JPH06214138A - Optical fiber array and optical fiber array equipped with collimator lens - Google Patents

Abstract

PURPOSE:To accurately and easily produce one-dimensional and two-dimensional optical fiber arrays, or an optical fiber array equipped with collimator lens with good working efficiency and at a low production cost. CONSTITUTION:A cylindrical ferrule 2 having high accuracy in an outer diameter is mounted on the end part of the optical fiber 1, and the ferrules 2 are aligned in one-dimensional so that the outer circumference of adjacent ferrules 2 may come into contact with each other in an axial direction, or the one- dimensional alignments are laminated so as to obtain a two-dimensional alignment. A bundle of aligned ferrules is surrounded by a ferrule aligning substrate(plate) 3 so that the outer circumference of the outside ferrules may come into contact with the substrate 3, and then, they are fixed with adhesive 4. The one-dimensional array, or the two-dimensional array is easily and accurately produced by use of the accurate ferrule 2 and the aligning substrate 3.

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 and a fiber optic array with a collimator lens used in a connector for connecting a large number of optical fibers at high density in the field of optical communication and the like.

[0002]

2. Description of the Related Art An optical fiber array that constitutes a connector includes a one-dimensional array in which a plurality of optical fibers are arranged on one plane due to its structure, and a two-dimensional array in which the one-dimensional array is laminated. One-dimensional arrays are generally formed on a Si substrate by photolithography and anisotropic etching.
A structure in which a groove is formed and an optical fiber is aligned on the V groove is widely used. On the other hand, in the two-dimensional array, as shown in FIG. 6, a large number of holes 52 are formed in the substrate 51 holding the optical fibers 50, and the optical fibers 5 are inserted in the holes 52.
A structure has been proposed in which the zero end is inserted.

[0003]

However, in the case of the one-dimensional array as described above, there is an advantage that the V groove on the Si substrate can be formed with high accuracy and at low cost by photolithography and anisotropic etching. A special aligning jig or the like is required for aligning the fibers in the V-grooves, and since a plurality of optical fibers are arranged in the smaller V-grooves, there is a problem that alignment work takes time and production efficiency is poor.

On the other hand, the above-mentioned two-dimensional array has two problems. One is that the hole in the holding substrate of the optical fiber is processed by a method such as photo-etching, so the fiber array on the side inserted into this hole can obtain relatively high accuracy, but the optical fiber is removed at the part away from the hole. Since the structure for holding with high accuracy is not provided, the parallelism between the optical fibers is poor, and it is difficult to maintain the orthogonality of the optical fiber 50 with respect to the surface of the fiber holding substrate 51 with high accuracy.
This appears as an angular deviation (θ) of the emitted light 54 with respect to the ideal optical axis 53 that is perpendicular to the fiber end face and serves as a reference, and causes a connection loss.

Another problem is workability in manufacturing an optical fiber array. That is, since the dimensional tolerance between the diameter of the optical fiber and the hole diameter is small, it is difficult to insert a large number of optical fibers at once. Therefore, it is necessary to insert the optical fibers one by one, but this takes a lot of time (if the diameter of the optical fiber holding hole is increased, the optical fibers are easily inserted, but the positional accuracy is lowered). The production efficiency is significantly reduced, and the production cost cannot be reduced.

As described above, in the conventional optical fiber array, since the structures of the one-dimensional array, the two-dimensional array and the one-dimensional array are different from each other, the constituent parts and the manufacturing method suitable for the respective structures are required. There was a problem that it was difficult to manufacture with high precision, high work efficiency and low manufacturing cost.
Furthermore, there are the following problems.

That is, when the two optical fiber arrays used for input and output are spatially separated, as in a free space switch, the two-dimensional optical fiber array is ideal light described above on the side that outputs light from the optical fiber. Axis 53 and outgoing light 5
The angles of 4 are matched with high accuracy (for example, 1 mrad or less), and at the same time, the light emitted from the optical fiber is converted into parallel light. On the other hand, the parallel light is converted into spot light even on the side where the light is input to the optical fiber. At the same time, it is required that the optical axis of the spot and the optical axis of the fiber coincide with each other. this is,
This is an important issue for achieving highly efficient coupling and reduction of crosstalk.

Here, matching the angle (θ) between the ideal optical axis 53 and the outgoing light 54 with high accuracy is a common problem with the higher accuracy of the optical fiber array, but the spot light and the parallel light are combined. A collimator is required for mutual conversion between the two. Up to now, a flat plate microlens array or rod lens has been used as a collimator combined with a two-dimensional optical fiber array.

The feature of the flat plate microlens array is that a different kind of atoms are diffused in a pattern region precisely formed at a predetermined position by photoetching on a glass plate having a thickness of about 1 mm to locally change the refractive index of the glass plate. Therefore, although a lens action is provided and a high array precision can be obtained in manufacturing, the optical fiber array and the flat plate microlens array are significantly different from each other in shape, so that it is difficult to perform high-precision alignment between them.

On the other hand, when a rod lens is used as a collimator lens array, there is a problem in forming an array of rod lenses, and conventionally, one rod lens is arranged corresponding to one optical fiber array. For this reason, it took a long time to form an array and the positioning accuracy was not sufficient.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to produce a one-dimensional or two-dimensional optical fiber array with high accuracy, easily and efficiently with low manufacturing cost. Another object of the present invention is to provide a structure of an optical fiber array that can be applied to an optical fiber array with a collimator lens.

[0012]

In order to achieve the above object, the present invention has the following constitution. That is, the optical fiber array of the present invention comprises an optical fiber, a cylindrical ferrule, and a flat plate (for example, a ceramic plate made of zirconia or the like) made of a hard material whose both surfaces are flat. The ferrules holding the ends of the optical fibers inside are one-dimensionally aligned so that the outer peripheries of adjacent ferrules are in contact with each other along the axial direction, or two-dimensionally by stacking the one-dimensionally aligned ferrules. Align. In the one-dimensional alignment, the outer circumference of all ferrules, in the two-dimensional alignment, the outer circumference of all ferrules located at the outermost circumference is configured to be in contact with the hard plate, and is held in the ferrule end face and this ferrule. The optical axis of the existing optical fiber is configured to intersect at an arbitrary angle. Further, the hard plate surrounding the ferrule bundle may be a composite substrate including a ceramic substrate having a flat surface in contact with the ferrule and a metal substrate bonded to the outside of the ceramic substrate.

In the case of an optical fiber array with a collimator lens, the ferrule is a fiber ferrule having an optical fiber held therein, and a rod lens ferrule having a rod lens held therein and having the same outer diameter as the fiber ferrule. The ferrule adhered to. Also in this case, the aligned state of all ferrules is regulated by a hard flat plate having good flatness. Further, the ferrule with the collimator lens may be a ferrule having an integral structure in which a fiber holding hole into which an end of an optical fiber is inserted and a rod lens holding hole into which a rod lens is inserted are formed. The hard plate may be a rectangular frame or a frame having another shape.

[0014]

In the above construction, the optical fibers are aligned by the ferrules processed with high accuracy, and the alignment state of these ferrules is regulated by the hard flat plate with good flatness, and the parallelism between the fibers and the fiber The alignment orthogonality and the like can be easily made highly accurate. Further, the work can be easily performed without using an alignment jig. Further, it can be easily manufactured regardless of the number of fiber arrays, and there is no limitation on the scale of the array. The pitch of the array can be easily changed by changing the outer diameter of the ferrule. Further, if the hard flat plate is a composite flat plate of which the outer side is metal, it can be mechanically fixed and held on the mating component, and an appropriate fixing and holding method can be selected according to the shape and material of the mating component. Furthermore, in the case of an optical fiber that requires a collimator lens, the optical fiber and rod lens can be held in the ferrule with high precision, and since this ferrule is aligned in the same manner as described above, the optical fiber array with a collimator lens can be easily and highly accurately arranged. Can be manufactured. Also fiber
If the ferrule for the rod lens is made into an integral structure, the ferrule manufacturing work will be simple and the precision and reliability of the ferrule can be improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to illustrated embodiments. FIG. 1 is a first embodiment of a two-dimensional optical fiber array of the present invention, FIG. 2 is a second embodiment in which the alignment substrate of FIG. 1 is composed of a composite substrate, and FIG. 3 is an optical fiber array with a collimator lens. FIG. 4 shows an embodiment of a ferrule in which two ferrules are connected, FIG. 4 shows an embodiment of a ferrule in which the ferrules of FIG. 3 are integrated, and FIG.

[Embodiment 1] As shown in FIG. 1, an optical fiber 1, a cylindrical ferrule 2, four ferrule aligned substrates (flat plates) 3, an adhesive 4 and a connector formed by a two-dimensional optical fiber array. Make up. The front end of the optical fiber 1 is inserted and held in the ferrule 2, and the ferrule 2 is aligned in contact with the adjacent ferrules in parallel, and the upper, lower, left, and right rows of the aligned ferrule bundle are respectively aligned. Contact with 3. The adhesive 4 is filled between the ferrules 2 and between the ferrules 2 and the alignment substrate 3, fixes the alignment substrate 3 in a frame shape, and fixes the alignment substrate 3 and the ferrule 2 so as not to be displaced in the axial direction.

The ferrule 2 is a member similar to a cylindrical plug used in a connector of a single-core optical fiber and having an accurate outer diameter. The ferrule 2 used here has an outer diameter of 2
It has a diameter of 50 ± 2 μm, an inner diameter of 127 ± 2 μm, a length of 10 mm and a parallelism of 3 μm or less with respect to the entire length, which is a member equivalent to the zirconia ferrule of the optical connector which has been widely used.

The size of the aligned substrate 3 is 3 mm in width and 1 m in thickness.
m, the length is 15 mm, the parallelism and the flatness are both 0.3 μm or less, and when the ferrule 3 holding the tip end of the optical fiber 1 inside is aligned on the alignment substrate 3, the ferrule 2 Even if the outer diameter variation of 2 is as large as 2 μm, + and − cancel each other well, so that the pitch accuracy of the optical fiber 1 falls within 1 μm or less. In addition, two adjacent alignment boards 3
The angle formed by is a transfer of a right angle of a triangular prism, and since there is an error of 1 mrad or less with respect to the right angle, a high degree of accuracy in the alignment orthogonality of the optical fibers 1 on the optical fiber array surface can be obtained.

On the other hand, the angular deviation between the optical axis of the optical fiber 1 and the emitted light is determined by the actual inclination angle θ of the optical fiber 1 with respect to the flat surface of the alignment substrate 3. Because the end face of the alignment substrate 3 and the end face of the optical fiber 1 are perpendicular to the flat face of the alignment substrate 3,
In addition, the polishing is performed so that they are flush with each other. Therefore, the maximum inclination angle θ in this embodiment is the ratio of the total variation of the inner and outer diameters of the ferrule 2 of 2 μm and the parallelism of the total length of 3 μm to the total length of 10 mm, that is, 7/10000.
(0.7 mrad), which is sufficient accuracy for practical use.

If the ferrule 2 and the alignment substrate 3 may be deformed at the contact portion between them, the above high precision cannot be achieved. Therefore, the aligned substrate 3 must be made of a hard material such as ceramics, and the same zirconia as the ferrule 2 was used in consideration of the compatibility with the ferrule. In this embodiment, it has been described that the end face of the ferrule 2 and the optical axis of the optical fiber 1 can be orthogonal to each other with an accuracy of the intersection angle of 1 mrad or less. However, in the actual polishing, the flat surface of the alignment substrate 3 is used as a reference. Since the intersection angle with the optical axis of 1 is defined, polishing can be performed with the same accuracy even for any intersection angle other than 90 °.

The ferrules 2 are simply arranged on the alignment substrate 3 without any special jig or device. Further, in FIG. 1, if the optical fiber array is arranged in only one stage, it becomes a one-dimensional optical fiber array as it is. At this time, it is clear from the configuration that the array accuracy of the optical fiber is not affected at all and can be manufactured by the same method as the two-dimensional array.

[Embodiment 2] FIG. 2 shows a two-dimensional fiber array which employs a composite substrate 5 in which a zirconia plate 7 is adhered to the inside of a metal plate 6 instead of the ceramic plate used in the aligned substrate 3 of Embodiment 1. is there. Even in such a configuration, the optical fiber array precision and the manufacturing method are the same as those in the first embodiment, but the optical fiber array mounting method is different.

That is, in the case of the first embodiment, since the outer part is made of ceramics, it is possible to avoid fixing and holding the two-dimensional optical fiber array to the mating part directly or through the third part by adhesion. Absent. In this case, when the coefficient of thermal expansion does not match that of the mating component or the bonding area is not sufficient, there remains a problem in reliability when mounting. On the other hand, if the outer part is made of metal, not only adhesion but also mechanical fixing and holding is possible, and a more appropriate fixing and holding method can be selected according to the shape and material of the other party, so mounting The reliability of can be greatly improved.

[Embodiment 3] FIG. 3 shows a ferrule used in an optical fiber array with a collimator lens, in which ferrules having optical fibers of different diameters and rod lenses held inside are bonded together at their end faces. It is a cross section of a ferrule of a structure. This ferrule is composed of an optical fiber 1, a rod lens 11, a fiber ferrule 12, and a rod lens ferrule 13.
Fiber ferrule 12 and rod lens ferrule 13
Are cylindrical members having different inner diameters but the same outer diameter. 1A is a core of the optical fiber 1.

In this structure, the ferrule 12 holding the optical fiber 1 inside and the ferrule 13 holding the rod lens 11 are separately manufactured, and then the ferrules 12 and 13 are placed on a flat V surface plate. The end faces of the both are integrated with the optical adhesive 14 based on the outer diameter of. After that, since the ferrules 12 and 13 are integrally formed into a uniform cylindrical shape, a two-dimensional array with a collimator lens in which rod lenses are arrayed can be easily formed by the same method as in the first and second embodiments. it can.

With this configuration, if there is a positional deviation (optical axis deviation d) between the centers of both the optical fiber 1 and the rod lens 11, an angle deviation θ (= πd / 2L) is generated. This angle deviation θ is
Since it causes coupling loss and crosstalk as in the first embodiment, it should be minimized. Since the optical axis deviation d in this case is matched on the basis of the outer diameter of the fiber ferrule 12 and the connector ferrule 13, it is caused by the inner diameter variation of 2 μm which depends on the outer diameter variation using the ferrule processing accuracy of the first embodiment. The maximum d is 6 μm. Here, if the length of the rod lens is L = 8 mm, the angle deviation θ is 1.1 mrad.
This value indicates that the position of the light shifts by 0.11 mm when the light propagates in the space of 10 cm.

Since the characteristics of the rod lens as a lens change depending on its length, the length of the rod lens used here should be adjusted in advance to the length (equal to the focal length) to be left finally. In addition, the end surface of the optical fiber that comes into contact with the end surface of the rod lens must be processed in advance so that it is perpendicular to the optical axis. Since all of these processes can be realized by the conventional polishing technique, there is no technical problem.

[Embodiment 4] In order to further simplify the manufacturing method of Embodiment 3, FIG. 4 is a cross-sectional structure of a ferrule having different diameters, in which holes having different inner diameters are machined at both ends, and an optical fiber 1 and a rod lens 11 are shown. And a ferrule 15 having an integral structure.
The ferrule 15 has a fiber holding hole 16 into which the end of the optical fiber is inserted and a rod lens holding hole 17 into which the rod lens is inserted.

Since the hole diameters at both ends of the ferrule are different, the manufacturing process is more complicated than the ferrules described so far, but the bonding process between the ferrules of the third embodiment can be omitted, so the manufacturing process is simpler. . Generally, the bonding process has a problem that it takes time manually and the accuracy and reliability are likely to be deteriorated. However, a different diameter ferrule has a great effect of alleviating this problem. Note that the length adjustment of the rod lens and the formation of the vertical surface of the end face of the optical fiber must be processed in advance as in the case of the third embodiment, but the optical axis deviation can be obtained with accuracy equal to or higher than that of the third embodiment.

The arrangement of the ferrule and the shape of the aligned substrate frame are not limited to those shown in FIGS. 1 and 2, and various modes can be adopted as shown in FIG.

[0031]

As described above, according to the present invention, the ferrule is attached to the end of the optical fiber, the ferrules are aligned in contact with each other, and the ferrule bundle is regulated by the hard flat plate having good flatness. It has the following effects. (1) Both one-dimensional and two-dimensional fiber arrays can be manufactured with high precision. (2) It can be easily manufactured, work efficiency is greatly improved, and manufacturing costs can be reduced. (3) There is no limit to the size of the fiber array, and the pitch of the fiber array can be easily changed by changing the outer diameter of the ferrule, and it can be used with any connector. (4) A fiber array that requires a collimator lens can be easily manufactured with high precision.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional perspective view showing an embodiment of a two-dimensional optical fiber array of the present invention.

2 is a partial cross-sectional perspective view showing an embodiment in which the aligned substrate of FIG. 1 is a composite substrate.

FIG. 3 shows a ferrule in which two ferrules are connected in the optical fiber array with a collimator lens according to the present invention, (a) is a transverse sectional view, and (b) is a longitudinal sectional view.

FIG. 4 is a vertical cross-sectional view showing an example in which the ferrule of FIG. 3 has an integrated structure.

FIG. 5 is a cross-sectional view showing a modified example in which the arrangement of ferrules and the shape of the aligned substrate frame are different.

FIG. 6 is a perspective view showing a conventional two-dimensional optical fiber array.

[Explanation of symbols]

 1 Optical Fiber 2 Ferrule 3 Ferrule Aligned Substrate 4 Adhesive 5 Composite Substrate 6 Metal Plate 7 Zirconia Plate 11 Rod Lens 12 Fiber Ferrule 13 Rod Lens Ferrule 14 Optical Adhesive 15 Ferrule 16 Fiber Holding Hole 17 Rod Lens Holding Hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Noguchi 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Kazuo Kimura 1-chome, Uchisaiwaicho, Chiyoda-ku, Tokyo No. 1-6 Nippon Telegraph and Telephone Corporation

Claims (4)

[Claims] 1. An optical fiber, a cylindrical ferrule,
The two ferrules are made of a flat plate of a hard material having flat both sides, and the ferrules holding the end portions of the optical fibers inside are aligned one-dimensionally so that the outer circumferences of the ferrules adjacent to each other are in contact along the axial direction, or The ferrules that were originally aligned are stacked to form a two-dimensional alignment.In the one-dimensional alignment, the outer perimeters of all ferrules, in the two-dimensional alignment, the outer perimeters of all ferrules located at the outermost perimeter are in contact with the hard plate. An optical fiber array characterized in that the ferrule end face and the optical axis of the optical fiber held in the ferrule intersect at an arbitrary angle. 2. The hard plate surrounding the ferrule bundle according to claim 1, wherein the hard plate is a composite substrate composed of a ceramic plate having a flat surface in contact with the ferrule and a metal plate bonded to the outside of the ceramic plate. An optical fiber array. 3. The fiber ferrule according to claim 1 or 2, wherein the ferrule integrally holds an optical fiber therein, and a rod lens ferrule having an outer diameter same as that of the fiber ferrule holding a rod lens therein. An optical fiber array with a collimator lens, which is a bonded ferrule. 4. The ferrule according to claim 1, wherein the ferrule has a fiber holding hole into which an end of an optical fiber is inserted and a rod lens holding hole into which a rod lens is inserted. An optical fiber array with a collimator lens, which is a ferrule.