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MATERIALS SCIENCE
A family of inexpensive organic compounds may help push 3-D optical data-storage technology toward commercial viability, according to researchers at Boston College. They found that, upon imprinting data in glasses and polymers made from certain aromatic ethers, the materials remain stable after numerous data reading events. Compared with two-dimensional (surface-layer) magnetic data-storage technology--the type used in computer disk drives--3-D optical methods for storing data offer potential benefits in terms of storage densities. Using 3-D methods, closely spaced data planes throughout the medium can be patterned individually. But despite anticipated benefits, efforts in developing 3-D optical-based technology have been impeded by a lack of satisfactory data-storage materials.
To record information, chemistry professor John T. Fourkas and graduate students Christopher E. Olson and Michael J. R. Previte, now a postdoctoral associate at MIT, used a laser-based method known as multiphoton absorption to write patterns in their data-storage materials. By irradiating the specimens with a tightly focused beam of 800-nm light, the team induced chemical modifications, still poorly understood, at the laser's focal point, where the molecules absorbed several photons simultaneously. Precise 3-D positioning of the focal point led to fine control of data patterns. The submicrometer-sized spots were then detected (read) in subsequent steps using fluorescence techniques. Because of high costs, many scientists have searched for data-storage materials that can be used with low-power lasers. Unfortunately, Fourkas explains, data from most of the materials examined previously degraded as the patterns were read repeatedly. So earlier researchers turned to amplified lasers for readout, which led to robust data-storage systems but jacked up the price. "The materials we have developed are inexpensive, readily available, and are easily process-ed," Fourkas asserts. "Data can be stored in these media and read out efficiently with unamplified ultrafast laser systems." At present, the writing step is quite slow, but the materials can be modified chemically, he adds, which should aid in further optimizing their storage properties. |
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