JP5278275B2 - Manufacturing method of optical waveguide with mirror - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an optical waveguide with a mirror for efficiently manufacturing the optical waveguide with a mirror having a core part wherein a mirror surface which sufficiently reduces loss of the light is formed. <P>SOLUTION: In the method of manufacturing the optical waveguide with a mirror, when a part of the core part of the optical waveguide including the core part, which contains a resin constituent and transmits light, is irradiated with a laser beam through a mask having an opening to scatter the resin constituent in a part of the core part, the mirror surface slanting to the transmission direction of the light transmitted through the core part is formed in the core part. The laser beams are radiated so that their radiation periods are reduced as separated farther in the width direction from the substantially central axis in the longitudinal direction of a plane to be irradiated with the laser beams of the core part. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a manufacturing method of an optical waveguide with a mirror, and more particularly to a manufacturing method of an optical waveguide with a mirror that forms a mirror surface on the optical waveguide by irradiating the optical waveguide with a laser beam.

  In recent years, there is an increasing demand for downsizing and high performance of electronic devices. And in order to cope with high-speed signals, it has been studied to connect electronic components by optical signals and to increase the speed of signal transmission paths in electronic equipment. Optical wiring for connection by optical signals And an optical / electrical hybrid substrate provided with electrical wiring have been used.

  In an electronic device including such a mixed optical / electrical board, a plurality of electronic components are mounted on the mixed board. For example, an electric signal output from a certain electronic component is transmitted through an electric wiring to emit a light emitting element. Is converted into an optical signal, and this optical signal is transmitted through the optical wiring. The optical signal transmitted through the optical wiring is converted into an electrical signal by the light receiving element, and the electrical signal is transmitted through the electrical wiring and input to another electronic component mounted on the mixed substrate. In this case, an optical waveguide is used for the optical wiring, and the light emitting element and the light receiving element are mounted on the optical waveguide. Therefore, in the optical waveguide, in order to introduce the optical signal emitted from the light emitting element into the optical waveguide, or to extract the optical signal in the optical waveguide to the outside, the transmission direction of the optical signal (traveling direction) ) Has been formed to change the mirror surface.

  Conventionally, the mirror surface in such an optical waveguide has been formed by dicing or installing a mirror block. However, the dicing process has a problem that parts other than the mirror part are processed, and there is a problem that the installation place is limited in the installation of the mirror block. As described above, the dicing process and the method of installing the mirror block are not always sufficient in terms of workability and the like.

  In recent years, a method of forming a mirror surface by irradiating an optical waveguide with a laser beam has been studied. For example, in Matsushita Electric Works Technical Report (Vol. 54, No. 1, p. 95-100) (Non-patent Document 1), an excimer laser is used to transmit a laser beam through an aperture mask having a fixed mask and a movable mask. And a movable mask is moved to continuously increase the irradiation area of the laser beam, thereby changing the processing depth of the optical waveguide to form an inclined surface (mirror surface). However, the method described in Non-Patent Document 1 cannot always sufficiently suppress the optical loss on the mirror surface in the obtained optical waveguide.

Tanaka et al., “Manufacturing Method of Micromirror for Optical / Electric Composite Wiring Board Using Excimer Laser”, Matsushita Electric Works Technical Report, March 2006, Vol. 54, No. 1, p. 95-100

  The present invention has been made in view of the above-described problems of the prior art, and efficiently manufactures an optical waveguide with a mirror including a core portion on which a mirror surface capable of sufficiently suppressing light loss is formed. An object of the present invention is to provide a method for manufacturing a mirrored optical waveguide.

  As a result of intensive studies to achieve the above object, the present inventors have provided an opening in a part of the core portion of the optical waveguide having a core portion for transmitting light containing a resin component. By irradiating a laser beam through a mask having a part and scattering the resin component of a part of the core part, a mirror surface inclined with respect to the transmission direction of light transmitted through the core part is formed in the core part. In the manufacturing method of an optical waveguide with a mirror, the irradiation time of the laser beam is shortened as the distance from the substantially central axis in the longitudinal direction of the surface of the core portion to which the laser beam is to be irradiated is increased in the width direction of the surface. By irradiating the laser beam on the optical waveguide, it becomes possible to efficiently manufacture an optical waveguide with a mirror including a core portion on which a mirror surface capable of sufficiently suppressing light loss is formed. Found that, it has led to the completion of the present invention.

That is, the manufacturing method of the optical waveguide with a mirror of the present invention includes a mask having an opening in a part of the core of the optical waveguide including a core for transmitting light containing a resin component. Light with a mirror that forms a mirror surface inclined with respect to the transmission direction of light transmitted through the core portion on the core portion by irradiating a laser beam to scatter the resin component in a part of the core portion. A method of manufacturing a waveguide,
Irradiating the laser beam so that the irradiation time of the laser beam becomes shorter as the distance from the substantially central axis in the longitudinal direction of the surface to be irradiated with the laser beam of the core portion increases in the width direction of the surface ; and
At the time of irradiation with the laser beam, at least one end side in the longitudinal direction of the core portion of the region on the surface of the core portion irradiated with the laser beam has an arc shape with a curvature radius of 100 to 250 μm;
It is the method characterized by this.

  In the method for manufacturing an optical waveguide with a mirror according to the present invention, the shape of the opening of the mask is preferably circular, elliptical, or oval.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the optical waveguide with a mirror which can manufacture efficiently the optical waveguide with a mirror provided with the core part in which the mirror surface which can fully suppress the loss of light was formed is provided. It becomes possible to do.

It is a schematic diagram which shows one Embodiment of the process of irradiating a laser beam, (a) in FIG. 1 is a schematic diagram which shows the state of the longitudinal cross-section of the optical waveguide at the time of the irradiation start of a laser beam, (B) is a schematic diagram which shows the state of the longitudinal cross-section of an optical waveguide when a mirror surface is formed by irradiation of a laser beam. It is a schematic diagram which shows one Embodiment of the surface which should be irradiated with the laser beam on the surface of a core layer. It is a schematic diagram which shows one Embodiment of the irradiation surface shape of the laser beam formed on the surface of a core layer when a laser beam is irradiated. It is a schematic diagram which shows one Embodiment of the irradiation surface shape of the laser beam formed on the surface of a core layer when a laser beam is irradiated. It is a schematic longitudinal cross-sectional view of one Embodiment of the optical waveguide used for formation of a mirror surface. FIG. 7 is a schematic diagram showing another embodiment of the step of irradiating a laser beam, and (a) in FIG. 6 is a schematic diagram showing the state of the longitudinal section of the optical waveguide at the start of laser beam irradiation, (B) of FIG. 6 is a schematic diagram showing the state of the longitudinal section of the optical waveguide from which the clad layer on the upper part of the part where the mirror surface is formed by laser beam irradiation is removed, and (c) in FIG. 6 is a mirror on the core layer. It is a schematic diagram which shows the state of the longitudinal cross-section of the optical waveguide when a surface is formed. It is a schematic diagram which shows one Embodiment of the irradiation surface shape of the laser beam on the surface of a core layer. It is a microscope picture which shows the state (state of a thin film) of the site | part in which the mirror surface of the core layer (thin film) of the optical waveguide with a mirror obtained in Example 2 was formed. It is a microscope picture which shows the state (thin film state) of the site | part in which the mirror surface of the core layer (thin film) of the optical waveguide with a mirror obtained in Comparative Example 1 was formed.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

The method of manufacturing an optical waveguide with a mirror according to the present invention includes a laser beam through a mask having an opening in a part of the core portion of the optical waveguide having a core portion for transmitting light containing a resin component. Of the optical waveguide with a mirror that forms a mirror surface inclined with respect to the transmission direction of the light transmitted through the core portion by scattering the resin component of a part of the core portion. A manufacturing method comprising:
The laser beam is irradiated such that the irradiation time of the laser beam is shortened as the distance from the substantially central axis in the longitudinal direction of the surface to be irradiated with the laser beam of the core portion increases in the width direction of the surface. It is a method to do.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description and drawings, the same or corresponding elements are denoted by the same reference numerals, and duplicate descriptions are omitted. Here, first, a preferred embodiment of the step of irradiating a laser beam will be described, and a preferred embodiment of the optical waveguide used in this step will be described later.

  FIG. 1 shows a case where a laser beam is irradiated on an optical waveguide 11 including a core layer 11a and a clad layer 11b ((a) is when laser beam LB irradiation is started, and (b) is when the mirror surface 12 is formed). It is a schematic longitudinal cross-sectional view which shows typically the state of the optical waveguide of this mirror structure vicinity. The core layer 11a is basically a layer composed of a core part 111A and a clad part 111B (see FIG. 2). In the schematic longitudinal sectional view of FIG. 1, the cross section of the core part 111A of the core layer 11a is shown. Has been.

  In the laser beam LB irradiation process as shown in FIG. 1, the optical waveguide 11 is irradiated with the laser beam LB through the opening 13 a of the mask 13. At the time of irradiation with such a laser beam LB, the laser beam LB is changed while relatively changing the portion irradiated with the laser beam in the light transmission direction of the core (the direction indicated by the arrow A in FIG. 1). Is irradiated. In the present embodiment, the irradiated portion of the laser beam is relatively changed by moving the optical waveguide 11 in the direction indicated by the arrow A. As a result, the irradiation area of the laser beam can be continuously increased in the light transmission direction of the core portion, and the processing depth of the optical waveguide is changed to tilt the light transmission direction of the core portion. An inclined surface (mirror surface) can be formed. Thus, when forming the mirror surface, it is preferable to irradiate the laser beam LB while relatively changing the irradiated portion of the laser beam LB in the longitudinal direction of the core portion.

  The irradiation process of the laser beam LB will be described more specifically. First, while irradiating the laser beam LB through the opening 13a of the mask 13, the optical waveguide 11 passes through the optical transmission direction of the core (FIG. 1). It is moved in the direction indicated by the arrow A inside (FIG. 1A). By such irradiation with the laser beam LB, the resin component forming the core portion is scattered (evaporated) and removed to a predetermined depth in the portion (irradiation portion) irradiated with the laser beam LB. At this time, since the laser beam LB is irradiated while moving the optical waveguide 11, the irradiated portion of the laser beam LB moves in the transmission direction A (horizontal direction), and the laser beam is transmitted in the light transmission direction of the core portion. The irradiation time of LB changes. That is, since the size of the irradiated portion of the laser beam LB does not change, the laser beam is not irradiated by the movement of the optical waveguide 11 on the left side (left side in the figure) of the irradiated portion, and the resin component that forms the core portion It is no longer removed. On the other hand, the right side portion (right side in the figure) of the portion irradiated with the laser beam LB is a portion that is newly irradiated with the laser beam LB due to the movement of the optical waveguide 11, and thus has been newly irradiated. The resin component forming the core portion is removed for the time. Therefore, in the region where the laser beam of the core portion is irradiated, the reach of the laser beam LB in the depth direction with respect to the optical waveguide 11 varies depending on the moving speed of the optical waveguide 11 in the light transmission direction. The resin component is continuously removed in the depth direction of the core portion according to the degree of reach, and a mirror surface 12 inclined with respect to the transmission direction of the light transmitted through the core portion is formed on the core portion. (FIG. 1B). As described above, in the laser beam LB irradiation process, the laser beam LB is irradiated to a part of the core portion of the optical waveguide 11 while relatively changing the irradiation portion of the laser beam LB with respect to the core portion. It is possible to partially change the irradiation time of the laser beam LB to the site forming the laser beam LB, and adjust the degree of arrival of the laser beam LB in the depth direction of the core portion while adjusting the resin component that is a constituent material of the core portion It can be removed. Therefore, according to such an irradiation method of the laser beam LB, the mirror surface 12 inclined with respect to the light transmission direction is formed. And after forming the mirror surface 12 in this way, the formation of the mirror surface is completed by terminating the irradiation of the laser beam LB. The series of steps for forming the mirror surface 12 is hereinafter referred to as “mirror surface processing step” in some cases.

  In the present invention, as shown in FIG. 1, when the laser beam LB is irradiated to a part of the core portion of the optical waveguide 11 while relatively changing the irradiation region of the laser beam LB with respect to the core portion, The laser beam LB is irradiated so that the irradiation time of the laser beam LB becomes shorter as the distance from the substantially central axis in the longitudinal direction of the surface S to be irradiated with the laser beam increases in the width direction W.

  Here, the “surface to be irradiated with the laser beam of the core portion” is a region on the upper surface of the core portion (surface on the side irradiated with the laser beam), and the laser beam passes through the mirror surface processing step. It refers to the area on the surface of the core that is irradiated. With reference to FIG. 2, the “surface to be irradiated with the laser beam in the core portion” will be described in more detail. FIG. 2 is a schematic view of the surface of the core layer 11a on the side irradiated with the laser beam (in the optical axis direction of the laser beam LB). In the embodiment shown in FIG. 2, the core layer 11a includes a core part 111A and a clad part 111B. In addition, the hatched portion S on the surface of the core portion 111A is irradiated with the laser beam through all the steps of irradiating the laser beam while moving the optical waveguide in the optical transmission direction. Area). In the present invention, the region S on the upper surface of the core portion 111A irradiated with the laser beam through such a mirror surface processing step is defined as “the surface on which the laser beam of the core portion is to be irradiated”. The “substantially central axis” is preferably the same axis as the central axis in the longitudinal direction of the core portion of the irradiation surface shape of the laser beam LB, and from the central axis C in the longitudinal direction of the core portion to the width direction (in the drawing) In the region sandwiched between the two lines when considering a line parallel to the central axis C in the longitudinal direction of the core portion at a position 5 μm apart from each other in the horizontal direction W from the central axis C of It is preferable that the axis be present in In the embodiment shown in FIG. 2, the central axis C in the longitudinal direction of the core portion and the “substantially central axis” are the same axis.

  By irradiating the laser beam LB such that the irradiation time of the laser beam LB becomes shorter as the distance from the substantially central axis in the longitudinal direction of the surface S to be irradiated with the laser beam of the core portion in the width direction W decreases, The reason why the mirror surface 12 in which the optical loss is sufficiently suppressed can be efficiently formed is not necessarily clear, but the present inventors infer as follows. That is, first, the present inventors dispose the core portion 111A containing the resin component away from the substantially central axis in the longitudinal direction of the surface S to be irradiated with the laser beam of the core portion 111A in the width direction W. It has been found that the absorption efficiency of the laser beam in the core portion is increased, and it tends to be more easily scraped during etching. Therefore, for example, as shown in FIG. 1, when the laser beam LB is irradiated while moving the optical waveguide 11, if the laser beam is uniformly irradiated as in the conventional case, the difference in etching grade (scraping) in the core portion Because of the difference in ease), the core portion 111A tends to be removed deeper as the distance from the central axis C in the longitudinal direction of the surface S to be irradiated with the laser beam in the width direction W increases. The present inventors have found that the surface 12 is curved according to the difference in etching grade (difference in ease of cutting) in the core portion, and the loss of light cannot be sufficiently suppressed at the mirror surface 12. Therefore, in the present invention, the irradiation time of the laser beam LB is shortened as the distance from the substantially central axis in the longitudinal direction of the surface S to be irradiated with the laser beam LB of the core portion 111A in the width direction W of the surface is increased. The laser beam LB is irradiated. That is, in the present invention, the laser beam irradiation time is increased in the surface S of the core portion 111A that is to be irradiated with the laser beam, the longer it is closer to the central axis, and vice versa. The further away from W, the shorter the laser beam irradiation time. Here, for example, the point P1 and the point P2 on any collinear line perpendicular to the central axis C in the longitudinal direction of the core part will be described as an example. The point P2 is located in the width direction from the central axis C rather than the point P1. In the present invention, the laser beam is irradiated so that the irradiation time of the laser beam LB on the point P2 is shorter than the irradiation time of the laser beam LB on the point P1. Irradiate. As described above, in the present invention, at the time of etching, the laser beam LB is irradiated for a portion that is harder to be cut in the core portion 111A, so that the formed mirror surface has a sufficiently corrected curvature. . Therefore, according to the present invention, it is possible to form a mirror surface 12 having a flat shape that is closer to a flat surface, and the mirror surface that can sufficiently suppress the loss of light when transmitting light is efficiently obtained. The present inventors speculate that it can be manufactured.

  Further, the laser beam LB is irradiated so that the irradiation time of the laser beam LB becomes shorter as the distance from the substantially central axis in the longitudinal direction of the surface S to be irradiated with such a laser beam increases in the width direction W of the surface S. Although the method is not particularly limited, as shown in FIG. 1, when the laser beam LB is irradiated while moving the optical waveguide 11, the shape of the opening 13a is circular, elliptical, or oval. It is preferable to employ a method using a mask. That is, in the present invention, the shape of the opening 13a of the mask 13 is preferably circular, elliptical, or oval. Here, the oval shape refers to a shape in which two sides are straight and two sides are curved, such as a shape such as a surface S in FIG. 2 or a dotted line in FIG. By using the mask having the opening 13a having such a shape, when the laser beam LB is irradiated while relatively moving the irradiated portion of the laser beam LB, the longitudinal direction of the surface S to be irradiated with the laser beam is increased. As the distance from the substantially central axis in the width direction of the surface decreases, the irradiation time of the laser beam can be easily shortened. In the present invention, when the shape of the opening of the mask 13 is an oval, the longitudinal direction of the opening and the light transmission direction (A direction) of the core are the same direction. It is preferable to irradiate the laser beam LB using a mask. In addition, the material of such a mask etc. is not restrict | limited in particular, A well-known material can be utilized suitably according to the kind etc. of a light source.

  Furthermore, it is preferable that at least one end side in the longitudinal direction of the core portion of the region on the surface of the core portion 111A irradiated with the laser beam LB has an arc shape. Here, the “region on the surface of the core portion 111A irradiated with the laser beam LB” will be described in detail with reference to FIG. FIG. 3 is a schematic diagram showing an embodiment of the relationship between the core layer 11a and the irradiation surface shape of the laser beam LB when viewed from the optical axis direction of the laser beam LB. Here, the “irradiation surface shape” of the laser beam LB refers to a spot shape of the laser beam formed on the surface of the core layer 11a when the laser beam LB is irradiated. In the embodiment shown in FIG. 3, the “irradiation surface shape” of the laser beam LB is a curve connecting points E1 to E6 in the order of point E1, point E2, point E3, point E4, point E5, point E6, and point E1. It is expressed as an elliptical shape formed by Here, in the embodiment shown in FIG. 3, the “region on the surface of the core portion irradiated with the laser beam LB” includes points E1 to E6, points E1, E2, E3, E4, This is an oval region formed by lines connecting in order of E5, point E6, and point E1, and a line connecting E1 and E6 and a line connecting E3 and E4 are straight lines. Thus, in the present invention, the “region on the surface of the core portion irradiated with the laser beam LB” is a portion (region) existing on the surface of the core portion 111A in the irradiation surface shape of the laser beam LB. ). Further, in the embodiment shown in FIG. 3, “ends in the longitudinal direction of the region on the surface of the core portion irradiated with the laser beam LB” are E1, E2, and E3 in the order of E1 to E3. And a curve connecting E4, E5, and E6 in the order of E4 to 6 respectively.

  Further, in the embodiment shown in FIG. 3, “the edge in the longitudinal direction of the region on the surface of the core portion irradiated with the laser beam LB” has an arc shape. In this way, by making both the “ends in the longitudinal direction of the region on the surface of the core part irradiated with the laser beam LB” arc-shaped, the laser beam LB of the core part 111A can be more easily formed. The laser beam LB can be irradiated so that the irradiation time of the laser beam LB becomes shorter as the distance from the substantially central axis in the longitudinal direction of the surface S to be irradiated increases in the width direction of the surface. Therefore, it is more preferable that both of “the edge in the longitudinal direction of the region on the surface of the core portion irradiated with the laser beam LB” have an arc shape.

  Here, the “laser beam shape” is more efficiently achieved by the “shape of the opening of the mask” and the “shape of the edge in the longitudinal direction of the region on the surface of the core portion irradiated with the laser beam LB” as described above. The reason why it is possible to irradiate the laser beam LB such that the irradiation time of the laser beam LB becomes shorter as the distance from the substantially central axis in the longitudinal direction of the surface S to be irradiated in the width direction W of the surface S decreases. Will be described with reference to FIG. FIG. 4 is a schematic diagram of the upper surface of the core layer 11a when the core layer 11a is viewed from the optical axis direction of the laser beam LB. In FIG. 4, with respect to the case of relatively moving the irradiated portion of the laser beam LB, the irradiation position and shape of the laser beam LB at the beginning of the laser beam irradiation are schematically shown as an irradiation surface shape F1, and after the laser beam irradiation. A position where the laser beam LB is irradiated after a predetermined time and its shape are schematically shown as an irradiation surface shape F2. In the embodiment shown in FIG. 4, the shape of the irradiation surface of the laser beam LB on the surface of the core layer 11a is an ellipse. Here, the irradiation time of the laser beam LB will be described by taking, as an example, a point P3 that is separated from the central axis C in the longitudinal direction of the core portion 111A in the width direction and a point P4 that is located farther from the central axis C than the point P3. consider. Note that the point P3 and the point P4 are points that are on an arbitrary straight line perpendicular to the central axis C in the longitudinal direction of the core portion 111A. The point P4 exists in the range of the irradiated portion (irradiation surface shape) F1 of the laser beam LB at the beginning of the laser irradiation, but exists outside the irradiation portion (irradiation surface shape) F2 after a predetermined time has elapsed. On the other hand, the point P3 exists in the range of the irradiated portions (F1 and F2) of the laser beam LB both at the beginning of laser irradiation and after a predetermined time has elapsed. As described above, when the laser beam LB is irradiated while relatively moving the irradiated portion of the laser beam LB, the length of the region on the surface of the core portion irradiated with the laser beam LB is shown in FIG. By making the edge in the direction arc-shaped, the laser beam LB is irradiated more easily and the laser beam LB is more distant from the center axis as it is closer to the center axis. The irradiation time of LB can be further shortened. In addition, the irradiation region on the surface of the core portion of the laser beam LB having an arcuate end in the longitudinal direction can be easily formed by making the shape of the opening of the mask circular, elliptical, or oval. . Therefore, by making the shape of the opening of the mask circular, elliptical, or oval, or by making the end side in the longitudinal direction of the core part of the irradiation region of the laser beam LB on the surface of the core part more circular, Efficiently “irradiate the laser beam LB so that the irradiation time of the laser beam LB becomes shorter as the distance from the substantially central axis in the longitudinal direction of the surface S to be irradiated with the laser beam in the width direction W of the surface S” increases. Is possible.

  Further, in such a “region on the surface of the core portion irradiated with the laser beam LB”, when the edge in the longitudinal direction of the core portion is arcuate, the radius of curvature of the arc is 100 to 250 μm ( More preferably, it is more preferable that it is 100-150 micrometers. If the radius of curvature of such an arc is less than the lower limit, the irradiation time in the vicinity of the central portion of the core portion becomes excessively long, so the vicinity of the central portion is shaved deeper than the end portion, and the flatness of the mirror surface is impaired. On the other hand, when the upper limit is exceeded, there is a tendency that the irradiation time is not sufficiently different between the end portion and the central portion of the core portion, and the curvature of the mirror surface tends not to be corrected. Note that the radius of curvature here refers to the minimum radius of curvature among the radii of curvature of the elliptical edges when the shape of the arc is elliptical. Further, by irradiating the laser beam LB with a radius of curvature of the arc of the end side of 100 to 250 μm, the surface of the core portion 111A from the substantially central axis in the longitudinal direction of the surface S to be irradiated with the laser beam LB The farther away in the width direction of S, the shorter the irradiation time of the laser beam LB, and the more easily the mirror surface 12 whose curvature is corrected tends to be formed.

  Note that the radius of curvature of the edge of the laser beam LB is such that when the laser beam LB is irradiated, the laser beam LB transmitted through the opening of the mask is condensed by a lens and the laser beam LB is applied to the core portion 111A. In the case of irradiation, even if a mask having the same shape of the opening is used, it varies depending on the magnification of the lens. Therefore, when the laser beam LB that has passed through the opening of the mask is condensed using a lens and irradiated onto the core, the opening of the mask depends on the design of the irradiation surface shape of the laser beam. It is necessary to appropriately change the combination of the shape of the lens and the lens to an optimum one, and thereby, the radius of curvature of the arc of the end of the irradiation region of the laser beam LB can be easily achieved within the above range. .

  When irradiating the laser beam LB, the central axis O (see FIG. 3) in the longitudinal direction of the core portion of the irradiation surface shape formed on the core surface 11a of the laser beam LB and the upper surface of the core portion 111A It is preferable to irradiate the laser beam LB such that the distance from the central axis C in the longitudinal direction (see FIG. 3) is 5 μm or less, and irradiate the laser beam LB so that the axis O and the axis C overlap. More preferably. When such a distance exceeds 5 μm, it is difficult to sufficiently correct the curvature of the mirror surface 12, and the loss of light on the formed mirror surface 12 tends not to be sufficiently suppressed. Further, the loss of light is further suppressed by overlapping the central axis O of the laser beam irradiation surface shape in the longitudinal direction of the core portion with the central axis C in the longitudinal direction of the upper surface of the core portion 111A. A mirror surface can be formed. In the present invention, the “substantially central axis” in the longitudinal direction of the surface to be irradiated with the laser beam of the core portion is the irradiation surface shape formed on the core surface 11a of the laser beam LB as described above. It is preferably the same axis as the central axis O in the longitudinal direction of the core portion.

Examples of the light source of the laser beam LB include excimer lasers such as ArF and KrF, YAG lasers, and CO ₂ lasers. Irradiation energy of such a laser beam LB is not particularly limited because it varies depending on the resin component in the core portion 111A, preferably in the range of 100~1000mJ / cm ^2, particularly preferably in the range of 250~700mJ / cm ² . When the irradiation energy is within the above range, the resin component in the core can be efficiently removed. The laser irradiation frequency is not particularly limited because it varies depending on the constituent material of the core part, but is preferably in the range of 50 to 300 Hz, and particularly preferably in the range of 50 to 200 Hz. When the frequency is within the above range, the smoothness of the inclined surface (mirror surface) tends to be excellent.

  Further, the speed at which the irradiated portion of the laser beam LB is relatively moved varies depending on the material of the core portion of the optical waveguide, the design of the target mirror surface angle, the type of the laser beam light source, etc. In other words, the speed may be set as appropriate according to the type of the optical waveguide and the design of the mirror surface.

  Next, a preferred embodiment of an optical waveguide (an optical waveguide before mirror surface processing) used in the laser beam irradiation process as described above will be described.

  FIG. 5 shows a schematic longitudinal sectional view in the light transmission direction of the core portion of such an optical waveguide. An optical waveguide 11 shown in FIG. 5 includes a core layer 11a containing a resin component and having a core part 111A and a clad part 111B, and a clad layer 11b containing a resin component. Such a core part 111A functions as a light guide.

  The core layer 11a is a layer containing a first resin as a resin component. As such 1st resin, well-known resin (polymer) which can be used in order to form the core layer 11a of an optical waveguide can be used suitably, for example, cyclic olefin resin, epoxy resin, polyamide Polymers, acrylic resins, methacrylic resins, polycarbonates, polystyrenes, polyimides, polybenzoxazoles, etc., and polymer alloys, polymer blends (mixtures), copolymers that combine one or more of these polymers And a crosslinked body, and a cyclic olefin resin, an epoxy resin, a polyamide resin, and an acrylic resin are preferable. Such 1st resin can be used individually by 1 type or in combination of 2 or more types. The first resin in the core layer 11a and the resin component (second resin) in the clad layer 11b to be described later may contain the same type of resin, but the refractive index difference can be more easily determined. From the viewpoint that they can be produced, it is preferable that they are of different types (including those having the same main chain and different types of side chains).

  Moreover, as such 1st resin, it is preferable that it is resin produced | generated when a chemical change arises by the effect | action of the acid derived from the acid generator mentioned later. That is, as such a first resin, a resin formed from a core layer polymer in a core forming varnish described later (for example, a core layer polymer itself, a reaction product between core layer polymers, a core, More preferably, the polymer is a resin formed by the reaction of a monomer for a layer and a monomer or a crosslinking agent in a core-forming varnish. The first resin in the core layer 11a is preferably a norbornene polymer from the viewpoint of having excellent optical transmission performance and having both heat resistance and flexibility.

  As content of the 1st resin in the core layer 11a, it is preferable that it is 50-90 mass%, and it is more preferable that it is 60-80 mass%. If the content is less than the lower limit, it tends to be difficult to stably maintain the shape and thickness of the core layer. On the other hand, if the content exceeds the upper limit, refractive index modulation between the core and the clad of the optical waveguide is likely to occur. It tends to be difficult. In addition, as components other than 1st resin in the core layer 11a, components other than 1st resin of the components produced | generated from each component in the varnish for core formation mentioned later or its component are mentioned, for example. It is done.

  The weight average molecular weight of the first resin is not particularly limited, but is preferably 1,000 to 1,000,000, more preferably 5,000 to 500,000, and particularly preferably 10,000 to 200,000. When the weight average molecular weight (Mw) of the first resin is within the above range, the heat resistance and the smoothness of the core surface are balanced, and as a result, an optical waveguide having excellent optical characteristics tends to be manufactured. is there. The “weight average molecular weight” can be evaluated in terms of polystyrene measured by, for example, gel permeation chromatography (GPC) using cyclohexane or toluene as an organic solvent.

  The average thickness of the core layer 11a can be changed as appropriate depending on the application, and is not particularly limited, but is preferably 1 to 200 μm, more preferably 5 to 100 μm, More preferably, it is 10-60 micrometers. Further, the cross-sectional shape of the core portion 111A is not particularly limited, but is preferably substantially square or substantially rectangular (substantially rectangular). The width of the core portion 111A can be changed as appropriate according to its use, and is not particularly limited, but is preferably 1 to 200 μm, more preferably 5 to 100 μm, More preferably, it is 10-60 micrometers. Further, the core portion 111A may be linear or may be curved or branched in the middle, and the shape can be appropriately changed according to the intended use.

Further, the core portion 111A in the core layer 11a has a higher refractive index than the cladding portion 111B. The refractive index difference between the core portion 111A and the clad portion 111B is not particularly limited, but is preferably 0.3 to 5.5%, and more preferably 0.8 to 2.2%. . If the refractive index difference is less than the lower limit, the effect of transmitting light through the core portion tends to be reduced. In the present invention, the “refractive index difference” is expressed by the following formula when the refractive index of the cladding 111B is n _B and the refractive index of the core 111A is n _A :
Refractive index difference (%) = {(n _A / n _B ) −1} × 100
The value obtained by calculating is adopted.

  The clad layer 11b is a layer containing a second resin as a resin component. Such a second resin is not particularly limited, and a known polymer that can be used for forming a cladding layer in an optical waveguide can be appropriately used. For example, a cyclic olefin resin, an acrylic resin , Methacrylic resins, polycarbonate resins, polystyrene resins, epoxy resins, polyamide resins, polyimide resins, polybenzoxazole resins, etc., and polymer alloys combining one or more of these polymers Polymer blends (mixtures), copolymers, cross-linked products and the like are preferable. In the optical waveguide including the clad layer 11b containing the second resin, the refractive index of the clad layer 11b is made higher than the refractive index of the core portion 111A in order to make the core portion 111A sufficiently function as a light guide. Need to be low. Therefore, it is preferable to select and use a resin having a lower refractive index than the material forming the core layer 11aB as the second resin in the cladding layer 11b. Further, as the second resin in the clad layer 11b, from the viewpoint of improving the adhesion between the clad layer 11b and the core layer 11a, the same type of resin as the first resin in the core layer 11a (for example, the core layer) When the resin inside is an acrylic resin, the resin in the clad layer is also an acrylic resin, and when the resin in the core layer is an epoxy resin, the resin in the clad layer is also It is preferable to use an epoxy resin.

  Furthermore, the second resin is preferably a norbornene-based polymer from the viewpoints of flexibility, heat resistance, and moisture resistance. The second resin in the clad layer 11b is a resin formed from a polymer for the clad layer in the clad forming varnish described later (for example, the polymer for the clad layer itself, a reaction product between the polymers for the clad layer, A resin or the like formed by reaction of a polymer for a cladding layer with a monomer, a crosslinking agent, or the like in the cladding varnish) is preferable.

  The clad layer 11b may contain other components other than the second resin. Examples of such other components include each component in the clad layer forming varnish described later or its component. Ingredients other than the second resin among the components generated from

  Moreover, although it does not specifically limit as average thickness of the clad layer 11b, It is preferable that it is 1-200 micrometers, It is more preferable that it is 5-100 micrometers, It is still more preferable that it is 10-60 micrometers. Further, the average thickness of the clad layer 11b is preferably 0.1 to 1.5 times, more preferably 0.3 to 1.25 times the average thickness of the core layer 11a. . By making the average thickness of the clad layer 11b within the above range, the function as the clad layer 11b is more fully exhibited while preventing the optical waveguide 11 from being unnecessarily enlarged (thickened). It tends to be.

  Further, the refractive index difference between the clad layer 11b and the core part 111A is not particularly limited as long as the refractive index of the clad layer 11b is lower than the refractive index of the core part 111A, but is 0.2 to 20%. It is preferable that it is 0.5 to 10%. If the refractive index difference is less than the lower limit, the effect of transmitting light through the core portion tends to be reduced.

  Next, a method that can be suitably employed as a method for manufacturing such an optical waveguide as shown in FIG. 5 will be described. A method for manufacturing such an optical waveguide is not particularly limited, and a known method capable of manufacturing the above-described optical waveguide can be appropriately employed. As such a method, for example, a film-like core layer is formed with a core layer-forming varnish, a film-like clad layer is formed with a cladding layer-forming varnish, and these are laminated (I), Examples include a method (II) in which a clad layer forming varnish is applied onto a substrate to form a clad layer, and then a core layer forming varnish is applied to the surface of the clad layer to form the core layer. Hereinafter, the method (I) suitable as a method for producing such an optical waveguide will be described.

  First, a method for forming a film-like core layer will be described. As a method for forming such a film-like core layer, for example, a coating layer (core layer precursor) is obtained by applying a varnish for forming a core layer on a base material, and then the core layer precursor is coated. Then, the active energy ray is selectively irradiated through the mask having the opening to form the clad portion 111B having a low refractive index in the active energy ray irradiation region and a high refractive index in the non-irradiation region of the active energy ray. A method of forming the core layer by forming the core portion 111A may be employed.

  Such a substrate is not particularly limited as long as it can support the core layer precursor, and a known substrate that can be used when forming a film material can be appropriately used. Examples thereof include a silicon substrate, a silicon dioxide substrate, a glass substrate, a quartz substrate, and a polyethylene terephthalate (PET) film.

  Such a varnish for forming a core layer is not particularly limited as long as it contains a material whose refractive index changes upon irradiation with active energy rays, and the core portion 111A can be formed by irradiation with active energy rays through a mask. And what contains the well-known material which can form the clad part 111B can be used suitably.

  Moreover, it is preferable that such a varnish for core layer formation contains an acid generator and the polymer for core layers. Examples of the acid generator contained in such a core layer forming varnish include a photoacid generator and a thermal acid generator. Among such acid generators, a photoacid generator is more preferable from the viewpoint that an acid can be efficiently released by irradiation with active energy rays.

  Examples of such photoacid generators include triphenylsulfonium trifluoromethanesulfonate, tris (4-t-butylphenyl) sulfonium-trifluoromethanesulfonate, dimethyl (2- (2-naphthyl) -2-oxoethyl) sulfonium. -Sulfonium salts such as tetrakis (pentafluorophenyl) borate, diazonium salts such as p-nitrophenyldiazonium hexafluorophosphate, ammonium salts, phosphonium salts, diphenyliodonium trifluoromethanesulfonate, (triccumyl) iodonium-tetrakis (pentafluorophenyl) borate Iodonium salts such as quinonediazides, diazomethanes such as bis (phenylsulfonyl) diazomethane, 1-phenyl- -(4-Methylphenyl) sulfonyloxy-1-benzoylmethane, sulfonic acid esters such as N-hydroxynaphthalimide-trifluoromethanesulfonate, disulfones such as diphenyldisulfone, tris (2,4,6-trichloromethyl) And triazines such as -s-triazine and 2- (3,4-methylenedioxyphenyl) -4,6-bis- (trichloromethyl) -s-triazine.

  Moreover, as such a photoacid generator, a commercially available photoacid generator may be used. As a commercial item of such a photoacid generator, for example, “RHODORSIL (registered trademark) PHOTOINITIATOR 2074 (CAS No. 178233-72-2)” available from Rhodia USA, available from Toyo Ink Manufacturing Co., Ltd. Possible "TAG-372R ((dimethyl (2- (2-naphthyl) -2-oxoethyl) sulfonium tetrakis (pentafluorophenyl) borate: CAS No. 193957-54-9)), from Midori Chemical Co., Ltd. Available "MPI-103 (CAS No. 87709-41-9)", "TAG-371 (CAS No. 193957-53-8)" available from Toyo Ink Manufacturing Co., Ltd., Toyo Gosei Kogyo Co., Ltd. "TTBPS-TPFPB (Tris (4-te rt-butylphenyl) sulfonium tetrakis (pentapentafluorophenyl) borate) ". In addition, when using RHODORSIL PHOTOINITIATOR 2074 as such a photo-acid generator, it is preferable to use a high-pressure mercury lamp or a metal halide lamp as the ultraviolet light irradiation means. As a result, ultraviolet light with sufficient energy of less than 300 nm can be supplied, and RHODORSIL PHOTOINITIATOR 2074 can be efficiently decomposed to generate an acid.

  Examples of the thermal acid generator include nitrobenzyl tosylate such as 2-nitrobenzyl tosylate, benzylanilinium sulfonates, bissulfonyldiazomethanes, arylsulfinic acids, 2-butenyltetramethylenesulfonium. Examples include hexafluoroantimonates such as hexafluoroantimonate and 3-methyl-2-butenyltetramethylenesulfonium hexafluoroantimonate, trihaloacetic acids such as trifluoromethanesulfonates, and trifluoroacetate.

  In addition, as the polymer for the core layer, from the viewpoint that the chemical stability during storage and the reactivity during use can be more reliably achieved, the acid generated by the acid generator releases the main chain. It is preferable to use a polymer having a side chain containing a leaving group (leaving group). Moreover, as a polymer having a side chain containing such a leaving group, transparency is sufficiently high (colorless and transparent), and it is released by the action of an acid (preferably proton) released from the acid generator. A polymer in which the refractive index is changed (preferably reduced) by leaving (cutting) the functional group from the side chain is preferable.

As such a leaving group, from the viewpoint that it is relatively easily released by the acid released from the acid generator, in its molecular structure, an —O— structure, an —Si—aryl structure and an —O—Si— structure are included. Those having at least one of these are preferred. Among these leaving groups, from the viewpoint that the refractive index of the polymer can be lowered by leaving, -Si-diphenyl structure (formula: -Si (Ph) ₂ [wherein Ph represents a phenyl group) And a —O—Si-diphenyl structure (formula: —O—Si (Ph) ₂ [wherein Ph represents a phenyl group]). Groups containing a structure are preferred.

Further, the side chain containing the leaving group is not particularly limited as long as it contains the leaving group, and for example, the formula: — (CH ₂ ) _n —CH (CF ₃ ) ₂ —O ^{_{-Si (R 1) 3 ;-( CH}} 2) n -CH (CF 3) 2 -O-CH 2 -O-CH 3 ;-( CH 2) n -CH (CF 3) 2 -O-C ( ^{_{O) -O-C (R 1}} ) 3 ;-( CH 2) n -C (CF 3) 2 -OH ;-( CH 2) n C (O) NH 2 ;-( CH 2) n C (O ^{_{) Cl ;-( CH 2) n C}} (O) OR 1 ;-( CH 2) n-OR 1 ;-( CH 2) n -OC (O) R 1 ;-( CH 2) n -C (O ^{_{) R 1 ;-( CH 2) n}} -OC (O) OR 1 ;-( CH 2) n Si (R 1) 3 ;-( CH 2) n Si (OR 1) 3; - ^{_{CH 2) n -O-Si (}} R 1) 3 ;-( CH 2) n C (O) OR 2; such a group represented the like. In addition, it is preferable that each n in such a formula is an integer of 0 to 10, and R ¹ may be the same or different, and each of hydrogen, linear or branched C ₁ -C ₂₀ alkyl group, a linear or halogenated or perhalogenated alkyl group branched _C 1 _{-C 20,} linear or branched _C 2 _{-C 10} alkenyl group, a linear or branched _C 2 _{-C 10} alkynyl group, C cycloalkyl groups ₅ -C _12, aryl group of C 6 _{-C 14,} be any of the halogenated or aralkyl group perhalogenated aryl, and _C 7 _{-C 24} of C 6 _{-C 14} Preferably, R ² is represented by the formula: —C (CH ₃ ) ₃ ; —Si (CH ₃ ) ₃ ; CH (R ³ ) OCH ₂ CH ₃ ; —CH (R ³ ) OC (CH ₃ ) ₃ ; One of a group or a cyclic group It is preferable that In the formula, R ³ represents a hydrogen atom or a linear or branched alkyl group.

Moreover, as a side chain containing such a leaving group, from the viewpoint that the leaving group can be more efficiently removed by an acid, the formula: — (CH ₂ ) _n —O—Si A group represented by (R ¹ ) ₃ or a formula: — (CH ₂ ) _n —Si (R ¹ ) ₃ is more preferable. Incidentally, n and R ¹ in such expressions are synonymous with those described above. Moreover, among the side chains represented by such a formula, it is more preferable that at least two of R ^{1 in} the formula are phenyl groups. The polymer having such a side chain containing a leaving group may contain at least one repeating unit having a side chain containing the leaving group in the polymer. It may contain two or more repeating units having a side chain containing a functional group.

  Examples of the core layer polymer include cyclic olefin resins such as norbornene resins and benzocyclobutene resins, acrylic resins, and methacrylic resins having a side chain containing the leaving group. , Polycarbonate resin, polystyrene resin, epoxy resin, polyamide resin, polyimide resin, polybenzoxazole resin, and a combination of one or more of these (polymer alloy, polymer blend ( Mixtures), copolymers, etc.). Moreover, as the polymer for the core layer, silane-based resins such as polysilane (eg, polymethylphenylsilane) and polysilazane (eg, perhydropolysilazane) may be used.

  Further, such a core layer polymer preferably mainly contains a norbornene-based resin (norbornene-based polymer) having a side chain containing the leaving group. Thus, by using a norbornene-based polymer having a side chain containing the leaving group as the core layer polymer, an optical waveguide having excellent optical transmission performance and heat resistance can be obtained. In addition, such a norbornene-based polymer makes it possible to obtain an optical waveguide that is less likely to undergo dimensional changes due to water absorption.

  Further, the norbornene-based polymer may be either a polymer having a single repeating unit (homopolymer) or a polymer having two or more norbornene-based repeating units (copolymer). Examples of such norbornene-based polymers include (1) addition (co) polymers of norbornene monomers obtained by addition (co) polymerization of norbornene monomers, and (2) norbornene monomers and ethylene or α-olefins. (3) addition polymers such as addition copolymers with norbornene-type monomers and non-conjugated dienes, and other monomers as required, (4) ring opening of norbornene-type monomers ( A (co) polymer, and a resin obtained by hydrogenating the (co) polymer if necessary, (5) a ring-opening copolymer of a norbornene-type monomer and ethylene or α-olefins, and ( A resin obtained by hydrogenating a (co) polymer, (6) a ring-opening copolymer of a norbornene-type monomer and a non-conjugated diene, or another monomer, and, if necessary, the (co) polymer And a ring-opening polymer such as a polymer obtained by hydrogenation. Examples of these polymers include random copolymers, block copolymers, and alternating copolymers.

  Further, as such a norbornene-based polymer, any norbornene having a repeating unit of norbornene having a side chain having a leaving group may be used, but norbornene having a relatively higher refractive index than a polymer for a cladding layer described later. It is preferable to use a polymer. Thus, by using a norbornene-based polymer having a relatively higher refractive index than the polymer for the cladding layer, when the core part is formed, the core part tends to have better optical transmission performance. .

  Such a norbornene-based polymer preferably contains a norbornene repeating unit having an alkyl group in the side chain in addition to the norbornene repeating unit having a side chain having a leaving group. .

  The side chain alkyl group in the repeating unit of such an alkylnorbornene may be either linear or branched, and may have a substituent. The alkyl group is not particularly limited, but is methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl. Group, octyl group, nonyl group, decyl group and the like. The substituent that the alkyl group may have is not particularly limited, and examples thereof include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group.

  The carbon number of the alkyl group in the side chain in the repeating unit of the alkyl norbornene is not particularly limited, but is more preferably 1 to 20 (more preferably 3 to 12). If the number of carbon atoms is less than the lower limit, flexibility from the polymer tends to be impaired, and application to applications that require flexibility tends to be difficult. On the other hand, if the upper limit is exceeded, the heat resistance of the polymer Tend to decrease.

  Moreover, as a norbornene-type polymer which has such a leaving group, following General formula (1):

[Wherein, R represents an alkyl group, Z represents a side chain containing the leaving group, and X and Y may be the same or different and each represents an integer of 70 or less. ]
A norbornene-based polymer having a structure represented by: Such an alkyl group represented by R is the same as the alkyl group in the side chain in the above repeating unit of alkylnorbornene.

  Further, such a norbornene-based polymer may be selected appropriately from known norbornene-based monomers according to its design, and used in ring-opening metathesis polymerization (ROMP), a combination of ROMP and a hydrogenation reaction, a radical or Manufactured using a known polymerization method such as polymerization using a cation, polymerization using a cationic palladium polymerization initiator, or polymerization using other polymerization initiators (for example, polymerization initiators of nickel and other transition metals). can do.

  Further, when a norbornene polymer is mainly used for the core layer polymer, the content ratio of the norbornene polymer in the core layer polymer is preferably 80 to 100% by mass, and preferably 95 to 100% by mass. More preferred. When such a content ratio is less than the lower limit, the effect obtained by using the norbornene-based polymer tends to be insufficient.

  Further, in such a varnish for forming a core layer, it is preferable to further contain a monomer, a procatalyst, a sensitizer, and an antioxidant in addition to the acid generator and the polymer for the core layer.

  Such a monomer is preferably a compound that forms a reaction product by reacting with the active energy ray using the core layer polymer as a matrix. The reactant derived from such a monomer includes a polymer (polymer) formed by polymerizing the monomer in the core layer polymer (matrix), a cross-linked structure that crosslinks the core layer polymers, and the core layer polymer. And branched structures (branched polymers and side chains) branched from the polymer for the cladding layer.

  Such a monomer is not particularly limited as long as it can be used for forming an optical waveguide. For example, a norbornene monomer, an acrylic acid (methacrylic acid) monomer, an epoxy monomer, and a styrene monomer Etc., and one or more of these can be used in combination. Among these, as the monomer, it is preferable to use a norbornene-based monomer from the viewpoint that an optical waveguide having excellent heat resistance and flexibility can be obtained.

  Such a norbornene-based monomer may have a substituent bonded to the norbornene ring. Such a substituent is not particularly limited, and examples thereof include a linear or branched alkyl group, a linear or branched alkenyl group, and a linear or branched alkynyl group. A linear or branched cycloalkyl group, a linear or branched cycloalkenyl group, a linear or branched aryl group, a linear or branched aralkyl group, Examples thereof include a linear or branched alkylidenyl group, a hydrocarbyl group, a halohydrocarbyl group, and a perhalohydrocarbyl group. Examples of such norbornene monomers include propyl norbornene and hexyl norbornene.

Further, such a norbornene-based monomer may be one in which a plurality of norbornene rings are bonded via an organic group. Examples of such an organic group is not particularly limited, for example, the following formula _{:-( CH 2) n - ;-( CH} 2) n -O- (CH 2) n -; - Ar-; or ;-( CH _{2) n -O-Si (X} ) 2 -O- (CH 2) n - [ wherein, n represents an integer of 1 to 10, Ar is an aromatic hydrocarbon which may have a substituent X represents an alkyl group which may have a substituent and an aromatic hydrocarbon which may have a substituent. ] Is represented. In addition, the several norbornene ring couple | bonded through such an organic group may have the said substituent, respectively. Examples of such norbornene-based monomers include bis-norbornene methoxydimethylsilane, bis-norbornene methoxydiethylsilane, and bis-norbornenemethoxydiphenylsilane. In addition, as such a monomer, the monomer described in the international publication 2005/052641 pamphlet can be used.

  The procatalyst is a substance that can initiate the reaction of the monomer (polymerization reaction, crosslinking reaction, etc.), and the substance whose activation temperature changes due to the action of an acid generator activated by irradiation with active energy rays. It is. Such a procatalyst (also referred to as a catalyst precursor) is not particularly limited as long as the activation temperature changes (increases or decreases) with irradiation of the active energy ray, and is not particularly limited. More preferably, the activation temperature decreases with this. With such a procatalyst, it is not necessary to perform heating that adds unnecessary heat to other layers during the preparation of the optical waveguide, and the characteristics (optical transmission performance) of the optical waveguide deteriorate due to the heat treatment during the preparation. It can be sufficiently prevented.

As such a procatalyst, those containing (mainly) at least one of the compounds represented by the following general formulas (Ia) and (Ib) are preferably used.
(E (R) ₃ ) ₂ Pd (Q) ₂ ... (Ia)
[(E (R) ₃ ) _a Pd (Q) (LB) _b ] _p [WCA] _r (Ib)
In the general formulas (Ia) and (Ib), E (R) ₃ represents a neutral electron donor ligand of Group 15, and E represents an element selected from Group 15 of the periodic table. R represents a hydrogen atom (or one of its isotopes) or a moiety containing a hydrocarbon group, and Q represents an anion coordination selected from the group consisting of carboxylate, thiocarboxylate and dithiocarboxylate Represents a child. In general formula (Ib), LB represents a Lewis base, WCA represents a weakly coordinating anion, a represents an integer of 1 to 3, b represents an integer of 0 to 2, and a and b And p and r represent numbers that balance the charge between the palladium cation and the weakly coordinated anion.

Typical procatalysts according to the general formula (Ia) include Pd (OAc) ₂ (P (i-Pr) ₃ ) ₂ , Pd (OAc) ₂ (P (Cy) ₃ ) ₂ , Pd (O ₂ CCMe ₃ ) ₂ (P (Cy) ₃ ) ₂ , Pd (OAc) ₂ (P (Cp) ₃ ) ₂ , Pd (O ₂ CCF ₃ ) ₂ (P (Cy) ₃ ) ₂ , Pd (O ₂ CC ₆ H ₅ ) ₃ (P (Cy) ₃ ) ₂ may be mentioned, but is not limited thereto. Here, Cp represents a cyclopentyl group, and Cy represents a cyclohexyl group.

Moreover, as a procatalyst represented by the said general formula (Ib), the compound whose p and r are either one of the integers of 1 and 2, respectively is preferable. A typical procatalyst according to the general formula (Ib) includes Pd (OAc) ₂ (P (Cy) ₃ ) ₂ . Here, Cy represents a cyclohexyl group, and Ac represents an acetyl group.

  The sensitizer increases the sensitivity of the acid generator to the active energy ray, reduces the time and energy required for activation (reaction or decomposition), and emits ultraviolet light at a wavelength suitable for the activation. It has a function to change the wavelength of. Such a sensitizer is not particularly limited. For example, anthracene such as 9,10-dibutoxyanthracene (CAS No. 76275-14-4), xanthones, anthraquinones, phenanthrenes, chrysene Benzopyrenes, fluoranthenes, rubrenes, pyrenes, indanthrines, thioxanthen-9-ones. Specific examples of the sensitizer include 2-isopropyl-9H-thioxanthen-9-one, 4-isopropyl-9H-thioxanthen-9-one, 1-chloro-4-propoxythioxanthone, and phenothiazine. It is done. These sensitizers can be used alone or in combination of two or more. In addition, 9,10-dibutoxyanthracene (DBA) can be obtained from Kawasaki Kasei Kogyo Co., Ltd.

  Further, the antioxidant can improve the characteristics of the optical waveguide obtained by preventing the generation of free radicals and the natural oxidation of the polymer. As such an antioxidant, Ciba (R) IRGANOX (R) 1076 and Ciba IRGAFOS (R) 168 available from Ciba Specialty Chemicals are preferably used. In addition, as other antioxidants, for example, Ciba Irganox (registered trademark) 129, Ciba Irganox 1330, Ciba Irganox 1010, Ciba Cyanox (registered trademark) 1790, Ciba Irganox (registered trademark) 3114, Ciba Ix it can.

  The core layer-forming varnish has other known additives (for example, a crosslinking agent and an antifoaming agent) that can be used for forming the core layer within a range that does not impair the effect of the core layer to be formed. , Adhesion aids, etc.) may be included as appropriate.

  Further, the method for producing such a core layer forming varnish is not particularly limited, and a known method can be appropriately employed. For example, a material for the core layer forming varnish (acid generator, core layer) can be used in a solvent. For example, a polymer, a monomer, a procatalyst, a sensitizer, an antioxidant, etc.) are dissolved to produce a varnish for forming a core layer. Examples of such a solvent include diethyl ether, diisopropyl ether, 1,2-dimethoxyethane (DME), 1,4-dioxane, tetrahydrofuran (THF), tetrahydropyran (THP), anisole, diethylene glycol dimethyl ether (diglyme), Ether solvents such as diethylene glycol ethyl ether (carbitol); cellosolv solvents such as methyl cellosolve, ethyl cellosolve, phenyl cellosolve; aliphatic hydrocarbon solvents such as hexane, pentane, heptane, cyclohexane; toluene, xylene, benzene, mesitylene Aromatic hydrocarbon solvents such as pyridine, pyrazine, furan, pyrrole, thiophene, methylpyrrolidone and other aromatic heterocyclic compounds solvents; N, N-dimethylformamide (DMF) Amide solvents such as N, N-dimethylacetamide (DMA); Halogen compound solvents such as dichloromethane, chloroform and 1,2-dichloroethane; Ester solvents such as ethyl acetate, methyl acetate and ethyl formate; Dimethyl sulfoxide (DMSO) ) And sulfur compound solvents such as sulfolane. These solvents can be used alone or in combination of two or more.

  Furthermore, although it does not restrict | limit especially as content of the acid generator in such a varnish for core layer formation, it is preferable that it is 0.1-10 mass%, and it is more preferable that it is 0.5-5 mass%. . If the content of such an acid generator is less than the lower limit, sufficient acid is not generated, and it tends to be difficult to proceed with the reaction efficiently. Loss tends to increase.

  The content ratio of the core layer polymer in the core layer forming varnish is not particularly limited, but is preferably 70 to 95% by mass, and more preferably 75 to 85% by mass. If the content ratio of the polymer for the core layer is less than the lower limit, it tends to be difficult to sufficiently modulate the refractive index.On the other hand, if the upper limit is exceeded, the viscosity of the varnish tends to increase significantly and filtration tends to be difficult. is there.

  Furthermore, the viscosity (normal temperature) of the varnish for forming the core layer is not particularly limited, and can be appropriately adjusted according to a coating method described later and a desired film thickness. The viscosity (normal temperature) of such a varnish for forming a core layer is preferably 100 to 10000 cP, more preferably 150 to 5000 cP, and still more preferably 200 to 3500 cP.

  The method for coating the core layer forming varnish on the substrate is not particularly limited, and for example, a doctor blade method, a spin coating method, a dipping method, a table coating method, a spray method, an applicator method, a curtain coating method, and a die coating method. And the like. In this way, the core layer precursor can be formed by applying the varnish for forming the core layer on the substrate.

  In the step of forming the core layer precursor, it is preferable that at least a part of the solvent is removed and dried after applying the core layer forming varnish on the substrate. As the step of removing the solvent (solvent removal step), a known method can be appropriately employed. For example, natural drying, a method of heating, a method of leaving under reduced pressure, or blowing an inert gas ( (Blow) method and a method of evaporating the solvent using a dryer.

Examples of the type of active energy rays irradiated to the core layer precursor thus obtained include ultraviolet rays, electron beams, X-rays, and lasers. Moreover, when employ | adopting ultraviolet light as such an active energy ray, it is preferable that the said ultraviolet light has a peak wavelength in 200-400 nm, and it is more preferable that it has a peak wavelength in 300-400 nm. If the peak wavelength of the ultraviolet light is less than the lower limit, the irradiation time of the ultraviolet light tends to be long and productivity tends to be poor.On the other hand, if the upper limit is exceeded, the light is exposed in the visible light region. It tends to be poor in stability. Furthermore, it is preferred that the irradiation dose of such ultraviolet light is 100~9000mJ / cm ^2, more preferably 200~6000mJ / cm ^2. If the irradiation amount of the ultraviolet light is less than the lower limit, it tends to be difficult to form the core portion 111A having sufficiently high optical transmission performance. On the other hand, if the upper limit is exceeded, chemical deterioration proceeds in the core layer. It tends to end up. Moreover, it does not restrict | limit especially as a light source for irradiating such an ultraviolet light, A well-known light source (For example, a high pressure mercury lamp etc.) can be used suitably.

  As a mask (masking) used when irradiating active energy rays to form such a core part 111A, an opening (window) equivalent to the shape (pattern) of the clad part 111B to be formed is formed and opened. A part that can block ultraviolet light in a part other than the part is used. By using such a mask, the active energy ray is transmitted through the opening, and the active energy ray is shielded at a portion other than the opening (transmission portion), thereby manufacturing the clad portion 111B derived from the shape of the opening. It becomes possible to do. In addition, such a mask for forming the core portion 111A may be formed in advance (separately formed) (for example, plate-shaped), or may be formed on the core layer precursor by, for example, a vapor deposition method. Alternatively, those formed by a coating method may be used.

  Examples of such a mask for forming the core portion 111A include a photomask made of quartz glass or a PET base material, a stencil mask, a metal thin film formed by a vapor deposition method (evaporation, sputtering, etc.), etc. Can be used as appropriate. Among such masks, it is particularly preferable to use a photomask or a stencil mask from the viewpoints that a fine pattern can be formed with high accuracy and that handling is good and productivity is improved. The constituent material of such a mask is not particularly limited, and may be appropriately selected from known materials depending on the peak wavelength of the active energy ray to be irradiated.

  Here, the reason why a portion having a different refractive index is formed in the core layer precursor by irradiation with active energy rays is, for example, that an acid derived from an acid generator is generated in a portion irradiated with active energy rays and In the case where the chemical structure of the core layer polymer is changed by cleavage or cross-linking due to the action of the acid, the portion irradiated with active energy rays along with the change of the chemical structure of the core layer polymer The refractive index of the material changes. In such a case, the chemical structure of the resin constituting the core layer precursor is different between the portion irradiated with the active energy ray and the non-irradiated portion, and portions having different refractive indexes are formed. In addition, even when the core layer forming varnish contains a monomer whose structure or the like is changed by the action of an acid derived from the acid generator, the core is composed of a portion irradiated with active energy rays and a portion not irradiated. A difference occurs in the chemical structure of the resin constituting the layer precursor, thereby forming a portion having a different refractive index.

  Next, if necessary, the film-shaped core layer 11a may be subjected to heat treatment. By such a heat treatment, the leaving group detached (cut) from the polymer is removed from, for example, the irradiated region, or rearranged or crosslinked in the polymer. Therefore, the refractive index difference between the core portion 111A and the clad portion 111B can be further increased by performing such heat treatment. Although the heating temperature in such heat processing is not specifically limited, It is preferable that it is about 70-195 degreeC, and it is more preferable that it is about 85-150 degreeC. The heating time may be set so that the leaving group detached (cut) from the irradiated region can be sufficiently removed, and is not particularly limited, but is preferably about 0.5 to 3 hours, 0 More preferably, it is about 5 to 2 hours.

  Thus, after forming a core layer precursor using the varnish for core layer formation on a base material, the core layer 11a is formed on a base material by selectively irradiating an active energy ray. Moreover, the film-like core layer 11a formed in this way can be peeled off from the substrate and used. Furthermore, in the core layer 11a formed in this way, in the step of forming the core part 111A and the clad part 111B, the monomer present in the clad part 111B at the time of irradiation with active energy rays is used for the reaction, and the clad part Since the monomer concentration in 111B becomes low, the monomer in the core part 111A tends to move toward the clad part 111B. Therefore, the composition continuously changes from the longitudinal center of the core portion 111A toward the cladding portion 111B, and a difference in hardness is formed inside the core portion 111A. Even when the mirror surface is formed on the optical waveguide obtained using the core layer forming varnish as described above, according to the present invention, the longitudinal direction of the surface of the core portion to be irradiated with the laser beam Since the laser beam is irradiated such that the irradiation time of the laser beam is shortened as the distance from the substantially central axis in the width direction of the surface decreases, the mirror surface can be made smoother.

  Next, a method for forming a film-like clad layer using the clad layer forming varnish will be described. A method for forming a clad layer using such a clad layer forming varnish is not particularly limited. For example, a method of forming a film-like clad layer on a substrate using a clad layer forming varnish is adopted. May be. In addition, as such a base material, the thing similar to the base material which can be used when forming a core layer can be used.

  As such a clad layer forming varnish, one containing a clad layer polymer is preferable. As such a cladding layer polymer, a resin is selected such that the refractive index of the second resin obtained from the cladding layer polymer is lower than the refractive index of the core when the cladding layer is formed. It may be used, and is not particularly limited. For example, cyclic olefin resins (including norbornene resins and benzocyclobutene resins), acrylic resins, methacrylic resins, polycarbonate resins, polystyrene resins, epoxy resin resins , Polyamide resins, polyimide resins, and polybenzoxazole resins, and one or more of these may be used in combination (polymer alloy, polymer blend (mixture), copolymer, etc.). . Among these, what mainly contains norbornene-type resin (norbornene-type polymer) is preferable. Such a norbornene-based polymer is not particularly limited, and a known norbornene-based polymer that can be used when forming the cladding layer can be appropriately used.

  Since such a norbornene-based polymer tends to have an excellent balance between heat resistance and adhesion, when this is used as a constituent material of the cladding layer 11b, heating is performed when a conductor layer or the like is formed in the optical waveguide. Even so, the cladding layer 11b tends to be sufficiently prevented from being softened and deformed. Further, since such norbornene-based polymer has high hydrophobicity, there is a tendency that a dimensional change due to water absorption of the clad layer 11b hardly occurs. Further, such a norbornene-based polymer is preferable because a norbornene-based monomer as a raw material thereof is relatively inexpensive and easily available.

  Further, in the clad layer forming varnish, by containing a norbornene polymer mainly in the clad layer polymer, the clad layer forming varnish has excellent resistance to deformation such as bending, and even when repeatedly bent and deformed, the interlayer between the clad layer 11b and the core layer 11a Peeling is unlikely to occur, and the occurrence of microcracks in the cladding layer 11b tends to be sufficiently prevented. Further, when a norbornene-based polymer is also used for the core layer 11a, the adhesion between the clad layer 11b and the core layer 11a becomes higher, and delamination between the clad layer 11b and the core layer 11a is further improved. It tends to be sufficiently prevented. By using the norbornene-based polymer in this way, it becomes possible to obtain an optical waveguide with excellent durability while maintaining the optical transmission performance of the optical waveguide sufficiently.

  Examples of such norbornene-based polymers include (1) addition (co) polymers of norbornene monomers obtained by addition (co) polymerization of norbornene monomers, and (2) norbornene monomers and ethylene or α-olefins. (3) addition polymers such as addition copolymers with norbornene-type monomers and non-conjugated dienes, and other monomers as required, (4) ring opening of norbornene-type monomers ( A (co) polymer, and a resin obtained by hydrogenating the (co) polymer if necessary, (5) a ring-opening copolymer of a norbornene-type monomer and ethylene or α-olefins, and ( (Co) polymer hydrogenated resin, (6) ring-opening copolymer of norbornene type monomer and non-conjugated diene or other monomer, and (co) polymerization if necessary And a ring-opening polymer such as a polymer obtained by hydrogenating the body. Examples of these polymers include random copolymers, block copolymers, and alternating copolymers. Among such norbornene-based polymers, addition (co) polymers are more preferable from the viewpoint of sufficient heat resistance and flexibility.

  Further, such a norbornene-based polymer may be selected appropriately from known norbornene-based monomers according to its design, and used in ring-opening metathesis polymerization (ROMP), a combination of ROMP and a hydrogenation reaction, radical or Manufactured using a known polymerization method such as polymerization using a cation, polymerization using a cationic palladium polymerization initiator, or polymerization using other polymerization initiators (for example, polymerization initiators of nickel and other transition metals). can do.

  Examples of such norbornene-based polymers include copolymers of butyl norbornene and methyl glycidyl ether norbornene, copolymers of hexyl norbornene and methyl glycidyl ether norbornene, copolymers of decyl norbornene and methyl glycidyl ether norbornene, and butyl norbornene and acrylic. Copolymer of 2- (5-norbornenyl) methyl acid, copolymer of hexylnorbornene and 2- (5-norbornenyl) methyl acrylate, copolymer of decylnorbornene and 2- (5-norbornenyl) methyl acrylate, and butylnorbornene Copolymer of norbornenylethyltrimethoxysilane, copolymer of hexylnorbornene and norbornenylethyltrimethoxysilane, decyl Copolymer of rubornene and norbornenylethyltrimethoxysilane, copolymer of butylnorbornene and triethoxysilylnorbornene, copolymer of hexylnorbornene and triethoxysilylnorbornene, copolymer of decylnorbornene and triethoxysilylnorbornene, butylnorbornene and trimethoxysilane Copolymers of methoxysilyl norbornene, copolymers of hexyl norbornene and trimethoxysilyl norbornene, copolymers of decyl norbornene and trimethoxysilyl norbornene, butyl norbornene, hexyl norbornene or decyl norbornene and 2- (5-norbornenyl) acrylate Methyl, norbornenylethyltrimethoxysilane, triethoxysilylnorbornene or Terpolymer with any of trimethoxysilyl norbornene, terpolymer of butyl norbornene, hexyl norbornene or decyl norbornene with 2- (5-norbornenyl) methyl acrylate and methyl glycidyl ether norbornene, butyl norbornene, hexyl norbornene or A terpolymer of any of decyl norbornene with methyl glycidyl ether norbornene, norbornenyl ethyl trimethoxysilane, triethoxysilyl norbornene or trimethoxysilyl norbornene, a copolymer of butyl norbornene and diphenylmethyl norbornene methoxysilane, hexyl norbornene and Copolymer with diphenylmethylnorbornene methoxysilane, decylnorbornene and di Examples thereof include a copolymer of phenylmethylnorbornene methoxysilane, a copolymer of butylnorbornene and phenylethylnorbornene, a copolymer of hexylnorbornene and phenylethylnorbornene, a copolymer of decylnorbornene and phenylethylnorbornene, and the like.

  Further, as such a norbornene-based polymer, a norbornene repeating unit having a side chain containing a polymerizable group, a norbornene repeating unit having a side chain containing an aryl group, and a norbornene having an alkyl group in the side chain Those containing at least one of the repeating units of (alkylnorbornene) are preferable, and those containing at least one repeating unit of norbornene having a side chain containing a polymerizable group are more preferable.

  In the case of including a norbornene repeating unit having a side chain containing such a polymerizable group, the norbornene polymers in the cladding layer 11b may be crosslinked directly or via a crosslinking agent with the polymerizable group, Depending on the type of polymer used for the core layer 11a, the polymer used for the core layer 11a and the norbornene-based polymer can be cross-linked, and the strength of the clad layer 11b itself and the adhesion between the clad layer 11b and the core layer 11a can be improved. Further improvement can be achieved. Moreover, as such a side chain polymerizable group, at least one of an epoxy group, a (meth) acryl group, and an alkoxysilyl group is preferable from the viewpoint of reactivity. In the norbornene-based polymer, the norbornene repeating unit having a polymerizable group in the side chain may contain only one type of repeating unit, or two or more types each having a different polymerizable group. It may contain a repeating unit. Among them, the crosslinking density can be further improved, and the above effect becomes more remarkable. Therefore, the repeating unit contains two or more kinds of norbornene repeating units each having a different polymerizable group. It is preferable.

  In addition, when the norbornene-based polymer includes a norbornene repeating unit having a side chain containing an aryl group, the aryl group has extremely high hydrophobicity, and therefore tends to prevent a change in dimensions of the cladding layer 11b due to water absorption. is there. In addition, since the aryl group is excellent in lipophilicity (lipophilicity), the affinity with the polymer used for the core layer 11a can be improved, thereby delamination between the clad layer 11b and the core layer 11a. Therefore, it is possible to obtain an optical waveguide with higher durability.

  Furthermore, when the norbornene-based polymer contains an alkylnorbornene repeating unit, the transmittance for light in the wavelength region of about 600 to 1550 nm (particularly in the wavelength region near 850 nm) tends to be excellent. There is a tendency that the flexibility becomes high and high flexibility (flexibility) can be imparted to the clad layer 11b. In addition, the alkyl group of the side chain in the repeating unit of such an alkyl norbornene is the same as the alkyl group in the alkyl norbornene described in the polymer for the core layer. Further, by including such a repeating unit of alkyl norbornene, it is possible to prevent an increase in the refractive index of the clad layer even when it further includes a repeating unit of norbornene having a side chain containing an aryl group having a relatively high refractive index. Is possible.

  Among such norbornene-based polymers, those containing a norbornene repeating unit having an alkyl group in the side chain (an alkylnorbornene repeating unit) and a norbornene repeating unit having a side chain containing a polymerizable group Among these, the following general formula (2) containing a repeating unit of alkylnorbornene and a repeating unit of norbornene having a side chain containing an epoxy group:

[Wherein, R represents an alkyl group, a represents an integer of 0 to 3, b represents an integer of 1 to 3, p and q may be the same or different, and each represents 20 or less. Indicates an integer. ]
A norbornene-based polymer having a structure represented by: In the formula, the alkyl group represented by R is the same as the alkyl group in the side chain in the repeating unit of the alkylnorbornene.

  Among the norbornene-based polymers having the repeating unit represented by the general formula (2), R is an alkyl group having 4 to 10 carbon atoms, and a and b are each 1 (for example, butylnorbornene and More preferred are copolymers of methyl glycidyl ether norbornene, copolymers of hexyl norbornene and methyl glycidyl ether norbornene, and copolymers of decyl norbornene and methyl glycidyl ether norbornene.

  Further, when a norbornene-based polymer is mainly used for the cladding layer polymer, the content ratio of the norbornene-based polymer in the cladding layer polymer is preferably 80 to 100% by mass, more preferably 95 to 100% by mass. preferable. When such a content ratio is less than the lower limit, the effect obtained by using the norbornene-based polymer tends to be insufficient.

  In addition, the clad layer forming varnish may further contain an acid generator, an acid neutralizer, a monomer, a procatalyst, a sensitizer, and an antioxidant, if necessary, in addition to the polymer for the clad layer. May be. Such an acid generator, monomer, procatalyst, sensitizer, and antioxidant are the same as those described in the varnish for forming the core layer. Further, the clad layer forming varnish has other known additives (for example, a crosslinking agent and an antifoaming agent) that can be used for forming the clad layer within a range that does not impair the effect of the clad layer to be formed. , Adhesion aids, etc.) may be included as appropriate. Moreover, it does not restrict | limit especially as such an acid neutralizer, What is necessary is just to use what can neutralize the acid generated with the said acid generator. Examples of such an acid neutralizing agent include amine compounds.

  In addition, the method for producing such a clad layer forming varnish is not particularly limited, and a known method can be appropriately employed. The core layer described above is used except that the polymer for the clad layer is used instead of the polymer for the core layer. A method basically similar to the method for producing the forming varnish can be employed.

  Further, the content ratio of the clad layer polymer in the clad layer forming varnish is not particularly limited, but is preferably 5 to 40% by mass, and more preferably 10 to 35% by mass. If the content ratio of the polymer for the cladding layer is less than the lower limit, the viscosity is too low and it tends to be difficult to form a cladding layer having a desired thickness. On the other hand, if the content exceeds the upper limit, the viscosity is too high. Therefore, it is easy to entrain bubbles at the time of application, and the production efficiency tends to decrease.

  Moreover, when an acid generator is contained in the varnish for forming a clad layer, the content ratio of the acid generator is preferably 0.01 to 10% by mass, and preferably 0.1 to 5% by mass. It is more preferable. If the content ratio of the acid generator is less than the lower limit, the effect obtained by containing the acid generator tends to be insufficient. On the other hand, if the content exceeds the upper limit, the acid generator may be completely neutralized. It tends to be difficult.

  Moreover, when an acid neutralizing agent is contained in the clad layer forming varnish, the content of the acid neutralizing agent is 0.01 to 50 parts by mass with respect to 100 parts by mass of the polymer for the clad layer. Is preferable, and it is especially preferable that it is 0.1-20 mass parts. If the content of such an acid neutralizing agent is less than the lower limit, it tends to be difficult to sufficiently neutralize the acid present in the optical waveguide. On the other hand, if the content exceeds the upper limit, Toughness and heat resistance tend to decrease.

  Furthermore, the viscosity (normal temperature) of the clad layer forming varnish is not particularly limited, and can be appropriately adjusted according to a coating method and a desired film thickness. Such a clad layer forming varnish has a viscosity (normal temperature) of preferably 100 to 10000 cP, more preferably 150 to 5000 cP, and still more preferably 200 to 3500 cP.

  The method for applying the clad layer forming varnish on the substrate is not particularly limited. For example, doctor blade method, spin coating method, dipping method, table coating method, spray method, applicator method, curtain coating method, die coating Methods such as law are listed.

  Thus, a clad layer can be obtained by apply | coating the varnish for clad layer formation. Further, the thickness of the coating film (cladding layer) formed by applying such a varnish for forming a cladding layer can be appropriately changed according to the design of the optical waveguide, and is not particularly limited. In this state, the thickness may be about 5 to 200 μm, preferably about 15 to 125 μm.

  Further, in such a film-like clad layer forming step, it is preferable to remove at least a part of the solvent after applying the clad layer forming varnish. As the step of removing the solvent (solvent removal step), a known method can be appropriately employed. For example, natural drying, a method of heating, a method of leaving under reduced pressure, or blowing an inert gas ( (Blow) method and a method of evaporating the solvent using a dryer. The film-like clad layer thus obtained may be used after being peeled off from the substrate, or may be used in a state of being laminated on the substrate.

  Next, a method for laminating a film-like core layer and a film-like clad layer will be described. A method for laminating such a film-like core layer and a film-like clad layer is not particularly limited, and a known method capable of laminating these layers can be appropriately employed. For example, a laminator can be used. A method of laminating a film-like clad layer on one surface of the film-like core layer may be employed. Thus, the optical waveguide 11 can be obtained by laminating the clad layer on one surface of the core layer. In addition, in the manufacturing process of such an optical waveguide 11, you may heat-process after the said lamination process. The conditions for such heat treatment are not particularly limited, but it is more preferable to heat at a temperature of 100 to 200 ° C. (more preferably 150 to 180 ° C.) for about 0.5 to 1.5 hours. If the temperature and time of the heating step are less than the lower limit, curing of the clad layer tends not to proceed sufficiently, whereas if the upper limit is exceeded, chemical deterioration of the core layer tends to proceed.

  The preferred embodiment of the manufacturing method of the optical waveguide with a mirror of the present invention has been described above, but the manufacturing method of the optical waveguide with a mirror of the present invention is not limited to the above embodiment. For example, in the above embodiment, the structure of the optical waveguide 11 used for forming the mirror surface 12 is a two-layer structure of a clad layer / core layer. The optical waveguide used for forming the mirror surface 12 only needs to include at least the core layer 11a, and the structure thereof is not particularly limited. For example, a three-layer structure of cladding layer / core layer / cladding layer, cladding A four-layer structure of layer / core layer / cladding layer / core layer may be used. The method for producing such a multilayered optical waveguide is not particularly limited, and a known method can be used as appropriate.

  Here, for example, a method of manufacturing an optical waveguide with a mirror when using an optical waveguide having a three-layer structure of clad layer / core layer / cladding layer will be described. A process of forming a mirror surface for such a three-layered optical waveguide is shown in FIG. In the embodiment shown in FIG. 6, when forming the mirror surface 12, the cladding layer 11 b existing on the upper surface side of the core layer 11 a is also irradiated with the laser beam LB, and the part of the mirror surface 12 is formed. A method similar to the method employed in the above embodiment is employed except that the step of removing the resin component of the cladding layer existing on the upper side is performed. That is, in the embodiment shown in FIG. 6, first, the laser beam LB is irradiated to the upper cladding layer 11b through the opening 13a of the mask 13, and the light transmission direction of the core portion of the optical waveguide 11 (see FIG. 6). 6 (direction indicated by arrow A in FIG. 6) (FIG. 6A). When the laser beam LB is continuously irradiated while moving the optical waveguide 11, a part of the upper clad layer 11b is removed by irradiation with the laser beam LB, and the laser beam LB is applied to the core layer 11a at that portion. Is irradiated (FIG. 6B). At this time, as described above, the laser beam LB is shortened such that the irradiation time of the laser beam decreases as the distance from the substantially central axis in the longitudinal direction of the surface to be irradiated with the laser beam in the core portion increases in the width direction of the surface. To the core. Thus, the method of irradiating the laser beam such that the irradiation time of the laser beam becomes shorter as the distance from the substantially central axis in the longitudinal direction of the surface to be irradiated with the laser beam of the core portion increases in the width direction of the surface For example, a method similar to the method described in the above embodiment may be employed. In the region where the laser beam of the core part is irradiated, the resin component is continuously removed in the depth direction of the core part according to the reach of the laser beam LB, and the light transmitted through the core part The mirror surface 12 inclined with respect to the transmission direction is formed on the core part (FIG. 6C).

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
<Process for producing polymer for core layer>
First, a polymer for the core layer was produced. That is, first, hexyl norbornene (HxNB) (8.94 g, 0.05 mol), diphenylmethyl norbornene methoxysilane (diphNB) (16.1 g, 0.05 mol), 1-hexene (4.2 g, 0.05 mol) and Toluene (142.0 g) was mixed in a 250 mL sealam bottle and heated to 120 ° C. in an oil bath to form a solution. Next, [Pd (PCy ₃ ) ₂ (O ₂ CCH ₃ ) (NCCH ₃ )] tetrakis (pentafluorophenyl) borate (Pd1446) (5.8 × 10 ⁻³ g, 4.0 × 10) was added to the solution. ⁻⁶ mol) and N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate (DANFABA) (3.2 × 10 ⁻³ g, 4.0 × 10 ⁻⁶ mol) were respectively added to a concentrated dichloromethane solution (0. 1 mL) to obtain a mixed solution. Subsequently, after maintaining the said mixed liquid at 120 degreeC for 6 hours, methanol was dripped, stirring vigorously, and the deposit was obtained. Thereafter, the precipitate (copolymer) thus obtained was collected by filtration and vacuum-dried in an oven at 80 ° C. to give a dry mass of 12.0 g (yield 48%) of the product (copolymer: Polymer for core layer) was obtained.

  When the molecular weight of such a product (copolymer) was measured by GPC in a THF solvent (polystyrene conversion), Mw was 16196 and Mn was 8448. Moreover, when the composition of such a product (copolymer) was measured by 1H-NMR, it was a 54/46 HxNB / diPhNB copolymer on a molar basis. Furthermore, when the refractive index of such a copolymer was measured by the prism coupling method, it was 1.5569 in the TE mode and 1.5555 in the TM mode at a wavelength of 633 nm.

<Manufacturing process of varnish for core layer formation>
First, the product (core layer polymer) obtained as described above was dissolved in mesitylene to prepare a 30 wt% resin solution. Next, to the resin solution (10.0 g), bis-norbornenemethoxydimethylsilane (SiX, CAS number: No. 376609-87-9) (0.72 g, 0.00245 mol) and Pd (PCy ₃ ) ₂ ( OAc) ₂ (Pd785) (4.94 × 10 ⁻⁴ g, 6.29 × 10 ⁻⁷ mol, in 0.1 mL of methylene chloride), RHODORSIL (registered trademark) PHOTOINITIATOR 2074 (CAS number: 178233-72— 2, obtained from Rhodia Inc, Cranberry, NJ) (2.55 × 10 ⁻³ g, 2.516 × 10 ⁻⁶ mol, in 0.1 mL of methylene chloride) and mixed uniformly, 0.2 The mixture was filtered through a micron pore filter to obtain a varnish for forming a core layer.

<Core layer forming step>
The core layer-forming varnish was uniformly applied onto a release-treated PET film with a doctor blade to form a coating film (thickness before drying: 140 μm). Next, the coating film is put together with a PET film in a dryer and put into a dryer at 45 ° C. for 15 minutes to completely remove the solvent (mesitylene), and then a photomask having a predetermined opening pattern is pressure-bonded, The coating film was selectively irradiated with ultraviolet rays (irradiation amount 500 mJ / cm ² ). Next, the pressure-bonded mask is removed, and the coating film after ultraviolet irradiation is put into a dryer together with a PET film, heated at 45 ° C. for 30 minutes, then heated at 85 ° C. for 30 minutes, and further heated at 150 ° C. for 1 hour, A layer was formed. Note that it was confirmed that a very clear waveguide pattern was formed after such heating. Subsequently, the core layer was obtained by peeling off the obtained film-form core layer from the mold release process PET film. Such a core layer was colorless and transparent, the refractive index of the core part was 1.5695 (measurement wavelength; 633 nm), and the refractive index of the cladding part was 1.5153 (measurement wavelength; 633 nm).

<Manufacturing process of varnish for forming clad layer>
A norbornene resin composition containing a cyclic olefin resin as the second resin (Avatrel 2590, 20% by weight 2-heptanone solution, 10 g, manufactured by Promeras Co., Ltd.) was used. 4-methylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd., product number 2E4MZ) (0.04 g) was added to produce a varnish for forming a cladding layer.

<Clad layer formation process>
After the clad layer forming varnish is uniformly applied on a polyimide film (Ubex Corporation, Upilex) with a doctor blade, it is put into a dryer at 45 ° C. for 15 minutes to completely dissolve the solvent (2-heptanone). After removing, heating at 160 ° C. in a dryer for 2 hours to cure the coating film, forming a film-like cladding layer on the polyimide film, and then peeling from the polyimide film, Obtained. The thickness of the obtained film-like clad layer was 20 μm. Moreover, such a clad layer was colorless and transparent, and its refractive index was 1.52 (measurement wavelength: 633 nm). Two such film-like clad layers were produced.

<Manufacture of optical waveguide>
A clad layer is laminated on each side of the core layer obtained as described above, put into a laminator set at 140 ° C., and laminated in the order of clad layer / core layer / cladding layer at 150 ° C. It heated for 0.5 hour and obtained the optical waveguide before the mirror process laminated | stacked in order of the clad layer / core layer / cladding layer.

<Excimer laser adjustment>
Prior to forming the mirror surface in the core portion of the optical waveguide before mirror processing, an excimer laser device (manufactured by OPTEC, product name “ATLEX-300i”) was adjusted as follows. After exhausting the pressure in the chamber provided in the excimer laser device to 10 mbar or less once, ArF premix gas (Ar: 4.13%, F2: 0.17%, neon gas: remainder) ) Until 6500 mbar. Moreover, after adjusting the beam irradiation energy to be within the range of 300 to 400 mJ / pulse using a power meter (manufactured by OPHIR, product name “NOVA II”), a beam profiler (manufactured by Spiricon, product name “ LASER BEAM PROFILERS G3 ") and adjusted so that there is no bias in intensity distribution. In the excimer laser device, after passing through a stainless steel mask in which an oval hole (opening) in which two linear portions are 500 μm and the radius of curvature of the arc on the longitudinal side edge is 500 μm is formed, a lens is further added. As shown in FIG. 7, the irradiation surface shape formed on the surface of the core layer 11a of the laser beam finally focused on the core layer 11a after being condensed and reduced and projected through The straight line portions (the line segment connecting the point T1 and the point T4 and the line segment connecting the point T2 and the point T3) are 100 μm, respectively, and the arc of the longitudinal end (the curved line unit connecting the point T1 and the point T2) The curved portion connecting the points T3 and T4) was adjusted to have an elliptical shape in which the radius of curvature was 100 μm.

<Mirror processing>
The surface of one clad layer of the optical waveguide (core thickness: 50 μm, core width: 50 μm) before mirror processing is placed on an adhesive substrate (trade name “Magic Resin” manufactured by Toyo Corporation). Pasted. Next, the base was placed on a fine movement stage of an excimer laser device, and the fixed surface of the base was sucked and fixed. Then, after adjusting the alignment by rotating the stage so that the longitudinal direction of the core portion of the optical waveguide before mirror processing and the movable direction of the fine movement stage coincide with each other, as shown in FIG. The center axis O in the longitudinal direction was adjusted so as to overlap the center axis in the longitudinal direction of the core part. Next, under the condition that He gas is flowed at 2.0 L / min as the assist gas, the fine movement stage is moved for 10 seconds (150 μm) at a speed of 15 μm / second in the light transmission direction of the core as shown in FIG. However, the optical waveguide was irradiated with a laser having a frequency of 100 Hz to form a mirror surface in the core portion. When the optical waveguide moved 150 μm, the laser irradiation was terminated to obtain an optical waveguide with a mirror. In addition, the angle with respect to the optical axis of the core part of the mirror surface formed in this way was 45 degrees.

(Example 2)
Regarding the laser beam used for the mirror processing, the irradiation surface shape of the laser beam finally irradiated on the core layer is 100 μm for each of the two straight portions, and the radius of curvature of the arc at the end in the longitudinal direction is both 125 μm. An optical waveguide with a mirror was obtained in the same manner as in Example 1 except that it was adjusted to have an oval shape (a shape as indicated by a dotted line in FIG. 7). In addition, the angle with respect to the optical axis of the core part of the mirror surface formed in this way was 45 degrees. FIG. 8 shows a micrograph of the thin film on which the mirror surface thus formed is formed.

(Comparative Example 1)
When adjusting the excimer laser used at the time of the mirror processing, a stainless steel mask having a square hole with a length of 500 μm on each side is used, and the shape of the irradiated surface of the laser beam finally irradiated onto the core layer is changed. An optical waveguide with a mirror was obtained in the same manner as in Example 1 except that the mirror surface was manufactured as a square having a side of 100 μm. In addition, the angle with respect to the optical axis of the core part of the mirror surface formed in this way was 45 degrees. A micrograph of the thin film on which the mirror surface thus formed is formed is shown in FIG.

[Evaluation of performance of optical waveguide with mirror obtained in Examples 1 and 2 and Comparative Example 1]
<Measurement of curvature under mirror surface>
The curvature of the portion of the mirror surface of the optical waveguide with a mirror obtained in Examples 1 and 2 and Comparative Example 1 in contact with the cladding layer (the lowermost edge of the mirror surface of the core portion) is shown in the laser microscope image. Measured based on. The results are shown in Table 1.

  As is clear from the results shown in Table 1, in the optical waveguides (Examples 1 and 2) obtained by employing the method for manufacturing an optical waveguide with a mirror according to the present invention, the conventional method for manufacturing a mirror surface is used. It was confirmed that the value of the curvature was sufficiently low as compared with the optical waveguide obtained by the adoption (Comparative Example 1), and the mirror surface was flatter.

  Further, as is apparent from the micrographs shown in FIGS. 8 and 9, in the optical waveguide (Example 2) obtained by employing the manufacturing method of the optical waveguide with a mirror of the present invention, the conventional mirror surface is used. It can be seen that the curvature of the mirror surface is further corrected and the mirror surface is flatter than the optical waveguide (Comparative Example 1) obtained by adopting this manufacturing method.

<Measurement of optical loss at mirror surface>
The optical loss in the mirror surface of the optical waveguide with a mirror obtained in Examples 1 and 2 and Comparative Example 1 was measured by the following method. That is, the light generated from the surface emitting laser (VCSEL) is input from one end of the core through the optical fiber, the output of the light emitted from the mirror surface is measured, and the total light represented by the following formula (F1) Loss (insertion loss) was determined.
Total optical loss (dB) = − 10 · log (P1 / P0) (F1)
In the above formula, P1 is the output of light emitted from the mirror surface, and P0 is the measurement output of the light source at the end of the optical fiber before coupling the optical fiber to one end of the core. The results are shown in Table 2.

  As is apparent from the results shown in Table 2, in the optical waveguides (Examples 1 and 2) obtained by adopting the method for manufacturing an optical waveguide with a mirror according to the present invention, the total optical loss (insertion loss) was obtained. ) Is 1.25 dB or less, confirming that the optical waveguide has a sufficiently high optical transmission performance. On the other hand, in the optical waveguide (Comparative Example 1) obtained by adopting the conventional mirror surface manufacturing method, the total light loss (insertion loss) is 1.50 dB, and the loss of light on the mirror surface is sufficient. It turns out that it cannot be suppressed.

  As described above, according to the present invention, an optical waveguide with a mirror capable of efficiently producing an optical waveguide with a mirror including a core portion on which a mirror surface capable of sufficiently suppressing light loss is formed. It is possible to provide a method for manufacturing a waveguide. Therefore, the present invention is very useful as a technique related to high density optical wiring.

  DESCRIPTION OF SYMBOLS 11 ... Optical waveguide, 11a ... Core layer, 11b ... Cladding layer, 111A ... Core part, 111B ... Cladding part, 12 ... Mirror surface, 13 ... Mask, 13a ... Opening of mask, LB ... Laser beam, A ... Core part , The width direction, P1 to P4, arbitrary points on the core layer, S, the surface to be irradiated with the laser beam, C, the central axis in the longitudinal direction of the core portion, O, the core layer The central axis in the longitudinal direction of the core portion of the laser beam irradiation surface shape on the surface, E1 to E6... Points on the irradiation surface shape of the laser beam on the surface of the core portion, F1. Irradiation surface shape, T1 to T4: Points on the periphery of the laser beam irradiation surface shape on the surface of the core layer.

Claims (2)

A part of the core part of the optical waveguide having a core part for transmitting light containing a resin component is irradiated with a laser beam through a mask having an opening, and a part of the core part is irradiated. A method of manufacturing an optical waveguide with a mirror that forms a mirror surface on the core portion that is inclined with respect to a transmission direction of light transmitted through the core portion by scattering the resin component,
Irradiating the laser beam such that the irradiation time of the laser beam is shortened as the distance from the substantially central axis in the longitudinal direction of the surface to be irradiated with the laser beam of the core portion increases in the width direction of the surface; and
At the time of irradiation with the laser beam, at least one end side in the longitudinal direction of the core portion of the region on the surface of the core portion irradiated with the laser beam has an arc shape with a curvature radius of 100 to 250 μm;
A manufacturing method of an optical waveguide with a mirror characterized by the above. The method of manufacturing an optical waveguide with a mirror according to claim 1, wherein the shape of the opening of the mask is circular, elliptical, or oval.