JP3326271B2 - Optical fiber terminal and connection structure between terminal and optical device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a connection structure between the optical fiber end portion及 beauty terminal portion and the optical device.

[0002]

2. Description of the Related Art Conventionally, an optical connection between an optical device such as an optical waveguide component or an optical semiconductor element (LD array, LED array) and an optical fiber has been conventionally performed by using an optical fiber terminal section in which a plurality of optical fibers are arranged at a predetermined pitch. And the optical device are abutted or opposed to each other. Then, alignment is performed to align the optical axis between the optical fiber and the optical device, and the two are bonded with an adhesive such as a thermosetting type or a light (ultraviolet) setting type, or the two are separated at a predetermined interval. After the optical axes are aligned, that is, aligned, between the optical fiber and the optical device, they are welded and fixed on a metal base.

As a first example of such connection between an optical fiber terminal and an optical device, for example, connection between an optical fiber terminal and an optical waveguide component is known. The optical fiber terminal includes a tape fiber and a ferrule in which a plurality of optical fibers are arranged at a predetermined pitch in a coating. The ferrule has an abutting end face facing or abutting the optical waveguide component, and a plurality of fiber holes formed in parallel at a predetermined pitch, and one end of the optical fiber is inserted and bonded and fixed to each of the fiber holes, Each optical fiber is exposed at the butt end face. For the ferrule, plastic molding using a mold is the cheapest and is a general manufacturing method.

Some optical waveguide components further include a waveguide substrate and a waveguide layer, or a cover adhered on the waveguide layer, and the waveguide layer has one or more waveguides formed thereon. The respective waveguides are exposed at the butting end faces on both sides. Here, the cover secures an effective bonding area with the optical fiber terminal by approximating the area and shape of the optical waveguide component at the butting end of the optical waveguide component to the optical fiber terminal.

[0005] The optical fiber terminal section is bonded to the optical waveguide component after the optical waveguide component and the butting end faces are abutted with each other, and the respective optical fibers are aligned with the corresponding waveguide. By the way, when the optical fiber terminal and the optical waveguide component are bonded to each other, in order to suppress the connection loss at the optical fiber terminal, especially when the optical fiber is in a single mode, the optical fiber and the corresponding waveguide are connected to each other by a submicron. It is necessary to align them on an order and bond and fix them in a short time while maintaining the aligned state.

As such an adhesive means, a thermosetting adhesive such as an epoxy resin which cures at a high speed is used. And the optical fiber terminal and the optical waveguide component are:
In order to prevent the optical path from being interrupted between each optical fiber and the corresponding waveguide, the optical fiber is bonded at a portion excluding the optical fiber and the waveguide exposed at the abutting end face. As a second example, connection between an optical fiber terminal portion having another structure and an optical waveguide component is also known.

This optical fiber terminal section includes a tape fiber, a V-groove substrate, and a pressing cover, and has abutting end faces formed at both ends. In the tape fiber, a plurality of optical fibers are arranged in the coating at a predetermined pitch, the coating is removed from the end to expose the end of each optical fiber, and the end of each exposed optical fiber is formed on the V-groove substrate. Each optical fiber is fixed to the V-groove substrate by positioning with the respective V-grooves and covering the holding cover.

Here, the end faces of the optical fibers are exposed to the butted end faces, and the end faces are polished together with the V-groove substrate and the holding cover. The V-groove substrate and the holding cover are made of an optically transparent material such as glass. Is used. Optical waveguide components
It is configured similarly to the optical waveguide component of the first example,
The cover is an optically transparent material such as glass.

Then, the optical fiber end portion and the optical waveguide component are brought into contact with each other at the butting end faces, and after aligning between the corresponding optical fiber and the waveguide, irradiation with curing light (ultraviolet light) is performed. While being bonded with a light-curing adhesive. At this time, since the V-groove substrate and the pressing cover are optically transparent materials, the transmitted irradiation light cures the adhesive in a shorter time as compared with the thermosetting adhesive such as the epoxy resin which cures at a high speed. Therefore, the optical fiber end portion and the optical waveguide component are quickly bonded to each other at the butt end face.

Further, as a third example, a connection between the optical fiber terminal section of the second example and an optical semiconductor is also known. In the optical semiconductor, a heat sink is arranged between an LD array in which a plurality of laser diode elements are arranged in a row and a carrier, and each laser diode element is electrically connected to a carrier by a bonding wire, and the carrier is electrically connected to the carrier. Is fixed to a metal mount base.

On the other hand, the optical fiber terminal is welded to a metal base via a sub-base, and each optical fiber of the tape fiber is aligned with a corresponding laser diode element, and the base is welded to the mount base. .

[0012]

The connection between the optical fiber terminal and the optical device has the following problems. First, in the connection between the optical fiber end portion and the optical waveguide component shown in the first example, in the case where the optical waveguide component is, for example, a silica-based optical waveguide component in which a silica-based waveguide layer is formed on a silicon substrate by deposition. , The coefficient of linear expansion is about 20
It is about 2.4 × 10 ^-6 at ° C. On the other hand, the end portion of the optical fiber has a coefficient of linear expansion of the plastic forming the ferrule of, for example, 5 × 10 ^{− at} about 20 ° C. in the case of an epoxy resin containing silicon dioxide (SiO ₂ ) fine particles as a filler. ⁶ or more.

For this reason, after connecting the optical fiber terminal portion and the optical waveguide component, the difference in the linear expansion coefficient between the two due to the time-dependent temperature change in the use environment causes the distance between each waveguide and the optical fiber. The alignment state is disturbed, the connection loss decreases,
There has been a problem that the performance is reduced and the function is lost. In addition, since the ferrule of the optical fiber end is manufactured by plastic molding using a mold, the linear expansion coefficient in the direction in which the plurality of fiber holes are arranged differs from the linear expansion coefficient in the direction orthogonal to the arrangement direction. When,
There is also a problem that the ferrule is deformed by warping or the like, and the fiber hole cannot be formed with high accuracy.

Further, the ferrule of the optical fiber terminal section is as follows:
Conventionally, an epoxy resin is mixed with a filler or the like for the purpose of minimizing the coefficient of linear expansion and improving strength and dimensional accuracy, and an optically opaque material has been used. For this reason, it has been impossible for the conventional optical fiber terminal to be connected to the optical waveguide component using a photocurable adhesive. On the other hand, the optical fiber terminal shown in the second and third examples uses an optically transparent material such as silicon or ceramic in addition to the above-mentioned glass as a material for the V-groove substrate and the holding cover. Is also possible.

However, since glass, silicon and ceramics are all hard and brittle, there is a problem that grinding costs are high, such as difficulty in grinding the V-groove and poor polishing of the butted end surfaces. In addition, since the optical fiber terminal section positions each of the fine optical fibers in the V-groove and fixes each optical fiber to the V-groove substrate with a holding cover, the optical fiber is assembled.
Workability in assembly work was poor.

In addition, since each optical fiber is fixed by the holding cover, if the optical fiber is excessively pressed by the holding cover, the optical fiber is extended when a stress acts on each optical fiber extending from the V-groove substrate. However, there was a case where it was easily disconnected. The present invention has been made in view of the above, can be molded with high accuracy, thus providing a connection structure between the optical fiber end portion及 beauty terminal portion and the optical device which is excellent in connection with the optical device The purpose is to do.

Another object of the present invention is to provide an optical fiber terminal portion which is easy to manufacture, is inexpensive, and in which the optical fiber is hardly broken, and a connection structure between the terminal portion and the optical device.

[0018]

According to the optical fiber terminal of the present invention, in order to achieve the above object, an abutting end face facing or abutting an optical device is formed in parallel with a single fiber hole or a predetermined pitch. Having a plurality of formed fiber holes, comprising a ferrule in which one end of an optical fiber is inserted and bonded and fixed to each of the fiber holes,
In the optical fiber terminal portion where the optical fiber is optically connected to an optical device, the ferrule is made of a synthetic resin molded body, and a linear expansion coefficient αCM on the side of abutting the optical device has a linear expansion coefficient αCM. The linear expansion coefficient αOD of the material is such that at least one connection member made of glass satisfying the following relationship is provided. | ΑCM−αOD | <5 × 10 ^-6

With this configuration, the optical fiber terminal is easy to manufacture and is connected to the optical device via the connecting member, so that the connectivity is improved . In addition , the optical fiber terminal portion suppresses thermal expansion and contraction of the synthetic resin constituting the ferrule when the ferrule is molded.

Further , the optical fiber terminal section is connected to the optical device in a short time by using a photo-curing adhesive since light is transmitted through the connection member. Preferably, the ferrule is a molded article made of any of thermosetting, thermoplastic or photocurable synthetic resins.

Thus, the ferrule of the optical fiber terminal is formed at a low cost by using the metal mold. Also preferably, the synthetic resin constituting the ferrule contains silicon dioxide as a coupling agent and a filler. Thereby, the adhesiveness between the ferrule and the glass connecting member is improved in the optical fiber terminal portion.

Furthermore, the synthetic resin constituting the ferrule preferably has a refractive index close to that of the silicon dioxide. More specifically, it is an optically transparent material that does not contain a coloring component or carbon. Thereby, when the optical fiber terminal section is connected to the optical device, the irradiation light is more easily transmitted, and the photocurable adhesive used is cured in a shorter time. In addition, since the irradiation light is less absorbed by the ferrule, heat generation at the end of the optical fiber can be reduced, and the dimensional change of the ferrule due to temperature rise can be suppressed.

At this time, the connecting member has a linear expansion coefficient αCM
However, regarding the linear expansion coefficient αOD of the constituent material of the optical device,
| To a glass that satisfies <5 × 10 ^-6 relationship | αCM-αOD
You .

Thus, the difference in the linear expansion coefficient between the optical fiber terminal and the optical device due to the temperature change over time is small, so that the dimensional change due to the temperature change is kept small, and the connection loss over time is reduced. Such as deterioration of performance and loss of function are suppressed. Further , the connection member has an opening surrounding the periphery of the butt end face of the ferrule, and the opening is N when the number of optical fibers adhered and fixed to the ferrule is N and the arrangement pitch of the optical fibers is P. The length a in the direction orthogonal to the arrangement direction of the optical fibers is 0.2 to 1.
0 mm, and the length b in the arrangement direction is set so as to satisfy the relationship of b = P × (N−1) + a.

Thus, in the optical fiber terminal portion, the area ratio of the connecting member to the entire butting end face is set to an appropriate value.

Further , according to the connection structure of the optical fiber terminal portion and the optical device of the present invention, the optical fiber terminal portion is connected to the optical device so as to face or abut.

In this case, preferably, the optical device is an optical waveguide component on which a plurality of waveguides having the same arrangement pitch as the plurality of optical fibers are formed, and an ultraviolet curing type is provided at a portion of a connection member provided on the ferrule. The connection structure is bonded to the optical fiber terminal part according to any one of claims 1 to 5 by the adhesive. Thereby, the optical fiber terminal and the optical waveguide component are connected in a short time.

[0028]

Here, "optically transparent" as used herein means that the transmittance of visible light and ultraviolet light is at least 10% or more. In addition, various coefficients of linear expansion used in the following description of this specification refer to values at about 20 ° C.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. First Embodiment First, a first embodiment of the present invention will be described in detail with reference to FIGS. As shown in FIG. 1, an optical fiber terminal unit (hereinafter, referred to as a “terminal unit”) 10 according to the present embodiment includes a ferrule 11 and a connecting member 12 and a tape fiber 13 attached thereto. Using a curable adhesive,
The optical waveguide component 20 is abutted and bonded.

The ferrule 11 is formed of an optically transparent synthetic resin having a small heat shrinkage. In the present embodiment, as such a synthetic resin, for example, a mixture of silicon dioxide particles of 70% by weight or more as a filler, the refractive index is substantially equal to the refractive index of silicon dioxide, and the linear expansion coefficient α _FP is 12 ×
A thermosetting epoxy resin of 10 ^-6 was used. Here, a thermosetting synthetic resin, for example, an epoxy resin contains a coupling agent for increasing the adhesive strength between the particles and silicon dioxide particles. Therefore, the adhesiveness with the connection member 12 made of Pyrex glass described later is also high.

As shown in FIGS. 3 and 5, the ferrule 11 is a hollow member having a cavity 11b formed at the rear of the main body 11a, and has a projection 11c at the front which abuts the optical waveguide component 20.
An opening 11 communicating with the cavity 11b is provided at the upper part.
d is formed. The protruding portion 11c has a front end face 11e for abutment with the optical waveguide component 20, and a peripheral groove 11e.
f is formed. A connecting member 12 described later is provided around the concave groove 11f (see FIGS. 1 and 7). Also,
As shown in FIG. 4 and FIG. 5, the protruding portion 11c has four fiber holes which are opened at the butting end face 11e and communicate with the cavity 11b.
11 g are formed. As shown in FIGS. 5 and 7, the protruding portion 11c is provided with a fiber guide 11h which guides an optical fiber 13a to be described later to the fiber hole 11g to improve the insertion property at a position adjacent to each fiber hole 11g. Is formed.

Here, the shapes of the protruding portion 11c and the concave groove 11f are determined by the shape of the opening 12a of the connecting member 12, which will be described later, and the concave groove 11f is not necessarily required. The connecting member 12 is
It is made of Pyrex glass that is optically transparent and has a linear expansion coefficient α _CM of 3.0 to 3.6 × 10 ⁻⁶ , and an optical waveguide component 20 described later.
The waveguide 22a has a linear expansion coefficient α _OD close to the array direction in the arrangement direction. The connecting member 12 has an opening 12a surrounding the periphery of the butt end face 11e, and is formed into a rectangular frame shape to be butt against the optical waveguide component 20 together with the butt end face 11e.

The size of the opening 12a affects the strength and moldability of the connecting member 12, the irradiation time of ultraviolet rays when connecting to the optical waveguide component 20, and the like. Therefore, the length (hereinafter, referred to as “vertical length”) a in the direction orthogonal to the arrangement direction of the optical fibers shown in FIG.
(mm) in the range of 0.2 ≦ a ≦ 1.0, the length b (mm) in the arrangement direction of the optical fibers (hereinafter referred to as “horizontal length”), the number of fiber holes 11g, 13, the number of optical fibers 13a to be described later is N, and the arrangement pitch of the optical fibers 13a is P
(mm), the relationship is set to b = P × (N−1) + a.

Here, if the area of the front portion of the connecting member 12 with respect to the entire butting end surface 11e is small, and therefore the area ratio of the connecting member 12 is smaller than an appropriate value, the filling pressure of the synthetic resin when the ferrule 11 is molded is reduced. As a result, the connecting member 12 is broken, or the connecting member 12 is damaged due to a heat cycle or the like. For this reason, there arise problems such as a decrease in the reliability of the manufactured ferrule 11 and thus the terminal unit 10. In addition, when bonding is performed using a photo-curing adhesive, the irradiation light hardly penetrates to the center of the end face, and it takes time to bond with the optical waveguide component 20.

On the other hand, if the area of the connecting member 12 occupying the entire butt end face 11e is large and the area ratio is larger than an appropriate value, high dimensional accuracy is required for manufacturing the connecting member 12. For this reason, the manufacturing cost of the ferrule 11 and therefore the terminal unit 10 increases. In addition, when the ferrule 11 is formed, if the setting work of setting the connection member 12 in the molding die is not carefully performed, the formed ferrule 11
In this case, the fiber hole 11g is too close to the connection member 12, and troubles such as breakage or bending of the molding pin due to contact occur frequently.

Therefore, in the connection member 12, the opening 12a
Are set as described above. This ferrule 11
It is manufactured using a molding die described below. FIG.
This is a molding die used for manufacturing the ferrule 11, and includes a lower die plate 30, an upper die plate 40, and a core 50 arranged between the two die plates 30, 40. The lower mold plate 30 is moved up and down by driving means (not shown), and the upper mold plate 40 is opened or clamped. As shown in the figure, the lower mold plate 30 is integrally provided with convex portions 30a for positioning the upper mold plate 40 at four corners of a square plate, and a concave portion 30b for disposing the molds 31, 32 in the center.
Are formed. Further, the lower mold plate 30 is provided with runners 30c, 30c from both sides toward the concave portion 30b.

The molding die 31 is a flat plate-shaped member arranged at one side end of the recess 30b.
A V-groove 31a for positioning the tip of 50d is formed.
On the other hand, the molding die 32 is a U-shaped member that is disposed substantially at the center of the recess 30b in which the molding die 31 is disposed and supports a body 50a of the core 50, which will be described later. When the mold is clamped, a cavity (not shown) for forming the ferrule 11 is formed in the front part. The molding die 32 positions a later-described flange portion 50b of the core 50 disposed in the concave portion 30b.

As shown in FIG. 6, the upper mold plate 40 is disposed between the projections 30a of the lower mold plate 30 on both sides of the rectangular plate. Flange portions 40a, 40a are provided integrally with each other.
Are formed in the recess 40b. In FIG. 6, the upper mold plate 40 is shown upside down for clarity of the configuration, and is actually turned upside down as shown by a one-dot chain line to be opposed to the lower mold plate 30. You.

The molding dies 41 and 42 have the same structure as the molding dies 31 and 32 except that a V-groove for positioning a molding pin 50d described later is not formed on the mold clamping surface 41a of the molding dies 41. Therefore, in the following description and drawings, corresponding parts are denoted by the same reference numerals, and detailed description is omitted. As shown in the figure, the core 50 has a flange 50b formed at the rear of the main body 50a, and a core 50c for forming the cavity 11b of the ferrule 11 and a fiber hole 11g formed at the front of the main body 50a. Four molding pins 50d are protrudingly provided.

When manufacturing the ferrule 11,
First, as shown in FIG.
The molds 41 and 42 are arranged in the recess 40b of the upper mold plate 40, respectively. Next, as shown by a dashed line in the figure, the connection member 12
And the connecting member 12 is disposed in the concave portion 30b between the molding dies 31 and 32, and the flange portion 50b is disposed in the concave portion 30b at the rear of the molding die 32. V part
The core 50 is positioned on the lower mold plate 30 while being positioned by the groove 31a.

Next, the lower mold plate 30 is lifted by the driving means (not shown), and the corresponding flange portion 40a of the upper mold plate 40 is arranged between the convex portions 30a, 30a to clamp the mold. As a result, the connecting member 12 and the core 50 are disposed between the concave groove 30b of the lower mold plate 30 and the concave portion 40b of the upper mold plate 40, and the inner portion of the connecting member 12 has the base of each forming pin 50d. A predetermined gap for forming the protruding portion 11c of the ferrule 11 is formed by inserting the end side. The body of the ferrule 11 is provided between the lower mold plate 30 and the upper mold plate 40 between the molding dies 32 and 42 located at the rear of the connection member 12.
A cavity (not shown) for molding 11a is formed.

Thereafter, using the runners 30c, 30c of the lower mold plate 30, the optically transparent epoxy resin mixed with silicon dioxide particles and having a small heat shrinkage rate is injected into the cavity, and is subjected to transfer molding. The ferrule 11 is formed. After the injected epoxy resin is heated and cured, the lower mold plate 30 is lowered to open the mold, and the molded ferrule 11 is taken out.

Thereafter, the core 50 is pulled out of the ferrule 11, and the production of the ferrule 11 is completed. The ferrule 11 manufactured in this manner is processed as the terminal section 10 by inserting a tape fiber from the rear side. That is,
The tape fiber is a ribbon-shaped optical fiber bundle in which a plurality of optical fibers are arranged in parallel at a predetermined pitch, and these optical fibers are coated.

In the terminal section 10 of this embodiment, the end of the tape fiber is treated to remove the coating by a predetermined length, and the exposed individual optical fiber is inserted into the cavity 11 b from the rear side of the ferrule 11. Then, as shown in FIG. 7, the optical fiber 13a of the tape fiber 13 is inserted into the corresponding fiber hole 11g as shown in FIG. 7, and the adhesive A is injected into the cavity 11b from the opening 11d as shown in FIG. The tape fiber 13 is fixed to the main body 11a together with the optical fiber 13a.

Here, the tape fiber 13 is an optical fiber
13a may protrude from the protruding portion 11c, but the protruding optical fiber 13a is subjected to cutting processing so as to be substantially flush with the butting end face 11e, and then the end face is polished together with the butting end face 11e by lapping or the like. . Through these steps, the ferrule 11 is processed into the terminal portion 10. At this time, in the manufactured terminal portion 10, the linear expansion coefficient α _CM of the connecting member 12 is set to be smaller than the linear expansion coefficient α _{FP of the} ferrule 11. For this reason, at the time of high temperature accompanying the molding of the ferrule 11, the connecting member 12 suppresses the expansion of the protrusion 11c in the width direction and the vertical direction, and suppresses the contraction at the time of cooling after the completion of the molding. Therefore, the ferrule 11 has an abutting end face because the expansion and contraction of the protruding portion 11c are suppressed by the connecting member 12.
A fiber hole 11g opening at 11e is formed with high precision.

The plurality of optical fibers 13a exposed by removing the coating are protected by being buried in the adhesive A in the cavity 11b of the ferrule 11 (see FIG. 9). However, there is no disconnection. The terminal unit 10 manufactured in this manner is coated with an ultraviolet-curing adhesive, for example, an epoxy-based or acrylate-based adhesive between the optical waveguide component 20 and irradiated with ultraviolet light in a short time. Glued.

The optical waveguide component 20 is composed of a waveguide layer 22 made of quartz having a thickness of several tens μm on a silicon substrate 21 having a thickness of 1 mm.
Is formed by, for example, a flame deposition method, and is covered with a cover 23 made of Pyrex glass having a linear expansion coefficient close to that of silicon, and has a linear expansion coefficient α _OD of about 2.4 ×.
^10-6 parts, both ends in the longitudinal direction are butt end faces.

Here, in the waveguide layer 22, four waveguides 22a are formed in the longitudinal direction in parallel with the plurality of optical fibers 13a at the same pitch. The cover 23 is an optical waveguide component.
By making the area and shape of the butt end face 20 approximate to the end face of the terminal part 10, an effective bonding area with the terminal part 10 is ensured. Note that the optical waveguide component 20 has a cover 23 only by forming the waveguide layer 22 on the silicon substrate 21.
The waveguide 22a formed in the waveguide layer 22 may be a single waveguide.

At the time of this bonding, the terminal portion 10 and the optical waveguide component
20 is bonded by aligning the corresponding optical fiber 13a and the waveguide 22a in the order of submicron. In the connection structure between the terminal portion 10 and the optical waveguide component 20, the irradiated ultraviolet light passes through the ferrule 11 and the connection member 12, so that
The adhesive cures in a short time. Therefore, in the connection structure between the terminal portion 10 and the optical waveguide component 20, the corresponding optical fiber
In a state where the center 13a and the waveguide 22a are aligned on the order of submicron, as shown in FIG. 9, the ultraviolet ray-curable adhesive _{AUV is} securely bonded to the connection member 12 at the portion.

Further, in the connection structure between the terminal portion 10 and the optical waveguide component 20, the connection member 12 has a linear expansion coefficient α _CM of 3.0 to 3.0.
At 3.6 × 10 ^-6 , the optical waveguide component 20 has a linear expansion coefficient α _OD of about 2.
4 × 10 ⁻⁶ , which satisfies the relationship of | α _CM −α _OD | <5 × 10 ⁻⁶ . For this reason, in the connection structure, since the difference in the linear expansion coefficient between the terminal portion 10 and the optical waveguide component 20 due to the temporal change in temperature is small, the dimensional change due to the temperature change is suppressed to be small. Fiber 13a and waveguide 22
The centering state between a and a is not disturbed. Therefore, by adopting the above-described connection structure, it is possible to prevent a decrease in performance and a loss in function such as a decrease in connection loss between the terminal section 10 and the optical waveguide component 20 over time.

At the time of manufacturing the ferrule 11, the opening 12a of the connecting member 12 made of Pyrex glass was set so that the vertical length a was set to five values in the range of 0.2 to 1.0 mm, and eight fiber holes were formed. Under four different pressures of 90, 150, 200 and 250 kg · f / cm ² , respectively,
Thirty pieces were each formed of the optically transparent epoxy resin mixed with silicon dioxide particles having a small heat shrinkage.

Here, the horizontal length b (mm) of the opening 12a is the number of the fiber holes 11g (= the number of cores of the tape fiber 13) because the arrangement pitch of the fiber holes 11g is set to P = 0.25 mm.
Is N = 8, so that b = P × (N−1) + a was set to 1.95 to 2.75 mm. At this time, in the molded ferrule 11, the relationship between the vertical length a of the opening 12a of the connecting member 12 and the cracking rate (%) of the connecting member 12 is all, and the HC characteristic fluctuation width (d
When the relationship between B) and the pass rate (%) relating to the molding pin trouble was examined for molded articles at 150 kg · f / cm ² , the results shown in FIGS. 10 to 12 were obtained.

Here, the pass rate (%) was determined to be acceptable if there was no trouble such as bending or bending of the molding pin.
It was determined as a percentage of each of the 30 molded ferrules 11. The HC characteristic fluctuation width (dB) shown in FIG. 11 indicates the average HC characteristic fluctuation width per ten ferrules 11 with respect to the vertical length a. Further, 20 ferrules 11 each having a different vertical length a are formed.
10 ferrules randomly extracted from the group
An ultraviolet-curable adhesive was applied between the optical waveguide component 11 and the optical waveguide component 20, and the adhesive was applied by irradiating ultraviolet rays. When the irradiation time (min.) Required for bonding at this time was measured in relation to the vertical length a of the opening 12a, the results shown in FIG. 13 were obtained.

Therefore, from the results shown in FIG. 10 to FIG.
When the ferrule 11 is formed, when the longitudinal length a of the opening 12a exceeds 1.0 mm, the connection member 12 has a cracking rate exceeding 50% and irradiates a photocurable resin used for bonding to the optical waveguide component 20. It can be seen that the time is close to one hour, which is not preferable. If the vertical length a of the opening 12a is smaller than 0.2 mm, the resin filling space at the portion where the fiber hole 11g is formed in the molding die shown in FIG. Therefore, as is clear from the pass rate (%) shown in FIG. 12, troubles such as breakage and bending of the molding pin during molding frequently occur.

Therefore, the vertical length a of the opening 12a is 0.2
It is preferable to set the range to 1.0 mm. Here, the connecting member 12 cannot be said to be an opening in the case where the lateral length b of the opening 12a is the same as the lateral width of the ferrule 11, that is, the connecting member 12 is vertically divided into two parts. However, when the vertical length of the protruding portion 11c of the ferrule 11 was made to correspond to the vertical length a of the opening 12a, the ferrule 11 could be manufactured with a high yield in the same manner as described above.

In the terminal section 10 of the above embodiment, the connecting member 12 is a square frame made of Pyrex glass provided on the side of the butted end face 11e of the ferrule 11. However, it is needless to say that the connection member is not limited to the arrangement of the above-described embodiment as long as the connection member is provided on the side of the butted end face and the ultraviolet ray passes through the connection portion between the terminal portion and the optical waveguide component. Therefore, for example, as shown in FIG. 14, the connection member may be arranged so that the outer periphery of the ferrule 11 is surrounded by the connection member 12 together with the butt end face 11e. Alternatively, as shown in FIG. The prismatic connecting members 12, 12 may be arranged at upper and lower portions of the ferrule 11 corresponding to the bonding portion with the component.

Further, as shown in FIG. 16, the connecting member surrounds the butted end face 11e of the ferrule 11 from above and below. One of the connecting members 14 and 15 has a U-shape and the other has a prismatic shape. As shown in FIG. 17, a prismatic connecting member 16 may be arranged in the width direction above the abutting end face 11e of the ferrule 11. Further, as in a connecting member 17 shown in FIG. 18, a ferrule 11 having two projecting portions 11c is formed.
An opening 18a surrounding the butting end face 11e of the ferrule 11 may have a shape having two openings 17a surrounding the two butting end faces 11e, or a connecting member 18 shown in FIG.
May be provided. Here, the ferrule 11 provided with the connecting member 18 is provided with a plurality of optical fibers on the butt end face 11e.
The ends of 13a are arranged in two rows and exposed.

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

As is apparent from the above description, according to the present invention, an optical fiber terminal which has excellent connectivity with an optical device, is easy to manufacture, and is hardly disconnected, and a method and a method for manufacturing the same. A connection structure for an optical device is provided. At this time, if the linear expansion coefficient α _CM of the connecting member is set to be smaller than the linear expansion coefficient α _FP of the synthetic resin forming the ferrule, the optical fiber terminal portion is configured such that the connecting member has a thermal expansion coefficient of the synthetic resin during molding of the ferrule. And suppress shrinkage. Therefore, the ferrule can form the fiber hole with high accuracy.

When the connecting member is made of an optically transparent material, such as glass, at least partially exposed on the outer periphery of the butt end face of the ferrule, a light-curing adhesive is used for the optical fiber end portion. Thereby, it is possible to connect to the optical device in a short time. Further, when the ferrule is a molded body made of any one of thermosetting, thermoplastic and photocurable synthetic resins, the ferrule of the optical fiber can be molded inexpensively using a mold.

Further, when the synthetic resin containing silicon dioxide constituting the ferrule contains a coupling agent, the adhesiveness between the ferrule and the connecting member made of glass is improved in the optical fiber terminal portion. Further, when the synthetic resin constituting the ferrule has a refractive index close to that of the silicon dioxide and is made of an optically transparent material, the optical fiber terminal portion transmits irradiation light when connected to an optical device. The photocurable adhesive used is cured in a shorter time, and the time required for connection work with the optical device can be reduced. In particular, when the synthetic resin constituting the ferrule is made of a material that does not contain a coloring component or carbon, the absorption of the irradiation light by the ferrule is reduced, so that the heat generation at the optical fiber terminal can be reduced, and the dimensional change of the ferrule due to the temperature rise is reduced. Can be suppressed.

The connecting member has a linear expansion coefficient αCM,
Regarding the linear expansion coefficient αOD of the constituent material of the optical device, | α
Glass satisfying the relationship of CM−αOD | <5 × 10 ⁻⁶ .

As a result, since the difference in the linear expansion coefficient between the optical fiber terminal and the optical device due to the temperature change over time is small, the dimensional change due to the temperature change is kept small, and the connection loss over time is reduced. Such as a decrease in performance and a loss of function can be suppressed. Further, the connection member has an opening surrounding the periphery of the butted end surface of the ferrule, and the opening is N when the number of optical fibers bonded and fixed to the ferrule is N and the arrangement pitch of the optical fibers is P. The length a in the direction orthogonal to the arrangement direction of the optical fibers is 0.2 to 1.
0 mm, and the length b in the arrangement direction is set so as to satisfy the relationship of b = P × (N−1) + a. Thereby, in the optical fiber terminal portion, the area ratio of the connection member occupying the entire butt end face can be set to an appropriate value, and the yield when forming the ferrule is improved.

Further, in the connection structure between an optical fiber terminal portion and an optical device according to the present invention, the optical device is an optical waveguide component in which a plurality of waveguides having the same arrangement pitch as the plurality of optical fibers are formed. If the connecting structure provided in the ferrule is bonded to the optical fiber terminal with an ultraviolet-curing adhesive, the optical fiber terminal and the optical waveguide component can be connected in a short time.

[0080]

[0081]

[Brief description of the drawings]

[1] serve to explain the first embodiment of the connection structure between the optical fiber end portion及 beauty terminal unit and the optical device of the present invention, the connection structure between the optical fiber end portion and the terminal portion and the optical waveguide part FIG.

FIG. 2 is a front view of a connecting member provided on a butt end face side of a ferrule in the optical fiber terminal shown in FIG.

FIG. 3 is a perspective view of a ferrule used for the optical fiber terminal of FIG.

FIG. 4 is a front view of the ferrule shown in FIG. 3;

FIG. 5 is a sectional view of the ferrule shown in FIG. 3;

6 is a perspective view of a molding die used for manufacturing the ferrule shown in FIG.

FIG. 7 is a perspective view showing a state in which a tape fiber is inserted into a ferrule manufactured using the molding die of FIG. 6;

FIG. 8 is a perspective view showing a state in which an adhesive is injected into the ferrule of FIG. 7 to fix a tape fiber to form an optical fiber terminal.

FIG. 9 is a cross-sectional view of a connection structure in which an optical fiber end portion and an optical waveguide component are bonded.

FIG. 10 is a characteristic diagram showing a relationship between a vertical length a of an opening of a connection member and a cracking rate (%) of the connection member in a molded ferrule.

[FIG. 11] Similarly, the vertical length a of the opening of the connection member and the HC characteristic fluctuation width (dB) in the heat cycle (HC) test
FIG. 4 is a characteristic diagram showing a relationship between

FIG. 12 is a characteristic diagram showing a relationship between a vertical length a of an opening of a connection member and a pass rate (%) regarding a molding pin trouble.

FIG. 13 is a characteristic diagram showing a relationship between a vertical length a of an opening of a connecting member in a molded ferrule and an irradiation time of ultraviolet light required for bonding the molded ferrule and the optical waveguide component with an ultraviolet-curable adhesive. It is.

FIG. 14 is a perspective view showing a modification of the optical fiber terminal.

FIG. 15 is a perspective view showing another modification of the optical fiber terminal.

FIG. 16 is a perspective view showing still another modified example of the optical fiber terminal.

FIG. 17 is a perspective view showing a modification of the optical fiber terminal.

FIG. 18 is a perspective view showing another modification of the optical fiber terminal.

FIG. 19 is a perspective view showing still another modification of the optical fiber terminal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Optical fiber terminal part 11 Ferrule 11e Butt end face 11g Fiber hole 12 Connection member 12a Opening 13 Tape fiber 13a Optical fiber 20 Optical waveguide component 21 Silicon substrate 22 Waveguide layer 22a Waveguide 23 Cover 30 Lower mold plate 40 Upper mold plate 50 Medium Child 50a Forming pin

──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. Hei 6-8162 (32) Priority date January 28, 1994 (28 Jan. 1994) (33) Priority claim country Japan (JP) (72) Inventor Shiro Nakamura 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Inventor Tomohiro Watanabe 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72 ) Inventor Kazuya Fukazawa 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd. (56) References JP-A-5-34543 (JP, A) JP-A-5-3345 (JP, A) JP-A-4-212113 (JP, A) JP-A-4-190309 (JP, A) JP-A-4-98207 (JP, A) JP-A-3-179405 (JP, A) (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB G02B 6/30 G02B 6/24 G02B 6/42

Claims (7)

(57) [Claims] An optical fiber has an abutting end face facing or abutting with an optical device and a single fiber hole or a plurality of fiber holes formed in parallel at a predetermined pitch, and one end of an optical fiber is inserted into each of the fiber holes. An optical fiber terminal part, wherein the optical fiber is optically connected to an optical device, wherein the ferrule is made of a synthetic resin molded product,
A linear expansion coefficient αCM is provided on the end face side of the butt with the device, and a linear expansion coefficient αOD of a constituent material of the optical device is provided, and at least one connection member made of glass satisfying the following relationship is provided. Fiber optic terminal. | ΑCM−αOD | <5 × 10 ^-6 2. The connecting member has an opening surrounding the butted end face of the ferrule, wherein the opening is N, the number of optical fibers bonded and fixed to the ferrule is P, and the arrangement pitch of the optical fibers is P. The length a in the direction perpendicular to the arrangement direction of the optical fibers is 0.2 to 1.0 mm, and the length b in the arrangement direction satisfies the relationship of b = P × (N−1) + a. Item 1. The optical fiber terminal section according to Item 1. 3. The optical fiber terminal according to claim 1, wherein the ferrule is a molded body made of any one of thermosetting, thermoplastic and photocurable synthetic resins. 4. The synthetic resin constituting the ferrule,
4. The optical fiber terminal according to claim 3, wherein said optical fiber terminal comprises silicon dioxide as a coupling agent and a filler. 5. The synthetic resin constituting the ferrule,
5. The optical fiber end of claim 4, wherein the refractive index is close to the refractive index of the silicon dioxide and is optically transparent. 6. A connection structure between an optical fiber terminal and an optical device, wherein the optical fiber terminal according to any one of claims 1 to 5 is connected to the optical device so as to face or face the optical device. 7. The optical device, wherein the optical device is an optical waveguide component on which a plurality of waveguides having the same arrangement pitch as the plurality of optical fibers are formed, and a part of a connecting member provided on the ferrule is applied to an ultraviolet curing adhesive. it is connected with Rihikari fiber terminal portion, the connecting structure between the optical fiber end portion and the optical device of claim 6.