JP2006133569A - Optical waveguide module, manufacturing method thereof, and optical communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a filter insertion groove having a high width accuracy for suppressing the inclination of an optical element, and to provide an inexpensive optical waveguide module manufactured by the manufacturing method and an optical communication apparatus. <P>SOLUTION: An etching groove 111a is formed on a silicon substrate 16 by DRIE. An optical waveguide 103 is bonded on a substrate 102 formed with the etching groove 111a. A through-groove 111b is formed on the optical waveguide 103 so as to be communicated with the etching groove 111a, and the filter insertion groove 111 is accomplished by the etching groove 111a and through-groove 111b. A filter 110 is inserted into the filter insertion groove 111 and is fixed by filling and curing an adhesive 112. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical waveguide module, a method for manufacturing the same, and an apparatus for optical communication.

  In recent years, the wave of broadband has been rushing and the ADSL service has started in Japan, and the number of users is increasing rapidly. In addition, a Fiber-To-The-Home (FTTH) service using an optical fiber that can meet the demand for higher speed has been started in some areas in 2001. The center of the current broadband service is ADSL, but it is considered that FTTH will be rapidly advanced as broadband becomes more advanced. In order to spread the FTTH service, it is necessary to develop a high-performance and low-cost optical waveguide module with low optical loss.

  There are various types of optical waveguide modules such as an optical multiplexer / demultiplexer and an optical transceiver depending on the purpose. For example, in an optical multiplexer / demultiplexer or optical transceiver, an optical element such as a filter that demultiplexes light of a plurality of wavelengths by transmitting or reflecting light of a specific wavelength among the light of a plurality of wavelengths propagating through the inside is inserted. ing. However, if the insertion state of the filter is poor, there is a problem that the loss of light transmitted or reflected by the filter becomes large. In order to reduce optical loss, the filter must be inserted as perpendicular to the optical waveguide module as possible. Therefore, it is very important to accurately form the groove width for inserting the filter.

  As a conventional method for forming a filter insertion groove of an optical waveguide module, a method using a dicing blade and a method using etching have been proposed.

  Japanese Patent No. 3175814 discloses a method of forming a filter insertion groove using a dicing blade. In general, dicing is considered difficult to process a thin (narrow) groove. This is because if a thin groove is to be deeply processed using a dicing saw, a thin dicing blade is required, and the blade cannot withstand the load during processing. As a result, the width of the filter insertion groove is widened or the groove itself is inclined. Therefore, in Japanese Patent No. 3175814, a wide filter insertion groove is formed using a dicing blade that is thicker than the thickness of the filter, and a specially processed filter is inserted therein to insert a warped filter. It is possible to insert a filter vertically even in a wide groove.

  However, when the object to be processed is a quartz glass substrate, a silicon substrate, or the like, the dicing blade is significantly worn by the processing, so it is very difficult to maintain the width accuracy of the mass-produced filter insertion groove. It is also possible to replace the blade frequently to ensure the width accuracy of the filter insertion groove, but it is very uneconomical.

  On the other hand, Japanese Patent Application Laid-Open No. 2003-140058 discloses a method of forming a filter insertion groove by etching without using a dicing blade. This method is a method of forming a filter insertion groove by dry etching, and the filter insertion groove can be formed with very high accuracy as compared with a method using a dicing blade.

  However, this formation method has selectivity depending on the optical waveguide material. For example, in the case of an optical waveguide module in which an optical waveguide made of a resin-based material is formed on a quartz glass substrate or a silicon substrate, the optical waveguide is also etched in the horizontal direction when the substrate is etched. The width of the insertion groove is considerably widened. As a result, there is a problem that the loss of light propagating in the optical waveguide becomes large.

  When the optical waveguide itself is formed of quartz glass, the filter insertion groove forming method is effective because it is not etched in the horizontal direction. However, the optical waveguide formed of quartz glass has a low production efficiency because the etching time required for groove formation is very long compared to the resin waveguide. In addition, the material cost is high and uneconomical.

Japanese Patent No. 3175814 Japanese Patent Laid-Open No. 2003-140058

  The present invention has been made in view of the technical problems as described above, and the object of the present invention is a method of forming a groove with high width accuracy capable of suppressing the tilt of an optical element and a manufacturing method thereof. An object of the present invention is to provide an inexpensive optical waveguide module and an optical communication device.

  An optical waveguide module manufacturing method according to the present invention includes: an optical waveguide module including an optical waveguide formed on a substrate; and an element insertion groove having a depth extending from the optical waveguide to the substrate. A step of forming a groove, a step of forming the optical waveguide on the substrate after forming the groove, a step of forming a through hole in the optical waveguide so as to communicate with the groove, the groove and the And a step of inserting an optical element into the element insertion groove formed by a through hole.

  According to such a method for manufacturing an optical waveguide module, since an element insertion groove with high width accuracy can be formed, an effect of suppressing the tilt of the optical element and reducing optical loss can be obtained. Further, since the groove is already formed on the substrate side by etching, even if the through hole is formed in the optical waveguide by dicing, it is only necessary to process the optical waveguide (thickness of about 50 μm). The dicing blade is less likely to be worn compared to the conventional processing of the substrate (groove depth of about 150 μm) and the optical waveguide by dicing. Further, since the filter can be inserted vertically by the groove formed in the substrate by etching, a dicing blade having a thickness larger than the thickness of the filter can be used. Furthermore, even if the dicing blade is worn slightly, there is no problem unless it becomes narrower than the groove formed in the substrate. Furthermore, since a normal optical element can be used, an optical element processed into a special shape becomes unnecessary.

  According to the embodiment of the method for manufacturing an optical waveguide module according to the present invention, before forming the optical waveguide on the substrate, the step of filling the groove with the filler, and the step of forming the through hole in the optical waveguide And a step of removing the filler from the groove. According to an embodiment of the method for manufacturing an optical waveguide module according to the present invention, before forming the optical waveguide on the substrate, the step of embedding the filler in the groove, and the through-hole in the optical waveguide Forming and removing the filler from the groove. According to an embodiment of the method for manufacturing an optical waveguide module according to the present invention, the filler is a water-soluble resin.

  Therefore, according to such a method of manufacturing an optical waveguide module, since the filler is embedded in the groove, the adhesive is applied to the groove formed on the substrate in the step of bonding the optical waveguide on the substrate with an adhesive or the like. Do not flow. If the filler embedded in the groove is water-soluble, the filler can be easily removed by washing without using a special method. Further, if a method using water is used as the method for forming the through hole, the filler embedded in the groove can be removed simultaneously with the formation of the through hole, and the process can be simplified.

  The embodiment of the method for manufacturing an optical waveguide module according to the present invention is characterized in that the width of the optical waveguide to be removed is processed wider than the width of the groove.

  According to such a method of manufacturing an optical waveguide module, in the step of inserting and fixing the optical element in the groove and the through hole, the optical element can be easily inserted and an adhesive is provided between the optical element and the groove and the through hole. It becomes easy to pour the adhesive when the pour is fixed.

  In addition, the component demonstrated above of this invention can be combined arbitrarily as much as possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, it goes without saying that the present invention is not limited to the examples described below.

  FIG. 1 is an external perspective view of an optical waveguide module 101 according to Embodiment 1 of the present invention. FIG. 2 is a view taken in the direction of arrow X in FIG. FIG. 3 is a plan view of the optical waveguide module 101 shown with the upper cladding layer 105 removed.

  In this optical waveguide module 101, a planar optical waveguide 103 is formed on a substrate 102 such as a silicon substrate or a glass substrate. The optical waveguide 103 is recessed on the surface side in contact with the lower cladding layer 104 bonded to the substrate 102, the upper cladding layer 105 laminated on the lower cladding layer 104, and the upper cladding layer 105 of the lower cladding layer 104. The core groove 109 and three cores 106, 107, 108 formed in the core groove 109. The core 106 (first core) and the core 107 (second core) constitute a curved main core. Both ends of the main core (ends outside the cores 106 and 107) reach both end faces of the lower cladding layer 104, and at both ends of the lower cladding layer 104, the ends of the cores 106 and 107 are in the longitudinal direction of the lower cladding layer 104. It is formed in parallel straight lines. Further, the central portion of the main core is curved in an S shape, and the main core is separated into the core 106 and the core 107 by the filter insertion groove 111 cut from the upper surface of the upper cladding layer 105 to the substrate 102 at the curved portion. Has been. A filter 110 made of a dielectric multilayer film or the like is inserted into the filter insertion groove 111, and the end surfaces of the core 106 and the core 107 are exposed in the filter insertion groove 111 and are optically coupled to each other with the filter 110 interposed therebetween. To face each other. The filter 110 is fixed by filling and curing the adhesive 112 in the remaining gap in which the filter 110 is inserted in the filter insertion groove 111. For example, the filter 110 transmits light in the wavelength region of wavelength λ1 (= 1.31 μm) and reflects light in the wavelength region of wavelength λ2 (= 1.55 μm).

  The core 108 (third core) extends linearly and is disposed on the same side as the core 106 with respect to the filter insertion groove 111. The core 108 is arranged on the side where the curved portion of the core 106 is convex. The inner end surface of the core 108 is adjacent to the side surface of the core 106 with a gap (gap) of 3 to 15 μm, and the end portion of the core 106 and the end portion of the core 108 are optically connected through the filter 110. Are connected. A part of the core 108 is exposed in the filter insertion groove 111. The outer end of the core 108 reaches the side surface of the lower cladding layer 104.

  The lower cladding layer 104 and the upper cladding layer 105 are made of quartz glass or translucent resin, and the cores 106 to 108 are made of quartz glass or transparent glass having a higher refractive index than the upper and lower cladding layers 105 and 104. It is formed of a light resin. In particular, resin waveguides in which the upper and lower cladding layers 105 and 104 and the cores 106 to 108 are made of resin can be mass-produced by duplication, so that a low-cost optical waveguide module can be obtained. The adhesive 112 is made of a material having the same refractive index as that of the cores 106 to 108 or a material having a higher refractive index than the upper and lower cladding layers 105 and 104.

  FIG. 2 is an enlarged view schematically showing a portion where the filter 110 is inserted into the filter insertion groove 111 as viewed in the direction of the arrow X in FIG. 1 and viewed from a direction parallel to the longitudinal direction of the filter 110. First, when the width of the optical waveguide region of the filter insertion groove 111 is defined as A, the thickness of the filter is defined as B, and the width of the substrate region of the filter insertion groove 111 is defined as C, the filter insertion groove 111 is defined as the substrate region of the filter insertion groove 111. The width A of the optical waveguide region of the filter insertion groove 111 is formed larger than the width C. The width A of the optical waveguide region of the filter insertion groove 111 may be 1 to 20 μm larger than the width C of the substrate region. However, if it is too large, the optical loss increases, so it is desirable that it be 1 to 10 μm larger. Further, the width C of the substrate region of the filter insertion groove 111 is formed to be about 1 μm larger than the thickness B of the filter.

  Therefore, in this optical waveguide module 101, for example, as shown in FIG. 3, when light having a wavelength λ 1 and light having a wavelength λ 2 are incident from an optical fiber to the core 106 and propagated through the core 106, Of the light emitted toward the filter 110, the light having the wavelength λ <b> 1 passes through the filter 110 and enters the core 107, propagates through the core 107, and exits from the end face of the core 107. Of the light emitted from the end face of the core 106 toward the filter 110, the light having the wavelength λ <b> 2 is reflected by the filter 110 and enters the core 108, propagates through the core 108, and exits from the end face of the core 108. . That is, a demultiplexing operation is performed. On the other hand, when light having a wavelength λ 1 is incident on the core 107, the light passes through the filter 110 and enters the core 106, propagates through the core 106, and is emitted from the end face of the core 106. Moreover, although description is abbreviate | omitted, a multiplexing operation | movement can also be carried out as operation | movement contrary to a demultiplexing operation | movement.

  Next, a manufacturing method of the optical waveguide module 101 according to the first embodiment will be described with reference to FIG. Here, a case where a silicon substrate is used as the substrate 102 will be described. First, a silicon substrate 16 is prepared {FIG. 4A}, and a resist layer 10 having a pattern in which a resist corresponding to the groove 111 is opened is formed on the prepared silicon substrate 16 {FIG. 4B}. The resist layer 10 is etched by applying a resist to the entire surface of the silicon substrate 16 by spin coating or the like, then exposing with ultraviolet light through a photomask having a pattern corresponding to the etching groove 111a, immersing in a developing solution. Is obtained. At the same time, an opening pattern 11a corresponding to the etching groove 111a is formed. Next, the silicon substrate 16 is etched from above through the opening pattern 11a of the resist layer 10 by DRIE, and an etching groove 111a having an arbitrary depth (for example, a depth of about 150 μm) to which the opening pattern 11a of the resist layer 10 is transferred. {FIG. 4 (c)}. Thereafter, the resist layer 10 is removed to obtain the substrate 102 in which the etching groove 111a is formed {FIG. 4D}. Next, the lower cladding layer 104 side of the optical waveguide 103 is bonded to the surface side of the substrate 102 where the etching groove 111a is formed with an adhesive or the like {FIG. 4 (e)}. Next, a resist layer 12 having a pattern in which a resist corresponding to the etching groove 111a is opened is formed on the upper clad layer 105 of the optical waveguide 103 using a resist resistant to the etching of the optical waveguide 103 {FIG. 4 (f)}. The resist layer 12 is formed by applying a resist to the entire surface of the upper clad layer 105 by spin coating or the like, then exposing with ultraviolet light through a photomask having a pattern corresponding to the filter insertion groove 111, and immersing and etching in a developer. Can be obtained. At the same time, the opening pattern 11b corresponding to the filter insertion groove 111 is formed. Next, the optical waveguide 103 located on the etching groove 111 a is removed by etching through the opening pattern 11 b of the resist layer 12 to form a through hole 111 b in the optical waveguide 103. A filter insertion groove 111 is formed by the through hole 111b and the etching groove 111a. Thereafter, the resist layer 12 is removed {FIG. 4 (g), (h)}. When the adhesive when the substrate 102 and the optical waveguide 103 are bonded flows into the etching groove 111a, the adhesive is also removed. Next, the filter 110 is inserted into the filter insertion groove 111 {FIG. 4 (i)}. Finally, when the filter insertion groove 111 is filled with the adhesive 112 and cured to fix the filter 110, the optical waveguide module 101 is completed {FIG. 4 (j)}.

DRIE (Deep Reactive Ion Etching) in the step {FIG. 4 (c)} of etching the silicon substrate 16 to form the etching groove 111a is anisotropic deep etching, and reactive ion etching (RIE). This is a technique of deep etching (high aspect ratio) using Etching. Various etching gases can be used as long as they do not attack the resist layer 10. For example, if SF ₆ or the like is used as an etching gas, the silicon substrate 16 can be etched at an etching rate of about 2 μm / min.

  As an etching method of the optical waveguide 103 etching step {FIGS. 4F to 4H}, the most suitable method from dry etching or wet etching can be used. For example, when dry etching using oxygen gas is applied to a resin optical waveguide, etching can be performed at an etching rate of about 0.5 μm / min. Also, the resist layer 12 may be an appropriate resist material that is resistant to each etching method. Further, instead of the etching process of the optical waveguide 103, a portion corresponding to the etching groove 111a of the optical waveguide 113 may be removed using a dicing blade.

  Further, when the optical waveguide 103 is formed of a glass-based material, an anodic bonding method can be used for the bonding process {FIG. 4E) between the substrate 102 and the optical waveguide 103. In this case, since no adhesive is used, an adhesive removing step is not necessary.

  Further, the width A of the filter insertion groove 111 formed on the optical waveguide 103 side and the width C of the filter insertion groove 111 formed on the substrate 102 side may be the same size, but the filter insertion groove formed on the optical waveguide 103 side. If the width A of 111 is formed to be about 1 to 20 μm larger than the width C of the filter insertion groove 111 formed on the substrate 102 side, the filter 110 can be easily inserted into the filter insertion groove 111. However, if it is too large, the optical loss increases, so it is desirable that it be 1 to 10 μm larger. Further, in the process of filling and curing the adhesive 112 in the filter insertion groove 111, there is an effect that the adhesive 112 can be easily poured.

  Therefore, if the method for manufacturing an optical waveguide module described in the first embodiment is used, the silicon substrate 16 and the optical waveguide 103 may be etched independently, and the optical waveguide 103 is etched when the silicon substrate 16 is etched. There is no. That is, the silicon substrate 16 and the optical waveguide 103 are etched by an optimum method and conditions, respectively, and are hardly affected by the mutual etching. Therefore, it is possible to form the filter insertion groove 111 with high width accuracy that can suppress the inclination of the filter.

  In the method of manufacturing the optical waveguide module 101 shown in Example 1 of the present invention, in the step {FIG. 4 (e)} of bonding the substrate 102 and the optical waveguide 103, the adhesive flows into the etching groove 111a, and etching is performed. It may be difficult to remove the adhesive that has flowed into the groove 111a. Therefore, Example 2 of the present invention proposes a method of manufacturing the optical waveguide module 101 in which the adhesive does not flow into the etching groove 111a. A method for manufacturing the optical waveguide module 101 according to the second embodiment of the present invention will be described with reference to FIG. It should be noted that the same steps as those in the first embodiment will be omitted and will be described with a focus on differences from the first embodiment.

  First, an etching groove 111a is formed in the silicon substrate 16 by DRIE as in the first embodiment {FIGS. 5A to 5D}. Next, the etching groove 111a is filled with the water-soluble resin 15 and cured or semi-cured so that the surface becomes flat {FIG. 5 (e)}. Next, an adhesive is applied to the lower cladding layer 104 side of the optical waveguide 103 and adhered to the surface side of the substrate 102 where the etching groove 111a is formed {FIG. 5 (f)}. Next, a resist layer 12 having a pattern in which a resist corresponding to the etching groove 111a is opened is formed on the upper cladding layer 105 of the optical waveguide 103 using a resist resistant to etching of the optical waveguide 103 {FIG. (G)}. Subsequently, the optical waveguide 103 is etched to form a through hole 11b {FIG. 5 (h)}. Further, after removing the resist layer 12, if the water-soluble resin 15 filled in the etching groove 111a is removed by washing or the like, the filter insertion groove 111 is completed by the through hole 111b and the etching groove 111a {FIG. 5 (i)}. . Next, the optical waveguide module 101 having the filter insertion groove 111 is obtained by inserting the filter 110 into the filter insertion groove 111, filling and curing the adhesive 112, and fixing the filter 110 {FIG. 5 (j), (K)}.

  In the step {FIG. 5 (h)} in which the optical waveguide 113 is etched to form the through hole 111b, when the etching groove 111a is formed by a method using water such as wet etching or wet dicing, etching is performed. Since the water-soluble resin 15 filled in the groove 111a can be removed simultaneously, the number of steps can be reduced.

  Thus, if the etching groove 11 is filled with the water-soluble resin 15 before the optical waveguide 103 is bonded to the substrate 102, the adhesive may flow into the etching groove 11 when the substrate 102 and the optical waveguide 103 are bonded. In addition, since the water-soluble resin 15 can be easily removed by washing or the like, the production efficiency is improved. The water-soluble resin 15 filling the etching groove 11 may be hardened when cured or may be jelly-like. Any material that reacts with an adhesive or the like for bonding the substrate 102 and the optical waveguide 103 and does not affect the subsequent process may be used.

  Further, the optical waveguide 103 may be formed on the substrate 102 by the method described below. That is, the lower cladding layer 104, the core groove 109, and the cores 106 to 108 are formed on a glass substrate or the like that has been subjected to a peeling treatment in advance. Next, the substrate 102 and the lower cladding layer 104 are opposed to each other through the upper cladding layer 105 before curing. Next, the upper cladding layer 105 is cured, and the substrate 102 and the lower cladding layer 104 are bonded. Thereafter, the glass substrate is peeled off to form the optical waveguide 103 on the substrate 102. In this case, although not particularly illustrated, the optical waveguide 103 is formed on the substrate 102 in a vertically inverted manner with respect to the optical waveguide module 101 shown in FIG.

  Moreover, in the said Example 1 and Example 2, although the board | substrate 102 was demonstrated as a silicon substrate, not only a silicon substrate but a glass substrate, a resin substrate, etc. can also be used, for example.

  In the first and second embodiments, the optical waveguide module 101 in which the filter 110 is inserted into the filter insertion groove 111 has been described as an example of the optical element. However, it is needless to say that the present invention can be applied not only to the filter 110 but also to an optical waveguide module using other optical elements such as a mirror and a Fresnel lens.

  Furthermore, an optical communication apparatus can be manufactured by combining the optical waveguide module 101 shown in Example 1 and Example 2, the light emitting element, the light receiving element, and the optical fiber. For example, the optical transceiver (optical transceiver) 120 shown in FIG. 6 can be manufactured. In this optical transceiver 120, a light emitting element 121 such as a semiconductor laser element that emits light of wavelength λ1 is provided at a position facing the end face of the core 107, and a photodiode or the like is placed at a position facing the end face of the core 108. A light receiving element 122 is provided. An optical fiber (not shown) is connected to the V-groove alignment groove 123 provided on the substrate 102 at a position facing the core 106. Thus, the light of wavelength λ1 emitted from the light emitting element 121 propagates through the core 107, passes through the filter 110, enters the core 106, and is transmitted to the optical fiber. Conversely, the light of wavelength λ 2 transmitted from the optical fiber propagates through the core 106, is reflected by the filter 110, enters the core 108, and is received by the light receiving element 122.

  As described above, according to the present invention, according to the present invention, a filter insertion groove with high width accuracy can be formed. Therefore, it is possible to suppress the inclination of the filter and manufacture an optical waveguide module with little optical loss. it can. Also, optical loss can be reduced in an optical transceiver using these optical waveguide modules. Furthermore, since it is not necessary to form grooves on the quartz glass substrate or silicon substrate with a dicing blade, the amount of wear of the dicing blade can be significantly reduced. Moreover, special processing is not required for optical elements such as filters, and ordinary optical elements can be used.

It is an external appearance perspective view of the optical waveguide module by Example 1 of this invention. It is a X arrow line view of an optical waveguide module same as the above. It is a top view of an optical waveguide module same as the above. (A)-(j) is a figure explaining the manufacturing method of an optical waveguide module same as the above. (A)-(k) is a figure explaining the manufacturing method of the optical waveguide module by Example 2 of this invention. It is the figure which showed the optical transmitter / receiver using the optical waveguide module of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Optical waveguide module 102 Board | substrate 103 Optical waveguide 104 Lower clad layer 105 Upper clad layer 106-108 Core 110 Filter 111 Filter insertion groove 111a Etching groove 111b Through groove 120 Optical transceiver

Claims (7)

In an optical waveguide module comprising an optical waveguide formed on a substrate and an element insertion groove having a depth from the optical waveguide to the substrate,
Forming a groove in the substrate by etching;
Forming the optical waveguide on the substrate after forming the groove;
Forming a through hole in the optical waveguide so as to communicate with the groove;
Inserting an optical element into the element insertion groove formed by the groove and the through hole;
A method for manufacturing an optical waveguide module, comprising: Embedding a filler in the groove before forming an optical waveguide on the substrate;
After the step of forming the through hole in the optical waveguide, removing the filler from the groove;
The manufacturing method of the optical waveguide module of Claim 1 characterized by the above-mentioned. Embedding the filler in the groove before forming an optical waveguide on the substrate;
Forming the through hole in the optical waveguide and removing the filler from the groove;
The manufacturing method of the optical waveguide module of Claim 1 characterized by the above-mentioned.   The method for manufacturing an optical waveguide module according to claim 2, wherein the filler is a water-soluble resin.   2. The method of manufacturing an optical waveguide module according to claim 1, wherein the width of the through hole is processed to be wider than the width of the groove.   An optical waveguide module manufactured by the method for manufacturing an optical waveguide module according to claim 1.   An optical communication device using the optical waveguide module according to claim 6.

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