Title: Resonance enhancement of twophoton crosssection for optical storage in the presence of hot band abso
1Resonance enhancement of two-photon cross-section
for optical storage in the presence of hot band
absorption
N. Makarov, A. Rebane, M. Drobizhev, D.
Peone (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) E. Makarova, E.
Lukyanets (Organic Intermediates and Dyes
Institute, Moscow, Russia)
2Outline
- Principles of 3D 2PA optical memory
- 2PA-sensitive photochromes
- Resonance enhancement
- 2PA vs. 1PA
- 2PA in phthalocyanines
- Summary
3Principles of 3D 2PA optical memory
4Need for 2PA-sensitive photochromes
Access with 1 pulse 100fs, 100MHz gt 1TB
read/write in 24 hrs Each bit have to be written
and read by only 1 femtosecond pulse!
52PA resonance enhancement
- A fundamental trade-off between 2PA and 1PA
- tune laser frequency as close as possible to the
resonance - tune as far as possible to decrease 1PA
background
62PA vs. 1PA
Absorption spectra at different temperatures as
calculated from fluorescence spectrum
Power dependence of the fluorescence signal
72PA-sensitive phtalocyanines
82PA-sensitive phtalocyanines
- The change of substituents from butyl groups at
?-positions to alkoxy groups at ?-positions
(molecule 1 vs. 2) increases 2PA cross-sections
by a factor of nearly 2. This also results in the
red shift of entire 1PA spectrum by 30 nm (500
cm-1). The 2PA spectrum also experiences the red
shift. This shows that addition of oxygen atoms
increases ?-conjugation. - Addition of extra CHO group (molecule 1 vs. 6)
results in a slight decrease of 2PA cross-section
as compared to better purified compound 1 and in
slight increase of the cross-sections compared to
1a and 1b. The 1PA spectrum practically does not
change. - Substituting an external benzene ring with
another alkoxy group (molecule 4 vs. 6) produces
a nearly symmetrical molecule. This shifts both
Qx and Qy peaks closer to each other so that they
overlap. A similar shift appears in 2PA spectrum.
The value of 2PA cross-section reduces by a
factor of nearly 2, which is probably because of
reduce of the difference in dipole moments in
more symmetrical molecule. - Addition of extra hydrogen atoms (molecule 3 vs.
4) reduces degree of symmetry. This slightly
increases the 2PA cross-section for molecule 3.
However, its cross-section is smaller than for
molecules 1 and 6. The reason is more symmetry
and thus less difference in dipole moments in the
molecule 3 - Change of substituent from molecule 3 to 5 makes
the molecule less symmetrical, and thus increase
2PA cross-section. However, molecule 6, and
especially 1 have the highest 2PA cross-sections
among all studied samples.
92PA-sensitive phtalocyanines comparison for 3D
memory
For molecules 3 and 5 absorption spectra of
tautomer forms T1 and T2 significantly overlaps
that makes them not practical as photochromes for
3D optical memory
10SNR-SBR comparison
11Summary
- 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 - A brief analysis of changes in 2PA spectra and
cross-sections due to different substituent
groups is provided and allow to deduce
structure-to-properties relations - We conclude that from the set of studied
molecules compound 1 is the most promising for
rewritable 3D optical memory.
12References
- D.A. Parthenopoulos, P.M. Rentzepis,
Three-Dimensional Optical Storage Memory,
Science, 245, 843-845 (1989). - 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,
J. Phys. Chem. B, 109, 7223-7236 (2005). - M. Drobizhev, A. Karotki, M. Kruk, N. Zh.
Mamardashvili, A. Rebane, Drastic enhancement of
two-photon absorption in porphyrins associated
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,
Hole Burning in Contour of a Pure Electronic
Line in a Shpolskii System, JETP Lett., 20,
216-218, (1974). - M. Drobizhev, A. Karotki, A. Rebane, Persistent
Spectral Hole Burning by Simultaneous Two-Photon
Absorption, Chem. Phys. Lett., 334, 76-82,
(2001). - A. Rebane, M. Drobizhev, A. Karotki, Y. Dzenis,
C.W. Spangler, A. Gong, F. Meng, New two-photon
materials for fast volumetric rewritable optical
storage, in Proc. SPIE, Advanced Optical and
Quantum Memories and Computing, Eds. H.J. Coufal,
Z.U. Hasan, (SPIE, Belligham, WA, 2004), 5362,
pp. 10-19. - M. Drobizhev, A. Karotki, M. Kruk, A.
Krivokapic, H.L. Anderson, A. Rebane, Photon
energy upconversion in porphyrins one-photon
hot-band absorption versus two-photon
absorption, Chem. Phys. Lett., 370, 690-699
(2003). - A. Karotki, M. Drobizhev, Y. Dzenis, P.N.
Taylor, H.L. Anderson, A. Rebane, Dramatic
enhancement of intrinsic two-photon absorption in
a conjugated porphyrin dimer, Phys. Chem. Chem.
Phys., 6, 7-10 (2004). - M. Drobizhev, A. Karotkii, A. Rebane, Dendrimer
molecules with record large two-photon absorption
cross section, Opt. Lett., 26, 1081-1083 (2001). - M. Drobizhev, N.S. Makarov, A. Rebane, E.A.
Makarova, E.A. Lukyanets, Two-photon absorption
in tetraazachlorin and its benzo-and
2,3-naphtho-fused derivatives Effective symmetry
of ?-conjugation pathway, J. Porphyrines and
Phtalocyanines, Proc. Of the International
Conference on Porphyrines and Phtalocyanines,
ICPP-4, Rome, Italy, 2-7 July, 2006 (to be
published).
13M.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.