Five Dimensional Optical Material

Data rainbow: These six patterns were written within the same area of a new data-storage medium using three different colors and two different polarizations of laser light. Credit: Nature Publishing Group

A new light-responsive material could lead to discs the size of today's DVDs that store four orders of magnitude more data. Traditional DVDs and CDs store data on their surface in two dimensions, and holographic discs can store it in three. Now researchers have for the first time demonstrated what they call a five-dimensional optical material. It can record data in three spatial dimensions and in response to different wavelengths and polarizations of laser light.

The material is being developed by researchers led by Min Gu, director of the Centre for Micro-Photonics at the Swinburne University of Technology in Victoria, Australia. The material is made up of layers of gold nanorods suspended in clear plastic spun flat on a glass substrate. Multiple data patterns can be written and read within the same area in the material without interfering with each other. Using three wavelengths and two polarizations of light, the Australian researchers have written six different patterns within the same area. They've further increased the storage density to 1.1 terabytes per cubic centimeter by writing data to stacks of as many as 10 nanorod layers. In a paper published online today in the journal Nature, Gu's group reports recording speeds of about a gigabit per second.

"You can record each bit by one laser pulse," says Gu. The writing laser melts and reshapes the gold particles, which are less than 100 nanometers long. The changes affect how the nanorods interact with light from a laser-imaging system, allowing the data to be read.