JPS60159712A - Method for connecting optical fiber and lens - Google Patents

Abstract

PURPOSE:To connect surely an optical fiber and lens and to reduce the loss of light by deforming the optical fiber elastically in a sleeve and pressing the end face of the optical fiber to the surface of the lens with its elastic restoring force. CONSTITUTION:Before an adhesive 2 is hardened, an end face 4a of an optical fiber bare conductor 4 is polished directly by a polishing material 9. At this time, though a projecting part of the optical fiber bare conductor 4 is pressed into a sleeve 1, the end face 4a is always pressed to the polishing material 9 by its elastic restoring force. After this processing, the sleeve 1 is inserted into a sleeve 7 before the adhesive 2 is hardened, and the end face 4a of the optical fiber bare conductor 4 is pressed to one end face 6a of a lens 6, and an end face 1a of the sleeve 1 is brought into contact with one end face 6a of the lens. In this state, sleeves 1 and 7 are stuck to each other by a solder 8 or the like. Consequently, the optical fiber is brought closely into contact with the surface of the lens completely, and therefore, they are connected with less loss of light.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of connecting an optical fiber and a lens.

One of the methods of connecting optical fibers or optical fibers with a light source/receiver is a method called an optical coupling method, and one of these optical coupling methods is a method using a lens. be. However, in this method using a lens, it is first necessary to connect the optical fiber and the lens.

FIGS. 1 and 2 show a conventional example of a method for connecting an optical fiber and a lens in this manner.

In this conventional example, a liquid hardening adhesive 2 is first filled into a sleeve 1 made of metal or the like. This adhesive 2
is for fixing the optical fiber inside the sleeve l, and usually uses epoxy resin.

After filling the adhesive 2, the optical fiber is inserted into the sleeve l, but the optical fiber cord is not inserted as is, but the outer coating layer (not shown) and the fibrous reinforcing material (not shown) are removed from the optical fiber cord. A portion of the optical fiber core wire 3 from which the core wire 3 has been removed, and a portion of the bare optical fiber wire 4 from which the inner coating layer such as the nylon coat has been removed from the optical fiber core wire 3 are inserted into the sleeve l.

When inserting the optical fiber into the sleeve 1, first insert the bare optical fiber 4 into the other end surface 1b so that the bare optical fiber 4 protrudes from one end surface 1a of the sleeve 1 by less than a few cranes.
It is inserted from the side, and then the optical fiber core wire 3 connected to the bare optical fiber wire 4 is inserted.

Thereafter, adhesive 5 is applied to a portion of the bare optical fiber 4 that protrudes from one end surface 1a of the sleeve 1 and this one end surface 1a. The adhesive 5 used is the same as the adhesive 2 filled into the sleeve 1, such as epoxy resin.

After the adhesives 2 and 5 have hardened, by polishing the end surface 4a of the bare optical fiber 4, the adhesive 5, and the one end surface 1a of the sleeve 1, the end surface 4 will be flush with the one end surface 1a and mirror-like.
In other words, the adhesive 5 acts as a coating.

After performing the above-mentioned processing, for example, as shown in FIG. 2, the sleeve l is inserted into the sleeve 7 made of metal etc. and into which the self-focusing lens 6 is inserted, and these sleeves 7 By fixing the sleeve 1 and the sleeve 1 with solder 8 or the like, the bare optical fiber 4 and the lens 6 can be connected.

However, in this conventional example, when the sleeve 1 and the sleeve 7 are fixed together with the solder 8, one end surface 1a of the sleeve 1 is
and one end surface 6a of the lens 6 (it is necessary to bring them into complete contact with each other).

However, such work is not easy, and if these two are even slightly separated from each other, it is impossible to connect the bare optical fiber 4 and the lens 6 with low optical loss.

SUMMARY OF THE INVENTION In view of these problems, it is an object of the present invention to provide a method for connecting an optical fiber and a lens, which can reliably connect the optical fiber and the lens with little loss of light.

Hereinafter, first and second embodiments of the present invention will be described with reference to FIGS. 3 to 5.

3 and 4 show a first embodiment of the invention.

In this first embodiment, the adhesive 2 is first filled into the sleeve 1, and then the bare optical fiber 4 and the optical fiber core 3 are inserted into the sleeve 1, but these steps are the same as in the conventional example described above. It may be substantially the same as when Note that the adhesive 2 is not necessarily required.

Next, as shown in FIG. 3A, the other end surface 1b of the sleeve l
The optical fiber core wire 3 is tightened by caulking the side wall surface, and by this tightening, the part of the optical fiber core wire 3 inside the sleeve 1 is fixed to the sleeve 1, and one end surface of the sleeve 1 of the bare optical fiber wire 4 is fixed. Cut the part protruding from 1a to a predetermined length.

Thereafter, as shown in FIG. 3B, before the adhesive 2 has hardened, the optical fiber is bonded without applying adhesive as a coating to the protrusion of the bare optical fiber 4 and one end surface 1a of the sleeve 1. The end surface 4a of the bare wire 4 is directly polished with an abrasive material 9.

At this time, the end surface 4a of the bare optical fiber 4 is pressed against the abrasive material 9, but since the optical fiber core 3 is tightened to the wall surface of the sleeve 1, even though the adhesive 2 is not cured,
This optical fiber core wire 3 does not move. For this purpose, the bare optical fiber 4 located inside the sleeve 1 is
Although the protrusion of the bare optical fiber 4 is elastically deformed as shown in FIG.

Therefore, the above-mentioned length is such that an appropriate elastic restoring force is generated in the bare optical fiber 4 and is within the limit of elastic deformation, and furthermore, the bare optical fiber 4 does not come into contact with the inner wall surface of the sleeve 1. It is necessary to select various values. In this embodiment, a bare optical fiber 4 having an outer diameter of 125 μm was used, but the preferred length in this case is 50 to 200 μm, more preferably 100 to 150 μm.

FIG. 3C shows the state after polishing is completed, and the bare optical fiber 4 still protrudes by a length l from one end surface 1a of the strip I), although it is only 10 to 100 μm, even after polishing is completed. ing.

After performing the above processing, as shown in FIG. 4, the sleeve l is inserted into the sleeve 7 before the adhesive 2 hardens, and the end surface 4a of the bare optical fiber 4 is aligned with one end surface of the lens 6. 6a, and one end surface 1a of the sleeve 1 is brought into contact with one end surface 6a of the lens 6. Then, in this state, the sleeve 1 and the sleeve 7 are fixed together with solder 8 or the like.

At this time, since the adhesive 2 is not yet cured, the bare optical fiber 4 located within the sleeve 1 is elastically deformed as shown in FIG. As a result, the protrusion of the bare optical fiber 4 enters into the sleeve 1, but its elastic restoring force keeps the end surface 4a pressed against the one end surface 6a of the lens 6.

Therefore, when the sleeve 1 and the sleeve 7 are fixed together by the solder 8 or the like, the one end surface 1a of the sleeve 1 and the one end surface 6 of the lens 6
Even if they are separated from each other by some distance, the end surface 4a of the bare optical fiber 4 and one end surface 6a of the lens 6 are in complete contact with each other, so there is no loss of light between the bare optical fiber 4 and the lens 6. Fewer connections can be made reliably.

FIG. 5 shows a second embodiment of the invention. In this second embodiment, as in the first embodiment described above, the adhesive 2 is first filled into the sleeve l, the bare optical fiber 4 and the optical fiber core 3 are inserted into the sleeve 1, and then By caulking the wall surface on the other end surface 1b side of the sleeve 1, the portion of the optical fiber core 3 inside the sleeve 1 is fixed to the sleeve 1.

However, at this time, the length of the bare optical fiber 4 that protrudes from the one end surface 1a of the sleeve 1 is as shown in FIG.
The length is made much longer than that in the first embodiment. Furthermore, the adhesive 2 is not necessarily necessary in this second embodiment either.

Next, the bare optical fiber 4 protruding from the sleeve 1 and the one end surface la side of the sleeve 1 are inserted from below into the through hole 15a of the thick plate-shaped support 15, and are fixed to the upper surface of the support 15. One end surface 1a is brought into contact with the positioning member 16 that is being held.

A holder 22 is suspended above the through hole 15a of the support 15 by a support 17 fixed to the upper surface of the support 15 and a spring 21 fixed to the support 17. Then, the bare optical fiber 4 protruding from the one end surface 1a is held by the holder 22, and the spring 21 applies a predetermined static tensile force to the bare optical fiber 14 in the axial direction. At this time, since the optical fiber core wire 3 is tightened by the wall surface of the sleeve 1, even if a tensile force is applied to the bare optical fiber wire 4, even though the adhesive 2 is uncured, the bare optical fiber wire 4 does not move relative to sleeve 1.

Finally, while applying a tensile force as described above, a crack is made with the diamond blade 23 at a point on the circumferential surface of the bare optical fiber 4 at a position a predetermined distance β from one end surface 1a of the sleeve l.

Then, a broken mirror surface is formed perpendicular to the axis of the bare optical fiber 4, and a mirror-like end surface is formed at a position protruding a distance l from one end surface 1a of the sleeve 1, as shown in FIG. 3C. 4a can be formed.

Therefore, by inserting the sleeve 1 into the sleeve 7 and fixing them together with solder 8 or the like as shown in FIG. 4, the same effect as in the first embodiment can be obtained.

In the first and second embodiments described above, self-focusing lenses were used as lenses to be connected to optical fibers, but the present invention can also be applied to connections between optical fibers and spherical lenses, etc. can be applied.

As described above, in the present invention, the optical fiber is elastically deformed within the sleeve, and the end surface of the optical fiber is pressed against the surface of the lens by the elastic restoring force, so that one end surface of the sleeve and the surface of the lens are Even if they are separated from each other to some extent, the end face of the optical fiber is in complete contact with the surface of the lens, so that a connection with low optical loss can be reliably established between the optical fiber and the lens.

[Brief explanation of the drawing]

Figures 1 and 2 show a conventional example of the present invention, with Figure 1 being a schematic vertical cross-sectional view showing an intermediate process, and Figure 2 being a schematic vertical cross-sectional view showing the final process. . 3 to 5 show the first and second embodiments of the present invention, FIG. 3 is a schematic longitudinal cross-sectional view showing an intermediate step in the first embodiment, and FIG. Schematic vertical cross-sectional view showing the final process of the second embodiment 1. FIG. 5 is a schematic side view showing an intermediate step in the second embodiment. In addition, in the symbols used in the drawings, 1...-1--1--11------Sleeve la--...--One end surface 3-- ...
−・・−・−・・−Optical fiber core wire 4−・−・・−・・
...-Optical fiber bare wire 4a...--One end surface 6--Self-focusing lens 6
a.------------ One end surface Agent Ueya Yoshio Katsunekane Figure 1 Figure 2 Figure 3 Figure 5

Claims (1)

[Claims] inserting the optical fiber into the sleeve and forming a mirror-like end surface on the optical fiber at a position slightly protruding from one end surface of the sleeve; pressing the end surface of the optical fiber against the surface of the lens; A method for connecting an optical fiber and a lens, comprising the steps of fixing the sleeve to the lens while the optical fiber is elastically deformed within the sleeve.