Holographic storage of multiple high-capacity digital data pages in thick photopolymer systems

Abstract

Multiple digital data pages (480 kbits per page) were holographically recorded and retrieved with low bit-error rates in thick (~250- and ~500-mum) photopolymer media. The photopolymer systems were fabricated with the optical quality and low level of scatter required for digital data storage. We believe that these results represent the first demonstration of holographic storage of high-capacity digital data pages in photopolymer media with the thickness that will be required for such storage densities.

Hybrid Ternary Modulation Applied to Multiplexing Holograms in Photopolymers for Data Page Storage

“…In addition, they were stored with a beam ratio of 100 and reconstructed on the CCD with a reading beam intensity of 0.03mW/cm 2 [24]. As the holograms are stored in the material, the dynamic range is consumed [21][22][23]25]; therefore, the exposure must be increased in order to store more holograms. Of course, when all the dynamic range is consumed, no more holograms will be formed in the material even if the exposure is increased.…”

“…In order to evaluate the image quality, its histogram was used to calculate the bit error rate (BER) [21][22][23] and determine the contrast between the pixels. BER values of each image were calculated to decide which parameters provide the best image quality (greater contrast and less noise).…”

The Approximate Model for Holographic Grating Formation in Photopolymers

“…Optical Society of America Photopolymer materials are of significant interest in the area of holographic data storage [1], particularly for W.O.R.M. storage applications.…”

“…Using Eq [1], the first harmonic of polymer concentration, N 1 (ξ), is determined, where ξ is related to exposure energy. A third order Taylor series expansion of N 1 (ξ), assuming ξ<<1, about ξ = 0 is taken.…”

Holographic data storage: optimized scheduling using the nonlocal polymerization-driven diffusion model

“…1,2 They therefore possess major advantages in the race to be the medium of choice for both write-once read-many holographic data storage [3][4][5][6] and for the fabrication of bulk and micro holographic optical elements. [7][8][9] When using a photopolymer as a holographic data storage medium, one wishes to choose a recording (exposure) schedule that optimizes the total polymer generated as a direct result of the recording process and at the same time produces M gratings of maximum and ideally equal strength (refractive-index modulation size).…”