It may be possible to improve the storage of information in our computers through an ingenious device for transferring light energy in a mechanical system. A team of researchers at Yale University, USA, has developed a device to “write” and “read” the information with the laser light. The results of this work, published in Nature Nanotechnology, could reduce the energy consumption of hard drives while making them very reliable.

When we talk about memory and information storage hard drives, the parameters determining the value of new technology are mainly: the stability of stored information, and energy storage density. Many studies seek to develop new devices competitive on these three parameters. The devices developed characters generally have in common. They have the two most stable configurations for encoding information through “0″ or “1″ (binary system). The stability depends of the energy needed to switch the device from one position to another. To be stable, this energy so-called “barrier” should be well above the energy of “noise” so that “noise” can not, by itself, change the information. The device must also have a power source allowing it to switch from one position to another with an error rate of almost zero.

Writing

In the case of the system developed at Yale University, the device uses small silicon rods 10 microns long, 500 nm wide and 110 nanometers thick. The rods are placed on an optical cavity using sounding bright. These optical cavities allow the capture and amplification of light rays between two mirrors placed face to face and reflecting the rays on numerous occasions. The silicon rod is slightly flexible. Thus, when designing the device, the silicon rod is compressed at both ends and bends slightly either up or down. With these two positions, called “up” and “down”, it is possible to encode information in binary, one of the positions corresponding to a bit “0″ and the other to a “1″.

In this scenario, write equivalent information to control the bending of successive stalks to encode information in a series of 0 and 1. For this, the Yale team uses lasers. They managed to induce a transfer of energy from the laser light into the silicon rod. If the energy injected is enough to shake the stability of silicon rods, a change in their curvature is possible. As a result of the first laser rod receives an amount of energy that makes the “vibrate”. The laser is then switched off and the stem could then be stabilized in one or the other positions without preference. Scientists then use a second laser says “cooling” to control the position in which the rod will stabilize. Its wavelength is carefully chosen to “guide” the position of stabilization. This wavelength creates an asymmetry in the movement of the rod which influences its position stabilization in a desired position.

Reading

For “Read” information and coded, it is necessary to distinguish the two different curvatures of the silicon rods. When the stem of a concave position switches “up” to a convex position “down”, the refractive index (proportional to the speed of light in a medium) is changed. The light is more or less slowed down through the silicon rod of its curvature. It is therefore possible to “read” optically the curvature of the rod by measuring the speed of light as it passes through it.

The team of researchers from Yale repeated thousands of times the writing and reading information on these silicon rods with laser light. They thus demonstrated that their system was very stable at room temperature and its error rate was zero reading.

In conclusion, the mechanical memory devices like this are, for now, the memory elements the most stable. The writing and reading information using lasers is an inexpensive energy. The density of data storage will be against by not particularly enhanced by this new technology. Indeed, stability and storage density are rarely compatible.

It could be that this new device may one day improve the capacity of computer hard drives. But what is most impressive at the moment is the mastery of mechanical elements (silicon rods) with laser via energy transfer. The light-matter interactions are indeed a largely unexplored area that is now technical applications as well as medical (opt genetics).