An optical gain-based super-scattering and zero-forward-scattering synergistic modulation system and method

Abstract

The application discloses a kind of based on optical gain's ultra-scattering and zero forward scattering synergic control system and method, it is related to optical scattering enhancement technical field.Method includes constructing space rectangular coordinate system, let cylindrical scatterer be placed vertically along z axis, transverse magnetic wave is emitted by emission device along x axis incidence, emission device emits transverse magnetic wave, let transverse magnetic wave and cylindrical scatterer interact, total magnetic field in the free space of cylindrical scatterer coordinate is detected using detection device, based on total magnetic field, scattering coefficient of different scattering channels of cylinder and total scattering cross section are obtained, based on scattering coefficient and total scattering cross section, key parameters for controlling scattering intensity and directionality are obtained, scattering pattern is obtained by adjusting key parameters of cylindrical scatterer.The application provides a new way for designing advanced optical devices applied in subwavelength antenna, optical communication, radar sensing and imaging and other fields.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical scattering enhancement technology, and in particular to a system and method for synergistic regulation of ultra-scattering and zero-forward scattering based on optical gain. BACKGROUND

[0002] Light scattering is one of the core phenomena of electromagnetic wave interaction with matter. At subwavelength scale, the scattering cross-section enhancement (ultra-scattering) and directional regulation (such as zero-forward scattering) of scatterers are crucial to the performance of optical devices.

[0003] Ultra-scattering technology can significantly enhance the scattering cross-section by exciting multipole resonances (such as electric dipole, magnetic dipole, and higher-order modes) of subwavelength scatterers, which has important potential in optical sensing, nanoantennas, and high-resolution imaging. However, existing researches mainly focus on the enhancement of scattering intensity, and pay little attention to the fine regulation of scattering directionality (such as forward, side, or back scattering distribution). For example, in ultra-scattering design, although the synergistic excitation of multipole resonances can break through the scattering cross-section limit, the asymmetric radiation pattern often leads to residual forward scattering energy (more than 30%), which limits the performance of directionally sensitive devices (such as reduced antenna radiation efficiency and elevated imaging background noise).

[0004] Currently, a few attempts to combine ultra-scattering and directional regulation mainly adjust the multipole phase difference through passive structural design (such as breaking the geometric symmetry or stacking dielectric layers), but due to material loss and mode competition, it is difficult to meet the requirements of ultra-scattering intensity and directional suppression. In addition, although the introduction of active regulation means (such as externally driven tunable materials) can dynamically modulate the scattering direction, it still maintains a large energy residue due to high system complexity, harsh implementation conditions, and the inability to completely eliminate forward or backward scattering light. It is worth noting that the application of traditional multi-layer scattering structures (such as boron nitride) to achieve ultra-scattering can compensate for loss and enhance scattering intensity, but it easily causes multi-mode coupling instability or spontaneous radiation interference, which further exacerbates the difficulty of directional regulation. Therefore, how to achieve high-precision regulation of scattering directionality (such as zero-forward, unidirectional side, or customized angular distribution) while maintaining the performance of ultra-scattering remains a technical bottleneck that has not been broken through in the field of subwavelength optical devices.

[0005] Therefore, to solve the existing difficulties in the prior art, a system and method for synergistic regulation of ultra-scattering and zero-forward scattering based on optical gain are provided, which is a problem that needs to be solved by those skilled in the art. SUMMARY

[0006] Therefore, the application provides an optical gain-based super-scattering and zero-forward scattering synergic regulation system and method, which provides a new way for designing advanced optical devices applied in the fields of sub-wavelength antennas, optical communication, radar sensing and imaging.

[0007] In order to achieve the above object, the application adopts the following technical scheme:

[0008] The application provides an optical gain-based super-scattering and zero-forward scattering synergic regulation system, which comprises a scattering body, a transmitting device and a detecting device.

[0009] The scattering body is a vertically placed adjustable-parameter non-magnetic gain medium cylindrical scattering body.

[0010] The transmitting device transmits a transverse magnetic wave perpendicular to the cylindrical scattering body, so as to interact with the cylindrical scattering body.

[0011] The detecting device is used for measuring the far-field radiation intensity and the near-field magnetic field distribution of the scattering at 360° around the cylindrical scattering body.

[0012] Optionally, the scattering body is infinitely extended along the vertical direction, and the imaginary part of the complex relative permittivity is negative.

[0013] Optionally, the transverse magnetic wave transmitted by the transmitting device is a transverse magnetic plane wave, and the polarization direction is parallel to the incident plane.

[0014] The application further provides an optical gain-based super-scattering and zero-forward scattering synergic regulation method, which is applied to the above-mentioned optical gain-based super-scattering and zero-forward scattering synergic regulation system and comprises the following steps.

[0015] A space rectangular coordinate system is constructed, the cylindrical scattering body is placed vertically along the z axis, and the transverse magnetic wave transmitted by the transmitting device is incident along the x axis.

[0016] The transmitting device transmits the transverse magnetic wave, so that the transverse magnetic wave interacts with the cylindrical scattering body.

[0017] The detecting device is used for detecting the total magnetic field in the free space in the coordinate of the cylindrical scattering body.

[0018] Based on the total magnetic field, the scattering coefficients of different scattering channels of the cylindrical body and the total scattering cross section are obtained.

[0019] Based on the scattering coefficients and the total scattering cross section, the key parameters for controlling the scattering intensity and directivity are obtained.

[0020] The scattering diagram is obtained by adjusting the key parameters of the cylindrical scattering body.

[0021] Optionally, the total scattering cross section comprises the far-field radiation intensity obtained from each azimuthal scattering cross section, and the total scattering cross section is obtained by integrating the far-field radiation intensity.

[0022] Optionally, the key parameter is a scattering coefficient, which is obtained by adjusting the radius and relative dielectric constant of the cylindrical scatterer.

[0023] Compared with the prior art, the application provides an ultra-scattering and zero-forward scattering synergistic regulation system and method based on optical gain, which has the following beneficial effects: 1) the application realizes a new mechanism of one-way ultra-scattering by carefully designing the gain and size of the scatterer, which exceeds the single-channel scattering limit and realizes zero-forward scattering; 2) the application exceeds the single-channel scattering limit through the gain medium, low-order or high-order scattering channels, thereby significantly enhancing the scattering intensity, and in addition, the destructive interference between multiple channels eliminates the forward scattering light, thereby being able to effectively control the scattering direction; 3) the application further enhances the scattering intensity and improves the directivity by setting the participation of the high-order channel, thereby providing a more flexible and efficient way to control light-matter interaction; 4) the application provides a deeper understanding of the interaction between multiple scattering channels and gain media, and provides a new way for designing advanced optical devices applied in the fields of subwavelength antennas, optical communication, radar sensing and imaging. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the provided drawings.

[0025] Figure 1 A flow chart of the ultra-scattering and zero-forward scattering synergistic regulation method based on optical gain disclosed by the present application is shown in the figure.

[0026] Figure 2a A zero-order scattering cross section schematic diagram of single-channel ultra-scattering disclosed by the embodiment of the present application is shown in the figure.

[0027] Figure 2b A per-angle scattering cross section schematic diagram of single-channel ultra-scattering disclosed by the embodiment of the present application is shown in the figure.

[0028] Figure 2c A magnetic field distribution schematic diagram of single-channel ultra-scattering disclosed by the embodiment of the present application is shown in the figure.

[0029] Figure 3a A zero-order scattering cross section schematic diagram of the second type of Kerr scattering disclosed by the embodiment of the present application is shown in the figure.

[0030] Figure 3b A per-angle scattering cross section schematic diagram of the second type of Kerr scattering disclosed by the embodiment of the present application is shown in the figure.

[0031] Figure 3c A magnetic field distribution diagram of the second type of Kerr scattering disclosed by the embodiment of the present application;

[0032] Figure 4a A zero-order scattering cross-section diagram of Kerr super-scattering disclosed by the embodiment of the present application;

[0033] Figure 4b An angle-by-angle scattering cross-section diagram of Kerr super-scattering disclosed by the embodiment of the present application;

[0034] Figure 4c A magnetic field distribution diagram of Kerr super-scattering disclosed by the embodiment of the present application;

[0035] Figure 5 A forward-to-backward scattering cross-section ratio diagram of Kerr super-scattering disclosed by the embodiment of the present application in the parametric space of ;

[0036] Figure 6 A normalized zero-order scattering cross-section diagram of Kerr super-scattering disclosed by the embodiment of the present application in the parametric space of ;

[0037] Figure 7 A total scattering cross-section and each scattering channel scattering cross-section and forward-to-backward scattering cross-section ratio diagram of Kerr super-scattering disclosed by the embodiment of the present application;

[0038] Figure 8 A field distribution diagram of Kerr super-scattering under software simulation disclosed by the embodiment of the present application;

[0039] Figure 9 A scattering field distribution diagram of Kerr super-scattering disclosed by the embodiment of the present application;

[0040] Figure 10 A parameter diagram of high-order mode dominated Kerr super-scattering disclosed by the embodiment of the present application;

[0041] Figure 11 A channel scattering cross-section diagram of high-order mode dominated Kerr super-scattering disclosed by the embodiment of the present application;

[0042] Figure 12 A total scattering cross-section and full width at half maximum diagram of high-order mode dominated Kerr super-scattering disclosed by the embodiment of the present application. DETAILED DESCRIPTION

[0043] Clearly, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present application.

[0044] The application discloses an optical gain-based super-scattering and zero-forward-scattering synergistic regulation system, comprising a scatterer, a transmitting device and a detection device.

[0045] The scatterer is a vertically placed adjustable-parameter non-magnetic gain medium cylindrical scatterer.

[0046] The transmitting device transmits a transverse magnetic wave perpendicular to the cylindrical scatterer for interaction with the cylindrical scatterer.

[0047] The detection device is used for measuring the far-field radiation intensity and the near-field magnetic field distribution of the scattering at 360 degrees around the cylindrical scatterer.

[0048] Further, the scatterer is infinitely extended along the vertical direction, and the imaginary part of the complex relative permittivity is negative.

[0049] Further, the transverse magnetic wave transmitted by the transmitting device is a transverse magnetic plane wave, and the polarization direction is parallel to the incident plane.

[0050] An optical gain-based super-scattering and zero-forward-scattering synergistic regulation method, applied to the optical gain-based super-scattering and zero-forward-scattering synergistic regulation system, refers to Figure 1 The method comprises the following steps:

[0051] A spatial rectangular coordinate system is constructed, the cylindrical scatterer is placed vertically along the z-axis, and the transverse magnetic wave transmitted by the transmitting device is incident along the x-axis.

[0052] The transmitting device transmits a transverse magnetic wave, and the transverse magnetic wave interacts with the cylindrical scatterer.

[0053] The detection device is used for detecting the total magnetic field in the free space in the cylindrical scatterer coordinate.

[0054] Based on the total magnetic field, the scattering coefficients of different scattering channels of the cylindrical body and the total scattering cross section are obtained.

[0055] Based on the scattering coefficients and the total scattering cross section, key parameters for controlling scattering intensity and directivity are obtained.

[0056] By adjusting the key parameters of the cylindrical scatterer, a scattering diagram is obtained.

[0057] Further, the positive Incidence of axis-propagating transverse-magnetic (TM, transverse-magnetic or p-polarized) plane waves. For a two-dimensional subwavelength scatterer in a uniform environment with refractive index n in a passive system, the maximum scattering cross section of a single channel cannot exceed where is the wavelength in free space. is the single-channel scattering limit in a two-dimensional coordinate system, setting the radius to r and the relative permittivity to According to electromagnetic wave theory, the total magnetic field in free space in cylindrical coordinates The expression is:

[0058] (1),

[0059] where, is the wave number in free space, and are the m-th order of the first kind Hankel function and Bessel function, respectively. is the polar coordinate with the origin as the center. The parameter S m , the scattering coefficient of the m-th scattering channel, can be analytically solved by matching the boundary conditions, and the expression is:

[0060] (2).

[0061] Further, the total scattering cross section includes the far-field radiation intensity obtained by the scattering cross section characterized by each azimuthal angle, and the total scattering cross section is obtained by integrating the far-field radiation intensity, and the expression is:

[0062] (3),

[0063] where the scattering cross section from a single m-th channel , and the total scattering cross section of each azimuthal angle The corresponding expression is:

[0064] (4),

[0065] (5),

[0066] where represents the angle between the wave vector of the incident wave and the wave vector of the scattered wave, is the reflection coefficient.

[0067] Further, the key parameter is the scattering coefficient S m , which is obtained by adjusting the radius r and the relative permittivity of the cylindrical scatterer.

[0068] In one embodiment, starting from the conceptual illustration of single-channel hyper-scattering and second-order Kerr scattering, the single-channel hyper-scattering is divided into Figures 2a-2c and Figures 3a-3c From the conceptual illustration, it can be found that the single-channel hyper-scattering enhances the intensity of scattering, so that a certain scattering channel (in this case, the zero-order channel) exceeds the single-channel scattering limit; and the second-order Kerr scattering controls the direction of scattering, in this case, the second-order Kerr scattering eliminates the forward scattering light.

[0069] Based on the conceptual illustration of Kerr hyper-scattering, the optimized relative permittivity and scattering body radius are and , Figure 4a which indicates that when the incident wave is incident on the optimized scattering body, Kerr-hyper-scattering occurs, and the scattering cross section of the m=0 channel exceeds the single-channel scattering limit, while Figure 4b shows the disappearance of the forward scattering light. The schematic diagram of the magnetic field distribution of Kerr hyper-scattering is shown in Figure 4c .

[0070] From equation (2), it is noted that is a function of the relative permittivity and a function of the radius From equations (3)-(5), the conditions for achieving single-channel hyper-scattering and second-order Kerr scattering depend on S m . Therefore, and r provide two degrees of freedom to achieve Kerr-hyper-scattering. Based on this, the relationship between the second-order Kerr scattering and the hyper-scattering is found in the parameter space of . The relative permittivity , is set to 3, as shown in Figure 5 , the parameter space of based on is drawn. The second-order Kerr scattering directly corresponds to the parameter condition to be achieved , which is represented by the blue area in Figure 5 . As shown in Figure 6 , the parameter space of based on is drawn, and the parameter condition for hyper-scattering to occur can be obtained. The black dashed line represents the single-channel scattering limit, and the parameter area to the right of the dashed line represents , where single-channel hyper-scattering phenomenon occurs. Through the combined analysis of Figure 5 and Figure 6 , the parameters for achieving Kerr hyper-scattering are determined corresponding to the parameter coordinates and . In this parameter setting, the second-order Kerr scattering and hyper-scattering can be achieved simultaneously.

[0071] The gain parameter of the scatterer is set to . Figure 7 The total scattering cross section and the scattering cross section of each angular momentum channel are shown under this parameter setting, and the horizontal dashed line represents the single-channel scattering limit. It can be clearly seen that when , the channel scattering cross section exceeds the single-channel scattering limit, reaching nearly 4.07 times. At the same time, the ratio of the forward and backward scattering cross sections reaches a minimum, approaching zero. COMSOL Multiphysics finite element software is used to numerically simulate the Kerr-Kocher super-scattering phenomenon under the optimized parameters. Figure 8 is a schematic diagram of the magnetic field distribution of the Kerr-Kocher super-scattering, as predicted earlier, the forward plane wave form is basically undisturbed after the plane wave is incident.

[0072] To further explore the role of each angular momentum channel on the scattering intensity and direction, the scattering field distribution and the scattering field distribution of each channel are drawn in Figure 9 . The total scattering field is obtained by linear superposition of the scattering field of each scattering channel by formula (3). The phase and amplitude of the forward direction of each channel scattering field are controlled by the gain parameter and the size parameter, and under the appropriate parameters, zero-forward super-scattering can be achieved after superposition.

[0073] The previous realization of Kerr-Kocher super-scattering is based on the super-scattering of the m=0 channel with gain coordination. As the size of the scatterer increases, the influence of higher-order scattering channels on the total scattering field intensity and direction becomes greater. In Figure 10 , still in the sub-wavelength range, increasing the radius of the scatterer cylinder can be found to appear different from the Kerr-Kocher super-scattering parameters in Figure 2a . In Figure 11 , the scattering cross section of each scattering channel of the Kerr-Kocher super-scattering of these different parameters is drawn, and it can be found that large size parameters induce the participation of higher-order channels. Due to the participation of high-order channels, compared with the Kerr-Kocher super-scattering of the channel, the total scattering cross section increases, and the full width at half maximum of the far-field radiation pattern decreases, and the directivity is further improved, as shown in Figure 12 .

[0074] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An optical gain-based synergistic modulation system of hyperdispersion and zero forward scattering, characterized in that, The system comprises a scatterer, a transmitting device and a detecting device; The scatterer is a vertically placed adjustable parameter non-magnetic gain medium cylindrical scatterer; The transmitting device transmits transverse magnetic wave perpendicular to the cylindrical scatterer for interaction with the cylindrical scatterer; The detecting device is used to measure the far-field radiation intensity scattered at 360° around the cylindrical scatterer and the near-field magnetic field distribution.

2. The system according to claim 1, wherein The scatterer is infinitely extended in the vertical direction, and the imaginary part of the complex relative permittivity is negative.

3. The system according to claim 1, wherein The transverse magnetic wave transmitted by the transmitting device is a transverse magnetic plane wave, and the polarization direction is parallel to the incident plane.

4. The method of synergistically regulating and controlling ultra-scattering and zero-forward scattering based on optical gain, applied to the system of synergistically regulating and controlling ultra-scattering and zero-forward scattering based on optical gain according to any one of claims 1-3, characterized in that, The method comprises the following steps: A spatial rectangular coordinate system is constructed, the cylindrical scatterer is placed vertically along the z-axis, and the transverse magnetic wave transmitted by the transmitting device is incident along the x-axis; The transmitting device transmits the transverse magnetic wave, and the transverse magnetic wave interacts with the cylindrical scatterer; The detecting device is used to detect the total magnetic field in the free space in the coordinate system of the cylindrical scatterer; Based on the total magnetic field, the scattering coefficients of different scattering channels of the cylindrical body and the total scattering cross section are obtained; Based on the scattering coefficients and the total scattering cross section, the key parameters for controlling the scattering intensity and directivity are obtained; By adjusting the key parameters of the cylindrical scatterer, the scattering pattern is obtained; The key parameter is the scattering coefficient Sm, which is obtained by adjusting the radius r and relative permittivity of the cylindrical scatterer The total scattering field is linearly superimposed by the scattering field of each scattering channel, the phase and amplitude of the forward direction of each channel scattering field are controlled by the gain parameters and size parameters, and after superposition, the zero-forward super-scattering is realized.

5. The method according to claim 4, wherein The total scattering cross section comprises the far-field radiation intensity obtained by the scattering cross section represented by each azimuth angle, and the total scattering cross section is obtained by integrating the far-field radiation intensity.

6. The method according to claim 4, wherein The key parameters are the scattering coefficients, which are obtained by adjusting the radius and relative permittivity of the cylindrical scatterer.

Images