JP2009098485A - Device with adhered mirror for converting optical path and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reliable device for converting multi-channel optical path of low loss for converting a plurality of optical paths using a mirror, and to provide a simple method for manufacturing. <P>SOLUTION: In the method of manufacturing the device for converting the optical path, a V groove slope forming an angle of substantially 45 ° with respect to both a vertical waveguide and a horizontal waveguide is formed in the intersection of them; a reflective film is formed on a bar-like body whose edge angle substantially matches with the angle between the slopes of the V groove; the reflective film is adhered to an end of a waveguide core on the V groove slope so that the film is in contact with the end to provide a mirror. In this method, the V groove is formed of a diamond blade having average grain size between 8 μm and 20 μm; the reflective film is formed on the surface of the bar-like body whose surface roughness Ra is 10 nm or less, and the edge of the bar-like body corresponding to the tip of the V groove is chamfered by a value more than the amount of the curved section at the tip of the V groove, and is adhered and fixed to the V groove with an adhesive. Also, the device for converting multi-channel optical path manufactured by the method is provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multi-channel optical path conversion element for converting the traveling direction of an optical circuit, which is necessary to efficiently connect between chips and between optical interconnections between boards. The present invention relates to an optical path conversion element and an effective manufacturing method thereof.

  As the amount of information increases and the processing speed increases, it is expected that metal wiring will not be able to cope with it, and the development of optical interconnection using light is being promoted. For these spreads, low cost and mass production are demanded, and a resin optical waveguide that is easy to handle has been developed as an effective component. As the resin material for the waveguide, fluorinated polyimide resin, epoxy resin, acrylic resin, silicone resin, or the like is used. In order to efficiently and inexpensively produce optical interconnections, it is important that semiconductor elements such as LDs and PDs used for optical interconnections can be mounted on a plane. To that end, optical path conversion technology that sharply bends the optical circuit of the horizontal resin optical waveguide, especially various multi-channel optical path conversion capable of transmitting and receiving a plurality of optical signals in parallel such as 2 to 16 channels. A device is needed. These optical path conversion elements are required to have little loss, have uniform characteristics between channels, and maintain the positional relationship between cores. In particular, maintaining the positional relationship between the cores directly affects the device characteristics, so that the accuracy is required to be ± 2.5 μm or less.

  It is also necessary to keep the loss at the mirror part that converts the optical path low. For this reason, gold, silver alloy, aluminum having a high reflectance, or a dielectric multilayer film having a high reflectance at a specific wavelength is used for the mirror portion.

  As a multi-channel optical path conversion component, a method has been proposed in which identical substrates on which orthogonal optical waveguides are formed are bonded together so that their optical axes take a predetermined relative position, and then a mirror is formed in the orthogonal optical waveguide portion. ing. In order to form the mirror part, a part of the intersecting part of the waveguide is cut by dicing to form a mirror surface, and a polishing method is shown to improve the flatness (see Patent Document 1).

Also, there has been proposed an opto-electric wiring board having two waveguides and connecting the signals of the waveguides by mirrors at the intersections of the waveguides. As a method of forming the mirrors, formation by dicer and formation by RIE are shown. (See Patent Document 2).
JP 2003-315578 A Republished patent WO01 / 001176

  However, in the formation by the dicer, when the mirror surface is not polished, the surface roughness of the mirror surface is rough, the reflectance is lowered, and the element loss is increased. Further, when polishing, it is very difficult to obtain the position accuracy of the reflecting surface with high accuracy, and it is necessary to polish many times while confirming the position, which takes time. It is difficult to regenerate after polishing past a predetermined position.

  In addition, the formation by RIE requires a long time for etching because the groove depth is deep. In addition, it is very difficult to accurately etch the position of the slope and the angle of the slope.

  In the present invention, a V-shaped groove slope having an angle of about 45 degrees with both waveguides is formed at the intersection of a vertical waveguide and a horizontal waveguide, and a bar shape having a ridge angle substantially coincident with the angle between the slopes of the V-groove. A reflection film is formed on the body, and the reflection film is attached so that the reflection film is in contact with the waveguide core end portion of the V-groove slope. In the production of an optical path conversion element as a mirror, the V-groove has an average particle diameter of 8 μm or more and 20 μm or less. Formed with a diamond blade, a reflective film is formed on the surface of the rod-shaped body having a surface roughness Ra of 10 nm or less, and the ridge of the rod-shaped body corresponding to the V-groove tip is chamfered more than the amount of the curved surface of the V-groove This is a method of manufacturing an optical path conversion element that is bonded and fixed to the V groove with an adhesive.

  Further, the present invention provides a method for producing an optical path conversion element in which the reflective film is a dielectric multilayer film made of silica and a material having a higher refractive index than that of silica, and the dielectric multilayer film is configured such that silica is on the outermost surface.

  Further, the present invention is a method for manufacturing an optical path conversion element in which the material having a higher refractive index than silica is tantalum pentoxide.

  Further, in the optical path conversion element, the reflective film is a metal reflective film having an area that is not less than twice the area of the end of the waveguide core on the slope of the V-groove and 2/3 or less of the area of the side surface of the rod-like body on which the reflective film is formed. This is a manufacturing method.

  Furthermore, it is a manufacturing method of a multi-channel optical path conversion element in which the reflective film is a number of separated gold mirrors.

  Furthermore, it is a multi-channel optical path conversion element manufactured by the above manufacturing method.

  A highly reflective metal or dielectric multilayer mirror is formed on the surface of a rod-shaped body having a small surface roughness, and is applied to the slope of the V-groove formed at the intersection of the vertical waveguide and the horizontal waveguide. Since a high mirror can be installed with high positional accuracy, an element with low loss can be easily manufactured. It is easy to reduce the surface roughness of the surface on which the reflective film is formed by forming a dielectric multilayer film on a flat plate-like substrate such as glass or silicon, and then cutting out the rod-shaped body. . A metal film or a dielectric multilayer film can be formed on these surfaces by a conventional technique. Further, it is possible to easily cut out these formed substrates into rods by using a dicer or the like. On the other hand, making the V-groove slope as a mirror surface and accurately forming the position accuracy of the reflecting surface requires very high technology, and the process becomes complicated and requires a lot of time.

  In the present invention, since the V-groove is formed with a diamond blade having an average particle diameter of 8 μm to 20 μm, the adhesive can be filled in a short time without bubbles or the like between the slope of the V-groove and the rod-like body. The position of the V groove can also be formed with the required accuracy. In addition, since the V-groove is formed by a diamond blade having an average particle diameter of 8 μm to 20 μm, it does not take a long time to form the V-groove even if the element member is a hard material such as glass. It takes a shorter time compared to the case of forming the direct reflection film. This makes it possible to easily form a mirror part with high reflectivity in a short time.

  When the reflective film is a dielectric multilayer film, the adhesion of the dielectric multilayer film to the slope of the V-groove can be enhanced by using silica as the outermost surface of the film formed in the rod-shaped body.

  When the reflective film is a metal, the area of the reflective film is at least twice the area of the waveguide core end and 2/3 or less of the side surface of the rod-shaped body on which the reflective film is formed. By increasing the adhesion, it becomes possible to supplement the adhesion between the metal reflection film and the slope of the V groove, and it is possible to manufacture a highly reliable element.

  Hereinafter, the present invention will be described in detail.

  FIG. 1 is a diagram in which a V-groove is formed at the intersection of a vertical waveguide and a horizontal waveguide.

  The V groove is formed by a dicer using a V-shaped blade at the tip. A method other than a dicer is also possible, but the method using a dicer is simple and enables high-precision processing. The tip angle of the V groove may be 90 ° (one side 45 ° × 2) or 45 ° (one side 45 ° one side vertical).

  One side is 45 ° and the other side is vertical or an angle other than 45 ° is possible, but 90 ° or 45 ° is used to confirm the fabrication accuracy of mirrors and waveguides when it is not particularly necessary for the design. It is preferable from the aspect of ease.

  FIG. 2 shows a rod-like body on which a dielectric multilayer film is formed. The rod-shaped body is produced by forming a metal film or a dielectric multilayer film on a flat substrate such as glass or silicon having a small surface roughness by sputtering or the like, and cutting out with a dicer. Glass substrates and silicon substrates having a small surface roughness are commercially available and can be easily obtained. The mirror-finished surface of these materials usually has a surface roughness Ra of less than 10 nm.

  The configuration of the dielectric multilayer film varies depending on the characteristics of the reflection (or transmission) spectrum. The film configuration is not limited to one type, and several configurations are possible. In general, a film having a high refractive index and a film having a low refractive index are laminated, combined with the number of layers, and desired film thickness is obtained by changing the film thickness of each layer. It is possible to design the silica film as the outermost surface without greatly impairing the reflection characteristics. As the material of the film, inorganic materials such as silica and tantalum pentoxide are used. In the present invention, a rod-like body on which a reflective film is formed is bonded and fixed to a V-groove with an adhesive in order to ensure ease of manufacture and secure a highly accurate mirror position, and the outermost surface is a silica film. By using this dielectric multilayer film, it is possible to produce a highly reliable device with strong adhesion.

  FIG. 3 shows a rod-like body when the reflective film is gold. When gold is used as the reflective film, the adhesion between the film and the substrate is weak, and in order to compensate for this, it is desirable to first form a film of titanium or chromium on the substrate and then deposit gold on the film. Sputtering, vacuum deposition, and other dry processes are suitable for the film forming method, but application of wet processes such as plating is also possible.

  The thickness of the reflective film is preferably 1 μm or more in order to ensure reflectivity. The reflective film can be patterned by a photolithography method and a lift-off method that are generally used. The reflective film is formed and patterned in a wafer state, and then cut into a rod-shaped body. Although it is possible to form a film on a rod-shaped body and pattern it, it is efficient to perform film formation and patterning in a wafer state and then cut it into a rod-shaped body.

  FIG. 4 is a view in which a rod-like body having a reflective film formed in the V-groove is inserted. The corner of the rod-shaped body must be formed so as to match the cross-sectional shape of the V-groove, but a 90 ° one is easy to manufacture. A 45 ° one can also be formed relatively easily. Others are difficult to manufacture and require time. A rod-shaped body with a 90 ° corner can be easily manufactured with a rectangular cross-section, and may be square or rectangular.

  The bottom of the V groove formed by the dicer blade is curved. Accordingly, if the ridge on the bottom side of the V-shaped groove of the rod-shaped body is a right angle, if the rod-shaped body is pressed and fixed with an adhesive, the distance between the slope of the V-groove and the reflecting film varies depending on the location, and the reflecting film cannot be installed at an accurate angle. When the corresponding ridges of the rod-like body are chamfered, the reflective film and the V-groove slope contact each other, and an accurate setting becomes possible. Usually, the size of the curved portion at the bottom of the V groove is 20 μm or less. Therefore, chamfering of about 50 μm may be performed.

  The chamfering can be easily formed by cutting the rod-shaped body from the wafer shallowly with a V-shaped tip blade and then completely cutting the tip with a normal blade having a rectangular shape. The rod-like body cross-sectional shape may be a square with one corner chamfered or a rectangle with one corner chamfered. A corner angle of 45 ° can also be produced by using a V-shaped blade and a rectangular blade at the tip.

  Next, an adhesive is injected to fix the rod-shaped body in the V-groove. FIG. 5 is a view in which the rod-like body is bonded and fixed to the V groove with an adhesive. As the adhesive, an ultraviolet curing agent which is transparent and has a refractive index equal to or close to the refractive index of the core is suitable. The UV curing agent can be efficiently operated with a short curing time. An ultraviolet heat combined adhesive and a thermosetting adhesive can also be used. When injecting the adhesive, it is preferable to hold the rod-shaped body with a jig so that the rod-shaped body is not displaced from the setting position. The resin is preferably injected sequentially from one direction so as not to bite the bubbles. If bubbles remain in the reflection part of the optical path, the reflection efficiency changes and the characteristics change. Usually loss increases.

  Hereinafter, an example explains.

  A dielectric multilayer film having a reflectance of 98% or more at a wavelength of 850 nm comprising a multilayer film of silica and tantalum pentoxide having a structure in which silica is the outermost layer is formed on a borosilicate glass substrate having a diameter of 0.5 mm and a thickness of 100 mm. Next, a V-groove having a width of 250 μm was formed by a dicer using a V-shaped blade. Next, using a normal blade with a blade width of 150 μm, the center position of the V-groove is completely cut in the horizontal direction and then cut in the vertical direction to a length of 20 mm, with a reflective film pattern. A rod-shaped body with chamfered ridges was prepared.

  Next, a waveguide in which a vertical waveguide having a cross section of 40 μm and a horizontal waveguide intersect with each other is arranged in 12 channels at a pitch of 250 μm in the vertical direction with respect to the waveguide, and an average diamond number 1000 is added to a waveguide element in which four sets are incorporated. A V-groove was formed with a blade having a V-shaped tip (90 ° angle) with a V-groove slope at the intersection of the vertical waveguide and the horizontal waveguide. The position of the V-groove slope was cut so as to enter 5 μm inside the diagonal line of the intersection of the vertical waveguide and the horizontal waveguide.

  A rod-shaped body having a reflection film formed in the groove was placed so that the reflection film pattern was in contact with the end of the waveguide, and an ultraviolet curable adhesive was injected using a dispenser while holding the rod-shaped body, and cured by irradiation with ultraviolet rays. The length of the vertical waveguide is approximately 1 mm, and the length of the horizontal waveguide is approximately 10 mm. In the loss measurement using the light source of 850 nm, the loss was 4 dB or less for each channel.

  A photoresist is applied to a borosilicate glass substrate having a thickness of 0.5 mm and a diameter of 100 mm using a spin coater and prebaked, and then ultraviolet rays are applied by an exposure machine using a mask in which 100 μm square patterns are arranged at a pitch of 650 μm in the vertical direction and a pitch of 250 μm in the horizontal direction. After irradiation, development and post-baking were performed to form a resist pattern on the glass substrate. Next, after depositing 100 nm of titanium and then 1.5 μm of gold on a substrate on which a resist pattern was formed by sputtering, the resist was peeled off, and a reflective film pattern was formed by a lift-off method.

  Next, a V-shaped groove having a width of 250 μm was formed in the lateral direction along the reflective film pattern by a dicer using a V-shaped blade. Next, using a normal blade with a blade width of 150 μm, the center position of the V-groove is completely cut in the horizontal direction and then cut in the vertical direction to a length of 20 mm, with a reflective film pattern. A rod-shaped body with chamfered ridges was prepared.

  Next, a waveguide in which a vertical waveguide having a cross section of 40 μm and a horizontal waveguide intersect with each other is arranged in 12 channels at a pitch of 250 μm in the vertical direction with respect to the waveguide, and an average diamond number 1000 is added to a waveguide element in which four sets are incorporated. A V-groove was formed by a blade having a V-shaped particle tip (angle 90 °) so that the slope of the V-groove comes to the intersection of the vertical waveguide and the horizontal waveguide. The position of the V-groove slope was cut so as to enter 5 μm inside the diagonal line of the intersection of the vertical waveguide and the horizontal waveguide.

  A rod-shaped body having a reflection film formed in the groove was placed so that the reflection film pattern was in contact with the end of the waveguide, and an ultraviolet curable adhesive was injected using a dispenser while holding the rod-shaped body, and cured by irradiation with ultraviolet rays. The length of the vertical waveguide is approximately 1 mm, and the length of the horizontal waveguide is approximately 10 mm. In the loss measurement using the light source of 850 nm, the loss was 4 dB or less for each channel.

  A photoresist is applied to a borosilicate glass substrate having a diameter of 0.3 mm and a diameter of 100 mm using a spin coater and prebaked, and then ultraviolet rays are applied by an exposure machine using a mask in which 100 μm square patterns are arranged at a pitch of 650 μm in the vertical direction and a pitch of 250 μm in the horizontal direction. After irradiation, development and post-baking were performed to form a resist pattern on the glass substrate. Next, after depositing 100 nm of titanium and then 1.5 μm of gold on a substrate on which a resist pattern was formed by sputtering, the resist was peeled off, and a reflective film pattern was formed by a lift-off method.

  Next, a V-groove having a width of 500 μm was formed on the back side of the substrate along the reflective film pattern in the lateral direction by a dicer using a V-shaped blade. Next, using a normal blade having a blade width of 150 μm, the both sides of the reflective film pattern are completely cut in the horizontal direction using a normal blade, and then the vertical direction is cut so that the length is 20 mm. A rod-like body with a chamfered ridge was produced.

  Next, a waveguide in which a vertical waveguide having a cross section of 40 μm and a horizontal waveguide intersect with each other is arranged in 12 channels at a pitch of 250 μm in the vertical direction with respect to the waveguide, and an average diamond number 1000 is added to a waveguide element in which four sets are incorporated. A V-groove was formed with a blade having a V-shaped tip (angle 45 °) so that the slope of the V-groove comes to the intersection of the vertical waveguide and the horizontal waveguide. The position of the V-groove slope was cut so as to enter 5 μm inside the diagonal line of the intersection of the vertical waveguide and the horizontal waveguide.

  A rod-shaped body having a reflection film formed in the groove was placed so that the reflection film pattern was in contact with the end of the waveguide, and an ultraviolet curable adhesive was injected using a dispenser while holding the rod-shaped body, and cured by irradiation with ultraviolet rays. The length of the vertical waveguide is approximately 1 mm, and the length of the horizontal waveguide is approximately 10 mm. In the loss measurement using the light source of 850 nm, the loss was 4 dB or less for each channel.

  The present invention can be used not only in a communication system in the field of optical communication but also in an application field of optical transmission such as evaluation and measurement.

The V groove for mirrors is shown. The rod-shaped body with a dielectric multilayer film reflective film is shown. The rod-shaped body with a metal reflective film is shown. The state which inserted the rod-shaped body with a reflecting film in V groove is shown. A state where the rod-shaped body is bonded and fixed to the V-groove with an adhesive is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mirror groove | channel 2 Horizontal waveguide 3 Vertical waveguide 4 A rod-shaped body with one edge chamfered in a rectangular shape 5 Dielectric multilayer film reflection film 6 Metal reflection film 7 A section with one edge chamfered in a triangle Rod
8 Adhesive

Claims (6)

A V-groove inclined surface that forms an angle of approximately 45 degrees with the two waveguides is formed at the intersection of the vertical waveguide and the horizontal waveguide, and a reflective film is formed on the rod-shaped body having a ridge angle substantially coincident with the angle between the inclined surfaces of the V-groove. In the manufacture of an optical path conversion element to be used as a mirror, the V groove is formed by a diamond blade having an average particle diameter of 8 μm or more and 20 μm or less. Then, a reflective film is formed on the surface of the rod-shaped body having a surface roughness Ra of 10 nm or less, and the ridge of the rod-shaped body corresponding to the tip of the V-groove is chamfered more than the amount of the curved surface at the tip of the V-groove. A method for producing an optical path conversion element bonded and fixed with an adhesive. 2. The optical path conversion element according to claim 1, wherein the reflection film is a dielectric multilayer film made of silica and a material having a higher refractive index than silica, and the dielectric multilayer film has a configuration in which silica comes to the outermost surface. Manufacturing method. The method for producing an optical path conversion element according to claim 2, wherein the material having a higher refractive index than silica is tantalum pentoxide. The reflective film is a metal reflective film having an area that is not less than twice the area of the waveguide core end portion of the slope of the V-groove and not more than 2/3 of the area of the side surface of the rod-like body on which the reflective film is formed. Item 2. A method for producing an optical path conversion element according to Item 1. 5. The method for producing a multi-channel optical path conversion element according to claim 4, wherein the reflective film is a number of separated gold mirrors. A multi-channel optical path conversion element manufactured by the manufacturing method according to claim 1.

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