JP2015055669A - Optical modulator module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize an optical modulator module.SOLUTION: An optical modulator module 10 includes: an optical modulator 20; an electrical terminal 30 that is connected to the optical modulator 20; and a housing 40 that houses the optical modulator 20 and the electrical terminal 30. The optical modulator 20 includes: a light guide 2; and a conductor layer 6 in which a high frequency electric signal for modulating a phase of light transmitted through the light guide 2 is inputted. The electrical terminal 30 includes: a terminal substrate 11; and a terminal circuit 12 that terminates the high frequency electric signal through the conductor layer 6. At least a part of the electrical terminal 30 is provided at a position superimposed on the optical modulator 20 in a planar view.

Description

  The present invention relates to an optical modulator module with electrical termination.

2. Description of the Related Art Conventionally, an optical modulator using a lithium niobate (LiNbO ₃ ) substrate having a so-called electro-optic effect whose refractive index is changed by applying an electric field has been used.
In recent years, an optical modulator using a substrate made of a semiconductor material capable of controlling light by electricity such as silicon or indium phosphide (InP) has been developed.

FIG. 4 is a diagram illustrating an example of an optical modulator module (see Patent Document 1).
The optical modulator module 110 shown here includes an optical modulator 120, an electrical termination unit 130 that terminates a high-frequency electrical signal, and a housing 40 that accommodates these.
The optical modulator 120 includes a substrate 1, an optical waveguide 2 formed on the substrate 1, and a traveling wave electrode 106 formed on the substrate 1.
The traveling wave electrode 106 includes a central wiring 103 and side wirings 104 and 105 formed on both sides of the central wiring 103.
The substrate 1 has a rectangular shape in plan view having side edges 1d and 1e having long sides and end edges 1f and 1g having short sides.

  The optical waveguide 2 is formed along the longitudinal direction of the substrate 1, and optical fibers 100 and 101 are connected to both ends thereof.

The electrical termination 130 has a termination circuit 112 formed on one surface of the termination substrate 111. The termination circuit 112 is connected to the wirings 103 to 105 of the optical modulator 120 and has a function of terminating the high-frequency electrical signal.
The electrical termination unit 130 is installed on the side of the optical modulator 120. The optical modulator 120 and the electrical terminal 130 are installed side by side on the bottom plate 41 of the housing 40. Since the electrical termination 130 is disposed on the side of the substrate 1, it does not interfere with the optical fibers 100 and 101.

JP 2011-175305 A

Although this type of optical modulator module is required to be downsized, the conventional optical modulator module has not been able to meet this demand.
The present invention has been made in view of the above problems, and an object thereof is to provide an optical modulator module that can be miniaturized.

The present invention employs the following means in order to solve the above problems.
The present invention includes an optical modulator, an electrical termination connected to the optical modulator, and a housing that houses the optical modulator and the electrical termination, and the optical modulator An optical waveguide provided on a modulator substrate; and a conductor layer to which a high-frequency electrical signal that modulates the phase of light propagating through the optical waveguide is input, and the electrical termination is a termination substrate; A termination circuit formed on the termination substrate and terminating the high-frequency electrical signal that has passed through the conductor layer, and at least a part of the electrical termination is located at a position overlapping the optical modulator in plan view. Provided is an optical modulator module.
It is preferable that the electrical terminal is fixed to the optical modulator via a fixing means.
The fixing means is preferably a bump or an adhesive layer.
The termination circuit of the electrical termination portion can be electrically connected to the conductor layer through a through electrode formed on the termination portion substrate.
The electrical termination may be fixed to the housing.

According to the present invention, since at least a part of the electrical termination is provided at a position overlapping the optical modulator in plan view, the space occupied by the optical modulator and the electrical termination in the housing can be reduced. .
Therefore, it is possible to reduce the size of the optical modulator module.

(A) It is a plane sectional view showing the composition of the optical modulator module concerning a 1st embodiment. (B) It is a sectional side view of the optical modulator module of (a). (A) It is a plane sectional view showing the composition of the optical modulator module concerning a 2nd embodiment. (B) It is a sectional side view of the optical modulator module of (a). It is a sectional side view which shows the structure of the optical modulator module which concerns on 3rd Embodiment. It is the plane sectional view and side sectional view which show the structure of the conventional optical modulator module.

Hereinafter, based on a preferred embodiment, the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram illustrating a configuration of an optical modulator module 10 according to the first embodiment. FIG. 1A is a plan sectional view of the optical modulator module 10, and FIG. 1B is a side sectional view of the optical modulator module 10.
As shown in FIG. 1A, the optical modulator module 10 includes an optical modulator 20 that modulates the phase of light by applying a high-frequency electrical signal, an electrical termination unit 30 that terminates the high-frequency electrical signal, And a housing 40 that houses the optical modulator 20 and the electrical termination 30.

  As shown in FIG. 1B, the housing 40 includes a rectangular (rectangular in the illustrated example) bottom plate 41, a side plate 42 erected on the periphery thereof, and an upper plate 43 provided on the upper edge of the side plate 42. And.

  As shown in FIG. 1A, the optical modulator 20 includes an optical modulator substrate 1 (hereinafter simply referred to as a substrate 1), an optical waveguide 2 formed on the main surface 1 c of the substrate 1, and a main substrate 1. A traveling wave electrode 6 (conductor layer) formed on the surface 1c.

The substrate 1 is made of a material having an electro-optic effect that can control light by electricity.
An example of a material having such an electro-optic effect is lithium niobate (LiNbO ₃ ). In addition, as a material having an electrooptic effect, a semiconductor material such as silicon or indium phosphide (InP) can also be used.

The substrate 1 is rectangular in plan view. Hereinafter, the dimension in the longitudinal direction of the substrate 1 may be referred to as the length, and the dimension in the short direction may be referred to as the width.
One long side of the substrate 1 is referred to as a side edge 1d, and the other long side is referred to as a side edge 1e. One short side of the substrate 1 is referred to as an edge 1f, and the other short side is referred to as an edge 1g.
The substrate 1 can be installed on the bottom surface 41a of the bottom plate 41 of the housing 40 along the bottom surface 41a.

The optical waveguide 2 is formed on the main surface 1 c of the substrate 1 along the longitudinal direction of the substrate 1.
The optical waveguide 2 includes an input waveguide 2a formed at one longitudinal end 1a of the substrate 1, branch waveguides 2b and 2c in which the input waveguide 2a branches into two, and branch waveguides 2b and 2c as one. This is a so-called Mach-Zehnder interferometer (or a waveguide Mach-Zehnder type waveguide) integrally provided with an output waveguide 2d formed at the other end 1b in the longitudinal direction of the substrate 1.
One branch waveguide 2 b of the optical waveguide 2 is formed along the central wiring 3 of the traveling wave electrode 6, and the other branch waveguide 2 c is formed along the side wiring 5.

  An input side optical fiber 100 is connected to the optical waveguide 2 at the input waveguide 2 a at one end 1 a in the longitudinal direction of the substrate 1. The output-side optical fiber 101 is connected to the optical waveguide 2 at the output waveguide 2 d at the other end 1 b in the longitudinal direction of the substrate 1.

  The traveling wave electrode 6 is for applying a high-frequency electric signal that modulates the phase of light propagating through the optical waveguide 2, and is formed on both sides of the central wiring 3 (central conductor layer) and the central wiring 3. Side wirings 4 and 5 (side conductor layers).

The central wiring 3 has a longitudinally extending portion 3a that extends in the longitudinal direction of the substrate 1 and a laterally extending portion 3b that extends in the lateral direction of the substrate 1 from one end 3c of the longitudinally extending portion 3a. It is formed in a substantially L shape in plan view.
The other end of the longitudinally extending portion 3a is referred to as a terminal end 3d.

The side wiring 4 includes a longitudinally extending portion 4a that extends in the longitudinal direction of the substrate 1 and a laterally extending portion 4b that extends in the lateral direction of the substrate 1 from one end 4c of the longitudinally extending portion 4a. It has a substantially L shape in plan view.
The longitudinally extending portion 4 a is formed along the side edge 1 d at a position close to the side edge 1 d of the substrate 1. The longitudinally extending portion 4 a is formed over almost the entire length of the substrate 1.
The other end of the longitudinally extending portion 4a is referred to as a terminal end 4d. The terminal end 4d is located close to the edge 1g of the substrate 1.

The short extending portion 4 b is formed along the edge 1 f at a position close to the edge 1 f of the substrate 1. The short extending portion 4 b is formed over almost the entire width of the substrate 1.
The extended end of the short extension portion 4b is referred to as a base end 4s. The base end 4s is in a position close to the side edge 1e. The side wiring 4 is formed at a substantially constant interval from the central wiring 3.

The side wiring 5 is formed along the side edge 1 e at a position close to the side edge 1 e which is the other long side of the substrate 1.
The side wiring 5 is formed at a substantially constant interval from the central wiring 3.

The end portion (base end 4s) of the short extension portion 4b of the side wiring 4 and the end portion (base end 5s) of the side wiring 5 are each electrically grounded.
An end portion (base end 3 s) of the short extending portion 3 b of the central wiring 3 is connected to a connector 8 provided on the housing 40 via a wiring 7. The connector 8 is connected to a driver 50 that is an external circuit separately provided outside the housing 40.

  The driver 50 includes, for example, a signal source 51 that generates an electric signal, and a capacitor 52 that cuts a DC (direct current) component from the electric signal output from the signal source 51.

The electrical termination unit 30 includes a termination unit substrate 11 and a termination circuit 12 mounted on the termination unit substrate 11.
The termination circuit 12 includes a termination resistor 13 electrically connected to the termination 3d of the central wiring 3, and high-frequency capacitors 14 and 15 electrically connected to the terminations 4d and 5d of the side wirings 4 and 5, respectively. A bias terminal 16, a bias resistor 17, and a low frequency capacitor 19 provided in the housing 40 are provided.
The bias resistor 17 is provided between the termination resistor 13 and the high frequency capacitors 14 and 15 and the bias terminal 16.
The low frequency capacitor 19 is disposed between the termination resistor 13 and the high frequency capacitors 14 and 15 and the grounding portion 18.

  Termination resistor 13 and high frequency capacitors 14 and 15 are electrically connected to terminations 3d, 4d, and 5d of wirings 3, 4, and 5, respectively, by wires 22, 23, and 24 formed by, for example, wire bonding or the like. .

The terminal end substrate 11 may be formed of a hard material such as ceramic, or may be a so-called FPC (Flexible printed circuits) made of a flexible film material made mainly of polyimide or the like.
The terminal end substrate 11 has a rectangular shape in plan view, and is arranged with its longitudinal direction directed toward the short side of the substrate 1 of the optical modulator 20.

As shown in FIG. 1A and FIG. 1B, the termination substrate 11 of the electrical termination unit 30 is located near the terminations 3d, 4d, 5d of the wirings 3, 4, 5 of the optical modulator 20. It is provided above.
For this reason, a part of the electrical terminal portion 30 is provided at a position overlapping the optical modulator 20 in plan view. In the illustrated example, the region including the center in the longitudinal direction of the termination substrate 11 is disposed at a position overlapping the substrate 1 of the optical modulator 20.
The termination substrate 11 is preferably installed in parallel with the substrate 1 (see FIG. 1B).

As shown in FIG. 1B, the electrical termination 30 can be stably installed by fixing the electrical termination 30 to the optical modulator 20 via a fixing means such as a bump 60 or the like. .
The bump 60 is made of metal, resin, or the like, and for example, a solder bump can be used.
The bump made of metal can be used as means for electrically connecting the terminal resistor 13 and the high frequency capacitors 14 and 15 to the wirings 3, 4 and 5.

  The fixing means for fixing the electrical terminal portion 30 on the optical modulator 20 is not limited to the bump 60, and an adhesive, a fitting pin, a screw member, or the like can be employed.

  The end portion substrate 11 can also be mechanically fixed to the housing 40 (for example, the bottom plate 41) by fixing means such as a resin layer, bumps made of metal, resin, or the like, an adhesive, a fitting pin, or a screw member. Thereby, the electrical terminal part 30 can be fixed more firmly and vibration resistance can be improved.

In the optical modulator module 10, the space occupied by the optical modulator 20 and the electrical termination unit 30 in the housing 40 can be reduced by disposing a part of the electrical termination unit 30 on the optical modulator 20. .
For this reason, the size of the optical modulator module 10 can be reduced by downsizing the housing 40.
In particular, when the substrate 1 of the optical modulator 20 is formed of a semiconductor material made of silicon, the effect of downsizing becomes more remarkable because the substrate 1 is small.

  Since the electrical termination unit 30 is provided on the optical modulator 20, the electrical termination unit 30 does not interfere with the optical fibers 100 and 101 connected to the optical waveguide 2, and the optical wiring is affected. Absent.

In the optical modulator module 10, since the electrical termination 30 is provided on the optical modulator 20, the termination of the traveling wave electrode 6 (the portion including the terminations 3 d, 4 d, 5 d of the wirings 3, 4, 5) is provided. A straight shape can be obtained. Thereby, the high frequency characteristic in the traveling wave electrode 6 improves.
On the other hand, in the example shown in FIG. 4, since the electrical termination unit 130 is installed on the side of the optical modulator 120 in order to avoid interference with the output-side optical fiber 101, the termination of the wirings 103 to 105 is performed. It is necessary to bend the end portions of the wirings 103 to 105 so as to reach the vicinity of the side edge 1e, which is not advantageous in terms of high frequency characteristics.

  The optical modulator module 10 can bring the traveling wave electrode 6 and the electrical termination 30 closer by providing the electrical termination 30 on the optical modulator 20 and improve the frequency characteristics in the high frequency range. Can do.

(Second Embodiment)
Next, a second embodiment of the optical modulator module according to the present invention will be described. In the following description, the same reference numerals are given to the same components as those in the first embodiment, and the description thereof is omitted.
The second embodiment is different from the first embodiment in that the connection structure between the electrical termination unit 30 and the optical modulator 20 is different.

FIG. 2 is a diagram illustrating a configuration of an optical modulator module 10A according to the second embodiment. 2A is a plan sectional view of the optical modulator module 10A, and FIG. 2B is a side sectional view of the optical modulator module 10A.
As shown in FIG. 2A, the optical modulator module 10A includes an optical modulator 20 that modulates the phase of light by applying a high-frequency electrical signal, an electrical termination unit 30A that terminates the high-frequency electrical signal, And a housing 40 for housing the optical modulator 20 and the electrical terminal end 30A.

The termination substrate 21 of the electrical termination unit 30 </ b> A is disposed on the optical modulator 20.
For this reason, at least a part of the electrical terminal portion 30A is provided at a position overlapping the optical modulator 20 in plan view.
A through-hole electrode 70 penetrating both sides of the termination substrate 21 is electrically connected to the termination resistor 13 and the high-frequency capacitors 14 and 15.

In the termination portion substrate 21, the through electrode 70 is mechanically bonded to the substrate 1 of the optical modulator 20 by the connecting means 71 on the lower surface 21 a facing the optical modulator 20.
The connection means 71 is a metal bump (such as a solder bump) or die bonding.
The termination resistor 13 and the high frequency capacitors 14 and 15 mounted on the termination substrate 21 are connected to the termination 3d, 4d, and the terminations 3d and 4d of the central wiring 3 and the side wirings 4 and 5 through the through electrode 70 and the connecting means 71, respectively. 5d is electrically connected.

In the optical modulator module 10A, by providing the electrical termination 30A on the optical modulator 20, the optical modulator 20 and the electrical termination 30A occupy the housing 40 as in the first embodiment. Space can be reduced.
For this reason, the housing | casing 40 can be reduced in size and the optical modulator module 10 can be reduced in size.

The termination circuit 12 of the electrical termination portion 30A is electrically connected to the traveling wave electrode 6 via connection means 71 made of a conductive material.
According to this structure, since connection by wire bonding or the like is not required, the optical modulator 20 and the electrical terminal portion 30A can be easily and reliably electrically connected. Since the connection means 71 can function as a means for mechanically fixing the electrical terminal end 30A to the optical modulator 20, no other fixing means is required.

(Third embodiment)
FIG. 3 is a side sectional view showing a configuration of an optical modulator module 10B according to the third embodiment.
In the optical modulator module 10B, the electrical terminal end 30A is fixed to the optical modulator 20 via an adhesive layer 61 (fixing means) made of an adhesive made of resin or the like.
The adhesive layer 61 is formed between the lower surface 21 a of the substrate 21 and the main surface 1 c of the substrate 1.
The other configuration of the optical modulator module 10B may be the same as that of the second embodiment shown in FIG.

(Other embodiments)
The present invention is not limited to the above-described embodiments described with reference to the drawings, and various modifications are conceivable within the technical scope thereof.
The electrical terminations 30 and 30A may be provided not only in a part but in a position where the electrical terminations 30 and 30A entirely overlap the optical modulator 20.
Further, the electrical terminal portions 30 and 30 </ b> A may be separated from the optical modulator 20.

In the example of FIGS. 1 and 2, the electrical terminal portions 30 and 30A are arranged so that the longitudinal direction is orthogonal to the longitudinal direction of the optical modulator 20, but the electrical terminal portions 30 and 30A are longitudinal. The direction may be arranged toward the longitudinal direction of the optical modulator 20.
Further, the central wiring 3 and the side wiring 4 are formed by bending portions including the terminations 3d, 4d, and 5d in the short direction of the substrate 1, similarly to the electrical termination 130 shown in FIG. It is good also as a shape where the short extension part was formed in the both ends of the extension part, respectively.
In addition, the termination circuit 12 of the electrical termination unit 30 may have any configuration as long as it can perform a required electrical function.

  In the illustrated example, the optical modulator 20 includes a substrate 1, an optical waveguide 2, and a traveling wave electrode 6. However, the optical waveguide and the traveling wave electrode (conductor layer) are provided on a casing (for example, a bottom plate). It may be formed. In this case, part or all of the bottom plate functions as an optical modulator substrate. For this reason, at least a portion of the electrical termination portion overlaps the optical modulator means that at least a portion of the electrical termination portion overlaps the optical waveguide or the traveling wave electrode.

  The present invention makes it possible to reduce the size of an optical modulator module.

DESCRIPTION OF SYMBOLS 10, 10A ... Optical modulator module, 20 ... Optical modulator, 1 ... Optical modulator board | substrate, 2 ... Optical waveguide, 3 ... Center wiring (conductive layer), 4,5. ..Side wiring (conductive layer), 6 ... traveling wave electrode (conductor layer), 30, 30A ... electrical termination, 11, 21 ... termination substrate, 12 ... termination circuit, 40 ... Case, 60 ... Bump (fixing means), 61 ... 70 ... Penetration electrode, 71 ... Connection means (bump).

Claims (5)

An optical modulator;
An electrical termination connected to the optical modulator;
A housing that houses the optical modulator and the electrical termination,
The optical modulator has an optical waveguide provided on an optical modulator substrate, and a conductor layer to which a high-frequency electric signal that modulates the phase of light propagating through the optical waveguide is input,
The electrical termination includes a termination substrate and a termination circuit formed on the termination substrate and terminating the high-frequency electrical signal through the conductor layer,
An optical modulator module, wherein at least a part of the electrical terminal portion is provided at a position overlapping the optical modulator in plan view.   The optical modulator module according to claim 1, wherein the electrical terminal is fixed to the optical modulator via a fixing unit.   The optical modulator module according to claim 2, wherein the fixing means is a bump or an adhesive layer.   3. The light modulation according to claim 1, wherein the termination circuit of the electrical termination unit is electrically connected to the conductor layer via a through electrode formed in the termination unit substrate. Module.   The optical modulator module according to claim 1, wherein the electrical terminal portion is fixed to the housing.

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