PORTLAND, Ore. Fiber optics for communications have vastly more bandwidth than standards networks, but cannot be manipulated as easily as electrical signals.
By inserting crystalline silicon into the core of conventional optical fibers, Clemson University researchers hope to harness the embedded semiconductors to process optical signals. Applications could include multiplying frequencies and providing access to longer wavelengths not currently available when using conventional glass fibers.
"You can make silicon semiconductor core fiber just like you could a glass fiber," said Clemson University professor John Ballato. "The two biggest applications or opportunities are longer wavelengths--three to seven microns for [electronic] countermeasures and for medicine.
"Secondly [silicon core fibers] could be very useful for taking the high powers that we can produce in the visible and near-infrared and frequency-shifting them out to the mid-infrared. That is the next step."
The researchers claim they have demonstrated for the first time that silicon core optical fibers can be mass produced merely by modifying the equipment used to manufacture conventional optical fibers. Optical fibers are currently made with molten glass, wrapped with a slightly different glass, that is pulled into long fibers.
Since the melting point of silicon is lower than that of conventional optical fibers, the researchers said they were able to insert molten silicon cores while the optical fibers were being pulled, resulting in fibers that can be mass produced, but which house a crystalline silicon semiconducting core.
The crystalline silicon core fibers outperformed conventional glass optical fibers while allowing longer wavelengths besides the 1.5-micron wavelengths used for telecommunicaitons. Devices that operate at 3 to 7 microns could be used in countermeasure devices to defeat radar-guided missiles. Medical scanners that work at the longer wavelengths also could benefit from the silicon core optical fibers.