JPH0815562A - Alignment method of direction of rotating direction of optical fiber in optical fiber array and optical fiber array - Google Patents

Abstract

PURPOSE:To provide an alignment method of the directions of the rotating directions of the optical fibers in an optical fiber array taking axial misalignment positions into consideration and an optical fiber array. CONSTITUTION:The magnified images of the plural optical fibers 2a, 2a are obtd. by an image obtaining means 6 for the respective optical fibers 2a, 2b in the alignment method of the directions of the rotating directions of the optical fibers in the optical fiber array contg. the optical fibers 2a, 2b and an optical fiber holding member 3. The distribution of the characteristics of the images corresponding to the positions in the diametral direction of the optical fiber images is determined from the magnified images obtd. in such a manner. The axial misalignment positions of the cores with respect to the centers of the optical fibers 2a, 2b are measured from this distribution of the characteristics of the images. The axial misalignment positions for the holding member 3 of the optical fibers 2a, 2b are adjusted by optical fiber rotating mechanisms 9a, 9b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an optical fiber gyro,
The present invention relates to a method for aligning the direction of rotation of optical fibers in an optical fiber array used for a coupling portion between an optical waveguide and an optical fiber used for an optical modulator, an optical switch, etc. and a coupling portion between optical fibers, and an optical fiber array.

[0002]

2. Description of the Related Art An example of an optical fiber array is an optical fiber array using a polarization maintaining optical fiber.
In the conventional method for aligning the rotation angle of a polarization-maintaining optical fiber, the polarization plane is preserved, and the linearly polarized light whose oscillation direction of the electric field is parallel to the principal axis of the birefringence is propagated to the optical fiber to produce the linearly polarized light at the exit end. The angle of the birefringent main axis with respect to the optical fiber holding member is adjusted by the angle of.
For example, as shown in FIG. 7, the light emitted from the semiconductor laser 31 is converted into substantially parallel light by the first lens 32, and the polarizer 3
Polarization-maintaining optical fiber 3 held by a holder 35 that is linearly polarized by means of 3 and is rotatable around a substantially central axis.
The light is condensed by the second lens 34 at one end of 6 and propagated in the optical fiber.

On the other hand, the other end of the optical fiber from which the propagating light is emitted is also V-shaped for embedding an optical fiber previously provided in an optical fiber holding member 37 through a holder 35 rotatable about a substantially central axis. Is placed in the groove (not shown), and the cover member 38 is placed thereon.

A polarization-maintaining optical fiber has two birefringent principal axes that are orthogonal to each other. Therefore, if the approximate direction of the birefringent principal axes is not known, the vibration direction of the electric field of linearly polarized light propagating in the optical fiber is It is not possible to know if it is parallel to the principal axis of birefringence. Therefore, if the alignment of the birefringent principal axis is attempted only by the vibration direction of the linearly polarized electric field emitted from the optical fiber, the desired direction is 90
° Since there is a possibility of different orientations, the birefringent main axis is aligned in a substantially desired direction in advance, and within the range of this alignment error, the optical fiber output end at the time of alignment depending on the direction of linearly polarized light It is necessary to limit the rotation range.

Therefore, when the elliptic core type optical fiber 42 is used as the polarization-maintaining optical fiber 36, as shown in FIG. 8, the major axis 44 and the minor axis 45 of the elliptical core 43 are the birefringent principal axes. Therefore, it is placed on the holding member while observing the near-field pattern of the emitted light from the optical fiber by the CCD camera (not shown) or the far-field pattern of the emitted light projected on the screen (not shown). The output end of the optical fiber is rotated to align the principal axis of birefringence in a substantially desired direction. Further, as the polarization-maintaining optical fiber 36, an elliptical jacket type optical fiber 46 is used.
In the case of using, the major axis 48 and the minor axis 49 of the elliptical jacket 47 are the birefringent main axes as shown in FIG. The exit end of the mounted optical fiber is previously etched with a hydrofluoric acid aqueous solution to form a step between the jacket and other parts, and the optical fiber is moved while observing an enlarged image of this end face with a CCD camera. Rotate and align the birefringent principal axis in a substantially desired direction.

Next, the emitted light is focused on the photodetector 41 through the third lens 39 and the analyzer 40, and while the output of the photodetector 41 is monitored, the incident end of the optical fiber and the analyzer 40 are rotated. When the rotational position of the incident end that minimizes the polarization crosstalk is obtained and one of the birefringent principal axes of the optical fiber at the incident end and the oscillation direction of the optical electric field are matched, the light emitted from the optical fiber is Linearly polarized light whose oscillation direction is parallel to one of the two birefringent principal axes.

Then, the azimuth of the analyzer 40 is aligned with the direction of the desired birefringent main axis, and the emitting end of the optical fiber is an elliptical jacket for alignment by a near field pattern or a far field pattern in the case of an elliptic core type optical fiber. In the case of a type optical fiber, by rotating within a range of an alignment error due to a magnified image of the end face, for example, within a range of ± 10 ° and directing it to a rotational position where the output of the light receiver 41 becomes maximum or minimum, Alignment in the direction of rotation of the optical fiber is being performed.

[0008]

By the way, when an optical fiber array is manufactured by using a plurality of optical fibers having an axis deviation of 0.5 μm, the core spacing of the adjacent optical fibers becomes
Since the error from the desired spacing reaches a maximum of 1 μm, it is difficult to reduce the coupling loss due to the positional deviation in the connection portion between the optical fiber array and the plurality of optical waveguides arranged and formed.

Further, the shorter the wavelength of the light propagating in the optical fiber, the smaller the mode field size of the propagating light in the optical waveguide and the optical fiber, and therefore the larger the coupling loss increase amount with respect to the same positional shift amount. In a system such as a sensor that uses light with a short wavelength, it is important to reduce the error in the core spacing between adjacent optical fibers of an optical fiber array due to the axial misalignment of the cores. When using a low-cost elliptical core type polarization-maintaining single-mode fiber, the mode field size in the minor axis direction of the elliptical core is smaller than that in the major axis direction. Matching is important for all optical fibers that make up the array. However, in the alignment of the polarization-maintaining optical fiber in the rotation direction by the conventional method, many steps have to be performed as described above, and in addition to requiring time, it is not possible to perform the alignment considering the axial misalignment position. could not.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide an alignment method for the direction of rotation of an optical fiber in an optical fiber array in consideration of an axial shift position, and an optical fiber array.

[0011]

In order to achieve the above-mentioned object, the present invention provides an alignment method for the direction of rotation of optical fibers in an optical fiber array including a plurality of optical fibers and an optical fiber holding member. An enlarged image of the optical fiber is obtained by the image obtaining means with respect to the optical fiber, and a distribution of image characteristics such as a light intensity distribution corresponding to the radial position of the optical fiber image is obtained from the obtained enlarged image, and the characteristic The axial shift position of the core center with respect to the optical fiber center is measured from the distribution, and the optical fiber rotating mechanism adjusts the axial shift position of the optical fiber with respect to the holding member.

According to the present invention, in an optical fiber alignment method in an optical fiber array including a plurality of optical fibers and an optical fiber holding member, at least two of the optical fibers whose angle is changed with respect to each optical fiber by the image acquisition means. Obtain two magnified images, find the distribution of image features such as the light intensity distribution corresponding to the radial position of the optical fiber image from the obtained magnified images, and use the distribution of these features to determine the center of the core with respect to the center of the optical fiber. The axial misalignment position is measured for each optical fiber, and the optical fiber rotating mechanism rotates an arbitrary optical fiber with respect to the holding member to adjust the axial misalignment position of the optical fiber with respect to the holding member.

According to the present invention, in the alignment method of the direction of rotation of the optical fiber in the optical fiber array including the plurality of optical fibers having the non-axisymmetric refractive index distribution and the optical fiber holding member, the central axis of each optical fiber is With respect to various rotation directions about the rotation axis, a magnified image of the optical fiber is acquired from the side with respect to the guided light propagation direction of the optical fiber by the image acquisition means, and the radial direction of the optical fiber image is acquired from the acquired magnified image. By determining the distribution of the image features such as the light intensity distribution corresponding to the position and detecting the direction of the optical fiber rotation direction that has the predetermined feature distribution, the predetermined optical fiber cross-section is determined. The specific axis is once aligned in parallel with the optical axis of the image acquisition means, and the axial misalignment position of the core with respect to the center of the optical fiber is measured from the distribution of the image features. To rotate the holding member for holding the optical fiber or optical fibers, which adjusts the axial deviation of the orientation and the core of the particular axis of the respective optical fiber with respect to the optical fiber holding member.

According to the present invention, in the alignment method of the direction of rotation of optical fibers in an optical fiber array including a plurality of optical fibers having a non-axisymmetric refractive index distribution and an optical fiber holding member, the central axes of the respective optical fibers are With respect to various rotation directions about the rotation axis, an enlarged image of the optical fiber is acquired by the image acquisition means from the side with respect to the guided light propagation direction of the optical fiber, and the radial position of the optical fiber image is obtained from the acquired enlarged image. By determining the distribution of the image features such as the light intensity distribution corresponding to, and detecting the orientation of the optical fiber in the rotation direction that has the predetermined feature distribution, the predetermined identification on the cross section of the optical fiber can be performed. The axis of the core is once aligned in parallel with the optical axis of the image acquisition means, and the axial deviation position of the core with respect to the center of the optical fiber is measured from the light intensity distribution. An optical fiber that does not match the desired position or an optical fiber that does not match the axial misalignment position of more than half of the optical fibers is rotated by 180 ° so that the specific axes of all the optical fibers and the optical axis of the image acquisition means are parallel again. The direction of the optical axis of the image acquisition means with respect to the holding member is adjusted or predetermined so that the specific axis of the optical fiber holding member is oriented in a desired direction when they are aligned.

According to the present invention, in an optical fiber array including a plurality of optical fibers and an optical fiber holding member, an enlarged image of the optical fiber is acquired by image acquisition means for each optical fiber, and the optical image is acquired from the acquired enlarged image. Obtain the distribution of image features such as the light intensity distribution corresponding to the radial position of the fiber image, measure the axial misalignment position of the core center from the center of the optical fiber from the distribution of the features, and use the optical fiber rotation mechanism. The distance between the cores is adjusted or made uniform by adjusting the axial shift position of each optical fiber with respect to the holding member.

[0016]

According to the above construction, when the plurality of optical fibers are photographed from the side with respect to the guided light propagation direction by the image obtaining means, an enlarged image of the optical fibers can be obtained. When image processing is performed by the image processing apparatus for each of the plurality of acquired enlarged images, the distribution of image characteristics such as the light intensity distribution corresponding to the radial position of the optical fiber image is obtained. The distribution of the features in this image shows a characteristic curve that differs depending on the direction of rotation of the optical fiber and is reproducible. Therefore, the rotation angle with the center axis of the optical fiber as the axis of rotation is measured from the distribution of the image features, and the axial misalignment position of the core with respect to the center of the optical fiber is known based on the measurement results, and any optical fiber can be rotated. By doing so, the distance between the cores can be made equal to the distance between the cores of the optical waveguide.

[0017]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a diagram showing an example of an outline of a main part of an apparatus to which an alignment method of an optical fiber in a rotation direction of an optical fiber array of the present invention is applied. Here, a case where an optical fiber array is manufactured by using the polarization-maintaining optical fiber strands 1a and 1b as the optical fiber will be described.

As shown in the figure, two optical fibers 2a and 2b, in which the coating on the tip of the polarization-maintaining optical fiber strands 1a and 1b is removed, are arranged in parallel on the surface of the optical fiber holding member 3 in advance. The optical fibers are placed in the two V-shaped grooves 4a and 4b for embedding the optical fiber, and an ultraviolet curable adhesive (not shown) is applied, and the cover member 5 is placed thereon. Has been done. The polarization-maintaining optical fiber strands 1a and 1b are attached to the optical fiber rotating mechanisms 9a and 9b serving as optical fiber rotating members, respectively, so that the optical fibers 2a and 2b are rotatable about the central axis of the core. Has become.

On the other hand, of the two polarization-maintaining optical fibers 2a and 2b mounted on the optical axis of the image pickup camera 6, the optical fiber (for example, 2a) which is aligned in the angle of the birefringent main axis. Are arranged so as to be sandwiched between the imaging camera 6 and the illumination light source 8. Illumination light is emitted from a lower side surface of the optical fiber 2a in a direction crossing the core, the emitted light is transmitted through the optical fiber 2a, and an enlarged image of the optical fiber 2a is acquired by the imaging camera 6. From the acquired enlarged image, the light intensity distribution corresponding to the radial position of the optical fiber image (not shown) can be calculated by the image processing device 7. In this light intensity distribution, characteristic curves having different characteristics can be obtained by changing the angle formed by the optical axis of the imaging camera 6 and the birefringent main axis. This is because the components of the polarization-maintaining optical fiber such as the core, the clad, and the jacket have different refractive indexes, and the shape of at least one component is non-axisymmetric.

Therefore, when the controller 10 determines the direction of the birefringent main axis and the axial misalignment position of the core, and the controller 10 drives the rotating mechanism 9a to which the optical fiber 2a to be aligned is attached. The orientation of the birefringent principal axis and the axial misalignment position of the core can be adjusted (the same applies to the orientation of the birefringent principal axis of the optical fiber 2b and the axial misalignment position of the core).

Next, the operation of the embodiment will be described.

FIG. 2A is a schematic cross-sectional view when the angle formed by the optical axis of the image pickup camera and the birefringent main axis in the major axis direction of the core of the elliptic core type polarization-maintaining optical fiber is 0 °. Two
(B) is a figure which shows the light intensity distribution. FIG. 3A is a schematic cross-sectional view when the angle formed by the optical axis of the imaging camera and the birefringent main axis in the major axis direction of the elliptical core is 90 °.
(B) is a figure which shows the light intensity distribution. The distance between the imaging camera 6 and the optical fiber 2a is adjusted with a resolution of 0.5 μm so that the maximum values l and r of the light intensity of the image on the outer peripheral portion of the optical fiber are maximized.

The optical axis 14a of the image pickup camera 6 and the birefringent main axis 1
When the rotation angle of the optical fiber 2a is adjusted so as to be parallel to 5a (FIG. 2 (a)), the maximum value a of the light intensity at the center of the optical fiber 2a as shown in FIG. 2 (b) is obtained. Is the maximum, and the minimum values b and c of the light intensity appear on both sides of the maximum a,
The difference in light intensity between b and between a and c was the maximum. Further, the light intensity distribution is substantially line-symmetrical with a corresponding to the center of the core 12a as the axis of symmetry, and the difference in light intensity between the minimum values b and c appearing at the substantially line-symmetrical position is minimized.

On the other hand, when the optical fiber 2a is rotated so that the angle formed by the optical axis 14a and the birefringent main axis 15a becomes 90 ° (FIG. 3 (a)), as shown in FIG. 3 (b). It is difficult to distinguish the maximum value a and the minimum values b and c, but b
The difference in the light intensity between c and c has almost disappeared. Although not shown here, when the angle formed by the optical axis 14a and the birefringent main axis 15a is other than 0 ° and 90 °, the difference in light intensity between b and c becomes large. . The light intensity distribution near the center of the optical fiber obtained here reflects the shape of the elliptical core 12a, the refractive index difference between the core 12a and the cladding 13a, and the angle formed by the optical axis 14a and the birefringent main axis 15a. Therefore, the position where the maximum value a of the light intensity appears in FIGS. 2B and 3B corresponds to the position of the center of the core 12a.

Utilizing the fact that the characteristic light intensity distribution is obtained depending on the orientation of the birefringent main axis 15a in this manner, the two polarization-maintaining optical fibers 2a and 2b shown in FIG. 2A, the major axis birefringent axis 15a of the elliptical core 12a of the one optical fiber 2a is aligned in parallel with the optical axis 14a of the imaging camera 6 as shown in FIG. From (b), the distance s between the left outer peripheral edge of the optical fiber 2a and the core center and the distance t between the right outer peripheral edge of the optical fiber 2a and the core center are measured in pixel units,
It was possible to measure the axial misalignment position of the elliptical core 12a in the minor axis direction. At this time, the axial misalignment position was 0.65 μm to the right of the center of the optical fiber 2a.

Next, for the other optical fiber 2b, the birefringent main axis 15b in the major axis direction of the elliptical core 12b is similarly formed.
Was aligned in parallel with the optical axis 14b of the image pickup camera 6 and the position of the axis deviation was measured and found to be 0.59 μm to the left, so the optical fiber 2b was rotated 180 ° so that the direction of the axis deviation was to the right. Again, the optical axis 14b and the birefringent main axis 15b are aligned parallel to each other, the adhesive is cured by ultraviolet irradiation, and the end faces of the optical fibers 2a and 2b, the holding member 3 and the cover member 5 are polished, and the polarization as shown in FIG. The wavefront-preserving optical fiber array 60 could be manufactured. 4 is a sectional view taken along the line AA of the optical fiber array shown in FIG.

In FIG. 4, the birefringent main axes 15a and 15b of the optical fibers 2a and 2b are perpendicular to the surface of the holding member 3 (parallel to the paper surface), and the cores 12a and 12b are located on the surface of the holding member 3. It is perpendicular to the core 12
a and 12b are centers 50a and 50 of the optical fibers 2a and 2b.
Both were off-axis to the upper right with respect to b. In addition, the two cores 12a,
Intervals P ₁ and two V-shaped grooves 4a between 12b, and the difference between the distance P ₂ between 4b can be made 0.1μm or less, further reference bottom tip 4aa of the V-shaped grooves 4a of the core 12a the height was h ₁ and the bottom tip 4 of the V-shaped grooves 4b of the core 12b
The difference from the height h ₂ based on bb could also be set to 0.1 μm or less. In this way, the elliptical cores 12a, 12b
The optical fibers 2a and
This is because 2b is continuously cut out from a single optical fiber.

After the optical fiber 2a is aligned in the rotational direction as in the above-described embodiment, the optical fiber 2b is rotated by 90 ° in the same direction, so that the birefringent main shafts 15a and 15b are held by the holding member 3. It was possible to fabricate an optical fiber array that was parallel to the surface and had the same axial misalignment. Further, the optical axes 14a and 14b
The optical axes 14a and 14b of the holding member 3 are preliminarily set so that the directions of the birefringent main axes 15a and 15b are parallel to the surface of the holding member 3 when the and the birefringent main axes 15a and 15b are aligned in parallel. A similar optical fiber array could be produced by setting the surface parallel to the surface (parallel to the paper surface).

As shown in FIG. 3A, the optical fiber 2a
Even when the angle formed by the birefringent main axis 15 in the long axis direction of the elliptical core 12a (12b) of (2b) and the optical axis 14 of the imaging camera 6 is set to 90 °, the light intensity distribution (see FIG. ))
The distance s between the left outer peripheral edge of the optical fiber 2a (2b) and the core center and the distance t between the right outer peripheral edge and the core center.
Can be measured in pixel units to measure the axial misalignment position of the elliptical core 12a (12b). Similarly, the birefringent main axes 15a and 15b are parallel to the surface of the holding member 3. In addition, it was possible to fabricate an optical fiber array in which the axial misalignment positions were the same.

Next, the case where the elliptical jacket type polarization-maintaining single-mode fiber 16 is used as the optical fiber will be described.

FIG. 5A is a schematic sectional view when the angle formed by the optical axis of the image pickup camera and the birefringent main axis in the major axis direction of the elliptical jacket of the polarization maintaining optical fiber of the elliptical jacket type is 0 °. 5B is a diagram showing the light intensity distribution. FIG. 6A is a schematic cross-sectional view when the angle formed by the optical axis of the imaging camera and the major axis birefringent main axis of the elliptical jacket is 90 °, and FIG. 6B shows the light intensity distribution. FIG. It should be noted that it is 1 than the distance at which the maximum values l and r become maximum
The distance between the imaging camera 6 and the optical fiber 16 is adjusted with a resolution of 0.5 μm so as to increase by 0 μm.

As shown in FIG. 5A, when the rotation angle of the optical fiber is adjusted so that the optical axis 14 and the birefringent main axis 21 are parallel to each other, as shown in FIG. The intensity distribution is substantially line-symmetrical with the center of the bright part a corresponding to the center of the core as the axis of symmetry, and one set of bright parts d and e appears at positions that are substantially line-symmetrical near the center of the optical fiber. The difference in the light intensity was minimized. Further, a pair of dark portions b and c appear at positions on the inner circumference side of the bright portions d and e on the inner circumference side of the optical fiber, which are substantially line-symmetrical with respect to the center of the bright portion a corresponding to the center of the core. In the vicinity of the outer peripheral side of the parts d and e, no remarkable dark part whose light intensity was lower than that of the outer peripheral side did not appear.

On the other hand, as shown in FIG. 6 (a), when the angle formed by the optical axis 14 and the birefringent main axis 21 is 90 °, that is, the optical axis 14 and the birefringent main axis 22 in the minor axis direction of the elliptical jacket. When the rotation angle of the optical fiber is adjusted so that and become parallel to each other, as shown in FIG. 6B, the light intensity distribution is substantially line-symmetrical with the center of the bright portion a corresponding to the center of the core as the axis of symmetry. And a pair of bright portions d and e appear at positions of substantially linear symmetry near the center of the optical fiber, and a pair of dark portions b and b at positions of the bright portions d and e on the inner circumference side of the optical fiber. c appeared, and a pair of remarkable dark parts f and g whose light intensity was lower than that on the outer peripheral side of the bright parts d and e appeared. Although not shown here, the angle formed by the optical axis 14 and the birefringent main axis 21 is 0.
When the angles were other than 90 ° and 90 °, the line symmetry of the light intensity distribution was lost.

Utilizing the fact that a characteristic light intensity distribution is obtained depending on the orientation of the birefringent principal axis 21 or the birefringent principal axis 22 as described above, the two polarization-maintaining single-mode fibers 2a and 2b shown in FIG. Elliptical jacket type polarization-maintaining optical fiber 1
6, the birefringent main axis 21 or the birefringent main axis 22 of the elliptical jacket 19 of the one optical fiber 16 is aligned in parallel with the optical axis 14 of the image pickup camera as shown in FIG. 5A or 6A. Light intensity distribution (Fig. 5 (b) or Fig. 6)
From (b), the distance s between the left outer peripheral edge of the optical fiber 16 and the core center and the distance t between the right outer peripheral edge and the core center are measured in pixel units, and the short axis direction and the length of the elliptical jacket 19 are measured. The axial misalignment position of the core 17 in the axial direction can be measured, and as in the case of the elliptic core type polarization-maintaining optical fiber,
It was possible to fabricate an optical fiber array in which the birefringent principal axes were aligned and the axial misalignment positions were matched.

As the optical fiber, the polarization-maintaining optical fiber of the elliptic core type and the elliptical jacket type has been described as an example. However, non-axial symmetry such as so-called PANDA type, Bow-Tie type, side pit type and side tunnel type is used. A polarization-maintaining single-mode fiber having a refractive index distribution, an absolute single-polarization optical fiber, or a multi-core optical fiber also has a characteristic light intensity distribution depending on the direction of rotation. The specific axis and the optical axis of the imaging camera are aligned in parallel, and the axial misalignment position in the direction orthogonal to the specific axis at that position is measured, and the optical axis rotation direction is taken into consideration in consideration of the specific axis and the axial misalignment position. Alignment,
It is possible to make an optical fiber array.

When manufacturing an optical fiber array using an optical fiber having a substantially axially symmetric refractive index distribution such as a so-called single mode optical fiber, a substantially similar light intensity distribution is exhibited in any rotation direction. However, it is possible to measure the distance from the outer peripheral edge of the optical fiber to the center of the core in pixel units in any rotation direction.

Therefore, it is possible to measure the axial shift position of each optical fiber by repeating the axial shift position measurement with respect to the center of the optical fiber at the center of the core while rotating the optical fiber about its rotation axis. Therefore, it is possible to fabricate the optical fiber array by performing the alignment in the rotation direction of the optical fiber in consideration of the axial shift position.

Although the optical fiber array having two cores is taken as an example, the number of optical fibers is not limited to two, and an optical fiber array having three or more cores may be used.

[0040]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) It is possible to manufacture an optical fiber array in which the distance between the cores of adjacent optical fibers and the distance from the surface of the optical fiber holding member to the cores are uniform.

(2) The coupling loss due to the positional deviation between the optical fiber array and the optical waveguide array is reduced.

(3) The production yield of the optical fiber array is improved and the cost is reduced.

(4) The requirement for axial misalignment of the cores of the optical fibers used in the optical fiber array can be relaxed, and the yield and cost of the optical fibers can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an outline of a main part of an apparatus to which an alignment method in an optical fiber rotating direction in an optical fiber array of the present invention is applied.

FIG. 2A is a schematic cross-sectional view when the angle formed by the optical axis of the imaging camera and the birefringent principal axis in the major axis direction of the core of the elliptic core type polarization-maintaining optical fiber is 0 °; ) Is a diagram showing the light intensity distribution.

FIG. 3 (a) is a schematic cross-sectional view when the angle formed by the optical axis of the imaging camera and the major axis of birefringence in the major axis direction of the elliptical core is 90 °, and FIG. 3 (b) shows its light intensity distribution. FIG.

FIG. 4 is a cross-sectional view taken along the line AA of the optical fiber array shown in FIG.

FIG. 5A is a schematic cross-sectional view when the angle formed by the optical axis of the imaging camera and the birefringent principal axis in the major axis direction of the elliptical jacket of the elliptical jacket-type polarization-maintaining optical fiber is 0 °; (B) is a figure which shows the light intensity distribution.

6A is a schematic cross-sectional view when the angle formed by the optical axis of the imaging camera and the birefringent main axis of the elliptical jacket in the major axis direction is 90 °, and FIG. 6B shows the light intensity distribution. FIG.

FIG. 7 is a schematic side view of a system that performs an alignment method for a rotation direction of an optical fiber in a conventional optical fiber array.

FIG. 8 is a cross-sectional view showing a birefringent main axis of an elliptic core type optical fiber.

FIG. 9 is a cross-sectional view showing a birefringent main axis of an elliptical jacket type optical fiber.

[Explanation of symbols]

 2a, 2b optical fiber 3 optical fiber holding member 6 image acquisition means (imaging camera) 7 image processing device 8 illumination light source 9a, 9b optical fiber rotation mechanism 10 control device

Front page continuation (72) Inventor Toshio Iizuka 5-1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture Hitachi Cable Co., Ltd. Hidaka Factory (72) Inventor Mamoru Ichimura 122, Upper end of Komaki City, Aichi Prefecture KU Co., Ltd. (72) Inventor Tomohiro Murakami 122, Upper end, Oma, Komaki City, Aichi Suntech Co., Ltd.

Claims (10)

[Claims] 1. In an alignment method of an optical fiber array in a direction of rotation in an optical fiber array including a plurality of optical fibers and an optical fiber holding member, an enlarged image of each optical fiber is obtained by an image acquisition means. Obtained, obtain the distribution of the image features corresponding to the radial position of the optical fiber image from the obtained enlarged image, and measure the axial misalignment position of the core center with respect to the center of the optical fiber from the feature distribution of the image, An alignment method of an optical fiber rotating direction in an optical fiber array, wherein an axial misalignment position of the optical fiber with respect to a holding member is adjusted by an optical fiber rotating mechanism. 2. In an alignment method of the direction of rotation of optical fibers in an optical fiber array including a plurality of optical fibers and an optical fiber holding member, the image acquisition means changes the angle of each optical fiber. Of at least two magnified images of the image are acquired, the distribution of the image features corresponding to the radial position of the optical fiber image is obtained from each of the acquired magnified images, and the distribution of the feature of the image determines the center of the core with respect to the center of the optical fiber. An optical fiber array characterized in that an axial misalignment position is measured for each optical fiber, and an optical fiber rotating mechanism rotates an arbitrary optical fiber with respect to a holding member to adjust an axial misalignment position of the optical fiber with respect to the holding member. Alignment method for optical fiber rotation direction. 3. In the alignment method of the direction of rotation of an optical fiber in an optical fiber array including a plurality of optical fibers having a non-axisymmetric refractive index distribution and an optical fiber holding member, the central axes of the respective optical fibers are substantially the same. An enlarged image of the optical fiber is acquired by the image acquisition means from the side with respect to the guided light propagation direction of the optical fiber with respect to various rotation directions about the rotation axis, and the radial position of the optical fiber image is set from the acquired enlarged image. Find the distribution of corresponding image features,
By detecting the direction of rotation of the optical fiber having a predetermined image feature distribution, a predetermined specific axis on the optical fiber cross section is once aligned parallel to the optical axis of the image acquisition means. , The axial misalignment position of the core with respect to the center of the optical fiber is measured from the distribution of the characteristics of the image, and then the optical fiber or the holding member for holding the optical fiber is rotated to determine the specific position of each optical fiber with respect to the optical fiber holding member. A method for aligning a direction of a rotation direction of an optical fiber in an optical fiber array, which comprises adjusting an axial direction and an axial shift position of a core. 4. In a method of aligning a direction of a rotation direction of an optical fiber in an optical fiber array including a plurality of optical fibers having a non-axisymmetric refractive index distribution and an optical fiber holding member, the central axes of the respective optical fibers are set substantially. An enlarged image of the optical fiber is acquired by the image acquisition means from the side with respect to the guided light propagation direction of the optical fiber with respect to various rotation directions about the rotation axis, and the radial position of the optical fiber image is set from the acquired enlarged image. Find the distribution of corresponding image features,
By detecting the direction of rotation of the optical fiber having a predetermined image feature distribution, a predetermined specific axis on the optical fiber cross section is once aligned parallel to the optical axis of the image acquisition means. Measure the axial misalignment position of the core with respect to the center of the optical fiber based on the distribution of the image features, and select the optical fiber whose axial misalignment position does not match the desired position or the optical axis misalignment position of more than half of the optical fibers. When rotated by 180 ° and the specific axes of all the optical fibers and the optical axes of the image acquisition means are aligned again in parallel, the specific axes are oriented in a desired direction with respect to the optical fiber holding member. In addition, the orientation of the optical axis of the image acquisition means with respect to the holding member is adjusted or determined in advance. Law. 5. The distribution of the features of the image is a light intensity distribution, and a bright portion or a dark portion corresponding to the outer peripheral end of the optical fiber,
The alignment method of the optical fiber array in the rotation direction of the optical fiber array according to claim 1, wherein the axial deviation position is measured from a distance between the core or a bright portion or a dark portion corresponding to the center of the core. 6. The alignment of the optical fiber in the optical fiber array according to claim 3, wherein the optical fiber is a polarization-maintaining optical fiber, and the specific axis is a birefringent main axis of the optical fiber. Method. 7. The alignment method of the rotation direction of an optical fiber in an optical fiber array according to claim 6, wherein the optical fiber is an elliptic core type polarization-maintaining optical fiber. 8. An alignment method for an optical fiber array in a rotation direction in an optical fiber array according to claim 6, wherein said optical fiber is an elliptical jacket type polarization-maintaining optical fiber. 9. In an optical fiber array including a plurality of optical fibers and an optical fiber holding member, an enlarged image of the optical fiber is acquired by image acquisition means for each optical fiber, and an optical fiber image is obtained from the acquired enlarged image. The image feature distribution corresponding to the radial position of the image is obtained, and the axial misalignment position of the center of the core with respect to the center of the optical fiber is measured from the image feature distribution. An optical fiber array characterized in that a core gap is adjusted or made uniform by adjusting an axial shift position with respect to a holding member. 10. The optical fibers are continuously cut out from a single optical fiber, and the optical fibers are aligned in the rotational direction so that the axial misalignment position is in a desired direction. The optical fiber array described.