JPH03242605A - Hermetic sealing structure of optical fiber introducing part - Google Patents

Abstract

PURPOSE:To obtain the hermetic sealing structure which is less deteriorated with lapse of time by press-fitting a capillary into the front end of a metallic pipe and inserting an optical fiber into the fine hole of the capillary, then packing solder into the aperture of the front end. CONSTITUTION:A capillary press-fitting hole 6 is formed in the metallic pipe 2 and the ceramics capillary 8 shorter than the depth of the press-fitting hole 6 is press-fitted into the press-fitting hole 6. After the optical fiber 12 is passed into the fine hole of the capillary 8, the aperture 13 of the press-fitting hole 6 is packed with the solder 14. The fine hole of about 0.1mm for optical fiber insertion is easily formed in the ceramics, such as alumina, by using the ceramics capillary 8 in such a manner. Since the solder 14 is packed into the aperture 13, the hermetic sealing with the small change with lapse of time is possible. The inside surface of the press-fitting hole 6 of the metallic pipe 2 is preferably coated with gold, etc., having good wettability with solder.

Description

[Detailed Description of the Invention] Table of Contents Overview Industrial Application Fields Prior Art Problems to be Solved by the Invention Means for Solving the Problems Implementation Examples Outline of the Effects of the Invention Optical fibers for devices such as optical transceiver modules Regarding the airtight sealing structure of the introduction part, the main purpose is to provide the above structure in which the airtight sealing has little deterioration over time. For example, a metal pipe into which an optical fiber is inserted and fixed is inserted and fixed into the introduction hole of the casing. In the optical fiber introduction section, a large capillary pressure hole is formed in the metal pipe, a ceramic capillary whose length is shorter than the depth of the press-fit hole is press-fitted into the press-fit hole, and the optical fiber is inserted into the fine hole of the ceramic capillary. The opening of the press-fit hole is filled with solder.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hermetically sealed structure for an optical fiber introduction part of a device such as an optical transceiver module.

As a form of device such as an optical transceiver module that has a part where an optical fiber and an optical component such as a waveguide type optical component are optically coupled, an optical fiber is inserted into the module housing from an introduction hole formed in the module housing. There is a configuration in which the tip is connected to a waveguide type optical component or the like. In this type of equipment, it is important to maintain good airtight sealing of the optical fiber introduction part over a long period of time in order to improve the environmental characteristics of the equipment or to improve the optical and electrical characteristics of the equipment. It is.

BACKGROUND OF THE INVENTION FIG. 8 is a sectional view showing an example of a conventional hermetic sealing structure of an optical fiber introduction section. A metal pipe 104 into which an optical fiber 102 is inserted and fixed is inserted and fixed into an introduction hole 108 of a housing 106 . The optical fiber 102 is inserted and fixed into the metal pipe 104 by, for example, filling the pores of the capillary 112 press-fitted into the metal pipe 104 with adhesive, and then inserting the optical fiber 102 into the pores.

Inserting and fixing the metal pipe 104 into the introduction hole 108 is performed by inserting the metal pipe 104 into the introduction hole 108 and welding the entire circumference of the ends of these contact parts. 110 is a coating for the optical fiber 102, and 114 is a lid fixed to the upper surface of the housing 106 by, for example, welding.

Problems to be Solved by the Invention With the above-mentioned conventional technology, there is a problem in that the hermetic seal between the metal pipe and the casing deteriorates little over time, but the hermetic seal between the optical fiber and the metal pipe deteriorates greatly over time. Ta.

In other words, since the metal pipe and the housing are hermetically sealed by welding, there is little deterioration over time, whereas optical fibers are fixed with adhesive, so they are susceptible to air leakage due to the influence of humidity outside the housing. The seal could deteriorate over time.

The present invention was created in view of the above circumstances, and an object of the present invention is to provide an airtight sealing structure for an optical fiber introduction part in which hermetic sealing is less likely to deteriorate over time. Purposes other than this purpose will become clear from the description below.

Means for Solving the Problem The above-mentioned technical problem is solved by any one of the first to third configurations shown below.

In the first structure, a capillary press-fit hole is formed in the metal pipe in an optical fiber introduction section in which a metal pipe into which an optical fiber is inserted and fixed is inserted and fixed into an introduction hole of a casing.
A ceramic capillary whose length is shorter than the depth of the press-fit hole is press-fitted into the press-fit hole, an optical fiber is passed through the pore of the ceramic capillary, and the opening of the press-fit hole is filled with solder. .

In the second configuration, a capillary press-fit hole is formed in the first metal pipe in an optical fiber introduction section in which a metal pipe into which an optical fiber is inserted and fixed is inserted and fixed into an introduction hole of a casing, and a capillary press-fit hole is formed in the first metal pipe, and the press-fit hole is A ceramic capillary longer than the length corresponding to the depth is press-fitted into the press-fitting hole, the ceramic capillary protruding from the first metal pipe is inserted and fixed into the second metal pipe, and the optical fiber is inserted into the narrow part of the ceramic capillary. The opening of the second metal pipe is filled with solder through the hole.

In the third configuration, in the optical fiber introduction section in which the metal pipe into which the optical fiber is inserted and fixed is inserted and fixed into the introduction hole of the casing, there is a fine hole and an opening with a larger diameter in the longitudinal direction of the metal pipe. At least a portion of the metal pipe near the opening is formed to have a small diameter, an optical fiber is passed through the pore, and the opening is filled with solder.

According to the first configuration, a ceramic capillary whose length is shorter than the depth of the press-fit hole is used, so when this ceramic capillary is press-fitted into the press-fit hole, the portion of the press-fit hole where the ceramic capillary is press-fitted An opening is formed in a shallower portion. Therefore, by filling this opening with solder, it is possible to achieve an airtight seal between the optical fiber and the metal pipe with little deterioration over time. The reason why a ceramic capillary is used is that it is easy to form a pore (about 11 mm in diameter) for inserting an optical fiber in ceramic such as alumina. According to a preferred embodiment,
A coating of gold or the like with good solder wettability is formed on the press-fit hole of the metal pipe and the portion of the optical fiber located inside the press-fit hole.

Even in the case of the second configuration, since the space between the optical fiber and the second metal pipe is filled with solder, a good hermetic seal between the optical fiber and the metal pipe can be achieved. In this case, hermetic sealing between the first metal pipe and the second metal pipe can be effectively achieved by welding, brazing, etc., as in the case of the prior art.

Even in the case of the third configuration, since the opening of the metal pipe is filled with solder, a good airtight seal is achieved. In the case of the third configuration, at least the part near the opening of the metal pipe is formed to have a small diameter, so when filling the opening with solder, heat diffusion is suppressed due to the large thermal resistance of the metal pipe. , it becomes possible to easily fill with solder. That is, in the case of the third configuration, less heat is required to fill the opening with solder, or the filling operation can be completed in a shorter time.

In the case of the first or second configuration, it is not necessary to form a pore with a diameter of about 0.1 aun in order to directly insert the optical fiber into the metal material, so it is easy to realize these configurations.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a sectional view of an optical fiber introduction part showing an embodiment of the first configuration. Reference numeral 2 denotes a metal pipe in which a covering insertion hole 4 and a capillary press-fitting hole 6 having a larger diameter than the covering insertion hole 4 are formed, and the metal pipe 2 is made of stainless steel, for example. Reference numeral 8 denotes a ceramic capillary made of ceramic such as alumina, and this ceramic capillary 8 is press-fitted into the capillary press-fit hole 6 so as to come into contact with the stepped portion between the capillary press-fit hole 6 and the coating insertion hole 4. The ceramic capillary 8 has a pore with a diameter of about 1 mm for inserting an optical fiber. The optical fiber 12 from which the coating 1O is removed from the tip end is passed through the pore of the ceramic capillary 8, and the coating 10 is fixed in the coating insertion hole 4 with an adhesive. Ceramic capillary 8
is shorter than the length corresponding to the depth of the press-fit hole, so when the ceramic capillary 8 is press-fit deep into the press-fit hole 6 as described above, an opening 13 is formed in the press-fit hole 6. Therefore, by filling the opening i13 with the solder 14 using a high frequency heater, a laser heater, etc., the optical fiber 12 and the metal pipe 2 can be hermetically sealed. The wettability of molten solder to quartz, which is the material of the optical fiber 12, and stainless steel, which is the material of the metal pipe 2, is generally not good. The wall surface of the optical fiber 12 and the surface of the optical fiber 12 are plated with gold to improve wettability with molten solder.

The metal pipe 2 into which the optical fiber is inserted and fixed has an insertion hole 1 formed in the side wall surface of a housing 16 made of metal, for example.
The metal pipe 2 and the housing 16 are hermetically sealed by laser welding the entire circumference of the insertion portion as shown by A.

In this example, a waveguide type optical component is placed and fixed inside the housing 16. This optical component includes a waveguide substrate 20 made of LiNbO3 or the like, and a high refractive index leading waveguide 22 formed on the waveguide substrate 20 by diffusing Ti or the like, and is introduced into a housing 16. The end of the optical fiber 2 is optically coupled to the end of the waveguide 22 using an optical adhesive or the like. Reference numeral 24 denotes a lid provided on the upper surface of the housing 16, and the lid 24 is fixed to the housing 16 by, for example, welding.

Since the hermetic sealing between the lid 24 and the casing 16 and between the casing 16 and the metal pipe 2 can be achieved by welding the metal materials together, good hermetic sealing properties can be achieved in the same manner as in the case of the prior art. is maintained stably over a long period of time. In addition, in this embodiment, since solder is used to hermetically seal the optical fiber 12 and the metal pipe 2, it is possible to stably maintain good hermetic sealing characteristics for this portion over a long period of time. This example and ceramic capillary 8
When compared with the case where solder is directly filled without using a solder, this embodiment is superior in that the molten solder does not come into contact with the adhesive used to fix the covering IO.

Another embodiment of the first structure will be explained with reference to FIG.

In this embodiment, at least a portion 2a of the metal pipe 2 near the opening 13 of the press-fit hole is formed to have a small diameter, so that the wall thickness of the metal pipe in this portion is thin. This increases the thermal resistance at the tip of the metal pipe 2, thereby suppressing heat diffusion when filling the opening 13 with the solder 14, thereby making it possible to shorten the working time. In this example, by providing a step on the outer circumference of the metal pipe 2, the part near the opening 13 is formed to have a small diameter, but by providing a groove around the entire circumference near the tip of the metal pipe 2, the opening The portion near 13 may be formed to have a small diameter.

Still another embodiment of the first configuration will be described with reference to FIG.

In this embodiment, the metal pipe 2, the housing 6, and the lid 24 are not fixed to each other by welding, but by soldering, brazing, or fusion using low-melting glass. When joining members by these means, increasing the contact area between the members and the brazing filler metal etc. is effective in increasing the joining force. Therefore, in this embodiment, a counterbore hole 26 with a larger diameter than the insertion hole 18 is formed on the outside of the insertion hole 18 of the casing, and a chamfered portion 28 is provided on the casing 16 side of the lid 24. We are trying to increase the bonding force.

An embodiment of the second configuration will be explained with reference to FIG. In this example, a capillary press-fit hole 32 is formed in the first metal pipe 30, and a ceramic capillary 34 whose length is longer than the depth of the press-fit hole 32 is press-fit deep into the press-fit hole 32. A ceramic capillary 34 protruding from the first metal pipe 30 is inserted and fixed into a second metal pipe 36.

This insertion and fixation is performed by brazing the entire circumference of the contact portion between the first metal pipe 30 and the second metal pipe 36. The length of the second metal pipe 3 is longer than the length of the portion of the ceramic capillary 34 that protrudes from the first metal pipe 30.
If the length of the metal pipe 6 is made longer, the opening 38 will be formed in the second metal pipe 36 as in the case of the first structure.
By filling this opening 38 with solder 40, the optical fiber 12 and the second metal pipe 36 are hermetically sealed. Further, the airtight seal between the first and second metal pipes 3036 is good because the entire circumference is brazed.

The first metal pipe 30 is welded to the metal ring 42 all around, and in this state, the first metal pipe 30 is loosely fitted into the insertion hole 44 formed in the side wall of the housing 16 . By making the inner diameter of the insertion hole 44 larger than the outer diameter of the first metal pipe 30, the optical coupling of the optical fiber 12 is achieved by sliding the metal ring 42 in close contact with the side surface of the housing 16. When performing this, optical axis adjustment is easy. metal ring 42
After the optical axis adjustment described above, the entire circumference of the housing 16 is laser welded. As a result, the inside of the housing 16 is hermetically sealed as in the case of the first configuration.

When the optical fiber 12 is passed through the pore of the ceramic capillary 34, the tip of the optical fiber 12 may be damaged, and this makes it difficult to achieve good optical coupling between the optical fiber 12 and the optical component. Therefore, in such a case, after the optical fiber 12 is passed through the ceramic capillary 34, the tip end 12a of the optical fiber 12 is heated by electric discharge to correct the tip shape.

C0 at the joint part of the metal ring 42 by welding etc.
, 5 or more makes welding easier and increases the joint strength.

Another embodiment of the second configuration will be described with reference to FIG.

In this example, a groove 36a is formed around the entire circumference of the second metal pipe 36 to facilitate the soldering process, as described with reference to FIG. At least a portion near the opening 38 is made to have a small diameter. This suppresses thermal diffusion during solder filling, making the solder filling operation easier. As in the case of FIG. 2, by providing a step on the outer periphery of the second metal pipe 36, the corresponding portion of the second metal pipe 36 may be formed to have a small diameter.

An embodiment of the third structure will be explained with reference to FIG. In this example, an optical fiber and a metal pipe are integrally formed to enable airtight sealing of the metal pipe. In the configuration shown in FIG. 6(a), a coating insertion hole 48, a fiber insertion hole 50, and an opening 52 having a larger diameter than the hole 50 are continuously formed in this order in the metal pipe 46, By forming a step 46a on the outer periphery of the metal pipe 46, the metal pipe 46
At least a portion near the opening 52 has a small diameter. This makes it possible to hermetically seal the optical fiber and the metal pipe as in the previous embodiments, and since the step 46a is formed, heat diffusion during solder filling is suppressed, making the solder filling work easier. Facilitated. When the metal pipe is integrally formed in this way, the amount of heat diffusion during solder filling is extremely large, so forming the portion of the metal pipe 46 near the opening 52 with a small diameter is a good way to prevent solder filling. It is extremely effective in making work easier. Figure 6 (
In the configuration shown in b), instead of providing a step on the outer periphery of the metal pipe 46, a groove 46b is provided all around the outer periphery of the metal pipe 46, so that the opening 52 of the metal pipe 46 is provided with a groove 46b.
The nearby portion is formed to have a small diameter.

By the way, when using, for example, an optical device equipped with the optical fiber introduction part shown in FIG. Possible temperature range may be limited. A preferred embodiment of temperature characteristics suitable for alleviating such restrictions will be described with reference to FIG. In this example, when optically coupling the optical fiber 12 introduced into the housing 16 to the optical waveguide 22, the exposed portion of the optical fiber 12 inside the housing 16 is made longer than the shortest distance, and this portion is Optical coupling is made in the bent state. In general, the linear thermal expansion coefficient of the casing 16 made of metal is larger than that of the optical fiber 12 made of quartz or the like. There is no risk of damage to the optical coupling part, etc. Also,
Even if a device manufactured at room temperature is used at low temperatures, the amount of deflection of the exposed portion of the optical fiber increases only slightly.
There is no effect on the characteristics. By bending the optical fiber and performing optical coupling in this manner, it is possible to realize a device with excellent temperature characteristics.

In the embodiment described above, the end face of the optical fiber introduced into the housing is directly connected to an optical component such as a waveguide to achieve optical coupling, but the optical fiber is cut at the end face of the metal pipe, Polishing the optical fiber together with solder and metal pipe,
The polished end face of the optical fiber and the optical component may be optically coupled using a lens or the like. In this case, the occurrence of reflected light can be suppressed by depositing an antireflection film on the polished end face of the optical fiber.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, the present invention has the effect of providing an airtight sealing structure for an optical fiber introduction part in which hermetic sealing has little deterioration over time.

[Brief explanation of drawings]

Fig. 1 is a sectional view of an optical fiber introducing part showing an embodiment of the first configuration, Fig. 2 is a sectional view of a metal pipe etc. showing another embodiment of the first configuration, and Fig. 3 is a further sectional view of an optical fiber introduction part showing an embodiment of the first configuration. FIG. 4 is a sectional view of the optical fiber introduction section showing another embodiment of the second configuration. FIG. 5 is a metallurgy showing another embodiment of the second configuration. 6 is a sectional view of a metal pipe showing an embodiment of the third configuration; FIG. 7 is a sectional view of an optical fiber introduction part showing an embodiment suitable for improving temperature characteristics; FIG. 8 is an explanatory diagram of the prior art. 2... Metal pipe, 6... Capillary press-fit hole, 8... Ceramic capillary, 12... Optical fiber, 30... First metal pipe, 36... Second metal pipe. 2 Eating bird pipe 8, τu□1 Kukyabiraso 12 Long fiber 1h11 On the back side, colorimetric ho 1 light fufuino〈T in the introduction section
National policy map 1? n

Claims (1)

[Claims] 1. In an optical fiber introduction section in which a metal pipe into which an optical fiber is inserted and fixed is inserted and fixed into an introduction hole of a housing, a capillary press-fit hole (6) is formed in the metal pipe (2). , press-fit a ceramic capillary (8) shorter than the length corresponding to the depth of the press-fit hole (6) into the press-fit hole (6), and insert the optical fiber (12) into the ceramic capillary (8).
A hermetically sealed structure for an optical fiber introduction part, characterized in that the opening (13) of the press-fit hole (6) is filled with solder (14). 2. The structure according to claim 1, wherein at least the opening (13) of the metal pipe (2)
An airtight sealing structure for an optical fiber introduction part, characterized in that a nearby part is formed with a small diameter. 3. In the optical fiber introduction part where the metal pipe into which the optical fiber is inserted and fixed is inserted and fixed into the introduction hole of the housing, the capillary press-fit hole (32) is inserted into the first metal pipe (30).
A ceramic capillary (34) having a length corresponding to the depth of the press-fit hole (32) is press-fitted into the press-fit hole (32), and the ceramic capillary protruding from the first metal pipe (30) is pressed into the press-fit hole (32). The capillary (34) is inserted and fixed into the second metal pipe (36), and the optical fiber (12) is inserted into the ceramic capillary (34).
), and the opening (38) of the second metal pipe (36) is filled with solder (40). 4. The structure according to claim 3, wherein at least a portion of the second metal pipe (36) near the opening (38) is formed to have a small diameter. Stop structure. 5. In the optical fiber introduction section in which the metal pipe into which the optical fiber is inserted and fixed is inserted and fixed into the introduction hole of the housing, there is a small hole (50) and a hole (50) with a larger diameter in the longitudinal direction of the metal pipe (46). an opening (52), and at least the opening (52) of the metal pipe (46).
) A hermetic sealing structure 6 for an optical fiber introduction part, characterized in that the neighboring part is formed to have a small diameter, the optical fiber is passed through the pore (50), and the opening (52) is filled with solder. The structure according to any one of claims 1 to 5, wherein the optical fiber (12) introduced into the housing (16) is bent to optically couple the optical fiber (12). Hermetically sealed structure for the optical fiber introduction section.