Terahertz photoconductive antenna with efficient radiation

Abstract

The invention discloses a terahertz photoconductive antenna, and aims to significantly improve the radiation efficiency of the antenna by optimizing an electrode structure and introducing an electrode grating and a nanorod array. The photoconductive antenna comprises a regular hexagonal electrode, a periodically arranged nanorod array, an electrode grating and a graphene composite substrate. The regular hexagonal electrode structure has better symmetry, can balance radiation in all directions, and reduces signal attenuation and distortion. The nano-pillar array utilizes a surface plasmon effect to enhance a local electric field and improve radiation efficiency; the width and the period of the electrode grating are adjusted to further enhance the electric field intensity and optimize the radiation performance. The graphene composite substrate is composed of double-layer graphene, a transition metal disulfide interface enhancement layer and a silicon oxide substrate, high conductivity is provided, and electric field distribution is optimized. Through the structural optimization, the photoconductive antenna provided by the invention can provide efficient radiation performance in a terahertz wave band.

Description

Technical Field

[0001] The present invention relates to photoconductive antenna technology, and in particular to a terahertz photoconductive antenna with high-efficiency radiation, which is suitable for radiation, photoelectric detection and other high-frequency application fields in the terahertz band. Background Art

[0002] As an important terahertz light source, photoconductive antennas are widely used in ultra-high-speed communication, imaging, sensing and other fields. However, photoconductive antennas in existing technologies still have deficiencies in radiation efficiency, frequency band response and photoconductive properties.

[0003] In view of the deficiencies in the prior art, the present invention proposes a novel photoconductive antenna design scheme, which combines regular hexagonal electrodes, electrode gratings, nanocolumn arrays, and graphene composite substrate structures, and has significant advantages in improving radiation efficiency, frequency band response, and photoconductive properties. Summary of the invention

[0004] In view of the technical problems existing in the background technology, the present invention provides a terahertz photoconductive antenna with high radiation efficiency, which aims to effectively improve the radiation efficiency and band response of the photoconductive antenna by optimizing the electrode structure and introducing nanoarrays and graphene composite substrates. Through these structural optimizations, the photoconductive antenna of the present invention can provide high-efficiency radiation performance in the terahertz band.

[0005] Figure 1 As shown, the main elements in the embodiment of the present invention include electrodes, electrode gratings, substrates and nanorod arrays. The synergistic effect of these components enables the photoconductive antenna to achieve efficient radiation performance and excellent frequency band response. The specific description is as follows:

[0006] The main size parameters of each part are described as follows: 1) Electrode: the main size parameters are: regular hexagon with side length of l. 2) Nanocolumn array, the main size parameters are: unit column spacing distance c, width a, arrangement is perpendicular to the substrate plane, and arranged in a regular triangle pattern. 3) Electrode grating, the main size parameters are: length D, width s, height h and spacing b.

[0007] Furthermore, the electrode structure is designed as a regular hexagon, and the side length l of the regular hexagonal electrode can be adjusted to ensure that its radiation performance meets the requirements of the terahertz frequency band. By optimizing the side length of the electrode, the best radiation effect can be achieved in different frequency bands.

[0008] Furthermore, the nanocolumn array is arranged periodically, and the local electric field is enhanced through the surface plasmon effect, thereby improving the radiation efficiency.

[0009] Furthermore, the electrode grating generates a local electric field concentration effect by being arranged on the antenna surface, further enhancing the electric field strength, and by adjusting the length D, width s, height h and spacing d of the grating, the radiation effect can be effectively improved within the working frequency band of the antenna.

[0010] Figure 3 As shown, in the embodiment of the present invention, the substrate material is a graphene composite structure, which is composed of a graphene layer, a silicon oxide substrate and an interface enhancement layer. The specific parameters are as follows:

[0011] Furthermore, the graphene layer is a double-layer graphene structure, and graphene has a high electron mobility (10 4 cm 2 / V·s), the thickness of the double-layer graphene is 0.68nm, which provides excellent electrical conductivity, electron mobility and high-frequency response performance for current transmission and radiation.

[0012] Furthermore, the interface enhancement layer uses transition metal disulfide MoS2 to enhance the adhesion between graphene and the substrate, adjust the conductivity, optimize the distribution of the electric field, and improve the photoconductivity of the antenna.

[0013] Furthermore, the silicon oxide substrate, as an insulating material, provides a stable electrical isolation layer for the graphene layer.

[0014] The present invention has the following advantages:

[0015] Compared with traditional rectangular or prismatic electrodes, the regular hexagonal electrode structure can evenly distribute the electric field, thereby effectively improving the radiation efficiency of the antenna. The symmetry of the hexagonal structure helps to balance the radiation in all directions, reduce signal attenuation and distortion, and has better performance, especially in certain applications with high directivity requirements.

[0016] Comprehensive optimization of electrode grating and nanocolumn array: The electrode grating enhances the local effect of the electric field, while the nanocolumn array further enhances the electric field strength through the surface plasmon effect. The combination of the two generates a stronger electric field at the junction of the electrode and the array, greatly improving the radiation efficiency.

[0017] By optimizing the electrode structure and introducing electrode gratings and nanocolumn arrays, the present invention can significantly enhance the radiation efficiency of terahertz antennas. The periodic metal wire array of the electrode grating can effectively concentrate the electric field, and the synergistic effect of the electrode shape and the nanocolumn array further enhances the local electric field strength, ensuring efficient radiation of the antenna within the working frequency band.

[0018] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the present invention.

[0020] Figure 1 A schematic diagram of the three-dimensional structure of a photoconductive antenna in an embodiment of the present invention;

[0021] Figure 2 A top view of a photoconductive antenna and a nanorod array in an embodiment of the present invention;

[0022] Figure 3 A schematic cross-sectional view of a photoconductive antenna electrode grating in an embodiment of the present invention;

[0023] Figure 4 is a graph showing the variation of the photocurrent in the photoconductive antenna with the bias voltage in an embodiment of the present invention;

[0024] Figure 5 The time domain waveform of the photoconductive antenna in the embodiment of the present invention;

[0025] Description of reference numerals:

[0026] 1. Electrode; 2. Nanocolumn array; 3. Electrode grating; 4. Substrate; 5. Silicon hemispherical lens; 6. Base; 7. Voltage source; 8. Ground terminal; 9. Laser pulse; 10. Unit nanocolumn; 11. Electrode layer; 12. Graphene layer; 13. Interface enhancement layer; 14. Base layer. DETAILED DESCRIPTION

[0027] The following embodiments of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0028] Figure 1 The figure shows a three-dimensional structure schematic diagram of a photoconductive antenna of the present invention, the main structure of which includes:

[0029] The left and right electrodes 1 of the photoconductive antenna are located at the top of the structure. The nanorod array 2 is located between the two electrodes. The electrode grating 3 is embedded in the electrode surface. The substrate 4 is located below the electrode. The silicon hemispherical lens 5 is located at the bottom of the photoconductive antenna substrate. The base 6 provides the required voltage bottom support for the entire electrode. The voltage source 7 and the ground terminal 8 provide the required voltage for the electrode. The laser pulse 9 is injected from the top to excite the photoconductive antenna to generate or guide the optical signal.

[0030] The electrode 1 is located at the top. In this example, it is a new type of electrode structure, which is a regular hexagonal electrode structure. The specific parameters are: side length l=2 μm, and electrode thickness is 50 nm.

[0031] Figure 2 The figure shows a top view of the photoconductive antenna and nanocolumn array of the present invention, wherein the gap between the two electrodes is d=3μm, and a periodic nanocolumn array is arranged in the gap; the nanocolumns are made of gold, the nanocolumn array is perpendicular to the substrate surface, and is arranged in an equilateral triangle array, with a spacing of c=120nm between the nanocolumns; the dimensions of the unit nanocolumn 10 are an inner diameter a=40nm and a height of 100nm.

[0032] Figure 3 It is a schematic cross-sectional view of the photoconductive antenna electrode grating of the present invention. The parameters of the electrode grating 3 are given in this example: length D = 2 μm, width s = 200 nm, height h = 50 nm, and spacing b = 450 nm.

[0033] The electrode grating 3 is embedded in the substrate surface and works in synergy with the regular hexagonal electrode structure and the nanocolumn array 2. The regular hexagonal electrode structure improves the role of the grating structure in improving radiation efficiency by optimizing the electric field distribution, and the nanocolumn array further improves the electric field intensity through the surface plasmon effect. The synergy of the two improves the radiation efficiency and bandwidth response of the antenna.

[0034] Figure 3 As shown, the substrate material is a graphene composite structure, which consists of an electrode layer 11, a graphene layer 12, an interface enhancement layer 13 and a base layer 14. The specific data of the substrate material are as follows:

[0035] The electrode layer is made of gold Au, and has a thickness of h1 = 50 nm.

[0036] The graphene layer is a double-layer graphene structure with high electron mobility (10 4 cm 2 / V·s), the thickness of the double-layer graphene is h2=0.68nm.

[0037] The interface enhancement layer is MoS2, which is a two-dimensional transition metal disulfide composed of molybdenum Mo and sulfur S, and has a thickness of h3=0.65nm.

[0038] The base layer is silicon oxide SiO2, and the thickness is h4=150nm.

[0039] By combining the electrode layer, the graphene layer, the interface enhancement layer and the base layer layer by layer, the substrate composite structure in the present invention effectively improves the conductivity, radiation efficiency and frequency band response, and optimizes the overall performance of the photoconductive antenna.

[0040] In this embodiment, a laser pulse 9 with a pulse width of W = 50 fs, a frequency of f = 80 MHz, and a wavelength of λ = 0.8 μm is selected as the light source and propagates along the Z axis. The laser pulse is focused by a silicon hemispherical lens to enhance the light intensity of the beam and achieve a high-precision photoconductive response. At the same time, a bias voltage is provided for the photoconductive antenna electrode.

[0041] Figure 4 The figure shows the variation of the photocurrent in the photoconductive antenna with the bias voltage in the embodiment of the present invention. In the experiment, the variation of the photocurrent in the bias voltage range from 5V to 10V was recorded. The photocurrent of the photoconductive antenna in the present embodiment is significantly higher than that of the conventional photoconductive antenna. This enhanced photocurrent corresponds to a more powerful terahertz radiation performance.

[0042] Figure 5 The figure shows the time domain waveform of the photoconductive antenna in the embodiment of the present invention, which records the amplitude change within the time 0-1ps. The peak value of the photoconductive antenna in this embodiment increases by 32% compared with the conventional photoconductive antenna. The radiation performance of the photoconductive antenna in this embodiment is significantly better than that of the conventional photoconductive antenna.

[0043] The technical solution of the present invention is not limited to the above specific implementations. These implementations are only exemplary, and all variants with the same functions and technical effects are included in the protection scope of the present invention without departing from the basic technical concept of the present invention.

[0044] In addition, those skilled in the art may make various modifications to the implementation scheme or combine different constituent elements to create new implementation schemes without departing from the core concept of the present invention, which are also within the scope of the present invention.

Claims

1. A terahertz photoconductive antenna with high radiation efficiency, characterized in that: It includes an electrode, an electrode grating, a substrate and a nanocolumn array. The electrode structure is a regular hexagon. The nanocolumn array is perpendicular to the substrate plane and arranged in a regular triangle pattern. The electrode grating is arranged on the antenna surface. The substrate is a graphene composite structure consisting of a graphene layer, a silicon oxide substrate and an interface enhancement layer.

2. The terahertz photoconductive antenna with high radiation efficiency according to claim 1, characterized in that: The length of the side of the regular hexagon of the electrode is l, the spacing distance between the unit columns of the nanocolumn array is c, the width is a, and the length of the electrode grating is D, the width is s, the height is h, and the spacing is b.

3. The terahertz photoconductive antenna with high radiation efficiency according to claim 1, characterized in that: The graphene layer is a double-layer graphene structure with a thickness of 0.68 nm.

4. The terahertz photoconductive antenna with high radiation efficiency according to claim 1, characterized in that: The interface enhancement layer is made of transition metal disulfide MoS2.

5. The terahertz photoconductive antenna with high radiation efficiency according to claim 1, characterized in that: The thickness of the silicon oxide substrate is 150 nm.

6. The terahertz photoconductive antenna with high radiation efficiency according to claim 2, characterized in that: The electrode thickness is 50 nm.

7. The terahertz photoconductive antenna with high radiation efficiency according to claim 2, characterized in that: The length of the electrode regular hexagon is l=2μm, the gap between the two electrodes is d=3μm, the spacing between the nanocolumns is c=120nm, the inner diameter of the unit nanocolumn is a=40nm, the electrode grating length is D=2μm, the width is s=200nm, the height is h=50nm, and the spacing is b=450nm.

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