JP2003255179A - Optical connector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical connector which enables a plurality of optical fibers to be connected to and disconnected from an optical module constituted based on a plane substrate type optical waveguide circuit. <P>SOLUTION: A bare optical fiber has a coating removed nearby the tip of optical fibers 2 so as to connect the optical fibers 2 to a plane substrate type optical waveguide 1 and the optical connector has a guide member 3 for aligning the inserted bare optical fibers 2 with the optical waveguide 1 at an end of the plane substrate 1a, optical fibers 2 constituting of 16 lines being provided, the end surfaces of the optical waveguide and optical fibers 2 slanting at a specified angle to a surface perpendicular to the optical axis, and a refractive index matching agent 4 being provided between the end surface of the optical waveguide 1 and the end surfaces of the optical fibers 2. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an optical waveguide / optical fiber connector for connecting an optical fiber and a flat substrate type optical waveguide, and an object thereof is to form a flat substrate type optical waveguide circuit. The purpose is to make the connection of a plurality of optical fibers to the optical module detachable.

[0002]

2. Description of the Related Art At present, with the rapid spread of the Internet, there is an increasing demand for a broadband network system capable of transmitting a huge amount of information such as moving images and music in a short time. Therefore, in the future, it is expected that the optical network based on the optical fiber communication will be expanded in order to realize such a high performance network.
In order for the optical network to become widespread, it is indispensable to improve the performance and economy of various optical devices such as various optical components or optical transmission / reception devices and optical switching devices configured using them.

Optical modules such as an optical transmitter / receiver, an optical distributor, an optical exchanger, and a wavelength multiplexer / demultiplexer, which are basically composed of an optical circuit based on a flat plate type optical waveguide, are important optical components for various optical devices. It is a part. Hereinafter, the flat plate type optical waveguide will be simply referred to as an optical waveguide. An optical fiber is usually connected to these optical modules in order to input and output an optical signal to the outside.

Conventionally, a permanent connection using an adhesive or a fusion bonding method is mainly used for connecting an optical module and an optical fiber, in other words, connecting an optical waveguide and an optical fiber.
Connection and disconnection cannot be repeated. Therefore, the optical module must be mounted on the printed circuit board with the optical fiber connected, which hinders the mounting of the optical module itself and other components, and causes a high mounting cost. It was

The connection between the optical module and the optical fiber is removable, in other words, if it is made into a connector, the optical module can be mounted on the printed circuit board without the optical fiber, and the optical fiber is connected at any time. be able to. As a result, the optical module itself and other optical components can be easily mounted on the printed board, and the mounting cost can be reduced.

Therefore, in recent years, several optical fiber / optical waveguide connectors have been invented for the purpose of making the connection between the optical module and the optical fiber detachable.
Hereinafter, the optical fiber / optical waveguide connector will be simply referred to as a connector. Japanese Patent Application No. 8-77282 describes a connector particularly suitable for connecting a plurality of optical fibers and an optical waveguide.

As shown in FIG. 4, this connector is roughly provided at the end of the optical waveguide substrate 1a, and has a receptacle 6 composed of a receptacle housing 6a and a guide member 3, a plurality of optical fibers 2 and a plug housing 7.
It consists of a. In the plug 7, the optical fiber 2 is a bare fiber whose coating is removed, and is fixed to the plug housing 7a in a cantilevered state.

Here, the optical fiber 2 is protruded by an appropriate length (ΔL) with respect to the tip of each end 7a. The guide member 3 has an inner diameter corresponding to the outer diameter of the optical fiber 2 and a fiber insertion hole 3a having an interval corresponding to the interval of the optical waveguide 1, and the center axis of the optical waveguide 1 and the fiber insertion hole 3a. The optical waveguide substrate 1 so that the central axis thereof coincides.
It is attached to the end face of a. The end faces of the optical fiber 2 and the optical waveguide 1 are processed into flat faces that are perpendicular to the optical axis direction.

When the plug 7 is inserted and fitted into the receptacle 6, the optical fiber 2 is inserted into the fiber insertion hole 3a, the end face of the optical fiber 2 abuts against the end face of the optical waveguide 1, and the optical waveguide 1 and the optical fiber 2 are connected. Are connected. At this time, since the end face of the plug 7 and the end face of the optical fiber 2 abut against the end face of the optical waveguide substrate 1a, the optical fiber 2
Based on the protrusion (ΔL) of the optical fiber 2 the plug 7
Buckles and bends in the cavity of the.

The end face of the optical fiber 2 and the optical waveguide 1 are caused by the elastic force of the optical fiber 2 which tends to extend to the original length.
The end face of is pressed with an appropriate load. As a result, the end face of the optical fiber 2 and the end face of the waveguide 1 are in close contact with each other,
That is, a PC (Physical Contact) is realized. Then, when light propagates from the optical waveguide 1 to the optical fiber 2 or from the optical fiber 2 to the optical waveguide 1, the power of the reflected return light generated at both end faces becomes very small. In other words,
The return loss is high. Here, the power of the guided light propagating to the connector portion in a certain direction is P1, and the power of the waveguide light reflected in the connector portion and returning in the opposite direction is P.
Assuming 2, the return loss is -10log (P2 / P1)
Is defined as

In this connector, the bare optical fiber 2 is used.
Since the optical fibers 2 are accommodated in the plug 7, the optical fibers 2 can be spatially arranged at a high density, and the connector can be made smaller than the number of optical fibers 2 (the number of connection cores) that can be collectively connected. It is possible. In this connector, the pressing force (buckling force) in the axial direction due to the buckling of the optical fiber 2 is usually set to about 0.7N in consideration of surely realizing the PC. Therefore, when the number of connecting cores is as large as 16 cores, the total buckling force becomes as large as about 11 N, and when trying to achieve a connection exceeding several tens of cores or 100 cores, the total sum of the buckling forces becomes large. Reaches several 10N.

Therefore, when the number of connecting cores exceeds 16 and is large, not only is the reliability (environmental resistance, long-term reliability, etc.) of the connector concerned, but also the optical waveguide substrate 1a is affected by the load. There is a possibility that stress will occur and change the optical characteristics of the optical circuit on the optical waveguide substrate 1a. In order to secure the reliability of the connector, a measure to increase the cross-sectional area of the members and the joint area between the members can be considered, but there is a drawback that the size of the connector becomes large.

[0013]

In recent years, in optical modules such as wavelength multiplexer / demultiplexer modules and thermo-optic effect type optical switch modules using a waveguide type diffraction grating, 12
More than 100 channels such as 8 channels have been developed. As described above, it is difficult to apply the above connector to make the optical fiber connection to the super multi-channel type optical module into a connector.

Further, in order to realize the PC with an appropriate pressing force, the surface roughness of the end face of the optical waveguide 1 and the end face of the optical fiber 2 is sufficiently small, and the angle error of both end faces with respect to an ideal right-angled surface is also present. It needs to be small enough. That is, in all of the optical fibers 2 fixed to the plug 7, the angle error of the end face needs to be less than or equal to a predetermined value.

Normally, the end faces of the optical fibers 2 are formed by polishing. However, the larger the number of the optical fibers 2 of the plug 7, the lower the yield in which the angular errors of all the end faces are below a predetermined value. Occurs. Now, as a basic connection configuration for permanent connection or connector connection between the optical waveguide and the optical fiber, (1) the optical waveguide end face and the optical fiber end face are right-angled faces, and a refractive index matching agent is provided between both end faces. Structure, (2) Both end surfaces are right-angled surfaces, and PC on both end surfaces
In the conventional configuration, (3) both end surfaces are slanted surfaces and a refractive index matching agent is provided between both end surfaces, and (4) both end surfaces are slanted surfaces and PCs on both end surfaces are realized. More commonly known.

Here, the "perpendicular surface" is a surface perpendicular to the optical axis, and the "oblique surface" is several degrees (typically 8 degrees) with respect to the surface perpendicular to the optical axis. Degree) It is an inclined surface. The refractive index matching agent is a transparent resin that has a refractive index similar to that of the core of the optical waveguide and the core of the optical fiber, and is, for example, silicone or an adhesive that satisfies the above conditions. The purpose of using such a connection structure is to ensure a low connection loss and a high return loss when the optical waveguide and the optical fiber are connected.

Specifically, it is possible to realize PCs on both end surfaces,
The reason for using a refractive index matching agent is that when air is present between both end faces, a relatively large Fresnel reflection occurs at the optical waveguide end face / air boundary or air / optical fiber end face with a large difference in refractive index, and the return loss decreases. Because it does. Also,
The both end surfaces are inclined because the propagating light reflected by the end surface of the optical waveguide or the end surface of the optical fiber is not coupled to the waveguide mode but becomes a radiation mode to be radiated or absorbed to the outside.

When both end surfaces are slanted surfaces, a relatively high return loss can be secured without using a refractive index matching agent and without realizing PC on both end surfaces, but the power of the propagating light due to the Fresnel reflection. This causes a loss and increases the connection loss. When the connection configuration of (1) is used, if the refractive index of the refractive index matching agent changes due to temperature change, Fresnel reflection on the end face of the optical waveguide or the end face of the optical fiber increases, and the return loss may deteriorate. As a connector using this connection configuration, a connector applying an MT type optical connector as shown in FIG. 5 has been devised.

This connector has a guide pin 1 positioned by a V groove 10 formed on an optical waveguide substrate 1a.
It has an MT type ferrule 13 having guide holes 12 corresponding to one and a plurality of optical fibers 2 and guide pins 11. The ferrule 13 is connected to the guide pin 11 and the end face of the ferrule 13 is abutted against the end face of the optical waveguide 1 for connection. At this time, silicone as a refractive index matching agent is filled between the both end faces.
In this connector, it is difficult to control the depth and position of the V groove 10 for positioning the guide pin 11 with high accuracy, and it is practically difficult to realize reproducible and low loss connection for each connector. It is believed that there is.

Further, since the ferrule 13 is generally manufactured by molding, when the number of connecting cores exceeds 16 cores, the position of the hole for passing the fiber in the ferrule 13 can be made sufficiently accurate. It is expected that it will become difficult and the connection loss will increase. The distance between the optical fibers in the ferrule 13 is usually 0.25 mm, and it is considered difficult to reduce the distance to about 0.127 mm. The connector shown in FIG. 4 uses the connection configuration of (2). Also, FIG.
In this connector, if the ferrule 13 is pressed toward the end face of the optical waveguide 1 with an appropriate load, such a connection configuration can be realized.

In this connection structure, as described above, when the number of connection cores is large, the total pressing force applied to the optical fiber 2 becomes large, which may impair the reliability of the connector itself or the optical module. The connection structure of (3) can be realized by making the end face of the plug 13 including the end face of the optical fiber 2 and the end face of the optical waveguide 1 oblique in the connector shown in FIG.

However, in this connector, as described above, when the number of connecting cores increases beyond about 16 cores, it is considered difficult to secure a sufficiently low connection loss in reality. On the other hand, as a permanent connection method using the connection structure of (3), as shown in FIG. 6, the end faces of the optical waveguide 1 and the end faces of the fiber blocks 14 are made to be slanting faces, and the fiber blocks 14 are adhered by UV curing adhesive. The method is known. Here, the UV curable adhesive has a refractive index matched with that of the optical waveguide and the optical fiber.

The fiber block 14 is a glass block in which a plurality of optical fibers are embedded in an aligned state. The connection configuration of (4) is realized by making the end face of the ferrule 13 and the end face of the optical waveguide 1 oblique in the connector shown in FIG. 5 and pressing the ferrule 13 toward the end face of the optical waveguide 1 with an appropriate load. can do. Further, in the connector shown in FIG. 4, the end faces of the optical waveguide 1 and the optical fiber 2 can be realized as an inclined face.

However, even with this configuration, if the number of connection cores is increased, the above-mentioned problems will occur. As described above, a connector for connecting an optical waveguide and an optical fiber having a single core to about 12 cores has been conventionally developed.
It has been difficult to practically realize a connector connection of more than 6 fibers and several tens to 100 or more fibers. Currently, development of an optical module which requires optical fiber connection of several tens to more than 100 fibers is in progress, and an invention of an optical waveguide / optical fiber connector capable of super multi-fiber connection to this extent has been desired.

The present invention has been made in order to solve such a problem, and an object thereof is to realize an ultra-multicore connection from about 16 cores to more than 100 cores, and to provide connection characteristics and reliability. Is to provide an optical waveguide / fiber optic connector that is good and low in manufacturing cost.

[0026]

The optical connector according to claim 1 of the present invention which achieves the above object has a coating near the tip of the optical fiber in order to connect the optical fiber and the flat substrate type optical waveguide. An optical connector having a removed bare fiber and having a guide member for aligning the inserted bare fiber with respect to the optical waveguide at an end of the flat plate substrate, the optical fiber having 16 or more optical fibers, The end faces of the optical waveguide and the optical fiber are inclined at a predetermined angle with respect to a plane perpendicular to the optical axis, and a refractive index matching agent is provided between the end face of the optical waveguide and the end face of the optical fiber. .

An optical connector according to a second aspect of the present invention which achieves the above object is the optical connector according to the first aspect, wherein the end face of the optical waveguide and the end face of the optical fiber are on the plane of the flat plate substrate with respect to a plane perpendicular to the optical axis. The optical connector according to claim 1, wherein the optical connector is inclined at a predetermined angle with a straight line as an axis.

The optical connector according to claim 3 of the present invention which achieves the above object is the optical connector according to claim 1 or 2, wherein the guide member is made of glass and the refractive index matching agent is an ultraviolet curable adhesive. Is characterized by. An optical connector according to claim 4 of the present invention, which achieves the above object, comprises claim 1 or 2.
In the above, the predetermined angle is about 8 degrees.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail based on embodiments.

First Embodiment FIG. 1 shows a first embodiment of the connector according to the present invention. The figure (a) shows the state of the connector before connection, and the figure (b) shows the state of the connector after connection. Further, FIG. 3C is an enlarged side view and a sectional view of the guide member 3 and its vicinity in FIG.

This connector has 32 connectors on the optical waveguide substrate 1a.
This is a connector for collectively connecting the optical waveguide 1 of one book and the optical fiber 2 of 32 books. Roughly, it consists of a receptacle housing 6a, a guide member 3 and a lock spring 8,
And the receptacle 6 provided at the end of the optical waveguide substrate 1a,
And the plug 7 in which the optical fiber 2 is aligned and fixed in the plug housing 7a. In FIGS. 1A and 1B, the optical waveguide 1, the optical fiber 2 and the like are illustrated with some parts omitted.

In the plug 7, the optical fiber 2 is a bare fiber 2a with the coating removed, and is fixed to the plug housing 7a in the state of forming a cantilever.
The tip of the optical fiber 2 projects to some extent with respect to the tip of the plug housing 7a. The optical waveguide 1 and the optical fiber 2 are arranged at 0.127 mm intervals. In the portion having the coating of the optical fiber 2 on one side of the plug 7, the optical fibers 2 are arrayed (taped) by a coupling agent.
The optical fiber 2 array formed into a tape is vertically stacked in two stages.

The guide member 3 has an inner diameter corresponding to the outer diameter of the optical fiber 2 and a fiber insertion hole 3a having an interval corresponding to the interval of the optical waveguide 1, and the central axis of the optical waveguide 1 and the fiber insertion hole 3a. So that the central axis of the hole 3a coincides,
It is mounted on the end facet 1b of the optical waveguide substrate. The glass block 5 is bonded onto the optical waveguide 1 to reinforce the optical waveguide end face 1b.

The two lock springs 8 are rotatably mounted at symmetrical positions on the receptacle housing 6a. The lock spring 8 is made of a metal wire, has a bent structure, and can elastically change its entire length. The end surfaces of the optical waveguide 1 and the optical fiber 2 are flat surfaces as shown in FIG. 1C, but both are at a predetermined angle with respect to a surface perpendicular to the optical axis direction, for example, as a typical value. Is tilted by 8 degrees. Along with this, the end surface of the guide member 3 is also inclined by the same angle.

When the plug 7 is inserted into the receptacle 6,
Each optical fiber 2 is inserted into the corresponding insertion hole of the guide member 3, and the end face of the optical fiber 2 is the end face of the optical waveguide 1.
Each optical waveguide 1 and the optical fiber 2 are connected to each other by contacting or very close to b. Figure 1 to maintain the connection
As shown in (b), the lock spring 8 is closed and hooked on the plug housing 7a to couple the receptacle 6 and the plug 7 together. In this state, the lock spring 8 presses the plug 7 toward the optical waveguide end face 1b with a certain load. However, the load is smaller than the load at which the bare fiber 1b outside the guide member 3 buckles, and is a load sufficient to maintain the connection.

Since the respective optical fiber end faces 2b are not always located on the same plane, some optical fiber end faces 2b contact the optical waveguide end face 1b at the time of connection, but other optical fiber end faces 2b. 2b comes very close to the end facet 1b of the optical waveguide, but does not make contact with it. That is, there is a gap of several μm between the optical waveguide end face 1b and the optical fiber end face 2b. Therefore, the refractive index matching agent 4 is provided between the optical waveguide end face 1b and the optical fiber end face 2b.

The refractive index matching agent 4 is used in order to reduce Fresnel reflection of the guided light at the optical waveguide end face 1b and the optical fiber end face 2b to increase the return loss and to prevent the splice loss from deteriorating. In addition, both end surfaces 1b, 2
As described above, b is an inclined surface because each of the end surfaces 1b and 2b
This is because even if the waveguide light is Fresnel reflected, it is hardly optically coupled to the waveguide mode and the return loss is further increased. Even if the refractive index matching agent 4 does not exist between a part of the optical waveguide end face 1a and the optical fiber end face 2b, the connection loss increases to some extent, but the return loss does not significantly decrease.

In the connector using the PC of the optical waveguide end surface 1b and the optical fiber end surface 2b, all the optical waveguide end surfaces 1
Since PC is achieved between b / the end face 2b of the optical fiber, it is necessary to increase the total load applied to the optical fiber 2 as the number of the optical fibers 2 increases. In this connector, since the refractive index matching agent 4 is used, both end faces 1b and 2b are
Since it is possible to create a gap between them, the optical fiber 2
It is not necessary to increase the total load applied to the optical fiber 2, that is, the load pressing the plug 7 by the lock spring 8 so much even if the number of the plugs increases.

As described above, in the present connector, since a slight gap is allowed between both end faces, it is not necessary to exactly match the angle of the optical waveguide end face 1b and the angle of the optical fiber end face 2b. Therefore, when the optical fiber end face 2b is formed by polishing or the like, the allowable range of the angular error of the end face 2b can be set relatively wide, and the manufacturing yield of the plug 7 can be improved. This is a great advantage when the number of optical fibers 2 of the plug 7 is large.

In this connector, since the optical fiber 2 is accurately aligned with the optical waveguide 1 by the guide member 3, the positional accuracy of the optical fiber 2 fixed to the plug housing 7a is determined by the plug 7 being placed in the receptacle 6. The positional accuracy may be such that each optical fiber 2 is inserted into the corresponding fiber insertion hole 3a when it is inserted. Therefore, even if the number of connecting cores increases and the positional accuracy with which the plug housing 7a aligns the optical fibers 2 decreases, it can be tolerated. If the guide member 3 is formed by using a glass V-groove substrate manufactured by grinding, even if the number of the fiber insertion holes 3a is increased, the positional accuracy of the central axis does not deteriorate so much.

Further, the fiber insertion hole 3a of the guide member 3
Even if the number of
There is no factor that deteriorates the position accuracy when mounted on the. As described above, in this connector, even if the number of connecting cores exceeds about 16 and becomes large, the connection loss in each optical waveguide 1 / optical fiber 2 connection does not increase so much. In the plug 7, the length of the bare fiber 2a in the cantilever state may be the same as the fiber insertion hole 3a in principle, but when the guide member 3 is not present when the plug 7 is inserted into the receptacle 6. In order to allow a difference in the position of the optical fiber 2 when existing, the length is set to the fiber insertion hole 3
The length is set to be somewhat longer than a so that the optical fiber 2 at the time of connection has an unconstrained portion.

In this connector, the interval between the bare fibers 2a of the plug 7 can be made as small as 0.127 mm as described above, and the optical fibers 2 can be spatially arranged at a high density. Also, the lock spring 8 causes the plug 7
The load that presses on the receptacle housing 7a and the plug housing 6 does not need to be so large.
It is not necessary to increase the cross-sectional area of the connector member such as a or the joint area of the joint portion of the connector member such as the joint portion of the receptacle housing 6a and the optical waveguide substrate 1a. Based on these matters, it is possible to reduce the size of the connector with respect to the number of connection cores.

In this connector, since the refractive index matching agent 4 is used, it is not necessary to polish the optical waveguide end face 1b and the optical fiber end face 2b to have a small surface roughness, and those faces are formed by slicing. But it is acceptable. That is,
No polishing step is required in the production of the connector, which leads to cost reduction of the production of the connector. However, when slicing, it is necessary to tilt the blade or the optical waveguide substrate.

In this connector, each optical fiber end face 2
If b is located exactly on the same plane, the PC of the optical waveguide end face 1b and the optical fiber end face 1b can be realized without buckling the optical fiber 2 by an appropriate load of the lock spring 8 applied to the plug 7. You can also Refractive index matching agent 4
As the material, a highly viscous silicone is used in consideration of chemical stability and washout prevention. The refractive index matching agent 4 is
It is injected into the fiber insertion hole 3a in advance or is applied near the tip of the optical fiber 2 at the time of connection.

When the core of the optical waveguide 1 and the core of the optical fiber 2 have different refractive indices, the refractive index of the refractive index matching agent 4 is
The refractive index should be in the middle of them. The larger the inclination of the optical waveguide end face 1b and the optical fiber end face 2b with respect to the right-angled surface, the higher the return loss can be. However, when the inclinations are large, it becomes difficult to process the end face. Therefore, those inclinations, that is, the predetermined angles may be set according to the required return loss.

When the inclination as the predetermined angle is about 8 degrees, even if there is an air layer between both end faces 1b and 2b,
A return loss of approximately 40 dB or more can be obtained. The connector of the present embodiment is for connecting an optical waveguide and an optical fiber, but the configuration of this connector can be applied to a connector for connecting a large number of optical fibers. The configuration of the connector for connecting the optical fibers can be easily estimated by replacing the optical waveguide substrate 1a with the plug 7 in FIG.

[0046]

Second Embodiment FIG. 2 shows a second embodiment of the connector according to the present invention. The basic structure of the connector is similar to that of the first embodiment described above. However, the optical waveguide end face 1
b and the end face 2b of the optical fiber are inclined with respect to a plane perpendicular to them with a straight line perpendicular to the surface of the optical waveguide substrate 1a as an axis. It is not inclined with respect to the height direction (direction perpendicular to the optical waveguide substrate 1a). In the manufacturing process of this connector,
The end surface 1b of the optical waveguide can be treated as if it is a right-angled surface.

That is, polishing of the end facet 1b of the optical waveguide after slicing the optical waveguide substrate 1a becomes relatively easy. Since the height direction of the optical waveguide end face 1b has only to be vertical, when the optical waveguide end face 1b is formed as a slice plane, only the advancing direction of the blade may be controlled at the time of slicing.
In the manufacturing process of the connector of the first embodiment, when the optical waveguide end face 1b is used as a slice surface, it is necessary to incline the optical waveguide substrate end face 1b so that the height of the end face 1b changes.

[0048]

Third Embodiment FIG. 3 shows a third embodiment of the connector according to the present invention. The structure of the entire connector is similar to that shown in FIG. 1, and FIG. 3 is a sectional view of the guide member 3 and its vicinity. However, the guide member 3 is made of glass, and the UV curable adhesive 4a is used as a refractive index matching agent. UV is ultraviolet light. This adhesive 4a
Is transparent and has a refractive index substantially equal to the refractive indexes of the cores of the optical waveguide 1 and the optical fiber 2.

At the time of connection, the adhesive 4a is filled between the optical waveguide end face 1b and the optical fiber end face 2b and between the fiber insertion hole 3a and the side face of the optical fiber 2. After mounting an optical module configured based on the optical waveguide substrate 1a on a printed circuit board, the optical fiber 2 is connected to the optical module using this connector. Usually, it is not necessary to remove the optical fiber 2 thereafter. Therefore, after connecting the optical fiber 2 using this connector, it is possible to irradiate the connector with UV to cure the adhesive and fix the optical fiber 2 to the guide member 3. . Since the guide member 3 is made of glass, UV can reach the fiber insertion hole 3a.

By fixing the optical fiber 2 to the guide member 3, even if the load by which the lock spring 8 presses the plug 7 is small, or even if the lock spring 8 is detached from the connector, it is applied to the plug 7 through the optical fiber 2. Due to an external force or the like, the optical fiber end face 2 is moved against the optical waveguide end face 1b.
It is possible to prevent the connection characteristic from being deteriorated due to the backward movement of b. In other words, the load of the lock spring 8 can be reduced regardless of the connection core. Alternatively, the lock spring can be removed.

In this embodiment, the adhesive 4a exists between the end face 1b of the optical waveguide and the end face 2b of the optical fiber. However, near the end face 1b of the optical waveguide, a highly viscous silicone which is not cured by UV is inserted into the fiber insertion hole 3a. Other parts of
A configuration having a UV curable adhesive is also conceivable. The splicing method of the present embodiment falls into the category of permanent splicing, but differs greatly from the ordinary splicing method in that the optical fiber can be connected to the optical module on the printed circuit board only by manual work.

As described above, the present invention is
The present invention relates to an improvement in a connector that connects an optical fiber and a planar optical waveguide circuit (PLC). Conventionally, as a connector for simply connecting a PLC and a large number of optical fibers, light using "buckling force (force generated by elastic deformation of fiber; see FIG. 4B)" described in FIG. Fiber connectors have been devised. However, in this connector, the total buckling force increases as the number of cores to be connected increases, and when the number of cores exceeds 16, the force exerted on the planar optical waveguide circuit distorts the PLC substrate and affects the optical waveguide characteristics. There was a problem of giving it. In order to solve this problem, in the connector of the present invention, an oblique end face and a refractive index matching agent are used in the connection portion instead of the PC connection by the buckling force, and the connector is fixed to the PLC by a lock spring or an adhesive. These are optical connections, and for the first time, a connector having several tens to more than 100 cores can be realized by combining these.

[0053]

In the invention according to claim 1, the guide member having the fiber insertion hole can be manufactured by using the glass V-groove substrate formed by grinding, and the fiber insertion hole has several tens of insertion holes. Alternatively, even if there are 100 or more fibers, it is possible to manufacture a guide member in which the position of the fiber insertion hole is accurate. When a refractive index matching agent is provided between the end face of the optical waveguide and the end face of the optical fiber, the Fresnel reflection of the guided light at each end face becomes small.

At this time, even if the gap between the end face of the optical waveguide and the end face of the optical fiber is about several μm, when the guided light passes between the both end faces, diffraction of the guided light (spreading of light)
Is smaller than that in the case of air, and the connection loss of the connector due to the diffraction of the guided light in the gap is small. Since the end face of the optical waveguide and the end face of the optical fiber are inclined with respect to the face perpendicular to the optical axis, even if the waveguide light is Fresnel reflected at each end face, the reflected light is almost not coupled to the guided mode. Therefore, the guided light does not propagate in the opposite direction to the guided light. That is, the return loss can be increased.

Alternatively, even if the refractive index matching agent does not reach between the end face of the optical waveguide and the end face of the optical fiber and air is present, the splice loss slightly increases due to the Fresnel reflection, but the reflection attenuation is caused. The quantity does not deteriorate significantly. As described above, even if there is a gap to some extent between the end face of the optical waveguide and the end face of the optical fiber, the connection loss and the return loss deterioration due to the gap are small. In other words, the existence of such a gap is allowed.

Further, when a refractive index matching agent is provided between the end face of the optical waveguide and the end face of the optical fiber, even if the surface roughness of the end face of the optical waveguide or the end face of the optical fiber is somewhat large, the light is guided from the end face of the optical waveguide or the end face of the optical fiber. When the wave light is emitted, the guided light is prevented from being scattered or refracted in a direction different from the optical axis direction. Based on this matter and the matter that the above gap is allowed, the allowable range of the angular error and the surface roughness of the optical fiber end face can be made relatively large, and even when the number of optical fibers included in the connector is large, The production yield of connector plugs is improved. This leads to a reduction in the manufacturing cost of the connector.

According to the above-mentioned allowance of the gap, the total sum of the weights for pressing the optical fiber toward the end face of the optical waveguide is achieved even when the connector realizes the super multi-core connection in which the number of cores exceeds several tens or 100. Does not have to be too large. The possibility that the reliability of the connector itself or the optical module body is impaired is reduced due to the load generated for connection in the connector. Since the load generated for connection at the connector does not have to be too large,
It is not necessary to increase the cross-sectional area of the constituent members of the connector or the joint area between the constituent members.

Since the optical fiber is a bare fiber in the connector, the optical fiber can be arranged at a narrow interval of about 0.127 mm. Therefore, it is possible to realize a compact connector with respect to the number of connection cores.
Since the end faces of the optical waveguide and the end face of the optical fiber are inclined faces, even if the refractive index of the refractive index matching agent changes due to temperature fluctuations or the like, it is possible to prevent the return loss from significantly deteriorating.
From the above, the connection loss is small, the return loss is high, and the reliability including environment resistance and long-term reliability is good,
It is possible to provide an optical connector, which has a low manufacturing cost, and which can connect an optical fiber with an optical fiber having several tens or more than 100 cores.

In the invention according to claim 2, the above effect can be obtained even when the end faces of the optical waveguide and the end faces of the optical fiber are inclined about a straight line perpendicular to the surface of the optical waveguide substrate. In this case, since the direction perpendicular to the optical waveguide substrate surface is a right angle, polishing of the optical waveguide end face after slicing the optical waveguide substrate is small. Alternatively, a normal slicing method can be used even when the end surface of the optical waveguide is formed as a sliced surface. That is, at the time of slicing, it is sufficient to control only the slicing direction (the feeding direction of the blade or the optical waveguide substrate). Thereby, the processing cost of the end face of the optical waveguide can be significantly reduced.

In the invention according to claim 3, the UV-curable adhesive in the fiber insertion hole of the guide member is transparent to the guided light and has the same refractive index as that of the optical waveguide and the core of the optical fiber. And acts as a refractive index matching agent. In addition, it is cured by UV irradiation to fix the optical fiber to the guide member. Since the guide member is made of glass, UV can reach the fiber insertion hole. The present invention is effective when it is not necessary to release the connection after connecting the optical fiber to the optical module.

Since the optical fiber is fixed to the guide member in the state where the optical waveguide and the optical fiber are connected by the UV-curing adhesive, even if the load pressing the plug toward the end face of the optical waveguide is small, Alternatively, even if the lock spring is released after the UV curable adhesive is hardened, external force such as pulling force and bending force applied to the connected optical fiber loosens the connection between the receptacle and the plug, and the connection characteristics deteriorate. This can be reliably prevented. Since the load generated in the connector for connection is smaller, the possibility of impairing the reliability of the connector itself or the optical module body is further reduced. This is the same even when the number of optical fibers in the connector is several tens to more than 100.

In the invention according to claim 4, even if the refractive index matching agent does not reach between the end face of the optical waveguide and the end face of the optical fiber and air is present, the connection loss is caused by the Fresnel reflection. Although it slightly increases, the return loss does not significantly deteriorate, and since the inclination of both end faces is about 8 degrees, the return loss can be approximately -40 dB or less. The present invention is effective when applied to a connector that simultaneously connects 16 cores or more in which the total buckling force of PC connection due to buckling force exceeds 11N, but the number of simultaneous connections is 32 cores, and further 64 It goes without saying that the effect becomes even more remarkable when applied to transcendental connections.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an optical connector according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an optical connector according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an optical connector according to a third embodiment of the present invention.

FIG. 4 is an explanatory view showing a conventional optical connector.

FIG. 5 is an explanatory diagram showing a conventional optical connector.

FIG. 6 is an explanatory view showing a means for permanently connecting an optical waveguide and an optical fiber.

[Explanation of symbols]

1 Optical waveguide 1a Optical waveguide substrate 1b Optical waveguide end face 2 optical fiber 2a bare fiber 2b Optical fiber end face 3 Guide member 3a Fiber insertion hole 4 Refractive index matching agent 4a UV curable adhesive 5 glass blocks 6 Receptacle 6a Receptacle housing 7 plug 7a plug housing 8 lock springs 10 V groove 11 guide pins 12 Guide hole 13 ferrules 14 Fiber block

Claims (4)

[Claims] 1. A bare fiber whose coating is removed in the vicinity of the tip of the optical fiber for connecting the optical fiber and the flat substrate type optical waveguide, and the bare fiber inserted is inserted into the optical waveguide. An optical connector having an aligning guide member at an end of the flat plate substrate, wherein there are 16 or more optical fibers, and the optical waveguide and the end faces of the optical fibers are inclined at a predetermined angle with respect to a plane perpendicular to an optical axis. And an index matching material between the end face of the optical waveguide and the end face of the optical fiber. 2. The end face of the optical waveguide and the end face of the optical fiber are inclined at a predetermined angle with respect to a plane perpendicular to the optical axis about a straight line perpendicular to the plane of the flat plate substrate. Optical connector. 3. The optical connector according to claim 1, wherein the guide member is made of glass, and the refractive index matching agent is an ultraviolet curable adhesive. 4. The optical connector according to claim 1, wherein the predetermined angle is about 8 degrees.