Amplifier brings polymer fiber home

17 Jun 2002

High-gain polymers are set to provide fiber-optic networks with simple and cheap amplification.

Polymer power

Scottish researchers have developed a polymer-based optical amplifier for low cost, short-haul data transmission in polymer optical fibers. Graham Turnbull and colleagues at the University of St Andrews claim that the amplifier - which is based on the semiconducting polymer PPV - is cheap, simple to make and will extend the transmission lengths of polymer fibers.

To generate amplification, the researchers pumped a range of liquid polymer solutions with a tunable 575 to 640 nm dye laser. A 2.0 g/l solution showed a maximum 43 dB gain, over a 500 to 700 nm photoluminescence range.

The researchers believe that these gains demonstrate the polymer's potential as a compact amplifier in optical fibers. "We have shown gains up to 43 dB across the dye tuning range," explained Turnbull. "This range includes the 610 to 640 nm low loss window of poly(methyl methacrylate) fibers which implies the [conjugated polymer] could be useful in these fibers."

Turnbull also adds that the wavelength bands at which the conjugated polymer absorbs and emits light are widely separated, which prevents the material losses that usually plague small-molecule optical amplifiers. These material losses can hamper the extraction of energy from an amplifier.

While the present work involves a liquid polymer solution, the researchers are confident that they will soon produce similar results in solid-state polymer solutions. This will set the amplifiers firmly on the road to commercialization. Turnbull and colleagues also plan to switch from optical to electrical pumping.

"We are currently working on using miniature pump lasers which will lead to a more compact system," said Turnbull. "We plan to use electrical pumping in the next few years, but this will first need some material advances."