JP2004235418A - Optical module, optical communication apparatus, photoelectricity mixed loading integrated circuit, circuit board, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical module excellent in protection of a light emission face or a light receiving face of an optical device with a simplified structure, and preferable for the use of optical communication. <P>SOLUTION: The optical module (1) comprises an optical device (20) for emitting signal light in response to a supplied electric signal or generating an electric signal in response to the intensity of supplied signal light, a multilayer wiring (12, 14, 16) for transmitting the electric signal to the optical device (20), and a transparent substrate (10) optically transparent for a wavelength of the light emitted or received in the optical device (20) and supporting the optical device (20) and the multilayer wiring (12, 14, 16). The optical device (20) has its light emitting face or light receiving face in an opening part (21) provided in the multilayer wiring (12, 14, 16), and the signal light enters or emanates through the opening part (21) and the transparent substrate (10). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
[Industrial applications]
The present invention relates to a device, a component, and the like used for optical communication in which information communication (signal transmission) between a plurality of devices or inside a device is performed by an optical signal.
[0002]
[Prior art]
Some use optical fibers for local area networks (LANs), direct connections between computer devices, and interconnections between computer devices and digital audio / video equipment. Such an apparatus uses an optical transceiver that converts an electric signal into an optical signal and sends it to an optical fiber, and also converts an optical signal received from the optical fiber into an electric signal. In recent years, in addition to information communication between devices as described above, optical communication has also been introduced in signal transmission inside the device, and metal wiring is used between circuit chips or modules in the device. Instead of the conventional method of passing an electric signal, a method of passing an optical signal through an optical fiber (tape fiber) or an optical waveguide is being adopted.
[0003]
In such optical communication, a light-emitting element that converts an electric signal carrying transmission information into an optical signal, a light-receiving element that converts an optical signal carrying reception information into an electric signal, a driver that drives these light-emitting elements or light-receiving elements, and the like. Is required. Generally, these light-emitting elements, light-receiving elements, drivers, and the like are mounted on a wiring board having a wiring pattern made of copper or the like, perform signal transmission between them, and perform predetermined operations. As a wiring board on which such a light emitting element or the like is mounted, for example, a multilayer board disclosed in JP-A-2000-277661 is known.
[0004]
[Patent Document 1]
JP 2000-277661 A [Problems to be Solved by the Invention]
By the way, when a light emitting element or the like is mounted on a circuit board (multilayer substrate) as in the conventional example, the light emitting surface or the light receiving surface is generally arranged facing the opposite side of the element mounting surface of the circuit board. In this case, however, the light-emitting surface of the light-emitting element is exposed, and the protection is lacking, and there is an inconvenience that the amount of light emitted (or light-receiving efficiency) is easily reduced or damaged due to the attachment of dust or the like. On the other hand, it is not preferable to provide a member or the like for protecting the light emitting surface or the like, because the number of parts increases, the structure becomes complicated, and the number of manufacturing steps increases. Use of a light-emitting element or the like including a member for protecting a light-emitting surface or the like is not preferable because the cost increases accordingly.
[0005]
Therefore, an object of the present invention is to provide an optical module which has a simple structure, is excellent in protection of a light emitting surface or a light receiving surface of an optical element, and is suitable for use in optical communication.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an optical module according to the present invention includes: an optical element that emits a signal light according to a supplied electric signal or generates an electric signal according to the intensity of the supplied signal light; A multi-layer wiring for transmitting an electric signal to the element, and a transparent substrate that has a light-transmitting property with respect to the wavelength of light emitted or received in the optical element and supports the optical element and the multi-layer wiring; The light emitting surface or the light receiving surface of the element is disposed in an opening provided in the multilayer wiring, and signal light enters or exits through the opening and the transparent substrate.
[0007]
With this configuration, the light emitting surface or the light receiving surface of the optical element has a structure in which the light emitting surface or the light receiving surface of the optical element faces one surface of the transparent substrate, and thus the light emitting surface or the light receiving surface of the optical element can be protected with a simple structure.
[0008]
Here, in the present specification, the “transparent substrate” is not limited to a substrate having a light-transmitting property with respect to visible light as long as it has a light-transmitting property with respect to a wavelength of light used in an optical element. For example, when the wavelength of light used for the optical element is visible light or a value close to it (for example, 850 nm), a transparent substrate can be formed using a material such as glass or plastic, and the wavelength of light can be increased. When the wavelength is relatively long (for example, 1300 nm to 1500 nm), a transparent substrate can be formed using a material such as silicon or germanium.
[0009]
The above-described multilayer wiring is preferably a microstrip transmission line. By using a microstrip transmission line (microstrip line), it is easy to deal with high-frequency signals, and an optical module suitable for high-speed optical communication can be realized.
[0010]
Further, it is preferable that both the optical element and the multilayer wiring are arranged on one side of the transparent substrate. This facilitates electrical connection between the optical element and the multilayer wiring.
[0011]
In addition, the multilayer wiring is configured by laminating a common wiring layer, a dielectric layer, and a signal line layer on one surface of a transparent substrate, and the optical element is preferably arranged above the signal line layer. In this case, the common wiring layer is disposed between the other side of the transparent substrate and the optical element. Therefore, by connecting this common wiring layer to the ground potential, light can be transmitted from the other side of the transparent substrate. It becomes easy to suppress noise from entering the element.
[0012]
Further, the multilayer wiring is configured by laminating a signal line layer, a dielectric layer, and a common wiring layer on one surface of a transparent substrate, and it is preferable that the optical element is disposed above the signal line layer. In this case, since the number of layers disposed below the optical element is reduced, the height (thickness) of this region can be easily controlled, and the positional accuracy of the light emitting surface or the light receiving surface of the optical element (particularly, the horizontal position) Accuracy).
[0013]
Further, it is preferable to further include an optical element arranged on the other surface side of the transparent substrate and opposed to the light emitting surface or the light receiving surface of the optical element. Here, in this specification, the “optical element” refers to an element that gives some optical action (for example, refraction or diffraction) to incident light, and includes, for example, a lens and a diffraction grating. Since the optical element and the optical element are disposed to face each other with the transparent substrate interposed therebetween, a necessary optical distance between the optical element and the optical element can be secured by the thickness of the transparent substrate. Thereby, it is easier to secure the positional accuracy as compared with the case where the optical elements are independently arranged, and the assembling process can be simplified.
[0014]
The present invention is also an optical communication device (optical transceiver) including the above-described optical module. Such an optical communication device according to the present invention is used for various electronic devices such as a personal computer and a so-called PDA (portable information terminal device) that perform information communication with an external device or the like using light as a transmission medium. It is possible. In this specification, the term “optical communication device” refers not only to a device including both a configuration related to signal light transmission (light emitting element and the like) and a configuration related to signal light reception (light receiving device and the like) but also to a device for transmission. It includes a device having only such a configuration (a so-called optical transmission module) and a device having only a configuration for receiving (a so-called optical receiving module).
[0015]
The present invention is also an opto-electric hybrid integrated circuit including the above-described optical module, and is also a circuit board including the above-described optical module and an optical waveguide for transmitting signal light. Such a circuit board may be referred to as an “opto-electric hybrid board”.
[0016]
The present invention is also an electronic device including the above-described optical module. More specifically, in addition to the case where the electronic device of the present invention includes the optical module itself, the electronic device includes any of the above-described optical communication device, optical-electrical hybrid integrated circuit, and circuit board including the optical module. Including cases. As used herein, the term “electronic device” refers to a general device that realizes a certain function using an electronic circuit or the like, and its configuration is not particularly limited. For example, a personal computer, a PDA (portable information Terminal) and various devices such as an electronic organizer. The optical module, the optical communication device, the opto-electric hybrid integrated circuit or the circuit board according to the present invention can be used for information communication inside the device or information communication with an external device in these electronic devices.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
<First embodiment>
FIG. 1 is a diagram illustrating the configuration of the optical module according to the first embodiment. The optical module 1 of this embodiment shown in FIG. 1 includes a transparent substrate 10, a common wiring layer 12, a dielectric layer 14, a signal line layer 16, a protective layer 18, a VCSEL (surface emitting laser) 20, a circuit chip 22, and a lens 24. , And a filler 26. A microstrip line is formed by multilayer wiring including the common wiring layer 12, the dielectric layer 14, and the signal line layer 16, and the microstrip line is used to connect between the VCSEL 20 and the circuit chip 22 or other circuit elements (not shown). The transmission and reception of electric signals are performed between each other. Hereinafter, each component will be described in detail.
[0019]
The transparent substrate 10 has transparency to the wavelength of the light emitted from the VCSEL 20 and supports each element constituting the optical module 1. For example, when the wavelength of light emitted from the VCSEL 20 is visible light or a value close to it (for example, 850 nm), the transparent substrate 10 may be made of a material such as glass or plastic. When the wavelength of the emitted light is relatively long (for example, 1300 nm to 1500 nm), the transparent substrate 10 can be made of a material such as silicon or germanium.
[0020]
The common wiring layer 12 is connected to the ground potential, and is formed on one surface (upper surface) of the transparent substrate 10 using a conductor film made of, for example, copper or the like. This common wiring layer 12 is preferably formed over substantially the entirety of one surface of the transparent substrate 10 in order to minimize the reactance.
[0021]
The dielectric layer 14 is for forming a microstrip structure by separating the common wiring layer 12 and the signal line layer 16 from each other, and is formed on the upper surface of the common wiring layer 12. The dielectric layer 14 is preferably formed to a thickness of about several tens of μm using a dielectric (insulator) such as polyimide.
[0022]
The signal line layer 16 is formed on the upper surface of the dielectric layer 14 using a conductor film made of copper or the like, and is patterned into a predetermined shape. As described above, the microstrip line includes the signal line layer 16, the common wiring layer 12, and the dielectric layer 14. The characteristic impedance of the microstrip line depends on the shapes (line width, line thickness, etc.) and materials of the common wiring layer 12 and the signal line layer 16, the dielectric constant of the dielectric layer 14, the common wiring layer 12 and the signal line layer 16. It can be adjusted to a desired value by appropriately setting each parameter such as the interval.
[0023]
Here, a method of forming a multilayer wiring (microstrip line) including the common wiring layer 12, the dielectric layer 14, and the signal line layer 16 will be schematically described. First, the common wiring layer 12 is formed on the transparent substrate 10 by a method such as electroforming, lift-off, or photolithography. Next, a photosensitive polyimide layer is formed on the common wiring layer 12 by a method such as spin coating or sheet bonding, and is further patterned to expose electrodes and the like. Thus, a dielectric layer 14 is formed. After that, the signal line layer 16 is formed in the same manner as the method of forming the common wiring layer 12 described above. Note that, if necessary, the above steps can be further repeated a plurality of times to form a multilayer wiring including more wiring layers.
[0024]
The protection layer 18 is for protecting the signal line layer 16 from corrosion, breakage, and the like, and is formed so as to cover substantially the entire upper surface of the signal line layer 16. The protective layer 18 is preferably formed by, for example, applying a soldering resist or the like.
[0025]
The VCSEL 20 is a surface-emitting type light-emitting element that emits signal light in accordance with a drive signal given from the circuit chip 22, and has a light-emitting surface at a predetermined position on one surface of the transparent substrate 10 with the light-emitting surface facing the transparent substrate 10. Are located. The light emitting surface of the VCSEL 20 is disposed in an opening 21 provided in a microstrip line including the common wiring layer 12, the dielectric layer 14, and the signal line layer 16 described above. An optical signal is emitted through 10. In this embodiment, a VCSEL which is a surface-emitting type light-emitting element is used, but another light-emitting element (for example, an edge-emitting type light-emitting element or the like) may be used.
[0026]
The circuit chip 22 includes a driver for driving the VCSEL 20 and the like, and is arranged at a predetermined position on the transparent substrate 10. The circuit chip 22 is connected to the VCSEL 20 via a microstrip line formed on the transparent substrate 10, and further connected to other circuit elements (not shown), circuit chips, external devices, and the like as necessary. .
[0027]
The lens 24 is disposed on the other surface side of the transparent substrate 10 at a position facing the light emitting surface of the VCSEL 20. As described above, since the VCSEL 20 and the lens 24 are arranged to face each other with the transparent substrate 10 interposed therebetween, it is possible to secure a necessary optical distance between the VCSEL 20 and the lens 24 according to the thickness of the transparent substrate 10. It is easier to ensure positional accuracy as compared with the case where they are independently arranged inside. If necessary, another optical element (for example, a diffraction grating or the like) may be provided instead of the lens 24.
[0028]
The filler 26 is filled in the vicinity of the VCSEL 20 in order to improve the airtightness and adhesiveness in the vicinity of the VCSEL 20, and is sometimes called an underfill agent. As the filler 26, a filler having a refractive index equivalent to that of the transparent substrate 10 is used. Thereby, return light due to reflection on the surface of the transparent substrate 10 can be suppressed.
[0029]
As described above, the optical module 1 of the first embodiment has a structure in which the light emitting surface of the VCSEL 20 and one surface of the transparent substrate 10 face each other, so that the light emitting surface of the VCSEL 20 can be protected with a simple structure. . Further, since a microstrip line is used, it is possible to cope with a high frequency signal. Therefore, it is possible to realize an optical module suitable for use in optical communication. In the present embodiment, the common wiring layer 12, the dielectric layer 14, and the signal line layer 16 are stacked on one surface of the transparent substrate 10 to form a microstrip line, and the VCSEL 20 is disposed above the signal line layer 16. Therefore, the common wiring layer 12 connected to the ground potential is interposed between the other surface side of the transparent substrate 10 and the VCSEL 20, and the VCSEL 20 and the circuit chip 22 are connected from the other surface side of the transparent substrate 10. There is also an operational effect that it is easy to suppress the entry of noise.
[0030]
In the above-described embodiment and each of the embodiments described below, a light receiving element (photodetector) that generates an electric signal according to the intensity of the received light may be mounted instead of the VCSEL 20. In this case, the above-described circuit chip 22 includes a current / voltage conversion amplifier (or transimpedance amplifier) for converting a current signal output from the light receiving element into a voltage signal, and the like. By transmitting and receiving electric signals between the elements by the microstrip line, it becomes possible to configure an optical module suitable for increasing the operation speed. Further, the optical module may be configured to include both the light emitting element and the light receiving element.
[0031]
<Second embodiment>
FIG. 2 is a diagram illustrating the configuration of the optical module according to the second embodiment. The optical module 1a shown in the figure has basically the same configuration as the optical module 1 of the first embodiment described above, and the lamination state of each wiring layer and dielectric layer constituting the microstrip line is different. Is different. Hereinafter, the configuration of the optical module 1a according to the second embodiment will be described, mainly focusing on the differences from the first embodiment.
[0032]
As shown in FIG. 2, in the optical module 1a, a signal line layer 16a is formed on the upper surface of the transparent substrate 10, and a dielectric layer 14a and a common wiring layer 12a are formed on the signal line layer 16a. A microstrip line includes these common wiring layer 12a, dielectric layer 14a and signal line layer 16a. Note that materials and shapes suitable for each of the common wiring layer 12a, the dielectric layer 14a, and the signal line layer 16a are described in each of the common wiring layer 12, the dielectric layer 14, and the signal line layer 16 in the first embodiment. Is the same as
[0033]
As described above, also with the optical module 1a of the second embodiment, the light emitting surface of the VCSEL 20 can be protected with a simple structure, is excellent in handling high-frequency signals, and is suitable for use in optical communication. Modules can be realized. In this embodiment, the signal line layer 16a, the dielectric layer 14a, and the common wiring layer 12a are stacked on one surface of the transparent substrate 10 to form a microstrip transmission line. Since the VCSEL 20 is disposed, the number of layers stacked in the region below the VCSEL 20 is reduced, so that the height (thickness) of the region can be easily controlled, and the positional accuracy of the light emitting surface of the VCSEL 20 (particularly, the horizontal position) This also has the effect of making it easier to ensure the accuracy).
[0034]
<Third embodiment>
Next, an optical transceiver (optical communication device) configured using the optical module described in the above embodiment will be described. The optical module according to the present invention can be used as a front-end unit that interfaces with an external device in an optical transceiver.
[0035]
FIG. 3 is a diagram illustrating a configuration example of the optical transceiver according to the third embodiment. An optical transceiver 100 shown in the figure performs information communication via an optical fiber, and includes an optical module 1 (or an optical module 1a) according to the above-described embodiment, a sleeve 102, a circuit board 104, and each component. It is configured to include a supporting casing 106.
[0036]
The sleeve 102 is connected to one end of the optical fiber, and serves for optical coupling between the optical fiber and the optical transceiver 100 of the present embodiment. The sleeve 102 is disposed on the other surface (back surface) of the optical module 1. . The sleeve 102 has a built-in lens 108 for collecting signal light emitted from the VCSEL 20 mounted on one surface of the optical module 1 and guiding the signal light to an optical fiber (not shown). The circuit board 104 includes an electric circuit for performing signal processing related to information communication, and is electrically connected to the optical module 1 via the flexible wiring board 110.
[0037]
As described above, by using the optical module according to the present invention, it is possible to obtain an optical transceiver suitable for increasing the operation speed. Such an optical transceiver according to the present invention is used for various electronic devices such as a personal computer and a so-called PDA (portable information terminal device) that perform information communication with an external device using light as a transmission medium. Is possible.
[0038]
<Fourth embodiment>
Next, an opto-electric hybrid integrated circuit configured using the optical module described in the above-described embodiment and a circuit board configured using the opto-electric hybrid integrated circuit will be described.
[0039]
FIG. 4 is a diagram illustrating a configuration example of an opto-electric hybrid integrated circuit and a circuit board including the opto-electric hybrid integrated circuit. The circuit board 200 shown in the figure includes an opto-electric hybrid integrated circuit 202 including the optical module 1 (or the optical module 1a) according to the above-described embodiment, and an opto-electric hybrid board 204.
[0040]
The opto-electric hybrid integrated circuit 202 includes the optical module 1 and the signal processing chip 206, and has a structure in which both are integrally molded with plastic or the like. The optical module 1 and the signal processing chip 206 are electrically connected by wire bonding. The optical module 1 is arranged such that the emission direction of the emitted light from the light emitting element is directed to the opto-electric hybrid board 204.
[0041]
A wiring film 208 is provided on the upper part of the opto-electric hybrid board 204, and an optical waveguide 210 is provided inside (an intermediate layer). The wiring film 208 is electrically connected to the opto-electric hybrid integrated circuit 202, and exchanges an electric signal between the opto-electric hybrid integrated circuit 202 and another circuit chip (not shown) via the wiring film 208. Is made.
[0042]
The optical waveguide 210 has a function of propagating an optical signal emitted from a light emitting element included in the opto-electric hybrid integrated circuit 202 and sending the signal to another device or module (not shown). The optical waveguide 210 has a reflection mirror 212 formed at an end thereof, and the optical signal from the light emitting element is changed in direction by approximately 90 degrees by the reflection mirror 212, enters the optical waveguide 208, and travels.
[0043]
The opto-electric hybrid integrated circuit 202 and the circuit board 200 according to this embodiment are applied to various electronic devices such as a personal computer, and are used for information communication within the device and information communication with an external device. It is possible.
[0044]
Note that the present invention is not limited to the contents of the above-described embodiments, and various modifications can be made within the scope of the present invention. For example, in the optical module shown in FIG. 1 or FIG. 2 described above, the optical element and the microstrip transmission line are both arranged on one surface of the transparent substrate. May be arranged on the other surface. In this case, the opening provided in the microstrip transmission line and the light emitting surface or the light receiving surface of the optical element are aligned and arranged so as to face each other, for example, a through hole is formed in a transparent substrate, and the through hole is formed. The connection between the optical element and the microstrip transmission line may be achieved through the filled conductor (plug).
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of an optical module according to a first embodiment.
FIG. 2 is a diagram illustrating a configuration of an optical module according to a second embodiment.
FIG. 3 is a diagram illustrating a configuration example of an optical transceiver.
FIG. 4 is a diagram illustrating a configuration example of an opto-electric hybrid integrated circuit and a circuit board including the opto-electric hybrid integrated circuit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical module, 10 ... Transparent substrate, 12 ... Common wiring layer, 14 ... Dielectric layer, 16 ... Signal line layer, 18 ... Protective layer, 20 ... VCSEL (surface emitting laser), 22 ... Circuit chip, 100 ... Light Communication device (optical transceiver), 200: circuit board, 202: opto-electric hybrid integrated circuit

Claims (11)

An optical element that emits a signal light according to the supplied electric signal or generates an electric signal according to the intensity of the supplied signal light,
Multilayer wiring responsible for transmission of electrical signals to the optical element,
The optical element has a light-transmitting property to the wavelength of light emitted or received, and a transparent substrate that supports the optical element and the multilayer wiring,
An optical module, wherein the optical element has a light emitting surface or a light receiving surface disposed in an opening provided in the multilayer wiring, and an optical signal is incident or emitted through the opening and the transparent substrate. The optical module according to claim 1, wherein the multilayer wiring is a microstrip transmission line. The optical module according to claim 1, wherein the optical element and the multilayer wiring are both disposed on one side of the transparent substrate. The multilayer wiring is configured by stacking a common wiring layer, a dielectric layer and a signal line layer on one surface of the transparent substrate,
The optical module according to claim 3, wherein the optical element is arranged above the signal line layer. The multilayer wiring is configured by laminating a signal line layer, a dielectric layer and a common wiring layer on one surface of the transparent substrate,
The optical module according to claim 3, wherein the optical element is arranged above the signal line layer. The optical module according to any one of claims 2 to 5, further comprising an optical element disposed on the other surface side of the transparent substrate and facing a light emitting surface or a light receiving surface of the optical element. The optical module according to claim 6, wherein the optical element includes at least one of a lens and a diffraction grating. An optical communication device comprising the optical module according to claim 1. An opto-electric hybrid integrated circuit comprising the optical module according to claim 1. An optical module according to any one of claims 1 to 7,
An optical waveguide for transmitting signal light;
A circuit board comprising: An electronic device comprising the optical module according to claim 1.

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