JPH05196835A - Connecting structure of optical fiber and optical waveguide circuit - Google Patents

Abstract

PURPOSE:To provide the connecting structure of optical fibers and an optical waveguide circuit which is simple and has a stable connecting characteristic. CONSTITUTION:The connecting structure of the optical waveguide circuit 2 formed on a substrate 1 and the optical fibers 3 is constituted by tightly adhering the end faces of the optical fibers disposed and fixed on a fixing member 10 and the end face 1' of the substrate formed with the optical waveguide circuit 2 to be optically connected via a gelatinous refractive index matching agent 11 and fixing both flanks of the fixing member 10 disposed and fixed with the optical fibers 3 and the extended surface of the end face 1' of the substrate formed with the optical waveguide circuit 2 by adhesives 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection structure between an optical fiber used in an optical circuit component for optical communication and an optical waveguide circuit.

[0002]

2. Description of the Related Art Conventionally, in connection between an optical fiber used for an optical circuit component for optical communication and an optical waveguide circuit, a connection structure as shown in FIG. 4 has been taken as an example. 1 is the substrate
1'is an end face of a substrate on which the optical waveguide circuit to be optically connected to an optical fiber is formed, 2 is an optical waveguide circuit formed on the substrate 1, 3 is an optical fiber, 4 is the optical waveguide circuit 2 and the optical fiber. A reinforcing plate member for connecting and fixing 3 and 4'is an end face of the reinforcing plate member 4, and 5 is a reinforcing glass pipe for connecting and fixing the optical waveguide circuit 2 and the optical fiber 3 similarly. , 6 is an adhesive for connection and fixing, 7 is a case for mounting the optical waveguide circuit 2, 8 is an optical fiber outlet, and 9 is a fixing agent for fixing the optical fiber 3 to the case 7.

In such a connection structure, the connection is made by the following procedure. First, the reinforcing plate member 4 is arranged on the substrate 1 on which the optical waveguide circuit 2 is formed. At this time, the end face 1'of the substrate and the end face 4'of the reinforcing plate member 4 are preliminarily aligned using a jig or the like so that they are flush with each other, and then the reinforcing plate member 4 is attached to the substrate with an adhesive or the like. 1 or the reinforcing plate member 4 is mounted and fixed so that the end face 4'is substantially aligned with the end face 1'of the substrate 1, and then both end faces 1'and 4'are polished. Next, the optical fiber 3 inserted into the reinforcing glass pipe 5 is held by a jig or the like, and the optical axis is adjusted so that the optical coupling between the optical fiber 1 and the optical waveguide circuit 2 is optimum. After the adjustment, the reinforcing glass pipe 5 and the optical fiber 3 are tightly fixed to the end face 1'of the substrate and the end face 4'of the reinforcing plate member 4 with an adhesive 6 such as an ultraviolet curable resin. At this time, the optical fiber 3 is also held and fixed in the reinforcing glass pipe 5.
After the connection is completed, the optical waveguide circuit 2 is mounted and fixed in the case 7, and the optical fiber 3 is held and fixed in the outlet 8 of the case 7 with a fixing agent 9 such as an adhesive.

The reinforcing plate member 4 and the reinforcing glass pipe 5 are used as described above for the following reasons.
Normally, the optical waveguide circuit 2 is formed in a thin region of a few microns to a few tens of microns or less from the upper surface of the substrate 1, so that the optical fiber 3 having an outer diameter of 125 microns is directly attached to the end face of the substrate.
However, even though the adhesive area of the end face of the optical fiber was originally small, most of the clad portion above the core portion of the optical fiber was not adhered and fixed to the end face of the substrate, and sufficient adhesive strength was not obtained. Therefore, in order to increase the bonding area and obtain sufficient bonding strength, the reinforcing plate member 4 is arranged on the upper surface of the substrate and the reinforcing glass pipe 5 is arranged around the optical fiber.

[0005]

However, in the conventional method, the substrate end face 1'and the end face 4 of the reinforcing plate member 4 are aimed at strengthening the connection and fixation between the optical waveguide circuit 2 and the optical fiber 3. Since the steps of aligning and polishing the end faces using a jig as described above are required to make ′ flush with each other, there is a drawback that assembly workability is poor. Further, when the optical waveguide circuit 2 mounted and fixed to the case 7 is used in an environment where the temperature changes, the optical fiber 3 and the optical fiber 3 are guided due to the difference in thermal expansion coefficient between the substrate 1, the optical fiber 3, the case 7 and other components. There is also a drawback that separation occurs at the connection boundary with the wave circuit 2 and the optical characteristics deteriorate.

Similar problems occur even when the optical fibers are arrayed, and in addition, since it is necessary to individually adjust and fix a plurality of optical fibers, there are problems such as low fiber array density and poor workability. It was

The present invention has been made in view of the above circumstances, and an object thereof is to provide a connection structure which is simple and has stable connection characteristics in connection between an optical fiber and an optical waveguide circuit.

[0008]

In order to solve the above-mentioned problems, the present invention uses an optical fiber which is previously arranged and fixed in a member for connecting an optical fiber formed on a substrate and an optical waveguide circuit. The optical waveguide circuit to be connected and the end face of the optical fiber are closely contacted with each other via a refractive index matching agent, and both side surfaces of the member and the extension surface of the end face of the substrate on which the optical waveguide circuit is formed are fixed with an adhesive. That is the most main feature.

It differs from the prior art in that the optical fiber and the optical waveguide circuit are adhered to each other via a gel-like refractive index matching agent.

As described above, since the optical fiber and the optical waveguide circuit are in close contact with each other via the gel-like refractive index matching agent, a simple and stable connection characteristic can be achieved.

[0011]

The present invention will be described in more detail below with reference to the drawings, but the embodiments disclosed below are merely examples of the present invention and do not limit the scope of the present invention.

(Embodiment 1) FIG. 1 is a diagram for explaining a first embodiment of the present invention. 1 is a substrate, 1'is a substrate end face on which the optical waveguide circuit to be optically connected to an optical fiber is formed, 2
Is an optical waveguide circuit (array) formed on the substrate 1, 3 is an optical fiber (array), 10 is a fiber fixing member when there is a single optical fiber, and each optical fiber has a predetermined pitch when there are a plurality of optical fibers The fiber array fixing member arranged and fixed at 11 is a gel-like refractive index matching agent interposed between the substrate end face 1'and the optical fiber end face, and 12 is a connecting and fixing adhesive. Although FIG. 1 is a diagram in which a plurality of optical waveguide circuits and optical fibers are arranged in an array, it goes without saying that the same configuration is obtained even in the case of a single device.

The process for connecting and fixing the optical waveguide circuit 2 and the optical fiber 3 shown in FIG. 1 is as follows. First, a refractive index matching agent 11 is applied to the end facet 1'of the substrate on which the optical waveguide circuit 2 is formed, and the refractive index matching agent 11 is applied to the fiber fixing member 10 and the refractive index matching agent 11 so as to be in close contact with each other. The relative position of the fiber fixing member 10 is adjusted so that the efficiency is maximized.
After the adjustment is completed, the substrate end surface 1'and the side surface of the fiber fixing member 10 are fixed with the adhesive 12 as shown in FIG. Here, the application of the refractive index matching agent 11 is not limited to the end face of the substrate, but may be applied to the fiber fixing member or both.

In the optical fiber fixing member 10, the optical fiber 3 is fixed to the fixing member 10 with an adhesive. Usually, the linear expansion coefficients of the three types of members do not often match, and it is often difficult to match them in terms of material selection. Therefore, when the optical circuit of FIG. 1 undergoes environmental temperature change, each of the three types of members thermally expands and contracts, and as a result, the optical fiber 3 is pulled in the optical axis direction at the end face of the fiber fixing member 10. Shows a sticking out phenomenon. However, since the gel-like refractive index matching agent 11 is interposed in the connecting portion between the optical fiber 3 and the optical waveguide circuit 2, the optical connection state is maintained even if the minute pull-in or stick-out phenomenon of the optical fiber occurs repeatedly. The peeling does not occur, and the optical connection reliability is improved.

When the optical fiber fixing member 10 and the optical waveguide circuit 2 are connected and fixed, an ultraviolet curable resin is desirable from the viewpoint of workability.

(Embodiment 2) FIG. 2A is a diagram for explaining a second embodiment of the present invention. 1 is a substrate, 1'is a substrate end face on which the optical waveguide circuit to be optically connected to an optical fiber is formed, 2 is an optical waveguide circuit (array) formed on the substrate 1,
3 is an optical fiber (array), 10 is a fiber fixing member when there is a single optical fiber, when there are a plurality of optical fibers, a fiber array fixing member that arranges and fixes each optical fiber at a predetermined pitch, and 11 is a substrate end face 1 ' Is a gel-like refractive index matching agent interposed between the end face of the optical fiber, 12 is an adhesive for connecting and fixing, and 13 is a groove provided on the surface of the fiber fixing member 10 to be joined to the end face 1'of the substrate.

In the embodiment shown in FIG. 2A, the groove 13 prevents the refractive index matching agent 11 from invading the adhesive interface between the substrate 1 and the adhesive 12 for connecting and fixing the substrate 1 and the fiber fixing member 10. It has the effect of preventing the deterioration of the adhesive strength.

FIG. 2B shows an example of a groove provided on the surface of the fiber fixing member 10 that is joined to the end face 1'of the substrate, and shows a case where it is formed on both sides of the optical fiber 3. Figure 2
(C) shows the case where the groove 13 is formed on the upper, lower, left and right sides of the optical fiber 3. In any case, the refractive index matching agent 11 is present only between the substrate end surface 1 ′ and the end surface of the fiber fixing member 10 on the optical fiber 3 inside the groove on the surface where the groove 13 is formed and in the vicinity thereof. Become.

It goes without saying that the pattern shape and the shape in the depth direction of the groove 13 may be formed according to the number of arrays of the optical fibers 3 and the amount of the refractive index matching agent 11.

(Embodiment 3) FIG. 3A is a diagram for explaining a third embodiment of the present invention. 1 is a substrate, 1'is a substrate end face on which the optical waveguide circuit to be optically connected to an optical fiber is formed, 2 is an optical waveguide circuit (array) formed on the substrate 1,
3 is an optical fiber (array), 10 is a fiber fixing member when there is a single optical fiber, when there are a plurality of optical fibers, a fiber array fixing member that arranges and fixes each optical fiber at a predetermined pitch, and 11 is a substrate end face 1 ' And a gel-like refractive index matching agent interposed between the optical fiber and the end face of the optical fiber, 12 is an adhesive for connecting and fixing, 13 is a groove provided on the surface of the fiber fixing member 10 to be joined to the end face 1'of the substrate, 14 and 14 ′ Is a reinforcing connecting member A fixed on the upper surface of the substrate 1 and the optical fiber fixing member 10, 15 and 15 ′ is a reinforcing connecting member B fixed on the lower surface of the substrate 1 and the optical fiber fixing member 10, and 16 is It is a gap between the reinforcing connecting member and the optical fiber fixing member 10.

In the embodiment of FIG. 3 (a), in order to increase the connection strength between the optical fiber 3 and the substrate 1 of the embodiment of FIG. 2 (a), the reinforcing connecting members 14 and the reinforcing connecting members 15 are connected. Member B is added. The reinforcing connecting members A and B are fixed to the substrate 1 and the optical fiber fixing member 10 with an adhesive, respectively.

FIG. 3B shows a structural cross-sectional view taken along the plane P-P 'in FIG. 3A, which corresponds to the case where the substrate 1 and the optical fiber fixing member 10 have the same thickness. It is the same as in the case of FIG. 2A that the refractive index matching agent 11 is prevented from entering the adhesive fixing surfaces of the reinforcing connecting member and the substrate 1 and the optical fiber fixing member 10, as shown in FIG. In the case of b), the groove pattern on the end face of the optical fiber fixing member is preferably the groove shown in FIG.

FIG. 3C shows a sectional view of the optical fiber fixing member 10 having a larger thickness than the substrate 1.
Here, the reinforcing connecting members 14 'and 15' and the optical fiber fixing member 10 are prevented so that the refractive index matching agent 11 does not penetrate into the adhesive fixing surfaces of the reinforcing connecting member and the substrate 1 and the optical fiber fixing member 10. A gap 16 is provided between and. Therefore, in the case of FIG. 3C, the groove shown in FIG. 2B may be used.
Needless to say, even if the substrate 1 is thicker than the optical fiber fixing member 10, it can be similarly reinforced by changing the shape of the reinforcing connecting member.

The material of the reinforcing connecting members A and B is the substrate 1
It goes without saying that it can be freely selected according to the materials of the fiber fixing member 10 and the fiber fixing member 10. By adding the reinforcing connecting members A and B as shown in the figure, the bonding strength between the substrate 1 and the optical fiber fixing member 10 can be significantly increased, and the connection reliability can be improved.

[0025]

As described above, in the connection structure of the present invention, since the gel-like refractive index matching agent is interposed at the connecting portion between the optical fiber and the optical waveguide circuit, the fine drawing of the optical fiber. Or even if the protrusion phenomenon occurs repeatedly,
No peeling occurs in the optical connection state, and the reliability of optical connection is improved. Further, there is an advantage that the connection characteristics can be further stabilized by preventing the refractive index matching agent from entering the adhesive fixing portion between the substrate and the optical fiber fixing member and introducing the reinforcing connecting member.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of a connection structure between an optical fiber array and an optical waveguide circuit of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of a connection structure between an optical fiber array and an optical waveguide circuit of the present invention.

FIG. 3 is a configuration diagram showing a third embodiment of a connection structure between an optical fiber array and an optical waveguide circuit of the present invention.

FIG. 4 is a perspective view showing an example of a conventional connection structure between an optical fiber and an optical waveguide circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 1 '... Substrate end face on which the optical waveguide circuit to be optically connected to an optical fiber is formed, 2 ... Optical waveguide circuit (array) formed on the substrate 1, 3 ... Optical fiber (array),
10 ... A fiber fixing member when a single optical fiber is provided, a fiber array fixing member which arranges and fixes each optical fiber at a predetermined pitch when a plurality of optical fibers are provided, 11 ... Interposed between the substrate end face 1'and the optical fiber end face. A gel-like refractive index matching agent, 12 ... an adhesive for connection and fixing, 13 ...
14 and 14 '... Reinforcing connection member A fixed to the upper surface of the substrate 1 and the optical fiber fixing member 10, 15 and 15' ... Reinforcing connection member B fixed to the lower surface of the substrate 1 and the optical fiber fixing member 10, 16 ... A gap between the reinforcing connecting member and the optical fiber fixing member 10.

Claims (4)

[Claims] 1. A connection structure between an optical waveguide circuit formed on a substrate and an optical fiber, wherein an end face of the optical fiber fixed to a member and an end face of the substrate on which the optical waveguide circuit is to be optically connected are formed. It is closely contacted through a gel-like refractive index matching agent, and both side surfaces of the member on which the optical fiber is arranged and fixed and an extension surface of the end surface of the substrate on which the optical waveguide circuit is formed are fixed by an adhesive agent. A connection structure between an optical fiber and an optical waveguide circuit. 2. The optical fiber and optical waveguide circuit connecting structure according to claim 1, wherein the optical fiber of the optical fiber fixing member is on the same surface as the optical fiber end surface where the optical fiber is arranged and fixed. A connection structure between an optical fiber and an optical waveguide circuit, characterized in that grooves are formed on at least both sides of the end face on which the optical fiber is arranged. 3. The connection structure of an optical fiber and an optical waveguide circuit according to claim 2, wherein the predetermined region on the upper surface of the fixing member of the optical fiber and the waveguide circuit in the substrate center direction from the end face of the optical waveguide circuit substrate. And a predetermined region on the back surface of the substrate on which the optical waveguide circuit is formed in the substrate center direction from the end face of the fiber and the end face of the substrate. A connection structure between an optical fiber and an optical waveguide circuit, which is characterized by being connected and fixed. 4. The connection structure of an optical fiber and an optical waveguide circuit according to claim 1, 2 or 3, wherein the optical fibers are arranged and fixed in an array at a predetermined interval in the optical fiber fixing member. Structure for connecting optical fiber and optical waveguide circuit.