JP2843338B2 - Optical waveguide / optical fiber connector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a connector structure for connecting an optical waveguide on a flat substrate to an input / output optical fiber.

<Prior Art> With the development of the optical industry including optical fiber communication, various optical components are required. These optical components can be realized by (1) bulk type, (2) fiber type, (3)
Planar waveguide types are known.

(1) A bulk-type optical component realizes a target optical circuit function by combining a prism, a lens, and the like.

(2) The fiber type optical component realizes an optical circuit function by processing the optical fiber itself.

(3) On the other hand, a planar waveguide optical component realizes an optical circuit function by forming an optical waveguide on a flat substrate at a time by a photolinography process similar to an LSI manufacturing process. Compared with the fiber type, it is superior in mass productivity, stability and function integration possibility, and is expected as a future optical component.

Here, there is an inevitable problem in putting a planar waveguide optical component into practical use, such as how to connect an optical waveguide terminal to an input / output optical fiber.

Conventionally, various methods have been proposed to solve the above-described problems. For example, (a) a method of providing an optical fiber guide groove for positioning and fixing an optical fiber to be connected to the optical waveguide on a substrate on which the optical waveguide is formed;
(B) A method in which optical fibers are arranged and fixed in a V-groove made of silicon is bonded to an end face of a substrate with an optical waveguide by abutting.

However, in either of the methods (a) and (b), the input and output optical fibers are permanently fixed to the substrate with the optical waveguide and cannot be separated.

For this reason, in the past, planar waveguide optical components have always been handled in a form in which an input / output optical fiber having a length of about 1 meter is fixed to the optical component. There were restrictions on the method. Also,
There is a problem that it is difficult to replace the optical component on a flexible basis, and that a measure when an optical component fails is delayed.

Recently, as an attempt to detachably attach an input / output optical fiber to a substrate with an optical waveguide, a connector configuration shown in FIGS. 5 and 6 has been proposed (Satake et al .: Showa)
Proceedings of the IEICE Autumn National Convention 1988, C-23
8).

In FIG. 5, 1 is an optical waveguide substrate, 2 is an optical waveguide formed on the substrate 1, 3 is a brass base of an optical waveguide / optical fiber coupling connector, 4 is a guide pin, 5 is a guide pin fixing hole. , 6 is an adhesive injection hole, and 7 is an adhesive.

The optical waveguide substrate 1 is housed in the concave hollow portion of the base 3 so that the surface on which the optical waveguide 2 is formed is located below, and the adhesive 7
Is fixed to the base 3. Further, two guide pins 4 are provided at both ends of the base 3. The guide pins 4 are inserted into fixing holes 5 formed outside the hollow portion, and are fixed to the base 3 by an adhesive 7 inserted through an injection hole 6. The center distance between the two guide pins 4, 4 is 4.6 mm.

FIG. 6 shows a state in which an optical fiber plug 9 is coupled to the optical waveguide substrate 1 of FIG. A plug can be similarly connected to the other end. Plug 9 is an input / output optical fiber
The base 3 has a hole 10 for receiving the guide pin 4 provided therein. And base 3
The guide pin 4 is inserted into the receiving hole 10 of the plug 9 as shown in FIG.
The position of the guide pin 4 in the fixing hole 5 is adjusted in advance so that the optical waveguide 2 and the optical fiber 11 are aligned with high precision.

<Problem to be Solved by the Invention> In the connector structure shown in FIG.
The input / output optical fiber 11 accommodated in the optical waveguide substrate 1 can be repeatedly attached to and detached from the optical waveguide substrate 1. However, the following problems remain.

That is, since the optical waveguide substrate 1 is accommodated in the concave hollow portion of the base 3, in order to be able to accommodate the optical waveguide substrate 1, the entire width W of the optical waveguide substrate 1 must be smaller than the interval between the two guide pins 4. Restrictions were imposed.

Such a restriction is caused by a relatively simple optical component such as a Y-type optical branching element or a directional optical coupler, that is, the width W is smaller than the length L.
This is not a major problem when only an optical component having a small value is targeted.

However, it was difficult to apply the connector structure of FIG. 5 to a wide and relatively large area optical component such as an optical ring resonator and a Mach-Zehnder optical interferometer circuit for optical frequency multiplexing communication. Of course, if the distance between the two guide pins 4, 4 is set to be as large as several tens of mm or more, it is possible to accommodate a wide optical waveguide substrate in the base 3. In addition, it is difficult to accurately align the optical axes of the terminals of the optical waveguide 2 with each other, and there is a problem that a spike in connection loss occurs.

In view of the above, it is an object of the present invention to provide an optical waveguide in which the width of the optical waveguide substrate is not restricted by the interval between the two guide pins, and the optical fiber plug can be repeatedly attached to and detached from the optical waveguide substrate. -To provide an optical fiber connector.

<Means for Solving the Problems> In order to achieve the above object, the present invention improves the connector structure shown in FIG. 5 and includes a guide pin fixing groove directly in the optical waveguide substrate.

Therefore, the optical waveguide / optical fiber connector according to the present invention includes a substrate, an optical waveguide terminal installed on the substrate, and two guides provided directly along the surface of the substrate and reaching the end surface of the substrate. An optical waveguide substrate including a pin fixing groove, two guide pins fixed to each guide pin fixing groove with a fixing material such as an adhesive or solder and having one end protruding from an end surface of the substrate; An optical fiber plug comprising a holder accommodating an optical fiber terminal to be provided, and two guide pin accommodation holes provided in the holder and detachably accommodating the guide pins,
The guide pin fixing groove has a clearance in which the guide pin can move within the guide pin fixing groove, and when the guide pin of the optical waveguide substrate is inserted into the guide pin receiving hole of the optical fiber plug, the optical waveguide terminal and The position of the guide pin, the position of the optical waveguide terminal, the position of the guide pin receiving hole, and the position of the optical fiber terminal are adjusted so that the optical axis is automatically aligned with the optical fiber. With the pin inserted in the hole,
The position is adjusted in advance in the clearance of the guide pin fixing groove so that the optical axis of the optical waveguide terminal and the optical axis of the optical fiber terminal are aligned, and the position is fixed to the guide pin fixing groove by the fixing material, and the guide pin is fixed. By inserting and removing the guide pin fixed to the groove and the guide pin receiving hole,
The connection and disconnection of the optical waveguide terminal and the optical fiber terminal are performed.

<Operation> In the present invention, the position of the guide pin is adjusted in advance in the clearance of the guide pin fixing groove so that the optical axes of the optical waveguide terminal and the optical fiber terminal are aligned with the guide pin inserted into the guide pin receiving hole. In this state, the guide pin is fixed to the guide pin fixing groove by the fixing material. Therefore,
The optical waveguide terminal and the optical fiber terminal are connected with high accuracy. In addition, the connection and disconnection of the optical waveguide terminal and the optical fiber terminal can be performed by inserting and removing the guide pin and the guide pin receiving hole. Further, since the guide pin fixing groove is provided directly on the optical waveguide substrate, the guide pins can be installed without widening the guide pin interval even if the width of the optical waveguide substrate is large.

<Example> Hereinafter, the present invention will be described in detail by examples with reference to FIG. 1 to FIG.

FIG. 1 is a view showing an embodiment of a connector according to the present invention, in which 20 is an optical waveguide circuit, 21 is a planar optical waveguide substrate, 22
Is an optical waveguide terminal, 23 is a connection guide pin, 24 is a guide pin fixing groove, 25 is an adhesive, 26 is an optical fiber plug, 27 is an optical fiber terminal, 28 is a guide pin receiving hole, and 29 is a holder.

As a waveguide type optical component, an optical waveguide circuit is formed on an optical waveguide substrate 21, and an optical waveguide terminal 22 is provided near an end surface on the substrate 21. Guide pin fixing groove 24 is a guide pin
In order to fix 23, two
The book is provided directly on the substrate 21. In the present embodiment, a Mach-Zehnder type optical interferometer circuit 20 for optical frequency multiplex communication is fabricated on a silicon substrate 21 based on a silica-based optical waveguide, and the substrate size is 25 mm × 25 mm. The guide pin 23 is fixed by an adhesive 25 such that a substantially lower half thereof is embedded in the guide pin fixing groove 24. In addition, approximately half of the length of the guide pin 23 protrudes from the end surface of the substrate 21.

The optical fiber plug 26 accommodates and fixes an input / output optical fiber terminal 27 in a holder 29, and has two receiving holes 28 for receiving guide pins in both sides of the optical fiber terminal 27 in the holder 29. This is provided in parallel. By inserting the guide pin 23 into the guide pin receiving hole 28, the connection between the optical waveguide terminal 22 and the optical fiber terminal 27 is automatically achieved. If it is desired to stop the connection, the plug 26 may be pulled out of the board 21 and is detachable.

As the optical fiber plug 26, it is advisable to divert a multi-core fiber connector structure developed for connecting optical fiber arrays. Therefore, the center line interval between the two guide pin receiving holes 28, 28 of the optical fiber plug 26 is
As an example, 4.6 mm according to the multi-core fiber connector specification
And The optical fiber terminal 27 is held on a plane connecting the center lines of the guide pin receiving holes 28, 28. Guide pin receiving hole
The inner diameter of 28 is 0.7 mm, and the outer diameter of the guide pin 23 is also set to 0.7 mm. Therefore, the guide pin spacing is 4.6mm
It is. The optical fiber terminals 27 and the optical waveguide terminals 22 are arranged with the same pitch.

Next, an example of position adjustment of the guide pin will be described with reference to FIG.

FIG. 2 is a view for explaining an assembling process of the connector shown in FIG. The guide pin fixing groove is previously formed on the substrate 21
24 are formed, but the guide pins 23 are not fixed. It is assumed that the optical fiber plug 26 is separately manufactured.

When assembling, first, the two guide pins 23 are inserted into the two guide pin receiving holes 28 of the optical fiber plug 26. Subsequently, the plug 26 is set on a fine adjustment table (not shown), and each guide pin 23 is inserted into the guide pin fixing groove 24 of the substrate 21.
The optical fiber terminal 27 in the plug 26 is the optical waveguide terminal of the substrate 21
The position of the plug 26 is adjusted so as to just abut the guide pin 22, and the guide pin 23 is fixed in the guide pin fixing groove 24. Note that a small amount of an adhesive (not shown) is preferably applied to the guide pin fixing groove 24 in advance. It is also advisable to introduce monitor light (not shown) into the optical fiber terminal 27 and adjust the position while monitoring the optical axis alignment with the optical waveguide terminal 22 online.

As is clear from the above description, the guide pin fixing groove 24 is provided with a clearance of about 0.01 to 0.1 mm with respect to the guide pin 23, and the guide pin 23 has a clearance of 0.
Since the optical waveguide terminal 22 and the optical fiber terminal 27 can move easily by about 01 to 0.1 mm, the optical axis can be easily adjusted. When the optical axis alignment is completed, this state is kept as it is until the adhesive is cured, and the guide pin 23 is fixed in the guide pin fixing groove 24 of the substrate 21. Once the guide pins 23 are fixed, the optical fiber plug 26 can be pulled out of the substrate 21. Also, by standardizing the optical fiber plug, it can be easily replaced with another plug.

Next, an example of processing the substrate 21 will be described with reference to FIG.
FIG. 3 shows a substrate 21 with an optical waveguide shown in FIGS. 1 and 2.
FIG. 4 is a diagram for explaining a manufacturing process of the optical waveguide, and shows a cross section near an optical waveguide terminal.

First, as shown in FIG. 3 (a), a silica-based glass core portion 31 having a cross-sectional dimension of 7 μm × 7 μm is embedded in a silica-based glass clad layer 32 having a thickness of 50 μm on a silicon substrate 21 having a thickness of 0.2 mm. Thus, two quartz single mode optical waveguides were formed. The formation method was based on a known combination of a glass film deposition technique by a flame hydrolysis reaction and a microfabrication technique by reactive ion etching. The pitch of the core 31 was set to 0.250 mm in accordance with the pitch of the optical fiber terminal.

Subsequently, as shown in FIG.
0.36 mm depth, width on the cladding layer 32 and substrate 21 on both sides of 31
A 0.71 mm guide pin fixing groove 24 was formed by machining with a diamond drill. The center interval between the guide pin fixing grooves 24, 24 was set to 4.6 mm in accordance with the center line interval of the guide pin receiving holes of the optical fiber plug.

Finally, as shown in FIG. 3 (c), the guide pin 23 is inserted into the guide pin fixing groove by the assembling process shown in FIG.
24, the optical waveguide terminal and the optical fiber terminal were aligned with each other, and then fixed with an adhesive 25 to obtain a desired connector configuration.

The connection loss of the connector configured in the above embodiment is 0.5 d
About B / point. In addition, a refractive index matching agent was put on the joint surface between the optical waveguide terminal 22 and the optical fiber terminal 27, but if the use of the matching agent is not desired, both terminals 22, 27 are polished, and a spring mechanism or the like is used. A structure for crimping the two terminals 22 and 27 may be employed.

Although the guide pin fixing groove 24 is formed by machining in the above embodiment, a glass film, reactive ion etching, anisotropic etching of a silicon substrate, or the like may be used instead.

By the way, in a case where the optical fiber plug 26 is frequently attached and detached, it is desirable to further strengthen the guide pin fixing groove portion. FIG. 4 is a view for explaining an embodiment of a connector suitable for such a purpose, and shows a cross section of a guide pin fixing portion. The difference from the embodiment of FIG. 1 described above is that the guide pin 23 is held between the guide pin fixing groove 24 and the newly provided guide pin fixing lid 41, and is fixed by the adhesive 25. Have been. According to the configuration of FIG. 4, the guide pins 23 are more firmly held on the substrate 21 than in the case of FIG.

In the embodiment shown in FIGS. 1 to 4, the case where the optical fiber terminal 27 has two cores is described for convenience.
The present invention can also be applied to multi-core optical fiber terminals such as core, 8-core, and 10-core.

Also, insert the guide pin 23 into the guide pin fixing groove 24 with adhesive.
Although fixed and held at 25, a method such as soldering can be used instead of the adhesive. In this case, the guide pin fixing groove 24 and the like are preliminarily subjected to a metallizing process to enhance the bonding property with the solder.

<Effects of the Invention> As described above, according to the connector structure of the present invention, an input / output optical fiber can be detachably attached to a large-sized waveguide-type optical component that has been impossible in the past. This is particularly effective when applied to large-scale integrated optical components such as a multi-channel optical multiplexing / demultiplexing circuit. Further, since the guide pins are directly fixed on the optical waveguide substrate without using a special base, there is also an effect that stability with respect to a temperature cycle is excellent.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of an optical waveguide / optical fiber connection connector according to an embodiment of the present invention, FIG. 2 is an explanatory view of a method of assembling the connector of FIG. 1, and FIG. 3 is a connector of FIG. FIG. 4 is a sectional view showing a guide pin fixing structure according to another embodiment of the present invention, and FIGS. 5 and 6 show the configuration of a conventional optical waveguide / optical fiber connector. It is a perspective view. In the drawing, 20 is an optical waveguide circuit (Mach-Zehnder type optical interferometer circuit), 21
Is a substrate, 22 is an optical waveguide terminal, 23 is a guide pin, 24 is a guide pin fixing groove, 25 is an adhesive, 26 is an optical fiber plug, 27
Is an optical fiber end, 28 is a guide pin receiving hole, 29 is a holder, 31 is an optical waveguide core, 32 is an optical waveguide cladding layer, 41
Is a guide pin fixing lid.

Continuing from the front page (72) Motohiro Nakahara, Inventor 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Toshiaki Satake 1-16-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation In-company (56) References JP-A-55-9916 (JP, A) JP-A-55-100514 (JP, A) JP-A-2-125209 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) G02B 6/30

Claims (1)

(57) [Claims] 1. A substrate, an optical waveguide terminal installed on the substrate, two guide pin fixing grooves provided directly along the surface of the substrate and reaching the end surface of the substrate, and fixing each guide pin. An optical waveguide substrate including two guide pins fixed to the grooves with a fixing material such as an adhesive or solder and having one end protruding from an end surface of the substrate; and a holder accommodating an optical fiber terminal to be coupled to the optical waveguide terminal. And an optical fiber plug provided in the holder and having two guide pin receiving holes for detachably receiving the guide pins, wherein the guide pin fixing groove is provided in the guide pin fixing groove. The pin has a movable clearance, and when the guide pin of the optical waveguide substrate is inserted into the guide pin receiving hole of the optical fiber plug, the optical waveguide terminal and the optical fiber terminal The position of the guide pin, the position of the optical waveguide terminal, the position of the guide pin receiving hole and the position of the optical fiber terminal are adjusted so that the optical axis is automatically aligned, and the guide pin is inserted into the guide pin receiving hole. In the inserted state, the position is adjusted in advance in the clearance of the guide pin fixing groove so that the optical axes of the optical waveguide terminal and the optical fiber terminal are aligned, and the optical waveguide terminal and the optical fiber terminal are fixed to the guide pin fixing groove by the fixing material. And connecting and disconnecting the optical waveguide terminal and the optical fiber terminal by inserting and removing the guide pin fixed to the guide pin fixing groove and the guide pin receiving hole. Fiber connector.