JPH11271572A - Optical coupling system, optical module, and optical transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the optical coupling system with low optical coupling loss by using an optical semiconductor element which has no spot size converting function by filling a space, constituting at least an optical path between optical component, with a solid light-transmissive organic material having a specific refractive index. SOLUTION: The optical coupling structure is constituted having at least the optical semiconductor device 1, a lens 2, and an optical fiber 3. Then at least the space between those optical components is filled with the solid light- transmissive organic material 4. The optical semiconductor device 1 is, for example, a light emitting semiconductor device or light receiving semiconductor device. As the solid light-transmissive organic material 4, silicone-based resin, epoxy-based resin, etc., is used. The refractive index n1 of the lens 2 and the refractive index n2 of the transparent organic material 4 are so set than n1>n2. Further, n1 is preferably larger than 1.2×n2 so as to display the function of the lens 2 sufficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an optical coupling system and an optical module. In particular, the present invention relates to a surface mount type optical module.

[0002]

2. Description of the Related Art In recent years, for full-scale introduction of an optical fiber transmission system into a subscriber network, cost reduction of an optical module has been strongly demanded. For this reason, studies are being actively conducted with the aim of simplifying the alignment process of the optical element and the optical fiber in the optical module and reducing the number of package components.

[0003] The prior art is disclosed in, for example, Japanese Patent Application Laid-Open No. 5-241407 (conventional example 1) and Japanese Patent Application Laid-Open No.
No. 006 (Conventional Example 2), reports from the Society of Circuit Implementation, Vol. 10 No. 5 pp 302-305 (199
5), similarly, Journal of Circuit Packaging Society, Vol. 10 No. 5
pp. 325-329 (1995) and the IEICE Autumn Meeting c-194 (1993) (conventional example 3).

[0004] The optical transmission module is a basic device constituting an optical communication system. These are a laser diode as a light emitting element, an optical semiconductor element such as a photodiode as a light receiving element, an optical fiber or an optical waveguide, a lens for optically coupling them, a substrate for fixing them, and input / output of electric signals. Consists of leads, packages, etc.

[0005] As for the above-mentioned optical coupling method, instead of a method in which a spherical lens or an aspherical lens is placed between an optical semiconductor element and an optical fiber or an optical waveguide, a method in which the optical semiconductor element is directly coupled to an optical fiber and an optical waveguide is used. It is getting. The intention is to remove the lens to reduce the number of parts. In this case, the optical coupling loss is about 10% due to the difference in spot size between the optical semiconductor element, the optical fiber, and the optical waveguide. In order to reduce the optical coupling loss, (1) a method of providing a spot size conversion function to an optical semiconductor element and (2) a spherical fiber in which the tip of an optical fiber core is formed into a lens shape are used to prevent this. And so on.

The method of assembling parts, particularly assembling a laser diode and an optical fiber, which must be optically coupled with low loss, is changing from an active alignment method to a passive alignment method. The active alignment method is a method in which a laser diode emits light and the intensity of output light from an optical fiber is monitored to perform alignment. On the other hand, the passive alignment method is a method of performing alignment without causing a laser diode to emit light.

As a method of realizing the passive alignment method, for example, a surface mounting method of mounting an optical component on one mounting board is used. The precise alignment method is to form alignment marks on the optical semiconductor device and the mounting substrate, transmit near-infrared light, and at the same time observe and align the alignment marks, or use a metal alloy surface for fixing. Methods such as self-alignment using tension have been performed.

As for packaging, a plastic package (resin sealing) suitable for mass production at low cost is considered to be a promising alternative to the metal / ceramic package (airtight sealing) which has been the mainstream in the field of optical devices. However, the plastic package is effective in reducing the cost of the optical module as compared with the metal / ceramic package, but generally has a drawback of high moisture permeability. Therefore, as a simple sealing method, a method of embedding an optical component with a transparent organic material or a method of covering an optical semiconductor element with a lid such as glass has been proposed.

In Conventional Example 1, a microlens is formed in a concave groove formed on a Si substrate, and an optical fiber is formed on a Si substrate.
It is intended to be fixed in the groove to achieve a highly efficient connection.
In the conventional example 2, the spherical lens and the optical fiber are both made of Si.
It is intended to be fixed to the V-groove formed in the substrate to achieve a highly efficient coupling. Each of them has an assembly structure in an airtight package, and is not expected to be easily sealed with resin. The third conventional example is an optical coupling system using a spherical fiber and filling an inert liquid having a refractive index of about 1.3 into the space between the semiconductor element and the spherical fiber. In this system, the optical coupling efficiency is reduced in order to increase the position deviation tolerance. This optical coupling system adjusts the refractive index in order to increase the positional deviation tolerance, and does not ensure reliability. In addition, handling is difficult because a liquid is used.

[0010]

SUMMARY OF THE INVENTION A first object of the present invention is to provide an optical coupling system having a low optical coupling loss on the assumption that an optical semiconductor device having no spot size conversion function is used.
And an optical module. Thus, for example, a high-output optical transmission module can be provided at low cost. In addition, the present invention provides a low-cost optical transmission system.

A second object of the present invention is to use an optical semiconductor element having no spot size conversion function, and to reduce the optical coupling loss and to provide a wide tolerance and precision regarding the mounting position accuracy of optical components. An object of the present invention is to provide an optical coupling system and an optical module that can be mounted in a position. For example, the easiness of production and the cost reduction are promoted. In addition, the present invention provides a lower cost optical transmission system.

A third object of the present invention is to provide an optical semiconductor device having no spot size conversion function and to mount various optical components in addition to the optical components having a low optical coupling loss and the basic configuration. To provide an optical coupling system and an optical module that can easily perform the above. A typical example of various optical components other than the optical components having the basic configuration is an optical isolator. This optical component is inserted between an optical semiconductor element and an optical waveguide, for example, an optical fiber, and facilitates matching of various optical characteristics.

Monolithically integrating an optical semiconductor device having a spot size conversion function for the purpose of reducing optical coupling loss is an effective method for cost reduction from the viewpoint of reducing the number of components. However, it is difficult to integrate the optical isolator into the optical member to which the present invention is applied, and it is also difficult to integrate the optical isolator when using a spherical fiber. Therefore, the problem cannot be solved simply by using an optical semiconductor device having a spot size conversion function in configuring an optical member having such various optical components.

When an optical isolator and a spherical fiber are integrated, the required accuracy of the mounting position is 2-3 times narrower than when a laser diode having a spot size conversion function is used. In addition, precise alignment is required not only in the direction perpendicular to the optical axis but also in the optical axis direction. As described above, mounting of various optical components requires extremely advanced optical design.

Next, as described above, the plastic package is effective in reducing the cost of the optical module as compared with the metal / ceramic package, but generally has a drawback of high moisture permeability.

Therefore, in order to promote the practical use of plastic modules, it is important to ensure the reliability while taking advantage of the low cost. As mentioned above, the method of covering an optical semiconductor element with a transparent organic material is used. However, since the refractive index of a transparent organic material is generally close to that of an optical fiber material, a glass material such as a spherical fiber or quartz is used. There is a drawback in that a lens using a lens cannot obtain the effect as a lens.

The present invention is intended to solve these difficulties.

[0018]

SUMMARY OF THE INVENTION Among the inventions disclosed in the specification of the present application, the main ones are summarized as follows. In the specification of the present application, a basic optical system is referred to as an optical coupling system, a configuration including mounting of optical components is referred to as an optical assembly, and a configuration including sealing of the optical components by packaging is referred to as an optical module.

(1) The optical coupling system and the optical assembly according to the first aspect of the present invention use a lens having a refractive index higher than the refractive index of a solid translucent organic material, and perform optical coupling while maintaining the function of the lens. It constitutes the system. By this means, the first object can be achieved.

More specifically, the first optical coupling system and the optical assembly according to the present invention will be described in more detail. The optical coupling system has at least an optical semiconductor element, a lens, and an optical fiber, and a solid light-transmitting part is provided between the optical components. An optical coupling structure filled with a transparent organic material, wherein the relationship between the refractive index n1 of the lens and the refractive index n2 of the translucent organic material is n1> n2. .

In order to make the function of the lens function more effectively, it is desirable that the relationship between the refractive indices is substantially n1 ≧
The relationship is 1.2 × n2.

As the solid translucent organic material according to the present invention, a gel material can also be used. Therefore, naturally, a mode in which a gel-like translucent organic material is applied is also included in the scope of the present invention. However, in the case of a gel, it is preferable to arrange a frame or the like, for example, in order to make the gel into a predetermined shape. The fact that the solid translucent organic material includes a gel translucent organic material can be similarly applied to each embodiment of the invention described below.

(2) A second aspect of the present invention is the optical coupling system according to the above item 1, wherein a semiconductor material having a refractive index of 2.2 or more is used.

(3) A third embodiment of the present invention has at least optical components of an optical semiconductor element, a lens, and an optical waveguide, and a space between the optical components is filled with a solid translucent organic material. The relationship between the refractive index n1 of the lens and the refractive index n2 of the solid translucent organic material is n1> n2, and the position of the lens and the optical waveguide is determined by a V-shaped groove provided on a predetermined substrate. The optical module is characterized in that the space between the optical components is filled with a solid translucent organic material.

FIG. 3 is a view showing a model of a fixed state of a spherical lens by a V groove on a silicon substrate. The optical semiconductor element 10 is fixed to a silicon substrate 40. Ball lens 2
0 is optically coupled to the optical semiconductor element 10 and disposed. In this case, a V-groove is provided in the recon board 40, and the spherical lens 20 is held here. This V groove 4
2 itself is a V-groove formed by ordinary anisotropic etching. FIG. 4 is a view showing a model of fixing an optical fiber by a V-groove on a silicon substrate. In FIG. 4, the optical fiber 30 is held in a V-shaped groove 42 provided in a silicon substrate 40.

As the form of the optical module of the present invention, for example, a form using a resin case or a collective molding method, for example, a transfer mold can be used. It goes without saying that these forms can also be used in the optical module described below.

(4) A fourth embodiment of the present invention has at least optical components such as an optical semiconductor element, a lens, and an optical waveguide, and a space between the optical components is filled with a solid translucent organic material. The relationship between the refractive index n1 of the lens and the refractive index n2 of the solid translucent organic material is n1> 1.2 × n2, and the lens and the optical waveguide are V-shaped grooves provided on a predetermined substrate. The position of the optical module is determined by the optical module, and a space between the optical components is filled with a solid translucent organic material.

This embodiment is desirable for making the function of the lens more effective.

(5) A fifth mode of the present invention is the optical module according to the above item 3 or 4, wherein the optical module is sealed with an organic resin mold.

Incidentally, an appropriate focal length of a spherical lens, a laser diode and a lens, and a lens and an end of an optical fiber so that the beam waist of light incident on the optical waveguide becomes 0.5 to 2 times the spot size of the fiber. By selecting a distance, assembling an optical system, and using a lens with a small diameter, the depth of the V-groove (V-groove width) formed at the mounting position of the lens can be reduced, and the range of V-groove manufacturing tolerance can be reduced. It is extremely effective practically.

(6) In a sixth aspect of the present invention, the lens has a focal length of 1 mm or less in the solid translucent organic material. Is an optical coupling system.

(7) A more specific embodiment will be described as a seventh embodiment of the present invention. That is, the lens has a focal length of 1 mm or less in the transparent organic material, and the ratio of the distance between the lens and the optical semiconductor element and the distance between the lens and the optical fiber is 6 times or less, that is, the image magnification is 6 times or less. This is an optical coupling system in which the relationship between the lens and the refractive index of the translucent organic material is the same as in the above item 1.

The optical module outlined in the above (4) to (7) achieves, among other things, the second object of the present invention.

(8) According to an eighth aspect of the present invention, the divergence angle of the light emitted from the optical semiconductor element is allowed to enter the optical waveguide within ± 10 degrees near the front surface of the optical waveguide, In addition, this is an optical coupling system in which the relationship between the lens and the refractive index of the translucent organic material is the same as in the above item 1.

As described above, the sixth to eighth aspects can achieve the third object of the present invention. Further, examples of more practical modes will be listed below.

(9) In a tenth embodiment of the present invention, the lens has a focal length of 500 μm or less in the transparent organic material, and the divergent angle of the light emitted from the optical semiconductor element 1 is ± 10% in the vicinity of the front surface of the optical fiber. This is an optical coupling system in which the light is incident on the optical fiber substantially parallel within a degree, and the relationship between the refractive index of the lens and the translucent organic material is the same as that of the above item 1.

The practical form of the form described as a means for achieving the third object can be summarized as follows. In particular, a lens having a short focal length is used, and the spot size of the light incident on the fiber is set to 0.1 mm of the spot size of the fiber. It can be said that an optical system is formed by selecting an appropriate focal length of the lens and a distance between the laser diode and the lens so as to increase the magnification by 5 to 2 times and to form parallel light.

In the present invention, it is preferable that the lens has a spherical shape from the viewpoints of securing lens characteristics, assembling, and manufacturing.

Hereinafter, various forms of the main optical assembly of the present invention will be further listed.

(10) A tenth embodiment of the present invention is directed to a mount substrate on which a V-groove 1 for fixing an optical fiber, a V-groove 2 for fixing a lens, and an electrode pattern are formed on the surface. An optical fiber fixed to the groove 1, a lens fixed to the V-groove 2, at least one optical semiconductor element and another optical semiconductor element mounted on the mount substrate, and these optical components are made of a transparent organic resin. An optical assembly in a sealed optical semiconductor device, which satisfies claim 1 above.

(11) An eleventh embodiment of the present invention relates to a mount substrate 1 having a V-groove for fixing an optical fiber on the surface, an optical fiber fixed to the V-groove 1, and a lens on the surface. A mounting substrate 2 on which a V-groove 2 for fixing the semiconductor device and an electrode pattern are formed, at least one optical semiconductor element and another optical semiconductor element mounted on the mounting substrate 2, and are fixed to the V-groove 2. An optical semiconductor device having a lens and a planar substrate for fixing the two mounting substrates, and these optical components are sealed with a transparent organic resin, wherein the optical semiconductor device satisfies claim 1 above. Optical assembly.

(12) In a twelfth embodiment of the present invention, the optical semiconductor element 1 has an optical waveguide structure, has a light emitting function, and has an optical axis height within ± 3 μm and the center of the spherical lens. The optical assembly according to any one of Items 10 to 11, wherein the optical assembly coincides with an optical axis height of the optical fiber.

(13) In a thirteenth embodiment of the present invention, the optical semiconductor device 2 has an optical waveguide structure, has a light receiving effect, and has an optical axis height within ± 3 μm.
Wherein the height of the optical axis coincides with the height of the optical axis.
It is an optical assembly of paragraph 1.

(14) In a fourteenth aspect of the present invention, an isolator is inserted between the two mounting substrates,
Item 12. The optical assembly according to Item 10 to 12, wherein the optical assembly is fixed to the planar substrate.

(15) According to a fifteenth aspect of the present invention, in the V-groove for mounting the above-mentioned lens, the V-groove shallower than at least one lens-mounting V-groove in a direction perpendicular to the optical axis.
Item 15. The optical assembly according to Item 10 to 14, wherein a groove is formed.

[0046]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing an optical assembly or an optical module according to the present invention, first, an embodiment of a basic optical coupling system will be described.

FIG. 1 is a diagram conceptually illustrating the basic structure of an optical coupling system.

The optical coupling structure according to the present application is configured to include at least the optical semiconductor device 1, the lens 2, and the optical component as the optical fiber 3. At least the space between the optical components is filled with the solid translucent organic material 4.

The optical semiconductor element 1 may be a light emitting semiconductor element or a light receiving semiconductor element, and the present invention can be applied to these.

Examples of the solid translucent organic material include silicone resin, epoxy resin, acrylic resin, urethane resin, and urea resin. From the viewpoint of moisture resistance, silicone resins and epoxy resins are preferred.

As a lens, a spherical lens is described as an example. Of course, other types of lenses may be used depending on the requirements of the characteristics.

The most important points in the present invention are, as described above, the refractive index n1 of the lens and the refractive index n2 of the transparent organic material.
And n1> n2. Further, as described above, n1> 1.
2 × n2 is preferred.

The refractive index of the lens material is, for example, about 3.45 for silicon and 2.42 for diamond.
And about 2.37 for zinc blende (ZnS). Meanwhile, examples of the refractive index of the translucent organic material are as follows. The silicone resin is about 1.40, and the epoxy resin is about 1.53.

(Embodiment 1) FIG. 2 is a view for explaining a first example of an optical assembly according to the present invention. (A) of FIG.
FIG. 2 is a partial cross-sectional structural view as viewed from above, and FIG. 2B is a partial cross-sectional structural view as viewed from a side parallel to the optical axis.

In the example of FIG. 2, the optical assembly comprises optical semiconductor elements 10, 11, a spherical lens 20, an optical fiber 30, and substrates 40, 41 for supporting these optical components.
It is made of a translucent organic resin 60 according to the present invention. The substrate for supporting the optical component is divided into two substrates (40, 41) as in this example for manufacturing reasons. Further, these divided substrates are mounted on a flat substrate 50 and integrated. Further, the substrate 40 or the substrate 41 for supporting the optical component is provided.
Are provided with V-grooves, respectively. These V-grooves are for fixing optical components mounted on this substrate. Usually, it is useful to employ a silicon substrate for these substrates. These V-grooves are formed in highly accurate positions and shapes by anisotropic etching of silicon. Therefore, the present invention is useful for fixing an optical component of an optical coupling structure or an optical assembly as in the case of the present invention which requires high-precision optical axis alignment.

The optical elements 10 and 11 are die-bonded to the substrate 40. The spherical lens 20 is fixed to a V-shaped groove 42 provided on the substrate 40. In addition, the fiber strand 30
Is fixed to a V-shaped groove 43 provided in the substrate 41. Thus, the optical semiconductor element 10 and the optical element 30 are optically coupled to each other, and the optical semiconductor element 10 and the optical element 11 are optically coupled to each other.

In this example, a V-groove 47 smaller than the V-groove 42 is further formed around the V-groove 42. For this reason, the V-groove 47 absorbs excess adhesive, and it is possible to prevent the adhesive from sneaking into the lens surface.

The tips of the optical semiconductor elements 10 and 11, the spherical lens 20 and the fiber 30 are covered with a translucent resin 60, for example, a silicone resin.

As for the optical semiconductor element, in this example, the optical semiconductor element 10 is an edge emitting laser diode made of an InP-based semiconductor. The oscillation wavelength is 1.3 μm, the forward output is 10 mW, and the full width at half maximum of the far field pattern is 25 × 30 degrees (approximately 1.1 × in terms of spot size).
0.9 μm). The optical semiconductor element 11 is made of InP.
This is an end face light receiving type (waveguide type) photodiode made of a system semiconductor. This optical semiconductor element 11 is an optical semiconductor element 1
This is for monitoring the rear output of 0.

The optical semiconductor elements 10 and 11 are die-bonded to predetermined positions of the substrate 40 by junction-down with Au-Sn solder. Markers for alignment with the substrate 40 are formed on the junction-side surfaces of the optical elements 10 and 11. Au-S
The thickness of the n solder layer is 3 to 5 μm, and the height of the active layers of the optical elements 10 and 11 from the surface of the substrate 40 is set to 8 to 10 μm.

The spherical lens 20 has a refractive index of 2.0 and a radius of 60.
The focal length is about 1 in resin with a refractive index of 1.4 μm.
00 μm. In this example, the refractive index of the lens is 2.0.
On the other hand, the refractive index of the translucent organic material is about 1.4 (a value for light having a wavelength of 1.3 μm).

The optical fiber 30 is a single mode quartz fiber. Outer diameter 125μm, spot size 5μ
m.

The distance between the optical element 10 and the spherical lens 20 is set to 130
μm, the distance between the spherical lens 20 and the optical fiber 30 is 390 μm.
If m, the enlargement rate of the spot size becomes three times, and optical coupling is performed with an efficiency of about -4 dB. The allowable range for displacement in the direction perpendicular to the optical axis direction is about 1.5 μm. The output light of the optical element 10 is coupled to the fiber 30,
The light propagates through the fiber 30 along the optical axis direction 33 and is output.

As described above, the substrates 40 and 41 are made of silicon substrates having a crystal plane orientation of (100). Substrates 40, 41
Is provided with V-grooves 42 and 43 for positioning the ball lens 20 and the optical fiber 30 with high accuracy, and wiring 45 for driving the optical elements 10 and 11.

An alignment marker (not shown) is formed at a position where the optical elements 10 and 11 are fixed. The V-groove 42 and the marker consist of a (111) crystal plane,
It is formed simultaneously by anisotropic etching with a KOH aqueous solution. The width of the V-shaped groove 43 is 138 to 143 μm, and the height of the optical axis at the tip of the fiber 30 as viewed from the surface of the substrate 40 matches the height of the active layer and the absorption layer of the optical elements 10 and 11. It has been processed.

The wiring 45 is made of Au / Pt / Ti film or Au.
/ Ni / Cr film or the like, and is deposited on the insulating film on the surface of the substrate 40. Although the wiring pattern in FIG. 2A is schematically drawn, the width and thickness of the wiring 45 and the thickness of the insulating film are naturally determined in consideration of the load capacitance and the thermal resistance of the optical elements 10 and 11. It is decided.

The translucent resin 60 is made of a silicone resin. The refractive index of the translucent resin 60 at a wavelength of 1.3 μm is 1.4, which is substantially matched with the refractive index of the fiber 30. The transparent resin 60 is composed of the optical elements 10 and 11 and the spherical lens 2.
0, is applied to the end of the fiber 30 (the entire surface of the fiber 30 according to the reliability specification) and is in close contact with them.
Further, reflected return light from the end face of the fiber 30 to the optical element 10 is eliminated.

The outline of the assembly process of the optical assembly 1 of the first example is as follows.

(1) The markers on the optical elements 10 and 11 and the substrate 40 are recognized by an infrared image, and the mutual alignment is performed.

(2) A load is applied to the optical elements 10 and 11, and the optical elements 10 and 11 are temporarily bonded to the preheated substrate 40.

(3) The Au—Sn solder is reflowed, and the optical elements 10 and 11 are die-bonded to the substrate 40.

(4) The substrate 40 is fixed to the parallel flat substrate 50 with a conductive (high thermal conductivity) epoxy resin.

(5) The wires 47 are bonded between the optical elements 10 and 11 and the wiring 45 of the substrate 40.

(6) The spherical lens 20 is fixed to the V groove 42 with an ultraviolet curable resin.

(7) The fiber 30 is fixed to the V-shaped groove 43 with an ultraviolet curing resin.

(8) The position in the in-plane direction (x direction) is adjusted so that the distance between the spherical lens 20 and the end face of the optical fiber 30 is a predetermined distance and the light output is maximized.
Is fixed to the parallel plane substrate 50 with a conductive (high thermal conductivity) epoxy resin. When the positions of the ball lens side end of the substrate 40 and the ball lens 20 and the fiber end side of the substrate 41 and the tip of the fiber 30 are 3 μm or less, the substrate 4
By aligning 0 and 41, positioning in the optical axis direction can be performed.

(9) The transparent resin 60 is dropped on the optical elements 10 and 11, the spherical lens 20 and the optical fiber 30, and thermally cured.

The focal length, radius, refractive index,
The distance between the spherical lens 20 and the optical element 10 and the distance between the spherical lens 20 and the optical fiber 30 are the optical coupling loss, the allowable displacement range,
Image magnification, V-groove depth (determined by manufacturing accuracy, etc. When the optical coupling loss is to be 4 dB or more, it is sufficient to couple a single mode fiber with a spot size of 5 μm with a beam waist of 2 to 12 μm.

The spot size of the optical element is approximately 1 μm, and the diameter of the beam waist is achieved by increasing the image magnification. The allowable range of the displacement increases as the beam waist diameter increases.

(Embodiment 2) FIG. 5 shows a second embodiment according to the present invention.
It is a figure explaining the optical assembly of the example of a. FIG. 5A is a partial cross-sectional structural view as viewed from above, and FIG. 5B is a partial cross-sectional structural view as viewed from a side surface parallel to the optical axis. In the second example, the substrate on which the optical components are mounted is constituted by a common substrate.

In the example of FIGS. 5A and 5B, the optical assembly is composed of optical semiconductor elements 110 and 111 and a spherical lens 12.
0, an optical fiber 130, a V-grooved substrate 140, and a transparent resin 160. The individual optical components are the same as those described above, and the description is omitted.

The spherical lens 120 has a refractive index of 3.0 and a radius of 5
In a resin having 0 μm and a refractive index of 1.4, the focal length is about 50 μm. If the distance between the optical element 110 and the spherical lens 120 is up to 50 μm, the light emitted from the optical element 110 becomes almost parallel light, and the beam diameter becomes about 12 μm.

(Embodiment 3) FIG. 6 shows a third embodiment according to the present invention.
It is a figure explaining the optical assembly of the example of a. FIG. 6A is a partial cross-sectional structural view as viewed from above, and FIG. 6B is a partial cross-sectional structural view as viewed from the side parallel to the optical axis. The third example is an example having an optical isolator. This optical isolator prevents reflected light from the end face of the optical fiber from returning to the optical semiconductor device, particularly to the semiconductor laser device. Such reflected light causes instability of the characteristics of the semiconductor laser device. Therefore, there is a strong demand for reducing such reflected light in practical use.

In the example of FIGS. 6A and 6B, the optical assembly 200 includes optical semiconductor elements 210 and 211, a spherical lens 220, an optical fiber 230, and a V-grooved substrate 24.
0, 241, a parallel plane substrate 250, and a transparent resin 260
And an optical isolator 270. The optical isolator itself may be a conventional one. The other individual optical components are the same as those in the first embodiment, and the description is omitted.

The spherical lens 120 has a refractive index of 3.0 and a radius of 5
In a resin having 0 μm and a refractive index of 1.4, the focal length is about 50 μm. When the distance between the optical element 110 and the spherical lens 120 is up to 50 μm, the light emitted from the optical element 110 becomes almost parallel light and enters the optical isolator 270.

As in this example, since the light of the optical element 110 is substantially parallel, an optical isolator can be easily inserted. Similarly, other optical components can be inserted as needed. In this way, the device can be further multi-functionalized.

(Embodiment 4) This embodiment is an example in which a gel material is used as the light-transmitting organic material.

FIG. 7 is a view for explaining a fourth example of the optical assembly according to the present invention. FIG. 7A is a partial cross-sectional structural view as viewed from above, and FIG. 7B is a partial cross-sectional structural view as viewed from a side surface parallel to the optical axis.

In the example of FIG. 7, the optical assembly 50 includes the optical semiconductor elements 10, 11, the spherical lens 20, the optical fiber 30, and the substrates 40, 41 for supporting these optical components.
And a translucent and gel organic resin 60 according to the present invention. The substrate for supporting the optical component is composed of two substrates (4) as in this example for manufacturing reasons.
0, 41). Further, these divided substrates are mounted on a flat substrate 50 and integrated. Further, the substrate 40 or the substrate 41 for supporting the optical component is provided with a V-groove, respectively. These V-grooves are for fixing optical components mounted on this substrate. Usually, it is useful to employ a silicon substrate for these substrates. These V-grooves are formed in highly accurate positions and shapes by anisotropic etching of silicon.
Therefore, the present invention is useful for fixing an optical component of an optical coupling structure or an optical assembly as in the case of the present invention which requires high-precision optical axis alignment.

The optical elements 10 and 11 are die-bonded to the substrate 40. The spherical lens 20 is fixed to a V-shaped groove 42 provided on the substrate 40. In addition, the fiber strand 30
Is fixed to a V-shaped groove 43 provided in the substrate 41. Thus, the optical semiconductor element 10 and the optical element 30 are optically coupled to each other, and the optical semiconductor element 10 and the optical element 11 are optically coupled to each other.

In this example, a V-groove 47 smaller than the V-groove 42 is further formed around the V-groove 42. For this reason, the V-groove 47 absorbs excess adhesive, and it is possible to prevent the adhesive from sneaking into the lens surface.

The tips of the optical semiconductor elements 10 and 11, the spherical lens 20 and the fiber 30 are covered with a translucent resin 60, for example, a gel silicone resin. In this example, since the translucent resin 60 is a gel, a frame 70 and a lid 71 are provided. A V-shaped groove 72 is formed in the frame.

Note that the V-groove 72 also serves to reduce the gap between the fibers and to hold down the fibers.

In this example, the optical semiconductor device 10 is an edge emitting laser diode made of an InP-based semiconductor. The oscillation wavelength is 1.3 μm, the forward output is 10 mW, and the full width at half maximum of the far field pattern is 25 × 30 degrees (approximately 1.1 × in terms of spot size).
0.9 μm). The optical semiconductor element 11 is made of InP.
This is an end face light receiving type (waveguide type) photodiode made of a system semiconductor. This optical semiconductor element 11 is an optical semiconductor element 1
This is for monitoring the rear output of 0.

The optical semiconductor elements 10 and 11 are die-bonded to predetermined positions of the substrate 40 by junction-down with Au-Sn solder. Markers for alignment with the substrate 40 are formed on the junction-side surfaces of the optical elements 10 and 11. Au-
The thickness of the Sn solder layer is 3 to 5 μm, and the height of the active layers of the optical elements 10 and 11 from the surface of the substrate 40 is 8 to 10 μm.
It is set to be.

The spherical lens 20 has a refractive index of 2.0 and a radius of 60.
The focal length is about 1 in resin with a refractive index of 1.4 μm.
00 μm. In this example, the refractive index of the lens is 1.4.
On the other hand, the refractive index of the translucent organic material is about 1.4 (a value for light having a wavelength of 1.3 μm).

The optical fiber 30 is a single mode quartz fiber. Outer diameter 125μm, spot size 5μ
m.

The distance between the optical element 10 and the spherical lens 20 is 130
μm, the distance between the spherical lens 20 and the optical fiber 30 is 390 μm.
When m is set, the enlargement ratio of the spot size becomes three times, and optical coupling is performed with an efficiency of about -4 dB. The allowable range for displacement in the direction perpendicular to the optical axis direction is about 1.5 μm. Light emitted from the optical element 10 is coupled to the fiber 30 and propagates through the fiber 30 along the optical axis direction 33 and is output.

The translucent resin 60 is made of a gel silicone resin. The refractive index of the translucent resin 60 at a wavelength of 1.3 μm is 1.4, which is substantially matched with the refractive index of the fiber 30.

In the case of this example, each optical component is mounted on a Si substrate (40, 41), and after electrical bonding is performed, a frame is formed with an adhesive (70), and a gel organic material 60 is formed. Is injected into the frame. Then, the lid 71 is attached.

FIG. 8 is a view for explaining an optical module using the exemplified optical assembly shown in the first embodiment. FIG. 8A is a partial cross-sectional structural view seen from above, and FIG.
(B) is a partial cross-sectional structure diagram viewed from a side surface parallel to the optical axis. In this example, the organic material 360 is provided in the entire package.

In the examples of FIGS. 8A and 8B, the optical assembly is composed of the optical semiconductor elements 310 and 311 and the spherical lens 3.
20, optical fiber 330, and V-grooved substrates 340, 34
1, a parallel plane substrate 350, a transparent resin 360, a lead frame 370, a package 380, and a cap 390.
It is composed of

The optical semiconductor elements 310 and 311 are provided on a substrate 340.
It is die bonded. Optical fiber strand 331
And the jacket 330 that covers the substrate 3
41 is fixed to a V-shaped groove 343 provided. At the same time, the jacket 330 is fixed to a concave portion provided on the substrate 341. The optical element 311 and the optical element 310, the optical element 310 and the lens 320, and the lens and the optical fiber 330 are optically coupled to each other.

Optical elements 311, 310 and lens 33
The substrate 340 on which the “0” is mounted is fixed on a die pad 350 extending from the lead frame 50. A jacket 330 is inserted into the fiber holder. The optical elements 311 and 310 and the lens 330 are covered with a translucent organic material 360.

The contents of the individual parts are the same as in the first embodiment. The optical element 311 is a semiconductor light receiving element, and the optical element 310 is a semiconductor light emitting element.

As described above, the V-groove 343 for the optical fiber, the V-groove 342 for the spherical lens, and the wiring 344 are formed on the substrate 310.

The lead frame 370 is a package 380
It is integrated with. The package 380 comprises an 8-pin dual in-line package (DIP). The outer shape of the package 380 is 14.6 mm in length (including 5 mm in length of the fiber holder), 6.3 mm in width, and 3 mm in height.

372-4 from the inner lead 372-1
373-5 through 373-5 are embedded in the package 500, and the outer leads 373-1 through 373-1.
373-8 is package 3 from 3-4 and 373-5
80 outside. Outer lead 373
-4-3 is electrically connected to the optical element 311 via wiring and wires 345 and 346. Similarly, the outer leads 373-6 and 373-7 are similarly connected to the optical element 310.
Is electrically connected to

(Embodiment 5) FIG. 9 is a view for explaining an optical module using the optical assembly exemplified in the first embodiment. 9A is a partial cross-sectional structural view as viewed from above, FIG. 9B is a partial cross-sectional structural view as viewed from a side surface parallel to the optical axis, and FIG. 9C is a cross-sectional view in a direction intersecting the optical axis. It is.

In the examples of FIGS. 9A, 9B, and 9C, the optical assembly is an optical semiconductor device 310, 311.
, A spherical lens 320, an optical fiber 330, V-groove substrates 340 and 341, a parallel plane substrate 350, a transparent resin 360, a lead frame 370 and a package 380.
It comprises a cap 390.

The optical semiconductor elements 310 and 311 are provided on a substrate 340.
It is die bonded. Optical fiber strand 331
And the jacket 330 that covers the substrate 3
41 is fixed to a V-shaped groove 343 provided. At the same time, the jacket 330 is fixed to a concave portion provided on the substrate 341. The optical element 311 and the optical element 310, the optical element 310 and the lens 320, and the lens and the optical fiber 330 are optically coupled to each other.

Optical elements 311, 310 and lens 33
The substrate 340 on which “0” is mounted is fixed on a die pad 350 extending from the lead frame 373. A jacket 330 is inserted into the fiber holder. The optical elements 311 and 310 and the lens 330 are covered with a translucent organic material 360.

The contents of the individual parts are the same as in the first embodiment. The optical element 311 is a semiconductor light receiving element, and the optical element 310 is a semiconductor light emitting element.

As described above, the V-groove 343 for the optical fiber, the V-groove 342 for the spherical lens, and the wiring 344 are formed on the substrate 310.

The lead frame 370 is a package 380
It is integrated with. The package 380 comprises an 8-pin dual in-line package (DIP). The outer shape of the package 380 is 14.6 mm in length (including 5 mm in length of the fiber holder), 6.3 mm in width, and 3 mm in height.

The inner leads 372-1 to 372-4
And 373-5 to 373-8 are embedded in the package 380, and the outer leads 373-1 to 373-8.
373-8 is package 3 from 3-4 and 373-5
80 outside. Outer lead 373
-4-3 is electrically connected to the optical element 311 via wiring and wires 345 and 346. Similarly, the outer leads 373-6 and 373-7 are similarly connected to the optical element 310.
Is electrically connected to

FIGS. 10A and 10B are examples of an optical module packaged with a resin by transfer molding. Except for the transfer molding, the components of each part are the same as those in the previous examples, and thus the details are omitted.

(Embodiment 6) In this embodiment, a typical example of an optical transmission system will be described. FIG. 11 is a diagram illustrating a typical example of an optical transmission system. In the optical transmission system 500, reference numeral 501 denotes a server, 510 denotes a transmitting device, 502 denotes an optical fiber, 503 denotes an optical distributor, 520 to 523 each indicate a receiving device, and 550 to 553 each indicate transmission to a terminal. Is transmitted to a plurality of terminals by the optical distributor 503. The transmission device 510 mainly includes a transmission LSI (integrated circuit device) unit 511 and an optical transmission module 512 for converting an electric signal to be transmitted into light and transmitting the light. On the other hand, receiving device 520-5
23 is mainly composed of the optical receiving module 530-5.
33, and a receiving LS for photoelectrically converting light from now on
It is composed of I sections 540-543. The present invention relates to the configuration of such a transmitting device or a receiving device.

The optical module exemplified in Embodiment 2-4 can be used as each transmitting module or optical receiving module.

As described above, according to the present invention, a highly reliable and inexpensive optical transmission system can be provided.

The basic structure of the optical coupling system according to the present invention and the basic structure of the optical module and the optical transmission system according to the first to fourth embodiments have been described.

The most important point of the present invention is to use a conventional laser diode which does not have a spot size conversion function while using a plastic package advantageous for cost reduction and a simple sealing method using a transparent organic material. An object of the present invention is to provide an optical system having a low optical coupling loss and a high-output optical transmission module. This makes it possible to realize low cost and high reliability.

[0123]

According to the first aspect of the present invention, it is possible to provide an optical coupling system having a low optical coupling loss and an optical module on the assumption that an optical semiconductor element having no spot size conversion function is used. is there.

That is, the effect of the lens can be provided even in a mode using a simple sealing method using a translucent organic material. Therefore, the laser diode and the optical fiber can be optically coupled with low optical coupling loss. A conventional laser diode having no spot enlarging portion can be used, a plastic case can be used, and reliability can be ensured. This is effective in reducing the cost of the transmission module.

According to the second means of the present invention, the allowable range for the positional deviation at the time of mounting components is widened, which is effective in improving the yield.

Further, even when the relative position of the optical component fluctuates due to the thermal expansion due to the change in the environmental temperature, the fluctuation of the optical coupling loss is reduced. For this reason, the reliability of the device can be improved.

According to the third means of the present invention, on the premise that an optical semiconductor element having no spot size conversion function is used, various optical components other than the optical components having a low optical coupling loss and the basic structure are used. It is possible to provide an optical coupling system and an optical module that can easily mount the optical module.
It is extremely useful for multifunctional devices.

For example, it is possible to insert another optical component (such as a built-in isolator) between the laser diode and the optical fiber, so that the optical transmission module can have another function. Thus, there is an effect of making the device multifunctional.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a basic structure of an optical coupling system according to the present invention.

FIG. 2 is a partial cross-sectional structural view of the optical assembly according to the first embodiment, as viewed from above and from the side.

FIG. 3 is a view showing a model of a fixed state of a spherical lens by a V groove.

FIG. 4 is a view showing a model of fixing an optical fiber by a V-groove in the same manner.

FIG. 5 is a partial cross-sectional structural view illustrating an optical assembly according to a second embodiment, as viewed from the top and side surfaces.

FIG. 6 is a partial cross-sectional structural view illustrating an optical assembly according to a third embodiment having an optical isolator, as viewed from above and from the side.

FIG. 7 is a partial sectional structural view of an optical assembly according to a fourth embodiment using a gel-like organic material, as viewed from above and from the side.

FIG. 8A is a partial cross-sectional structural view of an optical module using the optical assembly according to Embodiment 4 as viewed from the lower surface.

FIG. 8B is a partial cross-sectional structural view of an optical module using the optical assembly according to the fourth embodiment, as viewed from a direction parallel to the optical axis.

FIG. 9A is a partial cross-sectional structural view of an optical module using the optical assembly according to the fifth embodiment as viewed from the lower surface.

FIG. 9B is a partial cross-sectional structural view of an optical module using the optical assembly according to the fifth embodiment as viewed from a direction parallel to the optical axis.

FIG. 9C is a partial cross-sectional structural view of an optical module using the optical assembly according to the fifth embodiment, as viewed from a direction intersecting the optical axis.

FIG. 10A is a partial cross-sectional structural view showing an example of an embodiment to be a transfer mold as viewed from a lower surface of an optical module.

FIG. 10B is a partial cross-sectional structural view of an optical module showing an example of an embodiment to be a transfer mold, viewed from a direction parallel to an optical axis.

FIG. 11 is a diagram illustrating an optical transmission system according to the present invention.

[Explanation of symbols]

10, 110, 210, 310 ... optical element (laser diode), 11, 111, 211, 311 ... optical element (photodiode), 20, 120, 220, 320 ... spherical lens, 30, 130, 230, 330 ... light Fiber (core wire), 331 ... jacket, 40, 140, 24
0, 340... Substrate (ball lens mounting portion), 41, 241,
341,... Substrate (optical fiber mounting portion), 42, 142, 2
42, 342... V groove (sphere lens mounting portion), 43, 14
3, 243, 343... V groove (optical fiber mounting portion), 34
4: Wiring (part), 345, 346: Wire, 47, 1
47, 247... V groove (sphere lens mounting portion, adhesive flow stop), 50, 250, 350.
160, 260, 360: Organic transparent resin, 370: Lead frame, 371: Die pad (part), 372-
1-8: inner lead (part), 373-1-8: outer lead (part), 380: package (base), 3
90: package (lid), 500: optical transmission system, 5
01 server, 510 transmitting device, 502 optical fiber, 503 optical distributor, 520-523 receiving device, 5
30-533 ... optical receiving module 540-543 ... receiving LSI, 550-553 ... transmission to terminal.

Claims (8)

[Claims] An optical semiconductor device, a lens, and an optical waveguide, each having at least an optical component, at least a space forming an optical path between the optical components is filled with a solid translucent organic material, and An optical coupling system, wherein the relationship between the refractive index n1 and the refractive index n2 of the solid translucent organic material is n1> n2. 2. An optical semiconductor device, a lens, and at least each optical component of an optical waveguide, wherein at least a space forming an optical path between the optical components is filled with a solid translucent organic material, and An optical coupling system, wherein the relationship between the refractive index n1 and the refractive index n2 of the solid translucent organic material is n1> 1.2 × n2. 3. The optical coupling system according to claim 1, wherein the lens has a focal length of 1 mm or less in the solid translucent organic material. 4. The optical waveguide according to claim 1, wherein a divergence angle of light emitted from said optical semiconductor element is made to enter said optical waveguide within ± 10 degrees near a front surface of said optical waveguide.
Item 4. The optical coupling system according to Item 3. 5. An optical semiconductor device, a lens, and an optical waveguide having at least each optical component, at least a space forming an optical path between the optical components is filled with a solid translucent organic material, and the lens is refracted. The relationship between the refractive index n1 and the refractive index n2 of the solid translucent organic material is n1> n2, the position of the lens and the optical waveguide is determined by a V-shaped groove provided on a predetermined substrate, and An optical module, wherein a space between the optical components is filled with a solid translucent organic material. 6. An optical semiconductor device, a lens, and at least each optical component of an optical waveguide, at least a space forming an optical path between the optical components is filled with a solid translucent organic material, and the lens is refracted. The relationship between the refractive index n1 and the refractive index n2 of the solid translucent organic material is n1> 1.2 × n2,
The position of the lens and the optical waveguide is determined by a V-shaped groove provided on a predetermined substrate, and a space between the optical components is filled with a solid translucent organic material. Optical module. 7. The optical module according to claim 5, wherein the optical module is sealed with an organic resin mold.
An optical module according to the item. 8. An optical coupling system according to any one of claims 1 to 4, or an optical module according to any one of claims 5 to 7. Optical transmission system.