JP2002296463A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module in which the same mounting characteristic as that of a conventional end surface light-emitting type device is realized. SOLUTION: In the optical module in which a surface light-emitting type or a surface light-receiving type optical semiconductor device 12 and an optical fiber 13 optically connected to the optical semiconductor device 12 are arranged on a package board 11, the side surface of the optical semiconductor device 12 is formed so as to form a prescribed angle relative to a light-emitting surface or a light receiving surface, the side surface of the optical semiconductor device 12 is fixed through an insulating adhesive material on the board 11, and the light-emitting surface or the light receiving surface of the optical semiconductor device 12 and the optical axis of the optical fiber 13 are crossed.

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 fiber communication, and more particularly, to an optical semiconductor device for performing surface emission or surface reception on a substrate and an optical fiber optically connected to the optical semiconductor device. The present invention relates to an optical module provided.

[0002]

2. Description of the Related Art An optical module used for optical fiber communication uses a light receiving / emitting element for converting an optical signal used for transmission and an electric signal for signal processing. In optical communication, a semiconductor laser (hereinafter, referred to as LD), which is a light emitting element, is mainly used to convert an electric signal into an optical signal. LD
The light emitted from the optical fiber into the space is optically coupled to an optical fiber arranged precisely. In an optical fiber, since the size of a core used for transmission is about 10 μm, it is necessary to fix the emitting position of the LD and the position of the optical fiber with an accuracy of 1 μm or less.

FIG. 6 shows a conventional optical module. The LD 64 is mounted on the mounting substrate 63 on which the V groove 61 and the contact groove 62 are precisely formed. The LD is mounted with a precision of about 1 μm with respect to the position of the V groove 61 by a technique called visual alignment. afterwards,
The optical coupling is performed by arranging the optical fiber 66 in the V-groove 61 and the attaching groove 62 with an abutment. At this time, it is clear that the relative positional accuracy of the core (not shown) of the LD 64 and the optical fiber 66 depends on the accuracy of the visual alignment and the accuracy of the V-groove 61 and the attaching groove 62 of the mounting board 63.

[0004] Visual alignment generally has a
An alignment accuracy of about μm has been achieved, and as the mounting substrate 63, a high-precision and inexpensive substrate having a V-groove accuracy of 1 μm has been realized by anisotropically etching a Si (silicon) single crystal substrate. , Which contributes to the cost reduction of optical modules.

However, in a device that emits light in the surface direction of a device, such as a surface emitting laser (VCSEL), which has recently attracted attention due to its productivity and the like, the direction of light emission is different from that of a conventional LD. It is difficult to use the means for precise positioning by the described technique.

FIG. 7 shows a light receiving module as a conventional example of mounting a surface emitting / light receiving type device. The light receiving element (PD) 71 is mounted on a patterned carrier substrate 72. The carrier substrate 72 is mainly made of electrically wired ceramics. The optical fiber 73 is fixed on a mounting substrate 75 on which a V-shaped groove 74 is formed by using a fiber holder 76, and the carrier substrate 72 and the mounting substrate 75 are positioned and fixed on a package surface 77. The optical signal transmitted through the optical fiber 73 is emitted from the optical fiber, and is applied to the PD 72 while spreading. Conventionally,
The PD used has a small diameter even if the light receiving surface has a small diameter.
It is about 100 μm.

Even if the light emitted from the core diameter φ10 μm of the optical fiber falls within the range of φ100 μm or less on the light receiving surface of the PD, even if the positional accuracy between the optical fiber and the PD is about several tens μm, the optical module The function as was sufficient.

[0008]

However, in recent years,
Since the transmission capacity of the optical module increases and the response characteristics of the light receiving module are satisfied, the light receiving area is φ1.
It is required to use a small PD of about 0 μm.
Since the core diameter of the optical fiber is φ10 μm, it is necessary to bring the optical fiber core and the light receiving surface close to a level of several tens of μm, and it is necessary to adjust the relative positional accuracy at a level of 1 μm.

In such a surface type device, since the accuracy of mounting on the carrier substrate and the accuracy of the carrier substrate itself are on the order of several to 10 μm, it is difficult to apply the device to a PD module used for a large-capacity receiving module.

In the transmission module, the light emitting surface of the VCSEL has a diameter of about φ10 μm. Therefore, in order to obtain sufficient optical coupling to the optical fiber, the PD is required.
The same precision as that described above was required, and positioning was difficult with the conventional method using a carrier.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and a surface-emitting or surface-receiving type optical semiconductor device and an optical fiber are directly mounted on a mounting substrate to provide a surface-emitting or surface-receiving type light. It is an object of the present invention to provide an optical module in which a semiconductor element realizes the same mountability as a conventional edge emitting device.

[0012]

In order to solve the above-mentioned problems, an optical module according to the present invention comprises a surface-emitting or surface-receiving optical semiconductor element on a substrate and an optical fiber optically connected to the optical semiconductor element. The side surface of the optical semiconductor element is formed so as to be at a predetermined angle with respect to a light emitting surface or a light receiving surface, and the side surface of the optical semiconductor element is provided on the substrate with an insulating adhesive material. Wherein the light emitting surface or the light receiving surface of the optical semiconductor element intersects with the optical axis of the optical fiber.

Further, the adhesive is a low-melting glass, a thermosetting adhesive, or an anaerobic adhesive. Further, the optical semiconductor element is provided upright in a recess formed in the substrate by anisotropic etching.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of an optical module according to the present invention will be described in detail with reference to the drawings schematically shown. <Example 1> FIG. 1 is a perspective view of an optical module according to the present invention, and FIG. 2 is an exploded perspective view thereof. The optical module includes a mounting substrate 11 mainly made of, for example, single crystal silicon or the like, which can be anisotropically etched,
L12 and the optical fiber 13. On the mounting substrate 11, electrode pads 14, 15 and a V-groove 16 are formed. The side surface of the VCSEL 12 is formed so as to be at a predetermined angle (particularly perpendicular) to the surface of the light emitting point 17 (the light receiving surface when the optical semiconductor element is a light receiving element). In other words, the mounting board 1 is mounted upright via an insulating adhesive so that the surface 18 faces the mounting board 11.
The optical fiber 13 is mounted and mounted in one V-groove 16 to constitute an optical module.

The insulating adhesive (bonding agent) for fixing the VCSEL 12 is a low-melting glass, a thermosetting adhesive, or an anaerobic adhesive. An epoxy adhesive, an acrylic adhesive, or the like is used as the resin adhesive. Thereby, even if the side surface of the element is used for fixing, a defect such as a short circuit does not occur. In particular, a low melting point glass is desirable in consideration of fixing strength, reliability, and the like. Further, by using an anaerobic instant adhesive or the like containing an acrylic resin or the like as a component, heat curing or the like becomes unnecessary, and productivity is improved.

For positioning of the VCSEL 12, a mounting method called visual alignment is used. Visual alignment is performed by using the V-groove 1 formed in the mounting substrate 11.
6 is a means for mounting the element while monitoring the position 6 and precisely controlling the position relative to the position. According to this method, the relative displacement between the VCSEL 12 and the V-groove 10 can be mounted with an accuracy of 1 μm or less. The mounting surface 18 of the VCSEL 12 is formed by a cutting method called dicing. As a result, VCS
As for the accuracy of the mounting surface 18 of the EL 12 and the light emitting point 17 of the VCSEL 12, a positional accuracy of several μm is achieved.

V-groove 16 formed by anisotropic etching
Is easily achieved to 1 μm or less in the case of single crystal silicon. Therefore, the optical fiber 1 held against it
The core position of the exit surface of No. 3 can also be positioned with an accuracy of 1 μm or less. Light emitting point 17 of VCSEL 12
And the relative position accuracy of the core position of
m or less.

Conventionally, in the edge emitting type LD, the position of the light emitting point of the element is located at a position several μm from the mounting surface. It had to be formed deeply to be the same.
For example, in a conventional optical module as shown in FIG.
In order to arrange the end face of the optical fiber 66 close to the LD 64, it is necessary to form the contact groove 62.

On the other hand, in a surface-emitting type device such as the device of this embodiment, the position of the light-emitting point can be set freely. For example, in the present embodiment, the light emitting points are arranged at about 30 μm from the mounting board surface. In this case, the V-groove 16 on which the optical fiber 13 is mounted can be made shallow. Therefore, even if the optical fiber 13 is applied to the surface 19 in the optical axis direction of the formed V-groove 16, the VCSEL 1
It is possible to reduce the distance between the light emitting point 17 and the end face of the optical fiber.

In the present embodiment, the light emitted from the light emitting point 17 is reflected by the end face of the optical fiber 13 cut at a right angle, and returns to the light emitting point 17 again.
It is expected that the oscillation of the SEL 12 will be unstable.

However, in this embodiment, the VCSEL 12 is mounted on the substrate 11 by a visual alignment technique.
When mounting on a substrate, it can be easily mounted at an angle of 4 to 15 ° with respect to the substrate surface direction so that the optical axis of the optical fiber 13 and the light emitting point 17 are not orthogonal. Therefore, it is desirable that the optical axis of the optical fiber 13 and the light emitting surface of the VCSEL 12 are not parallel or do not coincide with each other, that is, have a crossing (including orthogonal) relation. That is, VCSE
The light emitting surface (or light receiving surface) of L12 and the optical axis of the optical fiber 13 intersect. According to the present invention, this relationship can be easily realized as described above.

When the VCSEL 12 is formed, the mounting surface 18 is formed by dicing. However, the mounting surface 18 can be cut at an angle during dicing. By using the VCSEL 12 formed in this manner, light having an angle in the direction perpendicular to the substrate can be emitted, and the degree of freedom in design can be further increased.

Next, the electrodes of the VCSEL 12 and the mounting substrate 1
The means for conducting the one electrode 14, 15 will be described. FIG.
Fig. 2 shows an enlarged view of the optical module. A conductor bump 20 made of Au or the like is formed on the VCSEL 12 in advance. The bumps are formed on both the output surface and the output surface electrode of the VCSEL 12. After mounting the VCSEL 12 upright, the side surface of the bump 20 and the electrode pad 14 on the mounting substrate 11 are connected using the bonding wire 21.

As described above, by using the bump 20 made of Au or the like formed in advance on the VCSEL 12, the connection between the electrode surface 22 of the VCSEL 12 and the electrode 14 on the substrate surface, which are vertically set, is realized by the bonding wire 21. It becomes easier. Here, bumps made of Au or the like, which are easy to form, are used, but a contact chip having a portion that is particularly perpendicular to the electrode surface of the VCSEL 12 and that has a portion parallel to the substrate surface is preliminarily soldered, conductive adhesive, or the like. The same effect can also be obtained by fixing with. Example 2 FIG. 4 is a perspective view showing another embodiment of the present invention, and FIG. 5 is an exploded perspective view thereof. A mounting substrate 41 made of the same material as in Example 1 has a V-groove 42 formed by anisotropic etching and a concave portion, for example, a trapezoidal groove 43. On the slope of the trapezoidal groove 43, as shown in FIG.
4, 45 are formed. The side surface of the VCSEL 46 is fixed inside a trapezoidal groove 43 formed in the mounting substrate 41. As in the case of Example 1, the VCSEL 46 is fixed on the inner surface of the trapezoidal groove 43 of the mounting board 41 by an insulating bonding agent. The optical fiber 47 is fixed to the V groove 42 and
The light emitted from the light emitting point 48 is coupled with the light.

In FIG. 5, the electrode 49 of the VCSEL 46
And a back electrode (not shown) is provided in the trapezoidal groove 4 of the mounting substrate 41.
In this state, the electrodes 45 and 44 formed on the slope 3 face the slope. Electrode 49 and electrode 45 of VCSEL 46
As shown in FIG. 4, conduction is achieved by pressing the bumps 50 while applying ultrasonic waves. VCSEL
The back electrode 46 and the electrode 44 are similarly fixed. As a result, the electrodes of the VCSEL 46 and the substrate 41 are conducted without wire bonding, and the optical module functions.

The bump 50 is formed by mounting the VCSEL 46 on the mounting substrate 4.
It may be formed on the VCSEL 46 before being fixed to 1. Of course, after fixing the VCSEL 46, the bump 50 may be supplied and pressed. Also, instead of the bumps 50, a contact chip is formed in a shape corresponding to the gap between the VCSEL and the slope of the trapezoidal groove 43, solder is previously formed on the contact chip, and the contact chip is placed in the gap and heated to conduct. It is also possible to take

By using the above-described means, optical coupling can be obtained with high accuracy in principle, and wire bonding can be omitted. Since the bonding wire has a coil component depending on the shape, the high frequency characteristic is improved in the present invention because the bonding wire is omitted. Further, it is not necessary to separately prepare a structural material such as a carrier substrate as in the conventional example, and the number of components can be reduced.

[0028]

According to the optical module of the present invention, since the side surface of the surface-emitting type optical semiconductor element is directly mounted on the mounting substrate without interposing a carrier substrate or the like, the position of the light-emitting point of the surface-emitting device and the optical fiber Can be accurately positioned.

Further, since no member such as a carrier substrate is required, an optical module having a small number of components and a simplified process can be provided.

Further, since the V-groove for mounting the optical fiber can be made shallow, the distance from the optical element can be shortened even if the etched slope of the V-groove is used for positioning in the optical axis direction. Thus, the degree of freedom in optical design is increased, the structure of the substrate is simplified, and an excellent optical module in which an optical fiber can be easily mounted can be provided.

Further, the contact between the electrode on the mounting substrate and the electrode of the optical semiconductor element arranged on the surface perpendicular to the mounting substrate surface is formed only for wiring by means using a contact chip such as Au bump. An excellent optical module which does not require a carrier substrate or the like can be provided.

Further, according to the optical module of the present invention, since a conductive bump can be used as a contact chip, its formation is easy and the process can be simplified.

Further, according to the present invention, it is possible to provide a means for conducting by pressing the contact chip, so that it is possible to avoid problems such as a decrease in transmission capacity due to wiring in a high-speed transmission module or the like.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing an embodiment of an optical module according to the present invention.

FIG. 2 is an exploded perspective view schematically showing an embodiment of the optical module according to the present invention.

FIG. 3 is an enlarged perspective view schematically showing an embodiment of the optical module according to the present invention.

FIG. 4 is a perspective view schematically showing another embodiment of the optical module according to the present invention.

FIG. 5 is an exploded perspective view schematically showing another embodiment of the optical module according to the present invention.

FIG. 6 is a perspective view schematically showing a conventional optical module.

FIG. 7 is a perspective view schematically showing another conventional optical module.

[Explanation of symbols]

 11, 41: mounting substrate 12, 46: VCSEL (optical semiconductor element) 13: optical fiber 18: mounting surface (standing) 20, 50: bump 43: trapezoidal groove (recess)

Claims (3)

[Claims] 1. An optical module comprising: a surface-emitting or surface-receiving optical semiconductor element; and an optical fiber for optically connecting to the optical semiconductor element. The side surface is formed so as to be at a predetermined angle with respect to the light emitting surface or the light receiving surface, and the side surface of the optical semiconductor element is fixed on the substrate via an insulating adhesive, and the light emitting surface of the optical semiconductor element or An optical module, wherein a light receiving surface and an optical axis of the optical fiber intersect. 2. The optical module according to claim 1, wherein the adhesive is a low-melting glass, a thermosetting adhesive, or an anaerobic adhesive. 3. The optical module according to claim 1, wherein the optical semiconductor element is provided upright in a recess formed in the substrate by anisotropic etching.