A mid-infrared modulator based on three-dimensional dirac semimetal enz phenomenon

Abstract

The application relates to a mid-infrared modulator based on a three-dimensional Dirac semimetal ENZ phenomenon, which comprises a dielectric fiber, a 3D DSM spacing layer and a metal substrate; the 3D DSM spacing layer is arranged above the metal substrate, and the dielectric fiber is deposited above the 3D DSM spacing layer. Compared with the prior art, the application has good tunable performance, multiple control modes and large modulation depth, can realize effective control of a mixed mode by changing temperature, can control the Fermi energy level by changing the bias voltage of the three-dimensional Dirac semimetal, and has low loss and strong constraint effect.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic materials and devices, and in particular to a mid-infrared modulator based on the three-dimensional Dirac semimetal ENZ phenomenon. Background Technology

[0002] Mid-infrared waves refer to wavelengths between 2.5-25 μm and frequencies between 400-4000 cm⁻¹. -1 Mid-infrared radiation is an electromagnetic wave between millimeter waves and infrared light. Since the vibrational resonances of most chemical substances occur in this band, mid-infrared technology is of great significance for various applications such as environmental gas sensing, biomedical diagnostics, hyperspectral imaging, and industrial process control. For example, many covalent bonds absorb radiation in the 600-4000 cm⁻¹ range. -1 Because molecules have different chemical bonds, mid-infrared "fingerprint spectroscopy" can be used to identify molecules and characterize their structures. Currently, there is a great demand for high-performance tunable plasma functional devices, and surface plasmonic waveguides are an important component in the design of high-performance tunable functional devices.

[0003] Surface plasmons are highly localized surface electromagnetic waves generated by the coupling of free electrons and photons in a metal. They propagate along the interface between the metal and the dielectric and can be manipulated at subwavelength levels. Hybrid-mode waveguides, as an important surface plasmon waveguide structure, mainly include dielectric fiber-dielectric gap-metal and dielectric-loaded metal hybrid plasmon structures, and have wide applications in the design of lasers, modulators, and filters. Compared to traditional metallic surface plasmon waveguides, hybrid-mode waveguides have the advantages of stronger confinement and lower loss, providing a good platform for designing tunable devices.

[0004] ENZ (epsilon-near-zero) materials are a class of novel materials whose real part of the dielectric constant is close to zero at one or more wavelengths. They possess optical properties such as near-infinite phase velocity, enhanced local electric field, and large nonlinear response, making them suitable for designing high-power metamaterial lenses, high-bandwidth absorbers, and low-loss optical switches. Currently, the ENZ phenomenon can be achieved over a wide frequency range from visible light to terahertz waves by utilizing different materials and structural designs. For example, in the mid-infrared band, polar crystals such as SiC and SiO2 exhibit significant ENZ responses near their phonon frequencies due to phonon resonance. Furthermore, topological half-metals, as a typical emerging material, also exhibit significant ENZ responses, such as two-dimensional graphene, three-dimensional Dirac half-metals (Na3Bi, Cd3As2), and Weyl half-metals (Eu2Ir2O7, TaAs). Three-dimensional Dirac semimetals, as a novel class of topological semimetals, possess ultra-high carrier mobility and Fermi velocity. Their dielectric constant can be dynamically tuned through doping, bias voltage, and temperature, making them suitable as control materials for designing high-performance tunable plasma devices. Due to the high energy of incident light in the mid-infrared band, interband transitions of electrons play a crucial role, thus affecting the transition frequency. Near the vicinity, the real part of the dielectric constant of the Dirac half-metal is close to zero, making it a typical ENZ material.

[0005] Based on the Au nanoantenna-ITO-SiO2-Tin multilayer structure, CKDass et al. achieved, in 2020, a second harmonic generation with an enhancement of approximately 50,000 times relative to the device's external performance, and near-perfect absorption (98%) with a bandwidth of approximately 245 nm at a thickness of about 1.55 μm, by utilizing an annealing process and the corresponding strong nonlinear response. In 2023, M. Liu et al. observed magnetization ENZ on a film with a thickness of λ / 40 by integrating a Si grating with a doped InAs film in multiple layers. Furthermore, this multilayer structure exhibited strong asymmetric absorption under a moderate external magnetic field of approximately 1.5 T, and its operating frequency and bandwidth could be easily controlled by changing the doping concentration of the InAs film.

[0006] Patent CN202210791866, published in 2022, discloses a mid-infrared all-optical modulator based on a graphene hybrid waveguide. In the mid-infrared band, based on a sapphire-silicon-chalcogenide-graphene waveguide structure, this modulator allows low-loss transmission of light in the 3-5 μm range and can achieve ultra-high-speed all-optical modulation by utilizing the saturable absorption effect of graphene. Patent CN202321381107, published in 2023, discloses a structure capable of achieving a strong nonlinear optical response over a wide bandwidth. This structure uses fluorine-doped tin oxide (FTO) as a thin film with a near-zero dielectric constant. Utilizing the strong coupling between the ENZ mode and the plasma mode of the FTO thin film, the nonlinear optical response of this structure can be enhanced by approximately 400 times in the near-infrared region.

[0007] Although there has been some research on graphene hybrid plasma waveguides, their tunability is greatly limited due to the thinness of the graphene film. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a mid-infrared modulator based on the ENZ phenomenon of a three-dimensional Dirac semimetal. It has good tunability, multiple control modes and large modulation depth. It can effectively control the mixing mode by changing the temperature and can control its Fermi level by changing the bias voltage of the three-dimensional Dirac semimetal. It has low loss and strong confinement effect.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] Compared to graphene, 3D DSM (three-dimensional Dirac half-metal) exhibits higher mobility and overcomes the limitation of very thin thickness in two-dimensional materials such as graphene, offering greater design freedom and higher stability. This invention achieves effective control of incident waves by adjusting the dielectric constant of the 3D DSM through changing the bias voltage or temperature.

[0011] This invention provides a mid-infrared modulator based on the three-dimensional Dirac semimetal ENZ phenomenon, comprising: a dielectric fiber, a 3D DSM spacer layer, and a metal substrate;

[0012] A 3D DSM spacer layer is disposed above a metal substrate, and dielectric fibers are deposited above the 3D DSM spacer layer.

[0013] Furthermore, the dielectric fiber is a semi-elliptical SiO2 dielectric fiber.

[0014] Furthermore, the cross-sectional area of ​​the semi-elliptical SiO2 dielectric fiber is 16 μm. 2 .

[0015] Furthermore, semi-elliptical SiO2 dielectric fibers are used to provide light confinement, with an ellipticity ratio of a... x / a y It is 0.1-1.

[0016] Furthermore, the metal substrate is an Au substrate.

[0017] Furthermore, the thickness of the Au substrate is 1 μm.

[0018] Furthermore, the thickness of the 3D DSM spacer layer ranges from 5 to 1000 nm.

[0019] Furthermore, the modulator adjusts the dielectric constant of the 3D DSM by regulating the temperature. When the temperature varies within the range of 77K-600K, the 3D DSM's switching frequency... The vicinity exhibits a clear ENZ phenomenon, and the propagation length of the mixed mode shows a significant abrupt change.

[0020] Furthermore, the 3D DSM spacer layer can control the Fermi level of the 3D DSM by changing the bias voltage. When the Fermi level changes in the range of 0.08 to 0.15 eV, the frequency corresponding to the peak position of the real part of the effective refractive index of the mixed mode can be controlled in the range of 21 THz to 38 THz, the peak value of the real part of the effective refractive index can be changed in the range of 1.8 to 3.5, and the abrupt change ratio of the propagation length can be adjusted between 3.8 and 45.3.

[0021] Furthermore, it also includes an electronic control unit and a temperature control unit. The electronic control unit is used to regulate the Fermi level of the 3D DSM, and the temperature control unit is used to regulate the temperature of the modulator.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) The mid-infrared modulator based on the ENZ phenomenon in three-dimensional Dirac semimetal proposed in this invention has the advantages of low loss and strong confinement effect. Its propagation length can reach 227.6μm in the mid-infrared band.

[0024] (2) The three-dimensional Dirac semimetal-supported hybrid plasma waveguide structure proposed in this invention can effectively control the hybrid mode by changing the temperature. In the mid-infrared band, due to the high energy of the incident wave, interband transitions in the 3DDSM play an important role in the frequency transition. A pronounced ENZ phenomenon is observed in the vicinity. When the temperature is between 77K and 600K, the abrupt change ratio of the propagation length of the mixing mode in the ENZ region can vary between 3.8 and 49.4, with a modulation depth exceeding 90%.

[0025] (3) The mid-infrared modulator based on the ENZ phenomenon in the three-dimensional Dirac semimetal proposed in this invention can control its Fermi level by changing the bias voltage of the three-dimensional Dirac semimetal. When the Fermi level is 0.08-0.15eV, the abrupt change ratio of the propagation length of the hybrid waveguide in the ENZ region can be adjusted within 3.81-45.3, and the peak value of the real part of the effective refractive index can be adjusted between 1.8-3.5, with the corresponding frequency varying between 21.3-38.2THz. Attached Figure Description

[0026] Figure 1 A schematic diagram of a mid-infrared modulator based on the three-dimensional Dirac semimetal ENZ phenomenon;

[0027] Figure 2 The diagram shows the modulator in Example 1 at different temperatures;

[0028] Figure 3 The diagram shows the modulator in Example 1 at different DSM Fermi levels;

[0029] Figure 4 The diagram shows the S-shaped three-dimensional structure of the modulator in Example 1 under different bending angles;

[0030] Figure 5 The diagram shows the Y-shaped three-dimensional structure of the modulator in Example 1 under different bending angles.

[0031] Figure reference numerals: 1-metal Au substrate; 2-3D DSM spacer layer; 3-semi-elliptical SiO2 dielectric fiber. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0033] Example 1

[0034] Compared to graphene, 3D DSM (three-dimensional Dirac half-metal) exhibits higher mobility and overcomes the limitation of very thin thickness in two-dimensional materials such as graphene, offering greater design freedom and higher stability. This invention achieves effective control of incident waves by adjusting the dielectric constant of the 3D DSM through changing the bias voltage or temperature.

[0035] This embodiment provides a mid-infrared modulator based on the three-dimensional Dirac semimetal ENZ phenomenon, such as... Figure 1 As shown, it includes: dielectric fiber, 3D DSM spacer layer 2, and metal substrate;

[0036] The 3D DSM spacer layer 2 is disposed above the metal substrate, and the dielectric fiber is deposited above the 3D DSM spacer layer 2.

[0037] In a specific embodiment, the dielectric fiber is a semi-elliptical SiO2 dielectric fiber 3.

[0038] In a specific embodiment, the cross-sectional area of ​​the semi-elliptical SiO2 dielectric fiber 3 is 16 μm. 2 .

[0039] In a specific embodiment, the semi-elliptical SiO2 dielectric fiber 3 is used to provide light confinement, and the ellipticity ratio ax / ay is 0.1-1.

[0040] In a specific embodiment, the metal substrate is a metal Au substrate 1.

[0041] In a specific embodiment, the thickness of the Au substrate is 1 μm.

[0042] In a specific implementation, the thickness of the 3D DSM spacer layer 2 ranges from 5 to 1000 nm.

[0043] In a specific implementation, the modulator adjusts the dielectric constant of the 3D DSM by regulating the temperature. When the temperature varies within the range of 77K-600K, the 3D DSM adjusts its switching frequency. The vicinity exhibits a clear ENZ phenomenon, and the propagation length of the mixed mode shows a significant abrupt change.

[0044] In a specific implementation, the 3D DSM spacer layer 2 can control the Fermi level of the 3D DSM by changing the bias voltage. When the Fermi level changes in the range of 0.08 to 0.15 eV, the frequency corresponding to the peak position of the real part of the effective refractive index of the mixed mode can be controlled in the range of 21 THz to 38 THz, the peak value of the real part of the effective refractive index can be changed in the range of 1.8 to 3.5, and the abrupt change ratio of the propagation length can be adjusted between 3.8 and 45.3.

[0045] In a specific implementation, it also includes an electronic control unit and a temperature control unit. The electronic control unit is used to regulate the Fermi level of the 3D DSM, and the temperature control unit is used to regulate the temperature of the modulator.

[0046] The propagation performance of the modulator can be simulated and analyzed using COMSOL simulation software. For example... Figure 1 As shown, the incident wave enters the waveguide structure and couples with electrons in the metal to excite surface plasmon resonances. Then, the plasmonic mode interacts with the dielectric fiber mode to generate a mixed mode. The dielectric constant of the three-dimensional Dirac half-metal can be effectively controlled by adjusting the temperature or bias voltage.

[0047] Figure 2The propagation performance of the hybrid plasma waveguide at different temperatures is shown in Figures 2(a), 2(b), 2(c), and 2(d), where 2(a), 2(b), 2(c), and 2(d) represent the real part of the effective mode refractive index, the normalized mode area, the propagation length, and the optimization factor, respectively. The results show that the propagation characteristics of the hybrid mode are closely related to temperature. At low temperatures, the real part of the effective refractive index (propagation length) of the hybrid mode exhibits a significant peak (valley) in the ENZ region. For example, at 77 K, the abrupt change ratio of the real part of the effective refractive index (propagation length) is 9.71 (49.4). Furthermore, when the temperature varies within the range of 77–600 K, the abrupt change ratio of the optimization factor of the hybrid mode in the ENZ region can be adjusted between 6.5 and 125.4, with a modulation depth exceeding 90%.

[0048] Figure 3 The effect of the Fermi level of a 3D DSM on waveguide propagation performance is shown. As the Fermi level increases, the peak value of the real part of the effective mode refractive index and the abrupt change ratio of the propagation length increase. For example, when the Fermi level varies in the range of 0.08 to 0.15 eV, the peak value of the real part of the effective mode refractive index increases from 1.84 to 3.5, and the abrupt change ratio of the propagation length increases from 3.8 to 45.3.

[0049] To better study the bending characteristics of the proposed three-dimensional DSM hybrid mode, Figure 4 The propagation characteristics of the S-shaped waveguide structure under different bending angles are demonstrated. As shown in the figure, when the bending angle varies from 1 to 10 degrees, the proposed waveguide bandwidth (transmittance greater than 75%) can reach 18.0 THz, and the corresponding peak transmittance can reach a maximum of 96%.

[0050] To investigate the wave distributive characteristics of the proposed Dirac semimetal-supported hybrid plasma waveguide, Figure 5 The propagation performance of the Y-shaped waveguide structure at different angles is demonstrated. As shown in the figure, the transmittance of the Y-shaped waveguide gradually increases with decreasing bending angle. When the bending angle is 30, 15, and 0 degrees, the corresponding peak transmittance can reach 66%, 75%, and 89%, respectively.

[0051] This embodiment uses a 3D DSM as the modulation medium. A hybrid plasma waveguide composed of a semi-elliptical SiO2 dielectric fiber 3, a 3D DSM spacer layer 2, and a metallic Au substrate 1 achieves low loss and a large modulation depth. Electrothermal dual control of the waveguide structure is achieved by adjusting either temperature or bias voltage. By adjusting the temperature within the range of 77-600K, the 3D DSM can achieve a switching frequency of [missing value]. The real part of the dielectric constant is close to zero, exhibiting a pronounced ENZ phenomenon. For example, at 77 K, the abrupt change ratio of the propagation length of the mixed mode in the ENZ region is 49.4, with a modulation depth exceeding 90%. Furthermore, by changing the bias voltage, when the Fermi level varies in the range of 0.08–0.15 eV, the frequency corresponding to the peak position of the real part of the effective refractive index of the mixed mode can shift from 21.3 THz to 38.2 THz; correspondingly, the abrupt change ratio of the propagation length can be adjusted between 3.81 and 45.3.

[0052] Components not described in detail in this embodiment are all existing components that can be purchased through public channels.

[0053] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A mid-infrared modulator based on the three-dimensional Dirac semimetal ENZ phenomenon, characterized in that, include: Dielectric fiber, 3D DSM spacer (2), metal substrate; The 3D DSM spacer layer (2) is disposed above the metal substrate, and the dielectric fiber is deposited above the 3D DSM spacer layer (2); The modulator controls the dielectric constant of the 3D DSM by adjusting the temperature. When the temperature varies in the range of 77K-600K, the 3D DSM exhibits a significant ENZ phenomenon near the conversion frequency, and the propagation length of the mixed mode shows a significant abrupt change.

2. A mid-infrared modulator based on the three-dimensional Dirac semimetal ENZ phenomenon according to claim 1, characterized in that, The dielectric fiber is a semi-elliptical SiO2 dielectric fiber (3).

3. A mid-infrared modulator based on the three-dimensional Dirac semimetal ENZ phenomenon according to claim 2, characterized in that, The cross-sectional area of ​​the semi-elliptical SiO2 dielectric fiber (3) is 16 µm. 2 .

4. A mid-infrared modulator based on the three-dimensional Dirac semimetal ENZ phenomenon according to claim 2, characterized in that, The semi-elliptical SiO2 dielectric fiber (3) is used to provide light confinement, and its ellipticity is greater than that of a. x / a y It is 0.1-1.

5. A mid-infrared modulator based on the three-dimensional Dirac semimetal ENZ phenomenon according to claim 1, characterized in that, The metal substrate is an Au substrate (1).

6. A mid-infrared modulator based on the three-dimensional Dirac semimetal ENZ phenomenon according to claim 5, characterized in that, The thickness of the Au substrate is 1 µm.

7. A mid-infrared modulator based on the three-dimensional Dirac semimetal ENZ phenomenon according to claim 1, characterized in that, The thickness of the 3D DSM spacer layer (2) ranges from 5 to 1000 nm.

8. A mid-infrared modulator based on the three-dimensional Dirac semimetal ENZ phenomenon according to claim 1, characterized in that, The 3D DSM spacer layer (2) can control the Fermi level of the 3D DSM by changing the bias voltage. When the Fermi level changes in the range of 0.08~0.15 eV, the frequency corresponding to the peak position of the real part of the effective refractive index of the mixed mode can be controlled in the range of 21 THz-38 THz, the peak value of the real part of the effective refractive index can be changed in the range of 1.8-3.5, and the abrupt change ratio of the propagation length can be adjusted between 3.8-45.

3.

9. A mid-infrared modulator based on the three-dimensional Dirac semimetal ENZ phenomenon according to claim 1, characterized in that, Also includes: The electronic control unit is used to regulate the Fermi level of the 3D DSM, and the temperature control unit is used to regulate the temperature of the modulator.

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