JPH0990172A - Connection device for optical fiber and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connection device of an optical fiber and an optical element, in which dislocation and an angle deviation hardly occurs, at the time of fixing by means of laser welding after an optical axis is adjusted. SOLUTION: A connection member 10 having an eccentric through hole 10a is freely rotatably engaged with the through hole 8a of a case member 8, and the optical element 9 is arranged in a position facing the through hole 8a. A ferrule holding member 11 having the eccentric insertion hole 1a is engaged to the through hole 10a of the connection member 10 so that it can freely rotate and it can freely move forwards and backwards. The tip part of the ferrule 13 fixing and holding the optical fiber 12 is inserted into a through hole 11a. The connection part of the three members are fixed by laser welding in a state where the optical element 9 and the optical fiber 12 are optically connected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coupling device for an optical fiber and an optical element, and more particularly to a coupling device in which the optical axes of the optical fiber and an optical semiconductor element such as a laser diode (LD) are aligned and adjusted. Regarding

[0002]

2. Description of the Related Art Placing an optical element such as a laser diode (LD) or a photodiode (PD) and an optical fiber in an optimum positional relationship with their optical axes aligned with each other is generally called coupling. It is considered to be extremely important in the configuration of communication systems, optical measuring instruments and the like.

Conventionally, the coupling of the optical fiber and the optical element has been performed by fixing the ferrule holding the optical fiber to the optical element via a fixing component and an adapter.

That is, in the conventional coupling device, FIG.
As shown in FIG. 3, a ferrule holder 3 which is a fixing component is fixed on the upper surface of a case 2 which accommodates the optical element 1, and a cylindrical shape for fixing and holding the optical fiber 4 in an insertion hole of the ferrule holder 3. Ferrule 5 is inserted and fixed.

In manufacturing such a coupling device,
After the optical axis of the optical element 1 and the optical axis of the optical fiber 4 are aligned (optical axis adjustment), the joint surface (shown by a in the figure) between the optical element case 2 and the ferrule holder 3 is fixed. Has been. Conventionally, resin-based adhesives have been used to fix the joint surfaces, but this method requires holding for a long time to ensure reliable adhesion, and production efficiency is low. The method of welding and fixing is becoming mainstream.

[0006]

However, in the method of fixing the joining surface between the case 2 and the ferrule holder 3 by laser welding, local and instantaneous explosion that occurs during laser welding, that is, abrupt melting point, occurs. The axis of the ferrule holder 3 is likely to tilt with respect to the optical element case 2 due to such expansion and generation of molten droplets and subsequent contraction accompanying solidification. Therefore, although the optical axes of the optical fiber 4 and the optical element 1 are adjusted in advance, a deviation from the optical axis adjustment position A, that is, a positional deviation Δx or an angular deviation θ occurs, as shown in FIG. was there.

Incidentally, since the mode field diameter of the single-mode optical fiber is as small as about 9.5 μm, the coupling position is specified in submicron units. When r is the vertical component of the length from the welding position to the optical axis adjustment position, the angular deviation θ means the positional deviation of rθ, and r = approximately 300 to 1000μ
Since it is as large as m, an angular deviation of 0.1 ° is 1000 × 0.1, for example.
/ 180 × π = about 1.7 μm, which is a very large displacement.

Conventionally, in order to prevent such positional displacement and angular displacement of the coupling, during laser welding, as shown by an arrow in FIG. 4, the joining surface a of the middle ferrule holder 3 is placed on the upper surface of the case 2. However, it is difficult to prevent the welded portion from being deformed or stressed because of the pressing contact between the flat surfaces. And due to the huge deformation of the welded part of the ferrule holder 3,
A phenomenon such as the deformed portion being lifted and the ferrule holder 3 tilting has occurred.

The present invention has been made in order to solve such a problem, and it is unlikely that a positional deviation or an angular deviation will occur during fixing by laser welding after adjusting the optical axis. An object is to provide a coupling device.

[0010]

In a device for coupling an optical fiber and an optical element according to the present invention, a ferrule for fixing and holding the optical fiber and a through hole into which the tip of the ferrule is inserted are provided at eccentric positions. And a through hole having an inner diameter substantially the same as the outer diameter of the first block is provided at an eccentric position, and the first block is provided in the through hole. A cylindrical second block into which the second block can be freely rotated and moved back and forth in the axial direction;
A through hole having an inner diameter substantially the same as the outer diameter of the block is coaxially provided, and the third block into which the second block is rotatably fitted is inserted into the through hole;
And an optical element disposed at a position facing the through hole of the block, the optical fiber and the optical element are aligned so as to be coupled, and the joint surface of each block is fixed. And

[0011]

In the coupling device of the present invention, the LD is provided at or near the center of the through hole of the third block which also serves as the case.
Such an optical element is arranged, and a second block, in which the through hole of itself is eccentrically provided, is rotatably fitted into the through hole, and the through hole of the second block is inserted. Since the first block having the eccentric through hole into which the ferrule for holding the optical fiber is inserted is movably inserted in the third block so that it can be rotated and moved forward and backward along the axial direction. By sliding the second block in the hole and slidingly rotating the first block in the through hole with respect to the second block, the optical axis of the optical fiber and the optical axis of the optical element are To XY
The alignment can be adjusted in the axial direction (direction perpendicular to the optical axis). At the same time or after that, the first block is moved forward or backward along the axial direction with respect to the second block, so that the light in the Z-axis direction (optical axis direction) between the optical fiber and the optical element is moved. Axis adjustment can be performed.

Further, since the first block is fitted in the through hole of the second block and the shaft of the first block is less likely to tilt with respect to the second block,
When the joining surfaces of these blocks are fixed by laser welding, the deviation from the joining position, especially the angular deviation due to the rapid expansion of the welded portion and the subsequent contraction is unlikely to occur. Further, the same applies to fixing the second block and the third block, and positional deviation and angular deviation are unlikely to occur during laser welding.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of a device for coupling an optical fiber and an optical element according to the present invention, and FIG. 2 is a longitudinal sectional view showing a main part of this embodiment.

In these drawings, reference numeral 6 denotes a disk-shaped base, on which a cylindrical through-hole 8a having a large diameter whose lower end is reduced by the step projection 7 is coaxially provided. The case member 8 is mounted and fixed. An optical element 9 such as an LD is arranged at the center of the through hole 8a of the case member 8 and mounted and fixed on the base 6. In addition, the through hole 8a of the case member 8 has an outer diameter substantially equal to the inner diameter thereof, and the through hole 10a of itself is eccentrically provided, and the cylindrical connecting member 10 is rotatably and has a lower end surface. Is fitted so as to abut the step projection 7 in the through hole 8a of the case member 8. Further, the eccentric through hole 10a of the connecting member 10 has a cylindrical ferrule holding member 11 having an outer diameter substantially equal to the inner diameter thereof and the ferrule insertion hole 11a provided eccentrically. It is fitted so that it can move back and forth in any direction. Then, the distal end portion of the ferrule 13 for coaxially fixing and holding the optical fiber 12 is inserted into the ferrule insertion hole 11a of the ferrule holding member 11 as described above.

Further, the joint portion of these three members is fixed by laser welding while the optical element 9 and the optical fiber 12 are optically coupled. That is, the coupling member 10 and then the ferrule holding member 11 are each slidably rotated with respect to the fixed case member 8 to perform the alignment of the optical axes of the optical element 9 and the optical fiber 12 in the X-Y axis directions simultaneously or. After that, the connecting member 10
On the other hand, the ferrule holding member 11 is moved forward or backward along the axial direction to perform the optical axis alignment in the Z-axis direction. With the optical axis adjusted in this way, the case member 8 and the connecting member 10 are aligned. And the joint between the connecting member 10 and the ferrule holding member 11 are respectively made of YAG.
It is welded and fixed by laser irradiation.

In the coupling device of the embodiment thus constructed, the optical element 9 and the optical fiber are rotated by moving the connecting member 10 and then the ferrule holding member 11 forward and backward in the axial direction with respect to the case member 8. 12 and the optical axis can be adjusted easily and accurately. Further, the lower part of the ferrule holding member 11 is fitted in the through hole 10a of the connecting member 10, and most of the axial direction of the connecting member 10 is fitted in the through hole 8a of the case member 8. Since the members are joined at the circumferential surface surrounding the shaft, the shaft of the inner member is less likely to tilt with respect to the members arranged on the outer side. Therefore, when laser welding the joining surfaces of these members, the deviation of the optical axis, particularly the angular deviation due to the expansion of the welded portion and the subsequent contraction is unlikely to occur.

In the above embodiment, the distance between each member is YA.
The example fixed by G laser welding was explained,
As the fixing means, welding by other laser or adhesion by an adhesive can be used.

Further, the shape of the through hole 8a of the case member 8 is not limited to the straight tube shape having the same diameter in the axial direction, and the inner peripheral surface is inclined so that the diameter decreases downward as shown in FIG. The tapered hole 14 may be used, and the connecting member 10 having the outer peripheral surface inclined at the same angle as the inclined inner peripheral surface and the through hole 10a provided eccentrically may be fitted into such a hole.

[0020]

As described above, in the coupling device of the present invention, the optical axes of the optical fiber and the optical element can be easily adjusted, and at the time of fixing by laser welding or the like after the optical axis adjustment. Positional deviation and angular deviation are unlikely to occur. Therefore, a device with high coupling efficiency and high reliability can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a coupling device of an optical fiber and an optical element according to the present invention.

FIG. 2 is a perspective sectional view showing a main part of the embodiment.

FIG. 3 is a perspective sectional view showing the shapes of a case member and a connecting member according to another embodiment of the present invention.

FIG. 4 is a perspective view showing a conventional coupling device of an optical fiber and an optical element.

FIG. 5 is a perspective view showing a state in which positional displacement and angular displacement have occurred in the conventional coupling device.

[Explanation of symbols]

 8: Case member 8a: Large-diameter through hole 9: Optical element 10: Connection member 10a: Eccentric through hole 11: Ferrule holding member 11a: Ferrule insertion hole 12 ……… Optical fiber 13 ……… Ferrule

Claims (2)

[Claims] 1. A columnar first block in which a ferrule for fixing and holding an optical fiber, a through hole into which a tip of the ferrule is inserted are provided at an eccentric position, and an outer portion of the first block. A through hole having an inner diameter substantially the same as the diameter is provided at an eccentric position, and the first block is a cylindrical first member into which the first block is freely inserted so as to be rotatable and axially retractable. The second block and a through hole having an inner diameter substantially the same as the outer diameter of the second block are coaxially provided, and the second hole is provided in the through hole.
A third block into which the block is rotatably inserted, and an optical element disposed at a position facing the through hole of the third block, so that the optical fiber and the optical element are coupled to each other. A coupling device for an optical fiber and an optical element, which is aligned and the joint surface of each block is fixed. 2. The apparatus for coupling an optical fiber and an optical element according to claim 1, wherein the joint surface of each block is fixed by laser welding.