JPS63108302A - Structure of connector for submarine light repeater - Google Patents

Abstract

PURPOSE:To secure watertight and airtight functions with high reliability by fitting a circuit side ferrule instead of an optical field and providing the circuit side ferrule with watertight and airtight holding functions and a connector function. CONSTITUTION:Taper parts 30, 31 having coincident shapes each other are formed in a 1st cylindrical body 25 and a through hole 20, a corn seal part 32 to be an airtight holding means is formed by these taper parts 30, 31 and both tapers 30, 31 are stuck fast to each other by screwing a press member 34 into a screw groove 33 formed around the through hole 20 and pressing the circuit side ferrule 21 to the right to secure sufficient airtightness. A gap between the press member 34 and the outer periphery of a 2nd cylindrical body 26 of the ferrule 21 is filled with a bonding agent 35 to be a watertight holding member, so that the gap is watertightly sealed. Thus, the gap can be prevented from the infiltration of sea water and the corn seal part 32 can be prevented from being corroded.

Description

[Detailed Description of the Invention] "Field of Industrial Application" This invention relates to a connector structure for connecting an optical fiber led out from a repeater circuit of a submarine optical repeater and an optical fiber of a submarine optical cable. be.

"Prior Art" Conventionally, the connection between a submarine optical cable and a repeater in a submarine optical transmission system is as shown in FIG. 4.

In Fig. 4, symbol l is a repeater circuit, and 2 is a repeater circuit l.
3 is an end plate that closes the tip of the pressure cylinder 2, 4 is an optical feedthrough that passes through the end surface 3, and 5 is an optical fiber drawn out from the repeater circuit l. , and the code 6 is a submarine optical cable,
7 is an optical fiber of the submarine optical cable 6, 8 is a cable tensioning device, and 9 is a T-'r connection part, in which the optical fiber 5 on the repeater circuit l side is guided through the optical feedthrough 4, and the T - It is connected to the optical fiber 7 on the submarine optical cable 6 side within the T connection part 9.

The symbol IO indicates the connection point.

Repeaters such as the one described above may be installed on the seabed at a depth of 8,000 m, so submarine optical cables 6
If a failure such as a disconnection occurs in the optical feedthrough 4,
Water pressure of up to 800 atmospheres may be applied to the water.

The optical feedthrough 4 is required to withstand such high water pressure and to have watertight performance to prevent seawater from entering the pressure-resistant cylinder 2. Further, even in normal times, airtight performance is required to suppress the increase in humidity within the pressure-resistant cylinder 2 over a long period of time, which causes deterioration of the characteristics of the repeater circuit 1.

"Problem to be solved by the invention" By the way, in the above case, the connection between the optical fibers 5 and 7 is T.
-1゛This must be done by thermal fusion within the connection 9, and therefore, in the case of a single mode fiber, the thickness of 1 μm
There was a problem in that it was necessary to perform the following high-precision axis alignment, and the connection work required a long time. Also, T-T
The connecting portion 9 must be capable of accommodating an extra length of optical fiber of about 1 m on both sides due to thermal fusion splicing, which poses a problem in that the repeater housing becomes large.

In view of the above circumstances, this invention makes it possible to downsize the repeater housing and shorten the connection time between a submarine optical cable and a submarine optical repeater circuit when constructing or repairing a transmission line, while also achieving low optical loss. The objective is to provide a connector structure for submarine optical repeaters that has highly reliable watertightness and airtightness.

This invention provides a temporary through hole in the end surface attached to the tip of a pressure-resistant cylinder that accommodates a circuit, and a circuit-side ferrule is attached to the through hole. The metal-coated fiber pulled out from the repeater circuit is inserted into the circuit-side ferrule, and the tip of the cable-side ferrule, into which the optical fiber of the submarine optical cable is inserted, is butted against the tip of the circuit-side ferrule. The circuit-side ferrule is configured to optically connect to the optical fiber, and the circuit-side ferrule includes a first cylindrical body disposed in the through hole and filled with solder, and a rear end of which is connected to the first cylindrical body. a second cylindrical body that is joined to the body and whose tip protrudes toward the outer surface of the through hole and whose interior is filled with an adhesive; and a metal coated fiber that is attached to the tip of the second cylindrical body. A gap between the outer circumferential surface of the circuit-side ferrule and the inner surface of the through hole is defined by an airtight retaining means and a ceramic ferrule member whose tip is terminated. It is characterized by being sealed by a watertight retaining means provided on the temporary outer surface side.

As the above-mentioned watertight maintenance means, it is possible to use an adhesive or an O-ring for sealing. The airtightness maintaining means may include pressing a tapered portion formed on the outer surface of the first cylindrical body against a tapered portion formed on the inner surface of the through hole to bring the tapered portions into close contact with each other for sealing. It is possible to do something like this.

"Function" This invention attaches a circuit-side ferrule to the end plate in place of the conventional optical feedthrough, and this circuit-side ferrule has a watertight and airtight function and a function as a connector for connecting optical fibers. It was designed to have both functions. That is, by aligning the ferrule on the submarine optical cable side with the ferrule on the circuit side installed in the through hole of the end plate, the metal coated fiber pulled out from the repeater circuit and the optical fiber of the submarine optical cable are optically connected. In addition, the 11th and 2nd ferrules constituting the circuit side ferrule are
The gaps between the inner surfaces of the eleventh and second cylinders and the metal coated fibers are sealed airtightly and watertightly by the solder and adhesive filled inside the respective cylinders, and
The gap between the outer circumferential surface of the circuit side ferrule and the inner surface of the through hole is sealed by a watertight retaining means and an airtight retaining means.
To prevent seawater from entering the pressure-resistant sealing and from increasing the temperature inside it by 19 degrees.

"Embodiment" An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

The connector structure of this embodiment is different from the conventional optical feedthrough 4 to the end plate 3 in the conventional medium-U device housing described above.
Instead, a circuit-side ferrule is attached, and this circuit-side ferrule has both the functions of maintaining watertightness and airtightness and the function of a connector for connecting optical fibers.

That is, as shown in FIG. 1, the end plate 3 has through holes 20.
is provided in the through hole 20, and a circuit side ferrule 21 is provided in the through hole 20.
is attached, and a metal coated fiber 22 drawn out from the repeater circuit 1 (see FIG. 4) is inserted into the circuit side ferrule 21.

The metal-coated fiber 22 is an optical fiber whose outer surface is coated with a metal (for example, gold) that has good wettability with a solder 28 (described later).

On the other hand, the optical fiber 7 of the submarine optical cable 6 is inserted through a cable-side ferrule 23, and by butting the tip of the cable-side ferrule 23 against the tip of the circuit-side ferrule 21 via the split sleeve 24, the metal coated fiber is inserted. 22 and the optical fiber 7 are optically connected.

Here, in addition to explaining the configuration of the circuit side ferrule 21 in detail, the circuit side ferrule 2 has the through hole 2.
0, a second cylindrical body 26 whose rear end is joined to the first cylindrical body 25 and whose tip protrudes toward the outer surface of the through hole 20; 2 cylindrical body 2
Ceramic ferrule member 2 attached to the tip of 6
7, and a metal coated fiber 22
The distal end of the ceramic ferrule member 27 is terminated at the distal end surface of the ceramic ferrule member 27. This ceramic ferrule member 27 has a through hole with the same diameter or a slightly larger diameter than the metal coated fiber 22, and has been conventionally used in land-based optical connectors such as PFlPC, and allows for highly accurate axis alignment. Second, there is a track record that interconnection of single mode fibers has sufficiently low loss.

Further, the inside of the first cylindrical body 25 is filled with solder 28, and the inside of the second cylindrical body 2G is filled with an adhesive material 29 continuous to the solder 28.
The gap between the inner surface of both cylinders 25 and 26 and the outer surface of metal coated fiber 22 is sealed watertightly and airtightly by adhesive material 29. As the adhesive material 29, it is preferable to use, for example, an epoxy-based material which has a small shrinkage rate upon curing and is immersed in mechanical properties, and is sufficiently filled into the filling hole 38 so as not to form air bubbles.

The gap between the outer circumferential surface of the circuit-side ferrule 21 configured as described above and attached to the single-layer single through hole 20 and the inner surface of the RJ communication hole 0 is double-layered by airtightness maintaining means and watertightness maintaining means. This prevents seawater from entering the pressure-resistant ring 2 (see Figure 4) through the gap, and prevents the humidity inside the pressure-resistant cylinder 2 from increasing. ing. As the above-mentioned airtightness maintaining means, a so-called cone seal, which has been applied to optical feedthrough assemblies and has a sufficient track record, has been adopted, and as the above-mentioned watertightness keeping means, an adhesive is used.

That is, the first cylindrical body 25 and the through hole 20 are respectively provided with tapered portions 30 and 31 having shapes that match each other, and these tapered portions 30 and 31 form a cone seal portion 32 as an airtight maintaining means. A presser member 34 is attached to a threaded groove 33 provided around the through hole 20.
By screwing them together and pressing the circuit-side ferrule 21 to the right in the figure, the tapered parts 30 and 31 come into close contact with each other to ensure sufficient airtightness. It looks like this.

Further, the gap between the presser member 34 and the outer peripheral surface of the second cylindrical body 26 of the circuit side ferrule 21 is sealed watertightly by being filled with an adhesive 35 as a watertight retaining means. This prevents seawater from entering the gap and prevents the cone seal portion 32 from corroding, thereby ensuring airtightness by the cone seal over a long period of time. Note that the presser member 34
Similarly, the adhesive 3 is also applied to the gap between the outer peripheral surface of the screw groove 33 and the screw groove 33.
5 is filled to prevent seawater from entering.

Constructed as described above, the through hole 20 is watertightly and airtightly connected.
As described above, the cable-side ferrule 23 is butted against the circuit-side ferrule 21 mounted on the cable via the split sleeve 24, thereby optically connecting the metal-coated fiber 22 and the optical fiber 7.

A ceramic ferrule member 36 that pairs with the ceramic ferrule member 27 is attached to the tip of the cable-side ferrule 23, and a ceramic ferrule member 36 is attached to the cable-side ferrule 23 inside the second cylindrical body 26. An adhesive material 37 similar to the adhesive material 29 is filled.

Further, the split sleeve 24 described above is similar to one that has been used in conventional optical connectors.

According to the above structure, the function of maintaining watertightness and airtightness that the optical feedthrough 4 (see FIG. The circuit side ferrule 21
As a result, connection work time can be shortened and the repeater housing can be made smaller. That is, by butting the circuit side ferrule 21 and the cable side ferrule 23 together, the metal coated fiber 22 on the circuit side
By using the ceramic ferrule members 27 and 36, it is possible to connect the optical fiber 7 on the cable side with high precision and low optical loss, and therefore it is possible to connect the optical fiber 7 on the cable side with high precision and with low optical loss, unlike when connecting by conventional heat fusion. There is no need to perform highly accurate axis alignment, and the time required for connection work can be significantly reduced. For example, conventionally it took about an hour to connect six optical fibers by thermal fusion, but by doing the above, the connection can be completed in just a few minutes. Furthermore, the T-T connection section 9 that was necessary in the past becomes unnecessary, and therefore the repeater housing can be downsized.

In addition, solder 28 and adhesive 29 are filled inside the circuit side ferrule 21, and a metal coated fiber 22 with good wettability with the solder 28 is used as the tip fiber on the circuit side.
Since the solder 28 and the adhesive 29 sufficiently ensure watertightness and airtightness inside the circuit side ferrule 21, they prevent seawater from entering the pressure cylinder 2 and humidity inside the pressure cylinder 2. This can be effectively prevented from rising. According to experiments conducted by the inventors, it has been found that the increase in optical loss during the solder sealing process is 0.01 dI3 or less on average, which is not a problem. In addition, according to another experiment by the inventors, when water pressure was applied to a sealing part made only by solder, the water pressure increased to 400 kg/kg as shown in Figure 2.
cm" or more, a significant optical loss occurs, which is thought to be caused by the microbending phenomenon of the optical fiber caused by the plastic flow of the solder, and even after the water pressure is released, the optical loss is 0.1 dB per sealing part.
It is known that a certain amount of optical loss remains (Figure 2 shows the optical loss per two sealing parts). In the above structure, such an increase in optical loss is effectively prevented by filling the adhesive 29 to prevent water pressure from being applied to the solder 28. In other words, by combining sealing with solder 28 which has perfect airtightness but poor mechanical strength, and sealing with adhesive 29 which has excellent mechanical strength but does not have a moisture permeability of zero in the long term. , highly reliable watertight and airtight functions are ensured.
゛Furthermore, the outer peripheral surface of the circuit side ferrule 21 and the through hole 2
The gap between the inner surface of the circuit side ferrule 2I and the inner surface of the circuit side ferrule 2I is doubly sealed by the cone seal part 32 as an airtightness keeping means and the adhesive 35 as a watertightness keeping means.
In addition to effectively preventing seawater from entering from the outer periphery of the
Since seawater is prevented from entering the cone seal portion 32, the cone seal portion 32 will not corrode early, and airtightness can be ensured over a long period of time.

In the above embodiment, the adhesive 35 is used as a watertight retaining means, but as shown in FIG. 3, an O-ring 40 may be attached instead of the adhesive 35 to achieve a watertight seal. In this case, the O-ring 40 is placed closer to the outer surface of the end plate 3 than the cone seal portion 32 (left side in FIG. 3).
By attaching it to the above, the same effect as in the above embodiment can be obtained.

"Effects of the Invention" As explained in detail above, according to the present invention, the cable-side ferrule is butted against the circuit-side ferrule attached to the end plate at the tip of the pressure-resistant cylinder, and a ceramic ferrule member is used. Therefore, it is possible to connect the metal-coated fiber from the circuit and the optical fiber of the cable in an extremely short time, with low optical loss, and with high precision, and it is possible to connect the metal-coated fiber from the circuit with high precision. This has the effect that the casing can be made smaller by omitting it.

In addition, by filling the inside of the circuit side ferrule with solder and adhesive, it has watertightness and airtightness functions, and the outer peripheral surface of the circuit side ferrule is also kept watertight and airtight by means of watertightness and airtightness retention means. Therefore, it is possible to effectively prevent seawater from entering the pressure cylinder and humidity from rising for a long period of time.

[Brief explanation of the drawing]

1 to 3 are diagrams showing embodiments of the present invention. Figure 1 is a cross-sectional view showing the schematic configuration of the connector structure of this embodiment, Figure 2 is a diagram showing how the optical loss increases when water pressure is applied to the hermetically sealed part made of solder, and Figure 3 is a watertight seal. FIG. 3 is a cross-sectional view showing a configuration example in which an O-ring is used as a holding means. FIG. 4 is a sectional view showing an example of the configuration of a conventional submarine optical repeater housing. l... Repeater circuit, 2... Pressure resistant cylinder, 3... End plate, 6... Submarine optical cable, 7... Optical fiber. , 20...Through hole, 21...Circuit side ferrule, 22...Metal coated fiber, 23
......Cable side ferrule, 25...
First cylindrical body, 26... Second cylindrical body, 27.
...Ceramic ferrule member, 28...
・Solder, 29...Adhesive, 30.31...
...Tapered part, 32... Cone seal part (airtight keeping means), 35... Adhesive material (watertight keeping means), 40...0 ring (watertight keeping means) ).

Claims (3)

[Claims] (1) A through hole is provided in the end plate attached to the tip of the pressure cylinder that houses the repeater circuit, a circuit side ferrule is attached to the through hole, and the metal drawn from the repeater circuit is attached to the circuit side ferrule. The metal-coated fiber and the optical fiber are optically connected by inserting the coated fiber and abutting the tip of the cable-side ferrule through which the optical fiber of the submarine optical cable is inserted with the tip of the circuit-side ferrule. None, the circuit side ferrule includes a first cylindrical body disposed in the through hole and filled with solder, and a rear end joined to the first cylindrical body and a tip end outside the through hole. a second cylindrical body protruding from the surface side and filled with an adhesive;
a ceramic ferrule member attached to the tip of the second cylindrical body and terminating the tip of the metal coated fiber, and the outer peripheral surface of the circuit side ferrule and the inner surface of the through hole. A connector structure for a submarine optical repeater, characterized in that a gap between the two is sealed by an airtightness maintaining means and a watertightness maintaining means provided closer to the outer surface of the end plate than the airtightness maintaining means. (2) The watertight maintenance means is configured to seal by filling the gap with an adhesive, and
The airtight maintaining means presses a tapered portion formed on the outer surface of the first cylindrical body against a tapered portion formed on the inner surface of the through hole, thereby bringing the tapered portions into close contact with each other for sealing. A connector structure for a submarine optical repeater according to claim 1, characterized in that the connector structure has the following structure. (3) The watertight maintaining means seals the gap with an O-ring, and the airtight maintaining means connects a tapered portion formed on the outer surface of the first cylindrical body to the inner surface of the through hole. 2. A connector structure for a submarine optical repeater according to claim 1, wherein the tapered portions are brought into close contact with each other and sealed by pressing against the tapered portions formed in the bottom.