An apparatus and method for realizing a near-field dual-polarized perfect janus dipole

Abstract

The application discloses a device and method for realizing a near-field dual-polarization perfect Janus dipole, and relates to the technical field of dipole near-field coupling and excitation. The device for realization comprises a dual-polarization perfect Janus dipole and two parallelly placed dielectric waveguides. The method for realization comprises designing dielectric waveguide and dipole parameters, constructing a rectangular coordinate system, placing two parallel dielectric waveguides in an xy plane, and placing the dipole at a middle position of the parallel dielectric waveguides. P-polarization and s-polarization waves excited by the dipole are coupled into the dielectric waveguides to excite guided waves. An electromagnetic field on a surface of the dielectric waveguide is detected through a detection device, and near-field coupling characteristics of the dual-polarization perfect dipole are analyzed based on extracted field distribution data. The application provides a new approach for the development of polarization multiplexing photonic devices, quantum routing and on-chip signal processing technology.

Description

Technical Field

[0001] This invention relates to the field of dipole near-field coupling and excitation technology, specifically to a device and method for realizing a near-field dual-polarized perfect Janus dipole. Background Technology

[0002] Near-field directional excitation of light is important for many applications, including integrated photonic routing, on-chip optics, and sensing. There are two main approaches to achieving near-field directional excitation of light: one approach relies on the structural design of the external coupler, such as using asymmetric nanocouplers and waveguides; the other approach relies on the design of the light source, such as using circularly polarized dipoles, Huygens dipoles, and Janus dipoles, in which the dipole moments constituting the dipoles are carefully tailored.

[0003] A Janus dipole has two distinct surfaces during near-field coupling: the so-called coupling surface and the uncoupled surface. When an external coupler (such as a dielectric waveguide) is aligned with the uncoupled surface of the Janus dipole, the guided wave cannot be effectively excited. Conversely, when the external coupler is aligned with the coupling surface, the guided wave can be effectively excited. In practice, these Janus dipoles can be fabricated using high-refractive-index dielectric nanoparticles or custom antenna structures. Furthermore, recent studies have found that the orientation of the uncoupled and coupling surfaces of the Janus dipole is related to polarization. For example, if the uncoupled surface of an s-polarized wave faces upward, the uncoupled surface of a p-polarized wave faces downward. Therefore, when a Janus dipole is placed between two parallel waveguides, it can primarily excite p-polarized waves to the upper waveguide and s-polarized guided waves to the lower waveguide.

[0004] Furthermore, the uncoupled surface of a Janus dipole can be designed to completely suppress the excitation of guided waves with specific polarizations (such as s-polarization or p-polarization), thereby generating a single-polarized perfect Janus dipole. For example, some technical solutions propose that by optimizing the constituent dipole moments, a Janus dipole that completely suppresses the excitation of s-polarized guided waves on the uncoupled surface can be designed. Currently, only single-polarized perfect Janus dipoles have been reported. Perfect Janus dipole technology in near-field coupling is still in its early stages. Does a bipolarized perfect Janus dipole exist? However, this question remains difficult to answer.

[0005] Therefore, providing a device and method for realizing a bipolar perfect Janus dipole based on near-field coupling to overcome the difficulties in the prior art is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] Based on the problems raised in the background art above, the purpose of this invention is to provide a device and method for realizing a near-field dual-polarized perfect Janus dipole, opening up new avenues for the development of advanced polarization multiplexed photonic devices and systems.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] The present invention provides a device for realizing a near-field dual-polarized perfect Janus dipole, comprising an external coupler, a dipole, and a detection device; the external coupler consists of two parallel dielectric waveguides; the dipole is a dual-polarized perfect Janus dipole with designed parameters, placed in the middle of the parallel dielectric waveguides; the detection device is used to measure the near-field electromagnetic field distribution on the surface of the dielectric waveguide.

[0009] Furthermore, the external coupler consists of two parallel dielectric waveguides with a relative permittivity of 3, supporting the transmission of p-polarized and s-polarized guided waves.

[0010] Furthermore, the Janus dipole is composed of electric dipoles and magnetic dipoles that are perpendicular to each other and have a phase difference of 90°. The Janus dipole is placed between two parallel dielectric waveguides to excite p-polarized and s-polarized guided wave modes in the dielectric waveguides.

[0011] Furthermore, when the external coupler is oriented toward the coupling surface of the Janus dipole, the guided wave can be effectively excited; when the external coupler is oriented toward the uncoupled surface of the Janus dipole, the guided wave cannot be effectively excited.

[0012] Secondly, the present invention provides a method for realizing a near-field dual-polarized perfect Janus dipole, comprising the following steps:

[0013] Design parameters for dielectric waveguide structures and Janus dipoles;

[0014] Construct a spatial rectangular coordinate system, place two parallel dielectric waveguides in the xy plane, and place the Janus dipole between the two parallel dielectric waveguides;

[0015] The p-polarized wave and s-polarized wave are excited by Janus dipole and coupled into the dielectric waveguide to generate guided waves.

[0016] The electromagnetic field distribution map is obtained by detecting the surface of the dielectric waveguide using a receiving probe.

[0017] The near-field coupling characteristics of the bipolar perfect Janus dipole were analyzed based on the extracted field distribution data.

[0018] Furthermore, the Janus dipole consists of mutually perpendicular electric dipoles with a phase difference of 90°. and magnetic dipole It consists of, and satisfies the relation m y / (p x ·i·c) are real numbers.

[0019] Furthermore, the excitation of the p-polarized wave is achieved via a potentiometer. To describe, through plane wave expansion, p-polarized waves Represented as:

[0020]

[0021] Where k0 = ω / c, c is the speed of light in a vacuum, and D z It is the z-component of the potential vector, k x k y and k z These are the x, y, and z components of the wave vector, respectively, m y It is the magnetic dipole moment of the Janus dipole, p x It is the electric dipole moment of the Janus dipole.

[0022] Furthermore, the excitation of the s-polarized wave is achieved through magnetic flux density. To describe, represented as:

[0023]

[0024] Among them, B z It is the z-component of the magnetic field strength, k x k y and k z These are the x, y, and z components of the wave vector, respectively, m y It is the magnetic dipole moment of the Janus dipole, p x It is the electric dipole moment of the Janus dipole.

[0025] Furthermore, the conditions for realizing the aforementioned bipolarized perfect Janus dipole are:

[0026]

[0027] in, and These are the z-components of the wave vectors of the p-polarized wave and the s-polarized wave, respectively, k0 = ω / c, where ω is the angular frequency and c is the speed of light in a vacuum.

[0028] Based on the above technical solution, the embodiments of the present invention can produce at least the following technical effects:

[0029] (1) By carefully designing the parameters of the dielectric waveguide and the Janus dipole, this invention achieves simultaneous and complete suppression of the uncoupled surfaces of p-polarized and s-polarized guided waves, thus realizing a new mechanism for a perfect dual-polarized Janus dipole; (2) By selecting the dielectric waveguide as the external coupler, this invention achieves maximum transmission directionality for both transversely polarized and transversely magnetically polarized guided waves, which has broad application prospects in photonic integrated circuits; (3) This invention provides a deeper understanding of the near-field coupling mechanism of dipoles and provides new approaches for polarization multiplexing nanophotonic devices, quantum routing architectures, and on-chip signal processing. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0031] Figure 1 This is a flowchart of a method for realizing a near-field dual-polarized perfect Janus dipole disclosed in an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the dual-polarized perfect Janus dipole realization device disclosed in an embodiment of the present invention;

[0033] Figure 3 This is a two-dimensional schematic diagram of the dielectric waveguide structure disclosed in an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the dispersion curve of the p-polarized wave in the dielectric waveguide disclosed in an embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of the s-polarization wave dispersion curve of the dielectric waveguide disclosed in an embodiment of the present invention;

[0036] Figure 6 This is a schematic diagram of the frequency point of the dual-polarized perfect Janus dipole disclosed in an embodiment of the present invention;

[0037] Figure 7 This is a schematic diagram of the Janus dipole design principle disclosed in an embodiment of the present invention;

[0038] Figure 8 This is a schematic diagram of the xz-plane electric displacement vector of a dual-polarized perfect Janus dipole excited according to an embodiment of the present invention;

[0039] Figure 9 This is a schematic diagram of the yz-plane magnetic induction intensity excited by a dual-polarized perfect Janus dipole, as disclosed in an embodiment of the present invention.

[0040] Figure 10 This is a schematic diagram of the xy-plane electric displacement vector excited by a dual-polarized perfect Janus dipole as disclosed in an embodiment of the present invention;

[0041] Figure 11 This is a schematic diagram of the xy-plane magnetic induction intensity excited by a dual-polarized perfect Janus dipole, as disclosed in an embodiment of the present invention. Detailed Implementation

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0043] The objective of this invention is achieved through the following technical solution:

[0044] Example 1

[0045] like Figure 2 As shown, this embodiment provides a device for realizing a near-field dual-polarized perfect Janus dipole, including an external coupler, a dipole, and a detection device. The external coupler consists of two parallel dielectric waveguides, the structure of which is composed of air-dielectric-air, wherein the relative permittivity and thickness of the dielectric determine its dispersion characteristics. The dipole is a dual-polarized perfect Janus dipole with optimized design parameters, placed in the middle of the parallel dielectric waveguides, which can excite p-polarized and s-polarized guided wave modes in the dielectric waveguides. The detection device is used to measure the near-field electromagnetic field distribution on the surface of the dielectric waveguide, and can measure the vertical electric displacement vector and magnetic induction intensity distribution on the surface of the dielectric waveguide.

[0046] In this embodiment, the Janus dipole consists of a pair of electric dipoles and a magnetic dipole that are perpendicular to each other and have a phase difference of 90°.

[0047] like Figure 3 As shown, in this embodiment, the external coupler consists of two parallel dielectric waveguides with a relative permittivity of ε. r The thickness is d0, and the vertical distance between the upper and lower waveguides is d1.

[0048] Example 2

[0049] like Figure 1As shown, this embodiment provides a method for realizing a near-field dual-polarized perfect Janus dipole, including the following steps:

[0050] Design parameters for dielectric waveguide structures and Janus dipoles;

[0051] Construct a spatial rectangular coordinate system, place two parallel dielectric waveguides in the xy plane, and place the dipole in the middle of the two waveguides;

[0052] Janus dipole-excited p-polarized and s-polarized waves are coupled into a dielectric waveguide to excite guided waves;

[0053] The electromagnetic field distribution map is obtained by detecting the surface of the dielectric waveguide using a receiving probe.

[0054] The near-field coupling characteristics of a bipolar perfect dipole are analyzed based on the extracted field distribution data.

[0055] like Figure 2 As shown, the external coupler consists of two parallel dielectric waveguides with a relative permittivity of ε. r The thickness is d0. The vertical distance between the upper and lower waveguides is d1. Without loss of generality, a waveguide with an electric dipole moment is... and magnetic dipole moment The Janus dipole is placed between these two waveguides. Here, for the Janus dipole, m y / (p x ·i·c) is a real number.

[0056] According to Maxwell's equations for air, we can derive... and in This is the current density corresponding to the Janus dipole. Here... and Select electric displacement To describe p-polarized waves, choose magnetic flux density To describe s-polarized waves. Through plane wave expansion, p-polarized waves... It can be represented as:

[0057]

[0058] Where k0 = ω / c, and c is the speed of light in vacuum. The "+" ("-") sign in formula (3) applies to z>0 (z<0). For stimulated p-polarized guided waves in a lossless dielectric waveguide, k z It is a purely imaginary number. in As for the Janus dipole, m y / (p x·i·c) is a real number. In this case, formula (3) can be rewritten as:

[0059]

[0060] Equation (4) implies that when z < 0, i.e., at the uncoupled surface of the Janus dipole, the p-polarized guided wave will always undergo coherent destructive phase. Furthermore, the condition for completely suppressing p-polarized guided wave excitation at the uncoupled surface is:

[0061]

[0062] Similarly, through plane wave expansion, s-polarized wave It can be represented as:

[0063]

[0064]

[0065] The "+" ("-") sign in formula (8) applies to z<0 (z>0). In this case, formula (8) can be rewritten as:

[0066]

[0067] Equation (9) implies that when z>0, i.e., at the uncoupled surface of the Janus dipole, the s-polarized guided wave will always undergo coherent destructive phase. Furthermore, the condition for completely suppressing s-polarized guided wave excitation at the uncoupled surface is:

[0068]

[0069] To achieve a perfectly bipolarized Janus dipole using formulas (5) and (10), the following is required:

[0070]

[0071] In one specific embodiment, we begin with a conceptual diagram of a bipolarized perfect Janus dipole, such as... Figure 2 From the conceptual diagram, it can be seen that when a dual-polarized perfect Janus dipole is placed between two parallel dielectric planar waveguides, the p-polarized waveguide will be excited in only one waveguide, while the s-polarized waveguide will be excited in only the other waveguide.

[0072] This section demonstrates the realization of a dual-polarized perfect Janus dipole, which requires careful joint design of the waveguide structure and the Janus dipole. The first step is to design the waveguide and the operating frequency. As a typical example, a relative permittivity of ε is chosen. r A two-dimensional schematic diagram of a dielectric waveguide with thickness d0 is shown below. Figure 3As shown. The specific design process of the waveguide to realize a dual-polarized perfect Janus dipole is as follows. Figure 4 and Figure 5 As shown. The dispersion relation of the p-polarized wave supported by the waveguide is as follows. Figure 4 As shown, the dispersion relation of the s-polarized wave supported by the waveguide is as follows: Figure 5 As shown. Figure 4 and Figure 5 In and Multiply, we get The curve is as follows Figure 6 As shown. From equation (11), it can be seen that as long as the following condition is met... Under certain conditions, waveguides can achieve perfectly bipolarized Janus dipoles. Figure 6 This condition can only be met at 68.2THz, so 68.2THz was chosen as the operating frequency.

[0073] The next step is to design the constituent dipole moments of the Janus dipole. According to formulas (9) and (10), the conditions for completely suppressing p-polarized or s-polarized guided wave excitation on the uncoupled surface are respectively... as well as like Figure 7 As shown, m y / (p x (·i·c) is a function of frequency. These two curves intersect at 68.2 THz, at which point m... y / (p x The value of ·i·c) = 0.89 indicates that it is possible to realize a bipolarized perfect Janus dipole at this selected frequency.

[0074] To demonstrate the possibility of realizing a near-field coupled bipolarized perfect Janus dipole, two [electrodes] were constructed. Figure 3 The same waveguide. A perfectly bipolarized Janus dipole is located in the middle of the waveguide, and the field distribution of the guided wave excited by the Janus dipole is as follows. Figures 8-11 As shown. Figure 8 and Figure 9 The field distribution of the excited p-polarized guided wave is shown. Figure 10 and Figure 11 The excited s-polarized guided wave field distribution is shown. Figures 8-11 In the middle waveguide, the p-polarized guided wave in the lower waveguide is not excited, while the s-polarized guided wave in the upper waveguide is not excited. Therefore, the emergence of a dual-polarized perfect Janus dipole requires the joint design of the external coupler (such as a dielectric waveguide) and the Janus dipole.

[0075] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An apparatus implementing a near-field dual-polarized perfect Janus dipole, characterized in that, Includes external couplers, dipoles, and detection devices; The external coupler consists of two parallel dielectric waveguides; The dipole is a double-polarized perfect Janus dipole with the design parameters, placed in the middle of the parallel dielectric waveguide. The detection device is used to measure the near-field electromagnetic field distribution on the surface of the dielectric waveguide; The Janus dipole consists of electric dipoles and magnetic dipoles that are perpendicular to each other and have a phase difference of 90°. The Janus dipole is placed between two parallel dielectric waveguides to excite p-polarized and s-polarized guided wave modes in the dielectric waveguides. When the external coupler faces the coupling surface of the Janus dipole, the guided wave can be effectively excited; when the external coupler faces the non-coupling surface of the Janus dipole, the guided wave cannot be effectively excited. The conditions for realizing the aforementioned bipolarized perfect Janus dipole are: ; in, and These are the z-components of the wave vectors of the p-polarized wave and the s-polarized wave, respectively. , It is the speed of light in a vacuum.

2. The device for realizing a near-field dual-polarized perfect Janus dipole according to claim 1, characterized in that, The external coupler consists of two parallel dielectric waveguides with a relative permittivity of 3, supporting the transmission of p-polarized and s-polarized guided waves.

3. A method for realizing a near-field dual-polarized perfect Janus dipole, applied to the device described in claim 1 or 2, characterized in that, Includes the following steps: Design parameters for dielectric waveguide structures and Janus dipoles; Construct a spatial rectangular coordinate system, place two parallel dielectric waveguides in the xy plane, and place the Janus dipole between the two parallel dielectric waveguides; The p-polarized wave and s-polarized wave are excited by Janus dipole and coupled into the dielectric waveguide to generate guided waves. The Janus dipole consists of mutually perpendicular electric dipoles with a phase difference of 90°. and magnetic dipole Composed of, and satisfying the relation It is a real number; The electromagnetic field distribution map is obtained by detecting the surface of the dielectric waveguide using a receiving probe. Analysis of near-field coupling characteristics of a bipolar perfect Janus dipole based on extracted field distribution data; The conditions for realizing the aforementioned bipolarized perfect Janus dipole are: ; in, and These are the z-components of the wave vectors of the p-polarized wave and the s-polarized wave, respectively. , It is the speed of light in a vacuum.

4. The method for realizing a near-field dual-polarized perfect Janus dipole according to claim 3, characterized in that, The parameters of the designed dielectric waveguide structure and Janus dipole include: the relative permittivity of the waveguide, its thickness, the vertical distance between the upper and lower waveguides, and the electric and magnetic dipole moments of the Janus dipole.

5. The method for realizing a near-field dual-polarized perfect Janus dipole according to claim 4, characterized in that, The excitation of the p-polarized wave is achieved through electric displacement. To describe, through plane wave expansion, p-polarized waves Represented as: ; in, , It is the speed of light in a vacuum. It is the z-component of the potential vector. , and These are the x, y, and z components of the wave vector, respectively. It is the magnetic dipole moment of the Janus dipole. It is the electric dipole moment of the Janus dipole.

6. The method for realizing a near-field dual-polarized perfect Janus dipole according to claim 5, characterized in that, The excitation of the s-polarized wave is achieved through magnetic flux density. To describe, represented as: ; in, It is the z-component of the magnetic field strength. , and These are the x, y, and z components of the wave vector, respectively. It is the magnetic dipole moment of the Janus dipole. It is the electric dipole moment of the Janus dipole.

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