Volume holographic data storage at an areal density of 250 gigapixels/in.²

Abstract

One thousand volume holographic data pages, each containing 1 × 106 pixels, are stored in a common volume of LiNbO3:Fe by use of the 90° geometry. An effective transverse aperture of 1.6 mm × 1.6 mm, realized by repetition of this experiment at each of the eight surrounding locations, results in a demonstrated areal density of 394 pixels/μm2 (254 Gpixels/in.2). Short-focal-length Fourier optics provide a tightly confined object beam at the crystal; the reference beam is angle multiplexed. Data pages retrieved with a 1024 × 1024 CCD camera are processed to remap bad spatial light modulator pixels and to compensate for global and local pixel misregistration and are then decoded with a strong 8-bits-from-12-pixels modulation code. The worst-case raw bit-error rate (BER) before error correction was 1.1 × 10 3, sufficient to deliver a user BER of 10 12 at an overall code rate of 0.61 user bits per detector pixel. This result corresponds to 1.08% of the well-known theoretical volumetric density limit of 1/λ3. © 2001 Optical Society of America.