JPH09101433A - Optical repeating connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical repeating connector which prevents an optical signal from leaking at a bent part halfway on an optical transmission line. SOLUTION: The optical repeating connector 1 is interposed in the bent part halfway on the optical transmission line for optical communication by an optical fiber 10. The optical repeating connector 1 is equipped with a repeating fiber 2 and connection connectors 3 connected to both the end parts of the repeating fiber 2. The repeating fiber 2 is equipped with a high-order mode fiber part 2a which is made less in diameter tan the optical fibers 10 connected to both the end parts, tapered propagation conversion area parts 2b which are increased gradually in diameter on both the sides up to the same diameter with the optical fibers 10, low-order mode fiber parts which are extended on the large-diameter sides and equal in diameter to the optical fibers 10. The outer periphery of the high-order made fiber parts 2a and both the propagation mode conversion area parts 2b is coated with a reinforcing clad layer with a low refractive index.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical relay connector attached to a bent portion in the middle of a transmission path, for example, a space inside a wall or a side surface of a device in optical communication using an optical fiber such as an indoor optical communication network.

[0002]

2. Description of the Related Art As an indoor optical communication network, for example, as disclosed in Japanese Patent Laid-Open No. 63-257704, an optical signal is transmitted via an optical fiber wired between a central device and terminals in a building. There is a method of exchanging data.

In this system, the optical fiber is wired by utilizing the space inside the wall of the building, the space under the floor, etc., and the optical outlet is installed at a necessary portion such as the wall surface or the floor surface as the lead-out portion of the optical fiber. However, an optical plug from a central device or a terminal is detachably connected to the optical outlet.

[0004]

However, it is necessary to bend the optical fiber appropriately when wiring the optical fiber using the space inside the wall of the building, the space under the floor, or the like. Since the space in the partition has a narrow width, the bending radius of the optical fiber becomes small, which causes a problem due to leakage of an optical signal due to the bending.

In particular, an optical fiber for broadband optical communication has a small numerical aperture, and even if the transmission path is slightly bent, leakage of an optical signal is remarkable.

Therefore, an object of the present invention is to provide an optical relay connector which prevents leakage of an optical signal at a bent portion in the middle of an optical transmission path.

[0007]

A technical means for solving the above-mentioned problems is an optical relay connector interposed in a bent portion in the middle of a transmission path in optical communication by an optical fiber, and the optical relay connector comprises: A relay fiber; and connecting connectors respectively connected to both ends of the relay fiber, wherein the relay fiber has a higher-order mode fiber portion having a smaller diameter than the optical fiber connected to the both ends, and the higher-order mode fiber portion. In addition to gradually increasing the diameter on both sides of the mode fiber portion, the maximum diameter is provided with a tapered propagation mode conversion region portion having the same diameter as the optical fiber connected to the both ends. .

The relay fiber may have a structure in which low-order mode fiber portions having the same diameter as the connected optical fibers are provided on the large diameter side of the propagation mode conversion areas on both sides. .

Further, the outer periphery of the higher mode fiber portion and both propagation mode conversion regions may be coated with a cladding layer having a low refractive index.

Furthermore, the core of the relay fiber may have the same refractive index as the core of the optical fiber connected to both ends thereof.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIGS. 1 to 3, 1 is an optical relay connector, which is connected to a relay fiber 2 and both ends of the relay fiber 2. It is mainly composed of a connection connector 3 made of ABS, PBT or the like.

The relay fiber 2 is made of a GI plastic optical fiber, for example, an optical fiber having a small numerical aperture such as "Esca Giga" or "Esca Mega" manufactured by Mitsubishi Rayon Co., Ltd., which has a small numerical aperture. Centered high-order mode fiber portion 2a
And a tapered propagation mode conversion area portion 2b having a gradually increasing diameter on both sides of the high-order mode fiber portion 2a, and an extension shape on the large diameter side of each propagation mode conversion area portion 2b. It has large diameter low-order mode fiber portions 2c at both ends. Both propagation mode conversion areas 2b are formed symmetrically with each other.

Further, as shown in FIG. 3, the relay fiber 2 has a central core 5 and a clad 6 provided around the core 5 and having a refractive index slightly smaller than the refractive index of the core 5. Further, in the present embodiment, the higher-order mode fiber section 2a and each propagation mode conversion area section 2
A reinforcing clad layer 7 coated with a polymer having a refractive index smaller than that of the clad 6 such as a resin having a low refractive index is provided over the outer circumference of b.

Further, the refractive index of the core 5 of the relay fiber 2 is the same as the refractive index of the optical fiber 10 connected to both ends thereof, and the diameter of the low-order mode fiber portion 2c is the optical fiber to be connected. It has the same diameter as 10.

Then, both low-order mode fiber portions 2c of the relay fiber 2 are connected to the connection connector 3, respectively, and in this embodiment, one connection connector 3 is mounted on the wall mounting frame 12 and the wall mounting frame 12 is mounted. The frame 12 is attached to the wall surface of the wall 14.

A wall 14 is provided on the other end side of the relay fiber 2.
The transmission path is bent upward in the higher-order mode fiber portion 2a while being inserted into the inner space portion 15, and the connection connector 3 at the other end is the connection connector 3 attached to the end portion of the optical fiber 10. Is connected to a connection connector (not shown), and the end face of the low-order mode fiber portion 2c of the relay fiber 2 and the end face of the optical fiber 10 are optically coupled thereto.

A connection connector (not shown) which is connectable to the connection connector 3 mounted on the end portion of the optical fiber 10 is also connected to the connection connector 3 on the wall mounting frame 12 side, and the relay fiber 2 is connected there. Low-order mode fiber part 2
The c end surface and the end surface of the optical fiber 10 are optically coupled.

The embodiment of the present invention is configured as described above, and when an optical signal incident from the optical fiber 10 side is guided to the low-order mode fiber section 2c and reflected by the subsequent propagation mode conversion area section 2b. , Its propagation mode (angle θ1 in the traveling direction of light with respect to the optical axis L of the relay fiber 2) is forcibly converted to a higher-order propagation mode. That is, the angle θ1 in the traveling direction of light with respect to the optical axis L of the relay fiber 2 is converted to a larger angle θ2.

Then, after passing through the higher-order mode fiber portion 2a which is bent in the higher-order propagation mode and then being reflected by the other propagation-mode conversion area portion 2b subsequent thereto, the higher-order propagation mode is generated. Are forcibly reconverted to lower order propagation modes. That is, the angle θ2 in the traveling direction of the light with respect to the optical axis L of the relay fiber 2 is reconverted to the original small angle θ1.

After that, the optical signal returned to the low-order propagation mode is passed through the low-order mode fiber portion 2c to the optical fiber 10.
Will be transmitted to.

By the way, FIG. 4 shows the wavelength of light λp = 653n.
Numerical aperture NA = 0.5 using m laser diode as light source
Shows a relational data diagram between the bending radius and the light transmission rate of the plastic optical fiber with the numerical aperture NA = 0.25 and the optical transmission rate, and the plastic optical fiber with the numerical aperture NA = 0.5 corresponds to the bending. It can be seen that there is little light leakage. From this fact, the higher-order propagation mode causes less light leakage to bending than the lower-order propagation mode, and the higher-order propagation mode can also reduce the minimum bending radius effective for optical signal transmission.

Therefore, in the case of the present embodiment, since the propagation mode of the optical signal is bent in the high-order mode fiber portion 2a which is transmitted by converting the propagation mode of the optical signal into the higher-order propagation mode, Since the leakage of the optical signal can be effectively prevented and the minimum bending radius r can be made smaller, the high-order mode fiber portion 2a can also be made very short, and the reduction of the band of the optical signal in the middle of the transmission path can be effectively prevented. The low loss and wide band can be maintained, and the transmission performance can be improved.

Since the relay fiber 2 is provided with the low-order mode fiber portions 2c at both ends, the connection to the connector 3 is convenient, and the relay fiber 2 is also convenient.
Will be easy to handle.

Further, since the reinforcing clad layer 7 is provided on the outer periphery of the high-order mode fiber portion 2a and each propagation mode conversion area portion 2b, the leakage of the optical signal can be prevented more effectively, and the adhesion and shape of dust can be prevented. Can be prevented and the optical stability can be improved.

In the above embodiment, the relay fiber 2 has a structure having the low-order mode fiber portions 2c at both ends, but may have a structure without the low-order mode fiber portion 2c. Further, a structure without the clad 6 and the reinforcing clad layer 7 may be adopted.

Further, the inclination angle θ and the length S in the optical axis direction of the propagation mode conversion area 2b may be appropriately determined according to the band of the optical signal used.

Further, although the structure in which the optical relay connector 1 is arranged in the wall 14 is shown, it may be used in a portion for bending the traveling direction of an optical signal in a narrow space such as a space inside a partition or a side surface of a device. The shape and structure of the connector 3 may be appropriately determined according to the purpose, and are not limited to the shape and structure of the embodiment.

Further, the reinforcing clad layer 7 may have a structure in which an optical adhesive is applied. For example, DEFEN manufactured by Dainippon Ink and Chemicals, Inc. having a refractive index of 1.479.
There are SA and OP-48.

[0029]

As described above, according to the optical repeater connector of the present invention, the optical repeater connector includes the repeater fiber and the connection connectors respectively connected to both ends of the repeater fiber. Higher-order mode fiber portions having a smaller diameter than the optical fibers connected to both ends thereof, and gradually increasing diameters on both sides of the higher-order mode fiber portions, and the maximum diameter thereof is connected to the both end portions. It is equipped with a tapered propagation mode conversion area that has the same diameter as that of the optical fiber, and is a high-order mode fiber section that converts the propagation mode of an optical signal to a higher-order propagation mode for transmission. Since the method of bending the traveling direction of the optical signal can effectively prevent the leakage of the optical signal, and the minimum bending radius can be made smaller, the high-order mode fiber section can be made very short. Band reduction of the optical signal in the middle transmission path can be effectively prevented, it is possible to maintain low loss and wide band, there is an advantage that can be improved transmission performance.

Further, if the relay fiber has a structure in which low-order mode fiber portions having the same diameter as the optical fibers to be connected are provided on the large diameter side of the propagation mode conversion area portions on both sides, respectively. The connection to the connector is convenient, and there is an advantage that handling is easy.

Further, if the outer periphery of the high-order mode fiber portion and both propagation mode conversion area portions is coated with a clad layer having a low refractive index, leakage of optical signals can be prevented more effectively, and There is an advantage that it is possible to prevent the adhesion of dust and the influence on the change of the shape, and to improve the optical stability.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a main part of an embodiment of the present invention.

FIG. 2 is a perspective view of the same.

FIG. 3 is an explanatory view of the relay fiber.

FIG. 4 is a relational data diagram between a bending radius of a plastic optical fiber and a light transmission rate.

[Explanation of symbols]

 1 Optical Repeater Connector 2 Repeater Fiber 2a Higher Mode Fiber 2b Propagation Mode Conversion Area 2c Lower Mode Fiber 3 Connector 5 Core 6 Cladding 7 Reinforcement Cladding Layer 10 Optical Fiber

Claims (4)

[Claims] 1. An optical relay connector interposed in a bent portion in the middle of a transmission path in optical communication by an optical fiber, wherein the optical relay connector is a relay fiber and connection connectors respectively connected to both ends of the relay fiber. And a high-order mode fiber portion having a diameter smaller than that of the optical fibers connected to both ends thereof, and a diameter gradually increasing on both sides of the high-order mode fiber portion, and An optical relay connector, comprising: an optical fiber having a maximum diameter connected to both ends thereof and a tapered propagation mode conversion region portion having the same diameter. 2. The relay fiber comprises low-order mode fiber portions having the same diameter as the optical fibers to be connected, respectively on the large diameter side of the propagation mode conversion area portions on both sides. The optical relay connector according to claim 1. 3. The optical relay connector according to claim 1, wherein the outer peripheries of the high-order mode fiber portion and both propagation mode conversion area portions are coated with a clad layer having a low refractive index. 4. The optical repeater according to claim 1, 2 or 3, wherein the refractive index of the core of the relay fiber is the same as the refractive index of the cores of the optical fibers connected to both ends thereof. connector.