KR102320441B1 - Optical intensity modulator and optical module using the same - Google Patents

Abstract

The present invention relates to an optical modulator and an optical module using the same, comprising: a substrate, a lower clad formed on the substrate, a first optical waveguide formed on the lower clad, a second optical waveguide, a first conductive line; a second conductive line, and an upper clad formed to surround the first and second optical waveguides formed on the lower clad, wherein electric energy of different polarities is applied to each of the first and second conductive lines In this case, the phase of the light passing through the first optical waveguide and the phase of the light passing through the second optical waveguide are configured to change opposite to each other.

Description

Optical modulator and optical module using the same

The present invention relates to an optical modulator used for optical communication and an optical module using the same.

The optical modulator is an element that controls the phase or intensity of a light wave propagating along an optical waveguide with an external signal.

The light modulator utilizes an electro-optical effect or a thermo-optical effect of a medium forming an optical waveguide.

Representative electro-optical materials include semiconductors (GaAs, InP), ferroelectrics (LiNbO3, LiTaO3), and polarized polymers. When an electric field is applied to these materials in a certain direction, the refractive index in the electric field direction or a direction perpendicular thereto is changed. Since a change in refractive index means a phase change of a light wave propagating in a medium, a phase modulator and an intensity modulator can be implemented using this change.

Such an optical modulator is used in the field of optical communication, and as optical communication becomes high-speed, the optical modulator must also operate at a high speed. have.

An embodiment of the present invention is to provide an optical modulator in which a voltage level for generating an electric field is lowered and an optical module using the same.

An embodiment of the present invention is to provide an optical modulator suitable for high-speed optical communication and an optical module using the same.

An embodiment of the present invention is to provide an optical modulator having a small size and an optical module using the same.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

An optical modulator according to an embodiment of the present invention includes a substrate, a lower clad formed on the substrate, a first optical waveguide, a second optical waveguide, a first conductive line, and a second conductive line formed on the lower clad and an upper clad formed to surround the first and second optical waveguides formed on the lower clad, wherein when electric energy of different polarity is applied to each of the first and second conductive lines, the first It is characterized in that the phase of light passing through the optical waveguide and the phase of light passing through the second optical waveguide are changed to be opposite to each other.

An optical module according to an embodiment of the present invention includes a substrate, a light source structure disposed on the substrate and configured to emit light, and a third disposed on the substrate and through which the light emitted from the light source structure passes. and an optical modulator including a first optical waveguide and a second optical waveguide, wherein when electric energy is supplied to the optical modulator, a phase of light passing through the first optical waveguide and a phase of light passing through the second optical waveguide are opposite to each other When the electric energy of a predetermined voltage level is supplied to the optical modulator, the light passing through the first optical waveguide and the light passing through the second optical waveguide are destructively interfered to prevent light emission of the optical modulator It is characterized by blocking.

This technology can be suitable for high-speed optical communication because high-speed operation is possible by lowering the voltage level for generating an electric field.

In addition, since the present technology can be implemented in a small size, power consumption is low, and it can be produced in a relatively simple process, thereby reducing cost.

In addition, various effects directly or indirectly identified through this document may be provided.

1 is a view showing a side view of an optical module to which an optical modulator according to an embodiment of the present invention is applied.
2 is a diagram illustrating a plan view of an optical module to which an optical modulator according to an embodiment of the present invention is applied.
3 is a cross-sectional view of an optical modulator according to an embodiment of the present invention.
4 is a cross-sectional view for explaining a manufacturing process of an optical modulator according to an embodiment of the present invention.
5 is a diagram for explaining an operation of an optical modulator according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated on different drawings. In addition, in describing the embodiment of the present invention, if it is determined that a detailed description of a related known configuration or function interferes with the understanding of the embodiment of the present invention, the detailed description thereof will be omitted.

In describing the components of the embodiment of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the components from other components, and the essence, order, or order of the components are not limited by the terms. In addition, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 5 .

1 is a view showing a side view of an optical module to which an optical modulator according to an embodiment of the present invention is applied.

Referring to FIG. 1 , an optical module to which a light modulator according to an embodiment of the present invention is applied may include a substrate 100 , a light source structure 200 , and a light modulator 300 .

The substrate 100 may be formed based on silicon or silica, and the light source structure 200 and the light modulator 300 may be disposed on the substrate 100 . At this time, the substrate 100 and the light source structure 200 may be electrically connected and shouldered to be physically fixed. Also, a silver adhesive may be used to electrically connect and physically fix the substrate 100 and the light modulator 300 .

The light source structure 200 may emit light to the light modulator 300 .

Light emitted from the light source structure 200 may include a laser, and the light source structure 200 may include a laser diode emitting a laser.

The light modulator 300 may include an optical waveguide 310 , and may be configured to output light emitted from the light source structure 200 through the optical waveguide. In this case, the light modulator 300 may change the phase or intensity of the light output from the light modulator 300 by generating an electric field to change the phase of the light incident through the optical waveguide.

The optical modulator 300 may divide a lower portion of the optical waveguide 310 into a lower clad and an upper portion of the optical waveguide 310 into an upper clad with respect to the optical waveguide 310 . In this case, the optical waveguide 310 may be referred to as a core.

The light modulator 300 according to the embodiment of the present invention may be formed of a material having a larger difference in electro-optical coefficients between the core and the cladding (including upper and lower parts).

For example, the core material of the optical modulator 300 may include lithium naobate (LiNbO3), which is a ferroelectric, and the material of the upper and lower clads of the optical modulator 300 may include silica (SiO2). At this time, the electro-optical coefficient of lithium naobate (LiNbO3) is about 2.2, the electro-optical coefficient of silica (SiO2) is about 1.45, and lithium naobate (LiNbO3), which is the core material of the optical modulator 300, and silica ( Silica), the difference in electro-optic coefficient is about 0.67, which is much larger than the difference in electro-optic coefficient between the core and the clad of the conventional optical modulator (about 0.0001).

Therefore, when an electric field is generated in the light modulator 300 according to the embodiment of the present invention, the phase of the incident light can be changed to a greater width than that of the conventional light modulator.

In addition, since the light module using the light modulator 300 according to the embodiment of the present invention can arrange the light source structure 200 and the light modulator 300 on one substrate 100 , the light source structure 200 and The distance between the light modulators 300 may be kept constant. Accordingly, the optical module according to the embodiment of the present invention capable of maintaining a constant distance between the light source structure 200 and the light modulator 300 may reduce optical coupling loss.

2 is a diagram illustrating a plan view of an optical module to which an optical modulator according to an embodiment of the present invention is applied.

Referring to FIG. 2 , in the optical module to which the optical modulator according to an embodiment of the present invention is applied, a light source structure 200 and a light modulator 300 may be disposed on a substrate 100 .

The optical modulator 300 may include an optical waveguide 310 , a first conductive line 321 , and a second conductive line 322 . In this case, the optical waveguide 310 , the first conductive line 321 , and the second conductive line 322 may be formed inside the optical modulator 300 .

The optical modulator 300 may be configured such that an optical waveguide 310 is formed therein, and a first conductive line 321 and a second conductive line 322 are disposed on both sides of the optical waveguide 310 .

For example, the optical waveguide 310 inside the light modulator 300 includes one input terminal IN to which the light emitted from the light source structure 200 is incident and one output terminal OUT to output the incident light to the outside. can be composed of In this case, the optical waveguide 310 may be configured such that the light incident to the input terminal IN is distributed to the two waveguides 310A and 310B and then merged into one output terminal OUT.

The first conductive line 321 and the second conductive line 322 may be disposed to generate an electric field in the two waveguides 310A and 310B.

For example, the first and second conductive lines 321 and 322 may be disposed to generate electric fields in different directions in each of the two waveguides 310A and 310B.

The first conductive line 321 may be formed on outer surfaces of the waveguides 310A and 310B.

For example, the first conductive line 321 may be formed on an outer surface of each of the two waveguides 310A and 310 to be parallel to each of the waveguides 310A and 310B.

More specifically, the first conductive line 321 is formed to provide electrical energy by connecting the conductive lines 321A and 321B and the conductive lines 321A and 321B formed to be parallel to the respective waveguides 310A and 310B. It may include a conductive line 321C.

As shown in FIG. 2 , the first conductive line 321 may be formed in a U-shape.

The second conductive line 322 may be formed between inner surfaces of the two waveguides 310A and 310B.

For example, the second conductive line 322 may be formed between inner surfaces of the two waveguides 310A and 310B to be parallel to the waveguides 310A and 310B.

In more detail, the second conductive line 322 provides electrical energy to the conductive line 322A and the conductive line 322A formed to be parallel to the waveguides 310A and 310B between the inner surfaces of the waveguides 310A and 310B. It may include a conductive line 322B formed for the purpose.

As shown in FIG. 2 , the second conductive line 322 may be formed in an inverted L-shape.

3 is a cross-sectional view of an optical modulator according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of the optical modulator 300 shown in FIG. 2 taken along the A-B direction.

Referring to FIG. 3 , the light modulator 300 may be disposed on the substrate 100 .

The optical modulator 300 may include an optical waveguide 310 , a first conductive line 321 , a second conductive line 322 , a lower clad 331 , and an upper clad 332 .

The lower clad 331 may be disposed on the substrate 100 .

The optical waveguide 310 , the first conductive line 321 , and the second conductive line 322 may be formed on the lower clad 331 .

The upper clad 332 may be formed to surround the optical waveguide 310 , the first conductive line 321 , and the second conductive line 322 formed on the lower clad 331 .

At this time, if the arrangement of the optical waveguide 310 and the first and second conductive lines 321 and 322 will be described in more detail, the waveguide 310A is disposed between the first conductive line 321A and the second conductive line 322A. The waveguide 310B may be formed between the second conductive line 322A and the first conductive line 321B.

4 is a cross-sectional view for explaining a manufacturing process of an optical modulator according to an embodiment of the present invention.

4 is a view for explaining the formation of the optical waveguide 310 between the first and second conductive lines 321 and 322 during the manufacturing process of the optical modulator according to an embodiment of the present invention.

First, referring to FIG. 4A , a lower clad 331 made of silica (SiO2) is formed on a substrate 100 formed of a silicon (Si) material, and lithium is released on the lower clad 331. A bait (LiNbO3) layer is formed.

Referring to FIG. 4B , a photoresist (PR) is disposed on the lithium naobate (LiNbO 3 ) layer through photo-lithography. In this case, the width of the disposed photoresist PR may be the thickness of the optical waveguides 310 and LN.

Referring to FIG. 4C , an etching process may be performed to remove the remaining lithium naobate (LiNbO3) layers except for the lithium naobate (LiNbO3) layer on which the photoresist PR is disposed.

Referring to FIG. 4D , after the etching process of FIG. 4C , a photoresist PR may be disposed on the lower clad 331 made of silica (SiO2) through photo-lithography. can In this case, an upper portion of the lower clad 331 and SiO2 may be divided into a region where the photoresist PR is disposed and a region where the photoresist PR is not disposed.

Referring to FIG. 4E , a conductor (eg, gold) may be deposited on the lower cladding 331 and SiO2 on which the photoresist PR is not disposed through a deposition process.

Referring to FIG. 4F , after the deposition process, a process (Lift-off) of removing the photoresist PR disposed in FIG. 4D may be performed.

Referring to FIG. 4G , the upper cladding 332 may be formed by depositing silica (SiO2) in the region where the photoresist PR removed in FIG. 4F is disposed.

Through this process, the lower clad 331 is disposed on the substrate 100 , first and second conductive lines 321 and 322 are formed on the lower clad 331 , and first and second conductive lines are formed on the lower clad 331 . An optical waveguide 310 (LN) may be formed between the lines 321 and 322 .

5 is a diagram for explaining an operation of an optical modulator according to an embodiment of the present invention.

Before describing FIG. 5 , the operation of the optical module to which the optical modulator according to an embodiment of the present invention is applied will be summarized with reference to FIG. 2 .

The light emitted from the light source structure 200 may be incident to the input terminal of the light modulator 300 and may be emitted to the output terminal OUT through the optical waveguide 310 . In this case, by generating an electric field in the optical waveguide 310 , the phase of light passing through the optical waveguide 310 may be varied.

The light modulator 300 according to an embodiment of the present invention can block light output to the output terminal OUT when electric energy for generating an electric field is applied, and when not generating an electric field, that is, electric energy is not applied. In this case, the light incident from the input terminal IN may be emitted to the output terminal OUT through the optical waveguide 310 .

Referring to FIG. 5 , it will be described in more detail as follows.

The first conductive line 321 and the second conductive line 322 when the light modulator 300 according to an embodiment of the present invention blocks the light incident to the input terminal IN so that the light is not emitted to the output terminal OUT. Electrical energy of different polarity is applied to the

For example, as shown in FIG. 5A , positive (+) electrical energy is applied to the first conductive line 321 and negative (-) electrical energy is applied to the second conductive line 322 .

When positive electrical energy is applied to the first conductive line 321 and negative electrical energy is applied to the second conductive line 322 , the waveguide 310A and the waveguide 310B have opposite directions as shown in FIG. 5 , respectively. An electric field of Accordingly, a phase of light passing through the waveguide 310A and a phase of light passing through the waveguide 310B are opposite to each other.

At this time, if the phase of the light passing through the waveguide 310A and the phase of the light passing through the waveguide 310B are out of phase, the light passing through the two waveguides 310A and 310B is destructively interfered and the light is output to the output terminal OUT. doesn't happen

The optical modulator 300 according to the embodiment of the present invention is configured to generate electric fields in different directions in the two waveguides 310A and 310B, so that the phases of light passing through each of the waveguides 310A and 310B change in opposite directions. , the phase of the light passing through the two waveguides 310A and 310B may be configured to have an opposite phase even in low voltage level electrical energy.

Also, referring to FIG. 5B , in the optical modulator 300 according to the embodiment of the present invention, waveguides 310A and 310B and conductive lines 321 and 322 are formed in a line on the lower clad 331 . and the waveguides 310A and 310B are formed between the conductive lines 321 and 322 , so that an electric field can be generated in the waveguides 310A and 310B even with low voltage level electrical energy.

In addition, the optical modulator 300 according to the embodiment of the present invention is formed of a material having a large difference in electro-optical coefficients between the optical waveguide 310 and the cladding surrounding the optical waveguide 310 (including the upper and lower clads) to generate an electric field. In this case, the phase of the incident light can be changed to a larger width than that of the conventional light modulator. For example, in the embodiment of the present invention, lithium niobate (LiNbO3) is used as the material of the optical waveguide 310, and silica (silica, SiO2) can be used as the material of the upper and lower clads 331 and 332. have.

As a result, the light modulator 300 according to the embodiment of the present invention can block or output the light emitted from the light source structure 200 by using electric energy of a low voltage level, so that the light modulator 300 according to the present invention can be output. ) can not only reduce the size and power consumption, but also repeat the output and blocking of light at high speed. Therefore, the optical module using the optical modulator 300 according to the present invention can reduce power consumption, can be implemented with a small size, and can be suitable for high-speed communication.

The above description is merely illustrative of the technical spirit of the present invention, and various modifications and variations will be possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains.

Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

Claims (10)

Board;
a lower clad formed on the substrate;
a first optical waveguide, a second optical waveguide, a first conductive line, and a second conductive line formed on the lower clad; and
and an upper clad formed to surround the first and second optical waveguides formed on the lower clad,
The first and second optical waveguides,
They are arranged parallel to each other and are connected by one input terminal and one output terminal,
The first conductive line is
disposed on an outer surface of each of the first and second optical waveguides;
The second conductive line is
and applying electrical energy of different polarities to the first and second conductive lines so that a phase of light passing through the first optical waveguide and a phase of light passing through the second optical waveguide are out of phase with each other modulator. The method according to claim 1,
The first and second conductive lines are
and receiving electrical energy having different polarities so that a phase of light passing through the first optical waveguide and a phase of light passing through the second optical waveguide are out of phase with each other. The method according to claim 1,
The material of each of the upper clad and the lower clad,
containing silica;
Materials of the first and second optical waveguides are
Light modulator comprising lithium naobate. The method according to claim 1,
The first and second optical waveguides,
An optical modulator, which is disposed parallel to each other and is connected to one input terminal and one output terminal. 5. The method according to claim 4,
The first conductive line is
the first and second optical waveguides are disposed on an outer surface of each
The second conductive line is
An optical modulator disposed between the first and second optical waveguides. Board;
a light source structure disposed on the substrate and configured to emit light; and
and a light modulator disposed on the substrate and including a first optical waveguide and a second optical waveguide through which the light emitted from the light source structure passes;
The first and second optical waveguides,
Commonly connected to one input terminal and one output terminal, arranged parallel to each other,
a first conductive line is disposed on an outer surface of each of the first and second optical waveguides;
a second conductive line is disposed between the first and second optical waveguides;
When electric energy of different polarity is supplied to each of the first and second conductive lines, the phase of the light passing through the first optical waveguide and the phase of the light passing through the second optical waveguide are out of phase with each other and mutually interfered An optical module, characterized in that the light emission of the light modulator is blocked. 7. The method of claim 6,
The first and second optical waveguides,
Commonly connected to one input terminal and one output terminal, arranged parallel to each other,
A first conductive line is disposed on an outer surface of each of the first and second optical waveguides, and a second conductive line is disposed between the first and second optical waveguides. 7. The method of claim 6,
The first and second conductive lines are
The optical module, characterized in that the electrical energy of different polarity is applied. 7. The method of claim 6,
The light modulator is
a clad made of silica, and
An optical module comprising the first and second optical waveguides made of lithium naobate. 10. The method of claim 9,
The clad is
An optical module formed to surround the first and second optical waveguides.

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