JP4059835B2 - Multi-channel optical path conversion element - Google Patents

Description

   In order to connect optical elements efficiently, a multi-channel optical path conversion element that converts the traveling direction of an optical circuit is required for the widespread use of optical waveguide devices. The present invention relates to a multi-channel optical path conversion element with low loss and uniform characteristics, and an effective manufacturing method thereof.

  As optical communication technology has permeated as the fundamental technology of information communication systems, optical waveguides are becoming increasingly important as optical network key devices, and at the same time, development is progressing toward applications in fields such as optoelectronic circuit wiring boards. It has been. The spread of optical waveguide devices is demanded for low cost and mass production, and resin optical waveguides that are easy to handle are being developed as promising candidates. As the resin material for the waveguide, fluorinated polyimide resin, deuterated polysiloxane resin, epoxy resin, perfluorinated alicyclic resin, acrylic resin, silicone resin and the like are used.

  The spread of optical waveguide devices is an optical path changing technique that bends an optical circuit abruptly in order to connect elements efficiently, especially various optical signals such as 2-16 channels can be transmitted and received in parallel. Therefore, there is a need for a low-cost optical path conversion element that has low loss and uniform characteristics between channels.

As the optical path conversion component, the inclined end faces of a pair of optical waveguides having an inclined end face at one end and the inclination angle of the inclined end face and the optical waveguide core at the inclined end face being substantially equal to each other, The inclined end faces are connected to each other so that the cores of the optical waveguides on the inclined end faces are substantially coincident with each other, the pair of optical waveguides are fixed in a substantially V shape, and the tops of the V shaped optical waveguides are removed to remove the core. A multi-channel optical path conversion component has been proposed that is manufactured by stacking a plurality of parts that are exposed to a predetermined position and provided with a reflecting surface in parallel at predetermined intervals and covered with a material having a refractive index lower than that of the core. (See Patent Document 1)
However, it requires complicated operations such as a process for producing waveguides with matching inclined surfaces and a process for pasting them together, and the process is complicated. By separately producing a horizontal waveguide and a vertical waveguide, The horizontal waveguide is likely to be misaligned and the loss may increase.

In addition, a method has been proposed in which a waveguide is horizontally formed on a substrate, a reflecting mirror is subsequently formed, a cladding layer is formed, a vertical opening is provided in the horizontal waveguide, and light is passed through the hollow portion. . (See Patent Document 2)
In this case, reflection or scattering of light occurs at the boundary between the core and the hollow portion, and loss increases. Even when the hollow portion is filled with the core material, the horizontal waveguide and the vertical waveguide are produced separately, and the vertical waveguide and the horizontal waveguide are likely to be misaligned. An interface is generated at the boundary between the cores of the portions, which causes an increase in loss.
JP 2001-194540 A JP 2000-193838 A

  In a multi-channel optical path conversion element that converts a plurality of optical paths using a mirror, an optical path conversion element with low loss and uniform characteristics between channels, and a manufacturing method that combines ease of manufacture and low cost are provided. Let it be an issue.

Further, the present invention is a method of manufacturing a resin multi-channel optical path conversion optical element,
1) Deposit a sacrificial layer on the temporary substrate,
2) A clad layer is formed thereon, and the clad layer is selectively etched to form a rectangular parallelepiped block made of clad resin,
3) Forming a core layer covering the block with a core resin,
4) By selectively etching the core layer and the block, a multi-channel core in which a core perpendicular to the substrate and a parallel core are integrally formed is formed at the same time, and embedded with a clad resin.
5) A V-groove for forming a mirror surface at the corner of the core is prepared, and a reflective film is formed to form a mirror surface.
6) V-groove is filled with clad resin, a base is pasted thereon, and after removing the temporary substrate described in the above item 1), at least six steps are carried out by cutting and separating into multi-channel optical path conversion elements. This is a method for manufacturing the element.

  In the wafer process, the vertical and horizontal portions of the waveguide core are integrally formed, and the cores of a plurality of channels are formed simultaneously while maintaining the positional relationship with each other. A multi-channel optical path conversion element having both low loss and low cost can be provided.

Hereinafter, the present invention will be described in detail.
FIG. 1 is a diagram for explaining an example of a manufacturing process of a multi-channel optical path conversion element of the present invention. The multi-channel optical path conversion element is manufactured by the following process. In FIG. 1A, a sacrificial layer 2 which is a metal film soluble in an acid is formed on a temporary substrate 1 using a technique such as magnetron sputtering. The sacrificial layer 2 may be a water-soluble resin.

 In FIG. 1B, the cladding layer 3 is formed. In FIG. 1C, the cladding block 4 is produced by a technique of photolithography and reactive ion etching (RIE). The block 4 has a rectangular parallelepiped shape, and the size thereof is appropriately selected as required by the optical path conversion element to be created. In addition, this block may be manufactured individually for each element, but it is also preferable to manufacture continuous blocks for a plurality of parallel elements in a line. A perspective view of the cladding block 4 is shown in FIG. This process can also be produced by a direct exposure method, a molding method, or a technique using a dicing saw.

  In FIG. 1D, a core layer 5 covering the cladding block 4 is formed. In FIG. 1E, a core 6 in which a horizontal portion and a vertical portion are integrally formed is produced by a technique of photolithography and reactive ion etching. A perspective view of the multi-channel core 6 is shown in FIG. This process can also be produced by a direct exposure method, a molding method, or a technique using a dicing saw. In FIG. 1 (f), the entire cladding layer 7 is filled.

In FIG. 1G, a V-groove 8 is produced by a dicing saw, and a reflection film 9 is formed using a technique such as magnetron sputtering to form a mirror. A metal film, a dielectric multilayer film, or the like is used as the reflection film. For forming the mirror surface, a method in which a prism formed with a reflective film is disposed in the V-groove and fixed with an adhesive or the like is also suitable. Also, a 45 ° cut can be made with a dicing saw, a film on which a reflective film is formed can be inserted, and fixed with an adhesive. In FIG. 1H, the V groove is filled with the clad resin 10 to flatten the element surface. In FIG. 1I, the substrate 11 is attached to the waveguide. As the substrate, a glass substrate, a silicon substrate, a resin substrate, or the like can be used. In FIG. 1 (j), the sacrificial layer 2 is removed using acid or the like, the temporary substrate 1 is removed, and the multi-channel optical path conversion element is cut and separated by a DAISO. By this method, cores with the mirrors sandwiched in the direction of the optical path are integrally formed, and a plurality of channel cores are formed simultaneously while maintaining the mutual positional relationship. The multi-channel optical path conversion element can be manufactured at once with high accuracy.
Hereinafter, the present invention will be described specifically by way of examples.

  A 4-channel optical path conversion element was produced. The size of the core cross section (viewed in FIG. 3E-E) is a square of 40 μm × 40 μm, and the core pitch between channels is 0.25 mm.

First, a sacrificial layer was formed on a 4-inch temporary glass substrate using magnetron sputtering. Al (thickness of about 1 μm) was used for the sacrificial layer. Next, a clad layer was formed. Epoxy resin was used for the cladding, and spin coating was used for film formation. After the film formation, planarization was performed by grinding and polishing, and the thickness of the clad layer was set to 70 μm. Next, a mask material was formed on the clad layer and patterned by photolithography. Al was used as the mask material, and unnecessary portions of the cladding layer that was not protected by the mask layer were removed by inflowing O ₂ gas by etching (O ₂ -RIE), thereby producing a rectangular parallelepiped block of the cladding. The height of the cladding block is 70 μm (A in FIG. 3), the width is 1 mm (B in FIG. 3), and the cladding blocks of a plurality of elements arranged in series are integrated in the direction perpendicular to the paper surface of FIG. Created in line.

A core layer was formed thereon by a spin coating method. An epoxy resin was used for the core layer. After the film formation, the top surface of the core layer was ground and polished, and the surface was flattened. The core layer thickness was 40 μm from the top of the cladding block. Next, an Al mask material is formed on the core layer and patterned by photolithography. Thereafter, unnecessary portions of the core layer and the cladding block are removed by O ₂ -RIE, and bent at a right angle along the cladding block. A core was prepared (FIG. 3). The size of the core is 40 μm × 40 μm (see FIG. 3E-E), and the horizontal part and the vertical part have the same size. The length of the core vertical portion is 110 μm (C in FIG. 3) from the upper end of the core horizontal portion, and the length of the core horizontal portion is 1,040 μm (D in FIG. 3) from the outer end of the core vertical portion. Next, the entire surface was filled with a clad resin, and after film formation, the upper surface of the clad resin was ground and polished to perform a flattening process. A spin coat method was used for filling the clad resin.

  Thereafter, a V-groove was formed with a dicing saw at a right-angled bent portion of the core to form a mirror film. The mirror was formed by magnetron sputtering so that an Au film was formed only in the V-groove portion. After forming the mirror surface, the V-groove was filled with a clad resin, a clad layer was formed, and the surface was ground and polished to perform a flattening process. Next, the glass substrate was attached to the upper surface of the clad layer using an epoxy adhesive, and then the sacrificial layer was dissolved to remove the temporary substrate. For the removal of the sacrificial layer, a mixed solution of copper sulfate, ferric chloride, and water was used. Next, each element was cut and separated into a 2 mm × 2 mm square to obtain 803 four-channel optical path conversion elements. When insertion loss was measured by passing light having a wavelength of 1.3 microns, there were 667 waveguides having an insertion loss of 3 dB or less in the waveguide in the element and a variation in insertion loss of 0.1 dB or less in the element ( 83%), and a homogeneous four-channel optical path conversion element could be manufactured at a high yield at a time.

FIG. 1 is a diagram showing an example of a manufacturing process of a multi-channel optical path conversion element according to the present invention. FIG. 2A shows a cladding block and FIG. 2B shows a core in which a horizontal portion and a vertical portion are integrally formed in a manufacturing process of a multi-channel optical path conversion element. FIG. 3 is a diagram illustrating a relationship between the core block and the core in the embodiment.

Explanation of symbols

1, provisional substrate 2, sacrificial layer 3, clad layer 4 formed on the sacrificial layer, clad block 5, core layer 6, core 7 in which horizontal and vertical portions are integrally formed, multi-channel core Covered clad layer 8, V-groove 9, reflective film 10, clad resin 11, substrate

Claims (1)

A method of manufacturing a resin-made multi-channel optical path conversion optical element,
1) Deposit a sacrificial layer on the temporary substrate,
2) A clad layer is formed thereon, and the clad layer is selectively etched to form a rectangular parallelepiped block made of clad resin,
3) Forming a core layer covering the block with a core resin,
4) By selectively etching the core layer and the block, a multi-channel core in which a core perpendicular to the substrate and a core parallel to the substrate are integrally formed is formed at the same time, and embedded with a clad resin;
5) A V-groove for forming a mirror surface at the corner of the core is prepared, and a reflective film is formed to form a mirror surface.
6) It includes six steps consisting of embedding the V-groove with clad resin, pasting the substrate thereon, removing the temporary substrate of the above item 1), and then cutting and separating into multi-channel optical path conversion elements. A method for producing a multi-channel optical path conversion element made of resin.