An intracavity vortex wave generating device and control method

Abstract

This invention discloses an intracavity vortex wave generation device and control method, relating to the field of acoustic engineering technology. The intracavity vortex wave generation device includes a resonant cavity system and a nonlinear control component integrated within the resonant cavity system. The resonant cavity system consists of several resonant units forming a closed loop through a coupling structure to support the resonance of wave modes. The nonlinear control component is used to achieve adjustable non-reciprocal coupling between at least two resonant units. It is also used to generate vortex waves carrying orbital angular momentum by adjusting the coupling parameters of the non-reciprocal coupling. This avoids the complexity and losses of traditional methods that require additional beamforming elements or multiple active transducer arrays. By adjusting the coupling parameters of the non-reciprocal coupling to control the topological charge of the generated vortex waves, vortex waves with different topological charges can be generated, providing wider applicability for various applications.

Description

Technical Field

[0001] This invention relates to the field of acoustic engineering technology, specifically to an intracavity vortex wave generating device and control method. Background Technology

[0002] Vortex waves, carrying orbital angular momentum, have their helical wavefronts rotating about their propagation axis, and have been extensively studied in acoustics, microwaves, and optics. Due to their unique orbital angular momentum characteristics, vortex beams hold promise for wide applications in particle manipulation, object rotation, high-speed communication, and quantum information. To date, various methods for generating acoustic vortex beams have been developed, which can be categorized into passive and active methods based on their generation mechanism. In passive methods, a standard Gaussian beam is converted into a vortex beam using discrete elements such as helical phase plates, helical diffraction gratings, q-plates, or metasurfaces. Furthermore, acoustic vortex beams can also be generated by active transducer arrays, typically utilizing phased array technology (i.e., regularly changing the phase or delaying time) and multiple active transducers to generate specific acoustic vortices. In optical systems, another method for realizing vortex beams is called intracavity vortex generation, or vortex laser. It can generate a beam directly from within a cavity without requiring additional beam-shaping elements. The intracavity vortex wave generation method can generate high-power, high-beam-quality vortex beams with significant efficiency and compact structure.

[0003] Despite some progress in existing acoustic vortex beam generation methods, numerous challenges remain. Passive methods, while versatile, often suffer from complex structures, high losses, low conversion efficiency, and limited scalability. Active methods require multiple active components, leading to integration difficulties, high losses, and stringent precision requirements. Furthermore, while intracavity vortex wave generation methods excel in optics, they present significant challenges due to the complex engineering involved in characteristic states, gain media, and nonlinearities. To date, intracavity vortex wave generation methods in acoustics remain unexplored. Summary of the Invention

[0004] The main objective of this invention is to provide an intracavity vortex wave generation device and control method. By integrating nonlinear control components into the resonant cavity system and utilizing the non-reciprocal coupling characteristic, vortex waves carrying orbital angular momentum are directly generated within the cavity, avoiding the complexity and energy loss associated with traditional methods that require additional beamforming elements or multiple active transducer arrays. By adjusting the non-reciprocal coupling parameters, the topological charge of the generated vortex waves can be flexibly controlled, thereby enabling the generation of vortex waves with different topological charges and providing broader applicability for various applications.

[0005] To achieve the above objectives, the embodiments of this application provide the following technical solutions:

[0006] According to a first aspect of the embodiments of this application, an intracavity vortex wave generating device is provided, comprising: a resonant cavity system and a nonlinear control component integrated in the resonant cavity system;

[0007] The resonant cavity system consists of several resonant units forming a closed loop through a coupling structure, which is used to support the resonance of wave modes;

[0008] The nonlinear control component is used to achieve adjustable non-reciprocal coupling between at least two of the resonant units; it is also used to enable the resonant cavity system to generate vortex waves carrying orbital angular momentum by adjusting the coupling parameters of the non-reciprocal coupling.

[0009] Optionally, the resonant cavity system is an acoustic resonant cavity system, the resonant unit is an acoustic resonant cavity, and the coupling structure includes an acoustic conduit connecting adjacent acoustic resonant cavities.

[0010] Optionally, the properties of the coupling structure include reciprocal coupling channels and non-reciprocal coupling channels. The reciprocal coupling channels connect all adjacent resonant units for bidirectional coupling between adjacent resonant units. The non-reciprocal coupling channels selectively connect at least one pair of resonant units to introduce unidirectional coupling to break time-reversal symmetry.

[0011] Optionally, the nonlinear control component includes an active electroacoustic element, which includes an amplifier and a transducer; the amplifier is used to adjust the gain and phase of the electrical signal; the transducer includes a loudspeaker and a microphone, which are used to inject sound waves into the resonant cavity and collect feedback signals, respectively; the amplifier controls the amplitude of the non-reciprocal coupling by adjusting the gain and controls the phase of the non-reciprocal coupling by adjusting the phase, thereby controlling the topological charge of the vortex wave.

[0012] Optionally, the non-reciprocally coupled phase and the topological charge of the vortex wave satisfy a preset mapping relationship, which includes: when the non-reciprocally coupled phase is -0.38π, the topological charge rotates 1 revolution counterclockwise in the phase field; when the non-reciprocally coupled phase is 0.38π, the topological charge rotates 4 revolutions counterclockwise in the phase field.

[0013] Optionally, when the non-reciprocal coupling phase is fixed, the gain of the amplifier is adjusted so that the resonant cavity system exhibits bistable characteristics; there is a set difference between the generation threshold gain and the disappearance threshold gain of the vortex wave.

[0014] Optionally, the resonant cavity system is a microwave resonant cavity, and the resonant unit is coupled through passive devices; the nonlinear control component includes active devices for achieving non-reciprocal coupling and adjusting the coupling amplitude and phase.

[0015] According to a second aspect of the embodiments of this application, a control method for the intracavity vortex wave generating device described in the first aspect is provided, comprising:

[0016] Adjusting the gain of the nonlinear control component allows the resonant cavity system to enter the nonlinear operating range;

[0017] Adjust the phase of the non-reciprocal coupling to the target value to determine the topological charge in the corresponding vortex wave mode;

[0018] Self-excited oscillation is generated through a non-reciprocal coupling channel, and a vortex wave carrying orbital angular momentum is output from the resonant cavity system.

[0019] By adjusting the coupling parameters of the non-reciprocal coupling, topological charge switching or bistable switching control can be achieved.

[0020] According to a third aspect of the embodiments of this application, an acoustic particle manipulation device is provided, which employs the cavity vortex wave generating device described in the first aspect to apply controllable angular momentum to particles using vortex waves with different topological charge numbers.

[0021] In summary, this application provides an intracavity vortex wave generation device and control method. The intracavity vortex wave generation device includes a resonant cavity system and a nonlinear control component integrated within the resonant cavity system. The resonant cavity system consists of several resonant units forming a closed loop through a coupling structure to support the resonance of wave modes. The nonlinear control component is used to achieve adjustable non-reciprocal coupling between at least two of the resonant units; it is also used to generate vortex waves carrying orbital angular momentum by adjusting the coupling parameters of the non-reciprocal coupling. By integrating the nonlinear control component into the resonant cavity system, and utilizing the characteristics of non-reciprocal coupling, vortex waves carrying orbital angular momentum are directly generated within the cavity, avoiding the complexity and losses of traditional methods that require additional beamforming elements or complex active transducer arrays. By adjusting the coupling parameters of the non-reciprocal coupling, the topological charge of the generated vortex waves can be flexibly controlled, thereby achieving the generation of vortex waves with different topological charges and providing wider applicability for various applications. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0024] Figure 1 A schematic diagram of an intracavity vortex wave generating device provided in an embodiment of this application;

[0025] Figure 2a A schematic diagram of a ring resonant cavity system provided in an embodiment of this application;

[0026] Figure 2b This is a schematic diagram of parameter settings for a ring resonant cavity system provided in an embodiment of this application;

[0027] Figure 3a This is a schematic diagram of the equivalent tight-binding model of the ring resonant cavity system provided in the embodiments of this application;

[0028] Figure 3b This is a schematic diagram of the steady-state solution of the ring resonator system under nonlinear phase provided in the embodiments of this application;

[0029] Figure 3c This is a schematic diagram of the radiation field phase distribution of a ring resonant cavity system provided in an embodiment of this application;

[0030] Figure 4a and Figure 4b A schematic diagram of a vortex wave provided in an embodiment of this application;

[0031] Figure 5a and Figure 5b This is another schematic diagram of a vortex wave provided in an embodiment of this application;

[0032] Figure 6 This is a schematic diagram of the bistable characteristic test results provided in an embodiment of this application;

[0033] Figure 7 A flowchart illustrating a control method for an intracavity vortex wave generating device provided in this application embodiment;

[0034] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0037] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0038] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0040] Figure 1 An embodiment of this application illustrates an intracavity vortex wave generating device, comprising: a resonant cavity system and a nonlinear control component integrated within the resonant cavity system; the resonant cavity system consists of a plurality of resonant units forming a closed loop through a coupling structure to support the resonance of wave modes; the nonlinear control component is used to achieve adjustable non-reciprocal coupling between at least two of the resonant units; and is also used to generate vortex waves carrying orbital angular momentum by adjusting the coupling parameters of the non-reciprocal coupling.

[0041] At the fundamental physics level, this device achieves precise control of wave modes through the synergistic effect of the closed-loop structure of the resonant cavity system and the nonlinear control components. It avoids the complex beamforming elements or multiple active transducer arrays required in traditional methods, directly generating vortex waves within the cavity, thus improving system efficiency and performance.

[0042] In one possible implementation, the resonant cavity system is an acoustic resonant cavity system, the resonant unit is an acoustic resonant cavity, and the coupling structure includes an acoustic conduit connecting adjacent acoustic resonant cavities.

[0043] In one possible implementation, the properties of the coupling structure include reciprocal coupling channels and non-reciprocal coupling channels. The reciprocal coupling channels connect all adjacent resonant units for bidirectional coupling between adjacent resonant units. The non-reciprocal coupling channels selectively connect at least one pair of resonant units to introduce unidirectional coupling to break time-reversal symmetry.

[0044] The coupling structure between resonant units (including reciprocal and non-reciprocal coupling channels) provides a stable resonant environment, and the time-reversal symmetry of the system is broken through non-reciprocal coupling. Adjustable non-reciprocal coupling is achieved between resonant units through nonlinear control components, and vortex waves carrying orbital angular momentum are generated by adjusting the coupling parameters.

[0045] In one possible implementation, the nonlinear control component includes an active electroacoustic element, which includes an amplifier and a transducer; the amplifier is used to adjust the gain and phase of the electrical signal; the transducer includes a loudspeaker and a microphone, which are used to inject sound waves into the resonant cavity and collect feedback signals, respectively; the amplifier controls the amplitude of the non-reciprocal coupling by adjusting the gain and controls the phase of the non-reciprocal coupling by adjusting the phase, thereby controlling the topological charge of the vortex wave.

[0046] The nonlinear control component includes active electroacoustic elements. By adjusting the gain and phase of the electrical signal through an amplifier, it controls the amplitude and phase of the non-reciprocal coupling, ultimately controlling the topological charge of the vortex wave. This active electroacoustic element enables efficient generation and flexible control of vortex waves, avoiding the complex mechanical structures or multiple active components required in traditional methods, thus improving system efficiency and performance.

[0047] In one possible implementation, the non-reciprocally coupled phase and the topological charge of the vortex wave satisfy a preset mapping relationship, which includes: when the non-reciprocally coupled phase is -0.38π, the topological charge rotates 1 revolution counterclockwise in the phase field; when the non-reciprocally coupled phase is 0.38π, the topological charge rotates 4 revolutions counterclockwise in the phase field.

[0048] By adjusting the phase of the amplifier, precise control of the topological charge of the vortex wave can be achieved, meeting the topological charge requirements of different application scenarios.

[0049] In one possible implementation, when the non-reciprocal coupling phase is fixed, the gain of the amplifier is adjusted so that the resonant cavity system exhibits bistable characteristics; a set difference exists between the generation threshold gain and the disappearance threshold gain of the vortex wave.

[0050] Using bistable characteristics to achieve history-dependent vortex wave state switching is applicable to novel devices such as vortex switches and vortex memory, providing a foundation for realizing complex signal processing and storage functions.

[0051] At the technical implementation level, the complex multi-channel control is simplified to single-point modulation. By adjusting the two key parameters of non-reciprocal coupling, phase and gain, the topological charge of the vortex wave can be precisely controlled. This simplification of modulation brings significant advantages: on the one hand, the deterministic relationship between the geometric parameters of the acoustic channel (e.g., diameter 3.4 mm) and the coupling coefficient (κ = -60 Hz) makes the system repeatable; on the other hand, the introduction of bistable characteristics (manifested as a threshold hysteresis effect during gain adjustment) endows the device with memory functionality.

[0052] In one possible implementation, the resonant cavity system is a microwave resonant cavity, and the resonant unit is coupled through passive devices; the nonlinear control component is composed of active devices and is used to achieve non-reciprocal coupling and adjust the coupling amplitude and phase.

[0053] In the microwave domain, the resonant cavity system is a microwave resonant cavity. The resonant units achieve reciprocal coupling through passive coupling devices (including microstrip lines and capacitors), forming a closed-loop structure. The nonlinear control component includes active devices (including microwave amplifiers). These active devices are used to achieve non-reciprocal coupling and adjust the coupling amplitude and phase, thereby controlling the topological charge and frequency of the vortex wave. This enables efficient vortex wave generation in the microwave band and is suitable for microwave communication, radar systems, and microwave imaging.

[0054] In one possible implementation, by fixing the non-reciprocal coupling phase, the system exhibits bistable characteristics between the generation and disappearance of vortex waves by adjusting the amplifier gain. Specifically, the system begins to generate vortex waves when the gain reaches a certain threshold, and stops generating vortex waves when the gain decreases to another threshold. Utilizing bistable characteristics to achieve history-dependent vortex wave state switching is suitable for novel devices such as microwave switches and microwave memory, providing a foundation for complex signal processing and storage functions.

[0055] Traditional methods for generating acoustic vortex waves (similar to "acoustic spiral waves") require complex external equipment (such as phase plates or multi-transducer arrays). This application proposes a solution that: 1. Generates vortex waves directly within the acoustic resonant cavity without external shaping components. 2. Requires only a single actively controlled electroacoustic element (speaker + microphone + amplifier). By adjusting its parameters (such as phase and amplification factor), the topological charge of the vortex wave (i.e., the number of spiral "turns," such as -1, -4, etc.) can be changed. 3. Allows for dynamic switching: It also utilizes bistable characteristics to achieve the "switching" and "memory" functions of the vortex wave. The following detailed illustrations, with reference to the accompanying drawings, illustrate the device and method for generating intracavity acoustic vortex waves using a single non-reciprocal nonlinear active electroacoustic element, as proposed in this application.

[0056] The working process of this application embodiment is illustrated by an example of an acoustic vortex wave generating device operating in the frequency range of 850-1250Hz: the vortex wave generator includes an acoustic ring resonant cavity and an active electroacoustic element.

[0057] Part 1: Acoustic Ring Resonator.

[0058] An acoustic ring resonator consists of multiple resonant units and connecting conduits, used to generate acoustic resonance. The specific parameters of the resonator (such as size and shape) are designed according to actual requirements. Non-reciprocal nonlinear active electroacoustic components include directional amplifiers, loudspeakers, and microphones. These components provide non-reciprocal coupling, have adjustable phase and amplification, and operate in the nonlinear range.

[0059] In this embodiment of the application, the acoustic ring resonant cavity is 3D printed from photosensitive resin with a thickness of 6mm, including 10 cuboid resonant cavities and connecting pipes, with one hole drilled at the top of each cuboid resonant cavity. Figure 2a This is a schematic diagram of a ring resonant cavity system in an embodiment of this application; 10 cuboid resonant cavities are connected in series through a pipe to form a closed acoustic loop. A top opening is used to radiate acoustic vortex waves into free space. Figure 2b This is a schematic diagram of the parameter settings of the ring resonant cavity system in an embodiment of this application. The specific parameters are: height h = 19.2cm, width w = 3.4cm, length l = 5.2cm, ring radius r = 7.8cm, connecting pipe spacing d = 3.4cm, d2 = 4cm, and radiation hole radius (opening at the top of each cavity) r = 5mm.

[0060] Part Two: Active Electroacoustic Components.

[0061] The active electroacoustic element includes a directional amplifier equipped with a DC power supply, a speaker (output), and a microphone (input). Two holes with radii of 4 mm and 6.1 mm are drilled on the side of the acoustic resonator for inserting the speaker (small hole) and microphone (large hole) of the active element. The phase and amplification of this active electroacoustic element are adjustable. A single component realizes an excitation-feedback closed loop, forming a nonlinear feedback loop, and the vortex wave characteristics are controlled by adjusting the phase / gain.

[0062] Physically, each cuboid resonant cavity has a resonant frequency of 1050 Hz, and the combined radiation and thermoviscous losses introduced by the top opening are 4 Hz. The connecting conduits between the 2nd to 9th cuboid resonant cavities provide reciprocal coupling with a coupling coefficient of κ = -60 Hz. The connecting conduit between the 1st and 10th cuboid resonant cavities provides another reciprocal coupling with a coupling coefficient of κ. b =-70Hz.

[0063] Active electroacoustic components provide non-reciprocal coupling. a The coupling coefficient |κ| of this non-reciprocal coupling a |and phase φ κa The element is adjustable and can be controlled to operate in a linear or nonlinear range based on factors such as amplification and intracavity energy. In one possible implementation, the active electroacoustic element operates in the nonlinear range. Utilizing mode locking induced by nonlinear coupling and a structural design that breaks time-reversal symmetry, the ring resonant cavity generates self-excited oscillating single-mode vortex wave radiation, and the topological charge of the vortex wave can be controlled by adjusting boundary parameters (such as phase and amplitude).

[0064] The following calculations using a tight-binding model and Hamiltonian demonstrate how nonlinear coupling can cause the system to lock into a specific vortex mode (l=-1 or l=-4).

[0065] Part 1: Transforming physical devices into mathematical models, abstracting 10 actual cavities into a ring composed of 10 coupling points.

[0066] This ring resonant cavity system can be equivalently represented as follows: Figure 3a The tight-binding model shown has each resonant cavity labeled 1 to 10. Figure 3a This is a schematic diagram of the equivalent tight-binding model of the ring resonator system in an embodiment of this application; the 10 resonator cavities are equivalent to coupled resonator rings, the Hamiltonian H describes the system state, and the coupling is non-reciprocal (κ). a It exists between cavity 1 and cavity 10, breaking the time reversal symmetry.

[0067] Part 2: How nonlinear coupling generates vortex waves: By adjusting the phase to change the steady-state solution of the system, the mode proportion in a certain rotation direction (clockwise / counterclockwise) is calculated, and the radiation field exhibits a corresponding stable spiral phase.

[0068] First, according to its dynamic equations Solving for the steady state, we obtain the steady-state solutions of the nonlinear amplitude and intrinsic frequency of the ring resonant cavity system under different nonlinear coupling phases, where... Let H be the eigenstate of the system (or the complex amplitude of the classical acoustic field), describing the modal distribution of the sound waves within the resonant cavity. H is the Hamiltonian of the system, containing all energy and coupling terms. This is a time evolution operator that represents the change of system state over time. Figure 3b This is a schematic diagram of the steady-state solution of the ring resonator system under nonlinear phase in an embodiment of this application; the x-axis represents the nonlinear coupling phase φ. κa The y-axis represents the nonlinear coupling amplitude, the z-axis represents the frequency, and the thick line represents the self-excited oscillation threshold.

[0069] The Hamiltonian of this system is calculated according to the following formula:

[0070]

[0071] Resonant cavity eigenvalues middle, The eigenfrequency of a single resonant cavity (e.g., 1050 Hz) is determined by the cavity geometry and materials. denoted as the loss coefficient (imaginary part), corresponding to radiation and thermoviscous losses (e.g., 4Hz), with positive values ​​indicating energy dissipation. n ( () represents the generation and annihilation operators. Reciprocal coupling between adjacent resonant cavities. middle, The reciprocal coupling coefficient (e.g., -60Hz) represents the energy exchange intensity between adjacent resonant cavities (the negative sign indicates phase reversal). Non-reciprocal coupling terms... In, κ b To fix the reciprocal coupling coefficient (such as κ between the 1st and 10th cavities) b =−60Hz). κ a (·) represents a nonlinear, non-reciprocal coupling introduced by an active electroacoustic element, with an amplitude |κ. a |and phase φ κa Adjustable (e.g., φ) κa =−0.38π).

[0072] exist Figure 3b The bolded portion represents the minimum nonlinear amplitude threshold. When the nonlinear coupling strength exceeds this threshold, the system locks into a single mode (e.g., l = −1, -2, -3, and -4). This corresponds to the nonlinear coupling phase, amplitude, and eigenfrequency of the final lasing state. When φ κa When φ = -0.38π, the l = -1 mode is locked. κa Locking the l=-4 mode when =0.38π.

[0073] The proportions of clockwise and counterclockwise modes in the wavefunction at each steady state are calculated using non-Bloch mode theory. The eigenstates of the system are also considered. It can be represented as and The superposition, that is ,here and .

[0074] l is an integer and depends on the wave function k, i.e., l≈Re(k)N / 2π, β 1,2 =e±ik represents the generalized Brillouin zone. The coefficients α1 and α2 can be solved using the following eigenvalue equations:

[0075]

[0076] Each eigenstate can be obtained through this equation. The corresponding coefficients α1 and α2. It can be observed that the mode proportion can be adjusted by regulating the boundary, making either the clockwise or counterclockwise mode dominant (up to 95%). Because the ring resonator system has openings, its wavefunction can be radiated into the air, from which its radiation field can be calculated. The phase of its radiation field is as follows... Figure 3c As shown, Figure 3c This is a schematic diagram of the radiation field phase distribution of the ring resonant cavity system in an embodiment of this application. The radiation field phase exhibits a spiral change, and the topological charge number l is determined by the number of phase rotations and the direction (e.g., -2π corresponds to l=-1). It can be seen that the wave function of the lasing state is different at different phases, that is, the topological charge of the lasing radiation field is different.

[0077] Part 3: The physical mechanism of bistable state: When the phase amplitude is fixed, the system will exhibit a hysteresis effect: the vortex wave is generated only when the amplitude is increased to the threshold A; the vortex wave disappears only when the amplitude is decreased to the threshold B; (A≠B, similar to a hysteresis loop).

[0078] Furthermore, due to the feedback mechanism of the nonlinear active components, the system exhibits bistable characteristics, meaning that when the phase of the active electroacoustic components is fixed, increasing / decreasing the amplifier amplitude will produce different phase transition points. Thus, the system demonstrates support for history-dependent vortex wave state switching.

[0079] To verify the proposed properties, two vortex wave generation experiments were conducted in practical applications. The active electroacoustic element was tested in the nonlinear region with phases of -0.38π and 0.38π, respectively, which proved the self-excited oscillating single-mode vortex wave radiation of the adjustable topological charge.

[0080] The frequency and topological charge of vortex waves generated by an active electroacoustic element operating in different phases within a nonlinear region were measured. Figure 4a and Figure 4b This is a schematic diagram of a vortex wave with a topological charge of -1 and a frequency of 950Hz generated when the nonlinear coupling phase is -0.38π in an embodiment of this application. When the phase of the active electroacoustic element is -0.38π, the upper surface of the ring resonant cavity radiates a 950Hz vortex wave, and its sound pressure curve is shown below. Figure 4a As shown. Figure 4b The phase field distribution of the vortex wave is shown, and it can be observed that the frequency changes by -2π, which means that the topological charge of the vortex wave is -1. That is, at a frequency of 950Hz, the phase field rotates by -2π → the topological charge l = -1.

[0081] Figure 5a and Figure 5b This is a schematic diagram of a vortex wave with a topological charge of -4 and a frequency of 1150Hz generated when the nonlinear coupling phase is 0.38π in an embodiment of this application. When the phase of the active electroacoustic element is 0.38π, the upper surface of the ring resonant cavity radiates an 1150Hz vortex wave, and its sound pressure curve is shown below. Figure 5a As shown. Figure 5b The phase field distribution of the vortex wave is shown, and it can be observed that the frequency changes by -8π, which means that the topological charge of the vortex wave is -4. That is, at a frequency of 1150Hz, the phase field rotates by -8π → topological charge l = -4.

[0082] When the phase is -0.38π, a vortex wave with a frequency of 950Hz and a topological charge of -1 is generated. When the phase is 0.38π, a vortex wave with a frequency of 1150Hz and a topological charge of -4 is generated. These experimental results are consistent with the theoretical calculations, proving the effectiveness of the device. If the nonlinear coupling is adjusted to other phases, vortex waves with other frequencies and topological charges can be generated.

[0083] The system exhibits bistable characteristics, meaning that at a fixed phase, by adjusting the amplifier amplitude, the system can switch between generating vortex waves and not generating waves, and exhibits hysteresis characteristics. Figure 6 This is a schematic diagram of the bistable characteristic test results in an embodiment of this application. When the phase of the active electroacoustic element is -0.38π, as the amplitude of the active electroacoustic element is continuously increased, the ring resonator initially does not radiate any signal. As the amplitude increases, after reaching a threshold, the upper surface of the ring resonator radiates a 950Hz vortex wave. Continuing to increase the amplitude, the vortex wave mode and frequency remain unchanged, and the detected radiation intensity gradually stabilizes. However, when the amplitude is gradually decreased, the ring resonator initially generates a vortex wave, but suddenly stops radiating a signal at a certain threshold. These two threshold points are not equal, exhibiting bistable characteristics. This can be used in acoustic memory ("on" state stores 1, "off" state stores 0).

[0084] This application's embodiments innovatively employ a single non-reciprocal nonlinear active electroacoustic element, overcoming the symmetry limitations of traditional acoustic vortex generation techniques. A single element can overcome the linearity, reciprocity, Hermitianness, and time-reversal symmetry of the system through a nonlinear feedback mechanism, achieving a revolutionary intracavity acoustic vortex wave generation scheme. Compared to traditional methods relying on external sound sources and passive elements, this scheme utilizes an intracavity self-excited oscillation mechanism to induce mode competition within the nonlinear operating range using boundary nonlinearity. It achieves self-excited oscillation and locks onto a single, single-frequency vortex wave without the need for an additional sound source, its working principle being similar to that of an "acoustic vortex laser."

[0085] The advantages of this device are also reflected in the following aspects: First, it achieves real-time dynamic switching of topological charges through phase adjustment, providing a new dimension for acoustic information encoding; second, the bistable characteristics exhibited by the system make it applicable to vortex switches and memory devices; third, the universal design concept of this scheme can be extended to the generation of higher-order mode vortices and is applicable to multiple physical fields such as circuits, microwaves, terahertz, and optics, showing broad application prospects. Experimental verification shows that this scheme based on nonlinear control of single components is not only theoretically innovative but also has practical engineering value, opening up new avenues for the development of acoustic vortex technology.

[0086] Its principle applies not only to acoustic systems but also extends to optics, microwaves, terahertz fields, and other areas, offering broad application prospects. In acoustics, this device can be used for acoustic communication, encoding and transmitting information by manipulating the topological charge of vortex waves, thus improving communication security and capacity. It can also be used for particle manipulation, utilizing the orbital angular momentum of vortex waves to capture and rotate tiny particles, with applications in biomedicine and materials science. In optics, this principle can be applied to the generation of optical vortex waves for quantum information processing, optical communication, and optical imaging. By manipulating the topological charge of optical vortex waves, high-capacity optical communication and high-precision optical imaging can be achieved. In the microwave and terahertz fields, this device can be used for high-power, high-efficiency vortex wave generation for radar, communication, and imaging systems. By manipulating the frequency and topological charge of vortex waves, multimodal signal transmission and high-resolution imaging can be achieved.

[0087] Based on the same technical concept, this application also provides a control method based on the aforementioned intracavity vortex wave generating device, such as... Figure 7 As shown, the method includes:

[0088] Step S701: Adjust the gain of the nonlinear control component to bring the resonant cavity system into the nonlinear operating range;

[0089] Step S701: Adjust the phase of the non-reciprocal coupling to the target value and determine the topological charge in the corresponding vortex wave mode;

[0090] Step S702: Excite self-excited oscillation through a non-reciprocal coupling channel, and output a vortex wave carrying orbital angular momentum from the resonant cavity system;

[0091] Step S703: By adjusting the coupling parameters of the non-reciprocal coupling, topological charge switching or bistable switching control is achieved.

[0092] In summary, this application provides an intracavity vortex wave generation device and control method. The intracavity vortex wave generation device includes a resonant cavity system and a nonlinear control component integrated within the resonant cavity system. The resonant cavity system consists of several resonant units forming a closed loop through a coupling structure to support the resonance of wave modes. The nonlinear control component is used to achieve adjustable non-reciprocal coupling between at least two of the resonant units; it is also used to generate vortex waves carrying orbital angular momentum by adjusting the coupling parameters of the non-reciprocal coupling. By integrating the nonlinear control component into the resonant cavity system, and utilizing the characteristics of non-reciprocal coupling, vortex waves carrying orbital angular momentum are directly generated within the cavity, avoiding the complexity and losses of traditional methods that require additional beamforming elements or multiple active transducer arrays. By adjusting the coupling parameters of the non-reciprocal coupling, the topological charge of the generated vortex waves can be flexibly controlled, thereby achieving the generation of vortex waves with different topological charges and providing wider applicability for various applications.

[0093] Based on the same technical concept, this application also provides an acoustic particle manipulation device, which uses the aforementioned intracavity vortex wave generating device to apply controllable angular momentum to particles using vortex waves with different topological charge numbers.

[0094] It should be noted that the above embodiments are illustrative of this application and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. This application can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

[0095] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0096] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made under the concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A cavity vortex wave generating device, characterized in that, include: A resonant cavity system and a nonlinear control component integrated in the resonant cavity system; the nonlinear control component includes an active electroacoustic element, which includes an amplifier and a transducer; The resonant cavity system consists of several resonant units forming a closed loop through a coupling structure, which is used to support the resonance of wave modes; The nonlinear control component is used to achieve adjustable non-reciprocal coupling between at least two of the resonant units; it is also used to enable the resonant cavity system to generate vortex waves carrying orbital angular momentum by adjusting the coupling parameters of the non-reciprocal coupling. The amplifier is used to adjust the gain and phase of the electrical signal; the transducer includes a loudspeaker and a microphone, which are used to inject sound waves into the resonant cavity and collect feedback signals, respectively; the amplifier controls the amplitude of the non-reciprocal coupling by adjusting the gain and controls the phase of the non-reciprocal coupling by adjusting the phase, thereby controlling the topological charge of the vortex wave.

2. The apparatus as claimed in claim 1, characterized in that, The resonant cavity system is an acoustic resonant cavity system, the resonant unit is an acoustic resonant cavity, and the coupling structure includes an acoustic conduit connecting adjacent acoustic resonant cavities.

3. The apparatus as described in claim 2, characterized in that, The properties of the coupling structure include reciprocal coupling channels and non-reciprocal coupling channels. The reciprocal coupling channels connect all adjacent resonant units and are used for bidirectional coupling between adjacent resonant units. The non-reciprocal coupling channel selectively connects at least one pair of resonant units to introduce unidirectional coupling to break time-reversal symmetry.

4. The apparatus as claimed in claim 1, characterized in that, The non-reciprocal coupling phase and the topological charge of the vortex wave satisfy a preset mapping relationship, which includes: when the non-reciprocal coupling phase is -0.38π, the topological charge rotates 1 revolution counterclockwise in the phase field; when the non-reciprocal coupling phase is 0.38π, the topological charge rotates 4 revolutions counterclockwise in the phase field.

5. The apparatus as claimed in claim 1, characterized in that, When the non-reciprocal coupling phase is fixed, the gain of the amplifier is adjusted so that the resonant cavity system exhibits bistable characteristics; there is a set difference between the generation threshold gain and the disappearance threshold gain of the vortex wave.

6. The apparatus as claimed in claim 1, characterized in that, The resonant cavity system is a microwave resonant cavity, and the resonant unit is coupled through passive devices; the nonlinear control component includes active devices for achieving non-reciprocal coupling and adjusting the coupling amplitude and phase.

7. A control method for the intracavity vortex wave generating device according to any one of claims 1-6, characterized in that, include: Adjusting the gain of the nonlinear control component allows the resonant cavity system to enter the nonlinear operating range; Adjust the phase of the non-reciprocal coupling to the target value to determine the topological charge in the corresponding vortex wave mode; Self-excited oscillation is generated through a non-reciprocal coupling channel, and a vortex wave carrying orbital angular momentum is output from the resonant cavity system. By adjusting the coupling parameters of the non-reciprocal coupling, topological charge switching or bistable switching control can be achieved.

8. An acoustic particle manipulation device, characterized in that, Using the cavity vortex wave generating device according to any one of claims 1-6, controllable angular momentum is applied to particles by vortex waves with different topological charge numbers.

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