Optical memory - from nanolaser to 1 Tbit / inch2

Researchers in the United States have just succeeded in creating a nanolaser device that converges a beam of light with a power of 200 nW into a small spot less than 35 nm in diameter. These results mean that optical memory with a storage density of 1 Tbit / inch2 has become a reality. (Detailed results of this study can be found in the published work in Appl. Phys. Lett. 91 153115 ).

" Moreover, our nanolaser technology can reduce the size of the converging spotlight to as small as 10 nm, " said team leader Sakhrat Khizroev of the University of California, Riverside. "This experiment can create a great compact for the industry to store information by magnetic memory and can especially be called magnetic recording technology with heat-assisted magnetic recording (HAMR). ), one of the promising information storage techniques in the future ".

Khizroev added: The information storage industry is currently in the race to find solutions to replace traditional recording technology that we still know is the longitudinal magnetic recording - technique Since the magnetic dimension of the magnetic moments in each word bit is in the plane of the magnetic media, it has been used almost 5 decades since it was first introduced. This technique will gradually reach the supercritical limit as the size of the word bits decreases and the stability of the stored information will be greatly reduced.

Figure 1. Apertures with different shapes are generated by convergent ion beam technique
(Photo: SEM - Appl. Phys. Lett. 91 153115).

The HAMR technique uses light beams oriented simultaneously with the magnetic field to produce a sufficiently large energy that can reverse the vector from the degree of a bit from the nanoscale in a magnetic media with an magnetic anisotropy. However, a stumbling block to realize HAMR's ability is the difficulty of conveying a sufficiently large energy into a point of very small size (nanometer size). And the new technique solves this when it creates a mechanism that allows focusing beams of energy up to 200 nW into a point of only 35 nm in size, more than enough to reverse the bit from nanometer size.

The team created nanolaser by depositing a thin film of metal into the luminescent edge of a laser diode. And then use convergent ion beam technique (using high-energy ion beams and focus on small points) to erode and destroy details that create a nanometer-sized aperture. And when light passes through this aperture, it will focus on a small point. After experimenting with various shapes of aperture, the team discovered that the C-shaped aperture allows the highest amount of light to pass through.

Khizroev said that the technology could quickly become a commercial product in just two years, of course, depending on how optical companies are interested in cooperating. This technology also allows for the creation of another type of data recording called " protein-based memory". The type of memory and type of storage can only be marketed in the next 10 years, according to Khizroev's prediction. The team also includes researchers from the University of Houston, Texas, who are currently working on research collaborations with potential research groups and high-tech companies to develop the technology. real trade.

Figure 2. The ability to converge different light of the apture,
aperture is C-shaped for best convergence (Appl. Phys. Lett. 91 153115).

"This work of course only makes sense when HAMR is produced into a product," commented Kevin Grady ( York University , UK). "However, one problem is the cost - whether you can create a drive with a price of $ 100 when you have a hard time making such a nanolaser, this is hard to imagine. Anyway. The work is still extremely important for creating small lasers for many other applications, not just HAMR " - Kevin Grady added.

Rabee Ikkawi fellows at the console of the experimental system

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According to Nanotechweb.org & American Institute of Physics, Vietnam Physics