Do you remember when we used physical CD’s and DVD’s for file storage? Physical storage devices are becoming a thing of the past as we move into a cloud and flash based society. But new technologies and advancement in optical writing may suggest we go backwards – as Zongsong Gan, Yaoyu Cao, Richard Evans and Min Gu publishes a three-dimensional deep sub-diffraction optical beam lithography method allowing 1000 terabytes of storage on a regular DVD.
The use of floppy disks, CD’s and DVD’s started to become obsolete as they were limited by the physical dimensions of the hardware. When information is burned to a CD or DVD, essentially the information of the file is literally written as small dots on the optical surface of the CD/DVD. This method of writing is limited by the Abbe’s Limit, a law published by German physicist Ernst Abbe, which states that the diameter of a spot of light cannot be smaller than half of its wavelength (around 500 nanometers) for visible light. Therefore, the non-expandable physical space provided by a CD/DVD is able to contain a set and unchangeable amount of dots, often understood as the 700MB limit on CDs, or 4.7 GB on a DVD. The process is a bit more complicated than that, but that was the general constraint.
However, Cao, Evans and Gu have recently published a method to use two laser beams to produce a smaller beam. This idea can be thought of as using two circles, red and blue, then joining them in the middle, producing violet light. The DVD can be coated with a chemical to be responsive ONLY to violet light, therefore allowing “smaller” dots to be recorded on the surface on the DVD, about 1000TB.
This new technique still has to compete with our growing dependence and convenience of cloud storage as well as the loading speed of flash memory. However, this new technique is cost effective and portable, which will allow its entry into the digital storage market once again.
Submitted By: Chong S. Choi
“Give me a museum and I’ll fill it.” – Pablo Picasso (1881-1973)