Better clear a shelf in your basement for that high-end Blu-ray DVD player you just bought. Researchers report that they can boost the amount of data stored on a disc 10,000-fold by using gold nanoparticles. If commercialized, the technology could allow a single disc to hold as many as 300 movies or 250,000 songs.
Today's CDs and DVDs store data as a string of pits burned into a narrow spiral track in plastic discs. Although less of a commercial success, holograms boost data-storage capacities by storing data in three dimensions. In an effort to kick things up a notch, researchers led by Min Gu, an optoelectronics expert at Swinburne University of Technology in Hawthorn, Australia, added two additional dimensions: the color of light used to write and read the data and the light's polarization, or the direction of its electric field.
Researchers have worked for years to encode multiple sets of data in the same spot without interfering with one another. But efforts have been stymied because they've had low spatial resolution. To boost that resolution, Gu's team suspended an assortment of gold nanoparticles of various sizes and shapes in a clear plastic disc. Nanorods absorb certain frequencies of light depending on their size and shape. That allowed Gu's team to write bits with several colors of laser light in the same region. To encode a single bit of data, a laser pulse melts selected gold nanorods. That deformation changes the way light of a particular color or polarization interacts with them, which allows the data to later be read out. The researchers report in today's issue of Nature that they used their scheme to write data in three colors and two polarizations in the same physical space. The approach could allow discmakers to store up to 1.6 terabytes of data on a single disc.
"This is a very interesting technology and might become commercially successful," says Richard Blahut, an optoelectronics engineer at the University of Illinois, Urbana-Champaign. For it to do so, plenty of issues still need to be addressed, such as increasing the speed at which data can be written and creating compact-disc readers equipped with lasers capable of firing light at different colors and polarizations. Gu's team has signed an agreement with Samsung to commercialize the technology.