JPS63149610A - Optical tapping device - Google Patents

Abstract

PURPOSE:To accurately set up the relative position relation of respective optical paths to an optical fiber and to suppress a loss the to branching and coupling a its minimum by forming an optical fiber holding means and a positioning means for a light branching device and a light coupling line on a base and setting up the bend angle of the fiber and a radius at a bent part respectively to prescribed values. CONSTITUTION:A 1st groove 3 to be a holding means for a optical fiber is formed on the upper face of the base 1 of an optical tapping device and a 2nd groove 5 is formed as a positioning means for the light branching means 4. The groove 3 is formed as a U-shaped groove continued along the light incident side straight part 21 of the optical fiber 2, a light projection side straight part 22 and a bent part 23. The angle theta of bend and the radius R of bend are applied to the optical fiber at the bent part 23 and the 2nd groove 5 is formed on an extended line of the straight part 21. A convergent rod lens forming a part of the means 4 is positioned by the 2nd groove 5.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical tap device that transmits and receives optical signals to and from an optical fiber.

[Conventional technology]

An optical branch/coupler (hereinafter referred to as an optical coupler) is an important component constituting an optical local area network (optical LAN), optical transmission line, etc.

Conventionally, this type of optical coupler is used by cutting an optical waveguide or optical fiber and inserting and connecting it into the cut portion. Therefore, connection loss occurs in the trunk optical fiber or the like due to the insertion of the optical coupler. Further, there are drawbacks such as difficulty in disconnecting the trunk line and subsequent connection of the optical coupler.

In response to this, a device called an optical tap device has been proposed. An optical tap device is an optical coupler that can send and receive optical signals to and from optical fibers without cutting them.
This example is also shown in IEICE technical research report 0QE-86-104.

According to this, an optical tap device is composed of an optical fiber bent at a predetermined bending angle and bending radius, and an optical branching path and an optical coupling path that are connected to the bent portion of the optical fiber via a bonding material. .

In such an optical tap device, an optical signal of an optical fiber is emitted from a bent portion to a bonding material and received by an optical branch path. Alternatively, the optical signal in the optical coupling path is optically coupled to the bent portion of the optical fiber via a bonding material. As a result, the optical tap device does not suffer from connection loss unlike conventional optical couplers. Another feature is that an optical tap device can be attached without cutting the existing optical fiber.

[Problem that the invention seeks to solve]

However, in the conventional optical tap device described above, it is difficult to set the bending angle and bending radius of the optical fiber to predetermined values. Therefore, bending loss caused by bending the optical fiber cannot be minimized. Furthermore, with conventional optical tap devices, it is difficult to position and stably hold the optical fiber. Therefore, it is not possible to arrange an optical branch path or an optical coupling path while maintaining a predetermined positional relationship with respect to the bent portion of the optical fiber.

As a result, conventional optical tap devices cannot perform optical coupling with optical fibers or optical branching with low loss, and many of the above-mentioned features of optical tap devices are rarely utilized.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical tap device that can perform optical coupling and branching with an optical fiber with high efficiency and can be easily connected to an optical fiber.

(Means for Solving the Problems) The optical tap device according to the first invention includes an optical fiber holding means for bending and holding the optical fiber at a predetermined bending angle and bending radius, and The optical branching path positioning means for positioning the optical branching path means on or near the tangent line along the light traveling direction at the incident side bending portion is arranged to position the optical branching path means.

The optical tap device according to the second invention includes the optical fiber holding means as described above, and an optical branching path means on or near a tangent along the opposite direction of the light traveling direction at the bent portion on the light output side of the optical fiber. The optical branch path positioning means for positioning the optical branch path is disposed on the base body.

[Effect]

According to the first invention, since the optical tap device is configured as described above, the optical fiber holding means bends the optical fiber at a predetermined bending angle and bending radius and restrains the optical fiber to the base body, and the optical fiber is fixed at a constant angle. The optical branch positioning means works to transmit an optical signal due to the bending loss of the optical fiber and radiate a part of the optical signal from the bent part, and the optical branching path positioning means moves the optical branching means to the direction in which the light travels at the bending part on the light incidence side of the optical fiber. The optical branch means receives a part of the optical signal emitted from the bent part of the optical fiber and branches the optical signal, and the base body The function is to maintain a stable relative positional relationship between the optical branching path means and the optical branching path means.

According to the second invention, since the optical tap device is configured as described above, the optical fiber retaining means bends the optical fiber in a predetermined state and retains it on the base body, so that the optical fiber is bent at a predetermined bending angle. The optical coupling path positioning means forms a bending radius to facilitate optical coupling, and the optical coupling path positioning means positions the optical coupling path on a tangent along the opposite direction of the light traveling direction at the bent portion on the light output side of the optical fiber or The base body stabilizes the relative positional relationship between the optical fiber and the optical coupling path means. It acts to maintain the

(Embodiments) Hereinafter, some embodiments of the present invention will be described with reference to FIGS. 1 to 6 of the accompanying drawings. In the description of the drawings below, the same elements are denoted by the same reference numerals. , avoiding duplication and duplication of explanations.

FIG. 1 is a perspective view showing the structure of a first embodiment of the present invention. As shown in the figure, a first groove 3 is formed on the upper surface of the base 1 as a holding means for the optical fiber 2, and a second groove 5 is formed as a positioning means for the optical branching means 4. The material used for the base body 1 is acrylic resin (PMMA), which is easy to mold and whose refractive index is higher than the refractive index of the coating of the optical fiber 2 .

The first groove 3 is formed between a straight part 21 on the light input side (indicated by the optical axis A-A' in FIG. 1) of the optical fiber 2 and a straight part 21 on the light output side (indicated by the optical axis B-- Indicated by B')22
A U-shaped groove is continuously formed on the base body 1 along the curved portion 23 and the curved portion 23 . Then, at the bending portion 23, the optical fiber 2 is bent at a bending angle θ and a bending radius R, and the optical fiber 2 is bent within a plane (bending plane) parallel to the upper surface of the base 1.
is bent. The groove width of the first groove 3 is approximately 10 μm wider than the outer diameter of the optical fiber 2, and the groove depth is such that the optical fiber 2 can be buried therein. A curved surface with a radius equal to 1/2 of the groove width is formed at the bottom of the groove, and as described above, a curved surface with a radius of 1/2 of the groove width is formed.
It has a letter-shaped cross section.

The second groove 5 is the straight part (A-A') on the light incidence side of the first groove 3.
>21.

The second groove 5 has a V-shaped cross section and is formed to be placed with a focusing rod lens (optical axis c-c'>4) serving as an optical branching path means.

FIG. 2 is a sectional view showing the first groove 3, the second groove 5, and the positional relationship between the optical fiber 2 and the focusing rod lens 4, which are positioned by these grooves.

As shown in the figure, grooves 3 and 5 are formed at the same position on the upper surface of the base 1 so that the positions of these optical axes coincide with each other.

Next, the operation of the optical tap device according to the first embodiment will be explained.

The optical fiber 2 is bent according to the bending angle θ and the bending radius R that are necessarily formed in the first groove 3, and is positioned along the bottom surface of the groove 3 and secured to the base body 1. For this reason,
A part of the optical signal that enters the input side straight part (A-A'> 21) of the optical fiber 2 is radiated from the bent part 23 to the base 1,
The remaining optical signal is sent out to the outside through the output side straight section (B-8') 22 while being accompanied by a certain bending loss.

The light emitted from the bent part 23 to the base 1 is incident on a focusing rod lens (light @C-C'>4) positioned on the extension line of the two straight parts, and is sent to an optical tap as an optical branch signal. Supplied externally from the device.

As described above, according to the first embodiment, the base body 1 can be formed into a flat plate shape, so that it is easy to manufacture.

In addition, when attaching an optical tap device to the optical fiber,
Since it is only necessary to bend the optical fiber 2 in a plane (bending plane) parallel to the upper surface of the base 1, the work is simple, such as when an optical tap device is retrofitted to an existing optical fiber.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 3 is a top view showing the structure of this embodiment.

This differs from the configuration of the first embodiment shown in FIG. A second groove 5 for positioning the optical coupling path means 6 and a third groove 7 for positioning the optical coupling path means 6 are formed.

The third groove 7 is located at the straight part (B-8') on the light output side of the optical fiber 2.
) 22 on the base 1 in a direction opposite to the light traveling direction, and has a V-shaped cross section.

Then, a focusing rod lens (optical axis DD') 6 as an optical coupling path means is positioned and placed.

Optical axis D of the focusing rod lens 6 placed in the third groove 7
-D' is positioned at a predetermined angle δ with respect to the optical axis B-8' of the output-side straight portion 22 of the optical fiber 2 held in the first groove 3. Further, the cross-sectional position of the third groove 7 on the base body 1 and the positional relationship of the focusing rod lens 6 placed thereon are the same as the relationship of the second groove 5 with respect to the first groove 3 shown in FIG. is the same as

In the example shown in FIG. 3, the optical fiber 2 has a core diameter of 100 μm, a cladding diameter of 140 μm, and a coating diameter of 2.
50 μm silica step index optical fiber (
A NA value of 0.30> is used, and the bent portion 2 of the optical fiber 2
3, the angle θ is set to 30' and the radius R is set to 7.5 m. Further, the angle δ between the focusing rod lens 6 placed in the third groove 7 and the straight portion 22 of the optical fiber 2 is set to 8°. Note that this angle δ depends on the bending shape of the optical fiber 2 at the bent portion 23 and the refractive index of the base 1, and is set to an optimal value depending on each. Furthermore, the outer diameter and the like of the optical fiber 2 can also be set to optimal values.

The focusing rod lens 4 as an optical branching path means and the focusing rod lens 6 as an optical coupling path means include optical fibers 41.6' of the same type as the optical fiber 2 laid in the first groove 3.
l are connected respectively. The focusing rod lenses 4 and 6 and the optical fiber 2 are fixed with resin having a refractive index close to that of the base 1.

Next, the operation of the optical tap device according to the second embodiment will be explained.

The light emitted from the bent portion 23 of the optical fiber 2 to the base 1 enters the focusing rod lens 4, and is supplied to the outside as an optical branch signal. Further, the light incident on the base 1 from the optical fiber 61 via the converging rod lens 6 is optically coupled from the base 1 to the bent portion 23 of the optical fiber 2. In this way, optical signals are transmitted and received to and from the optical fiber 2 via these converging rod lenses 4 and 6.

In order to confirm the effectiveness of this second embodiment, the inventor
The following experiment was conducted. That is, the bending loss occurring in the optical fiber 2 is set to O,'ldB, which is an extremely small value compared to the connection loss of a conventional optical coupler.

The optical branching characteristics obtained in this way will be explained as follows. That is, the NA value of the light beam radiated from the bent portion 23 to the base 1 is approximately 0.2, which is smaller than the NA value of 0.30 of the optical fiber 2, so the light branched from the optical fiber 2 has a convergence property. It is efficiently focused by the rod lens 4. The ratio between the amount of light emitted from the optical fiber 2 and the amount of light branched at the optical fiber 41 is approximately 85%. This value is approximately equal to the best value for conventional optical couplers.

Next, the optical coupling characteristics will be explained as follows. That is, the light introduced into the optical fiber 61 and emitted toward the optical fiber 2 through the focusing rod lens 6 as an optical coupling path has an NA value of 0.0.
Optimal optical coupling was achieved in the case of 5. As a result, the optical coupling efficiency reached approximately 85%, which was found to be significantly more efficient than that of conventional optical couplers, which had an optical coupling efficiency of approximately 40%. .

Next, a third embodiment of the present invention will be described with reference to FIG.

FIG. 4 is a perspective view showing the structure of this embodiment.

This differs from the first embodiment shown in FIG. The second groove 51 serving as a positioning means for the optical branching path means 4 has a V-shaped cross section and
It is located at the point formed on the back side of the .

According to the configuration of this third embodiment, the optical fiber 2 is bent in the depth direction inside the groove 31 perpendicular to the upper surface of the base 11. Therefore, the bent portion of the optical fiber 2 is almost completely covered by the base 1.
1 and is fully mechanically protected. Incidentally, it is also possible to bend the optical fiber 2 along the bottom surface of the groove 31 by separately preparing a top cover that fits into the groove 31.

Next, a fourth embodiment will be described with reference to FIG.

FIG. 5 is a perspective view showing the configuration of this embodiment.

This differs from the third embodiment shown in FIG.
and a second base body 13, in which a V-shaped groove 32 for positioning the optical fiber 2 is formed in the base body 13.

According to the configuration of this fourth embodiment, since the optical fiber 2 is bent while being sandwiched between the base bodies 12 and 13, there is an effect that the optical tap device can be easily attached to the optical fiber 2. .

FIG. 6 is a perspective view showing the structure of a fifth embodiment that is an improvement on the embodiment shown in FIG. This differs from the fifth embodiment in that an elastic sheet member 14 as a third base is further inserted between the bases 12 and 13. The elastic sheet member 14 is made of an elastic material such as silicone resin, and has an optical fiber 2 on its negative side.
A groove 33 for positioning is provided.

According to this fifth embodiment, the optical fiber 2 is held softly by the elastic sheet member 14, and the base body 12
．． 13, it is possible to prevent excessive stress from being applied to the optical fiber when the optical fiber is assembled into the optical tap device. Further, since the base bodies 12 and 13 do not require grooves, there is an advantage that the base bodies can be manufactured easily.

The present invention is not limited to the above, and various modifications are possible.

In the description of the embodiments, the optical fiber holding means and the positioning means for each optical path are described as grooves, but the present invention is not limited to such grooves. For example, a step or a protrusion guide that can position and hold an optical fiber or a focusing rod lens may be used.

Further, in the description of the above embodiments, the material of the base was described as acrylic resin (PMMA), but the material is not limited to this. For example, it may be made of polystyrene resin, polycarbonate resin, epoxy resin, or glass. Further, the above-mentioned base body can be formed of a light-transmitting material having a refractive index greater than the refractive index of the coating of the optical fiber.

Furthermore, we assumed that the optical coupling path and the optical branching path were constituted by a condensing rod lens and an optical fiber connected to it.
It is not limited to this. For example, a light receiving element or a light emitting element can be used instead of an optical fiber, and a photoelectric conversion output can be directly obtained in an optical tap device, or an optical fiber can be used to perform optical coupling according to an electric signal.

〔Effect of the invention〕

As described above in detail, according to the present invention, the optical fiber holding means and the positioning means for the optical branching path and the optical coupling path are disposed on the base body, and the bending angle of the optical fiber is set to a predetermined angle. Since the radius of curvature at the bent portion is set to a predetermined value, the relative positional relationship of each optical path to the optical fiber can be accurately set. by this,
It is possible to minimize the bending loss of the optical fiber, as well as the loss associated with coupling loss and branching, and to stably and highly efficiently transmit and receive optical signals to and from the optical fiber without causing connection loss. I can do it.

Further, according to the present invention, there is an advantage that when an optical tap device is attached to an optical transmission line, the work can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the configuration of an optical tap device according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view showing the groove shape of the first embodiment, and FIG. FIG. 4 is a top view showing the configuration of the optical tap device according to the third embodiment, FIG. 5 is a perspective view showing the configuration of the optical tap device according to the fourth embodiment, and FIG. FIG. 6 is a perspective view showing the configuration of an optical tap device according to a fifth embodiment. 1.11, 12, 13, 14... Base body, 2... Optical fiber, 3, 31, 32. 33... First groove, 4...
・Optical branching path means (focusing rod lens), 5.51...
- Second groove, 6... Optical branching path means (focusing rod lens), 7... Third groove. Patent Applicant Sumitomo Electric Industries Co., Ltd. Applicant Agent Yoshiki Hase Figure 4 Figure 6

Claims (1)

[Claims] 1. A base body; an optical fiber formed on the base body and extending from a light input side to a light output side is bent at a predetermined bending angle and bending radius;
an optical fiber holding means for holding the base; and a light beam formed on the base for positioning the optical branching path on or near a tangent along the light traveling direction at a bent portion on the light incidence side of the optical fiber. An optical tap device comprising branch path positioning means. 2. The optical tap device according to claim 1, wherein the optical branching path positioning means positions a focusing rod lens forming a part of the optical branching path means. 3. A base body, and an optical fiber formed on the base body and extending from the light input side to the light output side, which is bent at a predetermined bending angle and bending radius,
an optical fiber holding means for holding onto the base body; and an optical coupling path means formed on the base body on or near a tangent along a direction opposite to the light traveling direction at a bent portion on the light output side of the optical fiber. An optical tap device comprising an optical coupling path positioning means for positioning. 4. The optical coupling path positioning means positions the optical coupling path means at a predetermined angle with respect to a tangent along a direction opposite to the light traveling direction at the bent portion on the light output side of the optical fiber. The optical tap device according to item 3. 5. The optical tap device according to claim 3 or 4, wherein the optical coupling path positioning means positions a focusing rod lens forming a part of the optical coupling path means.