Ex-IITian unveils filters to enhance data transmission for optical networks

Washington, February 19 : An alumnus of the Indian Institute of Technology, Bombay has announced the conception of a potentially perfect way to sort and distribute the massive amounts of data that travel daily over optical fibres to people across the world, as part of a project he undertook as a physicist at the U.S. Department of Energy's Ames Laboratory.

Rana Biswas says that the new technology, a three-dimensional photonic crystal add-drop filter, shows promise to dramatically enhance the transmission of multiple wavelength channels (wavelengths of light) that travel along the same optical fibre.

He sees the new innovative filter as a significant achievement in the efforts to develop all-optical transport networks.

According to him, such a network may eliminate electrical components from optical transmission links. It may even guarantee virtually flawless data reception to end users of the Internet, and other fibre-based telecommunications systems, he adds.

"There are up to 160 wavelength channels traveling through an optical fiber at the same time," said Rana Biswas, one of the developers of the new add-drop filter.

"That means a lot of dialogue is going on simultaneously," added Biswas, who is also an Iowa State University adjunct associate professor of physics and astronomy and electrical and computer engineering.

The researcher says as information is transported over these multiple channels, it is necessary to drop off individual wavelength channels at different points on the fibre. At the same time, it's essential to be able to add data streams into unfilled wavelength channels.

"When the data being transported in multiple frequency channels over an optical fibre comes to a receiving station, you want to be able to pick off just one of those frequencies and send it to an individual end user. That's where these 3-D photonic crystals come into play," said Biswas.

He and his colleagues have successfully showed that 3-D photonic crystals may serve as add-drop filters, and thereby provide greatly enhanced data transmission.

The researchers used a three-dimensional, microwave-scale photonic crystal constructed from layered alumina rods and containing a full bandgap, a wavelength range in which electromagnetic waves cannot transmit, to prove their concept.

Biswas says that just like electronic bandgaps that prevent electrons within a certain energy range from passing through a semiconductor, photonic crystals create photonic bandgaps that confine light of certain wavelengths.

This is not the first time that the idea to use photonic crystals for add-drop filters has been conceived, as many research groups worldwide have been working to develop the technology with two-dimensional photonic crystals since the mid Nineties.

"It works, but there is loss of some intensity to the end user because 2-D photonic crystals don't confine the light completely. For example, in a phone conversation, the voices would dim out. But with 3-D photonic crystal add-drop filters, the communication would be clear," Biswas said

The researcher says that one great challenge before his team now is to get the size of the photonic crystals down to work at the wavelengths used for Internet communications.

ANI