Quartz disc can store information for a million years

^{(a) The information recording setup consists of a femtosecond laser, a spatial light modulator (SLM), Fourier lenses (FL), a half-wave phase plate (λ / 2 M), a dichromatic mirror, an 1.2 NA immersion objective lens, a sample of quartz glass and a platform . (b) Matrix color codes from a half-wave phase plate imprinted in quartz glass to control polarization.}

Scientists from the University of Southampton for the first time in the world managed to successfully record and read information from a five-dimensional carrier (5D) in quartz glass.
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By virtue of its strength and chemical inertness, quartz glass is a unique information carrier. A quartz glass disk can potentially hold up to 360 terabytes of information, while maintaining temperatures up to 1000 ° C and has a virtually unlimited shelf life.

In fused silica memory crystals, information is recorded in five dimensions: coordinates in 3D space, orientation, and size. The last two parameters are controlled by polarization and the intensity of the laser beam.

During the experiment, a 300-kilobyte text file was successfully written to the crystal. The file was recorded using a femtosecond laser with a wavelength of 1030 nm, pulses of 8 microjoules with a duration of 280 femtoseconds with a frequency of 200 kHz, using burning points in the crystal, layers at a distance of 5 μm from each other (1 micrometer - one million-meter) at a depth of 140 um from the surface of quartz glass.


^{Recorded data in three layers, approximation 60x}

To demonstrate the technology, the recording was made in two different ways: 1 bit at a point, in the illustration - (b) on the right, and 4 bits at a point, in illustration (b) on the left.

The use of a spatial light modulator and a half-wave phase plate allows one to get rid of moving components in a recording setup.

Burnt points change the optical characteristics of the crystal and the polarization of the light passing through it, which can be detected with an optical microscope and polarizer. It is this combination of devices used to read information. During the experiment, an Olympus BX51 optical microscope with a birefringence measurement system was used.


^{Quartz disc with recorded information}

A slow but durable new type of memory can be used to back up information. Especially in companies that are able to buy a femtosecond laser for $ 100 thousand.

The research paper “5D Data Storage by Ultrafast Laser Nanostructuring in Glass” (pdf) was presented at a conference on lasers and optoelectronics (CLEO'13) in San José.