JP6122380B2 - Optical module - Google Patents

Description

  The present invention relates to an optical module, and more particularly, is mainly applied to optical fiber communication, for optical elements such as light emitting elements such as laser diodes and light receiving elements such as photodiodes, and optical input / output such as optical fibers. The present invention relates to an optical module for optical and electrical connection with members.

  In recent years, with the remarkable development of optical fiber communication technology, a small-sized optical module in which a plurality of functions are integrated is required. For example, the optical module includes a light emitting element such as a laser diode (LD), a light receiving element such as a photodiode (PD), an optical component, an optical functional circuit, a photoelectric conversion circuit, and the like, and an optical fiber for optical input / output, It is configured to allow connection by electrical wiring. Of these, the long-term reliability of the optical element deteriorates due to moisture or oxygen. In order to prevent this, the optical module hermetically seals components such as optical elements using a highly airtight casing.

  FIG. 1 is a diagram illustrating an example of a conventional optical module. This is an optical module described in Patent Document 1, and is composed of two types of packages. In the first package, a mounting substrate 12 is fixed to a bottom surface C inside a metal-worked housing 11, and a quartz-based planar lightwave circuit (PLC) 13 is fixed on the mounting substrate 12. The opening of the housing 11 is closed with a lid 14 and sealed. A part of the bottom surface outside the housing 11 of the first package is provided with a notch having surfaces A and B so that the second package can be attached. Of the notches, a part of the surface A is attached with a lid 22 that transmits the light of the second package so that light can be output to the light receiving surface 24 of the PD array 23. In addition, an opening is provided through the housing 11.

  In the second package, a bare chip PD array 23 is fixed to the bottom surface inside the ceramic casing 21 with AuSn solder. The casing 11 and the lid 22 are joined by AuSn solder, and the PD array 23 and the transimpedance amplifier (TIA) 24 are hermetically sealed. The output of the TIA 24 is output from the lead pin 26 drawn to the outside of the housing 21 through the electrical wiring 25 and the through hole of the housing 21. In particular, an optical element that is required to be airtight is made a housing separate from the optical component and the optical functional circuit in order to improve reliability.

  The signal light input from the optical fiber 15 is input to the optical waveguide of the PLC 13. The light propagating through the optical waveguide is coupled from the end face of the PLC 13 to the light receiving surface 24 of the PD array 23 via the first lens 16, the prism mirror 17, the second lens 18, and the lid 22. The electrical signal photoelectrically converted in the PD array 23 is amplified by the TIA 24 and output to the outside of the optical module.

  Patent Document 2 discloses an optical device in which an optical element and an optical waveguide substrate are mounted on an electric wiring substrate having a multilayer structure and hermetically sealed by a thin film lid substrate. The LD is driven by an electric signal input from the electric wiring board through the electronic component and the driver IC. The signal light from the LD is input to the optical waveguide of the optical waveguide substrate via the optical path conversion unit, and is output to the outside of the optical module via the optical fiber.

JP 2011-164143 A JP 2010-28006 A

  In the optical module shown in FIG. 1, the light receiving element is hermetically sealed by a second package which is a housing separate from the optical component and the optical waveguide substrate. However, since the optical element is stored using a separate casing, the optical waveguide on the optical waveguide substrate and the optical element cannot be disposed close to each other, so that the distance between the optical waveguide and the optical element is large. Therefore, optical loss increases. In addition, when using an optical element with a small light receiving surface for high-speed operation, a lot of optical components such as lenses are used to sufficiently collect the signal light output from the optical waveguide and couple it to the light receiving surface. There is a need to. For this reason, the number of members has increased, and there has been a problem of an increase in the size of the optical module, and an increase in member costs and assembly costs.

  On the other hand, in the optical device described in Patent Document 2, since the optical waveguide substrate and the optical element are hermetically sealed by a pair of a housing and a lid substrate, the distance between them is arranged close to each other. Can do. Therefore, the number of optical components can be reduced. However, since this optical device accommodates not only the optical waveguide substrate and the optical element but also components such as electronic components in the same casing, the area and volume for hermetic sealing are inevitably increased. If the area of the hermetic seal is increased, the leak path is also increased, thereby increasing the possibility of hermetic leakage. In addition, the possibility of airtight leakage increases due to deterioration of rigidity due to an increase in housing size and deformation due to thermal stress or the like. Therefore, there has been a problem that the reliability of the optical device is deteriorated or the manufacturing yield is deteriorated, and the manufacturing cost is thereby increased.

  Further, regarding the arrangement of the components in the optical module, the optical waveguide substrate, the optical element, the electric element, and the electric wiring are arranged in a straight line with respect to the light output direction (optical axis) to the optical fiber. For this reason, there was a problem that the dimension of the optical device in the optical axis direction (longitudinal direction) was large.

  An object of the present invention is to provide an optical module that is small, highly functional, and economical, which ensures high reliability by hermetically sealing an optical element.

In order to achieve the above object, according to one embodiment of the present invention, an optical waveguide substrate having an optical waveguide formed and having an opening opened in only one direction, and a lid substrate bonded to the optical waveguide substrate are provided. An optical element is mounted in an internal space formed by the opening and the lid substrate, and the optical waveguide substrate has an optical path conversion unit that optically couples the optical waveguide and the optical element. The optical path changing portion is an inclined surface of about 45 degrees formed so as to cross the optical waveguide perpendicular to the optical axis at a position to be the exit end of the optical waveguide, It said slope parts, the light input and output members for bonding the optical waveguide optically coupled to the optical fiber is characterized that it is connected.

  As described above, according to the present invention, since the optical path conversion unit is provided, the optical waveguide substrate and the lid substrate are stacked in the direction perpendicular to the optical axis with respect to the optical axis direction of the optical waveguide. The size of the module in the optical axis direction (longitudinal direction) can be reduced. As a result, the area of hermetic sealing is reduced and high hermeticity can be ensured.

It is a figure which shows an example of the conventional optical module. It is a figure which shows the optical module concerning the 1st Embodiment of this invention. It is a figure which shows the calculation result of the optical coupling allowable value in the optical module of 1st Embodiment. It is a figure which shows the optical module concerning the 2nd Embodiment of this invention. It is a figure which shows the optical module concerning the 3rd Embodiment of this invention. It is a figure which shows the optical module concerning the 4th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 2 shows an optical module according to the first embodiment of the present invention. A multi-wavelength light receiver that demultiplexes and receives four-channel wavelength multiplexed light will be described as an example of an optical module. 2A is a cross-sectional view seen from the side, and FIG. 2B is a perspective view seen from the top. In the optical module, a bare chip PD array 111 and an electrical element TIA 112 are mounted on the surface of a lid substrate 101 which is an electrical wiring substrate. An optical element, an electric element, and the like are hermetically sealed by bonding the optical waveguide substrate 102 on which the optical waveguide is formed and the lid substrate 101.

  The optical waveguide substrate 102 is made of a quartz glass material, and is formed with an optical waveguide 121 and a wavelength demultiplexing circuit 122 (for example, an arrayed waveguide diffraction grating (AWG)) that demultiplexes 4-channel wavelength multiplexed light. . These optical functional circuits are formed by thermally oxidizing the surface of an optical waveguide substrate made of silicon. The optical waveguide 121 and the optical fiber 103 are connected via an optical input / output member (fiber bead or the like) 131.

  In addition, the optical waveguide substrate 102 includes an optical path conversion unit 123 for optically coupling the optical waveguide 121 and the PD array 111. The optical path changing unit 123 is formed using a dicing apparatus having a cutting angle of about 45 degrees. Dicing is performed so as to cross the optical waveguide on the optical waveguide substrate perpendicularly to the optical axis at a position to be the output end of the optical waveguide so that the output end of the optical waveguide is positioned on the slope of the V-groove. To cut. In order to improve the reflection characteristic in the optical path conversion unit 123, that is, the optical path conversion performance, the surface of the optical path conversion unit 123 is coated with a metal (not shown).

  The optical waveguide substrate 102 has a bathtub-shaped structure opened in only one direction, and a PD array 111, a TIA 112, and an electronic component 116 are formed in an internal space formed by the opening and a lid substrate (electric wiring substrate) 101. Etc. are hermetically sealed. The joint between the lid substrate (electrical wiring substrate) 101 and the optical waveguide substrate 102 is not shown, but is coated with a metal coating, and the two are joined via solder (AuSn).

  The PD array 111 is a four-channel photodiode integrated chip, and an indium phosphide-based material having high light receiving sensitivity and response speed is used in a communication wavelength band (wavelength 1.5 μm band or 1.3 μm band). The TIA 112 integrates a four-channel amplifier and uses a silicon-germanium-based material.

  Next, the operation of the optical module will be described. The signal light to be received is input from the optical fiber 103 to the optical waveguide 121 on the end face of the optical waveguide substrate 102 via the optical input / output member 131. The four-channel light propagating through the optical waveguide 121 and wavelength-demultiplexed by the wavelength demultiplexing circuit 122 is reflected by the optical path conversion unit 123, converts the optical path at a right angle, and travels toward the opening of the optical waveguide substrate 102. The wavelength-demultiplexed light is subjected to a condensing effect by the lens 132 provided on the optical path between the optical path conversion unit 123 and the PD array 111, and then is received on the light receiving surface corresponding to each channel of the PD array 111. Combined.

  The four-channel electrical signals photoelectrically converted in the PD array 111 are each amplified in the TIA 112 and output from the lead pin 114 to the outside of the optical module via the metal wire 115b and the metal wiring 113.

  FIG. 3 shows the calculation result of the allowable optical coupling value in the optical module of the first embodiment. The optical coupling tolerance (tolerance) caused by the dimensional error of the constituent members was calculated. 3A shows a calculation result of the tolerance of the thickness of the optical waveguide substrate 102 (the thickness of the portion where the opening is formed), and FIG. 3B shows the thickness of the optical element (PD 111). It is the calculation result of tolerance.

The optical wavelength of the optical signal is 1.3 μm, and the mode field diameter of the optical waveguide is 5 μm. The thickness of the optical waveguide (quartz glass) was 50 μm, and the optical waveguide substrate and the lens were both made of silicon. The lens was a one-side spherical lens, and the optical element was a back-illuminated type. Under these conditions, the member tolerance and mounting tolerance that satisfy the optical coupling tolerance of 0.1 dB or less were estimated as follows.
・ Thickness of substrate: 750 μm ± 65 μm (see FIG. 3A)
-Optical element thickness: 150 μm ± 65 μm (see FIG. 3B)
-Spatial distance between lens and optical element: 150μm ± 20μm
・ Lens curvature radius: 260μm ± 12μm

  With the above configuration, in the first embodiment, the optical waveguide substrate 102 and the lid substrate are arranged with respect to the light input direction from the optical fiber 103 (the optical axis direction of the optical waveguide) in the component arrangement in the optical module. 101 are stacked in the direction perpendicular to the optical axis. Therefore, the dimension of the optical module in the optical axis direction (longitudinal direction) can be reduced with respect to a configuration in which components are arranged in a straight line as in the conventional example. As a result, since the area of hermetic sealing is reduced and the leak path is also reduced, it is possible to improve hermeticity, improve rigidity by reducing the housing size, and reduce deformation due to thermal stress. As a result, the reliability of the optical module is improved and the manufacturing yield is also improved, so that a great effect of reducing the manufacturing cost of the optical module can be obtained. In addition, since the optical waveguide substrate also serves as the casing and the lid substrate also serves as the electrical wiring substrate, the number of parts of the optical module can be reduced as compared with the conventional example.

  In the first embodiment, since the optical element is hermetically sealed using the optical waveguide substrate, the distance between the optical element and the optical waveguide can be close. Therefore, not only the optical loss from the optical waveguide to the optical element is improved, but also when using an optical element having a small light receiving surface for the purpose of high-speed operation, the signal light can be transmitted without using many optical components such as lenses. It can be condensed on the optical element.

  Furthermore, it is not necessary to hermetically seal the connection portion between the optical fiber and the optical waveguide. In addition, since the connection between the optical input / output member and the optical waveguide substrate can be made after the optical module is hermetically sealed, the adhesive used for this connection need not have high temperature resistance. That is, there is no restriction on the adhesive material used for connection between the optical input / output member and the optical waveguide substrate, and optimal optical connection can be performed.

(Optical module manufacturing method)
(1) A method for manufacturing an optical waveguide substrate when a silicon substrate is used as the optical waveguide substrate will be described. First, a quartz glass layer is formed by thermal oxidation on one surface of a silicon substrate. The core of the optical waveguide is formed by patterning the quartz glass layer into a desired shape. Further, silicon is deposited to form an upper clad, and an optical waveguide is formed together with a silicon substrate to be a lower clad.

  Next, a resist is applied by spin coating to the surface of the silicon substrate where the optical waveguide is not formed. By photolithography exposure and development, the resist is patterned to have the shape of the outer periphery of the opening, and the silicon substrate is excavated by etching to form the opening. Finally, the resist is removed to complete the opening. As an etching technique, ion milling in which a silicon substrate is physically excavated by accelerated Ar ions may be used. Alternatively, plasma etching in which a silicon substrate is chemically excavated with a reactive gas such as CF 4 may be used.

  A lens is bonded to the inner surface of the formed opening at a position where the light whose path has been changed by the optical path changing section is led to the opening. As described in the third and fourth embodiments described later, when it is not necessary to provide a lens in the opening, the lens bonding operation is not necessary. In addition, as described in the second embodiment to be described later, when a lens is integrally formed in the opening, instead of adhering the lens to the opening, a spherically processed resist is formed when the opening is etched. What is necessary is just to etch.

  Finally, dicing is performed so as to cross the optical waveguide perpendicular to the optical axis at a position to be the output end of the optical waveguide in the surface of the silicon substrate on which the optical waveguide is formed. Of the surfaces formed by dicing, a metal thin film is vapor-deposited on at least the surface serving as the emission end of the optical waveguide to form an optical path changing portion.

  (2) A method for manufacturing the lid substrate (electrical wiring substrate) will be described. A through hole is provided in the insulator substrate, and desired metal wiring is formed on the front surface, the back surface, and the inner surface of the through hole of the insulator substrate. Desired electrical elements, optical elements, and the like are mounted on the surface of the insulating substrate and the surface facing the opening of the optical waveguide substrate. The electrical element, the optical element, and the metal wiring are connected by wire bonding using a metal wire such as gold (Au).

  (3) Bonding the optical waveguide substrate and the lid substrate. Metal thin films are vapor-deposited (metal coating) on the surfaces to which both the optical waveguide substrate and the lid substrate are bonded. The metal-coated positions of the optical waveguide substrate and the lid substrate are brought into contact with each other and bonded by solder (AuSn). The optical module is completed by bonding the optical input / output member to the incident end face of the optical waveguide of the optical waveguide substrate with an adhesive and connecting the optical fiber.

(Other application examples)
In the first embodiment, a four-channel integrated optical module is illustrated, but the number of channels may be increased or decreased depending on the application. The optical module of the first embodiment is an example of a light receiver, but can also be applied as a light emitter by changing the optical element to a laser, LED, and the electric element to a driver IC.

  In the first embodiment, the materials of the optical waveguide and the optical waveguide substrate are quartz glass and silicon, respectively. For example, both can be silicon, or both can be quartz glass, and an organic polymer (polymer) can be applied. In addition, although an optical demultiplexing circuit based on AWG is shown as an optical functional circuit, it is changed to a circuit having other functions, for example, an intensity branching circuit (coupler or splitter), an optical interference circuit (Mach-Zehnder interferometer, etc.) You can also

  In the first embodiment, the optical path conversion unit is formed by dicing. For example, the formation by etching and the nanoimprint method by transferring the mold shape can be applied. Here, the angle of the optical path conversion unit is 45 degrees with respect to the optical waveguide. For example, an angle such as 44 degrees or 46 degrees can be applied in order to reduce characteristic deterioration due to reflected return light generated at the interface of each component. A metal coating is applied to the optical path conversion unit, but a total reflection coating using a dielectric multilayer film can also be applied.

  In the first embodiment, the one-side spherical lens made of silicon is used as the lens, but other materials and configurations may be applied. For example, quartz glass or resin can be used as the material, and a gradient index lens (GRIN), a Fresnel lens, or an aspherical lens can be used as the lens configuration.

  In the first embodiment, bonding with AuSn solder is used for hermetic sealing. For example, tin silver copper (SnAgCu) solder and low melting point glass are also applicable. Although the airtightness is inferior, resins such as epoxy and acrylic can also be used.

(Second Embodiment)
FIG. 4 shows an optical module according to the second embodiment of the present invention. This module is a multi-wavelength light emitter that multiplexes and outputs 4-channel wavelength multiplexed light. 4A is a cross-sectional view seen from the side, and FIG. 4B is a perspective view seen from the top. In the optical module, a bare chip LD array 211 and a driver IC 212 which is an electric element are mounted on the surface of a lid substrate 201 which is an electric wiring substrate, and hermetically sealed by an optical waveguide substrate 202.

  The optical waveguide substrate 202 is made of a quartz glass material, and is formed with a wavelength multiplexing circuit 222 (for example, an arrayed waveguide diffraction grating (AWG)) that demultiplexes the optical waveguide 221, 4-channel wavelength multiplexed light. . These optical functional circuits are formed by thermally oxidizing the surface of an optical waveguide substrate made of silicon. The optical waveguide 221 and the optical fiber 203 are connected via an optical input / output member (lens or the like) 233.

  The optical waveguide substrate 202 includes an optical path conversion unit 223 for optically coupling the optical waveguide 221 and the LD array 211. The optical path conversion unit 223 is formed using a polishing apparatus having a polishing angle of about 45 degrees. Polishing so as to cross the optical waveguide on the optical waveguide substrate perpendicular to the optical axis at a position to be the output end of the optical waveguide so that the output end of the optical waveguide is located on a slope of about 45 degrees. To polish. In order to improve the reflection characteristics in the optical path conversion section 223, that is, the optical path conversion performance, the surface of the optical path conversion section 223 is coated with metal (not shown).

  The optical waveguide substrate 202 has a bathtub-shaped structure opened in only one direction, and an LD array 211, a driver IC 212, and an electronic component are formed in an internal space formed by the opening and a lid substrate (electric wiring substrate) 201. 216 and the like are hermetically sealed. The joint between the lid substrate (electrical wiring substrate) 201 and the optical waveguide substrate 202 is not shown in the figure, but is provided with a metal coating, and both are joined via solder (AuSn).

  The LD array 211 is a four-channel laser diode integrated chip, and indium phosphide-based materials having different emission wavelengths and high response speeds are used in the communication wavelength band (wavelength 1.5 μm band or 1.3 μm band). Yes. The driver IC 212 has a 4-channel current drive circuit integrated therein, and a silicon-germanium-based material is used.

  Next, the operation of the optical module will be described. A four-channel electrical signal is input to the driver IC 212 via a BGA (Ball Grid Array) 217, a metal wiring 213, and a metal wire 215b. The driver IC 212 drives the LD array 211 to output signal light to be emitted.

  The signal light receives a light condensing effect by the lens 224 provided on the optical path between the LD array 211 and the optical path conversion unit 223 and is then input to the optical waveguide on the end surface of the optical waveguide substrate 202. The light propagating through the optical waveguide is wavelength-multiplexed by the wavelength multiplexing circuit 222 and then output to the optical fiber 203 via the light input / output member (lens) 233.

  With the configuration as described above, the second embodiment has the same effect as the optical module shown in the first embodiment. That is, the size of the optical module in the optical axis direction (longitudinal direction) can be reduced, the area of hermetic sealing is reduced, and the leak path is also reduced. Improvement and reduction of deformation due to thermal stress can be achieved. As a result, the reliability of the optical module is improved and the manufacturing yield is also improved, so that a great effect of reducing the manufacturing cost of the optical module can be obtained. In addition, since the optical waveguide substrate also serves as the casing and the lid substrate also serves as the electrical wiring substrate, the number of parts of the optical module can be reduced as compared with the conventional example.

  In addition, since the optical element is hermetically sealed using the optical waveguide substrate as in the first embodiment, the distance between the optical element and the optical waveguide can be made close. Therefore, not only the optical loss from the optical waveguide to the optical element is improved, but there is no need to use many optical components such as lenses. Further, since the connection between the optical input / output member and the optical waveguide substrate can be made after the optical module is hermetically sealed, the adhesive used for this connection does not need to have high temperature resistance.

  Furthermore, in the second embodiment, a lens is integrally formed on the inner surface of the opening of the optical waveguide substrate. Therefore, the number of members and the number of work steps can be reduced as compared with the configuration of the first embodiment. As for the lens manufacturing method, when the opening is formed in the optical waveguide substrate by etching, the resist shape is spherically processed in advance to form a lens structure reflecting the shape. It is also possible to apply etching by sandblasting or laser beam instead of etching.

(Third embodiment)
FIG. 5 shows an optical module according to the third embodiment of the present invention. A multi-wavelength light receiver that demultiplexes and receives four-channel wavelength multiplexed light will be described as an example of an optical module. FIG. 5A is a cross-sectional view seen from the side, and FIG. 5B is a perspective view seen from the top. In the optical module, a bare chip PD array 311 and an electrical element TIA 312 are mounted on the surface of a lid substrate 301 that is an electrical wiring substrate, and hermetically sealed by an optical waveguide substrate 302.

  The optical waveguide substrate 302 is made of a quartz glass material, and an optical waveguide 321 and a wavelength demultiplexing circuit 322 (for example, an arrayed waveguide diffraction grating (AWG)) that demultiplexes four-channel wavelength multiplexed light are formed. . These optical functional circuits are formed by thermally oxidizing the surface of an optical waveguide substrate made of silicon.

  In addition, the optical waveguide substrate 302 has an optical path conversion unit 323 for optically coupling the optical waveguide 321 and the PD array 311. The optical path conversion unit 323 is formed using a polishing apparatus having a polishing angle of about 45 degrees. Polishing so as to cross the optical waveguide on the optical waveguide substrate perpendicular to the optical axis at a position to be the output end of the optical waveguide so that the output end of the optical waveguide is located on a slope of about 45 degrees. To polish. In order to improve the reflection characteristics in the optical path conversion section 323, that is, the optical path conversion performance, the surface of the optical path conversion section 323 is provided with a metal coating (not shown).

  The optical waveguide 321 and the optical fiber 303 are connected via an optical input / output member (fiber bead or the like) 331. Unlike the first embodiment, the light input / output member 331 is connected to the end face of the optical waveguide 321 disposed on the inclined surface (polishing surface) of about 45 degrees serving as the optical path conversion unit 323.

  The optical waveguide substrate 302 has a bathtub-shaped structure opened in only one direction, and a PD array 311, a TIA 312, and an electronic component 316 are formed in an internal space formed by the opening and the lid substrate (electric wiring substrate) 301. Etc. are hermetically sealed. Although not shown in the drawings, the joint between the lid substrate (electric wiring substrate) 301 and the optical waveguide substrate 302 is provided with a metal coating, and the two are joined via solder (AuSn).

  The PD array 311 is a four-channel photodiode integrated chip, and an indium phosphide-based material having high light receiving sensitivity and response speed is used in a communication wavelength band (wavelength 1.5 μm band or 1.3 μm band). The TIA 312 integrates a four-channel amplifier and uses a silicon-germanium-based material.

  Next, the operation of the optical module will be described. The signal light to be received is input from the optical fiber 303 to the optical waveguide 321 on the end face of the optical waveguide substrate 302 via the optical input / output member 331. The four-channel light propagating through the optical waveguide 321 and wavelength-demultiplexed by the wavelength demultiplexing circuit 322 is reflected by the optical path conversion unit 323, converts the optical path at right angles, and travels toward the opening of the optical waveguide substrate 302. The wavelength-demultiplexed light is combined with the light receiving surface corresponding to each channel of the PD array 311 after receiving the light condensing effect by the lens 311 a formed on the light receiving surface of the PD array 311.

  The four-channel electrical signals photoelectrically converted in the PD array 311 are each amplified in the TIA 312 and output from the flexible printed circuit board (FPC) 318 to the outside of the optical module via the metal wires 315b and the metal wires 313.

  With the configuration as described above, the third embodiment has the same effect as the optical modules shown in the first and second embodiments. That is, the size of the optical module in the optical axis direction (longitudinal direction) can be reduced, the area of hermetic sealing is reduced, and the leak path is also reduced. Improvement and reduction of deformation due to thermal stress can be achieved. As a result, the reliability of the optical module is improved and the manufacturing yield is also improved, so that a great effect of reducing the manufacturing cost of the optical module can be obtained. In addition, since the optical waveguide substrate also serves as the casing and the lid substrate also serves as the electrical wiring substrate, the number of parts of the optical module can be reduced as compared with the conventional example.

  In addition, since the optical element is hermetically sealed using the optical waveguide substrate, as in the first and second embodiments, the distance between the optical element and the optical waveguide can be close. Therefore, not only the optical loss from the optical waveguide to the optical element is improved, but there is no need to use many optical components such as lenses. Further, since the connection between the optical input / output member and the optical waveguide substrate can be made after the optical module is hermetically sealed, the adhesive used for this connection does not need to have high temperature resistance.

  In the third embodiment, a light input / output member is connected to a polishing surface that serves as an optical path conversion unit. Since the light input / output member is disposed in the space removed to form the optical path conversion unit, the longitudinal dimension of the optical module can be further reduced. In the optical waveguide substrate, the surface other than the polished surface of the optical path changing unit is not limited in the flatness of the surface. For example, the surface can be roughened only by cutting by dicing, and the number of work steps can be reduced.

  In the third embodiment, a lens is integrally formed on the light receiving element. Therefore, the number of members and the number of work steps can be reduced as compared with the configurations of the first and second embodiments. As for the lens manufacturing method, when the surface of the optical element is etched, the resist shape is spherically processed in advance to form a lens structure reflecting the shape. It is also possible to apply etching by sandblasting or laser beam instead of etching.

(Fourth embodiment)
FIG. 6 shows an optical module according to the fourth embodiment of the present invention. A multi-wavelength light receiver that demultiplexes and receives four-channel wavelength multiplexed light will be described as an example of an optical module. 6A is a cross-sectional view seen from the side, and FIG. 6B is a perspective view seen from the top. In the optical module, a bare chip PD array 411 and an electrical element TIA 412 are mounted in the opening of the optical waveguide substrate 402 and hermetically sealed by the surface of the lid substrate 401.

  The optical waveguide substrate 402 is made of a quartz glass material, and is formed with an optical waveguide 421 and a wavelength demultiplexing circuit 422 (for example, an arrayed waveguide diffraction grating (AWG)) that demultiplexes 4-channel wavelength multiplexed light. . These optical functional circuits are formed by thermally oxidizing the surface of an optical waveguide substrate made of silicon.

  In addition, the optical waveguide substrate 402 includes an optical path conversion unit 423 for optically coupling the optical waveguide 421 and the PD array 411. The optical path conversion unit 423 is formed using a polishing apparatus having a polishing angle of about 45 degrees. Polishing so as to cross the optical waveguide on the optical waveguide substrate perpendicular to the optical axis at a position to be the output end of the optical waveguide so that the output end of the optical waveguide is located on a slope of about 45 degrees. To polish. In order to improve the reflection characteristics in the optical path conversion section 423, that is, the optical path conversion performance, the surface of the optical path conversion section 423 is provided with a metal coating (not shown).

  The optical waveguide 421 and the optical fiber 403 are connected via an optical input / output member (lens) 433. Similar to the third embodiment, the light input / output member 433 is connected to the end surface of the optical waveguide 421 disposed on the inclined surface (polishing surface) of about 45 degrees serving as the optical path conversion unit 423.

  The optical waveguide substrate 402 has a bathtub-shaped structure opened in only one direction, and the PD array 411, the TIA 412, the electronic component 416, etc. are hermetically sealed in the internal space formed by the opening and the lid substrate 401. Is done. Although not shown in the drawings, the joint between the lid substrate 401 and the optical waveguide substrate 402 is provided with a metal coating, and both are joined via solder (AuSn). Unlike the first to third embodiments, the fourth embodiment is configured such that an optical element or the like is mounted on an optical waveguide substrate and hermetically sealed by a lid substrate.

  The PD array 411 is a 4-channel photodiode integrated chip, and an indium phosphide-based material having high light receiving sensitivity and response speed is used in a communication wavelength band (wavelength 1.5 μm band or 1.3 μm band). The TIA 412 integrates a four-channel amplifier and uses a silicon-germanium-based material.

  Next, the operation of the optical module will be described. The signal light to be received is input from the optical fiber 403 to the optical waveguide 421 on the end face of the optical waveguide substrate 402 via the optical input / output member 433. The four-channel light that propagates through the optical waveguide 421 and is wavelength-demultiplexed by the wavelength demultiplexing circuit 422 is reflected by the optical path conversion unit 423 to convert the optical path at a right angle, and corresponds to each channel of the PD array 411. Coupled to the light receiving surface.

  The four-channel electrical signals photoelectrically converted in the PD array 411 are amplified in the TIA 412 and output from the flexible printed circuit board (FPC) 418 to the outside of the optical module via the metal wires 415b and the metal wires 413.

  With the configuration as described above, the fourth embodiment has the same effects as the optical modules shown in the first to third embodiments. That is, the size of the optical module in the optical axis direction (longitudinal direction) can be reduced, the area of hermetic sealing is reduced, and the leak path is also reduced. Improvement and reduction of deformation due to thermal stress can be achieved. As a result, the reliability of the optical module is improved and the manufacturing yield is also improved, so that a great effect of reducing the manufacturing cost of the optical module can be obtained. In addition, since the optical waveguide substrate also serves as the casing and the lid substrate also serves as the electrical wiring substrate, the number of parts of the optical module can be reduced as compared with the conventional example.

  In addition, since the optical element and the like are mounted on the optical waveguide substrate by being hermetically sealed with the lid substrate, the distance between the optical element and the optical waveguide can be close. Therefore, not only the optical loss from the optical waveguide to the optical element is improved, but there is no need to provide an optical component such as a lens. Further, since the connection between the optical input / output member and the optical waveguide substrate can be made after the optical module is hermetically sealed, the adhesive used for this connection does not need to have high temperature resistance.

  In the fourth embodiment, a light input / output member is connected to a polishing surface that serves as an optical path conversion unit. Since the light input / output member is disposed in the space removed to form the optical path conversion unit, the longitudinal dimension of the optical module can be further reduced. In the optical waveguide substrate, the surface other than the polished surface of the optical path changing unit is not limited in the flatness of the surface. For example, the surface can be roughened only by cutting by dicing, and the number of work steps can be reduced.

  In the fourth embodiment, instead of mounting an optical element or the like on the lid substrate, a metal wiring is provided on the optical waveguide substrate to mount the optical element or the like. Therefore, only the optical waveguide substrate needs to be processed, and the lid substrate can be easily manufactured. Here, the metal wiring is mounted on the optical waveguide substrate by forming a through-hole at a necessary position of the wiring by etching and depositing the metal. As other methods, sandblasting or laser beam etching can be applied.

  In the fourth embodiment, the metal wiring is also arranged in the contact area between the electric element (TIA) and the optical waveguide substrate. This is because not only the grounding (ground) of the electric element is strengthened, but also the heat generated in the electric element is released from the metal wiring. Such a metal wiring can also be installed in the contact area between the optical element and the optical waveguide substrate, and the effect of strengthening the ground of the optical element and heat dissipation can be obtained.

  As described above, according to the present embodiment, high reliability can be ensured by hermetically sealing the optical element, and a small, high-performance, and economical optical module can be provided. In the present embodiment, with respect to the component arrangement in the optical module, the optical waveguide substrate and the lid substrate (electrical wiring substrate) are stacked in the vertical direction with respect to the optical input / output direction (optical axis direction) of the optical module; It has become. Therefore, the dimension of the optical module in the optical axis direction (longitudinal direction) can be reduced compared to the configuration in which components are arranged in a straight line in the optical axis direction as in the conventional example.

  As a result, since the hermetic sealing area is reduced and the leak path is also reduced, it is possible to improve hermeticity, improve rigidity by reducing the housing size, and reduce deformation due to thermal stress and the like. As a result, high airtightness can be ensured, the reliability of the optical module is improved, and the manufacturing yield is also improved, so that a great effect of reducing the manufacturing cost of the optical module can be obtained. In addition, since the optical waveguide substrate and the lid substrate also serve as the housing, and either the optical waveguide substrate or the lid substrate also serves as the electrical wiring substrate, the number of parts of the optical module can be reduced as compared with the conventional example.

  Since the optical waveguide substrate and the lid substrate serve as a casing and the optical element is hermetically sealed, the distance between the optical element and the optical waveguide can be close. Therefore, not only the optical loss from the optical waveguide to the optical element is improved, but also when using an optical element having a small light receiving surface for the purpose of high-speed operation, the signal light can be transmitted without using many optical components such as lenses. It can be condensed on the optical element.

  Furthermore, it is not necessary to hermetically seal the connection portion between the optical fiber and the optical waveguide. In addition, since the connection between the optical input / output member and the optical waveguide substrate can be made after the optical module is hermetically sealed, the adhesive used for this connection need not have high temperature resistance. That is, there is no restriction on the adhesive material used for connection between the optical input / output member and the optical waveguide substrate, and optimal optical connection can be performed.

(Other embodiments)
In each of the embodiments described so far, various forms and combinations relating to components such as an optical path conversion unit, a lens, an optical element, and an electric element constituting the optical module have been disclosed. The combinations of the forms that these component parts can take are not limited to those described in the first to fourth embodiments.

  For example, in the first embodiment, as shown in FIG. 1, a configuration is disclosed in which an optical waveguide substrate is diced to form a groove (dicing line) to form an optical path conversion unit. As described in the second to fourth embodiments, the optical path conversion unit may have a configuration in which the polishing surface is used as the light conversion unit by polishing the end of the optical waveguide substrate. In the first embodiment, a configuration in which an optical element, an electrical element, and the like are mounted on an electrical wiring substrate that is a lid substrate is disclosed. As described in the fourth embodiment, this configuration may be configured to be arranged on the surface facing the opening of the optical waveguide substrate. Needless to say, the present invention is not limited to these examples, and may be a combination of various forms described in the first to fourth embodiments.

101, 201, 301, 401 Cover substrate 102, 202, 302, 402 Optical waveguide substrate 103, 203, 303, 403 Optical fiber 111, 311, 411 PD array 112, 312, 412 TIA
113, 213, 313, 413 Metal wiring 114 Lead pin 115, 215, 315, 415 Metal wire 116, 216, 316, 416 Electronic component 121, 221, 321, 421 Optical waveguide 122, 322, 422 Wavelength demultiplexing circuit 123, 223 , 323, 423 Optical path conversion unit 131, 331 Optical input / output member 132, 224, 311a Lens 211 LD array 212 Driver IC
217 BGA
222 Wavelength multiplexing circuit 233,433 Optical input / output member (lens)
318, 418 FPC

Claims (4)

An optical waveguide substrate having an opening in which an optical waveguide is formed and opened in only one direction;
A lid substrate joined to the optical waveguide substrate;
Wherein the opening is the optical element is mounted inside space formed by the cover substrate, the optical waveguide substrate, have a light path changing unit for coupling the optical element and the optical waveguide optically,
The optical path changing part is a slope of about 45 degrees formed so as to cross the optical waveguide perpendicular to the optical axis at a position to be the exit end of the optical waveguide;
It said inclined surface of said optical path changing unit, an optical module optical output member is characterized that it is connected for joining the optical fiber to be coupled to the optical waveguide and optical. The optical waveguide substrate, an optical module according to claim 1, characterized in that it comprises a lens in the optical path between the optical path changing unit and the optical device. The optical device is an optical module according to claim 1 or 2, characterized in that it is mounted on the surface of the cover substrate that faces the opening. The optical module according to claim 1, wherein the optical element is mounted on an inner surface of the opening of the optical waveguide substrate.

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