JPH1068829A - Waveguide type optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-polymer waveguide type optical device having excellent heat resistance and moisture resistance by forming either or both of the core or clad of a directional coupler of fluorinated polyimide. SOLUTION: The directional coupler of which either or both of the core and the clad are formed of the fluorinated polyimide is included in this device. In such a case, the fluorinated polyimide produced from fluorinated tetracarboxylic acid or its deriv. and diamine, the fluorinated polyimide produced from tetracarboxylic acid or its deriv. and fluorinated diamine or the fluorinated polyimide produced from the fluroinated tetracarboxylic acid or its deriv. and fluorinated diamine is usable in this case. Not only the fluorinated polyimide alone but a fluorinated polyimide copolymer, fluorinated polyimide mixture and these fluorinated polyimide added with additives, etc., at need are usable as well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a waveguide type optical device formed using fluorinated polyimide.

[0002]

2. Description of the Related Art Various optical components have been researched and developed with the aim of improving the sophistication and economy of optical communication systems. Above all, optical waveguides are receiving attention as a basic technology for realizing high-density optical wiring and waveguide-type optical devices. In general, various conditions are required for an optical waveguide material, such as ease of manufacturing a waveguide, controllability of a refractive index, and heat resistance. At present, quartz is most often used as an optical waveguide material, and a quartz optical waveguide exhibits a low optical loss of 0.1 dB / cm or less at a wavelength of 1.3 μm. However, it has problems such as a complicated manufacturing process and difficulty in increasing the area, and it is difficult to obtain a waveguide-type optical device that is excellent in economy and versatility. On the other hand, since the polymer optical waveguide can be formed by using the spin coating method, it is easier to manufacture and enlarge the area as compared with the quartz optical waveguide. In addition, polymer materials have a thermo-optic (T
O) effect (temperature dependence of refractive index) in many cases.
Application to a waveguide type optical device utilizing the O effect is particularly promising. For example, polymethyl methacrylate (PMM
A) shows that the PMMA optical waveguide is a Mach-Zehnder TO switch because the temperature dependence of the refractive index is -1.0 × 10 ⁻⁴ / ° C., which is at least 10 times larger than that of quartz, 1 × 10 ⁻⁵ / ° C. or less. It is known that the switching power is greatly reduced to about 1/100 as compared with that of the silica-based optical waveguide when applied to HID [Hida et al., IEEE Photonics Techn.
ology Letters), Vol. 5, p. 782 (1993)].
However, since PMMA has a low heat distortion temperature of about 100 ° C. [Fumio Ide, “Optoelectronics and Polymers”, page 28, Kyoritsu Shuppan (1995)], the switching characteristics are repeated by repeated heating and cooling during operation. to degrade. Therefore, PMMA is not suitable for forming a waveguide type optical device utilizing the TO effect. Further, PMMA has a large hygroscopic property, and the refractive index greatly changes depending on the environmental humidity. For example, when a directional coupler, which is the most basic element of an optical component, is formed using PMMA, the branching ratio of the emitted light greatly changes depending on the installation environment. Furthermore, PMMA has a large absorption in the 1.55 μm band [Yoshimura et al., “Planar Polymer Lightwave Circuit”, Proceedings of IEICE Spring Conference, SC-8-3, 5-319 (199)
4)], there is a disadvantage that it cannot be used for optical communication parts in this wavelength band. As described above, as a material of the waveguide type optical device, a polymer material having excellent heat resistance, moisture resistance, and light transmittance at a long wavelength is required.

As a polymer material having excellent heat resistance, polyimide is well known, and is used for an interlayer insulating film of a semiconductor component, a flexible wiring board, and the like. However, this material is not only highly hygroscopic but also inferior in light transmittance in the near infrared region (1.3 μm, 1.55 μm), which is an optical communication wavelength band. Further, on the substrate, polarized light in the direction parallel to the substrate surface (TE polarized light) and polarized light in the direction perpendicular to the substrate surface (T
(M polarized light) has a different refractive index. For example, in the case of Kapton (manufactured by Dupon), which is a commonly used polyimide, the refractive index is 1.3 μm in wavelength, 1.6781 for TE polarized light, and 1.60113 for TM polarized light. .
For this reason, when used as the core or cladding material of the optical waveguide, the difference in refractive index between TE polarized light and TM polarized light is different, and polarization dependence of optical characteristics occurs. From the above, polyimide is not suitable as a material for a waveguide type optical component.

Heretofore, the present inventors have paid attention to the heat resistance of polyimide, and have been studying for its optical application. As a result, the fluorinated polyimide into which the fluorine substituent has been introduced is transparent in the near infrared region (Japanese Patent Laid-Open No. 3-725 / 1991).
No. 28), which proved to be excellent in moisture resistance. Further, it has been disclosed in JP-A-4-8734 that the refractive index can be easily changed by using the fluorinated polyimide as a copolymer and controlling the copolymerization ratio. Also,
A method for forming an optical waveguide using this fluorinated polyimide has been developed.
-235506. However, fluorinated polyimide directional couplers, or Y
There is no application example to a waveguide type optical device including a branch circuit.
Furthermore, since the thermo-optic effect of the fluorinated polyimide has not been studied, there is no application example utilizing the thermo-optic effect.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polymer waveguide type optical device having excellent heat resistance, moisture resistance, and light transmittance. To improve the performance.

[0006]

In summary, the present invention relates to a waveguide type optical device using fluorinated polyimide, and the waveguide type optical device of the first invention comprises a core and a core. One or both of the claddings is characterized by including a directional coupler formed of fluorinated polyimide. The waveguide type optical device of the second invention is
A Mach-Zehnder interferometer manufactured by combining two or more directional couplers according to the first invention is provided. Third
The waveguide type optical device according to the present invention is characterized in that, in the waveguide type optical device including the Y branch circuit, one or both of the core and the clad of the Y branch circuit are formed of fluorinated polyimide. A waveguide type optical device according to a fourth aspect is characterized in that the waveguide type optical device according to the first to third aspects has a thermo-optic phase shifter made of a resistor thin film for conducting electric heating. The waveguide optical device according to a fifth aspect of the present invention is the waveguide optical device according to the first to fourth aspects, wherein the 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) And a fluorinated polyimide synthesized from diamine and diamine, or a copolymer of this and another polyimide is used for one or both of the cladding and core materials. A waveguide type optical device according to a sixth aspect of the present invention is the waveguide type optical device according to any one of the first to fourth aspects, wherein 1,4-bis (3,4-
Forming a fluorinated polyimide synthesized from (dicarboxytrifluorophenoxy) tetrafluorobenzene dianhydride (10FEDA) and a diamine, or a copolymer of this and another polyimide as one or both of a cladding and a core material It is characterized by.

As a result of studying from the above viewpoint, the present inventors have found that the polyimide containing fluorine has the required processability for fabricating a waveguide-type optical device such as a directional coupler and the like. 1.3 μm and 1.55 μ wavelength
m, low heat loss in the near infrared region, excellent heat resistance and moisture resistance, and a thermo-optic constant showing the temperature dependence of the refractive index of -3 × 10
^The present invention was found to be larger than quartz or PMMA at ⁻⁴ / ° C. (FIG. 1), and the present invention was completed. FIG. 1 is a diagram showing the thermo-optic constant of the fluorinated polyimide. The horizontal axis represents temperature (° C.), and the vertical axis represents the refractive index.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The clad and core materials applicable to the present invention will be described. In order for the waveguide type optical device to exhibit stable performance, as described above, 1) the waveguide material must be transparent in the near infrared region, particularly, near the wavelength of 1.55 μm.
It is desired that the clad and core materials have low moisture absorption and that the refractive index has little dependence on the environment and humidity. Furthermore, in the case of a waveguide type optical device utilizing the thermo-optic effect, the thermo-optic constant and the heat resistance of the clad and core materials are also important. In the first to fourth inventions, a fluorinated polyimide produced from a fluorinated tetracarboxylic acid or a derivative thereof and a diamine, a fluorinated polyimide produced from a tetracarboxylic acid or a derivative thereof and a fluorinated diamine, or a fluorinated tetracarboxylic acid Alternatively, a fluorinated polyimide produced from a derivative thereof and a fluorinated diamine can be used. As these fluorinated polyimides, not only simple substances but also fluorinated polyimide copolymers, fluorinated polyimide mixtures, and those obtained by adding additives and the like as necessary can be used.

[0009] Examples of the tetracarboxylic acid or fluorinated tetracarboxylic acid and their derivatives such as acid anhydrides, acid chlorides and esterified compounds are as follows. Here, examples of tetracarboxylic acid or fluorinated tetracarboxylic acid will be given. (Trifluoromethyl) pyromellitic acid, di (trifluoromethyl) pyromellitic acid, di (heptafluoropropyl) pyromellitic acid, pentafluoroethylpyromellitic acid, bis {3,5-di (trifluoromethyl) phenoxy} Pyromellitic acid, 2,3,3 ', 4'-biphenyltetracarboxylic acid, 3,3', 4,4'-tetracarboxydiphenyl ether, 2,3,3 ', 4'-tetracarboxydiphenyl ether, 3,3 ', 4,4'-benzophenonetetracarboxylic acid, 2,3,6,7-tetracarboxynaphthalene, 1,4,5,7-tetracarboxynaphthalene, 1,4,5,6-tetracarboxynaphthalene, 3, 3 ′, 4,4′-tetracarboxydiphenylmethane, 3,3 ′, 4,4′-tetracarboxydiphenylsulfone, 2, -Bis (3,4-dicarboxyphenyl) propane, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane, 5,5′-bis (trifluoromethyl) -3,3 ′, 4 4'-tetracarboxybiphenyl, 2,2 ', 5,5'-tetrakis (trifluoromethyl) -3,3', 4,4'-tetracarboxybiphenyl, 5,5'-bis (trifluoromethyl)- 3,3 ′, 4,4′-tetracarboxydiphenyl ether, 5,5′-bis (trifluoromethyl) -3,3 ′, 4,4′-tetracarboxybenzophenone, bis {(trifluoromethyl) dicarboxyphenoxy {Benzene, bis} (trifluoromethyl)
Dicarboxyphenoxy｝ (trifluoromethyl) benzene, bis (dicarboxyphenoxy) (trifluoromethyl) benzene, bis (dicarboxyphenoxy) bis (trifluoromethyl) benzene, bis (dicarboxyphenoxy) tetrakis (trifluoromethyl) Benzene, 3,4,9,10-tetracarboxyperylene,
2,2-bis {4- (3,4-dicarboxyphenoxy) phenyl} propane, butanetetracarboxylic acid, cyclopentanetetracarboxylic acid, 2,2-bis {4-
(3,4-dicarboxyphenoxy) phenyl {hexafluoropropane, bis (trifluoromethyl) dicarboxyphenoxy} biphenyl, bis {(trifluoromethyl) dicarboxyphenoxy} bis (trifluoromethyl) biphenyl, bis} ( Trifluoromethyl)
Dicarboxyphenoxy diphenyl ether, bis (dicarboxyphenoxy) bis (trifluoromethyl) biphenyl, bis (3,4-dicarboxyphenyl) dimethylsilane, 1,3-bis (3,4-dicarboxyphenyl) tetramethyldi Siloxane, difluoropyromellitic acid, 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene,
1,4-bis (3,4-dicarboxytrifluorophenoxy) octafluorobiphenyl and the like.

[0010] Examples of the diamine or fluorinated diamine include the following. m-phenylenediamine, 2,4-diaminotoluene, 2,4-diaminoxylene, 2,4-diaminodulene, 4- (1H, 1
H, 11H-eicosafluoroundecanoxy) -1,
3-diaminobenzene, 4- (1H, 1H-perfluoro-1-butanoxy) -1,3-diaminobenzene,
-(1H, 1H-perfluoro-1-heptanoxy)-
1,3-diaminobenzene, 4- (1H, 1H-perfluoro-1-octanoxy) -1,3-diaminobenzene, 4-pentafluorophenoxy-1,3-diaminobenzene, 4- (2,3,5 , 6-tetrafluorophenoxy) -1,3-diaminobenzene, 4- (4-fluorophenoxy) -1,3-diaminobenzene, 4-
(1H, 1H, 2H, 2H-perfluoro-1-hexanoxy) -1,3-diaminobenzene, 4- (1H, 1
H, 2H, 2H-perfluoro-1-dodecanoxy)-
1,3-diaminobenzene, p-phenylenediamine,
2,5-diaminotoluene, 2,3,5,6-tetramethyl-p-phenylenediamine, 2,5-diaminobenzotrifluoride, bis (trifluoromethyl) phenylenediamine, diaminotetra (trifluoromethyl) benzene, Diamino (pentafluoroethyl) benzene, 2,5-diamino (perfluorohexyl) benzene, 2,5-diamino (perfluorobutyl) benzene, benzidine, 2,2′-dimethylbenzidine,
3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 2,2′-dimethoxybenzidine, 3,3 ′,
5,5′-tetramethylbenzidine, 3,3′-diacetylbenzidine, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl, octafluorobenzidine, 3,3′-bis (trifluoro Methyl)-
4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 2,2-
Bis (p-aminophenyl) propane, 3,3'-dimethyl-4,4'-diaminodiphenyl ether, 3,
3′-dimethyl-4,4′-diaminodiphenylmethane, 1,2-bis (anilino) ethane, 2,2-bis (p-aminophenyl) hexafluoropropane,
3-bis (anilino) hexafluoropropane, 1,4
-Bis (anilino) octafluorobutane, 1,5-bis (anilino) decafluoropentane, 1,7-bis (anilino) tetradecafluoroheptane, 2,2′-
Bis (trifluoromethyl) -4,4′-diaminodiphenyl ether, 3,3′-bis (trifluoromethyl) -4,4′-diaminodiphenyl ether, 3,
3 ', 5,5'-tetrakis (trifluoromethyl)-
4,4′-diaminodiphenyl ether, 3,3′-bis (trifluoromethyl) -4,4′-diaminobenzophenone, 4,4 ″ -diamino-p-terphenyl,
1,4-bis (p-aminophenyl) benzene, p-bis (4-amino-2-trifluoromethylphenoxy)
Benzene, bis (aminophenoxy) bis (trifluoromethyl) benzene, bis (aminophenoxy) tetrakis (trifluoromethyl) benzene, 4,4 ′ ″-
Diamino-p-quarterphenyl, 4,4′-bis (p-aminophenoxy) biphenyl, 2,2-bis {4- (p-aminophenoxy) phenyl} propane,
4,4'-bis (3-aminophenoxyphenyl) diphenylsulfone, 2,2-bis {4- (4-aminophenoxy) phenyl} hexafluoropropane, 2,2-
Bis {4- (3-aminophenoxy) phenyl} hexafluoropropane, 2,2-bis {4- (2-aminophenoxy) phenyl} hexafluoropropane, 2,2
-Bis {4- (4-aminophenoxy) -3,5-dimethylphenyl} hexafluoropropane, 2,2-bis {4- (4-aminophenoxy) -3,5-ditrifluoromethylphenyl} hexafluoropropane , 4,
4′-bis (4-amino-2-trifluoromethylphenoxy) biphenyl, 4,4′-bis (4-amino-3
-Trifluoromethylphenoxy) biphenyl, 4,
4'-bis (4-amino-2-trifluoromethylphenoxy) diphenylsulfone, 4,4'-bis (3-amino-5-trifluoromethylphenoxy) diphenylsulfone, 2,2-bis {4- (4 -Amino-3-trifluoromethylphenoxy) phenyl} hexafluoropropane, bis {(trifluoromethyl) aminophenoxy} biphenyl, bis [{(trifluoromethyl) aminophenoxy} phenyl] hexafluoropropane,
Diaminoanthraquinone, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, bis {2-[(aminophenoxy) phenyl] hexafluoroisopropyl} benzene, bis (2,3,5,6-tetrafluoro-4-amino Phenyl) ether, bis (2,3,5)
6-tetrafluoro-4-aminophenyl) sulfide, 1,3-bis (3-aminopropyl) tetramethyldisiloxane, 1,4-bis (3-aminopropyldimethylsilyl) benzene, bis (4-aminophenyl) Diethylsilane, 1,3-diaminotetrafluorobenzene, 1,4-diaminotetrafluorobenzene, 4,
4'-bis (tetrafluoroaminophenoxy) octafluorobiphenyl and the like.

In order to form a high-performance waveguide optical device, it is necessary to avoid polarization plane dependence of optical characteristics.
Therefore, in the fifth and sixth inventions, the difference between the refractive index (n _TE ) in the direction parallel to the substrate surface and the refractive index (n _TM ) in the direction perpendicular to the substrate surface (n _TM ) is given to the core and cladding material of the optical waveguide. Two types of polyimides having the same birefringence or two types of polyimide copolymers having the same birefringence are used. As a result, the difference in refractive index between TE-polarized light and TM-polarized light is almost the same, and the polarization plane dependence of the optical characteristics is eliminated. At this time, the refractive index difference between TE polarized light and TM polarized light can be freely controlled by changing the copolymerization ratio of the core and the clad material. In particular,
In the fifth invention, either or both of the cladding and the core material of the optical waveguide are made of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FD
A) and a fluorinated polyimide synthesized from a diamine or a copolymer thereof, and in the sixth invention, one or both of the cladding and the core material of the optical waveguide is 1,4-bis (3,4-dicarboxytrifluoro). (Phenoxy) limited to fluorinated polyimide synthesized from tetrafluorobenzene dianhydride (10FEDA) and diamine or a copolymer thereof. For example, as the two kinds of polyimides used as the clad and core materials of these inventions, 6FDA
And 2,2'-bis (trifluoromethyl) -4,4'-
Polyimide (6FDA / TFDB) synthesized from diaminobiphenyl (TFDB), 6FDA and 4,4'-
There is 6FDA / 4,4'-ODA synthesized from oxydianiline (4,4'-ODA). Furthermore, these copolymers can be used as clad and core materials by changing the copolymerization ratio. The two types of polyimides shown here and their copolymers have a copolymerization ratio (copolymerization ratio of 1: 0,
, And 0: 1). Combinations of such fluorinated polyimides or fluorinated polyimide copolymers are as shown in Tables 1 and 2 below.

[0012]

[Table 1]

[0013]

[Table 2]

Next, a general method for manufacturing the optical waveguide device of the present invention will be described. FIG. 2 is a diagram showing a process of manufacturing a directional coupler (Mach-Zehnder interferometer) using a fluorinated polyimide optical waveguide or a Y-branch circuit.
First, a lower cladding layer 2 is formed on a substrate 1. Next, a core layer 3 having a higher refractive index than the lower cladding layer 2 is formed on the lower cladding layer 2. Next, a directional coupler or Y is formed on the core layer 3 by photolithography.
The mask pattern 4 of the branch circuit is formed. The core layer 3 on which the mask pattern 4 is formed is etched by RIE to form a directional coupler or a core pattern 5 of a Y-branch circuit. After removing the mask, the upper cladding layer 6 is formed on the core pattern 5 of the directional coupler or the Y branch circuit. In this way,
A directional coupler (FIG. 3) using a fluorinated polyimide optical waveguide or a Y-branch circuit (FIG. 4) is formed. That is, FIG. 3 is a schematic diagram of the directional coupler, and FIG. 4 is a schematic diagram of the Y branch circuit. A directional coupler or a Y-branch circuit is one of the most important and basic components constituting a waveguide type optical device. For example, a directional coupler
A single component is used as an optical component that branches outgoing light at an arbitrary ratio, and the branching ratio can be controlled by changing the interaction length. In the present invention, the heat resistance of the fluorinated polyimide used as the waveguide material, moisture resistance, utilizing the excellent light loss characteristics, the direction of small changes in characteristics even when used for a long time under high temperature conditions and high temperature and high humidity conditions Sex coupler, or Y
The branch circuit can be easily manufactured, and the environmental resistance, economy, and versatility of the waveguide type optical device having the directional coupler or the Y branch circuit have been greatly improved.

The manufacturing process of the Mach-Zehnder interferometer using the fluorinated polyimide optical waveguide is basically the same as the manufacturing process of the directional coupler described with reference to FIG. A different mask pattern is used. In this way, a Mach-Zehnder interferometer (FIG. 5) made of fluorinated polyimide is formed. That is, FIG. 5 is a schematic diagram of a Mach-Zehnder interferometer. A Mach-Zehnder interferometer is a basic optical circuit that constitutes a waveguide type optical device, and can be used as various optical components in combination with a phase shifter. In the present invention, since a fluorinated polyimide having excellent heat resistance and moisture resistance is used as an optical waveguide material, a Mach-Zehnder interferometer that is resistant to environmental changes and has long-term stability can be easily formed. As a result, the environmental resistance, economy, and versatility of the waveguide optical device having the Mach-Zehnder interferometer have been greatly improved. Similarly, a Y-branch circuit using a fluorinated polyimide optical waveguide can be manufactured by the steps shown in FIG. First, a lower cladding layer 2 is formed on a substrate 1. Next, a core layer 3 having a higher refractive index than the lower cladding layer 2 is formed on the lower cladding layer 2. Next, a mask pattern 4 of a Y-branch circuit is formed on the core layer 3 by photolithography. The core layer 3 on which the mask pattern 4 is formed is etched by RIE to form a core pattern 5 of the Y branch circuit. After removing the mask, an upper clad layer 6 is formed on the core pattern 5 of the Y branch circuit. In this way,
Y-branch circuit using fluorinated polyimide optical waveguide (Fig. 4)
Is formed. The Y-branch circuit is one of the most important and basic elements constituting the waveguide type optical device. In the present invention, the fluorinated polyimide used as a waveguide material has excellent heat resistance, moisture resistance, and excellent light loss characteristics. The branch circuit can be easily manufactured, and the environment resistance, economy, and versatility of the waveguide type optical device having the Y branch circuit have been greatly improved.

FIG. 6 is a diagram showing a process of manufacturing a TO switch comprising a Mach-Zehnder interferometer formed using a fluorinated polyimide optical waveguide and a heating electrode formed of a resistor thin film. A metal film 7 is formed on the upper cladding layer 6 of the Mach-Zehnder interferometer manufactured in the same manner as in FIG.
Next, after forming a mask pattern 8 of a heating electrode (thermo-optical phase shifter) on the metal film 7 by a photolithographic method, the metal film 7 is etched to form a heating electrode 9. By such a method, a Mach-Zehnder TO switch or a Y-branch TO switch using a fluorinated polyimide optical waveguide is formed. In the present invention, since a fluorinated polyimide having excellent heat resistance and moisture resistance is used for the optical waveguide material, it is excellent in environmental resistance and long-term stability, and switches at lower power and higher speed than a quartz TO switch. A fluorinated polyimide TO switch can now be easily formed. As a result, the environmental resistance, economy, and versatility of the polymer TO switch were significantly improved. In the present invention, any substrate material can be used, but the switching speed is faster when a substrate material having a high thermal conductivity is used. Materials for forming the resistor thin film include Ti, Cr, Al, gold, silver, copper, platinum, tin oxide, indium oxide, indium tin oxide,
And mixtures thereof. Further, a stacked film of these thin films may be used.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically with reference to the drawings, but the present invention is not limited to these embodiments. In this embodiment, silicon is used for the substrate and Ti is used for the metal film, but it goes without saying that other materials may be used.

Example 1 (6FDA / TFDB) and (6FDA / TFDB) shown in Table 1
FIG. 2 shows a process for producing a directional coupler using a copolymer 1 (4,4′-ODA) (copolymerization ratio includes 1: 0).
This will be described with reference to FIG. First, (6FDA / TFDB):
Dimethylacetamide (DMAc) 15w of fluorinated polyamic acid, which is a precursor of a fluorinated polyimide copolymer having a copolymerization ratio of (6FDA / 4,4'-ODA) of 7: 3
After spin-coating a t% solution on the silicon substrate 1, the substrate is heated at 380 ° C. for 1 hour in an oven to perform imidization, and the lower cladding layer 2 (the refractive index is n _TE at a wavelength of 1.3 μm: n _TE : 1.
534, n _TM : 1.527, n _TE at 1.55 μm:
1.533, n _™ : 1.524). Next, on the lower cladding layer 2, (6FDA / TFDB) :( 6FDA / TFDB):
A 15 wt% solution of fluorinated polyamic acid, which is a precursor of a fluorinated polyimide copolymer having a copolymerization ratio of DA: 4,4′-ODA) of 6: 4, was heated to a thickness of 8 μm after imidization by DMAc. Spin coating was performed. afterwards,
The core layer 3 (refractive index for one hour heating was imidized at 380 ° C. in an oven, at a wavelength of 1.3 .mu.m n _TE: 1.53
8, n _TM : 1.531, 1.55 μm n _TE : 1.5
38, n _™ : 1.530). Next, the core layer 3
After spin-coating the photoresist on the top, the Cr mask pattern of the directional coupler was transferred to the resist by photolithography. Next, the mask pattern 4 of the directional coupler was formed on the core layer 3 by developing the photoresist. The core layer 3 on which the mask pattern 4 was formed was etched using RIE to form a core pattern 5 of a directional coupler. Finally, on the core pattern 5 of the directional coupler, the same as the lower cladding layer 2 (6FDA / TFDB): (6FDA / 4,4′-O)
DA) is a fluorinated polyamic acid DMAc 1 which is a precursor of a fluorinated polyimide copolymer having a copolymerization ratio of 7: 3.
After spin coating the 5 wt% solution, 380
By heating at 1 ° C. for 1 hour to perform imidization, an upper clad layer 6 having the same refractive index as the lower clad layer 2 was formed. According to such a method, when the wavelengths are 1.3 μm and 1.55 μm, the refractive index difference Δ between the core and the clad becomes TE polarized light, TM
When polarized, a directional coupler (FIG. 3) was formed by a fluorinated polyimide optical waveguide, both having the same value as 0.3%. This directional coupler has a coupling ratio of 97% or more for both TE-polarized light and TM-polarized light at a wavelength of 1.3 μm, insertion loss including connection loss of 2 dB, and excess loss of 3 dB coupler of 0.2 dB.
B and excellent optical characteristics. Furthermore, a wavelength of 1.55 μm
Also exhibited excellent optical characteristics such as a coupling ratio of 97% or more for both TE-polarized light and TM-polarized light, and an insertion loss including connection loss of 2 dB and an excess loss of a 3 dB coupler of 0.2 dB. The produced directional coupler has the same characteristics as the initial one after heat treatment at 100 ° C and after immersion in water, high temperature and high humidity (85 ° C, 85RH) atmosphere or acetone, and has environmental resistance and long-term stability It had excellent properties. As a result, the environment resistance, economy, and versatility of the waveguide type optical device having the directional coupler have been greatly improved.

Example 2 The compound was synthesized from 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene dianhydride (10FEDA) and tetrafluoro-m-phenylenediamine (4FMPD) shown in Table 1. Fluorinated polyimide (10FEDA / 4FMPD) and (6FDA / 4,4 '
-ODA) was used to form a directional coupler using a copolymer 2 having a copolymerization ratio of 1: 0. Lower, fluorinated polyimide (refractive index made of a material of the upper cladding (10FEDA / 4FMPD), when the wavelength of _{1.3μm n TE: 1.527, n TM} : 1.519,1.55μm when n _TE: 1.527, n _TM: using DMAc15wt% solution of a polyamic acid which is a precursor 1.518), also as a core material and (10FEDA / 4FMPD) (6
FDA / 4,4'-ODA) in copolymerization ratio of 8: 2 of the fluorinated polyimide copolymer (refractive index at a wavelength of _{1.3μm n TE: 1.535, n TM} : 1.527,1 .55 μm
In this case, the same operation as in Example 1 was performed using a 15 wt% solution of a polyamic acid as a precursor of n _TE : 1.535 and n _TM : 1.526) to perform directional coupling by a fluorinated polyimide optical waveguide. A vessel was formed. This directional coupler has a coupling ratio of 97% or more for both TE-polarized light and TM-polarized light at a wavelength of 1.3 μm, an insertion loss of 2 dB including a connection loss, and 3 dB.
It exhibited excellent optical characteristics with an excess loss of 0.2 dB of the dB coupler. Further, even at a wavelength of 1.55 μm, the coupling ratio is 97% or more for both TE-polarized light and TM-polarized light, insertion loss including connection loss 2 dB, excess loss of 3 dB coupler 0.2 d.
B and excellent optical characteristics. The manufactured directional coupler was heat-treated at 100 ° C. and in water, at high temperature and high humidity (85 ° C., 85
(RH) Even after immersion in an atmosphere or acetone, it had the same characteristics as the initial stage, and was excellent in environmental resistance and long-term stability. As a result, the environment resistance, economy, and versatility of the waveguide type optical device having the directional coupler have been greatly improved.

Examples 3 to 38 Using a polyamic acid solution which is a precursor of the copolymers 3 to 38 (copolymerization ratio includes 1: 0) shown in Tables 1 and 2, By performing the same operation as in Example 1, a directional coupler using a fluorinated polyimide optical waveguide was formed.
In these directional couplers, no change in optical characteristics due to TE polarized light and TM polarized light was observed. Wavelength 1.
The optical characteristics at 3 μm and 1.55 μm are summarized in Tables 3 and 4.

[0021]

[Table 3]

[0022]

[Table 4]

Explanation of symbols in Tables 1 to 4 6FDA: 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride 10FEDA: 1,4-bis (3,4-dicarboxytrifluoro) Phenoxy) tetrafluorobenzene dianhydride ODPA: 4,4′-oxydiphthalic anhydride BTDA: 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride TFDB: 2,2′-bis (trifluoromethyl ) -4,4′-Diaminobiphenyl 4FMPD: tetrafluoro-m-phenylenediamine 8FODA: bis (2,3,5,6-tetrafluoro-4-aminophenyl) ether 4,4′-ODA: 4,4 ′ -Oxydianiline 3,4'-ODA: 3,4'-oxydianiline 2,4'-ODA: 2,4'-oxydianiline 3FDAM: 1,1-bis (4-aminophenyl)
-1-phenyl-2,2,2-trifluoroethane 3FEDAM: [1,1-bis {4- (4-aminophenoxy) phenyl} -1-phenyl-2,2,2-trifluoroethane] 3, 3′-DDSO2: 3,3′-diaminodiphenylsulfone 4,4′-DDSO2: 4,4′-diaminodiphenylsulfone 4,4′-MDA: 4,4′-methylenedianiline 4-BDAF: 2,2 -Bis [4- (4-aminophenoxy) phenyl] hexafluoropropane APHF33: 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane 4,4'-6F: 2,2-bis (4 -Aminophenyl) hexafluoropropane

Embodiment 39 The same operation was performed by changing the Cr mask pattern of the directional coupler in the first embodiment to the Mach-Zehnder Cr mask pattern, and performing the same operation as (6FDA / TFDB) and (6FDA /
A Mach-Zehnder interferometer (FIG. 4) using a fluorinated polyimide copolymer composed of (4,4′-ODA) was formed. The fabricated Mach-Zehnder interferometer has the same properties as the initial state after heat treatment at 100 ° C and after immersion in water, high-temperature and high-humidity (85 ° C, 85RH) or acetone, and has environmental resistance and long-term stability It had excellent properties. As a result, the environment resistance, economy, and versatility of the waveguide optical device having the Mach-Zehnder interferometer have been greatly improved.

Embodiment 40 FIG. 6 is a diagram showing a process of manufacturing a Mach-Zehnder TO switch. A Ti metal film 7 serving as a heating electrode (thermo-optical phase shifter) was formed on the upper cladding layer 6 of the Mach-Zehnder interferometer manufactured in the same manner as in Example 39 by vacuum evaporation. After a photoresist was spin-coated on the Ti metal film 7, the mask pattern 8 of the electrode was transferred to the resist by a photolithographic method. Finally, the electrode 9 was formed by etching Ti using the photoresist as a mask. As a result of measuring the characteristics of the Mach-Ender TO switch using the fluorinated polyimide optical waveguide schematically shown in FIG. 7 formed by such a method, the switching time was 4 mS and the switching power was 1
It was 0 mW. (6FDA / TFDB) and (6FDA
/ 4,4'-ODA), a thermo-optical constant [10 times or more larger than that of quartz contained in the fluorinated polyimide copolymer [−
3 × 10 ⁻⁴ / ° C. (FIG. 1)], the switching power was 1/50 or less that of quartz, and it was found that the manufactured fluorinated polyimide TO switch operates as a low-power, high-speed optical switch. The manufactured TO switch was heat-treated at 100 ° C. and in water, high temperature and high humidity (85 ° C., 8
5RH) Even after immersion in an atmosphere or acetone, it had the same characteristics as the initial stage, and was excellent in environmental resistance and long-term stability. As a result, the environmental resistance of the polymer TO switch,
Economic efficiency and versatility were greatly improved.

Example 41 (6FDA / TFDB) and (6FDA / TFDB) shown in Table 1
The process of manufacturing a Y-branch circuit using the copolymer 1 (4,4′-ODA) (copolymerization ratio includes 1: 0) will be described with reference to FIG. First, (6FDA / TFDB):
A 15 wt% solution of a fluorinated polyamic acid, which is a precursor of a fluorinated polyimide copolymer having a copolymerization ratio of (6FDA / 4,4′-ODA) of 7: 3, in DMAc 15 wt% was applied to a silicon substrate 1.
Was spin-coated on the lower cladding layer 2 (refractive index for one hour heating was imidized at 380 ° C. in an oven, at a wavelength of _{1.3μm n TE: 1.534, n TM} : 1.52
7, at 1.55 μm n _TE : 1.533, n _TM : 1.5
24) was formed. Next, on the lower cladding layer 2, (6
FDA / TFDB): (6FDA / 4,4'-ODA)
15 wt% of fluorinated polyamic acid which is a precursor of a fluorinated polyimide copolymer having a copolymerization ratio of 6: 4
The solution was spin-coated so that the film thickness after heat imidization became 8 μm. Thereafter, the mixture is heated in an oven at 380 ° C. for 1 hour to imidize the core layer 3 (the refractive index is wavelength 1.
When 3 μm, n _TE : 1.538, n _TM : 1.531, 1.
At 55 μm, n _TE : 1.538, n _TM : 1.530) were formed. Next, after a photoresist was spin-coated on the core layer 3, a Cr mask pattern of the Y branch circuit was transferred to the resist by a photolithographic method. next,
By developing the photoresist, a mask pattern 4 of the Y-branch circuit was formed on the core layer 3. The core layer 3 on which the mask pattern 4 was formed was etched by RIE to form a core pattern 5 of a Y branch circuit.

Finally, on the core pattern 5 of the Y branch circuit, the same as the lower cladding layer 2 (6FDA / TFDB):
After spin-coating a 15 wt% solution of fluorinated polyamic acid, which is a precursor of a fluorinated polyimide copolymer having a copolymerization ratio of (6FDA / 4,4′-ODA) of 6: 4, in DMAc at 380 ° C. The mixture was heated for a period of time to perform imidization, thereby forming an upper clad layer 6 having the same refractive index as the lower clad layer 2. With this method, the wavelength 1.3 is obtained.
In the case of μm and 1.55 μm, a Y-branch circuit (FIG. 4) using a fluorinated polyimide optical waveguide is formed in which the refractive index difference コ ア between the core and the clad is the same as 0.3% for both TE polarized light and TM polarized light. Was done. This Y branch circuit has a wavelength of 1.3 μm.
In both cases, the insertion loss was 2 dB or less for both the TE-polarized light and the TM-polarized light, and the polarization dependence of the light loss (difference between the TE-polarized light and the TM-polarized light: PDL) also showed excellent optical characteristics of 0.2 dB. Further, even at a wavelength of 1.55 μm, both the TE-polarized light and the TM-polarized light exhibited excellent optical characteristics of an insertion loss of 2 dB or less and a PDL of 0.2 dB. The manufactured Y branch circuit is 100
After heat treatment, and in water, high temperature and high humidity (85 ° C, 85RH)
Even after being immersed in an atmosphere or acetone, it had the same characteristics as the initial stage, and had excellent environmental resistance and long-term stability. As a result, environment resistance, economic efficiency, and versatility of the waveguide type optical device having the Y branch circuit have been greatly improved.

Example 42 Synthesis was made from 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene dianhydride (10FEDA) and tetrafluoro-m-phenylenediamine (4FMPD) shown in Table 1. Fluorinated polyimide (10FEDA / 4FMPD) and (6FDA / 4,4 '
-ODA), a Y-branch circuit was formed using a copolymer 2 (copolymerization ratio including 1: 0). Fluorinated polyimide made of (10FEDA / 4FMPD) as a material for the lower and upper claddings (the refractive index is n at a wavelength of 1.3 μm)
_TE: 1.527, n _{TM: 1.519,1.55μm} when n _TE: 1.527, n _TM: using DMAc15wt% solution of a polyamic acid which is a precursor 1.518), also as a core material Are (10FEDA / 4FMPD) and (6F
DA: 4,4′-ODA) copolymer having a copolymerization ratio of 8: 2 (refractive index: n _TE : 1.535 at a wavelength of 1.3 μm, n _TM : 1.527, 1 when _{.55μm n TE: 1.535, n TM} : 1.526) of a precursor with DMAc15wt% solution of polyamic acid, Y branch due fluorinated polyimide optical waveguide by the same operation as in example 1 A circuit was formed. This Y branch circuit has an insertion loss of 2 for both TE polarized light and TM polarized light at a wavelength of 1.3 μm.
Excellent optical characteristics of PDL of 0.2 dB or less were exhibited. Further, even at a wavelength of 1.55 μm, the insertion loss of both TE-polarized light and TM-polarized light is 2 dB or less, and PDL is 0.2 dB.
And excellent optical properties. The fabricated Y branch circuit is 10
After heat treatment at 0 ° C and in water, high temperature and high humidity (85 ° C, 85R
H) Even after being immersed in an atmosphere or acetone, it had the same characteristics as the initial stage, and was excellent in environmental resistance and long-term stability. As a result, environment resistance, economic efficiency, and versatility of the waveguide type optical device having the Y branch circuit have been greatly improved.

Examples 43 to 78 Using a polyamic acid solution as a precursor of the copolymers 3 to 38 (copolymerization ratio including 1: 0) shown in Tables 1 and 2, By performing the same operation as in Example 1, a Y-branch circuit using a fluorinated polyimide optical waveguide was formed. In these Y branch circuits, no change in optical characteristics due to TE polarized light and TM polarized light was observed. 1.3μ wavelength
Tables 5 and 6 show the optical characteristics at m and 1.55 μm. The meanings of the symbols described in Tables 5 and 6 are as follows:
This is the same as the description of the symbols in Tables 1 to 4 described above.

[0030]

[Table 5]

[0031]

[Table 6]

Embodiment 79 FIG. 5 can be applied to a manufacturing process of a Y-branch type TO switch. A Ti metal film 7 serving as a heating electrode (thermo-optic phase shifter) was formed on the upper cladding layer 6 of the Y branch circuit manufactured in the same manner as in Example 41 by vacuum evaporation. This Ti
After spin coating a photoresist on the metal film 7, the mask pattern 8 of the electrode was transferred to the resist by photolithography. Finally, the electrode 9 was formed by etching Ti using the photoresist as a mask. As a result of measuring the characteristics of the Y-branch TO switch (FIG. 8) using the fluorinated polyimide optical waveguide formed by such a method, the switching time was 4 mS and the switching power was 10 mW. (6FDA / TFDB) and (6FDA
The switching power is quartz due to the effect of a thermo-optical constant [−3 × 10 ⁻⁴ / ° C. (FIG. 1)] which is at least 10 times larger than that of quartz contained in a fluorinated polyimide copolymer composed of DA / 4,4′-ODA). 1/50 or less, and it was found that the manufactured fluorinated polyimide TO switch operates as a low-power, high-speed optical switch. Further, the manufactured TO switch was heat-treated at 100 ° C. and in water, high temperature and high humidity (85 ° C.).
(° C., 85 RH) Even after immersion in an atmosphere or acetone, it had the same properties as the initial stage, and was excellent in environmental resistance and long-term stability. As a result, the environmental resistance, economy, and versatility of the polymer TO switch were significantly improved.

[0033]

According to the present invention, a polymer waveguide type excellent in heat resistance, moisture resistance and light loss characteristics due to the heat resistance, moisture resistance and high light transmission characteristics of the fluorinated polyimide used as the waveguide material. An optical device can be provided. As a result, a waveguide type optical device which is excellent in economy and versatility can be manufactured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a thermo-optical constant of a fluorinated polyimide.

FIG. 2 is a diagram illustrating a process of manufacturing a directional coupler (Mach-Zehnder interferometer) or a Y-branch circuit using fluorinated polyimide.

FIG. 3 is a schematic diagram of a directional coupler.

FIG. 4 is a schematic diagram of a Y branch circuit.

FIG. 5 is a schematic diagram of a Mach-Zehnder interferometer.

FIG. 6 is a diagram showing a manufacturing process of a TO switch using fluorinated polyimide.

FIG. 7: Directional coupler type TO using fluorinated polyimide
It is a schematic diagram of a switch.

FIG. 8 is a schematic diagram of a Y-branch TO switch made of fluorinated polyimide.

[Explanation of symbols]

1: substrate, 2: lower clad layer, 3: core layer, 4: mask pattern, 5: core pattern, 6: upper clad layer,
7: metal film, 8: mask pattern of electrode, 9: electrode

 ──────────────────────────────────────────────────の Continuing on the front page (72) The inventor Shigekuni Sasaki 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (6)

[Claims] 1. A waveguide optical device including a directional coupler, wherein one or both of a core and a clad of the directional coupler are formed of fluorinated polyimide. device. 2. The waveguide type optical device according to claim 1, further comprising a Mach-Zehnder interferometer manufactured by combining two or more directional couplers. 3. A waveguide optical device including a Y-branch circuit, wherein one or both of a core and a clad of the Y-branch circuit are formed of fluorinated polyimide. 4. A thermo-optical phase shifter comprising a resistor thin film for conducting electric heating.
The waveguide type optical device according to any one of claims 1 to 3. 5. The waveguide type optical device according to claim 1, wherein one or both of the core and the clad of the waveguide type optical device are 2,2-bis (3, The waveguide-type optical device according to any one of claims 1 to 4, further comprising a fluorinated polyimide obtained by reacting 4-dicarboxyphenyl) hexafluoropropane dianhydride with a diamine. 6. The waveguide type optical device according to claim 1, wherein one or both of a core and a clad of the waveguide type optical device are 1,4-bis (3,4). The waveguide type light according to any one of claims 1 to 4, comprising a fluorinated polyimide obtained by reacting 4-dicarboxytrifluorophenoxy) tetrafluorobenzene dianhydride with a diamine. device.