Efficiency enhanced broadband high-power light guide microwave generating device based on resonance adjustment

Abstract

The invention provides an efficiency-enhanced broadband high-power light guide microwave generation device based on resonance adjustment, which comprises a light guide switch and an adjustable radio frequency transmission structure, and is characterized in that the adjustable radio frequency transmission structure comprises a mobile feed structure, a gradient coaxial transmission line and an output connector; the photoconductive switch, the mobile feed structure, the gradient coaxial transmission line and the output connector are coaxially arranged; the device is of a vertical structure, through the resonance enhancement principle, the output power in the designed frequency band is remarkably improved, the bandwidth range of the device can be expanded to 0.25-2.8 GHz at most, the output efficiency is high, remarkable resonance enhancement at the low frequency position can be achieved by adjusting the overall position of the photoconductive switch and the feed structure, and the output power at the 0.6 GHz position can be improved to 138.6% of the original output power. The broadband high-power light guide device not only ensures broadband high-power output, but also improves the output efficiency at a low-frequency position, and provides a brand-new way for further development of simultaneously realizing broadband and high-power output for the broadband high-power light guide device.

Description

Technical Field

[0001] The invention belongs to the technical field of high-power microwaves, and in particular relates to an efficiency-enhanced broadband high-power photoconductive microwave generating device based on resonance regulation. Background Art

[0002] High-power microwave sources are widely used in pulse radar, continuous wave radar, charged particle radio frequency accelerator, plasma heating, and directed energy system applications. In previous studies, high-power microwave sources based on pulse power devices and relativistic electric vacuum devices have been fully developed, but there are still problems such as large equipment size, single output frequency, and difficulty in adjustment. Electron beam-free solid-state high-power microwave devices enable the system to develop towards high efficiency, miniaturization, and compactness. In recent years, with the continuous exploration of microwave photonics and wide bandgap semiconductor materials, photoconductive radio frequency technology realized by linear wide bandgap photoconductive semiconductors and tunable laser sources has received widespread attention. The high-power microwaves it outputs have the advantages of ultra-wideband, low loss, small time jitter, adjustable frequency pulse width, anti-electromagnetic interference, and small size and weight.

[0003] Photoconductive semiconductor devices are one of the key components of photoconductive RF / microwaves. The third-generation semiconductors have excellent properties such as wide bandgap, high electron saturation drift velocity, high carrier mobility, high critical breakdown field strength and high thermal conductivity. In recent years, the characteristics and applications of third-generation semiconductors such as SiC and GaN in the field of photoconductive RF have been widely studied. The device configuration is divided into vertical electrode configuration and horizontal electrode configuration. Among them, the SiC photoconductive device with vertical electrode configuration has a stronger voltage bearing capacity, and its electrode spacing determines the device's pressure bearing capacity and device response speed. At present, significant progress has been made in the use of SiC photoconductive devices with vertical electrode configuration to generate frequency-adjustable high-power microwaves, including improvements in output power and device life.

[0004] The main challenge facing this type of photoconductive microwave device is to achieve a wider adjustable frequency range while maintaining high power output. According to existing research, the output power of a typical vertical photoconductive device can reach hundreds of kW to MW level, but its frequency response capability is limited, and the above output power index can be achieved between about 0.5 GHz and 1.5 GHz. Although some studies (such as GaN photoconductive devices or planar photoconductive devices) have demonstrated a larger bandwidth, their output power is only at the kW level, and the material defect density and flashover breakdown of the planar electrode limit further output power increases. In short, vertically configured SiC photoconductive devices are still irreplaceable in high-power application scenarios. How to achieve a wider tuning range while maintaining a higher power output is a key problem that needs to be solved urgently.

[0005] Vertical photoconductive devices can be divided into two parts. One is the photoconductive RF generation part that includes the SiC substrate, usually called a photoconductive switch (Photoconductive Semiconductor Switch, PCSS), and the other is the photoconductive RF transmission part from the outside of the PCSS to the load end, that is, the RF transmission structure. The limitation of the existing technology is that the RF transmission structure of the photoconductive device is usually relatively fixed, and usually one structure can only achieve higher power output within a certain frequency range, which leads to the need to produce multiple structures for different application requirements. The device processing cost and disassembly complexity limit the further development of the system towards large-scale and multi-functional applications. Considering that the bandwidth and gain upper limit of a single configuration are mutually constrained (pf 2 Therefore, changing the RF transmission structure parameters to make the device gain more at different frequencies is an effective way to improve the overall electrical efficiency of the system and expand the bandwidth. Summary of the invention

[0006] In order to solve the technical problem of bandwidth / gain trade-off, the present invention proposes an efficiency-enhanced broadband high-power photoconductive microwave generating device based on resonance regulation, including a photoconductive switch and an adjustable radio frequency transmission structure, wherein the adjustable radio frequency transmission structure includes a mobile feeding structure, a tapered coaxial transmission line and an output connector;

[0007] The photoconductive switch, movable feeding structure, tapered coaxial transmission line and output connector are coaxially arranged; the photoconductive switch is arranged in the movable feeding structure; one end of the movable feeding structure is embedded in the tapered coaxial transmission line and can move axially relative to the tapered coaxial transmission line; the output connector is arranged at the output end of the tapered coaxial transmission line; the input end of the photoconductive switch is connected to the input connector, the output end of the photoconductive switch is connected to the output connector, the output end of the output connector is inserted into the annular socket of the output connector and can move axially relative to the output connector.

[0008] The photoconductive switch comprises a semi-insulating semiconductor substrate, a hollow metal electrode positive electrode, a hollow metal electrode negative electrode, and a packaging structure. The semi-insulating semiconductor substrate adopts a wide bandgap doped semi-insulating semiconductor material. A circular transparent electrode and an annular composite metal electrode are plated on the light incident surface of the semi-insulating semiconductor substrate, and a reflective silver layer and an annular composite metal electrode are plated on the backlight surface. The annular composite metal electrode on the light incident surface of the semi-insulating semiconductor substrate is connected to the input connector through the hollow metal electrode positive electrode, and the annular composite metal electrode on the backlight surface of the semi-insulating semiconductor substrate is connected to the output connector through the hollow metal electrode negative electrode. A packaging structure is arranged outside the photoconductive switch.

[0009] The input connector and the output connector are smooth hollow cylindrical metal structures.

[0010] The packaging structure includes an insulating packaging plate and insulating glue, wherein the insulating packaging plate is arranged outside the semi-insulating semiconductor substrate, the positive electrode of the hollow metal electrode, and the negative electrode of the hollow metal electrode; the insulating packaging plate is filled with insulating glue. The input connector and the output connector are connected to the positive electrode of the hollow metal electrode and the negative electrode of the hollow metal electrode respectively through the connection holes reserved on the insulating packaging plate.

[0011] When high peak power laser is incident on the substrate from the positive electrode of the photoconductive switch, the conductivity of the substrate is modulated by the incident laser, thereby generating a modulated high voltage electrical signal on the negative electrode of the photoconductive switch, and the voltage on the negative electrode is output to the load through the adjustable RF transmission structure.

[0012] The mobile feeding structure comprises a mobile feeding structure outer conductor, a mobile feeding structure inner conductor and a capacitor. The mobile feeding structure outer conductor is a cylindrical metal structure, the mobile feeding structure inner conductor is a circular metal electrode, the mobile feeding structure inner conductor is arranged in the mobile feeding structure outer conductor and is coaxially arranged; the inner ring of the mobile feeding structure inner conductor is connected to the input connector; the capacitor is connected between the mobile feeding structure outer conductor and the mobile feeding structure inner conductor.

[0013] Considering that when the incident laser modulates the conductivity of the photoconductive switch, the instantaneous voltage in the circuit is very large, which will cause the inter-stage voltage to be unstable. The voltage on the voltage divider resistor (load) can be maintained unchanged by capacitor discharge.

[0014] Furthermore, the capacitor is formed by connecting several sub-capacitors in parallel to form a parallel capacitor, one terminal of each sub-capacitor is connected to the grounding weld of the outer conductor of the mobile feeding structure, and the other terminal is connected to the inner conductor of the mobile feeding structure, and several sub-capacitors are arranged in a circular array with equal spacing. Alternatively, a circular capacitor or a patch inductor can also be used to store energy in order to reduce the volume.

[0015] When the photoconductive device is working, the output end of the high-voltage DC power supply is connected to the far end of the input connector, thereby providing a charging path for the parallel capacitor; when the incident laser modulates the conductivity of the photoconductive switch, the energy stored in the parallel capacitor will be quickly released and work together with the DC power supply to provide stable power supply for the photoconductive switch and its subsequent loads; compared with the method of directly using a DC power supply to feed, this design more effectively improves the stability of the output voltage, especially when the photoconductive device works under high repetition rate or long pulse conditions, it can significantly reduce voltage fluctuations and ensure reliable operation of the system.

[0016] The tapered coaxial transmission line is a cylindrical metal material structure, including an outer conductor of the tapered coaxial transmission line and an outer conductor of a stepped transmission line arranged along the axis inside. A circular blind hole is provided between the outer conductor of the tapered coaxial transmission line and the outer conductor of the stepped transmission line. One end of the outer conductor of the mobile feeding structure is inserted into the circular blind hole and tightly combined to ensure the stability of mechanical strength and electrical performance. The radius of the outer conductor of the stepped transmission line decreases step by step from the input end to the output end. The inner radius of the outer conductor of the first transmission line is the inner radius of the circular blind hole, that is, the inner radius of the outer conductor of the mobile feeding structure, and the length is the distance from the input port of the tapered coaxial transmission line to the first step plane. The inner radius of the outer conductor of the second transmission line and the outer conductor of the third transmission line decreases in sequence. The size of each section is optimized by simulation parameters to ensure that the tapered characteristics meet specific radio frequency transmission performance requirements. If there is a need for fine-tuning, the axial length can be accurately adjusted through the step-by-step nested structure of each section of the transmission line, thereby optimizing the impedance matching of the transmission line. In order to avoid tip discharge and breakdown caused by field concentration at the connection of the transmission lines, the connection is designed as a chamfered stepped structure.

[0017] In order to ensure the stable connection between the outer conductor of the tapered coaxial transmission line, the outer conductor of the mobile feeding structure and the ground, a bronze spring is installed on the outer wall of the outer conductor of the mobile feeding structure to increase the contact area between the outer conductor of the tapered coaxial transmission line and the outer conductor of the mobile feeding structure. At the same time, a hole is opened on the outer conductor of the tapered coaxial transmission line, and the outer conductor of the tapered coaxial transmission line is connected to the ground wire using screws.

[0018] The output connector includes an output connector outer conductor, an annular dielectric inner ring, an output connector inner conductor, a fixed probe and an annular dielectric sleeve; the output connector outer conductor is connected to the outer conductor of the tapered coaxial transmission line, the annular dielectric inner ring is arranged in the output connector outer conductor, and the output connector inner conductor is arranged in the annular dielectric inner ring; the fixed probe is connected to the input end of the output connector inner conductor to prevent flashover breakdown on the surface of the output connector inner conductor; the annular dielectric sleeve is connected to the annular dielectric inner ring, and a circular plug hole is formed between the fixed probe and the annular dielectric sleeve, the circular plug hole penetrates into the annular dielectric inner ring, and the output end of the output connector is inserted into the circular plug hole of the output connector; a bronze spring is installed on the outer surface of the fixed probe to increase the contact area with the output connector. The dielectric material of the annular dielectric inner ring and the annular dielectric sleeve is the same.

[0019] Beneficial effects of the present invention:

[0020] The present invention constructs a resonance-adjustable efficiency-enhanced broadband high-power photoconductive microwave generating device. The device is a vertical configuration. Through the resonance enhancement principle, after optimization, the output power in the designed frequency band is significantly improved. Its bandwidth range can be extended to 0.25 to 2.8 GHz at most. In addition, the output efficiency, especially when there is a clear demand for low-frequency output power, can achieve significant resonance enhancement at low frequencies by adjusting the positions of the photoconductive switch and the feeding structure as a whole, and the output power at 0.6 GHz can be increased to 138.6% of the original. This structure not only ensures high-power output in a wide band (especially at high frequencies), but also further improves the output efficiency at low frequencies. This resonance frequency adjustment method provides a new way for broadband high-power photoconductive devices to further develop towards achieving both wide bandwidth and high-power output. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the device of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure of the photoconductive switch of the present invention;

[0023] Figure 3 It is a front view schematic diagram of the mobile feeding structure of the present invention;

[0024] Figure 4 This is a schematic diagram of the mobile feeding structure of the present invention;

[0025] Figure 5 It is a schematic diagram of the structure of the tapered coaxial transmission line of the present invention;

[0026] Figure 6 This is a schematic diagram of the output connector structure of the present invention;

[0027] Figure 7 Schematic diagram of an equivalent circuit of the device of the present invention;

[0028] Figure 8 Frequency response curves of devices with different configurations under maximum light intensity incident conditions;

[0029] Fig. 9 Frequency response curves of devices with different configurations under different light intensity incident conditions;

[0030] 1. Photoconductive switch 11, semi-insulating semiconductor substrate 12, hollow metal electrode positive electrode 13, hollow metal electrode negative electrode 14, insulating packaging plate 15, insulating glue;

[0031] 2. Mobile feeding structure 21, mobile feeding structure outer conductor 22, mobile feeding structure inner conductor 23, sub-capacitor 24, grounding weld 25, bronze shrapnel;

[0032] 3. Gradient coaxial transmission line 31, gradient coaxial transmission line outer conductor 32, stepped transmission line outer conductor 33, annular blind hole 34, screws;

[0033] 4. Output connector 41, output connector outer conductor 42, annular dielectric inner ring 43, output connector inner conductor 44, conductor fixing probe 45, annular dielectric sleeve 46, and annular jack;

[0034] 5. Input connector 6. Output connector. DETAILED DESCRIPTION

[0035] like Figure 1 As shown, this embodiment proposes an efficiency-enhanced broadband high-power photoconductive microwave generating device based on resonance regulation, including a photoconductive switch 1 and an adjustable radio frequency transmission structure, wherein the adjustable radio frequency transmission structure includes a mobile feeding structure 2, a tapered coaxial transmission line 3 and an output connector 4;

[0036] The photoconductive switch 1, the mobile feeding structure 2, the tapered coaxial transmission line 3 and the output connector 4 are coaxially arranged; the photoconductive switch 1 is arranged in the mobile feeding structure 2; one end of the mobile feeding structure 2 is embedded in the tapered coaxial transmission line 3 and can move axially relative to the tapered coaxial transmission line 3; the output connector 4 is arranged at the output end of the tapered coaxial transmission line 3; the input end of the photoconductive switch 1 is connected to the input connector 5, the output end of the photoconductive switch 1 is connected to the output connector 6, the output end of the output connector 6 is inserted in the circular ring jack 46 of the output connector 4, and can move axially relative to the output connector 4.

[0037] like Figure 2 As shown, the photoconductive switch 1 comprises a semi-insulating semiconductor substrate 11, a hollow metal electrode positive electrode 12, a hollow metal electrode negative electrode 13, and a packaging structure. The semi-insulating semiconductor substrate 11 adopts a wide bandgap doped semi-insulating semiconductor material, and the substrate of this embodiment adopts a V-doped 6H-SiC material; a circular transparent electrode and an annular composite metal electrode are plated on the light incident surface of the semi-insulating semiconductor substrate 11, and a reflective silver layer and an annular composite metal electrode are plated on the backlight surface. In this embodiment, the material of the circular transparent electrode is AZ, and the material of the annular composite metal electrode is Cu-Pt-Al-Ti-Ni; the annular composite metal electrode on the light incident surface of the semi-insulating semiconductor substrate 11 is connected to the input connector 5 through the hollow metal electrode positive electrode 12, and the annular composite metal electrode on the backlight surface of the semi-insulating semiconductor substrate 11 is connected to the output connector 6 through the hollow metal electrode negative electrode 13; and a packaging structure is arranged outside the photoconductive switch 1.

[0038] The input connector 5 and the output connector 6 are smooth hollow cylindrical metal structures.

[0039] The packaging structure includes an insulating packaging plate 14 and an insulating glue 15. The insulating packaging plate 14 is arranged outside the semi-insulating semiconductor substrate 11, the hollow metal electrode positive electrode 12, and the hollow metal electrode negative electrode 13. The insulating packaging plate 14 is made of nylon material and plays the role of overall fixing and supporting protection; the insulating packaging plate 14 is filled with insulating glue 15, and the insulating glue 15 is made of Dow Corning material, which plays the role of protecting the electrode and the substrate and preventing electrical breakdown around the electrode. The input connector 5 and the output connector 6 are connected to the hollow metal electrode positive electrode 12 and the hollow metal electrode negative electrode 13 through the connection holes reserved on the insulating packaging plate 14. In this embodiment, considering that the photoconductive switch 1 will move synchronously with the adjustable radio frequency transmission structure part, it is necessary to ensure its reliable connection with the front and rear structures. In order to avoid the electrode applying excessive force to the substrate during the pushing process to cause damage, or the separation problem between the electrode and the substrate during the stretching, matching thread structures are designed between the input connector 5 and the insulating packaging plate 14 at the positive electrode of the switch, and the output connector 6 and the insulating packaging plate 14 at the negative electrode of the switch. The components are relatively fixed through threaded connection.

[0040] When high peak power laser is incident on the substrate from the positive electrode of the photoconductive switch 1, the conductivity of the substrate is modulated by the incident laser, thereby generating a modulated high voltage electrical signal on the negative electrode of the photoconductive switch 1, and the voltage thereon is output to the load through the adjustable RF transmission structure.

[0041] like Figure 3 , 4 As shown, the mobile feeding structure 2 includes a mobile feeding structure outer conductor 21, a mobile feeding structure inner conductor 22 and a capacitor. The mobile feeding structure outer conductor 21 is a cylindrical metal structure, and the mobile feeding structure inner conductor 22 is a circular metal electrode with an outer diameter of D. In this embodiment, D=12mm. The mobile feeding structure inner conductor 22 is arranged in the mobile feeding structure outer conductor 21 and is coaxially arranged; the inner circle of the mobile feeding structure inner conductor 22 is connected to the input connector 5; the capacitor is connected between the mobile feeding structure outer conductor 21 and the mobile feeding structure inner conductor 22. The distance from the connection between the capacitor and the mobile feeding structure inner conductor 22 to the output end of the mobile feeding structure 2 is L4, and the distance from the connection between the capacitor and the mobile feeding structure inner conductor 22 to the input end of the mobile feeding structure 2 is L5. In this embodiment, L4=25mm, L5=8mm.

[0042] Considering that when the incident laser modulates the conductivity of the photoconductive switch 1, the instantaneous voltage in the circuit is very large, which will cause the inter-stage voltage to be unstable. The voltage on the voltage divider resistor (load) can be maintained unchanged by capacitor discharge. In this embodiment, the capacitor is formed by six sub-capacitors 23 connected in parallel to form a parallel capacitor. One terminal of each sub-capacitor 23 is connected to the grounding weld 24 of the outer conductor 21 of the mobile feeding structure, and the other terminal is connected to the inner conductor 22 of the mobile feeding structure. The six sub-capacitors 23 are arranged in a circular array with equal spacing.

[0043] The capacitor specifications are selected based on the following: the load resistance is known to be 50 ohms. When the expected peak-to-peak output power is 1 MW, the theoretical peak current output is about 140 A, and the pulse width of the output electric pulse is about 30 ns. The voltage source needs to have an output voltage capability of 20 kV. Assuming that the voltage change of 1 kV can be ignored at this time, the overall capacitance of the parallel capacitor should be no less than 4.2 nF. When 6 sub-capacitors 23 are used, the capacitance value of each sub-capacitor 23 should be no less than 0.7 nF.

[0044] In this embodiment, the capacitance value of each sub-capacitor 23 is 1 nF.

[0045] When the photoconductive device is working, the output end of the high-voltage DC power supply is connected to the far end of the input connector 5, thereby providing a charging path for the parallel capacitor; when the incident laser modulates the conductivity of the photoconductive switch 1, the energy stored in the parallel capacitor will be quickly released and work together with the DC power supply to provide stable power supply for the photoconductive switch 1 and its subsequent loads; compared with the method of directly using a DC power supply to feed, this design more effectively improves the stability of the output voltage, especially when the photoconductive device works under high repetition rate or long pulse conditions, it can significantly reduce voltage fluctuations and ensure reliable operation of the system.

[0046] like Figure 5 As shown, the tapered coaxial transmission line 3 is a cylindrical metal material structure, including a tapered coaxial transmission line outer conductor 31 and a stepped transmission line outer conductor 32 arranged along the axis inside. A circular blind hole 33 is provided between the tapered coaxial transmission line outer conductor 31 and the stepped transmission line outer conductor 32. One end of the mobile feeding structure outer conductor 21 is inserted into the circular blind hole 33 and is tightly combined to ensure the stability of mechanical strength and electrical performance; the radius of the stepped transmission line outer conductor 32 decreases step by step from the input end to the output end, and the inner diameter of the first transmission line outer conductor is the inner radius R1 of the circular blind hole 33 (that is, the mobile feeding structure outer conductor 21 The inner radius of the tapered coaxial transmission line 3 is the distance L1 from the input port of the tapered coaxial transmission line 3 to the first step plane. In this embodiment, R1=17mm and L1=4mm. The inner radii of the outer conductor of the second transmission line and the outer conductor of the third transmission line are R2 and R3, respectively, and the lengths are L2 and L3, respectively. In this embodiment, R2=13mm, R3=7mm, L2=10mm, and L3=12mm. The dimensions of each segment are optimized by simulation parameters to ensure that the tapered characteristics meet specific RF transmission performance requirements. If there is a need for fine-tuning, the axial length can be precisely adjusted through the step-by-step nested structure of each segment of the transmission line, thereby optimizing the impedance matching of the transmission line. In order to avoid tip discharge and breakdown caused by concentrated field strength at the connection of the transmission line, the connection is designed as a chamfered stepped structure with a chamfer radius of 1mm.

[0047] In order to ensure the stable connection between the outer conductor 31 of the tapered coaxial transmission line, the outer conductor 21 of the mobile feeding structure and the ground, a bronze spring 25 is installed on the outer wall of the outer conductor 21 of the mobile feeding structure to increase the contact area between the outer conductor 31 of the tapered coaxial transmission line and the outer conductor 21 of the mobile feeding structure. At the same time, a hole is opened on the outer conductor 31 of the tapered coaxial transmission line, and a screw 34 is used to connect the outer conductor 31 of the tapered coaxial transmission line to the ground wire.

[0048] like Figure 6 As shown, the output connector 4 comprises an output connector outer conductor 41, an annular dielectric inner ring 42, an output connector inner conductor 43, a fixed probe 44 and an annular dielectric sleeve 45; the output connector outer conductor 41 is connected to the tapered coaxial transmission line outer conductor 31, the annular dielectric inner ring 42 is arranged in the output connector outer conductor 41, and the output connector inner conductor 43 is arranged in the annular dielectric inner ring 42; the fixed probe 44 is connected to the input end of the output connector inner conductor 43 to prevent flashover breakdown on the surface of the output connector inner conductor 43; the annular dielectric sleeve 45 is connected to the annular dielectric inner ring 42, and a fixed probe 44 is formed between the fixed probe 44 and the annular dielectric sleeve 45. The annular hole 46 is inserted into the annular medium inner ring 42. The total length of the annular hole 46 is L6, L6=21mm, and the length of the fixed probe 44 is L7, L7=13mm; the outer diameter of the annular medium sleeve 45 is D1, D1=4mm, the inner diameter (i.e., the outer diameter of the output connector 6) is D2, D2=5.5mm, and the length of the output connector 6 is 25mm; when the optical switch 1 and the mobile feeding structure 2 move as a whole, the output connector 6 will move accordingly, and the maximum range of movement is less than 21mm; the longer the length of the annular hole 46, the greater the range of movement of the optical switch 1. The output end of the output connector 6 is inserted into the annular hole 46 of the output connector 4; the outer diameter of the fixed probe 44 is 5.3mm, and a bronze spring 25 is installed on the outside of the fixed probe 44 to increase the contact area with the output connector 6. In this embodiment, the dielectric constant of the dielectric material of the annular medium inner ring 42 and the annular medium sleeve 45 is 2.55.

[0049] The device equivalent circuit is Figure 7 shown.

[0050] The structure shown in this embodiment is simulated using CST:

[0051] Figure 8 The frequency response curves of devices with different configurations under the condition of maximum light intensity incident (when the conductivity peak is 3S / m) are shown in Figure 1, where Δx refers to the axial movement distance of the photoconductive switch 1. The simulation results show that in the initial state (Δx = 0), its 3-dB frequency range is 0.25 to 2.8 GHz. It is worth noting that by adjusting it to the resonant enhancement state (Δx = 21 mm or 13.8 mm), the output power of the device at 0.6 GHz is increased by 138.6%.

[0052] Fig. 9 The frequency response curves of devices with different configurations under different light intensity incident conditions (conductivity peak is 1-2S / m) are shown in the figure. The simulation results show that in the initial state, the 3-dB bandwidth of the device is not less than 0.25-2.8GHz, and through structural adjustment (resonance enhancement), the maximum output power can be increased to 161.3% (1S / m) and 134.9% (2S / m) of the original.

[0053] In summary, compared with the same type of photoconductive devices, this embodiment achieves further expansion of bandwidth and introduces an effective method for enhancing the performance of wide bandgap photoconductive devices. Without changing the substrate material and the internal structure of the photoconductive switch 1, the working mode can be changed only by adjusting the RF transmission structure, which is conducive to meeting more types of application requirements in the future.

Claims

1. An efficiency-enhanced broadband high-power photoconductive microwave generating device based on resonance regulation, characterized in that: It includes a photoconductive switch and an adjustable radio frequency transmission structure, wherein the adjustable radio frequency transmission structure includes a movable feeding structure, a gradient coaxial transmission line and an output connector; The optical switch, the mobile feeding structure, the tapered coaxial transmission line and the output connector are coaxially arranged; the optical switch is arranged in the mobile feeding structure; one end of the mobile feeding structure is embedded in the tapered coaxial transmission line and can move axially relative to the tapered coaxial transmission line; The output connector is arranged at the output end of the tapered coaxial transmission line; the input end of the optical switch is connected to the input connector, the output end of the optical switch is connected to the output connector, the output end of the output connector is inserted into the circular socket of the output connector and can move axially relative to the output connector.

2. The efficiency-enhanced broadband high-power photoconductive microwave generating device based on resonance regulation according to claim 1, characterized in that: The photoconductive switch comprises a semi-insulating semiconductor substrate, a hollow metal electrode positive electrode, a hollow metal electrode negative electrode, and a packaging structure. The semi-insulating semiconductor substrate adopts a wide bandgap doped semi-insulating semiconductor material. A circular transparent electrode and an annular composite metal electrode are plated on the light incident surface of the semi-insulating semiconductor substrate, and a reflective silver layer and an annular composite metal electrode are plated on the backlight surface. The annular composite metal electrode on the light incident surface of the semi-insulating semiconductor substrate is connected to the input connector through the hollow metal electrode positive electrode, and the annular composite metal electrode on the backlight surface of the semi-insulating semiconductor substrate is connected to the output connector through the hollow metal electrode negative electrode. A packaging structure is arranged outside the photoconductive switch.

3. The efficiency-enhanced broadband high-power photoconductive microwave generating device based on resonance regulation according to claim 2, characterized in that: The packaging structure includes an insulating packaging plate and insulating glue. The insulating packaging plate is arranged outside the semi-insulating semiconductor substrate, the hollow metal electrode positive electrode, and the hollow metal electrode negative electrode; the insulating glue is filled inside the insulating packaging plate; the input connector and the output connector are respectively connected to the hollow metal electrode positive electrode and the hollow metal electrode negative electrode through the connection holes reserved on the insulating packaging plate.

4. The efficiency-enhanced broadband high-power photoconductive microwave generating device based on resonance regulation according to claim 1, characterized in that: The input connector and the output connector are smooth hollow cylindrical metal structures.

5. The efficiency-enhanced broadband high-power photoconductive microwave generating device based on resonance regulation according to claim 1, characterized in that: The mobile feeding structure comprises a mobile feeding structure outer conductor, a mobile feeding structure inner conductor and a capacitor, wherein the mobile feeding structure outer conductor is a cylindrical metal structure, the mobile feeding structure inner conductor is a circular metal electrode, and the mobile feeding structure inner conductor is arranged coaxially inside the mobile feeding structure outer conductor; The inner circle of the inner conductor of the mobile feeding structure is connected to the input connector; the capacitor is connected between the outer conductor of the mobile feeding structure and the inner conductor of the mobile feeding structure.

6. The efficiency-enhanced broadband high-power photoconductive microwave generating device based on resonance regulation according to claim 5, characterized in that: The capacitor is formed by connecting several sub-capacitors in parallel to form a parallel capacitor. One terminal of each sub-capacitor is connected to the grounding weld of the outer conductor of the mobile feeding structure, and the other terminal is connected to the inner conductor of the mobile feeding structure. Several sub-capacitors are arranged in a circular array with equal spacing.

7. The efficiency-enhanced broadband high-power photoconductive microwave generating device based on resonance regulation according to claim 5, characterized in that: The capacitor is a ring capacitor or a chip inductor for energy storage.

8. The efficiency-enhanced broadband high-power photoconductive microwave generating device based on resonance regulation according to claim 1, characterized in that: The tapered coaxial transmission line is a cylindrical metal material structure, including an outer conductor of the tapered coaxial transmission line and an outer conductor of a stepped transmission line arranged along the axis inside. A circular blind hole is provided between the outer conductor of the tapered coaxial transmission line and the outer conductor of the stepped transmission line, and one end of the outer conductor of the movable feeding structure is inserted into the circular blind hole; the radius of the outer conductor of the stepped transmission line decreases step by step from the input end to the output end, the inner radius of the outer conductor of the first transmission line is the inner radius of the circular blind hole, that is, the inner radius of the outer conductor of the movable feeding structure, and the length is the distance from the input port of the tapered coaxial transmission line to the first step plane; the inner radius of the outer conductor of the second transmission line and the outer conductor of the third transmission line decreases in sequence.

9. The efficiency-enhanced broadband high-power photoconductive microwave generating device based on resonance regulation according to claim 1, characterized in that: A bronze spring is installed on the outer wall of the outer conductor of the mobile feeding structure, a hole is opened on the outer conductor of the tapered coaxial transmission line, and the outer conductor of the tapered coaxial transmission line is connected to the ground wire by using screws.

10. The efficiency-enhanced broadband high-power photoconductive microwave generating device based on resonance regulation according to claim 1, characterized in that: The output connector comprises an output connector outer conductor, an annular dielectric inner ring, an output connector inner conductor, a fixed probe and an annular dielectric sleeve; the output connector outer conductor is connected to the outer conductor of the tapered coaxial transmission line, the annular dielectric inner ring is arranged in the output connector outer conductor, and the output connector inner conductor is arranged in the annular dielectric inner ring; the fixed probe is connected to the input end of the output connector inner conductor; the annular dielectric sleeve is connected to the annular dielectric inner ring, a circular plug hole is formed between the fixed probe and the annular dielectric sleeve, the circular plug hole penetrates into the annular dielectric inner ring, and the output end of the output connector is inserted into the circular plug hole of the output connector; a bronze shrapnel is installed on the outside of the fixed probe.

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