JP2002277689A - Optical fiber array and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber array by which a high arranging accuracy of optical fibers can be obtained and also to provide a manufacturing method of such optical fiber array. SOLUTION: One or more pairs of substrates 5a, 5b are disposed between a pair of holding parts 5c arranged to face each other. In the pair of substrates 5a, 5b, a plurality of grooves 6 are formed with a space apart only on each oppositely facing main surface. An optical fiber 7 is sandwiched between the groove 6 formed on the substrate 5a and the one 6 on the substrate 5b. A positioning member 8 is sandwiched between a substrate-side positioning groove 6a which is formed on the each of upper and lower ends of the pair of substrates 5a, 5b, and the holding part-side positioning groove 6b which is formed on the main surface of each of the pair of holding parts 5c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical fiber array, and more particularly, to an optical fiber array in which optical fibers are arranged in a matrix.

[0002]

2. Description of the Related Art A conventional optical fiber array will be described. For example, an optical fiber array in which optical fibers are two-dimensionally arranged is used as one of components constituting an optical switch. As shown in FIG. 25, in the optical fiber array, a plurality of grooves 106 extending in one direction are formed on one and the other main surfaces of the substrate 105a at intervals. Similarly, a plurality of grooves 106 extending in one direction are formed at intervals on both main surfaces of the substrate 105b disposed to face the substrate 105a.

An optical fiber 107 is sandwiched between a groove 106 formed on one main surface of the substrate 105a and a groove 106 formed on one main surface of the substrate 105b. The optical fiber 107 is sandwiched between the groove 106 formed on the other main surface of the substrate 105b and the groove 106 formed on the other main surface of the other substrate 105c.

As described above, in the conventional optical fiber array,
The optical fibers were sandwiched between the grooves formed on both main surfaces of each substrate 105a and the like.

[0005]

However, the above-mentioned optical fiber array has the following problems. The groove 106 formed on the main surface of each substrate 105a or the like is formed by etching the substrate 105a or the like by using a resist pattern formed on the main surface by predetermined photolithography as a mask.

The grooves 106 formed on one main surface and the grooves 106
Accuracy depends on the accuracy of the photomask in photolithography. As shown in FIG. 25, at present, the interval Px between the optical fibers in the horizontal direction varies by about ± 0.5 μm. However, the groove formed on one main surface and the groove formed on the other main surface of one substrate are formed in separate steps. Therefore, in a state where grooves are formed on both main surfaces, there is generally a variation ΔD of about several μm in the horizontal direction between the groove formed on one main surface and the groove formed on the other main surface.

Further, as shown in FIG. 25, each optical fiber 107 is sandwiched between each substrate 105a and the like. Therefore, the distance Py between the optical fibers in the vertical direction depends on the thickness of the substrate 105a and the like. Generally, the thickness of the substrate 105a or the like has a variation of several tens of μm.

Thus, each groove 1 formed on one main surface is
06, a horizontal variation ΔD (about several μm) between the groove formed on one main surface and the groove formed on the other main surface, as compared with the variation of the interval Px of about 06 (about ± 0.5 μm). The variation in the thickness of the substrate (several tens of μm) is large.

As a result, the arrangement accuracy of the optical fibers in the entire optical fiber array varies, making it difficult to align the optical axis with other optical devices with high accuracy.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and one object of the present invention is to provide an optical fiber array capable of obtaining a high precision of arrangement of optical fibers.
Another object is to provide a method for manufacturing such an optical fiber array.

[0011]

An optical fiber array according to one aspect of the present invention includes a substrate-to-array and a substrate-to-array sandwiching means. The substrate-to-array is
Only between a pair of substrates, a plurality of substrate pairs that hold a plurality of optical fibers arranged in parallel with each other at intervals, are substantially parallel to each other at intervals, and the held optical fibers are They are arranged so as to be substantially parallel to each other.
The substrate-to-array holding means sandwiches and holds the substrate-to-array from a pair of substrate holding members facing each other from both sides in the arrangement direction of the plurality of optical fibers.

According to this configuration, the plurality of optical fibers are
They are arranged only between a pair of opposing substrates. As a result, the arrangement accuracy of the optical fiber array is smaller than that in the case where a plurality of optical fibers are arranged between one pair of substrates and another pair of substrates as in a conventional optical fiber array. This eliminates variations in arranging a plurality of optical fibers on both main surfaces of a pair of substrates facing each other, and substantially eliminates variations in arranging optical fibers only on one main surface. become. As a result, the arrangement accuracy of the optical fibers in the arrangement direction of the plurality of optical fibers is greatly improved, and the optical axis with another optical device can be adjusted with high accuracy.

Preferably, a positioning unit is provided for positioning the pair of substrate holding members and the pair of substrates.

In this case, the precision of the arrangement of the optical fibers in the direction in which the pair of substrates is arranged is greatly improved, and the optical axis can be adjusted with another optical device with higher precision.

[0015] Such a positioning portion includes a holding portion side positioning groove provided in each of the pair of substrate holding members, and a substrate provided in the substrate pair array so as to face the holding portion side positioning groove. It is preferable to include a side positioning groove and a held portion that is held and positioned between the holding portion side positioning groove and the substrate side positioning groove.

In this case, the sandwiched portion is sandwiched between the holding portion side positioning groove and the substrate side positioning groove, so that the positioning of the substrate pair array and the pair of substrate holding members can be easily performed. .

More specifically, the cross-sectional shape of the held portion is substantially circular, and the cross-sectional shape of the holding portion-side positioning groove and the substrate-side positioning groove is substantially V-shaped, so that positioning is easily performed. be able to.

Preferably, each end face of the plurality of optical fibers is polished obliquely in a direction intersecting the optical axis of the optical fiber.

In this case, the efficiency of coupling the light reflected at the end face of the optical fiber to the optical fiber is reduced, and the return loss can be increased.

Preferably, a lens is provided on each end face of the plurality of optical fibers.

In this case, the spread angle of the light emitted from the optical fiber is suppressed, so that the optical fiber can have a collimating effect.

[0022] More preferably, the material of the substrates forming the substrate-to-array includes glass. In this case, the material of the substrate pair and the material of the optical fiber are substantially the same, and the difference in thermal stress caused by the difference in the material when the ambient temperature fluctuates is substantially eliminated. The reliability of the array accuracy is improved.

A method of manufacturing an optical fiber array according to another aspect of the present invention includes the following steps. A grooved substrate having a plurality of grooves arranged substantially in parallel with each other at intervals is formed only on one main surface of each of the plurality of substrates. On each of a predetermined number of the plurality of substrates, the same number of other substrates as the predetermined number of the plurality of substrates are opposed to each other such that the corresponding grooves face each other, and light is supplied between the mutually facing grooves. A plurality of substrate pairs are formed to hold the optical fiber while receiving the fiber. A substrate pair array is formed by arranging a plurality of substrate pairs so as to be substantially parallel to each other at an interval and to hold the sandwiched optical fibers substantially parallel to each other. The substrate pair array is sandwiched and held by a pair of substrate holding members facing each other from both sides in the arrangement direction of the plurality of grooves.

According to this manufacturing method, the grooves for receiving the optical fibers are formed only on one main surface of the substrate so as to be arranged substantially parallel to each other with an interval therebetween. Compared to the case where grooves are formed on both main surfaces of a substrate, the alignment accuracy of the optical fibers is substantially the same as that of forming grooves on both main surfaces of the substrate, eliminating variations in forming the grooves on both main surfaces of the substrate. Only when forming a groove on the substrate. As a result, the arrangement accuracy of the optical fibers in the direction in which the optical fibers are arranged is greatly improved.

Preferably, the method further includes a step of forming a positioning portion for positioning the substrate pair array and the pair of substrate holding members. In the substrate pair array holding step, one step is performed by the positioning portion.
A pair of substrate holding members are provided.

In this case, the positioning unit greatly improves the arrangement accuracy of the optical fibers in the arrangement direction of the substrate-to-array.

The step of forming such a positioning portion includes:
Forming a holding portion side positioning groove in each of the pair of substrate holding members, and forming a substrate side positioning groove in the substrate pair array so as to face the holding portion side positioning groove;
And a step of preparing a held portion to be positioned by being sandwiched between the holding portion side positioning groove and the substrate side positioning groove.

In this case, by sandwiching the held portion between the holding portion side positioning groove and the substrate side positioning groove, the positioning between the substrate pair array and the pair of substrate holding members can be easily performed. .

More preferably, the step of forming the grooved substrate includes the step of forming a pair of substrate-to-array holding members having holding portion side positioning grooves.

In this case, a substrate for forming a substrate pair and a pair of substrate pair array holding members can be formed simultaneously, and the number of steps can be reduced.

Preferably, in the step of forming the grooved substrate, a plurality of grooves are formed in one substrate, and one substrate is divided along at least one of the grooves into a substrate pair. The step of forming a substrate-side positioning groove includes a step of forming one substrate and another substrate, and the step of forming a substrate-side positioning groove includes, when forming a substrate pair, a part of one groove remaining in one substrate and remaining in another substrate. And a step formed by facing a part of the other groove.

In this case, the grooves are formed at the same time as forming the substrate pair without providing a separate step for forming the substrate-side positioning groove.

Preferably, in the step of forming a plurality of substrate pairs, a jig having a predetermined surface with which the ends of the optical fibers come into contact is used for aligning the ends of the sandwiched optical fibers.

In this case, the positions of the ends of the optical fibers can be easily aligned. Preferably, in the substrate-to-array holding step, a jig for arranging the substrate-to-array in the pair of substrate holding members from the arrangement direction of the plurality of grooves is used.

In this case, a plurality of substrate pairs can be easily arranged in a predetermined positional relationship with respect to a pair of substrate pair holding members.

[0036]

Embodiment 1 An optical fiber array according to Embodiment 1 of the present invention will be described.

An optical fiber array is used as one of the components of an optical switch. First, such an optical switch will be described. As shown in FIG. 1, the optical switch comprises:
Input side optical fiber array 1a, input side lens array 2
a, input-side mirror array 3a, output-side mirror array 3
b, an output side lens array 2b and an output side optical fiber array 1b.

In the input fiber array 1a, M optical fibers are arranged. M lenses are arranged in the input-side lens array 2a. M mirrors are arranged in the input-side mirror array 3a. And
N mirrors are arranged in the output side mirror array 3b. N lenses are arranged in the output side lens array 2b. N optical fibers are arranged in the output side fiber array 1b.

In the input-side fiber array 1a, the input-side lens array 2a, and the input-side mirror array 3a, optical fibers, lenses, and mirrors are arranged in a matrix of, for example, a rows and b columns. In the output-side mirror array 3b, the output-side lens array 2b, and the output-side fiber array 1b, mirrors, lenses, and optical fibers are arranged in a matrix of, for example, c rows and d columns.

In many optical switches, the number (or number) M of the input side and the number (or number) N of the output side are set to be equal, but may be different.

Next, the operation of such an optical switch will be described. For example, the light emitted from the input-side optical fiber in the p-th row and q-th column (1 <p <a, 1 <q <b) in the input-side optical fiber array 1a is input to the input-side lens array 2a.
Through the input side lens in the p-th row and the q-th column, and reaches the input-side mirror in the p-th row and the q-th column in the input-side mirror array 3a.

Here, the mirror array 3a is, for example,
It is manufactured by MEMS (Micro Electro Mechanical Systems) technology, and the angle of each mirror can be controlled by applying forces such as electrostatic force and electromagnetic force. Thereby, the angle of the input-side mirror array 3a can be changed, the path of the reflected light reflected by the mirror is deflected, and the reflected light can reach any of the mirrors of the output-side mirror array 3b. .

For example, when the reflected light reaches the output-side mirror of the r-th row and s-th column (1 <r <c, 1 <s <d) of the output-side mirror array 3b, the reflected light reflected by the mirror Is transmitted through the output-side lens in the r-th row and s-th column in the output-side lens array 2b, reaches the output-side optical fiber in the r-th row and s-th column in the output-side optical fiber array 3b,
Light is output to the outside of the optical switch.

As described above, in the optical switch, the function as a switch is achieved by independently controlling the angles of the mirrors of the input-side mirror array 3a and the output-side mirror array 3b to switch the optical path.

As described above, in the optical switch, the optical fibers, lenses, and mirrors are respectively arranged in a matrix. Therefore, in order to reliably reflect the light sent from each input-side optical fiber array and send it back to the output-side optical fiber array, each optical fiber
High positional accuracy is required for each lens and each mirror.

Next, an optical fiber array used in such an optical switch will be specifically described.

As shown in FIG. 2, the optical fiber array is
A pair of substrates 5a, 5b sandwiching the optical fiber 7 between a pair of holding parts 5c arranged to face each other.
Are provided substantially in parallel at intervals.

In the pair of substrates 5a and 5b, a plurality of grooves 6 arranged substantially in parallel with each other at intervals are formed only on the opposing main surfaces. The optical fiber 7 is sandwiched between the groove 6 formed on the substrate 5a and the groove 6 formed on the substrate 5b.

On the main surfaces of the pair of holding parts 5c, a plurality of holding part side positioning grooves 6b are formed at intervals. Substrate-side positioning grooves 6a facing the holding-portion-side positioning grooves 6b are formed in the plurality of pairs of substrates 5a and 5b, respectively. The positioning member 8 is sandwiched between the substrate-side positioning groove 6a and the holding-part-side positioning groove 6b.

As will be described later, the substrate-side positioning grooves 6a formed in the pair of substrates 5a and 5b divide one substrate into at least two along the inside of one V-shaped groove 6, for example. Then, the slopes (tapered portions) of the grooves remaining on one substrate and the slopes (tapered portions) of the grooves left on the other substrate are formed to face each other.

As shown in FIG. 3, a pair of substrates 5a, 5b
The optical fiber 7 sandwiched between the clad 7a and the core 7
b. Typical diameter D1 of optical fiber 7
Is about 125 μm. The diameter D2 of the core 7b is
It is about 9 to 10 μm for a single mode fiber and about 50 μm for a multimode fiber.

As shown in FIG. 4, it is desirable that the holding portion side positioning groove 6 formed in the holding portion 5c has a substantially V-shaped cross section. Usually, for example, a silicon substrate is used as the holding portion 5c including the substrates 5a and 5b. The holding portion side positioning groove 6b is formed by etching the silicon substrate. At this time, since the etching proceeds along the crystal orientation of silicon, the apex angle of the V-shaped holding portion side positioning groove 6b becomes a predetermined angle.

Therefore, the variation in the width of each holding portion side positioning groove 6b is sufficiently suppressed to form the holding portion side positioning groove 6b having a constant depth, and the outer diameter dimensional accuracy is formed in each holding portion side positioning groove 6b. By arranging the high positioning member 8, the height of the center of the positioning member 8 can be adjusted with high accuracy.

The V-shaped cross section of the holding part positioning groove 6b is desirable. However, if the positioning member 8 can contact two slopes of the holding part positioning groove 6b, for example, FIG. A groove 9 having a bottom surface as shown in FIG.

However, in the case of the groove 10 shown in FIG. 6, since the bottom portion of the groove 10 is large, the positioning member 8
Is in contact with the bottom surface and no longer in contact with one of the slopes, and positioning cannot be performed. Controlling the depth from the surface of the substrate to the bottom of the groove is more difficult than controlling the width of the groove. Therefore, as the cross-sectional shape of the holding portion side positioning groove 6b, the substantially V-shaped one shown in FIG. 4 is most desirable.

The positioning member 8 provided in the holding portion side positioning groove 6b is required to have high outer diameter dimensional accuracy as described above. As such a positioning member 8, it is desirable to use a member processed into a substantially columnar shape such as a rod made of glass or ceramics. For example, a ferrule or the like used for an optical fiber connector is manufactured with an outer diameter tolerance of about ± 0.5 μm, and is applicable to the positioning member 8. Further, the optical fiber itself (dummy) may be applied.

In the above-described optical fiber array, each optical fiber 7 is disposed between a pair of substrates 5a and 5b, and is sandwiched by grooves 6 formed on only one of the main surfaces of the substrates 5a and 5b facing each other. Have been. Substrates 5a, 5b
No groove is formed in each of the other major surfaces that are not opposed to each other. That is, no optical fiber is provided between the pair of substrates 5a and 5b and the other pair of substrates 5a and 5b.

As a result, variations in the arrangement of a plurality of optical fibers on both main surfaces of the substrate as seen in a conventional optical fiber array are eliminated, and the arrangement accuracy of the optical fibers is substantially eliminated. The only difference is when the optical fibers are arranged only on one main surface. That is,
Substantially, only a process variation when forming a groove in one main surface of the substrate is obtained. As a result, the arrangement accuracy of the optical fibers in the arrangement direction of the plurality of optical fibers is greatly improved.

Generally, the accuracy of the width of the groove formed on the main surface of the substrate and the arrangement dimension of the groove is about ± 0.5 μm or less.
Therefore, for example, n optical fibers 7 are provided,
Assuming that the distance between the optical fibers is D, the variation in the distance between both ends of the optical fiber is (n-1) D ± 0.5 μm.

Each of the plurality of substrates 5a, 5b disposed between the pair of holding portions 5c is provided with a substrate-side positioning groove 6a provided in the pair of substrates 5a, 5b and the holding portion. Positioning is performed by sandwiching the positioning member 8 between the holding member side positioning groove 6b and the holding portion-side positioning groove 6b formed in 5c.

As a result, the pair of substrates 5a, 5b
The arrangement accuracy of the optical fibers in the direction in which are substantially parallel to each other is substantially only a process variation when forming a groove on one main surface of the pair of holding portions 5c.

Therefore, for example, n pairs of substrates 5a, 5
b, a pair of substrates 5 located at both ends
The variation in the interval between a and 5b is (n-1) · D ± 0.5
μm.

As described above, in the present optical fiber array, the optical fibers are arranged in two directions, that is, the arrangement direction of the optical fibers on the pair of substrates 5a and 5b and the direction in which the plural pairs of substrates 5a and 5b are arranged. And the optical axis of the optical switch can be easily aligned with other optical devices.

Embodiment 2 Next, a method of manufacturing the above-described optical fiber array as Embodiment 2 will be described.

First, as shown in FIG. 7, one surface of a substrate such as a glass substrate or a silicon substrate is subjected to predetermined photolithography and etching, so that a plurality of grooves 6, 6a, 6b is formed. Next, by dividing the substrate along the inside of a specific groove 6a (position 11) of the plurality of formed grooves, the substrates 5a and 5b for holding the optical fiber and the substrates 5a and 5b are held. Forming a pair of holding portions 5c.

Next, as shown in FIG. 8, one of the substrates 5a and 5b is placed so as to abut a predetermined abutting portion (arrow) of the jig 12a with the surface on which the groove is formed facing upward. Next, as shown in FIG. 9, the optical fiber 7 is received in a groove formed in one of the substrates 5a and 5b (temporary placement).

Then, an adhesive 13 is applied as shown in FIG. As an adhesive, sufficient bonding strength is obtained,
Further, an epoxy resin adhesive containing no filler is preferable. Generally, the filler has a size on the order of several tens to several hundreds of μm, so that when the filler enters between the groove and the optical fiber, the optical axis of the optical fiber is shifted.

Next, as shown in FIG. 11, with the optical fiber 7 received in the groove, the other substrate 5a, 5b is placed on the other substrate 5a, 5b with the grooved surface facing downward. And put the optical fiber 7 therebetween. Thereby, the optical fiber 7 is sandwiched by the grooves formed on the substrates 5a and 5b. Then, before the adhesive is cured, one substrate and the other substrate are connected to each other in a state where the end of the optical fiber 7 is abutted against the jig 12a (arrow), for example, with a clip or a screw (neither shown) ) To fix mechanically. In the fixed state, the substrates 5a and 5b together with the jig 12a are placed in a thermostat and subjected to a predetermined heat treatment to cure the adhesive.

Thus, as shown in FIG.
A one-dimensional optical fiber array 21 sandwiched between the pair of substrates 5a and 5b is formed.

When the one-dimensional fiber array 21 is formed, the positions of the end faces of the optical fibers 7 are aligned by the jig 12a. However, there is no such jig and the positions of the end faces of the optical fibers 7 are not aligned. 13 and FIG.
As shown in FIG. 4, the ends of the optical fibers 7 held between the pair of substrates 5a and 5b may be aligned by polishing to the position 14.

Further, as shown in FIG.
When the end of the optical fiber 7 is polished to the position 15, as shown in FIGS. 16 (a) and (b), the end face of the optical fiber 7 may be formed so as not to be orthogonal to the optical axis but to intersect obliquely. Good.
The advantage of forming an end face obliquely intersecting the optical axis as the end face of the optical fiber will be described later.

Next, as shown in FIG. 17, one holding portion 5c is placed so as to abut against a predetermined abutting portion of the jig 12b with the grooved surface facing upward (arrow).
Next, as shown in FIG. 18, the rod 8 having high external dimension accuracy is placed in the groove of the holding portion 5c, and the rod 8 is fixed by a temporary fixing member 16 such as a tape. At this time, 1
It is desirable to provide the temporary fixing member 16 avoiding the portion where the two-dimensional fiber array is arranged.

Next, as shown in FIG. 19, an adhesive is applied around the groove of the holding portion 5c and around the rod 8, and the one-dimensional optical fiber array 21 is mounted. At this time, the rod 8 is arranged so as to be received in the substrate-side positioning groove 6a formed at one end of the one-dimensional optical fiber array 21 shown in FIG. Similarly, as shown in FIG. 20, a plurality of one-dimensional optical fibers 21 are arranged substantially in parallel.

Then, an adhesive is applied to the other holding portion 5c to which the rod 8 has been temporarily fixed in advance in the same manner as the one holding portion 5c, and the other holding portion 5c is placed on the one-dimensional optical fiber array 21. It is placed so as to face one holding part 5c. At this time, the substrate-side positioning groove 6 formed at the other end of each one-dimensional optical fiber array 21 is formed.
a so that the rod 8 can be received.

Next, the position of each one-dimensional optical fiber array 21 is adjusted such that the end of the optical fiber 7 of each one-dimensional optical fiber array 21 contacts the abutting portion of the jig 12b. Thereafter, the plurality of one-dimensional optical fiber arrays 21 and the holding portion 5c are fixed together with the jig 12b. At this time, as shown in FIG. 20, a jig 1 for arranging the one-dimensional optical fiber array 21 substantially vertically to the holding portion 5c.
2c, the substrates 5a and 5 of the one-dimensional optical fiber array 21
It is fixed with the screw 17 in a state where it is in contact with the portion b.

Thus, a plurality of one-dimensional optical fiber arrays 21 are provided between one holding portion 5c and the other holding portion 5c.
Are arranged to form a two-dimensional optical fiber array.

Thereafter, it is put in a thermostat together with the jigs 12b and 12c and heated at a predetermined temperature to cure the adhesive.
After the adhesive is cured, the jigs 12b and 12c are removed to obtain a two-dimensional optical fiber array.

In the above-described method for manufacturing an optical fiber array, each optical fiber 7 is sandwiched by the grooves 6 formed only on one main surface of the pair of substrates 5a and 5b facing each other. No groove is formed on the other main surfaces of the other pair of substrates 5a and 5b which are not opposed to each other, and the pair of substrates 5a and 5b and the other pair of substrates 5a and 5b are not formed.
No optical fiber is provided between them.

As a result, with respect to the arrangement accuracy of the optical fiber array, variations in forming grooves on both main surfaces of the substrate as seen in a conventional optical fiber array are eliminated, and substantially one substrate is eliminated. The only difference is that the grooves are formed only on the main surface.

Further, a plurality of one-pieces are provided for a pair of holding parts by the positioning groove on the substrate side, the positioning groove on the holding part side and the rod.
Since each of the two-dimensional optical fiber arrays is positioned and arranged, the arrangement accuracy of the optical fiber arrays excludes variations in the thickness of the substrate as seen in conventional optical fiber arrays.

As a result, as described above, in this optical fiber array, the arrangement direction of the plurality of optical fibers 7 in the pair of substrates 5a and 5b and the pair of substrates 5a and 5b
The arrangement accuracy of the optical fibers in the two directions with respect to the direction in which b (one-dimensional optical fiber array) is provided is greatly improved.

Note that, when producing a one-dimensional optical fiber array, the end face of each optical fiber was polished. When light is emitted from the optical fiber, due to the difference between the refractive index of the optical fiber and the refractive index outside the fiber, some light does not exit outside the fiber at the interface between them, and the fiber Will be reflected back inside.

At this time, as shown in FIG. 21, when the end face of the optical fiber is substantially perpendicular to the optical axis, the ratio R of the reflected light is expressed by the following equation.

R = ((n−1) / (n + 1)) ² (1) where n = n ₂ / n ₁ , n ₁ is the refractive index of the fiber core,
n ₂ is the refractive index outside the fiber.

For example, when the outside of the fiber is air, R = 0.04. Next, as shown in FIG. 22, when the end face is polished obliquely, the efficiency η when the light reflected in this way is coupled to the optical fiber again is expressed by the following equation.

Η = exp (− (2πθw / λ) ² ) (2) where θ is the polishing angle, w is the beam waist size, and λ
Is the wavelength. When the value of θ is 0 °, the value of η is 1. All the reflected light couples with the optical fiber, but θ
Increases, the value of the efficiency η decreases.

From these, the return loss Retain-L
oss is approximated by: Reteun-Loss = −10 · log (R · η) (3) Note that the ratio R of reflection is strictly dependent on θ, but is approximated by the above equation (1) near θ = 0 °. You. However, when the value of θ becomes large, it cannot be approximated by the above equation (1).

When the return loss is specifically calculated by the above equation (3), the return loss is 14 dB when θ = 0 °, 33 dB when θ = 5 °, and 90 dB when θ = 10 °. By polishing the end face of the optical fiber obliquely as described above, the amount of return loss of light can be increased.

As shown in FIGS. 23 and 24,
A resin lens 20 may be provided on the end face of the optical fiber 7.
Processing accuracy (diameter, pitch accuracy, etc.) of resin lens 20 is ± 1
It is about μm, and has little effect on the deviation of the optical axis. By providing the resin lens 20, the spread angle of the light emitted from the optical fiber can be suppressed, and the collimating effect can be provided to the optical fiber array.

Further, by making the refractive index of the resin lens coincide with the refractive index of the optical fiber, the amount of light reflected at the interface between the resin lens and the optical fiber can be reduced, and the reflection at the surface of the resin lens can be reduced. It is possible to prevent the reflected light from returning to the optical fiber again.

By using glass substrates as the substrates 5a, 5b and 5c, the same material as that of the optical fiber can be obtained.
When the ambient temperature changes, the difference in thermal stress caused by the difference in the material of the substrate and the optical fiber disappears,
The reliability of the arrangement accuracy of each optical fiber can be improved.

Furthermore, in the above embodiment, the optical fiber arrangement accuracy in two directions, that is, the arrangement direction of the optical fibers on the pair of substrates 5a and 5b and the direction in which the plurality of pairs of substrates 5a and 5b are disposed. Although an optical fiber array with improved alignment has been described, the structure of the one-dimensional optical fiber array or the one-dimensional optical fiber array described above is also applicable to an optical fiber array requiring alignment accuracy in one direction. A positioning structure with a pair of holding portions can be applied.

The embodiment disclosed this time is an example in all respects, and should be considered as not restrictive. The present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0094]

According to the optical fiber array of one aspect of the present invention, a plurality of optical fibers are arranged only between a pair of opposing substrates. As a result, the arrangement accuracy of the optical fiber array is smaller than that in the case where a plurality of optical fibers are arranged between one pair of substrates and another pair of substrates as seen in a conventional optical fiber array. This eliminates variations in arranging a plurality of optical fibers on both main surfaces of a pair of substrates facing each other, and substantially eliminates variations in arranging optical fibers only on one main surface. become. As a result, the arrangement accuracy of the optical fibers in the arrangement direction of the plurality of optical fibers is greatly improved, and the optical axis with another optical device can be adjusted with high accuracy.

Preferably, by providing a positioning portion for positioning the pair of substrate holding members and the substrate pair array, the accuracy of the arrangement of the optical fibers in the direction in which the substrate pairs are disposed is greatly improved. Thus, the optical axis can be aligned with another optical device with higher accuracy.

Such a positioning portion includes a holding portion-side positioning groove provided in each of the pair of substrate holding members, and a substrate provided in the substrate pair array so as to face the holding portion-side positioning groove. It is preferable that the positioning groove includes a side positioning groove, and a clamped portion that is positioned between the holding portion side positioning groove and the substrate side positioning groove to perform positioning, and between the holding portion side positioning groove and the substrate side positioning groove. By sandwiching the to-be-clamped portion, the positioning of the substrate pair array and the pair of substrate holding members can be easily performed.

More specifically, the cross-sectional shape of the held portion is substantially circular, and the cross-sectional shapes of the holding portion-side positioning groove and the substrate-side positioning groove are substantially V-shaped, so that positioning can be easily performed. be able to.

Preferably, each end face of the plurality of optical fibers is polished obliquely in a direction intersecting the optical axis of the optical fiber, so that the efficiency of coupling light reflected at the end face of the optical fiber with the optical fiber is improved. This can reduce the return loss and increase the return loss.

Preferably, a lens is provided at each end face of the plurality of optical fibers, so that the spread angle of the light emitted from the optical fibers is suppressed, and the optical fibers can have a collimating effect.

More preferably, the material of the substrate forming the substrate pair array includes glass, so that the material of the substrate pair and the material of the optical fiber become substantially the same, and when the ambient temperature fluctuates. The difference in thermal stress caused by the different materials is substantially eliminated, and the reliability of the arrangement accuracy of the optical fibers is improved.

According to the method of manufacturing an optical fiber array according to another aspect of the present invention, the grooves for receiving the optical fibers are formed only on one main surface of the substrate so as to be arranged substantially in parallel with each other at intervals. Compared with the case where grooves are formed on both main surfaces of a substrate as seen in a conventional optical fiber array, variation in forming grooves on both main surfaces of a substrate is eliminated as the arrangement accuracy of optical fibers. Therefore, only the variation when forming the groove on one main surface of the substrate is substantially caused.
As a result, the arrangement accuracy of the optical fibers in the direction in which the optical fibers are arranged is greatly improved.

Preferably, the method further includes a step of forming a positioning portion for positioning the substrate pair array and the pair of substrate holding members. In the substrate pair array holding step, one step is performed by the positioning portion.
By disposing the pair of substrate holding members, the positioning portion significantly improves the arrangement accuracy of the optical fibers in the direction of disposing the substrate pair array.

The step of forming such a positioning portion is as follows.
Forming a holding portion side positioning groove in each of the pair of substrate holding members, and forming a substrate side positioning groove in the substrate pair array so as to face the holding portion side positioning groove;
And a step of preparing a sandwiched portion for performing positioning by being sandwiched between the holding portion side positioning groove and the substrate side positioning groove. The sandwiching portion is sandwiched, and positioning between the substrate pair array and the pair of substrate holding members can be easily performed.

More preferably, the step of forming a grooved substrate includes the step of forming a pair of substrate-to-array holding members having holding portion side positioning grooves, so that a substrate for forming a substrate pair is formed. And a pair of substrate-to-array holding members can be simultaneously formed, and the number of steps can be reduced.

Preferably, in the step of forming a grooved substrate, a plurality of grooves are formed in one substrate, and one substrate is divided along at least one of the grooves into a substrate pair. The step of forming a substrate-side positioning groove includes a step of forming one substrate and another substrate, and the step of forming a substrate-side positioning groove includes, when forming a substrate pair, a part of one groove remaining in one substrate and remaining in another substrate. Including a step in which a part of one of the grooves is formed so as to be formed at the same time as forming a substrate pair without separately providing a step for forming a substrate-side positioning groove. You.

Preferably, in the step of forming a plurality of substrate pairs, a jig having a predetermined surface with which the ends of the optical fibers come into contact is used to align the ends of the sandwiched optical fibers. Thus, the positions of the ends of the optical fibers can be easily aligned.

Preferably, in the substrate-to-array holding step, a jig for arranging the substrate-to-array to the pair of substrate holding members from the arrangement direction of the plurality of grooves is used. The pair can be easily arranged in a predetermined positional relationship with respect to the pair of substrate pair holding members.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an optical switch to which an optical fiber array according to a first embodiment of the present invention is applied;

FIG. 2 is a side view of the optical fiber array according to the embodiment.

FIG. 3 is a cross-sectional view of an optical fiber used for an optical fiber array in the embodiment.

FIG. 4 is a first cross-sectional view for explaining positioning of the one-dimensional optical fiber array and the substrate holding unit in the optical fiber array in the embodiment.

FIG. 5 is a second cross-sectional view for explaining positioning of the one-dimensional optical fiber array and the substrate holding unit in the optical fiber array in the embodiment.

FIG. 6 is a third cross-sectional view for describing positioning of the one-dimensional optical fiber array and the substrate holding unit in the optical fiber array in the embodiment.

FIG. 7 is a view showing one step of a method for manufacturing an optical fiber array according to Embodiment 2 of the present invention.

FIG. 8 is a diagram showing a step performed after the step shown in FIG. 7 in the embodiment.

FIG. 9 is a diagram showing a step performed after the step shown in FIG. 8 in Embodiment 1;

FIG. 10 is a view showing a step performed after the step shown in FIG. 9 in Embodiment 1;

FIG. 11 is a view showing a step performed after the step shown in FIG. 10 in Embodiment 1;

FIG. 12 is a diagram showing a step performed after the step shown in FIG. 11 in Embodiment 1;

FIG. 13 is a diagram showing a step performed after the step shown in FIG. 12 in Embodiment 1;

FIG. 14 is a view showing a step performed after the step shown in FIG. 13 in Embodiment 1;

FIG. 15 is a view showing another step performed after the step shown in FIG. 12 in Embodiment 1;

FIG. 16 is a view showing a step performed after the step shown in FIG. 15 in Embodiment 1;

FIG. 17 or FIG.
FIG. 7 is a view showing a step performed after the step shown in FIG. 6.

FIG. 18 is a view showing a step performed after the step shown in FIG. 17 in Embodiment 1;

FIG. 19 is a view showing a step performed after the step shown in FIG. 18 in Embodiment 1;

FIG. 20 is a diagram showing a step performed after the step shown in FIG. 19 in Embodiment 1;

FIG. 21 is a first diagram for explaining the behavior of light on the end face of the optical fiber in the embodiment.

FIG. 22 is a second diagram for explaining the behavior of light on the end face of the optical fiber in the embodiment.

FIG. 23 is a diagram showing a step of forming a resin lens on the end face of the optical fiber in the embodiment.

FIG. 24 is a diagram showing a step performed after the step shown in FIG. 23 in Embodiment 1;

FIG. 25 is a side view showing a conventional optical fiber array.

[Explanation of symbols]

1a, 1b optical fiber array, 2a, 2b lens array, 3a, 3b mirror array, 5a, 5b substrate,
5c Holding part, 6 grooves, 6a Substrate side positioning groove, 6b
Holding part side positioning groove, 7 optical fiber, 7a clad, 7b core, 8 positioning member, 12a to 12c
Jig, 13 adhesives, 17 screws, 20 resin lenses.

Claims (14)

[Claims] 1. A plurality of substrate pairs, in which a plurality of optical fibers are arranged in parallel with each other at intervals and held between only a pair of substrates facing each other, substantially in parallel with each other at intervals, and A substrate pair array disposed so that the sandwiched optical fibers are disposed substantially parallel to each other; and a pair of the substrate pair arrays facing each other from both sides in the arrangement direction of the plurality of optical fibers. An optical fiber array comprising: a substrate-to-array holding means, which is held by being held by the substrate holding member. 2. A positioning unit for positioning the pair of substrate holding members and the substrate pair array.
An optical fiber array according to any of the preceding claims. 3. The positioning part is provided in the substrate pair array so as to face the holding part side positioning groove provided in each of the pair of substrate holding members, and the holding part side positioning groove. 3. The optical fiber array according to claim 2, further comprising: a substrate-side positioning groove provided; and a held portion that is positioned between the holding portion-side positioning groove and the substrate-side positioning groove to perform positioning. 4. The optical fiber array according to claim 3, wherein a cross-sectional shape of said held portion is substantially circular, and a cross-sectional shape of said holding portion side positioning groove and said substrate side positioning groove is substantially V-shaped. 5. The optical fiber array according to claim 1, wherein each end face of said plurality of optical fibers is polished obliquely in a direction intersecting with an optical axis of said optical fiber. 6. The optical fiber array according to claim 1, wherein a lens is provided on each end face of said plurality of optical fibers. 7. The optical fiber array according to claim 1, wherein a material of the substrate forming the substrate-to-array includes glass. 8. A step of forming a grooved substrate having a plurality of grooves arranged substantially parallel to each other at intervals only on one main surface of each of the plurality of substrates; For each of the number of substrates, the same number of other substrates as the predetermined number of the plurality of substrates,
Forming a plurality of substrate pairs, wherein the corresponding grooves are opposed to each other so as to face each other, and the optical fibers are sandwiched in a state where the optical fibers are received between the opposed grooves. Forming a substrate pair array by arranging the pairs so as to be substantially parallel to each other at an interval, and so that the sandwiched optical fibers are arranged substantially parallel to each other; and A substrate-to-array holding step of sandwiching and holding a pair of substrate holding members facing each other from both sides in the arrangement direction of the plurality of grooves. 9. A step of forming a positioning portion for positioning the substrate pair array and the pair of substrate holding members, wherein in the substrate pair array holding step, the pair of substrate holding members is formed by the positioning portion. The method for manufacturing an optical fiber array according to claim 8, wherein is disposed. 10. The step of forming the positioning part includes: forming a holding part-side positioning groove in each of the pair of substrate holding members; and opposing the holding part-side positioning groove in the substrate pair array. 10. A step of forming a substrate-side positioning groove as described above, and a step of preparing a pinched portion for positioning by being sandwiched between the holding part-side positioning groove and the substrate-side positioning groove. Of manufacturing an optical fiber array. 11. The method according to claim 10, wherein the step of forming the grooved substrate includes the step of forming the pair of substrate-to-array holding members having the holding portion-side positioning grooves. . 12. The step of forming the grooved substrate includes forming a plurality of grooves on one substrate, dividing the one substrate along the inside of at least one of the grooves, and forming a plurality of grooves on the substrate pair. Forming the one substrate and the other substrate, wherein the step of forming the substrate-side positioning groove includes, when forming the substrate pair, a part of the one groove remaining in the one substrate. The method of manufacturing an optical fiber array according to claim 11, further comprising a step of forming a part of the one groove remaining on the other substrate by facing the part of the one groove. 13. The step of forming the plurality of substrate pairs uses a jig having a predetermined surface with which the ends of the optical fibers are in contact, in order to align the positions of the ends of the optical fibers sandwiched therebetween. The method for manufacturing an optical fiber array according to any one of claims 8 to 12, which is performed. 14. A jig for arranging the substrate pair array with respect to the pair of substrate holding members from an arrangement direction of the plurality of grooves in the substrate pair array holding step. 14. The method for manufacturing an optical fiber array according to any one of items 13 to 13.