Optical waveguides – Planar optical waveguide – Thin film optical waveguide
Reexamination Certificate
2000-06-16
2003-06-24
Lee, John D. (Department: 2874)
Optical waveguides
Planar optical waveguide
Thin film optical waveguide
C385S142000, C385S143000, C252S582000, C428S412000, C428S423100, C428S473500
Reexamination Certificate
active
06584266
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to chromophores which can be used in the preparation of polymeric thin films for waveguide media, and to optical waveguides and devices comprising the chromophores.
BACKGROUND OF THE INVENTION
Thin films of organic or polymeric materials with large second order nonlinearities in combination with silicon-based electronic circuitry can be used in systems for laser modulation and deflection, information control in optical circuitry, as well as in numerous other waveguide applications. In addition, novel processes through third order nonlinearity such as degenerate four-wave mixing, whereby real-time processing of optical fields occurs, have utility in such diverse fields as optical communications and integrated circuit fabrication. The utility of organic materials with large second order and third order nonlinearities for very high frequency application contrasts with the bandwidth limitations of conventional inorganic electrooptic materials currently in use.
Numerous optically responsive monomers and polymers have been developed for use in organic materials which, in turn, can be used in the waveguide applications described above. For example, U.S. Pat. No. 5,044,725, which is incorporated herein by reference in its entirety, describes numerous polymer compositions which provide suitable nonlinear optical response. U.S. Pat. No. 5,044,725 describes, for example, a preferred polymer composition comprising an organic chromophore containing an electron donating group and an electron withdrawing group at opposing termini of a bridge.
Synthesis of high performance organic, high &mgr;&bgr; electro-optic chromophores must be accomplished in order to make polymer-based electro-optic waveguides and devices. The synthesis of electro-optic chromophore bridge compounds and donor-bridge compounds for organic nonlinear optical applications are generally known in the art. Although some chromophores have been reported in the literature, many of them have showed several and sometimes severe problems ranging from thermal instability, insolubility in the polymer, photodegradability, exhibition of a broad absorption band into the wavelength region of interest, and large birefringence upon poling. Accordingly, suitable electro-optic chromophores are desired.
SUMMARY OF THE INVENTION
The present invention is directed, in part, to compounds which can serve as chromophores in, for example, thin films for optical waveguides and optical devices.
Preferred compounds of the invention comprise novel electron withdrawing groups and have Formula I:
wherein D is an electron donating group; B is or contains at least one bivalent aromatic ring; and R
2
and R
3
each, independently, are either H, substituted or unsubstituted C
1
-C
10
alkyl, substituted or unsubstituted C
2
-C
10
alkenyl, substituted or unsubstituted C
2
-C
10
alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted alkylaryl, substituted or unsubstituted carbocyclic, substituted or unsubstituted heterocyclic, substituted or unsubstituted cyclohexyl, or (CH
2
)
n
—O—(CH
2
)
n
, where n is 1-10. Alternatively, R
2
and R
3
together form a ring structure or a substituted ring structure.
In other embodiments of the invention, the chromophores comprise novel cyclic bridges comprising at least one bivalent aromatic ring. Preferred compounds of the invention have Formula II:
wherein D is an electron donating group; A is an electron withdrawing group; K is O or S; R
1
is —Q—C
n
H
2n+1
, —Q—(CH
2
)
a
C
n
F
2n+1
, —Q—CH
2
OCH
2
C
n
F
2n+1
, —Q—CH
2
SCH
2
CC
n
F
2n+1
, —Q—CH
2
OCH
2
CF
3
, or —Q—CH
2
SCH
2
CF
3
, where n is 1-10, a is 0-10, and Q is absent, O or S; and q is 1, 2, or 3.
Other preferred compounds of the invention have Formula III:
wherein D is an electron donating group; A is an electron withdrawing group; J is CH
2
, O or S; R
1
is —Q—C
n
H
2n+1
, —Q—(CH
2
)
a
C
n
F
2n+1
, —Q—CH
2
OCH
2
C
n
F
2n+1
, —Q—CH
2
SCH
2
CC
n
F
2n+1
, —Q—CH
2
OCH
2
CF
3
, or —Q—CH
2
SCH
2
CF
3
, where n is 1-10, a is 0-10, and Q is absent, O or S,
In other embodiments of the invention, the chromophores comprise novel cyclic bridges comprising at least one bivalent or conjugated ring structure, such as an aromatic ring, and novel electron withdrawing groups. Preferred compounds of the invention have Formula IV:
wherein D is an electron donating group; K is O or S; R
1
is —Q—C
n
H
2n+1
, —Q—(CH
2
)
a
C
n
F
2n+1
, —Q—CH
2
OCH
2
C
n
F
2n+1
, —Q—CH
2
SCH
2
CC
n
F
2n+1
, —Q—CH
2
OCH
2
CF
3
, or —Q—CH
2
SCH
2
CF
3
, where n is 1-10, a is 0-10, and Q is absent, O or S; q is 1, 2, or 3; and R
2
and R
3
each, independently, are either H, substituted or unsubstituted C
1
-C
10
alkyl, substituted or unsubstituted C
2
-C
10
alkenyl, substituted or unsubstituted C
2
-C
10
alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted alkylaryl, substituted or unsubstituted carbocycle, substituted or unsubstituted heterocycle, substituted or unsubstituted cyclohexyl, or (CH
2
)
n
—O—(CH
2
)
n
where n is 1-10. Alternatively, R
2
and R
3
together form a ring structure or a substituted ring structure.
Other preferred compounds of the invention have Formula V:
wherein D is an electron donating group; J is CH
2
, O or S; R
1
is —Q—C
n
H
2n+1
, —Q—(CH
2
)
a
C
n
F
2n+1
, —Q—CH
2
OCH
2
C
n
F
2n+1
, —Q—CH
2
SCH
2
CC
n
F
2n+1
, —Q—CH
2
OCH
2
CF
3
, or —Q—CH
2
SCH
2
CF
3
, where n is 1-10, a is 0-10, and Q is absent, O or S; and R
2
and R
3
each, independently, are either H, substituted or unsubstituted C
1
-C
10
alkyl, substituted or unsubstituted C
2
-C
10
alkenyl, substituted or unsubstituted C
2
-C
10
alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted alkylaryl, substituted or unsubstituted carbocycle, substituted or unsubstituted heterocycle, substituted or unsubstituted cyclohexyl, or (CH
2
)
n
—O—(CH
2
)
n
where n is 1-10. Alternatively, R
2
and R
3
together form a ring structure or a substituted ring structure.
The present invention is also directed to optical waveguides comprising a thin film medium having Formula VI:
wherein P and P′ are polymer main chain units, which can be the same mer unit or different mer unit, and C is a comonomer unit where n is an integer greater than zero and n′ is 0 or an integer greater than zero; S is a pendant spacer group having a linear chain length of between about 2-12 atoms. M is a compound having either Formula I, Formula II, Formula III, Formula IV, or Formula V, as described above.
The chromophores of the present invention have several advantageous features which are not found in other known or commercially available chromophores. The electro-optic chromophores of the invention exhibit thermal stability to temperatures from 260° C. to 310° C. The chromophores of the invention also show great solubility in most common organic solvents and, thus, are useful in most polymer films for waveguides. In addition, under intense UV-irradiation (365 nm, dosage 3 J/cm
2
up to 13 minutes), the chromophores of the invention show no changes of the UV-VIS-NIR spectrum, which indicates that the chromophores are photo stable. The chromophores of the present invention also demonstrate an adjustable absorption band away from normal communications wavelenghts, which can be very important for reducing optical loss at communication wavelengths. The chromophores of the invention have significant three-dimensional design which can prevent chromophore-chromophore anti-parallel stacking. Because of the flexible side chain substitutions, the chromophores of the invention show significantly reduced birefringence losses. In some of the chromophores of the invention, there is unique regiospecific substitution on the bridging thiophene ring, which allows the electron acceptor to more easily access the conjugated &pgr; system of the bridge and allows the molecule backbone to be flatter. In addition, some of the preferred chromophores of the invention have
He Mingqian
Leslie Thomas M.
Braman & Rogalskyj LLP
Corning Incorporated
Douglas Walter M.
Lee John D.
Nwaneri Angela N.
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