Optical Module

Abstract

The present invention provides an optical module capable of stabilizing the optical coupling between an optical circuit element and an array lens against temperature changes to obtain stable optical characteristics. An optical module according to one embodiment comprises: a base having a first surface; a substrate having a second surface and a third surface; an optical circuit element having a fourth surface, a fifth surface and two ports; and an array lens, wherein the first surface is bonded to the second surface by a first solder material, the third surface has a first pattern and a second pattern, the first pattern and the second pattern are bonded to the fourth surface by a second solder material, the array lens is fixed on the surface of the first surface of the base so as to be optically coupled with the two ports of the optical circuit element, the first pattern is arranged near one end of the optical circuit element compared to the second pattern in the first direction, and is arranged between the two ports in the second direction.

Description

Technical Field

[0001] One aspect of the present invention relates to an optical module. Background Art

[0002] Patent document 1 describes an optical module having a PLC chip. The optical module has a first PLC chip and a second PLC chip. The first PLC chip has an input optical waveguide array, a VOA array, and an output optical waveguide. The second PLC chip has an input optical waveguide array, an AWG, and an output optical waveguide. The input optical waveguide array of the first PLC chip is optically coupled with an optical fiber array located outside the optical module. The output optical waveguide of the second PLC chip is optically coupled with an optical fiber extending to the opposite side of the optical fiber array. A substrate, a first mounting member, and a second mounting member are provided below the first PLC chip and the second PLC chip. Both the first mounting member and the second mounting member are arranged on the substrate. The first mounting member is fixed to the substrate by a first fixing screw, and is fixed by a second fixing screw so as to be movable in a direction approaching or separating from the second mounting member. The second mounting member is fixed to the substrate by a third fixing screw, and is fixed by a fourth fixing screw so as to be movable in a direction approaching or separating from the first mounting member. The height of the first mounting member from the substrate is higher than the height of the second mounting member from the substrate. The first PLC chip is fixed on the first mounting member. The second PLC chip is arranged so as to float from the second mounting member, and is held on the second mounting member by the elastic adhesive accumulated on the second mounting member.

[0003] Patent document 2 describes an optical module having an optical mixing element and a support for mounting the optical mixing element. The optical mixing element includes a semiconductor MMI coupler and a semiconductor optical waveguide led out from the MMI coupler. Signal light and local oscillation light are input to the optical module. The input signal light is respectively distributed to two optical mixing elements. The input local oscillation light is respectively distributed to two optical mixing elements in the same manner as the signal light. The optical mixing element is a PD-integrated multimode mixer using a semiconductor substrate. The optical mixing element has a PD (Photo Diode) for generating a photocurrent. The photocurrent generated by the PD is converted into a voltage signal by an amplifier provided outside the optical mixing element. Each of the two optical mixing elements has a signal light port for inputting signal light and a local oscillation light port for inputting local oscillation light. The signal light port and the local oscillation light port of one of the two optical mixing elements are optically coupled with a first lens system and a second lens system respectively arranged inside the package of the optical module. The signal light port and the local oscillation light port of the other of the two optical mixing elements are optically coupled to the third lens system and the fourth lens system disposed inside the package of the optical module, respectively.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2009-265188

[0005] Patent Document 2: Japanese Patent Application Publication No. 2017-32629

[0006] In addition, in an optical module having an optical circuit element with two ports and an array lens having a plurality of lenses optically coupled with the two ports, it is sought to improve the coupling efficiency of the optical coupling between the ports and the lenses. In the optical module, a substrate and the optical circuit element are fixed on a base, and the optical circuit element is fixed to the substrate via a solder material. The solder material is melted by heating the solder material, and then the solder material is solidified by cooling, so that the optical semiconductor element is fixed to the substrate. The substrate for fixing the optical circuit element mostly uses a material with high thermal conductivity. The material of the substrate is different from that of the optical circuit element. Therefore, when the optical circuit element is mounted on the optical module, due to the difference in the linear expansion coefficient of the substrate and the linear expansion coefficient of the optical circuit element, the interval between the two ports of the optical circuit element may change due to the temperature change accompanying the heating and cooling of the solder material. If the interval between the two ports is inconsistent with the interval between the lenses of the array lens, when the array lens is aligned relative to the optical circuit element, one of the two ports can be optically coupled with one lens, but the other of the two ports cannot be fully optically coupled with the other lens. Therefore, the change in the distance between the two ports due to the temperature change may deteriorate the coupling efficiency. Therefore, there is a concern that the optical coupling and optical characteristics may become unstable due to the temperature change. Summary of the invention

[0007] One aspect of the present invention provides an optical module capable of stabilizing optical coupling between an optical circuit element and an array lens against temperature changes to obtain stable optical characteristics.

[0008] An optical module according to one embodiment of the present invention comprises: a base having a first surface; a substrate having a flat plate-like shape extending in a first direction, a flat second surface and a third surface located on the opposite side of the second surface; an optical circuit element having a flat plate-like shape extending in the first direction, a fourth surface and a fifth surface located on the opposite side of the fourth surface, and having two ports arranged in a second direction intersecting the first direction at one end of the fifth surface in the first direction; and an array lens having two lenses arranged in the second direction, wherein the first surface of the base is bonded to the second surface of the substrate by a first solder material, and the third surface of the substrate includes a plurality of optical components connected to each other. A first pattern and a second pattern made of metal are arranged along a first direction, the first pattern and the second pattern are bonded to the fourth surface of the optical circuit element through a second solder material, the array lens is fixed to the surface of the first surface of the base so that one of the two lenses is optically coupled with one of the two ports of the optical circuit element, and the other of the two lenses is optically coupled with the other of the two ports of the optical circuit element, when the two ports, the first pattern and the second pattern are observed from the normal direction of the fifth surface, the first pattern is arranged near one end of the optical circuit element compared with the second pattern in the first direction, and is arranged between the two ports in the second direction.

[0009] Effects of the Invention

[0010] According to one aspect of the present invention, it is possible to stabilize the optical coupling between an optical circuit element and an array lens against temperature changes and obtain stable optical characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a plan view showing the internal structure of the optical module according to the embodiment.

[0012] Figure 2 Yes means Figure 1 An oblique view of the optical components, array lens and optical circuit elements of the optical module.

[0013] Figure 3 Yes means Figure 2 An oblique view of an optical circuit element and a substrate.

[0014] Figure 4 Yes means Figure 3 An oblique view of the substrate.

[0015] Figure 5 Yes means Figure 3 A top view of the substrate.

[0016] Figure 6 Yes means Figure 3 A top view of a modified example of a substrate.

[0017] Figure 7This is a diagram showing the relationship between the length of the side portion of the second pattern of the substrate and the amount of change in the interval between ports due to temperature change. DETAILED DESCRIPTION

[0018] [Description of Embodiments of the Invention]

[0019] First, the contents of the embodiments of the present invention are listed for explanation. An optical module involved in one embodiment of the present invention comprises: a base having a first surface; a substrate having a flat plate-like shape extending in a first direction, having a second surface and a third surface located on the opposite side of the second surface; an optical circuit element having a flat plate-like shape extending in the first direction, having a fourth surface and a fifth surface located on the opposite side of the fourth surface, and having two ports arranged along a second direction intersecting the first direction at one end of the first direction of the fifth surface; and an array lens having two lenses arranged along the second direction, the first surface of the base being bonded to the second surface of the substrate by a first solder material, and the third surface of the substrate including a plurality of lenses arranged along the second direction. A first pattern and a second pattern made of metal are arranged in a first direction, the first pattern and the second pattern are bonded to the fourth surface of the optical circuit element through a second solder material, the array lens is fixed to the surface of the first surface of the base so that one of the two lenses is optically coupled with one of the two ports of the optical circuit element, and the other of the two lenses is optically coupled with the other of the two ports of the optical circuit element, when the two ports, the first pattern and the second pattern are observed from the normal direction of the fifth surface, the first pattern is arranged near one end of the optical circuit element compared with the second pattern in the first direction, and is arranged between the two ports in the second direction.

[0020] In the optical module, the second surface of the substrate is placed on the first surface of the base, and the fourth surface of the optical circuit element is placed on the third surface on the opposite side of the second surface of the substrate. A first metal pattern is formed on the third surface of the substrate, and the first pattern is bonded to the fourth surface of the optical circuit element through a second solder material. The optical circuit element has two ports arranged along the second direction, and the two ports are optically coupled with each lens of the lens array fixed on the first surface of the base. When observed from the normal direction of the fifth surface of the optical circuit element, the first pattern and the second solder material formed on the first pattern are arranged on the inner side of the two ports in the second direction. The fourth surface of the optical circuit element is bonded to the first pattern of the third surface by melting and solidifying the second solder material. Therefore, the substrate and the optical circuit element are fixed by the first pattern on the inner side of the two ports when observed from the normal direction of the fifth surface. As a result, the area of ​​the second solder material is located on the inner side of the two ports when observed from the normal direction of the fifth surface, so that the interval between the two ports can be suppressed from changing when the temperature changes due to the heating and cooling of the second solder material. Therefore, when the lenses of the array lens are aligned with respect to the optical input port, the optical axis of the lens is prevented from being offset from the optical axis of the optical input port, thereby suppressing the optical coupling loss. As a result, the optical coupling and optical characteristics of the optical module accompanying temperature changes can be stabilized.

[0021] Furthermore, when the substrate and the optical circuit element are viewed from the normal direction, the optical circuit element may be included inside the substrate.

[0022] In addition, the distance between the second surface and the third surface of the substrate can be greater than 300 μm and less than 600 μm. The distance between the fourth surface and the fifth surface of the optical circuit element can be greater than 50 μm and less than 200 μm. The width of the first pattern in the second direction can be greater than 20% and less than 80% of the distance between the two ports. In this case, the width of the first pattern is less than 80% of the spacing between the two ports, thereby suppressing the variation of the spacing between the two ports associated with temperature changes. In addition, the width of the first pattern is greater than 20% of the spacing between the two ports, thereby more reliably suppressing the warping of the optical circuit element caused by temperature changes.

[0023] In addition, the imaginary line is a straight line extending along the first direction on the third surface, intersecting the first pattern and the second pattern, and when viewed from the normal direction of the fifth surface, the length of the portion where the imaginary line intersects the first pattern may be greater than 0.3 mm and less than 0.6 mm. The length of the portion where the imaginary line intersects the second pattern may be greater than 0.3 mm and less than 0.6 mm.

[0024] In addition, the material of the substrate may include aluminum nitride. The material of each of the first solder material and the second solder material may include gold tin. The material of the optical circuit element may include indium phosphide. In this case, the material of the substrate includes aluminum nitride, thereby improving the thermal conductivity of the substrate and improving the heat dissipation performance of the substrate. In addition, the material of the second solder material includes gold tin, thereby improving the reliability of the bonding.

[0025] In addition, the second pattern may further include a side portion extending from both ends of the second pattern in the second direction toward the first pattern along the first direction. When the optical circuit element and the substrate are observed from the normal direction, the side portion may include an overlapping region overlapping the optical circuit element. The second solder material may be formed to include an overlapping region on the second pattern.

[0026] Furthermore, the distance Ls between the side portion and the two ports in the first direction may be a value larger than 0.5×L1 and smaller than 1.5×L1, when the length of the first pattern in the first direction is L1.

[0027] [Details of the embodiments of the present invention]

[0028] Hereinafter, a specific example of an optical module involved in an embodiment of the present invention is described with reference to the accompanying drawings. The present invention is not limited to the following examples, but is shown by the claims, and includes all changes within the scope equivalent to the claims. In the description of the drawings, the same or equivalent elements are marked with the same reference numerals, and repeated descriptions are appropriately omitted. With respect to the drawings, in order to make it easier to understand, a part is sometimes simplified, and the dimensional ratios, etc. are not limited to the dimensional ratios recorded in the drawings.

[0029] Figure 1: is a top view showing the internal structure of the optical module 1 involved in the present embodiment. The optical module 1 has a roughly rectangular package 2, a signal light input port 3 and a local oscillator light input port 4. The signal light input port 3 and the local oscillator light input port 4 are arranged on one end surface 2b of the package 2. The signal light input port 3 is connected to a single-mode optical fiber, for example, outside the package 2. For example, the single-mode optical fiber supplies received signal light (SIGnal; hereinafter referred to as signal light) to the signal light input port 3. The local oscillator light input port 4 is connected to a polarization-maintaining optical fiber, for example, outside the package 2. For example, the polarization-maintaining optical fiber supplies local oscillator light (Local; hereinafter referred to as local oscillator light) to the local oscillator light input port 4. The optical module 1 has an optical component 5, a first array lens 6, a second array lens 7 and an optical mixing element 10. The optical component 5 includes, for example, a collimating lens, a reflector, a variable optical attenuator, a half-wavelength plate (λ / 2 plate), a skew adjustment element, a polarizer, a spectrometer and a photodiode for an optical power monitor (monitor PD). The signal light input to the signal light input port 3 is distributed to the first array lens 6 and the second array lens 7 through the optical component 5. The local oscillator light input to the local oscillator light input port 4 is distributed to the first array lens 6 and the second array lens 7 through the optical component 5. The signal light and the local oscillator light distributed to the first array lens are respectively focused on the lens of the first array lens 6 and incident on one optical mixing element 10. The signal light and the local oscillator light distributed to the second array lens are respectively focused on the lens of the second array lens 7 and incident on another optical mixing element 10. For example, when the signal light input to the signal light input port 3 is polarization multiplexed, the first polarization component (X polarization light) contained in the signal light is incident on one optical mixing element 10 from the optical component 5 via the first array lens 6. The second polarization component (Y polarization light) orthogonal to the first polarization component contained in the signal light is incident on the other optical mixing element 10 from the optical component 5 via the first array lens 7. In addition, the X polarization and Y polarization mentioned here only indicate the existence of two polarization modes for the sake of convenience, and are not related to the X direction and Y direction described later.

[0030] The optical mixing element 10 is, for example, a PD-integrated multimode mixer in the shape of a rectangular plate. The PD-integrated multimode mixer includes, for example, a semiconductor substrate made of indium phosphide (also called indium phosphide (InP)). The thickness of the optical mixing element 10 is, for example, greater than 50 μm and less than 200 μm. A photocurrent is generated by the PD integrated in the optical mixing element 10. The photocurrent is converted into a voltage signal by, for example, an amplifier 8 provided outside the optical mixing element 10. The amplifier 8 is, for example, a transformer impedance amplifier. The voltage signal converted by the amplifier 8 is output to the outside from any terminal of the plurality of terminals 9 of the package 2. The plurality of terminals 9 are, for example, provided on the end face of the package 2 on the opposite side to the one end face 2b, and extend to the outside of the package 2.

[0031] Figure 21 is an oblique view showing an optical component 5, a first array lens 6, a second array lens 7, an amplifier 8 and an optical mixing element 10. The optical mixing element 10 is, for example, an optical circuit element having a 90° hybrid 15. The 90° hybrid 15, for example, includes an MMI (Multi Mode Interference) coupler formed by a planar waveguide that optically couples the signal light and the local oscillator light. One optical mixing element 10 has two optical input ports 11 (ports). The two optical input ports 11 are optically connected to the 90° hybrid 15 via optical waveguides 14, respectively. The optical waveguide 14 is formed in the optical mixing element 10. That is, for example, the light input from the first array lens 6 to the optical input port 11 is transmitted in the optical waveguide 14 and input to the 90° hybrid 15. In more detail, the signal light and the local oscillator light are respectively input to the two optical input ports 11. The 90° hybrid 15 generates four output lights (IP: In-Phase Positive, IN: In-Phase Negative, QP: Quadrature Positive, QN: Quadrature Negative) from the input signal light and local oscillator light by interference and separation. IP is an optical signal of the positive phase of the 0° component of the received signal light, and IN is an optical signal of the reverse phase of the 0° component of the received signal light. QP is an optical signal of the positive phase of the 90° component of the received signal light, and QN is an optical signal of the reverse phase of the 90° component of the received signal light.

[0032] Figure 3 1 is a perspective view showing the installation state of the light mixing element 10 mounted inside the optical module 1. Figure 2 and Figure 3As shown, the optical mixing element 10 is mounted on the base 30 via the substrate 20. The substrate (plate) 20 is sometimes also referred to as a support. The base 30 is set to a rectangular plate shape. For example, the thickness of the base 30 is greater than 1.0 mm and less than 2.0 mm. The thickness of the base 30 is thicker than the thickness of the optical mixing element 10 and thicker than the thickness of the substrate 20. The material of the base 30 includes, for example, ceramics. The base 30 has a planar first surface 31, and the optical component 5, the first array lens 6, the second array lens 7 and the substrate 20 are mounted on the first surface 31. For example, when observed from the normal direction of the first surface 31, the substrate 20 is accommodated on the inner side of the base 30, and the optical mixing element 10 is accommodated on the inner side of the substrate 20. That is, the optical mixing element 10 does not protrude (overhang) from the substrate 20 in a direction parallel to the first surface 31. For example, when the light mixing element 10 is cantilevered from the substrate 20, the cantilevered portion is not supported by the substrate 20, and a hollow space is formed between the cantilevered portion and the first surface 31. On the first surface 31 of the base 30, the optical component 5 is mounted outside the substrate 20, so the area of ​​the first surface 31 is larger than the area of ​​the surface of the substrate 20 parallel to the first surface 31 (for example, the second surface 21 and the third surface 22 described later). Therefore, the thickness of the base 30 is thicker than the thickness of the light mixing element 10, and the area of ​​the first surface 31 is larger than that of the substrate 20. The base 30 has a rectangular plate shape.

[0033] The first array lens 6 has, for example, two lenses 6b. The two lenses 6b are opposite to the two light input ports 11 of one light mixing element 10 in the length direction of the light mixing element 10. The length direction of the light mixing element 10 is, for example, the same as the optical axis direction of the light input to the light input port 11. The second array lens 7 has two lenses 7b. The two lenses 7b are opposite to the two light input ports 11 of another light mixing element 10 in the length direction of the light mixing element 10. The first array lens 6 is fixed to the first surface 31 of the base 30 so that the two lenses 6b are optically coupled to the two light input ports 11 of one light mixing element 10. For example, the two lenses 6b are arranged and configured in a direction (for example, the Y direction described later) intersecting the length direction of the light mixing element 10 (for example, the X direction described later). For example, the two lenses 7b are arranged and configured in the same direction as the two lenses 6b. The interval between the two lenses 6b is set to be the same as the interval between the two light input ports 11. The interval mentioned here is, for example, the distance between the central axes of the two lenses 6b. In addition, the central axis is also referred to as the optical axis. The distance (height) of the optical axes of the two lenses 6b from the first surface 31 of the base 30 is set and adjusted to be the same as the distance (height) of the optical axis of the light input port 11 from the first surface 31. The distance (height) of the optical axes of the two lenses 7b from the first surface 31 of the base 30 is also set and adjusted in the same manner as the distance (height) of the optical axes of the two lenses 6b from the first surface 31 of the base 30. The material of the first array lens 6 and the second array lens 7 is, for example, glass or silicon. The first array lens 6 and the second array lens 7 can, for example, be set to have the same structure as each other, so in the following description, the first array lens 6 and the second array lens 7 are referred to as array lenses 6, 7.

[0034] Figure 4 2 is a perspective view showing the substrate 20. Figure 3 and Figure 4 As shown, the substrate 20 has a rectangular plate shape. For example, the thickness of the substrate 20 is greater than 300 μm and less than 600 μm. The thickness of the substrate 20, for example, corresponds to the length of the minimum value in each of the outer dimensions in the longitudinal direction, the lateral direction, and the height direction. For example, the thickness of the substrate 20 corresponds to the height of the substrate 20. In addition, the length direction corresponds to the direction in which the outer dimensions are the largest in the three directions of the longitudinal direction, the lateral direction, and the height direction. The material of the substrate 20 includes, for example, aluminum nitride (AlN: aluminum oxide). The substrate 20 has a planar second surface 21 and a planar third surface 22 located on the opposite side of the second surface 21. The second surface 21 is bonded to the first surface 31 of the base 30 via the first solder material 41. The first solder material 41 is not included in the substrate 20, but is Figure 4In order to show the installation state of the substrate 20, the first solder material 41 is shown. When the substrate 20 is joined to the base 30, the first solder material 41 can be formed on the first surface 31 of the base 30 by vapor deposition. In addition, the first solder material 41 can also be in a paste state, and is applied so as to form a predetermined shape on the first surface 31 of the substrate 20. The first solder material 41 is melted by heating. The heating when the substrate 20 and the base 30 are joined will be described later. For example, the third surface 22 of the substrate 20 is a plane parallel to the second surface 21. The thickness of the above-mentioned substrate 20 is, for example, equivalent to the distance between the second surface 21 and the third surface 22. The third surface 22 is joined to the optical mixing element 10 via the second solder material 42. The materials of the first solder material 41 and the second solder material 42 are, for example, gold tin (AuSn). In this case, the linear expansion coefficients of the first solder material 41 and the second solder material 42 are, for example, 17.5×10 －6 ( / K). The light mixing element 10 has a metallized planar fourth surface 12 and a fifth surface 13 located on the opposite side of the fourth surface 12 (see Figure 3 ). The fourth surface 12 is bonded to the third surface 22 of the substrate 20 via the second solder material 42. For example, the fifth surface 13 is a plane parallel to the fourth surface 12. In addition, the third surface 22 of the substrate 20 includes a first pattern 23 and a second pattern 24. The first pattern 23 and the second pattern 24 are both made of metal. The first pattern 23 and the second pattern 24 may include, for example, at least one of titanium (Ti), platinum (pt), gold (Au), or an alloy thereof. In addition, the second surface 21 of the substrate 20 may also be metallized, for example, by at least one of titanium (Ti), platinum (pt), gold (Au), or an alloy thereof. Figure 3 As shown, the first pattern 23 is arranged at a position closer to the two light input ports 11 than the second pattern 24 in the length direction of the substrate 20. That is, in the length direction of the substrate 20, the distance between the first pattern 23 and the light input port 11 is shorter than the distance between the second pattern 24 and the light input port 11. In addition, the first pattern 23 is arranged near one end (for example, the side where the light input port is provided) in the length direction of the light mixing element 10 than the second pattern 24, and the second pattern 24 is arranged near the other end (for example, the side opposite to the side where the light input port is provided) in the length direction of the light mixing element 10 than the first pattern 23.

[0035] The second solder material 42 is formed by vapor deposition on the first pattern 23 and the second pattern 24 in accordance with the shape of the light mixing element 10. When the light mixing element 10 is joined to the substrate 20, the second solder material 42 may be in a paste state and applied so as to form a predetermined shape on the first pattern 23 and the second pattern 24. For example, the second solder material 42 is in a solder paste state and applied on the first pattern 23 and the second pattern 24 through a metal mask. The second solder material 42 is melted by heating. The heating of the first solder material 41 and the second solder material 42 is performed, for example, by bringing a metal heat-conducting member (heating tool) into contact with a portion close to the first solder material 41 or the second solder material 42 of the base 30, the substrate 20, and the light mixing element 10, heating the heat-conducting member, and transferring heat through the contact portion. In addition, if the first solder material 41 and the second solder material 42 can be melted, only a predetermined portion of the base 30 and the substrate 20 may be heated. The first solder material 41 is heated to melt, and is cooled to solidify. The solidified first solder material 41 joins the second surface 21 of the substrate 20 to the first surface 31 of the base 30 .

[0036] The second solder material 42 is heated to melt, and is cooled to solidify. The first pattern 23 and the second pattern 24 are each bonded to the fourth surface 12 of the light mixing element 10 by the solidified second solder material 42. The molten second solder material 42 spreads in the X direction and the Y direction on the surface of the fourth surface 12, but the shape of the second solder material 42 in the solidified state is preferably contained inside the first pattern when viewed from the normal direction (Z direction) in a plan view. When the length (width) W2 of the second pattern 24 in the Y direction is greater than the length (width) W4 of the light mixing element 10 in the Y direction, the second solder material 42 is formed by vapor deposition (or applied) to include an area (overlapping area) where the fourth surface 12 and the second pattern 24 overlap when viewed from the Z direction. The second solder material 42 applied to the overlapping area melts and expands compared to the overlapping area when bonded to the fourth surface 12. As a result, in the portion where the second pattern 24 is bonded to the fourth surface 12 via the second solder material 42, the second solder material 42 expands compared to the overlapping area. Therefore, the length (width) W3 of the second solder material 42 in the Y-axis direction on the second pattern 24 in the bonded (solidified) state is larger than the width W4 of the light mixing element 10 in the Y-axis direction. For example, the width W3 may be larger than the width W4 by more than 100 μm. For example, the solidified second solder material 42 may be larger than the light mixing element 10 by more than 50 μm at both ends of the second solder material 42 in the Y-axis direction. Therefore, in the state where the light mixing element 10 is bonded to the substrate 20, the width W3 of the second solder material 42 on the second pattern 24 is smaller than the width W2 of the second pattern, and the width W4 of the light mixing element 10 is smaller than the width W3. The molten first solder material 41 solidifies when the heating stops and the temperature drops, and the substrate 20 is firmly fixed to the base 30. In addition, the molten second solder material 42 solidifies when the heating stops and the temperature drops, and the light mixing element 10 is firmly fixed to the substrate 20. When the light mixing element 10 is bonded to the substrate 20 , the thickness of the second solder material 42 is, for example, 5 μm or more and 10 μm or less. This thickness corresponds to the distance between the first pattern 23 and the second pattern 24 and the fourth surface 12 of the light mixing element 10 when the light mixing element 10 is bonded to the substrate 20 .

[0037] In addition, when the light mixing element 10 and the substrate 20 are bonded, the second solder material 42 is heated and then cooled, so that, for example, a temperature change occurs from 280° C., which is the melting point of AuSn, to 25° C., which is a normal temperature. As described above, when the material of the light mixing element 10 is InP and the material of the substrate 20 is alumina, the linear expansion coefficient of the light mixing element 10 is, for example, 4.5×10 －6 ( / K), the linear expansion coefficient of the substrate 20 is, for example, 7.2×10 －6( / K). Therefore, when the interval between the two optical input ports 11 is 0.5 mm, if the temperature of the light mixing element and the substrate 20 changes from 280°C to 25°C,

[0038] (7.2-4.5)×10 －6 ×0.5(mm)×(280-25)=-0.34(μm),

[0039] The interval between the two light input ports 11 is reduced by 34 μm. In addition, the heating for melting the first solder material 41 and the second solder material 42 is usually performed at a temperature higher than the melting point.

[0040] Here, if the difference in linear expansion coefficient is set to Δa, the interval between the two optical input ports 11 is set to L, the temperature difference between the melting point of the second solder material 42 and room temperature (25°C) is set to ΔT, and the amount of contraction of the interval between the two optical input ports 11 when the temperature drops from the melting point of the second solder material 42 to room temperature is set to ΔL, then ΔL is expressed by the following formula.

[0041] ΔL=Δa×L×ΔT

[0042] If the value of ΔL is large, the optical coupling between the two optical input ports 11 and the array lenses 6 and 7 may be degraded. For example, when one of the two lenses 6b is aligned with respect to one of the two optical input ports 11, if the interval between the two lenses 6b is set to be almost unaffected by the above-mentioned temperature change, the optical axis of the other of the two lenses 6b and the optical axis of the other of the two optical input ports 11 are offset from each other by ΔL, and the coupling efficiency of the optical coupling may be reduced. In contrast, the optical mixing element 10 and the substrate 20 involved in this embodiment can solve the above-mentioned problem. Regarding the optical coupling between the array lenses 6 and 7 and the optical mixing element 10, for example, the coupling loss can be made less than the allowable value of the coupling loss, i.e., -0.3 dB, relative to the temperature change for melting and solidifying the first solder material 41 and the second solder material 42.

[0043] Figure 5 2 is a plan view showing the substrate 20 when viewed from the side where the light mixing element 10 is located in the normal direction of the third surface 22 of the substrate 20. Figure 5 In FIG. 1 , the light mixing element 10 mounted on the substrate 20 is indicated by a dotted line. Figure 4 and Figure 5As shown, the length direction of the light mixing element 10 and the substrate 20 is set to the X direction (first direction), the width direction of the substrate 20 is set to the Y direction (second direction), and the thickness direction of the substrate 20 is set to the Z direction. The positional relationship of each part when observing from the normal direction (Z direction) of the fifth surface 13 of the light mixing element 10 is described. For example, the length of the light mixing element 10 in the X direction is greater than 2.0 mm and less than 5.0 mm. The width of the light mixing element 10 in the Y direction is greater than 1.0 mm and less than 3.0 mm. Figure 5 In the plan view shown, the first pattern 23 and the second pattern 24 are formed at positions separated from the 90° hybrid 15 included in the light mixing element 10 in the X direction.

[0044] The first pattern 23 is formed on one side of the 90° hybrid 15 in the X direction ( Figure 2 The second pattern 24 is formed on the other side (in the longitudinal direction (X direction) of the 90° hybrid 15) of the optical component 5 side. Figure 2 The first pattern 23 and the second pattern 24 are formed in such a manner that the 90° hybrid 15 is arranged between the first pattern 23 and the second pattern 24 in the longitudinal direction (X direction). As described above, when the first pattern 23 and the second pattern 24 of the substrate 20 are formed at a position separated from the 90° hybrid 15, it is possible to alleviate the residual stress on the 90° hybrid 15 caused by the temperature change accompanying the bonding of the light mixing element 10 with the first pattern 23 and the second pattern 24. If the distance in the X direction between the first pattern 23 and the 90° hybrid 15 is set as the distance X1, and the distance in the X direction between the 90° hybrid 15 and the second pattern 24 is set as the distance X2, the greater the values ​​of the distance X1 and the distance X2 become, the greater the effect of relieving the stress on the 90° hybrid 15 becomes. For example, the distance X1 and the distance X2 are preferably set to 0.2 mm or more.

[0045] When the substrate 20 is observed from the Z direction, the first pattern 23 is arranged between the two light input ports 11 in the Y direction (second direction). The two light input ports 11 are arranged in the Y direction, for example, the two light input ports 11 can be arranged at positions that are line-symmetrical to each other with respect to the reference line E of the light mixing element 10. The reference line E is an imaginary line that passes through the center of the light mixing element 10 in the Y direction and extends in the X direction. For example, the reference line E is the center line of the light mixing element 10 in the Y direction. In addition, the reference line E can also be a straight line (imaginary line) that extends in the X direction on the third surface 22 and intersects the first pattern and the second pattern. If the interval (pitch) between the two light input ports 11 arranged in the Y direction is set to P1 and the width of the first pattern 23 in the Y direction is set to W1, for example, the value of W1 is greater than 20% and less than 80% of the value of P1. As an example, the value of P1 is 0.5 mm, and the value of W1 is greater than 0.1 mm and less than 0.4 mm. In addition, from the viewpoint of suppressing the variation of the interval between the two optical input ports 11 due to the temperature change caused by the melting and solidification of the second solder material 42, it is preferable that the width W1 of the first pattern 23 in the Y direction is small. However, from the viewpoint of suppressing the warping in the Z direction that may occur in the optical input port 11, it is preferable that the width W1 of the first pattern 23 in the Y direction is not too small. For example, the thickness of the optical mixing element 10 is 50 μm or more and 200 μm or less. Since it is relatively thin, the optical mixing element 10 may be subjected to stress and warp in the Z direction due to temperature change. If a deviation occurs between the position (height) of the array lenses 6 and 7 in the Z direction from the first surface 31 and the position (height) of the optical input port 11 in the Z direction due to the above-mentioned warping, the coupling loss increases. Here, the inventors have found that the warping of the optical mixing element 10 is suppressed by configuring the first pattern 23 between the two optical input ports 11.

[0046] If the length of the first pattern 23 in the X direction is L1, the length L1 is determined by the distance X1 between the first pattern 23 and the 90° hybrid 15 and the position of the 90° hybrid 15 in the X direction of the optical mixing element 10. For example, the length L1 is greater than or equal to 0.3 mm and less than or equal to 0.6 mm. In addition, the optical input port 11 and the 90° hybrid 15 are connected via two optical waveguides 14. At the portion where the two optical waveguides 14 are connected to the 90° hybrid 15, the interval in the Y direction of the two optical waveguides 14 is smaller than the interval between the two optical input ports 11. Therefore, the two optical waveguides 14 approach each other as they move from the two optical input ports 11 toward the 90° hybrid 15. The length L1 of the first pattern 23 is set so that the first pattern 23 is separated from the portion of the two optical waveguides 14 that is bent so as to approach each other by a predetermined distance or more.

[0047] The second pattern 24 has, for example, a rectangular shape. The length (width) W2 of the second pattern 24 in the Y direction can be set to be larger than the length (width) W4 of the light mixing element 10 in the Y direction. When the substrate 20 is observed from the Z direction, the overlapping portion of the light mixing element 10 and the second pattern 24 is joined by the second solder material 42. The length L2 of the second pattern 24 in the X direction is determined by the distance X2 between the second pattern 24 and the 90° hybrid 15 and the position of the 90° hybrid 15 of the light mixing element 10 in the X direction. For example, the length L2 is greater than 0.3 mm. The length L2 can be set to less than 0.6 mm, for example, similarly to the length L1. In addition, when the substrate 20 is observed from the Z direction, the second pattern 24 only needs to have at least an area overlapping with the above-mentioned light mixing element 10, and the shape of the portion that does not overlap with the light mixing element 10 only needs to not extend to the vicinity of the edge of the substrate 20 in the Y direction. In addition, the shape of the portion of the second pattern 24 that does not overlap with the light mixing element 10 may not be a rectangular shape. For example, two sides of the second pattern 24 parallel to the X direction may be inclined in the X direction, and the second pattern 24 may have a trapezoidal shape including the two sides.

[0048] (Variation Example)

[0049] Next, a modification of the present embodiment will be described. In the modification of the present embodiment, the substrate 20 is replaced with a substrate 20A in the present embodiment described above. The difference between the substrate 20A and the substrate 20 is that the second pattern 24 is replaced with a second pattern 24A. In addition, the substrate 20A is also referred to as a support. The following mainly describes the differences from the present embodiment described above. Figure 6 As shown, the second pattern 24A of the substrate 20A has a "コ" shape when viewed from the Z direction, that is, Figure 2 The optical component 5 side of the second pattern 24A has a portion that does not overlap with the light mixing element 10. That is, the second pattern 24A has side portions S extending from both ends of the second pattern 24 in the Y direction toward the optical component 5 side in the X direction relative to the second pattern 24. In addition, the shape of the second solder material 42 formed on the second pattern 24 is a "コ" shape when viewed from the Z direction, that is, the side portion S also includes an overlapping area with respect to the light mixing element 10 described later.

[0050] The side portion S has an area (overlapping area) overlapping with the light mixing element 10 when the substrate 20A is observed from the Z direction. The overlapping area is bonded to the fourth surface 12 of the light mixing element 10 via the second solder material 42. Therefore, in the second pattern 24A, the portion overlapping with the light mixing element 10 when observed from the Z direction has a "コ" shape. The "コ"-shaped portion is bonded to the fourth surface 12 of the light mixing element 10 via the second solder material 42. The end Sa on the optical component 5 side of the side portion S extends to the position of the side of the amplifier 8 side of the first pattern 23 in the X direction, for example. When the substrate 20A is observed from the Z direction, the second pattern 24A includes a 90° hybrid 15 in the "コ"-shaped portion. The "コ"-shaped portion of the second pattern 24A is formed to surround the 90° hybrid 15 except for the direction in which the first pattern 23 exists. Therefore, the area of ​​the fourth surface 12 corresponding to the 90° hybrid 15 is not bonded to the second pattern 24A. The side portion S is separated from the 90° mixer 15 by a distance Y1 and a distance Y2 in the Y direction. For example, based on the reference line E, the side portion S is separated from the 90° mixer 15 by a distance Y1 in the -Y direction. In addition, based on the reference line E, the side portion S is separated from the 90° mixer 15 by a distance Y2 in the +Y direction. Alternatively, the side portion S is formed to be separated by a distance Y1 and a distance Y2 in the Y direction and the 90° mixer 15 is sandwiched therein. The greater the values ​​of the distance Y1 and the distance Y2 become, the greater the effect of stress relaxation to the 90° mixer 15 becomes. For example, the distance Y1 and the distance Y2 are preferably set to be more than 0.2 mm. The length of the distance Y1 can be set to the same value as the length of the distance Y2.

[0051] Figure 7 1 is a diagram showing the relationship between the length of the side portion S of the second pattern 24A of the substrate 20A and the amount of change in the interval (pitch) between the light input ports 11 due to temperature change. Figure 7 The results are based on a simulation of the variation in the interval (pitch) between the two light input ports 11 corresponding to the above-mentioned temperature change (hereinafter referred to as pitch variation) in a state where the light mixing element 10 is fixed to the third surface 22 of the substrate 20A via the second solder material 42 . Figure 7 The horizontal axis of the graph represents the length Ls from the end of the substrate 20A on the optical component 5 side to the end Sa of the second pattern 24A in the X direction. The length Ls is, for example, equal to the distance between the two optical input ports 11 and the end Sa of the side S of the second pattern 24A in the length direction (X direction). In addition, the length L3 of the side S becomes the longest when the length Ls is set to 0. On the other hand, if the length Ls is gradually increased and the length Ls reaches the maximum value, the length L3 of the side S becomes 0 (when the length L3 is 0, the second pattern 24A becomes the same as the second pattern 24). Figure 7The vertical axis of the graph represents the spacing variation ΔP1 of the two optical input ports 11. The spacing variation ΔP1=0 means that the spacing P1 does not change when the temperature of the substrate 20A changes from 280°C to room temperature (25°C). The lower side compared to ΔP1=0 indicates that ΔP1 becomes a negative value, and the spacing P1 becomes smaller or narrower relative to the temperature change. The upper side compared to ΔP1=0 indicates that ΔP1 becomes a positive value, and the spacing P1 becomes larger or wider relative to the temperature change. The spacing variation ΔP1 preferably has the smaller absolute value. Curve A shows the result when the substrate 20A is bonded to the fourth surface 12 of the light mixing element 10 through the first pattern 23 and the second pattern 24A. Curve B shows the result when the first pattern 23 is removed from the substrate 20A and only the second pattern 24A is bonded to the fourth surface 12 of the light mixing element 10 (comparative example). In addition, when viewed from the Z direction, the side portion S has an area overlapping with the light mixing element 10. The shape of the overlapping area between the second pattern 24A and the light mixing element 10 is a U-shape that is open on the light input port 11 side. Therefore, the shape of the second solder material 42 formed on the second pattern 24 is formed in a U-shape so as to include the overlapping area of ​​the U-shape. For example, the length (width) W3 in the Y direction of the second solder material 42 formed on the second pattern 24 is greater than the length (width) W4 in the Y direction of the light mixing element 10. In addition, the width W3 is smaller than the length (width) W2 in the Y direction of the second pattern 24A. In addition, the length (width) in the Y direction of the overlapping area between the side portion S and the light mixing element 10 can be, for example, 50 μm or more.

[0052] Both curve A and curve B show that the spacing variation ΔP1 will change if the length Ls is changed. The reason is that if the length L3 of the side S joined to the optical mixing element 10 is changed, the residual stress on the optical input port 11 will change due to the temperature change. For both curve A and curve B, if the length Ls gradually increases from 0, the spacing variation ΔP1 will temporarily increase, and if the length Ls is greater than the length L1 of the first pattern 23, the spacing variation ΔP1 will decrease. Curve B shows that ΔP1 is a positive value and does not change. If the length Ls is set to the maximum, ΔP=0. The reason is that the optical component 5 side of the optical mixing element 10 is not joined to the substrate 20A, and is in a hollow floating state, so it is not affected by the residual stress. However, in this state, the optical mixing element 10 is not firmly fixed to the substrate 20A, so it cannot actually be set to this state. Curve A is generally on the negative side compared to curve B. In curve A, if the length Ls is gradually reduced from the maximum value (equivalent to the case where there is no side S), the spacing variation ΔP1 gradually approaches 0 and the absolute value becomes smaller. If the length Ls is set to a value near the length L1 of the first pattern 23, the spacing variation ΔP1 can be set to 0. Therefore, by setting the length L3 of the side S to an appropriate size, the spacing variation ΔP1 can be suppressed from being minimized. For example, by adjusting the size of the length Ls within the range of 0.5 to 1.5 times the length L1 in the length direction (X direction) of the first pattern 23, the absolute value of the spacing variation ΔP1 can be reduced.

[0053] Next, the effects obtained from the optical module 1 involved in this embodiment are described in detail. In the optical module 1, the second surface 21 of the substrate 20 is placed on the planar first surface 31 of the base 30, and the fourth surface 12 of the optical mixing element 10 is placed on the third surface 22 on the opposite side of the second surface 21 of the substrate 20. A first metal pattern 23 is formed on the third surface 22 of the substrate 20, and the first pattern 23 is bonded to the fourth surface 12 of the optical mixing element 10 through a second solder material 42. The optical mixing element 10 has two optical input ports 11 arranged in the Y direction, and the two optical input ports 11 are optically coupled to each lens 6b, 7b of the array lens 6, 7 fixed to the first surface 31 of the base 30. Here, optical coupling means the following state, that is, for example, light incident from the optical component 5 side of the lens 6b is focused on the optical input port 11 by the lens 6b, and the intensity of the light input to the optical input port becomes a predetermined value or more relative to the intensity of the light incident from the optical component 5 side of the lens 6b. The ratio (proportion) of the intensity of light input to the optical input port to the intensity of light incident from the optical component 5 side of the lens 6b is represented by, for example, coupling efficiency. The greater the coupling efficiency, the smaller the loss (coupling loss), so it is preferred that the coupling efficiency has a large value. By obtaining optical coupling as desired, the optical signal is properly transmitted inside the optical module 1, and the optical module 1 can exert the prescribed function and performance.

[0054] When viewed from the Z direction, which is the normal direction of the fifth surface 13 of the light mixing element 10, the first pattern 23 and the second solder material 42 formed on the first pattern 23 are arranged on the inner side of the two light input ports 11 in the Y direction. The fourth surface 12 of the light mixing element 10 is bonded to the first pattern 23 of the third surface by the melting and solidification of the second solder material 42. Therefore, the substrate 20 and the light mixing element 10 are fixed at the first pattern 23 on the inner side of the two light input ports 11 when viewed from the Z direction. Thus, the area of ​​the second solder material 42 included in the first pattern 23 is located on the inner side of the two light input ports 11 when viewed from the Z direction. By providing the first pattern 23 as described above, it is possible to suppress the interval between the two light input ports 11 from changing when the temperature changes due to the heating and cooling of the second solder material 42. Therefore, when the lenses 6b and 7b of the array lenses 6 and 7 are aligned with respect to the two optical input ports, the optical axis of each lens 6b and 7b is prevented from being offset from the optical axis of each optical input port 11, thereby reducing the optical coupling loss. As a result, the optical coupling and optical characteristics of the optical module 1 accompanying temperature changes can be stabilized.

[0055] In addition, as described above, the thickness of the base 30 is, for example, not less than 1.0 mm and not more than 2.0 mm. It is thicker than the thickness of the optical mixing element 10 and the thickness of the substrate 20. Therefore, for example, when the substrate 20 is joined to the first surface 31 of the base 30 via the first solder material 41, the base 30 is subjected to temperature changes in order to melt and solidify the first solder material 41. However, since the base 30 is thick, it is difficult to cause warping, and the position change in the Z direction of the two lenses 6b and 7b in the array lenses 6 and 7 respectively accompanying the temperature change is small enough to be ignored. Therefore, by suppressing the shrinkage of the distance between the two optical input ports 11 caused by the temperature change, the optical coupling between the array lenses 6 and 7 and the optical input port 11 of the optical mixing element 10 is stabilized.

[0056] In addition, in the optical module 1 of the embodiment (example) in which the distance (pitch P1) between the two optical input ports 11 is set to 0.5 mm and the first pattern 23 is arranged on the inner side of the two optical input ports 11, a simulation of applying a temperature change from 280° C. to 25° C. is performed when the material of the substrate 20 is set to aluminum nitride. As a result, in the embodiment, the shrinkage of the interval between the two optical input ports 11 is suppressed to 0.2 μm or less. As described above, the shrinkage amount of the interval between the two optical input ports 11 can be reduced.

[0057] The distance between the second surface 21 and the third surface 22 of the substrate 20 (the thickness of the substrate 20 in the Z direction) is 300 μm or more and 600 μm or less. The distance between the fourth surface 12 and the fifth surface 13 of the light mixing element 10 (the thickness of the light mixing element 10 in the Z direction) is 50 μm or more and 200 μm or less. The width W of the first pattern 23 in the Y direction may be 20% or more and 80% or less of the distance (pitch P1) between the two light input ports 11. In this case, the width W of the first pattern 23 is 80% or less of the distance between the two light input ports 11, thereby more reliably reducing the variation in the pitch between the two light input ports 11 in the Y direction due to temperature changes. In addition, the width W of the first pattern 23 is 20% or more of the distance between the two light input ports 11, thereby more reliably reducing the warping (position change in the Z direction) of the light mixing element 10 caused by temperature changes. By suppressing the warping of the light mixing element 10 , it is possible to suppress the displacement of the positions of the two light input ports 11 in the Z direction relative to the lenses 6 b and 7 b , thereby stabilizing the optical coupling between the two light input ports 11 and the lenses 6 b and 7 b .

[0058] In addition, the material of the substrate 20 may include aluminum nitride. The material of the second solder material 42 may include gold tin. The material of the optical mixing element 10 may include indium phosphide. In this case, the material of the substrate 20 includes aluminum nitride, thereby improving the thermal conductivity of the substrate 20 and improving the heat dissipation performance of the substrate 20. In addition, the material of the second solder material 42 includes gold tin, thereby improving the reliability of bonding.

[0059] In addition, the optical module involved in the modified example has a substrate 20A, which forms a second pattern 24A having a "コ" shape. When viewed from the Z direction, the second pattern 24A includes a 90° hybrid 15 on the inner side of the "コ" portion. The "コ" portion of the second pattern 24A is formed to surround the 90° hybrid 15 except for the direction in which the first pattern 23 exists. The second pattern 24A has a side S extending in the Y direction relative to the second pattern 24. When the substrate 20A is viewed from the Z direction, the side S and the optical mixing element 10 have an overlapping area. The overlapping area of ​​the optical mixing element 10 is connected to the side S by the second solder material 42, thereby being more reliably fixed to the substrate 20. The length (width) of the overlapping area of ​​the side S and the optical mixing element 10 in the Y direction can be set to 50μm or more, for example. As described above, by arranging the second pattern 24A so as to surround the 90° hybrid 15 , it is possible to more effectively relax the residual stress on the 90° hybrid 15 caused by the temperature change of the second solder material 42 due to heating and cooling.

[0060] Above, the embodiment of the optical module involved in the present invention is described. However, the present invention is not limited to the aforementioned embodiment. That is, the present invention can be variously deformed and changed within the scope of the subject matter recorded in the claims, which is easy for a person skilled in the art to know. For example, in the aforementioned embodiment, an example in which the substrate 20 has two patterns, the first pattern 23 and the second pattern 24, is described. However, the style of the pattern formed on the substrate is not limited to the first pattern 23 and the second pattern 24, and can be appropriately changed. In addition, the structure of each optical component of the optical component 5 can also be appropriately changed. Moreover, in the aforementioned embodiment, an optical module 1 in which P1 is 0.5 mm, W is greater than 0.1 mm and less than 0.4 mm, and the length L1 is greater than 0.3 mm and less than 0.6 mm is described. However, the size, shape, material and configuration of each part of the optical module can be appropriately changed.

[0061] Description of the label

[0062] 1...optical module,

[0063] 2…Package,

[0064] 2b…one end face,

[0065] 3…Signal optical input port,

[0066] 4…Local oscillator optical input port,

[0067] 5…Optical components,

[0068] 6 ... a first array lens (array lens),

[0069] 6b, 7b… lenses,

[0070] 7... a second array lens (array lens),

[0071] 8…Amplifier,

[0072] 9…terminal,

[0073] 10... optical hybrid components (optical circuit components),

[0074] 11...Optical input port (port),

[0075] 12…The fourth side,

[0076] 13…Page 5,

[0077] 14…Optical waveguide,

[0078] 15…90° mixer,

[0079] 20, 20A...Substrate,

[0080] 21…side 2,

[0081] 22…side three,

[0082] 23…The first pattern,

[0083] 24, 24A…the second pattern,

[0084] 30…base,

[0085] 31…side one,

[0086] 41 ... a first solder material,

[0087] 42 ... a second solder material,

[0088] S…side,

[0089] E…baseline,

[0090] W1, W2, W3, W4...width,

[0091] X1…distance,

[0092] X2…distance.

Claims

1. An optical module, comprising: a base having a first surface; a substrate having a flat plate-like shape extending in a first direction, and having a second surface and a third surface located on an opposite side of the second surface; an optical circuit element having a flat plate-like shape extending in the first direction, having a fourth surface and a fifth surface located on the opposite side of the fourth surface, and having two ports arranged in a second direction intersecting the first direction at one end of the fifth surface in the first direction; as well as An array lens having two lenses arranged along the second direction, The first surface of the base is bonded to the second surface of the substrate via a first solder material. The third surface of the substrate includes a first pattern and a second pattern made of metal arranged along the first direction. The first pattern and the second pattern are bonded to the fourth surface of the optical circuit element via a second solder material. The array lens is fixed to the first surface of the base so that one of the two lenses is optically coupled to one of the two ports of the optical circuit element, and the other of the two lenses is optically coupled to the other of the two ports of the optical circuit element. When the two ports, the first pattern, and the second pattern are observed from the normal direction of the fifth surface, the first pattern is arranged closer to the one end of the optical circuit element than the second pattern in the first direction, and is arranged between the two ports in the second direction.

2. The optical module according to claim 1, wherein: When the substrate and the optical circuit element are viewed from the normal direction, the optical circuit element is included inside the substrate.

3. The optical module according to claim 1 or 2, wherein: The distance between the second surface and the third surface of the substrate is greater than or equal to 300 μm and less than or equal to 600 μm, The distance between the fourth surface and the fifth surface of the optical circuit element is greater than or equal to 50 μm and less than or equal to 200 μm. The width of the first pattern in the second direction is not less than 20% and not more than 80% of the distance between the two ports.

4. The optical module according to any one of claims 1 to 3, wherein: The imaginary line is a straight line extending along the first direction on the third surface, intersecting the first pattern and the second pattern, when viewed from above in the normal direction. The length of the portion where the imaginary line intersects the first pattern is greater than or equal to 0.3 mm and less than or equal to 0.6 mm, The length of a portion where the imaginary line intersects the second pattern is greater than or equal to 0.3 mm and less than or equal to 0.6 mm.

5. The optical module according to any one of claims 1 to 4, wherein: The material of the substrate comprises aluminum nitride, The first solder material and the second solder material each include gold tin, The optical circuit element includes indium phosphide.

6. The optical module according to any one of claims 1 to 3, wherein: The second pattern further has a side portion, which extends from both ends of the second pattern in the second direction toward the first pattern along the first direction. When the optical circuit element and the substrate are observed from the normal direction, the side portion has an overlapping region overlapping with the optical circuit element, The second solder material is formed to include the overlapping area on the second pattern.

7. The optical module according to claim 6, wherein: A distance Ls between the side portion and the two ports in the first direction is a value larger than 0.5×L1 and smaller than 1.5×L1, when the length of the first pattern in the first direction is defined as L1.

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