JPS6126008A - Fiber terminating part with lens - Google Patents

Abstract

PURPOSE:To improve the concentricity between a lens and a core and to improve the productivity and the yield of each member by pressing a part, at least, of peripheral surfaces of the core and the lens to the inside wall of a holder to fix them to the holder. CONSTITUTION:In a fiber terminating part, a core 5 which holds the end part of an optical fiber (a) in the center and a lens 4 have optical axes aligned in a holder 6 and are joined into one body. The inside of the holder 6 consists of a lens arranging part 6a and a core arranging part 6b, and solder storing parts 9 are formed in respective end parts of them. In a case of assembling, the lens 4 is inserted to the holder 6, and a solder 10 is put on the storing part 9, and the solder 10 is heated and flowed to the storing part 9 while pressing the lens 4 to the inside wall of the holder 6 by a jig through a hole, thus fixing the lens 4 to the holder 6. Next, the core 5 is inserted to the holder 6, and the solder is flowed to the storing part similarly. In this case, only storing parts 9 of the holder 6 are plated, and only corresponding parts of the core 5 are plated, thus improving the concentricity between the lens 4 and the core 5.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a structure in which the concentricity between a lens and an optical fiber is improved, and also to the introduction of light into an optical fiber or the light emitted from an optical fiber. This invention relates to a lens-equipped fiber termination section that makes it possible to efficiently derive the information.

[Prior art]

An example of the use of this type of lensed fiber termination section is an LD module. Figure 5 shows its configuration. In the figure, 1 is a semiconductor laser (hereinafter abbreviated as LD), 2 is a ball lens for converting the emitted light from the LD into almost parallel light, and 3 is a focusing rod for slightly focusing the parallel light obtained by the ball lens 2. Lens (hereinafter abbreviated as lens), 4 is a lens, and a holder 6 is attached together with a core 5 whose tip is coated with optical adhesive 11.
They are fixed and integrated by a bonding material tOa such as an organic adhesive or solder. The core 5 is used for fixing the nylon jacket 7 and the wire 8 of the optical fiber a.

The important things when integrating the lens 4 and the core 5 are: ■ High concentricity; ■ The relative position of the lens 4 and core 5 should not shift after being fixed to the holder 6; and ■ - Integration yield. It must be easy to perform, etc. In order to fix the lens 4 and the core 5 to the housing 6, it is possible to use an organic adhesive. However, the adhesive tends to creep when the internal stress generated during solidification is relaxed over time, and the lens 4 and the core 5 tend to be misaligned. As the optical fiber wire 8,
FIG. 6 shows how the coupling loss increases when axis misalignment occurs in a direction perpendicular to the optical axis in an LD module to which a lensed fiber termination section constructed using a single mode optical fiber is applied. From the figure, the axis deviation of only ±3 μm is 1.
It can be seen that an increase in loss of 3+1 B occurs. In general, adhesives tend to shift their axis by several degrees due to changes in environmental temperature after solidification, so in order to realize highly reliable T and D modules, DK, such as solder or laser welding, should be used instead of organic adhesives. It is necessary to fix the lens 4 and core 5 to the holder 6. Since the adhesive takes a long time to harden and the manufacturing efficiency of integration is not good, it is necessary to improve this by using solder or laser welding.

When fixing the core 5 to the holder 6 by soldering, since the nylon jacket 7 of the optical fiber is fixed to the core 5 using adhesive, these cannot be heated for a long time. Therefore, a high-frequency induction heating device is used to instantaneously heat and melt the solder. The core 5 and the holder 6 are made of a ceramic material in order to suppress heat generation of the members when high frequency is applied.

[Problem that the invention seeks to solve]

By the way, in the configuration of the termination part as described above, it is difficult to manufacture the core 5 and holder 6, which are made of ceramic material, with a clearance that is equivalent to matching the actual product, and the yield rate of the core 5 and holder 6 is low. There is a problem that the value decreases. Also, lens 4
Since the manufacturing accuracy of the outer diameter of the focusing rod lens normally used as a lens is approximately ±5 μm, it is extremely difficult to manufacture the lens 4 and the holder 6 with a clearance comparable to that of the actual product. On the other hand, if the clearance between the core 5 and the holder 6 is increased in order to improve the yield of the core 5 and the holder 6, the concentricity between the lens 4 and the core 5 will decrease, and the lens 4 or the core 5 tilts in the holder 6,
A problem arises in that the coupling efficiency of the LD emitted light to the optical fiber element 8 deteriorates.

The problem of the present invention is to obtain a high degree of concentricity between the lens and the core, and to improve the manufacturability and yield of each member.

[□Failure to solve the problem]

The present invention is characterized in that the core and the lens are fixed to the holder by pressing at least a portion of each of the circumferential surfaces of these members against the inner wall of the holder.

[Embodiment] - Fig. 1 is a diagram showing an embodiment of the present invention, in which the fiber termination part is connected to a ceramic core 5 that holds the end of the optical fiber a in the center, and It has a structure in which a lens 4 for introducing light or for guiding light from an optical fiber a is integrated within a cylindrical ceramic holder 6 with its optical axis aligned. Note that the reference numerals in FIGS. 1 to 4 that are the same as those in FIG. 5 indicate the same components.

The inside of the holder 6 consists of a lens placement part 6a with a slightly larger diameter than the lens 4, and a core placement part 6b with a slightly larger diameter than the core 5. A large diameter solder reservoir 9 is formed at each end. The holder 6 also includes a lens placement portion 6a and a core placement portion 6.
Holes 13 and 14 are formed to open each part to the outside.

The procedure for assembling the fiber termination part will be explained with reference to FIGS. 1 to 3. First, as shown in FIG.
Place it in the holder 6 which has been subjected to step 2.

Next, a ring-shaped solder 10 is placed on the solder reservoir 9, and the lens 4 is pressed against the inner wall of the holder 6 using a jig such as a screw or a rod through the hole 13, and the solder 10 is applied using a high-frequency induction heating device. is heated and poured into the solder reservoir 9, and the lens 4 is heated.
is fixed to the holder 6.

Further, as shown in FIG. 3, insert the core 5 whose tip is coated with optical adhesive 11 into the holder 6, place the ring-shaped solder 10 on the solder reservoir 9, and then insert the screw from the hole shown in 14. While pressing the core 5 against the inner wall of the holder 6 with a jig such as a rod or the like, the solder 10 is heated with a high frequency induction heating device, and the solder is poured into the reservoir 9. Here, as shown in the figure, the holder 6 is solder-plated only in the reservoir 9 portion where the inner diameter is increased at both ends.
Apply step 2 and leave the other parts as ceramic fabric.

Further, the core 5 is solder-plated only at a portion corresponding to the solder-plated portion of the holder 60, and the other portions are left as ceramic material.

As mentioned above, in this fiber termination section, the lens 4 and core 5 are fixed while being pressed against the inner wall of the holder 6, so the inner diameter of the holder 6 is made larger than the outer diameter of the lens 4 and the core 5. Also, the degree of concentricity between the lens 4 and the core 5 increases.

Currently, the outer diameter of the focusing rod lens, which is lens 4, is as follows:
For example, there is a variation of about ±5 μm with respect to the design values 1 and 8 mff1, but the inner diameter of the holder 6 may vary depending on the lens 4 or the core 5.
Even when the outer diameter of L is increased by approximately 2071 m,
It has already been confirmed that the coupling efficiency of the D output light to the single mode optical fiber strand hardly deteriorates. moreover,
Since the solder has sufficiently flowed into the solder reservoir 9, high fixing strength can be obtained. Furthermore, since the solder 10 flows uniformly and axially symmetrically into the solder reservoir 9, the relative positional relationship between the lens 4 and the core 5 is stable against changes in ambient temperature.

FIG. 4 is a diagram showing another embodiment of the present invention, and the embodiment shown in this figure is an example in which the inner diameter of the holder 6 is made uniform and the outer diameters of the lens 4 and the core 5 are also made equal. In this example,
As a result, the manufacturability of the holder 6 is extremely improved.

In each of the above embodiments, soldering was used as a method for fixing the lens 4 and core 5 to the holder 6, but the present invention can also be applied to laser welding. In that case, the solder reservoir 9 and the solder 10 become unnecessary.

Further, the core 5 and the holder 6 may be made of metal.

Note that it is difficult to cut screws in ceramic, so if a ceramic material is used for the holder 6, the integration hole 13
．． Reference numeral 14 is simply a blank hole, and after fixing the lens 4, core 5'f, and holder 6, the rod for integration is removed. Moreover, when metal is used as the holder 6, the integration hole 13.
14, and attach the lens 4 and core 5 to the holder 6.
Screws can be used when fixing to. This screw may be removed after fixing the lens 4 and the core 5, or may be left as is.

Further, in the above embodiment, an example in which a focusing rod lens is used as the lens 4 has been described, but a spherical lens, a plano-convex lens, an spheroidal lens, etc. can be used as the lens 4.

〔Effect of the invention〕

As explained above, according to the present invention, since the lens and the core are pressed and fixed against the inner wall of the holder, it is possible to obtain a high degree of concentricity between the lens and the core. Moreover, the lens and core do not tilt within the holder, and it is possible to obtain a high coupling efficiency of the LD emitted light to the optical fiber. Further, since the inner diameter of the holder can be made larger than the diameter of one row of lenses or cores, there are advantages such as high manufacturability and yield of the holder.

[Brief explanation of drawings]

Figures 1 to 3 are diagrams showing an embodiment of the present invention, in which Figure 1 is a schematic diagram of the fiber termination section, and Figures 2 and 6 are diagrams showing the assembly procedure of the fiber termination section. FIG. 4 is a schematic configuration diagram showing another embodiment of the present invention, and FIG. 5 is a schematic configuration diagram of an LD module using a conventional lens-covered fiber termination section. FIG. 3 is a diagram showing coupling loss due to axis misalignment of the optical fiber when a single mode optical fiber is used as the line. a...Optical fiber, 4...Lens, 5
... Core, 6 ... Holder. Figure 6: 7 shafts with 1 ton of bearing shaft - rχ amount O1m) Figure 2 Figure 3

Claims (1)

[Claims] A core that holds the end of an optical fiber at its center and a lens for introducing light into or extracting light from the optical fiber are integrated in a cylindrical holder with their optical axes aligned. A lens characterized in that, in the lens-equipped fiber termination section, the core and the lens are fixed to the holder with at least a portion of each of the circumferential surfaces of these members being pressed against the inner wall of the holder. Fiber termination section with attached.