A topological rainbow slow light trapping system based on a triangular lattice magneto-optical photonic crystal and a method for regulating the same

Abstract

This invention belongs to the field of topological photonics technology and discloses a topological rainbow slow-light trapping system and its control method based on triangular lattice magneto-optical photonic crystals. It includes a coupled slow-light waveguide substrate and a segmented gradient bias magnetic field loading module. The coupled slow-light waveguide substrate consists of two independent triangular lattice magneto-optical photonic crystals arranged vertically opposite each other. The coupling distance between the two sets of magneto-optical photonic crystals relative to the center of the dielectric pillar is fixed at d=1.5a. Wave packets containing electromagnetic waves of different frequencies are incident from the left side of the waveguide. This invention achieves spatial fixed-point separation and trapping of photons of different frequencies by changing the magnitude of the bias magnetic field in different regions. It successfully realizes the topological rainbow function of globally flat slow-light transmission, broadband continuously adjustable magnetic field, and controllable reading and writing of multi-frequency photons. It can be used for the design and development of miniaturized and integrated topological photonic devices such as on-chip optical buffers, multi-channel wavelength division multiplexing, and microwave photonic storage.

Description

Technical Field

[0001] This invention belongs to the field of topological photonics technology, and in particular relates to a topological rainbow slow light capture system and its control method based on a triangular lattice magneto-optical photonic crystal. Background Technology

[0002] Slow light refers to the optical phenomenon where the group velocity of electromagnetic waves in a medium is much lower than the speed of light in a vacuum. By relying on Brillouin dispersion engineering of photonic crystals, the group velocity and dispersion characteristics of slow light can be artificially controlled, which is the core foundation of optical buffers and optical delay devices. Topological photonic insulators have non-zero topological Chern numbers, and the boundaries can generate topologically protected unidirectional chiral edge states, which have natural resistance to backscattering from processing defects and structural corners. Magneto-optical materials will break the time reversal symmetry under an external static magnetic field perpendicular to the z-axis, and the permeability of the medium will become a second-order tensor, so that the dispersion curve can be controlled by the external field.

[0003] Currently, the mainstream mechanisms for realizing slow light include four main categories: electromagnetically induced transparency, metasurfaces, surface plasmons, and photonic crystal waveguides. However, the first three have shortcomings in practical applications, such as extremely low temperature operating conditions, mutual constraints between loss and bandwidth, and sensitivity to surface roughness. In the past two decades, photonic crystal waveguides have become the mainstream platform for integrated slow light. Topological slow light devices based on the photonic Hall effect further improve transmission robustness. Existing topological slow light is divided into two main realization paths: Brillouin zone entangled broadband slow light and reverse edge state coupled slow light. The latter relies on the reverse energy flow at the upper and lower boundaries to significantly reduce the photon group velocity.

[0004] Current research on magneto-optical topological slow-light rainbow devices, both domestically and internationally, largely focuses on cubic lattice configurations. Exploration of triangular lattice-coupled slow-light topological rainbow systems is scarce. Topological rainbows can be achieved primarily through three technical pathways: dispersion engineering, synthesis dimension, and Landau. Among these, gradient external magnetic field dispersion engineering offers the best integration effect. However, existing cubic lattice schemes still suffer from several drawbacks: the slow-light dispersion curve fluctuates wildly, the group velocity dispersion value is large, waveform distortion easily occurs during optical pulse transmission, and the continuous magnetic field tuning bandwidth is less than 10%, making it difficult to meet the requirements of multi-channel wavelength division multiplexing and parallel trapping. Furthermore, the fabrication stage requires photolithography to process gradient dielectric pillars and multilayer gradient loss films, resulting in complex processes and high mass production costs. Additionally, the lack of segmented magnetic field physical isolation structures leads to mutual coupling and interference between magnetic fields in adjacent gradient intervals, causing spectral aliasing of trapped photons at different frequencies. Currently, there is also a lack of targeted integrated static trapping device design schemes. Summary of the Invention

[0005] To address a series of problems in existing square lattice magneto-optical photonic crystal topological rainbow slow-light devices, such as large dispersion fluctuations, optical pulse distortion, insufficient tunable magnetic field bandwidth, complex chip fabrication processes, crosstalk between gradient magnetic field regions, and the lack of dedicated integrated static trapping devices, this invention, based on the reverse chiral edge coupling mechanism of triangular lattice bicrystalline crystals, designs a magnetically tunable topological rainbow slow-light trapping device and a matching magnetic field control scheme. It abandons complex fabrication structures such as gradient dielectric pillars and gradient loss thin films, and relies on segmented physically isolated gradient external fields to achieve crosstalk-free fixed-point trapping of multi-frequency photons. While ensuring near-zero group velocity dispersion and nearly 10% continuous magnetic field tuning performance across the entire domain, it simplifies the device configuration, reduces on-chip integration difficulty, and fills the research gap in triangular lattice magneto-optical coupled slow-light trapping devices.

[0006] To achieve the above objectives, the present invention provides a topological rainbow slow light trapping system based on a triangular lattice magneto-optical photonic crystal, comprising:

[0007] A coupled slow-light waveguide substrate includes an upper triangular lattice magneto-optical photonic crystal and a lower triangular lattice magneto-optical photonic crystal arranged in parallel. A slow-light coupling transmission channel is formed between the lower boundary of the upper triangular lattice magneto-optical photonic crystal and the upper boundary of the lower triangular lattice magneto-optical photonic crystal. The slow-light coupling transmission channel is divided into six lattice regions with increasing bias magnetic field magnitudes along the electromagnetic wave propagation direction. Each lattice region is subjected to a different static bias magnetic field, and a separator line is provided between adjacent lattice regions. An incident position is provided on the left side of the coupled slow-light waveguide substrate for inputting electromagnetic wave packets containing multiple frequency components.

[0008] The segmented gradient bias magnetic field loading module includes six independent magneto-optical photonic crystal units, each corresponding to one of the six lattice regions, for independently applying a corresponding bias magnetic field to each lattice region.

[0009] Optionally, the six lattice regions are arranged sequentially from low magnetic field to high magnetic field along the direction of electromagnetic wave propagation. The bias magnetic field of the first lattice region 1 is 1000G, the bias magnetic field of the second lattice region 2 is 1200G, the bias magnetic field of the third lattice region 3 is 1400G, the bias magnetic field of the fourth lattice region 4 is 1600G, the bias magnetic field of the fifth lattice region 5 is 1800G, and the bias magnetic field of the sixth lattice region 6 is 2000G. The bias magnetic field of each lattice region corresponds to a uniquely matched trapping frequency.

[0010] Optionally, the higher the value of the bias magnetic field of each lattice region, the greater the overall blue shift of the corresponding slow light dispersion curve; after electromagnetic wave packets 7 of different frequencies are incident, photons of each frequency are confined to the corresponding matching lattice regions, forming a topological rainbow effect.

[0011] Optionally, the bias magnetic field of each lattice region is configured to be synchronously adjusted up or down, so that the dispersion curve is synchronously shifted, and the operating frequency band is continuously tuned in the range of 11.4 GHz to 12.6 GHz.

[0012] Optionally, both the upper triangular lattice magneto-optical photonic crystal and the lower triangular lattice magneto-optical photonic crystal are composed of periodically arranged magneto-optical dielectric pillars 8.

[0013] Optionally, the center-to-center distance between the magneto-optical dielectric pillars 8 on the upper and lower sides of the slow optical coupling transmission channel is fixed as the coupling distance d = 1.5a, where a is the lattice constant.

[0014] Optionally, the magneto-optical dielectric column 8 is made of yttrium iron garnet (Y3Fe5O). 12 .

[0015] On the other hand, to achieve the above objectives, the present invention provides a topological rainbow magnetic field modulation method, applied to the aforementioned topological rainbow slow light trapping system based on a triangular lattice magneto-optical photonic crystal, comprising:

[0016] Step 1: Prepare a coupled slow optical waveguide substrate with a fixed coupling spacing of d=1.5a, divide it into six gradient-increasing lattice regions along the electromagnetic wave propagation direction, and physically separate adjacent lattice regions with separator lines, and initialize the gradient magnetic field corresponding to each lattice region.

[0017] Step 2: An electromagnetic wave packet 7 containing multiple frequency components is input from the left incident position of the coupled slow optical waveguide substrate, and photons of each frequency are statically captured at fixed points in each lattice region.

[0018] Step 3: Synchronously adjust the magnitude of the bias magnetic field in all lattice regions to achieve continuous and adjustable operating frequency band.

[0019] The technical effects of this invention are as follows:

[0020] Compared to traditional square lattice schemes, this invention uses a uniform triangular lattice array, eliminating the need for complex gradient structures, effectively simplifying the photolithography process and reducing manufacturing costs. The segmented isolation design can prevent spectral aliasing of different capture frequencies. The topological edges have inherent resistance to defects and corner scattering, resulting in outstanding device transmission stability. It retains only the core structure for static photon capture, making the overall size compact and the control method simple. It can be widely adapted to various integrated photonic chips such as on-chip optical buffers, microwave photonic storage, and multi-channel wavelength division multiplexing. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments 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 these drawings without creative effort.

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0023] Figure 1 This is a schematic diagram of the overall structure of the topological rainbow slow light trapping system based on a triangular lattice magneto-optical photonic crystal in an embodiment of the present invention.

[0024] Figure 2 These are the projected dispersion band diagrams of the supercell of the triangular lattice magneto-optical photonic crystal under different magnetic fields in embodiments of the present invention, and the corresponding group velocity distribution diagrams; wherein, Figure 2 (a) Projected dispersive band diagrams of the supercell of a triangular lattice magneto-optical photonic crystal under different magnetic fields; Figure 2 (b) is Figure 2 (a) A magnified view of the relevant area in the focused study section; Figure 2 (c) shows the curves relating the slow light group velocity to different magnetic field strengths;

[0025] Figure 3 This is the full-wave simulation result of the multi-frequency electromagnetic wave incident on the device in the embodiment of the present invention; wherein, Figure 3 (a) The global electric field amplitude distribution of the entire coupled waveguide channel after electromagnetic wave packets carrying all six sets of captured frequencies are incident from the left port; Figure 3 (b) is a schematic diagram of the multi-frequency incident wave packet components and the capture position corresponding to each characteristic frequency;

[0026] Figure 4 This is a detailed diagram of the steady-state local electric field of the overall structure in an embodiment of the present invention.

[0027] Labeling explanation: 1. First lattice region; 2. Second lattice region; 3. Third lattice region; 4. Fourth lattice region; 5. Fifth lattice region; 6. Sixth lattice region; 7. Electromagnetic wave packet; 8. YIG dielectric pillar; 9. First separator line; 10. Second separator line; 11. Third separator line; 12. Fourth separator line; 13. Fifth separator line. Detailed Implementation

[0028] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0029] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0030] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0031] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] Example 1

[0034] To address six major technical challenges of existing square lattice magneto-optical topological rainbow devices—pulse distortion, narrow bandwidth of tunable magnetic fields, complex fabrication processes, crosstalk within gradient magnetic fields, structural redundancy, and the lack of triangular lattice trapping devices—this embodiment provides a topological rainbow slow-light trapping system based on a triangular lattice magneto-optical photonic crystal, such as… Figure 1 - Figure 4 As shown, the system is divided into a coupled slow-light waveguide substrate and a segmented gradient bias magnetic field loading module. The waveguide is composed of two triangular lattice magneto-optical photonic crystals with identical parameters, arranged vertically to form a transmission channel. The internal structure is periodically arranged with yttrium iron garnet (Y3Fe5O3). 12 (YIG) dielectric pillars with a lattice constant of 16 mm were determined. The size of the dielectric pillars and the magnetic parameters of the materials were set according to the simulation standard. Six independent lattice regions were divided along the light propagation direction. Solid isolation structures were added between the regions to avoid mutual interference of magnetic fields. Independent electromagnets were matched at the bottom of each region to output a gradient vertical static magnetic field. Scattering boundary conditions were set around the magneto-optical photonic crystal to absorb the leaked stray electromagnetic waves and weaken the interface reflection interference.

[0035] The coupled slow-light waveguide substrate consists of two independent triangular lattice magneto-optical photonic crystals: an upper triangular lattice magneto-optical photonic crystal and a lower triangular lattice magneto-optical photonic crystal arranged in parallel. The lower boundary of the upper triangular lattice magneto-optical photonic crystal and the upper boundary of the lower triangular lattice magneto-optical photonic crystal form a slow-light coupling transmission channel. The center-to-center distance between the dielectric pillars on both sides of the slow-light coupling transmission channel is uniquely fixed as the coupling distance d = 1.5a, where a is a lattice constant. Along the propagation direction of the electromagnetic wave from left to right, the coupled slow-light waveguide substrate is divided into six continuous independent lattice regions arranged sequentially from low magnetic field to high magnetic field: the first lattice region 1 with a bias magnetic field of 1000G, the second lattice region 2 with a bias magnetic field of 1200G, the third lattice region 3 with a bias magnetic field of 1400G, the fourth lattice region 4 with a bias magnetic field of 1600G, the fifth lattice region 5 with a bias magnetic field of 1800G, and the sixth lattice region 6 with a bias magnetic field of 1800G. A sixth lattice region 6 with a field size of 2000G is defined; a first dividing line 9 is set as the boundary between the first lattice region 1 with a bias magnetic field size of 1000G and the second lattice region 2 with a bias magnetic field size of 1200G; a second dividing line 10 is set as the boundary between the second lattice region 2 with a bias magnetic field size of 1200G and the third lattice region 3 with a bias magnetic field size of 1400G; a third dividing line 11 is set as the boundary between the third lattice region 3 with a bias magnetic field size of 1400G and the fourth lattice region 4 with a bias magnetic field size of 1600G; a fourth dividing line 12 is set as the boundary between the fourth lattice region 4 with a bias magnetic field size of 1600G and the fifth lattice region 5 with a bias magnetic field size of 1800G; and a fifth dividing line 13 is set as the boundary between the fifth lattice region 5 with a bias magnetic field size of 1800G and the sixth lattice region 6 with a bias magnetic field size of 2000G. The first dividing line 9, the second dividing line 10, the third dividing line 11, the fourth dividing line 12, and the fifth dividing line 13 physically separate the lattice regions of two adjacent sets of different bias magnetic fields to avoid crosstalk between the magnetic fields inside the adjacent lattice regions; the incident position is set on the left side of the coupled slow waveguide substrate to input electromagnetic wave packets 7 containing multiple frequency components; YIG dielectric pillars 8 are periodically arranged inside the upper and lower regions of the coupled slow waveguide.

[0036] The feasible configuration involves both the upper and lower triangular lattice magneto-optical photonic crystals being composed of periodically arranged YIG dielectric pillar arrays; the dielectric material is yttrium iron garnet (Y3Fe5O). 12 YIG is abbreviated as YIG. The YIG dielectric pillar has a radius r = 0.12a, a height h = 10mm, a lattice constant a = 16mm, a saturation magnetization of 1850G, a linewidth ΔH = 50G, and a gyromagnetic damping coefficient α = 0.0002.

[0037] In a feasible configuration, a first lattice region 1 with a bias magnetic field magnitude of 1000G is designated as the lowest magnetic field region, and a bias magnetic field of 1000G is applied at a matching trapping frequency f1. A second lattice region 2 with a bias magnetic field magnitude of 1200G has a higher magnetic field strength than the first lattice region 1 with a bias magnetic field magnitude of 1000G, and a static bias magnetic field of 1200G is applied at a matching trapping frequency f2. A third lattice region 3 with a bias magnetic field magnitude of 1400G has a higher magnetic field strength than the second lattice region 2 with a bias magnetic field magnitude of 1200G, and a static bias magnetic field of 1400G is applied at a matching trapping frequency f3. A fourth lattice region 4 with a bias magnetic field magnitude of 1600G has a higher magnetic field strength than the third lattice region 3 with a bias magnetic field magnitude of 1400G. 3. A static bias magnetic field of 1600G is applied at a matching capture frequency f4; the magnetic field strength of the fifth lattice region 5, with a bias magnetic field of 1800G, is higher than that of the fourth lattice region 4, with a bias magnetic field of 1600G, and a static bias magnetic field of 1800G is applied at a matching capture frequency f5; the sixth lattice region 6, with a bias magnetic field of 2000G, is the highest magnetic field region, with a magnetic field strength higher than that of the bias magnetic field of 1800G5, and a static bias magnetic field of 2000G is applied at a matching capture frequency f6; the segmented gradient bias magnetic field loading module contains six sets of independent magneto-optical photonic crystal units corresponding to the six lattice regions respectively, and each set of magneto-optical photonic crystal units corresponds to the magnetic field size of the lattice region, so that the magnetic fields of each magnetic field region do not interfere with each other.

[0038] It is feasible that the higher the magnetic field value, the greater the overall blue shift of the slow light dispersion curve; the first dividing line 9, the second dividing line 10, the third dividing line 11, the fourth dividing line 12, and the fifth dividing line 13 sequentially separate the lattice regions of two adjacent sets of different bias magnetic fields, and each lattice region uniquely corresponds to a set of trapping frequencies with a group velocity vg≈0; after electromagnetic wave packets 7 containing different frequencies are incident from the left, photons of different frequencies are respectively bound to the corresponding magnetic field lattice regions, and multi-frequency photons are spatially trapped along the propagation direction by relying on the high and low magnetic field intervals to form a topological rainbow effect.

[0039] It is feasible to set scattering boundary conditions around the entire coupled slow optical waveguide substrate to absorb residual stray electromagnetic waves and suppress interface reflection interference.

[0040] It is feasible that the higher the external field strength, the greater the blue shift of the slow light dispersion curve. Each of the six gradient magnetic fields corresponds to a set of photon trapping characteristic frequencies with group velocities approaching zero. After multi-band electromagnetic waves are incident from the left, photons of different frequencies will match the corresponding lattice regions to complete fixed-point confinement. By uniformly and synchronously adjusting the magnetic field strength of all regions, the dispersion curve is synchronously shifted as a whole, and nearly 10% continuous bandwidth tuning can be achieved in the 11.4GHz~12.6GHz operating frequency band, overcoming the defect of narrow adjustable bandwidth of existing devices.

[0041] A vertical external field can disrupt the time-reversal symmetry of the photonic system. The native lattice contains a degenerate Dirac cone. After applying a reference magnetic field, the cone-shaped band splits, generating a topological photonic bandgap with a non-zero Chern number from 11.4 GHz to 12.6 GHz. Topological chiral edge states with opposite propagation directions are generated at the upper and lower boundaries of the two crystals, respectively. The two undergo mode hybridization and form a circulating energy flow in the channel, resulting in a slow-light dispersion curve with a gentle trend. The average group refractive index is about 10 in the whole momentum range, eliminating pulse transmission distortion at its source.

[0042] This embodiment also provides a method for controlling a topological rainbow magnetic field, comprising the following steps:

[0043] Step 1: Prepare a coupling structure with a fixed coupling spacing of d=1.5a, where a is a lattice constant. This coupling structure consists of two independent triangular lattice magneto-optical photonic crystals placed vertically opposite each other. Divide the structure along the electromagnetic wave propagation direction into six gradient-increasing lattice regions: 1000G first lattice region 1, 1200G second lattice region 2, 1400G third lattice region 3, 1600G fourth lattice region 4, 1800G fifth lattice region 5, and 2000G sixth lattice region 6. Set a first separator line 9 to separate the 1000G first lattice region 1 from the 1200G second lattice region 2, and set a second separator line 9 to separate the 1000G first lattice region 1 from the 1200G second lattice region 2. Line 10 separates the 1200G second lattice region 2 from the 1400G third lattice region 3. Third separating line 11 separates the 1400G third lattice region 3 from the 1600G fourth lattice region 4. Fourth separating line 12 separates the 1600G fourth lattice region 4 from the 1800G fifth lattice region 5. Fifth separating line 13 separates the 1800G fifth lattice region 5 from the 2000G sixth lattice region 6. These five separating lines isolate adjacent magnetic field regions and initialize corresponding gradient magnetic fields. Scattering boundary conditions are set around the entire coupled slow-waveguide substrate to absorb residual electromagnetic waves.

[0044] Step 2: Input the electromagnetic wave packet 7 containing multiple frequency components from the left side of the substrate, and complete the static capture of multi-frequency photons by relying on the high and low magnetic field lattice regions separated by the separator line.

[0045] Step 3: Synchronously adjust the magnetic field magnitude of all magnetic field lattice regions to achieve nearly 10% continuous adjustment within a bandwidth of 11.4–12.6 GHz, which is suitable for micro-integrated topological photonic devices such as on-chip optical buffers, multi-channel wavelength division multiplexing, and microwave photonic storage.

[0046] As described above, this embodiment provides a topological rainbow slow-light trapping device based on reverse edge-state coupling of a triangular lattice magneto-optical photonic crystal. The device employs a linear symmetrical coupling waveguide structure. The main body consists of two opposing triangular lattice magneto-optical photonic crystals with identical structural parameters, forming a coupling transmission channel. The dielectric pillar array uses a uniform periodic arrangement, eliminating the need for a gradient size structure and simplifying the fabrication process. The core physical parameters of the device satisfy: lattice constant a = 16 mm, dielectric pillar radius r = 0.12 a, pillar height h = 10 mm, and fixed coupling channel spacing d = 1.5 a. The dielectric material is yttrium iron garnet (Y3Fe5O3). 12 The material's magnetic parameters were set to saturation magnetization of 1850G, resonance linewidth ΔH = 50G, and gyromagnetic damping coefficient α = 0.0002.

[0047] In the slow light transport mechanism of photons, the photon group velocity and the slope of the dispersion curve satisfy the following relationship: In the formula, For the photon group velocity, The angular frequency of electromagnetic waves Let be the wave vector. When the dispersion curve approaches horizontal and its slope approaches zero, the photon group velocity... This enables static photon trapping. This embodiment utilizes wave vector... A flat dispersive band is obtained in the vicinity, where the global group velocity approaches zero and the group velocity dispersion coefficient approaches a minimum, which can completely suppress optical pulse transmission distortion.

[0048] Figure 2 This embodiment presents the projected dispersion band structure of the triangular lattice magneto-optical photonic crystal supercell under different magnetic fields, along with the corresponding group velocity distribution. Figure 2 (a) is the projected dispersion band diagram of the supercell of the triangular lattice magneto-optical photonic crystal under different magnetic fields in this embodiment. Wherein, Figure 2 (b) is the embodiment of this example. Figure 2 (a) A magnified view of the part of the study that is being focused on; the magnified object is... Figure 2 (a) The dispersive band region near kx=0.435(2π / a) is selected by the black dashed box. Figure 2 (c) shows the curves of the slow light group velocity variation under different magnetic field intensities in this embodiment.

[0049] This embodiment breaks the lattice time-reversal symmetry by using a vertical z-axis static bias magnetic field, causing band splitting in the degenerate Dirac cone under no external field conditions. This opens a topological photonic bandgap of 11.4 GHz to 12.6 GHz, where the bands possess a non-zero topological Chern number. This results in topological chiral edge states with opposite propagation directions at the upper and lower boundaries of the crystal. The two sets of opposite edge states undergo hybrid coupling within a d=1.5a coupling channel, forming a closed vortex energy flow distribution. This significantly cancels out the forward propagation momentum of photons, ultimately achieving a high-performance slow optical transmission mode with low group velocity and near-zero dispersion.

[0050] To achieve multi-frequency photon spatial separation and trapping, this embodiment uniformly divides the waveguide into six independent lattice regions along the electromagnetic wave propagation direction. The bias magnetic fields of the six regions increase sequentially from the incident end to the end, at 1000G, 1200G, 1400G, 1600G, 1800G, and 2000G respectively. Adjacent regions are completely isolated by five physical separation lines to prevent magnetic field crosstalk and spectral aliasing. The external magnetic field strength can linearly control the blue shift of the slow light dispersion curve. The higher the magnetic field strength, the greater the overall blue shift of the dispersion curve. Each gradient magnetic field uniquely corresponds to a set of zero group velocity trapping frequencies, forming a multi-frequency discrete trapping channel.

[0051] The device is surrounded by a perfectly matched layer boundary structure to absorb stray electromagnetic waves, eliminate interface reflection noise, and ensure the steady-state transmission quality of the electric field inside the waveguide. Multi-frequency composite electromagnetic wave packets are input from the left incident port of the device. Photons of different frequencies are automatically matched with the zero group velocity points in the corresponding gradient magnetic field range according to the dispersion matching condition, achieving spatial fixed-point local capture along the propagation direction and forming a typical topological rainbow effect.

[0052] This embodiment has the ability to synchronously tune the magnetic field across the entire domain. When the bias magnetic field of the six lattice regions is synchronously increased or decreased, the overall dispersion curve is shifted. The operating frequency band can be continuously adjusted within the range of 11.4 GHz to 12.6 GHz, and the effective tuning bandwidth is close to 10%, which is significantly better than traditional square lattice topology slow light devices.

[0053] Figure 3 The full-wave simulation results of multi-frequency electromagnetic waves incident on the device are used to fully demonstrate the overall electric field distribution, frequency correspondence, and local details of the device's static trapping of topological rainbow photons using a gradient magnetic field. This visually verifies that the segmented physical isolation structure can effectively suppress magnetic field coupling and photon spectral aliasing between adjacent lattice regions. Figure 3 (a) is the global electric field amplitude distribution of the entire coupled waveguide channel after electromagnetic wave packets carrying all six sets of capture frequencies are incident from the left port. It can be directly observed that photons of different frequencies separate from each other along the electromagnetic wave propagation path and are locally bound to the lattice region of the matching gradient magnetic field, which fully reflects the overall working effect of the topological rainbow capture in this embodiment. Figure 3 (b) is a schematic diagram of the multi-frequency incident wave packet composition and the capture position corresponding to each characteristic frequency. The spatial points corresponding to the six sets of capture frequencies and the six gradient magnetic field lattices are clearly marked, and the matching law between the gradient magnetic field and the photon capture position is clarified.

[0054] Figure 4 This is a detailed diagram of the steady-state local electric field of the overall structure in this embodiment. In the diagram, the electromagnetic energy is highly concentrated inside the corresponding lattice, and the electric field amplitude at the interface between adjacent intervals approaches zero. This confirms that the physical separation structure can completely block the mutual interference of the magnetic fields between intervals and prevent spectral aliasing of different captured photons.

[0055] This embodiment uses COMSOL Multiphysics finite element simulation software to numerically verify the transverse magnetic TM mode. Simulation results show that the dispersion curve of the coupled structure in this embodiment is generally flat without drastic fluctuations, the average group refractive index is approximately 10 across the entire momentum range, and the near-zero group velocity dispersion completely eliminates optical pulse distortion. The segmented isolation structure ensures independent photon capture in each region without spectral overlap. The topological edge states possess defect-immune transmission characteristics, significantly improving the device's operational stability and anti-interference capability. The overall structure is simple and compact, requiring no complex gradient processes, and is suitable for applications such as on-chip integrated optical buffers, wavelength division multiplexing, and microwave photonic storage.

[0056] 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.

Claims

1. A topological rainbow slow light trapping system based on a triangular lattice magneto-optical photonic crystal, characterized in that, include: A coupled slow-light waveguide substrate includes an upper triangular lattice magneto-optical photonic crystal and a lower triangular lattice magneto-optical photonic crystal arranged in parallel. A slow-light coupling transmission channel is formed between the lower boundary of the upper triangular lattice magneto-optical photonic crystal and the upper boundary of the lower triangular lattice magneto-optical photonic crystal. The slow-light coupling transmission channel is divided into six lattice regions with increasing bias magnetic field magnitudes along the electromagnetic wave propagation direction. Each lattice region is subjected to a different static bias magnetic field, and a separator line is provided between adjacent lattice regions. An incident position is provided on the left side of the coupled slow-light waveguide substrate for inputting electromagnetic wave packets containing multiple frequency components. The segmented gradient bias magnetic field loading module includes six independent magneto-optical photonic crystal units, each corresponding to one of the six lattice regions, for independently applying a corresponding bias magnetic field to each lattice region.

2. The topological rainbow slow light trapping system based on a triangular lattice magneto-optical photonic crystal according to claim 1, characterized in that, The six lattice regions are arranged sequentially from low magnetic field to high magnetic field along the direction of electromagnetic wave propagation. The bias magnetic field of the first lattice region (1) is 1000G, the bias magnetic field of the second lattice region (2) is 1200G, the bias magnetic field of the third lattice region (3) is 1400G, the bias magnetic field of the fourth lattice region (4) is 1600G, the bias magnetic field of the fifth lattice region (5) is 1800G, and the bias magnetic field of the sixth lattice region (6) is 2000G. The bias magnetic field of each lattice region corresponds to a uniquely matched capture frequency.

3. The topological rainbow slow light trapping system based on a triangular lattice magneto-optical photonic crystal according to claim 1, characterized in that, The higher the value of the bias magnetic field of each lattice region, the greater the overall blue shift of the corresponding slow light dispersion curve; after electromagnetic wave packets (7) of different frequencies are incident, photons of each frequency are bound to the corresponding matching lattice regions, forming a topological rainbow effect.

4. The topological rainbow slow light trapping system based on a triangular lattice magneto-optical photonic crystal according to claim 1, characterized in that, The bias magnetic field of each lattice region is configured to be synchronously adjusted up or down, so that the dispersion curve is synchronously shifted, and the operating frequency band is continuously tuned in the range of 11.4 GHz to 12.6 GHz.

5. A topological rainbow slow light trapping system based on a triangular lattice magneto-optical photonic crystal according to claim 1, characterized in that, Both the upper triangular lattice magneto-optical photonic crystal and the lower triangular lattice magneto-optical photonic crystal are composed of periodically arranged magneto-optical dielectric pillars (8).

6. A topological rainbow slow light trapping system based on a triangular lattice magneto-optical photonic crystal according to claim 5, characterized in that, The center-to-center spacing of the magneto-optical dielectric pillars (8) on both sides of the slow optical coupling transmission channel is fixed as the coupling spacing d = 1.5a, where a is the lattice constant.

7. A topological rainbow slow light trapping system based on a triangular lattice magneto-optical photonic crystal according to claim 5, characterized in that, The magneto-optical dielectric column (8) is made of yttrium iron garnet (Y3Fe5O3). 12 .

8. A method for controlling a topological rainbow magnetic field, applied to a topological rainbow slow light trapping system based on a triangular lattice magneto-optical photonic crystal according to any one of claims 1-7, characterized in that, include: Step 1: Prepare a coupled slow optical waveguide substrate with a fixed coupling spacing of d=1.5a, divide it into six gradient-increasing lattice regions along the electromagnetic wave propagation direction, and physically separate adjacent lattice regions with separator lines, and initialize the gradient magnetic field corresponding to each lattice region. Step 2: Electromagnetic wave packets (7) containing multiple frequency components are input from the left incident position of the coupled slow optical waveguide substrate, and photons of each frequency are statically captured at fixed points in each lattice region. Step 3: Synchronously adjust the magnitude of the bias magnetic field in all lattice regions to achieve continuous and adjustable operating frequency band.

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