JPH0534530A - Connecting structure for different optical fibers - Google Patents

Abstract

PURPOSE:To provide a proper connecting structure for different optical fibers without connection by welding. CONSTITUTION:The connecting ends of an optical fluoride fiber 1 and an optical quartz fiber 2 as different optical fibers are placed opposite to each other with a gap 3 in-between and a means 4 of preventing the reflection of light is set between the connecting ends of both the optical fibers 1, 2. The gap 3 avoids the contact of the fibers 1, 2 by thermal expansion and the means 4 prevents light from reflecting from one of the connecting ends and returning to the incident end.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting structure of different kinds of optical fibers for connecting different kinds of optical fibers having different components.

[0002]

2. Description of the Related Art As is well known, when an optical signal is transmitted over a long distance, signal amplification is performed on the way. In the amplification of the optical signal, the optical signal is once converted into an electric signal, the electric signal is amplified, and then the electric signal is reconverted into an optical signal for transmission. However, this signal amplification system has a problem that the device configuration is complicated and the size is increased because the optical signal is converted into an electric signal. Recently, a fluorinated optical fiber having an optical amplification function has been developed. As shown in FIG. 4, the pumping light generated by the pumping light source 13 is added to the optical signal transmitted by the silica-based optical fiber 2. Signal combiner 10
A method has been proposed in which the multiplexed optical signal is multiplexed, the multiplexed signal is passed through the fluorinated optical fiber 1 to amplify the optical signal, and the amplified optical signal is transmitted over a long distance through the silica optical fiber 2. The proposed method is epoch-making and is remarkable because it can perform signal amplification without converting an optical signal into an electric signal.

When an optical signal is amplified by using the fluorinated optical fiber 1, it is necessary to connect a fluorinated optical fiber for signal amplification to the silica optical fiber 2. For connection, it is conceivable that discharge energy is applied between connection end faces of the optical fibers, and fusion is performed by this discharge energy, similar to the connection between ordinary silica optical fibers.

[0004]

However, since different kinds of optical fibers have different compositions of optical fiber materials, they have different melting points, and it is very difficult to set conditions for providing appropriate discharge heat to both kinds of optical fibers. Even if conditions are set so that the appropriate discharge heat is given to the optical fiber, the discharge heat (fusion energy) is too large or too small for the optical fiber on the other side, and fusion splicing of different optical fibers There is a problem in that it cannot be performed effectively.

In order to avoid this difficulty in fusion splicing, it is conceivable that the connecting end faces of different types of optical fibers are butted against each other and connected in a contacting state, but then, since the hardnesses of both optical fibers are different, thermal expansion and the like occur. If the optical fibers are pressed against each other strongly, the end face of the softer optical fiber is damaged. It is also possible to connect the connection end faces of different kinds of optical fibers in a state of facing each other with a minute gap without making contact, but in such a case, the optical signal transmitted from the input side optical fiber is When entering the space, some light is reflected from the connection end face, the reflected return light returns to the office side of the communication headquarters, distorting the linearity of the laser diode etc. which is the light emitting source and increasing internal noise. , Or a new problem of causing oscillation of the optical amplifier will occur.

The present invention has been made in order to solve the above-mentioned problems, and an object thereof is to prevent the generation of scratches due to the contact between the connecting end faces and the generation of reflected return light, which is difficult. An object of the present invention is to provide a connection structure for different kinds of optical fibers that can be easily connected without setting fusion conditions.

[0007]

In order to achieve the above object, the present invention is configured as follows. That is, in the connection structure of the present invention, the connection end faces of different kinds of optical fibers having different components are arranged with a gap, and a light reflection preventing means for preventing the generation of reflected return light of an optical signal is provided between the connection end faces. It is configured by being characterized.

[0008]

In the present invention having the above-mentioned structure, since different kinds of optical fibers are arranged to face each other with a gap and a light reflection preventing means is provided between the connecting end faces, an optical signal passing through the input side optical fiber is After exiting from the optical fiber on the input side to the gap without generating reflected return light, the optical signal is transmitted by entering the different optical fiber on the output side.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a connection structure for heterogeneous optical fibers according to the present invention. In this embodiment, the connection structure of the fluorinated optical fiber 1 and the silica optical fiber 2 is shown.
This fluorinated optical fiber 1 is fluorinated mainly containing ZrF ₄ and BaF ₂ mixed with active ions of a fluorescent substance such as rare earth having a light amplification function such as Nd ³⁺ and Pr ³⁺ , or BeF ₂ . System optical fiber. The connecting end faces of the fluorinated optical fiber 1 and the silica optical fiber 2 are arranged to face each other with a gap 3 therebetween, and a light reflection preventing means 4 is provided between the connecting end faces of the optical fibers 1 and 2.

The light reflection preventing means 4 is provided from the connection end face of the input side end when the optical signal transmitted from one side (input side) of the fluoride type optical fiber 1 or the silica type optical fiber 2 goes out to the gap 3. The reflected return light is prevented from being generated, and the light reflection preventing means 4 can have various configurations. In FIG. 1A, the fluorinated optical fiber 1 and the silica optical fiber 2 are combined. A non-reflective film 5 is provided on the connection end face to serve as a light reflection preventing means 4. In FIG. 1B, lenses 6 are provided on the connection end face of the fluorinated optical fiber 1 and the connection end face of the silica optical fiber 2, respectively. To prevent light reflection.
Further, in (c) of the figure, the inclined surface 7 is formed by polishing on the connection end surface of the fluorinated optical fiber 1 and the connection end surface of the silica optical fiber 2 to form the light reflection preventing means 4. This inclined surface 7
The inclination angle of is set to an angle equal to or greater than the critical angle at which the optical signal transmitted from the optical fiber on the input side is non-reflected when exiting the gap 3. Furthermore, the one shown in (d) of FIG.
A refractive index matching agent 8 is provided between the connection end faces of the fluorinated optical fiber 1 and the silica optical fiber 2 to serve as the light reflection preventing means 4. The refractive index matching agent 8 is made of, for example, matching oil or the like, and a matching material having a refractive index slightly larger than that of the core of the optical fiber is used.

According to this embodiment, the fluorinated optical fiber 1 is
Since the silica-based optical fiber 2 and the silica-based optical fiber 2 are opposed to each other with a gap 3 therebetween, even if the optical fibers 1 and 2 are thermally expanded, the connection end faces of the optical fibers 1 and 2 may come into contact with each other and strongly press against each other. In addition, there is no problem that the softer optical fiber is damaged by the harder optical fiber. Further, when the optical signal transmitted from the optical fiber on one side goes out to the gap 3, the generation of reflected return light is prevented by the light reflection preventing means 4, so that the reflected return light returns to the station side, and the light emitting source. The problem of distorting the linearity of the laser diode or increasing internal noise can also be prevented.

Further, in the present embodiment, the fluorinated optical fiber 1 and the silica optical fiber 2 are connected by facing each other with a gap interposed therebetween, not by fusion. Difficulty can be eliminated, connection between different types of optical fibers can be performed quickly and reliably, connection work can be facilitated and efficiency improved, and connection reliability can be improved. Become.

FIG. 2 shows another embodiment of the connection structure for heterogeneous optical fibers according to the present invention. The embodiment shown in FIG. 2 is a system in which a directional coupling element, a filter element, an optical element having a non-reciprocal function, or an optical element integrating these functions is inserted in the gap between the connection end faces of the present invention. Is intended to be simplified. 2A shows an optical signal of wavelength λ ₁ added from the silica optical fiber 2a and a wavelength λ added from the silica optical fiber 2b.
Multiplexes by the multiplexer 10 and the optical signals of _two wavelengths, form the optical signal of the wavelength of lambda ₁ + lambda ₂ signal amplified using fluoride-based optical fiber 1 is shown. Also in this embodiment, the fluorinated optical fiber 1 and the silica optical fibers 2a and 2b are arranged through the gap 3, and the three optical fibers 1, 2a and 2b having the light reflection preventing means 4 are combined into a multiplexer. It is connected via 10.

2B shows a structure in which a fluorinated optical fiber 1 having a light reflection preventing means 4 and a silica optical fiber 2 are connected via a filter 11, and FIG. (C) shows a fluorinated optical fiber 1 and a silica optical fiber 2 similarly connected via an isolator 12.

Also in the splicing structure of different optical fibers shown in FIG. 2, since the fluorinated optical fiber 1 and the silica optical fibers 2, 2a and 2b are arranged with the gap 3 in between, the optical fibers are pushed in due to thermal expansion. No scratches are generated by contact. Further, there is no generation of reflected return light at the connection portion, and there is no problem of distorting the linearity of the laser diode or the like, which is a light source on the station side, or increasing internal noise. Further, there is no problem of difficulty in connection due to the difference in melting point generated at the time of fusion splicing, and it is possible to efficiently connect highly reliable dissimilar optical fibers.

FIG. 3 shows an example of an optical amplifier circuit to which the connection structure of different kinds of optical fibers of this embodiment is applied. The output end of the silica optical fiber 2a through which an optical signal is transmitted and the pumping light source 13 are shown. The output end of the silica-based optical fiber 2b to which the excitation light signal is supplied from is connected to the input end of the fluorinated optical fiber 1 via the multiplexer 10. The optical signal is amplified by passing the combined signal of the optical signal and the excitation optical signal through the fluorinated optical fiber 1. The output end of the fluorinated optical fiber 1 and the input end of the silica optical fiber 2c are connected via an isolator 12, and the optical signal amplified by the fluorinated optical fiber 1 is transmitted through the silica optical fiber 2c. It

The present invention is not limited to the above-mentioned embodiment, and various embodiments can be adopted. For example, in the above embodiment, the connection of different kinds of optical fibers has been described with the example of the fluorinated optical fiber 1 and the silica optical fibers 2, 2a, 2b and 2c, but the present invention is the fluorinated optical fiber and the silica optical fiber. The present invention is applied to the connection of heterogeneous optical fibers of any combination, such as multi-component optical fibers.

[0018]

According to the present invention, since the connecting end faces of different kinds of optical fibers are connected to each other without thermal fusion, there is no difficulty in connecting different kinds of optical fibers due to the difference in melting point.
It is possible to easily and efficiently connect different kinds of optical fibers in any combination.

Further, since a gap is provided between the connection end faces of different kinds of optical fibers to be connected, even if the optical fibers undergo thermal expansion, the connection end faces do not come into contact with each other.
This contact does not cause a problem that the softer optical fiber is pressed against the harder optical fiber and is damaged.

Further, since the light reflection preventing means is provided between the connection end faces, reflected return light is not generated from the connection end faces, and the reflected return light causes a straight line such as a laser diode which is a light source on the station side. Therefore, reliable and effective connection between different types of optical fibers can be achieved without the problems of distorting the optical properties and increasing internal noise.

[Brief description of drawings]

FIG. 1 is a constitutional explanatory view showing various aspects of a heterogeneous optical fiber connection structure according to the present invention.

FIG. 2 is an explanatory view showing other various embodiments of the heterogeneous optical fiber connection structure according to the present invention.

FIG. 3 is an explanatory diagram of an optical amplifier circuit that employs the connection structure of the present embodiment.

FIG. 4 is an explanatory diagram of an optical amplifier circuit in which different kinds of optical fibers are connected by fusion splicing.

[Explanation of symbols]

 1 Fluorinated optical fiber 2, 2a, 2b, 2c Quartz optical fiber 3 Gap 4 Light reflection prevention means

Claims (1)

Claim: What is claimed is: 1. A light reflection preventing means for preventing the generation of reflected return light of an optical signal between the connection end faces of the different kinds of optical fibers having different components, which are arranged with a gap therebetween. A connection structure for heterogeneous optical fibers provided with.