Nature Communications.

Quantum Dots' Splitting Light

The problem lies on quantum dots, the nanoscale crystals of semiconductor materials. There is a demand for quantum dots because they can be tuned to the desired wavelength by altering their sizes.

However, quantum dot lasers come with a major defect: they split the light into multiple wavelengths, distributing energy and therefore, making them less powerful.

For quantum dot lasers to concentrate all of its power into one wavelength, the collaborators from Georgia Institute of Technology produced 50 microscopic disk-shaped quantum dot lasers out of cadmium selenide. The team partnered two lasers together in an attempt to correct the splitting light.

The next step was to put one laser in full gain. To achieve the maximum energy possible, the researchers used a second green light, called pump light, onto the first laser.

They reported that the quantum dot laser absorbed the green light and re-emitted it to a more powerful red light.

The researchers explained that when the second light had no gain, splitting still occurred. The green light increased the second light's gain, closing the difference in gain between the two lasers, correcting the split. They were able to achieve concentrated energy into one wavelength

According to the team, this is the first time that the phenomenon has been observed.

Revolutionizing The Future Of Tech

The researchers believe that their work provides an option for a quantum dot laser rid of its fault using resources already at hand.

"It's not impossible that someone could make a defect-free laser with quantum dots, but it would be expensive and time-consuming," said Evan Lafalce, a professor of physics and astronomy at the University of Utah. "In comparison, coupling is a quicker, more flexible, cost-effective way to correct the problem. This is a trick so that we don't have to make perfect quantum dot lasers."

The findings could also aid in the new field of optics and photonics research, which involves the use of light to carry information in electronics. By providing a laser without the splitting wavelength will be necessary for the control of information.

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