JP2001111068A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce costs. SOLUTION: V channels 22 and 24 being orthogonally crossed each other are formed on the upper surface of a stem 21 and the lower surfaces of an optical element 23 and a fiber-fixing tool 27. A positioning rod 25 is placed in two V channels 22 of the stem 21, the V channel 24 is engaged with the positioning rod 25 for mounting the optical element 23, and a V channel 29 is engaged with the positioning rod 25 for mounting the fiber-fixing tool 27. By simple structure/assembly where the positioning rod 25 is used as reference for aligning the V channels 22, 24, and 29, the optical element 23 and optical fiber 26 can be accurately positioned, thus eliminating the need for aligning work.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an optical module used in fields such as optical communication.

[0002]

2. Description of the Related Art In the manufacture of an optical module for optically coupling an optical element such as a laser diode (LD) or a photodiode (PD) with an optical fiber, in order to efficiently optically couple the optical element with the optical fiber. A so-called centering operation of aligning the optical axes with high accuracy has been conventionally performed, and this operation has been troublesome and requires many man-hours.

On the other hand, a structure as shown in FIG. 3 has been conventionally proposed for the purpose of reducing the cost of an optical module. The optical module shown in FIG. 3 eliminates the need for alignment work, that is, the optical axis can be aligned without alignment, and the two optical modules 11 are mounted on the stem 12 on which the optical element 11 is mounted. The pin 13 is set up, two positioning holes 16 are provided in the fiber fixing device 15 holding and holding the optical fiber 14, and the positioning pin 13 and the positioning hole 16 are engaged to assemble the stem 12 and the fiber fixing device 15. Thus, the optical axis of the optical element 11 automatically coincides with the optical axis of the optical fiber 14. In the figure, the optical element 11 is a surface-emitting light-emitting element or a surface-light-receiving light-receiving element having a light-emitting portion and a light-receiving portion on its upper surface.

[0004]

As described above, FIG.
By adopting the structure as shown in (1), it is possible to perform optical axis alignment without alignment. However, in order to realize high-precision optical axis alignment, for example, the positioning pin 13 and the optical element 11 are required. Need to be mounted on the stem 12 with high relative positional accuracy, and in order to erect the positioning pin 13 vertically, it is necessary to form a hole 17 for erecting the positioning pin 13 in the stem 12 with high accuracy. As a result, assembly costs (mounting costs) and processing costs are required.

[0005] That is, although the cost reduction effect due to the non-alignment can be expected, it is difficult to significantly reduce the cost as a whole due to the increase in the assembly and processing costs. Further, as one measure for reducing the cost, it is conceivable that the stem 12 is made of, for example, an inexpensive plastic molding material instead of metal, but if the plastic molding material is used for the stem 12 in FIG. The amount of heat generated by the heat generated through the stem 12 is greatly reduced, and the heat of the optical element 11 cannot be released.
A plastic molding material cannot be used for the stem 12.

[0006] In view of the above problems, an object of the present invention is to provide
An object of the present invention is to provide an optical module structure that realizes a high mounting position accuracy and enables a significant cost reduction.

[0007]

According to the first aspect of the present invention, in an optical module having an optical element mounted on a stem, the optical elements are orthogonal to each other on the lower surface of the constituent substrate or the added substrate. And two V-grooves formed in such a manner as to be perpendicular to each other on the upper surface of the stem.
Two V-grooves are formed, and positioning rods are placed in the V-grooves. The optical element is structured such that the two V-grooves are engaged with the positioning rods and mounted on the stem.

According to the second aspect of the present invention, there is provided a light having a structure in which the upper surface of the optical element mounted on the stem and the end face of the optical fiber fixed to the fiber fixture are optically coupled to each other. In the module, the optical element has two V-grooves formed so as to be orthogonal to each other on the lower surface of the constituent substrate or the added substrate, and the concave portion is formed on the surface of the fiber fixing device facing the stem, and the concave portion is formed. And four V-grooves located on two orthogonal axes with their inner ends facing each other, the end face of the optical fiber is located on the bottom surface of the recess, and two V-grooves orthogonal to each other are formed on the upper surface of the stem. Then, positioning rods are placed in the V-grooves, the optical element is mounted on the stem with its two V-grooves being engaged with the positioning rods, and the fiber fixing tool has the four V-grooves. Engage with alignment rod It is, and is configured to be mounted on the stem housing the light element in the recess.

According to a third aspect of the present invention, in any one of the first and second aspects, the positioning rod is a metal rod.

[0010]

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1A shows an embodiment of the invention of claim 1, and FIG. 1B shows the embodiment in an exploded manner. In this example, two Vs orthogonal to each other on the upper surface (mounting surface) of the stem 21 for mounting an optical element.
A groove 22 is formed. The upper surface of the stem 21 has a square shape, and V-grooves 22 are formed between two opposing sides thereof.

In this embodiment, the stem 21 is made of silicon, and the V groove 22 is formed with high precision by anisotropic etching of silicon. On the other hand, the optical element 23 also has two V grooves 24 orthogonal to each other on the lower surface. These V grooves 24 can be formed on the lower surface of the constituent substrate of the optical element 23. For example, when the constituent substrate is a silicon substrate, the V grooves 24 can be formed with high precision by anisotropic etching.

When it is difficult to form the V-groove 24 in the optical element 23 itself, the substrate on which the V-groove is formed is replaced with the optical element 2.
3 is adopted. in this case,
As a substrate to be added, for example, a silicon substrate on which a highly accurate V-groove can be easily formed is used. It is preferable that such a bonding structure of the optical element 23 and the additional substrate (silicon substrate) is manufactured in a wafer state, that is, an optical element wafer on which optical elements are arranged and formed, and a silicon wafer on which a required V groove is formed. And a two-layer structure, which is individually cut out, to obtain an optical element 23 having a V-groove 24 on the lower surface. Note that, for example, the optical element 23 such as a laser diode or a photodiode has a light emitting unit (or light receiving unit) on the upper surface thereof, as shown by a two-dot chain line in FIG. 1A.

To mount the optical element 23 having the above structure on the stem 21, the positioning rods 25 are respectively mounted on the two V-grooves 22 of the stem 21, and the V-grooves are mounted on the positioning rods 25. This is performed by mounting the optical element 23 with the engagement of the optical elements 24, which are fixed using, for example, an adhesive. As shown in the figure, three positioning rods 25 are used in total.

By mounting the optical element 23 in this manner, the optical element 23 and the stem 21 are aligned with the V-grooves 24 and 22 facing each other with reference to the positioning rod 25, that is, a special mounting position. Optical element 2 without adjustment
3 is mounted on the stem 21 with high accuracy. As shown in this example, the constituent material of the stem 21 is silicon, and the constituent substrate or the additional substrate of the optical element 23 is a silicon substrate. That is, the V grooves 22 and 24 are formed by anisotropic etching of silicon. With such a structure, the sub-micron-accurate V-grooves 22 and 24 can be easily formed, so that extremely high mounting accuracy can be easily obtained.

In the above-described embodiment, the constituent material of the stem 21 is silicon, and the substrate material for attaching the V-groove forming substrate to the optical element 23 is also silicon. However, for example, a plastic molding material is used instead of silicon. You can also. The stem 21 having the V-groove 22 and the substrate having the V-groove 24 can be manufactured with high precision molding of plastic with almost the same precision as that of silicon.

When the stem 21 is made of silicon or plastic, the heat generated by the optical element
Although the amount of heat dissipated through is reduced, by using the positioning rod 25 as a metal rod, the positioning rod 25 becomes a heat conductor and the heat generated from the optical element 23 is guided to the outside of the optical element 23. That is, an efficient heat dissipation structure can be obtained by the positioning rod 25. For example, Cu or a Cu alloy is used as a metal material forming the alignment rod 25.

FIG. 2A shows an embodiment of the second aspect of the present invention, in which a fiber fixture 27 holding and holding an optical fiber 26 is mounted on the configuration shown in FIG. The fiber fixture 27, as shown in FIG.
A concave portion 28 is formed at the center of the surface facing the stem 21, and four V-grooves 29 are formed in the concave portion 28, each of which has an inner end facing each other and are positioned on two orthogonal axes.
The optical fiber 26 is inserted and fixed in the hole 31, and its end face is located on the bottom face of the recess 28. The fiber fixture 27 is molded with high precision, for example, from plastic.

In the assembly of the optical module shown in FIG. 2, an alignment rod 25 is placed in the V-groove 22 of the stem 21, an optical element 23 is first placed thereon, and four V-grooves 29 are further aligned. The fiber fixture 2 is engaged with the rod 25.
7 is mounted on the stem 21 from above, so that the optical element 23 is accommodated in the concave portion 28 of the fiber fixture 27.

By assembling in this manner, the optical element 23 and the fiber fixture 27 are mounted on the stem 21 with high positional accuracy with respect to the alignment rod 25, and the upper surface of the optical element 23 and the end face of the optical fiber 26 are Are opposed to each other, so that no special mounting position adjustment is performed, that is, the optical axis of the optical element 23 and the optical fiber 26
And the optical axis of the light beam are matched with high precision.

By using a metal rod as the positioning rod 25 as described above, a sufficient heat radiation effect can be obtained even if the stem 21 and the fiber fixing member 27 are made of, for example, silicon or plastic.

[0021]

As described above, according to the first aspect of the present invention, the optical element 23 can be mounted on the stem 21 with high positional accuracy with a simple configuration. Also,
According to the invention of claim 2, the optical element 23 and the optical fiber 26
The optical axes of the optical axis and the optical axis of the optical fiber can be aligned with high accuracy without alignment. For this purpose, V-grooves 22, 24, and 29 are formed in the stem 21, the optical element 23, and the fiber fixture 27, respectively. Positioning rod 25 placed in the V groove 22
The optical device 23 and the fiber fixture 27 are simply mounted by engaging the V-grooves 24 and 29 with the V-grooves 24 and 29. The assembly cost and the processing cost as in the conventional optical module shown in FIG. Does not lead to an increase in
Therefore, the cost of the optical module can be significantly reduced.

Further, according to the third aspect of the present invention, since the heat generated from the optical element 23 can be radiated to the outside by the positioning rod 25, the stem 21 does not have to be made of metal, ie, a plastic molding material. Inexpensive materials such as can be used.

[Brief description of the drawings]

FIG. 1A is a perspective view showing one embodiment of the invention of claim 1;
B is an exploded perspective view thereof.

FIG. 2A is a perspective view showing one embodiment of the invention of claim 2;
B is a perspective view showing a part of the disassembly.

FIG. 3 is a perspective view illustrating an example of a conventional configuration of an optical module.

Claims (3)

[Claims] 1. An optical module having an optical element mounted on a stem, wherein the optical element has two V-grooves formed orthogonally to each other on a lower surface of a constituent substrate or an added substrate. And two V-grooves orthogonal to each other are formed on the upper surface of the stem, and alignment rods are mounted on the V-grooves. The optical element is engaged with the two V-grooves on the alignment rod. And an optical module mounted on the stem. 2. An upper surface of an optical element mounted on the stem,
An optical module having a structure in which end faces of optical fibers fixed to a fiber fixture are optically coupled to each other so as to be opposed to each other, wherein the optical elements are orthogonal to each other on a lower surface of a constituent substrate or an added substrate. A concave portion on the surface of the fiber fixing device facing the stem,
The concave portion is formed with four V-grooves located on two orthogonal axes with the inner ends facing each other, the end surface of the optical fiber is located on the bottom surface of the concave portion, and the two perpendicular to the upper surface of the stem. V-grooves are formed, alignment rods are placed in the V-grooves, and the optical element is mounted on the stem with the two V-grooves being engaged with the alignment rods. An optical module characterized in that the four V-grooves are engaged with the alignment rod, and the optical element is accommodated in the concave portion and mounted on the stem. 3. The optical module according to claim 1, wherein the alignment rod is a metal rod.