WO1996003674A1

WO1996003674A1 - Bleachable optical waveguide component

Info

Publication number: WO1996003674A1
Application number: PCT/EP1995/002880
Authority: WO
Inventors: Marcus Charles Johannes Marie Donckers; Bernhardus Henricus Maria Hams; Ulfert Elle Wiersum; Tjerk Oedse Boonstra
Original assignee: Akzo Nobel N.V.
Priority date: 1994-07-22
Filing date: 1995-07-19
Publication date: 1996-02-08
Also published as: TW243501B

Abstract

Disclosed is an optical waveguide component having a layered structure comprising a polymeric guiding layer sandwiched between two deflection layers of lower refractive index than the guiding layer, wherein the guiding layer polymer comprises moieties susceptible to a change of refractive index when subjected to appropriate irradiation. Thus, the guiding layer polymer is rendered photobleachable. According to the invention, said moieties include a structure that satisfies the chemical formula (I), wherein n is 0, 1 or 2, and R?1 and R2¿ may be the same or different, and represent hydrogen, a C¿1-6? alkyl group, notably a methyl, ethyl, or propyl group, or a functional group through which the polymer can be cross-linked, such as isocyanate, hydroxy, epoxy. It has been found that these structures lead to unexpectedly favourable bleaching characteristics.

Description

BLEACHABLE OPTICAL WAVEGUIDE COMPONENT

The invention is in the field of optical waveguides. Such waveguides generally are built up such that light can propagate within the confinement of a waveguiding material surrounded by a material having a lower refractive index than the waveguiding material.

The invention is directed to optical waveguide components having a layered structure comprising a polymeric guiding layer sandwiched between two deflection layers of lower refractive index than the guiding layer, wherein the guiding layer polymer comprises moieties susceptible to a change of refractive index when subjected to appropriate irradiation. Thus, the wave confinement in vertical direction (i.e., perpendicular to the layers) is determined by the layered structure, and waveguide channels can be laterally defined by selectively changing the refractive index of the guiding layer polymer. The refractive index change in most cases amounts to a decrease, and the irradiation process is referred to as a bleaching process. The moieties susceptible to the refractive index change thus render the guiding layer polymer photobleachable, and the waveguide channels can be created by irradiating the material surrounding the desired confinement region. The invention especially is also directed to bleachable optical waveguide components that can be made electro- optically active, i.e. non-linear optical (NLO) polymers.

Bleachable optical waveguide components of the type referred to above have been disclosed in US 5,142,605 (and corresponding EP 358 476), which disclosure is hereby incorporated by reference into this description for all purposes. While suitable results can be achieved with the components disclosed herein, and these components can be made electro-optically active, other materials are being sought, and improvements are still desired. It is an object of the present invention to provide new and useful bleachable optical waveguide components. In particular, the invention seeks to provide such components as are capable of more efficient definition of lateral wave confinements (channels) than prior art components, i.e., that require a lower bleaching dose and/or in which suitable waveguide channels can be defined through a faster process. The invention also seeks to provide bleachable components that can be rendered electro-optically active at the same time, and which yield better e/o characteristics than prior art components of the type in which waveguide channels are defined by bleaching.

To this end, the invention consists therein that, in an optical waveguide component as described above, the moieties that are susceptible to a change of refractive index when subjected to appropriate irradiation include a structure that satisfies the following chemical formula:

C- /

CH - C

/ \ - CH=CH- CH Formula I

^{Rl R2} wherein n is 0,1 or 2, and Rι and R* may be the same or different, and represent hydrogen, a C^.β alkyl group, notably a methyl, ethyl, or propyl group, or a functional group through which the polymer can be crosslinked, such as hydroxy, epoxy. These structures exhibit unexpectedly favourable characteristics in respect of the bleaching time and dose required to laterally define waveguide channels.

Said structure is preferably incorporated in the form of a side group, pendant from a polymeric backbone. The polymeric backbone can, in principle, be of any type, including polyurethanes, polycarbonates, polyimides, polyesters, and polyacrylates. The polymeric backbone may be cross-linked. Preferred backbones are polyurethanes, polycarbonates, and polyimides.

It should be noted that NLO polymers comprising the above moiety have been described before. See EP 363 237, WO 91/13116, US 5 187 234, WO

91/02018, WO 91/02019, WO 92/22593, and EP 359 648. These disclosures are silent on the making of optical waveguide components.

As indicated above, it is particularly desired that the optical waveguide component of the present invention can be made electro-op - cally active. E/O-active, or NLO materials, are known. In such material: non-linear charge polarization occurs under the influence of an external electric field. Non-linear electric polar. Sc'.ion may give rise to several optically non-linear phenomena such as frequency doubling and Pockels effect. Obtaining the desired NLO effect in polymeric materials macroscopically requires that first the groups present in such a material, mostly hyperpolarisable side groups, be aligned (poled). Such poling is usually effected by exposing the polymeric material to electric (dc) voltage, the so-called poling field, with such heating as will render the polymeric chains sufficiently mobile for orientation.

In order to enable the optical waveguide component according to the invention to be made electro-optically active, an electron donor and an electron acceptor should be attached to the ethenyl dimethylcyclohexenylidene structure so as to form a Dn-A group in which the rr-system comprises the ethenyl dimethylcyclohexenylidene structure.

Donor groups for such Dn-A-systems can be those known in the art as "+M" groups, i.e., functional groups which are electron-donating by the resonance effect, see J. March Advanced Organic Chemistry, thir edition (1985), pages 237-238. Some examples of "+M" groups are -0", -S^", a ino groups including -NR2, NHR, and NH2, amido groups i attached via nitrogen (-NHC0R), alkoxy groups, hydroxyl groups, este groups if attached via the alcoholic oxygen (-0C0R), thiol ethers (-SR), mercapto groups (-SH), halogen (Br, I, Cl , F) , alkyl and aryl groups. The abbreviation R is used to indicate alkyl groups i general. These include methyl, ethyl, propyl, butyl, pentyl hexyl , and larger groups. Included are all isomers. Such groups can be attached via any carbon atom in the alkyl chain.

Acceptor groups can be described analogously as "-M" groups. Some examples are nitrogen, cyano, carboxylic acid, carboxylic ester if attached via carboxylic carbon (-C0OR), amido if attached via carboxylic carbon (-CONH2, -CONHR, CONR2), aldehydo (-CH0), keto (-C0R), sulfonyl (-SC R), sulfonate (-SO2OR), nitroso, and aryl (which is capable of both kinds of resonance effects). Suitable acceptor groups include barbiturates and thiobarbiturates, i.e. groups satisfying one of the following formulae:

0 0

II II

C-NH C-NH

/ \ / \

=C C=0 or =C C=S

In order for the above structures to become pendant side groups of an NLO polymer, the donor side has to be appropriately functionalized. E.g., for the preparation of polyurethanes and polycarbonates a diol function is employed, e.g. as in Formula II: (Formula II)

wherein Ri and R* have the meaning given above and D stands for an electron-donating moiety.

As suitable diol groups, i.e., the groups forming the moiety

HO

\ D- (Formula III), / HO may be mentioned those satisfying the following structural formulae:

i

10 OH HO OH

1 I I

CH₂ CH₂ HO OH CH₂ CH₂

\ / \ / / c== ====c C- -c C=====C

I I

1 1 I I S S C c S N

\ / \ / \ / c N C

CH

\

HO OH HO OH

\ / \ / c= ===C C===C

/ \ / \

0 N HN N

\ / \

C C

HO C C OH HO C OH

\ / \ / \ / \ / \ / C c c c c c

I II

C C c c c c

wherein OH stands for the OH-groups of Formula III

The preferred donor groups are alkoxy and amino groups. The preferred acceptor groups are cyano and nitro groups, with dicyano having the highest preference. In this respect, the following structure is preferred for the bleachable NLO moieties: CN

I

C-CN

(Formula IV)

wherein Ri and R* have the meaning given above.

The bleachable moiety according to the invention preferably is incorporated into a polyurethane by reacting a di isocyanate, preferably isophorone diisocyanate, with the diol [3-[2- [4- [bis (2-hydroxyethyl) amino] phenyl ] ethenyl ] 5,5-dimethyl-2-cyclo hexene-1-ylidene]- propane dinitrile, i.e., a diol satisfing the following chemical formula:

(Formula V)

wherein R* and R* have the meaning given above. Other preferred diol moieties include dihydroxypyrrolidine and dihydroxydithiaful vene groups.

Alternatively, of course, other, preferably aromatic, diols may be incorporated into the monomer mixture to enhance the polyurethane 's properties, such as Tg, mechanical strength, etc. For instance, use may be made of diols having a thermally or photochemically cross- linkable group, e.g., an allyl group, epoxy group, or isocyanate group. Alternatively, in addition to the diols according to formula II use may be made isocyanates having more than two isocyanate groups or diisocyanates containing another thermally or photoche ically cross- linkable group, e.g., an allyl group or epoxy group. Further, in addition to the compounds according to formula II and diisocyanates there may be added to the monomer mixture or to the resulting (pre)poly er compounds which will render the final polyurethane cross-linkable such as polyepoxides. It is preferred to use these cross-linkable polymers in waveguides made by spincoating various layers of polyurethane one on top of the other. In consequence, the invention also pertains to cross-linkable and already cross-linked polyurethanes obtained from a monomer mixture comprising a diol according to formula II and diisocyanates, with there being a cross-linkable group either in the monomer mixture as an additional compound or inthe diisocyanate.

Polyimides incorporating the above moiety are preferably prepared by reacting a tetracarboxylic dianhydride with a diamine of the following formula:

(Formula VI)

wherein Ri and R* have the meaning given above, and Ar stands for a substituted or unsubstituted aromatic ring such as phenylene, naphthylidene, tolylene, and the like. It is also possible to use a tetracarboxylic acid for the reaction with the diamine, and thereafter to effect ring closure of the resulting polyamic acid. Preferred tetracarboxylic acids are pyromellitic acid, benzophenon tetracarboxylic acid, 2,2-isopropylidene di(phthalic acid), and particularly hexafluoro 2,2-isopropylidene di(phthalic acid). The corresponding dianhydrides are preferred over the free acids.

The polyimides prepared from the diamine of Formula VI and a tetracarboxylic acid or the dianhydride thereof exhibit int.al. the following advantageous properties: they allow excellent definition of the waveguide channels, are stable at high temperatures (above 200^CC and higher), and have a high electro-optical coefficient upon poling. In these respects the instant polyimides are an improvement over known NLO polyimides such as those described in WO 91/03001.

In the preparation of polycarbonates, the above diols are reacted with a compound according to the following chemical formula:

- Q (Formula VII)

wherein: P stands for -Cl , 0-R, an imidazole group or -O-Ph, Q stands for -Cl, 0-R, an imidazole group or -O-Ph, R stands for an alkylene group having 1-6 carbon atoms, Ph stands for phenyl ,

A stands for -Ph-, halogenated -Ph-, -Ph-C(CH3)2~Ph-, -Ph-C(CF₃)₂-Ph, -Ph-C(S0₂)2-Ph-. a cycloalkylene group having 1-24 carbon atoms, a halo substituted cycloalkylene group having 1-24 carbon atoms, an arylene group having 1-20 carbon atoms, or a naphthalene group, is an integer from 0 to 5, with the A-groups being the same or different.

Preferably, this compound is a bischloroformate of bisphenol-A or hexafluorobisphenol-A. The resulting polycarbonates display excellent bleaching and e/o properties, have relatively high Tgs of above 150°C, and low optical attenuation (low loss of propagating light).

Alternatively, of course, other, preferably aromatic, diols may be incorporated into the monomer mixture to enhance the polycarbonate's properties, such as Tg, mechanical strength, etc. For instance, use may be made of diols having a thermally or photochemically cross- linkable group, e.g., an allyl group, epoxy group, or isocyanate group. Alternatively, in addition to the diols according to formula II use may be made of compounds according to formula VII containing a thermally or photoche ically cross-linkable group, e.g., an allyl group, epoxy group, or isocyanate group. Further, in addition to the compounds according to formula VII and the diols according to formula II there may be added to the monomer mixture or to the resulting (pre)polymer compounds which will render the final polycarbonate cross-linkable. Examples of these include polyisocyanates and polyepoxides. It is preferred to use these cross-linkable polymers in waveguides made by spincoating various layers of polycarbonate one on top of the other. In consequence, the invention also pertains to cross-linkable and already cross-linked polycarbonates obtained from a monomer mixture comprising a diol according to formula II and a compound according to formula VII, with there being a cross-linkable group either in the monomer mixture as an additional compound, or in a compound according to formula VII. With reference to the above-mentioned publications on NLO polymers, the man skilled in the art is aware of preparation methods for them. In particular, as regards polyurethanes EP 359 648 is referred to. Polyimides can be prepared analogously to WO 91/03001.

The polycarbonates can be obtained by reacting diols according to Formula II in a basic solvent such as pyridine or THF containing a tertiary amine with an equivalent amount of a compound according to Formula VII. For setting the molecular weight a quantity of chain stopper may be added, e.g., phenol. For further details with regard to the preparation of polycarbonates reference may be had to Comp. Pol. Sci . : The Synthesis, Characterization, Reactions and Applications of Polymers Vol. 5 (Pergamon Press), Chapter 20, pp. 345-356.

The making of polymeric layered waveguide components in general is known to the man skilled in the art. The consecutive layers, mostly a bottom deflection layer, a guiding layer, and a top deflection layer, may be coated onto a substrate in the form of, say, a polymer solution, preferably by means of spin coating, and then evaporating the solvent.

The waveguide channels are defined laterally by a process comprising the steps of providing a layered planar waveguide component with a mask selectively covering portions thereof and then irradiating it through said mask so as to change the refractive index of the portions of the waveguiding material not covered.

As a mask metal may be used, usually gold or aluminium. This very effectively prohibits the bleaching irradiation from reaching the portions of the waveguiding polymer that should not be bleached. The process generally involves the following steps:

(a) making a layered waveguide;

(b) applying a metal film onto the waveguide;

(c) providing the metal film with a photoresist layer; (d) selectively exposing the photoresist through a mask defining the desired pattern of lateral wave confinement;

(e) developing the photoresist so as to selectively uncover the metal;

(f) etching away the uncovered metal portions so as to make openings;

(g) stripping off the photoresist;

(h) irradiating the waveguide through said openings with irradation that causes the refractive index of the waveguiding polymer to change;

(i) (optionally) etching away the metal.

If an electro-optically active waveguide is made, it is possible to refrain from removing the metal mask, as it can be used as an electrode. For passive waveguide components and thermo-optic waveguide components, the metal layer is removed as redundant.

The bleaching wavelength for the optical waveguide components according to the invention, i.e., in which the bleachable group comprises a moiety according to Formula I, depends on the electron- donor and -acceptor groups chosen. It is preferably within the charge- transfer absorption region of the side-group. For most materials this will be within a range of from 350 to 750 nm. For the preferred structure of Formula IV, this range is 400-550 nm. The bleaching wavelength for this side group is preferably of from 490-500, λ_max being 493 nm. When the components of the invention are thus irradiated, highly suitable refractive index contrasts up to the preferred value of 0.005 and higher (such as 0.05) can be easily obtained. The contrast is preferably above 0.002. It should be noted that it may not be necessary for the guiding layer to be bleached throughout the entire layer thickness. What is essential is that in the area of the desired channels the light guided through the guiding layer experiences an effective index of refraction that is sufficiently higher than the refractive index of the surrounding material. In the case of a relatively low local refractive index change, a greater bleaching depth will generally be needed to obtain the desired effective index change than in the case of a relatively high local refractive index change.

The invention also pertains to polymeric optical waveguide devices comprising a polymeric optical waveguide having a layered structure as indicated above, wherein the guiding layer comprises a pattern of waveguide channels having a higher refractive index than the surrounding polymeric material, the pattern being formed by photobleaching the surrounding material, wherein the guiding layer consists essentially of a polymer comprising moieties according to Formula I. Preferably, the guiding layer polymer comprises these moieties as pendant side groups.

The invention will be further elucidated with reference to the following, unli itative examples.

EXAMPLE 1

A polyurethane having side groups in accordance with Formula V was prepared as follows. To 14 ml of DMF (dimethyl formamide) were added 3.77 g of [3-[2-[4-[bis (2-hydroxyethyl ) amino] phenyl] ethenyl] 5,5-dimethy1-2-cyclohexene-l-ylidene]-propane dinitrile (the diol of Formula V), and 2.22 g of isophorone diisocyanate. The reaction mixture was stirred at 100°C for 18 hours, cooled down to room temperature, precipitated in methanol , filtrated and dried. A polyurethane having an MW of 44000 and a Tg of 151°C resulted.

A three-layer planar waveguiding structure was prepared by successively spin coating and curing a bottom cladding (deflection layer) with a thickness of 3.47 μm, a core layer (guiding layer) with a thickness of 1.81 μm, and a top cladding (deflection layer) with a thickness of 3.42 μm. A polished Si wafer was used as substrate. Th bottom and top claddings were spin cast from a solution of HEMA/styrene copolymer and Desmodur N3390 in cyclopentanone. The inde of refraction at 1300 nm of the resulting cladding layers wa determined from prism coupling measurements to be 1.552. The core layer was spin cast from a solution of the above polyurethane in cyclopentanone. The refractive index of the unpoled core layer at 1300 nm was measured to be 1.654. After spin coating, the bottom and core layers were both cured for 90 minutes on a hot stage at 140°C. The top cladding was cured at the same temperature for 150 minutes. After the curing of the top cladding, a 100-nm thick Au layer was vacuum deposited on top of the waveguiding structure.

In order to make the resulting component electro-optically active, a voltage of -1080 V was applied to the Au top electrode and the optoboard was heated to 135°C, enabling the pendant side groups of the guiding layer polyurethane to align themselves along the applied field. After 10 minutes at 135°C, the component was cooled to 122°C in 4 minutes, at which temperature it was kept for another 4 minutes. Subsequently, the component was cooled to room temperature in a few minutes and the applied voltage was removed.

To define channel waveguides in the polymeric multilayer for lateral confinement of the light, the Au film was patterned into a mask for photobleaching of the core. A photoresist layer was spin coated on top of the Au film and baked for 2 minutes at 90°C. After exposure of the photoresist through a mask containing the desired waveguide pattern, the photoresist was developed and the uncovered regions of the Au layer were removed using a wet-etching process. Only the Au above the channel waveguides to be defined was retained. The uncovered areas were photobleached through irradiation with light of a wavelength of 420(+20)nm and an intensity of 15 mW/cm². Thus, two sections each containing 20 directional couplers with a coupling length varying from 96/03674 PCI7EP95/02880

15

1 mm to 20 mm were patterned in the three-layer polymeric structure. The irradiation time was chosen such that the accumulated irradiation dose amounted to 36 J/cm² for one section, and 54 J/cm² for the other. An identically prepared layered waveguide structure was patterned with a number of Mach-Zehnder interferometers, using a bleaching dose of 36 J/cm².

After bleaching of the uncovered areas the Au mask was stripped and a new 100-nm thick Au layer was vacuum deposited on top of the optoboard. This Au film was patterned according to the procedure outlined above so as to provide electrodes above the branches of the Mach-Zehnder interferometers.

The change in the effective index of refraction of the exposed areas with respect of that of the unexposed channels was derived from the experimentally determined beat length of the directional couplers. The irradiation doses of 36 J/cm² and 54 J/cm² were found to result in a lowering of the effective index of refraction at 1300 nm of 0.0044 and 0.0056 respectively. The electro-optic activity at 1300 nm was assessed by measuring Vπ L for the Mach-Zehnder interferometers, which was found to be 16.9 Vcm. Here, L is the length of the electrodes above the arms of the MZI.

COMPARATIVE EXAMPLE

A polyurethane having side groups derived from 4-di-(2-hydroxyethyl)amino-4'-nitrostilbene was prepared in accordance with Example 8 of EP 350 112. This polymer was chosen for comparison as up to now it has given optimal results in respect of waveguide channel formation and electro-optical activity. Following the procedure as outlined in Example 1, a three-layer plana waveguiding structure was prepared and poled, the bottom claddin having a thickness of 3.22 μm, the core having a thickness of 1.66 μm and the top cladding having a thickness of 3.23 μm. The unpoled cor layer had a refractive index at 1300 nm of 1.622.

Bleaching was conducted choosing such irradiation time that th accumulated irradiation dose amounted to 252 J/cm². Thus, 2 directional couplers with a coupling length varying from 1 mm to 20 m and a number of Mach-Zehnder interferometers were patterned in th three-layer polymeric structure.

After bleaching of the uncovered areas the Au mask was stripped and new 100-nm thick Au layer was vacuum deposited on top of th optoboard. This Au film was patterned according to the procedur outlined above so as to provide electrodes above the branches of th Mach-Zehnder interferometers.

The change in the effective index of refraction of the exposed areas with respect of that of the unexposed channels was derived from th experimentally determined beat length of the directional couplers. Th irradiation dose of 252 J/cm² was found to result in a lowering of th effective index of refraction of 0.005 at 1300 nm. The electro-optic activity at 1300 nm was assessed by measuring Vπ- L for the Mach- Zehnder interferometers, which was found to be 23.4 Vcm. Here, L is the length of the electrodes above the arms of the MZI.

EXAMPLE 2

A polycarbonate having side groups in accordance with formula V was prepared as follows. To 19.4 g of [3-[2-[4-[bis (2-hydroxyethyl ) amino] phenyl] ethenyl] 5,5-dimethyl-2-cyclohexene-l-ylidene]-propane dinitrile (the diol of Formula V) and 40.0 g of hexafluorotetrabromobisphenol A bischloroformate in 400 ml of THF (tetrahydrofuran) there was added dropwise in one hour 8.3 ml of pyridine, at 0°C. The reaction mixture was allowed to heat up to 20^CC. After 18 hours of stirring, the reaction product was precipitated in ethanol . M.W.: 23000, Tg was measured to be 167-175°C.

A successfully bleached electro-optically active layered waveguide component was made following the procedure described in Example 1, using o-xylene instead of cyclopentanone for spincoating the top cladding.

EXAMPLE 3

According to the procedure described in Example 2, a polycarbonate having a molecular weight of 16000 and a Tg of 141°C was prepared using 2,97 g of hexafluoro bisphenol-A bischloroformate, 2.43 g of the diol of Formula V, 1.04 ml of pyridine, and 30 ml of THF.

A successfully bleached electro-optically active layered waveguide component was made following the procedure described in Example 1, again using o-xylene for spincoating the top cladding.

EXAMPLE 4

(Preparation of polyimide)

First an amine according to Formula VIII was prepared, and converted to the diamine of Formula IX, as follows:

In a reaction vessel were added to 2.5 1 THF (tetrahydrofuran) and heated to 65°C 478.0 g (3.46 moles) of distilled isophorone, 228.4 g (3.46 moles) of alonitril (dicyano methylene), 84.2 g (0.94 moles) of /3-alanine, and 41.85 g (0.48 moles) of piperidine. After the mixture had been kept at 65°C for 1 hour, 565.3 g (3.46 moles) of 4-acetamid benzaldehyde was added. The reaction mixture was stirred overnight at 65°C, which resulted in a solid being formed. After cooling down to 20°C, the resulting suspension was drained via a P3 glass filter, the solid was washed using 800 ml of THF, and the product was dried in a vacuum stove. Yield: 65% of the acetate of the amine of Formula VIII. 720 g (2.2 moles) of the acetate was converted into the free amine by stirring in 2.2 1 THF for 20 minutes, adding 2.88 1 (17.3 moles) of 6N HC1 , and stirring overnight at 71°C. After neutralization with a 50% NaOH solution, draining the resulting emulsion, evaporating THF, and washing and drying the resulting solid, the amine of Formula VIII was obtained in 88% yield.

(Formula VIII)

In order to prepare the diamine of Formula IX 17.0 g (58.8 mmoles) of the amine of formula VIII, 27.36 g (120.0 mmoles) of 3-acetamidobenzyl bromide, 22.4 g (267.0 mmoles) of sodium bicarbonate, and 0.635 g (3.8 mmoles) of potassium iodide were mixed in N-methyl pyrrolidone and stirred overnight at 110°C. After cooling and pouring out into water, 2 hours of stirring, filtration, and washing with water, the resulting intermediate (36 g of the diacetamide of the desired diamine) was dried in a stove at 50°C for 3 days. Next, 35 g of this intermediate were added to 150 ml of THF and 150 ml of HC1 6N. The resulting reaction mixture was refluxed overnight at 65°C, with stirring, and subsequently poured out into ice/water containing 1 mol of NaOH. After several filtration and washing steps, and flash-column chromatography over silica, using methylene chloride as the eluent, pure diamine of Formula IX was obtained.

(Formula IX) wherein Ph stands for phenylene.

A polyimide was prepared by reacting 4.12 g (8.25 mmoles) of the above diamine with 3.33 g (7.5 mmoles) of hexafluoro isopropylidene 2,2-di (phthalic anhydride) and 0.15 g (1.5 mmoles) of maleic anhydride in 70 ml of dimethyl aceta ide. The reaction was conducted at 20^CC overnight. Thereafter 10 ml of toluene were added, followed by 16 hours of stirring at reflux temperature (employing a Dean-Stark apparatus to drive off water, and affect imide ring closure). The toluene was distilled off, and after cooling down the reaction product was precipitated in ethanol, filtrated, washed, and dried in a vacuum stove. A polyimide resulted with MW of 10.000, Tg of 223-234 °C. T6A (thermogravi etric analysis) showed decomposition above 280°C.

A successfully bleached electro-optically active layered waveguide component was made following the procedure described in Example 1.

Claims

Claims:

An optical waveguide component having a layered structur comprising a polymeric guiding layer sandwiched between tw deflection layers of lower refractive index than the guiding layer wherein the guiding layer polymer comprises moieties susceptible t a change of refractive index when subjected to appropriat irradiation, thus rendering the guiding layer polyme photobleachable, characterized in that these moieties include structure that satisfies the following chemical formula:

/

CH - C

/ \ CH=CH-C CH? Formula I

\ / (CH_2)n-

wherein n is 0,1 or 2, and Ri and R^ may be the same or differen and represent hydrogen, a Cι_β alkyl group, or a functional group.

2. An optical waveguide component according to claim 1, characterize in that the structure is incorporated in the form of a side group pendant from a polymeric backbone.

3. An optical waveguide component according to claim 2, characterize in that the backbone is selected from the group consisting o polyurethanes, polycarbonates, and polyimides.

4. An optical waveguide component according to claim 2 or 3, characterized in that an electron donor and an electron accepto are attached to the depicted structure so as to form a DrrA group i which the rr-system comprises said structure.

5. An optical waveguide component according to claim 4, characterized in that the guiding layer polymer is a polyurethane made by reacting a diisocyanate with a diol according to Formula II:

(Formula II)

wherein Ri and R* have the meaning as given in claim 1, and D stands for an electron-donating moiety.

6. An optical waveguide component according to claim 5, characterized in that the diisocyanate is isophorone diisocyanate and the diol satisfies Formula V:

HO CN

\ I

CH₂ C-CN

/ /

CH₂ CH-CH CH-C

\ / \ / \

N-C C-CH=CH-C CH? (Formula V)

/ \ / \ / CH₂ CH=CH CH₂-C \ /\

CH₉ R> R*

/ ² OH wherein R^ and R* may be the same or different and represent hydrogen or a methyl, ethyl, or propyl group.

7. A polymeric optical waveguide device comprising a polymeric optical waveguide having a layered structure comprising a polymeric guiding layer sandwiched between two deflection layers of a lower refractive index than the guiding layer, wherein the guiding layer comprises a pattern of waveguide channels having a higher refractive index than the surrounding polymeric material, the pattern being formed by photobleaching the surrounding material, characterized in that the guiding layer consists essentially of a polymer having side groups that include a structure according to Formula I.

8. A polymeric optical waveguide device according to claim 7, characterized in that the guiding layer polymer is selected from the group consisting of polyurethanes, polycarbonates, and polyimides.

9. A polyimide having side groups that are susceptible to a change of refractive index when subjected to appropriate irradiation and can be made electro-optically active, the polyimide being obtainable by reacting a diamine with a tetracarboxylic acid or the corresponding dianhydride, characterized in that the diamine satisfies the following formula:

(Formula VI)

wherein Ri and R* have the meaning given above, and Ar stands for a substituted or unsubstituted aromatic compound.