JP4283248B2 - Optical circuit structure and optical module - Google Patents

Description

  The present invention relates to an optical circuit structure and a method for manufacturing the same, and more particularly, an optical circuit that reduces the influence of spreading of a resin (for example, an adhesive) on an optical circuit (for example, a planar optical circuit) on mounting. The present invention relates to a structure and an optical module.

  In recent years, optical communication systems capable of transmitting large volumes of information at high speed have attracted attention because of the desire to transmit large volumes of information with the advancement of information technology. In such an optical communication system, an optical fiber is used as a transmission medium for constructing a high-speed and large-capacity communication network. As a technique for increasing the capacity of this optical fiber, a WDM (Wavelength Division Multiplexing) technique is used. Attention has been paid.

  In this WDM, since optical signals of different wavelengths are individually multiplexed on a single optical fiber, optical signals of different wavelengths are multiplexed / demultiplexed particularly in an optical signal transceiver (transceiver). Means are needed. As an example of such multiplexing / demultiplexing means, a wavelength selective filter such as a dielectric multilayer filter is used. Patent Document 1 discloses mounting of this wavelength selective filter on a waveguide substrate. ing.

In such an example of mounting the wavelength selective filter on the waveguide substrate, the wavelength selective filter is fixed to the waveguide substrate with an adhesive.
JP 11-258455 A

  However, since the adhesive is not highly viscous, that is, has high fluidity, it has a spreading property, and there are other elements (filter, wave plate, semiconductor element, electrode, etc.) in the vicinity of the filter fixed by the adhesive. In some cases, the spread adhesive can reach those other elements. As a result, other elements may be adversely affected. In order to reduce the influence on the other elements due to the spread of such an adhesive, it is conceivable that the elements are sufficiently separated from each other. However, this increases the element area and makes it difficult to reduce the size of the device. And it leads to cost increase.

  In addition, in order to answer the problem of cost reduction of devices, many passive alignment mountings using an optical bench have been proposed. In this method, first unevenness is formed on a PLC on which a filter is placed, and second unevenness that fits into the first unevenness is formed on the optical bench, and alignment is performed.

  In such a method, when the surface of the PLC on which the filter is formed is turned over and mounted on the optical bench, the gap between the PLC and the optical bench is narrowed, so that the adhesive on the PLC is unexpected ( For example, when it is turned over and mounted on the optical bench on the surface on which the PLC filter is formed, if it is attached to a region facing the flat portion of the optical bench, etc., the alignment cannot be performed. Therefore, it is necessary to newly provide a process for removing the adhesive adhering to an unexpected part of the PLC, leading to a longer manufacturing time and an increased manufacturing cost.

  This is not limited to the mounting method in which the PLC and the optical bench are connected by fitting, and any method can be used when the desired surface of the optical circuit such as the PLC is turned over and mounted on another member such as the optical bench. It becomes a problem.

  In the case of the passive alignment mounting described above, when the adhesive used to adhere the filter to the PLC spreads to the uneven portion formed on the PLC (a member to be fitted to the uneven portion of the optical bench) and adheres to the uneven portion. There is a possibility that the recesses are narrowed or the convex portions are widened, so that the uneven portions of the PLC and the uneven portions of the optical bench cannot be sufficiently fitted.

  AWG (Arrayed Waveguide Grating) is also widely used as a light multiplexing / demultiplexing means. This AWG has a temperature dependence of the transmission center wavelength due to the temperature dependence of the refractive index of the quartz glass constituting the AWG. In order to compensate for this temperature dependence, a Peltier element or a heater is provided. There is a need. Providing such a temperature compensation element leads to an increase in manufacturing cost and an increase in the size of the device. Therefore, it is required to make the AWG athermal (temperature independent).

  FIG. 1A is a diagram showing an example of a conventional athermal AWG, FIG. 1B is a diagram showing an enlarged portion X in FIG. 1A, and FIG. It is AA 'line cutting | disconnection sectional drawing of 1 (b).

  In FIG. 1A, an athermal AWG 200 has an input / output waveguide 201 composed of one waveguide, a slab waveguide 202 connected to the input / output waveguide 201, and an optical path length connected to the slab waveguide 202. A different arrayed waveguide 203, a slab waveguide 204 connected to the arrayed waveguide 203, and an input / output waveguide 205 composed of a plurality of waveguides connected to the slab waveguide are provided.

  In FIG. 1A, the arrayed waveguide 1 (arrayed waveguide 203) has a plurality of waveguide cores 2 and claddings 3. An athermal groove 4 is formed in the cladding 3 so as to penetrate the waveguide core 2 in a direction substantially perpendicular to the longitudinal direction of the arrayed waveguide 1. The athermal groove 4 is filled with silicone 5 as an athermal resin, and the filling of the silicone 5 compensates the temperature dependency of the quartz glass constituting the arrayed waveguide 1. At this time, as shown in FIGS. 1B and 1C, the silicone 5 does not fit in the athermal groove 4 but spreads from the athermal groove 4.

  In addition, a groove 6 is formed in the clad 3 so as to penetrate the waveguide core 2 in a direction substantially perpendicular to the longitudinal direction of the arrayed waveguide 1. A wave plate 7 is fitted in the groove 6 and fixed by an adhesive 8. At this time, the adhesive 8 spreads from the wave plate 7 as well as the silicone 5.

  When manufacturing such an athermal AWG, first, an athermal groove 4 is formed on the clad 3 of the arrayed waveguide 1 by dicing or the like, and the athermal groove 4 is filled with silicone 5. After confirming the chip characteristics, a groove 6 is formed by dicing while filling the silicone 5, the wave plate 7 is inserted into the groove, and the wave plate 7 is fixed with an adhesive 8.

  However, when the wave plate 7 is inserted with the silicone 5 filled, a dicing blade used to form the groove 6 into which the wave plate is inserted may come into contact with the silicone 5. Due to this contact, mechanical damage to the silicone 5 occurs, and the silicone 5 peels off due to this mechanical damage, or optical characteristics and reliability are deteriorated.

  In order to solve such a problem, conventionally, 1) the groove 6 for the wave plate 7 and the athermal groove 4 are separated sufficiently to avoid the damage caused by the dicing blade. Or 2) Before forming the groove 6, the silicone 5 is peeled and washed once, then the groove 6 is formed, the wave plate 7 is inserted, and then the silicone 5 is filled again, thereby causing damage to the dicing blade. Was avoiding.

  However, in 1), if the groove 6 and the athermal groove 4 are formed sufficiently separated, the spectroscopic circuit becomes large, which leads to an increase in the size of the device. In 2), once the silicone 5 is peeled and washed, and after the wave plate 7 is inserted, the silicone 5 is filled again, which requires a complicated process, resulting in an increase in manufacturing cost and an increase in cost. End up.

  In addition to the above, the spread of the resin also applies to members such as semiconductor lasers (LD) and electrodes, resins for protecting functional polymers, and adhesives used to fix the members to the flat part of the substrate. Is a problem.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an optical circuit structure and an optical module capable of reducing the manufacturing cost and reducing the size.

The present invention, in order to achieve the above object, an invention according to claim 1, a waveguide having a cladding and a core, the resin filling groove provided on the cladding to fill the resin,
The restraining means disposed at a predetermined distance from the resin filling groove, and when the resin is supplied to the resin filling groove, the resin from the region between the resin filling groove and the restraining means. There example Bei and suppression means for suppressing flowing out, the suppressing means comprises a first suppression means is the resin filling groove parallel-arranged recesses or protrusions, the end of the first suppression means Second restraining means that is a recess provided from the vicinity of the portion toward the resin filling groove, and when the first restraining means is the recess, the recess does not reach the core. It is an optical circuit structure characterized by being formed in a clad .

The invention of claim 2 is the invention according to claim 1, wherein the first suppression means is characterized in that at least one or more recesses.

The invention of claim 3 is the invention of claim 2, wherein, prior to SL at least one of the at least one or more of the recesses, characterized in that it is connected to the second suppression means .

The invention of claim 4 is the invention according to claim 1, wherein the first suppression means is characterized in that one or more protrusions even without low.

The invention of claim 5 is the invention according to any one of claims 1 to 4, wherein the resin is characterized by a athermal resin.

Invention of Claim 6 is equipped with the optical circuit structure in any one of Claim 1 thru | or 5 , and an optical bench, The said optical circuit structure has several notch structure, The said optical bench is The optical circuit structure is passively mounted on the optical bench by fitting the plurality of notches to the plurality of notches, and fitting the plurality of notches to the plurality of recesses. This is an optical module .

  As described above, according to the present invention, since the resin is prevented from flowing out from the predetermined region, another member is provided in the vicinity of the region where the resin is supplied without using a complicated process. Thus, the manufacturing cost can be reduced and the size can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings described below, components having the same function are denoted by the same reference numerals, and repeated description thereof is omitted.
(First embodiment)
In this embodiment, when a desired member (for example, a dielectric multilayer filter) is fixed to a groove formed in an optical circuit with a resin (for example, an adhesive), the resin used for the fixing is a predetermined region. To reduce outflow to the outside area.

FIGS. 2A and 2B are diagrams showing a configuration for reducing the outflow of resin according to the present embodiment.
In FIG. 2A, a filter insertion groove 21 for inserting a dielectric multilayer filter (hereinafter also simply referred to as “filter”) is formed, and the filter is inserted into the filter insertion groove 21 before the adhesive. It is fixed with. In addition, a rectangular groove 22 as a resin spreading suppression groove is formed substantially parallel to the filter insertion groove 21 at a predetermined distance from the filter insertion groove 21. By forming the groove 22 in this way, the adhesive used for fixing the filter falls into the groove 22, and the spread of the adhesive to the outside region can be prevented or reduced.

  In addition, the shape of the groove | channel 22 is not limited to the said rectangle, What kind of shape may be sufficient if it can form a groove | channel, such as circular, an ellipse, a triangle, and a square. In addition, an inclination may be formed in a region between the filter insertion groove 21 and the groove 22 to promote the flow of the adhesive from the filter insertion groove 21 to the groove 22. Further, the distance between the filter insertion groove 21 and the groove 22 may be set according to the design of the optical circuit. That is, when it is desired to provide other elements in the vicinity of the filter insertion groove 21, or to provide a notch structure in passive active mounting, the filter insertion groove depends on the location where these other members are to be provided. What is necessary is just to set the distance between 21 and the groove | channel 22.

  In the present specification, the “other member” is a member other than a target member fixed by resin or a member filled with resin, for example, an element such as a filter, a wavelength plate, a semiconductor element, or an electrode. There are also convex portions such as notch structures and concave portions such as grooves and depressions.

  Further, the size in the longitudinal direction of the groove 22 may be set according to the design of the optical circuit. That is, the size may be such that the adhesive from the filter insertion groove 21 does not reach other members. Further, the number of the grooves 22 is not limited to one by one with the filter insertion groove 21 interposed therebetween, and a plurality of grooves may be formed, and any combination of the numbers may be used. That is, the number of grooves provided may be at least one or more. Further, the filter insertion groove 21 may be provided with a groove only on one side. When a plurality of grooves 22 are provided, the plurality of grooves may be formed to have a periodic structure, or may be formed randomly. Thus, it is preferable that the formed grooves have a periodic structure because the width and depth of the grooves can be made uniform. Further, in consideration of the condition that the resin always reaches the upper end of the wall forming the groove 22 when the resin is in the groove 22, the relationship between the width h and the depth W of the groove 22 is 2hsinθ> W (θ; It is desirable to set so as to satisfy the contact angle of the resin with the groove.

  Further, a surface treatment that increases the affinity for the resin (here, adhesive) used for the region between the filter insertion groove 23 and the groove 22 and at least one of the grooves 22, that is, the above-described A surface treatment may be performed so that the region has high wettability to the resin. Preferably, the groove 22 has a surface treatment such that the contact angle with the resin (here, adhesive) used is smaller than the region between the filter insertion groove 23 and the groove 22.

  Such a groove 22 can be produced by dicing, etching, or the like.

  In the present embodiment, as described above, the grooves are used to reduce the outflow of the adhesive, but the present invention is not limited to this, and the outflow of the adhesive can be reduced by pouring the adhesive, such as a depression. Any shape may be used as long as it is concave.

  Furthermore, in this embodiment, when the waveguide core is embedded in the optical circuit in which the recess for reducing the outflow of the adhesive is formed, and the recess is formed across the waveguide core, the recess Is formed at a depth that does not reach the vicinity of the embedded waveguide core. However, this is not the case when the concave portion is not formed across the waveguide core.

  Moreover, in FIG.2 (b), the filter insertion groove | channel 23 for inserting a filter is formed, and after a filter is inserted in the filter insertion groove | channel 23, it is fixed with an adhesive agent. Further, a rectangular platform 24 is formed with respect to the filter insertion groove 23 at a predetermined distance from the filter insertion groove 23. By forming the platform 24 in this way, the adhesive used for fixing the filter is blocked by the platform 24, and the spread of the adhesive to the outside region can be prevented or reduced.

  Similarly to the groove 22, the shape of the platform, the distance from the filter insertion groove, the size of the platform, and the number of platforms may be set for the platform 24.

  Such a platform 24 can be made of an organic material such as a resist or a polymer. Moreover, it can produce by etching so that the part which wants to form a platform is left.

  Further, the surface treatment that increases the affinity for the resin (here, the adhesive) used for the region between the filter insertion groove 23 and the platform 24, that is, the region described above is against the resin. A surface treatment that increases wettability may be performed. Further, for example, plasma treatment or the like may be performed on the platform 24 so as to repel the resin (solvent) to be used. The above two surface treatments may be combined.

  Moreover, when providing a platform separately, you may make it provide the platform 24 using the material (material which enlarges the contact angle of this resin) which repels resin (solvent) used as the material. .

  In the present embodiment, as described above, the platform is used to reduce the outflow of the adhesive, but the present invention is not limited to this. Any shape may be used as long as it is convex and can reduce the outflow of water.

  In the present embodiment, the groove 22 and the platform 24 are formed substantially parallel to the filter insertion groove, but are not limited thereto. In the present embodiment, it is important to suppress the outflow of the adhesive at the groove 22 and the platform 24, so any arrangement may be employed as long as the outflow of the adhesive can be appropriately suppressed.

  Thus, in this embodiment, the groove | channel 22 or the platform 24 is used as a means to suppress the outflow of resin (here adhesive) from a predetermined area | region to an outer area | region. The groove 22 is for suppressing the spread of the resin by dropping the resin to flow out from the predetermined area to the outside area, and the platform 24 tries to flow out from the predetermined area to the outside area. This is for suppressing the spread of the resin by clogging the resin. Therefore, the grooves 22 and the platform 24 can prevent the resin such as the adhesive from being present in an undesired place. That is, it is possible to reduce the outflow of the resin outside the region that allows the presence of the resin. Therefore, another member can be provided in the vicinity of the filter insertion groove 21 without being affected by the adhesive, and the optical circuit can be reduced in size and cost.

  Such “region allowing the presence of resin” is determined according to the design of the optical circuit, and is the distance between the groove or platform and the filter insertion groove, the shape or size of the groove or platform. The distance between the filter insertion groove and another member, the viscosity of the resin used, and the like are determined.

  In the undesired place, when the resin is present, the surface of the optical circuit on which the desired member fixed by the resin is formed is turned over and mounted on the optical bench (passive alignment mounting). Includes areas that significantly reduce mounting accuracy. That is, the presence of the resin includes an area where the resin becomes an obstacle and the mounting surfaces are not well bonded.

  Also, as the above undesirable place, other member itself, a resin (for example, an adhesive) used to fix the member that surrounds the other member, or an athermal resin that extends from the groove, Also included are resins containing a light-shielding agent used for reducing VOA (Variable Optical Attenuator) and AWG crosstalk, functional polymers, and the like.

  In this specification, “the presence of the resin” means that the resin is attached to the optical circuit by curing or the like, or is in a state of high fluidity, or the above-mentioned curing. This means that the resin is “in place” even in the state between the applied state and the state of high fluidity.

  Furthermore, in the present embodiment, the filter is used as being fixed with an adhesive, but the present invention is not limited to this, and a wave plate or the like may be used. In the present embodiment, it is important to suppress the outflow of the resin when the member is fixed with a resin such as an adhesive, and any member to be fixed may be used. At this time, it goes without saying that the groove for inserting the member may not be provided as long as the member is formed with a groove and does not need to be fitted into the groove when the member is fixed with the resin. Specifically, it is a case where a member is fixed by dropping a resin on a waveguide to be formed and placing the member on the dropped resin. At this time, the spread of the resin protruding from the region where the member is arranged is suppressed by the above means.

FIG. 3 is a top view of a PLC having a dielectric multilayer filter according to the present embodiment.
In FIG. 3, a filter 32 is fixed to the PLC 31 by an adhesive so as to be substantially perpendicular to the PLC 31. Further, three platforms 33 are formed at a predetermined distance from the filter 32. Further, each of the four corners of the PLC 31 has a notch structure 34 so that passive alignment can be appropriately mounted on the optical bench.

  In this manner, the platform 33 functions as a dam with respect to the adhesive used for the filter 32, and the adhesive can be prevented from reaching the notch structure 34. As a result, the alignment accuracy of the passive alignment mounting of the PLC 31 to the optical bench increases, and the yield can be improved. Further, by increasing the number of the floors 33, it is possible to further suppress the outflow of the adhesive to the notch structure 34.

  4A is a cross-sectional view taken along the line BB ′ of FIG. 3, and FIGS. 4B to 4D show grooves and combinations of the stage and grooves instead of the stage 33 of FIG. 3. It is a BB 'line cutting sectional view at the time of using.

  In the present embodiment, as shown in FIGS. 4C and 4D, a platform and a groove may be combined. FIG. 4C is a diagram showing a form in which a combination of a platform and a groove is formed by the PLC 31, and FIG. 4D is a diagram in which the platform and the groove are formed by different members, that is, the groove is formed by the PLC 31. FIG. 3 is a diagram showing a form formed by a member separate from the PLC.

  Moreover, in this embodiment, you may make it provide a hollow newly between the filter insertion groove 21 (23) and the groove | channel 22 (bed 24). FIG. 5A is a diagram showing a configuration in which a recess 25 is formed between the filter insertion groove 21 and the groove 22, and FIG. 5B shows a recess 25 between the filter insertion groove 23 and the platform 24. It is a figure which shows the structure which formed.

  As described above, by forming the depression 25 from the vicinity of the end of the groove 22 or the platform 24 toward the filter insertion groove, the resin flows into the depression, and the suppression of the outflow of the resin such as the adhesive is further improved. Further, by controlling the position of the recess 25, it is possible to control the lengths of the grooves 22 and the platform 24 in the longitudinal direction. This control is particularly effective when it is desired to suppress the outflow of resin locally.

  In FIG. 5A, the groove 22 and the depression 25 are separate depressions, but the same depression may be formed by communicating a part of the groove 22 and a part of the depression 25. A combination of a form in which the grooves 22 and the depressions 25 are separate and a form in which they are the same may be used. In FIG. 5B, the platform 24 and the depression 25 are provided at a predetermined distance, but one surface of the wall of the depression 25 and one surface of the platform 24 are included in substantially the same plane. The platform 24 and the depression 25 may be provided. A combination of a form in which the platform 24 and the depression 25 are provided at a predetermined distance away from each other, and a form in which one surface of the wall of the depression 25 and one surface of the platform 24 are included in substantially the same plane may be used.

FIG. 6 is a top view of a configuration in which a depression is formed in the PLC having the dielectric multilayer filter shown in FIG. 3 inside the region where the platform is formed.
In FIG. 6, a recess 35 is formed from the vicinity of the end of the platform 33 toward the filter 32. As shown in the figure, by providing four depressions 35, it is possible to prevent the adhesive from flowing out to the side wall or the back surface of the PLC 31. Further, since the adhesive flows into the recess 35, the amount of the adhesive that cannot be stopped by the platform 33 can be reduced. Therefore, suppression of the outflow of the adhesive to the notch structure 34 can be further improved.

  In the present embodiment, a plurality of shallow grooves may be arranged in order to reduce the flow of resin such as an adhesive to an undesired place. At this time, it is desirable that the plurality of grooves have a periodic structure. FIG. 7A is a diagram illustrating a configuration according to the present embodiment that reduces the outflow of resin by periodically arranging shallow grooves. 7B is a cross-sectional view taken along the line CC ′ of FIG. 7A, and FIG. 7C shows the shape of the periodic structure 72 of the shallow groove of FIG. FIG. 6 is a cross-sectional view taken along the line CC ′ in the case of a shape.

  In FIG. 7A, shallow groove periodic structures 72 are formed on both sides in the longitudinal direction of the filter insertion groove 71. Each of the grooves constituting the shallow groove periodic structure 72 has a rectangular shape as shown in FIG. The depth of each groove of the shallow groove periodic structure 72 is set to a depth that can increase the contact angle of the resin (here, adhesive) used. When the adhesive flows into the periodic structure 72 of the shallow groove set as described above, it is possible to reduce the adhesive from flowing out to an undesired place (in the arrow direction P in FIG. 7A).

  In the present embodiment, the cross-sectional structure of the periodic structure 72 of the shallow groove is not limited to a rectangular shape. For example, the contact angle of the target resin such as a v shape as shown in FIG. Any shape may be used as long as the shape can be increased.

  It is also useful to provide a new depression at the end of the shallow groove periodic structure 72. FIG. 8A is a diagram showing a configuration in which a recess is provided at the end of a periodic structure of shallow grooves according to the present embodiment, and FIG. 8B is a PLC to which the configuration of FIG. 8A is applied. FIG. 8C is a cross-sectional view taken along the line DD ′ of FIG. 8B.

In FIG. 8A, a recess 73 is formed at the end of the shallow groove periodic structure 72.
A groove 74 is formed substantially parallel to the longitudinal direction of the grooves constituting the periodic structure 72 of the shallow grooves.

  Thus, by forming the depression 73, the adhesive used when fixing the filter to the filter insertion groove 71 flows into each groove of the periodic structure 72 of the shallow groove, and the introduced adhesive is depressed by capillary action. 73. At this time, the adhesive that has flowed out in the direction of the arrow P beyond the periodic structure 72 of the shallow groove flows into the depression 74. Therefore, the outflow of the adhesive to an undesired place can be further reduced, and the adhesive that has flowed into the shallow groove periodic structure 72 by capillary action flows into the recess 73, so that the adhesive flows onto the shallow groove periodic structure 72. There will be almost no adhesive left. Therefore, almost no adhesive remains on the optical circuit to which the configuration is applied. Therefore, when passive alignment mounting is performed, the passive is accurately performed without performing the process of removing the remaining adhesive. Alignment mounting can be performed.

  Further, as described above, since the flow of the adhesive to the undesired place is suppressed by the shallow groove periodic structure 72, the depression 73, and the groove 74, the spread of the adhesive to the notch structures 75 is prevented. In other words, in the passive alignment mounting, the alignment accuracy can be improved and the yield can be increased.

  In the present embodiment, the shallow groove periodic structure 72, the depression 73, and the groove 74 are formed in the same process by utilizing the microloading effect when the shallow groove periodic structure 72, the depression 73, and the groove 74 are formed. Thus, the manufacturing time can be shortened and the cost can be reduced.

  In FIGS. 8A to 8B, each groove constituting the periodic structure 72 of the shallow groove is provided at a predetermined distance from the depression 73, but at least one of the grooves is You may make it connect with the hollow 73. FIG. At this time, considering that the resin flows from the filter insertion groove 71 in the arrow direction P, it is preferable that the groove formed closest to the filter insertion groove 71 is connected to at least the recess 73. That is, it is preferable to connect at least one or more grooves including the groove on the filter insertion groove 71 side to the recess 73.

  In the present embodiment, as shown in FIGS. 9A to 9D, a platform 76 is used as a means for reducing the outflow of the adhesive from the periodic structure 72 of the shallow groove to the outside. May be. 9A, the recess 73 and the platform 76 are provided apart from each other by a predetermined distance. However, as shown in FIG. 9D, the U-shaped platform 77 having the projection 78 is replaced with the projection 78. The surface on the recess side may be provided so as to be substantially the same surface as the surface on the protrusion 78 side of the wall forming the recess of the recess 73. By arranging in this way, the resin that reaches the floor 76 and travels along the edge of the floor 76 falls into the depression 73 via the protrusion 78. Therefore, it is possible to further suppress the outflow of the resin. In addition, by setting the angle 79 to an acute angle of 90 ° or less, it is possible to further suppress the outflow of the resin transmitted to the protrusion 78. The above-described U-shaped platform 77 is effective not only in combination with the periodic structure 72 and the depression 73 of the shallow groove but also when the platform is used alone.

Hereinafter, it will be described that an optical module such as a transceiver is manufactured by passively mounting the optical circuit structure according to the present embodiment on an optical bench.
FIG. 10 is a configuration diagram of a PLC suitable for passive alignment mounting according to the present embodiment.
In FIG. 10, the PLC 100 includes a clad 101 in which a waveguide core 102 branched in a Y shape is embedded. A filter insertion groove 103 is formed in the clad 101 so as to cross the Y-shaped branch portion of the waveguide core 102 and penetrate the waveguide core 102. A filter 104 is inserted into the filter insertion groove 103 and is fixed by an adhesive. In addition, on the both sides in the longitudinal direction of the filter insertion groove 103, stairs 105a and 105b are formed at a predetermined distance. At this time, the predetermined region is a region between the platform 105a and the filter insertion groove 103 (filter 104) and a region between the step 105b and the filter insertion groove 103 (filter 104).

  Further, notch structures 106 are formed in the vicinity of the four corners of the PLC 100, and passive alignment mounting is performed by fitting the notch structures 106 into alignment grooves provided in the optical bench.

  In FIG. 10, since the adhesive 105 is prevented from flowing out from the predetermined area to the outside area by the steps 105 a and 105 b, it is possible to reduce the amount of the adhesive reaching the notch structure 106. It becomes. Therefore, in the passive alignment mounting of the PLC 100 and the optical bench, the alignment accuracy can be improved and the yield can be increased.

  In the present embodiment, a platform may be provided as shown in FIG. In FIG. 11, the stage 111 and the notch structure 112 are formed from the clad 101 by etching the clad 101 so as to leave the stage 111 and the notch structure 112.

  Although one filter 104 is formed in FIGS. 10 and 11, the present invention is not limited to this. That is, the number of filters and the members to be mounted may be set according to the design of the optical circuit. At this time, it is only necessary to provide a platform or a groove for each member fixed to the optical circuit to suppress the outflow of the adhesive from a predetermined region.

FIG. 12 is a diagram illustrating a state in which the PLC is passively mounted on the optical bench according to the present embodiment.
In FIG. 12, the optical bench 120 has a receiving groove 121 and four alignment grooves 122. In FIG. 12, the optical bench 120 shows only the accommodation groove 121 and the alignment groove 122, but may include other members such as a light receiving element. The width of the housing groove 121 is set so that the surface of the PLC 100 on which the filter 104 is formed is turned over so that the filter 100 and the platform 105a and 105b are all housed when the PLC 100 is mounted on the optical bench 120. . Outflow of the adhesive from a predetermined area of the PLC 100 (an area between the platform 105a and the filter insertion groove 103 and an area between the step 105b and the filter insertion groove 103) to the outside is suppressed, At this time, since the predetermined area is accommodated in the accommodating groove 121 of the optical bench 120 at the time of mounting, it is possible to reduce the hindrance to the mounting due to the adhesive adhering to an extra portion of the PLC 100. In addition, since the outflow of the adhesive to the notch structure 106 of the PLC 100 is also suppressed, the alignment accuracy at the time of passive alignment mounting can be increased, and the yield can be improved.

  In the case where grooves are used instead of the floors 115a and 115b in the PLC 100, the accommodation groove 121 of the optical bench 120 may be of a size that accommodates the filter 104 of the PLC 100.

(Second Embodiment)
This embodiment is used to fix other members fixed in the vicinity of the groove and the member when the groove formed in the optical circuit is filled with resin (for example, athermal resin such as silicone). This reduces the spread of the resin to the adhesive.

  FIG. 13 is a diagram illustrating an example of an athermal AWG according to the present embodiment, FIG. 13A is a top view of the athermal AWG according to the present embodiment, and FIG. FIG. 13C is a cross-sectional view taken along line FF ′ of FIG. 13A, and FIG. 13C is a cross-sectional view taken along line FF ′ when a platform is used instead of the groove 136 of FIG.

  In FIG. 13A, the AWG includes an arrayed waveguide 131, and the arrayed waveguide 131 has a plurality of waveguide cores 132 and a clad 133. An athermal groove 134 is formed in the cladding 133 so as to penetrate the waveguide core 132 in a direction substantially perpendicular to the longitudinal direction of the arrayed waveguide 131. The athermal groove 134 is filled with silicone 135 as an athermal resin, and the filling of the silicone 135 compensates for the temperature dependence of the quartz glass constituting the arrayed waveguide 1.

  On the wavelength plate insertion groove (described later) side of the athermal groove 134, three shallow grooves 136 as resin spreading suppression grooves are formed in a direction substantially perpendicular to the longitudinal direction of the arrayed waveguide 131. That is, a periodic structure of shallow grooves is formed. Further, two depressions 137 are formed so as to sandwich the athermal groove 134 on the athermal groove 134 side in a direction substantially perpendicular to the groove 136. Note that the depression 137 may not be provided.

  The clad 133 is formed with a wave plate insertion groove 138 penetrating the waveguide core 132 in a direction substantially perpendicular to the longitudinal direction of the arrayed waveguide 131. A wave plate 139 is fitted in the wave plate insertion groove 138 and is fixed by an adhesive 140. At this time, the adhesive 140 spreads from the wave plate 139.

  The silicone 135 spreads in the same manner as the adhesive 140, but as shown in FIGS. 13A and 13B, the silicone 135 that spreads without being fully filled in the athermal groove 134 flows into the groove 136. Then, due to capillary action, the groove 135 spreads rapidly in the longitudinal direction of the groove 136, so that the outflow of the silicone 135 to the direction perpendicular to the groove 136, that is, the wavelength plate 139 side can be reduced. Therefore, even when the wavelength plate insertion groove 138 is formed by dicing after the silicone is dropped into the athermal groove 134 to form the silicone 135, mechanical damage to the silicone 135 by the dicing blade can be avoided. That is, even when the wave plate 139 and the athermal groove 134 are close to each other, it is possible to prevent the silicone 135 and the dicing blade from contacting each other.

  That is, since it is not necessary to sufficiently separate the athermal groove 134 and the wave plate insertion groove 138, the apparatus can be reduced in size. Further, the resin (here, silicone) removal step, re-coating, and baking steps can be omitted without affecting the optical characteristics, and the manufacturing time and cost can be reduced.

  In the present embodiment, the number of grooves 136 is not limited to three, and it is sufficient that there are at least one groove.

  Further, in the present embodiment, the means for suppressing the outflow of silicone is not limited to the groove 136, and as shown in FIG. 13C, a platform 141 may be provided, or the groove and the platform A combination of these may be used.

  In this embodiment, the groove 136 may be formed up to the end face of the optical circuit, or may not be formed. When the groove 136 is not formed up to the end face of the optical circuit, it is more preferable because silicone spreading in the longitudinal direction of the groove 136 due to capillary action can be prevented or reduced from leaking to the side wall and back surface of the optical circuit.

  In the present embodiment, as shown in FIG. 19, a recess 191 that functions as a dam may be formed at the end of the groove 136. By forming a depression at the end of the groove 136 in this way, the silicone spreading in the longitudinal direction of the groove 136 due to capillary action flows down into the depression as described above, and the silicone leaks to the side wall and back surface of the optical circuit. Can be prevented or reduced. Further, as shown in FIG. 20, a recess 201 (a groove in a form in which the recess 137 and the recess 191 in FIG. 19 are connected) is arranged so as to sandwich the athermal groove and a groove 136 is connected to a part of the athermal groove. You may make it provide.

  In addition, when all the grooves and the depressions are connected, when the amount of the resin accumulated in the depressions increases, the resin penetrates all the groove structures, and conversely, the resin may be spread. For this reason, it is also effective to form only one or two of the grooves closest to the resin application region so as to be connected to the recess.

  Fig.14 (a) is a figure which shows the mode of the connection of the resin spreading | diffusion suppression groove | channel and the hollow which functions as a dam based on this embodiment, FIG.14 (b) is GG of Fig.14 (a). FIG. Moreover, FIG.14 (c) is a figure which shows a mode that a separate hollow is connected to each groove | channel of the resin spreading | diffusion suppression groove | channel based on this embodiment.

  In FIG. 14A, a recess 143 is formed at the end of the resin spreading suppression groove 142. In such a configuration, the resin 144 that has spread through the resin spread suppressing groove 142 flows into the recess 143, but as shown in FIG. 14B, the connecting portion between the resin spread suppressing groove 142 and the recess 143. When the resin 144 has a steep step and the viscosity and surface tension of the resin 144 are high, the resin 144 may not spread effectively in the depression 143 as shown in FIG.

  In addition, although Fig.14 (a) has shown the structure by which all the grooves are connected with respect to one hollow, it is not limited to this. That is, as shown in FIG. 14C, the recesses 155a, 155b, and 155c may be connected to the resin spreading suppression grooves 142, respectively.

  Therefore, as shown in FIGS. 15A and 15B, a tapered slope portion 152 is provided in the vicinity of the connecting portion so that the step of the connecting portion between the resin spreading suppressing groove 151 and the recess 153 is not steep. The tapered portion may be widened as the slope 152 approaches the recess 153. Thus, by providing the slope part 152, as shown in FIG.15 (b), the resin 154 can be poured into the hollow 153 effectively. In the present embodiment, the slope portion 152 is tapered, but may not be tapered.

  In addition, although Fig.15 (a) has shown the structure by which all the grooves are connected with respect to one hollow, it is not limited to this. That is, as shown in FIG. 15C, the depressions 156a, 156b, and 156c may be connected to the slope portions 152, respectively.

  Further, as shown in FIG. 16, a recess is connected to one end of each of the two sets of resin spread suppressing grooves sandwiching the athermal groove, and the other ends of the two sets of resin spread suppressing grooves are connected by the groove. The configuration is also effective.

  In FIG. 16, a resin spreading suppression groove 162 is formed so as to surround three sides of the athermal groove 161. Further, slope portions 163 are formed at both ends of the resin spread suppressing groove 162, and the widest portion of the tapered portion of the slope portion 163 is connected to the recess 164. With such a configuration, it is possible to suppress the spread of the silicone 165 locally.

  In addition, although Fig.16 (a) has shown the structure by which all the grooves are connected with respect to one hollow, it is not limited to this. That is, as shown in FIG. 16B, the recesses 166a to 166f may be connected to the slope portions 162, respectively.

  In the present embodiment, a combination of a form in which one groove is connected to one recess and a form in which a plurality of grooves are connected to one recess may be used.

  In the above description, an athermal AWG is taken up as an example of an optical circuit. However, this technology can also suppress resin spread even for an optical integrated circuit formed by a PLC such as a wavelength filter or a dispersion compensator. It is valid.

(Third embodiment)
In this embodiment, an example of a method for manufacturing an optical circuit described in the first and second embodiments will be described.
In this embodiment, there are various means as means for forming grooves and depressions in the optical circuit, but recesses such as grooves and depressions can be formed in the optical circuit by etching and dicing. When a plurality of recesses are formed in the optical circuit by etching, it is effective to use the microloading effect.

FIG. 17 is a diagram showing a method for producing an optical circuit structure having a filter insertion groove and a shallow-period groove structure according to the present embodiment.
First, a PLC 170 having a waveguide core 171 in which a filter is to be formed is prepared (FIG. 17A). Next, a photoresist is applied onto the PLC 170 by spin coating or the like to form a photoresist film 172 (FIG. 17B). Next, the PLC 170 is placed on a hot plate or the like, baked for a predetermined time, and then cooled to room temperature. Next, the pattern on the photomask is transferred to the photoresist film 172, and the photoresist other than the pattern on the photoresist film 172 is removed, so that the filter insertion etching mask pattern 173 and the shallow groove are formed on the photoresist film 172. A periodic structure etching mask pattern 174 is formed (FIG. 17C). At this time, by controlling the photomask pattern, the shallow groove periodic structure etching mask pattern 174 is formed narrower than the width of the filter insertion etching mask pattern 173.

  Next, the PLC 170 having a filter insertion groove 175 and a shallow groove periodic structure 176 is obtained by etching the PLC 170 by dry etching or wet etching and removing the photoresist film 172 remaining on the PLC 170 (FIG. 17). (D)).

  As described above, by utilizing the microloading effect, grooves having different depths by one etching, that is, the periodic structure 176 of the filter insertion groove 175 and the shallow groove can be formed. Cost reduction can be achieved and manufacturing load can be reduced.

  At this time, the width of the shallow groove periodic structure etching mask pattern 174 and the width of the filter insertion etching mask pattern 173 is set so that each groove of the shallow groove periodic structure 176 is formed even if the filter insertion groove 175 passes through the waveguide core 171. Is set so as not to reach the vicinity of the waveguide core 171.

  At the time of groove formation, it is effective to reduce the contact angle of the groove region with the resin compared to other regions. In order to change the contact angle, oxygen plasma or the like may be irradiated in a state where a resist or the like exists in a region excluding the groove portion.

  In FIG. 17, the filter insertion groove 175 and the shallow groove periodic structure 176 are collectively formed. However, after the filter insertion groove 175 is formed, the shallow groove periodic structure 176 is formed in a groove depth by another process. May be formed by etching at a depth that does not affect the optical characteristics.

  Also, when forming multiple recesses in the optical circuit by dicing, when forming recesses that suppress the outflow of resin, dicing so that the depth of the recesses does not affect the optical characteristics. Need to do. If the recess is formed at a depth exceeding the range that does not affect the optical characteristics, the element characteristics deteriorate due to the loss of the optical circuit, the phase error, etc., and the yield decreases. Specifically, the depth formed by dicing is preferably 1/3 or less of the cladding thickness of the optical circuit.

  As a means for reducing the outflow of resin, when forming a convex shape on the upper part of the clad, a method of applying a photosensitive polymer and performing exposure and development and, if necessary, a curing treatment with heat, etc. Is the easiest way. In order to form a pattern with higher accuracy, the pattern is produced by dry etching using a resist or metal film patterned with a clad layer or polymer layer. As the polymer used here, it is effective to use a fluorine resin having water repellency with respect to the solvent.

(Fourth embodiment)
FIG. 18 is a view showing a lattice type optical circuit provided with three stages of asymmetric Mach-Zehnder interferometers according to the present embodiment.

  In the lattice type optical circuit 181, the input waveguide 182 is connected to the input port of the optical coupler 183, and one end of the arm waveguide 184 and one end of the arm waveguide 185 are connected to the output port, respectively. Has been. The other end of the arm waveguide 184 and the other end of the arm waveguide 185 are connected to the input port of the optical coupler 186, respectively, and the one end of the arm waveguide 187 is connected to the output port of the optical coupler 186, respectively. And one end of the arm waveguide 188 are connected. The other end of the arm waveguide 187 and the other end of the arm waveguide 188 are respectively connected to the input port of the optical coupler 189, and one of the arm waveguides 190 is connected to each of the output ports of the optical coupler 189. The end and one end of the arm waveguide 191 are connected. The other end of the arm waveguide 190 and the other end of the arm waveguide 191 are connected to the input port of the optical coupler 192, respectively, and the output waveguide 193 is connected to the output port of the optical coupler 192, respectively. ing. The connection of each member is an optical connection.

  The arm waveguide 184 and the arm waveguide 185 are set such that the length of the arm waveguide 185 is longer than the length of the arm waveguide 184 so as to have a predetermined path difference. Similarly, the lengths of the arm waveguide 187 and the arm waveguide 188 and the lengths of the arm waveguide 190 and the arm waveguide 192 are set so as to have a predetermined path difference.

  As can be seen from FIG. 18, the lattice type optical circuit 181 has a configuration in which asymmetric Mach-Zehnder interferometers are connected in three stages.

  In the lattice-type optical circuit 181 having such a configuration, when an athermal groove is formed in one of the first arm waveguide pair (arm waveguides 184 and 185) and the athermal resin is filled, it is removed from a predetermined region. As a means for suppressing the outflow of the resin (here, athermal resin) to this region, it is effective to provide a concave portion or a convex portion in the vicinity of the athermal groove. As described above, by providing the concave portion and the convex portion, it is possible to suppress the outflow of the athermal resin to other members such as electrodes arranged in the vicinity of the athermal groove.

  Similarly, when an athermal groove is formed in either one of the second arm waveguide pair (arm waveguides 187 and 188) or one of the third arm waveguide pair (arm waveguides 190 and 191), As a means for suppressing the outflow of the resin (here, the athermal resin) from the predetermined area to the outside area, a concave portion or a convex portion may be provided in the vicinity of the athermal groove.

  In this embodiment, the lattice type optical circuit has a configuration in which three stages of asymmetric Mach-Zehnder interferometers are provided. However, the number of the asymmetric Mach-Zehnder type optical interferometers is not limited to the number. (N ≧ 2) may be provided. In addition, when N = 1, that is, when an asymmetric Mach-Zehnder interferometer is provided in one stage, when an athermal groove is formed in one of the arm waveguide pairs, a resin (from a predetermined region to an outer region) Here, as a means for suppressing the outflow of the athermal resin), a concave portion or a convex portion can be provided in the vicinity of the athermal groove.

  As described above, what is important in one embodiment of the present invention is to prevent the resin from flowing out from the region where the resin is supplied or flowing out to an undesired region on the optical circuit. is there. Therefore, the configuration of the optical circuit is not essential and may be any. In the above description, the concave portion such as the filter insertion groove and the athermal groove has been described as the region where the resin is supplied. However, the present invention is not limited to this.

  For example, when a resin is used as a protective film for another member such as a semiconductor laser (LD) or an electrode, the resin as the protective film may be dropped so as to cover the target member from above. The dropped resin covers the member as a protective film, but may spread from the member to the surrounding area. Therefore, the member on which the protective film is formed becomes a region where the resin is supplied. Such a protective film is not limited to a member such as an LD or an electrode, but may be a photofunctional polymer or the like.

  When a resin such as an adhesive is formed on the optical circuit and a member is disposed on the resin to bond the member, the region where the resin is supplied is a region where the resin is formed.

  The resin supplied to the region to which the resin is supplied according to an embodiment of the present invention is an adhesive, an athermal resin, a resin containing a light shielding agent used for reducing crosstalk of VOA and AWG, and the like. Functional polymers and the like are included. Examples of the optical functional polymer include those that function as a gas sensor and an optical sensor, and those that have an electro-optic effect and realize a modulation function.

(A) is a top view of a conventional athermal AWG, (b) is a diagram showing an enlarged portion X in (a), and (c) is a cross-sectional view taken along line AA ′ in (b). FIG. (A) And (b) is a figure which shows the structure which reduces the outflow of resin based on one Embodiment of this invention. It is a top view of PLC which has a dielectric multilayer filter based on one Embodiment of this invention. (A) is a cross-sectional view taken along the line BB ′ in FIG. 3, and (b) to (d) are obtained when a groove or a combination of a floor and a groove is used instead of the floor in FIG. 3. It is a BB 'line cutting sectional view. (A) And (b) is a figure which shows the structure which reduces the outflow of resin based on one Embodiment of this invention. It is a top view of PLC which has a dielectric multilayer filter based on one Embodiment of this invention. (A) is a figure which shows the structure which reduces the outflow of resin by arrange | positioning a shallow groove | channel periodically based on one Embodiment of this invention, (b) is CC 'of (a). It is line sectional drawing, (c) is CC 'line | wire sectional sectional drawing at the time of making the shape of the periodic structure of the shallow groove | channel of (a) into v shape. (A) is a figure which shows the structure which provided the hollow in the edge of the periodic structure of a shallow groove | channel based on one Embodiment of this invention, (b) is a top view of PLC which applied the structure of (a). (C) is a cross-sectional view taken along line DD ′ of (b). (A) is a figure which shows the structure which provided the hollow in the edge of the periodic structure of a shallow groove | channel based on one Embodiment of this invention, (b) is a top view of PLC which applied the structure of (a). (C) is a cross-sectional view taken along line EE ′ of (b), and (d) is a diagram showing an example of the arrangement of the depression and the platform. It is a block diagram of PLC suitable for the passive alignment mounting which concerns on one Embodiment of this invention. It is a block diagram of PLC suitable for the passive alignment mounting which concerns on one Embodiment of this invention. It is a figure which shows a mode that passive alignment mounting of PLC based on one Embodiment of this invention is carried out to the optical bench. (A) is a top view of the athermal AWG which concerns on one Embodiment of this invention, (b) is FF 'line | wire sectional drawing of (a), (c) is (a). It is a FF 'line cutting sectional view at the time of using a platform instead of a groove. (A) is a figure which shows the mode of the connection of the resin spread suppression groove | channel and the hollow which functions as a dam based on one Embodiment of this invention, (b) is the GG 'line cutting | disconnection of (a). It is sectional drawing, (c) is a figure which shows a mode that a separate hollow is connected to each groove | channel of the resin spreading | diffusion suppression groove | channel which concerns on one Embodiment of this invention. (A) is a figure which shows the mode of the connection of the resin spread suppression groove | channel and the hollow which functions as a dam based on one Embodiment of this invention, (b) is the HH 'line cutting | disconnection of (a). It is sectional drawing, (c) is a figure which shows a mode that a separate hollow is connected to each groove | channel of the resin spreading | diffusion suppression groove | channel which concerns on one Embodiment of this invention. (A) is a figure which shows the mode of the connection of the resin spreading | diffusion suppression groove | channel based on one Embodiment of this invention, and the hollow which functions as a dam, (b) is resin which concerns on one Embodiment of this invention. It is a figure which shows a mode that a separate hollow is connected to each groove | channel of an expansion suppression groove | channel. (A)-(d) is a figure which shows the method of producing the optical circuit structure which has a groove structure of a filter insertion groove | channel and a shallow period based on one Embodiment of this invention. It is a figure which shows the lattice type | mold optical circuit which provided three steps of asymmetrical Mach-Zehnder type interferometers based on one Embodiment of this invention. It is a top view of the athermal AWG which concerns on one Embodiment of this invention. It is a top view of the athermal AWG which concerns on one Embodiment of this invention.

Explanation of symbols

21, 23, 71, 103 Filter insertion groove 22, 136, 142, 151, 162 Groove 24, 33, 76, 105a, 105b, 111, 141 Platform 25, 35, 73, 74, 137, 143, 153, 164 31, 100 PLC
32, 104 Dielectric multilayer filter 34, 75, 106, 112 Notch structure 72 Shallow groove periodic structure 77 U-shaped platform 78 Projection 101, 133 Clad 102, 132 Waveguide core 120 Optical bench 121 Housing groove 122 Alignment groove 131 Array waveguide 134, 161 Athermal groove 135, 165 Silicone 138 Wave plate insertion groove 139 Wave plate 140 Adhesive 144, 154 Resin 152, 163 Slope

Claims (6)

A waveguide having a cladding and a core;
A resin filling groove provided in the cladding for filling the resin ;
The restraining means disposed at a predetermined distance from the resin filling groove, and when the resin is supplied to the resin filling groove, the resin from the region between the resin filling groove and the restraining means. There example Bei and suppression means for suppressing flowing out,
The restraining means includes a first restraining means that is a recess or a protrusion disposed in parallel with the resin filling groove, and a recess provided toward the resin filling groove from the vicinity of the end of the first restraining means. A second restraining means,
The optical circuit structure according to claim 1, wherein when the first suppressing means is the recess, the recess is formed in the clad so as not to reach the core . The optical circuit structure according to claim 1 , wherein the first suppression unit is at least one concave portion . At least one or more, optical circuit structure according to claim 2, characterized in that it is connected to the second suppression means of the previous SL least one recess. It said first suppression means is an optical circuit structure according to claim 1, characterized in that one or more protrusions even without low. The resin, optical circuit structure according to any one of claims 1 to 4, characterized in that the athermal resin. An optical circuit structure according to any one of claims 1 to 5 ,
With an optical bench,
The optical circuit structure has a plurality of notch structures,
The optical bench has a plurality of recesses that respectively fit into the plurality of notch structures,
An optical module, wherein the optical circuit structure is passively mounted on the optical bench by fitting the plurality of notch structures and the plurality of recesses.

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