Digital data storage using volume holograms offers high density and fast readout. Current research concentrates on system design, understanding and combating noise, and developing appropriate storage materials. Possible applications include fast data servers and high-capacity optical disks.

as the rapid increase in available storagecapacity fueled the demand for storage, orvice versa? It’s hard to say: Computer users’hard disk drives are perpetually overflow-ing with data, even though a year earlier thesame-size disk seemed more than sufficient. Researchinto and development of data storage devices is a raceto keep up with this continuing demand for morecapacity, more density, and faster readout rates.Improvements in conventional memory technolo-gies—magnetic hard disk drives, optical disks, andsemiconductor memories—have managed to keeppace with the demand for bigger, faster memories.However, strong evidence indicates that these two-dimensional surface-storage technologies areapproaching fundamental limits that may be difficultto overcome, such as the wavelength of light and thethermal stability of stored bits. An alternativeapproach for next-generation memories is to store data in three dimensions.In this article we discuss recent developments inholographic 3D memories,