JP5386290B2 - Optical coupling structure and optical transceiver module - Google Patents

Description

  The present invention relates to an optical module used in an optical communication technique, an optical transmission technique, and an optical information recording technique, and more particularly to an optical coupling structure between an optical semiconductor element and an optical transmission path in the optical module.

The optical module includes an optical semiconductor element mounted on a substrate and an optical transmission path arranged so that the optical axis is parallel to the substrate.
Conventionally, in this type of optical module, in order to optically couple the light emitting / receiving portion of the optical semiconductor element and the end of the optical transmission path, it is installed on the optical semiconductor element 101 as shown in FIG. A structure in which the optical transmission path 104 (particularly its core 105) and the optical semiconductor element 101 are optically connected (optically coupled) by combining the condenser lens 102 and the optical path conversion mirror 103 is generally used. .

  However, the condensing lens 102 and the optical path conversion mirror 103 need to have the refractive index of the lens, the reflectance of the mirror, and the like adjusted to desired values. In addition, the number of parts required for optical coupling is large, and it is necessary to precisely match the positional relationships among the optical semiconductor element 101, the condenser lens 102, the optical path conversion mirror 103, and the optical transmission path 104. For this reason, the cost of parts and the cost of work were high, which was a major factor in increasing costs.

In order to reduce the manufacturing cost of such optical modules and provide optical modules at lower costs,
For example, Patent Document 1 discloses an optical device including a guide groove on the surface of an optical mounting substrate and a tapered surface positioned on the optical axis of an optical fiber mounted in the guide groove, and a mirror is formed on the tapered surface. Has been proposed.
In Patent Document 2, a V-groove having a reflective surface formed obliquely at a position facing the end of the optical waveguide is formed, and the core of the optical waveguide is interposed between the end of the optical waveguide and the reflective surface. A coupling structure of an optical waveguide and a light receiving element, which is filled with a refractive index matching agent having substantially the same refractive index and includes a light receiving element that receives outgoing light reflected by a reflecting surface, has been proposed.

Further, in Patent Document 3, as an optical component joining method capable of simplifying connection between optical components in an optical transceiver module with high accuracy, an optical fiber and a light receiving and emitting element arranged so that optical axes are substantially coincided with each other are disclosed. Is stretched by pressing through an uncured transparent resin composition, drawn back to stretch an uncured transparent resin composition (photocurability, thermosetting, or thermoplastic), and then stretched transparent resin composition An optical component joining method for curing an object is described.
Further, in Patent Document 4, a semiconductor laser element, a monitor photodiode, and an optical fiber are sealed in a transparent resin, and the rear output light of the semiconductor laser element is reflected at the interface between the transparent resin and air and enters the monitor photodiode. A semiconductor laser device has been proposed.

JP 2003-167175 A Japanese Patent No. 2985791 JP-A-9-197196 Japanese Patent Laid-Open No. 2000-269584

  However, the optical device of Patent Document 1 requires a preparation of a mold for forming a guide groove and a tapered surface, and a process of forming a tapered mirror, which increases the cost. . Furthermore, since it is necessary to perform flip chip bonding with the optical semiconductor element facing downward on the optical mounting substrate having the guide groove, a wire bond is required from the optical semiconductor element, for example, between the light receiving element and the amplifier IC. There is a problem that the line length to the IC becomes long and it becomes easy to ride noise, and the optical semiconductor element that is flip-chip bonded is difficult to detect a connection defect because it is difficult to inspect the appearance after mounting. It was.

  In the optical coupling structure disclosed in Patent Document 2, a V-groove having a tapered surface is formed at a position facing a very thin optical fiber, a total reflection mirror is formed on the tapered surface, and the end of the optical waveguide is reflected from the end. Since it is necessary to fill the refractive index matching agent between the surfaces, there is a problem that the number of steps is increased and the cost is increased.

  In addition, in the optical component joining method of Patent Document 3, since it is necessary to arrange the optical axes of the optical fiber and the light receiving and emitting element to substantially coincide with each other, it can be applied only when both optical axes are coaxial, For example, there is a problem that it cannot be applied when both optical axes are perpendicular to each other.

  Further, since the semiconductor laser device of Patent Document 4 is intended to monitor the rear output light of the semiconductor laser element having a large aperture angle, it can be used even if the optical coupling efficiency is low. However, when the optical signal is incident on the light receiving element from the optical fiber having a small aperture angle, or when the optical signal is incident on the optical fiber from the light emitting element, the reliability of the transmission of the optical signal is ensured if the coupling efficiency is low. There was a problem that it was difficult. In addition, the position / shape of the resin interface serving as the reflection surface is considered to depend on the amount of transparent resin applied and the step shape of the substrate. However, if a step is formed on the substrate, the cost becomes high. In addition, the reflection surface must exist at the intersection where the optical axis perpendicular to the semiconductor laser element and the optical axis perpendicular to the monitor PD element intersect, but the resin interface is located just at the intersection. It is not easy to form.

  The present invention has been made in view of the above circumstances, and an optical semiconductor element and an optical transmission in an optical module including an optical coupling unit that can be manufactured at low cost and can transmit an optical signal with higher efficiency. It is an object to provide an optical coupling structure with a path.

In order to solve the above-mentioned problems, the present invention crosses an optical semiconductor element having a light emitting / receiving portion on the upper surface and mounted on a substrate on the lower surface side at a predetermined angle with respect to the optical axis of the optical semiconductor element. And an optical fiber disposed apart from the mounting surface of the substrate, and an optical coupling part for optically coupling between the optical semiconductor element and the optical fiber. The coupling portion is made of a resin that is transparent to transmitted light, and the resin is in close contact with at least a part of the light receiving and emitting part of the optical semiconductor element and at least a part of the end of the optical fiber ,
The outer surface of the resin constituting the optical coupling portion has a shape recessed toward the light emitting / receiving portion of the optical semiconductor element and the end portion of the optical fiber , and the optical coupling portion of the optical semiconductor element The resin does not exist at the position of the intersection where the optical axis and the optical axis of the optical fiber intersect, and the position where the outer surface of the resin faces the light emitting / receiving section is between the intersection and the light emitting / receiving section. And the position where the outer surface of the resin faces the end of the optical fiber provides an optical coupling structure between the intersection and the end of the optical fiber .

It is preferable that the resin constituting the optical coupling portion is within a range located above the upper surface of the optical semiconductor element.
It is preferable that the resin constituting the optical coupling portion is within a range below the height of the upper end of the end face of the optical fiber .
It is preferable that the periphery of the optical coupling portion is covered with a gas.
It is preferable that the periphery of the optical coupling portion is covered with a clad resin layer having a refractive index lower than that of the resin constituting the optical coupling portion.
It is preferable that the power supply wiring of the optical semiconductor element is covered with the clad resin layer.

The present invention includes a light receiving element and a light emitting element mounted on a mounting surface of the same substrate, a first optical fiber and a second optical fiber disposed apart from the mounting surface of the substrate, and the light receiving element. comprising the first optical coupling portion for optically coupling between the first optical fiber, and said light emitting element and the second optical coupling portion for optically coupling between the second optical fiber The light receiving element, the first optical fiber, and the first optical coupling portion constitute a first optical coupling structure, and the light emitting element, the second optical fiber, and the second optical coupling portion are the second light. Provided is an optical transmission / reception module having a coupling structure, wherein one or both of the first optical coupling structure and the second optical coupling structure constitute the optical coupling structure according to the present invention. To do.

According to the present invention, the optical coupling portion can be manufactured at a low cost without using a large number of components, and an optical signal can be transmitted with higher efficiency.
Since the light emitting / receiving portion of the optical semiconductor element can be mounted toward the side opposite to the mounting surface of the substrate, mounting by die bonding or wire bonding becomes possible. As a result, it is possible to connect wires important for transmission characteristics with the shortest line length, and it is difficult for noise to ride, and good transmission characteristics can be obtained. Further, it is easy to inspect the appearance of bonding, and it is easy to find a connection failure.

It is sectional drawing which shows an example of the optical module provided with the optical coupling structure which concerns on the 1st form example of this invention. It is sectional drawing explaining the manufacturing process of an optical coupling part. It is sectional drawing explaining the manufacturing process of an optical coupling part. It is sectional drawing which shows an example of the optical module provided with the optical coupling structure which concerns on the 2nd form example of this invention. It is sectional drawing explaining the shape of an optical coupling part. It is a perspective view which shows an example of the optical transmission / reception module of this invention. It is sectional drawing explaining the optical coupling structure of this invention. It is sectional drawing explaining the case where the outer surface of an optical coupling part is convex shape. It is sectional drawing explaining the case where an optical coupling part is a 45 degree mirror. It is sectional drawing explaining the case where an optical coupling part is a big 45 degree mirror. It is the schematic explaining the method of the optical coupling in the conventional optical module.

Hereinafter, based on an embodiment, the present invention will be described with reference to the drawings.
FIG. 1 shows an example of an optical module including the optical coupling structure according to the first embodiment.
The optical module 5 shown in FIG. 1 is disposed along the mounting surface 4a of the substrate 4 and the optical semiconductor element 1 mounted on the mounting surface 4a, which is the upper surface of the substrate 4, and away from the mounting surface 4a of the substrate 4. The optical transmission path 2 and an optical coupling portion 3 for optically coupling the optical transmission path 2 and the optical semiconductor element 1 are provided.

The optical semiconductor element 1 has a light emitting / receiving unit 1a as a part for emitting or entering an optical signal.
When the optical semiconductor element 1 is a light receiving element, the light emitting / receiving unit 1a is a light receiving unit. When the optical semiconductor element 1 is a light emitting element, the light emitting / receiving unit 1a is a light emitting unit.
Examples of the light emitting element include a light emitting diode (LED), a laser diode (LD), and a surface emitting laser (VCSEL).
A photodiode (PD) etc. are mentioned as a light receiving element.
The light emitting / receiving unit 1 a is provided on the upper surface 1 c of the optical semiconductor element 1. The vertical direction in the present invention is based on the mounting surface 4a on which the optical semiconductor element 1 is mounted on the substrate 4, and the direction away from the substrate 4 is upward (upward in FIG. 1), and the direction approaching the substrate 4 is downward (in FIG. 1). Down). In addition, a direction perpendicular to the up-down direction (left-right direction in FIG. 1) according to the above definition is defined as a horizontal direction. The vertical direction and horizontal direction in the present invention do not depend on the direction of gravity unless the transparent resin 31 is uncured and has fluidity as shown in FIGS.

The optical semiconductor element 1 is electrically connected to the circuit wiring 6 formed on the mounting surface 4a of the substrate 4 by a bonding material. For example, in the case of the present embodiment, the circuit wiring 6 is electrically connected by a power supply wiring composed of an electrode (not shown) formed on the upper portion (surface) of the optical semiconductor element 1 and the wire wiring 7. Yes. Further, the lower surface (back surface) 1d of the optical semiconductor element 1 and the circuit wiring 6 are electrically connected by a conductive adhesive (not shown).
For the substrate 4, various general insulating substrates such as a glass epoxy substrate and a ceramic substrate can be used. Examples of the wire wiring 7 include a gold (Au) wire, an aluminum (Al) wire, a copper (Cu) wire, and the like.

Examples of the optical transmission line 2 include optical fibers such as silica-based optical fibers and plastic optical fibers (POF), and substrate-type optical waveguides such as quartz optical waveguides and polymer optical waveguides.
In the optical transmission line 2, it is preferable that the optical axis 2b is linear at least in the vicinity of the end 2a so that the direction of light entering and exiting the optical coupling unit 3 is constant.

  The optical semiconductor element 1 is arranged such that the optical axis 1b intersects the optical axis 2b of the optical transmission line 2 (particularly, the optical axis 2b in the vicinity of the end 2a) at a predetermined angle θ. The optical axes 1b and 2b of the optical semiconductor element 1 and the optical transmission line 2 are preferably arranged perpendicularly (or substantially perpendicular) to each other.

The optical coupling unit 3 is made of a resin that is transparent to transmitted light. The resin constituting the optical coupling unit 3 is in close contact with at least a part of the light emitting / receiving unit 1 a of the optical semiconductor element 1 and at least a part of the end 2 a of the optical transmission path 2.
The transparent resin here refers to a resin capable of transmitting light transmitted between the optical semiconductor element 1 and the optical transmission line 2. Therefore, the color tone is not necessarily limited to a colorless and transparent tone under visible light. Further, since the optical path length in the resin through which light is transmitted is short, it is only necessary to have some degree of transparency.
As the transparent resin, for example, a UV curable resin or a thermosetting resin can be used.
Specific examples of the transparent resin include acrylic resins, epoxy resins, and silicone resins.

In FIG. 1, the shape of the optical coupling unit 3 is such that the optical coupling unit 3 covers the entire surface of the end 2 a of the optical transmission line 2, and the upper end of the optical coupling unit 3 adheres to the upper part of the optical transmission path 2. As in the optical module 5A shown in FIG. 5, a part of the end 2a of the optical transmission line 2 may be exposed outside the optical coupling unit 3A. In this case, the resin constituting the optical coupling portion 3A is in the plane including the optical axis 1b of the optical semiconductor element 1 and the optical axis 2b of the optical transmission path 2 (in the plane on the paper surface of FIG. 5) and out of the plane ( The front side and the back side of the paper surface of FIG. 5 are within the range below the height 2d (see FIG. 7) of the upper end 2c of the end surface 2a of the optical transmission line 2, and the light emitting / receiving portion 1a of the optical semiconductor element 1 The distance from the optical coupling unit 3 to the outer surface 3a and the distance from the end surface 2a of the optical transmission path 2 to the outer surface 3a of the optical coupling unit 3 become shorter. The entire cross-sectional area of the core (not shown) of the optical transmission line 2 is preferably covered with the optical coupling portion 3A.
The height 2d of the upper end 2c is a height with respect to the mounting surface 4a of the substrate 4 (distance in a direction perpendicular to the mounting surface 4a).

Here, in the case where the optical semiconductor element 1 is a light receiving element, the optical coupling unit 3 is configured such that the light incident on the optical coupling unit 3 from the optical transmission path 2 is a transparent resin that constitutes the optical coupling unit 3 and an external gas ( For example, the light is reflected by the difference in refractive index from the interface 3 a with air or dry nitrogen gas, and enters the optical semiconductor element 1.
When the optical semiconductor element 1 is a light emitting element, the light incident on the optical coupling unit 3 from the optical semiconductor element 1 is a refractive index of the interface 3a between the transparent resin constituting the optical coupling unit 3 and the external gas. The light is reflected by the difference and enters the optical transmission line 2.

The optical coupling unit 3 of the present embodiment has the following configuration in order to easily realize optical coupling between the optical semiconductor element 1 and the optical transmission line 2.
The outer surface 3a of the optical coupling part 3 forms an interface with an external gas, and the transparent resin constituting the optical coupling part 3 is composed of an optical axis 2b of the optical transmission path 2 and an optical axis 1b of the optical semiconductor element 1. The outer surface 3a of the optical coupling unit 3 (the interface between the optical coupling unit 3 and the external gas) is not located at the intersecting point P, and the end of the light emitting / receiving unit 1a and the optical transmission path 2 of the optical semiconductor element 1 The shape is recessed on the side of the portion 2a.

Here, in order for the outer surface 3a of the optical coupling portion 3 to have a recessed shape, at least
(1) A concave surface portion 11 having a shape in which a position A facing the light emitting / receiving portion 1a is recessed toward the light emitting / receiving portion 1a,
(2) A concave surface portion 12 having a shape in which the position B facing the end 2a of the optical transmission path 2 is recessed toward the end 2a of the optical transmission path 2,
(3) A concave surface portion 13 having a concave shape between a position A facing the light emitting / receiving section 1a and a position B facing the end 2a of the optical transmission line 2;
You need to have
A portion that is not involved in light transmission, for example, a portion 3b that is on the upper side of the optical transmission line 2 in FIG. 1, or a portion that is sandwiched between the lower side of the optical transmission line 2 and the upper surface 1c of the optical semiconductor element 1 It is acceptable that 3c has a convex shape.

Here, the concave surface portion 11 on the light emitting / receiving portion 1a side in (1) is, for example, near the position A where the optical axis 1b of the optical semiconductor element 1 intersects the outer surface 3a of the resin, and the outer surface 3a of the resin is on the resin side. What is necessary is just to form the concave surface used as a concave.
The concave surface portion 12 on the optical transmission line 2 side in (2) is, for example, in the vicinity of the position B where the optical axis 2b of the optical transmission line 2 intersects the outer surface 3a of the resin, and the outer surface 3a of the resin is recessed toward the resin side. It is only necessary to form a concave surface.
In addition, the concave surface portion 13 in the intermediate portion of (3) includes, for example, a position A where the optical axis 1b of the optical semiconductor element 1 intersects the outer surface 3a of the resin, and an optical axis 2b of the optical transmission line 2 is the outer surface 3a of the resin It suffices that the line segment AB connecting with the intersecting position B passes through the outside of the resin (external gas side) between AB and forms a concave surface in which the outer surface 3a of the resin is concave.

When the optical semiconductor element 1 is a light receiving element, the optical coupling portion 3 of the present embodiment has a shape in which the outer surface 3a of the optical coupling portion 3 is recessed, so that it is emitted from the optical transmission line 2 as shown in FIG. When the light 10 reflected by the outer surface 3 a of the optical coupling unit 3 is received by the light emitting / receiving unit 1 a of the optical semiconductor element 1, the reflection position on the outer surface 3 a of the optical coupling unit 3 is set to the optical semiconductor element 1 and the optical transmission line 2. The optical path length in the optical coupling unit 3 can be shortened.
The same applies to the case where the optical semiconductor element 1 is a light emitting element and the light 10 emitted from the light emitting / receiving section 1a of the optical semiconductor element 1 is reflected by the outer surface 3a of the optical coupling section 3 and is incident on the optical transmission line 2.
This is because, as shown in FIG. 7, when light is emitted from the optical transmission line 2 (or light receiving and emitting unit 1 a), it has a certain spread angle and travels while spreading in the optical coupling unit 3. .
As shown in FIG. 8, when the outer surface 3a of the optical coupling unit 3 has a convex shape, the position where the light 10 is reflected by the outer surface 3a of the optical coupling unit 3 becomes far, and the optical path length in the optical coupling unit 3 becomes longer. As the length increases, the light diffuses and the connection loss increases.
Therefore, as shown in FIGS. 1 and 7, by forming the outer surface 3a of the optical coupling unit 3 into a concave shape, the optical path length in the optical coupling unit 3 can be shortened and the connection loss can be reduced.

As shown in FIG. 9, when the resin 300 is formed so as to function as a 45 ° mirror, the position of the reflection surface 301 is far and the optical path is long, so that the light 10 spreads and connection loss increases. End up.
As shown in FIG. 10, when the resin 310 that becomes a 45 ° mirror is large and exceeds the height 2d of the upper end 2c of the end surface 2a of the optical transmission line 2, the distance from the end surface 2a to the reflecting surface 311 and the light 10 The optical path becomes even longer.
For this reason, it is preferable that the range in which the optical coupling portion 3 exists in the vertical direction is within the range below the height 2d of the upper end 2c of the end face 2a of the optical transmission line 2.
Moreover, as a range where the optical coupling part 3 exists in a horizontal direction, it is preferable that the whole is settled on the optical semiconductor element 1 (above the upper surface 1c).

That is, the optical coupling part 3 of the present embodiment has these concave surface parts 11, 12, and 13, so that the position and angle as the reflective surface can be precisely controlled with respect to the shape of the interface of the transparent resin. Reliable optical coupling can be realized with lower fabrication accuracy. In addition, the end portion 2a of the optical transmission line 2 and the light receiving / emitting portion 1a of the optical semiconductor element 1 are optically coupled by the optical coupling portion 3 made of a single transparent resin, which is extremely low cost and simple. It can be produced by a process.
The single transparent resin here means that the component (composition) is uniform (single), the transmittance for light of a specific wavelength is uniform, and is not physically two or more layers (no interface). The meaning is also included.

  These concave surface portions 11 to 13 are optically transmitted to and from the optical semiconductor element 1 by reflection at the interface 3a of the transparent resin, nearer to the positions of the light emitting / receiving portion 1a of the optical semiconductor element 1 and the end portion 2a of the optical transmission path 2. When optically coupling with the path 2, the range in which the light diffuses becomes narrow, and loss can be reduced. For this reason, the optical coupling portion 3 is such that the resin does not exist at the position of the intersection P where the optical axis 1b of the optical semiconductor element 1 and the optical axis 2b of the optical transmission line 2 intersect, and the outer surface 3a of the resin receives and emits light. The position A facing the portion 1a is between the intersection P and the light emitting / receiving portion 1a, and the position B where the outer surface 3a of the resin faces the end 2a of the optical transmission path 2 is between the intersection P and the optical transmission path 2. It is preferably between the end 2a.

  Furthermore, since the periphery of the transparent resin is covered with gas in the optical coupling unit 3 of this embodiment, the refractive index difference with the transparent resin is increased, and the reflectance of light at the interface can be increased. Thereby, the light coupling efficiency can be further improved.

  Since the optical semiconductor element 1 can be mounted on the mounting surface 4a of the substrate 4 such that the light emitting / receiving portion 1a is opposite to the mounting surface 4a (upper side in FIG. 1) of the substrate 4, it is possible to use die bonding or wire bonding. Implementation becomes possible. As a result, it is possible to connect wires important for transmission characteristics with the shortest line length, and it is difficult for noise to ride, and good transmission characteristics can be obtained. Further, it is easy to inspect the appearance of bonding, and it is easy to find a connection failure.

Next, in the description of the manufacturing method of the optical module of the present invention, a manufacturing method of the optical module 5 having the configuration shown in FIG.
As shown in FIG. 2, a circuit wiring 6 is formed in advance on the mounting surface 4a and a substrate 4 on which the optical semiconductor element 1 is mounted is prepared, and a precision dispenser or the like is provided to the light emitting / receiving portion 1a of the optical semiconductor element 1. An uncured transparent resin 31 is applied using a resin dipping device 29.
It is desirable to apply the transparent resin 31 within a range that fits on the upper surface 1 c of the optical semiconductor element 1.

Subsequently, as shown in FIG. 3, the end 2 a of the optical transmission line 2 is inserted into the optical semiconductor element 1 toward the transparent resin 31 placed on the optical semiconductor element 1 (in the direction of arrow L).
Then, the optical transmission path 2 inserted into the transparent resin 31 is moved away from the optical semiconductor element 1. At this time, the optical transmission line 2 is slowly pulled up from the optical semiconductor element 1 obliquely upward (in the direction of arrow R).

  Thereafter, according to the type of the transparent resin 31, for example, UV (ultraviolet) irradiation or heating is performed as necessary to cure the transparent resin 31. As a result, the optical coupling unit 3 that optically connects (optically couples) the optical semiconductor element 1 and the optical transmission line 2 is formed, and the optical module 5 is completed.

  In FIG. 3, the shape of the transparent resin 31 after the optical transmission path 2 is pulled up in an oblique direction is (1) the interfacial tension between the transparent resin 31 and the optical semiconductor element 1, and (2) the transparent resin 31 and the optical transmission path. 2 and (3) the surface tension between the transparent resin 31 and the external gas. That is, (A) a member of the optical semiconductor element 1, the optical transmission path 2, and the transparent resin 31, and (B) a state of the member such as the surface state of the optical semiconductor element 1 and the optical transmission path 2 and the viscosity of the transparent resin 31, (C) Depends on the mounting conditions such as the application amount of the transparent resin 31 in FIG. 2 and the insertion amount and pull-up amount of the optical transmission path 2 in FIG. If the conditions (A), (B), and (C) are the same, the shape of the transparent resin 31 is naturally the same.

  The amount of pulling up of the optical transmission line 2 in the R direction has an optimum value according to the structure of the optical transmission line 2 and the optical semiconductor element 1 used, the coating amount of the transparent resin 31, and the like. If such optimum values are examined in advance, it is possible to automate all the manufacturing processes described above, thereby realizing further labor saving. In addition, when the optical coupling unit 3 is manufactured, it is not necessary to transmit light between the optical semiconductor element 1 and the optical transmission line 2, and passive alignment is possible. Even if the position of the passive alignment is slightly deviated from the optimal position due to a change in the amount of resin applied, the transparent semiconductor 31 is connected to the surface of the transparent resin 31 because the optical semiconductor element 1 and the optical transmission path 2 are connected. Since it is deformed together with the optical transmission line 2, the coupling efficiency of the optical coupling unit 3 is hardly lowered, and the alignment tolerance is large. In active alignment performed while transmitting light, if a photocurable resin is used, the resin may be cured during the alignment of the optical fiber, but according to passive alignment, there is no possibility that the resin will be cured in the middle. .

Thus, according to the manufacturing method of the optical module of this embodiment, the transparent resin 31 is placed on the optical semiconductor element 1, the optical transmission line 2 is inserted into the transparent resin 31 and pulled up in an oblique direction, and then the transparent resin It is possible to form the optical coupling portion 3 that optically connects (optically couples) the optical semiconductor element 1 and the optical transmission path 2 only by curing 31. For this reason, when the optical coupling part 3 is formed, it is possible to manufacture an optical module at a very low cost with a small number of steps and a small number of components without the need for a metal mold or the like.
In addition, the formation method of the optical coupling part 3 is not limited to the said method. For example, the tip of the optical transmission line 2 is disposed above the optical semiconductor element 1, and a transparent resin 31 is provided so as to cover the tip of the optical transmission line 2 and the light emitting / receiving portion 1 a of the optical semiconductor element 1. Alternatively, the transparent resin 31 may be cured after the tip of the optical transmission line 2 is pulled up in an oblique direction. That is, in order to form the optical coupling portion 3 by pulling up the tip of the optical transmission line 2 in the transparent resin 31 in an oblique direction, a step of arranging the tip of the optical transmission line 2 on the optical semiconductor element 1, and transparent The order of the steps for arranging the resin 31 may be reversed.
In this case, instead of the above condition (C), the condition (C ′): “mounting conditions such as the coating amount of the transparent resin 31 and the position and the lifting amount of the optical transmission line 2 before lifting” are adopted. If the conditions (A), (B), and (C ′) are the same, the shape of the transparent resin 31 is naturally the same. In addition, if the procedure is different, the optimum value of the amount of pulling up of the optical transmission line 2 in the R direction may change. Therefore, it is desirable to examine the optimum value by performing an experiment in the same procedure as in practice.

2. Description of the Related Art Conventionally, it is known to use, as a convex lens or a concave lens, a shape that is naturally determined by physical properties such as surface tension and interface tension in sealing applications such as LEDs. Patent Document 4 describes a semiconductor laser device in which a transparent resin is coated along a step of a substrate so that backward output light of the semiconductor laser element is incident on a monitor photodiode.
Since the optical module manufacturing method according to the present embodiment does not require the transparent resin to adhere to the substrate, it is not necessary to add a processing step (such as a V groove or a step) of the substrate 4 when forming the optical coupling portion 3. The substrate is not limited to a substrate that can be used for plane anisotropic etching such as a silicon substrate, but can be manufactured at low cost even with a substrate with low workability such as a glass epoxy substrate.

FIG. 4 shows an example of an optical module provided with the optical coupling structure according to the second embodiment.
The optical module 9 shown in FIG. 4 includes an optical semiconductor element 1 mounted on the mounting surface 4a of the substrate 4 and optical transmission arranged along the mounting surface 4a of the substrate 4 and spaced from the mounting surface 4a of the substrate 4. A path 2, an optical coupling portion 3 that optically couples between the optical transmission path 2 and the optical semiconductor element 1, and a clad resin layer 8 that covers the periphery of the optical coupling portion 3 are provided.

In the optical module 9 of this embodiment, the periphery of the optical coupling unit 3 is covered with a clad resin layer 8 made of a second resin having a refractive index lower than that of the transparent resin (first resin) constituting the optical coupling unit 3. Is different from the optical module 5 according to the first embodiment. The optical semiconductor element 1, the optical transmission line 2, the substrate 4, the circuit wiring 6, the wire wiring 7, and the like can be configured in the same manner as the optical module 5 according to the first embodiment.
Since the clad resin layer 8 is formed of a resin having a refractive index lower than that of the transparent resin constituting the optical coupling portion 3, light transmitted through the optical coupling portion 3 is incident on the clad resin layer 8 and scattered. Can be suppressed. Furthermore, the periphery of the clad resin layer 8 can be sealed with a resin (not shown) having a higher refractive index than that of the optical coupling portion 3.

The refractive index here refers to the refractive index at the wavelength of light transmitted between the optical semiconductor element 1 and the optical transmission line 2. For example, a UV curable resin or a thermosetting resin can be used as the second resin. Specific examples of the second resin include acrylic resins, epoxy resins, and silicone resins.
The clad resin layer 8 can be formed by applying and curing a second resin after forming the optical coupling portion 3 as shown in FIGS.

The first resin constituting the optical coupling part 3 does not exist at the position of the intersection P where the optical axis 2b of the optical transmission line 2 and the optical axis 1b of the optical semiconductor element 1 intersect, and the optical coupling part 3 and the clad The interface 3a with the resin layer 8 has a shape recessed on the opposite side to the position of the intersection P.
The clad resin layer 8 in the optical module 9 of this embodiment functions as a clad resin for the optical coupling portion 3. Further, when the optical semiconductor element 1 is a light receiving element, the optical coupling unit 3 is configured such that light incident on the optical coupling unit 3 from the optical transmission path 2 is coupled with the interface 3a between the optical coupling unit 3 and the clad resin layer 8. The light is reflected by the difference in refractive index and enters the optical semiconductor element 1. When the optical semiconductor element 1 is a light emitting element, the light incident on the optical coupling part 3 from the optical semiconductor element 1 is reflected by the refractive index difference between the optical coupling part 3 and the interface 3 a between the clad resin layer 8. Is incident on the optical transmission line 2.

Further, in the example shown in FIG. 4, the optical transmission line 2 is fixed to the mounting surface 4 a of the substrate 4 by the clad resin layer 8. Thereby, the direction of the optical axis 2b in the vicinity of the end 2a of the optical transmission path 2 is difficult to move, and even when an external force is applied to the optical transmission path 2, deterioration of optical coupling can be suppressed.
Moreover, since the wire wiring 7 is covered and protected by the clad resin layer 8, it is possible to prevent the wire wiring 7 (feeding wiring) that is easily damaged by external stress from being disconnected.
In addition, since the end 2a of the optical transmission line 2, the optical coupling unit 3, and the optical semiconductor element 1 are covered with the clad resin layer 8, it can be protected from external stress. The mechanical strength of the entire optical coupling structure between the optical semiconductor element 1 and the optical transmission line 2 can be increased.
Thus, when the clad resin layer 8 is provided so as to function as a protective layer for the wire wiring 7 or a protective layer for the optical coupling structure, the protective layer can be easily formed.

FIG. 6 is a perspective view showing an example of the optical transceiver module of the present invention. The optical transceiver module 50 according to the present embodiment includes a first optical semiconductor element 51 a that is a light receiving element and a second optical semiconductor element 51 b that are light emitting elements mounted on a mounting surface 54 a of the same substrate 54, and Optical coupling between the first optical transmission line 52a and the second optical transmission line 52b, which are spaced apart from the mounting surface 54a, and the first optical semiconductor element 51a and the first optical transmission line 52a. And a second optical coupling portion 53b that optically couples between the second optical semiconductor element 51b and the second optical transmission line 52b.
The first optical semiconductor element 51a, the first optical transmission path 52a, and the first optical coupling portion 53a constitute a first optical coupling structure, and the second optical semiconductor element 51b, the second optical transmission path 52b, and The second optical coupling portion 53b constitutes a second optical coupling structure.

In the case of the optical transceiver module 50 according to the present embodiment, both the first optical coupling structure and the second optical coupling structure constitute the same optical coupling structure as the optical module 9 shown in FIG.
Specifically, the optical coupling portions 53a and 53b are made of a resin that is transparent to the transmitted light, and the first resin is at least part of the light receiving and emitting portions of the optical semiconductor elements 51a and 51b and the optical transmission path. The transparent resin that is in close contact with at least a part of the end portions of 52a and 52b and constitutes the optical coupling portions 53a and 53b intersects the optical axes of the optical transmission lines 52a and 52b and the optical axes of the optical semiconductor elements 51a and 51b. The interface between the optical coupling portions 53a and 53b is recessed at the opposite side to the position of the intersection.
Thereby, also in the optical coupling from the first optical transmission line 52a to the first optical semiconductor element 51a that is the light receiving element, the second optical semiconductor element 51b that is the light emitting element to the second optical transmission line 52b. Also in optical coupling, it is possible to produce an optical coupling structure at a low cost and with a simple process.

  In the case of the optical transceiver module 50 of this embodiment, two optical semiconductor elements 51a and 51b are mounted side by side on a common substrate 54. These optical semiconductor elements 51 a and 51 b are electrically connected to circuit wiring 56 formed on the substrate 54 by a bonding material. For example, in the case of the present embodiment, the circuit wiring 56 is electrically connected to the circuit wiring 56 by a power supply wiring including electrodes (not shown) formed on the upper portions (surfaces) of the optical semiconductor elements 51a and 51b and the wire wirings 57a and 57b. It is connected to the. Further, the back surfaces of the optical semiconductor elements 51a and 51b and the circuit wiring 56 are electrically connected by a conductive adhesive (not shown). The circuit wiring 56 and the wire wirings 57a and 57b are independently provided with a wiring connected to the light emitting element and a wiring connected to the light receiving element.

In the case of the optical transceiver module 50 of this embodiment, the first optical transmission path 52a and the second optical transmission path 52b are integrally covered with a common covering material 58. For this reason, when the optical coupling portions 53a and 53b are manufactured, when the optical transmission lines 52a and 52b are inserted into the transparent resin (L direction) and then pulled in the oblique direction (R direction) in the same manner as in FIG. The operation can be simplified by operating the optical transmission lines 52a and 52b at a time.
As the plurality of optical transmission lines 52a and 52b integrated with the common covering material 58, an optical fiber tape core, a substrate type optical waveguide, or the like can be used. The covering material 58 may be opaque to the light transmitted through the optical transmission paths 52a and 52b.

Further, the optical semiconductor elements 51a and 51b, the optical transmission lines 52a and 52b, and the optical coupling portions 53a and 53b may be covered with a single clad resin layer 59.
Since the clad resin layer 59 is formed of a resin having a refractive index lower than that of the transparent resin constituting the optical coupling portions 53a and 53b, light transmitted through the optical coupling portions 53a and 53b is directed toward the clad resin layer 59. It can suppress that it injects into and scatters. Furthermore, the periphery of the clad resin layer 59 can be sealed with a resin (not shown) having a higher refractive index than that of the optical coupling portions 53a and 53b.

In the case of the optical transceiver module 50 according to this embodiment, the optical transmission paths 52 a and 52 b integrated by the common covering material 58 are fixed to the mounting surface 54 a of the substrate 54 by the clad resin layer 59. Thereby, the direction of the optical axis near the ends of the optical transmission paths 52a and 52b is difficult to move, and deterioration of optical coupling can be suppressed even if an external force acts on the optical transmission paths 52a and 52b.
Further, since the wire wirings 57a and 57b are covered and protected by the clad resin layer 59, it is possible to prevent the wire wirings 57a and 57b (feeding wiring) that are easily damaged by external stress from being disconnected.
Further, since the end portions of the optical transmission lines 52a and 52b, the optical coupling portions 53a and 53b, and the optical semiconductor elements 51a and 51b are covered with the clad resin layer 59, they can be protected from external stress. The mechanical strength of the entire optical coupling structure can be increased.

6 is an optical transmission module in which both of the optical semiconductor elements 51a and 51b are light emitting elements, and light in which both of the optical semiconductor elements 51a and 51b are light receiving elements. It is also possible to configure a receiving module.
The clad resin layer 59 can cover only the periphery of some of the optical coupling portions 53a and 53b.

  The number of optical semiconductor elements mounted on the optical module is not limited to one or two, but may be three or more. The required number of optical coupling structures between the optical semiconductor element and the optical transmission line can be provided according to the number of optical semiconductor elements.

  Hereinafter, the present invention will be specifically described with reference to examples.

Example 1
As shown in FIGS. 1 to 3, a silica-based multimode optical fiber having a cladding diameter of 125 μm and a core diameter of 50 μm is prepared as the optical transmission line 2, and the optical semiconductor element 1 has a PD (light receiving portion has an opening diameter of 80 μm). UV transparent resin (acrylic resin) is used for the transparent resin 31, a glass epoxy substrate is used for the substrate 4, a gold wire is used for the wire wiring 7, and 2 nl (nanoliter) of the transparent resin 31 is formed on the light receiving portion of the PD. 1) After coating, the tip of the optical fiber is inserted into this transparent resin, pulled up by 40 μm obliquely upward by 30 °, and then irradiated with UV to cure the transparent resin 31, thereby forming the optical coupling structure 5 shown in FIG. Produced. The refractive index of the cured resin constituting the optical coupling unit 3 is 1.58.

As transparent resins, 11 types of resins having different viscosities (A: 0.02 Pa · s, B: 0.1 Pa · s, C: 0.7 Pa · s, D: 1.5 Pa · s, E: 3.2 Pa · s) S: F: 5.5 Pa · s, G: 15 Pa · s, H: 21 Pa · s, I: 26 Pa · s, J: 35 Pa · s, K: 50 Pa · s), immediately after forming the optical coupling portion The shape of the optical coupling part was observed.
The results are shown in Table 1.

  In addition, optical modules in which the positional relationship between the optical transmission line and the optical semiconductor element was optimized were prepared using the resins of samples D, H, and K, and the connection loss in each was measured. The results are shown in Table 2.

  From the results in Table 2, when the optical coupling portion has a concave shape, the connection loss is very small compared to the convex shape.

θ: angle formed by optical axes, P: intersection of optical axes, 1, 51a, 51b: optical semiconductor element, 1a: light emitting / receiving section, 1b: optical axis of optical semiconductor element, 1c: upper surface (front surface), 1d ... lower surface (back surface), 2, 52a, 52b ... optical transmission path, 2a ... end of optical transmission path (end face), 2b ... optical axis of optical transmission path, 3, 53a, 53b ... optical coupling section, 3a ... light Outer surface (interface) of coupling portion, 4, 54... Substrate, 4a, 54a... Mounting surface of substrate, 5, 5A... Optical module, 7, 57a, 57b. Layer, 9 ... optical module, 11, 12, 13 ... concave portion, 50 ... optical transceiver module.

Claims (7)

An optical semiconductor element having a light emitting and receiving part on the upper surface and mounted on the substrate on the lower surface side;
An optical fiber having an optical axis intersecting at a predetermined angle with respect to the optical axis of the optical semiconductor element, and disposed away from the mounting surface of the substrate;
An optical coupling part that optically couples between the optical semiconductor element and the optical fiber ;
The optical coupling part is made of a resin that is transparent to transmitted light, and the resin is in close contact with at least a part of the light receiving and emitting part of the optical semiconductor element and at least a part of the end of the optical fiber. ,
The outer surface of the resin constituting the optical coupling portion has a shape that is recessed toward the light emitting / receiving portion of the optical semiconductor element and the end portion of the optical fiber ,
In the optical coupling portion, the resin does not exist at the intersection point where the optical axis of the optical semiconductor element and the optical axis of the optical fiber intersect,
The position where the outer surface of the resin faces the light emitting / receiving portion is between the intersection and the light emitting / receiving portion, and the position where the outer surface of the resin faces the end of the optical fiber is the intersection. An optical coupling structure between the optical fiber and an end of the optical fiber . 2. The optical coupling structure according to claim 1 , wherein the resin constituting the optical coupling portion is within a range located above an upper surface of the optical semiconductor element. 3. The optical coupling structure according to claim 1, wherein the resin constituting the optical coupling portion is within a range below a height of an upper end of an end face of the optical fiber . Optical coupling structure according to any one of claims 1 to 3, characterized in that the periphery of the optical coupling portion is covered with a gas. Optical coupling structure according to any one of claims 1 to 3, characterized in that refractive index than the resin surrounding constituting the optical coupling portion of the optical coupling portion is covered with a lower cladding resin layer. 6. The optical coupling structure according to claim 5 , wherein a power supply wiring of the optical semiconductor element is covered with the clad resin layer. A light receiving element and a light emitting element mounted on the mounting surface of the same substrate, a first optical fiber and a second optical fiber arranged apart from the mounting surface of the substrate, the light receiving element and the first A first optical coupling unit that optically couples with an optical fiber; and a second optical coupling unit that optically couples between the light emitting element and the second optical fiber, and the light receiving element. The first optical fiber and the first optical coupling portion constitute a first optical coupling structure, and the light emitting element, the second optical fiber, and the second optical coupling portion constitute a second optical coupling structure. An optical transceiver module,
Optical transceiver module one or both of the first optical coupling structure and a second optical coupling structure, characterized in that it constitutes the optical coupling structure according to any one of claims 1-6.

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