Optical perfect supercoupling security information transmission device based on multi-layer nanometer film structure filling medium sheet

Abstract

This invention belongs to the field of transmission device technology and discloses a perfectly coupled secure information transmission device based on a multilayer nanofilm structure filled with a dielectric sheet. The device includes an input region, a transmission region, and an output region; the input and output regions are free space; the transmission region consists of a three-layer "sandwich" structure, which is formed by two layers of non-magnetic ENZ dielectric wrapped around a thin dielectric plate. This invention analyzes the effect of the amount of dielectric dopant on the electromagnetic resonant bandwidth of the doped ENZ dielectric when the above structure is equivalent to a lossy EMNZ material. The analysis shows that with the increase of the amount of dopant, the resonant bandwidth of the entire structure is significantly broadened, thereby extending the perfect absorption bandwidth of the above structure. Simultaneously, by using a multilayer Ag / silicon carbide nanofilm structure filled with dopant at a wavelength of 430 nm, an optically perfect absorber based on a lossy EMNZ dielectric with an extended operating bandwidth is designed.

Description

Technical Field

[0001] This invention belongs to the field of transmission device technology, and particularly relates to a perfectly coupled secure information transmission device based on a multilayer nanofilm structure filled dielectric sheet. Background Technology

[0002] The efficient transmission of electromagnetic waves has always been a fundamental technical problem in electromagnetic field theory and its applications, holding significant theoretical and engineering value in fields such as wireless communication, photonic integrated devices, and microwave transmission systems. Typically, when a plane electromagnetic wave propagates from one electromagnetic medium to another, reflection and transmission phenomena often occur when the incident wave couples with the medium interface due to the different electromagnetic parameters at the interface. The distribution of reflection and transmission is determined by the impedance difference between the media. When the incident region and the transmission region have an impedance mismatch, most of the incident energy is reflected, thus limiting the effective energy output, which is particularly evident between free space and a specific medium interface. Traditional transmission structures generally rely on adjusting geometric dimensions and material electromagnetic constants to reduce reflection loss and improve transmission efficiency. However, in practical engineering, this method usually requires structural resonance or gain compensation mechanisms, leading to problems such as increased device size, bandwidth limitation, and reduced frequency stability.

[0003] To address the low transmission efficiency of traditional structures, researchers have proposed a class of artificial materials based on extreme electromagnetic parameters. These materials achieve extraordinary electromagnetic transmission characteristics by bringing their effective dielectric constant close to zero. In materials with near-zero dielectric constant (ENZ), the effective propagation constant approaches zero during electromagnetic wave propagation, resulting in significant compression of the electromagnetic field phase accumulation. This allows for unconventional energy transfer phenomena under certain geometric configurations. Early theoretical work has shown that filling narrow channels or curved waveguides with such near-zero dielectric response materials significantly enhances energy transfer through the channels—a phenomenon known as "supercoupling" or tunneling—and, under ideal conditions, allows for energy transfer almost unaffected by channel geometry. This theoretical research indicates that, under specific conditions, near-zero dielectric materials can effectively couple electromagnetic energy from free space within the transmission region, minimizing reflection and thus significantly improving energy transfer efficiency at the free space-ENZ interface. Although these studies reveal the potential to improve transmission characteristics using near-zero response materials, current techniques often rely on introducing resonant cavities or high-Q modes to achieve impedance matching. While such resonant mechanisms can improve transmission in narrow frequency bands, they significantly increase the loss of electromagnetic energy within the material and limit frequency adaptability.

[0004] Besides resonance mechanisms, existing technologies have proposed multilayer dielectric matching structures and metasurfaces to achieve impedance matching. These methods reduce reflection and improve transmission efficiency by gradually transitioning dielectric parameters. However, such structures generally require precise material rendering and complex micro / nano fabrication techniques, and significant performance fluctuations still occur under different incident angles or frequencies. Furthermore, these existing methods often focus on utilizing a single physical phenomenon, such as relying solely on phase matching of a single layer or impedance adjustment of a single interface, lacking a systematic solution that can coordinate electromagnetic energy transfer from both phase accumulation and impedance matching dimensions at the overall structural level. This results in poor stability and robustness of transmission efficiency when incident conditions or structural parameters change, thus failing to meet the practical engineering requirements for high-efficiency, wide-bandwidth, and wide-incident-angle transmission devices.

[0005] Therefore, a new structural design method is still urgently needed to achieve efficient energy coupling and transmission between free space and transmission region by controlling the equivalent electromagnetic response of the transmission region as a whole, without relying on resonance enhancement, in order to solve the core technical problems of insufficient impedance matching, limited transmission efficiency and poor frequency stability in existing transmission structures. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a perfectly coupled secure information transmission device based on a multilayer nanofilm structure filled with a dielectric sheet.

[0007] This invention is achieved as follows: a perfectly coupled secure information transmission device based on a multilayer nanofilm structure filled with a dielectric sheet includes:

[0008] Input area, transmission area, and output area;

[0009] The input and output areas are free space;

[0010] The transmission region consists of a three-layer "sandwich" structure, which is formed by two layers of non-magnetic ENZ dielectrics wrapped around a thin dielectric plate; the thickness of ENZ dielectric 1 is l1, and the thickness of ENZ dielectric 2 is l2; the thickness of the dielectric plate is d, and the relative permittivity of the dielectric plate is... A plane wave with a magnetic field (H) along the y-axis is incident from the input region.

[0011] Furthermore, the equivalent transmission region is configured to form a transmission state in which the propagation phase is insensitive to changes in geometric dimensions within the target operating frequency band, so that the phase accumulation of electromagnetic waves within the transmission region is mainly determined by the equivalent dielectric response rather than the physical length.

[0012] This scheme breaks through the design limitations of traditional optical transmission structures where phase is strictly dependent on geometric dimensions. By using the equivalent dielectric response to dominate the phase evolution mechanism, the device can maintain stable phase control capability at the subwavelength scale, significantly improving the device's tolerance to manufacturing tolerances and structural scaling, and has obvious advantages in engineering applicability.

[0013] Furthermore, the equivalent medium regions of the transmission region form an overall compensation relationship at the transfer matrix level, so that the reflection components at the free space interface cancel each other out after multiple propagations, thereby achieving high transmission output under non-resonance conditions.

[0014] This scheme does not rely on cavity resonance or narrowband phase matching. Instead, it suppresses interface reflection through the overall compensation mechanism of the transfer matrix, effectively overcoming the problems of narrow bandwidth and poor stability of traditional resonant devices, and achieving more tolerant and stable supercoupled transmission characteristics.

[0015] Furthermore, the electromagnetic parameters of the equivalent transmission region are determined through a closed-loop adjustment method, so that the transmission performance converges to a preset transmission state after multiple rounds of parameter updates.

[0016] By introducing a closed-loop adjustment mechanism, device design is transformed from a one-time parameter setting process into an iterative optimization process. This not only improves the adaptability to environmental disturbances and parameter deviations, but also significantly enhances the consistency and repeatability of device performance, demonstrating technological progress at the system-level design level.

[0017] Furthermore, the transfer matrix of the ENZ medium can be expressed as:

[0018]

[0019] Here, k0 is the wavenumber in free space. p1 is the relative permittivity of ENZ medium 1. Vacuum wave impedance ,Right now ; .

[0020] Furthermore, the transfer matrices of the thin dielectric plate and the ENZ dielectric 2 can be expressed as follows:

[0021]

[0022]

[0023] Where εrd is the relative permittivity of the thin dielectric substrate, and pd is; .

[0024] Furthermore, the transfer matrix of the three-layer "sandwich" structure can be expressed as:

[0025]

[0026] Considering that both sides of the above structure are free space, the transmission coefficient on the transmission surface of the structure can be expressed as:

[0027] .

[0028] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0029] This invention proposes a sandwich structure composed of an ENZ dielectric filled with a dielectric sheet. By appropriately selecting parameters, this structure achieves perfect impedance matching at the incident interface and exhibits ideal supercoupling characteristics. Notably, by adjusting the thickness of the intermediate sheet, the phase difference between the incident and transmitted waves can be adjusted to 0° or 180°. Based on this design, a novel optical supercoupling transmission device was realized using an Ag / silicon carbide multilayer periodic thin film structure at a wavelength of 430 nm. Full-wave simulation results show that the device possesses accurate frequency selectivity and excellent phase reversal performance. Finally, utilizing these characteristics, a process for information encryption / decryption suitable for the field of information security was designed.

[0030] Simultaneously, by employing a multilayer Ag / silicon carbide nanofilm structure at a wavelength of 430 nm to achieve an equivalent ENZ medium, a perfectly coupled secure information transmission device based on a multilayer nanofilm structure filled with a dielectric sheet was designed. Finally, using this device, an information encryption / decryption process suitable for the field of information security was designed. This work has significant guiding significance for the development of novel high-performance optical transmission devices. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a sandwich structure composed of ENZ dielectric with embedded dielectric sheets, provided in an embodiment of the present invention.

[0032] Figure 2 The figure provided by the embodiment of the present invention shows the calculation results of the transmission coefficient and transmission phase of the structure as a function of the incident wave frequency under the above parameter conditions.

[0033] Figure 3 The embodiment of the present invention (a) shows the magnetic field distribution in the proposed structure, while Figure 3 (b) shows the electric field distribution in the proposed structure.

[0034] Figure 4 This is a lossless transmission diagram provided in an embodiment of the present invention.

[0035] Figure 5The diagram provided in this embodiment of the invention shows the relationship between the transmission coefficient and the transmission phase difference of the proposed structure as a function of frequency.

[0036] Figure 6 This is a simulation result diagram provided in the embodiment of the present invention.

[0037] Figure 7 The offset l3 shown in (a) is provided in the embodiment of the present invention. (b) shows the calculation results of the transmission coefficient and transmission phase difference of the proposed structure under different offsets.

[0038] Figure 8 This is a schematic diagram illustrating the equivalent ENZ characteristics of a 430nm band silver / silicon carbide multilayer periodic structure thin film provided in this embodiment of the invention. (a) The improved multilayer structure of the silver / silicon carbide multilayer periodic structure thin film is equivalent to an isotropic electromagnetic zero medium. (b) A unit of the modified multilayer alternating Ag / SiC thin film structure. (c) Part 1 of the unit is the initial structure rotated 90° around the y-axis. (d) Part 2 of the unit is the initial structure rotated 90° around the x-axis.

[0039] Figure 9 The magnetic field distribution at different wavelengths is shown in the embodiments of the present invention after the multilayer Ag / silicon carbide thin film structure is filled with a dielectric sheet (εrd=37). (a) The incident wave is completely transmitted through the above structure at a wavelength of 430nm. (b), (c) and (d) The incident waves are reflected by the above structure at wavelengths of 425nm, 435nm and 440nm, respectively.

[0040] Figure 10 The embodiments of the present invention provide a multilayer Ag / silicon carbide thin film structure with dielectric sheets of different thicknesses (d / λ0) for magnetic field distribution. (a) Electromagnetic waves are transmitted entirely through a sandwich structure composed of ENZ dielectrics embedded with dielectric sheets. When d = 0.0084λ0, the phase difference between the incident wave and the transmitted wave is zero, and the wavelength is 430 nm. (b) The ENZ dielectric is replaced by a multilayer Ag / SiC film structure. (c) The d value is adjusted to 0.0168λ0 at a wavelength of 430 nm. (d) The d value is adjusted to 0.0252λ0 at a wavelength of 430 nm.

[0041] Figure 11 This is a diagram of a novel multi-optical-path signal encryption transmission provided by an embodiment of the present invention.

[0042] Figure 1 In Chinese: 1. Input area; 2. Transmission area; 3. Output area. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0044] In the engineering applications of existing optical information transmission and coupling devices, common problems are mainly reflected in the low energy coupling efficiency caused by high reflectivity interfaces, the structural size being limited by the operating wavelength, and the phase distortion and bandwidth limitation caused by impedance mismatch of different media. Especially when achieving efficient and stable information transmission at the subwavelength scale, traditional dielectric or equivalent metamaterial structures often require complex gradient designs or fine parameter tuning, resulting in narrow manufacturing windows and insufficient robustness, making it difficult to meet the industrialization requirements of integrated photonic devices for high consistency and scalability.

[0045] To address the aforementioned technical bottlenecks, this solution introduces an ENZ dielectric, equivalent to multiple nanofilms, forming a sandwich-type transmission region structure with a thin dielectric substrate. The core idea of ​​this structure is not simply to improve the performance of a single material, but rather to manipulate the equivalent electromagnetic parameters to achieve a near-zero effective dielectric response in the transmission region within the operating frequency band, thereby macroscopically reshaping the propagation mechanism of electromagnetic waves within the device. Because the ENZ dielectric exhibits significant phase stretching under near-zero dielectric constant conditions, the phase change of the incident plane wave in this region is significantly compressed, laying the foundation for the subsequent synergistic coupling of the multilayer structure.

[0046] In the actual operation, a plane wave incident from free space enters the transmission region in a transverse magnetic mode along the y-direction, initially interacting with the first layer of non-magnetic ENZ medium. At this point, the equivalent wave impedance of the ENZ medium and the free space impedance form a controllable matching relationship within the transfer matrix framework, effectively suppressing interface reflections and guiding electromagnetic energy into the sandwich structure in a quasi-static manner. Unlike conventional high-refractive-index media, this process does not rely on geometric resonance but originates from the inherent electromagnetic boundary response characteristics of the ENZ material.

[0047] Subsequently, the electromagnetic wave undergoes a redistribution of energy and phase within the thin dielectric substrate. The finite thickness of the dielectric substrate and its relative permittivity together determine the local propagation constant, allowing the phase compressed in the ENZ layer to unfold in a predictable manner within that layer. This process does not occur independently but rather forms a synergistic constraint with the transmission characteristics of the ENZ media on both sides, adjusting the amplitude and phase relationships of each matrix element in the transmission matrix as a whole, thus creating conditions for achieving overall transmission enhancement.

[0048] As the electromagnetic wave continues to propagate to the second ENZ layer, its propagation state has been pre-modulated by the preceding structure. This ENZ layer plays a symmetrical compensation role in the sense of the transfer matrix. Through the selection of its thickness and equivalent dielectric parameters, the overall transfer matrix of the three-layer sandwich structure tends to an ideal form under free-space boundary conditions. As a result, the numerator and denominator of the transmission coefficient achieve coordinated matching in amplitude and phase, and the system as a whole exhibits supercoupling characteristics close to unity transmission without relying on loss compensation or active control mechanisms.

[0049] This device features a collaborative design of multiple equivalent dielectrics at the transfer matrix level: the ENZ dielectric handles phase compression and impedance adjustment, while the thin dielectric substrate provides propagation modulation and structural stabilization. These three components, under free-space boundary conditions, form an overall electromagnetic response optimization mechanism. This mechanism overcomes the dependence of traditional optical couplers on size and frequency sensitivity, providing an engineeringable technical path for achieving high-tolerance, high-consistency supercoupled optical information transmission, and possesses promising prospects for integrated applications.

[0050] In the two-dimensional (2D) case, Figure 1 The area is divided into three regions from left to right: input region 1, transmission region 2, and output region 3. Input region 1 and output region 2 are free space. Transmission region 3 consists of a three-layer "sandwich" structure, which is formed by two layers of non-magnetic ENZ dielectric wrapped around a thin dielectric plate. The thickness of ENZ dielectric 1 is l1, and the thickness of ENZ dielectric 2 is l2. The thickness of the dielectric plate is d, and the relative permittivity of the dielectric plate is... A plane wave with a magnetic field (H) along the y-axis is incident from the input region. Typically, due to impedance mismatch at the incident surface, the electromagnetic wave cannot completely pass through the transmission region to reach the output region because reflection occurs. Here, the transfer matrix method is used for quantitative analysis. Figure 1 The reflection and transmission characteristics of the structure.

[0051] In the two-dimensional case, the structure is divided into input region 1, transmission region 2, and output region 3 along the propagation direction z-axis. Input region 1 and output region 3 are both free air spaces. Transmission region 2 consists of a three-layer sandwich structure composed of "ENZ dielectric 1 – dielectric plate – ENZ dielectric 2". The incident electromagnetic wave is a plane wave, with its magnetic field component H polarized along the y-direction, its electric field component E polarized along the x-direction, and its wave vector propagating along the z-direction.

[0052] Because ENZ (Epsilon-Near-Zero) media have a near-zero dielectric constant near the operating frequency, their equivalent impedance and phase constant differ significantly from those of free space. This results in electromagnetic waves exhibiting an approximately uniform phase distribution and enhanced amplitude characteristics within the ENZ layer. When an incident wave enters the transmission region from the input region, direct coupling from free space into a conventional medium would cause strong reflections due to impedance mismatch. However, the near-zero dielectric properties of the ENZ medium effectively modulate the equivalent input impedance at the interface, thereby suppressing interface reflections and enhancing transmission coupling.

[0053] A thin dielectric plate (thickness d, relative permittivity) located between two ENZ dielectric layers This structure serves to compensate for phase and modulate energy. By appropriately selecting the ENZ dielectric thicknesses l1 and l2 and the dielectric plate parameters, the three-layer structure satisfies the overall equivalent impedance matching and phase matching conditions at the target frequency, thereby forming a low-reflection, high-transmission equivalent transmission channel within the transmission region. After undergoing superimposed interference from multiple interface reflections and transmissions within this channel, the reflected waves cancel each other out, while the transmitted waves coherently enhance, ultimately achieving high-efficiency transmission output.

[0054] Therefore, this structure achieves precise control over the reflection and transmission characteristics of electromagnetic waves through the synergistic mechanism of "ENZ impedance modulation + dielectric layer phase compensation", thereby overcoming the problem of transmission limitation caused by impedance mismatch at the traditional dielectric interface and improving the transmission efficiency of electromagnetic waves in subwavelength structures.

[0055] The transfer matrix of the ENZ medium can be expressed as:

[0056]

[0057] Here, k0 is the wavenumber in free space. η is the relative permittivity of ENZ medium 1, p1 is η, and η0 is the vacuum wave impedance. ,Right now .

[0058] Similarly, the transfer matrices of the thin dielectric plate and ENZ dielectric 2 can be expressed as follows:

[0059]

[0060]

[0061] in, Let be the relative permittivity of the thin dielectric substrate, and pd be .

[0062] The transfer matrix of the three-layer "sandwich" structure can be expressed as follows:

[0063]

[0064] Considering that both sides of the above structure are free space, the transmission coefficient on the transmission surface of the structure can be expressed as:

[0065]

[0066] in, and These are the permittivity and permeability of free space, respectively.

[0067] Let it represent The value is 37. Based on the comprehensive optimization calculation results of Equation 5, it is concluded that when both l1 and l2 are 0.75λ0 and d is 0.084λ0, the transmission coefficient (T) of this structure is 1, and the transmission phase is 0. Here, λ0 is the wavelength of the incident wave in free space. Figure 2 The calculation results show the transmission coefficient and transmission phase of the structure as a function of the incident wave frequency under the above parameter conditions, indicating that the structure is transparent to electromagnetic waves under constrained conditions. If the constraints change, this state will disappear rapidly, reflecting the excellent frequency selectivity of the structure.

[0068] The simulation is performed on a rectangular two-dimensional region, with the operating wavelength of the incident plane electromagnetic wave being λ0, and the constraints are as follows: Figure 3 As shown. Figure 3 (a) shows the magnetic field distribution in the proposed structure, while Figure 3 (b) shows the electric field distribution in the proposed structure, both of which pass smoothly and completely through the structure, indicating that electromagnetic energy can also be distributed as... Figure 4 The transmission is lossless as shown.

[0069] Investigating the effect of parameter variations on the electromagnetic transmission performance of the proposed structure: Figure 5 The relationship between the transmission coefficient and transmission phase difference of the proposed structure as a function of frequency is shown, indicating that the structure exhibits periodic resonance with varying wavelengths. Total transmission occurs at the resonance moment. The resonance period is nd / λ0 (n=1,2,3,4...). Interestingly, when n is odd, the transmission phase difference of the structure is 0; while when n is even, the transmission phase difference is π, a fact already established by... Figure 6 The simulation results were confirmed.

[0070] The displacement of the dielectric substrate from the center of the waveguide is defined as follows: Figure 7 The offset l3 is shown in (a). Figure 7(b) shows the calculated transmission coefficient and transmission phase difference of the proposed structure under different offsets, indicating that the center of the ENZ medium is the optimal position for filling the medium plate.

[0071] Design of optically fully transparent devices with multilayer film structures: First, an equivalent ENZ with optical isotropy should be achieved. In previous work, an effective isotropic ENZ medium at a wavelength of 430 nm was achieved by using a multilayer Ag / silicon carbide nanofilm structure. In this work, an optically perfect transmission device was successfully designed at a wavelength of 430 nm by filling the dielectric plate f with the above structure.

[30] The multilayer Ag / silicon carbide nanofilm structure with a rectangular cross-section is shown in the figure. Figure 8 As shown. At a wavelength of 430 nanometers ( Under these conditions, the relative permittivity and permeability of silver (white thin film) are both [value missing]. , The relative permittivity and permeability of silicon carbide (red thin film) are both... , .like Figure 8 As shown in (c), a single unit of the multilayer Ag / silicon carbide structure

[30] comprises three parts: the first part is a periodic stack of silver and silicon carbide films rotated 90° along the y-axis; the second part is a similar alternating stack rotated 90° along the x-axis; and the third part is an independent silicon carbide layer. Their respective thicknesses, dpt1, dpt2, and dpt3, satisfy dpt1 = dpt2 = 0.388dpt3, and are all much smaller than the operating wavelength

[30] .

[0072] Figure 8 —The 430nm ENZ dielectric is designed using a multilayer Ag / silicon carbide periodic thin film structure.

[0073] (a) An improved multilayer structure of silver / silicon carbide periodic thin film is equivalent to an isotropic electromagnetic null medium. (b) A unit cell of a modified multilayer alternating Ag / SiC thin film structure. (c) Part 1 of the unit cell is the initial structure rotated 90° about the y-axis. (d) Part 2 of the unit cell is the initial structure rotated 90° about the x-axis.

[0074] Let w0 be the length of the cross-section of the structure along the z-axis, and h0 be the length of the cross-section of the structure along the x-axis. Here, w0 = 2.83λ0, h0 = 0.885λ0.

[0075] like Figure 8 As shown in (a), the equivalent relative permittivity of the proposed structure is given by the modified equivalent dielectric theory.

[0076]

[0077] It can be regarded as an equivalent isotropic ENZ medium.

[0078] Numerical Analysis: This simulation was conducted using COMSOL full-wave simulation over a rectangular two-dimensional region. The incident plane electromagnetic wave from the left has a working wavelength of 430 nm (λ0). Two sets of multilayer Ag / silicon carbide thin film structures are placed at the center of the rectangular two-dimensional region. The width (along the z-axis) of each multilayer Ag / silicon carbide thin film structure is 0.075λ0. A dielectric sheet with a width of 0.0084λ0 and a relative permittivity of 37 is placed between the two sets of multilayer structures. Figure 9 As shown in (a), the incident wave can still completely pass through the structure, confirming that the multilayer Ag / silicon carbide thin film structure is equivalent to an ENZ medium in the 430 nm wavelength range. However, when the wavelength of the incident wave is slightly changed (e.g., 425 nm, 435 nm, 440 nm), the structure immediately exhibits obvious reflection, as shown in (a). Figure 9 As shown in (b), (c) and (d), Figure (9) demonstrates that the above structure has sensitive frequency selectivity, providing a novel and convenient method for the design of optical frequency selective devices.

[0079] Next, the width of the dielectric sheet was adjusted to observe the phase manipulation characteristics of the above structure, such as... Figure 10 As shown. Figure 10 Other parameters of the structure remain unchanged. Figure 10 (a) and (b) show the full-wave simulation results using a monolithic homogeneous ENZ dielectric and a multilayer equivalent ENZ structure, respectively. In this case, the dielectric sheet width is 0.0084 λ0, indicating that they have identical electromagnetic scattering effects, with a phase difference of 0 degrees between the transmitted and incident waves. When the dielectric sheet width is adjusted from 0.0084 λ0 to 0.0168 λ0, the wave still passes completely through the structure, but as... Figure 10 As shown in (c), the phase difference between the transmitted wave and the incident wave is 180 degrees. The width is further increased to 0.0252λ0. This provides a new approach to optical polarization manipulation.

[0080] Based on the anti-phase perfect transmission characteristics of the above structure, a novel multi-path signal encryption transmission scheme is proposed. When two signals with the same frequency and in phase (carrying information 1 and information 2 respectively) enter the structure, their phases are simultaneously reversed by 180 degrees. These two signals are then merged into a single propagating signal. Before incidence, the positive phase (red bar) of the signal represents code "1," and the negative phase (blue bar) represents code "0," but the phase meanings of the transmitted waves are completely opposite, which is equivalent to information encryption. When the signal reaches the receiving end, it is again split into two beams and undergoes phase reversal recovery through the structure (equivalent to decryption). Finally, the two recovered signals are merged and input into the receiving end, as shown below. Figure 11As shown.

[0081] In a specific embodiment, the optically perfectly coupled information transmission device of the present invention operates under free-space excitation conditions. The device as a whole includes, sequentially along the electromagnetic wave propagation direction, an input region, an equivalent transmission region, and an output region, wherein both the input and output regions are in free-space environments. The incident electromagnetic wave enters the equivalent transmission region from the input region in a transverse magnetic mode, with its magnetic field direction oriented along the y-axis. The incident parameters of the electromagnetic wave are determined by the free-space wavenumber and boundary conditions.

[0082] The equivalent transmission region is considered as a single transmission unit at the system level. Its electromagnetic response is not determined by a single material property, but rather by the coordinated formation of multiple equivalent dielectric regions arranged sequentially in the propagation direction. The system first constructs at least one phase-compression modulation region within the transmission region. This region is configured with equivalent dielectric parameters to exhibit a near-zero equivalent dielectric response within the target operating frequency band, thereby significantly reducing the propagation constant within this region. Consequently, when the incident electromagnetic wave propagates within this region, its phase accumulation rate is compressed, significantly reducing the sensitivity of the propagation phase to changes in geometric thickness, thus providing stable input conditions for subsequent modulation.

[0083] After phase compression, the electromagnetic wave enters a propagation unfolding region with a finite non-zero equivalent dielectric response. This region is used to remodulate the electromagnetic field distribution under the preceding phase-compression state, causing the electromagnetic energy to unfold again in the propagation direction. This unfolding process is constrained by the output field distribution of the phase-compression region, avoiding local reflections or field distortions, thereby ensuring the continuous transmission of the field quantity throughout the entire propagation region.

[0084] Subsequently, the electromagnetic wave continues into another phase modulation region. The equivalent electromagnetic parameters of this region are designed in conjunction with those of the aforementioned phase compression region to compensate for the phase and impedance deviations introduced during propagation. Through the sequential action of these multiple regions, the system forms an overall compensation relationship at the transfer matrix level, causing the total equivalent wave impedance in the transmission region to gradually approach the free-space impedance, thereby suppressing reflection at the interface between the transmission region and free space.

[0085] In the actual implementation, the equivalent dielectric parameters and propagation lengths of each equivalent medium region are not set in isolation, but are jointly determined through overall transfer matrix analysis. The system first sets transmission coefficient constraints based on free space boundary conditions and target transmission performance, and then adjusts the parameters of each region in reverse based on these constraints to ensure that the overall transfer matrix satisfies the transmission extremum condition. This parameter determination process can be achieved through parameter scanning, equivalent model estimation, or numerical optimization, without being limited to a specific mathematical algorithm.

[0086] To improve the device's adaptability to manufacturing errors and environmental disturbances, a multi-round iterative mechanism can be introduced into the parameter determination process. The system calculates the transmission response under the current parameter combination, feeds back the deviation information from the target transmission state to the parameter update module, and corrects the equivalent medium parameters or propagation length configuration accordingly until the overall transmission performance converges. Through this closed-loop adjustment, the device can stably achieve perfectly coupled optical information transmission under non-resonant conditions.

[0087] Through this implementation method, the present invention uses phase compression, propagation unfolding and impedance matching as the core mechanism to construct an executable and iterative equivalent transmission path, thereby achieving system-level synergistic enhancement rather than simple material or structural superposition.

[0088] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An information transmission device, characterized in that, The device constructs an equivalent transmission region under free-space excitation conditions, so that the incident electromagnetic wave simultaneously satisfies the near-zero phase accumulation effect and impedance matching condition in the equivalent transmission region, thereby achieving near-full transmission of energy super-coupled transmission without relying on resonance enhancement. The equivalent transmission region is a holistic structure in terms of the transfer matrix, and its total transfer matrix forms an extreme state of the transmission coefficient under the constraints of free space boundary conditions.

2. The information transmission device as described in claim 1, characterized in that, The near-zero phase accumulation effect arises from the fact that at least a portion of the equivalent transmission region exhibits an electromagnetic response state with a significantly reduced propagation constant, thereby weakening the dependence of the propagation phase on the geometric propagation length.

3. The information transmission device as described in claim 1, characterized in that, The impedance matching is achieved by the overall control of the equivalent wave impedance of the equivalent transmission region, so that the interface reflection between the equivalent transmission region and the free space on both sides is canceled at the overall transmission matrix level.

4. The information transmission device as described in claim 1, characterized in that, The extreme state of the transmission coefficient is characterized by the transmission coefficient being close to a unit value within the target operating frequency band.

5. The information transmission device as described in claim 1, characterized in that, The equivalent transmission region is robust to changes in incident phase and geometric parameters, making the transmission characteristics insensitive to these changes.

6. An equivalent sandwich structure for achieving high-transmission information transmission, characterized in that, The structure consists of multiple equivalent medium regions arranged in series along the propagation direction, including at least one region that undertakes phase compression modulation and one region that undertakes propagation expansion modulation. The equivalent medium regions form a compensation relationship in the sense of the overall transfer matrix, so that the sandwich structure exhibits a near-unit transmission response under free space excitation.

7. The equivalent sandwich structure as described in claim 6, characterized in that, The equivalent medium region that performs phase compression modulation exhibits an electromagnetic response state with a significantly reduced propagation constant.

8. The equivalent sandwich structure as described in claim 6, characterized in that, The equivalent medium region that performs the propagation and expansion modulation function exhibits a finite non-zero propagation constant state, which is used to remodulate the electromagnetic field distribution under the phase compression state.

9. The equivalent sandwich structure as described in claim 6, characterized in that, The geometric thickness and electromagnetic parameters of each equivalent medium region together participate in the construction of the overall transmission matrix to satisfy the extreme value condition of the transmission coefficient.

10. The equivalent sandwich structure as described in claim 6, characterized in that, The compensation relationship is manifested in the fact that the phase compression modulation and propagation spread modulation simultaneously form a canceling or synergistic state in both the phase response and impedance response dimensions.

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