Waveguide connection structure, waveguide chip, connector, and method of manufacturing waveguide connection component, and waveguide connecting method

A waveguide connection structure consists of a waveguide chip having a waveguide, and a connector having a groove dug in a thickness direction, the waveguide chip and the connector each having a concave-convex portion that fit into each other in a state of being adjacent to each other on the same plane.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase entry of PCT Application No. PCT/JP2019/020254, filed on May 22, 2019, which applications are hereby incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a production method of a waveguide connection structure, a waveguide chip, a connector, and a waveguide connection component, and a waveguide connection method, and relates to a production method of a connection structure of a waveguide chip having fibers and a waveguide for transmitting light to transmit and process optical signals such as, for example, optical communication and light sensing, a waveguide chip, a connector, and a waveguide connection component, and a waveguide connection method.

BACKGROUND

In order to connect a waveguide chip having a waveguide substrate to an optical fiber, a connection structure as shown inFIG.8is used. Here, a chip1001includes a waveguide1002made of glass on its upper surface, while a fiber1003includes a core1004.

In order to optically connect the waveguide1002and the core1004, the fiber1003is first sandwiched between a V-groove chip1005having a V-groove and a flat plate1006, which are fixed with an adhesive, the end face of the fiber1003, and the end faces of the V-groove chip1005and the flat plate1006are polished to become flush, to produce a fiber block1007.

Further, since the fiber block1007is thick, a block1008is fixed on the chip1001with adhesive, and, as in the production of the fiber block1007, the end faces of the chip1001, the waveguide1002, and the block1008are polished to become flush.

Next, the fiber block1007is aligned (centered) relative to the waveguide1002so that light may pass between the waveguide1002and the core1004, and the fiber block1007, the chip1001, and the block1008are fixed by adhesive where optical insertion loss is minimized.

Although not shown here, the portion of the fiber1003protruding outside of the V-groove chip1005is coated with resin or the like for mechanical and chemical protection. (Non-Patent Literature 1)

In recent years, waveguide chips that use silicon instead of glass as the waveguide material (silicon photonics) are being used. Since silicon is a material with a higher refractive index than glass, silicon optical waveguides are of a structure in which a cross-section perpendicular to the waveguide direction is a rectangular cross-section of 0.5 μm or less, which is smaller than the core diameter of the fiber (a few μm). In order to optically connect a silicon waveguide and a core of an optical fiber with such a difference in size, a structure for mutual connection is used in which a spot size converter is formed at the chip end face, which is the end of the waveguide, to expand the beam shape to about 4 μm, and a thin fiber with a core diameter of about 4 μm is used (Non-Patent Literature 2).

CITATION LIST

SUMMARY

Technical Problem

When the optical waveguide and the fiber core are this small, an alignment precision of 0.1 μm or less is necessary. However, with the conventional method described above, that is to say with active alignment in which the fiber block is aligned (centered) relative to the waveguide so that light may pass, it is not easy to perform highly precise alignment and connect. Further, due to changes in the adhesive over time or the like, it is difficult to stably maintain a highly precise alignment and connection even after connecting.

It is thus an object of the present invention to provide a waveguide connection structure that makes it easy to realize highly precise alignment.

Means for Solving the Problem

In order to achieve the above object, a waveguide connection structure (1) according to the present invention consists of a waveguide chip (100) having a waveguide (101) and a connector (110) having a groove (111) dug in a thickness direction, the waveguide chip (100) and the connector (110) each having a concave-convex portion (102,112) that fit into each other in a state of being adjacent to each other on the same plane.

In a waveguide connection structure according to an embodiment of the present invention, the waveguide chip and the connector respectively include a first substrate (104) and a second substrate (114) formed from silicon, the first substrate and the second substrate may be formed at a same thickness.

In addition, in a waveguide connection structure according to another embodiment of the present invention, an end of a convex portion of the concave-convex portion may be formed in a tapered shape.

In addition, a waveguide connection structure according to another embodiment of the present invention may further include a locking mechanism consisting of a locking claw formed on a convex portion of the concave-convex portion and a locking groove formed in a concave portion.

In addition, a waveguide chip according to the present invention includes a substrate (104); and a waveguide (101) formed on a surface of the substrate, wherein the substrate (104) has a concave-convex portion (102) arranged along a direction orthogonal to the waveguide as seen in a plan view, the concave-convex portion (102) being configured to fit into a concave-convex portion (112) formed on another component (110) in a state of the substrate (104) being adjacent to the other component (110) on a same plane.

In addition, a connector according to the present invention includes a substrate (114) having a groove (111) dug in a thickness direction, wherein the substrate has a concave-convex portion (112) arranged in a direction orthogonal to the groove as seen in a plan view, the concave-convex portion (112) being configured to fit into a concave-convex portion (102) formed on another component (100) in a state of the substrate (114) being adjacent to the other component (100) on a same plane.

In addition, a production method of a waveguide connection component according to the present invention includes a step of forming a waveguide on a surface of a substrate; a step of forming a groove that is dug in a thickness direction of the substrate and extending in a direction away from an end face of the waveguide, and a plurality of through holes arranged in a staggered manner along a direction orthogonal to the waveguide as seen in a plan view, each through hole penetrating the substrate; and a step of cutting the substrate along a direction orthogonal to the waveguide as seen in a plan view and separating the substrate into a first piece and a second piece including concave-convex portions that fit into each other, wherein the first piece is a waveguide chip having a first substrate which is a part of the substrate and the waveguide, and the second piece is a connector having a second substrate which is another part of the substrate and the groove formed in the second substrate.

In addition, an optical waveguide connection method according to the present invention includes a step of preparing a waveguide chip and a connector each having a concave-convex portion that fit into each other in a state of being adjacent to each other on a same plane, the waveguide chip having a first substrate and a waveguide formed on a surface of the first substrate, the connector having a second substrate, the second substrate having a groove dug in a thickness direction of the second substrate; a step of fixing an end of an optical fiber in the groove of the connector; a step of electrically connecting the waveguide chip to a package; a step of electrically connecting the package to a printed circuit board; and a step of fitting the concave-convex portion of the connector into the concave-convex portion of the waveguide chip inside the package to optically connect the waveguide and the optical fiber.

Effects of Embodiments of the Invention

According to embodiments of the present invention, so-called active alignment is not necessary, so highly precise alignment can easily be realized even with a small waveguide connection structure. Further, since the waveguide chip and the connector having the fiber are formed from the same substrate using a series of microfabrication steps, a small waveguide connection structure enabling highly precise alignment passively can be obtained.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

First Embodiment

FIG.1A,FIG.1B, andFIGS.2A to2Dshow an example of a waveguide connection structure according to a first embodiment of the present invention. Of these drawings,FIG.1A,FIG.2A, andFIG.2Bare respectively a perspective view, a top view, and a cross-sectional view showing a pre-connected state of a waveguide connection structure1according to the embodiment, andFIG.1B,FIG.2C, andFIG.2Dare respectively a perspective view, a top view, and a cross-sectional view showing a connected state.FIG.2Bis a cross-sectional view taken along line IIB inFIG.2A, andFIG.2Dis a cross-sectional view taken along line IID inFIG.2C.

The waveguide connection structure1according to the present embodiment is composed of a waveguide chip100having a waveguide101, and a connector110having a fiber120, and optically connects the waveguide101to the fiber120. As shown in the drawings, in the waveguide connection structure1according to the present embodiment, the waveguide chip100and the connector110each have concave-convex portions102,112that fit into each other in a state of being adjacent to each other on the same plane.

The waveguide chip100has a first substrate104and a waveguide101formed on a surface of the first substrate104. The waveguide101is covered by a cladding layer103over the first substrate104. In the present embodiment, the first substrate104and the waveguide101are both formed of silicon (Si). In addition, the cladding layer103is formed of a silicon oxide film (SiO2). For example, the substrate104is a Si substrate with a thickness of 1 mm, and a cross-sectional shape of a cross-section of the silicon waveguide101perpendicular to the waveguide direction is rectangular with a width of 0.1 μm and a height of 0.2 μm. In addition, the cladding layer103covers the waveguide101from above, below, left, and right as seen in a cross-sectional view with a thickness of 2 μm.

Further, at an end face of the waveguide chip100facing the connector110, a concave-convex portion102is formed. That is to say, the first substrate104has a concave-convex portion102, which is arranged along a direction orthogonal to the waveguide101in a plan view, and as shown inFIG.1BandFIG.2C, in a state of being adjacent to the connector110on the same plane, the concave-convex portion102fits into a concave-convex portion112formed on the connector110.

It should be noted that in the drawings, the main components of the waveguide101of the waveguide chip100and the spot size converter at the chip end face of the waveguide101are omitted.

Meanwhile, the connector110is formed of the same materials with the same film thicknesses as the chip100, and further, a groove111is formed in a substrate114at a portion in which the fiber is installed. Specifically, the connector110has a second substrate114, and a groove in dug in a thickness direction of the second substrate114is formed in the upper surface of the second substrate114. The substrate114has a concave-convex portion112, which is arranged along a direction orthogonal to the groove111in a plan view, and as shown inFIG.1BandFIG.2C, in a state of being adjacent to the waveguide chip100on the same plane, the concave-convex portion112fits into the concave-convex portion102formed on the waveguide chip100.

In the present embodiment, the first substrate104of the waveguide chip100and the second substrate114of the connector110are formed at the same thickness. Further, in the present embodiment, the second substrate114, like the first substrate104of the waveguide chip100, is formed of silicon (Si), and further, on the upper surface thereof, like the cladding layer103of the waveguide chip100, a silicon oxide film (SiO2) layer113is formed. Accordingly, if the cladding layer (silicon oxide layer)103and the silicon oxide layer113formed respectively on the first substrate104and the second substrate114are made to have the same thickness, then the waveguide chip100and the connector110will have the same thickness as each other.

As shown in the drawings, the groove111of the connector110is formed to extend in a direction away from the waveguide chip100from a position of the connector110corresponding to an end face of the waveguide101in a state where the concave-convex portion102of the waveguide chip100and the concave-convex portion112of the connector110fit into each other. At least part of an end of the fiber120installed in the connector110is accommodated in and positioned by the groove11.

The fiber120has a core121. When arranging the fiber120on the connector110, the portion of the fiber120protruding from the connector110at the opposite side of the waveguide chip100may be covered with a resin or the like to protect the fiber120from mechanical or chemical irritation.

In the waveguide connection structure1according to the present embodiment, as shown inFIG.2BandFIG.2D, after the fiber120is installed in the connector110, the waveguide chip100and the connector110are brought close to each other on a flat plane S to fit the concave-convex portion102and the concave-convex portion112into each other. By adjusting the depth and width of the groove in in advance according to the thickness of the fiber120so that the end face of the waveguide101of the waveguide chip100and the core121of the fiber120match up in this state, fitting the concave-convex portion102of the waveguide chip100and the concave-convex portion112of the connector110into each other with the waveguide chip100and the connector110on the flat plane S makes it possible to realize an optical connection between the waveguide101and the core121passively.

For example, as shown inFIG.2C, by installing the fiber120on the connector110, bringing the connector110close to the waveguide chip100on the flat plane S, and fitting the concave-convex portions102,112into each other, alignment of the waveguide101and the core121is performed passively. The components may be fixed in this state by an adhesive, as necessary. For example, the outer diameter of the fiber120is 125 μm and the diameter of the core is 4 μm.

By forming the waveguide chip100and the connector110constituting the waveguide connection structure1according to the present embodiment from the same substrate and by the same process, alignment can be performed in the top view plane ofFIG.2Awith a precision (0.1 μm or less) fit for microfabrication such as lithography and etching.

In addition, in the cross-sectional view plane ofFIG.2B, even substrate thicknesses normally have a thickness variation of about plus/minus 5% (for example, about plus/minus 50 μm), forming the components at adjacent portions of the same substrate makes it possible to perform alignment with a high precision (0.1 μm or less) while avoiding production variation in the substrate.

Further, while the depth of the groove11of the substrate114is, for example, 62.5 μm, corresponding to the radius of the fiber120, this depth can be made with a precision (0.1 μm) fit for microfabrication by controlling the etching time and conditions.

A production method of the components constituting the waveguide connection structure according to the present embodiment, namely the waveguide chip100and the connector110, will be described with reference toFIGS.3A to3EandFIG.4.

First, a wafer, such as the one shown inFIG.3AandFIG.3B, having a waveguide101, through holes301a,301b,301c,301d, and301e, and a concave portion302, is made.

Specifically, first, a SOI (Silicon On Insulator) wafer substrate is prepared (FIG.4: S41). For example, the thicknesses of the Si of the SOI layer, the SiO2of a BOX (Buried Oxide) layer, and the Si of the substrate are, respectively, 0.2 μm, 2 μm, and 1 mm.

Next, the waveguide101is formed by forming a resist pattern of the waveguide on the SOI layer by lithography, patterning the Si layer by dry etching using the resist pattern as a mask, and removing the resist pattern (S42).

Next, SiO2is deposited using a plasma CVD (Chemical Vapor Deposition) technique at a thickness of 2 μm to form the cladding layer103(S43).

Then, a resist pattern with open regions corresponding to the through holes301a,301b,301c,301d, and301e, and the concave portion302shown inFIG.3Ais formed by photolithography. Using this resist pattern as a mask, the SiO2layer forming the cladding layer103is selectively removed by dry etching to expose an Si layer as an etch stop layer (S44). At this time, each region is positioned relative to the waveguide101, making the resist pattern have an error of 0.01 μm or less.

When the regions of the SiO2forming the through holes301a,301b,301c,301d, and301e, and the concave portion302have been selectively removed, the resist pattern is removed. Next, a resist pattern which is only open at a region corresponding to the concave portion302and covers all other regions (including the regions corresponding to the through holes301a,301b,301c,301d, and301e) is formed by photolithography.

At this time, a width L of the region corresponding to the concave portion302(seeFIG.3A) is, for example, 125 μm, which is the outer diameter of the fiber. The resist pattern need only have a thickness of about 3 μm to be able to cover a level difference caused by the 2 μm thick cladding layer (SiO2layer), and there is no need for a very high positioning precision of the photolithography. Then, using the resist pattern and the underlying SiO2layer as a mask, the Si layer of the substrate104in the region corresponding to the concave portion302is dry etched to dig the concave portion which is to constitute the groove11to a desired depth (S45). The digging depth at this time may generally be set so that a distance D in the height direction between the concave portion302and the waveguide101becomes about half of the diameter of the fiber120. In the present embodiment, the Si layer at the region corresponding to the concave portion302is removed to a depth of about half the outer diameter of the fiber120(fiber diameter 62.5 μm−BOX layer 2 μm−half of waveguide height 0.2 μm=60.4 μm).

For the dry etching, anisotropic etching by ICP-RIE (Inductively Coupled Plasma-Reactive Ion Etching) may be performed. In this case, fabrication precision in the depth direction is 0.03 μm or less, corresponding to one cycle of etching.

Then, the resist pattern is removed.

Next, a resist pattern that covers only the concave portion302is formed by photolithography. The resist pattern need only have a thickness of about 20 μm to be able to cover a level difference of the concave portion302. By improving throwing power due to the viscosity of the resist, if at least the edges around the concave portion302can be covered, the resist pattern does not necessarily have to be formed at a film thickness corresponding to the depth of the concave portion302. Further, there is no need for a very high positioning precision of the photolithography.

Using this resist pattern and the SiO2layer as a mask, the Si layer of the substrate104exposed at the bottoms of the concave portions formed in the regions other than the concave portion302, namely the regions forming the through holes301a,301b,301c,301d, and301eis removed by dry etching (ICP-RIE) all the way to the backside, to form the respective through holes (S46).

FIG.3Bis a cross-sectional view taken along line IIIB inFIG.3A. The through holes formed in regions301a,301b,301c,301d, and301e, as shown inFIG.3B, are preferably shaped to be perpendicular (90°) relative to the surface of the substrate, so that there is no tapering (a gradient in the perpendicular direction of the substrate) when viewed in cross-section, but they may also be of a shape that expands toward the backside.

Once a wafer having the waveguide101, the through holes301a,301b,301c,301d,301e, and the concave portion302as shown inFIG.3AandFIG.3Bhas been made, the wafer is then diced and separated into a first piece which is to become the waveguide chip100and a second piece which is to become the connector110(S47).

Specifically, dicing is carried out using regions311and312with a width of about 70 μm shaded inFIG.3Aas scribe lines, to obtain the waveguide chip100and the connector110as shown inFIG.3C. Since the regions311and312constituting the scribe lines shown inFIG.3Ainclude part of each of the through holes301a,301b,301c,301d, and301e, the waveguide chip100and the connector110have both surfaces formed by dry etching and surfaces formed by dicing in their side surfaces. InFIG.3C, the dotted lines represent side surfaces formed by dicing. While the surfaces formed by dicing have a low fabrication precision and are rough, the other portions, including the side surfaces of the concave-convex portions102,112that fit into each other, are formed by dry etching of the wafer process, and have a high fabrication precision and are flat. In addition, by dicing through part of the concave portion302, the groove11for placing the fiber120is formed penetrating the left and right side surfaces of the connector110.

The above process is the wafer process for making the wafer having the waveguide101, the through holes301a,301b,301c,301d,301e, and the concave portion302as shown inFIG.3A. This wafer process makes it possible to produce the waveguide chip100and the connector110simultaneously.

InFIG.3A, the length of the waveguide chip100in the vertical direction (the up-down direction in the drawing) is longer than the vertical length of the connector110, so the regions311for dicing are discontinuous straight lines which end partway through, but it goes without saying that if the lengths of the waveguide chip100and the connector110in the vertical direction have the same, the wafer may be diced in a grid-like shape.

The connector110may be connected to the waveguide chip100in the following way, for example.

First, the fiber120is fixed in the groove111of the connector110. Since the groove111is microfabricated at a high precision to fit the outer diameter of the fiber120, the fiber120can be passively fixed in the connector110. An adhesive or the like may be used to fix the fiber120.

Then, the chip100and the connector110are brought close to each other on a flat plane S into a state where the concave-convex portions102and112fit into each other as shown inFIG.2C. Since the concave-convex portion102and the concave-convex portion112are made by the same dry etching process, they fit together with a high precision. In the height direction, the groove111is fabricated with a high precision, and is made from an adjacent portion of the same substrate. Accordingly, the waveguide101and the core121are passively aligned with a high precision.

In the order described above, the fiber120is first fixed in the connector110, after which the connector110is fitted into the waveguide chip100, and the end face of the fiber120is pressed against the end face of the waveguide101, but it is also possible to use an order in which the waveguide chip100and the connector110are first fit together, after which the fiber120is pressed against the waveguide chip100and the connector110and fixed in place.

Further, in the above description of the present embodiment, the fiber120is installed in the connector110so that an end face of the fiber120is flush with the end face of the connector110, as shown, for example, inFIG.2C, the waveguide101may be connected with the fiber120protruding from the end face of the connector110. By doing so, any roughness of the end surface of the waveguide101of the chip100formed by dicing is limited to the portion in contact with the fiber, which may reduce the influence of the rough surface.

Further, while the present embodiment is intended for one fiber with one core121, it goes without saying that it may also be applied to a multicore fiber having a plurality of cores, or a fiber array in which a plurality of fibers are arranged.

In addition, the length of the fiber to be fixed to the connector may be suitably set with consideration to mechanical strength and stability, an adhesive may be used to strengthen the fixation, and a coating material may be coated onto the fiber to prevent chemical deterioration of the fiber.

As described above, according to the present embodiment, the waveguide chip100and the connector110are formed from the same substrate using the same microfabrication process, which makes it possible to obtain a waveguide connection structure capable of realizing highly precise and passive alignment.

Next, a second embodiment of the present invention will be described with reference toFIG.5AandFIG.5B.

FIG.5Ais a drawing that corresponds toFIG.3Aused in the above description of the first embodiment, and shows a configuration of a wafer used for producing a waveguide chip500and a connector510of a waveguide connection structure5according to the present embodiment.

As shown inFIG.5B, in the waveguide connection structure according to the present embodiment, a concave-convex portion502of the waveguide chip500and a concave-convex portion512of the connector510have the ends of the convex portions formed in tapered shapes.

As such, in the first embodiment, as shown inFIG.3A, the through holes301a,301b,301c,301d, and301eformed in the wafer are formed in a rectangular shape in a plan view, whereas in the present embodiment, as shown inFIG.5B, when the through holes501a,501b,501c,501d, and501eare formed, they are made to be of a shape in which angular chamfers501a-1,501b-1,501b-2,501c-1,501c-2,501d-1,501d-2, and501e-1are added, and the wafer is processed.

Because of this, the concave-convex portion502and the concave-convex portion512will be of a chamfered shape after dicing, as shown inFIG.5B. This allows for a smooth fit, without causing problems such as the corners of the concave-convex portions colliding and being damaged when fitting.

Third Embodiment

As shown inFIG.6A, a waveguide connection structure6according to a third embodiment of the present invention is of a structure in which concave portions603are further formed in a concave-convex portion602of a waveguide chip600, and leaf springs613are added to a concave-convex portion612of a connector610. In other words, in the waveguide connection structure6according to the present embodiment, there is provided a locking mechanism consisting of locking claws formed on the concave-convex portion of one of the waveguide chip600and the connector610, and locking grooves formed in the other concave-convex portion. The leaf springs613formed from an elastic material correspond to the locking claws mentioned here, and the concave portions603correspond to the locking grooves.

By including such a locking mechanism, when the concave-convex portion602of the waveguide chip600and the concave-convex portion612of the connector610are fitted together, the concave portions603and the leaf springs613fit together, as shown inFIG.6B, making it possible to fix the positions of the chip600and the connector610without using an adhesive or the like.

Further, since the elasticity of the leaf spring613can be controlled by controlling the shape of the spring portion as seen in a top view and the thickness in the thickness direction of the substrate, the construction can be adapted to suit the application.

Fourth Embodiment

A fourth embodiment of the present invention will be described with reference toFIG.7AtoFIG.7E.

FIG.7AtoFIG.7Eshow a process of inserting a chip into a Flip Chip Ball Grid Array (FCBGA) package and surface mounting it on a printed circuit board.

First,FIG.7Ashows an example of a FCBGA substrate702in which bump balls701are formed on a substrate made of an organic resin. In a state where the wafer process is finished, the back surface of the waveguide chip100is polished to give the waveguide chip100a thickness of about 300 μm, after which it is diced into the chip and the connector. The chip100is electrically connected to the substrate702with the surface on which the waveguide101is formed facing down (by flipping the chip100).

At this time, electrical connection by bumps on the chip100side not shown here and land patterns on the substrate702side is carried out, and the distance between the chip100and the substrate702is adjusted. Although not shown here, other components such as chip capacitors and the like may be similarly arranged on the substrate702in the space near the chip100. Further, the electrically connected portions of the end faces of the chip100, except for the side surface which is to be connected to the connector110, may be protectively coated with a resin or the like.

Next, as shown inFIG.7B, a lid703is placed, and the edges of the lid703are fixed to the substrate702with an adhesive or the like. Here, the waveguide chip100and the lid703are connected at a suitable height by a thermally conductive sheet to ensure sufficient thermal conduction. As the thermally conductive sheet, a graphite sheet with a thickness of, for example, 10 μm may be used. The lid703also has an opening704. This constitutes a package705.

Next, as shown inFIG.7C, the package705is surface mounted on a printed circuit board710by reflow soldering. Although not shown here, a plurality of other electrical components such as LSI, chip capacitors, and electrical connectors are surface mounted on the circuit board710in the same process.

Next, as shown inFIG.7D, in a state where the package705is installed on the printed circuit board710, the connector110is inserted through the opening704and fitted into the chip100. At this time, by inserting the connector with its upper surface in contact with the inner upper surface of the lid703or the thermally conductive sheet, positioning is carried out automatically.

Then, as inFIG.7E, the connector110is fitted into the chip inside the package705and is passively aligned, whereby the fiber120and the waveguide on the chip are passively aligned. If necessary, adhesive may be applied in advance to the end surface of the fiber120and the vicinity thereof to be cured by heat treatment or the like after fitting. In addition, after this the opening704may be protected by a resin or the like, or the space formed between the inner surface of the lid703and the chip100may be filled with resin through the opening704.

As described above, after surface mounting the waveguide chip100, which is an opto-electrical component, on the printed circuit board710, passive alignment can be done by simply inserting the connector110.

When performing a conventional active alignment, after mounting the waveguide chip on the printed circuit board, there was a need to hold the fiber and bring it close to the chip near the printed circuit board surface to perform the alignment, but in addition to the need for equipment for holding and centering the fiber in order to do so, there was a problem in that electrical components could not be arranged near the chip on the printed circuit board. In addition, when performing active alignment before mounting on the printed circuit board, managing the excess length of the fiber was bothersome, and there was a problem in that the adhesive used in the connection between the fiber and the chip and the plastic of the commercial optical connector for the other end of the fiber could not withstand the reflow temperature (220° C. or higher) and deteriorated. Further, even when using a conventional commercial optical connector, it is not suited for direct application to a printed circuit board due to its large size and thickness.

By contrast, according to the present embodiment, the waveguide chip and the connector are separated, the connector can be made as small as the chip, and passive alignment is possible. Therefore, optical components such as a chip having a waveguide can be surface mounted by the same process as electrical components, after which the connector of the same small size as the chip may simply be inserted, achieving the superior effect of allowing for optical components to be easily mounted by the same process as electrical components.

REFERENCE SIGNS LIST