Tech UPTechnologyAn almost indestructible CD

An almost indestructible CD

On this day, November 8, 1877, the German-American inventor Emile Berliner patented the gramophone. Berliner introduced important improvements with respect to Edison’s phonograph and one of these was that a flat register was used for the first time, not cylindrical as in the case of the aforementioned phonograph. One hundred and forty-four years later, we are on the verge of achieving an album that could fit more than 100 million songs to listen to for a whole millennium. And all in half the size of the first singles that could fit one or two songs.

The most nostalgic lovers of music, movies or data from the 90s are in luck. A group of seven researchers from the University of Southampton (UK) have devised a potential method to achieve fast writing to storage disks that could hold up to 500 TB. The compact disc (CD) of a lifetime, but reinvented. Those people who recorded complete discographies of their favorite singer in compressed format, used a CD with a capacity of 700 MB. It means that this new album would be worth about 700,000 of those CD’s that gave so many joys. The truth is that the CD was having improvements in the medium and the way of recording. In 1996 DVDs (digital versatile disc) were released, with a capacity of 4.7 GB, which made data addicts kings of the mambo. If we do the calculation, we get that the proposed disc would have a capacity equivalent to ten thousand of those DVD’s where complete television series could already be hosted. The year 2002 brought us the Blu-ray, to enjoy high definition movies. The Southampton Magnificent Seven bring us an option with a density ten thousand times higher than Blu-ray discs.

The team, led by Yuhao Lei, proposes a method to greatly improve typing speed. In the cases mentioned above (CD, DVD and Blu-ray) we are talking about laser reading and writing. The problem is not so much the capacity but the time to record the data. Gutenberg’s press was a quantum leap in data recording. Although there were previous attempts, it would be in the 15th century when Gutenberg left the copyists unemployed. Perhaps we are on the eve of a similar event, with this five-dimensional (5D) optical data storage technique, based on high-density anisotropic nanostructures in silica glass. The name of this type of storage is due to the fact that there are two optical dimensions (polarization and intensity of the laser pulse) plus three spatial ones used to record the data. A technology that also avoids thermal damage caused in previous optical discs, since the point of incidence of the laser is smaller. Although it is not an indestructible album due to the passage of time, it would exceed the owner’s requirement.


According to the authors of the article, the big drawbacks of hard drives are their high energy consumption and their short lifespan. They propose optical reading and writing as a solution, but not the one we had until now, since CDs and DVDs have a low capacity and a useful life of a decade.

The great advances that have occurred in the use of femtosencond lasers open a way to solve both problems. These types of lasers base their operation at the quantum level, using very short pulses, of femtoseconds (1 fs = 0.000 000 000 000 001 s), which significantly reduces the space required to store information while considerably increasing speed. writing and reading. The Southampton researchers’ research team managed to write 5 GB in 50 layers, which shows a speed of 106 voxel / s, or about 225 kB / s. This means that you could copy more than 100 pages per second, that is, Joyce’s Ulises in less than ten seconds or copy the 5 million pages of the National Library of Spain in about 14 hours. However, to record an entire album it would take at least a couple of months. The next steps will be to further increase the veolicity. The aim is to reach the order of MB / s and for this, one of the keys in which the proposal is supported are the birefringent properties of the nanoholes where the data are written. Birefringence is an optical property that consists of the ability of certain materials to unfold a ray of light into two polarized rays. The Icelandic spar is the best known and can be easily found in different virtual stores. It could even be the mythical stone that the Vikings used to navigate, as a study among researchers from various universities suggests.

When Edison invented the phonograph in 1870, he could not even imagine that in less than ten years he would already be being displaced by a cheaper and more efficient recording system. The fight to find faster recording and writing, lower energy consumption and more capacity had begun. Long before the optical age with the release of the laserdisc, the predecessor of the CD, and everything that followed. Perhaps you have never heard of the laserdisc, nor have you ever read anything about the phonoautograph. It is a device that would be the forerunner of phonographs and gramophones, patented by French Édouard-Léon Scott de Martinville on March 25, 1857. The ending “graph” refers to the fact that this device was capable of “drawing” sound. on a line of soot that impregnated a cylinder. The downside is that the system did not allow for later playback. However, in 2008 a group of scientists from the Lawrence Berkeley National Laboratory of the University of Berkeley (California) managed to reproduce the first sound record in history. Ten seconds of the popular French song Au clair de la lune , more than a decade before Edison.

Yuhao Lei, Masaaki Sakakura, Lei Wang, Yanhao Yu, Huijun Wang, Gholamreza Shayeganrad, and Peter G. Kazansky, “High speed ultrafast laser anisotropic nanostructuring by energy deposition control via near-field enhancement,” Optica, 8, 1365-1371 (2021).



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