The first optical fibre made with a core of zinc selenide promises to open the door to more versatile laser-radar technology say researchers at Penn State University.
Advances in optical fibre technology mean light is converted from one colour to another more efficiently
Optical fibre technology is limited by the use of a glass core, but replacing the core with zinc selenide – a semiconductor – allows a more effective and liberal manipulation of light.
“Glass has a haphazard arrangement of atoms,” said John Badding, professor of chemistry. “In contrast, a crystalline substance like zinc selenide is highly ordered. That order allows light to be transported over longer wavelengths, specifically those in the mid-infrared.”
Badding said they’ve known for a long time that zinc selenide is a useful compound that can manipulate light in ways silica can’t, but the trick has been trying to figure out how to get in into a fibre. The fibres were created by depositing zinc selenide waveguiding cores inside silica glass capillaries in an innovative high-pressure chemical-deposition technique developed by graduate student Justin Sparks.
“The high-pressure deposition is unique in allowing formation of such long, thin, zinc selenide fibre cores in a very confined space,” Badding said.
The researchers found the fibres could be useful in two ways. Firstly they were more efficient at converting light from one colour to another – Badding believes this may have beneficial uses in signmaking, art and displays.
Secondly, the fibres provide more versatility in the visible and infrared spectrum where existing technology is inefficient.
“Exploiting these wavelengths is exciting because it represents a step towards making fibres that can serve as infrared lasers,” Badding said. “The military currently used laser-radar technology that can handle the near-infrared, or 2 to 2.5 micron range. A device capable of handling mid-infrared, or over 5-micron range would be more accurate.”
Badding said the fibres they have created can transmit wavelengths of up to 15 microns. He said the technology could also be used to detect pollutants and environmental toxins, and to improve laser-assisted surgical techniques such as corrective eye surgery.