Tiny T splits light

Photonic crystals contain microscopic holes of specific sizes and spacings designed to block certain wavelengths, or colors, of light. Researchers are working to use these materials to channel and filter light in very small areas.

This could lead to cheaper, more efficient communications devices and high-speed, all optical computers.

Researchers at the Swiss Federal Institute of Technology have designed a compact photonic crystal multiplexer that splits a lightwave into two slightly different colors. Splitting lightwaves is typical of high-speed communications networks that use multiple colors to send several signals over a line at once.

The T-shaped multiplexer has an input channel and a pair of output channels. The input channel has no holes, and the output channels have holes of a different size from each other and from the surrounding crystal.

The multiplexer fits in a section of photonic crystal 13 holes long by nine holes wide, which is smaller than previous photonic crystal designs and many times smaller than today's fiber-optic devices.

The research was funded by the Swiss National Science Foundation. The work appeared in the March 24, 2003 issue of Optics Express.