Optical connector and fiber module

An optical connector that permits an optical fiber ribbon to be led out in multiple directions and an optical fiber module that uses the optical connector are provided. The optical connector comprises a connector main body and a guide groove formed on the connector main body in which an optical fiber ribbon is arranged, wherein the guide groove is comprised of an end face holding slot, a vertical guiding face, an arcuate guiding face formed in arc-shape, and a positioning face for widthwise positioning and fixing the optical fiber ribbon and wherein the vertical guiding face and the arcuate guiding face and the positioning face define a space that opens toward a top face of the connector main body; and the optical fiber module comprises the optical fiber ribbon and the optical connector.

TECHNICAL FIELD

The present invention relates to an optical connector for connecting an optical fiber ribbon optically with arrayed optical elements and an optical fiber module that uses the optical connector.

BACKGROUND ART

Attention has been focused on the optical transmission system with optical interconnection technique as an optical transmission technology for intra- or inter-equipment. In the optical interconnection system for this category of application, arrayed optical elements such as the Vertical-Cavity Surface-Emitting Laser (VCSEL), which is easy to configure a multi-channel array, has been generally used.

Establishing the optical transmission between groups of arrayed optical elements has used an optical fiber ribbon151as shown inFIG. 16for example. The construction of the optical fiber ribbon151is such that: a plurality of optical fibers150(four fibers as an example shown inFIG. 16) are aligned flat at a pitch or spacing of P equal to the arraying pitch in the arrayed optical elements and then aligned optical fibers are commonly jacketed with a resin153.

At the end of the optical fiber ribbon151as shown inFIG. 17, an optical connector165is installed to connect the fiber end thereof optically with the surface-emitting face (or surface-receiving face)162of arrayed optical elements161mounted on a substrate160(refer to Patent Literatures 1 to 3 for example).

In a conventional art, to connect the optical fiber ribbon151optically with the surface-emitting face (or surface-receiving face)162of the arrayed optical elements161mounted on the substrate160using the optical connector165, the optical fiber ribbon151runs in a guiding slot164provided on a connector main body163so that the end face of the optical fiber ribbon151will oppose to each surface-emitting face (or surface-receiving face)162of the arrayed optical elements161mounted on the substrate160.

As described above, the construction of the optical connector165in a conventional art was such that the optical fiber ribbon151is bent within the connector main body163so that the optical path will turn its direction while running between the bottom face of the connector main body163and the side face thereof to permit leading out the optical fiber ribbon151from a desired face (side face for example) of the connector main body163.

In manufacturing optical fiber modules, the optical fiber ribbon151is arranged in the guiding slot164so that the tip thereof will project out of the bottom face of the connector main body163, and then the end of the optical fiber ribbon151and the bottom face of the connector main body163are polished together to obtain an end face166.

The reason of polishing the tip of the optical fiber ribbon151is to make the end face166of the optical fiber ribbon151flat. If not flat, signal light will make diffused reflection or other disorder at the end face166resulting in the light loss increase.

In the conventional art for manufacturing optical fiber modules therefore, the end face166is cleaved with such as a fiber cutter in advance and then the tip thereof is polished to make the end face166flat.

Patent Literature 1

SUMMARY OF INVENTION

In recent years, miniaturization of equipment is demanded. To respond to this, wiring optical fiber ribbons must be accommodated within a limited room. This requirement for wiring has brought a problem such that leading out the optical fiber ribbon is sometimes not practicable except only in a specific direction for example either perpendicular to or parallel to the substrate.

Conventional optical connectors has had a problem such that leading out the optical fiber ribbon is restricted only to a particular direction (from the side face of the connector main body163for example); because of this, the wiring operation is forced to be sophisticated or to properly use different style of connectors according to the desired lead-out direction.

The optical fiber150to be used in the optical fiber ribbon151usually has a first coating layer (a primary layer) applied over its bare fiber, comprised of the core and the clad, and a second coating layer (secondary layer) applied over the first coating layer, wherein the second coating layer has a Young's modulus higher than that of the first coating layer. In a conventional optical fiber module, the optical fiber150is arranged in the guiding slot164and then the bottom face of the connector main body163(the connection face with a substrate) is polished; while undergoing this polishing, the first coating layer may sometimes peel off because of its being soft.

This, being attributable to the polishing, develops to a breakage of the tip of the optical fiber150at the portion having no first coating layer or to a bend of the tip of the optical fiber150. These cause a positional deviation with the arrayed optical elements161on the substrate160resulting in the connection loss increase due to a misaligning of the optical axis with the transmission signal deteriorated.

The purpose of the present invention is to provide an optical connector that permits an optical fiber ribbon to be lead out in multiple directions and an optical fiber module that permits an optical fiber ribbon to be connected optically with arrayed optical elements without polishing the end face of the optical fiber ribbon.

Means for Solving the Problems

The present invention is devised to accomplish the purpose stated above. The invention defined in claim1is: an optical connector for connecting the end face of an optical fiber ribbon optically with arrayed optical elements on a substrate, comprising a connector main body having a bottom face parallel to the substrate; and a guide groove formed on the connector main body in which the optical fiber ribbon is arranged; the guide groove comprising an end face holding slot that holds the optical fiber ribbon so that the end face of the optical fiber ribbon on the bottom face of the connector main body facing the substrate will oppose to the arrayed optical elements, a vertical guiding face perpendicular to the substrate and extending from one side of the end face holding slot on the bottom face of the connector main body to the top face thereof, an arcuate guiding face formed in an arc-shape extending from the opposing other side of the end holding slot to the side face of the connector main body, and a positioning face for widthwise positioning and fixing the optical fiber ribbon formed perpendicularly to the substrate adjoining both the vertical guiding face and the arcuate guiding face, wherein the vertical guiding face and the arcuate guiding face and the positioning face define a space that opens toward the top face of the connector main body.

The invention defined in claim2is: the optical connector according to claim1, wherein the arcuate guiding face of the guide groove ends in the side face of the connector main body at a position lower than the top face thereof by a distance equal to the thickness of the optical fiber ribbon or more distance.

The invention defined in claim3is: the optical connector according to claim1or claim2, wherein the connector main body has a plurality of the guide grooves.

The invention defined in claim4is: the optical connector according to any one of claims1to3, wherein the bottom portion of the guide groove on the bottom face of the connector main body is formed integrally in one body with the connector main body and is sealed.

The invention defined in claim5is: the optical connector according to any one of claims1to4, wherein the connector main body has a lens provided integrally in one body with the bottom face thereof which bottom face is opposed to the end face of the guide groove.

The invention defined in claim6is: the optical connector according to any one of claims1to4, wherein the connector main body has a transparent substrate provided integrally in one body with the bottom face thereof which face is opposed to the end face of the guide groove.

The invention defined in claim7is: the optical connector according to claim1, wherein the connector main body is further comprised of a vertical guiding slot for arranging the optical fiber ribbon perpendicularly to the substrate.

The invention defined in claim8is: an optical fiber module comprising an optical fiber ribbon and an optical connector for connecting the end face of the optical fiber ribbon with arrayed optical elements on a substrate, wherein the optical connector is comprised of an optical connector defined in claim1that has a connector main body having a bottom face parallel to the substrate and a guide groove provided on the connector main body for arranging the optical fiber ribbon, wherein a resin having the same refractive index as the core of the optical fiber ribbon is filled in the guide groove formed on the connector main body for making one end of the optical fiber ribbon arranged perpendicularly to the substrate at the bottom face of the connector main body so as to intervene between the end face of the optical fiber ribbon and the bottom face of the connector main body.

According to the present invention, an optical fiber ribbon can be lead out in multiple directions. Further, the optical fiber ribbon can be connected optically with arrayed optical elements without polishing the end face of the optical fiber ribbon.

DESCRIPTION OF EMBODIMENTS

The following will explain preferred modes of implementing the present invention referring to attached drawings.

The optical connector by the present invention is to connect the end face of an optical fiber ribbon optically with arrayed optical elements on a substrate.

FIG. 1(a) is a perspective view of the optical connector according to Embodiment 1 of the present invention;FIG. 1(b) is a cross-sectional view of the optical connector shown inFIG. 1(a) sectioned along the line1B-1B; andFIG. 1(c) is a perspective view of an optical fiber module having an optical fiber ribbon and the optical connector.

As shown inFIGS. 1(a) and1(b), an optical connector1has such a construction that a connector main body2formed by resin molding has one or more guide grooves4(two grooves inFIG. 1).

The connector main body2is a rectangular solid and has a bottom face parallel to a substrate on which arrayed optical elements are mounted.

The guide groove4is comprised of: an end face holding slot5that holds an optical fiber ribbon so that the end face of the optical fiber ribbon on the bottom face of the connector main body2facing the substrate will oppose to the arrayed optical elements, a vertical guiding face7perpendicular to the substrate and extending from one side of the end face holding slot5(inFIG. 1(b), the left side face thereof) on the bottom face of the connector main body2to the top face thereof, an arcuate guiding face9formed in an arc-shape extending from the opposing other side of the end holding slot5(inFIG. 1(b), the right side face thereof) on the bottom face of the connector main body2to the side face thereof, and a positioning face10for widthwise positioning and fixing the optical fiber ribbon formed perpendicularly to the substrate adjoining both the vertical guiding face7and the arcuate guiding face9, wherein the vertical guiding face7and the arcuate guiding face9and the positioning face10define a space11that opens toward the top face of the connector main body2. Thus, the guide groove4has a shape that enlarges upwardly its opening.

The arcuate guiding face9of the guide groove4is preferred to end in the side face of the connector main body2at a position lower than the top face thereof by a distance equal to the thickness of the optical fiber ribbon or more distance. This is for prevention of bulge-out of the optical fiber ribbon out of the top face of the connector main body2when the optical fiber ribbon is fixed along the arcuate guiding face9.

When an optical fiber ribbon151is placed along the arcuate guiding face9of the guide groove4as shown inFIG. 2(a), the optical fiber ribbon151is lead out in the side face of the connector main body2.

Further, when the optical fiber ribbon151is placed along the vertical guiding face7of the guide groove4, the optical fiber ribbon151is led out in the top face of the connector main body2.

Moreover, since the space11defined by the vertical guiding face7and the arcuate guiding face9and the positioning face10opens to the top face of the connector main body2, the direction of leading out the optical fiber ribbon151can be chosen as desired within the range from the arcuate guiding face9to the vertical guiding face11.

Thus, the optical connector1permits the optical fiber ribbon151to be lead out in multiple directions. Employing above-stated methods, an optical finer module having the optical fiber ribbon151and the optical connector1(FIG. 1(c)) is manufactured.

Into the space11of the guide groove4, a resin12is filled and then cured to fix the optical fiber ribbon151. As for the resin12, UV-curable resin or thermo-setting resin for example is preferable.

As an example, the fixing method of the optical fiber ribbon151on the connector main body2will be explained for the case that the optical fiber ribbon151is led out from the side face of the connector main body2referring toFIGS. 3(a) to3(c).

As shown inFIG. 3(a), the optical fiber ribbon151is arranged along the arcuate guiding face9of the guide groove4. In this arrangement, the tip of the optical fiber ribbon151is positioned so that the tip will project from the underface of the connector main body2.

Then as shown inFIG. 3(b), the space11of the guide groove4is filled with the resin12, which is thereafter cured to fix the optical fiber ribbon151.

After the resin12had cured, the tip of the optical fiber ribbon151projected from the underface of the connector main body2is cleaved and polished as shown inFIG. 3(c).

Thus, the cleaving of the tip of the optical fiber ribbon151after glue-and-fix makes it flat at the end face of the optical fiber ribbon151establishing a good optical connection with the arrayed optical elements.

Methods of fixing the optical fiber ribbon151on the connector main body2are not limited to above-stated practice. The optical fiber ribbon151can be fixed as shown inFIG. 4(a) for example by a method comprising the processes of: placing the connector main body2on a plate40having a smooth-face such as glass plate; filling the guide groove4with the resin12; arranging the optical fiber ribbon151along the arcuate guiding face9of the guide groove4as shown inFIG. 4(b); and curing the resin12to fix the optical fiber ribbon151; thereafter, the connector main body2is removed from the plate40. Thereby, the resin12intervenes between the bottom portion of the guide groove4and the end face of the optical fiber ribbon151. In the optical fiber module3having the optical fiber ribbon151and the optical connector1therefore, irregularity of end face of the optical fiber ribbon151will be optically eliminated (refractive index matching) as shown inFIG. 4(d) even the end face thereof is rough somewhat since the intervening of the resin12compensates such roughness.

In this example, the optical fiber ribbon151was arranged after the guide groove4had been filled with the resin12. Alternatively, the optical fiber ribbon151may be arranged in the guide groove4before the resin12is filled. When arranging the optical fiber ribbon151in the guide groove4, an arrangement in which the end face of the optical fiber ribbon151is positioned in contact with the surface of the plate40, or instead positioned at a location recessed from the surface of the plate40by a predetermined distance (about 100 μm for example), may be practicable.

InFIGS. 4(b) and4(c), the end face of the optical fiber ribbon151is positioned at slightly upper location than the underface of the connector main body2and the resin12intervenes between the end face of the optical fiber ribbon151and the underface (or a plane even to the underface) of the connector main body2covering the tip of the optical fiber ribbon151. When the end face of the optical fiber ribbon151is irregular or not even as shown inFIG. 4(d), an arrangement, in which the optical fiber ribbon151is positioned so that the tip of a jut31on the end face thereof (the longest protrusion toward tiptop) will sit on a plane even to the underface of the connector main body2allowing the resin12to intervene between the irregular portion other than the jut31and the bottom portion of the guide groove4, may be practicable. This means that, when the end face of the optical fiber ribbon151is made optically flat, it is not necessary to cover the entirety of tip of the optical fiber ribbon151with the resin12.

In the fixing methods shown inFIGS. 4(a) to4(d), a flat end face is attained without polishing the tip of the optical fiber ribbon151. This makes the operation for fixing the optical fiber ribbon151on the connector main body2easy. As for the resin12, UV-curable resin or thermo-setting resin is preferable. When UV-curable resin is intended to be employed, it is suitable to form the connector main body2using a clear material that is UV-transparent. In selecting the resin12, it is suitable to employ a material having the same refraction index as the cores of fibers in the optical fiber ribbon151have or a lens (this element will be described later) has. In detail, a resin12having refraction index of 1.3 to 1.7, preferably 1.46 to 1.6, will be suitable.

In mounting on a substrate, the optical connector1is stuck on a transparent substrate (ceramic substrate)50and then the transparent substrate50is mounted on the substrate.

Plural protrusions51are provided on the underface of the transparent substrate50(in the four corners of the transparent substrate50for example); this is for installing the transparent substrate50on the substrate on which arrayed optical elements are mounted. A lens (micro-lens)60is installed on the underface of the transparent substrate50.

In sticking the optical connector1on the transparent substrate50, the optical axis of the lens60on the transparent substrate50is made to align with the optical axis of the end face of the optical fiber ribbon151.

The following explains an example in which a substrate70for High-definition Multimedia Interface (HDMI), shown inFIGS. 7 and 8, is used. However, the present invention is not limited to such method.

On the substrate70, arrayed optical elements81, a driver IC71for driving the arrayed optical elements81, a terminal72for establishing electrical connection with external electrical devices (external communication equipment), etc. are mounted with wiring patterns (not illustrated) formed thereon.

Around the arrayed optical elements81on the substrate70, fixing holes (not illustrated) are provided for positioning and fixing the transparent substrate50having the optical connector1stuck thereon. The fixing hole is formed at such a position that the optical axis of the lens60aligns with the optical axis of each surface-emitting face (or surface-receiving face) of the arrayed optical elements81.

The optical connector1is installed with the protrusion51provided on the transparent substrate50inserting into the fixing hole. Thereby, the optical axis of the end face of the optical fiber ribbon151aligns with the optical axis of each surface-emitting face (or surface-receiving face) of the arrayed optical elements81with the optical fiber ribbon151and the arrayed optical elements81optically connected.

The following explains details of the optical connector1and an optical fiber module, which has an optical fiber ribbon and the optical connector1, in Embodiment 1 of the present invention.

The optical connector1of the present invention uses the guide groove4as a guiding groove for holding the optical fiber ribbon151to make its end face opposed to each surface-emitting face or surface-receiving face of the arrayed optical elements. This permits the optical fiber ribbon151to be led out in multiple directions. In other words, the leading-out direction of the optical fiber ribbon151can be optionally changed in the rage from the top face of the optical connector2to the side face thereof.

This feature eliminates dependence on the variety of lead-out directions in choosing different optical connectors with complication in wiring operation prevented.

Further, since the guide groove4enlarges upwardly its opening, the tip of the optical fiber ribbon151will not be damaged while its being inserted into the guide groove4.

In the embodiment 1, the optical connector1and the transparent substrate50are separate bodies; however, the optical connector1and the transparent substrate50may be integrally configured in one body. Further, in Embodiment 1, the transparent substrate50has the lens60; however, the lens60may be omitted.

In Embodiment 1, the bottom portion of the guide groove4is a through-hole. However, it may be practicable to use such an optical connector92that the bottom portion of the guide groove4is sealed with a sealing91formed integrally in one body with the underface of a connector main body2as shown inFIG. 9(a). In this configuration, the connector main body2should be constituted of a material transparent to the light which the optical fiber ribbon151transmits.

It may further be practicable to use such an optical connector93that the lens60is provided integrally in one body with the sealing91on the bottom portion thereof as shown inFIG. 9(b). In this configuration, it is feasible to install the connector main body2directly on the substrate70without use of the transparent substrate50as shown inFIGS. 10 and 11helped by plural legs94(four legs in the case ofFIG. 9(b)) provided on the underface of the connector main body2. Then, the number of parts will be reduced since the transparent substrate50is not required.

In fixing the optical fiber ribbon151using the optical connectors92and93shown inFIGS. 9(a) and9(b), it would be suitable to take the steps of: filling the guide groove4having a sealed bottom portion with the resin12; inserting the optical fiber ribbon151into the guide groove4; and then curing the resin12to fix. Thereby, the end face of the optical fiber ribbon151is made flat without using the smooth-face plate40in the fixing method explained referring toFIGS. 4(a) to4(c).

In this practice, the lens60is provided underface of the sealing91integrally; alternatively, closing the bottom portion of the guide groove4only with the lens60may be practicable.

The optical fiber module of the present invention is fabricated undergoing the processes of: filling in advance the guide groove4with the curable resin12, inserting the optical fiber ribbon151into the guide groove4filled with the resin12, making the resin12intervene between the bottom portion of the guide groove4and the end face of the optical fiber ribbon151to make irregularity of the end face thereof optically eliminated, and curing the resin12.

Thereby, irregularity of end face of the optical fiber ribbon151will be optically eliminated (refractive index matching) even the end face thereof is rough somewhat, since the intervening of the resin12compensates such roughness.

Thus, the end face of the optical fiber ribbon151can be flattened without polishing; therefore, the optical fiber ribbon151can be connected optically with the arrayed optical elements without end face polishing. Because of this feature, the breakage of tip of the optical fiber ribbon151and positional deviation with the arrayed optical elements (misaligning of the optical axis) due to polishing is prevented. In addition, this feature cuts the manufacturing costs since the polishing process is not necessary.

An optical connector120shown inFIGS. 12(a),13(a) to13(d) has such a construction that a vertical guiding slot131is provided additionally to the guide groove4in the optical connector1shown inFIG. 1.FIG. 12(b) shows an optical module130that has the optical fiber ribbon151and the optical connector120.

More specifically, the construction is such that two or more vertical guiding slots131for guiding the optical fiber ribbon151vertically and two or more guide grooves4are provided in the connector main body2in a longitudinal direction of the optical fiber ribbon151(FIGS. 13(a) to13(d) show an example of two ranks of one each).

In the optical connector120, the direction of leading out the optical fiber ribbon151can be chosen as desired within the range from the top face side to the side face side of the connector main body2and at the same time the optical fiber ribbon151arranged in the vertical guiding slot131can be led out toward the top face side of the connector main body2. Thus, numbers of the optical fiber ribbons151can be wired varying their leading out directions. Further, the optical fiber ribbons151can be connected to a maximum of four (two sending/receiving pairs) offering highly densified and large capacity wiring system.

The optical connector120permits the optical fiber ribbon151to be led out in the top face side of the connector main body2to a maximum of four and in the side face side of the same to a maximum of two; this feature provides a variety in determination of proper leading-out direction depending on use applications.

Fixing the optical fiber ribbon151on the optical connector120undergoes, as described in the explanation of Embodiment 1, the processes of: placing the plate40having a smooth-face on the underface of the connector main body2to seal the bottom portion of the guide groove4; filling the resin12in the guide groove4; arranging the optical fiber ribbon151so that the resin12will intervene between the end face of the optical fiber ribbon151and the bottom portions of the vertical guiding slot131and of the guide groove4; and curing the resin12to fix the optical fiber ribbon151.

Thereby, irregularity of end face of the optical fiber ribbon151will be optically eliminated (refractive index matching) as well as the optical fiber module shown inFIG. 4(d) even the end face thereof is rough somewhat since the intervening of the resin12compensates such roughness.

Thus, the end face of the optical fiber ribbon151can be flattened without polishing; therefore the optical fiber ribbon151can be connected optically with the arrayed optical elements without end face polishing. Because of this feature, the breakage of tip of the optical fiber ribbon151or positional deviation with the arrayed optical elements (misalignment of the optical axis) due to polishing is prevented. In addition, this feature cuts the manufacturing costs since the polishing process is not necessary.

In Embodiment 2, the vertical guiding slot131and the guide grooves4are provided in the longitudinal direction. However, the vertical guiding slot131may be substituted with another guide groove4as shown inFIG. 13(d). In this case, the arcuate guiding face9of the guide groove4on the left side in the cited figure is shaped to intersect the vertical guiding face7of the guide groove4on the right side in the figure.

Providing a plurality of the guide grooves4in the longitudinal direction permits a plurality of the optical fiber ribbons151to be led out in the same direction or severally in the different directions.

Further, similarly to Embodiment 1, the bottom portions of the vertical guiding slot131and the guide groove4may be sealed by the sealing91formed integrally in one body with the underface of the connector main body2, or instead the lens60may be provided integrally in one body with the sealing91as shown inFIG. 14(b).

As stated above, the optical connector120provides the same advantageous effects that Embodiment 1 offers in addition to the same that Embodiment 2 offers.

The following will explain another embodiment of the present invention.

An optical connector100shown inFIG. 15(a) has such a construction that an optical fiber positioning slot101is provided on the end (bottom portion) of the guide groove4of the optical connector1shown inFIGS. 1(a) and1(b) for holding and fixing an optical fiber152that is a projected optical fiber formed by removing the jacket over the tip of the optical fiber ribbon151.

In the optical fiber ribbon151generally, the outer diameter of the optical fiber152can be formed accurately but applying its jacket accurately is not easy.

Therefore, when the optical axis alignment between the arrayed optical elements and the optical fiber152is required to be highly accurate, it is preferable to remove the jacket over the tip of the optical fiber ribbon151to project the optical fiber152and then to position the projected optical fiber152relying on the optical fiber positioning slot101.

For example, when the optical fiber ribbon151is a four-fiber ribbon and the external diameter of the optical fiber152is 250 μm as shown inFIG. 15(b), it is appropriate to make the optical fiber positioning slot101have a width of 1 mm and a height, or a depth, of 250 μm. Thereby, it becomes practicable to closely arrange four optical fibers152on the input-end or output-end with the positioning accuracy increased.

It is to be understood that the present invention is not limited in its implementation to the above-stated embodiments and may be practiced in various modifications without departing from the scope of the present invention.