As computer chips become ever more prodigious in their data-processing capacities, the task of shuttling all those gigabits around inside a chip becomes an increasing challenge. Help may be on the way in the form of photonic components, which deal in pulses of light instead of slower packets of electric charge. For several years researchers have been making so-called silicon optical waveguides, in which light speeds along inside the ridge between two channels as if along an optical fiber.
But such optical interconnects must deliver their data at precise times, which requires delaying the light pulses by controlled amounts. One method is to send the light pulses into microscopic loops made of waveguides where they circulate dozens of times before continuing on their journey. Yurii A. Vlasov and his co-workers at the IBM Thomas J. Watson Research Center in Yorktown Heights, N.Y., sent pulses of light through strings of as many as 100 such loops without suffering prohibitive losses of data.