JP2003344713A - Optical element module and manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive optical element module that causes no hermetic defect due to peeling of metallization applied on an optical fiber, even at the time of package expansion/contraction generated by a change in operational ambient temperature, and prevents an optical fiber from being broken in the bent part. <P>SOLUTION: In this module, an optical fiber 4 is an optical fiber as it is with the coating removed. The insertion tube 3 through which the core fiber is inserted is caulked to fixedly hold the optical fiber 4. Then, the optical fiber 4 is bent between a ferrule 5 and the insertion tube 3. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element module such as a semiconductor laser module for optical communication or a photodiode module and a method for manufacturing the same.

[0002]

2. Description of the Related Art An example of a conventional method for hermetically sealing an optical fiber insertion tube portion in a package of an optical element module will be described with reference to FIGS.

FIG. 3 is a vertical cross-sectional view of an essential part of an optical element module when the optical element 1 is a semiconductor laser. An insertion tube 3 is attached to a package 2 made of metal, ceramics or the like for housing the optical element 1 by a joining means such as silver brazing.
At the tip of the optical fiber 4, the first holding optical fiber 4
The ferrule 5 is fixed and introduced from the outside of the package 2 into the inside of the package 2 through the inner diameter of the insertion tube 3. As an example, the optical fiber 4 and the first ferrule 5 are metalized 11 by gold plating or the like (see US Pat. No. 5,619,609).

As another example, the metallization 11 of the optical fiber 4 is solder-coated, and
The fourth ferrule 5 and the first ferrule 5 are fixed by solder 6 (see Japanese Patent No. 2614018). The first ferrule 5 is fixed on the stem 8 together with the ferrule holder 7 after aligning the optical fiber 4 with the optical axis of the optical element 1. The stem 8 is mounted on the thermoelectric cooling element 9 in order to control the operating temperature of the optical element 1. The optical fiber 4 is led out from the insertion tube 3 which is a take-out port on the rear end side, and the solder 6 is supplied from the solder inflow port 10 of the insertion tube 3 so as to be hermetically sealed and fixed.

On the other hand, FIG. 4 is a longitudinal sectional view of a main part of a conventional example in which an optical fiber is fixed in a curved state in a package. The optical fiber 4 is held by the first ferrule 5 on the tip side and the second ferrule 13 on the insertion tube 3 side of the package 2, and the first ferrule 5, the optical fiber 4, and the second ferrule 13 The optical fibers 4 are fixed by solder 6, respectively, and particularly, a hermetic seal is achieved between the second ferrule 13 and the optical fiber 4. The first ferrule 5, the optical fiber 4, and the second ferrule 13 are provided with a metallization 11 such as gold plating for soldering.
Has been applied.

As a method of manufacturing this optical module, the first ferrule 5 and the ferrule holder 7 together with the stem 8 are used.
After fixing it to the upper side, the second ferrule 13 is pushed from the outside of the package 2 of the insertion tube 3 into the inside of the package 2,
The optical fiber 4 between the ferrule 5 and the second ferrule 13 is held in a curved state, and the second ferrule 1
3 is hermetically sealed and fixed to the insertion tube 3 with solder 6. The second ferrule 13 is required as a grip for bending the optical fiber 4 inside the package 2.

[0007]

However, in the conventional optical element module shown in FIG. 3, the optical fiber 4 is fixed in a straight line in the package 2 substantially horizontally with respect to the optical axis. When the package 2 expands and contracts due to the change of, the optical fiber 4 in the package 2 is pulled around the first ferrule 5 fixing portion as an axis and receives repeated stress such as compression, and the solder 6 and the optical fiber 4 inside the insertion tube 3 The first problem is that the metallization 11 of the optical fiber 4 is peeled off during the period, which causes poor airtightness.

Further, in the conventional optical element module shown in FIG. 4, the first problem can be solved by bending the optical fiber 4 in the package 2, but the optical fiber metalized with metal 11 is applied. 4 becomes weaker to bending stress due to increased hardness, and the optical fiber 4
A second problem of being easily broken occurred. Furthermore, it is expensive because the optical fiber 4 and the ferrule 5 need to be metallized 11 such as gold plating for soldering.

An object of the present invention is to eliminate the above-mentioned problems of the prior art. Even when the package expands or contracts due to a change in operating environment temperature, a poor airtightness occurs due to the metallization peeling applied to the optical fiber. It is an object of the present invention to provide an optical element module that does not cause breakage of an optical fiber at a curved portion and is inexpensive.

[0010]

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a package having an insertion tube made of metal for inserting an optical fiber therein and having the optical element housed therein. An optical element module in which the tip end of an optical fiber is fixed to a position where it is optically coupled with, the optical fiber is led out from the insertion tube, and the optical fiber lead-out portion of the insertion tube is hermetically sealed. In the optical fiber in the package, an optical fiber with the sheath removed is inserted, and the lead-out portion of the insertion tube is caulked to hermetically seal, and the optical fiber in the package is In addition, a metal base layer is provided on the inner surface of the insertion tube base material in the lead-out portion of the insertion tube, and the base layer is provided at the boundary between the base layer and the insertion tube base material. Composition ingredients of Wherein the composition components of the insertion tube preform is provided with a diffusion layer formed by diffusing.

Further, a metal foil or a metal thin plate as a base layer is laminated on the surface of a plate-shaped base material to be the insertion tube, and the metal foil or metal thin plate and the base material of the insertion tube are pressed against each other. A step of forming a diffusion layer in which the composition components of the underlayer and the insertion tube base material are diffusion-bonded to each other at the boundary between the underlayer and the insertion tube base material, and the plate-shaped insertion tube formed with this underlayer To a cylindrical shape, and welding the seam, and
The method further includes the step of caulking and fixing the optical fiber element wire inserted through the insertion tube through the underlayer.

That is, according to the present invention, the bending of the optical fiber reduces the tensile stress and compressive stress on the optical fiber generated when the package expands and contracts due to the change in ambient temperature, and the optical fiber is metalized. Since the absence of metallization prevents airtightness due to peeling of the metallization, the first problem can be solved, curing of the optical fiber by metallization is prevented, and breakage of the optical fiber when the optical fiber is curved in the package is suppressed. This is a solution to the problem.

Further, according to the present invention, since it is not necessary to perform metallization such as gold plating on the optical fiber or the ferrule, the optical element module is inexpensive and has a simple structure. Therefore, the optical element module is manufactured by a simple method. be able to.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical cross-sectional view of an essential part of an optical element module of the present invention. A semiconductor laser or the like as the optical element 1 is housed and fixed in the package 2. A ferrule 5 for holding the optical fiber 4 is joined to the tip of the optical fiber 4 by a low melting point glass 12,
After the optical fiber 4 is guided through the inner diameter of the insertion tube 3 into the package 2 and the optical element 1 fixed on the stem 8 and the optical fiber 4 are optically aligned, the stem is inserted through the ferrule holder 7. 8 is YAG welded and fixed on top.

The optical fiber 4 has an elemental wire made of glass in the coating portion, and comprises an exposed portion 40 of the elemental wire with the coating portion removed in the package. The exposed portion 40 is
No treatment for hardening by metallizing the surface is performed, and the surface is elastic and bendable.

The ferrule 5 can YAG laser welding, and was approximated to the low melting point glass 12 for bonding the optical fiber 4 5 to 10 × 10 ^- a metal material such as Kovar material having a thermal expansion coefficient of the ⁶ / ° C. Consists of optical fiber 4
Since the ferrule 5 and the ferrule 5 are joined by using the low melting point glass 12, the ferrule 5 is not metallized.

The low melting point glass 12 for joining the optical fiber 4 and the ferrule 5 is made of amorphous glass having a transition point of 280 to 320 ° C., and is melted and fixed by means such as high frequency induction heating. Instead of the low melting point glass 12, a joining means made of a ceramic material such as alumina which is also an inorganic material may be used.

The stem 8 is mounted and fixed on a thermoelectric cooling element 9 for controlling the temperature of the optical element 1.

The package 2 is generally used for optical communication and is used for an optical element module that requires hermetic sealing. The material is a ceramic material or a Kovar material. The package 2 has a box shape composed of a bottom surface portion and a side wall portion, and further has a hole portion for joining the insertion tube 3.

The insertion tube 3 is made of Kovar, copper, stainless steel,
It is made of at least one metal selected from iron / nickel alloy, iron / nickel / chromium alloy, iron / chromium alloy, aluminum, and magnesium, and is fixed to the package 2 by a joining means such as a silver brazing material. The fixing to the package 2 may be adhesive bonding or solder bonding.

An underlayer 3a is provided on the inside of the insertion tube 3 by pressure contact as described later, and at the boundary between this underlayer and the base material of the insertion tube 3, the composition components of the underlayer 3a and the base material of the insertion tube 3 are provided. A diffusion layer 3b composed of only composition components is provided. Examples of the material of the base material include Kovar, iron / nickel alloy, iron / nickel / chromium alloy, iron / chromium alloy and the like for metals, and copper, aluminum, magnesium and the like for non-ferrous metals. The material of the underlayer 3a is, for example, gold,
There are silver, copper, lead, nickel, chromium, tin, etc., and since the elemental wire of the optical fiber 4 is directly caulked and fixed, a material with excellent ductility is suitable, and damage to the fiber during caulking and fixing is minimized. Can be suppressed. The diffusion layer 3b is a combination of the base material and the base layer 3a. By providing the diffusion layer 3b, the strength of the base material of the layer-passing tube 3 and the base layer 3a is improved. That is, it is possible to improve the strength of the base layer 3a and hermetically seal the damage of the strand of the optical fiber 4 to the minimum. Next, the insertion tube 3 is shown in FIGS.
It can be manufactured by the method as shown in.

First, as shown in FIG. 2 (a), a metal foil or a metal thin plate to be the base layer 3a is placed on the surface of the base material of the plate-shaped insertion tube 3, and this metal foil or metal thin plate and the insertion tube are inserted. Diffusion bonding is performed by pressing the base material of No. 3 while rolling it. At this time, the thicknesses of the base material of the insertion tube 3 and the base layer 3a can be freely set by changing the thicknesses of the base material and the metal foil or the metal thin plate of the insertion tube 3 and the applied pressure. Moreover, its thickness becomes stable. In addition, when the base material of the insertion tube 3 and the underlayer 3a are pressed against each other with a high pressure, strong bonding becomes possible, and there is also a problem of peeling such as conventional metallization such as vapor deposition or sputtering, or ion plating or plating. Lost. The suitable range of the pressure of this pressure contact varies depending on the material and the above thickness, but generally the pressure after the pressure is applied is 80% or less of the thickness before the pressure is applied. Is desirable.
By doing so, more reliable diffusion bonding becomes possible. Here, diffusion bonding is a composition component (atom) that constitutes a metal by pressurizing and heating the two metals in contact with each other.
However, it is a phenomenon that thermal diffusion occurs between the metals and they are joined together.

Next, as shown in FIG. 2B, the insertion tube 3 is rolled into a cylindrical shape, and the seam 30 is welded by TIG welding or CO ₂ welding to form the tubular insertion tube 3. Since the outer diameter of the pipe at this time is in a state before the later-described drawing process, the outer diameter is larger than that of the final product. Next, a drawing process as shown in FIG. 2C is performed. Insert the tubular insertion tube 3 into the die 1
It is pulled out through 5 until the outer diameter φD reaches a prescribed size, and a long tubular insertion tube 3 is formed. Here, it is possible to freely set the outer diameter by changing the size of the die 15. Further, it is possible to stably produce a highly accurate shape.

The long tubular shape after the drawing is shown in FIG.
The insertion tube 3 is manufactured by cutting to a prescribed length h by cutting (cutting) as shown in (d).

The insertion tube 3 thus manufactured is brazed with silver to the hole of the package 2. In the next step, the optical element 1, the ferrule holder 7, and the stem 8 which have been mounted on the thermoelectric cooling element 9 in advance are packaged.
After being mounted inside, the optical fiber 4 is guided through the inner diameter of the insertion tube 3 into the package 2, and after aligning the optical element 1 fixed on the stem 8 and the optical fiber 4 at the position where they are optically coupled, the ferrule is placed. YAG is welded and fixed on the stem 8 via the holder 7, and then the end portion (lead-out portion) of the side surface of the insertion tube 3 is caulked to hold and fix the strand of the optical fiber 4 in the package 2 and a sealing cap. 16 is welded to the package 2 by resistance welding all around to hermetically seal the inside of the package 2.

The central axis a of the insertion tube 3 fixed to the package 2 is disposed below the package 2 with respect to the optical axis b of the optical element 1. Airtightly sealed by caulking and fixing the insertion tube 3 and the optical fiber 4,
Since the central axis “a” and the optical axis “b” are set to have a positional relationship such that they do not coincide with each other, the exposed portion 40 of the optical fiber 4 forms the curved portion 4 a that naturally curves in the vertical direction in the package 2. Become.

By providing the curved portion 4a in this way, when the package 2 expands or contracts due to a change in operating environment temperature, the tensile and compressive stress of the optical fiber 4 applied to the tip fixing portion of the optical fiber 4 in the package 2 is relaxed. Is
It is possible to suppress fluctuations and deterioration of the optical fiber output.

In this case, the amount of expansion or contraction of the package 2 made of, for example, a ceramic material with respect to the optical axis is about 2 μm, but in order to alleviate the tensile and compressive stress on the optical fiber 4 and prevent the deterioration of the optical fiber output. Requires a sufficient bending radius, and the bending radius of the bending portion 4a is 10 mm.
The following is desirable.

Further, the optical fiber 4 has the package 2
In the inside, there is an exposed portion 40 in which the bare wire from which the coating has been removed is exposed, and since the metallization is not applied and the exposed portion 40 is not cured, there is no deterioration of the allowable bending stress of the optical fiber 4, and the curved portion 4a Can be prevented from breaking. Further, since the ferrule 5 having a thermal expansion coefficient similar to that of the low melting point glass for joining the optical fiber 4 is used, cracks and the like at the interface between the ferrule 5 and the low melting point glass can be prevented at the same time.

As described above, according to the present invention, the optical fiber 4 is not metallized, and the curved portion 4a is provided as it is with the bare wire from which the coating is removed.
Since the optical fiber 4 is formed by caulking and fixing the insertion tube 3, it is possible to prevent the airtightness due to the metallization peeling of the hermetically sealed portion and prevent the optical fiber from breaking in the curved portion 4a. Since the ferrule 5 or the second ferrule 13 also does not require metallization such as gold plating, the manufacturing process can be simplified and simplified, and low-cost module manufacturing can be realized.

As another embodiment, when the second ferrule 13 as shown in the conventional example of FIG. 4 is used,
The second ferrule 13 and the optical fiber 4 are connected to the low melting point glass 1
It suffices to join at 2, and the metallization 11 can be eliminated.

[0032]

EXAMPLE An optical element module shown in FIG. 1 was manufactured as an example of the present invention. In FIG. 1, an insertion tube 3 made of a Kovar material for inserting an optical fiber 4 is fixed to a package 2 also made of a Kovar material with a silver brazing material.

The outer diameter of the insertion tube 3 is φ1.0 mm, the inner diameter is φ0.15 mm, Au material is used for the underlayer 3a, and the diffusion layer 3 is formed between the insertion tube 3 base material and the underlayer 3a by a pressure welding method.
b is formed. A thermo-electron cooling element 9 for controlling the temperature of the semiconductor laser 1 is fixed in the package 2 by soldering, a stem 8 made of Kovar material is provided on the thermo-electron cooling element 9, and a semiconductor laser is provided on the stem 8. The optical element 1 consisting of was also mounted and fixed by soldering.

A ferrule 5 having an outer diameter of 1 mm for holding the optical fiber 4 is provided at the tip of the optical fiber 4.
, Which have been joined in advance by a high-frequency induction heating means with a low-melting glass 12, and are introduced into the package 2 through the insertion tube 3 together with the ferrule 5 joined to the tip of the optical fiber 4, and the ferrule 5 is placed on the stem 8. Place on.

Then, after aligning the light emission of the semiconductor laser 1 and the optical fiber 4 in the package 2 at the position where they are optically coupled, the ferrule holder 7 is welded onto the stem 8 by the YAG laser, and the ferrule 5 is attached. Welded to.

The low melting point glass 12 has a coefficient of thermal expansion of 6.9.
^Amorphous glass having a temperature of × 10 ⁻⁶ / ° C. and a transition point of 298 ° C. was adopted, and the ferrule 5 adopted a Kovar material as a metal material having a thermal expansion coefficient close to that of the low melting point glass 12.

Next, the insertion tube end 14 was caulked in the axial center direction to hold and fix the optical fiber 4 in the package 2 and hermetically seal it.

As described above, the ferrule 5 is fixed by using the low-melting glass 12, the optical fiber 4 is fixed by caulking the insertion tube 3, and is hermetically sealed. Therefore, it is not necessary to perform metallization such as gold plating. . In addition, ferrule 5
Even a metal such as a Kovar material that is easily corroded by oxidation is hermetically sealed in the package 2 and therefore need not be metallized. The central axis of the insertion tube 3 fixed to the package 2 is about 0.
It is located 4 mm below, so the optical fiber 4
Naturally bends up and down in the package 2, and the bending radius of the bending portion 4a is about 9 mm. Here, in order to compare the embodiment of the present invention shown in FIG. 1 with the conventional structure shown in FIG. 3, a temperature cycle test is carried out at −40 to + 85 ° C., 10
The airtightness before and after 00 cycles was measured. The results are shown in Table 1, and it can be seen that the airtightness is kept high in the examples of the present invention as compared with the conventional structure and there is no deterioration with time.

The above results are caused by the fact that the optical fiber 4 is fixed in a straight line in the conventional structure in the package 2 substantially horizontally with respect to the optical axis, and the package 2 expands and contracts due to a change in ambient temperature. Therefore, the optical fiber 4 in the package 2 is pulled around the fixing portion of the first ferrule 5 and is subjected to repeated stress such as compression, and the metallization 11 of the optical fiber 4 between the solder 6 inside the insertion tube 3 and the optical fiber 4 is performed. Peeled off and the airtightness deteriorated.

[0040]

[Table 1]

[0041]

As described above, according to the present invention,
An optical element is housed inside, and a package equipped with a metal insertion tube for inserting an optical fiber is fixed to the tip of the optical fiber at a position where it is optically coupled to the optical element, In an optical element module in which an optical fiber is led to the outside, and the optical fiber lead-out portion of the insertion tube is hermetically sealed to fix the optical fiber to a package, the optical fiber in the package has a covering portion. While removing and exposing the strands, the optical fiber is fixed by caulking the lead-out portion of the insertion tube, and by bending the strands of the optical fiber, during expansion and contraction of the package due to changes in ambient temperature. The tensile and compressive stress of the generated optical fiber is relieved, the airtightness due to the metallization peeling is prevented, and the optical fiber is not cured by the metallization. It has become possible to prevent the breakage at the time of optical fiber curved in package.

Further, since the metallization such as gold plating is unnecessary, it becomes possible to provide an inexpensive optical element module.

Furthermore, the optical element module can be easily manufactured at low cost because it is a simple manufacturing method in which the wires are caulked and fixed by the insertion tube.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part showing an optical element module of the present invention.

2 (a) to 2 (d) are views showing manufacturing steps of the insertion tube of the present invention.

FIG. 3 is a longitudinal sectional view of a main part showing a conventional optical element module.

FIG. 4 is a longitudinal sectional view of a main part showing a conventional optical element module.

[Explanation of symbols]

1: Optical element 2: Package 3: Insertion tube 3a: Underlayer 3b: diffusion insertion 4: Optical fiber 4a: curved portion 5: First ferrule 6: Solder 7: Ferrule holder 8: Stem 9: Thermoelectric cooling element 10: Solder pouring port 11: Metallization 12: Low melting point glass 13: Second ferrule 14: End of insertion tube 15: Dice 16: Sealing cap 30: seam 40: Exposed part

Claims (3)

[Claims] 1. A front end portion of an optical fiber is fixed to a position where the optical fiber is inserted into a package having an insertion tube made of metal for inserting the optical fiber therein and containing the optical element therein. With the above, the optical fiber is led out from the insertion tube to the outside, and an optical element module is formed by hermetically sealing the optical fiber lead-out portion of the insertion tube, wherein the optical fiber in the package is a coating. An optical element module characterized in that an optical fiber element wire in the package is curved by inserting an element wire from which the portion has been removed, caulking a lead-out portion of the insertion tube to perform airtight sealing, and curving the optical fiber element wire in the package. 2. An underlayer made of metal is provided on the inner surface of the insertion tube base material at the lead-out portion of the insertion tube, and the composition component of the underlayer and the composition described above are provided at the boundary between the underlayer and the insertion tube base material. The optical element module according to claim 1, further comprising a diffusion layer formed by diffusing the composition components of the insertion tube base material. 3. The optical element module according to claim 1 or 2, wherein a metal foil or a metal thin plate serving as an underlayer is laminated on the surface of the plate-shaped base material to be the insertion tube, and the metal foil or By pressing the thin metal plate and the base material of the insertion tube under pressure, a diffusion layer is formed at the boundary between the base layer and the insertion tube base material by diffusion bonding of the composition components of the base layer and the insertion tube base material. A step, a step of welding the seam by rolling the plate-shaped insertion tube having the underlayer formed into a cylindrical shape, and
A method of manufacturing an optical element module, comprising a step of caulking and fixing an optical fiber element wire inserted into the insertion tube through the underlayer.