Patent Publication Number: US-2005141838-A1

Title: Optical waveguide device and manufacturing method thereof

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an optical waveguide device and a manufacturing method thereof. More particularly, the present invention relates to an optical waveguide device and a manufacturing method thereof in which an optical fiber array incorporating an optical fiber is connected to a waveguide via adhesive.  
      2. Description of the Related Art  
      Recent widespread use of optical fiber communication networks has stimulated development of high-performance optical parts. Typically, such optical parts are categorized into three groups: micro-optical parts, optical fiber parts and optical waveguide parts. Among these groups, especially, optical waveguide parts are spotlighted in that they can be suitably mass-produced and easily integrated on substrates. An optical waveguide module is a kind of these optical waveguide parts. An optical waveguide module typically multiplexes incoming light over an optical fiber into a plurality of outgoing rays of light. For example, such an optical waveguide module may be used as branching means for branching light toward individual houses.  
       FIG. 1  is a side view showing a conventional optical waveguide module. In  FIG. 1 , the X-axis direction represents an optical axis direction of a waveguide  148 , and the Z-axis direction represents a direction orthogonal to the X-axis direction.  
      Referring to  FIG. 1 , an optical waveguide module  140  mainly includes an input-side optical fiber array  142 , an optical waveguide device  146  and an output-side optical fiber array  151 .  
      The input-side optical fiber array  142  includes a substrate  143  and a holding layer  144 . The holding layer  144  is formed on the substrate  143 . An input-side optical fiber  141  is provided between the holding layer  144  and the substrate  143 .  
      The output-side optical fiber array  151  includes a substrate  152  and a holding layer  153 . The holding layer  153  is formed on the substrate  152 . A tape fiber  156  is provided between the substrate  152  and the holding layer  153 . The tape fiber  156  is provided with four output optical fibers.  
      The optical waveguide device  146  includes a substrate  147 , a waveguide  148  and a clad layer  149 . The clad layer  149  is formed on the substrate  147 , and the waveguide  148  is formed within the clad layer  149 . In the illustration, the waveguide  148  multiplexes light from the optical fiber  141  into four rays of lights. An end surface  166  of the optical waveguide device  146  is bonded to an end surface  165  of the input-side optical fiber array  142  via adhesive  155 , and thereby the optical fiber  141  can be optically connected to the waveguide  148 .  
      In the optical waveguide module  140 , end surfaces  148 A and  148 B of the waveguide  148  are sloped to have a predetermined slope angle with respect to the direction orthogonal to the optical axis of the waveguide  148 , that is, the Z-axis direction, and are formed as mirror surfaces so as to attenuate reflected light returning to the input side. Thus, the end surfaces  166  and  167  of the optical waveguide device  146 , the end surface  165  of the input-side optical fiber array  142 , and the end surface  168  of the output-side optical fiber array  151  are arranged to have the predetermined slope angle, and are further fabricated as mirror surfaces. For example, such a predetermined slope angle may be 8 degrees.  
      Conventionally, for example, as disclosed in Japanese Laid-Open Patent Application No. 05-273432, the end surfaces  166  and  167  of the optical waveguide device  146  are formed in such a way that a layered member comprised of a substrate  147 , a waveguide  148  and a clad layer  149  is cut with a dicing blade to have perpendicular end surfaces and then end surfaces  166  and  167  are processed with a polisher to have a predetermined slope angle. Through the polishing, the end surfaces  148 A and  148 B of the waveguide  148  are also processed to have the predetermined slope angle.  
      However, since such a polisher is designed for highly accurate surface processing, the processing speed is not so high in general. Thus, it takes much time to process the end surfaces  148 A and  148 B of the waveguide  148 .  
      In addition, a very thin adhesive layer  155  and  157  is provided between the end surface  166  of the conventional optical waveguide device  146  and the end surface  165  of the input-side optical fiber array  142 , and a very thin adhesive layer  157  is provided between the end surface  167  of the waveguide  146  and the end surface  168  of the output-side optical fiber array  151 . Since each of these thin adhesive layers  155  and  157  is a few micrometer in thick, the optical waveguide device  140  is bonded to the input-side and output-side optical fiber arrays  142  and  151  at weak bonding intensity.  
     SUMMARY OF THE INVENTION  
      It is a general object of the present invention to provide an optical waveguide device and a manufacturing method thereof in which one or more of the above-mentioned problems are eliminated.  
      A more specific object of the present invention is to provide an optical waveguide device and a manufacturing method that can improve productivity thereof by shortening processing time of end surfaces of a waveguide and strengthen bonding intensity with optical fiber arrays.  
      In order to achieve the above-mentioned objects, there is provided according to one aspect of the present invention an optical waveguide device, including: an end surface including a substrate, a clad layer on the substrate and a waveguide included in the clad layer, wherein the end surface is connected to an optical fiber array having at least one optical fiber via adhesive, the waveguide has an end surface sloped by a slope angle θ with respect to a direction orthogonal to an optical axis of the waveguide, and the substrate has a notch part on an end surface thereof.  
      According to one aspect of the invention, since the notch part is formed on an end surface of the substrate, the notch part can be filled with a larger amount of adhesive. As a result, it is possible to improve bonding intensity between the optical waveguide device and the optical fiber array.  
      Additionally, there is provided according to another aspect of the invention a method of manufacturing an optical waveguide device including an end surface having a substrate, a clad layer on the substrate and a waveguide included in the clad layer, wherein the end surface is connected to an optical fiber array having at least one optical fiber via adhesive, the waveguide has an end surface sloped by a slope angle θ with respect to a direction orthogonal to an optical axis of the waveguide, and the substrate has a notch part on an end surface thereof, the method including steps of: forming the notch part on the end surface of the substrate by grinding the end surface; and polishing the end surface of the waveguide to have the slope angle θ.  
      According to one aspect of the invention, the notch part is formed on the end surface of the substrate through grinding in shorter processing time than polishing. In this case, when the end surface of the waveguide is polished to have the slope angle θ, a smaller area only has to be polished than conventional methods. As a result, it is possible to shorten processing time required to process the end surface of the waveguide and improve productivity of the optical waveguide device.  
      In an embodiment of the invention, the notch part forming step may use a grinder to form the notch part, and the end surface polishing step may use a polisher to polish the end surface.  
      According to one aspect of the invention, the notch part forming step can be implemented by a grinder, and the polishing step can be implemented by a polisher.  
      In an embodiment of the invention, the method may further include a step of: providing a holding unit holding the optical waveguide device, wherein the grinder has a mounted part to mount the holding unit, the polisher has a mounted part to mount the holding unit, and the holding unit is configured to be attachable to the mounted part of the grinder and the mounted part of the polisher.  
      According to one aspect of the invention, the holding unit to hold the optical waveguide device can be attached alternately between the mounted part of the grinder and the mounted part of the polisher. Thus, when a polishing process starts after a grinding process, it becomes unnecessary to detach the optical waveguide device from the holding unit and then attach the optical waveguide device to a different holding unit of the polisher again. As a result, it is possible to improve productivity of the optical waveguide device.  
      In an embodiment of the invention, the grinder and the polisher may have respective processing members processing the optical waveguide device, and the holding unit may hold the optical waveguide device in such a way that the end surface of the waveguide is sloped by the slope angle θ with respect to the processing members.  
      According to one aspect of the invention, since the holding unit holds the optical waveguide device in such a way that the end surface of the waveguide can be sloped by the slope angle θ with respect to the processing members, it is unnecessary to conduct angle adjustment on the holding unit. As a result, it is possible to shorten processing time associated therewith and improve productivity of the optical waveguide device.  
      Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows an exemplary structure of a conventional optical waveguide module;  
       FIG. 2  schematically shows an exemplary structure of an optical waveguide module according to a first embodiment of the present invention;  
       FIG. 3  is an A directional view of the optical waveguide module shown in  FIG. 2 ;  
       FIG. 4  schematically shows an exemplary structure of an optical waveguide device according to the first embodiment;  
       FIG. 5  is a cross-sectional view showing the optical waveguide device in  FIG. 4  with respect to C-C line;  
       FIG. 6  schematically shows an exemplary structure of an optical waveguide device before processing of an end surface thereof according to the first embodiment;  
       FIG. 7  shows an exemplary structure of a holding unit according to the first embodiment;  
       FIG. 8  shows an exemplary structure of the holding unit under a status where an optical waveguide device is held;  
       FIG. 9  is a view showing the holding unit in  FIG. 8  from D directional viewpoint;  
       FIG. 10  shows an exemplary positional relation before grinding between a grinder and a holding unit having an optical waveguide device according to the first embodiment;  
       FIG. 11  shows an exemplary positional relation during grinding between the grinder and the holding unit in  FIG. 10 ;  
       FIG. 12  shows an exemplary structure of an optical waveguide device having a formed notch part according to the first embodiment;  
       FIG. 13  shows an exemplary structure of a polisher according to the first embodiment;  
       FIG. 14  is a plan view showing an exemplary base plate for mounting a holding unit according to the first embodiment;  
       FIG. 15  is a cross-sectional view showing the base plate in  FIG. 14  with respect to G-G line;  
       FIG. 16  is an enlarged view of a processing area F shown in  FIG. 13 ;  
       FIG. 17  shows an exemplary structure of an optical waveguide device after polishing according to the first embodiment;  
       FIG. 18  shows an exemplary structure of an optical waveguide device having a waveguide both end surfaces of which are polished according to the first embodiment;  
       FIG. 19  shows an exemplary structure of an optical waveguide module according to a second embodiment of the present invention;  
       FIG. 20  schematically shows an exemplary structure of an optical waveguide device according to the second embodiment; and  
       FIG. 21  schematically shows an exemplary structure of a holding unit according to the second embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      In the following, embodiments of the present invention will be described with reference to the accompanying drawings.  
      An optical waveguide module  10  according to a first embodiment of the present invention is described with reference to  FIG. 2  and  FIG. 3 .  FIG. 2  roughly illustrates an exemplary structure of the optical waveguide module  10 .  FIG. 3  is an A-directional view of the optical waveguide module  10  shown in  FIG. 2 . In  FIG. 2 , the X-axis direction represents the optical axis direction of a waveguide  21  of the optical waveguide module  10 , and the Z-axis direction represents a direction orthogonal to the X-axis direction.  
      Referring to  FIG. 2  and  FIG. 3 , the optical waveguide module  10  mainly includes an input-side optical fiber array  12 , an output-side optical fiber array  24  and an optical waveguide device  17 . In the following explanation, as illustrated in  FIG. 2 , if a surface is sloped in the illustration toward the right-hand side with respect to the Z-axis direction, a slope angle θ may be defined to be positive. On the other hand, if a surface is sloped in the illustration toward the left-hand side with respect to the Z-axis direction, the slope angle θ may be defined to be negative.  
      An end surface  12 A of the input-side optical fiber array  12  is adhered on an end surface  17 A of the optical waveguide device  17  with adhesive  31 A, and thereby an optical fiber  11  is connected to a waveguide  21 . On the other hand, an end surface  24 A of the output-side optical fiber array  24  is adhered on an end surface  17 B of the optical waveguide device  17  with adhesive  31 B, and thereby four optical fibers  29  are connected to the waveguide  21 .  
      The input-side optical fiber array  12  is used to lead incoming light from the optical fiber  11  to the waveguide  21 . The input-side optical fiber array  12  includes a substrate  13  and a holding layer  15 . The input-side optical fiber  11  is disposed at a predetermined position between the substrate  13  and the holding layer  15 . Also, the end surface  12 A at the connection side to the optical waveguide device  17  is processed to be a mirror surface. The end surface  12 A is formed to have a slope angle +θ 1 , as illustrated in  FIG. 2 . For example, the slope angle +θ 1  may be +8 degrees. It is noted that the slope angle +θ 1  is set to have the same absolute value as a slope angle −θ 1  of an end surface  34 A described in detail below.  
      The output-side optical fiber array  24  includes a substrate  25  and a holding layer  27 . The four optical fibers  29  are disposed at predetermined positions between the substrate  25  and the holding layer  27 . Also, the end surface  24 A at the connection side to the optical waveguide device  17  is processed to be a mirror surface. The end surface  24 A is formed to have a slope angle −θ 2 , as illustrated in  FIG. 2 . For example, the slope angle −θ 2  may be −8 degrees. It is noted that the slope angle −θ 2  is set to have the same absolute value as a slope angle +θ 2  of an end surface  34 B of a waveguide  21  described in detail below. The output-side optical fiber array  24  is used to guide rays of light multiplexed by the waveguide  21  to the four optical fibers  29 .  
      The optical waveguide device  17  is described with reference to  FIG. 3  through  FIG. 5 .  FIG. 4  roughly shows an exemplary structure of the optical waveguide device  17  according to the first embodiment.  FIG. 5  is a cross-sectional view of the optical waveguide device  17  shown in  FIG. 4  with respect to C-C.  
      Referring to  FIG. 4  and  FIG. 5 , the optical waveguide device  17  mainly includes a substrate  18 , a lower clad layer  19 , a waveguide  21 , an upper clad layer  22  and end surfaces  17 A and  17 B. The lower clad layer  19  is formed on the substrate  18 , and the waveguide  21  is provided on the lower clad layer  19 . As shown in  FIG. 3 , the waveguide  21  multiplexes or branches incoming light from the optical fiber  11  into four rays of light, and supplies the four rays of light to the four optical fibers  29 . The upper clad layer  22  is formed to cover the waveguide  21 .  
      The end surface  17 A is located at the connection side to the input-side optical fiber array  12  via the adhesive  31 A. As shown in  FIG. 4 , the end surface  17 A includes an end surface  32 A of the substrate  18  and an end surface  34 A of the waveguide  21 . A notch part  33 A is formed on the end surface  32 A of the substrate  18 . Also, the end surface  34 A of the waveguide  21  is processed to be a mirror surface, and is arranged to have a slope angle −θ 1  (−8° in this embodiment) with respect to the Z-axis direction (the direction orthogonal to the optical axis of the waveguide  21 ).  
      The end surface  17 B is located at the connection side to the output-side optical fiber array  24  via the adhesive  31 B. As shown in  FIG. 4 , the end surface  17 B includes an end surface  32 B of the substrate  18  and an end surface  34 B of the waveguide  21 . A notch part  33 B is formed on the end surface  32 B of the substrate  18 . Also, the end surface  34 B of the waveguide  21  is processed to be a mirror surface, and is arranged to have a slope angle +θ 2  (+8° in this embodiment) with respect to the Z-axis direction.  
      In this structure where the notch parts  33 A and  33 B are formed on the end surfaces  32 A and  32 B, respectively, of the optical waveguide device  17  as mentioned above, the notch parts  33 A and  33 B can be filled with a more amount of adhesive  31 A and  31 B than in conventional structures. As a result, it is possible to strengthen the bonding intensity between the input-side optical fiber array  12  and the optical waveguide device  17  and between the output-side optical fiber array  24  and the optical waveguide device  17 .  
      An exemplary structure of an optical waveguide device  60  before processing of end surfaces thereof is described with reference to  FIG. 6 .  FIG. 6  roughly shows an exemplary structure of the optical waveguide device  60  before processing of end surfaces thereof. In  FIG. 6 , the same parts as those in  FIG. 4  are designated by the same reference numerals.  
      Referring to  FIG. 6 , the optical waveguide device  60  before processing of end surfaces thereof mainly includes a substrate  18 , a waveguide  21 , a lower clad layer  19 , an upper clad layer  22  and end surfaces  66 A and  66 B oriented orthogonally to the X-axis direction. The end surface  66 A includes an end surface  64 A of the waveguide  21  and an end surface  65 A of the substrate  18 . On the other hand, the end surface  66 B includes an end surface  64 B of the waveguide  21  and an end surface  65 B of the substrate  18 . Thus, the end surfaces  64 A and  64 B of the waveguide  21  before processing thereon are arranged to be oriented orthogonally to the X-axis direction.  
      A holding unit  40  mounted to a grinder  70  (see  FIG. 10 ) and a polisher  90  (see  FIG. 13 ) is described with reference to  FIG. 7  through  FIG. 9 .  FIG. 7  shows an exemplary structure of the holding unit  40  according to the first embodiment. In  FIG. 7 , the Z-axis direction represents a direction orthogonal to a processing surface  54 A of a processing member  54 , and the X-axis direction represents a direction orthogonal to the Z-axis direction.  
      The holding unit  40  is used to keep the optical waveguide device  60 . The holding unit  40  mainly includes a fixing-side member  41 A for fixing a device, a holding-side member  41 B for holding a device and a screw  52 . The fixing-side member  41 A is positioned at the side where the optical waveguide device  60  is fixed to a mounted part  77  (see  FIG. 10 ) of the grinder  70  or a mounted part  182  (see  FIG. 13 ) of the polisher  90 . The fixing-side member  41 A is provided with two convex parts  43 , and a concave part  46  is formed between the two convex parts  43 . Respective holes  44 , through which screws can pierce, are formed in the convex parts  43 . The holding unit  40  is installed by inserting screws through the holes  44  and screwing the mounted part  77  of the grinder  70  or the mounted part  182  of the polisher  90 .  
      The fixing-side member  41 A has a slope surface  49  in contact with an optical waveguide device  60 . The slope surface  49  is formed to have a slope angle +θ 3  (+8° in this embodiment) with respect to the Z-axis direction.  
      The holding-side member  41 B is provided with a slope surface  51  in contact with an optical waveguide device  60 . The slope surface  51  is formed to have a slope angle −θ 3  (−8° in this embodiment) with respect to the Z-axis direction. The slope surface  51  is disposed to face the slope surface  49  in parallel. An area  47  to insert a plurality of optical waveguide devices  60  is formed between the slope surfaces  49  and  51 .  
      The holding-side member  41 B is shifted to sandwich the plurality of optical waveguide devices  60  inserted in the area  47  between the slope surfaces  49  and  51 . The screw  52  is used to fixably shift the holding-side member  41 B to the fixing-side member  41 A. Three screws  52  are used in this embodiment (see  FIG. 9 ). If these three screws  52  are fastened, the holding unit  40  can retain the optical waveguide device  60 . In contrast, if the three screws  52  are loosened, the optical waveguide device  60  can be detached.  
       FIG. 8  shows an exemplary structure of the holding unit  40  under a status where the optical waveguide devices  60  are retained.  FIG. 9  is a view from the D direction of the holding unit  40  shown in  FIG. 8 . As shown in  FIG. 8  and  FIG. 9 , a plurality of (four) optical waveguide devices  60  are retained in the holding unit  40 . Also, as shown in  FIG. 8 , the holding unit  40  retains the optical waveguide devices  60  in such a way that end surfaces  66 A of the optical waveguide devices  60  can be sloped to have a slope angle θ 4  (8°) with respect to the processing surface  54 A of the processing member  54 .  
      If the above-mentioned holding unit  40  is used, the end surfaces  66 A and  66 B can be processed under the status where the optical waveguide device  60  is fixed to the holding unit  40  in common use for the grinder  70  and the polisher  90 . Thus, when polishing is started after grinding, it becomes unnecessary to detach the optical waveguide devices  60  from the holding unit  40  and then reattach the optical waveguide devices  60  to another holding unit dedicated to the polisher  90 . As a result, it is possible to shorten processing time to attach and detach the optical waveguide devices  60  and improve productivity of the optical waveguide devices  60 .  
      In addition, since the end surfaces  64 A and  64 B of the waveguide  21  are retained in the holding unit  40  to have the slope angle θ 4 , it becomes unnecessary to conduct angle adjustment on the holding unit  40  relative to processing members of the grinder  70  and the polisher  90 . As a result, it is possible to accurately process the end surfaces  64 A and  64 B of the waveguide  21  in shorter processing time.  
      An exemplary method of forming a notch part is described with reference to  FIG. 10  through  FIG. 12  by using an example where the grinder  70  is used to form the notch part  32 A on the end surface  65 A.  FIG. 10  shows an exemplary status of the grinder  70  before grinding.  FIG. 11  shows an exemplary status of the grinder  70  during grinding.  FIG. 12  shows an exemplary structure of an optical waveguide device  60  having a formed notch part  32 A.  
      An exemplary structure of the grinder  70  is described with reference to  FIG. 10  and  FIG. 11 . The grinder  70  mainly includes a main shaft  71 , a cup-type grind stone  73  as a processing member, a drive device  74 , a control device  75  and a mounted part  77  to install the holding unit  40 .  
      The main shaft  71  is integrally provided with the cup-type grind stone  73  having a corner part  73 B. A processing surface  73 A of the cup-type grind stone  73  faces one or more optical waveguide devices  60 . The control device  75  controls overall operation of the grinder  70  as well as the drive device  74 .  
      The drive device  74  rotationally shifts the cup-type grind stone by rotationally driving the main shaft  71  so as to grind the end surface  65 A of the substrate  18 . The holding unit  40  holding the optical waveguide device  60  is installed to the mounted part  77  by using the screw  78 . The optical waveguide device  60  is kept in the holding unit  40  in such a way that the substrate  18  can be in contact with the slope surface  49  of the fixing-side member  41 A.  
      When the notch part  33 A is formed by grinding, as illustrated in  FIG. 11 , the corner part  73 B of the grind stone  73  is applied to be in contact with the end surface  65 A of the substrate  18 . As a result, it is possible to form the optical waveguide device  66  having the notch part  33 A, as illustrated in  FIG. 12 , on the end surface  32 A of the substrate  18 . After formation of the notch part  33 A, the holding unit  40  is detached from the mounted part  77  of the grinder  70  and then installed to the mounted part  182  of the polisher  90  (see  FIG. 13 ).  
      An exemplary structure of the polisher  90  to process the end surfaces  64 A and  64 B of the waveguide  21  is described with reference to  FIG. 13 .  FIG. 13  shows an exemplary structure of the polisher  90  during processing. In  FIG. 13 , a processing area F is a contact area between polishing fabric  93  and an optical waveguide device  66 .  
      The polisher  90  includes a main shaft  91 , a platen  92 , a drive device  94 , a control device  96 , a polishing liquid supply part  99  and a base plate  180  for installing the holding unit  40 . The platen  92  has almost round shape and is provided integrally with the main shaft  91 . The polishing fabric  93 , which works as a processing member, is disposed on the upper surface of the platen  92 .  
      The polishing liquid supply part  99  is provided above the polishing fabric  93 . The polishing liquid supply part  99  supplies polishing liquid  101  to the polishing fabric  93 . The control device  96  controls overall operation of the polishing device  90  as well as the drive device  94 . The drive device  94  rotationally drives the main shaft  91 . When the main shaft  91  rotates, the platen  92  also rotates integrally with the main shaft  91 , and thereby it is possible to process the end surface  64 A of the waveguide  21  under a status that the end surface  64 A remains in contact with the polishing fabric  93 .  
      Since the polisher  90  is configured as a high-precision processing device capable of performing mirror surface treatment, the processing of the polisher  90  is considerably slow relative to that of the grinder  70 . The polishing fabric  93  may be, for example, silk, foamed polyurethane, urethane nonwoven, and urethane suede fabric. The polishing liquid  101  may be liquid in which silica, alumina, ceria and others, particle diameter of which is less than  1  μm, are dispersed. In another embodiment, instead of the polishing fabric  93 , a fixed platen, in which diamond particles having particle diameter of 0.5 to 3 μm are scattered, may be used.  
      The base plate  180  for installing the holding unit  40  is described with reference to  FIG. 13  through  FIG. 15 .  FIG. 14  is a plan view of an exemplary structure of the base plate  180 .  FIG. 15  is a cross-sectional view of the base plate  180  shown in  FIG. 14  with respect to G-G.  
      Referring to  FIG. 14  and  FIG. 15 , the base plate  180  mainly includes a base body  181  and a mounted part  182 .  
      The base body  181  has almost square shape. The mounted part  182  is integrally formed at four side-surface parts of the base body  181 . The mounted part  182  is for mounting the holding unit  40 .  
      Three screw locking parts  184  to lock screws  98  are formed in the mounted part  182 . These screw locking parts  184  may be formed as female screws. The holding unit  40  can be attached to the base plate  180  by locking the screws  98  piercing through the holes  44  to the screw locking parts  184 . A round modifying ring  200  is provided at the external circumferential part of the holding unit  40 .  
      A polishing method according to this embodiment is described with reference to  FIG. 16  through  FIG. 18  by using a case where the end surface  64 A of the waveguide  21  is polished.  FIG. 16  is an enlarged view showing the processing area F enclosed by the dot line in  FIG. 13 .  FIG. 17  shows an exemplary structure of an optical waveguide device after polishing. In  FIG. 16 , an area H must be polished in accordance with either of conventional methods or this method. An area I must be polished in accordance with any of conventional methods.  
      As illustrated in  FIG. 16 , the optical waveguide device  66  is held in the holding unit  40  in such a way that the end surface  64 A of the waveguide  21  can be arranged to have a slope angle θ 5  (8° in this embodiment) with respect to the processing surface  93 A of the polishing fabric  93 . Since the notch part  33 A is formed in the optical waveguide device  66 , the substrate  18  is not in contact with the polishing fabric  93  located around the notch part  33 A (area corresponding to the area I) during polishing. Thus, it is unnecessary to polish the notch part  33 A of the substrate  18 . For this reason, only an area corresponding to the area H has to be polished. As a result, it is possible to form an optical waveguide device  79  having an end surface  34 A sloped to have a slope angle −θ 1 , as illustrated in  FIG. 17 , by polishing a smaller area with less processing time.  
       FIG. 18  shows an exemplary structure of an optical waveguide device  17  in which both end surfaces of a waveguide are polished. Also, in case of processing the other end surfaces  64 B of the waveguide  21  so as to have the slope angle +θ 2 , as illustrated in  FIG. 18 , after the notch part  33 B is formed on the end surface  65 B of the substrate  18  in accordance with the same method as the above-mentioned grinding method, it is possible to manufacture the optical waveguide device  17  having the end surfaces  34 B sloped to have the slope angle +θ 2  in accordance with the same method as the above-mentioned polishing method.  
      According to the first embodiment, after the holding unit  40 , to which the above-mentioned grinder  70  and polisher  90  can be installed, is used to form the notch parts  33 A and  33 B on end surfaces of the substrate  18  by grinding, the polisher  90  is used to polish the end surfaces  64 A and  64 B of the waveguide  21 . Thus, it is possible to shorten time to attach and detach an optical waveguide device to/from the holding unit  40  and processing time for the end surfaces  64 A and  64 B of the waveguide  21 . As a result, it is possible to improve productivity of the optical waveguide device  17 . Specifically, this embodiment can process the end surfaces  64 A and  64 B of the waveguide  21  for about half processing time of that required by conventional methods.  
      An optical waveguide module  110  according to a second embodiment of the present invention is described with reference to  FIG. 19  and  FIG. 20 .  FIG. 19  roughly shows an exemplary structure of the optical waveguide module  110 .  FIG. 20  roughly shows an exemplary structure of an optical waveguide device according to the second embodiment. In  FIG. 19  and  FIG. 20 , the same components as those of the optical waveguide module  10  shown in  FIG. 2  are designated by the same reference numerals, and the description thereof is omitted. Also, in the following, if a surface is sloped in the illustration toward the right-hand side with respect to the Z-axis by a slope angle θ, it is said that the surface is sloped to have the slope angle +θ. On the other hand, it a surface is sloped in the illustration toward the left-hand side with respect to the Z-axis by a slope angle θ, it is said that the surface is sloped to have the slope angle −θ.  
      Referring to  FIG. 19  and  FIG. 20 , the optical waveguide module  110  mainly includes an input-side optical fiber array  111 , an output-side optical fiber array  113  and an optical waveguide device  112 . An end surface  111 A of the input-side optical fiber array  111  is adhered to an end surface  112 A of the optical waveguide device  112  via adhesive  31 A, and thereby an input-side optical fiber  11  can be connected to a waveguide  21 . On the other hand, an end surface  113 A of the output-side optical fiber array  113  is adhered to an end surface  112 B of the optical waveguide device  112  via adhesive  31 B, and thereby four output-side optical fibers  29  can be connected to the waveguide  21 .  
      The input-side optical fiber array  111  includes a substrate  13 , a holding layer  15  and an end surface  11 A. The input-side optical fiber  11  is provided at a predetermined position between the substrate  13  and the holding layer  15 . The end surface  111 A is connected to the optical waveguide device  112 . The end surface  111 A is processed to be a mirror surface, and is arranged to have a slope angle +θ 6  with respect to the Z-axis direction. For example, the slope angle +θ 6  may be +8 degrees.  
      The output-side optical fiber array  113  includes a substrate  25 , a holding layer  27  and an end surface  113 A. The four optical fibers  29  are provided at predetermined positions between the substrate  25  and the holding layer  27 . The end surface  113 A is connected to the optical waveguide device  112 . The end surface  113 A is processed to be a mirror surface, and is arranged to have a slope angle −θ 7  with respect to the Z-axis direction. For example, the slope angle −θ 7  may be −8 degrees.  
      The optical waveguide device  112  according to the second embodiment is described. The optical waveguide device  112  mainly includes a substrate  18 , a lower clad layer  19 , a waveguide  21 , an upper clad layer  22  and end surfaces  112 A and  112 B.  
      The end surface  112 A is connected to the input-side optical fiber array  111 . As shown in  FIG. 20 , the end surface  112 A includes an end surface  115 A of the substrate  18  and an end surface  114 A of the waveguide  21 . A notch part  117 A is formed on the end surface  115 A of the substrate  18 . Also, the end surface  114 A of the waveguide  21  is processed to be a mirror surface, and is arranged to have a slope angle −θ 6  (−8°) with respect to the Z-axis direction.  
      The end surface  112 B is connected to the output-side optical fiber array  113 . The end surface  112 B includes an end surface  115 B of the substrate  18  and an end surface  114 B of the waveguide  21 . A notch part  117 B is formed on the end surface  115 B of the substrate  18 . Also, the end surface  114 B of the waveguide  21  is processed to be a mirror surface, and is arranged to have a slope angle +θ 7  (+8°) with respect to the Z-axis direction.  
      A holding unit  120  according to thee second embodiment is described with reference to  FIG. 21 .  FIG. 21  roughly shows an exemplary structure of the holding unit  120 . In  FIG. 21 , the same components as those of the holding unit  40  shown in  FIG. 8  are designated by the same reference numerals.  
      The holding unit  120  keeps an optical waveguide device  60  to be processed. The holding unit  120  mainly includes a fixing-side member  121 A, a holding-side member  121 B and a screw  52 . The fixing-side member  121 A may be located at the side fixed to a mounted part  77  of a grinder  70  (see  FIG. 10 ) or a mounted part  182  of a polisher  90  (see  FIG. 13 ). The fixing-side member  121 A is provided with two convex parts  43 , a concave part  46 , holes  44  and a slope surface  123 . The slope surface  123  is formed to have a slope angle +θ 8  (+8°) with respect to the Z-axis direction. When the optical waveguide device  60  is held, the slope surface  123  is in contact with the optical waveguide device  60 . In this embodiment, the optical waveguide device  60  is retained in the holding unit  120  in such a way that the substrate  18  can remain in contact with the slope surface  123 .  
      The holding-side member  121 B is provided with a slope surface  125  in contact with the optical waveguide device  60 . The slope surface  125  is formed to have a slope angle −θ 9  (−8°) with respect to the Z-axis direction. The slope surface  125  is positioned to face the slope surface  123  in parallel.  
      An area  47  to insert a plurality of optical waveguide devices  60  is formed between the slope surfaces  123  and  125 . The plurality of optical waveguide devices  60  inserted in the area  47  are held via the slope surface  125  of the holding-side member  121 B. The holding unit  120  holds the optical waveguide devices  60  in such a way that end surfaces of the optical waveguide devices  60  can be oriented at a slope angle θ 10  with respect to the X-axis direction. The three screws  52  are used to fix the holding-side member  121 B toward the fixing-side member  121 A.  
      After the holding unit  120  is used to form notch parts  117 A and  117 B on the substrate  18  by grinding, the end surfaces  64 A and  64 B of the waveguide  21  are polished. As a result, since end surfaces  114 A and  114 B of the waveguide  21  can be formed as sloped mirror surfaces in shorter processing time than that any of conventional methods, it is possible to improve productivity of the optical waveguide device  112 . It is noted that also in the second embodiment, the grinder  70  and the polisher  90  can be used to manufacture the optical waveguide device  112  in the same way as the first embodiment.  
      Although the first and second embodiments have been described for the purpose of explaining the present invention, the present invention is not limited to these embodiments. For example, the present invention simply requires that a notch part be formed in an end surface of a substrate before polishing and then an end surface of a waveguide be polished, and the present invention is not limited to the slope angles and shape of end surfaces shown in the first and second embodiments. Also, although the case of processing an end surface of a waveguide provided in an optical waveguide device has been described in the first and second embodiments, an end surface of an optical fiber array or an optical fiber may be processed in accordance with the above-mentioned grinding and polishing method.  
      The present invention is not limited to the specifically disclosed embodiments, and variations and modifications may be made without departing from the scope of the present invention.  
      The present application is based on Japanese Patent Priority Application No. 2003-435196 filed Dec. 26, 2003, the entire contents of which are hereby incorporated by reference.