Holographic Data Storage

Sadique NayeemM.Tech

Pondicherry University

The Tiger’s Speed And The The Tiger’s Speed And The Elephant's CapacityElephant's Capacity

• Very high capacities (from 200 GB disks up to many TB crystals).

• Very high data rates (from 50 MBps to many GBps).

Challenges Of Data Archiving Explosive Growth of Data

• IDC predicts 740% growth in organization data till 2010

• 50+% of data generated will NOT change (UC Berkeley study)– Medical Records – life of patient + 2 years– Brokerage records – life of account + 6 years– Archived forever –Movies, News, Scientific data, Historical data, etc.

• Analog to Digital Migration

Keeping Data Alive

• Long Media Life• Active Access to Data• Low Cost

What is holography?

• It is a technique that allows the light scattered from an object to be recorded and later reconstructed so that it appears as if the object is in the same position relative to the recording medium as it was when recorded.

• The storage of interference patter depends on absorption, refractive index and thickness of medium

• It is used to optically store, retrieve, and process information

2D Vs 3D

Volume Holography

In volume holography, we apply an object beam and a reference beam simultaneously on a photosensitive material that records the interference pattern.

Applying one of these beams to the resultant recording recreates the other.

Basic components needed

• Blue-green argon laser. • Beam splitters to spilt the laser beam.• Mirrors to direct the laser beams. • LCD panel (spatial light modulator). • Lenses to focus the laser beams.• Lithium-niobate crystal or photopolymer. • Charged-couple Device(CCD) Camera.

Practical Arrangement

Recording Data

Recording Data• To record data, light from a single laser beam is divided into two separate

beams– The signal beam which carries data.– The reference beam which serves as reference in the media.

• As the two beams cross paths in the recording medium, a hologram is formed. • Data is encoded into the signal beam by a spatial light modulator, which turns

the zeroes and ones that characterized electronic data into an optical pattern consisting of light and dark pixels. The effect looks much like a checkerboard.

• From there the data is set into an array of a million or so bits; the pixel count of the SLM ultimately determines the number of bits in the array or page.

• As the reference and signal beams intersect, the resulting chemical reaction causes a hologram to be formed and then recorded on a storage medium that is sensitive to light.

• With tweaks to the reference beam angle, wavelength, or media position, the storage medium is able to accommodate multiple holograms in a single volume.

Reading Data• The reference beam is focused on

the photosensitive material, which illuminates the appropriate inference patter, the light diffracts on the inference pattern, and projects the pattern onto a detector. The detector is capable of reading the data in parallel, over one millions bits at once. This parallel readout of data provides holography with its fast data transfer rates.

The Role of reference beam

• The readout of data depends sensitively upon the characteristics of the reference beam. By varying the reference beam, for example by changing its angle of incidence or wavelength, many different data pages can be recorded in the same volume of material and read out by applying a reference beam identical to that used during writing. This process of multiplexing data yields the enormous storage capacity of holography.

Promises

Some of the most important (in a theoretical and idealized sense) are:

• Very high storage densities (from 50 GB/in2 up to many Tb/in2) • Very high capacities (from 200 GB disks up to many TB crystals). • Very high data rates (from 50 MBps to many GBps). • Very fast page access times (from many msecs down to < 10

μsec). • Very low cost per TB (media cost/TB, for example, would be

much less than magnetic tape for most designs). • Very high reliability (assuming no moving parts and a

completely photonic implementation). • Very stable long-term storage (probably true only for certain

write-once storage media).

Why Yet Not In Market???

• With all of these exciting (potential) characteristics, one might reasonably ask why no commercial 3-D holographic data storage have ever come to market. Some of the basic reasons are listed below.

Absence of a viable storage medium

No photonic analog to magnetic media exists. The characteristics, requirements and specifications for 3-D holographic memory storage media are so complex that this component deserves a white paper in its own right. Lithium niobate, an electro-optical or “photorefractive” crystal is the best known, but has serious practical limitations.

Manufacturing cost is very high for the 3-D holographic memory drive.

Key component availability is limited

These include the laser (writing and reading device), spatial light modulator (input device), photodetector array (output device), and page addressing mechanism or subsystem.

These components do exist, but are (a) often very expensive, (b) designed and engineered mainly for laboratory use,(c) Lack of reliability characteristics suitable for commercial data

storage devices (especially, long-term archiving).

A 3-D holographic memory is a complex

• A 3-D holographic memory is a complex, analog, interferometric device. It is far more difficult to engineer and employ commercially than, for example, a near-field recording (NFR) optical disk drive, is well known to be extremely challenging. Very sophisticated servo systems will be required to compensate and control thermal variations, vibration, and shock that affect everything from laser power to storage medium alignment. The latter is especially problematic, because the positioning accuracy and precision at the reconstruction beam-stack area interface are often measured in microradians and nanometers for ultra-high density 3-D holographic memory

Holographic Timeline

• The hologram was invented by 1971 physics Nobel laureate Dr. Dennis Gabor in 1948.

• The concept of the 3-D HM was proposed by P. J. van Heerden, a research scientist at Polaroid, in 1963.

• From about 1963 through the mid-1970s, 2-D and 3-D HM were viewed as universal storage solutions. Interest in HM declined after this period because of the extremely difficult engineering challenges to systems implementation. The hologram storage medium was (and largely remains) the major item on the critical path. A few startups tried to develop either disk (notably, Tamarack Systems) or tape 3-D HM in the late 1980s, but failed.

• Finally, interest was rekindled in the early 1990s by significant improvements in key components. From about 1994 to the present, companies such as InPhase, IBM, Lucent Bell Labs and SIROS (Optitek) began serious attempts to commercialize 3-DHM.

• Some research continues in Japanese companies, for example, Hitachi, NHK, Pioneer, and Sony

In Next Presentation.• Laser– Blue-green argon laser. – Beam splitters to spilt the laser beam.

• Spatial light modulator (SLM).• Storage Media– Lithium-niobate crystal (LiNbO3:Fe crystal)– Photopolymer.

• Charged-couple Device(CCD) Camera.

• The curious case of “InPhase”

Conclusion

• Considering all positive and negative aspects ,it is now almost certain that the holographic storage technology will be the winner among the competing ones. This will be the opening of a new era in data storage and data processing .Applications requiring and using unusually high storage capacities will revolutionize content distribution, mobile computing and global information security. Possibilities include more efficient querying ultra dense databases, new kinds of displays, and ultrafast processors carved into holographic material. However, the technology still needs a few more years to offer common-place affordable products.

References(Journals)• Benjamin Alfonsi, “Holographic Storage Ready for Market," IEEE Distributed Systems

Online, vol. 6, no. 10,2005.• Bonsor, Kevin. "How Holographic Memory Will Work." 08 November 2000. • Mehmet C. Okur , “A CRITICAL EVALUATION OF NEWLY EMERGING HOLOGRAPHIC

DATA STORAGE “Journal Of Yasar University July2006 No3@volume 1• Dr. Richard G. Zech , “Holographic Memory Introduction & Tutorial”• M. LANG, H. ESCHLER, “Gigabyte capacities for holographic memories” published by

Elsevier Science Ltd.• LAMBERTUS HESSELINK, SERGEI S. ORLOV, AND MATTHEW C. BASHAW, “Holographic

Data Storage Systems”, PROCEEDINGS OF THE IEEE, VOL. 92, NO. 8, AUGUST 2004• N. N. VYUKHINA, I. S. GIBIN, V. A. DOMBROVSKY, S. A. DOMBROVSKY, “A review of

aspects the improvement of memory technology relating to Holographic” Optics & Laser Technology, Vol. 28, No. 4, pp. 269-276, 1996. published by Elsevier Science Ltd

• Demetri Psaltis, California Institute of Technology, Geoffrey W. Burr IBM Almaden Research Center, “Holographic Data Storage”, 1998 IEEE

References(Websites)• http://computer.howstuffworks.com• http://en.wikipedia.org/wiki/Holographic_data_storage• http://www.bell-labs.com/org/physicalsciences/projects/hdhds• http://www.youtube.com/watch?v=HlRsh0kUiUg&feature=related

Thank You…

Is still on !!!