Patent Application
20240159969
The present invention relates to an optical connecting structure used for connecting an optical element and an optical fiber, a package structure, an optical module, and a method of manufacturing the package structure.
With a recent rapid increase in Internet traffic, it has been required to increase communication capacity of a data center network. Further, in order to meet an increase in transmission capacity and a reduction in power consumption, optical interconnection for optical transmission has been introduced even in short or medium range applications.
In a typical method of the optical interconnection, signal processing is achieved by transmission between a light emitting element such as a laser diode (LD) arranged on a printed circuit board and a light receiving element such as a photodiode (PD) arranged thereon by using an optical transmission medium such as an optical waveguide or an optical fiber.
Depending on a transmission method, an optical modulator and the like are integrated in the light emitting element or are discretely connected thereto, and the light emitting element is further connected to, for example, a driver that performs electro-optic conversion. A configuration including the light emitting element, the optical modulator, the driver, and the like is mounted as an optical transmitter on an electric mounting board such as a printed circuit board (PCB).
Similarly, an optical processor and the like are integrated in the light receiving element or are discretely connected thereto, and the light receiving element is further connected to, for example, an electric amplifier circuit that performs optic-electro conversion. A configuration including the light receiving element, the optical processor, the electric amplifier circuit, and the like is mounted as an optical receiver on a printed circuit board.
An optical transmitter/receiver or the like, which is obtained by integrating the optical transmitter with the optical receiver, is mounted in a package or on a printed circuit board and is optically connected to an optical transmission medium such as an optical fiber, thereby achieving optical interconnection. Depending on topology, the optical interconnection is achieved via a relay such as an optical switch.
In conventional optical interconnection (a mounting structure of optical components), each component is (discretely) mounted in an individual package. However, it is difficult to collectively manufacture and mass-produce the above mounting structures.
As a technique for mounting electrical and electronic components, fan-out wafer-level packaging (FOWLP) for packaging components on a wafer has high mass productivity and has been implemented in recent years. In fan-out panel-level packaging (FOPLP) for packaging components on a panel (panel level), the components can be mounted in a larger area than that of FOWLP, thereby having higher mass productivity.
Meanwhile, the light emitting element, the light receiving element, and the optical modulator used for the optical interconnection are practically applied as elements made from materials such as semiconductors including silicon and germanium or III-V semiconductors represented by indium phosphide (InP), gallium arsenide (GaAs), indium gallium arsenide (InGaAs), and the like. There has recently been developed an optical waveguiding optical transmitter/receiver in which a silicon optical circuit (silicon photonics), an indium phosphide optical circuit, or the like having a light propagation mechanism is integrated together with the above elements. The optical modulator may be made from not only semiconductors but also ferroelectric materials such as lithium niobate or polymers.
An optical functional element including, for example, a planar lightwave circuit made from quartz glass or the like may be further integrated together with the above light emitting element, light receiving element, and optical modulator. Examples of the optical functional element include a splitter, a wavelength multiplexer/demultiplexer, an optical switch, a polarization control element, and an optical filter. Hereinafter, a device in which the light emitting element, the light receiving element, the optical modulator, the optical functional element, an optical amplifier, and the like having the optical propagation and waveguide mechanisms are integrated will be referred to as an optical waveguide device.
In the optical waveguide device, a silicon photonics chip has high integration, high mass productivity, and high affinity with electrical components and draws attention as a key device for achieving next-generation optical interconnection (Non Patent Literature 1).
A method of connecting an optical transmitter/receiver in which a silicon photonics chip, a driver, an electric amplifier circuit, and the like are integrated to electric wiring on a board is wire bonding, flip chip connection, or connection using a ball-grid array (BGA), land-grid array (LGA), pin-grid array (PGA), copper pillar, or the like. In those connections, the optical transmitter/receiver may be connected to an electric mounting board via another package substrate such as an interposer component as necessary.
One method of connecting a silicon photonics chip to an optical fiber is a structure that connects the silicon photonics chip to an optical fiber array integrated with glass or the like having a V-shaped groove. In the structure, in order to connect a core of each optical fiber and a core of each waveguide of the optical waveguide device with low loss, the optical waveguide device and the optical fiber are positioned (hereinafter, referred to as aligned) in submicrons and are then adhesively fixed.
However, the structure in which the optical fiber is adhesively connected to the silicon photonics chip has low durability against heat treatment or other processes in FOWLP or FOPLP. Therefore, it is difficult to use FOWLP or FOPLP for mounting optical components.
Further, the conventional structure in which the optical fiber is adhesively connected to the silicon photonics chip by using an adhesive or the like has the following problems.
In order to cause the optical fiber array to directly adhere to the silicon photonics chip, it is necessary to optically polish an end surface of the silicon photonics chip.
Further, a side surface of the chip is an adhesive surface, and thus an adhesion area is limited. This makes it difficult to obtain sufficient adhesive force.
Furthermore, the optical fiber is fixedly connected as a pigtail, and thus, in the next board mounting or other processes, it is necessary to perform, for example, a process for maintaining (stabilizing) the fixed connection state of the optical fiber. This reduces mass productivity (improvement in throughput and stabilization) of an assembly process.
As described above, the structure that adhesively connects the optical fiber to the silicon photonics chip in the package structure and the optical module has problems.
Further, in order to use FOWLP or FOPLP for mounting optical components, it is necessary to connect the silicon photonics chip and the optical fiber, without adhesively connecting the silicon photonics chip and the optical fiber.
In order to solve the above problems, an optical connecting structure according to embodiments of the present invention is an optical connecting structure in a package structure connected to an optical fiber and including a first electric wiring board and a second electric wiring board facing the first electric wiring board, the optical connecting structure including: an optical element arranged on either the first electric wiring board or the second electric wiring board; and a GRIN lens arranged on a surface of the second electric wiring board facing the first electric wiring board, in which one end surface of the GRIN lens faces an end surface of the optical element.
A method of manufacturing a package structure according to embodiments of the present invention includes: a step of mounting an optical element including a waveguide for alignment on a surface near an opening of a first electric wiring board; a step of mounting a GRIN lens on a surface of a second electric wiring board; a step of causing the GRIN lens to pass through the opening of the first electric wiring board, causing the surface of the first electric wiring board and the surface of the second electric wiring board to face each other, and bonding the first electric wiring board and the second electric wiring board; a step of forming a molding resin between the first electric wiring board and the second electric wiring board; a step of arranging an adapter so as to input and output light between the adapter and the GRIN lens; a step of detachably connecting a ferrule to which a multicore optical fiber is fixed to the adapter; a step of inputting light to one optical fiber of the multicore optical fiber; a step of measuring an intensity of the light propagated through the waveguide and output from another optical fiber of the multicore optical fiber; and a step of moving positions of the reflection structure and the adapter to fix the reflection structure and the adapter at the positions where the intensity of the light is maximum.
According to embodiments of the present invention, it is possible to provide an optical connecting structure, a package structure, an optical module, and a method of manufacturing the package structure capable of improving mass productivity, without causing an optical fiber to directly adhere to a silicon photonics chip.
An optical connecting structure, a package structure, and an optical module according to a first embodiment of the present invention will be described with reference to
The optical module 1 according to the present embodiment includes a package structure 11, a ferrule 112, and an optical fiber 113. The optical fiber 113 is fixed to the ferrule 112. The package structure 11 and the ferrule 112 are fixed by using a clip 114.
The optical fiber 113 is a multicore optical fiber and includes a plurality of optical fibers. In the following embodiments of the present invention, the optical fiber 113 includes a plurality of optical fibers 113_1, 113_2, 113_3, and 113_4 as an example.
In the package structure 11, a first electric wiring board 104 and a second electric wiring board 105 are arranged to face each other.
A silicon photonics chip 101, an IC 102_1, and a passive component 103_1 are arranged on a lower surface of the first electric wiring board 104, in other words, on a surface facing the second electric wiring board 105.
An IC 102_2, a passive component 103_2, and a prism 110 are arranged on an upper surface of the first electric wiring board 104, in other words, on a surface opposite to the surface facing the second electric wiring board 105.
The silicon photonics chip 101 may be arranged not only on the lower surface of the first electric wiring board 104 but also on an upper surface of the second electric wiring board 105 and only needs to be arranged between the first electric wiring board 104 and the second electric wiring board 105.
A gradient index (GRIN) lens 108 is arranged on the upper surface of the second electric wiring board 105, in other words, on a surface facing the first electric wiring board 104.
One end surface of the GRIN lens 108 is close to the silicon photonics chip 101. The other end surface of the GRIN lens 108 is close to the prism 110 mounted on the upper surface of the first electric wiring board 104.
The first electric wiring board 104 is, for example, a thin multilayer printed wiring board and has a thickness of 100 μm. The GRIN lens 108 is arranged to pass through an opening provided in a part of the first electric wiring board 104.
The first electric wiring board 104 and the second electric wiring board 105 are electrically connected via a connection terminal 106 and have a gap filled with a molding resin 107. The connection terminal 106 is, for example, a copper pillar, a copper pin, or a solder ball.
Electric connection portions 109 are formed on a lower surface of the second electric wiring board 105 and serve as an electric interface with an electric mounting board (not illustrated) such as a PCB on which an optical package is mounted. The electric connection portions 109 are BGA balls or an LGA pad.
The prism 110 is adhesively fixed to the upper surface of the first electric wiring board 104. An adapter 111 is arranged on an upper surface of the prism 110, in other words, on a surface opposite to a surface in contact with the first electric wiring board 104, and is adhesively fixed thereto.
The prism 110 may be a mirror and only needs to have a structure (hereinafter, also referred to as “reflection structure”) having a reflection function of converting a substantially horizontal optical path input to and output from the silicon photonics chip 101 and a substantially vertical optical path input to and output from the adapter 111.
The ferrule 112 is not adhesively fixed to the adapter 111 and is a detachable connector interface.
The ferrule 112 and the adapter 111 may be rectangular or cylindrical. In a case where the ferrule 112 and the adapter 111 are rectangular components, both the ferrule and the adapter are connected with high accuracy by providing two round holes for guide pins in both the ferrule and the adapter and inserting guide pins (not illustrated) into the round holes, as in a method of fitting an MT ferrule.
The clip 114 is used to hold the contact between both the ferrule and the adapter. In a case where the ferrule and the adapter are cylindrical components, the ferrule and the adapter are connected by using a cylindrical sleeve or a split sleeve, as in a method of fitting an LC ferrule.
The GRIN lens 108 is a cylindrical optical component and is a gradient index lens in which the refractive index is parabolically changed from a center axis 108_1 of the cylinder toward an outer peripheral portion. A focal length of the GRIN lens is changed by changing a length thereof, and a lens characteristic thereof is expressed by Expression (1).
Expression (1): Z=2πP/√A (1)
Z denotes the length of the GRIN lens, VA denotes a refractive index distribution constant determined based on a material or manufacturing method, and P denotes a pitch representing a meandering period of a light beam passing through the lens.
The GRIN lens 108 in
In the silicon photonics chip 101, for example, a modulator, a mixer circuit, a photodiode, and the like are formed together with a waveguide.
The passive components 103_1 and 103_2 are, for example, capacitors or optical splitters.
In the package structure 11 according to the present embodiment, light output from the silicon photonics chip 101 sequentially propagates through the GRIN lens 108, the prism 110, and the adapter 11 and is input to the optical fiber 113 fixed to the ferrule 112. Meanwhile, light input from the optical fiber 113 sequentially propagates through the adapter 111, the prism 110, and the GRIN lens 108 and is input to the silicon photonics chip 101.
The optical connecting structure 10 includes the silicon photonics chip 101, the GRIN lens 108, the prism 110, and the adapter 111. Hereinafter, propagation of light in the optical connecting structure 10 will be described with reference to
When the propagation of the light in the optical connecting structure 10 is viewed from the top, as illustrated in
The light beams propagated through the waveguides 1012 and 1013 are output from the silicon photonics chip 101, are propagated (condensed) by the GRIN lens 108 through the different paths 116_1 and 1162, and are input (coupled) to different optical fibers 113_2 and 113_4 via the prism 110 and the adapter 111.
The silicon photonics chip 101 herein includes, as an example, an optical element 1011, the first waveguide 1012, and the second waveguide 1013. In the present embodiment, the optical element 1101 is a modulator, but may be, for example, a mixer or a photodiode. The optical element 1101 is connected to the first waveguide 1102 and modulates input light to generate an optical signal, and the optical signal propagates through the first waveguide 1102. The second waveguide 1103 is used to adjust and align positions of components in a manufacturing process of the package structure 11 (described later).
As described above, the optical connecting structure 10 according to the present embodiment uses the GRIN lens 108. This makes it possible to easily input light input from different optical fibers to different waveguides of the silicon photonics chip 101 and to easily input light output from different waveguides to different optical fibers.
Next, vertical propagation of light in the optical connecting structure 10 will be described by exemplifying propagation of light output from the silicon photonics chip 101.
In the optical connecting structure 10, the silicon photonics chip 101 has a standard wafer thickness of 625 μm, and the first electric wiring board 104 and the second electric wiring board 105 have a gap of 800 μm.
The silicon photonics chip 101 is mounted below the first electric wiring board 104 in a “face-down” manner via the copper pillar (not illustrated) having a height of 40 μm provided on a surface (circuit surface) of the first electric wiring board. As a result, a light input/output portion of the silicon photonics chip 101 is arranged at a position about 40 μm lower than the lower surface of the first electric wiring board 104, in other words, at a position about 760 μm higher than the upper surface of the second electric wiring board 105.
As illustrated in
The light incident on the GRIN lens 108 is bent and propagated through the GRIN lens 108 according to a refractive index distribution, travels at 0.5 pitch (Z≈9.6 mm), and forms an image at a position offset upward by about 140 μm from the center axis 108_1 on the other end surface (right side in
The light output from the GRIN lens 108 is subjected to optical path conversion of about 90° by the prism 110 and is guided to the optical fiber 113 via the adapter 111 and the ferrule 112.
Meanwhile, light input from the optical fiber 113 is incident over the first electric wiring board 104 on the other end surface (right side in
The light propagating through the silicon photonics chip 101 may be output from a light emitting element such as a semiconductor laser mounted in the package structure 11.
In the present embodiment,
As described above, in the package structure according to the present embodiment, a condensing state such as a focal diameter of output light is determined based on the length of the GRIN lens. Therefore, an optical system can be easily designed. Further, in a case where light is input with an offset from the center axis, an image is formed at a position symmetrical with respect to the center axis and is then output.
In the present embodiment, the center axis of the GRIN lens is arranged in substantially the same plane as the first electric wiring board. Therefore, it is possible to easily and optically accurately output light input to the GRIN lens from the silicon photonics chip arranged below the first electric wiring board so as to form an image at a position above the first electric wiring board symmetrical with respect to the center axis of the GRIN lens.
It is also possible to easily and optically accurately output light input to the GRIN lens from the prism arranged above the first electric wiring board so as to form an image at a position below the first electric wiring board symmetrical with respect to the center axis of the GRIN lens.
Here, “substantially the same plane as the first electric wiring board” includes the upper surface or lower surface (bottom surface) of the first electric wiring board and also includes a horizontal plane positioned between the upper surface and the lower surface. Therefore, the center axis of the GRIN lens is desirably parallel to the upper surface or the lower surface (bottom surface) of the first electric wiring board. The center axis of the GRIN lens is substantially parallel to the x direction in
An optical connecting structure, a package structure, and an optical module according to a second embodiment of the present invention will be described with reference to
An optical module 2 according to the present embodiment has a substantially similar configuration to the optical module 1 according to the first embodiment, but a configuration of an optical connecting structure 20 in a package structure 21 is different.
The optical connecting structure 20 according to the present embodiment includes the silicon photonics chip 101, a GRIN lens 208, the prism 110, and the adapter 11.
The GRIN lens 208 has 0.25 pitch (about 4.8 mm). The pitch of the GRIN lens 208 is preferably 0.2 or more and 0.3 or less.
A reflective film 215 is further provided on an end surface (the other end surface) of the GRIN lens 208 opposite to an end surface (one end surface) close to the silicon photonics chip 101. The reflective film 215 is formed on the other end surface of the GRIN lens 208 by, for example, coating a reflective material (e.g., gold) or bonding a mirror component.
The prism 110 and the adapter 11 are arranged at the center of the package structure 21, as compared with the first embodiment.
In the optical connecting structure 20 according to the present embodiment, input/output light in the silicon photonics chip 101 propagates through the GRIN lens 208, the prism 110, and the adapter 111 in a substantially similar way to the first embodiment, but a path of the light in the GRIN lens 208 is different.
Hereinafter, propagation of light in the optical connecting structure 20 will be described with reference to
Solid lines 216 in
As an example, the silicon photonics chip 101 has a similar configuration to that of the first embodiment. The first waveguide 1102 is a waveguide for optical signals. The second waveguide 1103 is used to adjust and align positions of components in a manufacturing process of the package structure 11 (described later).
When the propagation of the light in the optical connecting structure 20 is viewed from above, light beams input from different optical fibers 113_1 and 113_3 are propagated (condensed) by the GRIN lens 208 through different paths 216_1_1 and 216_2_1 and are reflected by the reflective film 215 (20_1 in
The reflected light beams are propagated (condensed) through the paths 216_1_2 and 216_2_2 in a region below the first electric wiring board 104 of the GRIN lens 208 and are input (coupled) to the different waveguides 1012 and 1013 of the silicon photonics chip 101, respectively (20_2 in
The light beams propagated through the waveguides 1012 and 1013 are output from the silicon photonics chip 101, are propagated (condensed) through the different paths 116_1_3 and 116_2_3 in the region below the first electric wiring board 104 of the GRIN lens 208, and are reflected by the reflective film 215 (20_2 in
The reflected light beams are propagated (condensed) through the paths 216_1_4 and 216_2_4 in a region above the first electric wiring board 104 of the GRIN lens 208 and are input (coupled) to the different optical fibers 113_2 and 113_4 via the prism 110 and the adapter 111 (20_1 in
As described above, the optical connecting structure 20 according to the present embodiment uses the GRIN lens 208. This makes it possible to easily input light input from different optical fibers to different waveguides of the silicon photonics chip 101 and to easily input light output from different waveguides to different optical fibers.
Next, vertical propagation of light in the optical connecting structure 20 will be described by exemplifying propagation of light output from the silicon photonics chip 101.
As illustrated in
The light propagated through the GRIN lens 208 is reflected by the reflective film 215 on the other end surface (right side in
The light output from the GRIN lens 208 is subjected to optical path conversion of about 90° by the prism 110 and is guided to the optical fiber 113 via the adapter 11 and the ferrule 112.
Meanwhile, light input from the optical fiber 113 is incident over the first electric wiring board 104 on the one end surface (left side in
As described above, in the package structure according to the present embodiment, the center axis of the GRIN lens is arranged in substantially the same plane as the first electric wiring board, as in the first embodiment. Therefore, light input over the first electric wiring board can form an image below the first electric wiring board, whereas light input below the first electric wiring board can form an image above the first electric wiring board, and thus the light can be output easily and optically accurately.
Further, the length of the GRIN lens 208 can be reduced by about half in the optical connecting structure according to the present embodiment. This makes it possible to reduce the size of the entire package structure.
An example of a method of manufacturing the package structure 21 according to the present embodiment will be described with reference to
First, the first electric wiring board 104 is fabricated (
Alternatively, the first electric wiring board 104 may be a coreless substrate including only the buildup layer without using a core layer. Using the coreless substrate is desirable in the present embodiment because a thickness of the first electric wiring board 104 can be reduced.
Further, a rectangular opening for allowing the GRIN lens 208 to pass therethrough is provided in a part of the first electric wiring board 104 by laser or drilling (dotted lines in
Next, the silicon photonics chip 101 and the IC 102_1 are mounted on a surface of the first electric wiring board 104 via copper pillars, solder bumps, or the like (
Meanwhile, in parallel with the fabrication of the first electric wiring board 104, the second electric wiring board 105 is fabricated (
Next, the connection terminal 106 and the GRIN lens 208 are formed on a surface of the second electric wiring board 105 (
The GRIN lens 208 is directly adhesively fixed at a predetermined position of the second electric wiring board 105. Alternatively, a metal pattern may be formed on a bottom surface of the GRIN lens 208 or a bottom surface of a holder component of the GRIN lens 208 and then be metal-bonded to the second electric wiring board 105.
Next, the first electric wiring board 104 and the second electric wiring board 105 are bonded at panel level while surfaces of both the electric wiring boards are facing each other (
A back surface of the second electric wiring board 105 serves as a bottom surface (lower surface) of the package structure 21, and a front surface of the second electric wiring board 105 serves as the upper surface of the second electric wiring board 105 in the package structure 21.
Therefore, the silicon photonics chip 101, the IC 102_1, and the passive component 103_1 are mounted on the lower surface of the first electric wiring board 104. In other words, the silicon photonics chip 101 is arranged between the first electric wiring board 104 and the second electric wiring board 105 facing each other.
The GRIN lens 208 is mounted on the upper surface of the second electric wiring board 105 by passing through the opening provided in the first electric wiring board 104.
The first electric wiring board 104 and the second electric wiring board 105 are electrically connected by the connection terminal 106.
Next, in order to increase mechanical strength of the package, a gap between both the boards is filled with the molding resin 107, and the molding resin is cured (
Next, the prism 110 is arranged on the upper surface of the first electric wiring board 104 such that an inclined surface (reflective surface) of the prism is close to (faces) the emission end surface of the GRIN lens 208. Then, the adapter 111 is arranged on the prism 110 (
Hereinafter, adjustment of positions of the prism 110 and the adapter 111 will be described.
First, the ferrule 112 to which the multicore optical fiber 113 including the optical fibers 1133 and 113_4 is fixed is coupled to the adapter 111 and is fixed thereto by using the clip 114. The other end of the optical fiber 113_3 is connected to a light source for optical alignment, and the other end of the optical fiber 113_4 is connected to a photodetection device such as a photodetector (not illustrated).
Next, light for alignment is input from the light source to the optical fiber 113_3 and propagates to the silicon photonics chip 101 sequentially through the ferrule 112, the adapter 111, the prism 110, and the GRIN lens 208.
As illustrated in
In this configuration, as described above, the light for alignment input from the optical fiber 113_3 is reflected by the prism 110, is incident on the one end surface (left side in
The light output from the silicon photonics chip 101 is incident on the one end surface (left side in
The light for alignment is output from the other end of the optical fiber 113_4. An intensity (amount of light) of the output light is measured by the photodetector or the like connected to the other end of the optical fiber 113_4.
Next, the positions of the prism 110 and the adapter 111 are moved while the amount of light is being measured.
The prism 110 can move in a direction parallel to an optical axis of the GRIN lens 208 (an arrow 31 in
The adapter 111 can move in the direction parallel to the optical axis of the GRIN lens 208 (an arrow 32 in
Positions obtained by moving the positions of the prism 110 and the adapter 111 to maximize the amount of light to be measured are optimal positions of the prism 110 and the adapter 111.
Finally, in the optimal positions, the prism 110 is adhesively fixed to the first electric wiring board 104, and the adapter 111 is adhesively fixed to the prism 110. The fixing method herein is not limited to adhesion and may be metal bonding. Further, a holder member or housing having an appropriate adhesion area may be designed and used.
The prism 110 may be fixed to the GRIN lens 208, instead of being fixed to the first electric wiring board 104.
The positions of the prism 110 and the adapter 111 are adjusted as described above.
Next, the clip 114 is removed, and the ferrule 112 and the optical fiber 113 are removed from the package structure 21 (
Next, the IC 102_2 is mounted on the upper surface of the first electric wiring board 104 (
The optical fiber 113 has already been removed in this state, and thus it is possible to easily perform surface planarization (reflow) by high-temperature heat treatment at panel level, as in normal mounting of electronic components.
Finally, BGA balls serving as the electric connection portions 109 for secondary mounting are formed on the bottom surface of the second electric wiring board 105 (
Finally, packages are divided by dicing (not illustrated).
The method of manufacturing a package structure according to the embodiments of the present invention has been described by using the package structure according to the second embodiment as an example. However, the method can also be applied to the package structure according to the first embodiment.
In the embodiments of the present invention, rigidity and mass productivity of the package can be improved by using a molding resin.
Components made from a molding resin have been conventionally used as electric and electronic components whose positional accuracy is about 10 μm.
Meanwhile, optical components are required to be positioned with high accuracy of about 0.1 μm and to have high reliability. Therefore, it is difficult to use components made from a molding resin. In a case where the silicon photonics and the optical fiber are adhesively fixed, durability and stability of adhesive fixation are insufficient in a process of fixing each component by molding, and the optical axis cannot be adjusted after the process of fixing each component by molding. Therefore, it is difficult to adjust the positions of the components and the optical axis with high accuracy.
In the embodiments of the present invention, the optical axis can be adjusted after each component is fixed by molding. Therefore, a molding resin can be used for mounting an optical component.
As illustrated in
As illustrated in
Meanwhile, as illustrated in
The above effect is exerted not only in the second embodiment but also in the first embodiment.
According to the embodiments of the present invention, it is unnecessary to directly adhesively fix the optical fiber to the silicon photonics chip. This makes it possible to easily package the silicon photonics chip.
Further, the package structure and the optical module can be collectively manufactured at panel level, including an optical fiber interface.
Because the optical fiber interface is a detachable connector, the IC mounting, the PCB mounting, and other processes can be performed while the optical fiber is not being connected. This makes it possible to improve mass productivity and economic efficiency of optical mounting.
The reflection structure (prism) is used in the embodiments of the present invention. However, the GRIN lens may be directly connected to the adapter, without using the reflection structure (prism). For example, in a configuration of
As illustrated in
In the configuration in which the GRIN lens is directly connected to the adapter as described above, light is input and output between the GRIN lens and the adapter.
In the method of manufacturing the package structure, in a case where the GRIN lenses 108 and 208 are directly connected to the adapter 11 without using the prism 110, the adapter 111 may be adhesively fixed to the first electric wiring board 104 or may be adhesively fixed to the GRIN lenses 108 and 208.
In the embodiments of the present invention, an example where the adapter includes one component has been described. However, the adapter may include a plurality of components and only needs to be detachably connected to the ferrule. For example, as illustrated in
The optical connecting structure according to the embodiments of the present invention includes the adapter as an example, but may not include the adapter. In this case, the optical fiber or the ferrule to which the optical fiber is fixed may be directly connected to the GRIN lens.
In the embodiments of the present invention, the silicon photonics chip is arranged between the first electric wiring board and the second electric wiring board as an example. However, the silicon photonics chip may be arranged on the upper surface of the first electric wiring board, in other words, on the surface opposite to the surface facing the second electric wiring board. In a configuration of
As described above, in the embodiments of the present invention, light input from one end surface of the GRIN lens propagates from one region to the other region of the GRIN lens 108 by using the horizontal plane including the center axis of the GRIN lens as a boundary and is output from the other end surface.
In the embodiments of the present invention, the silicon photonics chip separately includes a waveguide for optical signals and a waveguide for alignment as an example. However, the present invention is not limited thereto. As long as an optical element connected to the waveguide for optical signals can transmit light for alignment, the waveguide for optical signals may be used for alignment. Therefore, the waveguide for optical signals and the waveguide for alignment may not be separately provided. In a case where the optical element is a photodiode, the waveguide for optical signals only needs to have an input port.
In the embodiments of the present invention, the silicon photonics chip is mounted on the lower surface of the first electric wiring board in the face-down manner as an example. However, the silicon photonics chip may be mounted in a face-up manner. In that case, electrical connection to the first electric wiring board 104 is achieved by wire bonding or a through-silicon via (TSV).
The silicon photonics chip may be mounted on the upper surface of the second electric wiring board in either the face-up manner or the face-down manner. Even if any mounting method is used, light from the silicon photonics chip provided in the gap between the first electric wiring board and the second electric wiring board is guided to the upper surface side of the first electric wiring board by using a meandering propagation characteristic of the GRIN lens.
In the embodiments of the present invention, the silicon photonics chip is used as an example. However, the present invention is not limited thereto, and an optical waveguide device made from another material may be used. For example, a planar lightwave circuit made from quartz glass or the like or an optical waveguide device made from indium phosphide (InP) may be used. The optical waveguide device may not be made from a single material such as silicon. For example, the optical waveguide device may be a device in which an InP-based optical semiconductor light emitting element or a lithium niobate-based optical modulator is integrated on a chip.
Instead of the optical waveguide device, an optical element having no waveguide, such as a semiconductor laser or a photodiode, may be used. In this case, in the manufacturing process of the package structure, for example, the amount of light can be adjusted by measuring output light from the semiconductor laser by using the photodetection device at the other end of the optical fiber. Alternatively, the amount of light can be measured and adjusted by receiving input light from the light source at the other end of the optical fiber by the photodiode.
In the embodiments of the present invention, a multicore optical fiber including a plurality of optical fibers is used as an example, but a single core optical fiber may be used. The single core optical fiber can be used in a case where, for example, a semiconductor laser or a photodiode is used as the optical element as described above.
In the embodiments of the present invention, one GRIN lens is used as an example. However, a plurality of GRIN lenses may be used. For example, two GRIN lenses each may be used to propagate input light and output light. Alternatively, in a case where a plurality of adapters is arranged, light may be input and output between the plurality of GRIN lenses and the plurality of adapters.
In the embodiments of the present invention, a molding resin is used as an example, but the present invention is not limited thereto. The molding resin may not be used in a case where the components can be firmly mounted in the package structure.
The embodiments of the present invention show examples of the structures, dimensions, materials, and the like of the components in the configuration, manufacturing method, and the like of the package structure of the optical components. However, the present invention is not limited thereto. The embodiments of the present invention only need to have the function and effect of the package structure of the optical components.
The embodiments of the present invention relate to an optical module of an optical component and can be applied to devices and systems for optical communication or the like.
This application is a national phase entry of PCT Application No. PCT/JP2021/010038, filed on Mar. 12, 2021, which application is hereby incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/010038 | 3/12/2021 | WO |
