SOUTHAMPTON, ENGLAND - A team from Penn State University (University Park, PA) and the University of Southampton has demonstrated a hybrid semiconductor and optical fiber technology that allows optical fibers to be constructed, and the functional materials to be chemically deposited, in distinct and independent steps, giving the full design flexibilities of both platforms. The new technology offers an opportunity to build hybrid devices that will perform light generation, detection, manipulation, and switching functions faster and more effectively than before.

“In essence, this new technique provides a platform for devices, systems and technologies that may revolutionize communications, as well as many other areas,” said Pier Sazio of the Optoelectronics Research Centre in the University of Southampton. “So far the team has demonstrated a transistor inside a fibre using this technique, but other optoelectronic devices like diode lasers could mean a fundamental advance in the way optical communications works.”

Semiconductor devices have been grown inside micro structured optical fibers (MOFs). Advantages include the fact that the light does not have to leave the fiber to interact with the electronic devices, and also that the devices can interact with the light over a long distance within the fiber, making use of effects that would not otherwise be strong enough to be useful. Researchers expect that the new technology to have applications in fields as diverse as communications, medicine, computing, and remote sensing devices.

The generally preferred method for depositing semiconductors and metals is chemical vapor deposition (CVD). However, CVD onto the walls of the long, extremely narrow pores in a MOF presents challenges in terms controlling the deposition and the mass transport of reactants into, and by-products out of, such a confined space. In this work, high-quality polycrystalline and single-crystal semiconductors are deposited within the voids of MOFs by using high-pressure microfluidic chemical deposition. The high-pressure flow is possible because of the very high mechanical strength of optical fibers, and it overcomes mass-transport constraints, producing what the team claims is a “strikingly uniform, dense, and conformal annular deposition” onto the capillary walls, even for pores that reduce to less than 10 nm in diameter.

“At present you still have electrical switching at both ends of the optical fiber. If we can get to the point where the signal never leaves the fiber, it will be faster and more efficient,” said John Badding of Penn State. “If we can actually generate signals inside a fiber, a whole range of optoelectronic applications become possible. For example, in endoscopic surgery, by building a laser inside the fiber you might be able to deliver a wavelength that could not otherwise be used.” - Bridget K. Marx

Sat Apr 01 00:00:00 CST 2006