One thousand volume holographic data pages, each containing 1×106pixels , are stored in a common volume of LiNbO3 :Fe by use of the 90° geometry. An effective transverse aperture of 1.6 mm × 1.6mm , realized by repetition of this experiment at each of the eight surrounding locations, results in a demonstrated areal density of 394pixels/μm 2 (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
(210.2860) Optical data storage : Holographic and volume memories
Geoffrey W. Burr, C. Michael Jefferson, Hans Coufal, Mark Jurich, John A. Hoffnagle, Roger M. Macfarlane, and Robert M. Shelby, "Volume holographic data storage at an areal density of 250 gigapixels/in.2," Opt. Lett. 26, 444-446 (2001)