Materials for 3D optical storage:

1
Materials for 3D optical storage two-photon
access vs. one-photon background
N.S. Makarov, A. Rebane, M. Drobizhev (Department
of Physics, Montana State University, Bozeman, MT
59717, USA) H. Wolleb, H. Spahni (Ciba Specialty
Chemicals Inc, P.O. Box Ch-4002 Basle,
Switzerland)
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Outline

• Principles of 3D 2PA optical memory
• Lack of 2PA-sensitive photochromes
• 2PA resonance enhancement
• 2PA vs. 1PA
• 2PA-sensitive phtalocyanines
• Summary
• References

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Principles of 3D 2PA optical memory
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Lack of 2PA-sensitive photochromes
Access with 1 pulse 100fs, 100MHz gt 1TB
read/write in 22.2 hrs Each bit have to be
written and read by only 1 femtosecond pulse!
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2PA resonance enhancement
A fundamental trade-off between 2PA and 1PA may
be formulated as follows On the one hand, one
would like to tune laser frequency as close as
possible to the resonance in order to increase
useful signal, but on the other hand, one would
like to tune as far as possible to decrease
detrimental background.
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2PA vs. 1PA
850-900 nm
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2PA-sensitive phtalocyanines
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Summary

• Because of the requirement of fast speed writing
  and readout, the storage materials need to have
  high molecular 2PA cross section, ?2gt103-104 GM
• It is evident that the crucial points in this
  approach are the two-photon sensitivity of a
  molecule and the possibility of its photochemical
  transformation from one form to another
• Careful choice of excitation frequency, along
  with suitable combination of 1PA and 2PA
  properties allow minimizing the negative impact
  of underlying near resonance hot band absorption
• Our model allows to predict the appropriateness
  of chromophores for the 2PA-based optical storage

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References

• D.A. Parthenopoulos, P.M. Rentzepis,
  Three-Dimensional Optical Storage Memory,
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• M. Drobizhev, A. Karotki, M. Kruk, A. Rebane,
  Resonance enhancement of two-photon absorption
  in porphyrins, Chem. Phys. Lett., 355, 175-182,
  (2002).
• M. Drobizhev, Y. Stepanenko, Y. Dzenis, A.
  Karotki, A. Rebane, P.N. Taylor, H.L. Anderson,
  Understanding Strong Two-Photon Absorption in
  -Conjugated Porphyrin Dimers via Double-Resonance
  Enhancement in a Three-Level Model, J. Am. Chem.
  Soc., 126, 15352-15353 (2004).
• M. Drobizhev, F. Meng, A. Rebane, Y. Stepanenko,
  E. Nickel, C.W. Spangler, Strong two-photon
  absorption in new asymmetrically substituted
  porphyrins interference between charge-transfer
  and intermediate-resonance pathways, J. Phys.
  Chem. B, 110, 9802-9814 (2006).
• M. Drobizhev, Y. Stepanenko, Y. Dzenis, A.
  Karotki, A. Rebane, P.N. Taylor, H.L. Anderson,
  Extremely strong near-IR two-photon absorption
  in conjugated porphyrin dimmers quantitative
  description with three-essential-states model,
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• M. Drobizhev, A. Karotki, M. Kruk, N. Zh.
  Mamardashvili, A. Rebane, Drastic enhancement of
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  with symmetrical electron-accepting
  substitution, Chem. Phys. Lett., 361, 504-512
  (2002).
• I. Renge, H. Wolleb, H. Spahni, U.P. Wild,
  Phthalonaphthalocyanines New Far-Red Dyes for
  Spectral Hole Burning, J. Phys. Chem. A 101,
  6202-6213, (1997).
• A.A. Gorokhovskii, R.K. Kaarli, L.A. Rebane,
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• M. Drobizhev, A. Karotkii, A. Rebane, Dendrimer
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  in tetraazachlorin and its benzo-and
  2,3-naphtho-fused derivatives Effective symmetry
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  Conference on Porphyrines and Phtalocyanines,
  ICPP-4, Rome, Italy, 2-7 July, 2006 (to be
  published).

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M.E. Marhic, Storage limit of two-photon-based
three-dimensional memories with parallel access,
Opt. Lett., 16, 1272-1273 (1991).
For systems that use parallel access by
simultaneous writing or reading of bits located
in an entire common plane, diffraction sets a
limit to the storage density that is far smaller
than that for sequential operation. Comparable
densities can be achieved by using a
three-dimensional waveguiding structure.