JPS6126007A - Fiber terminating part with lens and its formation - Google Patents

Abstract

PURPOSE:To reduce clearances between a lens and a holder and between a core and the holder and to obtain a high concentricity of the core by fixing each member with fixing parts formed in the holder when the lens and the core are fixed 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 having the same diameter as the lens 4 and a core arranging part 6b having the same diameter as the core 5, and large-diameter fixing parts 9 are formed in respective at end parts of arranging parts 6a and 6b. The lens 4 is inserted to the holder 6, and a solder 10 is put on fixing parts 9 and is heated by a heater and is flowed to fixing parts 9 to fix the lens 4 to the holder 6. The core 5 to which an optical adhesive 11 is applied is inserted to the holder 6, and the solder 10 is put on fixing parts 9 and is heated and is flowed to fixing parts 9. In this case, only fixing parts 9 of the holder 6 are plated with the solder, and only parts corresponding to fixing parts 9 of the core 5 are plated with the solder, thus improving the concentricity of the core 5.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a lens-attached lens that improves the concentricity between the lens and the optical fiber and that firmly fixes the lens and the core to the holder for integration. 7 eyeper termination and its formation method.

[Prior art]

An example of the use of this type of lensed fiber termination section is an LD module. Figure 6 shows its configuration. In the figure, 1 is a semiconductor laser (hereinafter abbreviated as LD), 2 is a ball lens for converting the LD emitted light into almost parallel light, and 3 is a converging rod for slightly focusing the parallel light obtained by the ball lens 2. Lens C (hereinafter referred to as "lens"), 4 is a lens, which is fixed to a holder 6 together with a core 5 whose tip is coated with an optical adhesive 11 by a bonding material 10 such as an organic adhesive or solder, and is integrated. has been done. The core 5 is used to fix the nylon jacket 7 and the wire 8 of the optical fiber a.

The important things for the integration of the lens 4 and the core 5 are: ■High concentricity, ■Fixed wave to the holder 6, and that the relative positions of the lens 4 and the core 5 do not shift, ■Integration can be easily performed with high yield, etc. To fix the lens 4 and the core 5 to the holder 6, it is possible to use an organic adhesive. However, when the internal stress generated during solidification is relieved over time, the adhesive tends to creep, and the lens 4 and the core 5 tend to be misaligned. Hikari 7 Aiba wire 8
In an LD module to which a lensed fiber termination section configured using a single mode optical fiber is applied,
FIG. 7 shows how the coupling loss increases when axis misalignment occurs in a direction perpendicular to the optical axis. From the figure, 1. It can be seen that an increased loss of ilB occurs. In general, adhesives undergo axis misalignment of a few microns after solidification due to changes in environmental temperature, etc., so it is difficult to realize highly reliable LD modules by using, for example, solder tubes instead of organic adhesives.
It is necessary to fix the lens 4 and the core 5 to the holder 6. Since the adhesive takes a long time to solidify, it is not easy to manufacture the product in one piece. Therefore, it is necessary to improve this by using solder.

When fixing the core 5 to the holder 6 with solder, the nylon jacket 7 of the optical fiber is fixed to the core 5 using an adhesive, so it cannot be heated for a very long time. Therefore, a high frequency induction heating device is used to instantaneously heat and melt the solder.

Further, the core 5 and the holder 6 are made of Fi ceramic material in order to suppress heat generation of the members when high frequency is applied.

When fixing the core 5 and holder 6, which are ceramic materials, with solder, it is necessary to metalize the core 5 and holder 6 in advance, and then perform solder plating in order to improve the solder's applicability. be. [Problems to be solved by the invention] In the conventional fiber termination structure as described above, the entire outer peripheral surface of the core 5 and the inner wall of the holder 6 are plated with solder. Due to the unevenness of the plating, lens 4
There was a problem in that the concentricity between the core 5 and the core 5 was not good, and the coupling efficiency of the LD emitted light to the optical fiber strand 8 was poor.

Also, the solder application inside the holder 6 may not be uniform.
Since the solder expands and contracts non-uniformly as the ambient temperature changes, there is a problem in that the relative positions of the lens 4 and the core 5 are misaligned, and the coupling efficiency fluctuates. Explanation, holder 6
In order to heat the solder-plated part from the outside, it is necessary to apply a high frequency wave with a large amount of power, which poses the problem of poor integration manufacturability and poor yield (tg).

In the present invention, the problems are the concentricity and misalignment between the lens and the core, as well as the manufacturability and yield rate of each member.

[φ stage to solve problems]

In the present invention, the holder has an inner diameter approximately equal to that of the core and the lens on both sides in the longitudinal direction, and at both ends, a portion having a length shorter than the length of the lens and the core inserted into the inner part of the holder. The holder is characterized in that the inner diameter of the holder is a fixed part formed to be larger than that of the following part, and the core and lens are fixed to the holder by solder only in this fixed part.

Furthermore, when forming the above lensed fiber termination part, the present invention applies solder plating to the inner circumferential surface of the fixing part and the part corresponding to the fixing part of the core, and after inserting the core into the holder. , solder is placed along the fixing part, and is poured into the fixing part by high-frequency induction heating to fix the core in the holder.For lenses, a lens whose outer periphery is coated with metal is inserted into the holder, and the core is It is characterized in that it is fixed to the holder by pouring solder into the fixing part in the same process as ib.

【Example〕

FIG. 1 is a diagram showing an embodiment of the present invention, in which the fiber termination part includes a ceramic core 5 that holds the end of the optical fiber a in the center, and a core 5 that introduces light into the optical fiber a. Alternatively, the lens 4t for guiding light from the optical fiber a has a structure in which the optical axis is aligned and integrated within a cylindrical ceramic holder 6. Note that reference numerals in the first box to FIG. 5 that are the same as in FIG. 6 indicate the same components.

The inside of the holder 6 consists of a lens placement part 6&, which has approximately the same diameter as the lens 4, a core placement part 6b, which has approximately the same diameter as the core 5, a lens placement part 6a, and a core placement part 6'. A large diameter solder reservoir portion 9 (fixing portion) is formed at each end of b.

The procedure for assembling the fiber termination part will be explained with reference to FIGS. 1 to 3. First, the lens 4t whose outer peripheral surface is metallized (metal coated), the solder plated 12f:
Next, place a ring-shaped solder 1 (l) on top of the solder reservoir 9, heat the solder 10 with a high-frequency induction heating device, pour it into the solder reservoir 9, and attach the lens 4. Fix it in the holder 6. Also, as shown in Fig. 3, insert the core 5 whose tip is coated with optical adhesive 11 into the holder 6.
After a ring-shaped solder 10 is placed on the solder reservoir 9, the solder 10 is heated by a high frequency heating device, and the solder is poured into the solder reservoir 9. Here, as shown in the figure, the holder 6 is solder-plated only on 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.

Thus, according to this fiber termination part, the outer diameter of the lens 4 and the core 5 and the inner diameter of the holder 6 can be made almost equal, and the clearance can be made small. Concentricity can be increased. Furthermore, since the solder has sufficiently flowed into the solder reservoir 9, high fixing strength can be obtained. 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. In the embodiment shown in this figure, 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. According to this embodiment, the manufacturability of the holder 6 is extremely improved.

FIG. 5 shows yet another embodiment of the invention, in which the holder 6 is provided with integration holes 13, 14. In this embodiment, a jig is inserted through the holes 13 and 14 to press the lens 4 and the core 5 against the inner wall of the holder 6. In this case, lens 4
Even if the inner diameter of the holder 6 is made larger than the outer diameter of the core 5, the lens 4 and the core 5 can be easily made concentrically, and the manufacturability of the holder 6 is further improved. It has already been confirmed (by experiment) that even if the clearance in this case is set to about 20 μm, the coupling efficiency of the LD emitted light to the single mode optical fiber strand 8 does not deteriorate much.

In each of the above embodiments, a convergent rod lens is used as the lens 4, but a spherical lens, a plano-convex lens, an spheroidal lens, etc. can also be used as the lens 4.

〔Effect of the invention〕

According to the present invention, when fixing the lens and the core to the holder, these parts are fixed using the fixing part formed on the holder, so the clearance between the lens, the core, and the holder is reduced. This allows for high concentricity of the lenses and cores. In addition, by concentrating the solder-fixed parts in one part, it is possible to prevent misalignment between the lens and the core due to the expansion and contraction of the solder, and it is also easy to conduct induction heating, resulting in an easy manufacturing process with a yield rate of 11. It has the advantage of improving.

[Brief explanation of drawings]

1 to 3 are diagrams showing one embodiment of the present invention, in which FIG. 1 is a schematic configuration diagram of a fiber termination section, FIG.
FIG. 3 is an explanatory diagram showing the assembly procedure of the fiber termination part,
4 and 5 are both schematic configuration diagrams showing another embodiment of the present invention, FIG. 6 is a schematic configuration diagram of an LD module using a conventional lens-to-fiber termination section, and FIG. 7 is an optical FIG. 3 is a diagram illustrating coupling loss due to optical fiber axis misalignment when a single mode optical fiber is used as the fiber wire. a...Optical fiber, 4...Lens, 5
... Core, 6 ... Holder, 9 ...
...Fixing part (reservoir part), 10...Solder, 12.
...Solder plating. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) A core held around the end of an optical fiber and a lens for introducing light into or emitting light from the optical fiber are aligned in a cylindrical holder so that their optical axes are aligned. In the integrated lensed fiber termination section, the holder has an inner diameter approximately equal to the core and lens on both sides in the longitudinal direction, and has an inner diameter at both ends that is longer than the length of the lens and core inserted into the holder. A lens-equipped lens characterized in that the inner diameter of the short length part is larger than that of the part that follows it, and the core and the lens are fixed to the holder by soldering only in the fixed part. Fiber termination. (2) The optical axis of a core held centered around the end of an optical fiber and a lens for introducing light into or out of the optical fiber are aligned in a cylindrical holder. When forming an integrated lensed fiber termination section, the length of the lens and core that has an inner diameter approximately equal to that of the core and lens on both sides in the longitudinal direction, and that is inserted into the inside of the holder at both ends. Using a holder having a fixing part in which the inner diameter of a portion shorter than the diameter of the fixing part is larger than that of the following part, solder plating is applied to the inner circumferential surface of the fixing part and a part corresponding to the fixing part of the core, After inserting the core into the holder, solder was placed along the fixing part, and solder was poured into the fixing part by high-frequency induction heating to fix the core to the holder, and the outer periphery of the lens was coated with metal. A method for forming a fiber termination part with a lens, which comprises inserting a lens into a holder and fixing it to the holder by pouring solder into the fixing part using the same process as for the core.