JPS58194010A - Connection type optical fiber sealed introduction structure - Google Patents

Abstract

PURPOSE:To improve watertightness and airtightness and to reduce optical loss, by executing a fusing connection of optical fibers, and making the thin hole of a sleeve less than the outside coating diameter of the optical fiber and minimizing the thickness of a sealing member. CONSTITUTION:Coatings at respective terminals of the optical fibers 17 and 18 are removed, the terminal of the optical fiber 17 is run through the thin hole 20 of the sleeve 19 made of ceramic, and a heat sealing connection between the terminal and the coating-removed terminal of the optical fiber 18 is made. Further, the gap between the inside circumferential surface of the thin hole of the sleeve and the terminal outside circumferential surface is treated by adhesive sealing 20a and a protecting sleeve 22 is attached and treated by internal adhesive sealing 22a; and they are inserted into a body 23 and adhesive sealing treatments 24 and 25 are carried out between the outside circumferential surfaces of the sleeves 19 and 22 and the inside circumferential surface of the body 23.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an original fiber sealing introduction structure used in optical submarine cable system repeaters and the like.

As shown in Figure 1, the basic structure of an optical submarine repeater is that it has a repeater unit 1 for amplifying optical signals inside, and the repeater unit 1 is protected from high water pressure around the outside. It has a pressure-resistant cylinder 2 and a cover 3, and the cover 3 is provided with a source fiber introduction part 5 for guiding the optical fiber 4 to the repeater unit. Since high water pressure acts on this optical fiber introducing section 5, high watertightness/airtightness and low light loss properties are required.

As shown in FIG. 2, the conventional optical fiber introducing section has a structure in which a rod lens 6 is interposed between optical fibers 7 and 8 from the viewpoint of high watertightness and airtightness.

That is, after removing part or all of the coating on the end portions of each of the optical fibers 7 and 8, inserting the coating into the strips 9 and 10, respectively.
and 10, filling gaps 11 and 12 with adhesive,
Furthermore, after polishing the end faces 13 and 14, the optical axes of the optical fiber 7 and the opening, and the drain lens 6 and the optical fiber 8 are completely aligned, and the end faces 13 and 14 are fixed to the optical fibers 7 and 8 with adhesive. This glued and fixed whole body 15
Insert into sleeve 9. (2) The gap I6 between the rod lens 6 and the body 13 is filled with a gold-sealed optical filler [7].

Since it is necessary to attach and fix with adhesive, the optical loss is very large at about 1 dB when the optical wavelength is 13 μIη. Furthermore, after the optical axis alignment has been performed, the optical axis must be held with high precision to prevent the optical axis from shifting until the adsorbent solidifies, resulting in poor workability.

Is the purpose of the present invention a structure for introducing optical noiper sealing that eliminates the above-mentioned drawbacks? It is to pray.

Introducing the seal of the present invention (the structure is such that the end portion of the optical fiber from which part or all of the coating has been removed is passed through the pore of the sleeve having a diameter smaller than the outer diameter of the coating of the optical fiber,
The terminal section and the terminal section of the other optical fiber 1 are fused together, and the gap between at least one of the fiber terminal sections and the pore is completely sealed with a low-melting metal, an adhesive, etc. It has a filled configuration.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 3 is a sectional view showing one embodiment of the present invention.

In this embodiment, the coating on the end portions of the original fibers 17 and 18 is removed, and the entire end portion of the optical fiber 17 from which the coating has been removed is passed through the pore 20 of the sleeve 19 made of a ceramic material. The end portion of the optical fiber 18 from which the coating has been removed is fusion spliced at the entire connection portion 21. Furthermore, the gap between the inner circumferential surface of the pore of the sleeve and the outer circumferential surface of the end portion is adhesively sealed 2 (l a L), Next, the entire protective sleeve 22 is attached and the inside is adhesively sealed 22 a L, and this is sealed to the body 23. and adhesively seals between the outer peripheral surfaces of the sleeves '19 and 22 and the inner peripheral surface of the body 23.
Do 5.

In this embodiment, a metal coating is applied to the terminal parts of the optical fibers 17 and 18, and the sleeve 19 is made entirely of a material with a low linear expansion coefficient such as cover or Elinvar, and is used as an adhesive sealing material. All low melting point metals may be used.

As described above, in the present invention, the pore 20 of the sleeve 19 can be made smaller than the outer diameter of the coating of the original fiber 17 by performing a one-way connection of the optical fiber, so that the thickness of the sealing member can be minimized. . In addition, a two-stage sealing structure is achieved by the sealing parts 20a and 22a, and water pressure of the sleeve 19 is received and watertight sealing is performed at the Nlh part 24, so watertightness and tracheal properties are highly reliable. Since no rod lens is involved in connecting the optical fibers 17 and 18, the loss is also approximately 0.2 d.
It has the effect of being able to achieve a very low B.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the basic structure of an optical submarine repeater, Fig. 2 is a sectional view showing a conventional optical fiber sealing introduction structure, and Fig. 3 is a sectional view showing an example of the present invention. . In the figure, 1...Repeater unit, 2...Pressure cylinder, 3...Cover, 4...Optical fiber, 5...
Optical fiber 4 people ff1S, 6...Rod lens, 7...Original fiber, 8...Optical fiber, 9
...Sleeve, 10... Sleeve, 11. Adhesive sealing filling section, 12. Adhesive sealing filling section, 12
・Original fiber end surface, 14 ・Original fiber end surface, 15・
・Body, 16... Adhesive sealed light * Capital, 17...
Optical fiber, 18... Optical fiber, 19... Sleeve, 20-... Pore, 21... Fusion splice,
22... Protection sleeve, 23... Body, 20a, 22a, 24° 25... Adhesive sealing part.

Claims (1)

[Claims] The end portion of the original fiber from which part or all of the coating has been removed is passed through the pore of the sleeve having a diameter smaller than the outer diameter of the coating of the optical fiber, and the end portion is connected to the other end portion of the original fiber. A spliced optical fiber sealing introduction structure characterized in that the entire fiber is fused and spliced, and a gap between at least one of the original fiber end portions and the pore is filled with a low melting point metal, an adhesive, or the like.