JPH0797165B2 - Lens connector type feedthrough - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention provides an optical fiber connecting function for facilitating connection and replacement of a submarine optical fiber cable in an optical fiber introducing portion of a submarine optical repeater housing. The present invention relates to a lens connector type feedthrough having excellent pressure resistance, airtightness, and heat resistance.

(2) Conventional Technology and Its Problems FIG. 1 shows an example of the configuration of a repeater of the submarine optical cable transmission system. 1 is a submarine optical cable, 2 is a T-T connection part, 3 is an optical feedthrough, 4 is a repeater circuit, 5 is an end face plate, 6 is a pressure-resistant housing, 7 is an optical fiber, 8 is an optical fiber fusion splicing part,
9 is a cable retractor.

The repeater may be laid on the seabed as long as 8000m, and the optical feedthrough 3 withstands water pressure up to 800 atm and has excellent airtightness to keep the humidity inside the pressure-resistant housing 6 low. Sex is required. The optical feedthrough 3 in FIG. 1 withstands water pressure and only introduces the optical fiber 7 into the pressure-resistant housing 6 while maintaining airtightness. The TT connector 2 for connecting and housing the optical fiber on the optical cable side and the optical fiber on the repeater circuit side is required. Therefore, as the size of the repeater housing increases, the connection between the optical fiber on the side of the submarine optical cable and the optical fiber on the repeater circuit side in the T-T connection portion 2 is highly accurate to 1 μm or less for a single mode optical fiber. Since the connection is made by heat fusion with the optical axis alignment, there is a drawback that it takes a long time.

The lens connector type feedthrough solves these drawbacks, and as a related art slightly related to this,
For the purpose of downsizing the repeater, etc., there are conventional feedsuls (for example, Japanese Patent Application No. 53-100872, Japanese Patent Application No. 53-36583, and Japanese Patent Application No. 115
No. 113), but its manufacture requires high precision in the connection between the lens and the optical fiber, and it takes a long time in the factory. Therefore, it is impossible to connect the cable and the repeater on board this part when repairing the cable trouble. Furthermore, none of these conventional examples specifically discloses a watertight or airtight structure that can be used for up to 25 years under a severe seabed environment at a maximum pressure of 800 atm. Or the idea of "contacting" is only shown abstractly.

(3) Object of the Invention The object of the present invention is to provide a connecting function by using a rod lens, thereby making it possible to downsize the repeater housing, shorten the connecting time, and relax the machining accuracy around the connecting portion. To provide a highly reliable lens connector type feedthrough.

(4) Configuration of the Invention (4-1) Difference between Features of the Invention and Conventional Technology In the present invention, a rod lens type connector is mounted on an end face plate portion (mainly beryllium copper alloy is mainstream) of a submarine optical repeater housing. When constructing a lens connector type feedthrough having a connection function with good workability, a ceramic component is interposed between the rod lens and the end plate to securely attach the rod lens to the end plate, and the rod lens and the ceramic component are inserted. The most important feature is that the gap between the two is sealed with solder for glass / ceramic bonding.

In order to mount a small-diameter rod lens made of glass-based material directly on the end plate, which is mainly made of beryllium copper alloy, while maintaining water-tightness and air-tightness, there is a large difference in the coefficient of thermal expansion between both materials. There is a problem because the rod lens has a small diameter of usually φ1 mm to φ2 mm.

According to the present invention, such a problem is solved by first securely mounting the rod lens on the ceramic component and then mounting it again on the metal of the end face plate. here,
There are the following two configuration examples of the mounting structure of the ceramic component and the end plate metal.

That is, first, a ceramic material whose coefficient of thermal expansion has an intermediate value of the coefficient of thermal expansion of each of the rod lens and the end plate metal is selected, and a configuration example in which the end plate is soldered, secondly, This is a configuration example in which a ceramic material having a coefficient of thermal expansion extremely close to that of a rod lens is selected and a metal C ring is mounted between the ceramic component and the end face plate.

In contrast to these techniques, the conventional feedthrough using a lens does not have a connecting function, and there is no concrete example of a method for hermetically attaching the lens.

(4-2) Example FIG. 2 is a view for explaining the first basic structure of the present invention, in which 10 is a rod lens A, 11 is a rod lens B, 12 is a ceramic part A, and 13 is a ceramic part B. , 14 is a metal coat, 15 is a guide, 16 is glass / ceramic solder, 17
Is an O-ring, 18 is a ceramic pipe, 19 is an adhesive A,
Reference numeral 21 is an optical fiber A, 22 is an optical fiber B, and 23 is a solder sealing portion.

In this basic structure, a material having a coefficient of thermal expansion intermediate between that of the rod lens and the end face plate metal is selected as the material of the ceramic component A12, and the end face plate is soldered.

FIG. 3 shows the range of expansion coefficient of each material.

The lens connector type feedthrough shown in FIG. 2 is normally located in a pressure resistant structure made of metal or the like and is not subject to water pressure, but may be subject to water pressure due to water intrusion due to cable breakage or the like. In FIG. 2, the left side of the end plate 5 is the high pressure side and the right side is the low pressure side.

The manufacturing method will be described below in the order of steps.

First, on the repeater circuit side, on one end surface of the rod lens A10, one end of a ceramic pipe 18 having an outer diameter smaller than the outer diameter of the rod lens A10 and an inner diameter larger than the outer diameter of the optical fiber A21 is bonded with an adhesive A19. Stick to it.

To bond the rod lens A10 and the ceramic component A12 with the glass / ceramic bonding solder 16, for example, immerse the sealing part in the molten glass / ceramic bonding solder 16 and apply ultrasonic vibration to seal it so that air bubbles do not intervene. It is possible to wear it. At this time, the glass / ceramic bonding solder 16 adhered to the end surface of the rod lens A10 on the submarine optical cable side is removed by cutting or polishing the axial length of the rod lens A10 to 1/4 or 3/4 pitch length. To do.

Next, the ceramic part A12 is mounted on the end plate 5. Here, airtightness is obtained by solder-sealing 23 the ceramic component A12, which is pressure-resistant sealed by an O-ring 17, and is previously metal-coated 14 by electrodeposition, ion plating, vacuum deposition, sputtering, etc. keep.

Next, the rod lens A10 and the optical fiber A21 are connected. Here, for example, an optical fiber A21 is fixed inside a ceramic pipe B having an outer diameter smaller than the inner diameter of the ceramic pipe 18, and collimated light is incident from the end surface of the rod lens A10 on the submarine optical cable side, and A method of moving the ceramic pipe B in the pipe 18 and fixing it at a position where the intensity of the light incident on the optical fiber A21 is maximum can be used.

Further, similarly to the above method, parallel light is incident from the end face of the submarine optical cable, eccentricity is given to the hole inside the ceramic pipe 18, and the ceramic eccentricity having an outer diameter slightly smaller than the inner diameter of the ceramic pipe. Double eccentricity method for independently rotating a ceramic eccentric pipe C having an outer diameter slightly smaller than the inner diameters of the pipe B'and its ceramic eccentric pipe B'and having an optical fiber A21 fixed therein for optical axis alignment. It is also effective to use “Single Mode Fiber Connector” published by NTT, Research Practical Report, 28-6 (1979) p999.

The connection between the rod lens A10 and the optical fiber A21 is as follows.
It is also possible to carry out before fixing the rod lens A10 and the ceramic component A12. In this case, a ceramic pipe is used.
The optical fiber A21 is directly fixed inside the 18, and the rod lens A
The ceramic pipe 18 may be bonded to the ceramic pipe 10.

The rod lens B11, the ceramic component B13, and the optical fiber B22 on the submarine optical cable side can be connected in the same manner as the above steps. The above steps are carried out in the factory during the manufacturing of repeaters and cables, and ceramic parts A12 and B13 are guided during the construction and repair work of transmission lines.
The optical connection between the submarine optical cable and the repeater can be achieved by a simple operation of butting via 15.

In addition, a matching material such as a polymer having a refractive index similar to that of the rod lens A10 and the rod lens B11 is interposed between the end faces of the rod lens A10 and the rod lens B11, or a ceramic is used from the left side in FIG. By applying a pressing force of a spring or the like to the component B13, it is possible to eliminate the presence of air between the end surfaces of the rod lens A10 and the rod lens B11 and reduce the reflected light.

The effect of the above basic structure is that the various materials are selected so that the coefficient of thermal expansion of the rod lens, the ceramic component, and the end face plate metal changes stepwise, and the polyethylene coating applied to the outer circumference of this portion Even if the structure is subjected to thermal shock during molding, the stress applied to the glass / ceramic bonding solder 16 between the rod lens A10 and the ceramic component A12 and the solder sealing portion 23 between the ceramic component A12 and the end plate 5 is Compared to the case where the lens A10 is directly attached to the end face plate 5, the number can be reduced, and there is an advantage that a desired highly reliable watertight and airtight function can be secured. In addition, the environmental temperature during manufacturing and the subsequent usage environment (in the sea: -2 to 30
There is little thermal strain due to the difference in (° C), and long-term safety can be secured.

FIG. 4 is a view for explaining the second basic structure of the present invention, in which 20 is an adhesive B, 39 is a metal C ring, and 40 is a ceramic component holder.

In this basic structure, a ceramic component A12 with a coefficient of thermal expansion extremely close to that of the rod lens A10 is selected as the material of the ceramic component A12, and the surface of the ceramic component A1 is coated with a metal coat 14.
A metal C ring 39 is mounted between 2 and the end face plate 5 for the purpose of keeping airtightness, and an O ring 17 for protecting this is provided on the high pressure side.

In this structure, an adhesive B20 is filled between the ceramic pipe 18 and the ceramic component A12 as a backup of the glass / ceramic bonding solder 16. As this filling method, for example, a vacuum suction hole 32 for filling the adhesive is provided and suction is performed,
It is effective to keep the filling space of the adhesive in a high vacuum and to fill the adhesive without bubbles between the ceramic pipe 18 and the ceramic part A12 due to the viscosity of the adhesive.

According to an experiment conducted by the inventor of the present invention, the filling method described above shows that an optical fiber having an outer diameter of 0.125 mm is fixed inside a hole having a diameter of about 0.4 mm and a length of 10 mm, and an abnormality such as water leakage up to 2000 kg / cm ² occurs. There is a track record that did not occur.

In this structure, the glass / ceramic bonding solder 16 between the rod lens A10 and the ceramic component A12 is resistant to the thermal shock.
It is possible to prevent the stress due to the difference in the coefficient of thermal expansion from being applied to.

Further, since the airtightness by the metal C ring 39 is a structure in which the C ring is elastically deformed and pressed, a high airtight function can be maintained even if the difference in the coefficient of thermal expansion between the ceramic component A12 and the end face plate 5 is large. You can This metal C ring
It is difficult to mount 39 directly on the outer periphery of the small-diameter rod lens A10, but it can be mounted on a relatively large-sized ceramic component A12 mounted with a plurality of rod lenses A10.

As a result, the desired highly reliable watertight and airtight functions are secured,
Moreover, there is an advantage that safety can be secured for a long time.

As a result of the first and second basic structures, it goes without saying that the repeater housing can be downsized, the machining accuracy around the connecting portion can be relaxed, and the connecting work can be simplified.

FIG. 5 is an example of the overall structure of an undersea optical feedthrough that can be constructed by applying the present invention.

24 is a pressure pipe that also serves as a power line, 25 is a solder connection part, 26 is a metal part A, 27 is a metal part B, 28 is a joining pin, 29 is polyethylene, 30 is a polyethylene joining part, 31 is a metal part C, and 35 is matching. Oil, 36 is a power supply line, 37 is an oxidation treatment mold, and 38 is a gold plating film.

Here, from the submarine optical cable side, the power feeding path connected to the repeater circuit by the route of [24 → 26 → 27 → 36] is completely covered with polyethylene 29, and the polyethylene 29 and the metal part B27 and metal Oxidation mold at the interface of component C31
37 is applied to keep it watertight. The metal component B27 also has a guide function when the ceramic component A12 and the ceramic component B13 are butted against each other.

Further, in this embodiment, the matching oil 35 is filled between the ceramic component A12 and the ceramic component B13 as a refractive index matching agent to reduce the reflected light which adversely affects the light emitting element of the repeater circuit.

As described above, in this structure, since the feedthrough structure of the present invention that is resistant to thermal shock is used, the distance between the polyethylene coating on the outer periphery and the rod lens portion, which become hot in the mold, is short, that is, the entire structure is small. In particular, by setting the polyethylene mold abutting portion and the rod lens abutting portion of the highest temperature at substantially the same position, there is an advantage that the structure is simple and the workability is good.

(5) Effects of the Invention As described above, according to the present invention, in constructing a lens connector type feedthrough having an optical fiber connecting function in an optical fiber introducing portion of a submarine optical repeater housing, a rod lens and an end are used. By interposing the ceramic parts between the face plates and filling the gap between the rod lens and the ceramic parts with the solder for glass / ceramic bonding, it is possible to prevent the deterioration of the watertightness and the function of the airtight mechanism due to the thermal shock at the time of molding the polyethylene joint. There is an advantage that a reliable optical feedthrough can be realized.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing a structural example of a conventional submarine optical repeater housing, FIGS. 2 and 4 are vertical sectional views showing a basic structural example of the present invention, and FIG. 3 is used for the present invention. FIG. 5 is a characteristic view showing the coefficient of thermal expansion of various materials, and FIG. 5 is a vertical cross-sectional view showing an example of the overall structure of an undersea optical feedthrough that can be constructed by applying the present invention. 1 ... Submarine optical cable, 2 ... TT connection part, 3 ... Optical feedthrough, 4 ... Repeater circuit, 5 ... End plate, 6 ...
… Pressure resistant housing, 7 …… Optical fiber, 8 …… Optical fiber fusion splicing part, 9 …… Cable retractor, 10 …… Rod lens A, 11 …… Rod lens B, 12 …… Ceramic part A,
13 …… Ceramic parts B, 14 …… Metal coat, 15 ……
Guide, 16 …… Solder for glass / ceramic, 17 …… O-ring, 18 …… Ceramic pipe, 19 …… Adhesive A, 20
...... Adhesive B, 21 ...... Optical fiber A, 22 ...... Optical fiber B, 23 ...... Solder sealing part, 24 ...... Pressurizing pipe that also serves as a power supply line,
25 ... Solder connection part, 26 ... Metal part A, 27 ... Metal part B, 28 ... Joining pin, 29 ... Polyethylene, 30 ... Polyethylene joint part, 31 ... Metal part C, 32 ... Adhesion Vacuum suction hole for filling agent, 35 …… Matching oil, 36 …… Feed wire,
37 …… Oxidation treatment mold, 38 …… Gold plating film, 39 …… Metal C ring, 40 …… Ceramic component holder.

Claims (1)

[Claims] 1. In a submarine optical repeater housing, a converging type rod lens A, to which one or more optical fibers A derived from a repeater circuit are connected, maintains airtightness and watertightness on an end face plate through a ceramic part. The optical fibers of the submarine optical cable side and the repeater circuit side are connected to each other by abutting the end faces of the focusing type rod lens B mounted on the optical fiber B on the submarine optical cable side The ceramic component is thicker than the outer diameter of the rod lens A over a certain depth from the submarine optical cable side, and further deeper than the outer diameter of the optical fiber led out from the repeater circuit, and The rod lens A has a hole penetrating in a stepwise shape smaller than the outer diameter of the rod lens A, and the rod lens A is attached to the stepped hole from the submarine optical cable side. Lens connector type feedthrough, characterized in that the interface of the rod lens A and the ceramic component is joined by a solder glass-ceramic adhesive Te.