JP2005258051A - Optical fiber array and substrate for optical fiber array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber array which prevents breakage of optical fibers and stress concentration and has a high optical fiber adhesion reliability, and a substrate for the optical fiber array. <P>SOLUTION: V grooves 26 in which naked parts 41 of optical fibers 4 will be placed and positioned are formed on the side of a step surface 23 formed between a V groove formation part 21 having the V grooves 26 formed therein and a plane part 22 having coating parts 42 of optical fibers 4 placed and fixed thereon so that an opening angle θ of the V grooves 26α is gradually widened and the surface roughness of inside wall surfaces of the V grooves 26α is equal to a maximum height Rz≤0.1 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical fiber array and an optical fiber array substrate, and more particularly, an optical fiber array used for positioning and fixing an optical fiber and connecting the optical fiber to another optical device and the like, and the optical fiber. The present invention relates to an optical fiber array substrate that can be suitably used as an array.

  For example, an optical fiber array is used as a component for connecting between optical fibers or between optical fibers and other optical devices.

  8A and 8B are external perspective views showing a conventional general optical fiber array 101. FIG. 8A shows a state before assembly, and FIG. 8B shows a state after assembly. The conventional general optical fiber array 101 includes a substrate 102 on which the optical fiber 104 is placed, and a pressing lid 103 that is attached to the substrate 102 on which the optical fiber 104 is placed. The substrate 102 has a flat planar portion 122 and a V-groove forming portion 121 that extends from the planar portion 122 and has a height dimension and is formed in a plateau shape. A step surface 123 is formed at the boundary with the portion 121. On the upper surface 125 of the V-groove forming portion 121, a plurality of grooves 126 having a V-shaped cross section from the end surface 124 (the surface on the back side invisible in FIG. 8) of the substrate 102 to the step surface 123 are formed in parallel. The

  Then, the coating material in the vicinity of the tip of the optical fiber 104 is removed to expose the bare optical fiber 141. This bare portion is placed in alignment in the groove 126 having a V-shaped cross section, and the pressing lid 103 is covered from above. The optical fiber 104 is positioned by pressing it. As a result, the optical fiber 104 is positioned at two points on the inner wall surface of the groove 126 having a V-shaped cross section and three points on the lower surface of the pressing lid 103. Thereafter, a gap formed between the optical fiber 104, the groove 126 having a V-shaped section and the pressing lid 103 from the opening of the groove 126 having a V-shaped section appearing on the stepped surface 123 or the end surface 124 of the substrate 102. Inject adhesive. The adhesive enters and fills this gap by capillary action, and fixes the optical fiber 104, the substrate 102, and the pressing lid 103 together.

  Further, after this, an adhesive is also applied to the portion 142 covered with the coating material of the optical fiber 104 extending from the V groove forming portion 121 to the flat surface portion 122 so as to include the vicinity of the tip of the portion 142 covered with the coating material of the optical fiber 104. The optical fiber 104 is fixed and protected by coating or the like.

  In such a configuration, stress concentration occurs due to the shrinkage of the adhesive or the like on the step surface 123 between the groove forming portion 121 and the flat surface portion 122, resulting in an increase in loss. Further, since the optical fiber 104 is in contact with the edge 129 of the stepped surface 123, the optical fiber 104 is likely to be damaged and may be disconnected.

  In order to prevent an increase in the loss or damage of the optical fiber on the step surface of the substrate, for example, a configuration is proposed in which the step surface is formed into a convexly curved shape (see Patent Document 1). And this patent document 1 is disclosing the structure formed in R shape as an example of a specific shape. According to the configuration disclosed in Patent Document 1, the stress applied to the optical fiber gradually changes on the step surface, so that stress concentration can be reduced. Further, when the optical fiber moves up, down, left and right, the stress fulcrum moves, so that stress concentration can be alleviated. Further, by relaxing the stress concentration on the optical fiber, it is possible to prevent an increase in loss and damage.

  However, in the configuration described in Patent Document 1, the configuration in which the optical fiber is in contact with the edge of the stepped surface of the substrate is the same as the conventional one. For this reason, there is a risk of damaging the optical fiber during assembly of the optical fiber array. In addition, even after assembly, if the thermal expansion coefficients of the optical fiber and the adhesive are different, the optical fiber may move due to a temperature change and may be damaged at the edge of the step surface.

  In this configuration, the adhesive is infiltrated into the gap between the substrate, the presser lid, and the optical fiber using capillary action. However, since the cross-sectional area of the gap is small, the adhesive force decreases when bubbles or the like are mixed. There is also a risk that the substrate peels off.

  Furthermore, no consideration is given to the surface properties of the contact surface with the optical fiber, such as the inner wall surface of the V groove of the substrate and the holding lid, and the surface of the optical fiber may be damaged depending on the surface properties. There is also a fear.

JP 2000-275478 A

  In view of the above situation, the problem to be solved by the present invention is that the optical fiber does not contact the edge of the substrate or the pressing lid, and the surface of the optical fiber can be prevented from being damaged, or the stress concentration at the step portion of the substrate. To prevent damage to the optical fiber by preventing the damage to the optical fiber, or to improve the adhesion so that no bubbles are generated in the gap filled with the adhesive, or to prevent scratches on the contact surface between the optical fiber and the substrate or the holding lid It is to provide an optical fiber array and a substrate for the optical fiber array.

  In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a V-groove substrate in which a V-groove portion having a plurality of V-grooves to which an optical fiber is mounted extends from a flat surface via a step surface, The surface of the contact surface between the V-groove substrate and / or the optical fiber of the fiber pressing lid is a maximum height Rz. In other words, it is 0.1 μm or less.

  Here, as in the invention described in claim 2, it is preferable that the opening angle of the V-groove formed in the V-groove substrate gradually widens toward the plane portion side.

  Further, as in the invention described in claim 3, the depth of the V-groove formed in the V-groove substrate may be gradually increased toward the plane portion side.

  According to a fourth aspect of the present invention, there is provided an optical fiber array substrate in which a V-groove portion having a plurality of V-grooves to which optical fibers are mounted is formed extending from a flat surface via a step surface. The gist of the present invention is that the surface roughness of the contact surface of the V-groove substrate with the optical fiber of the V-groove substrate is 0.1 μm or less at the maximum height Rz.

  Here, as in the invention described in claim 5, it is preferable that the opening angle of the V-groove formed in the V-groove substrate gradually widens toward the plane portion side.

  Furthermore, as described in claim 6, it is preferable to have a portion where the opening angle of the V-groove formed in the V-groove substrate is constant.

  In the fourth aspect of the invention, as described in the seventh aspect of the invention, it is preferable that the depth of the V-groove formed in the V-groove substrate is gradually increased toward the flat portion side.

  Furthermore, as described in claim 8, it is preferable to have a portion where the depth of the V-groove formed in the V-groove substrate is constant.

  The invention according to claim 9 is characterized in that, in the inventions according to claims 4 to 8, the optical fiber array substrate is formed by a glass mold.

  According to the first aspect of the present invention, since the surface roughness of the surface of the V-groove substrate and the fiber pressing lid that contacts the optical fiber is formed to be 0.1 μm or less at the maximum height Rz, the optical fiber is Even if contact is made, the surface of the optical fiber is hardly damaged. Therefore, damage and disconnection of the optical fiber can be suppressed.

  According to the invention described in claim 2 or claim 3, the optical fiber attached to the V-groove gradually moves away from the surface of the V-groove as it goes to the step surface formed between the V-groove. It will be. For this reason, the stress concentration of the optical fiber on the step surface can be relaxed, and an increase in loss can be suppressed. In addition, since the optical fiber floats from the inner wall surface of the V-groove in the vicinity of the step surface, the surface of the optical fiber is prevented from coming into contact with the edge of the step surface and being damaged. For this reason, the optical fiber is prevented from being damaged or disconnected at the step surface.

  Moreover, in such a structure, the gap formed between the optical fiber, the inner wall surface of the V-groove, and the pressing lid has a cross-sectional area that increases toward the step surface side. For this reason, when an adhesive that fixes the optical fiber and the fiber pressing lid is injected into the gap from the stepped surface side, the adhesive easily enters, the generation of bubbles is suppressed, and the adhesive strength is improved.

  According to the fourth aspect of the present invention, the surface roughness of the surface of the V-groove substrate and the fiber pressing lid that contacts the optical fiber is formed to be 0.1 μm or less at the maximum height Rz. When an optical fiber array is assembled using a substrate, the surface of the optical fiber is hardly damaged even if the optical fiber comes into contact. Therefore, damage and disconnection of the optical fiber can be suppressed.

  According to the fifth aspect of the present invention, the optical fiber attached to the V-groove gradually moves away from the surface of the V-groove as it goes to the step surface formed between the flat surface portion. For this reason, the stress concentration of the optical fiber on the step surface can be relaxed, and an increase in loss can be suppressed. In addition, since the optical fiber floats from the inner wall surface of the V-groove in the vicinity of the step surface, the surface of the optical fiber is prevented from coming into contact with the edge of the step surface and being damaged. For this reason, the optical fiber is prevented from being damaged or disconnected at the step surface.

  In such a configuration, the gap formed between the optical fiber, the inner wall surface of the V-groove, and the pressing lid increases in cross-sectional area toward the step surface side. For this reason, when an adhesive that fixes the optical fiber and the fiber pressing lid is injected into the gap from the stepped surface side, the adhesive easily enters, the generation of bubbles is suppressed, and the adhesive strength is improved.

  Here, as described in claim 6, when the opening angle of the V groove formed in the V groove substrate has a constant part, the optical fiber can be positioned in this part. For this reason, even if it changes the opening angle of V groove | channel other than this part, the effect of the invention of Claim 5 can be show | played, without deteriorating the positioning accuracy of an optical fiber.

  According to the seventh aspect of the invention, the same effect as that of the fifth aspect of the invention can be obtained. In this case, as described in claim 8, if there is a portion where the depth of the V-groove is constant, the optical fiber can be positioned in this portion, which is the same as in the invention described in claim 6. An effect can be produced.

  When the optical fiber array substrate is formed by a glass mold as described in claim 9, it is easy to form the surface property to be uniform and smooth and to have a surface roughness of 0.1 μm or less at the maximum height Rz. Become. In addition, once the mold is manufactured, productivity can be improved, and manufacturing is easier compared to grinding and the like.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic external view showing a schematic structure of an optical fiber array according to the first embodiment. FIG. 1 (a) is a perspective view showing a state before assembly, and FIG. 1 (b) is after assembly. It is the perspective view which showed the state.

  The optical fiber array 1α according to the first embodiment includes a substrate 2α on which the optical fiber 4 is placed, and a pressing lid 3 that covers and covers the substrate 2α from above. Further, the optical fiber 4 to be fixed is used by removing the covering material between a predetermined distance from the end portion and exposing the bare optical fiber 41. The arrow m in the figure indicates the direction in which the bare portion 41 of the optical fiber 4 is placed, and the arrow n indicates the direction in which the holding lid 3 is placed. Hereinafter, in the present specification, the portion of the optical fiber 4 covered with the coating material is referred to as “optical fiber coating portion 42”, and the portion exposed by removing the coating material is referred to as “optical fiber bare portion 41”. Called.

  The substrate 2α includes a flat surface portion 22 formed in a flat plate shape, and a V-groove forming portion 21 extending from the flat surface portion 22 and having a height dimension and formed in a plateau shape. A step surface 23 is formed at the boundary between the V groove forming portion 21 and the V groove forming portion 21. A plurality of V-shaped grooves 26α are formed in parallel on the upper surface 25 of the V-groove forming portion 21 from the end surface 24 of the substrate 2α (referring to the back-side surface not visible in FIG. 1) to the stepped surface 23. Is done. In the present specification, a groove having a V-shaped cross section is abbreviated as “V groove”. The detailed form of the V groove 26α will be described later. In addition, the figure is a schematic diagram and does not show an actual shape dimension. Further, the number of strips of the V-groove 26α is not limited to the six strips shown in the figure, and may be from one to five strips or seven strips or more.

  The pressing lid 3 is a member that is formed in a substantially square plate shape and is placed on the upper surface 25 of the V-groove forming portion 21 of the substrate 2α to cover it. The shape dimension is formed substantially the same as the shape dimension of the V groove forming portion 21 of the substrate 2α. Then, when placed on the upper surface 25 of the V-groove forming portion 21, a surface 32 (a lower surface not visible in FIG. 1, hereinafter referred to as “mounting surface”) facing the upper surface 25 of the V-groove forming portion 21. Of the edges of the side, at least the edge 31 of the side facing the stepped surface 23 of the substrate 2 is formed in a shape with a sharp corner, for example, an arc shape, as shown in the enlarged view.

  The substrate 2α and the presser lid 3 are preferably formed of a material that is the same as or similar to that of the optical fiber 4 whose thermal expansion coefficient is fixed. Specifically, for example, glass such as quartz glass and Pyrex (registered trademark) glass, or ceramics can be used.

  Further, the surface of the substrate 2α and the pressing lid 3 that contacts at least the optical fiber 4, specifically, the inner wall surface of the V groove 26α of the substrate 1α and the mounting surface 32 of the pressing lid 3 have a surface roughness (maximum height) Rz. Is formed to be 0.1 μm or less. By setting the maximum height Rz to 0.1 μm or less, even if the bare portion 41 of the optical fiber 4 comes into contact with the inner wall surface of the V-groove 26α or the mounting surface 32 of the pressing lid 3, the bare portion 41 of the optical fiber 4 Scratching on the surface can be suppressed. In addition, since the flowability of the adhesive into the gap is improved, the optical fiber array 1α and the optical fiber array substrate 2α with high reliability can be manufactured.

  For this reason, it is preferable that the substrate 2α and the pressing lid 3 are formed by a glass mold. According to the glass mold, the surface texture can be formed uniformly and smoothly, so that the surface roughness Rz is easily formed to 0.1 μm or less. In addition, although a mold cost is required for a glass mold, there is no problem in productivity because the mold only needs to be manufactured once. On the other hand, it is generally manufactured by grinding using a grindstone, but the grinding is a precision machining that requires a high degree of control, and the productivity is not good. Further, in the grinding process, since chipping is likely to occur on the processed surface, the surface of the bare portion 41 of the optical fiber 4 is easily damaged.

Next, the V groove 26α formed in the V groove forming portion 21 will be described. FIG. 2A is a partially enlarged view showing the V groove forming portion 21. In the first embodiment, the opening angle θ of the V groove 26α is formed larger on the step surface 23 side than on the end surface 24 side of the substrate 2α. Specifically, a predetermined distance from the end surface 24 of the substrate 2α, for example, the distance from the end surface 24 of the substrate 2α to the vicinity of the center of the V-groove forming portion 21 is constant, and the V-groove 26α is formed in a straight line. On the other hand, a predetermined distance from the step surface 23 of the substrate 2α, for example, from the step surface 23 to the vicinity of the center of the V-groove forming portion 21, is formed so as to gradually and gradually increase from the vicinity of the center toward the step surface 23. The Reference numeral X _alpha open angle θ indicates a portion that varies in the figure. In the example shown in the figure, the dimension from the upper surface 25 of the V groove forming portion 21 to the groove bottom 28α of the V groove is formed constant over the entire length of the V groove 26α. The positioning of the bare portion 41 of the optical fiber 4 is performed at a portion where the opening angle θ of the V groove 26α is formed constant.

FIG. 2B is a diagram showing a change in the cross-sectional shape along the axial direction of the V-groove 26α. Specifically, the cross-section A is a cross-section taken along the line aa and the cross-section B shown in FIG. Indicates the cross-sectional shape of the V groove 26α in each cross section of the cc line cross section, and also shows the position of the bare portion 41 of the optical fiber 4. As shown in the figure, the magnitude relationship of the opening angle θ of the V-groove 26α at each cross-sectional line is as follows: (opening angle θ _{A of} cross-section _A ) <(opening angle θ _{B of} cross-section _B ) <(opening angle θ of cross-section C) _C ).

In such a form, if the depth dimension is constant over the entire length of the V-groove 26α from the upper surface 25 to the groove bottom 28α of the V-groove forming portion 21, the optical fiber 4 (the bare portion 41 of the optical fiber 4) When the arrangement pitch is small and the apex 27α of the V-groove 26α is sharp, the apex 27α of the V-groove 26α gradually decreases as the opening angle θ of the V-groove 26α increases. Then, the height dimension I from the top portion 27α to the groove bottom 28α decreases in the order of I _A , I _B , and I _C , and the height of the top portion 27α and the groove bottom 28α approaches and the V groove 26α becomes shallow. . On the other hand, large arrangement pitch of the optical fibers 4 (bare portion 41 of optical fiber 4) is, when the top 27α of V grooves 26α is flat, as shown in the partial X _alpha to the opening angle θ is changed, the V-groove The flat portion between 26α (that is, the upper surface 25 of the V groove forming portion 21) gradually becomes narrower toward the step surface 23.

  The assembling operation of the optical fiber array 1α having such a configuration is as follows. 3A and 3B are partial cross-sectional views of the assembled optical fiber array 1α, where FIG. 3A is a cross-sectional view cut at right angles to the axial direction of the optical fiber 4, and FIG. 3B is cut parallel to the axial direction of the optical fiber 4. FIG.

  First, the bare portion 41 of the optical fiber 4 is placed on the V-groove 26, and the covering portion 42 of the optical fiber 4 is placed on the flat portion 22. Then, the pressing lid 3 is placed from above the bare portion 41 of the optical fiber 4 to position the optical fiber 4. When the covered cover 3 is pressed in the direction of the arrow q, the outer peripheral surface of the bare portion 41 of the optical fiber 4 is a total of three points (two points on the inner wall surface of the V groove 26α and one point on the mounting surface 32 of the cover 3) ( Actually, it is positioned in contact with a line, not a point.

  With the bare portion 41 of the optical fiber 4 positioned, the adhesive 5 is injected from the step surface 23 of the substrate 2α. The injected adhesive 5 enters and fills a gap formed between the bare portion 41 of the optical fiber 4, the inner wall surface of the V groove 26 α and the mounting surface 32 of the pressing lid 3 by capillary action. When the adhesive is solidified, the bare portion 41 of the optical fiber 4, the substrate 2α, and the pressing lid 3 are integrated. At the time of the assembly operation, the pressing lid 3 is lightly pressed to such an extent that the bare portion 41 of the optical fiber 4 can be positioned, and is released from the pressing force after being bonded and integrated by the adhesive 5.

  As an adhesive filling the gap, for example, an ultraviolet curable epoxy resin adhesive having a viscosity before curing of about 2.0 Pa · s can be applied.

  After the bare portion 41 of the optical fiber 4 accommodated in the V-groove 26α is fixed by the adhesive 5, an adhesive is applied to the covering portion 42 of the optical fiber 4 so that the covering portion 42 of the optical fiber 4 is attached to the substrate 2α. Secure to.

  As is apparent from FIG. 3, when the V groove 26α is formed in such a shape, the bare portion 41 of the optical fiber 4 becomes closer to the step surface 23 from the vicinity of the center of the V groove forming portion 21. Gradually away from the inner wall surface, the stepped surface 23 floats from the inner wall surface of the V-groove 26α. Further, by forming the edge on the stepped surface 23 side of the mounting surface 32 of the presser lid 3 in an arc shape, the bare portion 41 of the optical fiber 4 does not come into contact with the edge of the end of the presser lid 3. For this reason, even if the bare portion 41 of the optical fiber 4 is moved up and down and left and right due to the expansion and contraction of the adhesive due to the temperature change or the assembling operation, the surface of the bare portion 41 of the optical fiber 4 becomes the edge 29 of the step surface There is no contact, and the edge 29 of the step surface 23 can be prevented from being damaged. Further, since the stepped surface 23 changes gently, stress concentration due to the adhesive applied to the coating portion 42 of the optical fiber 4 can be reduced, and an increase in loss can be prevented.

  The bare portion 41 of the optical fiber 4 is positioned at a portion where the opening angle θ of the V groove 26α is formed constant.

  Further, since the opening area of the gap in the step surface 23 is large and the cross-sectional area gradually decreases toward the end surface 24 of the substrate 2α, the adhesive easily enters from the step surface 23. For this reason, by allowing the adhesive 5 to enter from the side of the step surface 23 toward the end surface 24 of the substrate 2 by capillary action, the adhesive can be smoothly filled without generating bubbles in the gap, and the adhesive strength Can be prevented.

  Furthermore, by setting the surface roughness Rz of the inner wall surface of the V-groove 26α and the mounting surface of the presser lid 3 to 0.1 μm or less, it is possible to prevent the optical fiber from being damaged on the mounting surface of the optical fiber.

  Next, a second embodiment of the present invention will be described. FIG. 4 is a diagram showing the configuration of the V-groove forming portion of the optical fiber array substrate according to the second embodiment. The optical fiber array 1β and the optical fiber array substrate 2β according to the second embodiment are different from the optical fiber array and the optical fiber array substrate according to the first embodiment in the form of a V-groove forming portion. Only the difference is made, and the others have substantially the same configuration. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

FIG. 4A is a partial perspective view of the V-groove forming portion 21 of the substrate 2β according to the second embodiment. As shown in this figure, the depth dimension from the upper surface 25 of the V-groove forming portion 21 to the groove bottom 28β of the V-groove 26β is deeper on the side of the step surface 23 than on the end surface 24 side of the substrate 2β. . In the example shown in FIG. 4, the opening angle θ of the V groove 26β is constant over the axial direction, and the depth dimension from the upper surface 25 of the V groove forming portion 21 to the groove bottom 28β is gradually increased. Specifically, a predetermined distance from the end surface of the substrate 2β, for example, the distance from the end surface of the substrate 2β to the vicinity of the center of the V-groove forming portion 21 is constant, and the V-groove 26β is formed linearly. On the other hand, the portion from the vicinity of the center of the V-groove forming portion 21 to the step surface 23 is formed so as to gradually and smoothly become deeper toward the step surface 23 side. Code X _beta in Figure 4 shows a portion where a change in the depth position of the groove bottom 26Beta.

  The bare portion 41 of the optical fiber 4 is positioned at a portion where the depth from the upper surface 25 of the V groove forming portion 21 to the groove bottom 28β of the V groove 26β is formed constant.

In such a configuration, when the arrangement pitch of the optical fibers 4 is small and the top portion 27β of the V-groove 26β has a sharp shape, as it goes toward the stepped surface 23 (in other words, from the upper surface 25 to the groove bottom 28β). As the depth dimension increases, the height of the top portion 27β gradually decreases from the upper surface 25 of the V-groove forming portion 21. However, the depth dimension from the top 27β to the groove bottom 28β remains substantially constant, and the cross-sectional area of the V-groove 26β is also substantially constant. On the other hand, large arrangement pitch of the bare portion 41 of optical fiber 4, if the apex 27β is flat, as shown in the partial X _beta depth of the V groove 26β changes, the flat portion of the top (i.e. V The width of the upper surface 25) of the groove forming portion 21 is gradually narrowed toward the step surface 23 side.

FIG. 4B is a cross-sectional view schematically showing changes in the cross-sectional shape of the V-groove along the axial direction of the optical fiber. Each cross-section D is a cross-section taken along the line dd in FIG. Similarly, a cross section taken along the line ee, and a cross section F shows the position and cross sectional shape of the V groove 26β in the cross section taken along the line ff, and also shows the position of the bare portion 41 of the optical fiber 4. As shown in FIG. 4B, the opening angle θ of the V groove 26β in each cross sectional line is constant, but the depth H from the upper surface 25 of the V groove forming portion 21 to the groove bottom 28β is (in the cross section D). Depth H _D ) <(depth H _{E in} cross section _E ) <(depth H _F in cross section _F ).

  According to such a configuration, as in the first embodiment, the distance between the inner wall surface of the V groove 26β and the mounting surface 32 of the pressing lid 3 gradually increases toward the stepped surface 23 side. For this reason, the bare portion 41 of the optical fiber 4 is gradually separated from the inner wall surface of the V-groove 26β, and the stepped surface 23 floats from the inner wall surface of the V-groove 26β. Further, by forming the edge of the side of the mounting surface 32 of the pressing lid 3 corresponding to the stepped surface 23 in an arc shape, the bare portion 41 of the optical fiber 4 is not in contact with the edge of the pressing lid 3. For this reason, even if the bare portion 41 of the optical fiber 4 moves up and down and left and right due to the expansion and contraction of the adhesive due to the temperature change and the assembling operation, the surface of the bare portion 41 of the optical fiber 4 becomes the edge 29 of the step surface 23. No contact and scratching is prevented. The positioning of the bare portion 41 of the optical fiber 4 is performed at a linear portion where the depth H of the V groove 26β is constant.

  Further, the cross-sectional area of the gap formed between the bare portion 41 of the optical fiber 4, the inner wall surface of the V-groove 26β, and the mounting surface 32 of the pressing lid 3 has a large opening at the step surface 23, and the end surface of the substrate 2β. Since it gradually decreases toward the side 24, the adhesive easily enters from the stepped surface 23. For this reason, by allowing the adhesive to enter from the stepped surface 23 toward the end surface 24 of the substrate 2β by capillary action, the adhesive can be smoothly filled without generating bubbles in the gap, and the adhesive force is reduced. Can be prevented.

  In addition, since the step surface changes gently as in the conventional technique, stress concentration due to the adhesive applied to the covering portion and the covering portion mounting portion can be alleviated and an increase in loss can be prevented.

  Next, examples of the present invention will be described. FIG. 5A is a micrograph of a V-groove of a substrate according to an embodiment of the present invention produced by a glass mold, and FIG. 5B is a micrograph of an inner wall surface of the V-groove of a substrate produced by grinding. It is. As is apparent from the figure, the surface of the V-groove of the substrate manufactured by grinding has many fine irregularities, and it is considered that the irregularities are easily damaged when the bare portion of the optical fiber comes into contact. On the other hand, the substrate according to the present invention manufactured by a glass mold has a smooth V-groove surface, and is considered to be hardly damaged even when the bare portion of the optical fiber comes into contact.

  6A shows the surface profile of the V-groove of the substrate according to the present invention produced by a glass mold, and FIG. 6B shows the surface profile of the V-groove of the substrate produced by grinding. As is apparent from this figure, the surface roughness (maximum height) Rz of the V groove of the substrate according to the present invention is 0.1 or less. On the other hand, the surface roughness (maximum height) Rz of the inner wall surface of the V groove of the substrate produced by grinding is about 0.5 μm.

  The measurement conditions for these surface profiles are as follows. A stylus type surface texture measuring device (model number: DEKTAK-3030) manufactured by veco Japan was used for the measurement. The stylus is made of diamond and has a tip radius of curvature of 12.5 μm. The measurement distance is 15 μm, and the needle pressure during measurement is 20 mg.

  An experiment for verifying the effect of the present invention was performed using these substrates. FIG. 7 is a schematic diagram showing an outline of an experiment for verifying the effect of the present invention. As shown in the figure, the optical fiber 4 is placed in the V-groove 26 of the substrate 2 and protruded from the step surface 23 by L = 100 mm. Then, the optical fiber 4 is swung left and right once as indicated by the arrow p, and the number of times until the optical fiber 4 is broken is measured. Here, the deflection angle η of the optical fiber 4 was 22.5 deg, and the number of times the optical fiber 4 was shaken was 20 at the maximum.

  Table 1 shows the results of the verification experiment. In order to verify the effect of the V-groove shape and the surface property of the inner wall surface of the V-groove, as a comparative example, a conventional-shaped substrate manufactured by grinding and a conventional-shaped substrate manufactured by a glass mold were used. Each experiment was performed 10 times. In the case of the substrate having the conventional shape manufactured by grinding, the wire was broken on the average 0.6 times, and in the case of the substrate having the conventional shape made by the glass mold, the wire was broken on the average 13.7 times. On the other hand, in the Example of this invention, it did not disconnect within 20 times.

  As described above, the optical fiber is likely to break in the conventional substrate having a large surface roughness Rz formed by grinding. Moreover, in the conventional-shaped board | substrate produced with the glass mold and the surface roughness was made small, the frequency | count to which a disconnection increases, but it does not reach the board | substrate which concerns on this invention. From this, it was confirmed that when the substrate is shaped according to the present invention and the surface roughness Rz of the inner wall surface of the V-groove is 0.1 μm or less, the optical fiber is not easily damaged at the stepped surface of the substrate.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention. For example, it is good also as a structure which combined the said 1st Embodiment and 2nd Embodiment. That is, you may form so that both the opening angle (theta) of V groove and the depth of V groove may become large gradually as it goes to the level | step difference surface side of a V groove formation part. According to such a configuration, although the shape of the V-groove is somewhat complicated, the same effects as those of the first embodiment and the second embodiment can be achieved.

It is the external appearance schematic diagram of the optical fiber array which concerns on 1st Embodiment, (a) is the exploded perspective view which showed the state before an assembly, (b) is the combined perspective view which showed the state after an assembly. It is the figure which showed the structure of the V-groove formation part of the board | substrate for optical fiber arrays which concerns on 1st Embodiment, (a) is the elements on larger scale of a V-groove formation part, (b) is the cross-sectional shape of V-groove It is sectional drawing which showed typically. It is the figure which showed the position state of the optical fiber after an assembly, (a) is sectional drawing which cut | disconnected the V-groove formation part at right angles to the axis line of an optical fiber, (b) is an axial direction of an optical fiber. It is sectional drawing cut | disconnected in parallel with. It is the figure which showed the structure of the V-groove formation part of the board | substrate for optical fiber arrays which concerns on 2nd Embodiment, (a) is the elements on larger scale of a V-groove formation part, (b) is the cross-sectional shape of V-groove It is sectional drawing which showed typically. (A) is the microscope picture of the V groove of the board | substrate which concerns on this invention, (b) is the microscope picture of the V groove of the board | substrate produced by the grinding process. (A) is the surface profile of the inner wall surface of the V-groove of the substrate according to the present invention, and (b) is the surface profile of the inner wall surface of the V-groove of the substrate manufactured by grinding. It is the figure which showed typically the experiment which verifies the effect of this invention. It is the external appearance schematic diagram of the conventional general optical fiber array, (a) is the exploded perspective view which showed the state before an assembly, (b) is the combined perspective view which showed the state after an assembly.

Explanation of symbols

1α Optical fiber array according to the first embodiment 2α Substrate according to the first embodiment 3 Holding lid 4 Optical fiber 21 V-groove forming portion 22 Plane portion
23 Step surface 24 End surface 25 Upper surface 26α V groove 27α according to the first embodiment V groove top portion 28α according to the first embodiment V groove bottom 29 according to the first embodiment 29 Edge 31 of the step surface Step surface The edge 32 corresponding to the mounting surface 41 Bare fiber 42 Coated fiber Xα Changed portion of the V-groove cross-sectional shape according to the first embodiment

Claims (9)

  A V-groove portion having a plurality of V-grooves to which optical fibers are mounted is attached to a V-groove substrate formed by extending from a flat surface through a step surface, and a V-groove portion to which optical fibers of the V-groove substrate are mounted. An optical fiber array, wherein the surface roughness of the contact surface of the V-groove substrate and / or the fiber pressing cover with the optical fiber is 0.1 μm or less at the maximum height Rz.   2. The optical fiber array according to claim 1, wherein an opening angle of the V-groove formed in the V-groove substrate gradually widens toward the plane portion side.   2. The optical fiber array according to claim 1, wherein a depth of the V-groove formed in the V-groove substrate is gradually increased toward the flat portion side.   A V-groove substrate having a plurality of V-grooves to which an optical fiber is mounted is formed to extend from a flat surface through a stepped surface, and the contact surface of the V-groove substrate with the optical fiber of the V-groove substrate The surface roughness of the optical fiber array substrate is characterized in that the maximum height Rz is 0.1 μm or less.   5. The optical fiber array substrate according to claim 4, wherein an opening angle of the V-groove formed in the V-groove substrate gradually widens toward the flat portion side.   6. The substrate for an optical fiber array according to claim 5, further comprising a portion in which an opening angle of the V groove formed in the V groove substrate is constant.   5. The optical fiber array substrate according to claim 4, wherein the depth of the V-groove formed in the V-groove substrate is gradually increased toward the flat portion side.   8. The optical fiber array substrate according to claim 7, further comprising a portion where the depth of the V-groove formed in the V-groove substrate is constant.   9. The optical fiber array substrate according to claim 4, wherein the optical fiber array substrate is formed of a glass mold.