JP2003172837A - Optical waveguide element with lens and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide element in which a coupling efficiency with another optical system is enhanced when light is made incident or emitted by converting the optical path of an optical waveguide and to provide a method of manufacturing the optical wave guide element. <P>SOLUTION: The optical waveguide element and the method of manufacturing the optical waveguide element are characterized by the fact that the optical waveguide element including a first clad layer, a core layer and a second clad layer has a reflection means on the end part, which converts the direction of an optical path from the optical waveguide composed of the core layer to the first clad layer, and a part of the outer surface of the first clad layer has a lens shape is provided on the converted optical path. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer optical waveguide, and more particularly to a method for manufacturing an optical component such as an optical integrated circuit, optical interconnection, or optical multiplexing / demultiplexing.

[0002]

2. Description of the Related Art Inorganic materials such as quartz glass and multi-component glass, which have the characteristics of low light propagation loss and wide transmission band, are widely used as a base material for optical parts or optical fibers. Recently, polymer materials have been developed and are attracting attention as materials for optical waveguides because they are superior in processability and price to inorganic materials. For example, a flat plate type having a core-clad structure in which a polymer having excellent transparency such as polymethylmethacrylate (PMMA) or polystyrene is used as a core, and a polymer having a refractive index lower than that of the core material is used as a clad material. An optical waveguide is manufactured (Japanese Patent Laid-Open No. 3-188402). On the other hand, Matsuura et al. Have realized a low-loss flat-type optical waveguide using polyimide, which is a transparent polymer having high heat resistance (JP-A-2-110500). Surface emitting lasers (VCSELs) are about to be mounted in the field of optical interconnection due to cost requirements, but when laser light emitted perpendicularly to the substrate enters an optical waveguide horizontal to the substrate, A 90 ° optical path change is required. In the polymer optical waveguide, the dicing saw
It is cut to about 45 ° to enable 90 ° optical path conversion (Japanese Patent Laid-Open No. 10-300961). However, since light propagates away from the core in a space, the light spreads and sometimes cannot be successfully connected to the core of the optical waveguide. In order to solve this, attempts have been made to reduce the spot size by forming a microlens on the optical waveguide side by an inkjet method or a dispensing method. However, this method has a problem that the viscosity of the lens material and the contact angle control of the surface of the optical waveguide are very important and the productivity is poor.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical waveguide element having improved coupling efficiency with another optical system when the optical path of the optical waveguide is converted and then enters or exits, and a method of manufacturing the same. To do.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventor has found that a mold for transferring a microlens shape is used.
The present invention has been completed by finding that the above problems can be solved by producing a lens forming clad. That is,
The present invention is an optical waveguide device including a first clad layer, a core layer, and a second clad layer, and has a reflection means for converting an optical path from the optical waveguide including the core layer toward the first clad layer at an end portion. Then, on the converted optical path, a part of the outer surface of the first cladding layer is an optical waveguide element having a lens shape.

Here, it is preferable that a part of the core layer forms a columnar protrusion on the optical waveguide immediately below the lens shape in order to easily form the lens shape.

The present invention also provides a first clad layer, a core layer,
In a method of manufacturing an optical waveguide including a laminate of a second clad layer, a molten or solution-state first polymer precursor is applied onto a mold on which columnar protrusions are formed, and the precursor is cured. After that, a step of obtaining a first clad layer made of a polymer by peeling from the mold and having columnar protrusions transferred on the surface in contact with the mold, and the surface of the first clad layer in contact with the mold A step of applying a second polymer precursor in a solution state or a solution state to be a core layer material and then heating and curing, a step of forming a second clad layer so as to sandwich the core layer with the first clad layer, and a columnar shape. And a step of obliquely cutting the laminated body at the position of the protrusion to obtain a reflection end surface.

At this time, a polymer in a molten or solution state is applied onto a mold having a lens shape, the polymer is cured by ultraviolet rays or heat, and then immersed in a liquid. It is preferable to include a step of peeling the mold. Further, on the substrate on which the lens shape is formed, a mold having a sacrificial layer for separating the polymer and the substrate is formed, and a polymer in a molten state or a solution state is applied, and the polymer is irradiated with ultraviolet rays or After curing by heat, it is preferable to include a step of removing the mold by removing the sacrificial layer with a liquid.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
Molds with lens shapes are used for plating, plasma etching, chemical etching, laser on the substrate surface of silicon, glass, aluminum, stainless steel, polyimide, etc., or on the substrate surface coated with polymers. A shape for forming a lens and a shape to be an optical waveguide pattern are processed by a method such as ablation.

Next, an optical waveguide manufacturing method using the lens-shaped polymer optical waveguide manufacturing die thus obtained will be described. Here, the production of a polyimide optical waveguide using a polyamic acid solution that is a precursor of polyimide will be described as an example, but it is produced using a resin solution of an optical material other than the polyamic acid solution as the material of the optical waveguide. Of course, it is also possible. FIG. 1 shows an example of a mold for a polymer optical waveguide with a lens shape. A ridge portion 1 corresponding to the optical waveguide and a columnar protrusion 2 for forming a lens are formed on a part of the ridge portion. here,
The columnar protrusions that give the lens shape are a cylinder, a rectangular parallelepiped, a trapezoid,
It may be designed according to the lens shape to be formed such as a cone or a hemisphere. The shape is preferably hemispherical. The shape of the formed lens is not a shape of the columnar protrusion as it is reflected on the shape of the outer surface, but a sagging shape when the precursor of the polymer material for the clad layer is applied on the mold. It can be obtained by using that. FIG. 2 is a cross-sectional view showing an example of steps for producing an optical waveguide using this mold. The mold 11 is the mold of FIG. 1 seen from the front side of the paper,
A cylindrical columnar protrusion 2 is formed on the ridge portion 1.

A first polyamic acid solution is applied onto the mold 11 by a method such as spin coating, and this is imidized by heating to form a first cladding layer 12 of polyimide on the mold. At this time, on the outer surface of the upper part of the columnar protrusion of the mold of the first clad layer, a curved surface in which the shape of the columnar protrusion is deviated is formed and becomes the lens portion 15 (FIG. 2).
(b)). Next, the lower clad layer is peeled from the mold by immersing the mold with the lower clad layer attached thereto in an aqueous solution. Next, with the surface that had been in contact with the mold facing up, a second polyamic acid solution that is a polyimide precursor that will become the core layer 13 is applied onto this by spin coating or another method, and this is heated imide. To form a polyimide core layer 13 on the first cladding layer 12 (see FIG. 2).
(c)). Next, if necessary, the excess core layer formed on the lower cladding layer is removed by a method such as reactive ion etching. Finally, a first polyamic acid solution which is a precursor of polyimide to be the second clad layer 14 is applied by a method such as spin coating, and this is imidized by heating (FIG. 2 (d)).

Next, as shown in FIG. 3, the reflection end face 16 was obtained by cutting the obtained optical waveguide at a lens portion at 45 °.
In this way, an embedded polymer optical waveguide in which the lens portion 15 is formed can be manufactured. A columnar protrusion for forming a lens shape is present as a part of the core layer above the optical waveguide composed of the core layer at the reflection end face portion. Moreover, an extra step is not required for forming the lens.

Subsequently, the present invention will be described in more detail with reference to some examples. It is clear that the polymer optical waveguides of the present invention are innumerable by using solutions of various polymers having different molecular structures. Therefore, the invention is not limited to only these examples.

(Example 1) First, the surface of a glass substrate was etched at a position where a lens was required to form a cylindrical convex shape having a radius of 50 μm and a height of 20 μm using a CF etching gas. After that, the line width is 50μm so that it fits with the lens.
The linear optical waveguide pattern having a length of 10 cm was etched by 20 μm using a CF etching gas so that 40 linear optical waveguide patterns were formed in a convex shape at intervals of 100 μm. This surface unevenness is S
Observed by EM, a cylindrical shape having a radius of 50 μm and a height of 20 μm and a ridge having a width of 50 μm and a height of 20 μm were formed in the lower part thereof, and a mold having a desired shape could be manufactured.

Next, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FD
A) and 2,2-bis (trifluoromethyl) -4,4 '
1-polyamino acid of diaminobiphenyl (TFDB)
After heating the 5 wt% DMAc solution on the mold, the film thickness is 30 μm.
m was spin coated. After heat imidization, 80
The polyimide film was peeled from the mold by immersing it in warm water at 0 ° C. for 20 minutes.

Next, with the surface that had been in contact with the mold facing up, the core layer of 6FDA and 4,4'-oxydianiline (ODA) polyamic acid of about 15 wt% DM
An Ac solution was applied by a method such as spin coating, and this was imidized by heating to form a polyimide core layer on the lower clad layer. Next, the excess core layer formed on the lower cladding layer was removed by reactive ion etching. Finally, 6FDA and TFD which will be the upper clad layer
A 15 wt% DMAc solution of the polyamic acid of B is applied by a method such as spin coating, and this is imidized by heating.
In this way, the embedded optical waveguide is formed. At this time, a lens having a diameter of 200 μm and a height of 50 μm was formed on the lower clad. The end faces were cut at 45 ° with a dicing saw, and the coupling efficiencies with the surface emitting laser and the photodetector mounted at desired positions were measured to be about 80% and about 90%, respectively.

(Comparative Example 1) A convex shape for forming a lens was not formed on the surface of a glass substrate, and 40 linear optical waveguide patterns having a line width of 50 μm and a length of 10 cm were formed at intervals of 100 μm to form a convex shape. 20μ using C-F type etching gas
m etched. Observing the surface irregularities by SEM, a cylindrical shape with a radius of 50 μm and a height of 20 μm and a width of 50
A ridge having a size of μm and a height of 20 μm was formed, and a mold having a desired shape could be manufactured. Next, a 15 wt% DMAc solution of polyamic acid of 6FDA and TFDB was spin-coated on the mold so that the film thickness after heating was 30 μm. After the heat imidization, the polyimide film was peeled from the mold by immersing it in warm water of 80 ° C. for 20 minutes.

Next, with the surface that had been in contact with the mold facing up, a 15% by weight DMAc solution of 6FDA and ODA, which is a polyamic acid, serving as a core layer was applied onto this surface by a method such as spin coating. By heating and imidizing, a polyimide core layer was formed on the lower clad layer. Next, the excess core layer formed on the lower cladding layer was removed by reactive ion etching. Finally, 15 wt% D of polyamic acid of 6FDA and TFDB to form the upper clad layer.
A MAc solution is applied by a method such as spin coating, and this is imidized by heating. In this way, the embedded optical waveguide is formed. The end face was cut at 45 ° with a dicing saw, and the coupling efficiency with the surface emitting laser and the photodetector mounted at desired positions was measured to be about 5 each.
It was 0% and about 70%.

Example 2 Pyromellitic dianhydride (PMDA) and ODA polyamic acid N, N-dimethylacetamide (DMAc) 1 on a 4-inch silicon substrate.
A 5 wt% solution was applied by spin coating to a film thickness of 70 μm after heating. It was imidized by heating to form a polyimide film. A silicon-containing resist film having a film thickness of 1.5 μm was coated thereon and prebaked at 90 ° C. Next, exposure and development were performed using a photomask in which a circular shape having a diameter of 50 μm to be a lens shape was drawn at a desired position, and the resist in the exposed portion was removed. Using the patterned resist layer as a mask, the polyimide film was etched by reactive ion etching to a depth of 20 μm from the film surface. Next, the resist layer remaining on the upper polyimide layer was removed with a stripping solution. Next, a resist is coated in the same manner to form a linear optical waveguide pattern having a line width of 50 μm and a length of 7 cm.
The resist in the exposed area was removed by exposing and developing using a photomask having 0 lines and drawn at intervals of 250 μm. Using the patterned resist layer as a mask, the polyimide film was etched by reactive ion etching to a depth of 20 μm from the film surface. Next, the resist layer remaining on the upper polyimide layer was removed with a stripping solution. Observation of the surface irregularities with a scanning electron microscope revealed a width of 50 μm and a height of 20 μm.
It was found that a cylindrical projection having a diameter of 50 μm and a height of 20 μm was formed on the upper part of the ridge, and it was found that a mold having a desired shape was formed.

Next, as a sacrifice layer, a silicon oxide film having a thickness of 20 nm was formed on the mold by vacuum deposition. next,
From above, 15 of polyamic acid of 6FDA and TFDB
After heating the wt% DMAc solution on the mold, the film thickness is 30 μmm
It was spin coated so that After the heat imidization, the mold was immersed in a 5 wt% hydrofluoric acid aqueous solution for 10 minutes, and the polyimide film to be the lower clad layer was peeled from the mold. At this time, a curved lens shape was obtained on the outer surface of the polyimide film having a cylindrical shape with a mold.

Next, with the surface that had been in contact with the mold facing up, the core layer of 6FDA and 4,4'-oxydianiline (ODA) polyamic acid about 15 wt% DM
An Ac solution was applied by a method such as spin coating, and this was imidized by heating to form a polyimide core layer on the lower clad layer. Next, the excess core layer formed on the lower cladding layer was removed by reactive ion etching. Finally, 6FDA and TFD which will be the upper clad layer
A 15 wt% DMAc solution of the polyamic acid of B is applied by a method such as spin coating, and this is imidized by heating.
In this way, the embedded optical waveguide is formed. Then, a convex lens having a diameter of 200 μm and a thickness of 50 μm was formed on the lower clad.

The end face was formed by cutting the portion where the lens was formed at 45 ° with a dicing saw. Using the optical waveguide device thus obtained, the coupling efficiency with the surface emitting laser and the photodetector installed at the condensing position of the lens was measured and found to be about 80% and about 90%, respectively. Although this optical waveguide element is obtained in the form of a polyimide sheet,
When forming a film in the middle of production or cutting with a dicing saw at 45 °, it was adhered to a flat plate with wax. Further, this optical waveguide element can be used alone, attached to a rigid substrate, or attached to a circuit-formed substrate.

[0022]

EFFECTS OF THE INVENTION The method for producing a polymer optical waveguide with a lens according to the present invention makes it possible to produce an optical waveguide having good coupling efficiency with a light emitting / receiving element and excellent mass productivity.

[Brief description of drawings]

FIG. 1 is a view showing an example of a mold for producing a polymer optical waveguide with a lens.

FIG. 2 is a process drawing showing an example of a process for producing a polymer optical waveguide with a lens using a mold.

FIG. 3 is a diagram showing an example of a cross-sectional structure of an optical waveguide having optical path changing and condensing functions.

[Explanation of symbols]

1: Ridge part, 2: Columnar protrusion, 11: Mold, 12: First clad layer, 13: Core layer, 14: Second clad layer, 1
5: lens part, 16: reflective end face

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 33/00 G02B 6/12 N H01S 5/02 H01L 31/02 C

Claims (3)

[Claims] 1. An optical waveguide device including a first clad layer, a core layer and a second clad layer, wherein a reflection means for converting an optical path from an optical waveguide comprising the core layer to a direction of the first clad layer is provided at an end portion. An optical waveguide element, wherein a part of the outer surface of the first cladding layer has a lens shape on the converted optical path. 2. The optical waveguide element according to claim 1, wherein a part of the core layer directly below the lens shape forms a columnar protrusion on the optical waveguide. 3. A method of manufacturing an optical waveguide comprising a laminated body of a first clad layer, a core layer and a second clad layer, wherein a first mold in a molten state or a solution state is formed on a mold on which columnar protrusions are formed. A step of applying a polymer precursor, curing the precursor, and then peeling from the mold to obtain a first clad layer made of a polymer and having columnar protrusions transferred to the surface in contact with the mold. A step of applying a solution state or a solution-state second polymer precursor to be a core layer material on the surface of the first clad layer that was in contact with the mold and then heating and curing, and sandwiching the core layer with the first clad layer So as to form the second cladding layer,
A step of obliquely cutting the laminated body at the position of the columnar protrusion to obtain a reflection end face.