Scheme optimizes light chips

Researchers from the Technical University of Denmark have borrowed a design tool developed for mechanical engineering to improve the efficiency of nano-size optical waveguides.

The method could be used to manufacture cheap, efficient optical components for telecommunications that could potentially increase data transfer rates by three orders of magnitude, according to the researchers. The devices could also be used to make minute lasers, lower-power light-emitting diodes and tiny, efficient sensors.

The researchers' method uses topology optimization, a method for solving the mechanical and civil engineering problem of finding structures with optimal stiffness-to-weight ratios, to design photonic crystals. Photonic crystals are light-guiding structures made from patterns of rods or a solid that contains patterns of holes.

Traditionally, topology optimization algorithms add material where stresses are high and subtract material in regions that are not loaded; an optimal structure emerges after many repeats of the process. Rather than distributing holes to obtain a optimal transfer of forces, the researchers' method distributes holes in a material to find a structure with the optimal light transfer.

The researchers' tests have shown that the method works for any size or shape material. The method made it possible to improve the performance of 120-degree bends in photonic bandgap waveguides tenfold, according to the researchers.

Some practical applications could be ready in three to five years. Full-scale, on-chip integration of the devices with electronics will take 10 to 15 years, according to the researchers. The work appeared in the May 3, 2004 issue of Optics Express.