JPH11295549A - Alignment method for optical fiber, and optical stage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and accurately splice optical fibers to each other in an alignment method for optical fibers for splicing the optical fibers having an end face inclined to an optical axis to each other. SOLUTION: In the case of attaching the optical fiber 20 to this optical stage 30, a capillary 10 is inserted between an upper side stage 31 and a lower side stage 32 and placed on the groove 32b of the optical stage 30 in the state of turning a reference surface 13 upwards. Then, by tightening screws 33 and 34 for adjustment, the upper side stage 31 approaches the side of the lower side stage 32 and clamps the capillary 10 with the groove 32b. At the time, since the reference surface 13 of the capillary 10 is tightly adhered to the lower side face 31a of the upper side stage 31 parallel to a horizontal plane, the reference surface 13 also becomes parallel to the horizontal plane. Also, since the groove 32b is formed so as to be inclined for an angle θ1 to a line L1 perpendicular to the end face 32c, the capillary 10 is also inclined for the angle θ1 to the line L1. Thus, the end face 12 of the capillary 10 becomes parallel to the end face 32c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical fiber alignment method for connecting optical fibers and an optical stage, and more particularly to an optical fiber alignment method for bonding end faces of optical fibers and an optical stage.

[0002]

2. Description of the Related Art At present, when optical fibers are connected to each other, monitor light is conducted between two optical fibers to be connected in order to perform coupling with low connection loss, and the output intensity of the monitor light is maximized. It is a mainstream to use an alignment method for adjusting the direction and the position of the optical fiber so as to be so-called, a so-called active alignment method.

FIG. 6 is a plan view showing a general active alignment method. When two optical fibers 71 and 72 are connected, capillaries 73 and 74 as holding members are attached to ends of the optical fibers 71 and 72. At this time, the end faces 73a, 74a of the capillaries 73, 74 are attached so as to coincide with the end faces 71a, 72a of the optical fibers 71, 72. In this manner, the positions of the optical fibers 71 and 72 are adjusted by using an optical stage (not shown) or the like.
Adjustment is made in the three axes of the axis, the Y axis, and the Z axis, and the end faces of the capillaries 73 and 74 are bonded at the point where the output intensity of the monitor light becomes maximum.

In such a method, each of the optical fibers 71,
72 and end faces 71a, 72 of the capillaries 73, 74
Since a, 73a and 74a are almost perpendicular to the optical axis, X
The work can be done simply by adjusting the three axes of axis, Y axis and Z axis.

However, the end faces 71a, 72a, 73a, 7
If 4a is perpendicular to the optical axis, the reflection of light on the connection surface will increase. Therefore, the optical fibers 71, 72
And each end face 71a, 72a of the capillary 73, 74,
There is an alignment method for an optical fiber in which 73a and 74a are cut obliquely with respect to the optical axis.

FIG. 7 is a view showing a conventional alignment method in which end faces of an optical fiber and a capillary are obliquely cut. Optical fibers 71 and 72 and capillaries 73 and 7
By making each of the end faces 71a, 72a, 73a, 74a of 4 beveled, light is reflected in a direction different from the optical axis on the connection surface, so that the return loss can be increased.

[0007]

However, in the alignment method as shown in FIG. 7, it is necessary to adjust θz around the Z-axis in addition to the three-axis adjustment of the X-axis, the Y-axis, and the Z-axis. For this reason, there was a problem that work became complicated and difficult.

[0008] On the other hand, there is a method of connecting two optical fibers by fusion, but it is not possible to use different materials because the melting points are different. The present invention has been made in view of such a point, and an object of the present invention is to provide an optical fiber alignment method and an optical stage capable of easily and accurately connecting optical fibers.

[0009]

According to the present invention, there is provided an optical fiber alignment method for connecting optical fibers having end faces inclined at a predetermined angle with respect to an optical axis. At the connection end of the fiber, a holding member having a reference surface formed in advance in a predetermined direction with respect to the direction of the end surface of the optical fiber is fixed, and the optical fibers are connected to each other based on the direction of the reference surface. An optical fiber alignment method is provided.

[0010] In such an alignment method, a holding member having a reference surface oriented in a predetermined direction with respect to the direction of the end surface of the optical fiber is fixed to the connection end portion of each optical fiber, and based on the orientation of the reference surface. To connect optical fibers. This eliminates the need to adjust the direction of the optical fiber around the optical axis, which simplifies the work and enables accurate alignment.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 2A and 2B are diagrams showing a configuration of a capillary used in the alignment method of the present embodiment, wherein FIG. 2A is a perspective view, and FIG. 2B is a perspective view showing a state where an optical fiber is inserted. The capillary 10 as a holding member is made of, for example, glass, and has a substantially columnar shape as a whole. At the center of the capillary 10, a hole 11 for inserting the optical fiber 20 is formed along the axis. The connection end 21 of the optical fiber 20 is
Is inserted and fixed until the end face 22 thereof coincides with the end face 12 of the capillary 10. An adhesive is used for fixing. The optical fiber 20 used here is a single mode fiber for a wavelength of 1.31 μm.

A reference surface 13 is formed on a part of the capillary 10. The reference plane 13 is formed by cutting out a plane parallel to the optical axis. Reference plane 1
The thickness of the capillary 3 before forming the reference surface 13
Is about 0.2 mm when the diameter is 1.8 mm.

Although the capillary 10 has a columnar shape here, it is not limited to this, and may be a polygon such as a triangle, a quadrangle, or the like. When connecting the optical fiber 20 to another optical fiber using the capillary 10 having such a configuration, as shown in FIG. 3, the end face 12 and the end face 22 are cut obliquely by cutting or polishing. By this cutting, the end face 12 and the end face 22 are formed so as to be perpendicular to the reference plane 13 and inclined by an angle θ _{1 with} respect to the original plane. The end faces 12 and 22 may be formed by fixing the capillary 10 to the optical fiber 20 and then polishing both at the same time. Alternatively, the capillary 10 and the optical fiber 20 may be formed.
May be polished individually before fixing.

In this manner, by making a cut so as to incline by the angle θ ₁ , the amount of return loss at the connection surface can be increased. As the angle θ ₁ is increased, the return loss can be increased, and the angle θ ₁ may be any number of times as long as the connected optical fibers have the same angle. In this embodiment, for example, an angle theta ₁ to 12 °. The return loss at this time is 60 dB or more.

Next, a specific alignment method of the optical fiber to which the capillary 10 is attached will be described. 4A and 4B are diagrams showing a configuration of an optical stage used when aligning and connecting optical fibers. FIG.
(B) is a plan view. The optical stage 30 mainly includes a rectangular parallelepiped upper stage 31, a rectangular parallelepiped lower stage 32, and two adjusting screws 33 and 3 as fixing members.
And 4. Lower surface 3 of upper stage 31
1a and the upper surface 32a of the lower stage 32 are attached so as to be parallel to the horizontal plane. This upper stage 3
1 separates or approaches the lower stage 32 by loosening or tightening the screws 33 and 34.

On the upper side surface 32a of the lower stage 32, a V-shaped groove 32b parallel to the horizontal plane is formed. Groove 32
b is formed at a position shifted from the center of the lower stage 32. The groove 32b, as shown in FIG. (B), and is formed to be inclined by an angle theta ₁ with respect to the connection side end face 32c perpendicular line L1 (which serve Again centerline). The optical fiber 20 is inserted into such a groove 32b.
Of the capillary 10 is placed.

FIG. 1 is a view showing a state in which an optical fiber 20 to which a capillary 10 is attached is mounted on an optical stage 30, in which (A) is a front view and (B) is a plan view. When the optical fiber 20 is mounted on the optical stage 30, the capillary 10 is inserted between the upper stage 31 and the lower stage 32, and is mounted on the groove 32b of the optical stage 30 with the reference surface 13 facing upward. Place. And adjusting screw 3
By tightening 3, 34, the upper stage 31 approaches the lower stage 32 side, and clamps the capillary 10 with the groove 32b. At this time, the reference surface 1 of the capillary 10
3 is a lower surface 3 of the upper stage 31 which is parallel to the horizontal plane.
1a, the reference plane 13 is also parallel to the horizontal plane.

Further, since the groove 32b is formed to be inclined by an angle θ _{1 with} respect to a line L1 perpendicular to the end face 32c, the capillary 10 is also inclined by an angle θ _{1 with} respect to the line L1. As a result, the end face 12 of the capillary 10 becomes the end face 32
Becomes parallel to c.

FIG. 5 is a plan view showing an actual connection method using the optical stage 30. When the optical fiber 20 fixed to the optical stage 30 is connected to another optical fiber 50, the capillary 40 is also attached to the other optical fiber 50 at the end and fixed to the optical stage 60. At this time, the capillary 40 has substantially the same shape and material as the capillary 10. The optical stage 60 has the same shape and material as the optical stage 30. On the other hand, the optical fiber 20 and the optical fiber 50 are formed of mutually different materials. For example, if the optical fiber 20 is quartz glass, the optical fiber 50 is a fluoride fiber.

The capillary 40 is mounted and fixed in a groove (not shown) of the optical stage 60 with a reference surface (not shown) facing upward, similarly to fixing the capillary 10 to the optical stage 30. However, the optical stage 60 is
The capillary 40 is fixed in a state where it is inverted by 180 ° with respect to the optical stage 30.

Therefore, when the optical stage 30 and the optical stage 60 face each other such that their end faces 32c and 60a are parallel as shown in the figure, the optical fiber 20 and the optical fiber 50 are also parallel to each other. Further, from the relationship between the shapes of the optical stages 30 and 60, the capillaries 10 and
The respective end faces 12 and 41 of 40 are also parallel to each other. Therefore, when the end faces 12 and 41 are joined together, alignment around the Z axis (θz) is not required, and only the optical stages 30 and 60 need to be aligned in the three axes of X, Y, and Z axes. . This makes it possible to easily and accurately connect optical fibers.

Also, in the optical stage 30 and the like of the present embodiment, the grooves 32b are formed at the same angle θ ₁ as the end faces 12 and 22 of the capillary 10 and the optical fiber 20, so that the optical stages 30 and 60 face in parallel with each other. When they are combined, the end faces 12, 41 of the capillaries 10, 40 naturally become parallel to each other, and the work becomes easier.

The optical fiber 2 thus aligned
0,50 can be connected with an adhesive. After the connection, the adjusting screws 33, 34, 62, and 6 of each optical stage are connected.
3 and the upper stages 31 and 61 are removed, so that the optical fibers 20 and 5 are removed from the optical stages 30 and 60.
0 can be separated.

In this embodiment, the groove 32b has a V-shape, but may have any shape such as a semicircle or a square as long as the capillary 10 can be fitted therein. In the case of a quadrangle, the capillary 10 may be fitted so that the reference surface 13 of the capillary 10 contacts the side surface of the groove. At this time, if the direction of the end face 12 of the capillary 10 is the same as that in the example of FIG. 3, the end face 12 faces diagonally upward or diagonally downward. Absent. However, in this case, the groove is preferably formed in parallel with the line L1. On the other hand, end face 12
If the inclination is shifted by 90 ° from the example of FIG. 3, the orientation of each end face after attachment to the optical stage is the same as that of the examples of FIGS.

[0025]

As described above, according to the present invention, a holding member having a reference surface oriented in a predetermined direction with respect to the direction of the end surface of the optical fiber is fixed to the connection end of each optical fiber. Since the optical fibers are connected based on the direction of the optical fiber, it is not necessary to adjust the direction of the optical fiber around the optical axis.

Therefore, the work is simplified and accurate alignment can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state in which an optical fiber to which a capillary is attached is mounted on an optical stage, (A) is a front view,
(B) is a plan view.

FIGS. 2A and 2B are diagrams showing a configuration of a capillary used in the alignment method of the present embodiment, wherein FIG. 2A is a perspective view and FIG. 2B is a perspective view showing a state where an optical fiber is inserted.

FIG. 3 is a perspective view showing a state in which end faces of a capillary and an optical fiber are cut.

4A and 4B are diagrams illustrating a configuration of an optical stage used when aligning an optical fiber, wherein FIG.
(B) is a plan view.

FIG. 5 is a plan view showing an actual connection method using an optical stage.

FIG. 6 is a plan view showing a general active alignment method.

FIG. 7 is a view showing a conventional alignment method in which end faces of an optical fiber and a capillary are cut obliquely.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Capillary 11 Porous hole 12 End surface 13 Reference surface 20 Optical fiber 21 Connection end 22 End surface 30 Optical stage 31 Upper stage 31a Lower side 32 Lower side 32a Upper side 32b Groove 33, 34 Adjustment screw

Claims (7)

[Claims] An optical fiber alignment method for connecting optical fibers having end faces inclined at a predetermined angle with respect to an optical axis, wherein a connection end of each of the optical fibers has a direction of an end face of the optical fiber in advance. An optical fiber alignment method, comprising: fixing a holding member having a reference surface facing a predetermined direction, and connecting the optical fibers based on the orientation of the reference surface. 2. The optical fiber alignment method according to claim 1, wherein a reference plane of the holding member is substantially parallel to an optical axis of the optical fiber and perpendicular to an end face of the optical fiber. . 3. The method according to claim 1, wherein the connecting optical fibers are made of different materials. 4. The optical fiber alignment method according to claim 1, wherein the optical fiber is fixed to an optical stage while the reference plane is held in a fixed direction, and the connection is performed. 5. An optical fiber alignment method for connecting optical fibers, wherein a holding member having a reference surface formed in advance is fixed to a connection end of each of the optical fibers; An optical fiber alignment method, comprising: forming an inclined surface facing a predetermined direction with respect to the reference surface on an end surface; and connecting the inclined surfaces of the optical fibers based on the orientation of the reference surface. 6. An optical stage for fixing an optical fiber having an end surface inclined at a predetermined angle with respect to an optical axis for alignment, said optical stage being attached to a connection end of said optical fiber and being fixed to an end surface of said optical fiber. A first groove having a groove for holding a holding member having a reference surface facing in a predetermined direction in a fixed direction;
And a holding surface capable of holding the holding member and sandwiching the holding member between the groove and contacting a reference surface of the holding member to fix the orientation of the holding member around the optical axis. An optical stage comprising: a second stage; and a fixing member that fixes the first stage and the second stage to each other. 7. The groove according to claim 6, wherein a longitudinal direction of the groove is inclined by a predetermined angle with respect to a direction parallel to the pressing surface and perpendicular to a connection end surface of the lower stage. Optical stage as described.