KR102268534B1 - Integrated waveguide for orbital angular momentum mode and manufacturing method thereof - Google Patents

Abstract

An integrated optical waveguide for an orbital angular momentum mode according to the present invention includes a clad portion and a core portion that has rotational symmetry with respect to the central axial direction and is surrounded by the clad portion, and waveguide modes having different phase differences pass through the core portion Then, it can be guided in a waveguide mode having orbital angular momentum.

Description

INTEGRATED WAVEGUIDE FOR ORBITAL ANGULAR MOMENTUM MODE AND MANUFACTURING METHOD THEREOF

The present invention relates to an integrated optical waveguide for orbital angular momentum mode and a method for manufacturing the same, and more particularly, to an integrated optical waveguide capable of providing a waveguide mode having an orbital angular momentum mode and a method for manufacturing the same.

In order to meet the ever-increasing data rate requirements, research on OAM mode, which can have an infinite number of vertical modes, is being actively conducted, unlike optical waveguides having a limited number of vertical modes.

In the OAM mode, each mode is classified by a phase change in the azimuth direction in a plane perpendicular to the traveling direction, which is divided by the quantum number l of the OAM mode. This first-order OAM mode is a new mode different from the existing mode using frequency or polarization, and a mode having a higher degree of freedom can be created by mixing two or more.

OAM mode generally has a rotating vortex shape, so it is easy to generate and propagate in a cylindrical optical waveguide such as an optical fiber, but it is difficult to apply to an optical integrated circuit using a rectangular optical waveguide. There are many difficulties with the spread.

Korean Patent Registration No. 10-0577929 (Registration Date: 2006. 05. 02.)

An object of the present invention is to provide an integrated optical waveguide for an orbital angular momentum mode capable of synthesizing an orbital angular momentum mode using a plurality of modes having the same propagation constant and a method for manufacturing the same.

The problem to be solved by the present invention is not limited to those mentioned above, and another problem to be solved that is not mentioned can be clearly understood by those of ordinary skill in the art to which the present invention belongs from the following description. will be.

The present invention, according to one aspect, a clad portion; and a core portion having rotational symmetry with respect to the central axial direction and surrounded by the cladding portion, wherein when waveguide modes having different phase differences pass through the core portion, having orbital angular momentum (OAM) It can be waveguided in waveguide mode.

In this case, the clad part and the core part _{may include SiO 2} SiN or Si, which is a light-transmitting material.

In addition, the core portion may be provided in a cross shape having rotational symmetry with respect to the central axial direction.

In addition, the core portion includes a core central portion; and a symmetrical core formed to protrude at equal intervals in the circumferential direction of the central portion of the core to have rotational symmetry with respect to the central axial direction.

The present invention, according to one aspect, stacking a first clad layer; first etching the first clad layer to form a groove on the first clad layer; laminating a core layer on the first clad layer in which the groove portion is formed; secondary etching of both sides of the core layer with the groove of the first clad layer as a center; third etching the core layer to form a core portion having rotational symmetry; and laminating a second clad layer on the core part and the first clad layer so that the clad part is formed to surround the core part.

In this case, in the second etching step and the third etching step, the core layer may be etched to form a cross-shaped core portion having rotational symmetry with respect to the central axial direction.

According to an embodiment of the present invention, synthesis and propagation of an OAM mode is possible in an optical waveguide manufactured through a general semiconductor stacking process, which is a Lager-Gaussian having a specific OAM through synthesis of a plurality of modes having the same propagation constant. Mode waveguide is possible.

In addition, according to an embodiment of the present invention, it is possible to generate and propagate Lager-Gaussian modes having different quantum numbers in one structure by changing the structure of the core layer.

1 is a cross-sectional view schematically illustrating an integrated optical waveguide for an orbital angular momentum mode according to an embodiment of the present invention.
2 is a state diagram schematically illustrating a primary OAM (orbital angular momentum) mode guided through an integrated optical waveguide for an orbital angular momentum mode according to an embodiment of the present invention.
3 is a state diagram schematically illustrating a secondary OAM (orbital angular momentum) mode guided through an integrated optical waveguide for an orbital angular momentum mode according to an embodiment of the present invention.
4 is a photograph showing the electric field distribution of the secondary OAM (orbital angular momentum) mode guided through the integrated optical waveguide for the orbital angular momentum mode according to an embodiment of the present invention.
5 is a photograph showing an electric field distribution in a tertiary OAM (orbital angular momentum) mode guided through an integrated optical waveguide for an orbital angular momentum mode according to an embodiment of the present invention.
6 is a photograph showing an electric field distribution in a quaternary OAM (orbital angular momentum) mode guided through an integrated optical waveguide for an orbital angular momentum mode according to an embodiment of the present invention.
7 is a flowchart illustrating a method of manufacturing an integrated optical waveguide for an orbital angular momentum mode according to an embodiment of the present invention.
8 is a state diagram illustrating a manufacturing process of an integrated optical waveguide for an orbital angular momentum mode according to an embodiment of the present invention.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms, and only these embodiments allow the disclosure of the present invention to be complete, and those of ordinary skill in the art to which the present invention pertains. It is provided to fully inform the person of the scope of the invention, and the scope of the invention is only defined by the claims.

In describing the embodiments of the present invention, detailed descriptions of well-known functions or configurations will be omitted except when it is actually necessary to describe the embodiments of the present invention. In addition, the terms to be described later are terms defined in consideration of functions in an embodiment of the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

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

1 is a cross-sectional view schematically illustrating an integrated optical waveguide for an orbital angular momentum mode according to an embodiment of the present invention.

As shown in FIG. 1 , in the integrated optical waveguide according to an embodiment of the present invention, when waveguide modes having different phase differences are propagated to the core unit 120 , the integrated optical waveguide is guided in a waveguide mode having orbital angular momentum. ) can be provided with a core portion 120 that can be. Here, the orbital angular momentum (OAM) may be understood as a momentum having an orbital motion that periodically rotates toward the center of the medium (central axial direction). The optical waveguide may be disposed to have a central axis direction parallel to a direction in which light is guided.

Specifically, the core part 120 may enable waveguide of the orbital angular momentum mode in the optical waveguide through a structure having rotational symmetry with respect to the central axial direction. The core part 120 may be provided in a structure surrounded by the clad part 110 . The clad part 110 and the core part 120 may include _{at least one of SiO 2} SiN and Si, which are light-transmitting materials. In this embodiment, the clad part 110 _{may be made of SiO 2} which is a light-transmitting material, and the core part 120 may be made of Si.

The core part 120 may include a core central part 121 including a central axis (C) direction and a symmetrical core part 122 spaced apart at equal intervals in the circumferential direction of the core central part 121 to protrude. have. The core symmetrical part 122 may be provided in pairs to have rotational symmetry with respect to the central axial direction. Here, rotational symmetry means having a symmetrical shape to maintain the same posture when rotated by a predetermined angle with respect to the central axis direction.

For example, the core part 120 may be provided in a cross shape having rotational symmetry with respect to the central axial direction. Since the core part 120 has a cross shape having rotational symmetry, it is possible to propagate a Lager-Gaussian mode having a specific orbital angular momentum by synthesizing a plurality of modes having the same propagation constant. In order to create a Lager-Gaussian mode having an orbital angular momentum (OAM), a plurality of modes may be synthesized at a specific ratio.

In the present embodiment, the long width W2 of the core part may be 1.626 μm, the short width W1 may be 1.118 μm, the high height L2 may be 1.504 μm, and the low height L1 may be 0.921 μm. At this time, the length ratio (W2/L2) of the long width (W2) to the high height (L2) satisfies the range of 1.0 to 1.2, and the short length ratio (W1/) of the short width (W1) to the low height (L1) L1) may satisfy the range of 1.1 to 1.3. If the long length ratio (W2/L2) is less than 1.0 or the long length ratio (W2/L2) is more than 1.2, the synthesis and propagation of OAM mode may not be well implemented in the optical waveguide, and the short length ratio (W1/L1) If is less than 1.1 or the stage length ratio (W1/L1) is greater than 1.3, synthesis and propagation of higher-order OAM modes may not be well implemented in the optical waveguide.

2 is a state diagram schematically illustrating a primary OAM (orbital angular momentum) mode guided through an integrated optical waveguide for an orbital angular momentum mode according to an embodiment of the present invention.

For example, as shown in FIG. 2 , in the core part 120 of the integrated optical waveguide according to the present invention, Hermitian-Gaussian 10 mode (200: HG ₁₀ ), Hermite-Gaussian 01 mode (201: If HG ₀₁ ) is synthesized with the same magnitude and a phase difference of 90 degrees from each other, Lager-Gaussian 01 mode (202:LG ₀₁ ) can be synthesized.

3 is a state diagram schematically illustrating a secondary OAM (orbital angular momentum) mode guided through an integrated optical waveguide for an orbital angular momentum mode according to an embodiment of the present invention, and FIG. 4 is an embodiment of the present invention. This is a photograph showing the electric field distribution of the secondary OAM (orbital angular momentum) mode guided through the integrated optical waveguide for the orbital angular momentum mode.

3 to 4 , in the core part 120 of the integrated optical waveguide according to the present invention, a Lager-Gaussian is the sum of the _{Hermitian-Gaussian 20 mode (HG 20} ) and the 02 mode (HG _{02 ).} The 02-even mode 300 can be synthesized. The synthesized Lager-Gaussian 02-even mode (300: LG ^e ₀₂ ) and the Hermitian-Gaussian 11 mode (HG ₁₁ ) with a phase difference of 90 degrees Lager-Gaussian 02-odd mode (301: LG ^o ₀₂ ) having the same electric field distribution A complete Lager-Gaussian 02 mode (302: LG ₀₂ ) can be synthesized from

In this way, instead of directly excitation of Hermitian-Gaussian 20 mode (HG ₂₀ ) and 02 mode (HG ₀₂ ), Lager-Gaussian 02-even mode (LG ^e ₀₂ ) is used to synthesize Lager-Gaussian 02 mode more simply. can do.

5 is a photograph showing an electric field distribution in a tertiary OAM (orbital angular momentum) mode guided through an integrated optical waveguide for an orbital angular momentum mode according to an embodiment of the present invention.

As shown in FIG. 5 , in the core part 120 of the integrated optical waveguide according to the present invention, it is a Lager-Gaussian 03-even as a sum of _{Hermitian-Gaussian 30 modes (HG 30} ) and 12 modes (HG _{12 ).} Mode (LG ^e ₀₃ ) can be synthesized. In addition, the Lager-Gaussian 03-odd mode (LG ^o ₀₃ ) may be synthesized by the sum of the Hermitian-Gaussian 21 mode (HG ₂₁ ) and the 03 mode (HG _{03 ).}

When Lager-Gaussian 03-even mode (LG ^e ₀₃ ) and Lager-Gaussian 03-odd mode (LG ^o ₀₃ ) are synthesized, the synthesized Lager-Gaussian 03-even mode (LG ^e ₀₃ ) and Lager-Gaussian 03-odd A complete Lager-Gaussian 03 mode (LG ₀₃ ) can be synthesized from the mode (LG ^o _{03 ).}

6 is a photograph showing an electric field distribution in a quaternary OAM (orbital angular momentum) mode guided through an integrated optical waveguide for an orbital angular momentum mode according to an embodiment of the present invention.

As shown in FIG. 6 , in the core part 120 of the integrated optical waveguide according to the present invention, the sum of _{Hermitian-Gaussian 40 modes (HG 40} ), 22 modes (HG ₂₂ ), and 04 modes (HG _{04 )} Lager-Gaussian 04-even mode (LG ^e ₀₄ ) can be synthesized with In addition, the Lager-Gaussian 04-odd mode (LG ^o ₀₄ ) may be synthesized by the sum of Hermitian-Gaussian 31 modes (HG ₃₁ ) and 13 modes (HG _{13 ).}

When Lager-Gaussian 04-even mode (LG ^e ₀₄ ) and Lager-Gaussian 04-odd mode (LG ^o ₀₄ ) are synthesized, the synthesized Lager-Gaussian 04-even mode (LG ^e ₀₄ ) and Lager-Gaussian 04-odd A complete Lager-Gaussian 04 mode (LG ₀₄ ) can be synthesized from the mode (LG ^o _{04 ).}

Meanwhile, higher-order, higher-order OAM modes not specified in the drawings may be generated in the same manner as described above.

In particular, in order for the OAM mode to propagate without distortion in the optical waveguide, the difference in propagation constant between the Hermitian-Gaussian modes constituting the OAM mode should be minimized. In the present invention, this can be implemented by minimizing the difference between the propagation constants of the even and odd terms of the Lagerian-Gaussian mode, which is the sum of the Hermitian-Gaussian modes, using the cross-shaped symmetry.

7 is a flowchart illustrating a method of manufacturing an integrated optical waveguide for orbital angular momentum mode according to an embodiment of the present invention, and FIG. 8 is an integrated optical waveguide for orbital angular momentum mode according to an embodiment of the present invention. It is a state diagram showing the manufacturing process.

7 to 8 , the method of manufacturing an integrated optical waveguide according to an embodiment of the present invention includes: stacking a first clad layer ( S100 ); Step (S200), stacking the core layer on the first cladding layer (S300), performing secondary etching on both sides of the core layer (core film) (S400), and tertiarily applying the core layer (core film) It may include etching (S500) and laminating a second clad layer (S600).

In the step of stacking the first clad layer ( S100 ), the first cladding layer 101 may be deposited on the base Si. For lamination of the first clad layer 101 , a low pressure chemical vapor deposition (LPCVD) may be used.

In the step of performing the primary etching of the first clad layer ( S200 ), the first clad layer 101 is etched (reactive ion etching (RIE)) such that the groove portion 101a is formed on the upper portion of the first clad layer 101 . Alternatively, (ICP)-RIE (inductively coupled plasma reactive ion etching) may be performed. In order to partially primary etch the first clad layer 101 , a photomask and photoresist may be used.

In the step of stacking the core layer on the first clad layer ( S300 ), the core layer 102 (core film) may be stacked on the first cladding layer 101 in which the groove portion 101a is formed. In order to deposit the core layer 102 on the first clad layer 101 , a low-pressure chemical vapor deposition (LPCVD) may be used.

In the secondary etching of both sides of the core layer (core film) ( S400 ), the side portions 102a of the core layer 102 stacked on the first clad layer 101 may be secondary etched. In this case, both side portions 102a of the core layer 102 may be etched with the groove portion 101a of the first cladding layer 101 as a center.

In the third etching of the core layer (core film) ( S500 ), the edge portions 102b on both sides of the core layer 102 on which both side portions 102a are secondarily etched are thirdly etched. In this case, the core layer 102 may be etched into a cross-shaped core part 120 having rotational symmetry with respect to the central axial direction.

In the step of stacking the second cladding layer ( S600 ), the second cladding layer 101 may be stacked on the cross-shaped core part 120 and the first cladding layer 101 . When the second clad layer 101 is stacked on the core part 120 and the first clad layer 101 , the clad part 110 surrounding the core part 120 may be formed.

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains may make various substitutions, modifications, and changes within the scope not departing from the essential characteristics of the present invention. It will be easy to see that this is possible. That is, 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.

Accordingly, the protection scope of the present invention should be interpreted by the claims described below, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

110: clad part
120: core part
121: core center
122: core symmetrical part
200: Hermitian-Gaussian 10-mode (HG ₁₀ ) electric field distribution
201: Electric field distribution of Hermitian-Gaussian 01 mode (HG _{01 )}
202: electric field distribution of Lager-Gaussian 01 mode (LG _{01 )}
300: Lager-Gaussian 02-even mode (LG ^e ₀₂ ) electric field distribution
301: Lager-Gaussian 02-odd mode (LG ^o ₀₂ ) electric field distribution
302: Lager-Gaussian 02 mode (LG ₀₂ ) electric field distribution

Claims (6)

clad part; and
and a core part having rotational symmetry with respect to the central axial direction and surrounded by the cladding part;
When a waveguide mode having a different phase difference passes through the core part, it is guided to a waveguide mode having an orbital angular momentum (OAM),
the core part
It includes a core center and a core symmetrical portion protruding at equal intervals in the circumferential direction of the core center to have rotational symmetry with respect to the central axial direction, and is provided in a cross shape having rotational symmetry with respect to the central axial direction Propagating a Lager-Gaussian mode with a specific orbital angular momentum through the synthesis of multiple modes having the same propagation constant
Integrated optical waveguide for orbital angular momentum mode. The method of claim 1,
The clad part and the core part
Light-transmitting material SiO ₂ comprising at least one of SiN and Si,
Integrated optical waveguide for orbital angular momentum mode. The method of claim 1,
The long length ratio of the long width to the high height of the core part,
satisfy the range of 1.0 ~ 1.2,
The step length ratio of the hem width to the low height of the core part,
1.1 to 1.3,
Integrated optical waveguide for orbital angular momentum mode. delete stacking a first clad layer;
first etching the first clad layer to form a groove on the first clad layer;
laminating a core layer on the first clad layer in which the groove portion is formed;
secondary etching of both sides of the core layer with the groove of the first clad layer as a center;
third etching the core layer to form a core portion having rotational symmetry; and
laminating a second clad layer on the core portion and the first clad layer to form a clad portion surrounding the core portion;
The second etching step and the third etching step are,
The core layer is etched to form a cross-shaped core portion having rotational symmetry with respect to the central axial direction;
the core part
It includes a core center and a core symmetrical portion protrudingly spaced apart at equal intervals in the circumferential direction of the core center to have rotational symmetry with respect to the central axial direction, and is provided in a cross shape having rotational symmetry with respect to the central axial direction, Propagating a Lager-Gaussian mode with a specific orbital angular momentum through the synthesis of multiple modes having the same propagation constant,
A method for manufacturing an integrated optical waveguide for orbital angular momentum mode. delete

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