KR20100058711A - Optical circuit board having optical waveguide with curved reflecting surface and method for preparing the same - Google Patents

Abstract

PURPOSE: An optical circuit board having an optical waveguide with a curved reflecting surface and a method for preparing the same are provided to reduce the thickness of an optical PCB by manufacturing the optical waveguide and an electrode pattern additionally. CONSTITUTION: A pattern groove is formed on the first surface of a copper foil. The pattern groove is used for forming the optical waveguide. The both end of the pattern groove forms an inclined slope. A first clad(205) is coated on the surface of the pattern groove. The core of the optical waveguide is formed by filling a core material inside the pattern groove. A dry film is patterned on the second surface of a copper foil. The second surface side of the copper foil is half-etched. A metal reflective layer(208) is formed in the inclined slope at the both ends of the pattern groove. A second clad(209) is formed to side the second surface of the copper foil. Electrode patterns is formed by patterning the first surface of the copper foil.

Description

Optical circuit board having an optical waveguide having a curved reflective surface and a manufacturing method therefor {OPTICAL CIRCUIT BOARD HAVING OPTICAL WAVEGUIDE WITH CURVED REFLECTING SURFACE AND METHOD FOR PREPARING THE SAME}

The present invention relates to an optical circuit board and a method of manufacturing the same. Specifically, an optical waveguide for transmitting an optical signal and an electrical wiring for transmitting an electric signal are integrally formed, and the optical waveguide and the optical transmitting / receiving module are vertically coupled. The present invention relates to an optical circuit board capable of fabricating a curved reflective surface by an integrated process and a method of manufacturing the same.

Due to the high speed and high capacity of data in electronic components, printed circuit board (PCB) technology using copper-based electric wiring is reaching its limit. Accordingly, a printed circuit board including optical wiring has attracted attention as a technology capable of overcoming the problems of the conventional copper-based electrical wiring.

The printed circuit board including the optical wiring inserts an optical waveguide in the printed circuit board to transmit and receive signals using light using a polymer and an optical fiber. Optical Circuit Board). EOCBs are used for backplanes and daughter boards in switches and transceivers in communication networks, switches and servers in data communications, communications in the aerospace industry and avionics, mobile base stations in universal mobile telecommunication systems (UMTS), or supercomputers. It is applied to Daughter Board.

A conventional method for manufacturing an optical waveguide is shown in FIG.

As shown in FIG. 1, a conventional optical waveguide includes a step (A) of applying a liquid curable composition 6 to an upper surface of a mold 4 on which a recess 5 for forming a core part is formed; A step (B) of scraping off and removing the liquid curable composition (6) applied to the upper surface of the mold (4) with a rubber squeeze (7); (C) pressurizing and bringing the uncured layer (3) of the lower clad layer dry film (1) onto the upper surface of the mold (4) manufactured in the step (B); A step (D) of simultaneously curing the liquid curable composition 6 and the uncured layer 3 for forming the core portion and forming a structure; Removing the mold (4) from the structure (E); It is manufactured by the step (F) of forming the upper clad layer 15 on the upper surface of the structure from which the mold 4 is separated.

Conventionally, in order to manufacture an optical circuit board, as described above, an optical waveguide for transmitting an optical signal has to be manufactured through a separate process, and it has to be connected to a general PCB in which electrical wiring for electrical signal transmission is formed. That is, after manufacturing the optical waveguide as shown in FIG. 1, the optical waveguide manufactured by the above method was connected to the printed circuit board, but the electrode pattern had to be manufactured by a separate manufacturing process and then separately connected to the printed circuit board. Therefore, the overall thickness of the optical circuit board increases, and there is a problem in that the manufacturing process is complicated by separately stacking the optical waveguide and the electrode pattern. In addition, due to the connection of a separate layer, there was a fear that the phenomenon of separation during the movement between the other processes because the bending between the two interfaces, the adhesive strength is lowered.

On the other hand, recently, a technology for making an optical connection using an optical transmission / reception module has been developed. For example, the optical reception device is directly coupled to a ribbon optical fiber multichannel optical connector having a reflector positioned at an inclination angle of 45 °. The optical transmission and reception device is vertically coupled to the polymer optical waveguide with a polymer optical waveguide having a reflector positioned at an inclination angle of 45 °, and the polymer optical waveguide is connected to a multichannel optical connector.

In this conventional optical connection method, in order to couple the light source and the optical waveguide, a reflector positioned at a 45 ° inclination angle must be provided at a connection portion with the optical transmission / reception module on the optical waveguide. There must be a grooving process by a diamond blade, etc., and a separate metal coating process has to be performed to increase reflection efficiency.

The present invention is to solve all the disadvantages and problems of the prior art as described above, the optical waveguide for optical signal transmission and the electrical wiring for the electrical signal transmission is integrally formed, the optical waveguide and the optical transmission / reception module is vertical An object of the present invention is to provide a method for manufacturing an optical circuit board capable of fabricating a curved reflective surface to be bonded by a single process, and an optical circuit board manufactured thereby.

The present invention (a) forming a pattern groove for forming an optical waveguide on the first surface of the copper foil, both ends of the pattern groove to form an inclined curved surface for manufacturing the reflective surface; (b) coating a first clad on the surface of the formed pattern groove; (c) filling a core material in the pattern groove coated with the first clad to form an optical waveguide core; (d) patterning a dry film on the second surface of the copper foil so as to correspond to both ends of the pattern groove; (e) half-etching the second surface side of the copper foil to reduce the thickness of the copper foil and to form a metal reflective layer on the inclined curved surfaces at both ends of the pattern groove; (f) forming a second clad on the second surface side of the copper foil; And (g) patterning the first surface of the copper foil to form an electrode.

In addition, the present invention (a) forming a pattern groove for forming an optical waveguide on the first surface of the copper foil, both ends of the pattern groove to form an inclined curved surface for manufacturing the reflective surface; (b) performing surface treatment on the formed pattern grooves to reduce roughness of the pattern grooves; (c) filling a core material into the surface-treated pattern groove to form an optical waveguide core; (d) patterning a dry film on the second surface of the copper foil so as to correspond to both ends of the pattern groove; (e) half-etching the second surface side of the copper foil to reduce the thickness of the copper foil and to form a metal reflective layer on the inclined curved surfaces at both ends of the pattern groove; (f) forming a clad on the second surface side of the copper foil; And (g) patterning the first surface of the copper foil to form an electrode.

In addition, the present invention is an optical waveguide core having a semi-circular or semi-elliptical cross-section perpendicular to the light propagation direction and having a curved reflective surface with metal layers attached to both ends thereof; A first clad surrounding a surface corresponding to a curved portion of a cross section of the optical waveguide core; A second clad in which the optical waveguide core and the first clad are buried in one surface; And a copper foil electrode patterned at a position different from the core on the same surface as the core buried surface of the second clad.

In addition, the present invention is an optical waveguide core having a curved surface reflecting a semi-circular or semi-elliptical shape of the cross section perpendicular to the light traveling direction, the metal layer is attached to both ends; A clad in which the optical waveguide core is buried in one surface; And a copper foil electrode patterned at a position different from the core on the same surface as the core buried surface of the clad.

According to the present invention, since the optical waveguide and the electrode pattern need not be manufactured and connected separately in the manufacture of the optical circuit board, not only can the thickness of the entire optical PCB be reduced, but also the manufacturing cost can be simplified and the manufacturing process can be simplified. In addition, the bending degree of the optical waveguide and the electrode pattern and the adhesive strength may be solved.

In addition, the present invention, since the curved reflective surface for vertical coupling with the optical transmission / reception module is integrally formed during the optical waveguide manufacturing process, a separate reflective surface manufacturing process is unnecessary, so that the unit cost can be reduced, and optical transmission / Alignment between the receiving module and the reflective surface of the optical waveguide is easy.

In addition, since the present invention can produce an optical waveguide using a half-etched copper pattern as a stamp, there is an advantage that a separate stamp is unnecessary, unlike conventional embossing technology.

In addition, the optical circuit board manufacturing process of the present invention can be a continuous process by a roll to roll (roll to roll) method.

Hereinafter, with reference to the accompanying drawings an optical circuit board manufacturing method of the present invention; And an optical circuit board that can be manufactured by the above manufacturing method will be described in more detail.

2 to 12 are schematic flowcharts of an optical circuit board manufacturing method according to an exemplary embodiment of the present invention, and the optical circuit board manufacturing method of the present invention will be described with reference to FIGS. 2 to 12.

(A) forming a pattern groove for forming an optical waveguide on the first surface of the copper foil, wherein both ends of the pattern groove form an inclined curved surface for manufacturing a reflective surface

Forming a pattern groove for forming an optical waveguide on the first surface on the copper foil 201, the pattern groove is used in a method such as etching, electro-forming method which is generally used in the art It can form, and a formation method is not specifically limited. For example, after the dry film 202 pattern is formed on the first surface on the copper foil 201 as shown in FIGS. 2 and 3, the pattern groove 203 for forming the optical waveguide can be formed by half etching. . The dry film to be used is not particularly limited as long as it is known to those skilled in the art to be used for patterning, and a liquid photoresist may be used instead of the dry film.

At this time, both ends of the pattern groove is preferably formed as an inclined curved surface 204 for the production of the reflective surface to be described later, the inclined curved surface 204 may be similar to the shape of a quadrant. The form can be easily formed by half etching or the like. In the present specification, the quadrant means a quarter of a sphere or a quarter of an ellipse.

The angle, shape, and the like of the inclined curved surface 204 can be controlled by the composition of the etching solution used for half etching, the etching rate, the etching solution spraying method, and the thickness adjustment of the dry film.

In general, since the metal has isotropic etching characteristics, when the dry film is patterned and the metal is etched, a curved etching surface is formed as shown in FIG. 13. Herein, the ratio of the horizontal length A and the etching depth B of the curved surface of the etching may be defined as an etching factor (F), that is, F = B / A, and the etching factor F is not particularly limited. On the basis of the central section of the curved surface, which is referred to, preferably in the range of 0.1 to 5.

The copper foil may be replaced with a metal foil such as aluminum, silver, gold, or an alloy having excellent electric conduction characteristics. As described above, since the optical waveguide can be manufactured using the etched copper pattern, there is an advantage that a separate stamp is unnecessary, unlike an embossing technique of forming a core portion of the optical waveguide using a frame having a conventional concave portion.

In general, etching may be used to form a pattern in which a cross section perpendicular to the light traveling direction has a semi-circle or semi-ellipse shape (see cross-sectional view on the left side of FIG. 3).

Although the thickness of the said copper foil which can be used is not specifically limited, Preferably it may be in the range of 12-500 micrometers.

On the other hand, since the surface of the pattern groove formed above is rough, if the optical waveguide is directly formed in the pattern, the waveguide loss may increase, so that surface roughness may be reduced by performing surface treatment. The surface treatment may be performed using a method such as electroplating, gloss plating, electropolishing, chemical polishing, or the like.

(B) optionally coating the first clad on the surface of the pattern groove

Optionally, the first clad 205 may be coated on the surface of the formed pattern groove 203 (see FIG. 4A). The coated first clad 205 serves to cladding the optical waveguide and to reduce light loss that may occur due to roughness of the copper foil pattern groove surface. The first clad 205 may be manufactured using the same or similar material as the second clad 209 to be described later.

Coating of the first clad 205 may be carried out by a method known to those skilled in the art, and non-limiting examples thereof may use a soft blade, soft roll, air blow, and the like. have.

The coating may be repeated two or more times to obtain the desired roughness of the pattern groove surface and the thickness of the clad layer (2 μm to 200 μm).

The first clad is preferably formed by coating only the surface of the pattern groove, but sometimes it may be extended to the first surface of the copper foil other than the pattern groove, and may be coated and formed. This also corresponds to the equivalent scope of the present invention.

However, in the case where the formed pattern groove is sufficiently smooth by performing a surface treatment such as electroplating, gloss plating, chemical polishing, electropolishing on the copper foil having the pattern groove manufactured in the step (A), the above (B) Coating the first clad of the step may or may not be performed relatively simply (see FIG. 4B). When the surface of the pattern groove for forming the optical waveguide is sufficiently surface-treated 215 and smoothed, the surface of the core of the optical waveguide formed in the pattern groove is smoothed, whereby an optical signal for propagating the optical waveguide is generated by the roughness of the surface of the optical waveguide core. This is because the loss can be reduced.

Therefore, the following description will be mainly focused on the first clad coated structure on the pattern groove surface (in the case of FIG. 4A), but the same post-process is performed even when only the surface treatment is performed without the first clad (in the case of FIG. 4B). Of course it also belongs to the scope of the present invention.

(C) filling the core material in the pattern groove coated with the first clad to form an optical waveguide core

The optical waveguide core 206 may be formed by filling a core material in the pattern groove coated with the first clad 205 (see FIG. 5). The means for filling for the core formation is not particularly limited. For example, it can fill by means, such as an inkjet or squeeze. In the case of using the inkjet technology, the core material is not laminated on the entire copper foil substrate, but the core material can be partially filled only inside the pattern, so that waste of the core material is remarkably reduced, which is preferable. In this case, preferably, the core material may be filled with the same width and height as the pattern groove formed in the copper foil.

On the other hand, after apply | coating a core substance to the whole copper foil, a core can also be formed by removing the core substance which remain | survives on copper foil surfaces other than a pattern using squeeze etc.

The core material may be used without limitation as long as the core material has been used as a core material for forming a core in the prior art, and may use a material having a different refractive index or a different kind of material as the material of the same series as the second clad material to be described later. have.

(D) patterning the dry film on the second surface of the copper foil so as to correspond to both ends of the pattern groove

The dry film 207 may be patterned on the second surface of the copper foil to form a metal reflective layer corresponding to the curved reflective surface formed at both ends of the pattern groove (see FIG. 6). Since the copper foil is thinly etched or partially removed entirely except for the curved reflective surface portion to be produced at both ends of the pattern groove by the second surface half etching of the copper foil to be described later, the metal reflective layer is left on the rear surface of the curved reflective surface. In order to form the metal film, it is preferable to mask the copper foil portion where the metal reflective layer is to be formed by using the dry film 207 or the like so as not to be removed by the etching solution during half etching.

At this time, the dry film used may be the same or similar materials to the dry film used when forming the pattern groove described above.

On the other hand, since the dry film patterning in this step is for half-etching the second surface of the copper foil, it may be patterned only on the second surface of the copper foil, but if the etching may possibly affect the core surface, the core is protected. For the sake of simplicity, as shown in FIG. 6, the dry film may be applied to all or part of the first surface of the copper foil.

(E) half-etching the second surface side of the copper foil to reduce the thickness of the copper foil and to form a metal reflective layer on the inclined curved surfaces at both ends of the pattern groove.

By half-etching the second surface of the copper foil patterned with the dry film on both end portions of the pattern grooves, the overall thickness of the copper foil can be reduced, and at the same time, a copper foil having a predetermined thickness on the inclined curved portion where the curved reflective surfaces at both ends of the pattern grooves are to be formed. The metal reflective layer 208 can be formed by leaving (see FIG. 7).

When the overall thickness of the copper foil is reduced, the thickness of the electrode formed in the process to be described later decreases, and precise control of the line width and the line spacing is possible when forming the electrode pattern.

In addition, the curved reflective surface portion patterned by the dry film may serve as a reflecting mirror by forming a metal reflective layer by remaining copper foil having a predetermined thickness, thereby improving light reflecting efficiency at both ends of the optical waveguide core. If there is no metal reflective layer, the light reflection efficiency at both ends of the curved optical waveguide core may be reduced.

A method of coating a metal film by using a vacuum deposition process or the like at both ends of the optical waveguide core may be possible, but there may be a problem in that the process becomes complicated and the process cost increases. Therefore, in the present patent, the reflection efficiency at both ends of the optical waveguide core can be improved by simply forming a metal reflective layer through an etching process.

At this time, except for the curved reflective surface portions at both ends, the optical waveguide portion exposes the first cladding layer to expose the first cladding layer, and the core surface is exposed when the first cladding layer is manufactured without surface treatment.

(F) forming a second clad on the second surface side of the copper foil

The second clad 209 may be formed on the copper foil and metal reflective surface thinned by half etching, and on the second surface side where the first clad or core is exposed to completely cover the second surface (see FIG. 8).

The second clad 209 may be formed by applying a photocurable composition or a thermosetting composition and then irradiating or heating UV. Examples of the liquid photocurable composition that can be used include resins containing polymerizable functional groups such as ethylene unsaturated groups, polymerizable monomers, photopolymerization initiators, organic solvents, and the like. Resin which has polymerizable functional groups, such as said ethylenically unsaturated group, is a compound containing glycidyl group and ethylenically unsaturated group in the polymer which has a carboxyl group or a hydroxyl group, the compound containing an isocyanate group and ethylenically unsaturated group, or acrylic acid chloride, for example. It can be obtained by addition reaction. Examples of the polymerizable monomer include methyl acrylate, ethyl acrylate, isopropyl acrylate, t-butyl (meth) acrylate, hydroxy ethyl (meth) acrylate and cyclohexyl (meth) acrylate. , 2-methyl cyclohexyl (meth) acrylate, isobonyl (meth) acrylate and the like can be used.

Meanwhile, in order to improve adhesion between the second surface of the copper foil exposed to the core and the second clad 209, an oxidation treatment (black oxide or brown oxide) may be additionally performed on the second surface of the copper foil. The oxidation treatment is a process of oxidizing the Cu surface to form Cu ₂ O (copper oxide) and CuO (copper oxide), and may be used to improve the adhesion by forming roughness on the Cu surface.

(G) patterning the first surface of the copper foil to form an electrode

After the second clad 209 is formed, a portion of the first surface of the copper foil may be removed to form the electrode pattern 210 (see FIG. 9). Under the present circumstances, the 1st surface patterning method of copper foil will not be restrict | limited especially if it is a method known to a person skilled in the art. For example, after the dry film 202 is patterned, the electrode pattern 210 may be formed by etching or the like.

Meanwhile, in order to improve adhesion between the first surface of the copper foil and the third clad 213 which will be described later, before and after patterning the first copper foil, an oxidation treatment (black oxide or brown oxide) may be additionally performed on the first surface of the copper foil.

As described above, the optical waveguide and the electrode pattern do not need to be manufactured and connected separately, and can be manufactured by an integrated process. Thus, the thickness of the entire optical circuit board can be reduced, the manufacturing cost can be reduced, and the manufacturing process can be simplified. In addition, the optical waveguide and the bending of the electrode pattern, there is an advantage that can solve the problem of poor adhesion.

As described above, after the steps (A) to (G), the optical devices 211 and 212 may be mounted on the electrode patterns of the optical circuit board (see FIG. 10). Optical devices that can be mounted include a vertical-cavity surface emitting laser (VCSEL) and a photo diode (PD). The VCSEL is an active element and converts an electrical signal into an optical signal, and the PD converts an optical signal into an electrical signal.

On the other hand, after the optical device is mounted, a third cladding layer 213 may be further formed (see FIG. 11). The third cladding layer 213 may simultaneously perform a role of cladding of the optical waveguide and an underfill function for protecting an electrical connection state of the optical device.

In addition, after the third cladding layer 213 is formed, the protective film 214 may be further attached to protect the product, and at the same time, the degree of bending may be improved (see FIG. 12).

The optical circuit board manufacturing process of the present invention can be a continuous process by a roll to roll (roll to roll) method.

On the other hand, as described above, when the (A) ~ (G) step, as shown in Figure 9, the cross section perpendicular to the light traveling direction is a semi-circle or semi-elliptic form, the curved surface plate with a metal layer attached to both ends An optical waveguide core 206 having a slope; A first clad 205 surrounding a surface corresponding to a curved portion of a cross section of the optical waveguide core; A second clad 209 in which the optical waveguide core and the first clad are buried in one surface; And a copper circuit electrode 210 formed on the same surface as the core buried surface of the second clad with a different position from the core, or an intermediate part thereof, as described above. The mounting, the formation of the third cladding layer and the forming of the protective film layer may be further roughened.

As described above, when only the surface treatment is performed without forming the first cladding layer in step (B), the cross section perpendicular to the light traveling direction is semi-circular or semi-elliptical in shape, and the metal layers are formed at both ends. An optical waveguide core having an attached curved reflective surface; A clad in which the optical waveguide core is buried in one surface; And an optical circuit board composed of a copper foil electrode patterned at a position different from the core on the same surface as the core buried surface of the clad, or an intermediate part thereof, which is equivalent to the scope of the present invention. It is obvious.

Although this invention demonstrated the optical circuit board using copper foil, the equivalent of copper foil which functions the same conductive substrate as copper foil also belongs to the scope of the present invention.

On the other hand, although the technical spirit of the present invention has been described in detail according to the above-described embodiment, the above-described embodiment is for the purpose of description and not of limitation, and those skilled in the art of the present invention It will be understood that various embodiments are possible within the scope of the spirit. In addition, the manufacturing order may be changed depending on the situation.

1 is a process chart showing a conventional optical waveguide fabrication method.

2 to 12 are process charts showing step by step an optical waveguide manufacturing method according to an embodiment of the present invention.

It is a schematic diagram which shows the isotropic etching characteristic of a metal.

<Drawing symbol>

1: Dry film for lower clad layer 2: Base material 3: Uncured layer

4: Form 5: Groove Bottom 6: Liquid Curable Composition for Core Formation

7: rubber squeeze 8: top of brother

9: space (squeegee scraped off) 10: ultraviolet light 11: lower cladding layer

12: core portion 13: liquid curable composition for forming an upper clad layer

14: ultraviolet light 15: upper cladding layer

201: copper foil 202: dry film 203: pattern groove

204: inclined curved surface for manufacturing a reflective surface 205: first clad 206: core

207 dry film 208 metal reflective layer 209 second cladding

210: electrode pattern 211: VCSEL array 212: PD array 213: second clad

214: protective film 215: surface of the surface pattern groove

Claims (17)

(a) forming a pattern groove for forming an optical waveguide on the first surface of the copper foil, wherein both ends of the pattern groove form an inclined curved surface for manufacturing a reflective surface; (b) coating a first clad on the surface of the formed pattern groove; (c) filling a core material in the pattern groove coated with the first clad to form an optical waveguide core; (d) patterning a dry film on the second surface of the copper foil so as to correspond to both ends of the pattern groove; (e) half-etching the second surface side of the copper foil to reduce the thickness of the copper foil and to form a metal reflective layer on the inclined curved surfaces at both ends of the pattern groove; (f) forming a second clad on the second surface side of the copper foil; And (g) patterning the first surface of the copper foil to form an electrode Method of manufacturing an optical circuit board comprising a. The method of claim 1, wherein the pattern groove of step (a) is formed by a half etching method. The method of claim 1, wherein the inclined curved surface of step (a) has a quadrant shape. The method of claim 1, wherein the cross section perpendicular to the optical signal traveling direction of the pattern groove is a semicircle or semi-elliptic curved surface. The method of claim 1, wherein the surface of the pattern groove formed after the step (a) is subjected to a surface treatment. 6. The method of claim 5, wherein the surface treatment of the pattern groove is electroplating, gloss plating, chemical polishing or electropolishing. The first surface of the copper foil according to claim 1, wherein the second surface of the copper foil is subjected to oxidation after step (e), or the first surface of the copper foil is subjected to oxidation after step (f) or after step (g). A method of manufacturing an optical circuit board, characterized by increasing the roughness of the surface or the second surface. The method of claim 1, wherein the first clad of the remaining portions except for both ends of the pattern groove is exposed by half etching of the step (e). (a) forming a pattern groove for forming an optical waveguide on the first surface of the copper foil, wherein both ends of the pattern groove form an inclined curved surface for manufacturing a reflective surface; (b) performing surface treatment on the formed pattern grooves to reduce roughness of the pattern grooves; (c) filling a core material into the surface-treated pattern groove to form an optical waveguide core; (d) patterning a dry film on the second surface of the copper foil so as to correspond to both ends of the pattern groove; (e) half-etching the second surface side of the copper foil to reduce the thickness of the copper foil and to form a metal reflective layer on the inclined curved surfaces at both ends of the pattern groove; (f) forming a clad on the second surface side of the copper foil; And (g) patterning the first surface of the copper foil to form an electrode Method of manufacturing an optical circuit board comprising a. The method of claim 9, wherein the pattern groove of step (a) is formed by a half etching method. 10. The method of claim 9, wherein the inclined curved surface of step (a) has a quadrant shape. The method of claim 9, wherein the cross section perpendicular to the optical signal traveling direction of the pattern groove is a semicircle or semi-elliptic curved surface. The method of claim 9, wherein the surface treatment of the pattern groove of step (b) is electroplating, gloss plating, chemical polishing or electropolishing. The method of claim 9, wherein after the step (e), the second surface of the copper foil is subjected to oxidation treatment, or after the step (f) or after the step (g), the oxidation treatment is performed on the first surface of the copper foil. A method of manufacturing an optical circuit board, characterized by increasing the roughness of the surface or the second surface. 10. The method of claim 9, wherein the half of the pattern groove is exposed by the half etching of the step (e). An optical waveguide core having a semi-circular or semi-elliptic cross section perpendicular to the light propagation direction and having a curved reflective surface with metal layers attached to both ends thereof; A first clad surrounding a surface corresponding to a curved portion of a cross section of the optical waveguide core; A second clad in which the optical waveguide core and the first clad are buried in one surface; And And a copper foil electrode patterned at a position different from the core on the same surface as the core buried surface of the second clad. An optical waveguide core having a semi-circular or semi-elliptic cross section perpendicular to the light propagation direction and having a curved reflective surface with metal layers attached to both ends thereof; A clad in which the optical waveguide core is buried in one surface; And And a copper foil electrode patterned at a position different from the core on the same surface as the core embedding surface of the clad.

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