Absorption type terahertz direct modulator with zero reflection
Through the absorption terahertz direct modulator designed with a double-layer artificial microstructure, the combination of rectangular waveguide and modulation module solves the problem of low insertion loss and high isolation in the prior art, and achieves integration with front-end RF devices, and has strong frequency transplantation characteristics.
Patent Information
- Application Number
- CN202510037429.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-09
- Publication Date
- 2025-04-15
Smart Images
Figure CN119834904A_ABST
Abstract
Description
Technical Field The invention relates to the technical field of terahertz communication, and in particular to an absorption-type terahertz direct modulator with zero reflection. Background Art Terahertz waves refer to electromagnetic waves with a frequency spectrum between 0.1 and 10 THz. As an important candidate technology for the next generation of mobile communication technology for 6G, terahertz communication technology can meet the requirements of ultra-high transmission rates at the terabit level and has a very broad application scenario. As the core device of the terahertz direct communication system, the terahertz direct modulator realizes the information loading of the terahertz carrier by high-speed switching between the "on" and "off" states. At present, the terahertz direct modulator is mainly realized based on the principle of strong-weak resonance conversion and circuit topology structure. These methods cannot simultaneously achieve low insertion loss, high isolation and non-reflection terahertz modulation in terms of mechanism. [1][1-3] .
[0001] Zhang T, Zhang Y. On-chip thz dynamic manipulation based on tunablespoof surface plasmonpolaritons[J]. IEEE Electron Device Letters, 2019, 40(11): 1844-1847.
[0002] Zhang YX,Ding KS,Zeng HX,et al.Ultrafast modulation of terahertzwaves using on-chip dual-layernear-field coupling[J].Optica,2022,9(11):1268-1275.
[0003] C.Bi, S.Gong, K.Ding, H.Liang, Z.Yang and Y.Zhang, "A terahertz absorption modulator based on GaAs Schottky Diodes," 2024 49th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), Perth, Australia, 2024, pp.1-2, Summary of the invention In order to solve the above problems existing in the prior art, the present invention provides an absorptive terahertz direct modulator with zero reflection, which solves the problem that the existing direct modulator solutions are difficult to integrate with front-end radio frequency devices. The present invention proposes an absorptive terahertz direct modulator with zero reflection, which realizes the regulation of terahertz waves based on a double-layer artificial microstructure. The design method is simple and effective, and can realize reflection-free terahertz regulation with low insertion loss and high isolation. It provides a new design idea for the next generation 100Gbps terahertz communication system, which will effectively solve the problem that the existing direct modulator solution is difficult to integrate with the front-end RF device. An absorption-type terahertz direct modulator with zero reflection comprises a rectangular waveguide and a modulation module, wherein both ends of the rectangular waveguide are waveguide openings, the modulation module penetrates the rectangular waveguide cavity wall and is placed on the wide side of the rectangular waveguide in a manner that its surface is perpendicular to the waveguide opening surface, the modulation module comprises a filter unit and a modulation unit arranged between the filter units, a cross-shaped slot line transmission structure and a semiconductor control device arranged on the cross-shaped slot line transmission structure are arranged on the front of the modulation unit, a double-opening collar is arranged on the back of the modulation unit, the cross-shaped slot line transmission structure is provided with a cross-shaped slot line, and the double-opening collar corresponds to the position of the cross-shaped slot line. The double-opening sleeve ring is composed of two open rings with opening directions opposite to each other. Two double-opening collars are provided, and the two double-opening collars are mirror-imaged with the vertical part of the cross groove line as the axis. The vertical part of the cross-shaped slot line is parallel to the direction in which the modulation module penetrates the rectangular waveguide. Furthermore, there is only one double-opening ring, which corresponds to the middle portion of the cross-shaped slotted wire in the cross-shaped slotted wire transmission structure. Furthermore, the modulation module is composed of a substrate and a metal circuit structure arranged on both sides of the substrate, a filter unit and the cross-slot line transmission structure are provided on one side of the substrate, the semiconductor control device is fixed on the cross-slot line transmission structure, and the double-opening ring is arranged on the other side of the substrate. Furthermore, the substrate material may be any one of GaAs, SiC or GaN. Furthermore, when the rectangular waveguide adopts the WR-2.8 standard rectangular waveguide, the modulation module is located in the middle of the wide side of the rectangular waveguide. Furthermore, the modulation unit is inside the rectangular waveguide, and the filtering unit is outside the rectangular waveguide. Furthermore, the filtering unit is an I-shaped low-pass filter, which is a microstrip low-pass filter circuit, used for suppressing terahertz waves and feeding high-speed modulation signals. The two I-shaped filters are placed symmetrically with the rectangular waveguide as the axis; the external modulation signal is input from the I-shaped low-pass filter on one side, fed into the modulation unit, and then connected to the matching load through the I-shaped low-pass filter on the other side. Furthermore, the modulator operating frequency can be transplanted by adjusting the slot width and length of the cross-shaped slot line transmission structure. Furthermore, the cross-slot transmission structure is composed of symmetrically arranged transmission lines, the intervals between the transmission lines form the horizontal part of the cross-slot, opposite notches are provided on the opposite sides of the transmission lines, the notches of the two transmission lines form the vertical part of the cross-slot, and the horizontal part is parallel to the rectangular waveguide. Furthermore, the semiconductor control device is a terahertz Schottky diode, and the cathode and anode of the terahertz Schottky diode are respectively placed on the transmission lines on both sides of the horizontal part of the cross-shaped slot line transmission structure, with a total number of M, M≥2, the anodes of the terahertz Schottky diodes are on the same side, the cathodes are on the same side, and they are connected in parallel. By adjusting the number of terahertz Schottky diodes and the distance between them, the amplitude and operating frequency can be better adjusted to meet the design requirements. Furthermore, the open ring of the double open ring is any one of a circular open ring and a square open ring. Furthermore, the substrate material is any one of quartz, sapphire, silicon dioxide, gallium arsenide or silicon carbide. The beneficial effects of the present invention include: (1) The present invention realizes the control of the semiconductor control device through the change of voltage, forms a resonant state on the cross-shaped slot line, forms an absorption structure through the double open ring on the back, and realizes reflection-free absorption modulation (low return loss) while having a large modulation depth; (2) The present invention has a strong frequency migration characteristic, and the modulator operating frequency can be effectively adjusted by adjusting the spacing, position, size, etc. of each semiconductor control device; (3) The present invention adopts a double-open collar method to enhance the field binding effect when the modulator is disconnected to achieve non-reflection absorption modulation; (4) The present invention provides a method for realizing high-precision terahertz modulation, and facilitates integration with existing front-end RF devices. It also has high portability of the operating frequency band, can operate under normal temperature, normal pressure, and non-vacuum conditions, and is easy to package and use, and has a very wide range of application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 This is a schematic structural diagram of an absorptive terahertz direct modulator with zero reflection involved in an embodiment of the present application. Figure 2 This is a top view of an absorptive terahertz direct modulator with zero reflection involved in an embodiment of the present application. Figure 3 This is a schematic diagram of the structure of the modulation module involved in the embodiment of the present application. Figure 4 is the transmission coefficient S of the modulator in the on / off state involved in the embodiment of the present application 21 result. Figure 5 is the return loss S of the modulator in the on / off state involved in the embodiment of the present application 11 result. Reference numerals 1-input waveguide, 2-output waveguide, 3-modulation module, 31-first filtering unit, 32-cross slot transmission structure, 33-semiconductor control device, 34-second filtering unit, 35-double open ring. DETAILED DESCRIPTION In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. An absorptive terahertz direct modulator with zero reflection, such as Figure 1-2 As shown, it includes a rectangular waveguide and a modulation module 3, wherein both ends of the rectangular waveguide are waveguide openings, the modulation module 3 penetrates the rectangular waveguide cavity wall and is placed on the wide side of the rectangular waveguide in a manner that its surface (the top surface of the modulation module 3) is perpendicular to the waveguide opening surface, the modulation module 3 includes a filtering unit and a modulation unit arranged between the filtering units, the front of the modulation unit is provided with a cross-shaped slot line transmission structure 32 and a semiconductor control device 33 arranged on the cross-shaped slot line transmission structure 32, and the back of the modulation unit is provided with a double-opening ring 35, and the double-opening ring 35 corresponds to the cross-shaped slot line position of the cross-shaped slot line transmission structure 32. The double-opening collar 35 is composed of two open rings with opposite opening directions, and the open rings are circular open rings. Two double-opening collars 35 are provided, and the two double-opening collars 35 are arranged in mirror image with the vertical part of the cross groove line as the axis. The vertical portion of the cross-shaped slot line is parallel to the direction in which the modulation module 3 penetrates the rectangular waveguide. The rectangular waveguide adopts the WR-2.8 standard rectangular waveguide, the rectangular waveguide at one end of the modulation module 3 is the input waveguide 1 for inputting the terahertz wave, and the rectangular waveguide at the other end of the modulation module 3 is the output waveguide 2 for outputting the modulated terahertz envelope signal. In another embodiment, there is only one double-opening ring 35, which corresponds to the middle portion of the cross-shaped slot line transmission structure 32, and is suitable for terahertz modulation above 500 GHz. In another embodiment, if Figure 3 As shown, the modulation module 3 is composed of a substrate and a metal circuit structure arranged on both sides of the substrate. Figure 3 (a) is provided with a cross-shaped slot line transmission structure 32 of two filter units and a resonant unit, the two filter units are a first filter unit 31 and a second filter unit 34, the semiconductor control device 33 is fixed on the cross-shaped slot line transmission structure 32, and the double open ring 35 of the resonant unit is provided on the other side of the substrate, i.e. Figure 3 In (b), the material of the substrate is quartz. The filtering unit is an I-shaped low-pass filter, which is a microstrip low-pass filter circuit, and is used for suppressing terahertz waves and feeding high-speed modulation signals. The two I-shaped filters are placed symmetrically with the rectangular waveguide as the axis; the external modulation signal is input from the I-shaped low-pass filter on one side, fed into the modulation unit, and then connected to the matching load through the I-shaped low-pass filter on the other side. In another embodiment, the substrate material may be any one of GaAs, SiC or GaN. In another embodiment, when the rectangular waveguide adopts the WR-2.8 standard rectangular waveguide, the modulation module 3 is located in the middle of the wide side of the rectangular waveguide. The modulation unit is inside the rectangular waveguide, and the filtering unit is outside the rectangular waveguide. In another embodiment, the modulator operating frequency can be transplanted by adjusting the slot width and length of the cross-shaped slot line transmission structure 32 . In another embodiment, the cross-slot transmission structure 32 is composed of symmetrically arranged transmission lines, the intervals between the transmission lines form the horizontal part of the cross-slot, and opposite notches are provided on the opposite sides of the transmission lines. The notches of the two transmission lines form the vertical part of the cross-slot, and the horizontal part is parallel to the rectangular waveguide. In another embodiment, the material of the transmission line is metal, and the metal involved in the entire modulator can be Ag, Cu, or Al. In another embodiment, the semiconductor control device 33 is a terahertz Schottky diode, and the cathode and anode of the terahertz Schottky diode are respectively placed on the transmission lines on both sides of the horizontal part of the cross-shaped slot line transmission structure 32, with a total number of M, M≥2, the anodes of the terahertz Schottky diodes are on the same side, the cathodes are on the same side, and they are connected in parallel. By adjusting the number of terahertz Schottky diodes and the distance between them, the amplitude and operating frequency can be better adjusted to meet the design requirements. In another embodiment, the semiconductor control device 33 may be any one of a PIN diode and a field effect transistor. In another embodiment, the open ring of the double open ring 35 is a square open ring. In another embodiment, the substrate material is any one of quartz, sapphire, silicon dioxide, gallium arsenide or silicon carbide. The embodiment of the present invention is based on the principle of field absorption by a double-open collar 35, and combines a semiconductor control device 33, a cross-shaped slot line transmission structure 32, and a modulation module 3 composed of a filter unit to realize the control function of the terahertz wave. The terahertz wave with the main mode of TE10 is fed into the standard WR2.8 waveguide, and the modulation module 3 implements the control of the TE10 wave. When the modulation module 3 is turned on, the modulator is in the on state, and the terahertz wave can be transmitted; when the modulation module 3 is turned off, the terahertz wave cannot be transmitted. Based on this, the control function of the terahertz wave is realized. What is important is that when the modulator is disconnected, the terahertz wave is bound in the back double-open collar 35 through the joint action of the cross-shaped slot line and the semiconductor control device 33 to achieve phase cancellation. As a result, the present invention realizes reflection-free terahertz absorption modulation at a lower loss and a larger modulation depth. The simulation results are as follows Figure 4-5 As shown. Specifically: Figure 4 The middle grey curve is the insertion loss curve when the modulator is turned on, and the red curve is the isolation curve when the modulator is turned off. For this embodiment, the optimal operating point is around 336 GHz, with a minimum insertion loss of 2.4 db and an isolation of 24.5 db. The good performance regulation effect above 300 GHz is achieved thanks to the modulation module 3, the front cross groove and the back double complementary ring form a strong resonant absorption structure, which is achieved under the regulation of the Schottky diode. Figure 5 The middle grey curve is the return loss curve when the modulator is turned on, and the red curve is the return loss curve when the modulator is turned off. For this embodiment, the bandwidth that satisfies the return loss less than 15db when the modulator is turned on or off is 30GHz, and this result shows the excellent characteristics of the modulation module 3. Thanks to this, a very low return loss can be achieved even with a maximum isolation of 24.5db for the modulator. The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.
Claims
1. An absorptive terahertz direct modulator with zero reflection, characterized in that: It comprises a rectangular waveguide and a modulation module, wherein both ends of the rectangular waveguide are waveguide openings, the modulation module penetrates the rectangular waveguide cavity wall and is placed on the wide side of the rectangular waveguide in a manner that its surface is perpendicular to the waveguide opening surface, the modulation module comprises a filter unit and a modulation unit arranged between the filter units, a cross-shaped slot line transmission structure and a semiconductor control device arranged on the cross-shaped slot line transmission structure are arranged on the front of the modulation unit, a double-opening collar is arranged on the back of the modulation unit, the cross-shaped slot line transmission structure is provided with a cross-shaped slot line, and the double-opening collar corresponds to the position of the cross-shaped slot line.
2. The zero-reflection absorption terahertz direct modulator according to claim 1, characterized in that: The double-opening sleeve ring is composed of two open rings with opening directions opposite to each other.
3. The zero-reflection absorption terahertz direct modulator according to claim 1, characterized in that: It comprises two double-opening collars, which are mirror-set with the vertical part of the cross-shaped groove line as the axis, and the vertical part of the cross-shaped groove line is parallel to the direction in which the modulation module penetrates the rectangular waveguide.
4. The zero-reflection absorption terahertz direct modulator according to claim 1, characterized in that: There is only one double-opening collar, which corresponds to the middle part of the cross-slotted transmission structure.
5. The zero-reflection absorption terahertz direct modulator according to claim 1, characterized in that: The modulation module consists of a substrate and a metal circuit structure arranged on both sides of the substrate. The metal circuit structure on one side of the substrate includes a filter unit and the cross-slot line transmission structure. The semiconductor control device is fixed on the cross-slot line transmission structure. The metal circuit structure on one side of the substrate is a double open ring.
6. The zero-reflection absorption-type terahertz direct modulator according to claim 5, characterized in that: The substrate material can be any one of GaAs, SiC or GaN.
7. The zero-reflection absorption-type terahertz direct modulator according to claim 5, characterized in that: When the rectangular waveguide adopts the WR-2.8 standard rectangular waveguide, the modulation module is in the middle of the wide side of the rectangular waveguide, the modulation unit is inside the rectangular waveguide, and the filtering unit is outside the rectangular waveguide.
8. The zero-reflection absorption-type terahertz direct modulator according to claim 1, characterized in that: The cross-slot transmission structure is composed of symmetrically arranged transmission lines, the intervals between the transmission lines form the horizontal part of the cross-slot, the opposite sides of the transmission lines are provided with facing notches, the notches of the two transmission lines form the vertical part of the cross-slot, and the horizontal part is parallel to the rectangular waveguide.
9. The zero-reflection absorption-type terahertz direct modulator according to claim 1, characterized in that: The semiconductor control device is a terahertz Schottky diode, and the cathode and anode of the terahertz Schottky diode are respectively placed on both sides of the cross-shaped slot line transmission structure, with a total number of M, M≥2, and the anodes and cathodes of the terahertz Schottky diodes are on the same side and the cathodes are on the same side, in a parallel connection mode.
10. The zero-reflection absorption-type terahertz direct modulator according to claim 1, characterized in that: The working frequency of the modulator can be transplanted by adjusting the width and length of the cross-shaped slot line.