JP2000249995A - Waveguide type optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waveguide type optical device usable for a wide band of 40 GHz or above by shifting a minimum frequency that a loss dip occurs to a frequency region of 40 GHz or above in the waveguide type optical device. SOLUTION: The waveguide type optical device is provided with a substrate 1 containing material having an electrooptical effect, an optical waveguide 3 formed on the substrate 1, a traveling wave type signal electrode 2 provided on the substrate for controlling a light wave propagating through the optical waveguide 3 and a pair of ground electrodes 4, 5 provided on both sides of the signal electrode 2. The thickness of the substrate 1 is 0.4 mm or above, and the length becoming the longest of a section perpendicular to the optical waveguide of the substrate 1 is made so as to become 1.8 mm or above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide type optical device which can be used in a wide band of 40 GHz or more.

[0002]

2. Description of the Related Art At present, the communication capacity is dramatically increasing, and in the analog domain, the carrier frequency is increasing from a microwave band (several GHz) to a millimeter wave band (30 GHz or more). Therefore, there is a demand for a high-speed waveguide type optical device that can be used in a wide band of 40 GHz or more. As a waveguide type optical device, a ground electrode, a signal electrode and an optical waveguide are formed on a substrate made of a material having an electro-optical effect, a microwave signal voltage is applied to the signal electrode, and a light wave propagating through the optical waveguide is formed. Modulating optical devices are known. In such an optical device, at a specific frequency, so-called "loss dip"
There was a problem that the transmission characteristics deteriorated. The usable frequency band of such an optical device is limited to a frequency lower than a lowest frequency at which a loss dip occurs (hereinafter, referred to as a loss dip frequency).

A method of shifting the occurrence frequency of loss dip to a higher frequency side in a waveguide type optical device is disclosed in, for example, Japanese Patent No. 2669097.
According to this publication, in a waveguide-type optical device, a dielectric resonator is formed in a cross-sectional direction of a substrate at a connection portion between an external power supply and a traveling-wave signal electrode. Almost all of them escape to the substrate side, so that there is a problem that the light wave is not modulated. Then, the frequency fc of the loss dip is given by fc = co / (2Nmd), and a substantial modulation band (hereinafter, referred to as a substantial loss dip frequency) fo in consideration of the safety factor 0.7 is fo = 0.7fc (co is the speed of light in a vacuum, Nm is the effective refractive index of the microwave, and d is the length of the diagonal line in a rectangular substrate cross section). . An object of the present invention is to shift the loss dip frequency to a 10 GHz band. As a result, the product Nmd of the longest length d (usually the length of the diagonal line) of the substrate cross section perpendicular to the optical waveguide and the effective refractive index Nm of the microwave in this direction is larger than 0.8 mm,
It is alleged that the resonance peak frequency was successfully shifted to 10 GHz or more by making the distance smaller than 11 mm.

[0004]

However, the present inventor has
To provide an optical device that can be used in a wide band of substantially 40 GHz or more, Japanese Patent No. 266909 is disclosed.
It has been found that the technique disclosed in Japanese Patent Application Publication No. 7 cannot be used. That is, in the invention described in this publication, it is necessary to reduce the length of the diagonal line of the cross section of the substrate in order to shift the frequency at which the loss dip occurs to the higher frequency side. On this occasion,
For example, a single crystal of lithium niobate is used as the material of the substrate, and the thickness of the substrate is 0.4 mm. The effective refractive index Nm of the microwave is 5.36 in the Z-axis direction (the thickness direction of the cross section of the substrate), and is 6.59 in the X and Y-axis directions. When these data are assumed and the loss dip frequency is calculated from the above equation, the result is as shown in a graph A in FIG.

For example, assuming that the thickness of the substrate is 0.5 mm, a substantial loss dip frequency is 10 GHz.
In the case of, d is 1.7 mm, and in the case of 20 GHz, d is 0.3 mm.
In the case of 9 mm and 30 GHz, d becomes 0.6 mm, and d
= 0.5 mm, since the substantial loss dip frequency is 39 GHz, the substantial loss dip frequency does not become 40 GHz. Further, when a trial calculation is performed with the thickness of the substrate being 0.4 mm, when the substantial loss dip frequency is 10 GHz, d is 1.7 mm and 20 G
In the case of Hz, d is 0.8 mm, and in the case of 30 GHz, d is 0.6 mm. In the case of 40 GHz, d is 0.5 mm
However, the dimension in the width direction at that time is 0.2 mm,
Not realistic. As can be seen from these results, in order to shift the substantial loss dip frequency to 40 GHz or more, it is necessary to further reduce the thickness and width of the substrate, that is, to reduce the width or thickness of the substrate to less than 0.4 mm. There is
In consideration of the strength of the substrate, workability, etc., it was found that this was not practical.

SUMMARY OF THE INVENTION An object of the present invention is to provide a waveguide type optical device by shifting the minimum frequency at which a loss dip occurs to a frequency region of 40 GHz or more.
An object of the present invention is to provide a waveguide type optical device which can be used substantially in a wide band of 0 GHz or more.

[0007]

SUMMARY OF THE INVENTION The present invention substantially comprises
A waveguide type optical device for use in a wide band of GHz or more, and a substrate including a material having an electro-optical effect,
An optical waveguide formed on the substrate, a traveling-wave signal electrode provided on the substrate for controlling a light wave propagating through the optical waveguide, and a pair of ground electrodes provided on both sides of the signal electrode And the thickness of the substrate is 0.4 mm
As described above, the longest length of the section of the substrate perpendicular to the optical waveguide is 1.8 mm or more.

[0008] In the course of research to shift the substantial loss dip frequency to a band of 40 GHz or higher,
A so-called symmetric ground electrode arrangement (where at least a pair of ground electrodes are provided on both sides of a traveling wave signal electrode) and the thickness of the substrate is 0.4 mm or more,
The length of the longest section of the substrate perpendicular to the optical waveguide is defined as 1.
It has been found that setting the thickness to 8 mm or more is effective, and the present invention has been achieved.

For example, in Japanese Patent No. 2669097,
For a high-speed optical waveguide device having a so-called asymmetrical ground electrode arrangement in which an installation electrode is provided on only one of the signal electrodes, an attempt has been made to shift the loss dip to the 10 GHz band. In an optical device having such an asymmetrical ground electrode arrangement, the influence of the substrate mode is dominant as a cause of the loss dip. That is, the microwave signal applied to the signal electrode is difficult to stably propagate at the connection between the coaxial line and the coplanar electrode, and a part of the signal is radiated to the substrate side. This radiation causes unwanted coupling of the microwave signal with the intrinsic light modulation to the substrate mode.

As a result, the microwave leaked from the signal electrode excites the substrate mode, causes a resonance phenomenon, and generates a loss dip. The loss dip frequency is determined by the substrate mode size governed by the substrate size. Therefore, by reducing the substrate size, the loss dip frequency also shifts to the higher frequency side.

On the other hand, in the waveguide type optical device having the symmetrical ground electrode arrangement of the present invention, the cause of the loss dip is little affected by the substrate mode. This is because, since the electrodes are symmetrically arranged, the microwaves output from the signal electrodes are almost applied to the ground electrodes arranged on the left and right of the signal electrodes. For this reason, the microwave signal applied to the signal electrode is easily propagated stably at the connection portion between the coaxial line and the coplanar electrode, and the radiation to the substrate side can be suppressed.

However, it has been found that microwaves leak into the substrate from the R portion formed before and after the working portion of the signal electrode, which is a major cause of loss dip. And
The adoption of the symmetrical ground electrode arrangement suppresses microwave leakage (radiation) from the signal electrode and increases the thickness of the substrate by 0.4 mm so that there is no problem in the strength and workability of the substrate. By setting the longest length of the section perpendicular to the optical waveguide of the substrate to 1.8 mm or more, the microwave radiated from the R portion into the substrate is dispersed,
We succeeded in suppressing the substrate mode coupling and shifting the loss dip frequency to a band of 40 GHz or more.

In the present invention, the substrate may be an integral body. The substrate includes a main body provided with an optical waveguide, a signal electrode, and a ground electrode, and a dummy substrate integrated with the main body. May be provided. In the latter case, the dimensions of the entire substrate can be changed by changing the dimensions of the dummy substrate.

As the material of the substrate, lithium niobate,
Electro-optical crystals such as lithium tantalate and lithium niobate-lithium tantalate solid solution are particularly preferred. As a method for forming the optical waveguide, an internal diffusion method such as a titanium diffusion method or a proton exchange method can be used. The waveguide type optical device of the present invention can be suitably used as an optical modulator, an optical phase modulator, a polarization scrambler, an optical switching element, an optical logic element for an optical computer, and the like.

The dummy substrate must be made of an insulating material, and is particularly preferably made of a material having an electro-optic effect. The dummy substrate is made of an electro-optic crystal such as lithium niobate, lithium tantalate, or a lithium niobate-lithium tantalate solid solution. Is particularly preferred. The main body of the substrate and the dummy substrate may be different materials, but are particularly preferably the same material.

According to the present invention, 0.4 mm is provided over the entire length of the substrate.
It is not necessary to have a thickness of at least 1.8 mm and a length of the longest section perpendicular to the optical waveguide of at least 1.8 mm, but at least in the vicinity of the curved portion on the input side of the signal electrode on the substrate body. It is necessary to have a thickness of 4 mm or more and a longest length of a section perpendicular to the optical waveguide of 1.8 mm or more.

The dummy substrate may or may not be provided over the entire length of the substrate main body, but is preferably arranged at least in the vicinity of the curved portion on the input side of the signal electrode on the main body. Further, the dummy substrate can be bonded in the width direction of the substrate main body and / or can be bonded in the thickness direction of the substrate main body. Further, two or more dummy substrates can be connected to one substrate body.

The operating band of the waveguide type optical device is 50 GHz.
In order to make z or more, when the thickness of the substrate is 0.4 mm or more, it is preferable that the longest length of the cross section of the substrate perpendicular to the optical waveguide is 2.6 mm or more.

From an economic viewpoint, it is preferable that the thickness of the substrate is 5 mm or less, and the longest length of a cross section of the substrate perpendicular to the optical waveguide is 50 mm or less.

FIG. 2A is a plan view showing an example of the optical device according to the present invention, and FIG.
It is a b-IIb line sectional view. The optical device 11A is a so-called Mach-Zehnder type modulator. On the main surface of the substrate 1, for example, a titanium diffused optical waveguide 3 is formed.
The optical waveguide 3 includes an input section 3a, branch sections 3b and 3c, and an output section 3d. A pair of ground electrodes 4 and 5 and a signal electrode 2 sandwiched between the pair of ground electrodes are provided on the main surface of the substrate 1.
Are provided. An insulating region is provided between each of the ground electrodes 4 and 5 and the signal electrode 2. In an optical device, a ground electrode and a signal electrode having a so-called coplanar wave guide (CPW) form are used for the purpose of further improving the operation speed. The signal electrode 2 includes an input unit 2a,
It is composed of a modulation section 2b, an output section 2c, an R section 2d on the input side, and an R section 2e on the output side.

According to the present invention, the length d of the diagonal line of the section perpendicular to the optical waveguide of the substrate 1 is set to 1.8 mm or more, and the thickness t is set to 0.4 mm or more.

FIGS. 3 to 7 show optical devices according to other embodiments of the present invention. Description of the components already described in FIG. 2 will be omitted.

In the optical device 11B shown in FIGS. 3 (a) and 3 (b), the substrate 10 comprises a main body portion 10a and an extended portion 10b provided on the input side of the side. On the main body portion 10a, the optical waveguide 3, the ground electrodes 4, 5, the signal electrode 2
Is provided. The diagonal length d of the cross section perpendicular to the optical waveguide of the substrate 10 at the position of the R portion 2d on the input side of the signal electrode is W, which is the sum of the width W1 of the main body portion 10a and the width W2 of the extension portion 10b; It is determined by the thickness t of the substrate 10.

In the optical device 11C shown in FIGS. 4A, 4B, and 4C, the substrate 20 includes a main body portion 20a and an extension portion 20 provided on the input side on the back surface of the main body portion 20a.
b. An optical waveguide 3, ground electrodes 4, 5 and a signal electrode 2 are provided on the main body portion 20a. The diagonal length d of the cross section perpendicular to the optical waveguide of the substrate 10 at the position of the R portion 2d on the input side of the signal electrode is a thickness which is the sum of the thickness t1 of the main body portion 20a and the thickness t2 of the extension portion 20b. T
And the width W of the substrate 10.

In the optical device 11D shown in FIGS. 5A and 5B, the substrate 30 includes a main body 30a and a separate dummy substrate 30b joined to a side surface of the main body 30a. An optical waveguide 3, ground electrodes 4, 5 and a signal electrode 2 are provided on a main body 30a. Ground electrode 5 on dummy substrate 30b
Is provided. The length d of the diagonal line of the section perpendicular to the optical waveguide of the substrate 30 is the width W1 of the main body 30a and the length of the dummy substrate 3.
It is determined by W, which is the sum of the width W2 of Ob, and the thickness t of the substrate 30.

In the optical device 11E shown in FIGS. 6A and 6B, the substrate 40 comprises a main body 40a and a dummy substrate 40b joined to the input side of the side surface. Main body 40a
An optical waveguide 3, ground electrodes 4, 5 and a signal electrode 2 are provided thereon. The ground electrode 5 is provided on the dummy substrate 40b. The diagonal length d of the cross section perpendicular to the optical waveguide of the substrate 40 at the position of the R portion 2d on the input side of the signal electrode is:
It is determined by W, which is the sum of the width W1 of the main body 40a and the width W2 of the dummy substrate 40b, and the thickness t of the substrate 40.

In the optical device 11F shown in FIGS. 7A, 7B and 7C, the substrate 50 comprises a main body 50a and a main body 5a.
And a dummy substrate 50b provided on the input side on the back side of Oa. On the main body 50a, the optical waveguide 3, the ground electrode 4,
5, a signal electrode 2 is provided. The diagonal length d of the cross section perpendicular to the optical waveguide of the substrate 50 at the position of the R portion 2d on the input side of the signal electrode is a thickness that is the sum of the thickness t1 of the main body 50a and the thickness t2 of the dummy substrate 50b. t and the substrate 50
And the width W.

In the present invention, the substrate body and the dummy substrate may be integrated so as not to be separated from each other. At this time, the bonding surface between the substrate body and the dummy substrate is brought into close contact with each other so that the adhesive does not enter the bonding surface, and the periphery of the bonding surface can be fixed with a conductive adhesive. In this case, the bonding surfaces of the substrate main body and the dummy substrate are brought into close contact with each other, the substrate main body and the dummy substrate are mounted on the jig, and the screws of the jig are tightened to apply pressure to the bonding surface between the substrate main body and the dummy substrate. Then, a conductive adhesive is applied to the periphery of the joint surface and cured, so that the ground electrode on the substrate body and the ground electrode on the dummy substrate are electrically connected.

Further, an ultraviolet curing adhesive is provided between the bonding surfaces of the substrate main body and the dummy substrate, and the adhesive is cured, whereby the substrate main body and the dummy substrate can be bonded. Also in this case, a conductive adhesive is applied to the periphery of the joint surface between the substrate body and the dummy substrate, and the conductive adhesive is cured so that the ground electrode on the substrate body and the ground electrode on the dummy substrate are electrically connected.

[0030]

(Experiment A) Optical device 11 as shown in FIG.
A was manufactured. On a Z-cut lithium niobate wafer, titanium was patterned by a photolithography method, and titanium was diffused by a thermal diffusion method to form an optical waveguide 3. The condition at this time is that the thickness of titanium is 8
00 Å, the diffusion temperature was 1000 ° C., and the diffusion time was 20 hours. On the main surface of the substrate 1, Si
An insulating buffer layer of O2 was formed (thickness 0.5-2 μm).
m). Next, electrodes 2, 4, and 5 made of metal plating having a thickness of 15 to 30 μm were formed thereon. Next, the wafer was cut to produce optical devices 11A of various dimensions.
However, the length of the substrate 1 is 60 mm and the thickness is 0.4 m
m, and the length d of a diagonal line of a cross section perpendicular to the optical waveguide is:
The values were changed to 0.8, 1.0, 1.8, 2.0, and 2.6 mm, respectively.

Each optical device and the measuring instrument were connected by a high-frequency cable. A sweep signal whose frequency gradually changed was output from the measuring instrument, the transmission characteristics at each frequency of 0 to 80 GHz were measured, and the loss dip frequency was confirmed.
The result is shown in Table 1 and graph B in FIG. 1 (the vertical axis is Nmd).
Shown in FIG. 8 shows the relationship between the frequency and the optical transmission characteristics when the length d of the diagonal line of the cross section perpendicular to the optical waveguide of the substrate is 0.8 mm, and the frequency and the light when d is 1.8 mm. FIG. 9 shows the relationship with the transmission characteristics.

[0032]

[Table 1]

As described above, when the length d of the diagonal line of the section perpendicular to the optical waveguide of the substrate is 0.8 and 1.0 mm, the substantial loss dip frequency is 20 to 30 GHz.
Assuming that d is 1.8 mm, the substantial loss dip frequency increased to 41 GHz. This showed a completely different tendency from the calculated value (graph A) in the case of the optical device having the asymmetrical ground electrode structure.

(Experiment B) An optical device 11D shown in FIG. 5 was manufactured. First, the substrate body 30a and the dummy substrate 30b were separately manufactured. Both materials were Z-cut lithium niobate. An optical waveguide, a signal electrode, and a ground electrode were formed on the substrate body 30a in the same manner as in Experiment A.
The ground electrode 5 was also formed on the dummy substrate 30b. The width W1 of the substrate body 30a is 0.8 mm, and the thickness is 0.4 mm.
And the length was 60 mm. Width W of dummy substrate 30b
2 is set such that the diagonal length d of the cross section perpendicular to the optical waveguide of the substrate is 1.0 mm, 1.2 mm, 1.8 mm, the thickness is 0.4 mm, and the length is 60 mm And 1. A dummy substrate is bonded to a side surface of the substrate body, and a length d of a diagonal line of a cross section perpendicular to the optical waveguide of the substrate is 1.8 mm.
Each substrate of 0 mm and 2.6 mm was produced.

However, when bonding the substrate body and the dummy substrate, an ultraviolet-curing adhesive is interposed between the bonding surface of the substrate body and the bonding surface of the dummy substrate, and this is cured.
Next, a conductive adhesive 8 is applied on the ground electrode on the substrate body and the ground electrode on the dummy substrate on the joint surface 6 of both, and further over the entire circumference of the joint surface 6 between the substrate body and the dummy substrate. The conductive adhesive 8 was applied and cured. For each optical device, the loss dip frequency was measured in the same manner as in Experiment A, and the measurement results are shown in Table 2.

[0036]

[Table 2]

When the length d of the diagonal line of the section perpendicular to the optical waveguide of the substrate is 0.8 mm, the same as in Experiment A, but d
Is 1.8 mm or more, the substantial loss dip frequency is 41 GHz or more. Therefore, experiment A
It was found that the same effect as in the case where the length d of the diagonal line of the cross section perpendicular to the optical waveguide of the substrate was increased as in the above can also be obtained by bonding the dummy substrate.

[0038]

According to the present invention, in a waveguide type optical device, by shifting the minimum frequency at which a loss dip occurs to a frequency region of 40 GHz or more,
It is possible to provide a waveguide type optical device that can be substantially used in a wide band of 40 GHz or more.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a substantial loss dip frequency and Nmd of an optical device according to the present invention.

FIG. 2A is a plan view showing an optical device 11A according to an embodiment of the present invention, and FIG.
It is IIb line sectional drawing.

FIG. 3A is a plan view showing an optical device 11B according to an embodiment of the present invention, and FIG. 3B is a IIIb of FIG.
FIG. 3 is a sectional view taken along line −IIIb.

4A is a side view showing an optical device 11C according to an embodiment of the present invention, FIG. 4B is a plan view of the optical device 11C shown in FIG. 4A, and FIG. IVc-I
It is a Vc line sectional view.

FIG. 5A is a plan view showing an optical device 11D according to an embodiment of the present invention, and FIG. 5B is a view showing Vb-V of FIG.
It is a sectional view taken on line b.

FIG. 6A is a plan view showing an optical device 11E according to an embodiment of the present invention, and FIG. 6B is a plan view showing VIb− in FIG.
It is a VIb line sectional view.

7A is a side view showing an optical device 11F according to an embodiment of the present invention, FIG. 7B is a plan view of the optical device 11F of FIG. 7A, and FIG. VIIc-
It is a VIIc line sectional view.

FIG. 8 shows the measurement results of the frequency and the optical transmission characteristic when the diagonal length d of the cross section perpendicular to the optical waveguide of the substrate is 0.8 mm and the thickness is 0.4 mm in the optical device of FIG. 6 is a graph showing a loss dip frequency.

FIG. 9 shows a measurement result of the frequency and the optical transmission characteristic when the diagonal length d of the cross section perpendicular to the optical waveguide of the substrate is 1.8 mm and the thickness is 0.4 mm in the optical device of FIG. 6 is a graph showing a loss dip frequency.

[Explanation of symbols]

1, 10, 20, 30, 40, 50 Substrate 2 Signal electrode 2d R part on input side 3 Optical waveguide
4, 5 Ground electrode 6 Bonding surface 8 Conductive adhesive 10a, 20a Substrate main body 10b, 20b Substrate extension 11A,
11B, 11C, 11D, 11E, 11F Optical device 30a, 40a, 50a Substrate body 30
b, 40b, 50b Dummy substrate W Width of substrate
W1 The width of the main body portion or the main body of the substrate W2 The width d of the extended portion of the substrate or the dummy substrate d
Diagonal length of a cross section perpendicular to the optical waveguide of the substrate t
Substrate thickness t1 Body part or body thickness of substrate t2 Extension part of substrate or thickness of dummy substrate

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[Procedure amendment]

[Submission date] December 2, 1999 (1999.12.
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

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[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a waveguide type optical device which shifts the minimum frequency at which a loss dip occurs in a frequency region of 40 GHz or more, has good workability, and is economical. Is to provide a device.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

[0007]

SUMMARY OF THE INVENTION The present invention relates to a waveguide type optical device for use in a wide band of 40 GHz or more, comprising a substrate containing a material having an electro-optic effect, and a light guide formed on the substrate. A waveguide, a traveling-wave type signal electrode provided on the substrate for controlling a light wave propagating through the optical waveguide, and a pair of ground electrodes provided on both sides of the signal electrode. Has an input portion, an output portion, a modulation portion, an input side curved portion between the input portion and the modulation portion, and an output side curved portion between the output portion and the modulation portion, and the thickness of the substrate is 0. 4 mm or more and 5 mm or less, and the longest length of the section perpendicular to the optical waveguide of the substrate is 1.8 mm or more;
2.6 mm or less, and a substantial loss dip generation frequency due to microwave radiation from the input portion side curved portion and the output portion side curved portion is 40 GHz or more. Further, the present invention is a waveguide type optical device for use in a wide band of 40 GHz or more, comprising a substrate main body made of a material having an electro-optical effect, and a dummy substrate,
The side surface of the substrate main body and the side surface of the dummy substrate are joined, and the optical waveguide formed on the substrate main body and the traveling wave type provided on the substrate main body for controlling the light wave propagating through the optical waveguide. Signal electrode, a pair of ground electrodes provided on both sides of the signal electrode on the substrate body, and a ground electrode provided on the dummy substrate, wherein the signal electrode is an input section, an output section, and a modulation section. Section, an input-side curved section between the input section and the modulating section, and an output-side curved section between the output section and the modulating section, from the input section-side curved section and the output section-side curved section. A substantial loss dip generation frequency due to microwave radiation is at least 40 GHz.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008] In the course of research to shift the substantial loss dip frequency to a band of 40 GHz or higher,
A so-called symmetrical ground electrode arrangement (having at least a pair of ground electrodes on both sides of a traveling wave signal electrode) is adopted, and the thickness of the substrate is 0.4 mm or more and 5 m.
m or less, and the longest length of the section perpendicular to the optical waveguide of the substrate to be 1.8 mm or more and 2.6 mm or less is effective, and it is found that workability is good and economical. Reached the present invention.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

According to the present invention, 0.4 mm is provided over the entire length of the substrate.
mm or more and 5 mm or less in thickness and 1.8 mm or more and 2.6 or more
It is not necessary to provide the optical waveguide of not more than mm and the longest length of the cross section perpendicular to the optical waveguide, but at least in the vicinity of the curved portion on the input portion side of the signal electrode on the substrate body, a thickness of not less than 0.4 mm and not more than 5 mm It is necessary to have a length of 1.8 mm or more and 2.6 mm or less and a longest section perpendicular to the optical waveguide.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

The dummy substrate may or may not be provided over the entire length of the substrate main body, but is preferably arranged at least in the vicinity of the curved portion on the input side of the signal electrode on the main body. The dummy substrate is joined in the width direction of the substrate body.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction contents]

In the case where a dummy substrate is provided, in order to set the working band of the waveguide type optical device to 50 GHz or more, when the thickness of the substrate is set to 0.4 mm or more, the maximum cross section perpendicular to the optical waveguide of the substrate is obtained. It is preferable that the length of the elongation is 2.6 mm or more.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

When a dummy substrate is provided, the thickness of the substrate is preferably 5 mm or less from the viewpoint of economy, and the longest length of the section of the substrate perpendicular to the optical waveguide is 50 mm or less. Is preferred.

[Procedure amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

According to the present invention, the length d of the diagonal line of the section perpendicular to the optical waveguide of the substrate 1 is set to 1.8 mm or more and 2.6 mm or less, and the thickness t is set to 0.4 mm or more and 5 mm or less.

[Procedure amendment 10]

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[Correction target item name] 0038

[Correction method] Change

[Correction contents]

[0038]

According to the present invention, in a waveguide type optical device, the minimum frequency at which a loss dip occurs can be shifted to a frequency region of 40 GHz or more, and the waveguide is excellent in workability and economy. Type optical device can be provided. ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 29, 2000 (200.2.2
9)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

[0007]

SUMMARY OF THE INVENTION The present invention relates to a waveguide type optical device for use in a wide band of 40 GHz or more, comprising a substrate containing a material having an electro-optic effect, and a light guide formed on the substrate. A waveguide, a traveling-wave type signal electrode provided on the substrate for controlling a light wave propagating through the optical waveguide, and a pair of ground electrodes provided on both sides of the signal electrode. Has an input portion, an output portion, a modulation portion, an input side curved portion between the input portion and the modulation portion, and an output side curved portion between the output portion and the modulation portion, and the thickness of the substrate is 0. 4 mm or more and 5 mm or less, and the longest length of the section perpendicular to the optical waveguide of the substrate is 1.8 mm or more;
2.6 mm or less, and a substantial loss dip generation frequency due to microwave radiation from the input portion side curved portion and the output portion side curved portion is 40 GHz or more. Further, the present invention is a waveguide type optical device for use in a wide band of 40 GHz or more, comprising a substrate main body made of a material having an electro-optical effect, and a dummy substrate,
The side surface of the substrate main body and the side surface of the dummy substrate are joined, and the optical waveguide formed on the substrate main body and the traveling wave type provided on the substrate main body for controlling the light wave propagating through the optical waveguide. Signal electrode, a pair of ground electrodes provided on both sides of the signal electrode on the substrate body, and a ground electrode provided on the dummy substrate, wherein the signal electrode is an input section, an output section, and a modulation section. Part, an input part side curved part between the input part and the modulation part, and an output part side curved part between the output part and the modulation part, the thickness of the substrate is 0.4 mm or more, the substrate The longest length of the cross section perpendicular to the optical waveguide is 1.8.
mm or more, and a substantial loss dip generation frequency due to microwave radiation from the input portion side curved portion and the output portion side curved portion is 40 GHz or more.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction contents]

In the case where a dummy substrate is provided, the longest length of a section perpendicular to the optical waveguide of the substrate is set to 2.6 m in order to set the working band of the waveguide type optical device to 50 GHz or more.
m or more.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Tsutomu Saito 585 Tomimachi, Funabashi-shi, Chiba F-term in the New Technology Research Laboratories, Sumitomo Osaka Cement Co., Ltd. 2H079 AA02 AA12 BA01 BA02 BA03 CA05 CA08 DA03 DA21 DA22 EA05 EB04 HA05 HA14

Claims (5)

[Claims] 1. A waveguide type optical device for use in a wide band of 40 GHz or more, comprising: a substrate including a material having an electro-optic effect; an optical waveguide formed on the substrate; It has a traveling wave type signal electrode provided on the substrate to control the light wave, and a pair of ground electrodes provided on both sides of the signal electrode, and the thickness of the substrate is 0.4 mm or more. Yes,
The longest length of the section perpendicular to the optical waveguide of the substrate is 1.
A waveguide type optical device having a length of 8 mm or more. 2. The apparatus according to claim 1, wherein the substrate includes a main body provided with the optical waveguide, the signal electrode, and the ground electrode, and a dummy substrate integrated with the main body. Item 2. The waveguide type optical device according to Item 1. 3. The waveguide type optical device according to claim 2, wherein said dummy substrate is made of an insulating material. 4. The waveguide type optical device according to claim 3, wherein the insulating material is a material having an electro-optic effect. 5. The semiconductor device according to claim 2, wherein the dummy substrate is arranged at least in the vicinity of a curved portion on the input portion side of the signal electrode on the main body. The waveguide type optical device according to the above.