JPH0651155A - Method for connecting optical fiber and optical waveguide - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the connection loss by shortening the work time for connecting an optical fiber and an optical waveguide, and improve the temperature characteristics and wet heat characteristics. A light for connecting an end face of a ferrule 14 and an end face of a waveguide substrate 15 to each other and connecting one end of an optical fiber 13 sandwiched by the ferrule 14 and one end of an optical waveguide 17 formed on the waveguide substrate 15 to each other. In the method of connecting a fiber and an optical waveguide, the ferrule 14 is made of crystallized glass that easily transmits ultraviolet rays and has a coefficient of thermal expansion of 2.4 × 10 ⁻⁶ / ° C. which is almost equal to the coefficient of thermal expansion of the waveguide substrate 15. Then
An adhesive of an ultraviolet curable resin 16 is applied to the abutting portion of the end faces of the ferrule 14 and the waveguide substrate 15, the optical axes of the optical fiber 13 and the optical waveguide 17 are aligned, and then the ultraviolet curable resin 16 is applied. By uniformly irradiating the entire abutting portion with ultraviolet rays from the outside, the abutting portion of the end face is bonded and fixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting an optical fiber and an optical waveguide, and more particularly to a method for connecting an optical fiber and an optical waveguide using an ultraviolet curing adhesive.

[0002]

2. Description of the Related Art Conventionally, a ferrule, which is a fiber holder for holding the ends of arrayed optical fibers, is made of a hard material such as ceramic or glass and is mainly divided into those using a glass capillary and a V groove. However, at present, in terms of accuracy, glass capillaries are not often used, and those using V-grooves are the mainstream.

The ferrule using the V-groove has a lower part of the ferrule substrate in which one to many V-grooves are manufactured with high precision, and an upper part of the ferrule substrate sandwiching the optical fiber with the lower part of the ferrule substrate. The optical fiber is fixed by adhering the lower part and the upper part of the substrate, and then the end face abutted with the waveguide substrate is polished. Next, when connecting the produced ferrule and the waveguide substrate, the ferrule and the waveguide substrate are fixed to respective predetermined jigs,
After applying an adhesive consisting of an ultraviolet curable resin mainly on the abutting end faces of both, using the fine adjustment mechanism provided on at least one, after performing the end face abutting and optical axis alignment,
Ultraviolet rays are radiated from the outside to cure the adhesive, thereby fixing the two together, and connecting the optical fiber held by the ferrule and the optical waveguide formed on the waveguide substrate.

[0004]

However, in the above connection method, when the ultraviolet curable resin applied between the abutting end faces of the ferrule and the waveguide substrate is cured, the conventional ferrule is opaque to ultraviolet rays, and therefore the end face Since it was not possible to directly irradiate the butting portion with ultraviolet rays, it was difficult to uniformly and quickly cure the ultraviolet curable resin. Therefore, there is a problem that it takes time to connect, the ferrule and the waveguide substrate are easily displaced, and a connection loss is likely to occur. In addition, the thermal expansion coefficient of the ferrule and that of the waveguide substrate are greatly different, so that there is a problem in that the temperature characteristics and the wet heat characteristics are poor.

The present invention has been made in view of the above problems, and an optical fiber capable of reducing the connection loss by shortening the work time for connecting the optical fiber and the optical waveguide and improving the temperature characteristic and the wet heat characteristic. An object is to provide a method for connecting optical waveguides.

[0006]

In order to achieve the above object, in the present invention, an end face of a fiber holder and an end face of a waveguide substrate are butted against each other, and one end of an optical fiber held by the fiber holder, In a method for connecting an optical fiber and an optical waveguide for connecting one end of an optical waveguide formed on the waveguide substrate, the light transmittance is 20% or more per 1 mm in a wavelength range of 0.35 μm to 0.45 μm. ,
And, by the member whose coefficient of thermal expansion is 7 × 10 ⁻⁶ / ° C. or less,
By configuring at least a part of the fiber holder, between the abutting end faces of the fiber holder and the waveguide substrate, an ultraviolet curing adhesive is applied, and the ultraviolet curing adhesive is irradiated with ultraviolet light, A connection method is provided in which the abutting end faces are adhesively fixed and the optical fiber and the optical waveguide are connected to each other.

[0007]

The ferrule is made of a material that allows ultraviolet rays to easily pass therethrough, and the coefficient of thermal expansion of the ferrule is made substantially equal to that of the waveguide substrate. Therefore, it is possible to uniformly irradiate the entire abutting portion of the end face with ultraviolet rays, and it is possible to match the expansion and contraction of the ferrule and the waveguide substrate with respect to temperature change.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings of FIGS. FIG. 1 is a view showing an assembled state of a ferrule according to the present invention. In the first embodiment of the present invention, crystallized glass having a coefficient of thermal expansion of 2.4 × 10 ⁻⁶ / ° C., which transmits ultraviolet light easily and is approximately equal to the coefficient of thermal expansion of the waveguide substrate 15 described later, is precisely ground. Four parallel V-grooves 10 are engraved by processing to manufacture a ferrule lower substrate 11. Further, the ferrule upper substrate 12 is manufactured using the same crystallized glass. Next, in this embodiment, the lower part 11 of the ferrule substrate
In the V groove 10 of one end of the plurality of optical fibers 13,
The optical fiber 13 is accommodated between the ferrule lower substrate 11 and the ferrule upper substrate 12, and the end faces 11a and 12a of both substrates 11 and 12 are polished to make a transparent ferrule. 14 is produced (see FIG. 2).

The waveguide substrate 15 shown in FIG.
The optical waveguide 17 is formed by laminating silica glass having different refractive indexes on the i substrate to form the optical waveguide 17, or by laminating semiconductor thin films of various compositions on a special semiconductor substrate such as InGaAsP. There is a formed one. In addition,
The optical waveguides 17 are formed on the waveguide substrate 15 at the same intervals as the V grooves 10 formed in the lower portion 11 of the ferrule substrate.

Next, the ferrule 14 and the waveguide substrate 1
In connection with 5, the ultraviolet curable resin 16 is used as the adhesive as shown in FIG. Then, similarly to the conventional example, the optical fiber 13 sandwiched between the ferrules 14 by the fine adjustment mechanism (not shown) and the optical waveguide 1 formed on the waveguide substrate 15
After the optical axes of 7 are aligned, the ultraviolet curable resin 16 applied to the abutting portions of the end faces of the ferrule 14 and the waveguide substrate 15 is cured by ultraviolet irradiation from the outside, and the ferrule 14 and the waveguide substrate 15 are To connect. This completes the connection between the optical fiber 13 and the optical waveguide 17.

Therefore, in this embodiment, as compared with the conventional method, the ferrule is made transparent to ultraviolet rays so that the ultraviolet rays can be uniformly irradiated to the entire abutting portion of the end face.
The curing speed of the adhesive due to UV irradiation was fast and uniform, and the working time was able to be reduced to almost half. Due to this reduction in work time, the connection loss averages 0.
It was possible to reduce the level to 08 dB to a range not exceeding 0.1 dB at the maximum. Moreover, the temperature characteristic is from -10 ° C to 6
At 0 ° C., the fluctuation of the connection loss was ± 0.1 dB, which was a good value.

Although the ferrule has four V-grooves in the present embodiment, the present invention is not limited to this, and any number of V-grooves may be used. In the second embodiment of the present invention, a single crystal silicon chip having a coefficient of thermal expansion of 2.4 × 10 ⁻⁶ / ° C. that easily transmits ultraviolet rays and is approximately equal to the coefficient of thermal expansion of the waveguide substrate 15 described later is different. The same V as above due to isotropic etching
The groove 10 is formed, and the ferrule lower substrate 11 and the ferrule upper substrate 12 are similarly produced. Other steps are performed in the same manner as in the first embodiment, the ferrule 14 and the waveguide substrate 15 are connected, and the connection between the optical fiber 13 and the optical waveguide 17 is completed. In this embodiment, the anisotropic etching is used for engraving the V groove, but the present invention is not limited to this, and other processing means such as precision grinding may be used.

In the second embodiment, the same effect as that of the first embodiment can be obtained. It should be noted that the end surface 11a of the ferrule lower substrate 11 on the V-groove 10 side cannot be directly irradiated with ultraviolet rays, but the reason why such an effect is obtained is that the ferrule upper substrate 12 is transparent and therefore ultraviolet rays can be irradiated. It is considered that the impossible area is small. Further, in the present invention, the same effect as above can be obtained when the ferrule lower substrate 11 on the V groove 10 side is made of a transparent material and the ferrule upper substrate 12 is made opaque.

Therefore, in the above-described embodiment, the ferrule is made of a material that allows ultraviolet rays to easily pass therethrough, and the thermal expansion coefficients of the ferrule and the waveguide substrate are made substantially equal to each other. It is possible to uniformly irradiate the entire abutting portion of the end face, so that the optical fiber and the optical waveguide can be connected and fixed, and the expansion and contraction of the ferrule and the waveguide substrate with respect to the temperature change can be matched.

[0015]

As described above, according to the present invention, the end face of the fiber holder and the end face of the waveguide substrate are butted against each other, and one end of the optical fiber held by the fiber holder and the waveguide substrate are attached to each other. In a method for connecting an optical fiber and an optical waveguide for connecting one end of a formed optical waveguide, the fiber has a light transmittance of 20% or more per 1 mm in a wavelength range of 0.35 μm to 0.45 μm. By forming at least a part of the holder, applying a UV curable adhesive between the abutting end faces of the fiber holder and the waveguide substrate, and irradiating the UV curable adhesive with ultraviolet light, the abutting end face Since the spaces are bonded and fixed, the working time for connecting the optical fiber and the optical waveguide can be shortened to reduce the connection loss, and the temperature characteristics and the wet heat characteristics can be improved.

[Brief description of drawings]

FIG. 1 is a view showing an assembled state of a ferrule according to the present invention.

FIG. 2 is a configuration diagram of the ferrule shown in FIG.

3 is a diagram showing a connection state of the ferrule shown in FIG. 2 and a waveguide substrate.

[Explanation of symbols]

 10 V Groove 11 Ferrule Lower Substrate 12 Ferrule Upper Substrate 13 Optical Fiber 14 Ferrule 15 Waveguide Substrate 16 UV Curable Resin 17 Optical Waveguide

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kuji Yanagawa 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (2)

[Claims] 1. An end face of a fiber holder and an end face of a waveguide substrate are butted against each other to connect one end of an optical fiber held by the fiber holder and one end of an optical waveguide formed on the waveguide substrate. In the method for connecting an optical fiber and an optical waveguide, at least a part of the fiber holder is constituted by a member having a light transmittance of 20% or more per 1 mm in a wavelength region of a wavelength of 0.35 μm to 0.45 μm, An ultraviolet curable adhesive is applied between the abutting end faces of the fiber holder and the waveguide substrate, and the ultraviolet curable adhesive is irradiated with ultraviolet light to bond and fix the abutting end faces. How to connect optical fiber and optical waveguide. 2. The member constituting the fiber holder is
2. The method of connecting an optical fiber and an optical waveguide according to claim 1, wherein the material has a coefficient of thermal expansion of 7 × 10 ⁻⁶ / ° C. or less.