Isolator and manufacturing method

Abstract

This isolator has a waveguide, a substrate, a first magnetic body part, a second magnetic body part, and a first sealing material. The waveguide propagates electromagnetic waves in an extension direction. The waveguide is mounted on the substrate. The first magnetic body is positioned in a first direction with respect to a first portion that is a part of the waveguide. The first magnetic body part has at least one magnetic body. The second magnetic body part is positioned in a direction opposite to the first direction with respect to the first portion. The second magnetic body part has at least one magnetic body. The first sealing material is positioned so as to cover the first magnetic body part, the second magnetic body part, and at least a part of the main surface of the substrate. The first magnetic body part and the second magnetic body part are fixed by at least one of adhesion by an adhesion part and engagement of the first magnetic body part and the second magnetic body part with a recess formed on the main surface of the substrate.

Description

Isolator and manufacturing method

[0001] The present invention relates to an isolator and a manufacturing method.

[0002] An interference-type optical isolator generates a phase change by applying a magnetic field to a magneto-optical material (see Patent Document 1).

[0003] International Publication No. 2007 / 083419

[0004] In an interference-type optical isolator, the magnetic field application means must be installed with high precision to generate a uniform magnetic field around the magneto-optical material, but it is difficult to install a minute magnetic field application means with high precision.

[0005] Therefore, an object of the present disclosure, which has been made in consideration of the above-mentioned problems of the conventional technology, is to provide an isolator in which a magnetic field application means is installed with high precision.

[0006] In order to solve the above-mentioned problems, an isolator according to a first aspect comprises: a waveguide that propagates electromagnetic waves along an extension direction; a substrate on which the waveguide is mounted; a first magnetic material portion located in a first direction parallel to a main surface of the substrate relative to a first portion that is a part of the waveguide and including at least one magnetic material; a second magnetic material portion located in a direction opposite to the first direction relative to the first portion and including at least one magnetic material; and a first sealing material located so as to cover at least a portion of the main surface of the substrate, the first magnetic material portion, and the second magnetic material portion, wherein the first magnetic material portion and the second magnetic material portion are fixed by at least one of engaging with a recess formed in the main surface of the substrate and adhering with an adhesive portion.

[0007] A method for manufacturing an isolator according to a second aspect includes forming a waveguide on a substrate, fixing a first magnetic material portion to a first portion that is a part of the waveguide in a first direction parallel to a main surface of the substrate and fixing a second magnetic material portion in a direction opposite to the first direction, covering the part of the substrate, the first magnetic material portion, and the second magnetic material portion with a first sealing material, and magnetizing the first magnetic material portion and the second magnetic material portion.

[0008] 6 is a top view of the isolator of the first embodiment as seen from the normal direction of the first surface. FIG. 7 is a cross-sectional view showing a cross section of the isolator of FIG. 1 taken along line II-II. FIG. 8 is a cross-sectional view showing a cross section of the isolator of FIG. 1 taken along line III-III. FIG. 9 is a cross-sectional view of a modified example of the isolator of FIG. 2. FIG. 10 is a cross-sectional view of a further modified example of the isolator of FIG. 4. FIG. 11 is a configuration diagram of the phase shift section of FIG. 1 taken from the normal direction of the first surface. FIG. 12 is a cross-sectional view of a portion of the first branch path overlapping the first non-reciprocal member 24 of FIG. 6 taken perpendicular to the extension direction. FIG. 13 is a cross-sectional view of an isolator of a second embodiment.

[0009] Hereinafter, an embodiment of an isolator to which the present disclosure is applied will be described with reference to the drawings.

[0010] 1 and 2 , an isolator 10 according to a first embodiment of the present disclosure includes a waveguide 11, a substrate 12, a first magnetic material portion 13, a second magnetic material portion 14, and a first sealing material 15. The isolator 10 may further include a radiation source 16, a second sealing material 17, a heat dissipation member 18, and an electrode pad 19.

[0011] As shown in Fig. 2, the waveguide 11 extends along the major surface of the substrate 12. The major surface is the surface with the largest area. The waveguide 11 propagates electromagnetic waves along the extension direction. As shown in Fig. 1, at least one end of the waveguide 11 may be coupled to a radiation source 16. The waveguide 11 may be formed of, for example, silicon.

[0012] 1, a first portion 22, which is a part of the waveguide 11, may be sandwiched between a first magnetic material portion 13 and a second magnetic material portion 14, which will be described later. The first portion may constitute a phase shift portion 23, which will be described later.

[0013] 2, the substrate 12 may be flat. The substrate 12 may be made of a conductor such as metal, a semiconductor such as silicon, glass, or resin. The waveguide 11 is mounted on the substrate 12. The waveguide 11 may be mounted on a first surface s1, which is one of the main surfaces of the substrate 12.

[0014] As shown in FIG. 3 , a recess rs may be formed in the first surface s1 of the substrate 12. In FIG. 3 , the first portion 22 is depicted as a single waveguide 11 for convenience. However, as described below, the first portion 22 may be configured such that multiple waveguide 11 portions are arranged side by side along the first direction, and a nonreciprocal member may be located adjacent to some of the waveguide 11 portions. As described below, the recess rs may be formed at a position where the first magnetic material portion 13 and the second magnetic material portion 14 are to be provided. The recess rs may have a shape that allows a portion of the first magnetic material portion 13 to be embedded therein, as viewed from the normal direction of the main surface of the substrate 12. The depth of the recess rs may be calculated by subtracting the height of the waveguide 11 in the normal direction from the height of the first magnetic material portion 13 in the normal direction to the first surface s1, and dividing the result by 2.

[0015] 2, a groove gr may be formed in the first surface s1 of the substrate 12 between the first portion 22 and a radiation source 16, which will be described later. The groove gr may be deeper than the recess rs.

[0016] As shown in Fig. 3, the first magnetic material part 13 is located in a first direction relative to the first portion 22. The first direction is a direction parallel to the main surface of the substrate 12. The first magnetic material part 13 includes at least one magnetic body. The magnetic body may be magnetized. The first magnetic material part 13 may be entirely or partially made of a magnetic body.

[0017] The first magnetic material portion 13 is fixed by at least one of engaging with the recess rs of the substrate 12 and being adhered by the adhesive portion 20. Specifically, the first magnetic material portion 13 may be fixed by both engaging with the recess rs and being adhered by the adhesive portion 20. The adhesive portion 20 may be formed by solidifying an adhesive. Any material that bonds the first magnetic material portion 13 to the recess rs may be used as the adhesive. For example, a material with a viscosity of 10 Pa·s or less may be preferably used as the adhesive. For example, the adhesive may be an inorganic adhesive such as solder or silica, or an organic adhesive such as a synthetic adhesive. The adhesive is preferably thermosetting.

[0018] The center position in the normal direction of the main surface of the magnetic material included in the first magnetic material part 13 may overlap with the first portion 22 when viewed from the first direction. Specifically, by partially embedding the first magnetic material part 13 in the recess rs having the depth as described above, the center position can overlap with the first portion 22.

[0019] The second magnetic material portion 14 is located in a direction opposite to the first direction relative to the first portion 22. The second magnetic material portion 14 includes at least one magnetic body. The magnetic body may be magnetized. The second magnetic material portion 14 may be entirely or partially made of a magnetic body.

[0020] The second magnetic material portion 14 is fixed by at least one of engaging with the recess rs of the substrate 12 and being adhered by the adhesive portion 20. Specifically, the second magnetic material portion 14 may be fixed by both engaging with the recess rs and being adhered by the adhesive portion 20.

[0021] The center position in the normal direction of the main surface of the magnetic material included in the second magnetic material part 14 may overlap with the first part 22 when viewed from the first direction. Specifically, by partially embedding the second magnetic material part 14 in the recess rs having the depth as described above, the center position can overlap with the first part 22.

[0022] 2, the first sealing material 15 is positioned so as to cover at least a portion of the main surface of the substrate 12, the first magnetic material portion 13, and the second magnetic material portion 14. The first sealing material 15 may further be positioned so as to cover at least a portion of the waveguide 11. The first sealing material 15 may be filled in the groove gr.

[0023] The first sealing material 15 may be formed by solidifying a sealing agent. The thermal conductivity of the sealing agent is preferably 0.2 W / m·K from the viewpoint of reducing the heat transfer from heat-generating components such as the radiation source 16 to the waveguide 11 via the first sealing material 15. The sealing agent may be an organic material such as an epoxy resin, a silicone resin, a urethane resin, or a phenol resin.

[0024] The radiation source 16 may be mounted on the substrate 12. The radiation source 16 may be coupled to the waveguide 11 as described above. The radiation source 16 may be located in a direction perpendicular to the first direction and parallel to the first plane s1 with respect to a portion of the waveguide 11 located between the first magnetic material portion 13 and the second magnetic material portion 14. The radiation source 16 may emit an electromagnetic wave to be propagated in the waveguide 11. The radiation source 16 may be, for example, a light source that emits light in the C-band.

[0025] The second encapsulant 17 may be positioned to cover at least a portion of the substrate 12 and the radiation source 16. As shown in Figure 4, the second encapsulant 17 may also be positioned to cover the first encapsulant 15. The second encapsulant 17 may have a higher thermal conductivity than the first encapsulant 15.

[0026] The second sealing material 17 may be formed by solidifying a sealing material. The thermal conductivity of the sealing material is preferably about 0.2 W / m·K from the viewpoint of reducing the heat transfer of heat from heat-generating components such as the radiation source 16 to the waveguide 11 via the first sealing material 15 and the like, and from the viewpoint of the heat transfer properties required for the solidified second sealing material 17. The sealing material may be an organic material such as an epoxy resin, a silicone resin, a urethane resin, or a phenol resin.

[0027] The heat dissipation member 18 may be positioned so as to be in contact with the second sealing material 17. As shown in FIG. 1 , at least a portion of the heat dissipation member 18 may be positioned so as to overlap the radiation source 16 when viewed from the normal direction of the first surface s1. The heat dissipation member 18 may be positioned so as not to overlap with a portion of the waveguide 11 sandwiched between the first magnetic material portion 13 and the second magnetic material portion 14 when viewed from the normal direction of the first surface s1. Alternatively, as shown in FIG. 4 , the heat dissipation member 18 may be positioned so as to overlap with a portion of the waveguide 11 sandwiched between the first magnetic material portion 13 and the second magnetic material portion 14. As shown in FIG. 5 , the heat dissipation member 18 may be positioned on the back side of the first surface s1 of the substrate 12 without being in contact with the second sealing material 17.

[0028] The heat dissipation member 18 is, for example, a heat sink. The heat dissipation member 18 may be made of a metal such as aluminum that has high thermal conductivity. The heat dissipation member 18 may be provided with a plurality of fins for heat dissipation.

[0029] 1, the electrode pad 19 may be located at a position different from the radiation source 16 when viewed from the normal direction of the first surface s1. The electrode pad 19 may apply a voltage to various elements provided on the substrate 12.

[0030] Next, a detailed configuration of the phase shift section 23 in the isolator 10 will be described. As shown in Fig. 6, the phase shift section 23 may include a first portion 22, a first non-reciprocal member 24, and a second non-reciprocal member 25. The first portion 22 may have a branch portion 26, a first branch path 27, and a second branch path 28.

[0031] The first portion 22 may have two ends through which electromagnetic waves enter or exit the first portion 22. A branch portion 26 may be provided at each of the two ends. A first branch path 27 and a second branch path 28 may be provided between the two branch portions 26. The branch portion 26 may include a first branch portion 29 and a second branch portion 30. In the following description, a common configuration that is not distinguished between the first branch portion 29 and the second branch portion 30 will be described as the configuration of the branch portion 26.

[0032] The branching section 26 may branch the electromagnetic waves incident on the first portion 22 so that they are transmitted to the first branch path 27 and the second branch path 28. The branching section 26 may couple the electromagnetic waves incident from the first branch path 27 and the second branch path 28 so that they are radiated from the first portion 22.

[0033] The first branch path 27 and the second branch path 28 may propagate TM mode electromagnetic waves from one branch portion 26 to the other branch portion 26. The extending direction of the first branch path 27 and the second branch path 28 may be changed at at least one location. For example, the extending direction of the first branch path 27 may be changed by 180 degrees at each of two locations, a first location p1 and a second location p2, by folding back. Furthermore, for example, the extending direction of the second branch path 28 may be changed by 180 degrees at two locations, a third location p3 and a fourth location p4, by folding back. The change in the extending direction does not have to be limited to folding back. Furthermore, the angle by which the extending direction is changed is not limited to 180 degrees.

[0034] The phase shift section 23 may be configured to transmit TM mode electromagnetic waves input to the first branch section 29 to the second branch section 30, and to attenuate TM mode electromagnetic waves input to the second branch section 30 in the first branch section 29 so as not to transmit them to the first branch section 29.

[0035] An electromagnetic wave in TM mode is an electromagnetic wave in which the amplitude direction of the electric field coincides with the normal direction to the principal surface when the electromagnetic wave propagates along the principal surface of the substrate 12. Conversely, an electromagnetic wave in TE mode is an electromagnetic wave in which the amplitude direction of the electric field is perpendicular to the propagation direction of the electromagnetic wave and coincides with the direction along the principal surface when the electromagnetic wave propagates along the substrate 12.

[0036] For convenience, the direction in which the electromagnetic wave propagates from the first branch 29 to the second branch 30 is referred to herein as a first propagation direction. For convenience, the direction in which the electromagnetic wave propagates from the second branch 30 to the first branch 29 is referred to herein as a second propagation direction. In other words, the phase shifter 23 may transmit the TM mode electromagnetic wave in the first propagation direction, but may not transmit it in the second propagation direction.

[0037] The phase shifter 23 may achieve asymmetric electromagnetic wave propagation characteristics using the principle of asymmetric Mach-Zehnder interferometer. The phase shifter 23 may be configured such that, among the electromagnetic waves propagating from the first branch 29 in the first propagation direction, the phase of the electromagnetic wave that reaches the second branch 30 through the first branch path 27 coincides with the phase of the electromagnetic wave that reaches the second branch 30 through the second branch path 28. Alternatively, the phase shifter 23 may be configured such that, among the electromagnetic waves propagating from the second branch 30 in the second propagation direction, the phase of the electromagnetic wave that reaches the first branch 29 through the first branch path 27 is shifted by 180 degrees from the phase of the electromagnetic wave that reaches the first branch 29 through the second branch path 28. With this configuration, the phase shifter 23 may operate to pass the electromagnetic wave in the first propagation direction and to block the electromagnetic wave in the second propagation direction.

[0038] The phase shift can be adjusted by adjusting the line length of the waveguide or the effective refractive index of the waveguide. The first portion 22 may be configured such that the phase of the electromagnetic wave propagating through the first branch 27 lags behind the phase of the electromagnetic wave propagating through the second branch 28 by 90 degrees, whether the electromagnetic wave propagates through the first portion 22 in the first propagation direction or the second propagation direction.

[0039] In the phase shift section 23, the first nonreciprocal member 24 and the second nonreciprocal member 25 may be arranged to cause a phase shift between an electromagnetic wave propagating in a first propagation direction through the waveguide and an electromagnetic wave propagating in a second propagation direction to differ from each other. The first branch path 27 including the first nonreciprocal member 24 and the second branch path 28 including the second nonreciprocal member 25 may function as a nonreciprocal waveguide when a magnetic field is applied.

[0040] The nonreciprocal waveguide advances or delays the phase of the propagating electromagnetic wave. In the phase shifter 23 according to this embodiment, the nonreciprocal waveguide may be configured so that the relationship between the phase advance and delay in the waveguide 11 to which magnetic fields are applied from opposite directions toward the propagation direction of the electromagnetic wave is reversed. Specific examples of the arrangement of the first nonreciprocal member 24 and the second nonreciprocal member 25 are described below.

[0041] The first nonreciprocal member 24 may be positioned so as to overlap a portion of the first branch path 27 when viewed from the normal direction to the main surface of the substrate 12. "Overlapping" means that the first nonreciprocal member 24 is positioned in a direction away from the substrate 12 along the normal direction to a portion of the first branch path 27, as shown in FIG. 7 . Specifically, the first nonreciprocal member 24 may be positioned so as to overlap a portion of the first branch path 27 extending along a second direction perpendicular to the first direction in which the first magnetic body 13 and the second magnetic body 14 are aligned. Furthermore, the second nonreciprocal member 25 may be positioned so as to overlap a portion of the second branch path 28 when viewed from the normal direction to the main surface of the substrate 12. Specifically, the second nonreciprocal member 25 may be positioned so as to overlap a portion of the second branch path 28 extending in the first direction.

[0042] The first nonreciprocal member 24 and the second nonreciprocal member 25 may be located in the first branch path 27 and the second branch path 28 so that the directions of propagation of electromagnetic waves branching at one branch portion 26 are opposite to each other. For example, the first nonreciprocal member 24 may be provided in a portion where the electromagnetic wave incident on the first branch portion 29 and propagating through the first branch path 27 travels in the second direction, and the second nonreciprocal member 25 may be provided in a portion where the electromagnetic wave propagating through the second branch path 28 travels in the direction opposite to the second direction. Alternatively, the first nonreciprocal member 24 may be provided in a portion where the electromagnetic wave incident on the first branch portion 29 and propagating through the first branch path 27 travels in the direction opposite to the second direction, and the second nonreciprocal member 25 may be provided in a portion where the electromagnetic wave propagating through the second branch path 28 travels in the second direction. Specifically, the first non-reciprocal member 24 may be located in a first branch path 27 between the second location p2 and the second branch 30, while the second non-reciprocal member 25 may be located in a second branch path 28 between the third location p3 and the fourth location p4.

[0043] The following explains how the phase shifter 23 functions as a nonreciprocal waveguide with the configuration of this specific example. Assume that the phase of an electromagnetic wave advances by 45 degrees when a magnetic field is applied from the right side of the propagation direction of the electromagnetic wave, and lags by 45 degrees when a magnetic field is applied from the left side of the propagation direction of the electromagnetic wave. In the phase shifter 23 illustrated in FIG. 6, the magnetic field is applied in a first direction.

[0044] When an electromagnetic wave propagates in the first propagation direction, the propagation direction of the electromagnetic wave in the portion of the first branch path 27 overlapping the first nonreciprocal member 24 is from left to right. On the other hand, the propagation direction of the electromagnetic wave in the portion of the second branch path 28 overlapping the second nonreciprocal member 25 is from right to left. Therefore, a magnetic field is applied to the portion of the first branch path 27 overlapping the first nonreciprocal member 24 from the right side of the propagation direction of the electromagnetic wave. Also, a magnetic field is applied to the portion of the second branch path 28 overlapping the second nonreciprocal member from the left side of the propagation direction of the electromagnetic wave. Therefore, the phase of the electromagnetic wave in the first branch path 27 leads by 45 degrees. Conversely, the phase of the electromagnetic wave in the second branch path 28 lags by 45 degrees. As a result, the phase of the electromagnetic wave propagating in the first propagation direction through the first branch path 27 leads the phase of the electromagnetic wave propagating in the first propagation direction through the second branch path 28 by 90 degrees.

[0045] Conversely, when the electromagnetic wave propagates in the second propagation direction, the propagation direction of the electromagnetic wave in the portion of the first branch path 27 overlapping the first nonreciprocal member 24 is from right to left. On the other hand, the propagation direction of the electromagnetic wave in the portion of the second branch path 28 overlapping the second nonreciprocal member 25 is from left to right. Therefore, the magnetic field is applied to the portion of the first branch path 27 overlapping the first nonreciprocal member 24 from the left side of the propagation direction of the electromagnetic wave. Also, the magnetic field is applied to the portion of the second branch path 28 overlapping the second nonreciprocal member 25 from the right side of the propagation direction of the electromagnetic wave. Therefore, the phase of the electromagnetic wave in the first branch path 27 lags by 45 degrees. Conversely, the phase of the electromagnetic wave in the second branch path 28 leads by 45 degrees. As a result, the phase of the electromagnetic wave propagating in the second propagation direction through the first branch 27 lags behind the phase of the electromagnetic wave propagating in the second propagation direction through the second branch 28 by 90 degrees. As described above, the first portion 22 may be configured such that the phase of the electromagnetic wave propagating in the first branch 27 lags behind the phase of the electromagnetic wave propagating in the second branch 28 by 90 degrees in both the first propagation direction and the second propagation direction.

[0046] Therefore, when the electromagnetic wave propagates in the first propagation direction in the phase shift section 23, the phase of the electromagnetic wave propagating in the first branch path 27 advances by 90 degrees, and as a result, the difference in phase between the electromagnetic wave propagating in the first branch path 27 and the electromagnetic wave propagating in the second branch path 28 becomes 0 degrees in the second branch section 30. As a result, when the electromagnetic wave propagating in the first branch path 27 and the electromagnetic wave propagating in the second branch path 28 are multiplexed in the second branch section 30, they reinforce each other, causing the electromagnetic wave to be transmitted in the first propagation direction.

[0047] Conversely, when the electromagnetic wave propagates in the second propagation direction in the phase shift section 23, the phase of the electromagnetic wave propagating through the first branch path 27 is delayed by 90 degrees, and as a result, in the second branch section 30, the difference in phase between the electromagnetic wave propagating through the first branch path 27 and the electromagnetic wave propagating through the second branch path 28 becomes 180 degrees. As a result, when the electromagnetic wave propagating through the first branch path 27 and the electromagnetic wave propagating through the second branch path 28 are combined in the second branch section 30, they weaken each other, and the electromagnetic wave does not transmit in the second propagation direction.

[0048] In other words, the phase shifter 23 is configured so that the propagation direction of the electromagnetic wave in the portion of the first branch path 27 that overlaps with the first nonreciprocal member 24 when viewed from the normal direction of the substrate 12 differs from the propagation direction of the electromagnetic wave in the portion of the second branch path 28 that overlaps with the second nonreciprocal member 25 when viewed from the normal direction. With this configuration, the phase shifter 23 can cause the phase of the electromagnetic wave to advance or delay differently when the electromagnetic wave propagates in the first propagation direction and when the electromagnetic wave propagates in the second propagation direction. As a result, the phase shifter 23 may be configured to transmit the electromagnetic wave propagating in the first propagation direction and not transmit the electromagnetic wave propagating in the second propagation direction.

[0049] Next, a method for manufacturing the isolator 10 of the first embodiment will be described below. In the manufacturing method of this embodiment, the waveguide 11 is made of Si and the substrate 12 is made of SiO ２ However, as described above, the materials of the waveguide 11 and the substrate 12 are not limited to these materials.

[0050] First, SiO ２By patterning one Si layer of an SOI (Silicon On Insulator) substrate having a layer, SiO ２ A waveguide 11 having a longitudinal direction along a first surface s1 is formed on a substrate 12 having layers.

[0051] Next, a recess rs may be formed on the first surface s1 of the substrate 12 at a position where the first magnetic material part 13 and the second magnetic material part 14 are fixed. Furthermore, a groove gr may be formed on the first surface s1 of the substrate 12 between a region where a part of the waveguide 11 sandwiched between the first magnetic material part 13 and the second magnetic material part 14 is mounted and a region where the radiation source 16 is mounted. The recess rs and the groove gr may be formed by, for example, etching.

[0052] Next, adhesive may be applied to the recess rs at the position where the first magnetic material portion 13 is to be fixed, in other words, to the recess rs formed in the first direction relative to a portion of the waveguide 11. The first magnetic material portion 13 is fixed by embedding a portion of the first magnetic material portion 13 in the recess rs at the position where the first magnetic material portion 13 is to be fixed and then curing the adhesive. Alternatively, adhesive may be applied to the recess rs at the position where the second magnetic material portion 14 is to be fixed, in other words, to the recess rs formed on the opposite side of the first magnetic material portion 13 across a portion of the waveguide 11 (the opposite side of the first direction). The second magnetic material portion 14 is fixed by embedding a portion of the second magnetic material portion 14 in the recess rs at the position where the second magnetic material portion 14 is to be fixed and then curing the adhesive.

[0053] Furthermore, on the first surface s1, a radiation source 16 may be mounted on the opposite side of the groove gr from the portion of the waveguide 11 sandwiched between the first magnetic material portion 13 and the second magnetic material portion 14.

[0054] Next, for example, a sealant that will become the first sealing material 15 is applied to a portion of the substrate 12, the first magnetic material portion 13, and the second magnetic material portion 14, and then cured, thereby covering the portion of the substrate 12, the first magnetic material portion 13, and the second magnetic material portion 14 with the first sealing material 15. A portion of the waveguide 11 and the groove gr may also be covered with the first sealing material 15, similar to the first magnetic material portion 13, etc.

[0055] Next, for example, a sealant that will become the second sealant 17 may be applied to the other part of the substrate 12 and the radiation source 16 and cured, thereby covering the other part and the radiation source 16 with the second sealant 17.

[0056] Next, the first magnetic material part 13 and the second magnetic material part 14 covered with the first sealing material 15 are magnetized. The magnetization may be performed by applying a magnetic field to the first magnetic material part 13 and the second magnetic material part 14 from the outside in either a first direction or a direction opposite to the first direction.

[0057] The isolator 10 of the first embodiment configured as described above comprises a waveguide 11 that propagates electromagnetic waves along the extension direction, a substrate 12 on which the waveguide 11 is mounted, a first magnetic material portion 13 that is located in a first direction parallel to the main surface of the substrate 12 relative to a first portion 22 that is a part of the waveguide 11 and that includes at least one magnetic material, a second magnetic material portion 14 that is located in the opposite direction to the first direction relative to the first portion 22 and that includes at least one magnetic material, and a first sealing material 15 that is positioned so as to cover at least a portion of the main surface of the substrate 12, the first magnetic material portion 13, and the second magnetic material portion 14, and the first magnetic material portion 13 and the second magnetic material portion 14 are fixed by at least one of engaging with a recess rs formed in the main surface of the substrate 12 and adhering with an adhesive portion 20. When the first magnetic material portion 13 and the second magnetic material portion 14 are magnetized, it is difficult to install them in positions with high precision due to the magnetic force generated between the first magnetic material portion 13 and the second magnetic material portion 14. In response to such an event, the isolator 10 having the above-described configuration can magnetize the first magnetic material portion 13 and the second magnetic material portion 14 after fixing them, which do not generate magnetic force before magnetization, and therefore the first magnetic material portion 13 and the second magnetic material portion 14 can be positioned with high precision.

[0058] Furthermore, in the isolator 10 of the first embodiment, the center positions in the normal direction to the main surfaces of the magnetic material included in the first magnetic material portion 13 and the magnetic material included in the second magnetic material portion 14 overlap with the first portion 22 when viewed from the first direction. With this configuration, the isolator 10 can position the waveguide 11 at a position where the magnetic flux density is relatively high between the first magnetic material portion 13 and the second magnetic material portion 14. Therefore, the isolator 10 can improve the magneto-optical effect in the waveguide 11.

[0059] Moreover, the isolator 10 of the first embodiment further includes a radiation source 16 mounted on the substrate 12, and a groove gr is formed on the main surface of the substrate 12 between the first portion 22 and the radiation source 16. With this configuration, the isolator 10 blocks the heat generated in the radiation source 16 from being transferred to the portion of the waveguide 11 at the groove gr, thereby reducing the thermal conductivity of the heat to the portion.

[0060] Furthermore, in the isolator 10 of the first embodiment, the radiation source 16 is positioned relative to the first portion 22 in a direction perpendicular to the first direction and parallel to the main surface. With this configuration, even if the waveguide 11 branches between the first magnetic material portion 13 and the second magnetic material portion 14, the isolator 10 can make the distances from the radiation source 16 to each of the branched waveguides 11 approximately equal. Therefore, even if the waveguide 11 branches between the first magnetic material portion 13 and the second magnetic material portion 14, the isolator 10 can reduce the temperature difference between each of the branched waveguides 11. As a result, the isolator 10 can reduce the effect of heat transfer on the transmittance of electromagnetic waves in the forward direction and the blocking ability of electromagnetic waves in the reverse direction.

[0061] Furthermore, in the isolator 10 of the first embodiment, the groove gr is filled with the first sealing material 15. With such a configuration, the isolator 10 can reduce the heat transfer of heat generated in the radiation source 16 to the first portion 22 because the first sealing material 15 generally has lower thermal conductivity than the material of the substrate 12.

[0062] Moreover, the isolator 10 of the first embodiment further includes a second sealing material 17, which has higher thermal conductivity than the first sealing material 15 and covers at least a part of the main surface of the substrate 12 and the radiation source 16. With this configuration, the isolator 10 can further reduce the thermal conductivity of the heat of the radiation source 16, which may be generated by radiating electromagnetic waves, to the part of the waveguide 11 located between the first magnetic material part 13 and the second magnetic material part 14.

[0063] Moreover, the isolator 10 of the first embodiment further includes a heat dissipation member 18 located in contact with the second sealing material 17. With this configuration, the isolator 10 has a heat path formed from the radiation source 16 to the heat dissipation member 18, which transfers heat more efficiently than the heat transfer to the portion of the waveguide 11 located between the first magnetic material portion 13 and the second magnetic material portion 14. Therefore, the isolator 10 can reduce a temperature rise in the portion of the waveguide 11 located between the first magnetic material portion 13 and the second magnetic material portion 14, which is caused by heat from the radiation source 16 that may be generated by radiating electromagnetic waves.

[0064] Moreover, the isolator 10 of the first embodiment further includes electrode pads 19 that are located at positions different from the radiation source 16 when viewed from the normal direction of the main surface and that apply voltage to elements provided on the substrate 12, and the heat dissipation member 18 is located so as to partially overlap the radiation source 16 when viewed from the normal direction of the main surface. The isolator requires the mounting of electrode pads. However, if a heat dissipation member is provided on the electrode pads, it becomes impossible to wire electrode cables to the electrode pads. In response to such a situation, the isolator 10 having the above-described configuration can shorten the heat transfer path from the radiation source 16, improving heat dissipation, while still allowing electrode cables to be wired to the electrode pads 19.

[0065] Next, a second embodiment of the present disclosure will be described. The second embodiment differs from the first embodiment in that a spacer is provided. The second embodiment will be described below, focusing on the differences from the first embodiment. Note that parts having the same configuration as those in the first embodiment will be assigned the same reference numerals.

[0066] In the second embodiment, the isolator is configured to include a waveguide 11, a substrate 12, a first magnetic material portion 13, a second magnetic material portion 14, and a first sealing material 15, similar to the first embodiment. Also, in the second embodiment, the isolator may be configured to further include a radiation source 16, a second sealing material 17, a heat dissipation member 18, and an electrode pad 19, similar to the first embodiment. As shown in FIG. 8 , in the second embodiment, the isolator 100 is configured to further include a spacer 210. The configurations and functions of the waveguide 11, the substrate 12, the first magnetic material portion 13, the second magnetic material portion 14, the first sealing material 15, the radiation source 16, the second sealing material 17, the heat dissipation member 18, and the electrode pad 19 are the same as those in the first embodiment.

[0067] The spacer 210 is located between the first magnetic material portion 13 and the second magnetic material portion 14. The spacer 210 may maintain the distance between the first magnetic material portion 13 and the second magnetic material portion 14 in the first direction. The spacer 210 may be made of any material. The spacer 210 may be integrated with the first magnetic material portion 13 and the second magnetic material portion 14. In an integrated configuration, the spacer 210 may be made of the same material as the first magnetic material portion 13 and the second magnetic material portion 14.

[0068] Next, a method for manufacturing the isolator 100 of the second embodiment will be described below. In the manufacturing method of this embodiment, the waveguide 11 is made of Si and the substrate 12 is made of SiO ２ However, as described above, the materials of the waveguide 11 and the substrate 12 are not limited to these materials.

[0069] First, as in the first embodiment, a waveguide 11 having a longitudinal direction along the first surface s1 is formed on a substrate 12. Also, as in the first embodiment, a recess rs and a groove gr may be formed in the first surface s1 of the substrate 12. Next, as in the first embodiment, an adhesive may be applied to the recess rs.

[0070] Next, unlike the first embodiment, a portion of each of the first magnetic material portion 13 and the second magnetic material portion 14 sandwiching the spacer 210 is embedded in the recess rs. After embedding, the first magnetic material portion 13 and the second magnetic material portion 14 are fixed by curing the adhesive. The first magnetic material portion 13 and the second magnetic material portion 14 may or may not be magnetized before being embedded in the recess rs.

[0071] In a configuration in which the spacer 210 is not integrated with the first magnetic material portion 13 and the second magnetic material portion 14 after the adhesive has hardened, the spacer 210 may be removed. Alternatively, the spacer 210 does not need to be removed.

[0072] Next, as in the first embodiment, the radiation source 16 may be mounted on the first surface s1. Next, similarly to the first embodiment, a part of the substrate 12, the first magnetic material part 13, and the second magnetic material part 14 may be covered with the first sealing material 15. Next, as in the first embodiment, another part of the substrate 12 and the radiation source 16 may be covered with the second sealing material 17.

[0073] In a configuration in which the first magnetic material portion 13 and the second magnetic material portion 14 are not magnetized before being fixed, the first magnetic material portion 13 and the second magnetic material portion 14 covered with the first sealing material 15 may then be magnetized, as in the first embodiment.

[0074] Like the first embodiment, the isolator 100 of the second embodiment configured as described above also includes a waveguide 11 that propagates electromagnetic waves along an extension direction, a substrate 12 on which the waveguide 11 is mounted, a first magnetic material portion 13 that is located in a first direction parallel to the main surface of the substrate 12 with respect to a first portion 22 that is a part of the waveguide 11 and that includes at least one magnetic material, a second magnetic material portion 14 that is located in the opposite direction to the first direction with respect to the first portion 22 and that includes at least one magnetic material, and a first sealing material 15 that is located so as to cover at least a portion of the main surface of the substrate 12, the first magnetic material portion 13, and the second magnetic material portion 14, and the first magnetic material portion 13 and the second magnetic material portion 14 are fixed by at least one of engagement with a recess rs formed in the main surface of the substrate 12 and adhesion by an adhesive portion 20. Therefore, the isolator 100 can also align the first magnetic material portion 13 and the second magnetic material portion 14 with high precision.

[0075] Moreover, unlike the first embodiment, the isolator 100 of the second embodiment further includes a spacer 210 positioned between the first magnetic material portion 13 and the second magnetic material portion 14. With this configuration, the isolator 100 can suppress the influence of magnetic force by the spacer 210 even if the first magnetic material portion 13 and the second magnetic material portion 14 are magnetized during manufacturing. Therefore, the isolator 100 can use the first magnetic material portion 13 and the second magnetic material portion 14 that are magnetized before being fixed to the substrate 12.

[0076] Also in the isolator 100 of the second embodiment, as in the first embodiment, the center positions in the normal direction to the main surfaces of the magnetic material included in the first magnetic material portion 13 and the magnetic material included in the second magnetic material portion 14 overlap with the first portion 22 when viewed from the first direction. Therefore, the isolator 100 can also improve the magneto-optical effect in the waveguide 11.

[0077] Similarly to the first embodiment, the isolator 100 of the second embodiment also includes the radiation source 16 mounted on the substrate 12, and a groove gr is formed on the main surface of the substrate 12 between the first portion 22 and the radiation source 16. Therefore, the isolator 100 can also reduce the thermal conductivity of heat generated in the radiation source 16 to a portion of the waveguide 11.

[0078] Also, in the isolator 100 of the second embodiment, similarly to the first embodiment, the radiation source 16 is positioned in a direction perpendicular to the first direction and parallel to the main surface with respect to the first portion 22. Therefore, the isolator 100 can also reduce the influence of heat transfer on the transmittance of electromagnetic waves in the forward direction and the blocking ability of electromagnetic waves in the reverse direction.

[0079] Also, in the isolator 100 of the second embodiment, as in the first embodiment, the groove gr is filled with the first sealing material 15. With this configuration, the isolator 100 can also reduce the heat transfer of heat generated in the radiation source 16 to the first portion 22 because the first sealing material 15 generally has lower thermal conductivity than the material of the substrate 12.

[0080] Similarly to the first embodiment, the isolator 100 of the second embodiment also includes a second sealing material 17 that has higher thermal conductivity than the first sealing material 15 and covers at least a part of the main surface of the substrate 12 and the radiation source 16. Therefore, the isolator 100 can also further reduce the thermal conductivity of the heat of the radiation source 16, which may be generated by radiating electromagnetic waves, to the portion of the waveguide 11 located between the first magnetic material portion 13 and the second magnetic material portion 14.

[0081] Similarly to the first embodiment, the isolator 100 of the second embodiment also includes a heat dissipation member 18 located in contact with the second sealing material 17. Therefore, the isolator 100 can also reduce the temperature rise of the portion of the waveguide 11 located between the first magnetic material portion 13 and the second magnetic material portion 14, which is caused by the heat of the radiation source 16 that may generate heat by radiating electromagnetic waves.

[0082] Similarly to the first embodiment, the isolator 100 of the second embodiment further includes electrode pads 19 that are located at positions different from the radiation source 16 when viewed from the normal direction of the main surface and that apply voltage to elements provided on the substrate 12, and the heat dissipation member 18 is located so as to partially overlap the radiation source 16 when viewed from the normal direction of the main surface. Therefore, the isolator 100 can also improve heat dissipation by shortening the heat transfer path from the radiation source 16 while allowing electrode cables to be wired to the electrode pads 19.

[0083] Although the embodiments according to the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art would easily be able to make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications and alterations are included within the scope of the present disclosure. For example, the functions included in each component or step can be rearranged so as not to be logically inconsistent, and multiple components or steps can be combined or divided into one.

[0084] For example, in the first and second embodiments, the phase shift section 23 realizes asymmetric electromagnetic wave propagation characteristics using the principle of an asymmetric Mach-Zehnder interferometer, but the asymmetric electromagnetic wave propagation characteristics may also be realized by a directional coupler type or ring resonator type configuration.

[0085] In this disclosure, descriptions such as "first" and "second" are identifiers for distinguishing the configuration. In this disclosure, the configurations distinguished by descriptions such as "first" and "second" can have their numbers interchanged. For example, the first magnetic material part can have its identifiers "first" and "second" interchanged with the second magnetic material part. The identifiers are interchanged simultaneously. The configurations remain distinguished even after the identifiers are interchanged. Identifiers may be deleted. A configuration from which an identifier has been deleted is distinguished by a symbol. The identifiers "first" and "second" in this disclosure should not be used solely to interpret the order of the configurations or to justify the existence of an identifier with a smaller number.

[0086] 10 Isolator 11 Waveguide 12 Substrate 13 First magnetic material portion 14 Second magnetic material portion 15 First sealing material 16 Radiation source 17 Second sealing material 18 Heat dissipation member 19 Heat transfer pad 20 Adhesive portion 210 Spacer 22 First portion 23 Phase shift portion 24 First non-reciprocal member 25 Second non-reciprocal member 26 Branch portion 27 First branch path 28 Second branch path 29 First branch portion 30 Second branch portion gr Groove p1 First location p2 Second location p3 Third location p4 Fourth location rs Recess s1 First surface

Claims

1. An isolator comprising: a waveguide that propagates electromagnetic waves along an extension direction; a substrate on which the waveguide is mounted; a first magnetic material portion located in a first direction parallel to a main surface of the substrate with respect to a first portion that is a part of the waveguide and including at least one magnetic material; a second magnetic material portion located in a direction opposite to the first direction with respect to the first portion and including at least one magnetic material; and a first sealing material located so as to cover at least a portion of the main surface of the substrate, the first magnetic material portion, and the second magnetic material portion, wherein the first magnetic material portion and the second magnetic material portion are fixed by at least one of engagement with a recess formed in the main surface of the substrate and adhesion with an adhesive portion.

2. The isolator according to claim 1, further comprising a spacer positioned between the first magnetic body and the second magnetic body.

3. An isolator according to claim 2, wherein the spacer is integrated with the first magnetic body and the second magnetic body.

4. An isolator according to any one of claims 1 to 3, wherein the central positions of the magnetic material contained in the first magnetic material section and the magnetic material contained in the second magnetic material section in the normal direction to the main surfaces overlap with the first portion when viewed from the first direction.

5. An isolator according to any one of claims 1 to 4, further comprising a radiation source mounted on the substrate, wherein a groove is formed on the main surface of the substrate between the first portion and the radiation source.

6. An isolator according to claim 5, wherein the radiation source is positioned relative to the first portion in a direction perpendicular to the first direction and parallel to the main surface.

7. An isolator according to claim 5 or 6, wherein the groove is filled with the first sealing material.

8. An isolator according to any one of claims 5 to 7, further comprising a second sealing material having a higher thermal conductivity than the first sealing material and covering at least a part of the main surface of the substrate and the radiation source.

9. The isolator according to claim 8, further comprising a heat dissipation member positioned in contact with the second sealing material.

10. An isolator according to claim 9, further comprising an electrode pad that is located at a position different from the radiation source when viewed from the normal direction of the main surface and that applies a voltage to an element provided on the substrate, and the heat dissipation member is located so that a portion of the heat dissipation member overlaps with the radiation source when viewed from the normal direction of the main surface.

11. A method for manufacturing an isolator, comprising: forming a waveguide on a substrate; fixing a first magnetic material part in a first direction parallel to a main surface of the substrate to a first portion that is a part of the waveguide; fixing a second magnetic material part in a direction opposite to the first direction; covering the part of the substrate, the first magnetic material part, and the second magnetic material part with a first sealing material; and magnetizing the first magnetic material part and the second magnetic material part.

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