UB-developed photonic materials
could revolutionize data storage

By ELLEN GOLDBAUM
News Services Editor

"Stacks" of data can be packed into the new materials, like pages in a book. Made of extremely inexpensive plastic blended with new dyes designed at UB, the materials store thousands of times more data than conventional compact disks (CDs).

UB researchers also have developed an optical technology to "read" the new materials. The materials and technology were described for the first time Aug. 27 at the national meeting of the American Chemical Society in Orlando, Fla.

Current CDs store information only on their surfaces, but "these new materials could revolutionize data storage because they allow data to be stored in the depth of a disk," said Paras N. Prasad, professor of chemistry, director of the UB Photonics Research Laboratory and principal investigator. Other research team members are Jayant D. Bhawalkar, Ping-Chin Cheng, Ryszard Burzynski, Deepak Kumar, Gary Ruland, Shan-Jen Pan, Ang W. Shih, Wendy C. Chang, Wen-Shan Liou and Mun-Soo Park.

The new materials are capable of storing up to 1 terabyte of data per cubic centimeter, one thousand times more than can be stored in a conventional CD. "You would have to stack more than 1,000 CDs one on top of the other to get the same amount of data that is in 1 cubic centimeter of one of these new materials," said Bhawalkar, UB research assistant professor in the Photonics Research Laboratory.

Prasad showed a video illustrating the new technique and how a confocal microscope probing deep into the material can "read" each frame of a Bugs Bunny cartoon. Several seconds of the cartoon are stored in stacks of data in a cubic volume, each side of which has the thickness of a human hair.

According to Prasad, this may be the first time frames of a movie have been stored in a stacked format and reproduced in a three-dimensional, data-storage medium. The method also will make possible more efficient storage for color movies, which require three times as much storage space as black-and-white images.

At the heart of the new materials is 'two-photon absorption,' in which a molecule absorbs two photons of light simultaneously if pumped with light of sufficiently high intensity. Dyes developed at UB, exhibiting strong two-photon absorption, are blended with transparent plastics to make the data storage medium. "The presence of the dye enables the polymer to strongly absorb infrared laser light due to two-photon absorption and this absorption can be confined to a very precise area by tightly focusing the laser beam," said Bhawalkar. The infrared beam penetrates deep into the material, so data can be stored in its bulk, as opposed to only on its surface. n