An international science team from Penn State
University in the United States and the University of
Southampton in the United Kingdom has developed a process for growing a
single-crystal semiconductor inside the tunnel of a hollow optical
fiber. The device adds new electronic capabilities to optical fibers,
whose performance in electronic devices such as computers typically is
degraded by the interface between the fiber and the device. The
research is important because optical fibers -- which are used in a
wide range of technologies that employ light, including
telecommunications, medicine, computing, and remote-sensing devices --
are ideal media for transmitting many types of signals.
 | | Single-crystal semiconductor wires integrated into microstructored optical wires. Credit: Penn State University |
The development of the single-crystal device, which will be
described in a paper to be published later this month in the journal
Advanced Materials, builds on research reported in 2006, in which the
team first combined optical fibers with polycrystalline and amorphous
semiconductor materials in order to create an optical fiber that also
has electronic characteristics. The group's latest finding -- that a
single-crystal semiconductor also can be integrated into an optical
fiber -- is expected to lead to even further improvements in the
characteristics of optical fibers used in many areas of science and
technology.
"For most applications, single-crystal semiconductor materials
have better performance than polycrystalline and amorphous materials,"
said John Badding, associate professor of chemistry at Penn State. "We
have now shown that our technique of encasing a single-crystal
semiconductor within an optical fiber results in greater functionality
of the optical fiber, as well."
The team used a high-pressure fluid-liquid-solid approach to
build the crystal inside the fiber. First, the scientists deposited a
tiny plug of gold inside the fiber by exposing a gold compound to laser
light. Next, they introduced silane, a compound of silicon and
hydrogen, in a stream of high-pressure helium. When the fiber was
heated, the gold acted as a catalyst, decomposing the silane and thus
allowing silicon to deposit as a single crystal behind the moving gold
catalyst particle, forming a single-crystal wire inside the fiber.
"The key to joining two technologies lies not only in the
materials, but also in how the functions are built in," said Pier
Sazio, senior research fellow in the Optoelectronics Research Centre at
the University of Southampton. "We were able to embed a nanostructured
crystal into the hollow tube of an optical fiber to create a completely
new type of composite device."
The research team sees potential to carry the application to
the next level. "At present, we still have electrical switches at both
ends of the optical fiber," said Badding. "If we can get to the point
where the electrical signal never leaves the fiber, it will be faster
and more efficient."
Posted 13th March 2008
|
