JP5277389B2 - Optical module - Google Patents

Description

  The present invention relates to an optical module.

  Data transmission using light has been applied to a short distance from the trunk communication network to the metro, access, and even between racks, and is expected to spread further in the home and between boards. In such short-distance optical transmission, cost reduction, miniaturization, and large capacity are strongly demanded, and those using a surface emitting laser (VCSEL) as a light source have been developed.

  On the other hand, in order to receive or transmit an optical signal transmitted through an optical fiber or the like, an optical module including an optical element that converts an optical signal and an electrical signal into each other is used. A surface light emitting device typified by the VCSEL is used for conversion from an electric signal to an optical signal, and a surface light receiving device typified by a PIN photodiode is used for conversion from an optical signal to an electric signal. These optical elements are electrically connected to the substrate, and optical fibers and the like are optically connected to the optical elements.

  Such an optical module has an optical transmission body such as an optical fiber from the viewpoint of workability when optical wiring such as an optical fiber is performed on a wiring board (printed wiring board or board), and ease of maintenance and replacement. It is desirable to be detachable via a connector.

  In addition, when an optical fiber or the like is attached to or detached from the optical element, a structure for attaching or detaching the optical fiber or the like around the component on which the optical element is mounted should be provided if it is configured to be attached to and detached from the wiring board in the horizontal direction. Since it cannot be obtained, there is a problem that other parts cannot be mounted in the space, and the mounting density cannot be increased. Therefore, it is desirable that attachment / detachment of an optical fiber or the like can be performed in a direction perpendicular to the wiring board.

  Conventionally, in order to meet such demands, an optical element is mounted so that its light emitting / receiving surface is horizontal with respect to the wiring board, and a reflection mirror is provided on the end face of an optical fiber or the like to vertically align the optical axis. There has been proposed an optical module that optically connects an optical fiber or the like and an optical element so as to be detachable in a vertical direction by using a connector converted into (see Patent Document 1).

Further, the present inventors have an optical transmission body having a structure bent in an arc shape, the optical axis on the outside side and the optical axis on the optical element side being perpendicular to each other, and a holding member for holding the optical transmission body An optical element mounting board on which a plurality of electronic components including an optical element and a driver integrated circuit device for driving the optical element are mounted, and an optical element / electronic on the wiring board. A mounting body for optically connecting the optical transmission path of the upper structure to the optical element of the optical element mounting board by pressing and fixing the upper structure on the upper surface of the component mounting board in a vertical direction; An optical module has been proposed (see Patent Document 2).
JP 2006-65358 A Japanese Patent Application No. 2007-217574

  However, in the short-distance optical transmission as described above, it cannot be said that the optical transmission path such as an optical fiber or an optical waveguide has been able to meet the expectation of cost reduction, downsizing, and large capacity at present. Further study is required.

  In addition, the optical module proposed by the present inventors described above achieves significant downsizing and detachable optical connection between the optical transmission body and the optical element in the vertical direction. In response to the spread of optical data transmission from long distances to short distances in the recent optical communication field, it has been adapted to driving at 10 Gbps / channel or lower, and high speed driving at 40 Gbps / channel or 100 Gbps. There was room for further improvement in terms of various driving.

  Furthermore, there is room for further improvement in the acquisition of DC light characteristics and the reflow resistance in the optical module design stage, the reliability of the optical module, and the cost reduction.

  The present invention has been made in view of the circumstances as described above, and uses an optical transmission technique capable of further reducing the cost, size, and capacity in an optical transmission line used for short-distance optical transmission. Improves transmission density (transmission throughput) and adapts to driving at 10 Gbps / channel or lower, and high-speed driving such as 40 Gbps and 100 Gbps in response to the spread of optical data transmission from long to short distances in recent optical communication fields It is an object of the present invention to provide an optical module that can perform various driving operations.

First, the optical module of the present invention includes:
a) An optical module that optically connects an optical transmission path for transmitting an optical signal and an optical element having at least one of a function of converting an optical signal into an electrical signal and a function of converting an electrical signal into an optical signal. And
b) An optical transmission body forming an optical transmission path, and a circle such that the optical transmission body is sandwiched between the guide groove of the upper member and the holding surface of the lower member so that the end face of the optical transmission body faces downward An upper structure including a holding member that holds the bent arcuate state ;
c) An optical element / electronic component mounting board on which an electronic component including an optical element and a driver integrated circuit device for driving the optical element is mounted, which is detachably arranged in a vertical direction on the wiring board;
d) An opening is formed in the center of the fixed end on the wiring board, and the optical element / electronic component mounting board fitted in the opening and the upper structure fitted in the opening are both pressed downward. The optical transmission line of the upper structure to the optical element of the optical element / electronic component mounting substrate, and a fitting member for optically connecting the optical element,
e) The optical element and the driver integrated circuit device are electrically connected to the electronic component mounting substrate by flip chip connection,
f) The optical transmission path is a polymer optical waveguide that transmits light in multimode, and one light incident portion that receives light of different wavelengths from two or more light emitting points adjacent to the surface light emitting element is incident. An optical transmission line body that multiplexes and transmits two or more light beams of different wavelengths, a light emission part that is branched into two or more on the emission side of the optical transmission line body, and light emitted from the light emission part There is a light receiving portion of the light receiving element that has a wavelength selection filter that is provided between the branching portion of the optical transmission path and the light receiving portion and demultiplexes the light with different wavelengths, and the core on the light incident portion side of the optical waveguide The optical waveguide is formed in a tapered shape that gradually widens toward the end, the light emitting portion side of the optical waveguide is formed in a tapered shape in which the width of the core gradually increases before the branching portion, and the light incident portion of the optical waveguide The width of the end of the light emitting point between the light emitting point on one end of the surface light emitting element and the light emitting point on the other end Characterized by comprising the wavelength-multiplexed optical transmission line structure being greater than the distance setting.
Second, in the first optical module, the mounting body made of the fitting member has a pair of protrusions on the upper edge thereof, and the upper surface of the holding member of the upper structure to be fitted and mounted. In this case, a pair of shoulder portions which form a tapered surface are brought into contact with peripheral edge portions on both sides parallel to the optical transmission line.

  The present invention is characterized by the following in order to solve the above problems.

First, an optical module of the present invention includes an optical transmission path for transmitting an optical signal, and an optical element having at least one of a function of converting an optical signal into an electrical signal and a function of converting an electrical signal into an optical signal. An optical module that is optically connected to an upper structure including an optical transmission body that forms an optical transmission path and a holding member that holds the optical transmission body, and is detachably disposed on a wiring board in a vertical direction. , An optical element / electronic component mounting board on which an electronic component including an optical element and a driver integrated circuit device for driving the optical element is mounted, and an optical transmission path of an upper structure with respect to the optical element of the optical element / electronic component mounting board and a fitting member for connecting optically to the optical element and the driver integrated circuit device is electrically connected to the electronic component mounting board by flip chip connection, the optical transmission path, transmits light in multiple modes Polymer A waveguide, and light transmitted and one light introduction unit which introduces light of a different wavelength from the adjacent two or more light emitting points of the surface light emitting device, the light of two or more different wavelengths incident multiplexed to There are a transmission path main body , a light emitting section that is branched into two or more on the emission side of the optical transmission path main body , and a light receiving section of a light receiving element that receives light emitted from the light emitting section. And a wavelength selection filter for separating light of different wavelengths provided between the light receiving portions, and the width of the core on the light incident portion side of the optical waveguide is gradually curved into a curved shape connecting arcs toward the ends. The light output part side of the optical waveguide is formed in a taper shape that gradually expands into a curved shape with the width of the core connecting arcs before the branch part, and further, the light incident part of the optical waveguide The width of the end portion is between the light emitting point on one end side of the surface light emitting element and the light emitting point on the other end side. Characterized by comprising the wavelength-multiplexed optical transmission line structure is greater than away.

Second, in the first optical module, the light incident part of the wavelength division multiplexing optical transmission line structure is configured to receive light from a light emitting point whose distance between centers of the light emitting points is 10 to 40 μm from the surface light emitting element. It is configured.

Thirdly, in the first or second optical module, the width of the core of the light incident portion of the optical waveguide of the wavelength division multiplexing optical transmission line structure is formed in a tapered shape extending in a curved shape connecting arcs. It is characterized by.

Fourthly, in any one of the first to third optical modules, the width of the core in front of the branching portion on the light emitting part side of the optical waveguide of the wavelength division multiplexing optical transmission line structure expands into a curved shape connecting arcs. It is characterized by being formed in a tapered shape .

Fifthly, in any one of the first to fourth optical modules, the optical element has a lens integrally provided on an upper surface thereof. module.

Sixth, in the fifth optical module, the lens is a semiconductor lens .

Seventh, in any one of the first to sixth optical modules, the optical element / electronic component mounting board has electronic components mounted in a cavity surrounded by a wall portion standing on the board. The cavity is partially sealed with resin, including the entire surface inside the cavity .

Eighth, in any one of the first to sixth optical modules, the optical element / electronic component mounting substrate has electronic components mounted in a cavity surrounded by a wall portion standing on the substrate, The cavity is sealed with a light-transmitting substrate .

Ninth, in any one of the first to eighth optical modules, at least a part of the electrode pattern formed on the lower surface of the optical element and driver integrated circuit device on the optical element / electronic component mounting substrate is a heat spreader. It is characterized by being connected to .

In the optical modules of the first , third and fourth inventions, the optical element and the driver integrated circuit device are electrically connected to the optical element / electronic component mounting substrate by flip chip connection. Compared with the above case, it is excellent in manufacturability such as acquisition of DC light characteristics and flow resistance in the design stage of the optical module, has high reliability, and can be manufactured at low cost. Further, in short-distance optical transmission that is expected to be rapidly developed in the future, further cost reduction, downsizing, large capacity (improvement of transmission density), simplification of configuration, and low power consumption can be achieved. Furthermore, it becomes possible to perform various driving suitable for driving at 10 Gbps / channel or less and high-speed driving such as 40 Gbps or 100 Gbps.
Further, since the optical waveguide of the wavelength multiplexing optical transmission line structure is a polymer optical waveguide, in addition to the above effects, the wavelength multiplexing optical transmission line structure can be manufactured more easily and at a lower cost, and the optical module has a lower optical module. Cost can be reduced.
In addition to the above effect, the width shape of the core of the light incident portion of the wavelength division multiplexing optical transmission line structure is a tapered shape that gradually expands toward the end, and a curved shape that connects arcs. The positional deviation tolerance (tolerance) between the surface light emitting element and the light incident portion can be increased. Furthermore, the core of the light incident part is formed into a curved shape connecting arcs, so that the inclination of the core taper part and the width of the core width before and after the core do not become discontinuous, so that the light of the core Loss can be suppressed without leaking outside.
In addition, the width of the core in front of the branching portion of the light emitting part of the wavelength division multiplexing optical transmission line structure is a tapered shape that gradually widens, and a curved shape that connects arcs. In addition, insertion loss due to branching can be minimized.
Furthermore, by using an optical transmission path in which the light propagating through the optical transmission path is a multimode, in addition to the above effects, a large positional deviation tolerance between the optical element and the optical transmission path can be obtained.

  According to the optical module of the second aspect of the present invention, light from a light emitting point having a very short distance between the centers of the light emitting points of the surface light emitting element having the wavelength multiplexing optical transmission line structure can be incident. Two or more lights from the element can be easily incident on the light incident part directly without using a lens or a mirror.

In the optical module of the fifth aspect, since the lens is integrally provided on the upper surface, in addition to the above effects, the optical element can be easily sealed with resin, and an optical module having high reliability can be easily manufactured. can do.

Since the optical module of the sixth invention uses a semiconductor lens, in addition to the above effects, the lens can be prevented from being altered or damaged due to resin sealing or heating during reflow. Furthermore, since the refractive index of the semiconductor lens is high, high optical coupling efficiency between the optical element and the optical transmission body can be ensured even when the optical element is covered with a resin sealing material.

In the optical module according to the seventh aspect of the invention, since the optical component / electronic component mounting substrate is formed in the cavity shape, the electronic component is mounted therein, and the cavity is resin-sealed. Resin sealing is easy and an optical module having high reliability can be easily manufactured.

In the optical module according to the eighth aspect of the invention, the electronic component mounting substrate is formed into a cavity shape, the electronic component is mounted therein, and the cavity is sealed with a translucent resin, so that the optical element can be easily sealed. Thus, an optical module having high reliability can be easily manufactured.

In the optical module according to the ninth aspect of the invention, at least a part of the electrode pattern formed at the position of the lower surface portion of the optical element and driver integrated circuit device in the optical element / electronic component mounting substrate is connected to the heat spreader. In addition to the above effects, it excels in heat dissipation during operation and has high reliability.

  In this specification, the “optical transmission body” includes an optical fiber made of glass or resin, an optical waveguide made of resin, or the like. In the following embodiment, an example using an optical waveguide will be described. However, the optical transmission body applied in the present invention is not limited to this, and various types of optical transmission lines such as an optical fiber can be configured. Things can be applied.

  In the present specification, the “optical element” includes not only one having a single light receiving / emitting surface but also one having a plurality of light receiving / emitting surfaces arranged in an array or the like. Specific examples of the optical element include a surface light emitting element such as a VCSEL and a surface light receiving element such as a PIN photodiode. The surface light emitting elements and / or the light receiving and emitting surfaces of the surface light receiving elements are arranged in an array. It may be integral.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 are perspective views showing an optical module according to an embodiment of the present invention. FIG. 1 shows a state in which the optical connection and the electrical connection are disconnected, and FIG. 2 shows a state in which the optical connection and the electrical connection are made. Yes.

  As shown in FIG. 1, the optical module 1 of the present embodiment includes an optical element / electronic component mounting board on which an upper structure 5 in which an optical waveguide 7 is held by a holding member 6, an optical element 40, and an electronic component 41 are mounted. 30, an anisotropic conductive sheet 60, and a fitting member 50 fixed on a wiring board 70 (printed wiring board or board).

  In this optical module 1, an anisotropic conductive sheet 60 is arranged in an opening 51 in a fitting member 50 on a wiring board 70, an optical element / electronic component mounting board 30 is arranged thereon, and further from above By fitting the upper structure 5 vertically as shown in FIG. 2, the optical waveguide 7 of the upper structure 5 and the optical element 40 of the optical element / electronic component mounting substrate 30 are optically connected to each other. The element / electronic component mounting board 30 and the wiring board 70 are electrically connected via an anisotropic conductive sheet 60. The mounted optical module 1 shown in FIG. 2 constitutes a compact module having a width of 10 mm × 10 mm and a thickness of 6.4 mm, for example.

  As shown in FIGS. 3A and 3B, the upper structure 5 includes a plurality of (in this embodiment, 12) optical waveguides 7 arranged in parallel from the back surface of the resin holding member 6. The tape-shaped waveguide 8 enters the holding member 6 horizontally, the optical waveguide 7 is bent in an arc shape in the holding member 6, and the end surface 7 a of the optical waveguide 7 is vertically exposed from the lower surface of the holding member 6. doing.

  A pair of shoulder portions 12 having a tapered surface along the peripheral edge portion are provided on both peripheral edges parallel to the optical waveguide 7 on the upper surface of the holding member 6 and are fitted into the fitting member 50 of FIG. The pair of protrusions 52 provided on the upper portion of the fitting member 50 abuts against the shoulder 12 of the holding member 6 and presses downward.

  Further, as shown in FIG. 1, the holding member 6 is provided with two positioning holes 11, and when fitted into the fitting member 50 of FIG. A positioning pin 42 erected on the holding member 6 is inserted into the positioning hole 11 of the holding member 6 so that the upper structure 5 and the optical element / electronic component mounting board 30 are positioned in the horizontal direction.

  The holding member 6 includes an upper member 10 and a lower member 20 as shown in FIGS. 3A and 3B, and the optical waveguide 7 is sandwiched between the upper member 10 and the lower member 20. It comes to hold. On the other hand, an upper surface side of the lower member 20 is provided with an optical waveguide holding surface having a curved surface corresponding to the arc shape of the optical waveguide 7, and by sandwiching the optical waveguide 7 between the upper member 10 and the lower member 20, The optical waveguide 7 is held in a state of being bent in an arc shape between the guide groove of the upper member 10 and the optical waveguide holding surface of the lower member 20.

  The radius of curvature R of the arc portion between the external optical axis 65a and the optical element side optical axis 65b of the optical waveguide 7 is preferably 5 mm or less, more preferably 1 to 3 mm. Thus, the radius of curvature of the arc portion is very small, the vertical direction of the upper structure 5 is reduced, and the horizontal direction is also reduced in size.

  4 is a top side perspective view of the optical element / electronic component mounting substrate 30, FIG. 5 is a partial cross-sectional view, and FIG. 6 is a cross section showing a state where the upper structure and the optical element / electronic component mounting substrate are optically connected. FIG. As shown in FIG. 4, the optical element / electronic component mounting substrate 30 includes a box-shaped ceramic substrate 31 in which a wall portion 32 is erected along the outer peripheral portion, and a position on the front side on the ceramic substrate 31. An optical element 40 in which a number of light receiving and emitting surfaces corresponding to the optical waveguide 7 are arranged side by side is mounted.

  The optical element / electronic component mounting substrate 30 is mounted with electronic components such as the optical element 40 and a driver integrated circuit device 41 for driving the optical element 40 on the bottom surface of the cavity 34 surrounded by the wall portion 32. The inside 34 is sealed with a sealing resin 38 as shown in FIG. As the optical element 40, for example, an element having a thickness of about 100 to 150 μm can be used.

  The optical element 40 includes a VCSEL as a surface light emitting element and a PIN photodiode as a surface light receiving element. The upper surface 32a of the wall portion 32 constitutes an optical reference surface, and comes into contact with the lower surface of the upper structure 5 so that the end surface 7a of the optical waveguide 7 and the optical element 40 are vertically aligned as shown in FIG. Positioned.

  As shown in FIG. 4, a pair of positioning pins 42 having a protruding height of 2 mm and a protruding portion diameter of 0.7 mm are erected at positions on both sides of the optical element 40 on the ceramic substrate 31. By inserting the positioning pins 42 into the positioning holes 11 of the upper structure 5, the optical element / electronic component mounting board 30 and the upper structure 5 are positioned in the horizontal direction.

  A driver integrated circuit device 41 is mounted behind the optical element 40 on the ceramic substrate 31. The optical element 40 and the driver integrated circuit device 41 are flip-chip connected via bumps 40a and 41a as shown in FIG. Are connected to the electrode pattern 36 on the ceramic substrate 31.

  A part of the electrode pattern 36 to which the bumps 40a and 41a of the optical element 40 and the driver integrated circuit device 41 are connected, through a through hole (not shown) penetrating the ceramic substrate 31 through the printed wiring 33 and the like of FIG. It is electrically connected to a pad provided on the back surface of the ceramic substrate 31.

  Further, as shown in FIG. 5, the other part of the electrode pattern 36 is connected to a heat spreader 37 that spreads in the horizontal direction, and the heat from the optical element 40 and the driver integrated circuit device 41 during the operation of the optical module 1. Is diffused to the heat spreader 37 through the electrode pattern 36.

  The heat spreader 37 may be embedded in the ceramic substrate 31 as shown in FIG. 5, for example, or may be provided on the surface of the ceramic substrate 31. Further, the heat spreader 37 may be provided on another external structure, for example, the wiring board 70, as long as no electrical influence is given.

  The specific arrangement and form of the heat spreader 37 are not particularly limited as long as they do not affect the signal line, the power supply, etc., and can be, for example, a wiring pattern or a plate.

  The heat spreader 37 can have good thermal conductivity by being formed by the same method as that for forming the wiring of the ceramic substrate 31, for example, a method such as screen printing. Also, the heat spreader 37 can be formed simultaneously with the process of forming the wiring of the ceramic substrate 31. Alternatively, the heat spreader 37 may be formed in a process different from the wiring formation, for example, the heat spreader 37 may be attached to the ceramic substrate 31 after the wiring of the ceramic substrate 31 is formed.

As shown in FIG. 5, the optical element 40 is integrally provided with a semiconductor lens 40b on its upper surface. As the semiconductor lens 40b, for example, a lens having a radius of curvature of 80 to 200 [mu] m and a lens opening diameter of about 70 [mu] m can be used, and as the material, a compound semiconductor such as InP or GaAs can be used.

  The semiconductor lens 40b can be manufactured by the following method, for example. After applying a resist to the element substrate on the light incident / exit side of the optical element 40, the resist is heated and cured to form a lens-like resist, and then the resist is processed by ion milling. The lens shape is transferred onto the substrate of the optical element 40. Finally, an antireflective film is formed on the transferred lens.

  Although not shown, the semiconductor lens 40b is disposed on each of the plurality of light emitting / receiving units arranged in the direction perpendicular to the paper surface, and the end surface 7a of the optical waveguide 7 is formed by the fitting member 50 as shown in FIG. When the optical element 40 and the optical element 40 are positioned in the vertical direction, they are optically aligned by the semiconductor lens 40b.

  The anisotropic conductive sheet 60 shown in FIG. 1 ensures electrical conduction in the vertical direction by pressurization, and various types can be used without particular limitation. For example, an insulating material having elasticity such as silicone rubber can be used. A substrate in which conductive particles such as metal are arranged in the thickness direction or a conductive wire embedded therein can be used. The thickness of the anisotropic conductive sheet 60 is, for example, 0.1 to 1 mm.

  Next, the “optical transmission body” described above as the optical waveguide 7 will be described in detail.

In this embodiment, a wavelength division multiplexing optical transmission line structure is used as the “optical transmission line”. This wavelength division multiplexing optical transmission line structure can take the following three forms.
(1) An optical transmission path main body that multiplexes and transmits one or more incident light beams having different wavelengths from two or more light emitting points adjacent to the surface light emitting element. A wavelength division multiplexing optical transmission line structure characterized by comprising:
(2) an optical transmission line main body that transmits a combination of two or more different wavelengths of light from the surface light emitting element, a light emission unit that is branched into two or more on the emission side of the optical transmission line main body, and light There is a light receiving portion of a light receiving element that receives light emitted from an emitting portion, and includes a wavelength selection filter that is provided between a branch portion of an optical transmission path and a light receiving portion and demultiplexes light having different wavelengths. Wavelength multiplexed optical transmission line structure.
(3) One light incident portion for entering light of different wavelengths from two or more light emitting points adjacent to the surface light emitting element, and an optical transmission line main body for combining and transmitting the incident light of two or more different wavelengths A wavelength multiplex optical transmission line structure, and an optical transmission line main body that transmits a combination of two or more different wavelengths of light from the surface light emitting element, and two or more branches on the output side of the optical transmission line main body. Wavelength selection filter for splitting light with different wavelengths provided between the branching portion of the optical transmission path and the light receiving portion, and a light receiving portion of the light receiving element that receives the light emitted from the light emitting portion. A combined wavelength division multiplexing optical transmission line structure comprising:

  In the present invention, the light propagating through the optical transmission path can be an optical transmission path in which the multimode is used. In that case, the positional deviation tolerance between the optical element and the optical transmission path can be increased.

  In the above, each wavelength division multiplexing optical waveguide structure may be constituted independently, or a plurality of plural wavelength optical waveguide structures may be constituted. When performing light transmission over a short distance, the light incident part and the light reflecting part may be provided together in one module, or if both are provided to some extent or considerably separated from each other, they may be provided separately. It may be provided as a module.

  Here, a case where the wavelength division multiplexing optical transmission structure is constituted by an optical waveguide will be described as an example. Of course, the present invention is not limited to the optical waveguide but is applied to various optical transmission lines such as an optical fiber.

  In FIG. 7, the structural example of the optical waveguide 21 which concerns on this embodiment is typically shown with a top view. In this example, optical transmission of two wavelengths is performed, the left side is the incident side station, and the right side is the emission side station. Both stations may be provided as separate modules or may be provided as the same module. Further, the same module may include each station in any combination. In FIG. 7, 21 is an optical waveguide, 21a is an incident side portion of the optical waveguide 21, 21b is an output side portion of the optical waveguide 21, 22 is a surface light emitting element (VCSEL), 23 is a surface light emitting element (VCSEL) drive circuit, 24 -1, 24-2 are wavelength selection filters, 25 (25-1, 25-2) are surface light receiving elements (PD), and 26 is an amplifier.

  The surface light emitting device (VCSEL) 22 has two light emitting points 22-1 and 22-2 provided adjacent to each other, and emits light having different wavelengths λ1 and λ2. The light of the wavelengths λ1 and λ2 is incident on the incident side portion 21a of the optical waveguide 21 and is combined and transmitted through the optical waveguide 21.

  The exit side portion 21b of the optical waveguide 21 is branched into two portions 21b-1 and 21b-2. A wavelength selection filter 24-1 and a surface light receiving element (PD) 25-1 are provided for the emission side portion 21b-1, and a wavelength selection filter 24-2 and a surface light reception element (PD) are provided for the emission side portion 21b-2. ) 25-2. The wavelength selection filter 24-1 transmits light of wavelength λ1, and blocks light of other wavelengths. On the other hand, the wavelength selection filter 24-2 transmits light of wavelength λ2, and blocks light of other wavelengths.

  Here, the shape of the actually produced polymer optical waveguide is shown in FIG. The polymer optical waveguide is composed of a core and a clad surrounding the core. 8A is a plan view showing the shape of the core on the light incident side, and FIG. 8B is a plan view showing the shape of the core on the light exit side. The optical waveguide 21 includes a core and a clad, and the core and the clad can be configured using acrylic resin, epoxy resin, or the like and having different refractive indexes. In one example of the present embodiment, the core on the light incident side has a tapered shape with a width (vertical) extending from 50 μm to 90 μm toward the end surface. The thickness (height) is 50 μm. In the present embodiment, one of the main features is that the core on the light incident side has a tapered shape whose width increases toward the end face. Specifically, the light incident portion 21a of the optical waveguide 21 is formed in a taper shape whose width shape expands into a curved shape connecting arcs. In this way, it is possible to increase the positional deviation tolerance (tolerance) between the incident light from the surface light emitting element 22 and the incident side portion 21a of the optical waveguide 21. FIG. 9 shows the dependence of the insertion loss on the incident position. From this figure, it can be seen that the incident position tolerance is expanded by 40 μm. Two wavelengths of light having wavelengths λ1 and λ2 are incident from the end face of the incident side portion 21a of the optical waveguide 21.

  On the other hand, the light-emitting side core is once tapered and expanded from 50 μm width to 100 μm width, and then divided into two at the Y branch. More specifically, the width of the core in front of the branching portion of the light emitting portion 21b is a tapered shape that gradually expands, and a shape that expands into a curved shape connecting arcs. When the arcuate curvature is 10 mm or more, the insertion loss can be minimized. And incident light can be branched to 1: 1. The length of the spreading portion of the core before the branching portion was set to more than 1000 μm. The length of the tapered portion is set in consideration of conditions such as the wavelength, the core width, and the light divergence angle, and is preferably 500 μm or more, more preferably 1000 μm or more. The insertion loss in this Y branch is shown in FIG. From this figure, the optical power decreases by 3 dB due to the branching, but a sufficient loss budget can be secured for short-distance transmission.

  In the above example, light of two different wavelengths λ1 and λ2 is incident and combined, transmitted through an optical transmission line composed of the optical waveguide 21, and the transmitted multiplexed signal is split into two on the light output side. It is like that. In this way, since optical data transmission / reception with the wavelength λ1 and optical data transmission / reception with the wavelength λ2 can be performed together, the transmission density can be further improved.

  Next, the structure of a monolithic two-wavelength VCSEL 100 (22) which is an example of a surface light emitting device (VCSEL) used in the present embodiment is shown in a sectional view in FIG. The VCSEL 100 has two adjacent mesa structures formed on a p-type GaAs substrate 101. This mesa structure includes a laminated lower DBR (Distributed Bragg Reflector) layer 102, an oxidized constricting layer 103, an active layer 104 having a QW (quantum well structure), and a first upper DBR layer 105. On the first upper DBR layer 105, a phase control layer 106 and a stacked second upper DBR layer 107 are provided. Reference numeral 108 denotes a lower electrode, and reference numeral 109 denotes an upper electrode. The oscillation wavelength can be changed by changing the thickness of the phase control layer 106.

  In the monolithic two-wavelength VCSEL 100 of this example, the distance between the light emitting points was about 30 μm, the oscillation wavelengths were 853 nm and 867 nm, and the oscillation wavelength was different by 14 nm. FIG. 12 shows how the VCSEL 100 oscillates. FIG. 13 shows an eye diagram when the VCSEL 100 operates at 8, 10, and 13 Gbps, respectively. It can be seen that a clear eye opening is obtained even at 13 Gbps.

  When the above monolithic two-wavelength VCSEL 100, the combining polymer optical waveguide 21 and the GI50 multimode optical fiber (arranged between the light incident side and the light emitting side) are combined, the incident tolerance and the optical wavelength spectrum after transmission are calculated. Examined. The incident tolerance was obtained by moving the optical waveguide 21 on the XY plane while causing the VCSEL 100 to emit light, and creating a map of optical power after passing through the optical waveguide 21. FIGS. 14A and 14B show optical power maps when the VCSEL 100 having a light-emitting point center distance of 30 μm is caused to emit light. Due to the difference in the light emission position, a shift is observed in the region indicated by the dark density where the optical power is large. FIG. 14C is a map by light emission from both light emitting points of the VCSEL 100. FIG. 14D shows an optical power region within -1 dB from the maximum intensity. From 14 (d), the positional tolerance of 1 dB down between the VCSEL chip and the optical waveguide was ± 10 μm or more despite the light emitting point being 30 μm away.

  FIG. 15 shows a spectrum of light that is emitted from two adjacent light emitting points having different wavelengths and propagates through the optical waveguide. Peaks are seen at wavelengths of 853 nm and 867 nm, indicating that light from two light emitting points having different wavelengths is incident on the core of one optical waveguide and transmitted, and that multiplexing is performed. confirmed.

  FIG. 16 is a schematic plan view of the optical waveguide 21 when performing optical transmission of three wavelengths. Light of three different wavelengths of wavelengths λ1, λ2, and λ3 is incident on the light incident side portion 21a of the optical waveguide 21. Further, the light emission side portion 21b branches into three portions 21b-1, 21b-2, and 21b-3, and only the light having the wavelength of the wavelength selection filter 24-1 and λ2 that transmits only the light having the wavelength of λ1, respectively. A wavelength selection filter 24-2 that transmits light and a wavelength selection filter 24-3 that transmits only light having a wavelength of λ3 are provided. Also in this case, since transmission and reception of optical data using the three wavelengths λ1, λ2, and λ3 can be performed on the same principle as in the case of the two wavelengths, the transmission density can be further improved.

  In addition, according to the present invention, optical data transmission / reception can be performed using multiple wavelengths of 4 wavelengths or more.

  The wavelength multiplexed optical transmission line structure has been described above by taking the optical waveguide as an example. However, the present invention is not limited to the optical waveguide, and can be applied to an optical fiber by using a photocoupler or the like.

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

  For example, in the above embodiment, the upper structure 5 is detachably mounted in the vertical direction using the fitting member 50 as the mounting body, and the upper structure is mounted on the optical element 40 of the optical element / electronic component mounting substrate 30. 5 optical transmission lines were optically connected, but there are various types of mounting structures such as clamp springs, screwing structures, leaf spring structures, latch structures, and open / close clamp springs having such functions. Can be used.

  As the optical element 40, a surface light emitting element other than a VCSEL such as a laser diode may be used, or a surface light receiving element other than a PIN photodiode may be used.

  In the above embodiment, the example in which the optical element / electronic component mounting board 30 and the wiring board 70 are electrically connected via the anisotropic conductive sheet 60 has been described. As the electrical connection structure with the substrate 70, various structures such as a structure in which the optical element / electronic component mounting substrate 30 is solder-connected to the wiring substrate 70 can be used.

FIG. 1 is a perspective view showing an optical module according to an embodiment of the present invention, and shows a state where an optical connection and an electrical connection are disconnected. FIG. 2 is a perspective view showing a state where optical connection and electrical connection are made in the optical module of FIG. 3A and 3B are views showing the arrangement of the upper member, the optical fiber, and the lower member of the upper structure, in which FIG. 3A is a perspective view and FIG. 3B is a cross-sectional view. FIG. 4 is a perspective view of the optical element / electronic component mounting substrate. FIG. 5 is a partial cross-sectional view of the optical element / electronic component mounting substrate. FIG. 6 is a cross-sectional view showing a state where the upper structure and the optical element / electronic component mounting substrate are optically connected. FIG. 7 is a plan view schematically showing a structural example of the optical waveguide according to the present embodiment. 8A and 8B are diagrams showing the shape of the actually produced polymer waveguide. FIG. 8A is a plan view showing the shape of the core on the light incident side, and FIG. 8B is a plan view showing the shape of the core on the light output side. is there. FIG. 9 is a diagram illustrating the dependence of the insertion loss on the incident position. FIG. 10 is a diagram showing insertion loss in the Y branch. FIG. 11 is a cross-sectional view showing the structure of a monolithic two-wavelength VCSEL. FIG. 12 is a diagram illustrating a state in which the monolithic two-wavelength VCSEL oscillates. FIG. 13 is an eye diagram when the VCSEL operates at each transmission rate. FIG. 14 shows a VCSEL power map. FIG. 15 is a diagram showing a spectrum of light emitted from two light emitting points having different wavelengths and propagated through an optical waveguide. FIG. 16 is a schematic plan view of an optical waveguide when three-wavelength optical transmission is performed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical module 5 Upper structure 6 Holding member 6a Lower surface 7 Optical waveguide 7a End surface 8 Tape-shaped optical waveguide 10 Upper member 11 Positioning hole 12 Shoulder part 20 Lower member 21 Optical waveguide 21a Incident side part 21b (21b-1, 21b- 2) Output side portion 22 Surface light emitting device (VCSEL)
22-1, 22-2 Light emitting point 23 Surface light emitting element driving circuit 24-1, 24-2 Wavelength selection filter 25 (25-1, 25-2) Surface light receiving element (PD)
30 Optical element / electronic component mounting substrate 33 Printed wiring 34 Cavity 36 Electrode pattern 37 Heat spreader 38 Sealing resin 40 Optical element 40a Bump 40b Semiconductor lens 41 Driver integrated circuit device 41a Bump 42 Positioning pin 50 Fitting member 60 Anisotropic conductive sheet 70 Wiring board

Claims (9)

a) An optical module that optically connects an optical transmission path for transmitting an optical signal and an optical element having at least one of a function of converting an optical signal into an electrical signal and a function of converting an electrical signal into an optical signal. And
b) An optical transmission body forming an optical transmission path, and a circle such that the optical transmission body is sandwiched between the guide groove of the upper member and the holding surface of the lower member so that the end face of the optical transmission body faces downward An upper structure including a holding member that holds the bent arcuate state ;
c) An optical element / electronic component mounting board on which an electronic component including an optical element and a driver integrated circuit device for driving the optical element is mounted, which is detachably arranged in a vertical direction on the wiring board;
d) An opening is formed in the center of the fixed end on the wiring board, and the optical element / electronic component mounting board fitted in the opening and the upper structure fitted in the opening are both pressed downward. The optical transmission line of the upper structure to the optical element of the optical element / electronic component mounting substrate, and a fitting member for optically connecting the optical element,
e) The optical element and the driver integrated circuit device are electrically connected to the electronic component mounting substrate by flip chip connection,
f) The optical transmission path is a polymer optical waveguide that transmits light in multimode, and one light incident portion that receives light of different wavelengths from two or more light emitting points adjacent to the surface light emitting element is incident. An optical transmission line body that multiplexes and transmits two or more light beams of different wavelengths, a light emission part that is branched into two or more on the emission side of the optical transmission line body, and light emitted from the light emission part There is a light receiving portion of the light receiving element that has a wavelength selection filter that is provided between the branching portion of the optical transmission path and the light receiving portion and demultiplexes the light with different wavelengths, and the core on the light incident portion side of the optical waveguide The optical waveguide is formed in a tapered shape that gradually widens toward the end, the light emitting portion side of the optical waveguide is formed in a tapered shape in which the width of the core gradually increases before the branching portion, and the light incident portion of the optical waveguide The width of the end of the light emitting point between the light emitting point on one end of the surface light emitting element and the light emitting point on the other end Light module, comprising the wavelength-multiplexed optical transmission line structure is configured from a distance greater.   2. The light incident part of the wavelength division multiplexing optical transmission line structure is configured to receive light from a light emitting point whose distance between centers of the light emitting points from the surface light emitting element is 10 to 40 [mu] m. The optical module as described in.   3. The optical module according to claim 1, wherein the width of the core of the light incident portion of the optical waveguide of the wavelength division multiplexing optical transmission line structure is formed in a tapered shape extending in a curved shape connecting arcs. 4.   4. The width of the core in front of the branching portion on the light emitting portion side of the optical waveguide of the wavelength division multiplexing optical transmission line structure is formed in a tapered shape extending in a curved shape connecting arcs. An optical module according to any one of the above.   The optical module according to claim 1, wherein a lens is integrally provided on an upper surface of the optical element.   The optical module according to claim 5, wherein the lens is a semiconductor lens.   In the optical element / electronic component mounting substrate, electronic components are mounted in a cavity surrounded by a wall portion standing on the substrate, and the cavity is partially resin-sealed including the entire surface inside the cavity. The optical module according to claim 1, wherein the optical module is an optical module.   The optical element / electronic component mounting substrate is characterized in that electronic components are mounted in a cavity surrounded by a wall portion standing on the substrate, and the cavity is sealed by a translucent substrate. An optical module according to any one of claims 1 to 6.   9. At least a part of an electrode pattern formed at a position of a lower surface portion of the optical element and driver integrated circuit device on the optical element / electronic component mounting substrate is connected to a heat spreader. The optical module as described in.