JP2005099522A - Optical waveguide device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide device capable of reducing excessive loss while avoiding an increase in manufacturing cost. <P>SOLUTION: The optical waveguide device is provided with a core 1 which is made of a light-transmissive material varying in refractive index with temperature and has an input end where an optical signal is inputted and an output end 12 where the optical signal inputted from the input end and propagated inside is outputted, and a clad 2 which is made of a light-transmissive material having a smaller refractive index than the core 1 and surrounds the core 1 while exposing the input end and output end 12. A heater part 31 which generates a thermal gradient crossing the optical axis of the core 1 in the core 1 is provided nearby the output end 12 of the clad 2. The optical signal is bent by a refractive index gradient generated by thermooptic effect of the heat of the heater part 31, so the optical axis is easily aligned by adjusting the output of the heater part 31 after the device is optically and mechanically coupled with another optical element, thereby reducing the excessive loss. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical waveguide device used when a plurality of optical elements are optically connected to each other.

  2. Description of the Related Art Conventionally, there has been provided an apparatus using an optical signal that includes an optical element such as a light emitting element, a light receiving element, an optical fiber, or an optical waveguide.

  In this type of apparatus, when optical elements are connected to each other, if there is a shift in the optical axes of each other, so-called excess loss occurs in the optical signal transmitted between the optical elements.

Conventionally, excessive loss has been reduced by using a highly accurate assembly device or by a skilled engineer working to improve the accuracy of mutual alignment of optical elements. In addition, as a method for improving the alignment accuracy regardless of a highly accurate assembly apparatus or skilled technique, it has been proposed to provide a positioning structure such as a pedestal or a groove (for example, Patent Document 1). And Patent Document 2).
JP-A-8-36118 (page 3, FIG. 1) Japanese Patent Laid-Open No. 6-3545 (page 5-6, FIG. 2)

  However, in order to improve the alignment accuracy, a highly accurate assembly device and a skilled engineer are required, or a process for providing a structure for positioning is required, which increases the manufacturing cost. It was.

  The present invention has been made in view of the above reasons, and an object thereof is to provide an optical waveguide device capable of reducing excess loss while avoiding an increase in manufacturing cost.

  The invention of claim 1 includes a core made of a light-transmitting material and having an input end to which an optical signal is input, an output end to which an optical signal input from the input end and transmitted through the inside is output, and refracted more than the core. A thermal gradient in a direction crossing the optical axis of the core, which is made of a light-transmitting material with a low rate and which is provided in the vicinity of at least one of the input end and the output end, and the clad surrounding the core by exposing the input end and the output end A heater for aligning the core and an output adjusting means for adjusting the output of the aligning heater, and at least the vicinity of the aligning heater of the core is made of a material whose refractive index changes with temperature. It is characterized by.

  According to the above configuration, since the optical signal is bent by the refractive index gradient generated inside the core due to the thermo-optic effect according to the output of the alignment heater, the output of the alignment heater is fixed after fixing to another optical element. By adjusting the position, the position and orientation of the optical axis can be finely adjusted, so that the alignment of the optical axis is facilitated. Accordingly, it is possible to reduce excess loss while avoiding an increase in manufacturing cost by eliminating the need for a highly accurate assembly apparatus and skilled techniques.

  The invention of claim 2 is characterized in that, in the invention of claim 1, a plurality of aligning heaters are provided, and the output adjusting means adjusts the output of each heater individually.

  According to the above configuration, since the degree of freedom and the degree of alignment of the optical axis are improved, the optical axis is easily aligned.

  According to a third aspect of the present invention, in the first aspect of the invention, there is provided an alignment heater having a shape surrounding the entire circumference of the core in a plane intersecting the optical axis of the core, and at least the alignment heater of the core. The neighborhood is made of a material whose refractive index has a negative correlation with temperature.

  According to the above configuration, since the refractive index distribution of a convex lens shape is generated inside the core and the optical signal is converged by the thermo-optic effect due to the heating by the alignment heater, the optical axis alignment is facilitated.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, a diameter-enlarged portion having a cross-sectional area in a cross-section perpendicular to the optical axis of the core is made larger than that of other portions, and the alignment heater It is characterized by being arranged in the middle part in the optical axis direction.

  According to the above configuration, since the degree of freedom of the input position or output position of the optical signal is improved as compared with the case where the diameter-expanded portion is not provided, the optical axis alignment is further facilitated. In addition, since a refractive index distribution in the form of a convex lens is generated on both sides of the alignment heater in the optical axis direction of the core, the alignment heater is provided at the end in the optical axis direction of the enlarged diameter portion. In comparison, since the optical signal can be converged smaller, the optical axis alignment becomes easier.

  The invention of claim 5 is characterized in that, in the invention of claim 1, the alignment heater is formed in a shape that approaches the optical axis of the core from the input side toward the output side along the optical axis of the core.

  According to the above configuration, the region of the core that has been heated by the aligning heater, that is, the region in which the refractive index has greatly changed, has a shape that approaches the optical axis of the core from the input side to the output side along the optical axis of the core. Therefore, the optical axis alignment is further facilitated as compared with the case where the alignment heater is formed in parallel to the optical axis of the core.

  According to a sixth aspect of the present invention, in the first aspect of the present invention, an enlarged-diameter portion having a cross-sectional area in a cross section perpendicular to the optical axis of the core larger than that of the other portion is provided in the vicinity of the core alignment heater. It is characterized by that.

  According to the above configuration, since the degree of freedom of the optical axis alignment is improved as compared with the case where the enlarged diameter portion is not provided, the optical axis alignment is further facilitated.

  The invention according to claim 7 is the invention according to claim 1, wherein the core has a plurality of output ends, and has a plurality of branch heaters provided corresponding to each one of the output ends. And an optical switch unit that outputs an optical signal input from the input end to the output end corresponding to the branching heater by a thermo-optic effect when one of the heaters is energized. It is provided in the vicinity of the output end, and the branching heater and the alignment heater in the vicinity of the output end corresponding to the branching heater are electrically connected.

  According to the above configuration, the branching heater and the alignment heater near the output end corresponding to the branching heater can be operated simultaneously.

  According to the present invention, since the alignment heater that generates the thermal gradient in the direction crossing the optical axis of the core is provided inside the core, the refractive index generated inside the core by the thermo-optic effect according to the output of the alignment heater. The optical signal can be bent by the gradient, and the position and orientation of the optical axis can be finely adjusted by adjusting the output of the alignment heater after optically and mechanically coupling to other optical elements. Therefore, the alignment of the optical axis becomes easy. Accordingly, it is possible to reduce excess loss while avoiding an increase in manufacturing cost by eliminating the need for a highly accurate assembly apparatus and skilled techniques.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
In the present embodiment, as shown in FIG. 1, an input terminal (not shown) made of a translucent material whose refractive index changes with temperature and an optical signal input from the input terminal are output. A core 1 having an output end 12 and a cladding 2 made of a translucent material having a higher refractive index than that of the core 1 and exposing the input end and the output end 12 of the core 1 and surrounding the entire circumference of the core 1. An optical element coupled to the input terminal and an optical element coupled to the output terminal 12 are provided by optically and mechanically coupling the input terminal and the output terminal 12 of the core 1 to different optical elements. The element is optically coupled. The clad 2 is provided with a conductive pattern 3 having a heater portion 31 that generates heat when energized, and a heat gradient in the direction intersecting the optical axis of the core 1 is generated inside the core 1 by the heat of the heater portion 31. It is like that. The refractive index gradient accompanying this thermal gradient makes it possible to align the optical axis even after coupling with other optical elements. That is, the heater unit 31 is a centering heater. Hereinafter, the upper and lower sides will be described with reference to FIG.

  More specifically, the clad 2 is formed in a rectangular parallelepiped shape on a substrate 4 made of a material having a higher thermal conductivity than the clad 2, and the conductive pattern 3 is located near the input end and the output on the upper surface of the clad 2. It is provided in the vicinity of the end 12.

  The core 1 is formed in a square shape in cross section perpendicular to the optical axis. As an example of specific dimensions, when the optical signal transmitted by the core 1 is a single mode and the refractive index difference between the core 1 and the clad 2 is 0.3%, The length is desirably 5 to 10 μm.

  As shown in FIG. 2, the conductive pattern 3 includes two heater portions 31 formed in a linear shape sandwiching the projection of the core 1 onto the upper surface of the cladding 2, and the rear end portions of the heater portions 31 (see FIG. 2). A right end portion) and two terminal portions 32 that extend from the front end portion of each heater portion 31 and are connected to a variable voltage power source (not shown). The heater portion 31 is formed to be narrower than other portions of the conductive pattern 3 and generates heat when energized between the terminal portions 32. The output of the heater unit 31 can be adjusted by adjusting the voltage of the variable voltage power supply. That is, the variable voltage power source is the output adjustment means. As a material of the conductive pattern 3, for example, titanium, gold, aluminum, nickel, chromium, nickel-chromium alloy, or the like can be used. When gold is used as the material of the conductive pattern 3, if the width of the heater portion 31 is 10 μm and the thickness is 0.2 μm, it can be used with an output of several tens of mW.

  If electricity is applied between the terminal portions 32 of the conductive pattern 3, the heater portion 31 generates heat, and a refractive index gradient in the vertical direction is generated inside the core 1, so that the correlation of the refractive index of the core 1 with the temperature is positive. If it is negative, the optical signal is bent downward. By adjusting the energization amount to the heater unit 31, the optical axis in the vertical direction can be aligned.

  On the upper surface of the clad 2, an attenuation conductive pattern 5 having a linear attenuation heater portion 51 along the core 1 and terminal portions 52 provided at both ends of the attenuation heater portion 51 is provided. By energizing between the terminal portions 52, the optical signal can be attenuated using the thermo-optic effect. That is, the optical waveguide device of this embodiment has a function as a variable optical attenuator.

  As a method for manufacturing the above optical waveguide device, for example, a layer of a translucent material that is a portion below the core 1 of the clad 2 is formed on the substrate 4 by a sol-gel method or spin coating. Next, a layer to be the core 1 is provided on this layer, and reactive ion etching using a photolithography technique is performed to remove unnecessary portions, or a reactivity using a photolithography technique is applied to a portion where the core 1 is to be provided. The core 1 is formed by forming a groove using ion etching, mold transfer, or the like, filling the inside of the groove with a thermoplastic resin, and then solidifying the groove. Next, a layer that is a portion above the core 1 of the clad 2 is formed by a sol-gel method or a spin coating method. Next, the conductive pattern 3 and the attenuation conductive pattern 5 are formed on the upper surface of the clad 2 by, for example, vapor deposition of a metal thin film. Note that the sol-gel method, spin coating, photolithography technique, reactive ion etching, and mold transfer are well-known techniques and will not be described.

Here, the material used for the core 1 is specifically an inorganic material such as quartz, sapphire, LiTaO ₃ , or LiNbO ₃ , or a polymer material such as acrylic, epoxy, silicone, or polyimide. be able to. When a material having a refractive index having a positive correlation with temperature, such as quartz, is used as the material of the core 1, for example, the heater portion 31 is formed in a spindle shape that is long in a direction intersecting the optical axis of the core 1. As shown in FIG. 3, the convex lens-like refractive index distribution is formed in the core 1 by forming it in a narrow range on the projection of the core 1 on the upper surface of the clad 2, and the optical signal is converged. Can be obtained. On the other hand, since the polymer material has a higher temperature dependence of the refractive index than the inorganic material (the absolute value of the thermo-optic constant is large), when the polymer material is used as the material of the core 1, the inorganic material is Compared with the case where it is used, the output of the heater unit 31 can be small, and the power consumption can be reduced.

  According to the above configuration, by adjusting the output of the heater unit 31 after optically and mechanically coupling the input end or the output end 12 of the core 1 to other optical elements, the input end and the output end 12 can be adjusted. Since the direction of the optical signal and the position at which the optical signal is output at the output end 12 can be finely adjusted, the optical axis can be easily aligned. In addition, since the conductive pattern 3 can be formed simultaneously with the attenuation conductive pattern 5, the number of processes does not increase as compared with the case without the conductive pattern 3, and thus an increase in manufacturing cost is suppressed. Therefore, it is possible to reduce excess loss by aligning the optical axis while avoiding an increase in manufacturing cost by eliminating the need for a highly accurate assembly apparatus, skilled technology, and a new process.

  In addition, as shown in FIG. 4, you may provide the enlarged diameter part 13 which made the cross-sectional shape larger than the other site | part in the vicinity of the output end 12 of the core 1, or an input end. 4 is formed in a shape that overlaps the other part of the core 1 and the clad 2 when viewed from the optical axis direction of the core 1, and the clad 2 is provided around the enlarged diameter part 13. Not. As the material of the enlarged diameter portion 13, a material different from other portions of the core 1 may be used as long as the refractive index is higher than that of the clad 2 and the refractive index depends on temperature. In order to prevent a loss due to reflection or the like with other parts of the core 1, it is desirable to form the enlarged diameter portion 13 with the same material as the other parts of the core 1. According to this configuration, since the areas of the output end 12 and the input end are increased, an optical signal can be input / output in a wider range than the cross section of the other part of the core 1, so that the optical axis is aligned. It becomes easier.

(Embodiment 2)
Since the basic configuration of the present embodiment is the same as that of the first embodiment, common portions are denoted by the same reference numerals, description thereof is omitted, and only different portions are described.

  In the present embodiment, as shown in FIG. 5, a terminal portion 32 is provided for each heater portion 31, and the heater portions 31 are connected in parallel to each other as shown in FIG. VR is connected in series. By adjusting the voltage of the variable voltage power source VE, the output of each heater unit 31 can be adjusted simultaneously, and by individually adjusting the resistance value of each variable resistor VR, the energization amount to each heater unit 31, that is, The output can be adjusted individually. That is, in this embodiment, the variable voltage power source VE and the variable resistor VR are output adjusting means.

  According to the above configuration, for example, by making the output of one heater unit 31 higher than the output of the other heater unit 31, the thermal gradient and refractive index gradient in the left-right direction (upper left-lower direction in FIG. Since the direction in which the optical signal is generated and bent and the output position of the optical signal at the output end 12 can be adjusted in the horizontal direction, alignment of the optical axis is further prepared compared to the first embodiment.

  As shown in FIG. 7, if the heater portion 31 is formed in a shape that approaches the core 1 from the input end 11 toward the output end 12 along the optical axis of the core 1, the heater portion 31 in the core 1 is heated to a high temperature. In other words, the region where the refractive index has changed is formed in a shape that approaches the optical axis of the core 1 from the input end 11 toward the output end 12 along the optical axis of the core 1. The alignment of the optical axis is further facilitated as compared with the case where the optical axis is formed parallel to the axis. Here, in FIG. 7, the attenuation conductive pattern 5 is not shown.

  Further, as shown in FIG. 8, the conductive pattern 3 similar to the upper surface of the clad 2 may be provided on the lower surface of the clad 2 by evaporating a metal thin film on the substrate 4 before forming the clad 2. If this configuration is adopted, the optical signal can be bent in both the upper and lower directions, so that the alignment of the optical axis is further facilitated.

  Furthermore, as shown in FIGS. 9 and 10, if the heater portions 31 are provided on the left and right sides of the core 1, it becomes easy to bend the optical signal in the left-right direction, so that it becomes easy to correct the deviation of the optical axis in the left-right direction. 9 and 10, the left heater unit 31 is not illustrated, but the heater unit 31 is provided symmetrically on the left and right. In order to form the conductive patterns 3 positioned on the left and right sides of the clad 2, for example, a metal thin film is formed on the entire surface near the portion where the conductive pattern 3 of the clad 2 is provided, and then unnecessary portions are removed with a laser.

  In the example shown in FIGS. 9 and 10, by reducing the thickness T of the left and right claddings 2 of the core 1 in the vicinity of the heater portion 31, from the heat generation of the heater portion 31 to the generation of the refractive index gradient inside the core 1. The time is shortened and the responsiveness is improved. Here, in order to prevent leakage of the optical signal from the core 1, the cladding 2 has a certain thickness according to the refractive index difference between the core 1 and the cladding 2 and the wavelength and mode of the optical signal transmitted through the core 1. It is necessary to ensure the thickness. For example, when the optical signal is a single mode, the wavelength is 1.55 μm, and the refractive index difference between the clad 2 and the core 1 is 0.3%, the thickness T of the clad 2 should be 5 to 10 μm. Is desirable.

(Embodiment 3)
Since the basic configuration of the present embodiment is the same as that of the first embodiment, common portions are denoted by the same reference numerals, description thereof is omitted, and only different portions are described.

  As shown in FIG. 11, the heater portion 61 of the conductive pattern 6 for alignment of the present embodiment is provided on the end surface of the clad 2 where the output end 12 of the core 1 is exposed, and on the output end 12 of the core 1. It is formed in an annular shape having a center and surrounding the entire circumference of the output end 12. Further, the terminal portion 62 of the conductive pattern 6 extends on the upper surface of the clad 1. Furthermore, the core 1 is formed of a material having a negative correlation between the refractive index and the temperature, such as the polymer material described in the first embodiment.

  According to the above configuration, a convex lens-shaped refractive index distribution is generated inside the core 1 when the heater unit 31 is energized, so that the optical signal is converged and the area of the range in which the optical signal is output at the output end 12 of the core 1 is increased. By narrowing, it becomes easy to align the range in which the optical signal is output within the range of the input end F1 of another optical element such as the optical fiber F. In addition, since the refractive index distribution is axisymmetric, a stable effect independent of the polarization direction of the optical signal can be obtained.

  In addition, when the optical waveguide device of the present embodiment is coupled to, for example, the optical fiber F, a material having a negative correlation between the refractive index and the temperature is used at the end of the adhesive B or the optical fiber F used. Since the refractive index distribution in the form of a convex lens also occurs at the ends of the adhesive B and the optical fiber F, the optical signal can be converged more finely by the output of the same heater unit 61, and the alignment of the optical axis can be made easier. . Alternatively, the power consumption can be reduced by reducing the output of the heater unit 61 while obtaining the same effect.

(Embodiment 4)
Since the basic configuration of the present embodiment is the same as that of the first embodiment, common portions are denoted by the same reference numerals, description thereof is omitted, and only different portions are described.

  In the present embodiment, as shown in FIG. 12, a diameter-enlarged portion 14 having a cross-sectional area in a cross-section perpendicular to the optical axis of the core 1 larger than that of other portions is provided in the vicinity of the output end 12 of the core. 61 is provided over the entire circumference of the intermediate portion of the enlarged diameter portion 14 in the optical axis direction. The cross-sectional shape of the enlarged diameter portion 14 in a cross section orthogonal to the optical axis of the core 1 is formed in a square shape centering on one optical axis of the core. The terminal portion 62 of the conductive pattern 6 is formed on the upper surface of the substrate 4 exposed on the left and right sides of the enlarged diameter portion 14. Here, at least the diameter-expanded portion 14 of the core 1 is formed of a material whose refractive index has a negative correlation with temperature.

  According to the above configuration, the refractive index distribution in the form of a convex lens is generated inside the core 1 on both sides of the heater unit 61 in the direction along the optical axis of the core 1, the optical signal is converged inside the core 1, and the output end 12. As a result, the range in which the optical signal is output becomes narrow, so that the alignment of the optical axis becomes easy.

(Embodiment 5)
Since the basic configuration of the present embodiment is the same as that of the first embodiment, common portions are denoted by the same reference numerals, description thereof is omitted, and only different portions are described.

  As shown in FIG. 13, the core 1 of the present embodiment is made of a material whose refractive index has a negative correlation with temperature, and is branched into a Y-shape in the vertical direction of FIG. 13 so as to have two output ends 12a and 12b. And an optical switch unit that outputs an optical signal input from the input end 11 of the core 1 to one of the output ends 12a and 12b. The optical switch unit includes branching conductive patterns 7a and 7b for outputting an optical signal to one output terminal by a thermo-optic effect. The branching conductive patterns 7a and 7b are respectively provided on both sides of the projection of the position where the core 1 branches on the upper surface of the clad 2, and linear branching heater parts 71a and 71b and a branching heater part along the core 1 are provided. Terminal portions 72a and 72b provided at both ends of 71a and 71b, respectively. When energized between one of the terminal portions 72a and 72b of the branch conductive patterns 7a and 7b, an optical signal input from the input end 11 is output to one of the output ends 12a and 12b by the thermo-optic effect. It has become. For example, when the lower branch heater 71a in FIG. 13 is energized, the optical signal input from the input end 11 is output from the upper output end 12a in FIG. The heater portions 31a and 31b of the conductive patterns 3a and 3b for alignment are provided in the vicinity of the output ends 12a and 12b of the core 1, respectively.

  As shown in FIG. 14, two heater portions 31a and 31b corresponding to one output end 12a and 12b are connected in parallel to each other, and branch heater portions 71a and 71b corresponding to the same output ends 12a and 12b are connected to each other. The heater portions 31a and 31b are connected in series with each other. The variable voltage power source VE is connected to a common terminal of a changeover switch SW for selecting one of the branch heater portions 71a and 71b.

  According to the above configuration, the optical axis can be easily aligned by adjusting the output of the variable voltage power supply VE after optically and mechanically coupling the output ends 12a and 12b to other optical elements. . Further, since the conductive patterns 3a and 3b can be formed simultaneously with the branch conductive patterns 7a and 7b, and it is not necessary to add a new process, an increase in manufacturing cost can be suppressed. In other words, excessive loss can be reduced by aligning the optical axis while avoiding an increase in manufacturing cost by eliminating the need for a highly accurate assembly device, advanced technology, and new processes.

  Further, since the branch heater portions 71a and 71b corresponding to the same output ends 12a and 12b and the heater portions 31a and 31b are electrically connected, the branch heater portions corresponding to the same output ends 12a and 12b. 71a and 71b and heater part 31a and 31b can be operated simultaneously.

  As shown in FIG. 15, a conductive pattern 3c for alignment is added to the input end 11 side, and as shown in FIG. 16, a heater portion 31c, a variable voltage power supply VR, and a changeover switch SW on the input end 11 side are provided. The heaters 31c on the input end 11 side may be operated when they are connected in series with each other and one contact of the changeover switch SW is closed. According to this configuration, the heater unit 31c on the input end 11 side can be operated at the same time regardless of which output terminal 12a, 12b outputs the optical signal.

  In the first to fourth embodiments, the conductive pattern 3 can be easily formed in the same process when forming the attenuation conductive pattern 5 or the branching conductive patterns 7a and 7b, and the effect of the present invention is great. Applicable not only to optical waveguide devices that originally have a heater unit, such as the variable optical attenuators and optical switches described in Embodiments 1 to 4, but also to optical waveguide devices that do not normally have a heater unit, such as optical multiplexers / demultiplexers. Is possible.

It is a perspective view which shows Embodiment 1 of this invention. It is a top view which shows the principal part same as the above. It is a top view which shows the principal part of another form same as the above. It is a perspective view which shows another form same as the above. It is a perspective view which shows Embodiment 2 of this invention. It is a circuit diagram which shows the same as the above. It is a top view which shows another form same as the above. It is a perspective view which shows another form same as the above. It is a perspective view which shows another form same as the above. It is a right view which shows the same as the above. It is a perspective view which shows Embodiment 3 of this invention. It is a perspective view which shows Embodiment 4 of this invention. It is a top view which shows Embodiment 5 of this invention. It is a circuit diagram which shows the same as the above. It is a top view which shows another form same as the above. It is a circuit diagram which shows the same as the above.

Explanation of symbols

1 Core 2 Cladding 11 Input end 12 Output end 31 Heater VE Variable voltage power supply VR Variable resistance

Claims (7)

  A core made of a translucent material, having an input end for inputting an optical signal, an output end for outputting an optical signal input from the input end and transmitted through the inside, and a translucent material having a refractive index smaller than that of the core And a cladding that surrounds the core with the input and output ends exposed and a thermal gradient in the direction that intersects the optical axis of the core and that is provided near at least one of the input and output ends. An optical waveguide device comprising: a core heater; and an output adjusting means for adjusting an output of the alignment heater, wherein at least the vicinity of the alignment heater of the core is formed of a material whose refractive index changes with temperature. .   2. An optical waveguide device according to claim 1, wherein a plurality of alignment heaters are provided, and the output adjusting means individually adjusts the output of each heater.   An alignment heater having a shape that surrounds the entire circumference of the core in a plane that intersects the optical axis of the core is provided, and the refractive index has a negative correlation with temperature at least in the vicinity of the alignment heater of the core. 2. The optical waveguide device according to claim 1, wherein the optical waveguide device is made of a material.   A diameter-enlarged portion having a cross-sectional area in a cross-section perpendicular to the optical axis of the core larger than that of other portions is provided, and a centering heater is disposed at an intermediate portion in the optical axis direction of the enlarged-diameter portion. The optical waveguide device according to claim 3.   2. The optical waveguide device according to claim 1, wherein the alignment heater is formed in a shape that approaches the optical axis of the core from the input side toward the output side along the optical axis of the core.   2. The optical waveguide device according to claim 1, wherein a diameter-expanded portion having a cross-sectional area in a cross section perpendicular to the optical axis of the core larger than other portions is provided in the vicinity of the core alignment heater.   The core has a plurality of output ends, and has a plurality of branch heaters provided corresponding to each one of the output ends. When the core is energized, the thermo-optics And an optical switch unit that outputs an optical signal input from the input terminal to the output terminal corresponding to the branch heater, and the alignment heater is provided in the vicinity of the output terminal of the core. 2. The optical waveguide device according to claim 1, wherein an alignment heater near the output end corresponding to the branching heater is electrically connected.

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