JPH05264846A - Coupling device and coupling method for optical waveguide and optical fiber - Google Patents

Abstract

PURPOSE:To provide the device which couples optical fibers with good accuracy to a quartz optical waveguide without requiring the laborious adjustment for optical axis alignment. CONSTITUTION:This device is constituted by recessing core parts 4 at the coupling side end face 5 of the quartz optical waveguide 1 to form recessed parts 6, projecting core parts 7 on the coupling side end face 10 of the optical fibers 2 as projecting parts 9 and fitting the recessed parts 6 of the quartz optical waveguide 1 and the projecting parts 9 of the optical fibers 2. The core parts are inevitably disposed to face each other by the fitting of the recessed parts and the projecting parts, by which the coupling accuracy is improved and the easy mis-alignment is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coupling device and a coupling method for efficiently coupling a quartz optical waveguide and an optical fiber.

[0002]

2. Description of the Related Art In recent years, construction of optical communication systems such as LAN and CATV has become popular, and quartz optical waveguides used as optical branch circuits, optical multiplexers and the like have become more important as constituent elements. By the way, this quartz optical waveguide needs to be coupled with an optical fiber at its input / output portion. This coupling is performed by accurately opposing the core portion of the quartz optical waveguide and the core portion of the optical fiber. However, the core portion is usually about several μmβ to several tens of μm and cannot be easily bonded. Therefore, various coupling devices have been proposed.

A typical example of this conventional coupling device is shown in FIG.
Will be explained. Reference numeral 21 is an optical waveguide, and 22 is an optical fiber. The optical waveguide 21 has a clad 2 on a silicon substrate 23.
4 is laminated, and a core portion 25 is embedded in a predetermined portion of the clad 24. The optical fiber 22 is the core 2
6 and a clad 27 around it. In order to accurately couple the optical waveguide 21 and the optical fiber 22, a concave groove 28 is formed with the core portion 25 of the optical waveguide 21 as a reference, and the tip of the optical fiber 22 is pushed into the concave groove 28. The core part 26 of 22 and the core part 25 of the optical waveguide 21 are opposed to each other and are fixed with an adhesive or the like. Further, instead of the guide of the groove, a guide wall is formed (see Japanese Patent Publication No. 3-24642),
A device having a V groove (see Japanese Patent Laid-Open No. 61-185991) has been proposed.

[0004]

In all of the conventional coupling devices, a guide such as a groove is formed in the optical waveguide with the core portion as a reference, and the entire tip of the optical fiber is positioned by this guide. .. Therefore, provide guides such as grooves to the core with high precision, and pay close attention to prevent misalignment when fixing optical fibers in guides such as grooves with adhesive. Required to do so.

However, even if these precautions are taken with great care, it is premised that the optical fiber cross section is a perfect circle and the core is not eccentric. However, unless the optical fiber is a perfect circle and has no eccentricity, it is inevitable that the core of the optical fiber is displaced from the axial center of the core of the optical waveguide.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is not to require troublesome adjustment for optical axis alignment.
An object is to provide a coupling device and a coupling method for accurately coupling an optical fiber to a quartz optical waveguide.

[0007]

In order to achieve the above-mentioned object, the coupling device of the present invention has a recessed core portion at the coupling-side end face of a quartz optical waveguide, and a core at the coupling-side end face of an optical fiber. The projection is a convex portion, and the concave portion of the quartz optical waveguide and the convex portion of the optical fiber are fitted and coupled to each other.

In the coupling method of the present invention, a positive type UV curable resin is applied to the end face of the quartz optical waveguide on the side of coupling with the optical fiber, and the UV curable resin is applied by injecting UV rays into the core portion from the other end face. The UV curing resin of the core part is removed by exposing the core part of
Thereafter, a concave portion forming step of forming a concave portion by etching the exposed core portion, a convex portion forming step of forming a convex portion on an end face of the optical fiber coupling side with the optical waveguide, and the optical fiber in the concave portion of the optical waveguide. And the convex-concave coupling step of inserting and coupling the convex portions.

[0009]

The core portion of the quartz optical waveguide is formed in the concave portion and the core portion of the optical fiber is formed in the convex portion. Therefore, when the concave portion and the convex portion are fitted together, the core portions inevitably face each other and are joined together. The accuracy is improved and it does not easily shift.

It is important to break the common wisdom that it is difficult to make the core of the optical waveguide hollow, and to form the quartz optical waveguide in the concave portion of the core. Therefore, a positive type ultraviolet curable resin is formed on the end face. After exposing the core portion of the ultraviolet curable resin by exposing the core portion of the ultraviolet curable resin by exposing the core portion of the ultraviolet curable resin from the other end surface to expose the core portion only by developing. The exposed core portion is etched to form a predetermined recess.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing a coupling state of the coupling device.

In FIG. 1, reference numeral 1 is, for example, a 1 × 8Y branched quartz optical waveguide, and 2 is a quartz optical fiber. This quartz optical waveguide 1 is for branching from one to eight,
Reference numeral 3 is a clad, and 4 is a core portion. In the illustrated example, a part of the coupling side end surface 5 is shown. The core portion 4 exposed on the end face 5 on the coupling side is formed in the recess 6. The quartz optical fiber 2 is composed of a core portion 7 and a clad 8, and the core portion 7 exposed at the coupling side end face 10 thereof is formed in a convex portion 9.
The truncated conical hole-shaped guide hole 11 concentric with the concave portion 6 of the quartz optical waveguide 1 is formed of silicon or the like, and is a preliminary guide for fitting the convex portion 9 of the quartz optical fiber 2 into the concave portion 6. Has become.

Since the coupling is completed by fitting the convex portion 9 of the quartz optical fiber 2 into the concave portion 6 of the quartz optical waveguide 1 and the coupling device described above, the core portions 4 and 7 directly face each other. Therefore, even if there is an eccentricity between the core portion 7 and the clad 7 of the quartz optical fiber 2, the heart is not displaced. Further, since the coupling accuracy is determined by the concave and convex fitting, the guide hole 11 itself is not required to have such accuracy. Further, due to mechanical coupling such as concave-convex fitting, there is no displacement due to a slight external force, and there is no risk of displacement when filling the guide hole 11 with an adhesive or the like.

Next, the step of forming the concave portion of the quartz optical waveguide 1 will be described with reference to FIG. In FIG. 3A, a positive type ultraviolet curable resin 12 is applied to the end surface 5 on the coupling side, ultraviolet rays UV are incident on the core portion 4 from the other end side, and only a portion corresponding to the core portion 4 of the ultraviolet curable resin 12 is applied. Is exposed to UV light. In FIG. 2B, the ultraviolet curable resin 12 that has been exposed to light by developing is removed, and the end face of the core portion 4 is exposed. Thereafter, the core portion 4 is etched with an etching solution such as hydrofluoric acid that does not react with the ultraviolet curable resin 12 but reacts with the quartz of the core portion to form the recess 6. In the same figure (c), the remaining ultraviolet curable resin 12 is removed, and the predetermined recess forming step is completed.

Referring to FIG. 3, a process of forming a convex portion of the quartz optical fiber 2 by the same etching as the quartz optical waveguide will be described. In FIG. 3A, a negative type ultraviolet curable resin 13 is applied to the end surface 10 on the coupling side, and the core portion 7
UV light is incident on the core 7 of the UV curable resin 13.
Only the portion corresponding to is exposed to ultraviolet UV. In FIG. 2B, the portions other than the ultraviolet curable resin 13 that have been exposed to light by developing are removed, and the portions of the clad 8 other than the end faces of the core portion 7 are exposed. After that, the clad 8 is etched with an etching solution such as hydrofluoric acid that does not react with the ultraviolet curable resin 13 but reacts with the quartz of the core portion to form the protrusion 9. In the same figure (c), the remaining ultraviolet curable resin 13 is removed and the predetermined convex portion forming step is finished.

The step of forming the convex portion of the quartz optical fiber 2 is not limited to the above step, and FIG. 4 is an explanatory view of the simple method. An etching solution (for example, 6% by weight of hydrofluoric acid) which makes it easier to selectively etch the coupling end surface 10 of the quartz optical fiber shown in FIG.
An aqueous solution in which 30% by weight of ammonium fluoride is mixed with 64% by weight of water in a ratio of 5/6) is dipped to form the protrusions 9 as shown in FIG.

Further, FIG. 5 shows a step of forming a convex portion in which the ultraviolet curable resin itself is a convex portion. In FIG. 3A, an ultraviolet curable resin 13 is applied to the coupling-side end face 10 of the quartz optical fiber 2 and ultraviolet UV is incident on the core portion 7 from the other end side, which corresponds to the core portion 7 of the ultraviolet curable resin 13. Only part of it is exposed to UV light. In FIG. 3B, the portions other than the ultraviolet curable resin 13 exposed by the development are removed, the portions of the clad 8 other than the end faces of the core portion 7 are exposed, and the convex portions 9 are formed. In this case, UV curable resin 1
The property of 3 is selected appropriately so that the coupling efficiency is not deteriorated.

Then, as shown in FIG. 1, the quartz optical waveguide 1 having undergone the recess forming step of FIG. 2 and the quartz optical fiber 2 having undergone the convex forming step of FIG. The convex portion 9 is fitted into the concave portion 6 by means of and is coupled, and is fixed with an adhesive or the like in the coupled state.

[0019]

According to the coupling device of the present invention, the core portion of the quartz optical waveguide is formed in the concave portion, the core portion of the optical fiber is formed in the convex portion, and when the concave portion and the convex portion are fitted, the core portion is inevitably formed. Since the coupling accuracy is increased by facing each other, there is no need for troublesome optical axis alignment adjustment, and there is no fear that the coupling accuracy will decrease due to the misalignment between the core of the optical fiber and the cladding axis.

In the coupling method of the present invention, the common sense that it is difficult to make the core portion of the optical waveguide difficult to dent, the positive type UV curable resin is applied to the end face, and the UV ray is applied to the core portion from the other end face. To expose the core portion of the ultraviolet curable resin to remove the ultraviolet curable resin of the core portion by developing to expose only the core portion, and then etch the exposed core portion to form a predetermined concave portion. Since it is formed, the concave portion of the optical waveguide can be formed precisely and easily.

[Brief description of drawings]

FIG. 1 is a diagram showing a coupled state of a coupling device of the present invention.

FIG. 2 is a diagram showing a recess forming step in which a core portion of an optical waveguide is recessed.

FIG. 3 is a diagram showing a step of forming a convex portion in which a core portion of an optical fiber is convex.

FIG. 4 is a diagram showing another step of forming a convex portion in which the core portion of the optical fiber is a convex portion.

FIG. 5 is a diagram showing still another convex portion forming step in which the core portion of the optical fiber is made into a convex portion.

FIG. 6 is a perspective view showing a coupled state of a conventional coupling device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quartz optical waveguide 2 Quartz optical fiber 4 Quartz optical waveguide core part 5 Coupling side end face 6 Recessed part 7 Quartz optical fiber core part 9 Convex part 10 Coupling side end face 12 Positive type UV curable resin 13 Negative type UV curable resin

Claims (2)

[Claims] 1. A concave portion in which the core portion on the coupling-side end surface of the quartz optical waveguide is depressed and a convex portion in which the core portion on the coupling-side end surface of the optical fiber is projected are provided, and the concave portion of the quartz optical waveguide and the convex portion of the optical fiber are formed. A device for coupling an optical waveguide and an optical fiber, which are fitted and coupled to each other. 2. A positive type ultraviolet curable resin is applied to the end face of the quartz optical waveguide on the side of coupling with the optical fiber, and ultraviolet rays are made incident on the core part from the other end face to expose the core part of the ultraviolet curable resin, The UV curable resin on the core portion is removed by developing, and then the exposed core portion is etched to form a concave portion, and a convex portion is formed on the end face of the optical fiber coupled to the optical waveguide. A method of coupling an optical waveguide and an optical fiber, comprising: a step of forming a convex portion; and a concave-convex coupling step of inserting a convex portion of the optical fiber into a concave portion of the optical waveguide and coupling them.