WO2018168783A1

WO2018168783A1 - Polymer optical waveguide

Info

Publication number: WO2018168783A1
Application number: PCT/JP2018/009533
Authority: WO
Inventors: 健太小林; 盛輝大原
Original assignee: Ａｇｃ株式会社
Priority date: 2017-03-15
Filing date: 2018-03-12
Publication date: 2018-09-20
Also published as: TW201837078A; JPWO2018168783A1; JP7036108B2

Abstract

The present invention relates to a polymer optical waveguide which comprises a core and a cladding that has a lower refractive index than the core, and which is characterized in that: the polymer optical waveguide has a sheet form; if the thickness direction of the sheet form is taken as the core height and a direction perpendicular to the thickness direction is taken as the core width in a cross-section of the core in a direction perpendicular to the direction of propagation of light, the core height is 0.5-10 μm and the core width is 0.5-15 μm; and the depth of a recess that is present in the core upper surface and/or the core lateral surface of the cross-section of the core is 0.33 μm or less.

Description

Polymer optical waveguide

The present invention relates to a polymer optical waveguide.

With the miniaturization of devices and the speeding up of communication in the field of communication devices and the like, attention has been paid to the use of polymer optical waveguides for signal transmission (Patent Document 1).
The polymer optical waveguide can pass a large volume of signal, and can realize noiseless, space saving, and ease of assembly.

Japanese Unexamined Patent Publication No. 2002-2298

An object of the present invention is to provide a polymer optical waveguide that can reduce propagation loss.

In order to achieve the above object, the present invention is a polymer optical waveguide having a core and a clad having a refractive index lower than that of the core,
The polymer optical waveguide has a sheet shape, and in the core cross-sectional shape perpendicular to the light propagation direction of the core, when the thickness direction of the sheet shape is the core height and the direction perpendicular to the thickness direction is the core width The core height is 1.0-10 μm, the core width is 1.0-15 μm,
Provided is a polymer optical waveguide characterized in that the depth of a dent existing on the upper surface and / or the side surface of the core in the core cross-sectional shape is 0.33 μm or less.

The polymer optical waveguide of the present invention has a propagation loss ratio X / Y of 0.2 to 2 obtained by dividing the propagation loss value X [dB / cm] at a wavelength of 1550 nm by the propagation loss value Y [dB / cm] at a wavelength of 1310 nm. Preferably there is.

In the polymer optical waveguide of the present invention, the core is obtained by curing a composition containing a fluorinated polyarylene prepolymer (A) having a crosslinkable functional group, and the clad is the fluorinated polyarylene prepolymer. (A) It is preferable that the composition (B) containing a compound having a crosslinkable functional group having a lower refractive index is cured.

In the polymer optical waveguide of the present invention, the composition (B) comprises the fluorine-containing polyarylene prepolymer (A) and a compound (C) having a crosslinkable functional group and having a molecular weight of 140 to 5000 and having no fluorine atom. Are preferably included.

In the polymer optical waveguide of the present invention, the fluorine-containing polyarylene prepolymer (A) preferably has an absorbance at a wavelength of 365 nm at a polymer thickness of 10 mm and a polymer concentration of 100 wt% of 7.5 or less.

The polymer optical waveguide of the present invention is preferably a single mode polymer optical waveguide.

The polymer optical waveguide of the present invention preferably has a coupling portion where at least a part of the core is exposed on one end side.

The present invention also provides a composite optical waveguide having the polymer optical waveguide of the present invention and a connector that accommodates the optical waveguide portion of the polymer optical waveguide.

The polymer optical waveguide of the present invention can reduce single-mode propagation loss.

FIG. 1 is a perspective view showing one structural example of the polymer optical waveguide of the present invention. FIG. 2 is a perspective view showing an example of a usage pattern of the polymer optical waveguide of FIG. FIG. 3 is a side view of FIG. FIG. 4 is a perspective view showing an example of another usage pattern of the polymer optical waveguide of the present invention. FIG. 5 is a side view of FIG. FIG. 6 is a cross-sectional view of the polymer optical waveguide taken along line AA in FIG. FIG. 7 is a diagram showing another example of the core cross-sectional shape. FIG. 8 is a diagram showing still another example of the core cross-sectional shape. FIG. 9 is a graph showing the absorbance of the prepolymer A used in the core material in Examples 1 and 4 near a wavelength of 400 nm. FIG. 10 is a plan view of the polymer optical waveguides of Examples 1 to 4. FIG. 11 is a diagram showing a core cross-sectional shape of Example 1. FIG. 12 is a diagram showing the core cross-sectional shape of Example 2. FIG. 13 is a diagram showing the core cross-sectional shape of Example 3. FIG. 14 is a diagram showing the core cross-sectional shape of Example 4.

The present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view showing one structural example of the polymer optical waveguide of the present invention.
A polymer optical waveguide 10 shown in FIG. 1 has a core 20 and a clad 30 having a refractive index lower than that of the core 20. The clad 30 includes an under clad 31 disposed below the core 20 and an over clad 32 disposed above the core 20.
On one end side of the polymer optical waveguide 10, there is provided a core exposed portion 40 where the over clad 32 is not present and the core 20 is exposed.

The polymer optical waveguide 10 has a flat sheet shape and is used as an optical interconnection or an optical waveguide device. Examples of the optical interconnection include an intra-chip optical interconnection, an inter-chip optical interconnection, an intra-board optical interconnection (substrate with built-in optical circuit), and an intra-casing optical interconnection (optical backplane).

FIG. 2 is a perspective view showing an example of a usage pattern of the polymer optical waveguide 10 of FIG. 1, and FIG. 3 is a side view of FIG. However, the polymer optical waveguide 10 is turned upside down, and the core exposed portion 40 is located below.
2 and 3, the polymer optical waveguide 10 is adiabatically coupled to the silicon optical waveguide 100 through a core exposed portion provided on one end side. The other end side of the polymer optical waveguide 10 is butt-coupled with the single-mode optical fiber 200 (face-to-face coupling).

FIG. 4 is a perspective view showing another example of usage of the polymer optical waveguide of the present invention, and FIG. 5 is a side view of FIG. 4 and 5, a core exposed portion 42 is provided on one end side of the polymer optical waveguide 12, and the polymer optical waveguide 12 and the silicon optical waveguide 100 are adiabatically coupled by the core exposed portion 42. The point is the same as in FIGS.
In the polymer optical waveguide 10 shown in FIG. 1, the number of the cores 20 is one for the clad 30, whereas in the polymer optical waveguide 12 shown in FIG. 4, a plurality of cores 22 are arrayed along one direction. A bending region is provided to widen the interval between the cores 22.
4 and 5, the other end of the polymer optical waveguide 12 is accommodated in a connector 300 for butt coupling (facing coupling) with a single mode optical fiber or the like.
As shown in FIGS. 4 and 5, a structure having the polymer optical waveguide 12 and the connector 300 that accommodates the optical waveguide portion of the polymer optical waveguide 12 is referred to as a composite optical waveguide in this specification.

The structure at both ends of the polymer optical waveguide can be appropriately selected according to the coupling method when the polymer optical waveguide is used. As shown in FIGS. 2 to 5, when the coupling method on one end side is an adiabatic coupling and the coupling method on the other end side is a butt coupling (face-to-face coupling), a core is placed on one end side of the polymer optical waveguide. An exposed part is provided. When the coupling method at both ends is an adiabatic coupling, core exposed portions are provided at both ends of the polymer optical waveguide. When the coupling method at both ends is a butt coupling (facing coupling), the core exposed portion is not provided in the polymer optical waveguide.

The core in the polymer optical waveguide may have various structures (couplers, directional couplers, pitch changers, TO switches, etc.) according to the wiring pattern.

FIG. 6 is a cross-sectional view of the polymer optical waveguide cut along line AA in FIG. 1, and is a cross-sectional view of the core 20 in the direction perpendicular to the light propagation direction. Hereinafter, in this specification, the cross-sectional shape of the polymer optical waveguide or the cross-sectional shape of the core or the clad constituting the polymer optical waveguide means the cross-sectional shape in the direction perpendicular to the light propagation direction of the core.
In FIG. 6, the cross-sectional shape of the core 20 is a shape having a recess on the rectangular upper surface. However, in the polymer optical waveguide of the present invention, the cross-sectional shape of the core is not limited to this. For example, it may be a trapezoid, a circle, an ellipse, or a shape having a dent in a part of a polygon that is a pentagon or more. When the cross-sectional shape of the core is a polygon, the corners may be rounded.

In the cross-sectional shape of the core 20 shown in FIG. 6, the thickness t direction of the sheet shape formed by the polymer optical waveguide 10 is the core height, and the direction perpendicular to the thickness direction (that is, the width w of the sheet shape formed by the polymer optical waveguide 10). (Direction) is the core width, the core height is 1.0 to 10 μm, and the core width is 1.0 to 15 μm. When the core height and the core width are within the above ranges, propagation loss at a wavelength of 1310 nm and a wavelength of 1550 nm, which are typical as a single mode band, is suppressed. The core height is preferably 1 to 9 μm, more preferably 1 to 7 μm, further preferably 1 to 5 μm, and particularly preferably 1 to 3 μm. The core width is preferably 1 to 10 μm, and more preferably 1 to 9.5 μm.
The core width and core height can be specified using a white light interferometer, an optical microscope, a laser microscope, and a scanning electron microscope (SEM). In the case of a core exposed part, it can be specified by directly observing the cross-sectional shape of the core. In the case of a polymer optical waveguide without a core exposed part, the polymer optical waveguide is cut and the cross-sectional shape of the core is observed. Can be specified.

The polymer optical waveguide of the present invention may have portions with different core heights as long as the above range is satisfied. For example, the core height may be different between one end and the other end of the polymer optical waveguide. Further, the core height may be different between both ends of the polymer optical waveguide and the intermediate portion in the light propagation direction of the core. Further, the core height may be different between the exposed core portion of the polymer optical waveguide and the other portion.

Further, the polymer optical waveguide of the present invention may have a portion having a different core width as long as the above range is satisfied. For example, the core width may be different between one end and the other end of the polymer optical waveguide. Further, the core width may be different between both ends of the polymer optical waveguide and the intermediate portion in the light propagation direction of the core. In addition, the core width may be different between the exposed core portion of the polymer optical waveguide and the other portions.

Further, in the case of a polymer optical waveguide in which a plurality of cores are arranged in parallel with respect to the clad, the core height and the core width must satisfy the above ranges for all of the plurality of cores. However, not all cores are used for the purpose of signal propagation, and there may be a core for positioning when connecting polymer optical waveguides. About the core provided for such a purpose, core height and core width may not satisfy | fill the said range.

The core 20 cross-sectional shape shown in FIG. 6 has a dent 60 on its upper surface. As will be described later, there are various methods for producing the polymer optical waveguide, but in any case, a dent is generated on the upper surface and / or the side surface of the core cross-sectional shape.
It has been conventionally considered that the recess of about 1 μm existing on the upper surface and / or the side surface in the core cross-sectional shape does not cause propagation loss in the polymer optical waveguide.
However, as a result of intensive studies by the inventors of the present application, it is possible that the depressions present on the upper surface and / or the side surface in the cross-sectional shape of the core can cause propagation loss at 1310 nm and 1550 nm, which are typical wavelength bands in the single mode, It has also been found that if there is a recess having a specific depth or more, significant propagation loss occurs at 1310 nm and 1550 nm, which are typical wavelength bands in the single mode.

In the polymer optical waveguide of the present invention, the depth of the dent present on the upper surface and / or the side surface of the core in the core cross-sectional shape is 0.33 μm or less. That is, when a dent exists on the upper surface of the core, the depth of the dent is 0.33 μm or less. When a dent exists on the side surface of the core, the depth of the dent is 0.33 μm or less. When there are dents on the core upper surface and the core side surface, the depths of these dents are each 0.33 μm or less.
If the depth of the dent present on the upper surface and / or the side surface of the core is 0.33 μm or less, the propagation loss is reduced at 1310 nm and 1550 nm, which are typical wavelength bands in the single mode.
In the present specification, the case where there is a dent on the upper surface of the core refers to the case where there are at least two convex portions on the upper surface of the core and there are concave portions between the convex portions.
FIG. 7 shows another configuration example in which the recess 60 is present on the upper surface of the core.
The depth of the dent present on the upper surface of the core can be obtained by the following procedure.
When a tangent line is drawn between two adjacent convex portions existing on the core upper surface, the maximum height difference in the core thickness direction between the tangent line and the concave portion located between the two convex portions exists on the core upper surface. The depth of the dent to be made.

In this specification, the case where there is a dent on the core side surface means that when a tangent line is drawn so as to connect two protruding points on the side surface, a part of the core side surface is located inside the tangential profile. Point to.
FIG. 8 shows an example of a configuration in which a dent exists on the side surface of the core.
The depth of the dent existing on the side surface of the core can be obtained by the following procedure.
The maximum value of the distance between the tangential profile defined above and the core side surface is defined as the depth of the recess existing on the core side surface.

The depth of the dent existing on the upper surface and / or the side surface of the core can be specified by observing the cross-sectional shape of the core in the procedure described above.
In the examples described later, the cross-sectional shape of the core is observed only at one point in the light propagation direction of the polymer optical waveguide. However, the depression on the upper surface of the core and / or the side surface of the core occurs when the polymer optical waveguide is manufactured. Therefore, when there is a recess in the core upper surface and / or the core side surface at one place in the light propagation direction of the polymer optical waveguide, the core upper surface and / or the core side surface also in other portions of the polymer optical waveguide. There is a high possibility that a recess having substantially the same depth exists.

In the polymer optical waveguide of the present invention, the depth of the dent present on the upper surface and / or the side surface of the core in the cross-sectional shape of the core is preferably 0.30 μm or less, more preferably 0.25 μm or less. It is particularly preferably 15 μm or less.

In the case of a polymer optical waveguide in which a plurality of cores are arranged in parallel to the clad, it is required that the depth of the recesses existing on the top surface and / or the side surface of the core is 0.33 μm or less. However, not all cores are used for the purpose of signal propagation, and there may be a core for positioning when connecting polymer optical waveguides. About the core provided for such a purpose, the depth of the dent which exists in a core upper surface and / or a core side surface does not need to be 0.33 micrometer or less.

As described above, according to the polymer optical waveguide of the present invention, propagation loss is reduced at 1310 nm and 1550 nm, which are typical wavelength bands in the single mode.
The polymer optical waveguide of the present invention has a propagation loss ratio X / Y of 0.2 to 2 obtained by dividing the propagation loss value X [dB / cm] at a wavelength of 1550 nm by the propagation loss value Y [dB / cm] at a wavelength of 1310 nm. Preferably there is. If the transmission loss value X / Y satisfies the above range, the design freedom of the polymer optical waveguide is increased. Further, the productivity of the polymer optical waveguide is increased. That is, polymer optical waveguides of the same design can be used for the propagation of signals in both the 1310 nm and 1550 nm wavelength bands. Further, signals in the 1310 nm and 1550 nm wavelength bands can be propagated in one polymer optical waveguide.

In the polymer optical waveguide of the present invention, the constituent materials of the core and the clad are not particularly limited as long as the refractive index difference is such that the clad refractive index is lower than the core refractive index. For example, acrylic resins, methacrylic resins such as polymethyl methacrylate (PMMA), epoxy resins, oxetane resins, phenoxy resins, benzocyclobutene resins, norbornene resins, fluorine resins, silicone resins, phenolic resins Resin, polyester resin, polycarbonate resin, polystyrene resin, polyamide resin, polyimide resin, poly (imide / isoindoloquinazolinedioneimide) resin, polyetherimide resin, polyetherketone resin, polyesterimide resin, etc. Various resin materials such as polyimide resin, polybenzoxazole resin, polysilane, polysilazane imidazole resin, and organic-inorganic hybrid materials can be used.
Of these materials, fluororesins are suitable as materials for cores and clads because of their low water absorption or moisture absorption, excellent resistance to high temperature and high humidity, and high chemical stability. A polymer optical waveguide using a fluororesin has stable characteristics with a small change in refractive index due to a change in external environment, particularly a change in humidity, and has high transparency in an optical communication wavelength band.

On the other hand, the polymer optical waveguide preferably has good heat resistance. In addition, it is preferable that the adhesion between the core and the clad is good so that peeling, cracking or the like does not occur at the interface between the core and the clad due to heating, bending, temperature change or the like.
From the viewpoint of heat resistance and adhesion between the core and the clad, the core in the polymer optical waveguide of the present invention may be referred to as a fluorine-containing polyarylene prepolymer (A) (hereinafter, simply referred to as prepolymer (A)). ) Is preferably cured.
On the other hand, the clad in the polymer optical waveguide of the present invention is preferably formed by curing a composition (B) containing a compound having a crosslinkable functional group having a refractive index lower than that of the prepolymer (A).

(Prepolymer (A))
The prepolymer (A) has a polyarylene structure in which a plurality of aromatic rings are bonded via a single bond or a linking group, a fluorine atom, and a crosslinkable functional group.
Examples of the linking group in the polyarylene structure include an ether bond (—O—), a sulfide bond (—S—), a carbonyl group (—CO—), and a divalent group (—SO ₂ —) obtained by removing a hydroxyl group from a sulfonic acid group. Etc. Among the prepolymers (A), those having a structure in which aromatic rings are bonded with a linking group containing an ether bond (—O—) are referred to as a fluorinated polyarylene ether prepolymer (A1). The prepolymer (A) in the present invention is a concept including a fluorine-containing polyarylene ether prepolymer (A1).
Specific examples of the linking group containing an ether bond include an ether bond (—O—) consisting only of an etheric oxygen atom, and an alkylene group containing an etheric oxygen atom in the carbon chain.

The crosslinkable functional group of the prepolymer (A) does not substantially react during the production of the prepolymer, reacts by applying external energy, and causes a high molecular weight by crosslinking or chain extension between prepolymer molecules. It is a group.
Examples of the external energy include heat, light, and electron beam. These may be used in combination. When heat is used as external energy, a reactive functional group that reacts at a reaction temperature of 40 ° C. to 500 ° C. is preferable. If the reaction temperature is too low, stability during storage of the prepolymer or the composition containing the prepolymer cannot be ensured, and if it is too high, thermal decomposition of the prepolymer itself occurs during the reaction. It is preferable. The reaction temperature is more preferably 60 ° C. to 300 ° C., further preferably 70 ° C. to 200 ° C., and particularly preferably 120 ° C. to 250 ° C.
Moreover, when using light (actinic radiation) as external energy, it is preferable to expose in the state where the prepolymer (A) and the photosensitizer coexist. Specifically, it is preferable to prepare a coating liquid (curable composition) containing the prepolymer (A) and to contain a photosensitizer. By selectively irradiating only a desired part with actinic radiation in the exposure step, only the exposed part can be made to have a high molecular weight, and the unexposed part can be dissolved in the developer and removed. Further, if necessary, after the exposure and development, external energy such as actinic radiation or heat can be applied to further increase the molecular weight.

Specific examples of the crosslinkable functional group include vinyl group, allyl group, allyloxy group, methacryloyl (oxy) group, acryloyl (oxy) group, vinyloxy group, trifluorovinyl group, trifluorovinyloxy group, ethynyl group, 1- Examples thereof include an oxocyclopenta-2,5-dien-3-yl group, a cyano group, an alkoxysilyl group, a diarylhydroxymethyl group, a hydroxyfluorenyl group, a cyclobutalene ring, and an oxirane ring. Vinyl groups, methacryloyl (oxy) groups, acryloyl (oxy) groups, trifluorovinyloxy groups, ethynyl groups, cyclobutalene rings, and oxirane rings are preferred because of their high reactivity and high crosslink density. A vinyl group and an ethynyl group are the most preferable from the viewpoint of later good heat resistance.
The methacryloyl (oxy) group means a methacryloyl group or a methacryloyloxy group. The same applies to the acryloyl (oxy) group.

Since the prepolymer (A) has an aromatic ring, the heat resistance is good.
Among the prepolymers (A), in particular, the fluorine-containing polyarylene ether prepolymer (A1) has an etheric oxygen atom, so that the molecular structure is flexible and the cured product has good flexibility. This is preferable.
The prepolymer (A) has a fluorine atom. That is, since the prepolymer (A) has a C—F bond in which a hydrogen atom of a C—H bond is substituted with a fluorine atom, the proportion of the C—H bond is small. Since the C—H bond has absorption in the optical communication wavelength band (1250 to 1650 nm), the prepolymer (A) having few C—H bonds can suppress light absorption in the optical communication wavelength band. Further, since the prepolymer (A) has a fluorine atom, the water absorption or hygroscopicity is low, the resistance to high temperature and high humidity is excellent, and the chemical stability is also high. Therefore, the optical waveguide using the prepolymer (A) has small refractive index fluctuation due to changes in the external environment, particularly humidity change, and has stable characteristics, and has high transparency in the optical communication wavelength band.
Moreover, since the cured product of the prepolymer (A) has high transparency in the vicinity of a wavelength of 1310 nm, an optical waveguide having good compatibility with existing optical elements can be obtained. That is, in general, in an optical transmission device using a silica-based optical fiber, a wavelength of 1310 nm is often used, so that many optical elements such as a light receiving element suitable for this wavelength are manufactured, and the reliability is high. .

Examples of preferred prepolymer (A) include fluorine-containing aromatic compounds such as perfluoro (1,3,5-triphenylbenzene) and perfluorobiphenyl; 1,3,5-trihydroxybenzene, 1,1,1 Reacting a phenolic compound such as tris (4-hydroxyphenyl) ethane with a crosslinkable compound such as pentafluorostyrene, acetoxystyrene or chloromethylstyrene in the presence of a dehydrohalogenating agent such as potassium carbonate; Examples include the resulting polymer.

The content of the crosslinkable functional group in the prepolymer (A) is preferably 0.1 to 4 mmol, more preferably 0.2 to 3 mmol with respect to 1 g of the prepolymer. By setting this range to 0.1 mmol or more, the heat resistance and solvent resistance of the cured product can be increased, and by setting it to 4 mmol or less, brittleness can be reduced and an increase in the dielectric constant can be suppressed. . *

The prepolymer (A) preferably has an absorbance of 7.5 or less at a wavelength of 365 nm at a polymer thickness of 10 mm and a polymer concentration of 100 wt%. In this specification, the absorbance at a polymer concentration of 100 wt% refers to an actually measured value of absorbance at 100 wt% polymer or an assumed value of absorbance at 100 wt% polymer.
As will be described in detail later, a photolithography process may be used when forming the core of the polymer optical waveguide during the production of the polymer optical waveguide. For exposure in this photolithography process, i-line having a wavelength of 365 nm is usually used. When the absorbance at a wavelength of 365 nm is high, the prepolymer (A) absorbs i-line during exposure in the photolithography process, and there is a possibility that a dent will be formed in the formed core. If the prepolymer (A) has a polymer thickness of 10 mm, a polymer concentration of 100 wt% and an absorbance at a wavelength of 365 nm of 7.5 nm or less, the prepolymer (A) is less likely to be dented.
As a result, propagation loss is reduced at 1310 nm and 1550 nm, which are typical wavelength bands in the single mode.
The prepolymer (A) preferably has an absorbance at a wavelength of 365 nm at a polymer thickness of 10 mm and a polymer concentration of 100 wt% of 7.5 or less, more preferably 6.5 or less, and 6.0 or less. Is more preferable and 5.5 or less is particularly preferable.

The prepolymer (A) preferably has an absorbance peak value of 0.045 or less at a wavelength of 1400 nm to 1460 nm at a polymer thickness of 10 mm and a polymer concentration of 100 wt%.
When the prepolymer (A) contains moisture, in the core formed using the prepolymer (A), propagation loss may occur at 1310 nm and 1550 nm, which are typical wavelength bands in the single mode.
When the prepolymer (A) contains moisture, absorption at a wavelength of 1400 nm to 1460 nm increases. If the peak value of absorbance at a wavelength of 1400 nm to 1460 nm at a polymer thickness of 10 mm and a polymer concentration of 100 wt% is 0.045 or less, the prepolymer (A) contains very little water, and the prepolymer (A) is used. In the core to be formed, propagation loss is reduced at 1310 nm and 1550 nm, which are typical wavelength bands in the single mode.

In addition, as shown in the Example mentioned later, in prepolymer (A), a correlation is recognized between the absorption in wavelength 365nm and the absorption in wavelength 1400nm-1460nm. Therefore, by measuring one of the absorbance at a wavelength of 365 nm and the peak value of the absorbance at a wavelength of 1400 nm to 1460 nm, the other tendency can be estimated. For example, the level of absorbance at a wavelength of 365 nm can be estimated from the absorbance peak value at a wavelength of 1400 nm to 1460 nm.

(Composition (B))
The composition (B) preferably contains a prepolymer (A) and a compound (C) having a crosslinkable functional group and having a molecular weight of 140 to 5000 and having no fluorine atom.
The prepolymer (A) contained in the composition (B) may be the same or different from the prepolymer (A) used for forming the core. The same is preferable from the viewpoint of adhesiveness, adhesion, crack suppression, or reduction in expansion coefficient difference.

(Compound (C))
The compound (C) has a molecular weight of 140 to 5000, has a crosslinkable functional group, and does not have a fluorine atom. Since there are no fluorine atoms, good embedding flatness is easily obtained. If the embedded flatness is good, the surface of the clad tends to be flat. Further, the cost is likely to be lower than that of the fluorine-containing compound.

When the molecular weight of the compound (C) is 5000 or less, the viscosity of the compound (C) is suppressed low, and a uniform composition is easily obtained when mixed with the prepolymer (A). Also, good flatness can be easily obtained.
When the molecular weight of the compound (C) is 140 or more, good heat resistance is obtained, and decomposition and volatilization due to heating hardly occur. The molecular weight range of the compound (C) is preferably 250 to 3000, particularly preferably 250 to 2500.

The crosslinkable functional group of the compound (C) does not contain a fluorine atom, and a reactive functional group that reacts in the same step as the step of reacting the crosslinkable functional group of the prepolymer (A) is preferable.
The crosslinkable functional group of compound (C) reacts with at least compound (C) to cause crosslinking or chain extension. It is preferable that the crosslinkable functional group of the compound (C) reacts with both the prepolymer (A) and the compound (C) to cause crosslinking or chain extension.
The crosslinkable functional group of the compound (C) is preferably a double bond or triple bond at a carbon atom-carbon atom. However, aromatic double bonds and triple bonds are not included.
The double bond and triple bond as the crosslinkable functional group may exist inside the molecular chain or may exist at the terminal, but preferably exist at the terminal because of high reactivity. In the case of a double bond, it may be an internal olefin or a terminal olefin, but a terminal olefin is preferred. Being inside a molecular chain includes being present in a part of an aliphatic ring such as cycloolefins.
Specifically, it is preferable to include at least one selected from the group consisting of a vinyl group, an allyl group, an ethynyl group, a vinyloxy group, an allyloxy group, an acryloyl group, an acryloyloxy group, a methacryloyl group, and a methacryloyloxy group. Among these, an acryloyl group and an acryloyloxy group are preferable in that a reaction is caused by light irradiation even in the absence of a photosensitizer.

The compound (C) preferably has 2 or more crosslinkable functional groups, more preferably 2 to 20, more preferably 2 to 8. When two or more crosslinkable functional groups are present, the molecules can be cross-linked, so that the heat resistance of the cured film can be improved, and the film thickness reduction due to heating in the cured film can be satisfactorily suppressed.

Specific examples of the compound (C) include dipentaerythritol triacrylate triundecylate, dipentaerythritol pentaacrylate monoundecylate, ethoxylated isocyanuric acid triacrylate, ε-caprolactone modified tris- (2-acryloxyethyl) Isocyanurate, dipentaerythritol polyacrylate, 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, ethoxylation Bisphenol A diacrylate, ethoxylated bisphenol A dimethacrylate, propoxylated bisphenol A diacrylate Propoxylated bisphenol A dimethacrylate, 1,10-decanediol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,3-butanediol diacrylate Methacrylate, hydroxypivalate neopentyl glycol diacrylate, 1,9-nonanediol diacrylate, 1,9-nonanediol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, pentaerythritol triacrylate, trimethylolpropane tri Acrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, triallyl cyanurate, Triallyl isocyanurate, trimethallyl isocyanurate, 1,4-butanediol divinyl ether, 1,9-nonanediol divinyl ether, cyclohexane dimethanol divinyl ether, triethylene glycol divinyl ether, trimethylolpropane trivinyl ether, pentaerythritol tetra Vinyl ether, 2- (2-vinyloxyethoxy) ethyl acrylate, 2- (2-vinyloxyethoxy) ethyl methacrylate, trimethylolpropane diallyl ether, pentaerythritol triallyl ether, dipentaerythritol hexaacrylate, pentaerythritol tetraacrylate , Ethoxylated pentaerythritol tetraacrylate represented by the following formula (1), pro represented by the following formula (2) Carboxymethyl pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, tricyclodecane dimethanol diacrylate, tricyclodecane dimethanol methacrylate, compounds represented by the following formula (3). In addition, polyester acrylate (compound obtained by modifying both ends of the condensate of dihydric alcohol and dibasic acid with acrylic acid: manufactured by Toagosei Co., Ltd., trade name Aronix (M-6100, M-6200, M-6250, M-6500) ); Compound obtained by modifying the hydroxyl terminal of the condensate of polyhydric alcohol and polybasic acid with acrylic acid: manufactured by Toagosei Co., Ltd., trade name Aronix (M-7100, M-7300K, M-8030, M-8060, M -8100, M-8530, M-8560, M-9050)) can also be used. These can be obtained from commercial products.
Among those listed above, polypropylene glycol dimethacrylate and 1,10-decanediol diacrylate are preferable because of good moldability of the cured film.

As described above, the clad constituent material needs to have a lower refractive index than the core constituent material. When the core constituent material is a prepolymer (A) and the clad constituent material is a polymer composition including the prepolymer (A) and the compound (C), the polymer is more preferable than the cured product of the prepolymer (A). What is necessary is just to adjust the mixing ratio of the kind of compound (C) and the prepolymer (A) in a polymer composition, and a compound (C) so that the refractive index of the hardened | cured material of a composition may become low.
When using the compound (C) in which the refractive index of the cured product is higher than the refractive index of the cured product obtained by curing the prepolymer (A) alone, the refractive index of the cured product was obtained by curing the prepolymer (A) alone. By using it in combination with another compound (C) lower than the refractive index of the cured product, the refractive index of the cladding can be made lower than the refractive index of the core.

In the polymer optical waveguide 10 shown in FIG. 1, the under clad 31 and the over clad 32 may be made of the same material or different materials. For example, when materials having different refractive indexes are used for the underclad 31 and the overclad 32, the light confinement state in the polymer optical waveguide 10 can be controlled.

The method for producing the polymer optical waveguide of the present invention is not particularly limited, and various methods can be used. Specifically, replication (stamper) method, direct exposure method, method combining reactive ion etching (RIE) and photolithography process, method based on injection molding, photo bleaching method, direct drawing method, self-formation The law etc. can be used.

An example of the manufacturing method of the polymer optical waveguide 10 of the present invention will be described.
First, a coating solution containing the composition (B) is applied on a substrate by spin coating. Subsequently, the composition (B) is cured to form the underclad 31.
Next, a coating solution containing the prepolymer (A) is applied on the underclad 31 by spin coating. Subsequently, the prepolymer (A) is patterned by a photolithography process, and the core 20 is formed on the underclad 31. At this time, when forming a shape in which the width of the core 20 is different along the light propagation direction, development is performed after performing exposure using a photomask having a shape in which the width of the core 20 is different along the light propagation direction. Thus, the core 20 can be formed. Moreover, after forming the core 20, you may post-bake as needed.
Next, the coating liquid containing the composition (B) is applied onto the underclad 31 and the core 20 by spin coating. Subsequently, the composition (B) is cured to form the overclad 32. When the over clad 32 is formed, the exposed core portion 40 where the over clad 32 does not exist and the core 20 is exposed can be formed by a photolithography process.
The polymer optical waveguide 10 can be manufactured by the above method. In addition, when apply | coating the coating liquid containing a composition (B) or the coating liquid containing a prepolymer (A), these coating liquids should be left still and defoamed and then applied. preferable. Thereby, the polymer optical waveguide 10 in which no bubble defect exists in the core 20 or in the vicinity of the interface between the core 20 and the clad 30 can be manufactured. Moreover, it is preferable to defoam using a defoaming apparatus in addition to or in place of sufficiently leaving the coating solution to defoam. Moreover, it is preferable to filter the coating solution before coating the coating solution. Thereby, the foreign material in a coating liquid can be removed. Further, it is preferable to clean the substrate before applying the coating solution. Thereby, the foreign material on the surface of the substrate can be removed. In order to prevent foreign matter from adhering to the air, these operations are preferably performed in a clean room, and in order to prevent foreign matter from adhering to static electricity, it is more preferable to use an electrostatic remover (ionizer).

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following, Examples 1 to 3 are Examples, and Example 4 is a Comparative Example.

(Example 1)
The prepolymer (A) used for forming the core was prepared by the following procedure.
In a N, N-dimethylacetamide (hereinafter referred to as DMAc) solvent, perfluorobiphenyl (67% by mass) and 1,3,5-trihydroxybenzene (12% by mass) in the presence of potassium carbonate are added to 35 to 35%. After reacting at 42 ° C. for 5 hours, 4-acetoxystyrene (21% by mass) was subsequently reacted in the presence of an aqueous potassium hydroxide solution to synthesize a prepolymer. The obtained DMAc solution of the prepolymer was poured into an aqueous hydrochloric acid solution for reprecipitation purification and vacuum dried to obtain a powdery prepolymer (A).

About the prepolymer (A) obtained by said procedure, the light absorbency in wavelength 365nm was measured in the following procedures.
It was measured with a spectrophotometer (manufactured by Shimadzu Corporation, product type: SolidSpec3700DUV). Using a quartz cell with an optical path length of 10 mm, the absorbance of three or more solutions with a prepolymer (A) concentration stepwise changed from 10 wt% to 40 wt% is measured, and the value at the time of 100% extrapolation is converted to the least square method. And approximated. The measurement wavelength range was 300 to 2500 nm, the scan speed was medium, and the sampling pitch was 5 nm. The detector unit measured by direct light reception. Deuterated chloroform was used as the solvent. The absorbance of the prepolymer (A) is determined by subtracting the solvent absorption as a baseline. FIG. 9 shows the absorbance of the prepolymer (A) obtained by the above procedure in the vicinity of a wavelength of 400 nm. Absorbance at a wavelength of 365 nm (polymer thickness: 10 mm, concentration: 100% equivalent) was 3.98.
The absorbance peak value at a wavelength of 1400 nm to 1460 nm (polymer thickness 10 mm, concentration 100% conversion) was determined by the above procedure. The absorbance peak value at a wavelength of 1400 nm to 1460 nm (polymer thickness 10 mm, concentration 100% conversion) was 0.06.

A composition (B) used for forming the clad was prepared by the following procedure.
50 parts by mass of the prepolymer (A) obtained by the above procedure, 25 parts by mass of 1,10-decanediol diacrylate (molecular weight: 282) as the compound (C), 25 parts by mass of polypropylene glycol dimethacrylate, Was put in a container and mixed at room temperature for 55 hours to obtain a composition (B).

Using the prepolymer (A) obtained by the above procedure and the composition (B), a polymer optical waveguide was produced by the following procedure.
A silicon wafer was used as the substrate. The composition (B) was applied onto the substrate by spin coating, and heated at 190 ° C. for 1 hour to form an underclad.
Next, a prepolymer (A) is applied thereon, and the coating film is exposed with an ultrahigh pressure mercury lamp at an irradiation energy of 2000 mJ / cm ² in a state where light is shielded with a metal foil except for the core portion of the coating film. did. Then, it developed using the liquid mixture of PGMEA and ethyl lactate as a developing solution, and it was made to dry after removing the unexposed part of a coating film. Post-baking was performed at 190 ° C. for 1 hour to form a core.
Subsequently, the composition (B) was applied by spin coating on the core and the underclad to form a coating film. The coated film was exposed with an ultrahigh pressure mercury lamp at an irradiation energy of 2000 mJ / cm ² in a state in which the portion other than the overcladding portion was shielded from light with a metal foil. Then, it developed using PGMEA as a developing solution, and it was made to dry after removing the unexposed part of a coating film. Further, post-baking at 190 ° C. for 2 hours was performed to form an overclad and a core exposed portion where the overclad was not present and the core was exposed.

FIG. 10 is a plan view of the polymer optical waveguide obtained by the above procedure. In the polymer optical waveguide of FIG. 10, reference numeral 120 denotes a core, and reference numeral 132 denotes a clad (over clad). In the polymer optical waveguide shown in FIG. 10, the symbol a is a core in a region where no overcladding exists. In Examples 1 to 4, the core was observed at the position of the symbol a. Reference numeral b denotes an overclad in which the optical measurement core on the input side exists below, and reference numeral c denotes an overclad in which the optical measurement core on the output side exists below.
In (Example 1), the core exposed portion (input side) indicated by symbol a has a core height of 2.5 μm and a core width of 7.5 μm. The core for optical measurement (input side) indicated by symbol b has a core height of 2.5 μm and a core width of 2.5 μm. The core for optical measurement (output side) indicated by symbol c has a core height of 2.5 μm and a core width of 2.5 μm. The thickness of the underclad is 25 μm, and the thickness of the overclad is 25 μm.

With respect to the core exposed portion (input side) indicated by symbol a, the cross-sectional shape of the core was measured at a point of about 1300 μm from the input side end portion. A white interferometer (manufactured by ZYGO, product type: three-dimensional optical profiler system Newview 7300) was used to measure the cross-sectional shape of the core. The objective lens used 50 times.
For the core height, plot data of the core shape with a white interferometer, create data with the undercladding part corrected horizontally, and draw a baseline at the height of the undercladding part at a distance of 25 μm on both sides from the core center. Using the baseline as the origin, the highest value of the core protrusions was defined as the core height. The core width in the cross-sectional shape was defined as the width at the position where the core height becomes half value.
FIG. 11 is a diagram showing a core cross-sectional shape in the core exposed portion. As shown in the figure, a recess is present on the upper surface of the core.
When a tangent line is drawn between two adjacent convex portions existing on the core upper surface, the maximum height difference in the core thickness direction between the tangent line and the concave portion located between the two convex portions exists on the core upper surface. The depth of the dent to be.
The depth of the dent existing on the upper surface of the core was 0.07 μm.

Propagation loss measurement was performed using the optical measurement core (input side) indicated by symbol b and the optical measurement core indicated by symbol c (output side). The propagation loss measurement was performed using the method described in the JPCA standard (2008) 4.6.2.1 cutback method. The mode combination of the incident side optical fiber and the optical waveguide is a combination corresponding to the combination number 6 described in the JPCA standard, Table 4.6.1-1. The single mode fiber on the incident side and the single mode on the output side. A mode fiber was used. The fiber used for the insertion loss measurement was a single mode fiber (manufactured by Corning, product number: SMF-28, NA 0.14, core diameter 8.2 um) on both the incident side and the outgoing side.
As a light source on the light emission side used in the optical measurement system, a unit (product name: AQ2140, manufactured by Ando Electric Co., Ltd.) having an LD light source (product name: AQ4213) was used. On the light receiving side, a power meter (manufactured by Advantest, product name: Q8221 unit) and a sensor unit (manufactured by Advantest, product name: Q82208) were used.
The propagation loss value X at a wavelength of 1550 nm was 0.32 [dB / cm], the propagation loss value Y at a wavelength of 1310 nm was 0.61 [dB / cm], and the propagation loss ratio X / Y was 0.52.

(Example 2)
In the polymer optical waveguide shown in FIG. 10, the core exposed portion (input side) indicated by symbol a has a core height of 2.5 μm, a core width of 9.3 μm, and optical measurement indicated by symbol b in the polymer optical waveguide shown in FIG. Core (input side) is 2.5 μm in core height and 2.5 μm in core width, and the core for optical measurement (output side) indicated by symbol c is 2.5 μm in core height, 2.5 μm in core width, and under cladding The same procedure as in Example 1 was performed except that the thickness of the overcladding was 25 μm and the thickness of the overclad was 25 μm.
For the core exposed portion (input side) indicated by symbol a, the cross-sectional shape of the core was measured in the same procedure as in Example 1 at a point of about 1300 μm from the input side end portion.
FIG. 12 is a diagram showing a core cross-sectional shape in the core exposed portion. As shown in the figure, a recess is present on the upper surface of the core. The depth of the recess existing on the upper surface of the core was 0.15 μm. Propagation loss measurement was performed in the same procedure as in Example 1 using the optical measurement core (input side) indicated by symbol b and the optical measurement core (output side) indicated by symbol c.
The propagation loss value X at 1550 nm was 0.29 [dB / cm], the propagation loss value Y at 1310 nm was 0.61 [dB / cm], and the propagation loss ratio X / Y was 0.47.

The heat resistance of the polymer optical waveguide obtained in Example 2 was evaluated by the following three methods.

[Heat cycle test]
The temperature cycle test described in the JPCA standard (2008), 6.2.5 was performed. In this test, the temperature was lowered from room temperature (25 ° C.) to −50 ° C. over 55 minutes, held for 30 minutes, then raised to 25 ° C. over 30 minutes, held for 20 minutes, and then 125 ° C. over 30 minutes. The temperature cycle of raising the temperature to 25 ° C. and holding it for 30 minutes and then lowering the temperature to 25 ° C. over 45 minutes and holding it for 20 minutes was repeated 35 cycles. The difference in insertion loss was measured before and after the test.
The insertion loss was measured by the insertion loss measuring method described in the JPCA standard, 4.6.1. The measurement apparatus, measurement procedure, measurement conditions, and the like were performed under the same conditions as the above-described propagation loss measurement.
The measurement result of the insertion loss was within the range of measurement error before and after the temperature cycle test, and the change in insertion loss before and after the temperature cycle test was 0.1 dB or less.

[Heat resistance (high temperature storage test)]
A high temperature storage test described in the JPCA standard (2008), 6.2.1 was performed to evaluate heat resistance. Assuming that the optical waveguide is soldered, it is preferable that the optical waveguide is stable against heating at 200 ° C. or higher.
In this test, the sample was placed in an oven, heated from room temperature to 260 ° C. over 5 minutes, held at 260 ° C. for 30 seconds, and then allowed to stand naturally until the temperature reached room temperature. In the evaluation, the difference in insertion loss was measured before and after being put into the oven. The difference in insertion loss was as small as 0.1 dB or less, and the heat resistance was good.

[Heat resistance (high temperature and high humidity storage test)]
A high temperature and high humidity leaving test described in the JPCA standard (2008), 6.2.3 was performed to evaluate heat resistance. The test condition was “Test condition 3”. That is, in this test, after being put in a high temperature and high humidity condition of 85 ° C. and 85% RH for 140 hours, it was allowed to stand until the temperature naturally reached room temperature. The difference in insertion loss before and after charging under high temperature and high humidity conditions was measured. As a result, the change in insertion loss due to being held under high temperature and high humidity conditions was 0.2 dB or less.

(Example 3)
Prepolymer A used for core formation was prepared by the following procedure.
In a solvent of N, N-dimethylacetamide (hereinafter referred to as DMAc), perfluorobiphenyl (67% by mass) and 1,3,5-trihydroxybenzene (12% by mass) in the presence of potassium carbonate were added in an amount of 40 to 40 After reacting at 43 ° C. for 5 hours, 4-acetoxystyrene (21% by mass) was subsequently reacted in the presence of an aqueous potassium hydroxide solution to synthesize a prepolymer. The obtained DMAc solution of the prepolymer was poured into an aqueous hydrochloric acid solution for reprecipitation purification and vacuum dried to obtain a powdery prepolymer A.
As prepolymer A, the absorbance at a wavelength of 365 nm (polymer thickness: 10 mm, converted to 100% concentration) is 4.86, and the absorbance peak value at a wavelength of 1400 nm to 1460 nm (polymer thickness: 10 mm, converted to 100% concentration) is 0.12. The same procedure as in Example 1 was carried out except that it was used. In the polymer optical waveguide shown in FIG. 10, the core exposed portion (input side) indicated by symbol a is 2.5 μm in core height, the core width is 7.4 μm, and the optical measurement core indicated by symbol b (input side) is the core height. The thickness is 2.5 μm and the core width is 2.5 μm. The core for optical measurement (output side) indicated by symbol c has a core height of 2.5 μm, a core width of 2.5 μm, an underclad thickness of 25 μm, and an overclad thickness of 25 μm.
For the core exposed portion (input side) indicated by symbol a, the cross-sectional shape of the core was measured in the same procedure as in Example 1 at a point of about 1300 μm from the input side end.
FIG. 13 is a diagram showing a core cross-sectional shape in the core exposed portion. As shown in the figure, a recess is present on the upper surface of the core. The depth of the dent existing on the upper surface of the core was 0.13 μm. Propagation loss measurement was performed in the same procedure as in Example 1 using the optical measurement core (input side) indicated by symbol b and the optical measurement core (output side) indicated by symbol c.
The propagation loss value X at 1550 nm was 0.40 [dB / cm], the propagation loss value Y at 1310 nm was 0.61 [dB / cm], and the propagation loss ratio X / Y was 0.66.

(Example 4)
Prepolymer A used for core formation was prepared by the following procedure.
In a solvent of N, N-dimethylacetamide (hereinafter referred to as DMAc), perfluorobiphenyl (67% by mass) and 1,3,5-trihydroxybenzene (12% by mass) in the presence of potassium carbonate were added in an amount of 40 to 40 After reacting at 46 ° C. for 5 hours, 4-acetoxystyrene (21% by mass) was subsequently reacted in the presence of an aqueous potassium hydroxide solution to synthesize a prepolymer. The obtained DMAc solution of the prepolymer was poured into an aqueous hydrochloric acid solution for reprecipitation purification and vacuum dried to obtain a powdery prepolymer A.
Prepolymer A having an absorbance at a wavelength of 365 nm (polymer thickness of 10 mm, converted to 100% concentration) of 7.9, and an absorbance peak value at a wavelength of 1400 nm to 1460 nm (polymer thickness of 10 mm, converted to a concentration of 100%) of 0.26 In the polymer optical waveguide shown in FIG. 10, the exposed core portion (input side) indicated by reference symbol a has a core height of 2.5 μm, a core width of 9.4 μm, and reference symbol b. 1. An optical measurement core (input side) shown in FIG. 2 has a core height of 2.5 μm and a core width of 2.5 μm, an optical measurement core shown by reference c (output side) has a core height of 2.5 μm, and a core width of 2. The same procedure as in Example 1 was performed except that the thickness was 5 μm.
FIG. 9 shows the absorbance of the prepolymer (A) used in Example 4 around a wavelength of 400 nm.
For the core exposed portion (input side) indicated by symbol a, the cross-sectional shape of the core was measured in the same procedure as in Example 1 at a point of about 1300 μm from the input side end.
FIG. 14 is a diagram showing a core cross-sectional shape in the core exposed portion. As shown in the figure, a recess is present on the upper surface of the core. The depth of the dent existing on the upper surface of the core was 0.36 μm.
Propagation loss measurement was performed in the same procedure as in Example 1 using the optical measurement core (input side) indicated by symbol b and the optical measurement core (output side) indicated by symbol c.
The propagation loss value X at 1550 nm was 0.69 [dB / cm], the propagation loss value Y at 1310 nm was 0.82 [dB / cm], and the propagation loss ratio X / Y was 0.83.

Examples 1 to 3, in which the depth of the dent existing on the upper surface of the core is 0.33 μm or less, are representative of wavelength bands in the single mode compared to Example 4 in which the depth of the dent existing on the upper surface of the core is greater than 0.33 μm. Propagation losses X and Y at 1310 nm and 1550 nm are reduced. In Examples 1 to 3, since the propagation loss ratio X / Y is in the range of 0.2 to 2, the design freedom of the polymer optical waveguide is high, and the productivity of the polymer optical waveguide is high.
In Examples 1 to 3, since the prepolymer A used for core formation had an absorbance at a wavelength of 365 nm (concentration of 100%) of 7.5 or less, 1310 nm, which is a typical wavelength band in a single mode, And propagation losses X and Y at 1550 nm are reduced. Moreover, it is estimated that it has influenced that the depth of the dent which exists in a core upper surface is 0.33 micrometer or less.
In Example 4, as the prepolymer A used for core formation, one having an absorbance at a wavelength of 365 nm (polymer thickness 10 mm, concentration 100% equivalent) of more than 7.5 is representative of the wavelength band in the single mode. The propagation losses X and Y at the typical 1310 nm and 1550 nm are increased. Further, it is assumed that the depth of the dent existing on the upper surface of the core is affected by being over 0.33 μm.

Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on March 15, 2017 (Japanese Patent Application No. 2017-049960), which is incorporated by reference in its entirety.

10: polymer optical waveguide 20: core 30: clad 31: under clad 32: over clad 40: core exposed portion 60: dent 100: silicon optical waveguide 200: single mode optical fiber

Claims

A polymer optical waveguide having a core and a clad having a refractive index lower than that of the core,
The polymer optical waveguide has a sheet shape, and in the core cross-sectional shape perpendicular to the light propagation direction of the core, the thickness direction of the sheet shape is the core height, and the direction perpendicular to the thickness direction is the core width. The core height is 1.0 to 10 μm, the core width is 1.0 to 15 μm,
A polymer optical waveguide, wherein a depth of a dent existing on the upper surface and / or the side surface of the core in the core cross-sectional shape is 0.33 μm or less.
The propagation loss ratio X / Y obtained by dividing the propagation loss value X [dB / cm] at a wavelength of 1550 nm by the propagation loss value Y [dB / cm] at a wavelength of 1310 nm is 0.2 to 2. Polymer optical waveguide.
The core is obtained by curing a composition containing a fluorinated polyarylene prepolymer (A) having a crosslinkable functional group, and the clad has a lower refractive index than the fluorinated polyarylene prepolymer (A). The polymer optical waveguide according to claim 1 or 2, wherein the composition (B) containing a compound having a crosslinkable functional group is cured.
The composition (B) contains the fluorine-containing polyarylene prepolymer (A) and a compound (C) having a crosslinkable functional group and having a molecular weight of 140 to 5000 and having no fluorine atom. The polymer optical waveguide described.
The polymer optical waveguide according to claim 3 or 4, wherein the fluorine-containing polyarylene prepolymer (A) has an absorbance at a wavelength of 365 nm at a polymer thickness of 10 mm and a polymer concentration of 100 wt% of 7.5 or less.
The polymer optical waveguide according to any one of claims 1 to 5, which is a single-mode polymer optical waveguide.
The polymer optical waveguide according to any one of claims 1 to 6, wherein the polymer optical waveguide has a coupling portion where at least a part of the core is exposed on one end side.
A composite optical waveguide comprising the polymer optical waveguide according to any one of claims 1 to 7 and a connector that accommodates an optical waveguide portion of the polymer optical waveguide.