A PHOTON CONVEYOR BELT has been created using sound waves and lasers, bringing about a new method for processing and storing light signals on a chip. In some opto-electronic devices it is desirable to delay or store an optically-encoded message by dispatching it down kilometer-long fiber cul-de-sacs. In a device developed at the University of Munich, the delay can be accomplished more compactly by first converting the light into a splash of excitons (electron-hole pairs) which propagate at a more leisurely pace, the electrons and holes surfing along on different parts of a guiding acoustic wave. Later the electron-hole pairs recombine into photons, which are read out at the other end of the sample. In effect the signal has been converted from a speed-of- light wave into a speed-of-sound wave, and back again. This technique is also a way of prolonging the lifetime of excitons, which typically live for mere nanoseconds before recombining; in this experiment they have now been preserved for microseconds. (C. Rocke et al., Upcoming article in Physical Review Letters, 26 May 1997; contact Achim Wixforth, Achim.Wixforth @physik.uni-muenchen.de; animation at Physics News Graphics)