JPH03184007A - Optical coupler for photosemiconductor device - Google Patents

Abstract

PURPOSE:To obtain the optical coupler which has small coupling loss and excellent reproducibility by making a split sleeve larger in rigidity on the fixed- ferrule side than on the ferrule side. CONSTITUTION:The fixed ferrule 4a which is fixed to the photosemicondcutor devide 1a and the movable ferrule 10a of an optical fiber with a connector are held coaxially by the split sleeve 5a and then the image formation point 3 of a light beam which is projected from the photosemiconductor 1a through the fixed ferrule 4a is aligned with the position of the core of the optical fiber 9a. In this optical coupling device, the part 16 of the split sleeve 5a on the side of the fixed ferrule 4a is made higher in rigidity than the part 17 on the side of the ferrule 10a. Consequently, unnecessary motion which may cause decentering can be suppressed without spoiling the elasticity of the split sleeve. Consequently, the optical coupler which has small coupling loss and excellent reproducibility is obtained.

Description

[Detailed Description of the Invention] Overview Regarding optical coupling devices for optical semiconductor devices used in optical communication trunk lines, etc., the purpose of this invention is to realize an optical coupling device for optical semiconductor devices with low coupling loss and good reproducibility. By holding the fixed ferrule fixed to the semiconductor device and the movable 7-ferrule of the optical fiber with a connector in the same name with a breakable sleeve, the light beam emitted from the optical semiconductor device through the inside of the fixed ferrule can be controlled. In an optical coupling device in which the imaging point is aligned with the core position of the optical fiber,
The rigidity of the portion of the breakable sleeve on the fixed ferrule side is made higher than the rigidity of the portion on the ferrule side.

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to an optical coupling device for an optical semiconductor device used in an optical communication trunk line or the like.

Local loop/LAN (local are
An optical semiconductor device for use in a network is required to have an optical coupling device and to be able to easily couple an optical fiber with a standard optical connector. On the other hand, when coupling, it is required that the coupling loss be small and its reproducibility should be good.

BACKGROUND ART (1) Overview of an optical coupling device for an optical semiconductor device FIG. 4 is a diagram for explaining an optical coupling device for an optical semiconductor device, and shows only the optical coupling device in a sectional view.

Moreover, FIG. 5 is a diagram explaining an optical fiber with a connector,
Only the connector is shown in cross section.

That is, the connector shown in FIG. 5 is inserted into the optical coupling device shown in FIG. 4, and the optical semiconductor device 1 and the optical fiber 9 are optically and mechanically coupled.

The optical coupling device of an optical semiconductor device is intended to efficiently transmit a convergent light beam 2 emitted from an optical semiconductor device 1 to an optical fiber 9.

For this purpose, it is necessary to align the imaging point 3 of the light beam 2 with the position of the core of the optical fiber 9.

Therefore, the optical semiconductor device 1 and the fixed ferrule 4 are fixed to the housing 6, and the imaging point 3 of the light beam 2 of the optical semiconductor device 1 is aligned in advance, and on the other hand, the fixed ferrule 4 and the ferrule 10 of the optical fiber are aligned. By holding the ferrules 4 and 10 in the same manner through a split sleeve 5 whose inner diameter is slightly smaller than the outer diameter of both ferrules 4 and 10, the imaging point 3 of the light beam 2 and the position of the core of the optical fiber 9 are made to coincide with each other. There is.

That is, the optical fiber with a connector is inserted into the optical coupling device of the optical semiconductor device, and the threaded portion 14 of the fastening screw 13 and the housing 6
The optical fiber ferrule 10 is inserted into the splitting sleeve 5 by fitting the threaded portion 8 of the optical fiber ferrule 10 into the splitting sleeve 5, and the optical fiber ferrule 10 pushed out by the spring 11 is positioned at the tip of the fixed ferrule 4, and the splitting sleeve 5 This is a mechanism in which the ferrules 4 and 10 are held on a concentric line by the elastic force of .

(2) Optical coupling device and cracking sleeve The cracking sleeve 5 holds the fixed ferrule 4 and the optical fiber ferrule 10 with the same name, and the imaging point 3 of the light beam 2
It plays a particularly important role in matching the position of the core of the optical fiber 9 with the position of the core of the optical fiber 9.

FIG. 6 is a perspective view illustrating the split sleeve.

The breakable sleeve 5 is made of a material such as phosphor bronze or zirconia, and has elasticity. Therefore, when a ferrule whose outer diameter is larger than the inner diameter of the split sleeve 5 is inserted into the split sleeve 5, the slit portion 15 of the split sleeve 5
opens, and a contraction force acts on the split sleeve 5. The contractile force acts as a force to hold the fixed ferrule and the optical fiber ferrule in the same name.

It is also possible to use a sleeve without slits, but such a sleeve requires extremely high precision in the inner diameter of the sleeve, and the precision of maintaining the same name between ferrules is lower than with a split sleeve. Become.

Problems to be Solved by the Invention As described above, since the split sleeve 5 has the slit portion 15, the ferrules can be held concentrically with each other with high precision. However, there are disadvantages due to the presence of the slit portion 15. That is, when a force such as bending or twisting is applied to the ferrule of the optical fiber when the ferrule of the optical fiber is inserted, the accuracy of maintaining concentricity between the ferrules decreases. As a result, the coupling loss between the optical semiconductor device and the optical fiber increases, and the coupling efficiency decreases.

FIG. 7 is a view of the fixed ferrule 4 and the optical fiber ferrule IO held concentrically by the split sleeve 5, viewed from the ferrule axial direction, and the deformation of the split sleeve 5 is exaggerated. According to experiments and observations by the inventors, the elastically deformed cracking sleeve 5 has two line segments corresponding to the slit portion, and one line segment located at a position symmetrical to these line segments with respect to the ferrule center. to 2
It has become clear that the book is in contact with the ferrule at the line segment position, and that a uniform holding force is not acting on the ferrule in the circumferential direction. Therefore, although the fixed ferrule 4 and the ferrule 10 are unlikely to be misaligned in the vertical direction in FIG. 7, they are likely to be misaligned in the lateral direction. For example, when inserting the ferrule into the split sleeve 5, if the ferrule 10 on the insertion side is inclined with respect to the fixed ferrule 4 within the A-A cross section in the figure,
When the ferrule 10 abuts the fixed ferrule 4 due to non-uniform forces acting on the split sleeve 5 in its longitudinal direction, misalignment may occur as shown in FIG. 8. Note that FIG. 8 is a cross-sectional view taken along line A-A in the case where misalignment occurs. Incidentally, for example, a misalignment of about 2 to 3 μm causes a coupling loss of about 10%.

Such a decrease in concentricity holding accuracy is particularly remarkable in the case of an optical coupling device for an optical semiconductor device in which one ferrule is fixed. In other words, in an optical coupling device that couples optical fibers, the ferrules of both optical fibers are inserted from both sides of the split sleeve and abutted against each other by a spring, so the ferrules of both optical fibers are held in a highly flexible state. This is because misalignment as explained in FIGS. 7 and 8 is less likely to occur.

The present invention was created in view of such technical problems, and an object of the present invention is to provide an optical coupling device for an optical semiconductor device with low coupling loss and good reproducibility.

Means for Solving the Problems FIG. 1 is a diagram explaining the basic principle of the present invention, in which (a) is a diagram showing a state in which a fixed ferrule and an optical fiber ferrule are held by a split sleeve, (5) is a sectional view taken along line A-A in (a). Note that (a) shows only the cracked sleeve in cross section.

The present invention is characterized in that the rigidity of the split sleeve is varied depending on the position.

That is, the fixed ferrule 4a fixed to the optical semiconductor device 1a
and a movable optical fiber ferrule 10 with a connector.
By holding the optical fibers a concentrically with the split sleeve 5a, the imaging point 3 of the light beam 2 emitted from the optical semiconductor device 1a through the inside of the fixed ferrule 4a is directed to the optical fiber 9.
In the optical coupling device aligned to the core position of a, the rigidity of the portion 16 of the split sleeve 5a on the fixed ferrule 4a side is made higher than the rigidity of the portion 17 on the ferrule 10a side.

According to the configuration of the present invention, the rigidity of the portion 16 of the split sleeve 5a on the fixed ferrule 4a side is made higher than the rigidity of the portion 17 on the ferrule 10a side, so that the split sleeve 5a is relatively higher than the fixed ferrule 4a. The ferrule 10a of the optical fiber is held firmly concentrically, and the ferrule 10a of the optical fiber is flexibly held concentrically.

Therefore, the force F exerted by the split sleeve 5a to hold the ferrule 10a and the fixed ferrule 4a concentrically is larger than the force obtained only from the rigidity of the portion 17 of the split sleeve 5a on the ferrule 10a side. As a result, the 8th
Even when misalignment as shown in the figure occurs, the misalignment is eliminated by the action of the restoring force of the relatively rigid portion 16 of the split sleeve 5a, and an undesired increase in coupling loss is prevented. Ru. Here, the reason why the rigidity of the portion 16 of the split sleeve 5a on the fixed ferrule 4a side is made relatively high is because the degree of freedom of movement of the fixed ferrule 4a within the split sleeve 5a is small.

In addition, the reason why the overall rigidity of the cracking sleeve 5a is not increased is that if the overall rigidity of the splitting sleeve 5a is increased to increase the force for holding the same name, the insertion operation of the optical fiber ferrule 10a will be facilitated. This is because there is a risk that the cracked sleeve 5a may damage the ferrule 10a of the optical fiber.

Example The present invention will be explained in detail below.

(1) Example-1 Figure 2 is a diagram explaining Example-1, in which (a) is a diagram showing a state in which a fixed ferrule and an optical fiber ferrule are held by a split sleeve, and ( A-A in a)
A cross-sectional view (C) is a diagram showing an optical coupling device of an optical semiconductor device housed in a housing. Note that (a) shows only the cracked sleeve in sectional view, and (C) shows only the optical coupling device in sectional view.

In this embodiment, another split sleeve 18 is mounted on the split sleeve 5 on the fixed ferrule 4 side.

That is, by attaching the reinforcing split sleeve 18, the apparent rigidity of the coupling split sleeve 5 on the fixed ferrule 4 side is increased.

In this case, the slit portion 15b of the reinforcing crack sleeve 18
It is desirable that the slit portion 15 of the split sleeve 5 for coupling be provided at symmetrical positions with the optical fiber 9 as the center. By doing so, it is possible to suppress unnecessary movement of both slit portions 15, 15b without impairing the original elastic force.

Further, the reinforcing crack sleeve 18 does not need to be particularly cracked as long as it can maintain the original elasticity of the joining crack sleeve 5, and may be cylindrical.

On the other hand, as shown in FIG. 2C, in the optical coupling device of this embodiment, it is only necessary to provide a stepped portion in the housing 6a for receiving the breakable sleeve 18, so that there is almost no increase in manufacturing costs.

When manufacturing the optical coupling device of this embodiment, first, the split sleeve 5 is attached to the small diameter portion of the fixed ferrule 4, and the reinforcing split sleeve 18 is attached from above, and in this state, the fixed ferrule 4 is placed inside the housing 6a. For example, fix it by press fitting. Thereafter, the optical semiconductor device 1, which has a built-in optical semiconductor element (not shown) to which the terminal 7 is electrically connected and a lens (not shown) for converging the light emitted from the element, is connected to the optical semiconductor device 1 for emitting light. The optical semiconductor device 1 is fixed to the housing 6a by laser welding, for example, by adjusting the position so that the focal point of the beam is located at the center of the small hole on the distal end surface of the fixed ferrule 4. In this way, the optical coupling device can be easily manufactured.

(2) Example-2 Figure 3 is a diagram explaining Example-2, (a) is a diagram showing a state in which the fixed ferrule and the optical fiber ferrule are held by a split sleeve, and (b) is ( A- in a)
It is an A sectional view. Note that (a) shows only the cracked sleeve in cross section.

In this embodiment, the thickness of the split sleeve 19 on the side of the fixed ferrule 4 is made thicker than the thickness on the ferrule side O of the optical fiber.

That is, since the rigidity increases as the wall thickness increases, the coaxial holding force also increases.

(3) Results Generally speaking, the variation in coupling efficiency due to attachment and detachment of the optical coupler is ±
Approximately 10% or less is required.

Of course, the conventional optical coupling device of the optical semiconductor device satisfies the above value with respect to bending, twisting, etc. of the ferrule of the optical fiber.

However, as a result of implementing Example 1, it was possible to secure performance that far exceeded the conventional device and could reproduce fluctuations in coupling efficiency within a few percent.

Effects of the Invention As described above, according to the optical coupling device for an optical semiconductor device of the present invention, by making the rigidity of the split sleeve on the fixed ferrule side higher than that on the optical fiber ferrule side, the inherent elastic force of the split sleeve is impaired. In addition, it is possible to suppress unnecessary movements that may cause misalignment.

Therefore, it is possible to realize an optical coupling device for an optical semiconductor device with low coupling loss and excellent reproducibility.

Furthermore, the present invention makes it easier to attach and detach single mode optical fibers, which has been considered particularly difficult.

[Brief Description of the Drawings] Figure 1 is a diagram explaining the basic principle of the present invention, in which (a) shows a fixed ferrule and an optical fiber ferrule held by a split sleeve, and (a) shows 2 is a diagram illustrating Example 1, and (a) is a diagram showing a state in which a fixed ferrule and an optical fiber ferrule are held by a split sleeve; ) is A-A in (a)
A cross-sectional view, (C) is a diagram showing an optical coupling device of an optical semiconductor device housed in a housing, Figure 3 is a diagram explaining Example-2, and (a) is a diagram showing a fixed ferrule and an optical fiber ferrule separated. A diagram showing the state in which it is held by a sleeve, (b) is A- in (a)
A sectional view, Figure 4 is a diagram explaining an optical coupling device of an optical semiconductor device, Figure 5 is a diagram explaining an optical fiber with a connector, Figure 6 is a perspective view explaining a cracked sleeve, and Figure 7 is a diagram explaining a cracked sleeve. FIG. 8 is a diagram illustrating deformation of the sleeve, and FIG. 8 is a diagram illustrating misalignment of the ferrule. 1.1a... Optical semiconductor device, 2... Light beam, 3... Image forming point, 4.4a... Fixed ferrule, 5.5a, 19... Crackable sleeve, 18... Reinforcement 6.6a...Housing, 7...Terminal, 8.14...Thread part, 9.9a...Optical fiber, lO...Optical fiber ferrule, 11...Spring , 2... Guide, 3... Fastening screw, 15°5a. b...Slit part, 0...Light passage hole.

Claims (1)

[Claims] 1. A fixed ferrule fixed to an optical semiconductor device (1a) (
4a) and a movable connector-attached optical fiber ferrule (10a) are held concentrically by a breakable sleeve (5a), so that the inside of the fixed ferrule (4a) can be accessed from the optical semiconductor device (1a). In an optical coupling device in which the imaging point (3) of the light beam (2) emitted through the optical fiber is aligned with the core position of the optical fiber (9a), the fixed ferrule (4a) side of the split sleeve (5a) The part (1
6) The rigidity of the part (17) on the ferrule (10a) side
1. An optical coupling device for an optical semiconductor device, characterized in that the rigidity is higher than the rigidity of the optical semiconductor device. 2. By attaching a reinforcing cracking sleeve (18) to the fixed ferrule side of the splitting sleeve, the rigidity of the part of the splitting sleeve on the fixed ferrule side is made higher than the rigidity of the part on the ferrule side. 2. The optical coupling device for an optical semiconductor device according to claim 1. 3. The optical coupling device for an optical semiconductor device according to claim 2, wherein the slit of the reinforcing breakable sleeve (18) and the slit of the breakable sleeve are provided at symmetrical positions with respect to the optical fiber. . 4. By making the wall thickness on the fixed ferrule side of the cracking sleeve thicker than the wall thickness on the ferrule side,
2. The optical coupling device for an optical semiconductor device according to claim 1, wherein the rigidity of the portion of the breakable sleeve on the fixed ferrule side is higher than the rigidity of the portion on the ferrule side.