JPS6319609A - Optical coupler - Google Patents

Abstract

PURPOSE:To improve optical coupling efficiency by composing an optical coupler of a 2nd lens fixation base, a storage member fixation cylinder, and a 2nd lens and optical fiber storage member having a penetration hollow part where the 2nd lens and an optical fiber are stored having axes aligned with each other. CONSTITUTION:An LD 23 is fixed to the base 21 through an LD fixation base 22, and then a 1st lens 24 is held by a 1st lens fixation cylinder 25, which is inserted into the opening part of a 1st lens fixation base 26 and fixed to the base 21. The 1st lens 24 is adjusted to a specific position about the optical axis and the 1st lens fixation base 26 is fixed to the base 21 finally. On the other hand, the 2nd lens 28 and optical fiber 30 are stored at specific position and fixed in the storage member 27 previously, and this storage member 27 is set opposite the base 21 across the storage member fixation cylinder 31 and storage member fixation base 32. The storage member 27 is slidable in the front-rear direction of the optical axis and its angle to the optical axis is adjustable. Consequently, the high-accuracy fitting is enabled and the optical coupling efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical coupler between a light emitting element and an optical fiber used in fields such as optical fiber communication and optical fiber data transmission.

(Conventional technology) Conventionally, as a technology in this field, IEE Journal op Quantum Electronics 7
．． (IEEE Journal of Quantum
mElectronics), QE218[4](19
82-4) (US) There was one described in P, 705-717. The configuration will be explained below using figures.

FIG. 2 is a sectional view showing an example of the configuration of a conventional optical coupler described in the above-mentioned document. This optical coupler is an example of optical coupling between a laser diode (hereinafter referred to as LD) and a single mode optical fiber (hereinafter simply referred to as optical fiber) using a compound lens system using two lenses. be.

In the figure, reference numeral 1 denotes a circular base of an optical coupler, and an LD 3 is fixed to the front surface of this base 1 via an LD fixing base 2. In front of the laser beam output end face of the LD3, there is a first lens made of a ball lens whose center is aligned with the optical axis of the laser beam.
A lens 4 is arranged, and this first lens 4 has a cylindrical first shape.
It is fixed to a lens fixing stand 5 and attached to the base 1. In front of the first lens 4, a second lens 6 made of a convergent rod lens is also fixed to a cylindrical second lens fixing base 7 along the optical axis. The fixed base 7 is attached to the base l. Further, at the optical axis position in front of the second lens 6, an optical fiber 8 is fixed to a cylindrical optical fiber fixing base 9, and this optical fiber fixing base 9 is located at the front of the second lens fixing base 7. is attached to. The base 1, the LD fixing base 2
, the first lens fixing base 5, the second lens fixing base 7, and the optical fiber fixing base 9 are mainly made of metal, and are joined together by half a day or with an adhesive or the like.

The optical coupler having the above configuration is assembled by the 5-order procedure. First, the LI 13 is attached to the front surface of the pedestal via the LD fixing base 2 so that its optical axis is perpendicular.

bA, align the center of the sphere of the first lens 4 with the optical axis of the LD 3, maintain a predetermined distance from the head D3, and attach the first lens 4 to the base 1 via the first lens fixing base 5. The second lens fixing base 7 is adjusted and fixed to the base l so that the axis of the zero-order cylindrical second lens 6 to be attached coincides with the optical axis of the LD 3. At this time, if the optical axis of the LD 3 is not perpendicular to the base l due to a mounting error with respect to the base l, or if the first lens 4 is misaligned with respect to the optical axis, the correction should be made to the In order to use two lenses 6, a second lens fixing stand 7 is installed.
is installed at an angle with respect to the base 1 by a correction angle. At this time, a gap is created between the joint surface of the base 1 and the second lens fixing table 7 according to the inclination, so fill this gap with solder or adhesive to adjust the inclination angle.
Fix both. Thereafter, the optical coupler is assembled by attaching the optical fiber fixing base 9 to the second lens fixing base 7 while adjusting the optical fiber fixing base 9 so that the tip of the optical fiber 8 coincides with the axis of the second lens 6.

In the optical coupler configured as described above, the laser light emitted from the light emitting region of the front end face of the LD 3 is refracted by the first lens 4 as shown by the dotted chain line 10 in the figure, and becomes a substantially parallel beam of light. becomes. This substantially parallel light beam enters the second lens 6, is refracted, and is focused on the tip of the optical fiber 8, thereby optically coupling the LD 3 and the optical fiber 8.

As described in the above-mentioned literature, this type of optical coupler uses lenses with relatively large apertures, so the mounting tolerance of each lens with respect to the optical axis is required for stable optical coupling. has the advantage of being relatively large. Therefore, when the angles of the optical axis of the laser beam and the axis of the second lens 6 match, the tolerance of the lateral deviation of the axis of the second lens 6 with respect to the optical axis increases, and the second If the lens 6 is within this tolerance range, the decrease in optical coupling efficiency will be small and a stable optical coupling state can be maintained.

(Problems to be Solved by the Invention) However, the optical coupler having the above configuration has the following first-order problems.

(1) When the inclination of the optical axis of the LD 3 or the deviation of the first lens 4 from the optical axis is large, the correction angle with respect to the perpendicularity of the second lens fixing table 7 to the base l becomes large in order to correct them. In this case, the gap created between the joint surface of the base l and the second lens fixing base 7 also becomes large, making it difficult to adjust the correction angle by filling with solder, adhesive, or the like. Therefore, not only the mounting accuracy deteriorates and the optical coupling efficiency decreases, but also the efficiency of the assembly process deteriorates.

(2) Attachment of the optical fiber fixing base 9 to the second lens fixing base 7 is performed by adjusting the position and angle of the axis of the optical fiber 8 while maintaining the distance between the second lens 6 and the optical fiber 8 at a predetermined dimension. Since it is difficult to maintain mounting accuracy and the work efficiency is poor.

The present invention solves the problems that the above-mentioned prior art had, such as that the correction of the angle with respect to the optical axis by the second lens 6 is limited to a small angle and the correction range is narrow, and that it is difficult to attach the optical fiber 8 with high precision. Therefore, it is an object of the present invention to provide an optical coupler that solves the problem of the possibility of poor optical coupling efficiency and poor assembly work efficiency.

(Means for Solving the Problems) In order to solve the above problems, the present invention includes a light emitting element that emits light, and a first lens that converges the emitted light from the light emitting element into a substantially parallel light beam. a second lens fixing base for fixing the lens; and a second lens fixing base for converging the emitted light that has passed through the first lens.
In an optical coupler comprising a second lens fixing base for fixing a lens, and an optical fiber fixed to the second lens fixing base and receiving the emitted light that has passed through the second lens, the second lens fixing base may be fixed to the second lens fixing base. , a holding member fixing cylinder having a through-hollow part and a sliding surface formed therein; a protruding part that can slide and freely adjust the angle in contact with the sliding surface on the outside; and the second housing member inside; The optical fiber accommodating member includes a second lens and an optical fiber accommodating member having a penetrating hollow portion for accommodating a lens and an optical fiber with their respective axes aligned.

(Function) According to the present invention, since the optical coupler is configured as described above, the second lens ψ optical fiber housing member whose protruding portion is in contact with the inner surface of the housing member fixing cylinder is connected to the second lens and the optical fiber housing member. are accurately housed on a straight line with their respective axes aligned, and the housing member is located within the housing member fixing cylinder, and functions to enable highly accurate correction in the direction of the optical axis and at any angle with respect to the optical axis. At the same time, it functions to facilitate mutual adjustment of the second lens and the optical fiber, and correction of their optical axis direction and angle with respect to the optical axis. Therefore, the above problem can be eliminated.

(Example) Fig. 1 is a sectional view of a compound lens type optical coupler showing a first example of the present invention, in which an LD is used as a light emitting element and a single mode optical fiber is used as an optical fiber. It is.

In the figure, reference numeral 21 denotes a base of the optical coupler, and an LD 23 is fixed to the front surface of the base 21 via an LD fixing base 22. In front of the laser beam output end face of LD23,
A first lens 24 made of a spherical lens whose center is aligned with the optical axis of the laser beam is arranged. This first lens 24
is housed in a first lens fixing barrel 25 for holding the first lens 24 and adjusting its position at the same time, and further, this first lens fixing barrel 25 is fixed to the base 21 via the first lens fixing base 2B. ing. In front of the first lens 24, a second lens/optical fiber accommodating member (hereinafter simply referred to as accommodating member) has a spherical outer shape on the laser light incident side and a cylindrical outer shape on the laser light output side behind it. 27 are provided. Inside this housing member 27, there is provided a hollow part having a circular cross section that passes completely in the optical axis direction, and on the laser beam incident side of this hollow part, a ball lens is formed into a cylindrical shape according to the inner diameter of the hollow part. A second lens 28 is housed, and an optical fiber 30 covered with a cylindrical ferrule 28 is housed inside the laser beam output side. The accommodating member 27 is fixed with its spherical outer surface in contact with the inner surface of the cylindrical accommodating member fixing tube 31. This housing member fixing tube 31 is fixed to a cylindrical housing member fixing base 32 at its flange portion. The base 21, the LD fixing base 22, the first lens fixing cylinder 25, the first lens fixing base 28. Accommodating member 27, ferrule 29, accommodating member fixing cylinder 31, and accommodating member fixing base 32
are mainly made of metal, and their respective connections are made with solder or an adhesive such as epoxy resin.

Next, a method of assembling the optical coupler configured as described above will be explained. First, the LD2 is connected via the LD fixing base 22.
3 to the base 21, the first lens 24 is held by the first lens fixing tube 25, and then this first lens fixing tube 2 is fixed.
5 into the opening of the first lens fixing base 2B. Next, this second lens fixing stand 28 is fixed to the base 21, but at this time, the first lens 24 is placed at a predetermined position with respect to the optical axis while keeping the opposite end of the second lens fixing cylinder 25 on the lens holding side. Adjust so that it is set. When the adjustment is completed, the first lens fixing base 2B is finally fixed to the base 21. Separately, the second lens 28 and the optical fiber 30 are previously housed and fixed at predetermined positions inside the housing member 27.Next, the housing member 27 is inserted into the housing member fixing cylinder 31 and the housing member is fixed. It is fixed to the base 21 via the stand 32. At this time, the base 21 and the housing member fixing base 32 are fixed with screws, solder, adhesive, or the like. The housing member fixing base 32 and the housing member fixing barrel 31 are moved smoothly in the plane direction through planar contact using the flange surface of the housing member fixing barrel 31 to adjust their positions. The two lenses 28 and the optical fiber 30 are attached at a predetermined position so that their axes coincide with the optical axis. Furthermore, since the housing member 27 is housed with the outer surface of its spherical portion in contact with the inner surface of the housing member fixing cylinder 31, the housing member 27 can slide in the front-rear direction of the optical axis, and at the same time can freely adjust its angle with respect to the optical axis. It can be adjusted to a predetermined position by changing to . After setting the position and angle of the accommodating member 27 in this manner and, as a result, setting the second lens 28 and the optical fiber 30 at predetermined positions and angles with respect to the optical axis, the accommodating member 27 is housed from the open end of the accommodating member fixing cylinder 31. The contact portion of the member 27 spherical portion is filled with solder, adhesive, or the like and fixed.

This embodiment has the following advantages.

(2) The housing member 27 is provided, and a cylindrical hollow part that passes through the housing member 27 is provided so that the axial center can be seen accurately. can be accommodated. Moreover, the effort of adjusting these axes can be saved.

(2) The housing member 27 has a spherical outer shape, and this spherical part is in contact with the inner surface of the housing member fixing tube 31. Therefore, the housing member 27 can be freely adjusted in the optical axis direction, and at the same time, the housing member fixing tube 31 can be adjusted freely. The second lens 2B and the optical fiber 30 can be adjusted freely in any direction and at a large angle.
can be adjusted accurately and easily with respect to the optical axis.

(2) Since the second lens is a spherical lens instead of a rod lens, the lens surface on which the laser beam enters has a certain curvature, and the ratio of reflected light from the lens surface returning to the light source is smaller than that of a flat loft lens. Therefore, the modulation characteristics of the LD are less likely to be adversely affected.

(2) Since the first lens fixing tube 25 is provided, by adjusting the end portion thereof, the second lens 28 can be easily adjusted when attached, and can be attached with high precision.

In this embodiment, as a result of having the above-mentioned advantages, the assembly accuracy of the optical coupler can be dramatically improved, so that the efficiency of optical coupling can be improved. Furthermore, since it has become easier to adjust each part during assembly, it is expected that the work efficiency and yield rate in the assembly process will be improved.

FIG. 3 is a sectional view of an optical coupler showing a second embodiment of the present invention. The main differences between this embodiment and the first embodiment are as follows:
A non-reflective film is formed on the tip surface of the optical fiber on the laser beam incident side, and a first annular lens holder for holding the first lens is provided.

That is, on the front surface of the base 41 of the optical coupler, the base 4
A protruding LD fixing base 42 that is integrated with 1 is provided,
An LD 43 is fixed to this LD fixing base 42.
A first lens 44 arranged in front of L[143 with its optical axis aligned with the first lens 44 is held by an annular first lens holder 45 and fixed to the front surface of the LD fixing base 42. A glass window 48 for airtight sealing is provided in front of the first lens 44 and is fixed to a housing member fixing base 47 . The glass window 4B and the housing member fixing base 47 form an airtight sealing structure together with the base 41, and inert gas is injected into the interior of the glass window 4B and the housing member fixing base 47 to form an airtight structure.
D43 is sealed. The distal end surface of the optical fiber 49 fixed to the housing member 48 is coated with a pyrolytic film 50 formed by vapor deposition or the like.

With the above configuration, the effect is almost the same as that of the first embodiment,
Not only is the effect obtained, but the LD is integrated with the base 41.
The simplification of the structures of the fixing base 42 and the first lens holder 45 facilitates their manufacture and installation. Also,
By providing the non-reflection [50], it is possible to increase the optical coupling efficiency and at the same time prevent the reflected light from returning to the light source and adversely affecting the modulation characteristics.

FIG. 4 is a sectional view of an optical coupler showing a third embodiment of the present invention. This embodiment differs from the second embodiment in that instead of forming an anti-reflection film on the tip end face of the optical fiber, a glass plate that has been separately subjected to an anti-reflection treatment is provided.

A glass plate 53 with anti-reflection treatment on one side is attached to the laser beam incident side end surface of the ferrule 52 for holding the optical fiber including the tip surface of the optical fiber 51 with the anti-reflection treatment surface facing outward. It is being As the adhesive, an optical adhesive or the like having a refractive index approximately the same as that of the optical fiber is used.

With this configuration, almost the same functions and effects as in the second embodiment can be obtained, and at the same time, the glass can be treated with anti-reflection treatment using a simpler process than forming an anti-reflection film on the tip surface of the optical fiber 51. A plate 53 can be provided.

FIG. 5 is a sectional view of an optical coupler showing a fourth embodiment of the present invention. This embodiment differs from the first embodiment in that the second
A gear-shaped protrusion is provided on the cylindrical outer periphery of the lens φ optical fiber housing member, and a receiving portion that engages with the gear-shaped protrusion is provided on the inner surface of the housing member fixing cylinder. FIG. 6 shows a front cross-section (A) of the gear-shaped protrusion and a front cross-section (B) of the receiver.

A gear-shaped protrusion 62 is provided concentrically on the cylindrical outer circumference of the housing member 61, and a groove is carved on the inner surface of the housing member fixing cylinder 63 to engage with the gear-shaped protrusion 82. A portion 64 is provided. The gear-shaped protrusion 82 and the receiving part 84 are arranged so that the gear-shaped protrusion 62 is fixed to the housing member fixing cylinder B3.
The housing member 81 is inserted into the light source side along the optical axis from the open end of the housing member 81, so that they interlock with each other, and there is a slight play in the interlocking portion of the two to enable the angle adjustment of the housing member 81 with respect to the optical axis. It is a provision.

With the above configuration, the effect is almost the same as that of the first embodiment,
At the same time, the effect can be expected, and at the same time, the contact area between the housing member 81 and the housing member fixing cylinder 63 is larger than in the first embodiment, and the rotational direction with respect to the axis is restrained.
If this part is fixed with solder, adhesive, etc., there is an advantage that a stronger joint strength can be obtained.

Note that the present invention is not limited to the illustrated embodiment, and can be modified in various ways, such as the following modifications.

■ In the first to fourth embodiments, L is used as a light emitting element.
D. Although a single mode optical fiber is used as the optical fiber, the present invention is not limited to this. For example, a light emitting diode or a multimode optical fiber may be used.

(2) The accommodating member fixing tube and the accommodating member fixing base in the first to fourth embodiments may not be constructed separately, but may be integrally constructed.

■ The housing member has a cylindrical outer part with a spherical or gear-shaped protrusion, but is not limited to this. For example, instead of a spherical protrusion, a concentric disk-shaped protrusion may be provided. , the portion in contact with the inner surface of the housing member fixing cylinder may have a curvature. Further, the shape and number of teeth of the gear-shaped protrusion may be changed, and the shape of the receiving portion on the inner surface of the housing member fixing cylinder may be changed accordingly.

■ Although the optical fiber is attached to the hollow part of the housing member through the ferrule, the present invention is not limited to this.
For example, the portion corresponding to the ferrule may be formed into an integral structure and provided in the hollow portion of the housing member.

(2) The second lens is not limited to a ball lens, and may be a rod lens, for example.

(Effects of the Invention) As described in detail above, according to the present invention, the housing member fixing tube that constitutes a part of the fixing member of the optical coupler slides in contact with the inner surface of the housing member fixing tube. Since the second lens and the optical fiber accommodating member are provided that can change the angle with respect to the optical axis, the correction range of the angle of the second lens with respect to the optical axis is widened, and at the same time, it is possible to attach the second lens and the optical fiber with high precision. As a result, the optical coupling efficiency can be increased. Furthermore, since the attachment of the second lens and the optical fiber facilitates time adjustment and correction, it is expected that the efficiency of assembling the optical coupler will be improved.

[Brief explanation of the drawing]

FIG. 1 shows an optical coupler showing a first embodiment of the present invention. Figure, no. Figure, t=come. Light result. - Configuration example. 3 is a sectional view of an optical coupler showing a second embodiment of the invention, FIG. 4 is a sectional view of an optical coupler showing a third embodiment of the invention, and FIG. 5 is a sectional view of an optical coupler showing a third embodiment of the invention. A sectional view of an optical coupling element according to a fourth embodiment of the present invention, and FIG. 6 is a partial sectional view of FIG. 5, showing the cross-sectional shape of the gear-like protrusion and the receiver. 21.41...base, 22.42...
・LD fixing stand, 23.43... Laser diode (LD), 24.44... First lens, 25
......First lens fixing barrel, 26...First
Lens fixing stand, 27, 48. 81... Second lens e optical fiber housing member, 28... Second lens, 29.52... Ferrule, 30, 49.
51...Optical fiber, 31.83...
Accommodating member fixing tube, 32.47... Accommodating member fixing base, 45... First lens holder, 48...
...Glass window, 50...Non-reflective film, 53...
... Glass plate, 62 ... Gear-shaped protrusion, 64
・・・・・・Uke is part. Applicant's representative Yasushi Kakinoki Figure 2: Cross-sectional view of a conventional optical coupler Figure 3: Cross-sectional view of another optical coupler of the present invention Figure 3: Cross-sectional view of another optical coupler of Honkai Tatsuki Figure 4: Other optical coupler of the present invention Optical coupler sectional view Fig. 5 Partial sectional view of Fig. 5 and Fig. 6

Claims (1)

[Scope of Claims] A first lens that fixes a light emitting element that emits light and a first lens that converges the light emitted from the light emitting element into a substantially parallel light beam.
a lens fixing table; a second lens fixing table fixing a second lens that focuses the emitted light that has passed through the first lens;
The optical coupler includes an optical fiber fixed to the second lens fixing base and receiving the output light that has passed through the second lens, the second lens fixing base having a through-hole and sliding into the interior thereof. It has a housing member fixing cylinder on which a moving surface is formed, a protrusion on the outside that can slide and adjust the angle in contact with the sliding surface, and has the second lens and the optical fiber on the inside so that their respective axes are aligned. a second hole having a through-hole for accommodating the second
An optical coupler comprising a lens and an optical fiber housing member.