Optical module and opto-electric substrate

Abstract

To provide an optical module and an opto-electric substrate that enable optical ICs to be highly densely mounted.SOLUTION: An optical module according to one embodiment comprises: an opto-electric substrate that has a first surface, a first recessed part opened to the first surface, a first waveguide extending toward the first recessed part, and a first mirror formed inside the first recessed part and reflecting signal light propagating through the first waveguide; and an optical IC that has a circuit surface facing the first surface, a second waveguide formed in the circuit surface, a second recessed part opened to the circuit surface, and a second mirror formed inside the second recessed part and reflecting signal light propagating through the second waveguide, and that is connected to the opto-electric substrate while the circuit surface faces the first surface. The first waveguide and the second waveguide are optically coupled to each other through the first mirror and the second mirror.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to an optical module and an optoelectronic substrate.

Background Art

[0002] Patent Document 1 describes an optoelectronic assembly including an optoelectronic substrate on which an optical connector and an optical IC are mounted. The optoelectronic substrate has a glass optical waveguide extending from the optical connector to an overlapping region. The optical IC has a waveguide region extending from the overlapping region to a photoelectric conversion section. The optoelectronic substrate has a rewiring layer electrically connected to the photoelectric conversion section and a conductive via extending downward from the rewiring layer. The glass optical waveguide of the optoelectronic substrate and the waveguide region of the optical IC are optically coupled to each other in the overlapping region.

[0003] Patent Document 2 describes a substrate for mounting optical components including a glass substrate. The substrate for mounting optical components is mounted on a printed circuit board and converts an electrical signal from the printed circuit board into an optical signal. Via holes are formed in the glass substrate and filled with resin. A lower cladding, a core, and a photoresist are applied to the glass substrate, and the photoresist is exposed and developed using a waveguide pattern mask. Then, the core is patterned so that its cross-section becomes rectangular by reactive ion etching, and then the photoresist is removed. A mirror is formed at a predetermined location of the core, and an upper cladding and an optical wiring layer are formed on the core in this order. The mirror is formed by processing the core at an angle of 45° with a laser or the like.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in an optical module including an optoelectronic substrate such as a glass substrate, a long optical path length may be required to suppress the loss of optical coupling. For example, there is optical coupling by evanescent coupling where a long optical path length is required. In this case, there is a concern about the increase in size of the optical module and the optoelectronic substrate. Therefore, it is required to be able to mount optical ICs mounted on the optoelectronic substrate at high density to realize miniaturization of the optical module and the optoelectronic substrate.

[0006] An object of the present disclosure is to provide an optical module and an optoelectronic substrate capable of high-density mounting of an optical IC and reduction of optical coupling loss.

Means for Solving the Problems

[0007] The optical module according to the present disclosure includes an optoelectronic substrate having a first surface, a first recess opening to the first surface, a first waveguide extending toward the first recess, and a first mirror formed in the first recess and reflecting signal light propagating through the first waveguide, a circuit surface facing the first surface, a second waveguide formed on the circuit surface, a second recess opening to the circuit surface, and a second mirror formed in the second recess and reflecting signal light propagating through the second waveguide, and an optical IC having the circuit surface facing the first surface and connected to the optoelectronic substrate. The first waveguide and the second waveguide are optically coupled to each other via the first mirror and the second mirror.

Effects of the Invention

[0008] According to the present disclosure, an optical IC can be mounted at high density and the loss of optical coupling can be reduced.

Brief Description of the Drawings

[0009]

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DETAILED DESCRIPTION OF THE INVENTION

[0010] [Description of Embodiments of the Present Disclosure] First, embodiments of the optical module and the optoelectronic substrate according to the present disclosure will be listed and described. (1) An optical module according to an embodiment includes a first surface, a first recess opening in the first surface, a first waveguide extending toward the first recess, a first mirror formed in the first recess and reflecting signal light propagating through the first waveguide, an optoelectronic substrate having a first mirror, a circuit surface facing the first surface, a second waveguide formed on the circuit surface, a second recess opening in the circuit surface, a second mirror formed in the second recess and reflecting signal light propagating through the second waveguide, and an optical IC having a circuit surface facing the first surface and connected to the optoelectronic substrate. The first waveguide and the second waveguide are optically coupled to each other via the first mirror and the second mirror.

[0011] (7) The optoelectronic substrate according to one embodiment is an optoelectronic substrate connected to an optical IC. The optoelectronic substrate includes a first surface facing the circuit surface of the optical IC, a first recess opening in the first surface, a first waveguide extending toward the first recess, and a first mirror formed in the first recess and reflecting signal light propagating through the first waveguide.

[0012] (8) The optoelectronic substrate according to another embodiment has a first surface and a second surface opposite to the first surface. The optoelectronic substrate includes a first glass substrate having the first surface and a second glass substrate having the second surface. The first glass substrate has a first recess opening in the first surface, a first waveguide extending toward the first recess, a first mirror formed in the first recess and reflecting signal light propagating through the first waveguide, and a first terminal formed on the first surface. The second glass substrate has a second terminal formed on the second surface. Wiring for electrically connecting the first terminal and the second terminal to each other is formed in the first glass substrate and the second glass substrate.

[0013] The optoelectronic substrate of this optical module has a first surface facing the circuit surface of the optical IC, and a first recess is formed in the first surface. The optoelectronic substrate has a first waveguide, and the first waveguide extends toward the first recess. A first mirror is formed in the first recess, and the first mirror reflects signal light propagating through the first waveguide. By arranging the first mirror in the first recess in which the first waveguide extends and reflecting the signal light propagating through the first waveguide by the first mirror, the optical path of the signal light can be made compact. Therefore, the optical IC mounted on the optoelectronic substrate can be mounted at high density, and miniaturization of the optical module and the optoelectronic substrate can be realized.

[0014] (2) In the above (1), the optoelectronic substrate may be configured by laminating a plurality of glass substrates. The first surface may be the upper surface of the uppermost glass substrate among the plurality of glass substrates, and the first waveguide may be formed on the uppermost glass substrate. In this case, when the optoelectronic substrate is mounted on the wiring substrate, it is possible to easily match the pitch of the electrodes on the wiring substrate to the pitch of the electrodes in the optical IC between the plurality of glass substrates. Further, when a plurality of glass substrates are laminated, it is possible to make it difficult for the upper surface of the uppermost glass substrate, which is the first surface, to warp. Therefore, the mounting of the optical IC on the optoelectronic substrate can be easily performed.

[0015] (3) In the above (1) or (2), signal light may be output from the first waveguide into the first recess, and the signal light may be reflected by the first mirror toward the optical IC. The second mirror may reflect the signal light reflected by the first mirror toward the second waveguide. In this case, the signal light propagating through the first waveguide of the optoelectronic substrate can be reflected toward the optical IC by the first mirror disposed in the first recess. Then, by reflecting the signal light reflected by the first mirror by the second mirror onto the second waveguide of the optical IC, the first waveguide can be optically coupled to the second waveguide.

[0016] (4) In the above (3), the second mirror may reflect the signal light so that the direction of the signal light propagating through the second waveguide is the same as the direction of the signal light propagating through the first waveguide.

[0017] (5) In any of the above (1) to (4), the optoelectronic substrate may have an end face intersecting the first surface, and the first waveguide may extend from the end face toward the first recess. The optical module may further include an optical fiber connected to the end face and optically coupled to the first waveguide. In this case, the optical fiber located outside the optoelectronic substrate can be optically coupled to the first waveguide.

[0018] (6) In any of (1) to (5) above, the optoelectronic substrate may have a plurality of first recesses, a plurality of first waveguides extending toward each of the plurality of first recesses, and a plurality of first mirrors formed inside each of the plurality of first recesses. The optical IC may have a plurality of second recesses, a second waveguide extending between the plurality of second recesses, and a plurality of second mirrors formed inside each of the plurality of second recesses. The plurality of first waveguides may be optically coupled to each other via the plurality of first mirrors, the plurality of second mirrors, and the second waveguide.

[0019] [Details of Embodiments of the Present Disclosure] Specific examples of the optical module and the optoelectronic substrate according to the embodiment will be described below with reference to the drawings. Note that the present invention is not limited to the following examples, and is intended to include all modifications within the scope shown in the claims and within the scope equivalent to the claims. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and overlapping descriptions are omitted as appropriate. The drawings may be drawn with some parts simplified or exaggerated for ease of understanding, and the dimensional ratios and the like are not limited to those described in the drawings.

[0020] FIG. 1 is a cross-sectional view showing an optical module 1 according to the present embodiment. FIG. 2 is a plan view showing the optical module 1. As shown in FIGS. 1 and 2, the optical module 1 includes an optoelectronic substrate 2 and an optical IC (integrated circuit) 3. The optical module 1 is, for example, a switch circuit module with optical signal input and output. For example, the optical module 1 is a switch circuit module for Ethernet signals.

[0021] The optoelectronic substrate 2 has a first surface 2b extending in both the first direction D1 and the second direction D2, and a second surface 2c facing opposite to the first surface 2b and extending in both the first direction D1 and the second direction D2. The optoelectronic substrate 2 is composed of a plurality of glass substrates 2G laminated together. The plurality of glass substrates 2G are laminated, for example, by an adhesive (not shown). For example, the optoelectronic substrate 2 has three glass substrates 2G1, 2G2, and 2G3. The optoelectronic substrate 2 formed by laminating a plurality of glass substrates 2G is, for example, a glass interposer. The glass substrate 2G extends in the first direction D1 and in the second direction D2 intersecting the first direction D1. The glass substrate 2G has a thickness in a third direction D3 intersecting both the first direction D1 and the second direction D2. The glass substrate 2G may be composed of, for example, any one of borosilicate glass, alkali-free glass, aluminosilicate glass, crystallized glass, fused silica glass, and soda-lime glass (soda lime glass).

[0022] For example, the main component of the glass constituting the glass substrate 2G is silicon dioxide (SiO2). The glass substrate 2G may be a composition containing at least any one of boron oxide (B2O3), alumina (Al2O3), sodium (Na), and calcium (Ca). The linear expansion coefficient of the glass substrate 2G is, for example, 3 to 5 [ppm / K]. However, the linear expansion coefficient of the glass substrate 2G can be made 1 [ppm / K] or less, or about 10 [ppm / K] or more by adjusting the composition of the material constituting the glass.

[0023] The glass substrate 2G has a via 2d extending in the third direction D3 and penetrating the glass substrate 2G. The via 2d is also referred to as a TGV (Through Glass Via). The via 2d has, for example, a cylindrical shape. The glass substrate 2G has a plurality of vias 2d. The plurality of vias 2d are arranged, for example, along each of the first direction D1 and the second direction D2. For example, in a plan view of the optoelectronic substrate 2, the vias 2d may be two-dimensionally arranged at a constant pitch.

[0024] The via 2d is filled with, for example, a metal (also referred to as a field via). As a specific example, the via 2d is filled with copper (Cu). However, the via 2d may not be completely filled with the metal. For example, the via 2d may have a metal film formed only on the sidewall surface and a cavity in the center (also referred to as a conformal via).

[0025] The optoelectronic substrate 2 has, for example, an electrical wiring 2f formed on the first surface 2b, an electrical wiring 2x formed between the glass substrate 2G1 and the glass substrate 2G2, an electrical wiring 2y formed between the glass substrate 2G2 and the glass substrate 2G3, and an electrical wiring 2g formed on the second surface 2c. The electrical wirings 2f, 2g, 2x, 2y are, for example, thin films made of copper. The surfaces of the electrical wirings 2f, 2g, 2x, 2y may be plated with gold (Au). Also, nickel (Ni) or palladium (Pd) may be plated between the gold plating and the copper to form. The electrical wirings 2f, 2g, 2x, 2y can also be used as electrodes or pads. The electrical wiring 2f and the electrical wiring 2x are electrically connected to each other through the via 2d of the glass substrate 2G1. The electrical wiring 2x and the electrical wiring 2y are electrically connected to each other through the via 2d of the glass substrate 2G2. The electrical wiring 2y and the electrical wiring 2g are electrically connected to each other through the via 2d of the glass substrate 2G3.

[0026] The optoelectronic substrate 2 has a first surface 2b and a second surface 2c opposite to the first surface 2b. For example, the glass substrate 2G1 (first glass substrate) has the first surface 2b, and the glass substrate 2G3 (second glass substrate) has the second surface 2c. The glass substrate 2G1 has a first recess 2h opening to the first surface 2b, a first waveguide 2j extending toward the first recess 2h, a first mirror 2k formed in the first recess 2h and reflecting the signal light L propagating through the first waveguide 2j, and a terminal 7 (first terminal) formed on the first surface 2b. The glass substrate 2G3 has a terminal 4 (second terminal) formed on the second surface 2c. The glass substrate 2G1 and the glass substrate 2G3 are formed with wirings for electrically connecting the terminal 4 and the terminal 7 to each other. As shown in FIG. 1, the optoelectronic substrate 2 may further have a glass substrate 2G2 between the glass substrate 2G1 and the glass substrate 2G3. For example, the glass substrate 2G2 is adhered onto the glass substrate 2G3, and the glass substrate 2G1 is adhered onto the glass substrate 2G2. Thus, the glass substrates 2G1, 2G2, and 2G3 are laminated along the third direction D3. The third direction D3 is also referred to as the lamination direction. The lamination direction may coincide with the normal direction of the first surface 2b and the second surface 2c. In the optoelectronic substrate 2 shown in FIG. 1, the wirings for electrically connecting the terminal 4 and the terminal 7 to each other are constituted by, for example, the above-described electrical wirings 2f, 2g, 2x, 2y, and the via 2d. For example, when the optoelectronic substrate 2 does not include the glass substrate 2G2, the electrical wiring 2x and the electrical wiring 2y may be merged with each other. As the number (number of layers) of the plurality of glass substrates included in the optoelectronic substrate 2 increases, the three-dimensional intersection of the plurality of wirings formed inside becomes easier, and the degree of freedom of the wirings is improved, and the integration density of the wirings can be improved.

[0027] The optical module 1 is, for example, surface-mounted on an external wiring substrate 100. In the following description, the direction in which the optical module 1 is provided as viewed from the wiring substrate 100 may be referred to as up, upper side, or upward, and the direction in which the wiring substrate 100 is provided as viewed from the optical module 1 may be referred to as down, lower side, or downward. However, these directions are for convenience of explanation and do not limit the arrangement position or direction of an object.

[0028] For example, the optical module 1 has terminals 4 for external connection. The terminals 4 are provided on the second surface 2c of the optoelectronic substrate 2. The terminals 4 are solder balls having a spherical shape. As an example, the terminals 4 are Sn-Ag-Cu alloy-based solder. The terminals 4 are connected to the electrical wiring 2g formed on the second surface 2c of the optoelectronic substrate 2. The optical module 1 has a plurality of terminals 4. For example, the plurality of terminals 4 are arranged along the first direction D1 and the second direction D2. The terminals 4 may be arranged in an array. The arrangement interval (pitch) of the terminals 4 arranged in an array is, for example, 0.5 mm. For example, the plurality of terminals 4 constitute a BGA (Ball Grid Array). The terminals 4 are interposed between the optoelectronic substrate 2 and the wiring substrate 100. The terminals 4 electrically connect the electrical wiring of the wiring substrate 100 and the electrical wiring 2g of the optoelectronic substrate 2 to each other.

[0029] For example, the optical module 1 includes a plurality of integrated circuits 10 mounted on the optoelectronic substrate 2. In the present embodiment, the plurality of integrated circuits 10 are at least one optical IC 3, at least one electrical IC 5, and at least one LSI (Large-Scale Integration) 6. In plan view (when viewed along the third direction D3), the plurality of electrical ICs 5 are arranged so as to surround the LSI 6, and the plurality of optical ICs 3 are arranged so as to surround the plurality of electrical ICs 5.

[0030] The optical IC 3 is, for example, a modulator or a photodiode. The electrical IC 5 is, for example, a driver or a TIA (Trans Impedance Amplifier). The electrical IC 5 is, for example, a front-end IC for the optical IC 3. When the electrical IC 5 is a driver, the electrical IC 5 drives, for example, the optical IC 3 which is a modulator. When the electrical IC 5 is a TIA, the electrical IC 5 converts the output current of the optical IC 3 which is a photodiode into a voltage and amplifies it. The LSI 6 is, for example, an Ethernet switch. A plurality of integrated circuits 10 are flip-chip mounted on the optoelectronic substrate 2. That is, the integrated circuit 10 is mounted in a state where its circuit surface is directed toward the optoelectronic substrate 2. Note that the type of the integrated circuit 10 is not limited to the electrical IC 5 and the LSI 6 described above, and can be changed as appropriate. The electrical IC 5 is interposed between the optical IC 3 and the LSI 6. The electrical IC 5 can be omitted, for example, when the LSI 6 includes the function of the electrical IC 5, or when the optical IC 3 includes the function of the electrical IC 5.

[0031] The optical module 1 has an underfill resin 8 filled between the optoelectronic substrate 2 and the integrated circuit 10. For example, the underfill resin 8 contains a filler. The underfill resin 8 is filled in the region between the optoelectronic substrate 2 and the integrated circuit 10 by capillary action. The underfill resin 8 stops in front of the first recess 2h of the optoelectronic substrate 2 and the second recess 3c of the optical IC 3, which will be described later, due to surface tension. Note that the underfill resin 8 can also be omitted.

[0032] The optical module 1 has terminals 7 for electrically connecting the integrated circuit 10 to the optoelectronic substrate 2. The terminals 7 are provided on the first surface 2b of the optoelectronic substrate 2. The terminals 7 are solder balls having a spherical shape. The terminals 7 may be made of a Su-Ag-Cu alloy-based solder, similar to the terminals 4. The terminals 7 are connected to the electrical wiring 2f formed on the first surface 2b of the optoelectronic substrate 2. The optical module 1 may have a plurality of terminals 7. The terminals 7 may be arranged in an array. The arrangement interval of the terminals 7 arranged in an array is, for example, 0.1 mm.

[0033] For example, the arrangement interval of terminals 4 is larger than that of terminals 7. Accordingly, in a plurality of glass substrates 2G, the arrangement intervals of vias 2d are different from each other. Specifically, the arrangement interval of vias 2d in the glass substrate 2G3 close to terminal 4 (for example, adjacent to the wiring substrate 100) is larger than the arrangement interval of vias 2d in the glass substrate 2G1 close to terminal 7 (for example, adjacent to the integrated circuit 10). The arrangement interval of vias 2d in the lowermost glass substrate 2G3 is larger than the arrangement interval of vias 2d in the second glass substrate 2G2 from the bottom. The arrangement interval of vias 2d in the uppermost glass substrate 2G1 is smaller than the arrangement interval of vias 2d in the second glass substrate 2G2 from the top. Thus, by including a plurality of glass substrates 2G, the optoelectronic substrate 2 can easily match the pitch of terminal 4 in the wiring substrate 100 to the pitch of terminal 7 in the integrated circuit 10.

[0034] The optoelectronic substrate 2 has a first recess 2h that opens to the first surface 2b, a first waveguide 2j that extends toward the first recess 2h, and a first mirror 2k that is formed in the first recess 2h and reflects the signal light L input to and output from the first waveguide 2j. For example, the signal light L transmitted through the first waveguide 2j is output from the end face of the first waveguide 2j and reflected by the first mirror 2k. Alternatively, the signal light L reflected by the first mirror 2k is input to the end face of the first waveguide 2j and transmitted through the first waveguide 2j. Thus, input and output do not necessarily need to be performed simultaneously and in parallel, and at least one of input and output may be performed. For example, the optoelectronic substrate 2 has a plurality of first recesses 2h arranged along the first direction D1, a plurality of first waveguides 2j arranged along the first direction D1, and a plurality of first mirrors 2k arranged along the first direction D1. For example, the first surface 2b is the upper surface of the uppermost glass substrate 2G1 among the plurality of glass substrates 2G, and the first waveguide 2j is formed in the uppermost glass substrate 2G1.

[0035] The optoelectronic substrate 2 has an end face 2p that intersects the first face 2b. The end face 2p extends in both the second direction D2 and the third direction D3 at the end of the optoelectronic substrate 2 in the first direction D1. The first waveguide 2j extends from the end face 2p toward the first recess 2h. That is, the first waveguide 2j extends from the end face 2p to the inner surface 2h1 (see FIG. 3) of the first recess 2h. The first waveguide 2j is a glass waveguide. There may be a distance between the end of the first waveguide 2j and the inner surface 2h1 of the first recess 2h. The distance between the end of the first waveguide 2j and the inner surface 2h1 of the first recess 2h is, for example, 0.1 mm. Further, the first waveguide 2j, which is a glass waveguide, is formed at a position, for example, 100 μm deep from the surface (first face 2b) of the glass substrate 2G1. When an electrical wiring 2f described later is formed on the surface of the glass substrate 2G1, it becomes easy to suppress an increase in the waveguide loss of the first waveguide 2j as compared with the case where the first waveguide 2j is formed on the surface of the glass substrate 2G1. Thereby, it is possible to improve the design freedom of the electrical wiring 2f. The depth at which the first waveguide 2j is formed is, for example, in the range of 50 μm or more and 200 μm or less from the surface of the glass substrate 2G1.

[0036] For example, the optical module 1 includes an optical fiber 9 and an optical fiber array 11 that holds the optical fiber 9. The optical fiber array 11 holds a plurality of optical fibers 9. For example, the optical fiber array 11 may include a V-groove substrate in which a plurality of V-grooves on which the respective optical fibers 9 are placed are formed, and a lid that covers the V-groove substrate. Further, the optical fiber array 11 may be a ferrule having a plurality of optical fiber holding holes through which the respective optical fibers 9 pass.

[0037] As an example, the optical fiber 9 is a single-core single-mode fiber. The optical fiber 9 may be, for example, a polarization-maintaining fiber. However, the optical fiber 9 may be a multi-core fiber or a multi-mode fiber. In the optical fiber array 11, the plurality of optical fibers 9 are arranged along the first direction D1 (or the second direction D2).

[0038] The first waveguide 2j of the optoelectronic substrate 2 is optically coupled to the optical IC 3. FIG. 3 is a schematic cross-sectional view showing an enlarged optical system of the optoelectronic substrate 2 and the optical IC 3. As shown in FIG. 3, the optical IC 3 includes a circuit surface 3b facing the first surface 2b of the optoelectronic substrate 2, a second recess 3c opening in the circuit surface 3b, a second waveguide 3d formed in the circuit surface 3b, and a second mirror 3f formed in the second recess 3c and reflecting the signal light L input / output to / from the second waveguide 3d. For example, the signal light L transmitted through the second waveguide 3d is output from the end face of the second waveguide 3d and reflected by the second mirror 3f. Alternatively, the signal light L reflected by the second mirror 3f is input to the end face of the second waveguide 3d and transmitted through the second waveguide 3d. Thus, for input / output, it is not necessary that input and output are always performed simultaneously and in parallel, and at least one of input and output may be performed. The optical IC 3 is connected to the optoelectronic substrate 2 with the circuit surface 3b facing the first surface 2b of the optoelectronic substrate 2. The first waveguide 2j and the second waveguide 3d are optically coupled to each other via the first mirror 2k and the second mirror 3f. The second mirror 3f reflects the signal light L such that the signal light L propagating through the second waveguide 3d has the same direction as the direction in which the signal light L propagates through the first waveguide 2j. Note that the second mirror 3f may reflect the signal light L such that the signal light L propagating through the second waveguide 3d has a direction different from the direction in which the signal light L propagates through the first waveguide 2j.

[0039] The inner surface 2h1 of the first recess 2h of the optoelectronic substrate 2 includes an inner surface 2h2 where the first waveguide 2j is formed, a bottom surface 2h3 to which the first mirror 2k is fixed, and an inner surface 2h4 that faces the inner surface 2h2 along the first direction D1. The first recess 2h is defined by the inner surface 2h2, the bottom surface 2h3, and the inner surface 2h4. The first mirror 2k has, for example, a fixing surface 2k1 fixed to the bottom surface 2h3, an outer surface 2k2 facing the inner surface 2h2, an outer surface 2k3 facing the inner surface 2h4, and an inclined surface 2k4 that extends obliquely downward from the upper end of the outer surface 2k3 to the upper end of the outer surface 2k2. The first mirror 2k has a reflecting surface 2k5 that reflects the signal light L. The reflecting surface 2k5 is formed on the inclined surface 2k4. The reflecting surface 2k5 is concave on the inclined surface 2k4. For example, the reflecting surface 2k5 is coated with a metal film. As an example, the material of the metal film is gold.

[0040] The inner surface 3c1 of the second recess 3c of the optical IC 3 includes an inner surface 3c2 where the second waveguide 3d is formed, a bottom surface 3c3 to which the second mirror 3f is fixed, and an inner surface 3c4 that faces the inner surface 3c2 along the first direction D1. The second recess 3c is defined by the inner surface 3c2, the bottom surface 3c3, and the inner surface 3c4. The second mirror 3f has, for example, a fixing surface 3f1 fixed to the bottom surface 3c3, an outer surface 3f2 facing the inner surface 3c2, an outer surface 3f3 facing the inner surface 3c4, and an inclined surface 3f4 that extends obliquely upward from the lower end of the outer surface 3f3 to the lower end of the outer surface 3f2. The second mirror 3f has a reflecting surface 3f5 that reflects the signal light L. The reflecting surface 3f5 is formed on the inclined surface 3f4. The reflecting surface 3f5 is concave on the inclined surface 3f4. For example, the reflecting surface 3f5 is coated with a metal film in the same manner as the reflecting surface 2k5. The curvature of the reflecting surface 3f5 may be different from the curvature of the reflecting surface 2k5.

[0041] For example, the first mirror 2k is a concave mirror having a reflecting surface 2k5 presenting a concave shape, and the second mirror 3f is a concave mirror having a reflecting surface 3f5 presenting a concave shape. When signal light L is output from the first waveguide 2j into the first recess 2h, the signal light L is reflected by the first mirror 2k toward the optical IC 3, and the second mirror 3f reflects the signal light L reflected by the first mirror 2k toward the second waveguide 3d. More specifically, when the signal light L is output as divergent light from the first waveguide 2j into the first recess 2h, the divergent light is converted into collimated light by the reflecting surface 2k5 of the first mirror 2k and is reflected toward the second mirror 3f. The collimated light reflected toward the second mirror 3f is converted into focused light by the reflecting surface 3f5 of the second mirror 3f and is reflected toward the second waveguide 3d.

[0042] Also, when the signal light L is output from the second waveguide 3d into the second recess 3c, the signal light L is reflected by the second mirror 3f toward the optoelectronic substrate 2, and the first mirror 2k reflects the signal light L reflected by the second mirror 3f toward the first waveguide 2j. More specifically, when the signal light L is output as divergent light from the second waveguide 3d into the second recess 3c, the divergent light is converted into collimated light by the reflecting surface 3f5 of the second mirror 3f and is reflected toward the first mirror 2k. The collimated light reflected toward the first mirror 2k is converted into focused light by the reflecting surface 2k5 of the first mirror 2k and is reflected toward the first waveguide 2j. Since the optoelectronic substrate 2 is a glass interposer, it is less likely to warp and has a small linear expansion coefficient compared to an organic interposer. Therefore, stable optical coupling can be realized between the first waveguide 2j and the second waveguide 3d.

[0043] For example, the length of the first mirror 2k in the first direction D1, the length of the first mirror 2k in the second direction D2, and the length of the first mirror 2k in the third direction D3 are 300 μm or less. The length of the first mirror 2k in the first direction D1, the length of the first mirror 2k in the second direction D2, and the length of the first mirror 2k in the third direction D3 may be 100 μm or less (for example, 50 μm). For example, the angle of the inclined surface 2k4 with respect to the fixed surface 2k1 is 30° or more and 60° or less. The radius of curvature of the reflecting surface 2k5 is, for example, 10 μm or more and 300 μm or less. The material of the first mirror 2k is, for example, resin or glass. For example, the beam diameter of the collimated light converted by the reflecting surface 2k5 is 10 μm or more and 100 μm or less, and the distance that the collimated light propagates is 10 μm or more and 200 μm or less.

[0044] The length of the first recess 2h in the first direction D1 is 100 μm or more and 500 μm or less, and the length of the first recess 2h in the second direction D2 of the first direction D1 is 100 μm or more and 500 μm or less. The length (depth) of the first recess 2h in the third direction D3 is 10 μm or more and 300 μm or less. A plurality of first mirrors 2k may be arranged along the second direction D2. In this case, the pitch of the first mirrors 2k arranged along the second direction D2 is, for example, 10 μm or more and 300 μm or less. The pitch of the first mirrors 2k may be the same as the pitch of the plurality of optical fibers 9 arranged along the second direction D2. When arranging a plurality of first mirrors 2k, a plurality of first recesses 2h may be formed for each first mirror 2k, or one first recess 2h in which a plurality of first mirrors 2k are arranged may be formed. The above describes examples of the lengths, angles, fixing methods, etc. of each part of the first mirror 2k and the first recess 2h. It is also possible to make the second mirror 3f and the second recess 3c of the optical IC 3 as in the above examples. Note that the shapes of the first mirror 2k and the second mirror 3f may be the same or different.

[0045] The examples of the first mirror 2k of the optoelectronic substrate 2 and the second mirror 3f of the optical IC 3 have been described above. However, the configurations of the first mirror 2k and the second mirror 3f are not limited to the examples described above. In the above, an example in which the first mirror 2k is fixed to the bottom surface 2h3 of the first recess 2h has been described. However, the first mirror 2k may be fixed to the inner surface 2h4, and the location where the first mirror 2k is fixed can be changed as appropriate. The same applies to the second mirror 3f.

[0046] FIG. 4 is a diagram schematically showing an optical fiber 9, an optical fiber array 11, an optoelectronic substrate 2, and an optical IC 3 in a plan view. As shown in FIGS. 1 and 4, the first recess 2h of the optoelectronic substrate 2 is covered by the optical IC 3. Therefore, the intrusion of dust or the like into the first recess 2h can be suppressed, and the reliability of optical coupling in the optoelectronic substrate 2 and the optical IC 3 can be improved. Further, as described above, the underfill resin 8 stops in front of the first recess 2h and the second recess 3c due to surface tension. Thereby, the intrusion of the underfill resin 8 into the first recess 2h and the second recess 3c can be suppressed, and the reliability of optical coupling in the optoelectronic substrate 2 and the optical IC 3 can be further improved.

[0047] The first waveguide 2j and the glass portion of the optoelectronic substrate 2 (glass substrate 2G) have transparency in the wavelength band of the signal light L used by the optical module 1 (for example, 1.2 μm to 1.7 μm). The first waveguide 2j has a refractive index higher than that of the glass portion of the optoelectronic substrate 2 located around the first waveguide 2j. Thereby, the glass portion of the optoelectronic substrate 2 functions as a cladding, and the first waveguide 2j functions as a core. Then, the signal light L can be confined inside the first waveguide 2j functioning as a core. For example, the first waveguide 2j has a refractive index comparable to that of the core of the optical fiber 9, and the glass portion of the optoelectronic substrate 2 has a refractive index comparable to that of the cladding of the optical fiber 9. The optical fiber 9 is connected to the end face 2p and is optically coupled to the first waveguide 2j.

[0048] The optical module 1 has a plurality of first waveguides 2j, and the plurality of first waveguides 2j are arranged along the first direction D1 (or the second direction D2). For example, the first waveguide 2j has a first portion 2t extending from the optical IC 3 in a plan view, a third portion 2w optically connected to the optical fiber 9 held by the optical fiber array 11, and a second portion 2v that smoothly connects the first portion 2t to the third portion 2w. The pitch of the second portions 2v arranged along the second direction D2 (or the first direction D1) increases as the distance from the first portion 2t increases.

[0049] Next, the effects obtained from the optical module 1 and the optoelectronic substrate 2 according to this embodiment will be described. The optoelectronic substrate 2 of the optical module 1 has a first surface 2b facing the circuit surface 3b of the optical IC 3, and a first recess 2h is formed in the first surface 2b. The optoelectronic substrate 2 has a first waveguide 2j, and the first waveguide 2j extends toward the first recess 2h. A first mirror 2k is formed in the first recess 2h, and the first mirror 2k reflects the signal light L propagating through the first waveguide 2j. By arranging the first mirror 2k in the first recess 2h where the first waveguide 2j extends and reflecting the signal light L propagating through the first waveguide 2j by the first mirror 2k, it is possible to reduce the loss in a wider wavelength band compared to the case where a grating coupler is used for optical coupling, for example. In addition, the first mirror 2k can be formed of resin. Resin has better workability than glass and is easy to process into a three-dimensional shape. Thereby, a mirror with low loss can be formed.

[0050] As described above, the optoelectronic substrate 2 may be configured by laminating a plurality of glass substrates 2G. The first surface 2b may be the first surface 2b of the uppermost glass substrate 2G1 among the plurality of glass substrates 2G, and the first waveguide 2j may be formed on the uppermost glass substrate 2G1. In this case, when the optoelectronic substrate 2 is mounted on the wiring substrate 100, it is possible to easily match the pitch of the electrical wiring (for example, terminal 4) in the wiring substrate 100 to the pitch of the electrical wiring (for example, terminal 7) in the integrated circuit 10 between the plurality of glass substrates 2G. Further, since the first waveguide 2j is formed on the uppermost glass substrate 2G1, the distance from the optical IC 3 is short, and it is possible to easily improve the efficiency of optical coupling. In addition, it is possible to increase the design freedom of the electrical wirings 2x, 2y, 2g and the vias 2d in the glass substrates 2G2, 2G3 located below the glass substrate 2G1. Further, by forming the first waveguide 2j and the first recess 2h only on a specific glass substrate among the plurality of glass substrates, the reliability can be improved.

[0051] As described above, the signal light L may be output from the first waveguide 2j into the first recess 2h, and the signal light L may be reflected by the first mirror 2k toward the optical IC 3. The second mirror 3f of the optical IC 3 may reflect the signal light L reflected by the first mirror 2k toward the second waveguide 3d. In this case, the signal light L propagating through the first waveguide 2j of the optoelectronic substrate 2 can be reflected by the first mirror 2k disposed in the first recess 2h toward the optical IC 3. Then, by reflecting the signal light L reflected by the first mirror 2k by the second mirror 3f toward the second waveguide 3d of the optical IC 3, the first waveguide 2j can be optically coupled to the second waveguide 3d. Since it is optical coupling using two mirrors, for example, compared with optical coupling using evanescent coupling, small-sized optical coupling can be realized. For example, in a plan view, the area required for optical coupling can be reduced compared with evanescent coupling. Therefore, the optical IC 3 mounted on the optoelectronic substrate 2 can be mounted at high density, and miniaturization of the optical module 1 and the optical IC 3 can be realized. Further, the second mirror 3f can be formed of resin. Resin has better workability than the inorganic materials (for example, silicon or silicon dioxide) constituting the optical IC 3, and three-dimensional shape processing is easy. Thereby, low-loss optical coupling can be realized.

[0052] As described above, the second mirror 3f may reflect the signal light L such that the direction of the signal light L propagating through the second waveguide 3d becomes the same as the direction of the signal light L propagating through the first waveguide 2j. In this case, the direction of the signal light L propagating through the second waveguide 3d can be made the same as the direction of the signal light L propagating through the first waveguide 2j.

[0053] As described above, the optoelectronic substrate 2 may have an end face 2p intersecting the first face 2b, and the first waveguide 2j may extend from the end face 2p toward the first recess 2h. The optical module 1 may further include an optical fiber 9 connected to the end face 2p and optically coupled to the first waveguide 2j. In this case, the optical fiber 9 can be optically coupled to the first waveguide 2j of the optoelectronic substrate 2, and signal light L can be transmitted and received to and from the outside of the optical module 1 via the optical fiber 9.

[0054] Next, various modifications of the optical module and the optoelectronic substrate according to the present disclosure will be described. Some configurations of the optical module and the optoelectronic substrate according to the various modifications are the same as some configurations of the above-described optical module 1 and optoelectronic substrate 2. Therefore, hereinafter, descriptions overlapping with the descriptions of the optical module 1 and the optoelectronic substrate 2 will be given the same reference numerals and appropriately omitted.

[0055] FIG. 5 is a cross-sectional view schematically showing the optoelectronic substrate 2A and the optical IC 3A of the optical module 1A according to the first modification. As shown in FIG. 5, the optoelectronic substrate 2A has a first mirror 2q different from the above-described first mirror 2k, and the optical IC 3A has a second mirror 3g different from the above-described second mirror 3f.

[0056] The first mirror 2q has a fixing surface 2q1 fixed to the inner surface 2h2 of the first recess 2h, an outer surface 2q2 facing the second recess 3c of the optical IC 3A, and an inclined surface 2q3 extending obliquely upward from the lower end of the fixing surface 2q1. The first mirror 2q has a reflecting surface 2q4 formed on the inclined surface 2q3. The reflecting surface 2q4 has a convex shape protruding outward from the inclined surface 2q3 of the first mirror 2q. The second mirror 3g has a fixing surface 3g1 fixed to the inner surface 3c2 of the second recess 3c, an outer surface 3g2 facing the first recess 2h, and an inclined surface 3g3 extending obliquely downward from the upper end of the fixing surface 3g1. The second mirror 3g has a reflecting surface 3g4 formed on the inclined surface 3g3. The reflecting surface 3g4 has a convex shape protruding outward from the inclined surface 3g3 of the second mirror 3g.

[0057] When the signal light L is output as divergent light from the first waveguide 2j to the first mirror 2q in the first recess 2h, the divergent light is converted into collimated light by the reflecting surface 2q4 of the first mirror 2q and reflected toward the second mirror 3g. The collimated light reflected toward the second mirror 3g is converted into convergent light by the reflecting surface 3g4 of the second mirror 3g and reflected toward the second waveguide 3d. Further, when the signal light L is output as divergent light from the second waveguide 3d to the second mirror 3g in the second recess 3c, the divergent light is converted into collimated light by the reflecting surface 3g4 of the second mirror 3g and reflected toward the first mirror 2q. The collimated light reflected toward the first mirror 2q is converted into convergent light by the reflecting surface 2q4 of the first mirror 2q and reflected toward the first waveguide 2j.

[0058] FIG. 6 is a cross-sectional view schematically showing the optoelectronic substrate 2B and the optical IC 3B of the optical module 1B according to the second modification. As shown in FIG. 6, the first mirror 2r of the optoelectronic substrate 2B has a fixing surface 2r1 fixed to the inner surface 2h2 of the first recess 2h, an outer surface 2r2 facing the second recess 3c of the optical IC 3B, and an inclined surface 2r3 extending obliquely upward from the lower end of the fixing surface 2r1. The reflecting surface 2r4 of the first mirror 2r has a concave shape that is recessed inward from the inclined surface 2r3 of the first mirror 2r. The first mirror 2r has a lens portion 2r5 having a convex shape that protrudes outward from the outer surface 2r2 of the first mirror 2r.

[0059] The second mirror 3h of the optical IC 3B has a fixing surface 3h1 fixed to the inner surface 3c2 of the second recess 3c, an outer surface 3h2 facing the first recess 2h, and an inclined surface 3h3 extending obliquely downward from the upper end of the fixing surface 3h1. The reflecting surface 3h4 of the second mirror 3h has a concave shape that is recessed inward from the inclined surface 3h3 of the second mirror 3h. The second mirror 3h has a lens portion 3h5 having a convex shape that protrudes outward from the outer surface 3h2 of the second mirror 3h.

[0060] When the signal light L is output as divergent light from the first waveguide 2j to the first mirror 2r in the first recess 2h, the divergent light is reflected by the reflecting surface 2r4 of the first mirror 2r while the beam diameter is enlarged, and is reflected toward the lens portion 2r5. The divergent light reflected toward the lens portion 2r5 is converted into collimated light by the lens portion 2r5 and is emitted toward the second mirror 3h. The collimated light emitted toward the second mirror 3h is converted into focused light by the lens portion 3h5 and is reflected by the reflecting surface 3h4 toward the second waveguide 3d. In the first mirror 2r and the second mirror 3h shown in FIG. 6, the reflecting surface 2r4 and the reflecting surface 3h4 act as convex mirrors, respectively. Since the divergent light with an enlarged beam diameter by the reflecting surface 2r4 enters the lens portion 2r5, it is possible to make the beam diameter of the collimated light larger than that of the first mirrors 2k and 2q and the second mirrors 3f and 3g. Thereby, the tolerance regarding the alignment between the optoelectronic substrate 2B and the optical IC 3B is improved, the decrease in the efficiency of optical coupling can be suppressed, and it becomes easy to realize a high optical coupling efficiency between the optoelectronic substrate 2B and the optical IC 3B.

[0061] When the signal light L is output as divergent light from the second waveguide 3d to the second mirror 3h in the second recess 3c, the divergent light is reflected by the reflecting surface 3h4 of the second mirror 3h while the beam diameter is enlarged, and is reflected toward the lens portion 3h5. The divergent light reflected toward the lens portion 3h5 is converted into collimated light by the lens portion 3h5 and is emitted toward the first mirror 2r. The collimated light emitted toward the first mirror 2r is converted into focused light by the lens portion 2r5 and is reflected by the reflecting surface 2r4 toward the first waveguide 2j.

[0062] FIG. 7 is a plan view schematically showing the optoelectronic substrate 2C of the optical module 1C according to the third modification. FIG. 8 is a cross-sectional view schematically showing the optoelectronic substrate 2C and the optical IC 3 of the optical module 1C. The optoelectronic substrate 2C has a first recess 2s in which a region A that is exposed to the outside of the optical module 1C is formed in a state where the optical IC 3 is mounted on the optoelectronic substrate 2C. The region A located at the end of the first recess 2s in the second direction D2 is not covered by the optical IC 3. In the optical module 1C, it is possible to access the first recess 2s from the outside of the optical module 1C through the region A.

[0063] In the optical module 1C, it is possible to fill the first recess 2s with the matching resin R from the outside of the optical module 1C through the region A. The matching resin R is filled to suppress the reflection of the signal light L at the interface between glass and air or at the interface between resin and air. Further, by filling the first recess 2s with the matching resin R, the occurrence of dew condensation in the first recess 2s and the intrusion of dust and the like into the first recess 2s can be suppressed, so that the reliability of optical coupling in the optoelectronic substrate 2C and the optical IC 3 can be improved. The matching resin R may be a curable resin or a non-curable resin. FIG. 7 shows an example in which both ends of the first recess 2s in the second direction D2 are exposed to the outside of the optical module 1C. However, one side of the first recess 2s in the second direction D2 may be exposed to the outside of the optical module 1C.

[0064] FIG. 9 is a cross-sectional view showing the optical module 1D according to the fourth modification. As shown in FIG. 9, the optical module 1D has an optoelectronic substrate 2D and an optical IC 3D. The optical module 1D has a plurality of optical ICs 3D. The plurality of optical ICs 3D include, for example, a light source 3E and a modulator 3F. As an example, the modulators 3F are arranged on both sides of the light source 3E in the first direction D1. However, the configuration of the plurality of optical ICs 3D is not limited to the above example and can be changed as appropriate.

[0065] The optical IC 3D has a plurality of second recesses 3c. The optoelectronic substrate 2D has a plurality of first recesses 2h that face each of the plurality of second recesses 3c of one optical IC 3D along the third direction D3. The optoelectronic substrate 2D has a plurality of first waveguides 2j. Any one of the plurality of first waveguides 2j extends along the first direction D1 between two first recesses 2h. The optoelectronic substrate 2D has a plurality of first waveguides 2j that extend toward each of the plurality of first recesses 2h and a plurality of first mirrors 2k formed inside each of the plurality of first recesses 2h. The optical IC 3D has a second waveguide 3d that extends between the plurality of second recesses 3c and a plurality of second mirrors 3f formed inside each of the plurality of second recesses 3c.

[0066] The plurality of first waveguides 2j are optically coupled to each other via the plurality of first mirrors 2k, the plurality of second mirrors 3f, and the second waveguide 3d. As a specific example, when the first waveguide 2j1, the first waveguide 2j2, the first waveguide 2j3, and the first waveguide 2j4 are arranged in this order along the first direction D1, the first waveguide 2j1 is optically coupled to the first waveguide 2j2 via the first mirror 2k, the second mirror 3f of the modulator 3F, the second waveguide 3d of the modulator 3F, the second mirror 3f of the modulator 3F, and the first mirror 2k.

[0067] The first waveguide 2j2 is optically coupled to the first waveguide 2j3 via the first mirror 2k, the second mirror 3f of the light source 3E, the second waveguide 3d of the light source 3E, the second mirror 3f of the light source 3E, and the first mirror 2k. And the first waveguide 2j3 is optically coupled to the first waveguide 2j4 via the first mirror 2k, the second mirror 3f of the modulator 3F, the second waveguide 3d of the modulator 3F, the second mirror 3f of the modulator 3F, and the first mirror 2k. Thus, in the optical module 1D, optical coupling with various optical IC 3Ds can be realized.

[0068] The embodiments and various modifications of the optical module and the optoelectronic substrate according to the present disclosure have been described above. However, the optical module and the optoelectronic substrate according to the present disclosure are not limited to the above-described embodiments or modifications, and may be further modified within the scope of the gist described in the claims. That is, the configuration, shape, size, material, number, and arrangement mode of each part of the optical module and the optoelectronic substrate according to the present disclosure can be appropriately changed within the scope of the above gist.

[0069] For example, in the fourth modification described above, the optical module 1D including a plurality of optical ICs 3D in which modulators 3F are arranged on both sides of the light source 3E in the first direction D1 has been described. However, as shown in FIG. 10, a light source 3E may be arranged at each of the four corners of the rectangular optoelectronic substrate 2 in a plan view, and the optical module may be such that each light source 3E is optically coupled to an adjacent modulator 3F via a first waveguide 2j. Further, a semiconductor optical amplifier may be used in addition to the light source. Thus, the number, arrangement position, and connection mode of the optical ICs mounted on the optoelectronic substrate of the optical module can be appropriately changed.

[0070] Further, for example, the optoelectronic substrate may be composed of a single glass substrate. In this case, one or a plurality of wiring layers (rewiring layers or build-up layers) may be formed on at least one of the first surface and the second surface of the optoelectronic substrate. With one or a plurality of wiring layers, it becomes easy to match the pitch of the electrical wiring (for example, terminal 4) in the wiring substrate 100 to the pitch of the electrical wiring (for example, terminal 7) in the integrated circuit 10. It is desirable that the wiring layer is removed at the location where the first recess 2h is formed for optical coupling between the integrated circuit 10 and the first waveguide 2j.

Description of Reference Numerals

[0071] 1, 1A, 1B, 1C, 1D... optical module 2, 2A, 2B, 2C, 2D... optoelectronic substrate 2G... glass substrate 2b... first surface 2c... second surface 2d... via 2f, 2g… Electrical wiring 2h… First recess 2h1… Inner surface 2h2… Inner side surface 2h3… Bottom surface 2h4… Inner side surface 2j, 2j1, 2j2, 2j3, 2j4… First waveguide 2k… First mirror 2k1… Fixed surface 2k2, 2k3… Outer side surfaces 2k4… Inclined surface 2k5… Reflecting surface 2p… End face 2q… First mirror 2q1… Fixed surface 2q2… Outer surface 2q3… Inclined surface 2q4… Reflecting surface 2r… First mirror 2r1… Fixed surface 2r2… Outer surface 2r3… Inclined surface 2r4… Reflecting surface 2r5… Lens part 2s… First recess 2t… First part 2v… Second part 2w… Third part 3, 3A, 3B, 3C, 3D… Optical IC 3b… Circuit surface 3c… Second recess 3c1… Inner surface 3c2… Inner side surface 3c3… Bottom surface 3c4… Inner side surface 3d… Second waveguide 3E… Light source 3f… Second mirror 3F… Modulator 3f1… Fixed surface 3f2, 3f3… Outer side surfaces 3f4… Inclined surface 3f5… Reflecting surface 3g… Second mirror 3g1… Fixed surface 3g2… Outer surface 3g3… Inclined surface 3g4… Reflecting surface 3h…Second mirror 3h1…Fixed surface 3h2…Outer surface 3h3…Inclined surface 3h4…Reflecting surface 3h5…Lens part 4…Terminal 5…Electric IC 6…LSI 7…Terminal 8…Underfill resin 9…Optical fiber 10…Integrated circuit 11…Optical fiber array 100…Wiring board A…Region D1…First direction D2…Second direction D3…Third direction L…Signal light R…Matching resin

Claims

1. an optoelectronic substrate having a first surface, a first recess opening on the first surface, a first waveguide extending toward the first recess, and a first mirror formed in the first recess for reflecting signal light propagating through the first waveguide; an optical IC including a circuit surface facing the first surface, a second waveguide formed on the circuit surface, a second recess opening on the circuit surface, and a second mirror formed in the second recess for reflecting the signal light propagating through the second waveguide, the circuit surface facing the first surface and connected to the opto-electrical substrate; Equipped with the first waveguide and the second waveguide are optically coupled to each other via the first mirror and the second mirror; Optical module.

2. The optoelectronic substrate is configured by laminating a plurality of glass substrates, the first surface is a top surface of an uppermost glass substrate among the plurality of glass substrates; The first waveguide is formed in the uppermost glass substrate.

2. The optical module according to claim 1.

3. the signal light is output from the first waveguide into the first recess, and the signal light is reflected by the first mirror toward the optical IC; the second mirror reflects the signal light reflected by the first mirror toward the second waveguide; 3. The optical module according to claim 1 or 2.

4. the second mirror reflects the signal light such that a direction of the signal light propagating through the second waveguide becomes the same as a direction of the signal light propagating through the first waveguide; 4. The optical module according to claim 3.

5. the optoelectronic substrate has an end face intersecting the first surface, and the first waveguide extends from the end face toward the first recess; an optical fiber connected to the end surface and optically coupled to the first waveguide; 3. The optical module according to claim 1 or 2.

6. the optoelectronic substrate has a plurality of the first recesses, a plurality of the first waveguides extending toward the plurality of first recesses, respectively, and a plurality of the first mirrors formed within the plurality of first recesses, respectively; the optical IC includes a plurality of the second recesses, the second waveguide extending between the plurality of the second recesses, and a plurality of the second mirrors formed within the plurality of the second recesses, respectively; the first waveguides are optically coupled to each other via the first mirrors, the second mirrors, and the second waveguide; 3. The optical module according to claim 1 or 2.

7. An opto-electrical substrate connected to an optical IC, a first surface facing a circuit surface of the optical IC; a first recess opening to the first surface; a first waveguide extending toward the first recess; a first mirror formed in the first recess and configured to reflect signal light propagating through the first waveguide; Equipped with Opto-electrical board.

8. 1. An opto-electrical substrate having a first surface and a second surface opposite the first surface, a first glass substrate having the first surface; a second glass substrate having the second surface; Equipped with the first glass substrate has a first recess opening in the first surface, a first waveguide extending toward the first recess, a first mirror formed in the first recess and configured to reflect signal light propagating through the first waveguide, and a first terminal formed on the first surface; the second glass substrate has a second terminal formed on the second surface; The first glass substrate and the second glass substrate are provided with wiring for electrically connecting the first terminal and the second terminal to each other. Opto-electrical board.

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