JP2012194285A - Optical waveguide, evaluation method, optical waveguide structure, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical waveguide of which the state can be evaluated after formation of the optical waveguide, and a highly reliable optical waveguide structure and a highly reliable electronic apparatus which includes the optical waveguide.SOLUTION: The optical waveguide structure includes a core part 211, a core part 213 for evaluation, and a clad part 212. The clad part 212 includes a low-refractive index region 215 having a lower refractive index than the core part 211 and being in contact with at least one of the core part 211 and the core part 213 for evaluation and a plurality of high-refractive index regions 214 having a higher refractive index than the low-refractive index region 215 and spaced from the core part 211 and the core part 213 for evaluation with the low-refractive index region 215 therebetween. The plurality of high-refractive index regions 214 are scattered or arrayed in the clad part 212, and the core part 211 is provided so that at least its one end in an optical path direction is not exposed in an end surface of an optical waveguide 20.

Description

  The present invention relates to an optical waveguide, an evaluation method, an optical waveguide structure, and an electronic device.

  In recent years, with the wave of computerization, wideband lines (broadband) capable of communicating a large amount of information at high speed have been spreading. Also, as devices for transmitting information to these broadband lines, transmission devices such as router devices and WDM (Wavelength Division Multiplexing) devices are used. In these transmission apparatuses, a large number of signal processing boards in which arithmetic elements such as LSIs and storage elements such as memories are combined are installed, and each line is interconnected.

  Each signal processing board has a circuit in which arithmetic elements, storage elements, etc. are connected by electrical wiring. However, with the increase in the amount of information to be processed in recent years, each board has a very high throughput. It is required to transmit. However, with the speeding up of information transmission, problems such as generation of crosstalk and high frequency noise and deterioration of electric signals are becoming apparent. For this reason, electrical wiring becomes a bottleneck, making it difficult to improve the throughput of the signal processing board. Similar problems are also becoming apparent in supercomputers and large-scale servers.

  On the other hand, an optical communication technique for transferring data using an optical carrier wave has been developed, and in recent years, an optical waveguide is becoming popular as a means for guiding the optical carrier wave from one point to another point. This optical waveguide has a linear core part and a clad part provided so as to cover the periphery thereof. The core part is made of a material that is substantially transparent to the light of the optical carrier wave, and the cladding part is made of a material having a refractive index lower than that of the core part.

  In the optical waveguide, light introduced from one end of the core portion is transmitted (conveyed) to the other end while being reflected at the boundary with the cladding portion. A light emitting element such as a semiconductor laser is disposed on the incident side of the optical waveguide, and a light receiving element such as a photodiode is disposed on the emission side. Light incident from the light emitting element propagates through the optical waveguide, is received by the light receiving element, and performs communication based on the flickering pattern of the received light or its intensity pattern.

  By replacing the electric wiring in the signal processing board with such an optical waveguide, it is expected that the problem of the electric wiring as described above is solved and the signal processing board can be further increased in throughput.

  For example, Patent Document 1 proposes a signal processing board in which a plurality of optical waveguides and light-emitting elements and light-receiving elements are arranged corresponding to the respective optical waveguides. In this signal processing board, a plurality of optical waveguides are formed in the signal processing board by disposing clad parts that are in contact with each other between adjacent core parts.

  In the signal processing board having such a configuration, as the density and size of the signal processing board are increased, the distance between the adjacent core portions becomes closer. As a result, the optical waveguide formation stage, the light emitting element and the light receiving element with respect to the optical waveguide In a process such as mounting, adjacent core parts come into contact with each other, and there is a problem that a rejected product is generated.

  For this reason, in each manufacturing stage of a signal processing board having an optical waveguide, a configuration of the optical waveguide capable of evaluating the state of the optical waveguide has been studied.

JP 2009-139412 A

  An object of the present invention is to provide an optical waveguide capable of evaluating the state of the optical waveguide after the optical waveguide is formed, a highly reliable optical waveguide structure including the optical waveguide, and a highly reliable electronic device. is there.

Such an object is achieved by the present invention described in the following (1) to (13).
(1) An optical waveguide having a flat plate shape used for transmitting light,
A core portion, an evaluation core portion provided in parallel with the core portion, and a clad portion provided adjacent to at least one of the core portion and the evaluation core portion,
The cladding portion has a refractive index lower than that of the core portion, a low refractive index region in contact with at least one of the core portion and the evaluation core portion, a refractive index higher than the low refractive index region, and the low refractive index region. A plurality of high refractive index regions spaced from the core portion and the evaluation core portion via a refractive index region, and the plurality of high refractive index regions are scattered or aligned in the cladding portion. ,
The optical waveguide is characterized in that at least one end portion in the optical path direction of the core portion is provided without being exposed at an end surface of the optical waveguide.

(2) having a plurality of the core part and the evaluation core part,
The said evaluation core part and the said core part are the optical waveguides as described in said (1) currently arranged in parallel by turns via the said clad part.

  (3) The said evaluation core part is an optical waveguide as described in said (1) or (2) from which the both ends of the optical path direction are exposed in the end surface of the said optical waveguide.

  (4) The optical waveguide according to any one of (1) to (3), wherein an optical path changing unit that changes a direction of the optical path is provided at at least one end of the core unit.

  (5) The optical waveguide according to any one of (1) to (4), wherein the evaluation core part has a central axis provided in parallel to the core part.

  (6) In the above (1) to (5), the plurality of high refractive index regions refract light passing through the cladding part in a direction away from the core part or irregularly scatter the light. The optical waveguide according to any one of the above.

  (7) The optical waveguide according to any one of (1) to (6), wherein each of the high refractive index regions is granular.

  (8) The optical waveguide according to any one of (1) to (6), wherein each of the high refractive index regions has a strip shape.

(9) The core portion, the evaluation core portion, the high refractive index region, and the low refractive index region,
Actinic radiation is applied to a layer containing a polymer and a monomer having a refractive index different from that of the polymer, and the reaction of the monomer proceeds in an irradiation region irradiated with the active radiation. The unreacted monomer is diffused from the unirradiated region that is not irradiated to the irradiated region, and as a result, a difference in refractive index is generated between the irradiated region and the unirradiated region, whereby the irradiated region and the The above (1) to (8) are formed by using any one of the unirradiated regions as the core portion, the evaluation core portion, and the high refractive index region and the other as the low refractive index region. The optical waveguide according to any one of the above.

  (10) The state of the core part included in the optical waveguide according to any one of (1) to (9) above is obtained by introducing light into the evaluation core part from one end and deriving from the other end. An evaluation method for evaluating by measuring strength.

  (11) An optical waveguide structure comprising the optical waveguide according to any one of (1) to (9).

  (12) The optical waveguide structure according to (11), including an optical element including a light emitting unit or a light receiving unit.

  (13) An electronic apparatus comprising the optical waveguide structure according to (11) or (12).

  According to the present invention, it is possible to evaluate the state of the optical waveguide (particularly the core layer) after the optical waveguide is formed. Therefore, since only the optical waveguide determined to be an acceptable product can be used for manufacturing the optical waveguide structure and the electronic device, a highly reliable optical waveguide structure and electronic device can be obtained.

  Furthermore, it becomes possible to evaluate the state of the optical waveguide structure (particularly the core layer) in the manufactured optical waveguide structure and electronic equipment.

It is a longitudinal cross-sectional view which shows the outline of 1st Embodiment of the optical waveguide structure of this invention. It is a top view which shows the outline of 1st Embodiment of the optical waveguide structure of this invention. It is a top view which shows the core layer with which the optical waveguide structure shown in FIG. It is the sectional view on the AA line of the core layer shown in FIG. It is a fragmentary longitudinal cross-sectional view for demonstrating the manufacturing process of the optical waveguide board | substrate with which an optical waveguide structure is provided. It is a fragmentary longitudinal cross-sectional view for demonstrating the manufacturing process of the optical waveguide board | substrate with which an optical waveguide structure is provided. It is a fragmentary longitudinal cross-sectional view for demonstrating the manufacturing process of the optical waveguide board | substrate with which an optical waveguide structure is provided. It is a top view which shows the core layer with which the manufactured optical waveguide board | substrate is provided. It is a top view which shows the core layer with which 2nd Embodiment of the optical waveguide structure of this invention is provided.

  Hereinafter, the optical waveguide, the evaluation method, the optical waveguide structure, and the electronic device of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

  First, prior to describing the optical waveguide of the present invention, an optical waveguide structure including the optical waveguide of the present invention (optical waveguide structure of the present invention) will be described.

<First Embodiment>
First, a first embodiment of the optical waveguide structure of the present invention will be described.

  FIG. 1 is a longitudinal sectional view showing an outline of the first embodiment of the optical waveguide structure of the present invention, FIG. 2 is a plan view showing the outline of the first embodiment of the optical waveguide structure of the present invention, and FIG. FIG. 4 is a plan view showing a core layer provided in the optical waveguide structure shown in FIGS. 1 and 2, and FIG. In the following description, the upper side in FIGS. 1 and 4 is referred to as “upper”, and the lower side is referred to as “lower”.

  The optical waveguide structure 1 mainly includes an optical waveguide substrate 2, wiring substrates 3a and 3b bonded to the upper surface of the optical waveguide substrate 2, light emitting elements 4 mounted on the wiring substrates 3a and 3b, and light emission, respectively. The device IC 40 includes a light receiving element 5 and a light receiving element IC 50.

  Light L from the light emitting element 4 is transmitted through the optical waveguide substrate (optical circuit) 2 and received by the light receiving element 5. That is, optical communication is performed between the light emitting element 4 and the light receiving element 5 through the optical waveguide substrate 2.

  The optical waveguide substrate 2 includes an optical waveguide 20 and protective layers 29 provided on the upper and lower surfaces of the optical waveguide 20, respectively.

  The optical waveguide (optical waveguide of the present invention) 20 has a flat plate shape as a whole, a layered core layer 21, and a layered clad layer 22 provided on the upper and lower surfaces of the core layer 21, respectively. have. Then, the light L incident on one end of the core layer 21 is transmitted (propagated) to the other end. The present invention is characterized by the structure of the optical waveguide 20 (particularly the core layer 21), and details thereof will be described later.

  Further, in the present embodiment, the optical waveguide substrate 2 has a defect portion 28a formed by losing a portion from the lower surface to the upper protective layer 29 beyond the core layer 21 (core portion 211), 28b. At least the surfaces of the core layer 21 facing the defect portions 28a and 28b are mirrors that reflect light based on the refractive index difference between the core layer 21 and the air in the defect portions 28a and 28b (optical paths that change the optical path of light). (Change part) 23a, 23b is comprised.

  Thereby, the mirrors 23a and 23b of the core part 211 form the end part of the core part 211, and the defect parts 28a and 28b as air layers are located in the peripheral part of the mirrors 23a and 23b.

  Further, the defect portions 28 a and 28 b are formed so as to form a right triangle in the longitudinal section of the optical waveguide substrate 2, and the mirrors (optical path changing portions) 23 a and 23 b are approximately the center axis of the core layer 21. Inclined at 45 °. Therefore, as indicated by the arrow in FIG. 1, the light L emitted downward from the light emitting element 4 is changed (bent) by 90 ° by the mirror 23a immediately below the light L, and then the core The light is transmitted through the layer 21 (core portion 211), and the light path is changed upward by about 90 ° by the mirror 23 b directly below the light receiving element 5, and then enters the light receiving element 5.

  By providing such mirrors 23a and 23b, the main surface (upper surface and / or lower surface) of the optical waveguide substrate 2 can be used as a region for mounting the light emitting element 4 and the light receiving element 5, so that the optical waveguide structure 1 This contributes to high-density packaging.

The protective layer 29 has a function of protecting the upper and lower surfaces of the optical waveguide 20.
Although the average thickness of the protective layer 29 is not specifically limited, It is preferable that it is about 5-200 micrometers, and it is more preferable that it is about 10-100 micrometers. Thereby, the protective layer 29 can sufficiently exhibit the function of protecting the optical waveguide 20. Moreover, when providing flexibility as the entire optical waveguide substrate 2, it is possible to prevent the flexibility from being lowered.

  The constituent material of the protective layer 29 is not particularly limited, and examples thereof include polyimide, polyimide amide, polyimide amide ether, polyester imide, and polyimide ether.

  Wiring substrates 3a and 3b are bonded to the upper surface of such an optical waveguide substrate 2, and the upper surfaces of the wiring substrates 3a and 3b correspond to core portions 211 provided in the core layer 21 described later, respectively. The light emitting element 4 and the light emitting element IC 40, and the light receiving element 5 and the light receiving element IC 50 are mounted.

  The wiring boards 3a and 3b have wiring portions (conductor portions) 30 formed in a predetermined pattern.

  The light emitting element (optical element) 4 includes an element main body 41 including a light emitting unit and a bump 42, and the bump 42 is bonded to a terminal included in the wiring unit 30. The light emitting element IC 40 includes an element body 401 and a bump 402 on which a predetermined circuit is formed, and the bump 402 is joined to a terminal included in the wiring unit 30. Thus, the light emitting element 4 is electrically connected to the light emitting element IC 40 via the wiring boards 3a and 3b, and the operation thereof is controlled by the light emitting element IC 40.

  Further, the light receiving element (optical element) 5 includes an element main body 51 including a light receiving unit and a bump 52, and the bump 52 is bonded to a terminal included in the wiring unit 30. The light receiving element IC 50 includes an element body 501 on which a predetermined circuit is formed and a bump 502, and the bump 502 is bonded to a terminal of the wiring unit 30. Thus, the light receiving element 5 is electrically connected to the light receiving element IC 50 via the wiring boards 3a and 3b, and the light receiving element IC 50 operates to amplify the detection signal from the light receiving element 5.

  Thereby, an electric circuit is constructed in the optical waveguide structure 1, and in the optical waveguide structure 1, these optical elements (light emitting element 4 and light receiving element 5) and electric elements (light emitting element IC 40 and light receiving element IC 50). ) In cooperation with each other, the mutual conversion between the optical signal and the electric signal is performed reliably, and the signal processing with high speed and low noise can be easily performed.

  In such wiring boards 3a and 3b, the part corresponding to the optical path of the light L from the light emitting element 4 and the part corresponding to the optical path of the light L to the light receiving element 5 respectively transmit the light L. It is comprised with the member which has a light transmittance so that it may accept | permit.

  The optical waveguide (optical waveguide of the present invention) 20 has a layered core layer 21 and a layered clad layer 22 provided on the upper and lower surfaces of the core layer 21 as described above. Yes.

  The core layer 21 includes a core part 211 having a predetermined pattern (in the present embodiment, a strip shape long in the longitudinal direction of the optical waveguide 20), and an evaluation core part 213 whose central axis is provided in parallel to the core part 211. And a core part (waveguide channel) 211 and a clad part 212 (side clad part) adjacent to the evaluation core part 213.

  In the present embodiment, as shown in FIG. 3, four core portions 211 and four evaluation core portions 213 are alternately provided, and are interposed between the core portions 211 and the evaluation core portion 213. As described above, the cladding portion 212 is provided adjacent to the core portion 211 and the evaluation core portion 213.

  The clad part 212 is a part that performs the same function as the clad layer 22, and the clad part 212 (low refractive index region 215) and the clad layer 22 have an average refractive index (hereinafter simply referred to as the core part 211). Sometimes called "refractive index").

  Thereby, the core part 211 formed by being surrounded by the clad part 212 and the clad layer 22 reflects the light L incident from the defect part 28a at the interface between the core part 211, the clad part 212, and the clad layer 22. Thus, an optical path that transmits (propagates) to the defect portion 28b is configured. Further, the evaluation clad part 213 is also formed so as to be surrounded by the clad part 212 and the clad layer 22 and exhibits the same function as the core part 211.

  Moreover, in this embodiment, the core part 211 and the evaluation core part 213 have a quadrangular shape such as a square or a rectangle (rectangle) in cross-sectional shape.

  Furthermore, the core portion 211 has a strip shape that is long in the longitudinal direction of the optical waveguide 20 in a plan view. In the present embodiment, both ends of the core portion 211 are configured by mirrors 23a and 23b. Defects 28a and 28b are provided in the periphery. And these defect | deletion parts 28a and 28b have comprised the clad part 212 so that it might be surrounded. Therefore, the clad part 212 and the missing parts 28a and 28b are interposed between the longitudinal end face of the optical waveguide substrate 2 (optical waveguide 20) and the end part (mirrors 23a and 23b) of the core part 211. The both end portions of each core portion 211 are not exposed from the end surface (end surface) of the optical waveguide substrate 2.

  In addition, the evaluation core part 213 has a strip shape that is long in the longitudinal direction (optical path direction) of the optical waveguide 20, similar to the core part 211, and the central axis thereof is parallel to the adjacent core part 211. Is provided. And in this embodiment, the both ends are exposed in the both ends (both end surfaces) of the longitudinal direction of the optical waveguide 20, respectively.

  In the present embodiment, four core portions 211 and four evaluation core portions 213 are provided in the core layer 21, and the core portion 211 and the evaluation core portion 213 are provided via the cladding portion 212. Are arranged in parallel.

  Moreover, the core part 211 and the evaluation core part 213 preferably have a width in the direction of the optical path of the light L of about 10 to 100 μm in a plan view as shown in FIG. 3 and about 15 to 80 μm. Is more preferable. As a result, the light L incident from the core part 211 or the evaluation core part 213 is reflected at the interface between the core part 211, the clad part 212, and the clad layer 22, and is transmitted (propagated) to the end part. Will surely perform its functions.

  Further, as will be described in detail later, each cladding portion 212 includes a plurality of high refractive index regions 214 each having a higher refractive index than other regions (low refractive index regions 215) in the cladding portion 212. That is, the clad portion 212 is divided into a plurality of high refractive index regions 214 and a low refractive index region 215 having a refractive index lower than that of the high refractive index region 214. As shown in FIG. 3, the plurality of high refractive index regions 214 are aligned in the respective cladding portions 212.

  The difference in refractive index between the core portion 211, the evaluation core portion 213, and the high refractive index region 214 and the low refractive index region 215 in the cladding portion 212 is not particularly limited, but is preferably 0.5% or more. More preferably, it is 0.8% or more. On the other hand, the upper limit value may not be set, but is preferably about 5.5%. If the difference in refractive index is less than the lower limit, the effect of transmitting light may be reduced, and even if the upper limit is exceeded, no further increase in light transmission efficiency can be expected.

The difference in refractive index is expressed by the following equation, where A is the refractive index of the core portion 211 and the evaluation core portion 213, and B is the refractive index of the low refractive index region 215.
Refractive index difference (%) = | A / B-1 | × 100

  In the present embodiment, the core portion 211 and the evaluation core portion 213 are each formed in a strip shape (straight shape) in plan view, but may be curved, branched or the like in the middle. Is optional. In addition, if the manufacturing method of the optical waveguide 20 which is mentioned later is used, the core part 211 and the evaluation core part 213 of complicated and arbitrary shapes can be formed easily and with high dimensional accuracy.

  The constituent materials of the core layer 21, the evaluation core portion 213, and the cladding layer 22 are not particularly limited as long as they are materials that cause the above-described difference in refractive index. Specifically, acrylic resin, methacrylic resin, polycarbonate , Polystyrene, epoxy resin, polyamide, polyimide, polybenzoxazole, polysilane, polysilazane, and various resin materials such as cyclic olefin resin such as benzocyclobutene resin and norbornene resin, quartz glass, borosilicate glass A glass material such as can be used.

  On the other hand, the two clad layers 22 constitute a clad portion located below and above the core portion 211. With such a configuration, the core portion 211 functions as a light guide path whose outer periphery is surrounded by the clad portion.

  The average thickness of the clad layer 22 is preferably about 0.1 to 1.5 times the average thickness of the core layer 21, and more preferably about 0.3 to 1.25 times. Specifically, the average thickness of the clad layer 22 is not particularly limited, but is usually preferably about 1 to 200 μm, and more preferably about 5 to 100 μm. Thereby, the function as a clad layer is suitably exhibited while preventing the optical waveguide 20 from becoming unnecessarily large (thickened).

  In addition, as the constituent material of the cladding layer 22, for example, the same material as the constituent material of the core layer 21 described above can be used, but a norbornene polymer is particularly preferable.

  As described above, the clad portion 212 includes a plurality of high refractive index regions 214 and a low refractive index region 215 having a refractive index lower than that of the high refractive index regions 214.

  As shown in FIG. 3, the low refractive index region 215 is provided so as to be in contact with at least one of the core portions 211 or the evaluation core portions 213, as shown in FIG. 3.

  On the other hand, as shown in FIG. 3, the high refractive index region 214 is provided so as not to directly contact each core part 211 and each evaluation core part 213. That is, the low refractive index region 215 is interposed between the high refractive index region 214 and each core portion 211 and each evaluation core portion 213.

  Further, in the present embodiment, each of the plurality of high refractive index regions 214 has a strip shape in plan view, and is arranged so that the axes are parallel to each other between adjacent ones. Yes. In addition, each high refractive index area | region 214 shown in FIG. 3 has comprised the parallelogram in planar view, respectively. The plurality of high-refractive index regions 214 are aligned on both sides of each cladding portion 212 with each core portion 211 or each evaluation core portion 213 interposed therebetween.

  Each high refractive index region 214 shown in FIG. 3 has an elongated parallelogram, and the length of the long side is preferably about 2 to 50 times the short side, and is about 5 to 30 times. Is more preferable.

  Furthermore, as shown in FIG. 3, these strip-shaped high refractive index regions 214 are provided so as to cross the respective clad portions 212 in the width direction. As a result, the light passing through each clad portion 212 inevitably passes through each high refractive index region 214, and the function of each high refractive index region 214 described below can be surely exhibited.

  Each strip-like high refractive index region 214 is provided such that its axis is inclined backward in the traveling direction of the light L passing through the core 211 with respect to the perpendicular of the axis of the core 211. It has been. By providing such an inclination, light passing through each high refractive index region 214 is incident on the high refractive index region 214 from the low refractive index region 215 and low from the high refractive index region 214. When the light is emitted to the refractive index region 215, the light is refracted so as to inevitably move away from the core 211 based on the difference in refractive index between the two. As a result, the light passing through the clad part 212 can be kept away from the core part 211, and the emission position of the light L and the clad part 212 are propagated in the defect part 28 b where the light L propagated through the core part 211 is emitted. A sufficient separation distance from the light emission position is ensured.

  In this case, the angle (inclination angle of the high refractive index region 214) θ formed by the perpendicular of the axis of the core part 211 and the axis of each high refractive index region 214 having a strip shape shown in FIG. Depending on the refractive index difference between the refractive index region 214 and the low refractive index region 215, the width of the cladding portion 212, and the like, the light passing through the cladding portion 212 is appropriately set so as to be refracted sufficiently and sufficiently.

  Specifically, the inclination angle θ of the high refractive index region 214 is preferably about 10 to 85 °, and more preferably about 20 to 70 °. By setting the inclination angle θ within the above range, the light leaking from the core part 211 is refracted so as to be surely separated from the core part 211, and the signal light and the noise light are separated at the emission side end face 10 b of the optical waveguide 20. Can be separated. As a result, the S / N ratio as a carrier wave can be more reliably increased.

  Also, the separation distance between the high refractive index regions 214 is appropriately set according to the refractive index difference between the high refractive index region 214 and the low refractive index region 215, the width of the cladding portion 212, and the like.

  Furthermore, the width of each high-refractive index region 214 is appropriately set in the same manner, but as an example, it is preferably about 1 to 30 μm, and more preferably about 3 to 20 μm.

  The shape of each high-refractive index region 214 is not particularly limited as long as it has a strip shape (elongated shape). In addition to a quadrangle such as a trapezoid, a rectangle, and a rhombus, there are many shapes such as a triangle, a pentagon, and a hexagon. It may be a square, an ellipse, a circle such as an oval, or the like.

Further, when each high refractive index region 214 has a strip shape, the high refractive index region 214 is provided so as to be inclined with respect to the central axis of the core portion 211 as in the present embodiment. You may provide perpendicular | vertical with respect to a central axis, and may provide in parallel.
The optical waveguide structure 1 as described above is manufactured as follows.

  In the following, a case where the core layer 21 provided in the optical waveguide substrate 2 is formed using the photosensitive resin composition 70 whose refractive index is lowered by the action of the photosensitive light will be described as an example.

  5 to 7 are partial vertical cross-sectional views for explaining the manufacturing process of the optical waveguide substrate included in the optical waveguide structure.

<1> First, the optical waveguide substrate 2 is formed.
<1-1> First, the photosensitive resin composition 70 which changes so that a refractive index may become low by the effect | action of photosensitive light EL (active radiation) is prepared.

  As such a photosensitive resin composition 70, for example, a resin composition having a special composition can be used.

  This resin composition contains a base polymer and a monomer having a refractive index lower than that of the base polymer, and the reaction of the monomer proceeds in the irradiation region irradiated with the photosensitive light EL, whereby the photosensitive light EL. In some cases, unreacted monomer is diffused into the irradiated region from the unirradiated region where no irradiation is performed, and as a result, the refractive index of the unirradiated region becomes higher than the refractive index of the irradiated region.

  Examples of the base polymer include cyclic olefin resins such as norbornene resins and benzocyclobutene resins, acrylic resins, methacrylic resins, polycarbonates, polystyrenes, epoxy resins, polyamides, polyimides, polybenzoxazoles, and silicone resins. , Fluorine resins and the like, and one or more of these can be used in combination (polymer alloy, polymer blend (mixture), copolymer, etc.).

  Among these, those mainly composed of cyclic olefin resins are preferable. By using a cyclic olefin-based resin as the base polymer, the core layer 21 having excellent optical transmission performance and heat resistance can be formed.

  Furthermore, as the cyclic olefin-based resin, it is preferable to use a norbornene-based resin from the viewpoints of heat resistance and transparency. Moreover, since norbornene-type resin has high hydrophobicity, the core layer 21 which is hard to produce the dimensional change by water absorption, etc. can be formed.

  On the other hand, as the monomer, for example, a norbornene monomer, an acrylic acid (methacrylic acid) monomer, an epoxy monomer, an oxetane monomer, a vinyl ether monomer, a styrene monomer, or the like having a lower refractive index than the base polymer is selected. Of these, one or two or more of these can be used in combination.

  Among these, as the monomer, it is preferable to use a monomer or oligomer having a cyclic ether group such as an oxetanyl group or an epoxy group. By using a monomer or oligomer having a cyclic ether group, the cyclic ether group is likely to be opened, so that a monomer capable of reacting quickly can be obtained.

  Specifically, as a monomer having an oxetanyl group and having a refractive index lower than that of the base polymer, for example, a monofunctional oxetane (3- (cyclohexyloxy) methyl-3-ethyloxetane represented by the following formula (1): CHOX) and the like.

  <1-2> Next, on the clad layer 22 formed in advance, as shown in FIG. 5A, the photosensitive resin composition 70 is supplied as a varnish as necessary to form a liquid film. .

  In addition, when making the photosensitive resin composition 70 into a varnish form, it can obtain by dissolving or dispersing the photosensitive resin composition 70 in a solvent or a dispersion medium.

  In addition, although it does not specifically limit as this solvent or a dispersion medium, For example, what was described in Unexamined-Japanese-Patent No. 2010-90328 etc. are mentioned.

  Here, as a method for supplying the photosensitive resin composition 70 onto the clad layer 22, various coating methods can be used. For example, a doctor blade method, a spin coating method, a dipping method, a table coating method, a spray method, Examples include an applicator method, a curtain coating method, and a die coating method.

  In addition, as the clad layer 22, for example, a sheet material having a refractive index lower than that of a core part 211 described later is used, and is not particularly limited. For example, a sheet material including a norbornene-based resin and an epoxy resin is used. Is used.

  <1-3> Next, the liquid film formed on the clad layer 22 is dried to form a film 210 for forming an optical waveguide as shown in FIG.

  The film 210 becomes the core layer 21 including the core part 211, the evaluation core part 213, and the clad part 212 by irradiation with photosensitive light (active radiation) EL described later.

  <1-4> Next, the light EL for sensitization (for example, ultraviolet rays) is selectively applied to the region of the film 210 where the low refractive index region 215 included in the cladding 212 is to be formed.

  At this time, as shown in FIG. 6A, a mask M having an opening corresponding to the shape of the low refractive index region 215 provided in the cladding 212 to be formed above the film 210 is disposed. Through this mask M, the film 210 is irradiated with photosensitive light EL.

  In other words, the area where the core part 211, the evaluation core part 213 and the high refractive index area 214 are to be formed is masked using the mask M.

  Examples of the photosensitive light EL used include those having a peak wavelength in a wavelength range of 200 to 450 nm. Thereby, the refractive index in the region irradiated with the photosensitive light EL of the film 210 can be relatively easily lowered.

The irradiation amount of the photosensitive optical EL is not particularly limited, and is preferably about 0.1~9J / cm ^2, more preferably about 0.2~6J / cm ^2, 0.2 More preferably, it is about ˜3 J / cm ² .

  Note that the use of the mask M can be omitted in the case of using the highly directional photosensitive light EL such as laser light.

  Here, in the irradiated area of the film 210 where the photosensitive light EL is irradiated, the monomer reaction (crosslinking of the pace polymer, polymerization of the monomer, etc.) starts. Further, no monomer reaction occurs in the non-irradiated region where the photosensitive light EL is not irradiated.

  Therefore, in the irradiation region, the remaining amount of monomer decreases as the reaction of the monomer proceeds. In response, the monomer in the unirradiated region diffuses toward the irradiated region, thereby causing a refractive index difference between the irradiated region and the unirradiated region.

  Here, in this embodiment, since the refractive index of the monomer is lower than the refractive index of the base polymer, the monomer in the unirradiated region diffuses into the irradiated region, so that the refractive index of the irradiated region continuously decreases. The refractive index of the unirradiated region is continuously increased.

  Through this process, as shown in FIG. 6B, the unirradiated area of the film 210 becomes the core part 211, the evaluation core part 213, and the high refractive index area 214, and the irradiated area of the film 210 is the low refractive index area. The core layer 21 having become 215 is formed.

  <1-5> Next, the clad layer 22 is formed on the core layer 21 by sticking the same film as the clad layer 22 formed below the core layer 21.

  Accordingly, the pair of clad layers 22 are arranged so as to sandwich the core portion 211 from a direction different from the clad portion 212, that is, from the vertical direction of the core portion 211. As a result, an optical waveguide as shown in FIG. 20 is formed.

  The upper clad layer 22 can also be formed by a method in which a liquid material is applied on the core layer 21 and cured (solidified) instead of a film.

<1-6> Next, the protective layer 29 is formed on both clad layers 22.
For the formation of the protective layer 29, the same method as the formation method of the clad layer 22 described in the above step <1-5> can be used.
Through the steps as described above, the optical waveguide substrate 2 as shown in FIG. 7B is manufactured.

  Here, as described above, in this embodiment, due to the diffusion of the monomer in the unirradiated region to the irradiated region side, a difference in refractive index occurs between the irradiated region and the unirradiated region, and as a result, the irradiated region. 8, the low refractive index region 215 is formed, and the core portion 211, the evaluation core portion 213, and the high refractive index region 214 are formed in the unirradiated region, whereby the core layer 21 as shown in FIG. 8 is formed. The

  In such a core layer 21, as the density and size of the core layer 21 are increased, the separation distance between the adjacent core portions 211 approaches, so that the monomer is sufficiently diffused to the irradiated region side in the unirradiated region. Otherwise, the core part 211, the evaluation core part 213, and the high refractive index region 214 cannot be defined by the low refractive index region 215, and these may be connected to each other.

  Therefore, when the optical waveguide substrate 2 is manufactured as described above or when the optical waveguide 20 is manufactured, the state of the core portion 211, that is, whether or not the core portions 211 are connected, the core portion 211 and the evaluation core portion 213. If it is possible to know the presence or absence of connection with the core portion 211 and the presence or absence of connection between the core part 211 and the high refractive index region 214, it is determined that these connections are not accepted, and only this accepted product is Since it can use for the process for manufacturing the optical waveguide structure 1, it becomes possible to aim at the improvement of the yield of the optical waveguide structure 1. FIG.

  However, if the cladding portion 212 and the missing portions 28a and 28b are interposed between the end portion of the core portion 211 in the optical path direction (longitudinal direction) and the end surface of the optical waveguide 20 as in the present embodiment, the core The end portion of the portion 211 is configured to be surrounded by the clad portion 212 without being exposed from the end face of the optical waveguide 20 (cladding portion 212). Therefore, since the light cannot be efficiently incident from one end of the optical path direction (longitudinal direction) of the core portion 211 and the intensity of the light emitted from the other end cannot be measured, as described above. The presence or absence of connection cannot be determined. That is, it is not possible to evaluate whether or not the manufactured optical waveguide 20 is an acceptable product.

  On the other hand, in the present invention, as described above, the core layer 21 is provided with the evaluation core part 213 whose central axis is provided substantially in parallel with the core part 211. In this evaluation core portion 213, both end portions in the optical path direction (longitudinal direction) of the evaluation core portion 213 are exposed from the optical waveguide 20 (cladding portion 212). Therefore, the state of the evaluation core portion 213 can be known by making light incident from one end of the evaluation core portion 213 in the optical path direction (longitudinal direction) and measuring the intensity of the light emitted from the other end. Furthermore, it is possible to indirectly know the state of the core portion 211 adjacent to this (the evaluation method of the present invention).

  Therefore, at the time when the optical waveguide substrate 2 is manufactured or when the optical waveguide 20 is manufactured, the state of the core portion 211 is indirectly evaluated using the evaluation core portion 213, and the acceptable product is based on the evaluation result. By making it the structure which determines whether it is, the improvement of the yield of the optical waveguide structure 1 manufactured can be aimed at.

  As shown in FIG. 8, the clad portion 212 includes a high refractive index region 214, and light is allowed to enter and exit from the end portion of the optical waveguide 20 through the high refractive index region 214. Since it is necessary, it is unclear whether the emitted light indicates the state of the core part 211 or the high refractive index region 214. Therefore, in the optical waveguide having such a configuration, it is a particularly effective technique to evaluate the state of the core part 211 using the evaluation core part 213.

  In the present embodiment, both ends of the core portion 211 in the optical path direction are not exposed from both end faces of the optical waveguide 20, but at least one end is not exposed from the end face of the optical waveguide 20. For the above, it is effective to apply the present invention to evaluate the state of the core part 211 using the evaluation core part 213.

  Furthermore, it is not necessary to determine whether or not the optical waveguide substrate 2 is an acceptable product, and generally, the connection as described above tends to be formed for each manufactured lot. Alternatively, several pieces in the same lot may be sampled and inspected.

  Further, in the present embodiment, the core layer 21 includes the four core portions 211 and the four evaluation core portions 213, which are alternately arranged in parallel. The layer 21 only needs to include at least one evaluation core portion 213. However, it is possible to more reliably evaluate the state of the corresponding core part 211 by adopting a configuration in which one evaluation core part 213 is provided for one core part 211 as in the present embodiment. It becomes possible.

  <2> Next, the optical waveguide substrate 2 is subjected to, for example, laser processing, grinding processing, and the like to form the defect portions 28a and 28b at predetermined positions.

<3> Next, wiring boards 3a and 3b are prepared.
For each of the wiring boards 3a and 3b, for example, a laminated board (for example, a double-sided copper-clad board) in which a metal layer is formed on both sides of a flat base is prepared, etched, laser processed, etc. It is manufactured by patterning into a predetermined shape to form a wiring part.

  <4> Next, the light-emitting element 4 and the light-emitting element IC 40, the light-receiving element 5 and the light-receiving element IC 50 are respectively prepared and mounted (bonded) to predetermined positions of the wiring boards 3a and 3b.

<5> Next, the wiring boards 3a and 3b are positioned so that the light emitting part of the light emitting element 4 corresponds to the mirror 23a of the missing part 28a and the light receiving part of the light receiving element 5 corresponds to the mirror 23b of the missing part 28b. However, it joins to the upper surface of the optical waveguide board | substrate 2 using an adhesive agent.
The optical waveguide structure 1 is manufactured through the above steps.

  The optical waveguide substrate 2 manufactured in the step <1> is evaluated for the core portion 211 using the evaluation core portion 213, and the optical waveguide substrate 2 that is determined to be an acceptable product is thereby determined in the step <1>. Although the yield of the optical waveguide structure 1 is also improved by adopting the configuration of 2> to <5>, the state of the core part 211 is changed using the evaluation core part 213 after the optical waveguide structure 1 is manufactured. You may make it evaluate. This is because the state of the core part 211 may change due to the optical waveguide 2 undergoing a thermal history or the like by performing the steps <2> to <5>. . Therefore, the manufactured optical waveguide structure 1 is evaluated for the core portion 211 using the evaluation core portion 213, and the optical waveguide structure 1 determined to be an acceptable product thereby is incorporated into an electronic device described later. As a result, the reliability of the manufactured electronic device can be improved.

  In particular, in step <2>, after providing the missing portions 28a and 28b at the end of the core 211 in the optical path direction, light is incident on the core 211 from the end of the optical waveguide substrate 2 in the optical path direction. Since this is almost certainly difficult, it is effective to evaluate the state of the core part 211 using the evaluation core part 213.

  In addition, after the wiring substrates 3a and 3b provided with the optical elements are mounted on the optical waveguide substrate 2 in the step <5>, the defect portions 28a and 28b and the mirrors 23a and 23b are replaced with the wiring substrates 3a and 3b. However, the evaluation core portion 213 is exposed even after the wiring boards 3a and 3b are mounted by exposing the end surface of the evaluation core portion 213 from the longitudinal end surface of the optical waveguide substrate 2. Is not blocked by the wiring boards 3a and 3b. Therefore, even after the wiring boards 3a and 3b are mounted, the state of the core part 211 using the evaluation core part 213 can be evaluated.

  In the present embodiment, the case where the core layer 21 including the core part 211 and the clad part 212 is formed using a resin composition containing a monomer having a refractive index lower than that of the base polymer has been described. The core layer 21 may be formed using a resin composition containing a monomer having a higher refractive index than that of the base polymer.

  When such a resin composition is used, the refractive index is higher in the irradiated region of the film 210 where the monomer is diffused by irradiation with the photosensitive light EL than in the unirradiated region of the film 210. Therefore, in such a form, the core layer 21 is formed in which the irradiated region and the unirradiated region of the film 210 become the core portion 211, the evaluation core portion 213, the high refractive index region 214, and the low refractive index region 215, respectively. .

Second Embodiment
Next, a second embodiment of the optical waveguide of the present invention will be described.

FIG. 9 is a plan view showing a core layer provided in the second embodiment of the optical waveguide structure of the present invention.
Hereinafter, although the optical waveguide 2 concerning this embodiment is demonstrated, it demonstrates centering around difference with the optical waveguide 2 concerning the said 1st Embodiment, and abbreviate | omits the description about the same matter.

  The optical waveguide 2 according to this embodiment is the same as that of the first embodiment except that the high-refractive index region 214 and the low-refractive index region 215 have different patterns in plan view.

  The clad portion 212 shown in FIG. 9 has a plurality of high refractive index regions 214 that are granular in plan view.

  The plurality of high refractive index regions 214 are regions having a higher refractive index than the low refractive index region 215 and are surrounded by the low refractive index regions 215, as in the high refractive index region 214 described in the first embodiment. Are aligned.

  Further, the high refractive index regions 214 are independent from each other, and are provided so as not to directly contact each core portion 211. That is, the low refractive index region 215 is interposed between the high refractive index region 214, the core portion 211, and the evaluation core portion 213, respectively.

  As in the first embodiment, such a high refractive index region 214 has a higher refractive index than the other regions of the cladding portion 212, that is, the low refractive index region 215, but the difference is preferably 0. .5% or more, more preferably the difference is 0.8% or more. Moreover, although an upper limit does not need to be set in particular, Preferably it is set to 5.5%. By providing such a sufficient refractive index difference between the high refractive index region 214 and the low refractive index region 215, total reflection is reliably generated at the interface between the high refractive index region 214 and the low refractive index region 215. be able to. As a result, it is possible to more reliably prevent light propagating through the high refractive index region 214 from unintentionally leaking into the low refractive index region 215.

  Further, in the optical waveguide 20 according to the present embodiment, the light leaked from the core portion 211 to the cladding portion 212 (low refractive index region 215) while the light incident from the incident side end surface 10a propagates to the output side end surface 10b. Reaches the high refractive index region 214, and is scattered irregularly there. Thereby, the light leaking from the core part 211 to the clad part 212 spreads over a wide range and attenuates before reaching the emission side end face 10b. As a result, at the emission side end face 10b, the light intensity of the noise light emitted from the clad portion 212 is reduced, and the S / N ratio as a carrier wave can be increased.

  The shape of the granular high refractive index region 214 in plan view is not particularly limited, and for example, a circle such as a perfect circle, an ellipse, or an ellipse, a triangle, a quadrangle, a hexagon, an octagon, and a star shape. It is assumed to be a square, semicircle, fan shape, etc.

  Moreover, it is preferable that the outline of the high refractive index region 214 has irregularities as shown in FIG. As a result, the contour of the high refractive index region 214 has irregularity on the surface that receives the light leaking from the core portion 211, and can reliably diffuse the light.

  The average particle size of each high refractive index region 214 is preferably about 10 to 500 μm, and more preferably about 20 to 300 μm. By setting the average particle diameter of each high refractive index region 214 within the above range, the probability that each high refractive index region 214 scatters light can be sufficiently increased.

  Also in the core layer 21 including the high refractive index region 214 having such a configuration, it is possible to obtain the operation and effect by providing the evaluation core portion 213 as described in the first embodiment.

  The optical waveguide structure of the present invention is applicable to any electronic device that performs signal processing of both optical signals and electrical signals, and includes, for example, an optical waveguide structure electrically connected on a mother board or an interposer. Applied to opto-electric hybrid board. In this case, a semiconductor element or the like may be further electrically connected on the mother board or interposer provided in the opto-electric hybrid board.

  Furthermore, the opto-electric hybrid board provided with the optical waveguide structure of the present invention is preferably applied to electronic devices such as router devices, WDM devices, mobile phones, game machines, personal computers, televisions, home servers, and the like. In any of these electronic devices, it is necessary to transmit a large amount of data at high speed between an arithmetic device such as an LSI and a storage device such as a RAM. Therefore, since such an electronic device includes the optical waveguide structure according to the present invention, problems such as noise and signal degradation peculiar to electric wiring are eliminated, and a dramatic improvement in performance can be expected.

  In addition, the amount of heat generated in the optical waveguide portion is greatly reduced compared to electrical wiring. For this reason, the degree of integration in the substrate can be increased, the power required for cooling can be reduced, and the power consumption of the entire electronic device can be reduced.

  The embodiments of the optical waveguide, the evaluation method, the optical waveguide structure, and the electronic device of the present invention have been described above, but the present invention is not limited to this.

  For example, each part which comprises an optical waveguide structure can be substituted with the thing of the arbitrary structures which can exhibit the same function. Moreover, arbitrary components may be added.

  In the optical waveguide structure of the present invention, any configurations of the first and second embodiments can be combined.

  In each of the above embodiments, the case where the longitudinal cross-sectional shapes of the core portion and the evaluation core portion are rectangular has been described, but the present invention is not limited to this. The longitudinal cross-sectional shapes of the core part and the evaluation core part may be elliptical, oval, triangular, or the like.

  Further, in each of the embodiments described above, the case where both ends of the evaluation core portion in the optical path direction are exposed from the ends of the optical waveguide is described. As long as the light can enter and exit the core portion, the cladding portion may be provided in contact with the end portion of the evaluation core portion.

DESCRIPTION OF SYMBOLS 1 Optical waveguide structure 2 Optical waveguide board | substrate 20 Optical waveguide 21 Core layer 210 Film 211 Core part 212 Cladding part 213 Evaluation core part 214 High refractive index area | region 215 Low refractive index area | region 22 Clad layer 23a, 23b Mirror 28a, 28b Missing part 29 Protective layer 3a, 3b Wiring board 30 Wiring part 4 Light emitting element 41 Element main body 42 Bump 40 Light emitting element IC
401 Element body 402 Bump 5 Light receiving element 51 Element body 52 Bump 50 Light receiving element IC
501 Element body 502 Bump 70 Photosensitive resin composition M Mask L Light EL Photosensitive light

Claims (13)

An optical waveguide having a flat plate shape that is used by transmitting light,
A core portion, an evaluation core portion provided in parallel with the core portion, and a clad portion provided adjacent to at least one of the core portion and the evaluation core portion,
The cladding portion has a refractive index lower than that of the core portion, a low refractive index region in contact with at least one of the core portion and the evaluation core portion, a refractive index higher than the low refractive index region, and the low refractive index region. A plurality of high refractive index regions spaced from the core portion and the evaluation core portion via a refractive index region, and the plurality of high refractive index regions are scattered or aligned in the cladding portion. ,
The optical waveguide is characterized in that at least one end portion in the optical path direction of the core portion is provided without being exposed at an end surface of the optical waveguide. Each of the core part and the core part for evaluation has a plurality,
The optical waveguide according to claim 1, wherein the evaluation core portion and the core portion are alternately arranged in parallel via the clad portion.   The optical waveguide according to claim 1, wherein both ends of the evaluation core portion in the optical path direction are exposed at an end surface of the optical waveguide.   4. The optical waveguide according to claim 1, wherein an optical path changing unit that changes a direction of the optical path is provided at at least one end of the core part. 5.   The optical waveguide according to claim 1, wherein the evaluation core part has a central axis provided in parallel to the core part.   The light according to any one of claims 1 to 5, wherein the plurality of high refractive index regions refract light passing through the cladding part in a direction away from the core part or irregularly scatter light. Waveguide.   The optical waveguide according to claim 1, wherein each of the high refractive index regions is granular.   The optical waveguide according to claim 1, wherein each of the high refractive index regions has a strip shape. The core portion, the evaluation core portion, the high refractive index region and the low refractive index region are respectively
Actinic radiation is applied to a layer containing a polymer and a monomer having a refractive index different from that of the polymer, and the reaction of the monomer proceeds in an irradiation region irradiated with the active radiation. The unreacted monomer is diffused from the unirradiated region that is not irradiated to the irradiated region, and as a result, a difference in refractive index is generated between the irradiated region and the unirradiated region, whereby the irradiated region and the 9. Any one of the unirradiated regions is formed by using the core portion, the evaluation core portion and the high refractive index region, and the other as the low refractive index region. An optical waveguide according to 1.   The state of the core portion included in the optical waveguide according to claim 1 is obtained by introducing light from one end into the evaluation core portion and measuring the intensity of the light derived from the other end. Evaluation method to evaluate.   An optical waveguide structure comprising the optical waveguide according to claim 1.   The optical waveguide structure according to claim 11, comprising an optical element including a light emitting part or a light receiving part.   An electronic apparatus comprising the optical waveguide structure according to claim 11.

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