JP2003255196A - Optical module and method of assembling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the reliability of a high-temperature, high-humidity test of an optical module which has an optical fiber fixture 1 fixed to a holder 3 with an adhesive 4. <P>SOLUTION: The optical module, equipped with a laser diode 9 and/or a photodiode 10 and also equipped with the optical fiber fixture 1, is characterized in that the optical fiber fixture 1 is fixed to the holder 3 by using at least one connecting component. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical module used for optical communication and an assembling method thereof.

[0002]

2. Description of the Related Art Generally, an optical module has a structure in which an optical signal emitted from a laser diode of a semiconductor element is coupled to an optical fiber, or conversely, an optical signal emitted from an optical fiber is coupled to a photodiode. Take the configuration. At this time, it was devised to increase the coupling efficiency and minimize the optical coupling loss. This devising method will be described with reference to FIG. 5, which is a conventional optical module. One of the measures to reduce the optical coupling loss is the optical fiber fixture 1
There is a method of giving an angle to the end face 1a. This is because the characteristics of the laser diode become unstable when it receives reflected light or stray light. Therefore, the end face 1a of the optical fiber fixture 1 is angled to prevent reflected light and stray light.
However, by making the end surface 1a of the optical fiber fixture 1 have an angle, the optical coupling efficiency has been lowered.
On the other hand, the optical coupling efficiency is secured by inclining the optical fiber fixture 1 itself as a whole. As the method, the optical fiber fixture 1 is inserted into the holder 2 that is obliquely penetrated, and the gap is filled with an adhesive to integrate the optical fiber fixture 1 and the holder 2.

An example is a bidirectional optical module.
The bidirectional optical module is characterized in that it can transmit and receive a signal through an optical fiber of one core in optical communication. FIG. 5 shows a cross-sectional view of a conventional technique used in a conventional bidirectional optical module. Further, FIG. 5 shows operations in the transmission direction 21 and the reception direction 22. The transmission direction 21 means that the signal light emitted from the laser diode 9 passes through the lens 6, passes through the wavelength selection element 8, and then is coupled to the optical fiber end face 1 a of the optical fiber fixture 1, and the reception direction 22. Means that the signal light emitted from the optical fiber end face 1a of the optical fiber fixture 1 is reflected by the wavelength selection element 8 and received by the photodiode 10.

[0004]

In the above-mentioned conventional optical module, the optical fiber fixture 1 and the holder 2 are generally fixed by the adhesive 4. Optical fiber fixture 1
There are YAG welding fixing, solder fixing, low melting point glass fixing, etc. for fixing the holder 2 and the holder 2, but the optical fiber fixture 1
Has an optical fiber, and an adhesive 4 is often used for fixing the optical fiber. For this reason, high-temperature treatment requires adhesive 4
However, the adhesive 4 has been mainly used for fixing the optical fiber fixture 1 and the holder 2 to each other.
However, the adhesive 4 is weak in the environment such as temperature and humidity,
It caused a cause of failure called misalignment of the optical axis of the optical module. Particularly, the high temperature and high humidity test is a severe test, and swelling of the adhesive 4 due to humidity has been a problem. Therefore, it is necessary to suppress the optical axis misalignment due to the swelling of the adhesive 4.

The present invention has been made in view of the above-mentioned points, and an object thereof is to provide a very small optical axis misalignment, a small optical coupling loss, and stable characteristics in a severe high temperature and high humidity environment. It is extremely easy to provide a highly reliable optical module.

[0006]

In view of the above problems, the present invention provides an optical module including a light emitting / receiving element and an optical fiber fixing device, wherein the optical fiber fixing device is used as a holder by using at least one fastener. The holder is fixed and the holder is fixed to the main body case.

An optical module including a light emitting / receiving element and an optical fiber fixing tool is characterized in that the optical fiber fixing tool has a fastening structure and is fixed to a holder, and the holder is fixed to a main body case.

Further, the optical fiber fixture is characterized by being inclined with respect to the axial direction of the holder and being fixed by an adhesive.

Further, the shape of the tip of the above-mentioned fastening component is characterized by having a concave portion and / or a convex portion.

Further, in an optical module including a light emitting / receiving element and an optical fiber fixing tool, a holder for fixing the optical fiber fixing tool is provided with an oblique through hole, and the optical fiber fixing tool is inserted into the through hole, It is characterized in that it is fixed with a fastening component, and after the adhesive is filled and fixed in the gap between the holder and the optical fiber fixture, the holder is welded to the main body case.

The light emitting / receiving element in the present invention means a light receiving element, a light emitting element, or both.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

FIG. 1 shows a block diagram of a bidirectional optical module which is an embodiment of the present invention. Module body case 1
1, a wavelength selection element 8 is arranged, a laser diode 9 as a light emitting element for transmitting an optical signal, a photodiode 10 as a light receiving element for receiving an optical signal, and a light source via a lens 6 and a lens 7 in the main body case 11 as well. After axis alignment, YA
It is fixed by G welding, resistance welding, press fitting, etc. Further, as a propagation of these optical signals, a holder 2 to which an optical fiber fixture 1 having an optical fiber mounted thereon is fixed to the main body case 11 of the module and then YAG welding 5 is performed.

In the wavelength selection element 8, a multilayer film for transmitting and reflecting an optical signal is formed on a white plate or a plate glass of BK7.

The laser diode 9 is a semiconductor element that converts an electric signal into the transmitted light 21, and in some cases, a spherical lens or an aspherical lens is integrally fixed to the front surface of the element. Lens 6
If it is not fixed, the main body case 1 of the module
A similar lens 6 to 1 is fixed in advance.

Similarly, the photodiode 10 receives the received light 2
There is also an element for converting 2 into an electric signal, in which a spherical lens or an aspherical lens is integrally fixed to the front surface of the element. When the lens 7 is not fixed, a similar lens 7 is fixed in advance to the main body case 11 of the module.

The optical fiber fixture 1 is inserted into the oblique through hole of the holder 2 and is integrally fixed by the fastening component 3.

The optical fiber fixture 1 is constructed by holding an optical fiber in a metal ferrule, and between the hardness of the metal forming the ferrule of the optical fiber fixture 1 and the hardness of the fastening component 3, a fastening component is provided. It is desirable to provide a hardness difference of hardness 3 ≧ hardness of the optical fiber fixture 1. The reason is,
This is because by satisfying the above formula, the fastening component 3 can surely bite into the optical fiber fixture 1 and eliminate play. If the hardness of the fastening component 3 is lower than the hardness of the optical fiber fixture 1, the tip shape of the fastening component 3 will be crushed when the optical fiber fixture 1 is fixed by the fastening component 3, and it will not be possible to bite and fix. However, when the hardness of the fastening component 3 is too higher than the hardness of the optical fiber fixture 1, the biting part of the fastening component 3 easily enters the inside of the optical fiber fixture 1 and affects the characteristics of the optical fiber fixture 1.
Since looseness easily occurs at the biting portion due to the difference in hardness of the material, the difference in hardness between the optical fiber fixture 1 and the fastening component 3 is 5
It is desirable to keep it within 00HV.

Specifically, the material of the metal forming the ferrule of the optical fiber fixture 1 that achieves these hardness differences is SUS.
304, SUS303, SUS430, stainless steel, SF20T, Kovar, aluminum, etc. are suitable. On the other hand, the material of the fastening component 3 is selected from the same stainless steel, iron, etc. as the metal of the optical fiber fixture 1 and having the above hardness difference.

As shown in FIG. 2, the shape of the tip of the fastening component 3 forms a concave portion and / or a convex portion. Figure 2 (a)
Has a convex biting part 31a and has a sharp tip. This bites well with the optical fiber fixture 1 as described above. FIG. 2B shows a concave portion formed so that the biting portion 32 a at the mountain portion of the circumference bites into the optical fiber fixture 1. Figure 2 (c)
2 has the advantages of FIG. 2 (a) and FIG. 2 (b) because it has a convex portion and a concave portion and has a biting portion 33a and a biting portion 33b. It is expected that the biting force will be higher than in b). Figure 2 (d) shows
Although the biting portion 34a of the convex portion is formed, the biting portion 34a is a flat surface, and it is expected that the biting force is lower than that of the convex portion forming fastening component 31. In FIG. 2E, the protruding biting portion 35 a is formed, and the biting portion 35 a is formed.
a is a bar-shaped protrusion. This convex portion forming fastener 3
5 is by forming a recess in the optical fiber fixture 1,
It is possible to bite by fitting.

The condition common to these fastening parts 3 and more effective in the present invention is that the angle formed by the tip shape of the fastening parts 3 is 45 ° so that the optical fiber fixture 1 can be surely bited.
An angle of ~ 150 ° is desirable.

Further, when these fastening parts 3 are attached to the holder 2, it is important that the fastening parts 3 be attached without looseness, and the fixing may be strengthened by applying an adhesive 4 to the fastening parts 3.

As another embodiment of the present invention, FIG.
As shown in (a), the fastening process 1 is performed on the optical fiber fixture 1 itself.
2 may be given to have a fastening function and fastened to the holder 2. The optical fiber fixture 1 having the fastening process 12 is fastened to the holder 2, and the adhesive 4 is applied and filled in the gap between the optical fiber fixture 1 and the holder 2 as reinforcement.

Further, as shown in FIG. 3B, when the tip shape of the fastening component 3 has a protrusion structure as shown in FIG. 2E, a fastening component receiving process (counterbore) 13 is attached to the optical fiber fixture 1. It is also possible to give and fasten. In this case, it is important that the size of the fastening component receiving process (counterbore) 13 is adjusted to the size of the fastening component 3, and the press-fitting structure further exerts the effect of the present invention.

Further, as shown in FIG. 3 (c), the stepped optical fiber fixture 1 is fastened with the ring-shaped fastening component 3 via the stepped holder 2, whereby the stepped portion 14 and the fastening component 3 are joined. Thus, the optical fiber fixture 1 and the holder 2 can be integrally fixed.

When fixing the optical fiber fixing tool 1 to the holder 2, the optical fiber fixing tool 1 is inserted into the holder 2, the insertion position and rotation position of the optical fiber fixing tool 1 are determined, and the fastening component 3 is tightened and fixed. . After that, the adhesive 4 is applied between these gaps and the through holes of the optical fiber fixture 1 and the holder 2. Then, the adhesive agent 4 is transmitted through the optical fiber fixing tool 1 due to the capillary phenomenon, and is held and filled inside the through hole of the holder 2. In this case, the viscosity of the adhesive 4 is 100 cps to 50
A range of 000 cps is desirable. It is not preferable that the fastening torque of the fastening component 3 is too small or too large. If it is too small, it will not be fixed, and if it is too large, stress may be exerted on the optical fiber inside the optical fiber fixture 1 and characteristic deterioration may occur. For example, when the fastening part 3 is made of a stainless steel material of M1.4 and the tip shape is sharp by forming the protruding biting part 31a as shown in FIG. 2 (a), the tightening torque is in the range of 1 to 8 N · cm. Good to do in.

In the above embodiments, the bidirectional optical module is shown as an example, but the optical module of the present invention is not limited to this, and is applied to various things such as an LD module, a PD module, an isolator module, and an optical switch. be able to.

[0028]

EXAMPLES Here, an experiment was conducted by the following method.

The optical fiber fixture 1 according to the present invention is inserted into a holder 2 which is obliquely penetrated and integrally fixed with a fastening component 3,
The bidirectional optical module of FIG. 1 manufactured by filling the gap with the adhesive 4 and the optical fiber fixture 1 which is a conventional assembly method as a comparative example are inserted into a holder 2 which is obliquely penetrated and adhered to the gap. A bidirectional optical module of FIG. 5 was manufactured in which the agent 4 was filled and integrally fixed without using the fastening component 3.

Under the above conditions, the optical module is subjected to a high temperature and high humidity test at 85 ° C., 85% RH for 1000 hours, and the optical output fluctuation and the photodiode which show the optical axis misalignment between the laser diode 9 and the optical fiber fixture 1 can be seen. 10 and the light-receiving sensitivity fluctuations in which the optical axis misalignment of the optical fiber fixture 1 can be understood are compared. The result is shown in FIG.

FIG. 4A is a graph showing the optical output fluctuation of the optical module of the present invention. FIG. 4B is a graph showing the fluctuation of the light receiving sensitivity of the optical module of the present invention. Figure 4
(C) is a graph showing the optical output fluctuation of the conventional optical module. FIG. 4D is a graph showing the light receiving sensitivity variation of the conventional optical module.

Regarding the result of the optical output fluctuation, it can be seen from FIG. 4 (c) of the prior art that the optical output is decreased after the start of the test, the optical output fluctuations are all biased in the negative direction, and the optical axis is displaced. . On the other hand, in FIG. 4A of the present invention, it can be seen that no large optical output fluctuation is observed and the optical axis shift does not occur. In addition, regarding the result of fluctuations in light receiving sensitivity,
In FIG. 4 (d) of the prior art, it can be seen that the amount of received light is reduced after the start of the test, and the fluctuations in the received light sensitivity are all biased in the negative direction, resulting in an optical axis shift. On the other hand, FIG.
In (b), it can be seen that there is almost no fluctuation in the light receiving sensitivity, and no optical axis deviation occurs.

In other words, with respect to each of the optical output fluctuation which shows the optical axis misalignment on the laser diode 9 side and the light receiving sensitivity fluctuation which shows the optical axis misalignment on the photodiode 10 side, the optical axis misalignment is extremely small. It can be seen that the improvement effect was achieved.

[0034]

As described above, according to the optical module of the present invention, in the optical module including the light emitting / receiving element and the optical fiber fixing tool, the optical fiber fixing tool is at least one fastening component. An optical module with extremely small optical axis misalignment in a high temperature and high humidity test can be realized by fixing the optical module to a holder using.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a bidirectional optical module that is an example of the optical module of the present invention.

2 (a) to 2 (e) are views showing various embodiments of a fastening component used in the optical module of the present invention.

3A to 3C are cross-sectional views showing another embodiment of the present invention.

4 (a) to (d) are graphs comparing the present invention with a conventional example.

FIG. 5 is a cross-sectional view of a conventional bidirectional optical module.

[Explanation of symbols]

1: Optical fiber fixture 1a: Optical fiber end face 2: Holder 3: Fastening parts 4: Adhesive 5: YAG weld 6: Lens 7: Lens 8: Wavelength selection element 9: Laser diode 10: Photodiode 11: Body case 12: Fastening process 13: Fastening part receiving process (counterbore) 14: Stepped part 21: Transmitted light 22: Received light 31: Fastening forming fastener 31a: Biting part 32: Recess forming fastener 32a: biting part 33: Fastening and recess forming fastener 33a: Biting part 33b: biting part 34: Convex forming fastener 34a: biting part 35: Fastening forming fastener 35a: biting part

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Claims (5)

[Claims] 1. An optical module comprising a light emitting / receiving element and an optical fiber fixture, wherein the optical fiber fixture is fixed to a holder using at least one fastening component, and the holder is fixed to a main body case. Characteristic optical module. 2. An optical module comprising a light emitting / receiving element and an optical fiber fixture, wherein the optical fiber fixture is provided with a fastening structure and is fixed to a holder, and the holder is fixed to a main body case. module. 3. The optical module according to claim 1, wherein the optical fiber fixture is inclined with respect to the axial direction of the holder and is fixed by an adhesive. 4. The optical module according to claim 1, wherein the shape of the tip of the fastening component has a concave portion and / or a convex portion. 5. An optical module comprising a light emitting / receiving element and an optical fiber fixing tool, wherein a holder for fixing the optical fiber fixing tool is provided with an oblique through hole, and the optical fiber fixing tool is inserted into the through hole. A method for assembling an optical module, comprising fixing with a fastening component, filling and fixing an adhesive in a gap between the holder and the optical fiber fixture, and then welding the holder to the main body case.