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11 Dec 2007
US researchers have made a nanolaser that could enable data to be stored with a density of 10 Tbit per square inch.
The nanolaser can focus light with a power of over 200 nW into a spot just 35 nm across. The result suggests that data storage beyond 10 Tbit per square inch could be possible at last. "Furthermore, our nanolaser technology could be scaled down to a spot size as small as 10 nm," team leader Sakhrat Khizroev of the University of California at Riverside told nanotechweb.org. "This experiment could have a great impact on the magnetic data storage industry and especially enable so-called heat-assisted magnetic recording (HAMR) – one of the most promising data storage technologies of the future."
The data storage industry is now looking for alternatives to its conventional recording technology, known as longitudinal magnetic recording, for the first time since it was introduced over five decades ago. This is because the technology will one day reach the fundamental, superparamagnetic limit – beyond which the magnetic bits in conventional recording media become so small that the stored information is unstable.
HAMR uses co-aligned beams of light and magnetic fields to produce enough energy to switch the magnetization of a nanoscale bit in a highly anisotropic magnetic recording medium. However, the main stumbling block to enabling HAMR is the difficulty in delivering an adequate amount of power into a nanoscale spot size. The new technique has overcome this problem because it is capable of delivering more than 200 nW of power into a spot size with a diameter of 35 nm, which is more than enough to switch nanoscale bits.
C-shaped aperture
The researchers made their nanolaser by depositing a thin layer of metal on the emitting edge of a diode laser. They then used a focused beam of gallium ions to etch a nanosized aperture. When light propagates through such an aperture, it focuses onto a nanoscale spot. After experiments with a variety of different-shaped apertures, the team found that a C-shaped aperture let the highest amount of light through.
Khizroev says that the technology could be on the market in as little as two years, depending on how the collaboration with optical companies goes.
The technology might also allow another type of data recording, called protein-based memory. This type of information storage and memory could hit the market within the next ten years, predicts Khizroev.
The team, which includes researchers from the University of Houston, Texas, is now looking at establishing partnerships with high-tech companies to develop a real product based on its technology.
"This work certainly is significant if HAMR is ever to be made into a product," said Kevin Grady of the University of York in the UK. "However, one problem is the cost – how you would make a disk drive for $100 when you had to produce a nanolaser is hard to imagine. Nonetheless, the work is important for making small lasers for other applications as well as HAMR," he added.
The results were reported in Applied Physics Letters.
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