Optical connection structure, package structure and optical module

Abstract

This optical connection structure (10) is in a package structure (11) which is connected to an optical fiber (109) and has a substrate (1041). The optical connection structure comprises: an optical element (101) disposed on the substrate (1041); and an optical path conversion part (102) disposed on the substrate (1041). One end surface of the optical path conversion part (102) faces an end surface of the optical element (101).　Due to this configuration, the present invention can provide an optical connection structure, with which mass productivity can be improved and an optical fiber does not have to be directly bonded to an optical element.

Description

[Technical field]

[0001] The present invention relates to an optical connection structure for connecting an optical fiber and an optical element, a package structure, and an optical module. [Background technology]

[0002] The recent rapid increase in Internet traffic has created a demand for an expansion of the communication capacity of datacenter networks. Furthermore, in order to respond to the expansion of transmission capacity and the need for low power consumption, the introduction of optical interconnections that transmit data by light is also progressing for short- and medium-distance applications.

[0003] In a typical optical interconnection system, signal processing is achieved by transmitting signals between optical emitters such as laser diodes (LD) and optical receivers such as photodiodes (PD) arranged on a printed circuit board using optical transmission media such as optical waveguides and optical fibers.

[0004] Depending on the transmission method, the optical light emitting element is integrated with an optical modulation element or is connected discretely, and further connected to a driver that performs electrical-optical conversion, etc. A configuration including these optical light emitting elements, optical modulation elements, drivers, etc. is mounted on an electrical mounting board such as a printed circuit board (PCB) as an optical transmitter.

[0005] Similarly, an optical processor and the like are appropriately integrated or discretely connected to the optical receiving element, and an electric amplifier circuit that performs optical-electrical conversion is further connected to the optical receiving element. A configuration including the optical receiving element, optical processor, electric amplifier circuit, etc. is mounted on a printed circuit board as an optical receiver.

[0006] Optical transceivers that integrate these optical transmitters and receivers are mounted in packages or on printed circuit boards and optically connected to optical transmission media such as optical fibers to realize optical interconnections. Depending on the topology, optical interconnections are also realized via repeaters such as optical switches.

[0007] Meanwhile, as light-emitting elements, light-receiving elements, and light-modulating elements used in optical interconnections, elements using semiconductors such as silicon and germanium, and III-V group semiconductors such as indium phosphide (InP), gallium arsenide (GaAs), and indium gallium arsenide (InGaAs) have been put to practical use. In recent years, optical waveguide-type optical transceivers that integrate silicon optical circuits (silicon photonics) and indium phosphide optical circuits that have a light propagation mechanism, as well as these elements, have been developed. In addition to semiconductors, optical modulating elements may also use materials such as ferroelectrics such as lithium niobate and polymers.

[0008] Furthermore, optical functional elements such as planar lightwave circuits made of quartz glass may be integrated together with the above-mentioned optical light-emitting elements, optical light-receiving elements, and optical modulation elements. Optical functional elements include splitters, wavelength multiplexers / demultiplexers, optical switches, polarization control elements, optical filters, etc. Hereinafter, devices that integrate optical light-emitting elements, optical light-receiving elements, optical modulation elements, optical functional elements, optical amplifier elements, etc., that have the above-mentioned optical propagation and waveguiding mechanisms will be referred to as optical waveguide devices.

[0009] Among optical waveguide devices, silicon photonics chips have excellent integration, mass production, and compatibility with electrical components, and are attracting attention as key devices for realizing next-generation optical interconnections (Non-Patent Document 1).

[0010] Methods for connecting an optical transceiver, which integrates a silicon photonics chip, driver, and electric amplifier circuit, to electrical wiring on a board include wire bonding, flip chip connection, and connection using a ball-grid array (BGA), land-grid array (LGA), pin-grid array (PGA), copper pillar, etc. When making the above connection, if necessary, it may be connected to an electrical mounting board via another package substrate such as an interposer component.

[0011] One method for connecting a silicon photonics chip to an optical fiber is to connect it to an optical fiber array integrated with glass or the like in which a V-groove is formed. In this structure, it is required to connect each core of the optical fiber to each core of the waveguide of the optical waveguide device with low loss. To achieve this low-loss connection, it is necessary to position (hereinafter referred to as "alignment") and fix the optical waveguide device and the optical fiber to the submicron level.

[0012] In conventional optical waveguide devices, alignment (optical alignment) is performed while actually inputting and outputting light and monitoring the power, and the device is then mounted inside a package or on a board in an integrated state with an optical fiber array. [Prior art documents] [Non-patent literature]

[0013] [Non-Patent Document 1] K. Shikama et al., "Multicore-Fiber Receptacle With Compact Fan-In / Fan-Out Device for SDM Transceiver Applications," in Journal of Lightwave Technology, vol. 36, no. 24, pp. 5815-5822, 15 Dec.15, 2018, doi: 10.1109 / JLT.2018.2879100. Summary of the Invention [Problem to be solved by the invention]

[0014] However, the conventional structure in which an optical fiber is adhesively connected to a silicon photonics chip using an adhesive or the like has the following problems.

[0015] In order to directly bond the fiber array to the silicon photonics chip, it was necessary to optically polish the end face of the silicon photonics chip.

[0016] In addition, because the adhesive surfaces are the sides of the chip, the adhesive area is limited, raising concerns that it may be difficult to obtain sufficient adhesive strength.

[0017] In addition, since the optical fiber is connected as a pigtail, the next process such as board mounting requires a process for maintaining (stabilizing) the fixed connection state of the optical fiber, such as handling the optical fiber, which reduces the mass productivity (throughput improvement and stabilization) of the assembly process. [Means for solving the problem]

[0018] In order to solve the above-mentioned problems, the optical connection structure according to the present invention is an optical connection structure in a package structure connected to an optical fiber and having a substrate, the optical connection structure including an optical element having an optical circuit arranged on the substrate, an optical path conversion unit arranged on the substrate, and the optical fiber of Detachable To connection In order to an adapter, wherein a surface of the optical element having the optical circuit faces one surface of the substrate, and one end surface of the optical path changing unit faces an end surface of the optical element, before An optical connection structure, wherein input and output light in the optical path changing section is propagated symmetrically with respect to a central axis of the optical path changing section between the one end face and the other end face. Effect of the Invention

[0019] According to the present invention, it is possible to provide an optical connection structure, a package structure, and an optical module that can improve mass productivity without directly bonding an optical fiber to an optical element. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic side view showing the configuration of an optical module according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic side view showing an example of the configuration of the optical module according to the first embodiment of the present invention. [Diagram 3]FIG. 3 is a schematic side view showing an example of the configuration of the optical module according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a schematic top view showing the configuration of the optical module according to the first embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic top view showing an example of the configuration of the optical module according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a schematic side view showing an example of the configuration of the optical module according to the first embodiment of the present invention. [Figure 7] FIG. 7 is a schematic side view showing the configuration of an optical module according to the second embodiment of the present invention. [Figure 8] FIG. 8 is a schematic side view showing an example of the configuration of an optical module according to the second embodiment of the present invention. [Figure 9] FIG. 9 is a schematic side view showing an example of the configuration of an optical module according to the second embodiment of the present invention. [Figure 10] FIG. 10 is a schematic top view for explaining the operation of the optical connection structure according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] <First embodiment> An optical connection structure, a package structure, and an optical module according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG.

[0022] <Package structure and optical module configuration> Fig. 1 is a schematic side view showing the configuration of an optical module 1 according to the present embodiment. Hereinafter, when optical module 1 is configured as shown in Fig. 1, the surface on the Z+ side in the figure is referred to as the "upper surface" and the surface on the Z- side is referred to as the "lower surface."

[0023] The optical module 1 according to the present embodiment includes a package structure 11, a ferrule 108, and an optical fiber 109. The package structure 11 and the ferrule 108 are fixed together by a clip 110.

[0024] In the package structure 11, a silicon photonics chip 101, a GRIN lens 102, and an IC 103 are mounted on a substrate 1041, and are covered with a molding resin 105. Here, the substrate 1041 is a thin-layer wiring board having a thickness of about 10 μm to 30 μm.

[0025] A BGA or LGA is formed as an electrical connection portion 106 on the surface (bottom surface) opposite the component mounting surface (top surface) of the substrate 1041, providing an electrical interface with an electrical mounting board (not shown) such as a PCB on which the optical package is mounted.

[0026] Silicon photonics chip 101 is a chip on whose surface optical circuits and electric circuits are formed, and its thickness is 625 μm, which is the standard silicon wafer thickness.

[0027] The silicon photonics chip 101 is flip-chip mounted on the substrate 1041 via solder balls or copper pillars, with the surface on which the optical circuit is formed (circuit surface) facing downward, i.e., face-down. Since it is mounted face-down, the position (height) of the input / output light from the silicon photonics chip 101 is low, about several tens of μm to several hundred tens of μm above the upper surface of the substrate 1041.

[0028] The GRIN lens 102 is a cylindrical optical component, and is a gradient index lens in which the refractive index changes parabolically from the central axis of the cylinder to the outer periphery. The focal length of the GRIN lens changes by changing its length, and the lens characteristics are expressed by the following relational equation.

[0029] Z=2πP / √A

[0030] Here, Z is the GRIN lens length, √A is the refractive index distribution constant determined by the material and manufacturing method, and P is the pitch that represents the meandering period of the light beam passing through the lens.

[0031] In this embodiment, a GRIN lens with a pitch of about 0.5 (P≈0.5) is used, and in the case of a typical GRIN lens with a diameter of 1.8 mm, its length Z is about 9.6 mm.

[0032] The light emitted from silicon photonics chip 101 is incident on one end face of GRIN lens 102 at a low position (the end face on the left side in FIG. 1), and then propagates inside GRIN lens 102 while changing its direction of travel and its state of divergence / convergence, as shown by curve 12 in the figure, and is imaged at a high position on the other end face of GRIN lens 102 (the end face on the right side in FIG. 1).

[0033] Here, the "low" position of the GRIN lens 102 refers to a position below the central axis of the GRIN lens 102, and in particular in FIG. 1, refers to the vicinity of the bottom surface of the GRIN lens 102 (the surface in contact with the substrate 1041).

[0034] Moreover, the "high" position of the GRIN lens 102 refers to a position above the central axis of the GRIN lens 102, and in particular in FIG. 1, this refers to the vicinity of the top surface of the GRIN lens 102 (the surface opposite the surface in contact with the substrate 1041).

[0035] In the GRIN lens 102 , the incident position of light on one end face and the image formation (emergence) position on the other end face are symmetrical with respect to the central axis of the GRIN lens 102 .

[0036] 2 shows an example in which silicon photonics chip 101 is mounted so-called face-up, with the surface on which an optical circuit is formed (circuit surface) facing upward. In this case, light is incident on one end face of GRIN lens 102 (the end face on the left in FIG. 2) at a position near the central axis. The light rays inside GRIN lens 102 propagate along a path different from that in the case of face-down mounting (FIG. 1), and form an image at the other end face (the end face on the right in FIG. 2).

[0037] Here, in the GRIN lens 102, the incident position of light on one end face and the image (emergence) position on the other end face are symmetrical with respect to the central axis of the GRIN lens 102, as in the case of face-down mounting (FIG. 1).

[0038] The electrical connection between the silicon photonics chip 101 and the substrate 1041 is realized by wire bonding or TSV (Through Silicon Via).

[0039] The substrate 1041 is a multi-layer wiring layer in which copper foil layers and insulating resin layers are alternately stacked, and is generally called a re-distribution layer (RDL) when manufactured using fan-out wafer-level package (FOWLP) technology or fan-out panel-level package (FOPLP) technology.

[0040] In this embodiment, the fan-out package can be fabricated, for example, by adopting the "RDL first method," in which an electrical wiring layer (RDL) is first formed on a support substrate (wafer or panel), then chip mounting and resin molding are performed, and finally the support substrate is peeled off.

[0041] However, the substrate 1041 is not limited to an RDL, and may be a general wiring substrate (an organic build-up substrate or a ceramic substrate).

[0042] Furthermore, the substrate can be partially thinned or a notch can be provided. For example, as shown in Fig. 3, the substrate 1042 can be made thinner only at the portion where the GRIN lens 102 is mounted than at the portion where the silicon photonics chip 101 is mounted, so that the heights of the silicon photonics chip 101 and the GRIN lens 102 can be set arbitrarily. Here, the substrate 1042 is a substrate (thickness: about 1000 µm) made of ceramic or the like.

[0043] Like the silicon photonics chip, the IC 103 is not limited to face-down mounting, but may be face-up mounting. The IC 103 is not limited to a bare chip, but may be a packaged component. In addition to multiple ICs or packaged components and silicon photonics chips, various optical chips (optical elements) may be mounted as described above.

[0044] In this embodiment, the other end face of the GRIN lens 102 (the end face on the right side in FIGS. 1 to 3) is exposed from the mold resin 105 and is adhesively fixed to an adapter 107.

[0045] A short optical fiber or optical waveguide component is built inside the adapter 107 and guides the light imaged on the other end surface of the GRIN lens 102 .

[0046] The end face of the adapter 107 opposite to the face facing the GRIN lens 102 is in contact with a ferrule 108 , and the light is further guided to an optical fiber 109 built inside the ferrule 108 .

[0047] When the optical fiber 109 is a single mode optical fiber, it is necessary to align the components with submicron accuracy for these guided lights. Therefore, the adapter 107 performs active alignment with respect to the GRIN lens 102, and is fixed by adhesive at the optimal position.

[0048] The connection structure between the adapter 107 and the ferrule 108 will be described below with reference to the top views shown in FIGS.

[0049] As shown in Fig. 4, the adapter 107 is a rectangular part with two circular holes for guide pins in the horizontal direction (top and bottom in the figure). Similarly, the rectangular ferrule 108 is also provided with circular holes for guide pins. By inserting guide pins 111 (indicated by dotted lines in the figure) into these circular holes, the adapter 107 and ferrule 108 are connected with high precision. To maintain contact between the two, they are fixed with a clip 110. Here, the dashed line in the figure indicates the optical fiber 109.

[0050] The ferrule 108 and the adapter 107 can be detached by removing the clip 110, and the same fitting mechanism as that of a known MT connector can be used. Note that any mechanism that applies a pressing force between the ferrules other than the clip can be used. For example, a leaf spring part, a coil spring part, or magnetic force other than mechanical fastening may be used.

[0051] As described above, the GRIN lens 102 has a refractive index distribution that is rotationally symmetric about the central axis, and therefore can obtain the same focusing characteristics in the horizontal plane as in the vertical direction. As shown in Fig. 4, light incident on one end face of the GRIN lens 102 (the end face on the left in Fig. 4) from the optical input / output parts arranged in an array on the silicon photonics chip 101 is arrayed and imaged on the other end face (the end face on the right in Fig. 4).

[0052] Therefore, an MT ferrule, which is a general multi-core ferrule, can be used as the rectangular ferrule 108. The material of the ferrule may be a resin containing a filler used in MT ferrules, or other resin materials, glass materials, ceramic materials, metal materials, Si, etc. Also, the guide pin 111 may be integrated with the adapter 107 or the ferrule 108 in advance.

[0053] Alternatively, as shown in Fig. 5, it is possible to form an optical interface for each core by using a plurality of GRIN lenses and a plurality of single-core ferrules. In this configuration, a plurality of GRIN lenses 102_1, 102_2 and a plurality of second ferrules 108_1, 108_2 are provided. Also, as an adapter, first ferrules 107_1, 107_2, which are single-core ferrules having a coaxial structure, are provided. The first ferrules 107_1, 107_2 and the second ferrules 108_1, 108_2 can be connected with high accuracy by split sleeves 112_1, 112_2.

[0054] In this embodiment, the design is such that no large optical reflection occurs between the GRIN lens and the silicon photonics chip. For example, by matching the refractive index of the molding resin material with that of the materials constituting the chip end face and the lens end face, it is possible to suppress large Fresnel reflection caused by the difference in refractive index.

[0055] Alternatively, the end faces may be designed to be inclined so that the reflected light does not recombine. Also, a known anti-reflection film may be formed on the end face of the silicon photonics chip or the end face of the GRIN lens. Similarly, the design is such that there is no anti-reflection between the GRIN lens 102 and the optical fiber or optical waveguide in the adapter.

[0056] The GRIN lens can be positioned and mounted on the silicon photonics chip by any method, and may be passively mounted using active alignment or in-plane mechanical precision standards of the packaging material, electrical contacts, and positioning structures.

[0057] According to the package structure of the present embodiment, there is no need to directly adhesively fix an optical fiber to the silicon photonics chip, and the silicon photonics chip can be packaged while avoiding any influence on the optical fiber connection during the manufacturing process of the package structure.

[0058] The optical fiber connection is realized by fitting the adapter 107 or the first ferrules 107_1 and 107_2 with the ferrule 108 or the second ferrules 108_1 and 108_2, respectively, and then actively aligning the exposed GRIN lens and adhesively fixing the respective interfaces.

[0059] After bonding, the ferrule 108 or the second ferrules 108_1 and 108_2 can be removed and refitted because it is a connector system. Therefore, the next process such as PCB mounting can be carried out without the optical fiber, and the conventional problem of the difficulty in handling the pigtail optical fiber can be solved.

[0060] In addition, the package structure according to this embodiment has the advantage that the silicon photonics chip can be freely arranged in the molded package by using a GRIN lens in a molded package form as shown in FIGS. 1 to 3.

[0061] In other words, when directly connecting a silicon photonics chip and an optical fiber array in a conventional molded package, it was necessary to place the end face of the silicon photonics chip on the same plane as the end face of the package or very close to the end face of the package, which imposed significant constraints in terms of electrical wiring and package design.

[0062] On the other hand, by providing a GRIN lens, it becomes possible to place the silicon photonics chip in the center for the length of the GRIN lens, greatly increasing the degree of freedom in electrical wiring access to the chip and electrical wiring with the BGA / LGA. The length of the GRIN lens can be flexibly changed by changing the refractive index distribution shape.

[0063] In addition, as shown in Figure 1, the electrical contacts of the silicon photonics chip are provided on the waveguide layer on the silicon substrate, so the distance between the silicon core and the substrate in the thickness direction is set to within a few tens of micrometers. On the other hand, the thickness of the V-groove substrate used in conventional fiber arrays needs to be about a few hundreds of micrometers.

[0064] Therefore, when a fiber array is directly bonded and fixed to an optical package using flip-chip connection, etc., using conventional methods, the V-groove substrate and the electrical mounting substrate mechanically interfere with each other. This problem is particularly noticeable in packaging forms that use a thin RDL layer. As a result, there are restrictions such as the need to provide a notch on the electrical mounting substrate or to mount the package on the edge of the electrical mounting substrate.

[0065] On the other hand, in the package structure according to the present embodiment, a GRIN lens is used so that the optical input / output section can be positioned higher in the thickness direction of the substrate than in the conventional position, that is, at a position away from the electrical mounting substrate. This eliminates the above-mentioned constraints on the mounting position, and enables a highly flexible mounting form to be realized.

[0066] Similarly, in the face-up configuration shown in FIGS. 2 and 3, if the ferrule 108 or the adapter 107 interferes with the electrical mounting board (not shown) connected downward via the electrical connection portion 106 (BGA, etc.), the lens optical system may be configured to be positioned upward as appropriate, similar to the light rays inside the lens in FIG. 1.

[0067] In this embodiment, an example of using a bulk GRIN lens as the optical path conversion unit has been shown, but any other lens that exhibits a similar optical function can be used. For example, a known GI (Graded Index) fiber can be used. Since the GI fiber has a small diameter and high external shape accuracy, it is easy to form it larger than that, and a GI fiber array can be used according to the number of channels of the chip. In addition, a Fresnel lens or a metasurface lens can be used. Any other lens can be used as long as it has the function of emitting light incident from one end face from the other end face with the central axis of the optical path conversion unit as the axis of symmetry.

[0068] In addition, in applications that do not require a detachable connection structure, as shown in FIG. 6, the GRIN lens end face of the package structure and the fiber array (fiber block) 113 may be directly adhesively fixed together, without using the detachable structure using the adapter and ferrule described above.

[0069] <Second embodiment> An optical connection structure, a package structure, and an optical module according to a second embodiment of the present invention will be described with reference to FIGS.

[0070] <Optical connection structure, package structure and optical module configuration> The optical module 2 according to the present embodiment differs from the first embodiment in that the GRIN lens is divided into a first GRIN lens 2021 and a second GRIN lens 2022. The other configurations are substantially similar to those of the first embodiment.

[0071] In the configuration shown in FIG. 7, an example is shown in which a face-down type silicon photonics chip 101 is used.

[0072] In the package structure 21, the pitch of each of the first GRIN lens 2021 and the second GRIN lens 2022 is about 0.25 (P=0.25), and the length is about 4.6 mm.

[0073] Light from the silicon photonics chip 101 enters one end face of the first GRIN lens 2021 (the left end face in Figure 7), and passes through the other end face of the first GRIN lens 2021 (the right end face in Figure 7) and one end face of the second GRIN lens 2022 (the left end face in Figure 7), and is imaged on the other end face of the second GRIN lens 2022 (the right end face in Figure 7).

[0074] Only the first GRIN lens 2021 is covered with the mold resin 105, and the other end face of the first GRIN lens 2021 (the end face on the right side in FIG. 7) is exposed from the mold resin 105.

[0075] The second GRIN lens 2022 is incorporated in the adapter 2071 .

[0076] 8 shows a case where a face-up type silicon photonics chip 101 is used. Since light can be propagated near the central axes of the GRIN lenses 2021 and 2022, the size of the adapter 2072 can be reduced.

[0077] The package structure shown in Figure 9, like the package structure shown in Figure 3, is an example that uses a substrate 1042 such as an organic build-up substrate or a ceramic substrate, and only the portion of the substrate 1042 on which the first GRIN lens 2021 is mounted is made thinner than the portion on which the silicon photonics chip 101 is mounted.

[0078] The first GRIN lens 2021 and the second GRIN lens 2022 may be GRIN lenses with different characteristics. For example, by using the second GRIN lens 2022 having a refractive index distribution constant (√A) larger than that of the first GRIN lens 2021, the overall length can be shortened and the spot size at the other end face of the second GRIN lens 2022 (the end face on the right side in FIG. 7) can be changed.

[0079] Moreover, in addition to the second GRIN lens 2022, optical waveguide components (not shown) can also be built into the adapters 2071 and 2072. By using a spot size conversion circuit, an optical system, or an NA expansion fiber (TEC fiber), a polymer waveguide, a glass waveguide, or the like as the optical waveguide components, the NA (spot size) on the input side and the output side can be changed, and it becomes possible to guide light to the optical fiber 109 with lower loss.

[0080] In this embodiment, the interface between the first GRIN lens 2021 and the second GRIN lens 2022 serves as an alignment surface and an adhesive fixing surface. Unlike the first embodiment, coupling is performed using thick collimated light, so as long as the dimensional accuracy of the optical components is sufficient, active alignment is not necessarily required.

[0081] In this embodiment, similarly to the configurations shown in FIGS. 4 and 5, a multi-core ferrule or a single-core ferrule can be used.

[0082] The optical fiber is connected by fitting the adapters 2071 and 2072 into the ferrule 108, aligning them with the exposed first GRIN lens 2021, and adhesively fixing them.

[0083] After bonding, the ferrule 108 or the second ferrules 108_1 and 108_2 (not shown) can be removed and refitted because of the connector system. Therefore, the next process such as PCB mounting can be carried out without the optical fiber, and the conventional problem of the difficulty in handling the pigtail optical fiber can be eliminated.

[0084] According to the package structure of this embodiment, similarly to the first embodiment, there is no need to directly adhesively fix an optical fiber to the silicon photonics chip, and the silicon photonics chip can be packaged while avoiding any influence on the optical fiber connection in the manufacturing process of the package structure.

[0085] Also, similarly to the first embodiment, there is an effect that the mounting position of the silicon photonics chip within the mold package can be freely arranged.

[0086] Furthermore, as in the first embodiment, the use of a GRIN lens makes it possible to position the optical input / output section higher in the thickness direction of the substrate than in the conventional position, i.e., at a position away from the electrical mounting substrate. This eliminates the above-mentioned restriction on the mounting position, thereby enabling a highly flexible mounting form to be realized.

[0087] In the embodiment of the present invention, an example in which light is emitted from a silicon photonics chip has been shown, but light can also be made incident on a silicon photonics chip. In this case, the light incident from the optical fiber fixed to the ferrule travels in the reverse direction from the above, passes through an adapter, enters the other end face of the GRIN lens at a high position (the end face on the right side in FIG. 1), and is imaged (incident) at a low position on one end face of the GRIN lens (the end face on the left side in FIG. 1).

[0088] In the embodiment of the present invention, for ease of explanation, an image is formed on the output end face of the GRIN lens, but since it is necessary to take into account the optical path length propagating inside the adapter, the image is not necessarily formed on the output end face of the GRIN lens. The image may be formed on the end face of the adapter, or it is sufficient that the light propagates within a range that allows operation as a package structure even if the image is not completely formed (even if it is not in focus).

[0089] In this way, in the package structure according to the embodiment of the present invention, the length of the GRIN lens determines the focusing state of the output light, such as the focal diameter, making it easy to design the optical system. Also, when light is input with an offset from the central axis, it is imaged and output at a position symmetrical to the central axis.

[0090] The propagation of light in an embodiment of the present invention will be described with reference to Fig. 10, taking the optical connection structure 10 as an example. Fig. 10 is a schematic top view of the optical connection structure 10 for explaining the propagation path of light. Here, dotted line 112_1 and dashed line 12_2 in the figure indicate the path of light propagating within the GRIN lens 102.

[0091] When viewing the propagation of light in the optical connection structure 10 from above, as shown in FIG. 10, light input from different optical fibers 109_1, 109_3 propagates (concentrates) through different paths 12_1, 12_2 by the GRIN lens 102 and is input (coupled) to different waveguides 1012, 1013 of the silicon photonics chip 101.

[0092] The light propagating through the waveguides 1012 and 1013 is output from the silicon photonics chip 101, propagates (collects) through different paths 12_1 and 12_2 by the GRIN lens 102, and is input (coupled) through the adapter 107 to different optical fibers 109_2 and 109_4.

[0093] Here, the silicon photonics chip 101 includes, as an example, an optical device 1011, a first waveguide 1012, and a second waveguide 1013. Here, a modulator is used as the optical device 1101, but a mixer, a photodiode, or the like may also be used. The modulator 1101 is connected to the first waveguide 1102, modulates input light to generate an optical signal, and the optical signal propagates through the first waveguide 1102. The second waveguide 1103 is used for adjusting and aligning the position of components in the manufacturing process of the package structure 11 (described later).

[0094] In this way, by using the GRIN lens 102, the optical connection structure 10 according to the embodiment of the present invention can easily input input light from different optical fibers to different waveguides of the silicon photonics chip 101, and input output light from the different waveguides to different optical fibers.

[0095] Active alignment in the manufacture of a packaging structure according to an embodiment of the present invention will now be described.

[0096] A ferrule 108 to which a multi-core optical fiber 109 including optical fibers 109_3 and 109_4 is fixed is connected to an adapter 107 and fixed with a clip 110 for the silicon photonics chip 101 and the GRIN lens 102 fixed with a molding resin 105 .

[0097] Next, the light for alignment is input to the optical fiber 109_3, and propagates in this order through the adapter 107 and the GRIN lens 208 to the silicon photonics chip 101.

[0098] Here, the silicon photonics chip 101 has a loopback optical circuit (second waveguide) 1013 for core alignment, as shown in FIG.

[0099] In this configuration, as described above, the light for alignment input from optical fiber 109_3 is incident on the other end face (right side in Figure 10) of GRIN lens 102, propagates through path 12_2, inputs (couples) to the second waveguide 1013 of the silicon photonics chip 101, propagates through the second waveguide 1013, and is output from the silicon photonics chip 101.

[0100] The light output from the silicon photonics chip 101 is incident on one end face of the GRIN lens 102 (left side in Figure 10), propagates along path 12_2, is focused on the other end face of the GRIN lens 102 (right side in Figure 10), and is input to the optical fiber 109_4 via the adapter 107.

[0101] The intensity (amount of light) of the light output from the other end of the optical fiber 109_4 is measured, and the adaptor 107 is positioned (aligned) so that the intensity (amount of light) of the light is maximized.

[0102] In the embodiment of the present invention, the use of a molding resin can improve the rigidity and mass productivity of the package.

[0103] Conventionally, structures using mold resin have been used for electrical and electronic components with a component positional accuracy of about 10 μm.

[0104] On the other hand, optical components require high-precision alignment of about 0.1 μm and high reliability, making it difficult to use a configuration using molded resin. Also, when silicon photonics and optical fiber are adhesively fixed, the durability and stability of the adhesive fixation in the process of fixing each component with a mold is insufficient, and the optical axis cannot be adjusted after the process of fixing each component with a mold, making it difficult to adjust the position of the components and the optical axis with high precision.

[0105] In an embodiment of the present invention, there is no need to directly adhesively fix the silicon photonics chip and the optical fiber, and the optical axis can be adjusted after each component is fixed with a mold, so that molding resin can be used to mount the optical components.

[0106] Similarly, since there is no need to directly glue and fix the silicon photonics chip and the optical fiber, FOWLP and FOPLP can be used to mount optical components.

[0107] In an embodiment of the present invention, in an application that does not require a detachable connection structure, the GRIN lens end face of the package structure and the fiber array may be directly adhesively fixed without using the detachable structure using the adapter and ferrule described above.

[0108] In the embodiment of the present invention, the structure, dimensions, materials, etc. of each component in the configuration of the package structure, the manufacturing method, etc. are shown as examples, but the present invention is not limited to these. Anything that can exhibit the function and effect of the package structure may be used. [Industrial Applicability]

[0109] The present invention relates to an optical module of an optical component, and can be applied to devices and systems for optical communications and the like. [Explanation of symbols]

[0110] 1 Optical module 10 Optical connection structure 11 Package Structure 101 Silicon photonics chip (optical element) 102 GRIN lens (optical path conversion part) 103 IC 1041 Circuit Board 105 Molding resin 106 Electrical Connections 107 Adapter 108 Ferrule 109 Optical Fiber

Claims

1. An optical connection structure in a package structure connected to an optical fiber and having a substrate, an optical element disposed on the substrate and having an optical circuit; an optical path changing unit disposed on the substrate; an adapter for detachably connecting the optical fiber; Equipped with a surface of the optical element having the optical circuit and one surface of the substrate are opposed to each other; one end face of the optical path changing unit faces an end face of the optical element, The input and output light of the optical path changing unit is propagated symmetrically with respect to the central axis of the optical path changing unit between the one end face and the other end face. An optical connection structure comprising:

2. the optical path changing units are respectively connected to a plurality of first ferrules serving as the adapters, the plurality of first ferrules are respectively connected to a plurality of second ferrules; The optical fiber is fixed to the second ferrule.

2. The optical connection structure according to claim 1 .

3. Another optical path changer is provided between the optical path changer and the optical fiber.

3. The optical connection structure according to claim 1 or 2.

4. The optical connection structure according to any one of claims 1 to 3, The substrate; a molding resin that covers the optical element and the optical path conversion unit; A package structure comprising:

5. In the substrate, a portion where the optical path conversion unit is arranged is thinner than a portion where the optical element is arranged.

5. The package structure according to claim 4.

6. A package structure according to claim 4 or claim 5; An optical fiber; Ferrule and An optical module comprising:

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