Quartz disk can store information for a million years

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

For the first time in the world, scientists from the University of Southampton were able to successfully record and read information from a five-dimensional medium (5D) in quartz glass.

Due to 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 withstanding temperatures up to 1000 ° C and has an almost unlimited shelf life.

In the “memory crystals” of fused quartz, information is recorded in five dimensions: coordinates in 3D space, orientation and size. The last two parameters are controlled by the polarization and 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, by burning points in the crystal, layers at a distance of 5 μm from each other (1 micrometer - one millionth meter) at a depth of 140 microns from the surface of quartz glass.


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

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

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


^{Quartz disk with recorded information A}

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

scientific work “5D Data Storage by Ultrafast Laser Nanostructuring in Glass” (pdf) was presented at the conference on lasers and optoelectronics (CLEO'13) in San Jose.