With 5D optical storage, each file uses three layers of nanoscale dots. The dots' size, orientation, and position within the three standard dimensions, make up the five "dimensions." The dots change the polarization of light travelling through the disc, which is read using a microscope and polarizer.
We've seen 5D optical storage before, but there were several problems—particularly the slow writing speeds that made the technology impractical. It has huge upsides for (extremely) long-term storage, though. It's been estimated that the storage medium could withstand temperatures up to 1,000 degrees C and last 13.8 billion years at room temperature without degrading.
To overcome the speed problem, researchers used a femtosecond laser with a high repetition rate. Rather than writing directly in the glass, they used the laser to produce a phenomenon called near-field enhancement, that creates tiny structures using a few weak light pulses. Those can enhance the circular voids generated by a more powerful, single-pulse "micro-explosion." This technique "minimized the thermal damage that has been problematic for other approaches that use high-repetition-rate lasers," according to the paper.
Using the new technique, the team could write 5GB of text data onto a silica glass disc the size of a conventional CD with nearly 100 percent readout accuracy. "With the writing density available from the method, the disc could hold 500 terabytes of data," the researchers said. They could also write at speeds of a million voxels per second, or about 230 KB per second.
That might sound slow, but by introducing parallel writing, you could feasibly fill a 500TB disc in about 60 days. That could provide a way to back up reams of valuable data, essentially forever. "With the current system, we have the ability to preserve terabytes of data, which could be used, for example, to preserve information from a person’s DNA," said research team leader Peter G. Kazansky.