High-density Holographic Data Storage with …10MSST-2002, April 15-18 1 Irvine, California MetroLaser High-density Holographic Data Storage with Random Encoded Reference Beam Vladimir

10MSST-2002, April 15-18 1Irvine, CaliforniaMetroLaser

HighHigh--density Holographic density Holographic Data Storage with Random Data Storage with Random Encoded Reference BeamEncoded Reference Beam

Vladimir B. MarkovMetroLaser, Inc.

18010 Skypark Circle, Irvine, CA [email protected]


Outline

• Motivation• Outline of Theory• System Design• Results from a Shift Selectivity• Conclusions


Motivation

Holographic memory offers:

• bit storage density of the order of 1012/cm3

• parallel access and parallel data processing

• high retrieval rate

• solid-state configuration


PrinciplesPrinciples

• Selective properties of volume hologram• Volume holograms with amplitude-phase

modulated reference beam and theirselective properties

• Solid-state configuration with randomreference beam

• Selective properties of volume hologram• Volume holograms with amplitude-phase

modulated reference beam and theirselective properties

• Solid-state configuration with randomreference beam


Angular Bragg SelectivityAngular Bragg Selectivity

Non-Dispersion Plane Selectivity

y

x

VolumeGrating

oRθ

ϕ

1e-005

0.0001

0.001

0.01

0.1

1

Dif

frac

tion

effi

cien

cy

-8 -4 0 4 8Angular Dev. (a.u.)

Dispersion PlaneSelectivity


ØReference Beam RandomAmplitude-Phase Encoding:

ünew type of Spatial & Angular(isotropic) selectivity;üsolid-state architecture - no moving partsü secure data access

ØReference Beam RandomAmplitude-Phase Encoding:

ünew type of Spatial & Angular(isotropic) selectivity;üsolid-state architecture - no moving partsü secure data access

ØAngular and Spectral Braggselectivity results in:ünon-isotropic diffraction at off-Bragg tuning üincremental noiseüinsecure data accessürequire moving parts.

ØAngular and Spectral Braggselectivity results in:ünon-isotropic diffraction at off-Bragg tuning üincremental noiseüinsecure data accessürequire moving parts.

Angular-spectral selectivity ofvolume hologram and random encodingof reference beam are used as basic mechanisms for data multiplexing


Random APM volume hologram - RecordingRandom APM volume Random APM volume hologram hologram -- RecordingRecording

y

x

zT

∆⊥xRo(r)

<σ⊥> = 1.22 λD/dL

K SSo(r)

S(r)

Initial position of speckle


y

x

zT

Initial position of speckle

Ro(r)

<σ⊥> = 1.22 λD/dL

K S

S(r)

Random APM volume hologram - Reconstruction

Random APM volume Random APM volume hologram hologram -- ReconstructionReconstruction


Shiftdirection

y

∆⊥y

x

zT

∆⊥

Displaced speckleposition

Initial speckleposition

∆⊥xRo(r)

<σ⊥> = 1.22 λD/dL

S

S(r)

K

Random APM volume hologram - Reconstruction

Random APM volume Random APM volume hologram hologram -- ReconstructionReconstruction


Basic results of the Basic results of the analysisanalysis

Where Ro(q,z)R*(q,z) is spatial correlation function of a random amplitude-phase modulated (speckle) field:Where RWhere Roo(q,z)R(q,z)R*(q,z) *(q,z) is spatial correlation function of is spatial correlation function of a random amplitudea random amplitude--phase modulated (speckle) field:phase modulated (speckle) field:

∫ ∫∞+

∞−⊥

⊥⊥⊥

∆−×

∆=∆ ,qdq

znik

exp)q(Pz2nik

exp)'z,(C 2

eff

o2L

eff

2o rrr

rr

The diffracted field amplitude:The diffracted field amplitude:The diffracted field amplitude:

∫∫ ∫=S

T

oso dqdzzqRzqRikzqS ')',()',(]sinexp[)',( * rrr

0θ


Mirror

Computer/Data Base

Controller

yx

z

TranslationStage

Iris

PolarizingFilter

NDFilter

Lens

PhotoDetector

CMOS

Modulator CondenserLensPre-modulator

BeamSplitter

Shutter1

Shutter2

SLM ImagingLens1

ImagingLens2

SpatialFilter

Lens

Experimental Setup for Random APE Holographic Memory


Laboratory setup for Laboratory setup for APM hologram APM hologram


SPECKLE SHIFT SPECKLE SHIFT SELECTIVITYSELECTIVITY

0.0 4.0 8.0 12.0 16.0 20.0X-SHIFT (µm)

0.00

0.20

0.40

0.60

0.80

1.00In

ten

sity

IN

D

<ε⊥> ~ 12.0 µm<ε⊥> ~ 8.0 µm<ε⊥> ~ 6.0 µm

XX--SHIFT SELECTIVITYSHIFT SELECTIVITY(experiment)(experiment)

<ε⊥> - average speckle size


X-Y Speckle-Shift SelectivitySpeckle-Shift Selectivity is perfectly symmetric in both X and Y directions and the retrieved signal intensity decreases with ∆⊥ in almost 3 orders of the magnitude with no side-lobes. This promises low cross-talk and a high level of security.

TheoryTheory

0.00 1.00 2.00 3.00 4.00SHIFT ∆⊥x,y(µm)

0.001

0.010

0.100

1.000

DIF

FRA

CTE

D B

EA

M I

NTE

NSI

TY I ∆

⊥(a

.u.)

∆⊥X

∆⊥Y

ExperimentExperiment


Image Characteristics@ Spatial Shift

Spatial Shift doesn’t introduce any side effects on the reconstructed image quality beside the intensity decrease. The phase distribution remains invariable with ∆⊥

∆⊥ = − 0.5 µm

∆⊥ = 0.0 µm

∆⊥ = 0.5 µm

∆⊥ = 1.5 µm


0.00 5.00 10.00 15.00 20.00 25.00

Shift ∆⊥(µm)

0.00

0.20

0.40

0.60

0.80

1.00

Nor

mal

ized

Inte

nsity

I DRecordingmedium

Recordingmedium

OpticsOptics

Random APMRandom APM

Pre-encoderPre-encoder

DetectorDetector

Realization of Solid-StateData Storage ConfigurationRealization of SolidRealization of Solid--StateState

Data Storage ConfigurationData Storage Configuration

Principal setupPrincipal setup


Solid-State technique validation

Solid-State technique validation

0 0.2 0.4 0.6 0.8 1

Relative shif t ∆⊥/<σ⊥>

0

0.2

0.4

0.6

0.8

1

Inte

nsity

I NDDecorrelation with:

• Pre-encoder spatial variation(shift or rotation)

• Reference beam spatial steering• Beam angular steering with deflector

• Encoder (or pre-encoder)rotation

Decorrelation with:

• Pre-encoder spatial variation(shift or rotation)

• Reference beam spatial steering• Beam angular steering with deflector

• Encoder (or pre-encoder)rotation


Page encoding and data recallPage encoding and data recall

Recording

Reconstruction


Data Recall SequenceData Recall Sequence


Holographic Memory Module architecture with solid-state

configuration

APE-SLM

RecordingMedium

Data-SLM

Receiver

Laser

MemoryErasure

Anticipated HMMparameters:

¬Capacity - 1011 b¬Trans. rate - 1 Gb/sec¬Size - < 0.4 ft3

¬Weight - <1.5 kg¬Power cons.- < 50 W

Anticipated HMMparameters:

¬Capacity - 1011 b¬Trans. rate - 1 Gb/sec¬Size - < 0.4 ft3

¬Weight - <1.5 kg¬Power cons.- < 50 W


Conclusion

• High- density holographic data storage is demonstrated with random encoded reference beam

• Parallel recording and retrieval• Optical memory in solid-state configuring

Acknowledgment This work was supported in part through the SBIR projects with NASA and DOE

• High- density holographic data storage is demonstrated with random encoded reference beam

• Parallel recording and retrieval• Optical memory in solid-state configuring

Acknowledgment This work was supported in part through the SBIR projects with NASA and DOE

High-density Holographic Data Storage with …10MSST-2002, April 15-18 1 Irvine, California MetroLaser High-density Holographic Data Storage with Random Encoded Reference Beam Vladimir

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