JP2000221347A - Mirror structure and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a mirror plane in a desired place and in a desired direction on a waveguide substrate with high accuracy by forming a groove filled with a polymer material in a part of the waveguide in such a manner that at least one plane in the polymer material in the groove is formed as a reflection plane at a specified angle to the substrate. SOLUTION: A groove 10 is formed by, for example, a dry etching method in the region where the mirror structure is to be formed. Then a polymer material as an org. material such as a UV-curing material is poured into the groove 10. The groove 10 filled with the polymer material is exposed to light by using an exposing means 1 in the incident direction according to the angle of the mirror plane 106. By using the exposing means 1 to expose the photosensitive material 105 to the light through a varied optical path in the oblique direction to form the mirror plane, the mirror structure to convert the optical path can be produced at any position in a desired direction in the waveguide substrate 101 with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mirror structure having a mirror surface for converting an optical path in an optical waveguide, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, there is a mirror structure that converts an optical path perpendicular to a waveguide surface or at a certain angle. This mirror structure is an indispensable structure when a light emitting element or a light receiving element is integrated into a waveguide.

As a conventional method of manufacturing a mirror structure, a dicing method or a reactive ion etching method is generally used.

In the dicing method, a waveguide is cut using teeth having a wedge angle of 90 degrees, and a total reflection mirror having a 45-degree inclination is formed in the middle of the waveguide to produce a mirror structure.

In the reactive ion etching method, a mirror structure is manufactured by performing reactive ion etching on a waveguide surface obliquely.

Here, a method of manufacturing a mirror structure by a conventional reactive ion etching method will be described with reference to FIGS.
Description will be made based on (b).

[0007] As shown in FIG.
A lower clad layer 202, a core layer 203, and an upper clad layer 204 are sequentially laminated on the waveguide 01, and the upper portion of such a waveguide is covered with a mask 205. And mask 2
The ion stream is irradiated from an oblique direction 05.

By the irradiation of the ion current, only the portion irradiated with the ion current is etched as shown in FIG. 5B, whereby a total reflection mirror 206 as a mirror structure is manufactured.

[0009]

However, the conventional method has the following problems.

In the dicing method, there is a problem that the mirror structure is formed on a straight line and is cut when there is another waveguide on the straight line. Further, the positioning accuracy is not so high as about ± 2 microns.

In the reactive etching method, since the mirror structure is formed in the direction in which the substrate is inclined, it is not possible to manufacture mirror structures in different directions at the same time. Moreover, there is a problem that it is generally difficult to obtain a clean etching end face and a flat etching end face.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a mirror structure and a method of manufacturing the same, which enable a mirror surface to be manufactured at an arbitrary position and an arbitrary direction on a waveguide substrate with high accuracy. It is in.

[0013]

According to the present invention, there is provided a structure having a reflection surface in a waveguide on a substrate, the waveguide having a groove in which a polymer material is embedded in a part of the waveguide. A mirror structure is formed by setting at least one surface of the polymer material embedded in the substrate as a reflection surface having a predetermined angle with respect to the substrate.

Further, the present invention is a method for manufacturing a mirror structure having a reflection surface in a waveguide on a substrate, wherein a groove for etching a desired reflection surface in the waveguide is formed by etching. Providing, a step of pouring a photosensitive material into a region of the groove, a step of performing exposure to a region including the groove from an incident direction corresponding to an angle of the reflection surface using an exposure unit, and A method of manufacturing a mirror structure by forming a reflection surface in the groove by removing a region other than a desired region from among the regions of the photosensitive material.

Here, the method may further include a step of forming a protective film on the reflection surface.

The groove is formed in a part of the waveguide, and an ultraviolet-curable oligomer is poured into the groove, and ultraviolet light is applied to the oligomer from the optical axis different from the optical axis of the waveguide by using the exposure means. The reflection surface can be formed on at least one surface of the polymer material buried in the groove by irradiating a part of the oligomer to cure the oligomer and removing an unirradiated portion of the oligomer.

The groove can be formed in a part of the waveguide by using a reactive ion etching method.

The exposure means has a prism and a mask. The ultraviolet light having an optical axis perpendicular to the substrate is incident on the prism to change an optical path, and the ultraviolet light having the changed optical path is transmitted to the prism. A part of the oligomer can be irradiated from an optical axis different from the optical axis of the waveguide through a mask.

The prism and the mask can be integrally formed.

Ultraviolet rays are irradiated perpendicularly to the waveguide substrate, the apex angle of the prism is α, the refractive index of the prism is n _p , the refractive index of the oligomer is n _m , and the reflection surface is irradiated with respect to the normal line of the waveguide substrate. When the angle is ε,

[0021]

(Equation 3)

The condition can be set so as to satisfy the following condition.

The exposure means has an optical fiber, a lens, and a mask, guides and emits the ultraviolet light from the optical fiber, and transmits the emitted ultraviolet light to the optical axis different from the optical axis of the waveguide by the lens. And a part of the oligomer is irradiated with the parallel light through the mask.

The exposure means has an optical fiber and a beam profile conversion lens, guides and emits the ultraviolet light from the optical fiber, and makes the emitted ultraviolet light incident on the beam profile conversion lens with uniform intensity. The rectangular beam may be converted into a parallel light beam having an optical axis different from the optical axis of the waveguide, and the parallel light beam may be applied to a part of the oligomer.

When the incident angle φ of light and the irradiation angle of the reflecting surface with respect to the normal of the waveguide substrate are ε,

[0026]

(Equation 4)

The condition can be set so as to satisfy the following condition.

[0028]

Embodiments of the present invention will be described below in detail with reference to the drawings.

[First Example] A first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows a configuration example of a mirror structure.

On the substrate 101, the lower cladding layer 10
2, a core layer 103 and an upper cladding layer 104 are sequentially laminated to form a waveguide.

This waveguide is provided with a groove 10. In the groove 10, a photo-curing material 105 having an inclined mirror surface 106 on one surface is buried. On the mirror surface 106, a protective film 107 is applied.

Here, specific examples will be given.

In the case of a silica-based waveguide, the substrate 101 is made of a silicon substrate, the lower clad layer 102 and the upper clad layer 104 are made of SiO ₂ , and the core layer 103 is made of Ta ₂ O ₅ / Si 0 _2. Can be.

In the case of a polymer-based waveguide, the lower clad layer 102, the core layer 103, and the upper clad layer 104 are adjusted so that the refractive index of the core layer 103 is increased by about 1 to 5%. They can be made of methacrylate, polyimide or the like.

As the light curing material 105, a photosensitive epoxy resin can be used.

As described above, a mirror structure can be formed by embedding the photocurable material 105 having the mirror surface 106 formed in the groove 10 in the waveguide.

In particular, the mirror structure according to the present invention does not depend on the composition of the waveguide and the distinction between a single mode waveguide, a multimode waveguide, a channel waveguide and a slab waveguide. Can be applied to any type of waveguide.

(Manufacturing Method) Next, a method of manufacturing a mirror structure will be described.

The mirror structure is formed by a groove 1 provided in the waveguide.
0 is filled with the polymer material in the substrate 101 of the waveguide.
Is manufactured by processing so as to have a surface (mirror surface 106) at a predetermined angle with respect to.

First, the manufacturing process will be described briefly.

This step utilizes the direct exposure method as shown in the following steps (A) to (F).

(A) Lower cladding layer 1
02, a core layer 103 and an upper clad layer 104 are fabricated.

(B) In the portion where the mirror structure is to be formed, the groove 1 is etched by, for example, a dry etching method.
0 is formed.

(C) A polymer material as an organic material, for example, a material having ultraviolet curability is poured into the groove 10.

(D) Exposure is performed on the groove 10 filled with the polymer material using the exposure means 1 from an incident direction corresponding to the angle of the mirror surface 106. The exposure means 1 in this step is generally performed through a mask having a prism structure.

(E) A portion which is not cured by irradiation with light is removed using a suitable solvent. With this removal,
One surface of the cured polymer material corresponding to the incident direction is formed as a mirror surface 106.

(F) If necessary, the mirror surface 1
06, a protective film 107 is provided.

Next, details of the manufacturing process will be described with reference to FIG.

In the first step, a substrate 1 such as silicon
First, a waveguide including a lower cladding layer 102, a core layer 103, and an upper cladding layer 104 is manufactured.

In the second step, a groove 10 for filling the photocurable material 105 is formed in a portion of the manufactured waveguide where the mirror structure is to be formed.

In the third step, an ultraviolet curable epoxy oligomer is poured as a polymer material into the groove 10.

In the fourth step, exposure is performed using the exposure means 1. In this case, the exposure unit 1 includes, for example, an exposure light source (not shown), a metal mask 108, and a prism 10
9 can be used.

Such a metal mask 108 and the prism 1
09 on a reticle consisting of ultraviolet light (UV light)
Irradiate 20. The position of the reticle can be set with high precision with respect to a marker provided on the silicon substrate 101 in advance. Then, the traveling direction of the light is changed to an oblique direction by the prism 109, and the light is irradiated to the groove 10 portion where the photocurable material 105 exists. By this exposure, the photocurable material 105
Only the irradiated part is cured.

Here, ultraviolet rays 20 are irradiated perpendicularly to the substrate 101, the vertex angle of the prism 109 is α, the prism 1
09 is n _p , the refractive index of the oligomer is n _m , and the irradiation angle of the mirror surface 106 with respect to the normal of the substrate 101 is ε.

[0056]

(Equation 5)

As shown in FIG. The mirror surface 106 can be manufactured using a prism structure that satisfies the incident angle of the expression (1).

The equation (1) is calculated from the angles β, γ, and δ between the auxiliary lines (broken lines) and the light rays shown in FIG. 2 and the following equations (2) to (5). You. However, the refractive index of air is approximated by one.

[0059]

(Equation 6)

Then, in the fifth step, the photocurable material 1
The remaining unirradiated portion other than the light-irradiated portion of No. 05 is removed by using an appropriate solvent to obtain a desired mirror surface 1.
06 can be produced.

In addition to the above steps, a protective film 107 may be formed on the mirror surface 106 as necessary. As the protective film 107, a SiO ₂ film, a dielectric multilayer film, or a metal film such as Au, Ag, or Al can be used.

As described above, the light that travels in the direction perpendicular to the substrate 101 has its optical path changed by the prism 109, and the light whose path has been changed is applied to the photocurable material 105 from an oblique direction. By using an optimal reticle as an exposure method, a mirror structure having a mirror surface for optical path conversion can be collectively manufactured at an arbitrary position and an arbitrary direction on the substrate 101 with high accuracy.

(Modification) In the above example, an example was described in which an unirradiated portion other than the light-irradiated portion was removed after exposure and development. However, the present invention is not limited to this.

For example, when a photosensitive material whose light-irradiated portion is removed after exposure and development is used as the photo-curing material 105, the procedure after the fabrication of the waveguide is as follows.

As a first step, a photosensitive material such as a resist is poured into the groove. As a second step, the entire substrate is heated and prebaked. As a third step, the photosensitive material protruding from the groove portion to the upper portion is removed by a method such as polishing. As a fourth step, in order to form a mirror structure, a portion to be removed is subjected to the same exposure using the above-described exposure means such as a prism and a mask. As a fifth step, wet etching is performed as etching. That is, the exposed substrate is immersed in a developing solution to dissolve and remove unnecessary portions, and then washed. As the sixth step,
The entire substrate is heated, post-baked, and completely cured. Thus, a mirror structure can be manufactured.

[Second Example] Next, a second embodiment of the present invention will be described with reference to FIG. Note that the first
The description of the same parts as in the above example is omitted, and the same reference numerals are given.

This embodiment is different from the first embodiment in the exposure method. That is, the exposure means 1 includes a light guide 110 made of an optical fiber or the like and a collimating lens 11 for light shaping.
1, a mask 112, and a quartz substrate 113 to which the mask 112 is integrally attached.

When the mirror is manufactured, the light from the ultraviolet light source in the fourth exposure step (D) is
The light guide 110 is guided to the vicinity of the groove 10 using the light guide 110.
Outgoing light from the lens is incident on the collimating lens 111 and is converted into parallel light. Then, the mirror surface 106 is manufactured by guiding the parallel light to the quartz substrate 113 and irradiating the parallel light to the groove 10 obliquely through the mask 112.

Here, assuming that the incident angle φ of light and the irradiation angle of the mirror surface 106 with respect to the normal line of the substrate 101 are ε,

[0070]

(Equation 7)

Are shown as

As described above, the present embodiment has an advantage that the arbitrariness in exposure, such as the irradiation angle and direction, can be made larger than in the first embodiment. In some cases, processing for simultaneously manufacturing the mirror surfaces 106 simultaneously may be limited.

[Third Example] Next, a third embodiment of the present invention will be described with reference to FIG. Note that the first
The description of the same parts as those of the second example and the second example will be omitted, and the same reference numerals will be given.

This embodiment is different from the first embodiment in the exposure method. That is, the exposure means 1 includes a light guide 110 made of an optical fiber or the like and a beam profile conversion lens 1.
14 is provided.

The beam profile conversion lens 114 is
Usually, it has a function of deforming the intensity profile of the light emitted from the light guide 112, which is circular and has poor uniformity of the light intensity around the periphery, into a rectangular shape and improving the uniformity.

At the time of manufacturing the mirror, the light from the ultraviolet light source in the above-described fourth exposure step (D) is
The light guide 110 is guided to the vicinity of the groove 10 using the light guide 110.
Is converted into parallel light by entering the beam profile conversion lens 114, and the light intensity distribution in the beam plane is kept constant to form a rectangular beam shape. Then, the mirror surface 106 is manufactured by irradiating the rectangular parallel light to the groove 10 in the waveguide in an oblique direction.

As described above, in the present example, the arbitrariness in the exposure such as the irradiation angle and direction can be made larger than in the first example. Further, since the mask as used in the second example is not required, there is an advantage that the number of components can be reduced and the manufacturing cost can be suppressed.

[0078]

As described above, according to the present invention,
Using an exposure unit, the optical path of light traveling in the direction perpendicular to the waveguide substrate is changed, and the light whose path has been changed is exposed to the photosensitive material from an oblique direction to form a mirror surface. Therefore, the mirror structure for optical path conversion can be manufactured at an arbitrary position and an arbitrary direction on the waveguide substrate with high accuracy.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a mirror structure according to a first embodiment of the present invention.

FIG. 2 is a sectional view illustrating a method for manufacturing the mirror structure of FIG.

FIG. 3 is a cross-sectional view illustrating a method for manufacturing a mirror structure according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a method for manufacturing a mirror structure according to a third embodiment of the present invention.

5A and 5B show a conventional method for manufacturing a mirror structure, in which FIG. 5A is a sectional view showing a process of ion etching, and FIG. 5B is a sectional view showing a mirror surface after etching.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exposure means 10 Groove 101 Substrate 102 Lower cladding layer 103 Core layer 104 Upper cladding layer 105 Photosensitive material (polymer material, photocurable material) 106 Mirror surface 107 Protective film 108 Mask 109 Prism 110 Optical guide 111 Collimating lens 112 Mask 113 Quartz substrate 114 Beam Profile Conversion Lens

Continued on the front page (72) Inventor Takashi Sakamoto Nippon Telegraph and Telephone Corporation 3-1-2, Nishi-Shinjuku, Shinjuku-ku, Tokyo (72) Inventor Amano Main Tax 3-192-2, Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Inside Telephone Co., Ltd. (72) Inventor Makoto Hikita 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Inside Telegraph and Telephone Corporation (72) Akira Tomaru 3-192-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Co., Ltd. (72) Inventor Koji Enbu 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Co., Ltd. F-term (reference) 2H047 LA09 PA24 QA04 QA05 RA00

Claims (11)

[Claims] 1. A structure having a reflection surface in a waveguide on a substrate, the groove having a polymer material buried in a part of the waveguide, wherein the polymer material embedded in the groove is provided. A mirror structure, wherein at least one surface is set as a reflection surface having a predetermined angle with respect to the substrate. 2. A method for producing a mirror structure having a reflection surface in a waveguide on a substrate, comprising: providing a groove in a region for producing a desired reflection surface in the waveguide by etching. Casting a photosensitive material into the groove region; exposing the region including the groove from an incident direction corresponding to the angle of the reflection surface using an exposure unit; A method for manufacturing a mirror structure, wherein a reflection surface is formed in the groove by removing a region other than a desired region among the regions. 3. The method of manufacturing a mirror structure according to claim 2, further comprising a step of forming a protective film on the reflection surface. 4. The groove is formed in a part of the waveguide, an ultraviolet-curable oligomer is poured into the groove, and the ultraviolet light is irradiated from the optical axis different from the optical axis of the waveguide using the exposure unit. By irradiating a part of the oligomer to cure the oligomer, and removing the UV-irradiated portion of the oligomer, the reflection surface is formed on at least one surface of the polymer material embedded in the groove. The method for manufacturing a mirror structure according to claim 2. 5. The method according to claim 4, wherein the groove is formed in a part of the waveguide by a reactive ion etching method. 6. The exposure means has a prism and a mask, and the ultraviolet light having an optical axis perpendicular to the substrate is incident on the prism to change an optical path, and the ultraviolet light having the changed optical path is provided. 6. A method for manufacturing a mirror structure according to claim 4, wherein a portion of the oligomer is irradiated from the optical axis different from the optical axis of the waveguide through the mask. 7. The method according to claim 6, wherein the prism and the mask are integrally formed. 8. An ultraviolet ray is radiated perpendicularly to the waveguide substrate, the apex angle of the prism is α, the refractive index of the prism is n _p , the refractive index of the oligomer is n _m , and the reflection surface with respect to the normal line of the waveguide substrate. When the irradiation angle of is expressed as ε, 8. The method for manufacturing a mirror structure according to claim 6, wherein the conditions are set to satisfy the following condition. 9. The exposure means has an optical fiber, a lens, and a mask, guides and emits the ultraviolet light from the optical fiber, and the emitted ultraviolet light is different from an optical axis of the waveguide by the lens. The method of manufacturing a mirror structure according to claim 4, wherein the light is converted into a parallel light beam having an optical axis, and the parallel light beam is applied to a part of the oligomer through the mask. 10. The exposure means has an optical fiber and a beam profile conversion lens, guides and emits the ultraviolet light from the optical fiber, and makes the emitted ultraviolet light incident on the beam profile conversion lens to be uniform. 6. A beam having a rectangular shape with an intensity and converted into a parallel light beam having an optical axis different from the optical axis of the waveguide, and irradiating a part of the oligomer with the parallel light beam. The method for manufacturing the mirror structure of the above. 11. An incident angle φ of light and an irradiation angle of the reflecting surface with respect to a normal line of the waveguide substrate are represented by ε. 11. The method for manufacturing a mirror structure according to claim 9, wherein the conditions are set so as to satisfy the following condition.