JP2023129736A - Fiber array and manufacturing method therefor - Google Patents

Abstract

To provide a fiber array in which optical fibers can be arranged highly accurately, preferably highly accurately and highly concentratedly (highly densely) in a cylindrical base substance along a plane including the axial center of the cylindrical base substance.SOLUTION: The cylindrical base material substance 100A of a round fiber array 100 is composed of a semi-cylindrical first glass base material 110, a semi-cylindrical second glass base material 120, and an adhesive layer 5D. A plurality of V grooves 111,,, and V grooves 121,,, are formed in a first plane portion 110A of the first glass base material 110 and a second plane portion 120A of the second glass base material 120. Optical fibers 1 are arranged in the V grooves 111 and V grooves 121 facing each other, and the first glass base material 110 and the second glass base material 120 are joined together at the first plane portion 110A and the second plane portion 120A, the optical fibers 1,,,, are arranged highly accurately on a plane (virtual plane S) including the axial center of the cylindrical base material substance 100A.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fiber array and a method for manufacturing the same, and more particularly to a small round fiber array suitable for high integration and a method for manufacturing the same.

In optical fiber communications (optical communications), high-performance optical fibers, planar lightwave circuits (PLCs), and wavelength division multiplexing circuits (WDMs) that multiplex signals on the wavelength axis of light are being developed one after another. As a result, the amount of communication that can be sent and received with optical communications has increased dramatically compared to conventional telecommunications.
Recently, with the rapid increase in traffic due to mobile networks, cloud computing, big data, etc., the transmission capacity required for optical communications is steadily increasing. Currently, optical digital coherent technology has been developed as a technology for transmitting high-speed optical signals of 100 Gbps, and practical development of 5th generation mobile communication systems is being carried out in various places.

Particularly in data centers, where huge amounts of data are processed at high speed, the optical devices used are required to be compact and highly integrated (requirement for compact optical devices).
The key components of the optical devices that make up these devices, that is, the lightwave circuits, are also required to be smaller in size as well as faster and larger in capacity. Naturally, a compact and highly accurate fiber array is required for the fiber array that inputs and outputs light to a light wave circuit.
"Pitch deviation" at the connection between the fiber array and the lightwave circuit causes connection loss and deteriorates optical characteristics, but lightwave circuits can be formed with a desired pitch by applying semiconductor technology.
Therefore, on the fiber array side, if small, multicore fiber arrays can be manufactured with high pitch accuracy, it is thought that small optical devices can greatly contribute to the construction of future optical communication networks.

In the technical field of conventional optical fiber communication, rectangular fiber arrays were mainly used, but as mentioned above, with the increasing demand for compact optical devices in recent years, round fiber arrays (capillaries), which are suitable for miniaturization, have been used. There is a growing desire to use

Round fiber arrays and rectangular fiber arrays used in light wave circuits and the like are used depending on the light wave circuit and the like of the optical communication device used.
Among these, rectangular fiber arrays have been proposed, for example, in Japanese Patent No. 4331250 and Japanese Patent No. 4698487. In these rectangular fiber arrays, the optical fibers are accommodated in grooves (V grooves) with a V-shaped cross section formed in a substrate, and are pressed down from above with a flat plate and fixed with an adhesive.

Furthermore, in a rectangular fiber array, V grooves are formed in the upper and lower substrates so as to face each other, and the optical fibers are held from above and below by these V grooves. It has been proposed in Japanese Patent Publication No. 2017-142275, etc.
Furthermore, a fiber array has been proposed in Japanese Patent Publication No. 2015-513127 in which a plurality of optical fibers are sandwiched between upper and lower sides of a base material whose cross section is not rectangular but elliptical. This Japanese translation of PCT publication No. 2015-513127 discloses a technique for holding and fixing optical fibers in a fiber array having an elliptical cross section using V grooves located above and below.

On the other hand, a so-called "round fiber array" having a cylindrical shape with a perfect circle in cross section has been proposed in Japanese Patent Publication No. 57-32910, Japanese Patent Application Publication No. 9-33752, and Japanese Patent Application Publication No. 2003-215400.

Published Practical Application No. 1983-32910 discloses the use of V-grooves to hold and fix optical fibers in a round fiber array.

For small round fiber arrays, for example, see Nakahara Photodenshi Research Co., Ltd.'s website "https://noel-sekiei.co.jp/technology/fiber_arrays.html" for round fiber arrays with insertion holes. array is proposed.
The small round fiber array proposed here does not require fixing a cylindrical member (capillary) with a lid, but instead uses ordinary optical fibers (optical fibers with a perfect circular cross section) and polarization-maintaining fibers in a circular manner. It has a structure in which it is inserted into a circular hole (insertion hole) formed in a columnar member.
The same website also discloses examples in which two holes (insertion holes) for inserting optical fibers are formed in a cylindrical member, and examples in which five holes are formed in a cylindrical member.

FIG. 16 shows a round fiber array 10 proposed by Nakahara Hikari Research Co., Ltd.
The round fiber array 10 is of a type in which two optical fibers 1, 1 are inserted into two insertion holes 11, 11 formed in advance in a glass base material. Two holes (not shown) are provided in advance, and this cylindrical base material can be manufactured by stretching it by a wire drawing process until it has a desired diameter.

Patent No. 4331250 Patent No. 4698487 Japanese Patent Application Publication No. 2008-145796 Japanese Patent Application Publication No. 2017-142275 Special Publication No. 2015-513127 Publication Practical Publication No. 57-32910 Japanese Patent Application Publication No. 9-33752 Japanese Patent Application Publication No. 2003-215400

Nakahara Photoelectronics Laboratory Co., Ltd. homepage (https://noel-sekiei.co.jp/technology/fiber_arrays.html)

In recent years, there has been a desire to use small round fiber arrays (capillaries) instead of square fiber arrays, and as mentioned above, highly accurate alignment with the light wave circuit side is required, so miniaturization is required. In round fiber arrays, the challenge is how to arrange optical fibers with high precision and high integration (narrow pitch).

As a round fiber array that has been miniaturized to meet the above demand, the round fiber array described in the above non-patent document has been commercialized, but the structure in which an insertion hole is provided and the optical fiber 1 is inserted, It is thought that it will not be able to adequately respond to the high precision (high precision and high integration) that is expected to become even greater in the future.
In the case of a round fiber array in which a plurality of insertion holes are formed in advance and optical fibers are inserted and fixed therein, a cylindrical base material of a predetermined shape (for example, 30 mm in diameter and 100 mm in length) is It is necessary to form two holes with high accuracy and draw them to form the fiber array (diameter 2 mm).
In this case, in order to achieve the pitch tolerance of the insertion holes of the round fiber array, long holes with a diameter of 2 mm must be accurately formed in the cylindrical base material before drawing (with a length of 100 mm). Even if an ultrasonic drill is used, the desired dimensional accuracy cannot be achieved.
Therefore, even a fiber array obtained by drawing a cylindrical base material with such precision does not have the desired dimensional precision, making it extremely difficult to achieve pitch tolerance. ,

Further, as shown in FIG. 16, when inserting a plurality of optical fibers 1, 1 into the insertion holes 11, 11 of the round fiber array 10, the diameter of the insertion holes 11, 11 is smaller than the diameter of the optical fibers 1, 1. Since the optical fibers 1, 1 are actually inserted into the insertion holes 11, 11 and fixed with adhesive, the center of the insertion holes 11, 11 and the center of the optical fibers 1, 1 will differ due to the difference in diameter. deviates, making it difficult to achieve pitch tolerance (pitch y, pitch y+Δy in FIG. 16(A)). If more holes (5) are formed as disclosed on the homepage mentioned above, it becomes even more difficult to achieve pitch tolerance.

Furthermore, as disclosed on the above homepage, if you want to provide a larger number (5) of insertion holes in a round fiber array, it is necessary to form the desired number of holes (5 insertion holes) in the base material in advance. After that, the wire must be drawn, which not only makes it difficult to obtain dimensional accuracy, but also requires a predetermined spacing between the holes to withstand the wire drawing, making it difficult to integrate highly integrated optical fibers. (Narrow pitch)

In addition, on the lightwave circuit side to which the round fiber array is connected, the cores of the optical fibers in the input/output section are normally arranged in a straight line with high precision, so the optical fibers mounted in this round fiber array are also aligned in a straight line. However, when three or more insertion holes are formed in a known round fiber array in which optical fibers are inserted into the insertion holes, it is difficult to accurately form the holes in a straight line in a cylindrical base material. In the round fiber array obtained by drawing the fibers, it is even more difficult to precisely arrange the insertion holes in a straight line.
In particular, when trying to arrange optical fibers in a straight line and in a highly integrated manner (narrow pitch) along a plane that includes the center line of a small round fiber array, the fiber cores must be arranged so that they touch each other within the fiber array. However, in the above-described known round fiber array 10, it is necessary to form the insertion holes separated from each other, so that high integration (narrow pitch) cannot be achieved.

In manufacturing a small-sized fiber array, in the round fiber array 10 described above, a plurality of (two) optical fiber cores 1a are inserted into a plurality of (two) insertion holes as shown in FIG. 16(B). At the same time, the fiber sheath must be inserted into the fiber array to a predetermined depth.
In order to prevent disconnection at the boundary between the fiber core and the fiber coating, a large-diameter portion corresponding to the diameter of the fiber coating is provided at the entrance of the insertion hole, and this large-diameter portion and the insertion hole are connected. It is necessary to process the gap into a tapered shape. For this reason, there is also the problem that the manufacturing process of the round fiber array becomes complicated.
As described above, the conventional round fiber array 10 cannot perform highly accurate positioning for multi-core fibers, and has only been put into practical use for connection with light wave circuits up to two fibers.
In addition, since the manufacturing method involves creating multiple holes in the base material and drawing the wire, it is not possible to precisely align the position of the insertion hole formed after drawing the wire with the input/output position of the light wave circuit, as described above. It becomes difficult.

Incidentally, in recent years, in the field of optical communications, there has been a desire to further increase the speed, specifically, to enable high-speed signal propagation processing of 100 Gbit/s or more.
Such high speeds cannot be achieved with simple binary ON/OFF processing; instead, coherent detection methods that detect the intensity and phase information of light and digital signal processing that multiplex high-speed signals are used in combination with digital signal processing. Coherent optical communication technology will be required.

For this coherent detection method and digital coherent optical communication technology, it is essential to use a polarization maintaining fiber as a new optical fiber.
Additionally, with the miniaturization of the entire equipment used for optical communication (optical fiber communication), a miniaturized round fiber array is required as described above, but in this miniaturized round fiber array, When connecting to a light wave circuit, it becomes necessary to align the core portions of the optical fibers to be connected with each other with high precision.
However, in the so-called "PANDA type optical fiber" among polarization-maintaining optical fibers, a material softer than the cladding base material is formed at a predetermined location of the cladding adjacent to the core portion of the optical fiber at the stage of the base material before drawing. Because of the provision of the curved region, the cross-sectional shape of the fiber is slightly distorted when it is drawn, and does not become a perfect circle (FIG. 17(A)).

Conventional round fiber arrays are designed on the assumption that the optical fibers to be mounted are perfect circles (for example, perfect circles with a diameter of 125 μm). A slight distortion of the wave-maintaining fiber causes the position of the core to shift slightly (Δh in FIG. 17(B)).
Therefore, if optical fibers with a perfect circular cross-section and polarization-maintaining fibers with distorted cross-sections are mixed and mounted in a round fiber array, the core positions of the optical fibers with a perfect circular cross-section and the polarization-maintaining fibers will be shifted by Δh. It will shift slightly.

In recent years, in optical communication systems that require higher performance, a slight core misalignment (Δh) in this fiber array causes a misalignment in the connection at the input/output section of the light wave circuit, and this misalignment (Δh) causes optical loss. The problem arises that it becomes larger.

The present invention has been made in view of the above circumstances, and is a small circular fiber array in which multi-fibers (multiple fibers) can be arranged with high precision along the center line of a perfect circle in a round fiber array with a perfect circle cross section. The present invention aims to provide a shaped fiber array and a method for manufacturing the same.
Another object of the present invention is to provide a round fiber array with a perfect circular cross section, in which fibers can be arranged with high precision and high density along a plane including an axis (center line). The purpose is to provide a manufacturing method thereof.
Still another object of the present invention is to provide a round fiber array with a perfect circular cross section and a method for manufacturing the same, in which fibers with a perfect circular cross section and polarization maintaining fibers can be arranged at the same time with high precision and with high integration. The purpose is to

In order to achieve the above object, the round fiber array of the first invention of the present application includes a semi-cylindrical first base, a semi-cylindrical second base, the first base and the second base. a cylindrical base consisting of an adhesive layer provided between the fibers, and a plurality of first fiber holding grooves formed in the axial direction in a first flat part formed in the axial direction of the first base. A plurality of second fiber holding grooves facing the first fiber holding grooves are formed in a second flat part formed in the axial direction of the second base, and a plurality of second fiber holding grooves facing the first fiber holding grooves are formed in the second flat part formed in the axial direction of the second base. A plurality of optical fibers are arranged between the first fiber holding groove and the second fiber holding groove, and the adhesive layer is filled between the first plane part and the second plane part. It is made of a chemical agent.

Further, in the round fiber array of the second invention of the present application, in the first invention, the first base is formed by cutting a cylindrical base material having a perfect circular cross section parallel to a plane including the axis. The second base is formed into a semi-cylindrical shape by cutting a cylindrical base material having a perfect circular cross section parallel to a plane including the axis, 1, the first plane part is further formed by cutting a plane including the axis of the cylindrical base material to a depth of 1/2 of the adhesive layer, and the second base part Further, the second plane portion is formed by cutting a plane including the axis of the cylindrical base material to a depth of 1/2 of the adhesive layer, and the first base portion and the second The cylindrical base body made of the base and the adhesive layer has a cylindrical shape with a perfect circle in cross section.

Further, in the round fiber array of the third invention of the present application, in the first or second invention, the thickness of the adhesive layer is adjusted between the first flat part and the first flat part by the adhesive due to capillary action. The thickness is such that it penetrates between the two flat parts.
Moreover, in the round fiber array of the fourth invention of the present application, in any one of the first to third inventions, the optical fibers held in the first fiber holding groove and the second fiber holding groove are provided. The diameter of the fiber holding groove is 125 μm, and the first fiber holding groove and the second fiber holding groove are both formed at a pitch of 127 μm.

Further, in the round fiber array of a fifth invention of the present application, in any one of the first to fourth inventions, the first plane portion is connected to two first adhesive portions provided at both ends. a first clamping part sandwiched between the first adhesive part, the first fiber holding groove is formed in the first clamping part, and the second flat part is provided at both ends. It consists of two second bonding parts and a second holding part sandwiched between the second bonding parts, the second holding groove is formed in the second holding part, and the second holding groove is formed in the second holding part, and the second holding groove is formed in the second holding part. The top of the section is formed deeper than the surface of the first bonding section, and the top of the second clamping section is formed deeper than the surface of the second bonding section.

Further, in the round fiber array of a sixth invention of the present application, in any one of the first to fifth inventions, the first fiber holding groove and the second fiber holding groove have a cross section of an equilateral triangle. It has a V groove.
Further, in the round fiber array of the seventh invention of the present application, in the sixth invention, the depth of the V-groove is smaller than the diameter of the optical fiber to be mounted by 1/2 of the thickness of the adhesive layer. be.
Further, in the round fiber array of the eighth invention of the present application, in the sixth or seventh invention, a plurality of optical fibers are arranged in the first holding part so that their core wires are in contact with each other, and The V-grooves are arranged in a straight line, and the depth of the V-grooves is greater than at least 3/4 of the diameter of the optical fiber.
Further, in the round fiber array of a ninth invention of the present application, in any one of the first to eighth inventions, the plurality of optical fibers are optical fibers with a perfect circular cross section and polarization maintaining fibers. , a first V-groove and a second V-groove having different depths are formed in the first plane part, and a first V-groove and a second V-groove are formed in the second plane part at a position facing the first V-groove. A third V-groove having the same depth as the first V-groove, and a fourth V-groove having the same depth as the second V-groove are formed at a position facing the second V-groove, and The depths of the V-groove and the third V-groove are determined according to the diameter of the optical fiber and the thickness of the adhesive layer, and the depths of the second V-groove and the fourth V-groove are determined so that the cross section is correct. It is determined based on the difference between the core position when the optical fiber is placed in the triangular V-groove and the core position when the polarization maintaining fiber is placed.

Further, the method for manufacturing a fiber array according to the tenth invention of the present application includes the step of cutting a cylindrical base material having a perfect circular cross section to a predetermined depth from a plane including the axis to form a semi-cylindrical base material. , forming a plurality of V grooves extending in the axial direction in the axial plane portion of the semi-cylindrical base material; and cutting the semi-cylindrical base material at a plurality of locations to form a plurality of first base portions and a plurality of first base portions. arranging an optical fiber along a plurality of V-grooves in the axial plane part of the semi-cylindrical base material that will become the first base; joining an axial plane part of the semi-cylindrical base material, which will become the second base part, to an axial plane part of the arranged first base part so that their V grooves overlap; filling an adhesive into a gap created between the axial plane part of the semi-cylindrical base material serving as the first base and the axial plane part of the semi-cylindrical base material serving as the second base; Contains.

Further, in the method for manufacturing a fiber array according to the eleventh invention of the present application, both ends of the axial plane part of the semi-cylindrical base material which becomes the first base part and the semicircular part which becomes the second base part forming two V-grooves at both ends of the axial plane portion of the columnar base material; and forming a plurality of V-grooves between the two V-grooves, the plurality of V-grooves In the forming step, the apex of the convex portion formed between adjacent V grooves is formed lower than the first base portion and the second axial plane portion.

Further, in the method for manufacturing a fiber array according to the twelfth invention of the present application, in the tenth or eleventh invention, when forming the V-groove, the V-groove is formed based on the diameter of the optical fiber with a circular cross section to be mounted. a step of determining the depth of the V-groove and forming a V-groove, a step of arranging the optical fiber and the polarization-maintaining fiber in the V-groove and detecting a difference between the two core positions, and based on the detected difference. , determining the depth of a V-groove in which the polarization maintaining fiber is placed.

According to the first aspect of the present invention, a plurality of optical fibers are arranged between the first fiber holding groove and the second fiber holding groove that face each other, and the first flat part and the second fiber holding groove Since the optical fibers are fixed with the adhesive filled between the two flat parts, the plurality of optical fibers can be arranged with high precision on a plane including the center (axis) of the cylindrical base.
Further, according to the second invention of the present application, the first base is cut from a plane including the axis of the cylindrical base material to a depth of 1/2 of the adhesive layer, and the second base is also cut from the plane including the axis of the cylindrical base material. Since the plane including the axis of the cylindrical base material is cut to a depth of 1/2 of the adhesive layer, and the adhesive layer is provided in between, the first base, the second base, and the adhesive layer The cylindrical base body has a cylindrical shape with a perfect circular cross section, and the plurality of optical fibers arranged between the first fiber holding groove and the second fiber holding groove have a perfect circular cross section. can be arranged in a straight line with high accuracy on a plane including the axis of the cylindrical columnar base.

Further, according to the third invention of the present application, the thickness of the adhesive layer is such that the adhesive spreads over the entire surface due to capillary action without forming bubbles, so the amount of adhesive that is more brittle than that of the cylindrical base material is can be minimized to maintain the overall strength of the fiber array.
Further, according to the fourth invention of the present application, optical fibers having a diameter of 125 μm can be arranged at a pitch of 127 μm in accordance with the standard.

Furthermore, according to the fifth invention of the present application, when a plurality of optical fibers are arranged so that their core wires are in contact with each other, it is possible to prevent the groove portions from interfering with each other.
Further, according to the sixth invention of the present application, the first fiber holding groove and the second fiber holding groove can be easily cut, and the depth of the V groove can be easily designed. I can do it.
Further, according to the sixth invention of the present application, the depth of the V-groove can be made smaller by 1/2 the thickness of the adhesive layer than the diameter of the optical fiber to be mounted, and the optical fiber can be inserted into the inside of the V-groove. can be accommodated, and at this time, the gap between the first plane part and the second plane part, that is, the adhesive layer can be adjusted to a desired thickness.

According to the eighth invention of the present application, when arranging the plurality of optical fibers in the first holding part so that their core wires are in contact with each other and in a straight line, the depth of the V groove is arranged. If the V-groove is made even slightly larger than 3/4 of the diameter of the optical fiber, the optical fiber can be held securely in the V-groove.
Further, according to the ninth invention of the present application, even when optical fibers with a perfect circular cross-sectional shape and polarization-maintaining fibers with a distorted cross-sectional shape are mixed and mounted in a fiber array, the core of the optical fiber The cores of polarization maintaining fibers can be arranged on the same plane with high precision.

Further, according to the tenth invention of the present application, the optical fibers to be mounted can be arranged and mounted with high precision along a plane including the axis of the round fiber array.
Further, according to the eleventh invention of the present application, it is possible to arrange and mount the optical fibers so that their core wires are in contact with each other.
Further, according to the second invention of the present application, an optical fiber with a perfect circular cross-sectional shape and a polarization-maintaining fiber with a distorted cross-sectional shape are arranged so that the core of the optical fiber and the core of the polarization-maintaining fiber are on the same plane. It can be placed with high precision.

FIG. 1 is a perspective view of a round fiber array 100 according to a first embodiment. FIG. 2 is a diagram showing a cross section of the semi-cylindrical first glass base 110. FIG. 3 is a diagram illustrating the shape of the V-groove 111 formed in the first flat portion 110A of the first glass base 110. FIG. 4 is a diagram showing a method of grinding the V-groove 111 and the tapered portions 110B and 120B in the semi-cylindrical base material 101A. FIG. 5 is a perspective view showing the procedure for assembling the round fiber array 100. FIG. 6 is a diagram illustrating the positions of the V-grooves 111 and 121 on the connection surface 100X of the round fiber array 100 and the optical fibers 1 mounted thereon. FIG. 7 is a diagram showing an example in which common optical fibers 1 and polarization maintaining fibers 2 are mixed and mounted in a round fiber array 100. FIG. 8 is a perspective view of a round fiber array 200 according to the second embodiment. FIG. 9 is a perspective view showing the procedure for assembling the round fiber array 200. FIG. 10 is a diagram illustrating the V-grooves 211 and 221 on the connection surface 200X of the round fiber array 200 and the positions of the optical fibers 1 mounted thereon. FIG. 11 is a diagram for explaining the shape of the V-grooves 211, 221 when the optical fibers 1, 1, . . . are arranged at a narrow pitch (127 μm) adjacent to each other. FIG. 12 is a diagram showing an example in which optical fibers 1, 1, . . . are mounted at a narrow pitch (127 μm) in a round fiber array 200. FIG. 13 is a diagram showing an example in which common optical fibers 1 and polarization maintaining fibers 2 are mixed and mounted in a round fiber array 200. FIG. 14 is a diagram showing a method of narrowing the gap H between the first plane part 210A and the second plane part 220A while arranging the optical fibers 1, 1, . . . at a narrow pitch in the round fiber array 200. FIG. 15 is a diagram showing an example of arrangement of V-grooves in a round fiber array 200 formed by thinning out V-grooves. FIG. 16 is a front view and a perspective view showing the structure of a known round fiber array 10. FIG. 17 is a diagram for explaining the cross-sectional shapes of a typical optical fiber 1 and polarization-maintaining fiber 2, each having a perfect circular cross-section, and the core deviation Δh when they are arranged in a V-groove.

(First embodiment)
FIG. 1 is a perspective view of a small round fiber array 100 of a first embodiment.
As shown in the figure, the round fiber array 100 consists of a first glass base (first base) 110 and a second glass base (first base) that sandwich a plurality of optical fibers (single mode optical fibers) 1, 1, . A cylindrical base 100A having a perfect circular cross section is constituted by the base part 2) 120 and the adhesive layer 5D between them.
The first glass base 110 has a first plane part 110A (FIG. 2) formed in its axial direction, and a plurality of ( In this embodiment, five V grooves (first fiber holding grooves) 111, 111, . . . are formed. This V-groove 111 has an equilateral triangular cross section.
Further, the second glass base 120 is also formed with a second flat portion 120A in the axial direction, similar to the first glass base 110, and this second flat portion 120A is also formed in the axial direction of the second glass base 120. A plurality of V grooves (second fiber holding grooves) 121, 121, . . . having the same cross-sectional shape are formed along the V grooves 111, 111, . . . at positions facing the V grooves 111, 111, .

The first flat part 110A of the first glass base 110 and the second flat part 120A of the second glass base 120 are overlapped with each other with the optical fibers 1, 1,... sandwiched between them, and the gap H between them is An adhesive (photocurable adhesive) 5 is filled and fixed.
At this time, the optical fibers 1, 1, . . . are also held by the V-grooves 111, 111, . . . of the first plane portion 110A and the V-grooves 121, 121, . 5 (adhesive layer 5D).

Next, the shapes of the first glass base 110 and the second glass base 120 that constitute the columnar base 100A of the round fiber array 100 will be described. Note that the second glass base 120 has the same shape as the first glass base 110, except that the flat part 110E for alignment is not provided, and only the first glass base 110 will be described below. .
As shown in FIG. 2, the first glass base 110 is obtained by cutting a cylindrical base material 101 with a perfect circle in cross section and a diameter R (=2000 μm) from above (the upper side of FIG. 2(A)). 101 (indicated by a two-dot chain line in FIG. 2A) to a predetermined depth ΔD (=15 μm), which is approximately parallel to the virtual plane S. It is formed into a semi-cylindrical shape. The surface formed in the axial direction by this polishing becomes the first flat portion 110A.

Here, the predetermined depth ΔD (=15 μm) from the virtual plane S is 1/2 of the gap H between the first plane portion 110A and the second plane portion 120A.
When the round fiber array 100 is formed by fixing the gap H with the adhesive 5, the adhesive 5 that adheres the first plane part 110A and the second plane part 120A covers the entire surface by "capillary action". The value is determined within a desired thickness range that allows for even filling without bubbles.
In this embodiment, the value of ΔD is 15 μm on the first glass base 110 side and 15 μm on the second glass base 120 side, so the first glass base 110 and the second glass base 120 are When joined, the thickness (gap H) of the adhesive layer 5D between the first plane part 110A and the second plane part 120A is 2×ΔD (=30 μm). Note that here, the value of 2×ΔD can be appropriately determined depending on the viscosity of the adhesive 5 actually used.

Considering the strength of the round fiber array 100 after mounting, the strength of the adhesive 5 after solidification is weaker than the glass that is the material of the round fiber array 100, so the smaller the gap (2×ΔD), the better. preferable. According to the viscosity of the adhesive 5 currently used for manufacturing fiber arrays, the gap H (2×ΔP) can be narrowed to a minimum of about 5 μm.

FIG. 2B shows the pitch Y1 of the V-grooves 111, 111, . . . formed in the first flat portion 110A of the first glass base 110, and the depth D of the V-grooves. A plurality (five) of V-grooves 111, 111, . . . are formed in the axial direction of the first plane portion 110A, and the pitch Y1 of these V-grooves 111, 111, . . . is 250 μm.
In addition, the cross section of the V grooves 111, 111, ... (V grooves 121, 121, ...) is an equilateral triangle, and the depth D thereof is determined according to the diameter R (125 μm) of the optical fibers 1, 1, ... to be arranged. has been done.

FIG. 3 shows a method for determining the depth D of the V-groove 111 according to the diameter R (125 μm) of the optical fiber 1.
The V-groove 111 holds the optical fiber 1 in two straight lines q1 and q2 (indicated by points q1 and q2 in the cross-sectional view of FIG. 3A) extending in the axial direction.
Further, as shown in FIG. 3(B), when the second flat portion 120A on the second glass base material 120 side is overlapped, the optical fiber 1 is It is held by four straight lines q1 to q4 (indicated by points q1 to q4 in the cross-sectional view of FIG. 3(B)) extending in the axial direction.
The gap H between the first flat part 110A of the first glass base 110 and the second flat part 120A of the second glass base 120 is maintained at 2×ΔD (=30 μm) by sandwiching the optical fiber 1 therebetween. be done.
When the optical fibers 1, 1, ... are mounted on the round fiber array 100, the cores (P0, P0, ...) are arranged in a virtual plane S (Fig. 2(A) and the two-dot chain line in FIG. 3(A)).

The deepest parts of the V-groove 111 and the V-groove 121 are formed so that the depth from the virtual plane S (the two-dot chain line in FIGS. 2 and 3) is D1 in order to contain one optical fiber 1. (Figure 3(A)).
Since the first glass base 110 is ground to an extra depth of ΔD from the virtual plane S, the V-groove 111 itself has to be ground to a depth of D (=D1-ΔD) from the first plane part 110A. For example, the depth from the virtual plane S is D1. In this embodiment, the diameter of the optical fiber 1 is 125 μm and the gap H is 30 μm (Δh=15 μm), so the depth D of the V-groove 111 from the surface of the first flat portion 110A is 110 μm.

When the optical fibers 1, 1, ... are mounted on the round fiber array 100, as shown in FIG. It is held by being sandwiched between the grooves 121 and then fixed with the adhesive 5.
As shown in FIG. 3B, the optical fiber 1 is held at p1 to p4 in the V grooves 111 and 121, so if the cross section of the V grooves is an equilateral triangle, at least the V grooves 111, 121, 121 needs to be the depth Dmin (D1×3/4≈94 μm) (here, D1 is the same value as the diameter R of the optical fiber 1).
In other words, the gap H (ΔD×2) provided between the first planar portion 110A and the second planar portion 120A is such that the adhesive 5 can connect to the first planar portion 110A without forming bubbles due to capillary action. The value can be set from the minimum value (approximately 5 μm) to the maximum value (Hmax in FIG. 3: approximately 62.5 μm) that can be evenly spread and filled between the second flat portion 120A. Note that this gap H is preferably smaller.

4 and 5 are diagrams schematically showing a method of manufacturing the round fiber array 100.
FIG. 4 shows a long cylindrical base material 101 that has been ground to a predetermined depth ΔD (=15 μm) from a plane (double-dashed line in FIG. 2A) including the center line (axis P). The figure shows the steps up to forming a plurality of V grooves using a disk-shaped grindstone T1 using a semi-cylindrical base material 101A (the V grooves 111 and 121 are formed in the same process).
Note that, after the grinding process, the semi-cylindrical base material 101A is cut into predetermined lengths (for example, every 5 mm) to form a plurality of first glass substrates 110 and a plurality of second glass substrates 120. is produced. In addition, in FIG. 4(A), K1, K2, and K3 (dotted chain lines) indicate the cutting positions after the V groove is ground.
FIG. 4(B) is a diagram in which tapered portions (110B, 120B) are formed at cutting positions K1, K3 shown in FIG. 4(A) using a disc-shaped grindstone T2.
By forming these tapered parts 110B and 120B, when the first glass base 110 and the second glass base 120 are bonded together, a space 100Z is formed, and the optical fibers 1, 1, . . . are mounted. At this time, the boundary between the fiber core 1a and the fiber coating portion 1b can be covered with the adhesive 5 within this space 100Z (space 100Z in FIGS. 1 and 5(B)).
When the first flat part 110A of the first glass base 110 and the second flat part 120A of the second glass base 120 are fixed with the adhesive 5, the tapered parts 110B and 120B define the Since the adhesive 5 is also filled in the space 100Z due to capillary action, the optical fibers 1, 1, ... are fixed so that no stress is generated at the joint between the fiber core 1a and the fiber coating 1b (see Fig. 1).

The long semi-cylindrical base material 101A is first divided into two parts at the cutting position K in the center, and a flat part 110E for positioning is attached to the bottom of one of the two halves of the semi-cylindrical base material 101A (FIG. , FIG. 2) is formed.
By forming the flat portion 110E, when connecting the round fiber array 100 with a perfect circular cross section to a predetermined portion of a light wave circuit (not shown), the connection can be made with high precision without causing deviation in the circumferential direction. becomes possible.
The semi-cylindrical base material 101A that has been divided into two parts is cut to a desired length (for example, 5 mm) at cutting positions (K1, K3...), and one semi-cylindrical base material 101A (having a flat portion 110E) is cut into a desired length (for example, 5 mm). The other semi-cylindrical base material 101A is cut to a desired length (for example, 5 mm) to become the second glass base 120.

In the first glass base 110, five optical fibers 1, 1, . . . are arranged in five V grooves 111, 111, . The glass base portion 120 is covered with the second flat portion 120A facing downward (FIG. 5(A)).
At this time, the first flat part 110A of the first glass base 110 and the first flat part 110A of the first glass base 110 and The second glass base portion 120 is aligned with the second flat portion 120A (FIGS. 5A and 5B). When the optical fibers 1, 1, . . . are arranged, the gap H between the first planar portion 110A and the second planar portion 120A becomes 2×ΔD (=30 μm).

The end 110X of the first glass base 110 and the end of the second glass base 120 are located in the gap H (2×ΔD) between the first plane part 110A and the second plane part 120A which are overlapped with each other. By dropping the adhesive 5 onto the fiber core wires 1a, 1a, . . . protruding from the fiber core 120X, the adhesive 5 is filled by capillary action (FIG. 5(B)).
The adhesive 5 filled to a thickness H (30 μm = 2×ΔD) is solidified to form the adhesive layer 5D of the fiber array 100. At this time, the adhesive 5 further fills the space 100Y provided by the tapered portions 110B and 120B (FIG. 1).
After the adhesive 5 has solidified, the end 1210X of the first glass base 110 and the end 120X of the second glass base 120 are polished, so that the connecting surface 100X has a perfectly circular cross section and is flattened with high precision. The shaped fiber array 100 is completed (FIG. 1).

FIG. 6 shows the positions of the V-grooves 111 and 121 of the round fiber array 100 with a perfect circular cross section of the first embodiment, and the arrangement positions of the optical fibers 1, 1, ... mounted thereon on the connection surface 100X. It is a diagram.
The round fiber array 100 has a diameter of 2000 μm, and optical fibers 1, 1, . It is held by V grooves 121, 121, . . . and fixed with adhesive 5.
Furthermore, the five V-grooves 111, 111, . . . and the five V-grooves 121, 121, .

The five optical fibers 1, 1, ... mounted on the round fiber array 100 are arranged along a virtual plane S (double-dashed line in FIG. 6(B)) that includes the center line (axis) of the round fiber array 100. At this time, the optical fibers 1, 1, ... are arranged with the cores 1c, 1c, ... in a straight line on the virtual plane S at the connection surface 100X of the round fiber array 100, with a pitch Y1 (250 μm) and arranged with high precision (FIG. 6(B)).

Next, using FIG. 7, V grooves 111, 111 when a general optical fiber 1 with a perfect circular cross section and a polarization maintaining fiber 2 with a distorted cross section are mounted in a mixed manner in the round fiber array 100. , . . , the shapes of the V grooves 121, 121, . . are explained.
The polarization maintaining fiber 2 used here is a PANDA type fiber in which a circular region of a material softer than the cladding material is formed in a predetermined region of the cladding to exert a polarization maintaining function.

In such a PANDA type fiber 2, a soft material is embedded in the base material constituting the cladding, so when it is drawn into a thin wire, the cross section of the fiber becomes a perfect circle like a typical optical fiber (Fig. 7(A)), but is known to deform slightly and become an ellipse (right side of FIG. 7(A): the deformation is emphasized in this figure).
When the PANDA polarization-maintaining fibers 2, 2, ... are mounted as they are in the V-groove (left side of Figure 7 (A)) that has a shape suitable for optical fibers (125 μm in diameter) 1, 1, ..., the right side of Figure 7 (A) As shown, the position of the core 2c is lowered in height by Δh compared to the core 1c of the optical fiber 1 (coinciding with the virtual plane S).

In recent years, in the field of optical communications that requires high precision and high integration, optical loss caused by the error Δh in the height direction of the core 2c due to slight distortion occurring in this PANDA type fiber becomes a problem. This is because it is expected that the influence of optical loss will become greater as higher precision and higher integration are required.
Therefore, in the present invention, when mounting not only the general optical fiber 1 having a perfect circular cross section but also a PANDA type polarization maintaining fiber in a mixed manner in the round fiber array 100, a Two V-grooves (a first V-groove 111a and a second V-groove 111b) having different depths are formed in the V-grooves 111, 111, . . . corresponding to these two fibers.

Furthermore, two V-grooves (a third V-groove 121a and a fourth V-groove 121b) having different depths are formed on the second plane portion 120A side as well as on the first plane portion 110A side.
Note that the third V groove 121a formed in the second plane portion 120A is located at a position opposite to the first V groove 111a, and the fourth V groove 121b is located opposite to the second V groove 121b. It is located.

The depth D of the first V-groove 111a and the third V-groove 121a is determined according to the diameter R (=125 μm) of the general optical fiber 1 having a perfect circular cross section, as described above, and The depth D' of the V-groove 111b and the fourth V-groove 121b is determined by the difference Δh between the core position of the optical fiber 1 and the core position of the polarization-maintaining fiber.

Specifically, first, with the optical fiber 1 and the polarization-maintaining fiber 2 having a perfect circular cross section placed on a V-groove having an equilateral triangular cross section, the position of the core 1c of the optical fiber 1 and the position of the polarization maintaining fiber 2 are determined. The height difference (Δh) of the core 2c is detected, and the third V-groove 111b and the fourth V-groove 121b for the PANDA polarization maintaining fiber are formed to a predetermined depth D (115 μm) using the detected Δh. It is formed shallower by Δh.
In this way, by separately forming the V-groove (111a, 121a) for the general optical fiber 1, which has a perfect circular cross-section, and the V-groove (111b, 121b) for the polarization-maintaining fiber 2, the cross-section can be perfectly circular. Even if the optical fiber 1 of They can be arranged in a straight line on the top and arranged with high accuracy at a predetermined pitch Y1 (=250 μm) (FIG. 7(B)).

(Second embodiment)
Next, a second embodiment of the present application will be described using FIGS. 8 to 14.
FIG. 8 is a perspective view of a round fiber array 200 with a perfectly circular cross section according to the second embodiment.
The round fiber array 200 differs from the round fiber array 100 of the first embodiment described above in that the optical fibers 1, 1, . . . can be arranged with high precision (narrow pitch).
In the round fiber array 200 of this embodiment, the optical fibers 1, 1, ... are arranged in a straight line on the virtual plane S in a highly integrated (high density) manner with a pitch Y2 (127 μm) that is approximately the same as the diameter (125 μm) of the optical fibers. (Fig. 11, Fig. 12).

Similarly to the round fiber array 100 of the first embodiment, the round fiber array 200 of the second embodiment also includes a first glass base (first base) 210 that sandwiches the optical fibers 1, 1,... A cylindrical base 200A is constituted by the second glass base (second base) 220 and the adhesive layer 5D.
Nine V grooves (first fiber holding grooves) 211, 211, ... are formed along the axial direction in the first plane part (first plane part) 210A of the first glass base 210. ing. Further, in the second plane part of the second glass base 220, there are a plurality of (nine) V grooves (second fiber holding grooves) 221, 221, . . . facing the V grooves 211, 211, . is formed in the axial direction (FIG. 9(A)).

The first flat part 210A of the first glass base 210 and the second flat part 220A of the second glass base 220 are pasted together and fixed with adhesive 5, but at this time, the optical fibers 1, 1,... is held and fixed between the V-groove 211 and the V-groove 221.
The gap H between the first plane part 210A and the second plane part 220A, which occurs when the optical fibers 1, 1, . . . becomes.
Note that the first glass base 210 and second glass base 220 of this second embodiment are different from the first glass base 110 and second glass base 120 of the first embodiment described above, and the V groove 211. , 211, . . . , 221, 221, .

The gap H (=adhesive layer 5D) between the first flat part 210A of the first glass base 210 of the round fiber array 200 and the second glass base 220A of the second glass base 220 is In order to ensure the strength of 200, it is preferable that the hole be narrow.

FIG. 10 is a diagram showing a cross-sectional shape of a round fiber array 200 according to the second embodiment.
Of these, FIG. 10(A) shows the shapes of the V grooves 211, 211, . . . , V grooves 221, 221, . . . . shows an example (narrow pitch) in which optical fibers 1, 1, . . . are arranged in the highest concentration such that their fiber cores are in contact with each other.
FIG. 11 shows in detail the relationship between the shape of the V-groove and the optical fiber 1 when the optical fiber 1 (diameter 125 μm) having a perfect circular cross section is arranged at a narrow pitch (arranged so that the core wires touch each other).
As shown in FIG. 11(A), when a general optical fiber 1 with a perfect circular cross section is held and fixed by sandwiching it between upper and lower V grooves with an equilateral triangular cross section, the optical fiber 1 can be held in place by only the upper and lower V grooves. If the fibers 1, 1, ... are completely surrounded and crowded, the width of the V groove will be larger than the diameter R of the optical fiber 1 on the virtual plane S, so the fiber core wires will be in contact with the optical fibers 1, 1, ... They cannot be arranged at a narrow pitch (127 μm pitch).

If general optical fibers 1, 1, ... with a diameter R (=125 μm) and a perfect circular cross section are to be held and fixed with equilateral triangular V grooves 211 and 221 with their core wires touching each other, the V groove 211 , the depth Dx of the V-groove 221 needs to be the height of an equilateral triangle that touches the outer periphery of the optical fibers 1, 1, . . . as shown in FIG. 11(B).
Since the length of the base of this equilateral triangle is approximately the same as the radius R (=125 μm) of the optical fiber 1, the height Dx is approximately 108 μm. Theoretically, if the gap H between the first plane part 210A and the second plane part 220A is about 34 μm, the top of the convex part between the plane of the first plane part 210A and the V-grooves. The heights of match.
Actually, since the narrow pitch (Y2) is 127 μm, the length of the base of the triangle is 127 μm, so Dx is 110 μm, and if the gap H is 30 μm, the plane of the first flat portion 210A The heights of the apexes of the convex portions between the V grooves are substantially the same (vertex F in FIG. 12).
That is, if the gap H between the first plane part 210A and the second plane part 220A is 30 μm, and the depth Dx of the V-groove is 110 μm, the pitch of the optical fibers 1, 1, ... to be mounted is Y2 can be approximately the diameter of the optical fiber 1 (127 μm according to the narrow pitch standard) (FIG. 11(B)).

FIG. 12 shows nine V-grooves 211, 211, An example is shown in which the depth Dx of the nine V-grooves 221, 221, . Here, the first plane part 210A is composed of first adhesive parts 210A1, 210A1 provided at both ends (both sides in FIG. 12), and a first clamping part 210A2 sandwiched therebetween.
Further, the second flat part 220A also includes second adhesive parts 220A1, 220A1 provided at both ends (both sides in FIG. 12), and a second clamping part 220A2 sandwiched therebetween.
In FIG. 12, the top of the first clamping part 210A2 (the position of the apex F of the convex part formed by the V-groove 211 with the adjacent V-groove 211) is located on the surface of the first adhesive part 210A1, 210A1. Matches the position.
Further, the topmost part of the second holding part 220A2 (the position of the apex G of the convex part formed by the V-groove 221 with the adjacent V-groove 221) coincides with the position of the surface of the second adhesive part 220A1, 220A1. do.

Therefore, as shown in the figure, if the gap H between the first plane part 210A and the second plane part 220A is 30 μm, the V grooves 211, 211, . . . , the V grooves 221, 221, . They can be formed adjacent to each other on the surface of the first plane section 210A and the surface of the second plane section 220A.

FIG. 13 shows a V-groove (first V-groove) 211a, a V-groove (first V-groove) 211a, and a It shows a groove (second V groove) 211b, a V groove (third V groove) 221a, and a V groove (fourth V groove) 221b.
If the round fiber array 200 is to be equipped with a mixture of general optical fibers 1 with a perfect circular cross section and polarization maintaining fibers 2 with a distorted cross section, the first embodiment (FIG. 7) Similarly, the depths of the V-groove (second V-groove) 211b and the V-groove (fourth V-groove) 221b that hold the polarization-maintaining fiber 2 are determined from the depths of the V-grooves 211a and 221a for core 1c and core 2c. It is only necessary to make it shallower by the height difference Δh.

FIG. 14 shows an example in which the gap between the first plane part 210A and the second plane part 220A is narrower than 30 μm (for example, 10 μm).
As shown in FIG. 11(B), V grooves 211, 211, . ,... are formed so as to be in contact with each other, it is necessary to set the gap H between the first plane part 210A and the second plane part 220A to about 30 μm (in the case of a narrow pitch of 127 μm).

Here, if the gap between the first plane part 210A and the second plane part 220A is made narrower than 30 μm (for example, 10 μm), as shown in FIG. What is necessary is to make the shapes (left-right asymmetrical) of the V-grooves (both-end V-grooves) 211m, 211m located there different (left-right symmetrical) and the shapes (left-right symmetrical) of the V-grooves (intermediate V-grooves) 211n, 211n, . . . formed therebetween.

If the gap is 10 μm, the top of the first holding part 210A2 (positions F, F, ... in FIG. It must be made deeper than the surface of the adhesive portions 210A1 and 210A1.
Also, in the second plane part 220A, the top of the second clamping part 220A2 in the center (G, G, ... in FIG. It must be deeper than the position of.

When forming the intermediate V-groove 211n in this way, the apex of the convex portion formed by the adjacent V-groove (F, F, etc. in FIG. 14(A)) is placed at a position deeper than the first flat portion 210A. shall be.
Also, in the second flat part 220A, intermediate V grooves 221n, 221n, etc. formed between the V grooves (both end V grooves) 221m, 221m located at both ends of the second flat part 220A are adjacent to each other. The apexes of the convex portions (G, G, . . . in FIG. 14(A)) formed by and are made deeper than the second flat portion 220A.

By forming the intermediate V grooves 211n, . . . , 221n, . . . as described above, the optical fibers 1, 1, . By making the gap with 220A, that is, the adhesive layer 5D, about 10 μm, the ratio of adhesive 5 to glass in the round fiber array 200 can be lowered, and the strength of the fiber array 200 can be increased.

Note that in the second embodiment, an example is given in which optical fibers and polarization-maintaining fibers are mounted in the round fiber array 200 so as to be in contact with each other, so the V-grooves are also formed densely so that they are in contact with each other. However, as shown in FIG. 15(A), the optical fibers (125 μm) 1 are designed so that they are in contact with each other on the first plane portion 210A and the second plane portion 220A. Desired optical fibers 1, 1, . . . may be mounted by cutting and forming only necessary V-grooves (FIG. 15(B)). By actually thinning out and cutting the V-grooves designed to have a continuous pitch of 127, for example, if you thin out one pitch, the pitch will be 254 μm, and if you thin out two pitches, the pitch will be 381 μm. By forming V-grooves and arranging the optical fibers 1, 1, . . . in these V-grooves, the design can be repurposed to suitably provide a desired arrangement pattern.

In the first and second embodiments, the first and second bases are glass bases, but the present invention is applicable to bases made of other materials (for example, silicon bases, etc.). The same effect can be obtained by applying it to When a material that does not transmit light, such as silicone, is selected, a thermosetting adhesive or the like may be used as the adhesive.

Although the present invention is used for small round fiber arrays, it is also applicable to other fields where it is required to accurately arrange a capillary in a straight line at the center of a cylindrical member.

1 Optical fiber 1a Fiber core 1b Fiber coating 1c Core 2 Polarization maintaining fiber 2c Core 5 Adhesive 5D Adhesive layer 100 Round fiber array 100A Cylindrical base 110 First glass base (first base)
110A First plane part 111 V groove (first fiber holding groove)
120 Second glass base (second base)
120A Second plane part 121 V groove (second fiber holding groove)
121A V-groove at both ends 121B Intermediate V-groove 200 Round fiber array 200A Cylindrical base 210 First glass base 210A First flat part 211 V-groove (first fiber holding groove)
220 Second glass base 220A Second plane part 221 V groove (second fiber holding groove)
221A V-groove at both ends 221B Intermediate V-groove S Virtual plane

Claims (12)

It has a cylindrical base consisting of a semi-cylindrical first base, a semi-cylindrical second base, and an adhesive layer provided between the first base and the second base,
A plurality of first fiber holding grooves are formed in the axial direction in the first flat part formed in the axial direction of the first base,
A plurality of second fiber holding grooves facing the first fiber holding grooves are formed in a second flat part formed in the axial direction of the second base,
A plurality of optical fibers are arranged between the first fiber holding groove and the second fiber holding groove that face each other,
A fiber array characterized in that the adhesive layer is formed of an adhesive filled between the first plane part and the second plane part. The first base is formed into a semi-cylindrical shape by cutting a cylindrical base material with a perfect circular cross section parallel to a plane including the axis,
The second base is formed into a semi-cylindrical shape by cutting a cylindrical base material with a perfect circular cross section parallel to a plane including the axis,
The first base is further cut from a plane including the axis of the cylindrical base material to a depth of 1/2 of the adhesive layer to form the first plane part,
The second base is further shaved from a plane including the axis of the cylindrical base material to a depth of 1/2 of the adhesive layer to form the second plane part,
2. The fiber array according to claim 1, wherein the cylindrical base including the first base, the second base, and the adhesive layer has a cylindrical shape with a perfect circle in cross section. , 2. The adhesive layer has a thickness such that the adhesive permeates between the first plane part and the second plane part by capillary action. The fiber array according to item 2. The diameter of the optical fiber held in the first fiber holding groove and the second fiber holding groove is 125 μm, and the pitch of both the first fiber holding groove and the second fiber holding groove is 127 μm. The fiber array according to any one of claims 1 to 3, characterized in that: The first plane part includes two first adhesive parts provided at both ends and a first clamping part sandwiched between the first adhesive parts, and the first clamping part has the first adhesive part sandwiched between the first adhesive parts. A fiber holding groove is formed,
The second plane part includes two second adhesive parts provided at both ends and a second clamping part sandwiched between the second adhesive parts, and the second clamping part is provided with the second adhesive part. A fiber holding groove is formed,
The top of the first holding part is formed deeper than the surface of the first adhesive part,
5. The fiber array according to claim 1, wherein the top of the second holding part is formed deeper than the surface of the second adhesive part. 6. The fiber array according to claim 1, wherein the first fiber holding groove and the second fiber holding groove are V-shaped grooves having an equilateral triangular cross section. 7. The fiber array according to claim 6, wherein the depth of the V-groove is smaller than the diameter of the optical fiber to be mounted by half the thickness of the adhesive layer. A plurality of optical fibers are arranged in a straight line in the first holding part so that their core wires are in contact with each other,
8. The fiber array according to claim 6, wherein the depth of the V-groove is greater than at least 3/4 of the diameter of the optical fiber. The plurality of optical fibers are optical fibers with a perfect circular cross section and polarization maintaining fibers,
A first V groove and a second V groove having different depths are formed in the first plane part,
The second flat portion includes a third V groove having the same depth as the first V groove at a position facing the first V groove, and a third V groove at a position facing the second V groove. A fourth V groove having the same depth as the second V groove is formed,
The depths of the first V-groove and the third V-groove are determined according to the diameter of the optical fiber and the thickness of the adhesive layer,
The depths of the second V-groove and the fourth V-groove are determined by the core position when the optical fiber is placed in the V-groove with an equilateral triangular cross section and the core position when the polarization maintaining fiber is placed. 9. The fiber array according to claim 1, wherein the fiber array is determined based on a difference. cutting a cylindrical base material with a perfect circular cross section to a predetermined depth from a plane including the axis to form a semi-cylindrical base material;
forming a plurality of V grooves extending in the axial direction in the axial plane part of the semi-cylindrical base material;
cutting the semi-cylindrical base material at a plurality of locations to produce a plurality of first bases and a plurality of second bases;
arranging optical fibers along a plurality of V grooves in the axial plane portion of the semi-cylindrical base material serving as the first base;
A step of joining an axial plane part of the semi-cylindrical base material, which will become the second base part, to an axial plane part of the first base part, on which the optical fiber is arranged, so that their V grooves overlap. and,
Filling an adhesive into a gap created between the axial plane part of the semi-cylindrical base material that will become the first base and the axial plane part of the semi-cylindrical base material that will become the second base part. A method for manufacturing a fiber array, comprising the steps of: Two at both ends of the axial plane part of the semi-cylindrical base material which becomes the first base, and at both ends of the axial plane part of the semi-cylindrical base material which becomes the second base part. forming a V-groove;
forming a plurality of V grooves between the two V grooves,
In the step of forming the plurality of V grooves, the apex of the convex part formed between adjacent V grooves is formed lower than the first base and the second axial plane part. The fiber array manufacturing method according to claim 10. forming a V-groove by determining the depth based on the diameter of the optical fiber with a perfect circular cross section to be mounted;
arranging the optical fiber and the polarization-maintaining fiber in the V-groove and detecting a difference in their respective core positions;
The method for manufacturing a fiber array according to claim 10 or 11, further comprising the step of determining the depth of the V-groove in which the polarization maintaining fiber is placed based on the detected difference. .