JP4115894B2 - Compound optical device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a composite optical device used for optical interconnection and the like.In placeRelated.
[0002]
[Prior art]
Surface-emitting lasers and photodiodes are increasingly useful as key devices for parallel optical interconnection. In its practical use, mounting for controlling light is required, and higher mounting accuracy is required compared to conventional electrical component mounting. In particular, a connector portion that joins an optical fiber, a waveguide, and the like to a light emitting element or a light receiving element has a large optical loss unless it is mounted with high accuracy, and thus various studies have been made. In addition, since the core diameter of a single mode optical fiber or the like is as small as several μm, a method of condensing light emitted from a light emitting element with a lens or the like and performing optical coupling is employed.
[0003]
2. Description of the Related Art In recent years, a method has been put to practical use in which an optical element is mounted on a reference surface by using a member processed with extremely high precision by using a semiconductor process or the like. This member processed with high precision is called MOB (Micro-Optical Bench), which is a very important technique for satisfying various requirements as a MOB mounting method. However, such a mounting method still has a major problem in terms of manufacturing cost.
[0004]
In addition, a method of directly attaching an optical element such as a microlens to a surface emitting laser without using an MOB has been studied (for example, Patent Document 1 (FIG. 20), Patent Document 2 (FIG. 21), Patent) Reference 3 (FIG. 22)).
[0005]
That is, in the mounting method of Patent Document 1 (FIG. 20), the microlens is attached to the upper portion of the surface emitting laser by the ink jet method, and the mounting accuracy is low. In addition, since the lens shape is an ink-jet reflow method, it has a spherical shape with a low degree of freedom. Although there is a method of forming an aspherical surface by controlling the selection ratio at the time of etching after resist formation by the reflow method, it is difficult to control with high accuracy, and it is difficult to have a lens with accuracy.
[0006]
Further, in Patent Document 2 (FIG. 21), a refractive index distribution lens is formed at the emitting portion of the surface emitting laser. However, with this refractive index distribution lens, refraction at a steep angle with a large NA is difficult. In addition, while the refractive index of a normal lens changes discretely at the interface, the refractive index of a gradient index lens does not change uniquely because the refractive index changes continuously. As a result, problems such as crosstalk occur.
[0007]
Moreover, in patent document 3 (FIG. 22), the shape of the microlens is made with resin in the light emission part of the surface emitting laser. By making a microlens in this way, almost all light can be refracted. However, this method employs a reflow method in which a resin is melted and a shape is formed by its surface tension, so that the shape is limited to a spherical surface. In addition, since the resin is reflowed and used as it is as a lens, a refractive index distribution tends to exist in the lens, and the collimated light with high wavefront aberration and high accuracy cannot be produced.
[0008]
Further, in the lens, it is necessary to add a very expensive part in order to realize the tolerance of the lens including an error of the lens shape. Therefore, there is a need for an element that does not use a lens or the like, exhibits a light condensing function, and relaxes the tolerance of mounting accuracy.
[0009]
As described above, if the error due to mounting is large, the light coupling efficiency is lowered, and the manufacturing method that requires high mounting accuracy and the manufacturing method that sandwiches the microlens increases the cost.
[0010]
[Patent Document 1]
JP 2001-185752 A
[0011]
[Patent Document 2]
JP-A-9-532428
[0012]
[Patent Document 3]
Japanese Patent Laid-Open No. 9-072759
[0013]
[Problems to be solved by the invention]
  The present invention provides a composite optical device capable of realizing a high coupling efficiency at a low manufacturing cost.PlaceIt is intended to provide.
[0014]
[Means for Solving the Problems]
  In order to achieve the above object, the first aspect of the present invention provides a first light emitting device.elementAnd the firstelementThe second incident light fromelementAnd the firstelementAnd secondelementAnd twoelementIn a composite optical device having an optical connector that optically couplesThe second element has a core region, and a surface of the core region of the second element that contacts the optical connector is irradiated with UV light. ₂ The wettability of the resin on the surface of the second element in contact with the optical connector where the film is formed is larger in the core region than in other regions,The optical connector isA liquid resin is cured after arranging the first element and the second element,FirstelementAnd secondelementDirectly in contact with the firstelementThe area in contact with the second iselementLarger than the area in contact withHas becomeIt is characterized by that.
[0019]
  Also,Claim 2The described invention is claimed.1In the composite optical device described above, the firstelementIs a light emitting element, and the secondelementIs characterized by being an optical fiber or a waveguide.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0024]
(First embodiment)
The mounting accuracy is several hundred μm for a normal electric component, and if the accuracy is further improved, the manufacturing cost for mounting increases accordingly. There is a need for a method that can achieve high coupling efficiency even with low mounting accuracy. When an error due to mounting occurs, an optical connector having a waveguide function that can correct the error is required. This function is provided by the microlens, but if the microlens is used, it becomes a factor that increases the cost.
[0025]
In order to solve such a problem, the first embodiment of the present invention includes a first optical element that emits light, a second optical element that receives light from the first optical element, and the first optical element. In a composite optical device having an optical connector that optically couples two optical elements, an optical element and a second optical element, the optical connector is in direct contact with the first optical element and the second optical element, The area in contact with the first optical element is larger than the area in contact with the second optical element.
[0026]
In such a configuration, the light emitted from the first optical element is efficiently guided to the second optical element by the function of the waveguide of the optical connector. At this time, the coupling efficiency is increased by making the contact area of the optical connector with the second optical element equal to a region (such as a core region of an optical fiber) in which light of the second optical element propagates. The contact surface between the first optical element and the optical connector is not limited to the light emission region as shown in FIG. The contact surface between the first optical element and the optical connector includes the light emission region of the first optical element and has a contact area around it. With such a shape, for example, as shown in FIG. 1, the second optical element (optical fiber in the example of FIG. 1) is placed in front of the first optical element (surface emitting laser in the example of FIG. 1). It does not need to be placed accurately. This is a tolerance in mounting, and this allowable amount reduces the mounting manufacturing cost. This is because, for example, as shown in FIG. 1, light is guided to an arbitrary position by the waveguide function of the optical connector.
[0027]
(Second Embodiment)
The second embodiment of the present invention is characterized in that the optical connector of the first embodiment is obtained by curing a liquid resin after arranging the first optical element and the second optical element. It is said.
[0028]
Only when the first optical element and the second optical element are arranged, the respective arrangement errors are determined (the magnitude and direction of the error due to the mounting differ depending on the mounted individual), A corresponding optical connector shape (waveguide shape) is required. Thus, if the shape of the optical connector connecting the first and second optical elements after the first and second optical elements are determined, the optical connector shape corresponding to each arrangement error can be selected.
[0029]
(Third embodiment)
The light emitted from the first optical element needs to be efficiently guided to the second optical element. For this purpose, a conical optical connector is desired around a region (core region) where light from the second optical element needs to be guided. Here, the defined core region is used in substantially the same meaning as a core referred to in an optical fiber or the like. In other words, the second optical element also has a clad and a core like an optical fiber, and light is confined in the core. When the second optical element is a light receiving element such as a photodiode, the core indicates the light receiving part and is distinguished from other areas. It is desirable that the second optical element is in contact with the optical connector only in the core region. In this form, the light emitted from the first optical element is transmitted to the second optical element with high efficiency.
[0030]
Therefore, according to the third embodiment of the present invention, in the composite optical device according to the second embodiment, the second optical element has a core region, and the optical connector of the second optical element The wettability of the resin on the contact surface is characterized in that the core region is larger than the other regions. Thereby, a region (core region) where light needs to be guided is selectively wetted with the resin, and the resin has a contact surface only with the core region as compared with other regions. Moreover, the optical connector produced by curing this has a shape having a contact surface only in the core region. The second optical element is a direction where light enters, and it is desirable that the core region and the region where the resin is wetted coincide with each other as much as possible. Thereby, the configuration of the first embodiment can be realized, and an optical connector with high coupling efficiency can be realized.
[0031]
(Fourth embodiment)
According to a fourth embodiment of the present invention, in the composite optical device according to the third embodiment, a surface of the second optical element that comes into contact with the optical connector is formed of TiO 2.₂It is characterized in that a film is formed. TiO₂Can improve the wettability of only the portion irradiated with light. This time, the part where we want to selectively improve wettability is limited to the core region through which light can pass, and it is easy to selectively irradiate only the core region, and this is self This is possible with alignment. Thereby, it becomes possible to improve the wettability accurately only in the core region.
[0032]
(Fifth embodiment)
According to a fifth embodiment of the present invention, in the composite optical device according to the second embodiment, the second optical element has a core region on a surface that contacts the optical connector of the second optical element. The core region is characterized by a convex shape. Thereby, when the 2nd optical element is made to approach the 1st optical element, possibility that a core area will touch resin can be raised. That is, the resin can selectively contact only the core region, and the second optical element is pulled away from the state, whereby the configuration of the first embodiment can be realized.
[0033]
(Sixth embodiment)
According to a sixth embodiment of the present invention, in the composite optical device according to any one of the first to fifth embodiments, the first optical element is a light emitting element, and the second optical element is an optical fiber or a waveguide. It is characterized by that.
[0034]
(Seventh embodiment)
According to a seventh embodiment of the present invention, in the composite optical device according to any one of the first to fifth embodiments, the first optical element is an optical fiber or a waveguide, and the second optical element is a photodiode or the like. It is a light receiving element.
[0035]
A surface-emitting laser, an edge-emitting laser, or a photodiode is an essential element for optical interconnection. In the sixth and seventh embodiments, efficient light between these elements and a waveguide or an optical fiber is used. Bonding can be realized.
[0036]
(Eighth embodiment)
The eighth embodiment of the present invention includes a step of applying a liquid resin on the first optical element;
Contacting the second optical element with the resin;
Pulling up the second optical element to keep the distance between the first optical element and the second optical element constant;
Curing the resin;
It is a manufacturing method of the composite optical apparatus characterized by having.
[0037]
Here, the resin deforms its shape with its viscosity in a state where it contacts and adheres to the second optical element. The deformation is caused by the viscosity of the resin, and an arbitrary shape can be controlled by controlling the viscosity, the distance to be pulled up, the amount of the resin, the contact area with the first and second optical elements, and the like. By adopting such a method, the configuration of the second embodiment can be realized.
[0038]
(Ninth embodiment)
According to a ninth embodiment of the present invention, in the method of manufacturing the composite optical device according to the eighth embodiment, when the second optical element is manufactured, the resin is cured using light propagating through the core. It is a feature.
[0039]
In the second optical element, the core region is a region through which light can pass from the opposite end face. That is, it is possible to emit light accurately only from the core region. By curing the resin using light accurately emitted from the core region, the cured resin can be formed in the core region by self-alignment. The resin thus formed becomes a protrusion formed only in the core region. This becomes the convex of the core region as shown in the fifth embodiment, and has the function shown in the fifth embodiment.
[0040]
【Example】
Next, examples of the present invention will be described.
[0041]
Example 1
FIG. 1 is a diagram illustrating a composite optical device according to a first embodiment. Referring to FIG. 1, the composite optical device according to the first embodiment includes a surface emitting laser, a single mode optical fiber, and an optical connector that optically connects the surface emitting laser and the single mode optical fiber.
[0042]
Here, the surface emitting laser has a light emitting region having a diameter of several tens of μm on the surface thereof. Further, the optical fiber and the surface emitting laser are arranged with a distance of several hundred μm. The optical connector is formed of a transparent resin, and a photo-curing resin is used. The optical connector has a diameter of about 100 μm on the surface emitting laser side and a diameter of about 10 μm on the optical fiber side. An optical fiber having a core diameter of about 10 μm is used. The surface of the optical fiber is TiO₂The resin wettability is increased only in the core region by irradiating light from the opposite end face of the optical fiber. In addition, a black fixed resin having a low refractive index is sealed around the optical connector. The optical fiber and the surface emitting laser are fixed by the fixing resin. Further, this resin can prevent light from adjacent surface emitting lasers from entering as shown in FIG. Thereby, even if the distance to the adjacent fiber is small, the crosstalk can be greatly reduced.
[0043]
3 to 7 are views for explaining a method of manufacturing the composite optical device according to the first embodiment. As shown in FIG. 3, the surface emitting laser is arranged on the PCB in a bare chip shape. A resin having a diameter of about 100 μm is dropped onto the surface emitting laser substrate fixed on the PCB. The resin has a high viscosity and is held in a hemispherical state on the surface emitting laser surface as shown in FIG. The position accuracy of the dropped resin may be several tens of μm, and the center of the dropped droplet is the emission center of the surface emitting laser including the error.
[0044]
The end face of the optical fiber has TiO₂Is applied. Here, a simple method such as spray coating is selected as the coating method, and the film thickness is about several μm. UV light is irradiated from the end surface opposite to the optical fiber surface. TiO₂Has a property of improving its wettability over light irradiation, and as a result of this light irradiation, as shown in FIG. 4, the core region has high wettability to the resin, and the regions other than the core region have low wettability. It becomes a state.
[0045]
The optical fiber is brought close to the surface of the surface emitting laser, and the resin and the optical fiber are brought into contact as shown in FIG. The resin contacts almost the entire end face of the optical fiber. Thereafter, the optical fiber is pulled upward by about 100 μm. At this time, the resin is wet only in the core region of the optical fiber. By pulling up in this state, as shown in FIG. 6, the resin is deformed so as to selectively adhere to the core region. That is, the resin has a conical shape centered on the core region of the optical fiber. The resin is cured by holding in this state and irradiating with UV light (lamp light).
[0046]
While maintaining this state, a fixing resin having a low refractive index is injected. The resin covers the entire surface emitting laser substrate, has a thickness of about several millimeters, and includes a part of the optical fiber. As a result, the distance between the surface emitting laser and the optical fiber is fixed. The resin is black and absorbs light when it is incident. The resin is thermosetting and is cured after injection (see FIG. 7).
[0047]
(Example 2)
As in the first embodiment, the composite optical device of the second embodiment also includes a surface emitting laser, a single mode optical fiber, and an optical connector that optically connects the surface emitting laser and the single mode optical fiber, as shown in FIG. It has become.
[0048]
Here, the surface emitting laser has a light emitting region having a diameter of several tens of μm on the surface thereof. Further, the optical fiber and the surface emitting laser are arranged with a distance of several hundred μm. The optical connector is formed of a transparent resin, and a photo-curing resin is used. The optical connector has a diameter of about 100 μm on the surface emitting laser side and a diameter of about 10 μm on the optical fiber side. An optical fiber having a core diameter of about 10 μm is used. Further, an optical fiber that protrudes only in the core region is used. This protrusion of the optical fiber is made of the same resin as the optical connector. For this reason, in appearance, the optical connector and the protrusion of the optical fiber are integrated. The presence of this protrusion selectively causes light to enter the optical fiber. In addition, a black fixed resin having a low refractive index is sealed around the optical connector. The optical fiber and the surface emitting laser are fixed by the fixing resin. Further, this resin can prevent light from adjacent surface emitting lasers from entering as shown in FIG. Thereby, even if the distance to the adjacent fiber is small, the crosstalk can be greatly reduced.
[0049]
8 to 13 are views for explaining a method of manufacturing the composite optical device according to the second embodiment. As shown in FIG. 8, the surface emitting laser is arranged on the PCB in a bare chip shape. A resin having a diameter of about 100 μm is dropped onto the surface emitting laser substrate fixed on the PCB. The resin has a high viscosity and is held in a hemispherical state on the surface emitting laser surface as shown in FIG. The position accuracy of the dropped resin may be several tens of μm, and the center of the dropped droplet is the emission center of the surface emitting laser including the error.
[0050]
Moreover, as shown in FIG. 9, a protrusion is created only in the tip core region of the optical fiber. That is, UV light is incident on the optical fiber from one end face by the UV lamp. Thereby, UV light is radiate | emitted from the other end surface of an optical fiber. The resin is cured using the emitted light. The resin to be cured is only the region that is exposed to light, and this resin to be cured is selectively formed as a protrusion at the tip of the core region as shown in FIG. The resin used at this time is the same as that dropped onto the surface emitting laser in FIG. 8 and has the same refractive index. This method is described in detail in the document “Proc. SPIE, vol 4106, pp 11-20, 2000”.
[0051]
Next, as shown in FIG. 11, the optical fiber of FIG. 10 is brought close to the surface of the surface emitting laser of FIG. 8, and the resin on the surface of the surface emitting laser is brought into contact with the projection of the optical fiber. At this time, the resin contacts only the projection of the optical fiber and does not contact other portions.
[0052]
Thereafter, as shown in FIG. 12, the optical fiber is pulled upward by about 100 μm. By pulling up in this state, the resin is deformed so as to selectively adhere to the core region. That is, the resin has a conical shape centered on the core region of the optical fiber. The resin is cured by holding in this state and irradiating with UV light.
[0053]
While maintaining this state, a fixing resin having a low refractive index is injected. The resin covers the entire surface emitting laser substrate, has a thickness of about several millimeters, and includes a part of the optical fiber. As a result, the distance between the surface emitting laser and the optical fiber is fixed. The resin is black and absorbs light when it is incident. The resin is thermosetting and is cured after injection (see FIG. 13).
[0054]
(Example 3)
FIG. 14 is a diagram illustrating a composite optical device according to the third embodiment. Referring to FIG. 14, the composite optical device of Example 3 includes a photodiode, a single mode optical fiber, and an optical connector that optically connects the photodiode and the single mode optical fiber.
[0055]
Here, the photodiode has a light receiving region with a diameter of several tens of μm on the surface thereof. The optical fiber and the photodiode are arranged with a distance of several hundred μm. The optical connector is formed of a transparent resin, and a photo-curing resin is used. The optical connector has a diameter of about 10 μm on the photodiode side and a diameter of about 100 μm on the optical fiber side. An optical fiber having a core diameter of about 10 μm is used. The size of the contact surface between the resin of the optical connector and the photodiode is almost the same as the size of the light receiving surface of the photodiode. As a result, almost 100% of light from the optical fiber is received by the photodiode. In addition, a black fixed resin having a low refractive index is sealed around the optical connector. The optical fiber and the photodiode are fixed by the fixing resin. Further, this resin can prevent light from entering adjacent photodiodes.
[0056]
15 to 19 are views for explaining a method of manufacturing the composite optical device according to the third embodiment. First, as shown in FIG. 15, an optical fiber is dipped in a resin and pulled up to form a substantially spherical resin on the end face of the optical fiber. At this point, the resin is liquid and not cured.
[0057]
Further, as shown in FIG. 16, the photodiode is disposed on the PCB in a bare chip shape. This photodiode chip is made of TiO with only the light receiving surface exposed.₂A film is formed. TiO₂The wettability is enhanced by exposure, and therefore, only the light receiving surface of the photodiode is easily wetted by the resin. In this state, an optical fiber having a resin formed on the end face is pressed. The pressed resin is deformed as shown in FIG. 17 and is pressed against the entire photodiode chip. In this state, as shown in FIG. 18, when the optical fiber is pulled up, the resin does not come into contact with the photodiode except for a portion with high wettability. The resin is kept in contact with only the light receiving portion of the photodiode, and the resin is cured by a UV lamp. Thereafter, as shown in FIG. 19, a black resin for fixing the optical fiber is injected and cured.
[0058]
【The invention's effect】
  As explained above, the claims1According to the invention described, the first that emits lightelementAnd the firstelementThe second incident light fromelementAnd the firstelementAnd secondelementAnd twoelementAnd an optical connector that optically couples the optical connector to the optical connector.elementAnd secondelementDirectly in contact with the firstelementThe area in contact with the second iselementAnd an optical connector having an optical path function in which the area on the exit side is smaller than the area on the entrance side.elementAnd secondelementAnd the mounting accuracy becomes moderate. Thereby, a high coupling efficiency can be realized at a low manufacturing cost.
[0059]
  In particular,Claim 1In the described invention,in frontThe light connector is the firstelementAnd secondelementIt is what hardened the liquid resin after arranging the first and secondelementBy using optical connectors in which the resin is cured after arranging the optical connectors, optical connector shapes corresponding to the respective arrangements can be realized. Accordingly, it is possible to provide a composite optical device that does not reduce the optical coupling efficiency for each arrangement (that is, the tolerance for the arrangement becomes gentle).
[0060]
  Also,Claim 1In the described invention,in frontThe second optical element has a core region,The surface of the core region of the second element that comes into contact with the optical connector is irradiated with TiO irradiated with UV light. ₂ A film is formed,The secondelementThe wettability of the resin on the surface in contact with the optical connector is greater in the core region than in other regionsHas becomeTherefore (that is, by increasing the wettability only in the core region), the resin can be selectively formed only in the core region, and light passes only through that region. As a result, an optical connector with low manufacturing cost and high optical coupling efficiency can be realized, and a composite optical device with reduced manufacturing cost can be provided.
[0062]
  Also,Claim 2In the described invention, the claims1In the composite optical device described above, the firstelementIs a light emitting element, and the secondelementIs an optical fiber or waveguide and the firstelementFor example, by using a surface emitting laser, it is possible to widen the emission surface and the horizontal substrate surface. In this case, a large amount of fixing resin or the like can be injected, and stable fixing can be realized at low cost.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a composite optical device according to a first embodiment.
FIG. 2 is a diagram for explaining the operational effect of the composite optical device according to the first embodiment.
FIG. 3 is a view for explaining the method for manufacturing the composite optical device according to the first embodiment.
4 is a view for explaining a method for manufacturing the composite optical device of Example 1. FIG.
5 is a view for explaining a method of manufacturing the composite optical device of Example 1. FIG.
6 is a view for explaining a method of manufacturing the composite optical device of Example 1. FIG.
7 is a view for explaining a method of manufacturing the composite optical device of Example 1. FIG.
FIG. 8 is a diagram for explaining a method of manufacturing the composite optical device according to the second embodiment.
FIG. 9 is a view for explaining the method for manufacturing the composite optical device according to the second embodiment.
10 is a diagram for explaining a method of manufacturing the composite optical device according to the second embodiment. FIG.
FIG. 11 is a diagram for explaining a method of manufacturing the composite optical device according to the second embodiment.
12 is a diagram for explaining a method of manufacturing the composite optical device according to the second embodiment. FIG.
13 is a diagram for explaining a method of manufacturing the composite optical device according to the second embodiment. FIG.
FIG. 14 is a diagram illustrating a composite optical device according to a third embodiment.
15 is a diagram for explaining a method of manufacturing the composite optical device according to Example 3. FIG.
16 is a diagram for explaining a method of manufacturing the composite optical device according to Example 3. FIG.
FIG. 17 is a view for explaining the method of manufacturing the composite optical device according to the third embodiment.
FIG. 18 is a view for explaining the method for manufacturing the composite optical device according to the third embodiment.
FIG. 19 is a diagram for explaining a method of manufacturing the composite optical device according to the third embodiment.
FIG. 20 is a diagram for explaining a conventional technique.
FIG. 21 is a diagram for explaining a conventional technique.
FIG. 22 is a diagram for explaining a conventional technique.

Claims (2)

A first element that emits light; a second element that receives light from the first element; and an optical connector that optically couples the first element and the second element. In the composite optical device, the second element has a core region, and a surface of the core region of the second element that contacts the optical connector is formed with a TiO ₂ film irradiated with UV light, The wettability of the resin on the surface of the second element in contact with the optical connector is greater in the core region than in other regions, and the optical connector includes the first element and the first element. The liquid resin is cured after the two elements are disposed, and is in direct contact with the first element and the second element, and the area in contact with the first element is larger than the area in contact with the second element A compound optical device characterized in that it is also large.   2. The composite optical device according to claim 1, wherein the first element is a light emitting element, and the second element is an optical fiber or a waveguide.

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