Holographic Data Storage
Holographic data storage is a technology that allows holograms containing millions of bits of data to be written or read in a single flash of light. Thousands of overlapping holograms can be stored in a common volume of recording medium.
Holography breaks through the density limits of conventional 2D storage by recording throughout the full depth of a 3D medium. Holography can write and read millions of bits of data in parallel, enabling significantly higher data transfer rates than current optical storage devices. Holography combines high storage densities and fast transfer rates with a durable low-cost storage medium, making it a compelling choice for next-generation storage and content distribution needs.
Light from a laser is split into two beams: the signal beam (which carries the data) and the reference beam. A hologram is formed where these two beams intersect in the recording medium. Data are encoded onto the signal beam using a device called a spatial light modulator (SLM). The SLM translates the electronic 0’s and 1’s into an optical “checkerboard” pattern of light and dark pixels. The data are arranged in an array, or page, of several million pixels.
A hologram is formed in the light-sensitive storage medium at the point where the reference beam and the signal beam intersect. Chemical reactions occur causing the light distribution to be recorded as a permanent polymerization pattern. By varying the reference beam angle and medium position, thousands of independent holograms can be co-located in the same volume of material.
Data recovery is accomplished by illuminating a hologram with a copy of the reference beam used to record it. The desired hologram selectively diffracts the reference beam, whereas the thousands of co-located holograms do not. The diffraction creates a copy of the signal beam which is then imaged onto a detector pixel array and decoded electronically. Millions of bits are thus recovered in parallel, providing holography with its extraordinarily fast data transfer rates.