Dual-mode plasmonic modulator

Abstract

The application discloses a dual-mode artificial surface plasmon modulator, comprising: top metal layer, first dielectric layer, floor layer, adhesive layer, second dielectric layer and bottom metal layer which are stacked in sequence from top to bottom; a plurality of even-mode SSPP units in the top metal layer are loaded with even-mode varactor diodes, the dispersion characteristics of the even-mode SSPP units are dynamically controlled by adjusting the bias voltage, and continuous phase modulation of the even-mode is realized; the floor layer is etched with odd-mode central groove and symmetrical groove to form periodically arranged odd-mode SSPP units, the bottom metal layer excites odd-mode SSPP waves through odd-mode coupling circular holes, and odd-mode varactor diodes are loaded to dynamically control the dispersion characteristics of the odd-mode SSPP, and amplitude modulation of the odd-mode is realized. The odd-mode and the even-mode electromagnetic waves can be orthogonally transmitted in parallel, and the dispersion control of the two modes is independent and does not interfere with each other. The application makes full use of the advantages of adjustable dispersion and mode orthogonality of the artificial surface plasmon, realizes dual-mode parallel independent control on a single transmission line, and solves the problems that the existing SSPP modulator is difficult to simultaneously support multi-mode independent control and compact design.

Description

Technical Field

[0001] This invention relates to the field of microwave and millimeter-wave device design technology, and in particular to a dual-mode artificial surface plasmon modulator. Background Technology

[0002] A modulator is an important microwave control device that can regulate parameters such as the amplitude and phase of a signal. It plays a core role in systems such as signal modulation, beamforming, phased array antennas, and wireless communication. Modulators are designed to help systems achieve flexible manipulation of electromagnetic waves to meet the signal processing capabilities and system integration requirements of different applications.

[0003] In recent years, with the rapid development of communication technology, higher demands have been placed on the functional integration and transmission capacity of microwave devices. Supporting parallel transmission of multiple modes on a single transmission line and independently controlling each mode can significantly improve channel capacity and signal processing capabilities, and is an important way to solve the problem of scarce spectrum resources. However, most traditional modulators only support single-mode transmission and control, making it difficult to achieve orthogonal parallel transmission and independent control of multiple modes on a single transmission line simultaneously. A few multi-mode solutions suffer from problems such as high crosstalk between modes, poor control independence, or complex structures that are not conducive to integration.

[0004] Artificial surface plasmons (ASPs) are periodic structures that support surface wave mode transmission in the microwave and millimeter-wave bands, exhibiting excellent properties such as low transmission loss, strong field confinement, and tunable dispersion. Through multilayer structural design, ASPs can support orthogonal parallel transmission of odd-mode and even-mode electromagnetic waves. Furthermore, by independently loading tunable elements onto the transmission layers corresponding to different modes, the dispersion characteristics of different modes can be independently controlled, providing a new approach for the design of high-performance multimode independently tunable devices. Summary of the Invention

[0005] Purpose of the invention: This invention provides a dual-mode artificial surface plasmon modulator that overcomes the problem that existing modulators cannot simultaneously support multi-mode orthogonal parallel transmission and independent control on a single transmission line.

[0006] Technical Solution: The present invention discloses a dual-mode artificial surface plasmon modulator, comprising: a top metal layer, a first dielectric layer, a ground layer, an adhesive layer, a second dielectric layer, and a bottom metal layer stacked sequentially from top to bottom; even-mode varactor diodes are loaded between several even-mode SSPP units in the top metal layer, and the dispersion characteristics of the even-mode SSPP units are dynamically controlled by adjusting the bias voltage to achieve continuous phase modulation of the even modes; the ground layer is etched with odd-mode center slots and symmetrical slots to form periodically arranged odd-mode SSPP units; the bottom metal layer excites odd-mode SSPP waves through odd-mode coupling circular holes, and loads odd-mode varactor diodes to dynamically control the dispersion characteristics of the odd-mode SSPPs to achieve amplitude modulation of the odd modes.

[0007] Furthermore, the top metal layer includes a top 50Ω microstrip line, a transition structure, several even-mode SSPP units, an even-mode choke structure, an even-mode negative electrode feed structure, an even-mode positive electrode feed structure, and an even-mode varactor diode. The top 50Ω microstrip line is connected to the even-mode SSPP units through the transition structure to excite the even-mode SSPP wave and achieve impedance matching. The even-mode varactor diode is laterally connected between adjacent even-mode SSPP units. By applying a bias voltage through the even-mode positive electrode feed structure, the bias voltage of the even-mode varactor diode is changed to adjust its capacitance value, thereby achieving dynamic control and phase modulation of the even-mode SSPP dispersion. The negative terminal of the even-mode varactor diode is connected to the ground plane through a via of the even-mode negative electrode feed structure to form a DC loop. The even-mode choke structure is used to isolate the DC control signal from the RF signal.

[0008] Furthermore, several even-mode SSPP units are arranged periodically, including a central conductor, parallel stubs, and gaps; the parallel stubs are symmetrically loaded on both sides of the central conductor; adjacent even-mode SSPP units are physically isolated by gaps to achieve electrical connection.

[0009] Furthermore, the floor layer includes a central groove for odd-mode, a circular hole for odd-mode coupling, and odd-mode SSPP units; the central groove for odd-mode extends along the length of the floor layer, and symmetrical grooves are symmetrically etched on both sides of the central groove for odd-mode, forming periodically arranged odd-mode SSPP units.

[0010] Furthermore, the bottom metal layer includes a bottom 50Ω microstrip line, an odd-mode coupled wafer, an odd-mode choke structure, an odd-mode positive feed structure, an odd-mode negative feed structure, an odd-mode feed conduction band, and an odd-mode varactor diode. The bottom 50Ω microstrip line and the odd-mode coupled wafer are coupled through an odd-mode coupled circular aperture to excite an odd-mode SSPP wave, realizing the conversion between the bottom microstrip line mode and the odd-mode SSPP mode. The odd-mode varactor diode is connected across the odd-mode feed conduction band and the odd-mode negative feed structure. A bias voltage is applied through the odd-mode positive feed structure and the odd-mode feed conduction band to dynamically control the odd-mode SSPP dispersion characteristics and achieve amplitude modulation. The negative terminal of the odd-mode varactor diode is connected to the ground plane through a via of the odd-mode negative feed structure to form a DC loop. The odd-mode choke structure is used to isolate the DC control signal from the RF signal.

[0011] Furthermore, the even-mode choke structure adopts a fan-shaped stub structure, and the odd-mode choke structure adopts a symmetrical double-fan-shaped stub structure, both of which are used to suppress the interference of radio frequency signals on the DC bias network and achieve isolation between DC control signals and radio frequency signals.

[0012] Furthermore, the top and bottom metal layers are made of copper, the first and second dielectric layers are made of Rogers RT 5880, and the adhesive layer is made of Rogers RO 4450B.

[0013] Furthermore, within the 13.5GHz to 15.5GHz frequency band, by independently adjusting the bias voltage of the even-mode varactor diode, the even mode can achieve a continuous phase shift of more than 270°, realizing 2-bit phase modulation; by independently adjusting the bias voltage of the odd-mode varactor diode, the odd mode can achieve switching between on and off states, realizing 1-bit amplitude modulation; the adjustment of odd and even modes is independent of each other and does not interfere with each other.

[0014] Beneficial Effects: Compared with the prior art, the present invention has the following significant advantages: The present invention provides a dual-mode artificial surface plasmon modulator, which, by adopting a design combining a double-layer dielectric structure with an etched grooved ground plane, simultaneously supports the orthogonal parallel transmission of odd-mode and even-mode electromagnetic waves on a single transmission line; wherein, even-mode varactor diodes are loaded between the even-mode SSPP units in the top metal layer, and the dispersion characteristics of the even-mode SSPPs are dynamically controlled by adjusting the bias voltage to achieve continuous phase modulation of the even mode; the odd-mode SSPP grooves are etched in the ground plane, and the bottom metal layer is coupled through circular holes to excite the odd-mode SSPPs. This invention generates a singular-mode SSPP wave and loads a singular-mode varactor diode to dynamically control the dispersion characteristics of the singular-mode SSPP, thereby achieving amplitude modulation of the singular mode. Since the electromagnetic field distributions of the singular and even modes are orthogonal to each other, and their dispersion control is achieved by varactor diodes independently loaded on different metal layers, the control of the two modes does not interfere with each other, resulting in good mode isolation. This invention achieves parallel independent control of dual modes on a single transmission line, combining the advantages of multi-mode transmission, independent control, and compact design, and solves the technical problem that existing modulators cannot simultaneously support multi-mode independent control and miniaturized design. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the modulator structure of the present invention.

[0016] Figure 2 This is a schematic diagram of the SSPP unit structure of the present invention.

[0017] Figure 3 This is a schematic diagram illustrating the effect of the capacitance value of the varactor diode of the present invention on the unit dispersion characteristics.

[0018] Figure 4 The simulation diagram shows the reflection coefficient and transmission coefficient of the even mode under different diode conditions according to the present invention.

[0019] Figure 5 This is a simulation diagram of the phase shift of the even mode under different diode states according to the present invention.

[0020] Figure 6 This is a simulation diagram of the transmission coefficient of the odd mode under different diode states according to the present invention.

[0021] Figure 7 This is a simulation diagram of the isolation between odd and even modes of the diode under different conditions according to the present invention.

[0022] The components are as follows: 1. Top metal layer; 2. First dielectric layer; 3. Ground layer; 4. Adhesive layer; 5. Second dielectric layer; 6. Bottom metal layer; 11. Top 50Ω microstrip line; 12. Transition structure; 13. Even-mode SSPP unit; 131. Center conductor; 132. Parallel stub; 133. Gap; 14. Even-mode choke structure; 15. Even-mode negative electrode feed structure; 16. Even-mode positive electrode feed structure; 17. Even-mode varactor diode; 31. Odd-mode center slot; 32. Odd-mode coupling circular hole; 33. Odd-mode SSPP unit; 331. Symmetrical slot; 61. Bottom 50Ω microstrip line; 62. Odd-mode coupling disc; 63. Odd-mode choke structure; 64. Odd-mode positive electrode feed structure; 65. Odd-mode negative electrode feed structure; 66. Odd-mode feed conductor; 67. Odd-mode varactor diode. Detailed Implementation

[0023] like Figure 1 As shown, a dual-mode artificial surface plasmon modulator includes, from top to bottom, a top metal layer 1, a first dielectric layer 2, a ground layer 3, an adhesive layer 4, a second dielectric layer 5, and a bottom metal layer 6. This multilayer structure can simultaneously support the orthogonal parallel transmission of both odd-mode and even-mode electromagnetic waves, and the dispersion characteristics of the two modes can be independently controlled without interference.

[0024] like Figure 2 As shown, the top metal layer 1 includes a top 50Ω microstrip line 11, a transition structure 12, several even-mode SSPP units 13, an even-mode choke structure 14, an even-mode negative electrode feed structure 15, an even-mode positive electrode feed structure 16, and an even-mode varactor diode 17. The top 50Ω microstrip line 11 is disposed at both ends of the even-mode SSPP units 13 for exciting and receiving even-mode SSPP signals. The transition structure 12 is a matching transformation section that connects the top 50Ω microstrip line 11 and the even-mode SSPP units 13 to achieve impedance matching between them.

[0025] The even-mode SSPP unit 13 includes a central conductor 131, parallel stubs 132, and a slot 133. The parallel stubs 132 are symmetrically loaded on both sides of the central conductor 131 and extend outward from the central conductor. Several even-mode SSPP units 13 are arranged periodically, and adjacent even-mode SSPP units 13 are physically isolated by the slots 133 and electrically connected by electromagnetic coupling through the slots.

[0026] Even-mode varactor diodes 17 are laterally connected between adjacent even-mode SSPP cells 13. Specifically, even-mode varactor diodes 17 are bridged across the gap 133 between the center conductive strips 131 of adjacent cells. The anode of even-mode varactor diodes 17 is biased through even-mode anode feed structure 16, and the cathode is connected to the ground plane 3 through a via via even-mode cathode feed structure 15, forming a complete DC bias circuit. To simplify the bias network, the anode feed lines of each even-mode varactor diode converge at the edge of the dielectric layer for unified DC feed.

[0027] The even-mode choke structure 14 is set in the DC bias network and adopts a fan-shaped stub structure to suppress the interference of AC radio frequency signals on the DC bias network and realize the isolation between DC control signals and radio frequency signals.

[0028] The ground plane 3 includes an odd-mode central groove 31, an odd-mode coupling circular hole 32, and odd-mode SSPP units 33. The odd-mode central groove 31 extends along the length of the ground plane 3. The odd-mode SSPP units 33 include the odd-mode central groove 31 and symmetrical grooves 331. The symmetrical grooves 331 are etched on both sides of the odd-mode central groove 31 and are symmetrically distributed to form periodically arranged odd-mode SSPP units 33. The odd-mode coupling circular holes 32 are disposed at both ends of the ground plane 3 to realize the coupling conversion between the bottom signal and the odd-mode SSPP mode.

[0029] The bottom metal layer 6 includes a bottom 50Ω microstrip line 61, an odd-mode coupling disc 62, an odd-mode choke structure 63, an odd-mode positive electrode feed structure 64, an odd-mode negative electrode feed structure 65, an odd-mode feed conduction band 66, and an odd-mode varactor diode 67. The bottom 50Ω microstrip line 61 and the odd-mode coupling disc 62 are disposed below the odd-mode coupling circular aperture 32, and are electromagnetically coupled through the odd-mode coupling circular aperture 32 to excite an odd-mode SSPP wave, realizing the conversion between the bottom microstrip line mode and the odd-mode SSPP mode.

[0030] The odd-mode feed conductor 66 extends along the length of the bottom metal layer 6 and connects to the odd-mode positive feed structure 64. An odd-mode varactor diode 67 is connected between the odd-mode feed conductor 66 and the odd-mode negative feed structure 65. One end of the odd-mode varactor diode 67 is connected to the odd-mode feed conductor 66, and the other end is connected to the ground plane layer 3 via a via through the odd-mode negative feed structure 65, forming a DC circuit. The bias voltage is uniformly input through the odd-mode positive feed structure 64 and distributed to each odd-mode varactor diode 67 via the odd-mode feed conductor 66.

[0031] The odd-mode choke structure 63 is set in the DC bias network and adopts a symmetrical double-fan-shaped stub structure to suppress the interference of radio frequency signals on the DC bias network and realize the isolation between DC control signals and radio frequency signals.

[0032] In this embodiment, the top metal layer 1 and the bottom metal layer 6 are made of copper, the first dielectric layer 2 and the second dielectric layer 5 are made of Rogers RT 5880, and the adhesive layer 4 is made of Rogers RO 4450B. The main parameter settings of the modulator are shown in Table 1.

[0033] Table 1 SSPP Modulator Parameter Settings

[0034]

[0035] The working principle of the even-mode SSPP unit is as follows: The even-mode signal is fed in through the top 50Ω microstrip line 11, and after impedance matching through the transition structure 12, it excites the even-mode SSPP wave. The even-mode SSPP wave propagates along the periodic even-mode SSPP unit 13 of the top metal layer 1. Its electromagnetic field is mainly concentrated in the first dielectric layer 2, and the electric field is evenly symmetrically distributed about the ground layer 3. When different DC bias voltages are applied through the even-mode positive electrode feeding structure 16, the even-mode varactor diode 17 exhibits different capacitance values, changing the equivalent circuit parameters of the even-mode SSPP unit 13, thereby dynamically controlling the dispersion characteristics of the even-mode SSPP and realizing phase modulation.

[0036] like Figure 3 As shown on the left, the capacitance values ​​C of different even-mode varactor diodes are solved using the CST intrinsic mode solver. even Simulations were performed using an even-mode SSPP element to obtain the even-mode dispersion curve. It can be observed that the dispersion curve of the even-mode SSPP changes with the capacitance value, and the phase constant at a fixed frequency point changes accordingly, thus generating a continuously adjustable phase difference. It is also noted that the capacitance value C of the odd-mode varactor diode... odd The change does not affect the dispersion curve of the even mode, demonstrating the independent control capability of the dispersion of the odd and even modes.

[0037] like Figure 4 As shown, the S-parameters of the even-mode SSPP modulator under different bias conditions were simulated using the CST time-domain solver. The simulation results show that within the operating frequency band of 13.5 GHz to 15.5 GHz, the reflection coefficient of the even mode is below -10 dB, and the transmission coefficient remains above -4 dB, indicating that the even mode has good impedance matching and transmission efficiency.

[0038] like Figure 5 As shown, the phase shift simulation results of the even mode under different bias conditions show that the phase shift of the even mode is greater than 270° in the working frequency band, which can achieve 2-bit phase modulation.

[0039] The working principle of the odd-mode SSPP unit is as follows: The odd-mode signal is fed in through the bottom 50Ω microstrip line 61. Through the electromagnetic coupling effect of the odd-mode coupling disc 62 and the odd-mode coupling aperture 32, the bottom microstrip line mode is converted into the odd-mode SSPP mode. The odd-mode SSPP wave propagates along the periodic odd-mode SSPP unit 33 on the ground plane 3. Its electromagnetic field is oddly symmetrically distributed about the ground plane 3, and the electric field is mainly concentrated in the second dielectric layer 5 and the first dielectric layer 2, with opposite directions on both sides of the ground plane. When different DC bias voltages are applied through the odd-mode positive electrode feeding structure 64, the odd-mode varactor diode 67 exhibits different capacitance values, changing the equivalent circuit parameters of the odd-mode SSPP unit 33, thereby dynamically controlling the dispersion characteristics of the odd-mode SSPP. By controlling the bias voltage to switch the odd-mode varactor diode 67 between specific capacitance values, the transmission characteristics of the odd-mode SSPP can be made to be in a conducting or cut-off state within the operating frequency band, realizing 1-bit amplitude modulation.

[0040] like Figure 3 As shown on the right, the capacitance C of different odd-mode varactor diodes is solved using the CST eigenmode solver. odd Simulations were performed on the odd-mode SSPP unit to obtain the odd-mode dispersion curve. It can be observed that the dispersion curve and cutoff frequency of the odd-mode SSPP change significantly with the capacitance value, and the transmission characteristics at a fixed frequency point can switch from conduction to cutoff. It is also noted that the capacitance value C of the even-mode varactor diode... even The change does not affect the dispersion curve of the odd mode, demonstrating the independent control capability of the dispersion of the odd and even modes.

[0041] like Figure 6 As shown, the transmission coefficient of the odd-mode SSPP modulator under different bias conditions is simulated using the CST time-domain solver. The simulation results show that within the operating frequency band, the transmission coefficient of the odd mode exhibits two distinct states: conduction and cutoff. The transmission coefficient is higher in the conduction state and significantly lower in the cutoff state, achieving a good 1-bit amplitude modulation effect.

[0042] like Figure 7 As shown, the isolation between odd and even modes is simulated. The simulation results show that the isolation between odd and even modes is greater than 30dB within the operating frequency band, indicating that the two modes have good isolation. This is due to the orthogonal electromagnetic field distributions of the odd and even modes, and the dispersion control of the two modes is achieved by varactor diodes independently loaded on different metal layers, so the transmission and control of the two modes do not interfere with each other.

[0043] In summary, the dual-mode artificial surface plasmon modulator of this invention achieves orthogonal parallel transmission and independent control of odd and even modes through a multi-layer structure design and independent loading of varactor diodes on different mode transmission layers. Within the 13.5 GHz to 15.5 GHz frequency band, the even mode can achieve a continuous phase shift of greater than 270°, completing 2-bit phase modulation; the odd mode can switch between on and off states, completing 1-bit amplitude modulation; the two modes have good isolation and do not interfere with each other.

Claims

1. A dual-mode artificial surface plasmon modulator, characterized in that, include: The top metal layer (1), first dielectric layer (2), ground layer (3), adhesive layer (4), second dielectric layer (5), and bottom metal layer (6) are stacked sequentially from top to bottom. A varactor diode (17) is loaded between several even-mode SSPP units (13) in the top metal layer (1). The dispersion characteristics of the even-mode SSPP units (13) are dynamically controlled by adjusting the bias voltage to achieve continuous phase modulation of the even mode. The ground layer (3) is etched with odd-mode center groove (31) and symmetrical groove (331) to form periodically arranged odd-mode SSPP units (33). The bottom metal layer (6) excites the odd-mode SSPP wave through the odd-mode coupling circular hole (32) and loads the odd-mode varactor diode (67) to dynamically control the dispersion characteristics of the odd-mode SSPP to achieve amplitude modulation of the odd mode.

2. The dual-mode artificial surface plasmon modulator as described in claim 1, characterized in that, The top metal layer (1) includes a top 50Ω microstrip line (11), a transition structure (12), several even-mode SSPP units (13), an even-mode choke structure (14), an even-mode negative electrode feed structure (15), an even-mode positive electrode feed structure (16), and an even-mode varactor diode (17); the top 50Ω microstrip line (11) is connected to the even-mode SSPP unit (13) through the transition structure (12) to excite the even-mode SSPP wave and achieve impedance matching; the even-mode varactor diode (17) The even-mode varactor diode (17) is horizontally connected between adjacent even-mode SSPP units (13). The bias voltage is applied through the even-mode positive electrode feeding structure (16) to change the bias voltage of the even-mode varactor diode (17) and regulate its capacitance value, thereby realizing the dynamic control and phase modulation of the even-mode SSPP dispersion. The negative electrode of the even-mode varactor diode (17) is connected to the ground plane (3) through the even-mode negative electrode feeding structure (15) via a through hole to form a DC circuit. The even-mode choke structure (14) is used to realize the isolation between the DC control signal and the radio frequency signal.

3. The dual-mode artificial surface plasmon modulator as described in claim 3, characterized in that, Several even-mode SSPP units (13) are arranged periodically, including a central conductor (131), parallel stubs (132) and a gap (133); the parallel stubs (132) are symmetrically loaded on both sides of the central conductor (131); adjacent even-mode SSPP units (13) are physically isolated by the gap (133) to achieve electrical connection.

4. The dual-mode artificial surface plasmon modulator as described in claim 1, characterized in that, The floor layer (3) includes a quirk center groove (31), a quirk coupling circular hole (32), and a quirk SSPP unit (33). The quirk center groove (31) extends along the length of the floor layer (3), and symmetrical grooves (331) are symmetrically etched on both sides of the quirk center groove (31) to form periodically arranged quirk SSPP units (33).

5. The dual-mode artificial surface plasmon modulator as described in claim 1, characterized in that, The bottom metal layer (6) includes a bottom 50Ω microstrip line (61), an odd-mode coupling disc (62), an odd-mode choke structure (63), an odd-mode positive electrode feeding structure (64), an odd-mode negative electrode feeding structure (65), an odd-mode feeding conduction band (66), and an odd-mode varactor diode (67). The bottom 50Ω microstrip line (61) and the odd-mode coupling disc (62) are coupled through an odd-mode coupling circular hole (32) to excite an odd-mode SSPP wave, thereby realizing the conversion between the bottom microstrip line mode and the odd-mode SSPP mode. The odd-mode varactor diode (67) is connected between the odd-mode feed conduction band (66) and the odd-mode negative electrode feed structure (65). The bias voltage is applied through the odd-mode positive electrode feed structure (64) and the odd-mode feed conduction band (66) to dynamically adjust the dispersion characteristics of the odd-mode SSPP and realize amplitude modulation. The negative electrode of the odd-mode varactor diode (67) is connected to the ground plane (3) through the odd-mode negative electrode feed structure (65) via a through hole to form a DC circuit. The odd-mode choke structure (63) is used to realize the isolation between the DC control signal and the radio frequency signal.

6. The dual-mode artificial surface plasmon modulator as described in claim 2 or 5, characterized in that, The even-mode choke structure (14) adopts a fan-shaped stub structure, and the odd-mode choke structure (63) adopts a symmetrical double-fan-shaped stub structure. Both are used to suppress the interference of radio frequency signals on the DC bias network and realize the isolation between DC control signals and radio frequency signals.

7. The dual-mode artificial surface plasmon modulator as described in claim 2 or 5, characterized in that, The top metal layer (1) and the bottom metal layer (6) are made of copper, the first dielectric layer (2) and the second dielectric layer (5) are made of RogersRT 5880, and the adhesive layer (4) is made of Rogers RO 4450B.

8. The dual-mode artificial surface plasmon modulator as described in claim 1, characterized in that, Within the 13.5GHz to 15.5GHz frequency band, by independently adjusting the bias voltage of the even-mode varactor diode (17), the even mode can achieve a continuous phase shift of more than 270°, realizing 2-bit phase modulation; by independently adjusting the bias voltage of the odd-mode varactor diode (67), the odd mode can achieve switching between on and off states, realizing 1-bit amplitude modulation; the regulation of odd and even modes is independent of each other and does not interfere with each other.

Images