3D bit-oriented optical storage in photopolymers

Results from the investigation of the diffusion processes in a dry acrylamide-based photopolymer system are presented. The investigation is carried out in the context of experimental work on optimization of the high spatial frequency response of the photopolymer. Tracing the transmission holographic grating dynamics at short times of exposure is utilized to measure diffusion coefficients. The results reveal that two different diffusion processes contribute with opposite sign to the refractive index modulation responsible for the diffraction grating build up.Monomer diffusion from dark to bright fringe areas increases the refractive index modulation. It is characterized with diffusion constant D 0 =1.6.10 -7 cm 2 /s. A second diffusion process takes place during the recording. It decreases the refractive index modulation and we ascribe it to diffusion of short chain polymer molecules and/or radicals from bright to dark fringe areas. The estimated diffusion coefficient for this process is D 0 = 6.35.10 -10 cm 2 /s. The presence of the second process could be responsible for poor high spatial frequency response of the investigated photopolymer 2 system. Comparison with the diffusion in photopolymer systems known for their good response at high spatial frequencies shows that both investigated diffusion processes measured here occur in a much faster time scale.

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“…We ensure that the exposure is 6 small enough so that we can assume the diffusion coefficient is not spatially modulated.…”

Section: Measurement Of Monomer Diffusion Coefficientmentioning

confidence: 99%

“…, real-time interferometry 3,4 and write once optical memories [5][6][7] . The acrylamide -based photopolymer developed in our group 2,8 has excellent characteristics for transmission holograms recording.…”

mentioning

confidence: 99%

Investigation of the diffusion processes in a self-processing acrylamide-based photopolymer system

Naydenova¹,

Jallapuram²,

Howard³

et al. 2004

Appl. Opt.

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“…To satisfy this requirement, the optical system is required to short wavelength and high numerical aperture (NA) lenses. The micrograting created in a photopolymer is commonly analyzed by two counter-propagating beams using scalar diffraction theory [1,7,8]. However, the scalar diffraction theory is not considered polarization illumination and transmission and reflection of the propagating beam.…”

Section: Introductionmentioning

confidence: 99%

“…In Figure 1b, the reading of the recorded micrograting is carried out by the reflection of reference beam. Using this micrograting configuration, we assume that the signal and reference beams have the same amplitude and waist, i.e., and [7]. To calculate the electric field in the photopolymer, we introduce vector diffraction theory which accounts for polarization illumination and the boundary conditions of multi-layer system such as lens-air-photopolymer configuration [12].Vector diffraction theory approaches the limits of the validity of scalar theory used to describe the illumination; additionally, this theory provides an exact solution when the NA exceeds 0.6 [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Diffraction Focal Position and Vector Diffraction Theory for Micro Holographic Storage Systems

et al. 2014

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Abstract:In this study, we proposed a method to determine the optimal focal position for micro-holographic storage systems, using vector diffraction theory; the theory provides exact solutions when the numerical aperture (NA) exceeds 0.6. The best diffraction focus was determined by the position and wavelength corresponding to minimal spherical aberration. The calculated refractive index modulation, polarization illumination, and boundary conditions at the interface of different media were analyzed. From the results of our analysis, we could confirm the size of micrograting as a function of NA and wavelength, based on vector diffraction theory, compared with scalar diffraction theory which defines the micrograting by . To demonstrate our analysis, we adapted an optical alignment method using a Twyman-Green interferometer, and could obtain good agreement between analysis and experimental results.

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“…[5][6][7][8][9] Bit-oriented holographic storage is commonly achieved in a counterpropagating geometry by focusing an incident beam on a sensitive medium, where it interferes with its counterpropagating reflection issued from a mirror placed on the other side of the disk. [5][6][7][8] During readout, the reflection on the mirror is prevented and a Bragg reflection at a given wavelength and location indicates that the corresponding bit is in the "1" state.…”

mentioning

confidence: 99%

Homodyne detection readout for bit-oriented holographic memories

2006

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Homodyne detection is proposed to increase the readout signal of bit-oriented holographic memories. It can be easily implemented on present memory architectures by making the diffracted signal interfere with a reflection of the reading beam. The large resulting increase of the readout signal can be used to enhance the data transfer rate. A first experimental demonstration of such a readout procedure is presented.

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3D bit-oriented optical storage in photopolymers

Cited by 61 publications

References 6 publications

Investigation of the diffusion processes in a self-processing acrylamide-based photopolymer system

Investigation of the diffusion processes in a self-processing acrylamide-based photopolymer system

Diffraction Focal Position and Vector Diffraction Theory for Micro Holographic Storage Systems

Homodyne detection readout for bit-oriented holographic memories

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