Device and method for realizing near-field dual-polarization perfect Janus dipole

Abstract

The invention discloses a device and a method for realizing a near-field dual-polarization perfect Janus dipole, and relates to the technical field of near-field coupling and excitation of dipoles. The implementation device comprises a dual-polarization perfect Janus dipole and two dielectric waveguides which are arranged in parallel. The implementation method comprises the steps of designing parameters of the dielectric waveguides and the dipoles, constructing a rectangular coordinate system, placing the two parallel dielectric waveguides on an xy plane, and placing the dipoles in the middle positions of the parallel dielectric waveguides. P-polarized and s-polarized waves excited by the dipole are coupled to the dielectric waveguide to excite guided waves, an electromagnetic field on the surface of the dielectric waveguide is detected through a detection device, and the near-field coupling characteristic of the dual-polarized perfect dipole is analyzed based on extracted field distribution data. The invention provides a new way for the development of polarization multiplexing photonic devices, quantum routing and on-chip signal processing technologies.

Description

Technical Field

[0001] The present invention relates to the technical field of dipole near-field coupling and excitation, and in particular to a device and method for realizing a near-field dual-polarization perfect Janus dipole. Background Art

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

[0003] A Janus dipole has two distinct faces during near-field coupling: the coupling face and the non-coupling face. When an external coupler (such as a dielectric waveguide) is aligned with the non-coupling face of the Janus dipole, the guided wave cannot be effectively excited. Conversely, when the external coupler is aligned with the coupling face, 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 discovered that the orientation of the non-coupling and coupling faces of a Janus dipole is polarization-dependent. For example, if the non-coupling face of an s-polarized wave faces upward, the non-coupling face of a p-polarized wave faces downward. Therefore, when a Janus dipole is placed between two parallel waveguides, the Janus dipole can primarily excite p-polarized waves into the upper waveguide while exciting s-polarized guided waves into the lower waveguide.

[0004] In addition, the non-coupling surface of the Janus dipole can be designed to completely suppress the excitation of guided waves of a specific polarization (such as s-polarization or p-polarization), thereby producing a single-polarization perfect Janus dipole. For example, a technical solution proposes that by optimizing the constituent dipole moments, a Janus dipole can be designed that completely suppresses the excitation of s-polarized guided waves on the non-coupling surface. At present, only single-polarization perfect Janus dipoles have been reported. The technology of perfect Janus dipoles in near-field coupling is still in its infancy. Is there a dual-polarization perfect Janus dipole? However, this question remains difficult to answer.

[0005] Therefore, it is an urgent problem for those skilled in the art to provide an apparatus and method for realizing a dual-polarization perfect Janus dipole based on near-field coupling to solve the difficulties existing in the prior art. Summary of the Invention

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

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

[0008] The present invention provides a device for realizing a near-field dual-polarization perfect Janus dipole, comprising an external coupler, a dipole, and a detection device; the external coupler is two parallel dielectric waveguides; the dipole is a dual-polarization perfect Janus dipole after designing parameters, and is placed in the middle position 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 outer coupler is two parallel placed dielectric waveguides with a relative dielectric constant of 3, supporting the transmission of p-polarized guided waves and s-polarized guided waves.

[0010] Furthermore, the Janus dipole is composed of an electric dipole and a magnetic dipole 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 faces the coupling surface of the Janus dipole, the guided wave can be effectively excited; and when the external coupler faces the non-coupling surface of the Janus dipole, the guided wave cannot be effectively excited.

[0012] In a second aspect, the present invention provides a method for realizing a near-field dual-polarization perfect Janus dipole, comprising the following steps:

[0013] Design the parameters of 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 in the middle of 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 excite guided waves;

[0016] The electromagnetic field on the surface of the dielectric waveguide is detected by a receiving probe to obtain a field distribution map;

[0017] The near-field coupling characteristics of a dual-polarized perfect Janus dipole are analyzed based on the extracted field distribution data.

[0018] Furthermore, the Janus dipole is composed of electric dipoles that are perpendicular to each other and have a phase difference of 90°. and magnetic dipoles Composition, and satisfy the relationship m y / (p x ·i·c) are real numbers.

[0019] Furthermore, the excitation of the p-polarized wave is carried out by a potentiometer. To describe, by plane wave expansion, p-polarized wave Expressed as:

[0020]

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

[0022] Furthermore, the excitation of the s-polarized wave is achieved by the magnetic flux density To describe, it is expressed as:

[0023]

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

[0025] Furthermore, the conditions for achieving the dual-polarization perfect Janus dipole are:

[0026]

[0027] in, and are the z components of the wave vectors of the p-polarized wave and the s-polarized wave respectively, k0 = ω / c, ω is the angular frequency, and c is the speed of light in 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, the present invention achieves the complete simultaneous suppression of the uncoupled surfaces of the p-polarized waveguide and the s-polarized waveguide, thereby realizing a new mechanism of dual-polarized perfect Janus dipole; (2) By selecting the dielectric waveguide as the external coupler, the present invention achieves the maximum transmission directionality for both transverse electric polarization and transverse magnetic polarization waveguide, which has broad application prospects in photonic integrated circuits; (3) The present invention provides a deeper understanding of the near-field coupling mechanism of dipoles, and provides a new approach for polarization multiplexing nanophotonic devices, quantum routing architectures and on-chip signal processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

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

[0032] Figure 2 Schematic diagram of a device for realizing a dual-polarization perfect Janus dipole disclosed in an embodiment of the present invention;

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

[0034] Figure 4 Schematic diagram of the dispersion curve of p-polarized waves in a dielectric waveguide disclosed in an embodiment of the present invention;

[0035] Figure 5 Schematic diagram of the dispersion curve of the dielectric waveguide S-polarization wave disclosed in an embodiment of the present invention;

[0036] Figure 6 A schematic diagram of frequency points for realizing a dual-polarization perfect Janus dipole disclosed in an embodiment of the present invention;

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

[0038] Figure 8 Schematic diagram of the xz-plane electric displacement vector excited by a dual-polarized perfect Janus dipole disclosed in an embodiment of the present invention;

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

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

[0041] Figure 11 Schematic diagram of the xy-plane magnetic induction intensity excited by a dual-polarized perfect Janus dipole disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

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

[0043] The object of the present invention is achieved through the following technical solutions:

[0044] Example 1

[0045] like Figure 2 As shown, this embodiment provides a device for realizing a near-field dual-polarization perfect Janus dipole, including an external coupler, a dipole, and a detection device; the external coupler is two parallel dielectric waveguides, and the dielectric waveguide structure is composed of air-dielectric-air, wherein the relative dielectric constant and thickness of the dielectric determine its dispersion characteristics; the dipole is a dual-polarization perfect Janus dipole after design parameters, which is placed in the middle position of the parallel dielectric waveguides and can excite p-polarization and s-polarization guided wave modes in the dielectric waveguide; the detection device is used to measure the near-field electromagnetic field distribution on the surface of the dielectric waveguide, and the detection device 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 is composed of a pair of electric dipole and 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 outer coupler is composed of two parallel dielectric waveguides, and the relative dielectric constant of the waveguide is 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-polarization perfect Janus dipole, including the following steps:

[0050] Design the parameters of 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] The p-polarized and s-polarized waves excited by the Janus dipole couple into the dielectric waveguide to excite guided waves;

[0053] The electromagnetic field on the surface of the dielectric waveguide is detected by a receiving probe to obtain a field distribution map;

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

[0055] like Figure 2 As shown, the outer coupler consists of two parallel dielectric waveguides with a relative dielectric constant of ε r , with a thickness of d0. The vertical distance between the upper and lower waveguides is d1. Without loss of generality, a waveguide with an electric dipole moment and magnetic dipole moment The Janus dipole is placed in the middle of the 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 get and in is the current density corresponding to the Janus dipole. Here and Select electric displacement To describe the p-polarized wave, choose the magnetic flux density To describe the s-polarized wave. By plane wave expansion, the p-polarized wave It can be expressed as:

[0057]

[0058] Where k0 = ω / c, c is the speed of light in vacuum. The "+" ("-") sign in formula (3) applies to z>0 (z<0). For stimulated p-polarization guided waves in a lossless dielectric waveguide, k z is a purely imaginary number, in 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] Formula (4) means that when z < 0, that is, on the non-coupling surface of the Janus dipole, the p-polarized guided wave will always undergo coherent decomposition. In addition, the condition for completely suppressing the p-polarized guided wave excitation on the non-coupling surface is:

[0061]

[0062] Similarly, by plane wave expansion, the s-polarized wave It can be expressed as:

[0063]

[0064]

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

[0066]

[0067] Formula (9) means that when z>0, that is, on the non-coupling surface of the Janus dipole, the s-polarized guided wave will always undergo coherent decomposition. In addition, the condition for completely suppressing the s-polarized guided wave excitation on the non-coupling surface is:

[0068]

[0069] According to equations (5) and (10), to realize a dual-polarization perfect Janus dipole, we need:

[0070]

[0071] In one embodiment, starting from a conceptual diagram of a dual-polarized perfect Janus dipole, e.g. Figure 2 From the conceptual diagram, it can be found that when a dual-polarized perfect Janus dipole is placed between two parallel dielectric planar waveguides, the p-polarized guided wave will be excited only in one waveguide, while the s-polarized guided wave will be excited only in the other waveguide.

[0072] Here, we demonstrate the realization of a dual-polarization perfect Janus dipole, which requires careful co-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, the relative permittivity is chosen to be ε r and a dielectric waveguide with a thickness of d0, the two-dimensional schematic diagram is as follows Figure 3The specific design process of the waveguide to achieve dual-polarization perfect Janus dipole is as follows. Figure 4 and Figure 5 The dispersion relation of the p-polarized wave supported by the waveguide is shown as 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 Multiplying together, we get The curve is Figure 6 As shown in formula (11), as long as Under the conditions of , the waveguide can realize dual-polarization perfect Janus dipole. Figure 6 This condition can only be met at 68.2 THz, so 68.2 THz is selected as the operating frequency.

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

[0074] In order to demonstrate the possibility of realizing near-field coupled dual-polarized perfect Janus dipoles, two Figure 3 The dual-polarized perfect Janus dipole is located in the middle of the waveguide. The field distribution of the guided wave excited by the Janus dipole is as follows: Figures 8-11 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 The p-polarized guided wave in the middle and lower waveguides is not excited, while the s-polarized guided wave in the upper waveguide is not excited. Therefore, the emergence of a dual-polarization perfect Janus dipole requires the joint design of the outer coupler (such as a dielectric waveguide) and the Janus dipole.

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

Claims

1. A device for realizing a near-field dual-polarization perfect Janus dipole, characterized in that: including an external coupler, a dipole, and a detection device; The outer coupler is two parallel placed dielectric waveguides; The dipole is a dual-polarization perfect Janus dipole after designing parameters and is 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.

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

3. The device for realizing near-field dual-polarization perfect Janus dipole according to claim 2, characterized in that: The Janus dipole is composed of an electric dipole and a magnetic dipole that are perpendicular to each other and have a phase difference of 90 degrees. The Janus dipole is placed between two parallel dielectric waveguides to excite p-polarized and s-polarized guided wave modes in the dielectric waveguides.

4. The device for realizing near-field dual-polarization perfect Janus dipole according to claim 3, characterized in that: 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.

5. A method for realizing a near-field dual-polarization perfect Janus dipole, applied to the device according to any one of claims 1 to 4, characterized in that: The following steps are involved: Design the parameters of 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 in the middle of 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 excite guided waves; The electromagnetic field on the surface of the dielectric waveguide is detected by a receiving probe to obtain a field distribution map; The near-field coupling characteristics of a dual-polarized perfect Janus dipole are analyzed based on the extracted field distribution data.

6. The method for realizing a near-field dual-polarization perfect Janus dipole according to claim 5, characterized in that: The parameters for designing the dielectric waveguide structure and the Janus dipole include: the relative dielectric constant and thickness of the waveguide, the vertical distance between the upper and lower waveguides, and the electric dipole moment and magnetic dipole moment of the Janus dipole.

7. The method for realizing a near-field dual-polarization perfect Janus dipole according to claim 5, characterized in that: The Janus dipole is composed of mutually perpendicular electric dipoles with a phase difference of 90°. and magnetic dipoles Composition, and satisfy the relationship m y / (p x ·i·c) are real numbers.

8. The method for realizing a near-field dual-polarization perfect Janus dipole according to claim 7, characterized in that: The p-polarized wave is excited by the electric displacement To describe, by plane wave expansion, p-polarized wave Expressed as: Where k0 = ω / c, ω is the angular frequency, c is the speed of light in vacuum, D z is the z component of the potential vector, k x 、k y and k z are the x, y, and z components of the wave vector, m y is the magnetic dipole moment of the Janus dipole, p x is the electric dipole moment of the Janus dipole.

9. The method for realizing a near-field dual-polarization perfect Janus dipole according to claim 8, characterized in that: The s-polarized wave is excited by the magnetic flux density To describe, it is expressed as: Among them, B z is the z component of the magnetic field strength, k x 、k y and k z are the x, y, and z components of the wave vector, m y is the magnetic dipole moment of the Janus dipole, p x is the electric dipole moment of the Janus dipole.

10. The method for realizing a near-field dual-polarization perfect Janus dipole according to claim 9, characterized in that: The conditions for achieving the dual-polarization perfect Janus dipole are: in, and are the z components of the wave vectors of the p-polarized wave and the s-polarized wave respectively, k0 = ω / c, ω is the angular frequency, and c is the speed of light in vacuum.

Images