JP2003255172A - Optical fiber array and its fixing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for fixation to a structure, a module, etc., which makes it possible to manufacture an optical fiber array where the positions of optical fibers are prescribed with high precision by an easy and realistic means as to the structure of an optical fiber array held and fixed between a V-groove substrate 11 and a fixed substrate. <P>SOLUTION: The optical fiber array comprising the V-groove substrate where a plurality of V grooves for optical fiber installation are arrayed, optical fibers mounted in the V grooves, and a fixing substrate which holds the optical fibers in the V grooves of the V-groove substrate is characterized in that the fixing substrate is wider than the V-groove substrate in the array direction of the V grooves and the bottom surface of the fixing substrate that the optical fibers come into contact with has ≤1 μm flatness and 0.005 to 0.1 μm mathematical mean roughness. <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 an optical fiber array for aligning a plurality of optical fibers used in optical connectors and optical modules used for optical communication and the like, and a fixing method thereof.

[0002]

2. Description of the Related Art In order to align and fix a plurality of optical fibers while keeping their optical axes parallel, it is common to use a structure as shown in FIG. FIG. 4A is a sectional view, and FIG.
(B) is a perspective view. After the optical fiber wire portions 31 are respectively installed in the V grooves 41 formed in parallel to the V groove substrate 11, a holding fixed substrate 24 for fixing the optical fiber in the V groove is covered from above to form a void portion. The adhesive 51 is filled in and fixed.

Regarding the shape of the fixed substrate 24 for pressing, a rectangular shape is often used, and the width thereof is usually made to match the width of the V groove substrate 11 in which the V groove 41 is formed. The cross-sectional shape of the optical fiber array 4 is a rectangular integral shape. After that, the side surface of the optical fiber bare wire portion 31 on the side where the end surface is located is polished to align the position of the optical fiber end surface in the optical axis direction (JP-A-5-224).
097 publication).

There is also an optical fiber array having a structure as shown in FIG. 5 for the purpose of cost reduction. 5A is a sectional view and FIG. 5B is a perspective view. The fixed substrate 25 and the V which are longer than the width of the V-groove substrate 11 in the arrangement direction of the V-groove 41
The optical fiber element wire portion 31 is sandwiched between the grooved substrates 11 and bonded and fixed with an adhesive 51 to form an optical fiber array. A hole portion 35 is provided in the fixed substrate 25, and the exposed bottom surface 65 of the fixed substrate 25 is brought into contact with a substrate such as a module so that the hole portion 35 can be used for fixing with a bolt or the like (special feature). Kaihei 12-304960).

The optical fiber array can be used as a component for coupling an optical element with an optical element arranged on a substrate made of silicon or the like. FIG. 6 shows a conceptual diagram of alignment of the conventional optical fiber array 4 shown in FIG. FIG. 6A is a side view and FIG. 6B is a sectional view. The substrate 26 is subjected to an edging process so that when the optical element 12 and the optical fiber array 4 are placed, they are all aligned with the optical axis surface 42. The optical fiber array 4 can be aligned in the height direction only by placing the bottom surface 71 of the V-groove substrate 11 on the substrate 46.

The optical fiber array 5 shown in FIG. 5 is used as shown in FIG. (A) is a side view and (b) is a sectional view. The substrate 22 is provided with a concave portion 52 having an appropriate depth so that the bottom surface 71 of the V-groove substrate 11 does not come into contact with the bottom surface 65 of the fixed substrate 21. After the bottom surface 65 of the fixed substrate 21 is placed on the substrate 22 for alignment, the screw holes formed on the upper surface of the substrate 22 are aligned with the hole portions 35 and fixed with bolts.

[0007]

When the alignment is performed by the method shown in FIG. 6, the dimensional accuracy from the bottom surface 71 of the V-groove substrate 11 to the center of the core of the optical fiber becomes important. However, in the conventional optical fiber array 4 shown in FIG.
Since the V groove 41 is generally processed by mechanical grinding or etching, the V groove depth variation for each product is 5 μm.
To some extent. Further, the thickness of the V-groove substrate 11 can be processed only with an accuracy of about 5 μm. for that reason,
When the optical element 12 is coupled with the bottom surface 71 of the V-groove substrate 11 as a reference, the height H from the bottom surface 71 of the V-groove substrate 11 to the center of the core of the optical fiber is displaced by about 10 μm. was there.

In the conventional optical fiber array 5 shown in FIG. 5, the optical element 1 is based on the bottom surface 61 of the fixed substrate 21.
Since it is coupled with V, it does not depend on the processing accuracy of the V-groove substrate 11, so the accuracy of the height H from the bottom surface 61 to the center of the core of the optical fiber is improved to about 5 μm. However, since only the alignment accuracy of fixing the fixed substrate 25 to the substrate 22 with the bolts 17 is taken into consideration, the surface accuracy of the bottom surface 65 was about 2 μm in flatness and about 1 μm in arithmetic mean roughness (Ra). Therefore, the substrate 22
Rattling occurred between the bottom surface 65 of the fixed substrate 25 and the fixed substrate 25, and highly accurate alignment could not be performed. Further, in alignment with the optical element 12, while the optical output is monitored so that the optical element 12 and the optical fiber array 5 have the maximum optical output, the upper surface 32 of the substrate 22 is slid to perform the alignment. Friction was generated between the substrate 25 and smooth fine adjustment. Further, when fixing the fixed substrate 25 with the bolt 17, there is a problem that a force is applied in the rotation direction of the bolt and the aligned position is displaced.

The present invention is to solve the above-mentioned problems in the conventional optical fiber array, and is a structure capable of producing an optical fiber array capable of highly accurate alignment by an easy and practical means. And its fixing method.

[0010]

A V-groove substrate in which a plurality of V-grooves for arranging an optical fiber are arranged, an optical fiber placed in the V-groove, and an optical fiber in the V-groove of the V-groove substrate. In an optical fiber array composed of a fixed substrate that holds the fixed substrate, the width of the fixed substrate is V with respect to the arrangement direction of the V grooves.
It is characterized in that it is longer than the width of the groove substrate, the flatness of the bottom surface of the fixed substrate with which the optical fiber contacts is 1 μm or less, and the arithmetic mean roughness (Ra) is 0.005 μm to 0.1 μm.

Further, in fixing the optical fiber array of claim 1 with a substrate such as a module, UV curing or an adhesive using both UV curing and heat curing is used.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 shows an embodiment of an optical fiber array structure according to the present invention. FIG. 1A is a sectional view, and FIG. 1B is an overall perspective view. V-groove substrate 11 for optical fiber array
A V-shaped groove 41 for positioning the optical fiber is formed in the. In each V-groove 41, the optical fiber element wire portion 31 from which the tip coating of the optical fiber 81 has been removed is arranged.
A fixed substrate 2 for holding a rectangular optical fiber from its upper surface
1 is covered.

The optical fiber element portion 31, the V-groove substrate 11 and the fixed substrate 21 are fixed by an adhesive 51. The width of the fixed substrate 21 is larger than that of the V-groove substrate 11, the bottom surface 61 of the fixed substrate 21 does not match the upper surface of the V-groove substrate 11, and the bottom surface 61 of the fixed substrate 21 is exposed. Has become. The flatness of the bottom surface 61 of the fixed substrate 21 is
The arithmetic average roughness (Ra) within 1 μm is polished with an accuracy of 0.001 μm to 0.1 μm.

Since the optical fiber strands 31 are aligned along the fixed substrate 21, the processing accuracy of the bottom surface 61 of the fixed substrate 21 is flatness of 1 μm or less and the arithmetic average roughness (Ra) is 0.0.
By setting the thickness within the range of 01 μm to 0.1 μm, the optical fiber element wire portions 31 aligned along the fixed substrate 21 can be aligned with high accuracy. Bottom surface 6 of fixed substrate 21
1 and the center of the core of the optical fiber are within the range of the shift amount depending only on the radius of the optical fiber. In the case of a commonly used single mode optical fiber, variations in optical fiber diameter and core eccentricity are 0.5 μm or less. Therefore, the bottom surface 61 of the fixed substrate 21 and the center of the optical fiber core can be aligned with an accuracy of 0.5 μm or less.

According to the embodiment of the present invention, since the bottom surface 61 of the fixed substrate 21 processed with high surface accuracy is exposed, the bottom surface 61 of the fixed substrate 21 can be used as a reference for easy alignment with an optical element or the like with high accuracy. it can. FIG. 2 shows a conceptual diagram of alignment and fixing. (A) is a side view and (b) is a sectional view. The substrate 22 is provided with a recess 52 having an appropriate depth so as not to come into contact with the bottom surface 71 of the V-groove substrate 11, and the bottom surface 61 of the fixed substrate 21 is brought into contact with the top surface 32 of the substrate 22 so that it can be placed. It has become. The upper surface 32 of the substrate 22 on which the bottom surface 61 of the fixed substrate 21 is placed is treated so that it can be aligned with the optical axis surface 42 in the height direction only by placing the optical fiber array. As described above, the bottom surface 61 of the fixed substrate 21 and the core of the optical fiber are 0.5 μm.
The optical fiber array 1 and the optical element 1 placed on the bottom surface 61 of the fixed substrate 21 are aligned with the following accuracy.
2 enables alignment in the height direction with an accuracy of 0.5 μm or less.

Further, since the bottom surface 61 of the fixed substrate 21 has a high surface accuracy, smooth fine adjustment is possible even in the position adjustment along the upper surface 32 of the substrate 22, and the surface direction can be adjusted to 1
Alignment can be performed with an accuracy of μm or less.

An adhesive 62 is used to fix the optical fiber array 1 and the substrate 22. After performing the above alignment,
An adhesive agent 62 is applied to the side surface of the fixed substrate 21 and adhered and cured to fix it to the substrate 22. A thermosetting adhesive is generally used as the adhesive, but the adhesive 62 is selected in consideration of the characteristic deterioration of the components due to heat and the subtle shift due to the difference in thermal expansion coefficient between the substrate 22 and the optical fiber array 1. , UV curable or UV
An adhesive that uses both curing and heat curing is used. The fixing with the UV curable adhesive is performed by applying the adhesive 62 and then irradiating it with UV light from the UV light source 72 to cure it, as described above. UV
When both curing and thermal curing are used, UV curing may be performed and temporary fixing may be performed, and then thermal curing may be performed to eliminate subtle shifts due to the difference in thermal expansion coefficient.

Materials for the V-groove substrate 11 and the fixed substrate 21 include quartz glass, Pyrex glass, borosilicate glass, crystallized glass and other glass materials, zirconia, alumina, silicon nitride, silicon carbide, aluminum nitride, cordierite, and the like. Silicon, such as ceramics having crystal particles containing mullite as a main component, is preferable. The materials of the V-groove substrate 11 and the fixed substrate 21 may be made of the same material, or different materials of the above materials may be used in combination if necessary.

As the kind of the adhesive 51, an ultraviolet curing epoxy resin, a thermosetting epoxy resin, an ultraviolet and thermosetting combined epoxy resin, an ultraviolet curing acrylic resin,
It is preferable to use an ultraviolet curable polyimide resin, a thermosetting acrylic resin, a thermosetting polyimide resin, or the like. Further, glass fiber, glass powder, carbon fiber, mineral powder or the like may be added to the above adhesive.

As the optical fiber 81, all kinds of optical fibers such as a single mode optical fiber, a multimode optical fiber, a polarization dependent optical fiber, a zero dispersion optical fiber and a plastic optical fiber can be used. A manufacturing process of the optical fiber array 1 will be described. V
With the surface on which the V groove 41 is formed facing upward, the groove substrate 11 is aligned with the optical fiber element wire portions 31 in alignment with the V groove 41 of the V groove substrate 11 and temporarily placed, and temporarily fixed with a small amount of adhesive 51. do. Next, the bottom surface of the fixed substrate 21 is placed on the upper surface of the V-groove substrate 11. Then, the adhesive 51 is injected and fixed in the gap between the fixed substrate 21, the V-groove substrate 11, and the optical fiber bare wire portion 31.

As shown in FIG. 3A, the V-groove substrate 13 may be provided with a step to provide a flat surface 23, and the optical fiber coating portion may be bonded and fixed at the flat surface 23. Also, the fixed substrate is shown in FIG.
As shown in (b), an appropriate step may be provided from the fiber alignment surface 33 to provide the flat surface 43, and the optical fiber array itself may adjust the alignment height position according to the thickness of the step of the fixed substrate.

Further, in FIG. 1, a structure may be adopted in which a gap is provided without making the tapered surface of the V groove 41 and the optical fiber 31 contact with each other, and the adhesive 51 is present in the gap. Further, although a plurality of optical fiber arrays have been described so far, it goes without saying that the structure according to the present invention can be applied to a single optical fiber alignment component.

[0023]

EXAMPLES Here, an experiment was conducted by the following method.

As an example of the present invention, the optical fiber array shown in FIG. 1 was prepared. Quartz glass was used as the material of the V-groove substrate 11, the V-groove 41 had 8 cores, and V-groove processing was performed by cutting. Further, the fixed substrate 11 is made of Pyrex glass, and the width in the optical fiber alignment direction is 4 times larger than that of the V-groove substrate 11.
The structure is made as large as mm. The optical fiber 81 is a single mode optical fiber. On the other hand, a conventional optical fiber array shown in FIG. 4 was prepared as a comparative example.

For the processing accuracy, the distance H between the alignment reference plane (bottom surface 71, bottom surface 61) of each fiber array and the core center of the optical fiber was measured, and the degree of variation from the average value was compared. As confirmation of improvement in processing accuracy, 50 samples each were prepared and measured. 10 V-groove substrates 11 were arbitrarily taken out from 10 processing lots and used. Table 1 shows the measurement results.

[0026]

[Table 1]

From the above results, the optical fiber array 4 shown in FIG. 4 which is a conventional example has a shift amount of 8.4 μm or less and a σ indicating the degree of dimensional variation is 2.81. It has been found that the optical fiber array 1 of the present invention shown in FIG. 1 has a maximum shift amount of 0.5 μm and a very small σ of 0.18. From the above, it was confirmed that the optical fiber array of the present invention has higher processing accuracy.

Further, in order to compare the alignment accuracy with the optical fiber array 5 shown in FIG. 5, the coupling loss after alignment with the optical element 12 and fixing was measured. Each sample was similarly prepared under the above experimental conditions. A UV-curable adhesive was used to fix the optical fiber array 1 of FIG. The optical fiber array 5 shown in FIG. 5 was fixed by using bolts. The measurement was performed on 10 samples each. Table 2 shows the measurement results.

[0029]

[Table 2]

It can be seen from Table 2 that the optical fiber array 1 according to the present invention has an average coupling loss lower than that of the conventional optical fiber 5 by 0.17 dB. From the above, it was confirmed that the optical fiber array of the present invention has higher alignment accuracy.

[0031]

As described above, according to the present invention, a V-groove substrate on which a plurality of V-grooves for arranging an optical fiber are arranged, and the V-groove is placed on the upper surface of the V-groove substrate to hold the optical fiber in the V-groove. And an optical fiber array composed of a fixed substrate to be fixed and an optical fiber, wherein the width of the fixed substrate is longer than the width of the V-groove substrate in the arrangement direction of the V-grooves. The flatness of the bottom surface of the fixed substrate in contact is 1 μm or less and the arithmetic average roughness (Ra) is 0.
With a feature of being 005 μm to 0.1 μm, it becomes possible to fabricate an optical fiber array capable of highly accurate alignment by an easy and practical means.

[Brief description of drawings]

FIG. 1 is a diagram showing an optical fiber array according to the present invention,
(A) is sectional drawing, (b) is a perspective view.

2A and 2B are conceptual views of alignment of an optical fiber array according to the present invention, in which FIG. 2A is a side view and FIG. 2B is a sectional view.

FIG. 3 is another embodiment of an optical fiber array according to the present invention.

FIG. 4 is a diagram showing an example of a conventional optical fiber array,
(A) is sectional drawing, (b) is a perspective view.

FIG. 5 is a diagram showing an example of a conventional optical fiber array,
(A) is sectional drawing, (b) is a perspective view.

6A and 6B are conceptual views of alignment of the conventional optical fiber array shown in FIG. 4, where FIG. 6A is a side view and FIG. 6B is a sectional view.

FIG. 7 is a conceptual diagram of alignment of the conventional optical fiber array shown in FIG. 5, (a) is a side view, and (b) is a sectional view.

[Explanation of Codes] 11: V-groove substrate 21: Fixed substrate 31: Optical fiber bare wire portion 41: V groove 51: Adhesive 61: Bottom surface of fixed substrate 71: V-groove substrate bottom surface 81: Optical fiber H: Alignment reference Height from surface to center of optical fiber core

Claims (2)

[Claims] 1. A V-groove substrate in which a plurality of V-grooves for arranging an optical fiber are arranged, and an optical fiber mounted in the V-groove,
In the optical fiber array including a fixed substrate that holds an optical fiber in the V groove of the V groove substrate, the width of the fixed substrate is longer than the width of the V groove substrate in the arrangement direction of the V grooves, and The flatness of the bottom surface of the fixed substrate with which the fiber contacts is 1 μm or less, and the arithmetic average roughness (Ra) is 0.0.
An optical fiber array having a thickness of 05 μm to 0.1 μm. 2. A method for fixing an optical fiber array, characterized in that a substrate such as a module and the optical fiber array according to claim 1 are fixed by using a photocurable adhesive and / or a thermosetting adhesive. .