A new optical data storage technology based on the surface‐enhanced Raman scattering (SERS) effect has been developed for high‐density optical memory and three‐dimensional data storage. With the surface‐enhanced Raman optical data storage (SERODS) technology, the molecular interactions between the optical layer molecules and the substrate are modified by the writing laser, changing their SERS properties, so that they are encoded to store information as bits. Since the SERS properties are extremely sensitive to molecular microenvironments, very small ‘‘spectrochemical holes’’ approaching the diffraction limit can be produced for the writing process. The SERODS device uses a reading laser to induce the SERS emission of molecules on the disk and a photometric detector tuned to the frequency of the Raman spectrum to retrieve the stored information. The results illustrate that SERODS is capable of three‐dimensional data storage. ©1994 American Institute of Physics.