A terahertz tunable attenuator

Abstract

The application provides a terahertz adjustable attenuator, which comprises an attenuation function chip and a chip packaging box, and the attenuation function chip comprises an echo wall mode micro-ring waveguide, two electric contact electrodes, a heating electrode, a straight waveguide, a first tapered coupling waveguide, a second tapered coupling waveguide and a substrate, wherein the straight waveguide is located on one side of the echo wall mode micro-ring waveguide, and the echo wall mode micro-ring waveguide and the straight waveguide constitute an echo wall mode micro-ring resonant cavity; the contact electrode, the heating electrode and the contact electrode are sequentially connected to form a three-section electrode structure and are integrated on the echo wall mode micro-ring waveguide; the first and second tapered coupling waveguides are located at two ends of the straight waveguide; and the substrate is used for integrated preparation of the echo wall mode micro-ring waveguide, the electric contact electrode, the heating electrode, the straight waveguide and the first and second tapered coupling waveguides. The application improves the ability of dynamically adjusting terahertz signals and realizes attenuation of terahertz signals with different intensities.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of terahertz, and particularly relates to a terahertz adjustable attenuator. BACKGROUND

[0002] Terahertz waves are electromagnetic waves with a frequency of 0.1 THz to 10 THz. With the rapid development of terahertz technology, its potential applications in high-resolution imaging, high-data wireless communication, biomedicine and other fields have attracted extensive research. As an indispensable part of a terahertz application system, an attenuator plays an important role in regulating signal path loss gain and realizing reliable communication. Among them, a variable attenuator can flexibly control the signal level by dynamically adjusting the attenuation degree to adapt to different signal intensities, improve signal quality and improve system performance.

[0003] Several methods of variable attenuators studied in the terahertz range are generally based on the free carrier absorption effect of semiconductors. Current research methods mainly focus on optical and electronic tuning, but generally have the following problems. First, optical tuning requires external laser equipment or optical fiber to transfer laser to irradiate dielectric materials, increasing the volume and cost of the system. Second, the realization of attenuation function often relies on the assembly of multiple elements, which is complex in technology and lacks integration. The whispering gallery mode resonant cavity has attracted much attention in the optical field due to its high Q value, small mode volume, simple structure and excellent signal processing capability. Its application in terahertz technology such as detectors, modulators, filters and sensors has been widely reported, but the design of attenuators based on this has received less attention. When a specific terahertz wave passes through a whispering gallery mode micro-ring resonant cavity, strong resonance will occur inside the cavity, resulting in a large amount of energy being absorbed, thereby achieving attenuation of the intensity of the terahertz wave. By applying a voltage to guide heat, the continuous tunability of the WGMR resonant frequency can be achieved, thereby realizing dynamic attenuation control of the terahertz signal. This becomes a simple and compact tunable attenuator solution. Moreover, the whispering gallery mode micro-ring resonant cavity can be integrated on a chip to prepare a waveguide-type attenuation function chip, which can effectively solve the low integration of traditional attenuators. SUMMARY

[0004] The application aims to provide a terahertz adjustable attenuator.

[0005] The technical solution for achieving the object of the application is: a terahertz adjustable attenuator, comprising an attenuation function chip and a chip packaging box, the attenuation function chip comprising an echo wall mode micro-ring waveguide, two electric contact electrodes, a heating electrode, a straight waveguide, a first tapered coupling waveguide, a second tapered coupling waveguide and a substrate, wherein: the straight waveguide is located on one side of the echo wall mode micro-ring waveguide, and the echo wall mode micro-ring waveguide and the straight waveguide constitute an echo wall mode micro-ring resonant cavity; the contact electrode, the heating electrode and the contact electrode are sequentially connected to form a three-section electrode structure and are integrated on the echo wall mode micro-ring waveguide; the first and second tapered coupling waveguides are located at the two ends of the straight waveguide; and the substrate is used for integrated preparation of the echo wall mode micro-ring waveguide, the electric contact electrode, the heating electrode, the straight waveguide and the first and second tapered coupling waveguides.

[0006] Further, the electric contact electrode and the heating electrode are both circular arcs, are connected to share the same center with the echo wall mode micro-ring resonant cavity, are located on the top surface of the echo wall mode micro-ring waveguide away from the end of the straight waveguide, and are left-right symmetrical along the central axis of the echo wall mode micro-ring waveguide perpendicular to the straight waveguide.

[0007] Further, the first and second tapered coupling waveguides are suspended and do not directly contact the substrate, and are isosceles triangles with the base width and the width of the straight waveguide being consistent from the perspective of top view, and the angle of the top corner opposite to the base is determined by the length of the tapered waveguide, when the base width of the straight waveguide is determined, the longer the length of the tapered coupling waveguide is, the smaller the angle of the top corner of the isosceles triangle is.

[0008] Further, the width of the straight waveguide is equal to the width of the echo wall mode micro-ring waveguide, the width of the heating electrode is smaller than the width of the electric contact electrode and the width of the echo wall mode micro-ring waveguide, the thickness of the heating electrode and the electric contact electrode is equal and smaller than the height of the echo wall mode micro-ring waveguide, the thickness of the substrate is smaller than the height of the echo wall mode micro-ring waveguide, the height of the first and second tapered coupling waveguides, the height of the straight waveguide and the height of the echo wall mode micro-ring waveguide are equal, the first and second tapered coupling waveguides are suspended and do not contact the substrate, and are left-right symmetrical in the extension direction of the straight waveguide.

[0009] Further, the attenuation function chip is prepared on the substrate through micro-nano processing, the electric contact electrode and the heating electrode are both platinum, and the materials of the echo wall mode micro-ring waveguide, the straight waveguide, the first tapered coupling waveguide, the second tapered coupling waveguide and the substrate are all high-resistance silicon.

[0010] Further, the transmission mode of the echo wall mode micro-ring resonant cavity is TM mode.

[0011] Further, the frequency offset of the echo wall mode micro-ring resonant cavity is determined according to the formula wherein ΔT(t) represents the temperature change of the echo wall mode micro-ring waveguide under different heating powers. is the thermo-optic coefficient of the material of the whispering gallery mode micro-ring waveguide; f0 represents the resonance frequency of the whispering gallery mode micro-ring waveguide; n g is the group refractive index of the terahertz wave in the whispering gallery mode micro-ring waveguide.

[0012] Further, the chip packaging box adopts an upper cavity structure and a lower cavity structure, the upper cavity is a cover, the lower cavity is a slide box, the lower cavity has metal rectangular waveguide openings on both sides, the openings extend inward to form metal rectangular waveguide channels and are left-right symmetrical, during packaging, the attenuation functional chip is placed in the center of the slide box of the lower cavity, the first and second tapered waveguides are inserted into the rectangular waveguide channels, a PCB board placing box is arranged above the slide box, during packaging, metal wires are used to connect the electrodes on the attenuation functional chip and the PCB board, a coaxial line interface is arranged on the upper side of the lower cavity and is connected with the PCB interface, and a power supply is connected to the packaging box through the coaxial line interface.

[0013] Further, the main part of the chip packaging box is made of copper, and the inner and outer surfaces are covered with a gold coating, and the thickness of the gold coating is greater than the skin depth of the terahertz wave signal.

[0014] Further, the working process is as follows: the terahertz signal is coupled into the first tapered waveguide through the metal rectangular waveguide, then is coupled into the whispering gallery mode micro-ring waveguide from the straight waveguide, the terahertz wave satisfying the resonance condition is transmitted in the micro-ring waveguide, the heating electrode is heated by applying a voltage to the electrical contact electrode, heat is transferred to the whispering gallery mode micro-ring waveguide to change the effective refractive index, thereby causing the frequency shift phenomenon to occur, that is, the signal attenuation is realized at the same frequency point, and finally the signal is re-entered into the straight waveguide through coupling and is output through the second tapered waveguide.

[0015] Compared with the prior art, the present application has the following advantages: 1) the whispering gallery mode resonant cavity adopts a TM transmission mode, the tapered waveguide is suspended below and does not directly contact the substrate, thereby enhancing the coupling efficiency and reducing the transmission loss; 2) the contact electrode and the heating electrode are directly placed on the whispering gallery mode micro-ring waveguide and adopt a circular arc symmetrical structure concentric with the micro-ring, thereby improving the structural stability, heating efficiency and temperature sensitivity of the device and the tuning and attenuation effects are obvious; 3) the contact electrode and the heating electrode are placed on the whispering gallery mode micro-ring waveguide away from the straight waveguide and are adjacent to the PCB board exchanging with the external power supply, thereby enhancing the reliability and stability of the electrical connection and reducing the influence of the electro-thermal conversion region on the coupling region, and compared with the probe voltage application mode, the present application is more suitable for integration and miniaturization. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a schematic diagram of a terahertz adjustable attenuator (the attenuation functional chip is placed on the slide box of the lower cavity).

[0017] Figure 2 is a structural schematic diagram of the attenuation functional chip of the terahertz adjustable attenuator.

[0018] Figure 3 is the size diagram of the attenuation function chip of the terahertz adjustable attenuator.

[0019] Figure 4 is the S parameter result diagram of the terahertz adjustable attenuator.

[0020] Figure 5 is the thermal adjustable transmission spectrum diagram of the terahertz adjustable attenuator near the working frequency point.

[0021] Figure 6 is the transmission spectrum diagram of the terahertz adjustable attenuator at the working frequency point.

[0022] Figure 7 is the schematic diagram of a terahertz attenuation experimental system built by using the present application.

[0023] Figure 8 is the attenuation result diagram of the present application at different frequencies. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0025] As shown in Figures 1-2 , a terahertz adjustable attenuator comprises an attenuation function chip and a chip packaging box. The attenuation function chip is composed of an echo wall mode micro-ring waveguide 2, two electric contact electrodes 3, a heating electrode 4, a straight waveguide 5, a first tapered coupling waveguide 1, a second tapered coupling waveguide 6 and a substrate 7, and is packaged in the packaging box. The straight waveguide 5 is located on one side of the echo wall mode micro-ring waveguide 2, and the echo wall mode micro-ring waveguide 2 and the straight waveguide 5 constitute an echo wall mode micro-ring resonant cavity; the electric contact electrodes 3 and the heating electrode 4 are connected and integrated on the echo wall mode micro-ring waveguide 2; the first and second tapered coupling waveguides 1, 6 are located at both ends of the straight waveguide 5; the substrate 7 is used for integrated preparation of the echo wall mode micro-ring waveguide 2, the electric contact electrodes 3, the heating electrode 4, the straight waveguide 5 and the first and second tapered coupling waveguides 1, 6; and the packaging box is used for reducing the influence of external interference on the attenuation function chip. The attenuation function chip with the echo wall mode micro-ring resonant cavity as the core is micro-assembled to form a terahertz adjustable attenuator module, which can be easily connected with other terahertz devices such as a terahertz source and a terahertz detector.

[0026] For example, the tapered waveguide 1 is placed in the rectangular waveguide channel in the designed packaging box, the rectangular waveguide channel is formed by extending inward from the rectangular waveguide opening, the size of the rectangular waveguide opening can refer to the WR series waveguide specification, and the terahertz signal is coupled from the metal rectangular waveguide channel into the tapered waveguide. In some examples, the size of the rectangular waveguide opening in the packaging box is WR6.5, WR5.1, WR4.3, WR3.4, WR2.8, WR2.2, WR1.5, WR1.0, etc.

[0027] The echo wall mode micro-ring waveguide, the straight waveguide, and the tapered coupling waveguide in the application belong to dielectric waveguides, and the electrode belongs to a conductive element. The effective refractive index n of the dielectric waveguide is related to the material, width, and height of the dielectric waveguide, and determines the transmission loss of the terahertz signal in the dielectric waveguide. The substrate material can be selected from high-resistance silicon, lithium niobate, silicon dioxide, or gallium nitride, and the echo wall mode micro-ring waveguide, the straight waveguide, the contact electrode, the heating electrode, and the tapered coupling waveguide are obtained by micro-nano processing. eff

[0028] In order to further reduce the transmission loss of the terahertz signal in the dielectric waveguide, the transmission mode of the echo wall mode micro-ring resonant cavity is TM mode, the width of the straight waveguide 5 is equal to the width of the echo wall mode micro-ring waveguide 2, the width of the heating electrode 4 is less than the width of the electric contact electrode 3, which is less than the width of the echo wall mode micro-ring waveguide 2, the thickness of the heating electrode 4 and the electric contact electrode 3 is equal, which is less than the height of the echo wall mode micro-ring waveguide 2, the electric contact electrode 3 and the heating electrode 4 are connected and are circular arcs, and share the same center with the echo wall mode micro-ring resonant cavity, are located on the top surface of the echo wall mode micro-ring waveguide 2 away from the end of the straight waveguide 5, are left-right symmetrical along the central axis of the echo wall mode micro-ring waveguide 2 perpendicular to the straight waveguide 5, the thickness of the substrate 7 is less than the height of the echo wall mode micro-ring waveguide 2, the height of the first and second tapered coupling waveguides 1, 6, the height of the straight waveguide 5, and the height of the echo wall mode micro-ring waveguide 2 are equal, the first and second tapered coupling waveguides 1, 6 are suspended and do not directly contact the substrate 7, and are isosceles triangles with the same width as the width of the straight waveguide 5 from the top view, and the angle of the top corner opposite to the bottom side is determined by the length of the tapered waveguide, when the width of the bottom side of the straight waveguide 5 is determined, the longer the length of the tapered coupling waveguide, the smaller the angle of the top corner of the isosceles triangle.

[0029] The frequency offset of the echo wall mode micro-ring resonant cavity in the resonant adjustable functional chip is determined according to the formula where ΔT(t) represents the temperature change of the echo wall mode micro-ring waveguide under different heating powers, is the thermal-optical coefficient of the material of the echo wall mode micro-ring waveguide; f0 represents the resonant frequency of the echo wall mode micro-ring waveguide; n g is the group refractive index of the terahertz wave in the echo wall mode micro-ring waveguide.​

[0030] The chip packaging box adopts upper and lower cavity structure, the upper cavity is a cover, the lower cavity is a slide box, the lower cavity has metal rectangular waveguide openings on both sides, the openings extend inward to form metal rectangular waveguide channels and are left-right symmetrical, the attenuation functional chip is placed in the center of the slide box during packaging, the first and second tapered waveguides are inserted into the rectangular waveguide channels, the slide box is above the PCB board, the electrodes on the attenuation functional chip are connected with the PCB board by metal wires during packaging, the lower cavity has a coaxial line interface on the upper side, which is connected with the PCB interface, and the input power is connected to the packaging box through the coaxial line interface. The main part of the chip packaging box is made of copper, and the inner and outer surfaces are covered with a gold coating, and the thickness of the gold coating is greater than the skin depth of the terahertz wave signal.

[0031] The terahertz signal is coupled into the first tapered waveguide 1 through the metal rectangular waveguide, then coupled into the whispering gallery mode micro-ring waveguide 2 from the straight waveguide 5, the terahertz wave satisfying the resonance condition will be transmitted in the micro-ring waveguide, by applying voltage to the electrical contact electrode 3, the heating electrode 4 is heated, the heat is transferred to the whispering gallery mode micro-ring waveguide 2 to change its effective refractive index, thereby causing frequency shift phenomenon, that is, the attenuation of the signal is realized at the same frequency point, and finally re-enters the straight waveguide 5 through coupling and is output through the second tapered waveguide 6.

[0032] Embodiment

[0033] In this embodiment, high resistance silicon is selected as the substrate, and the specific meanings of the size parameters of the whispering gallery mode micro-ring waveguide, the straight waveguide, the electrode and the tapered waveguide are shown in Figure 3 The width w of the whispering gallery mode micro-ring waveguide 2 and the straight waveguide 5 is designed to be 200 μm, the height of the whispering gallery mode micro-ring waveguide 2 and the straight waveguide 5 is 140 μm, and the thickness of the substrate 7 is 60 μm. The width w1 of the two electrical contact electrodes 3 is 180 μm, the radian θ1 is 15°, the width w2 of the heating electrode 4 is 12 μm, and the radian θ2 is 6°. The contact electrode, the heating electrode and the contact electrode are connected in sequence to form a three-section electrode structure. At the same time, in order to ensure the coupling efficiency when the terahertz energy is coupled from the rectangular waveguide to the tapered waveguides 1, 6 after the attenuation functional chip is packaged, the length of the tapered waveguides 1, 6 needs to be more than 3 times of its width, and here the length l is designed to be 1500 μm, and the length of the tapered triangle is 1150 μm, at this time the top angle θ of the tapered waveguide is about 9.9°. The resonance frequency of the whispering gallery mode micro-ring resonator is 1800 μm, the distance g between the straight waveguide and the whispering gallery mode micro-ring waveguide is 10 μm, the width a of the substrate 7 is 4800 μm, and the length b is 5900 μm.

[0034] The terahertz time-domain differentiator is prepared and packaged according to the following process, and the specific steps are as follows:

[0035] 1. Use the lift-off process to form 100nm thick platinum on the silicon platform as contact electrodes and heating electrodes;

[0036] 2. Using a deep silicon etching process, the silicon wafer is etched to a depth of 140 μm to form a whispering gallery mode microring, a straight waveguide, and a tapered coupled waveguide to create an attenuation function chip.

[0037] 3. According to the size of a single attenuation function chip, design the corresponding packaging box and micro-assemble it into an attenuator.

[0038] 4. Use a wire bonding machine to establish electrical connection between the PCB board and the electrode with metal wire, and input the external DC voltage source through the coaxial cable.

[0039] 5. Connect the attenuator to the terahertz source and terahertz detector that are compatible with the interface for testing.

[0040] In order to verify the transmission characteristics of the terahertz adjustable attenuator, the packaged terahertz attenuator was connected to a vector network analyzer to test the S parameters of the device. The tapered coupling waveguide 1 was used as the signal input end, and the tapered coupling waveguide 5 was used as the signal output end. 21 is the transmittance of the device. Figure 4 S 21 The results show that the overall insertion loss is only 5.5dB, which shows that the design of the tapered coupled waveguide has played a role; the extinction ratio is in the range of 9-14dB. The transmission spectrum of the attenuator in the frequency range of 388GHz to 394GHz is fitted, as shown in the figure below. Figure 5 As shown in Figure 3, as the heating power gradually increases, the resonance redshifts, demonstrating the continuous tunability of the attenuator. At a heating power of 3.35 W, the thermal tuning range reaches 1.26 GHz.

[0041] In order to verify the signal attenuation effect of this terahertz adjustable attenuator, Figure 6 As shown in the figure, the fabricated and packaged terahertz adjustable attenuator is connected to a continuous-wave terahertz source and a terahertz detector. The system uses a terahertz transmitter consisting of an amplifier-multiplier chain to provide terahertz waves. A voltage from a high-precision DC voltage source is applied to the electrodes to achieve thermal tunability. A power meter is used as a detector to directly observe the signal attenuation. Figure 7The changes of transmission power at 388.56GHz, 389.5GHz, 390GHz on the left side of the resonance point and 392GHz on the right side with different applied voltages are summarized. The transmission power at 389.5GHz decays from 15.8μW to 3.3μW, because as the temperature rises, the resonance frequency moves to low frequency, the signal originally located on the left side of the frequency gradually approaches the resonance point, resulting in the decrease of transmission efficiency in the ring resonator, thus showing the decrease of output power. The right side frequency is opposite to it, showing the increase of output power, such as the change at 392GHz. The results show that through thermal tuning, the ring resonator can dynamically adjust the signal transmission capability at different frequency points, and realize the control of the attenuation at different frequency points. Among them, 389.75GHz is located far from the passband resonance point, and the transmission loss increases with the increase of voltage. Without applying voltage, S 21 -5.5dB, which proves the low-loss transmission of the device. When the voltage increases to 12V, S 21 drops to-11dB, showing a decay range of 5.5-11dB.

[0042] The embodiments of the present application are not limited by the examples. Without departing from the spirit and principles of the present application, any changes, simplifications, substitutions, combinations made without departing from the spirit and principles of the present application shall be included in the protection scope of the present application.

[0043] The technical features of the above examples can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above examples are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0044] The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A terahertz tunable attenuator, characterized by, The attenuation function chip and the chip packaging box are included, the attenuation function chip includes a whispering gallery mode micro-ring waveguide (2), two electric contact electrodes (3), a heating electrode (4), a straight waveguide (5), a first tapered coupling waveguide (1), a second tapered coupling waveguide (6) and a substrate (7), wherein: the straight waveguide (5) is located on one side of the whispering gallery mode micro-ring waveguide (2), and the whispering gallery mode micro-ring waveguide (2) and the straight waveguide (5) constitute a whispering gallery mode micro-ring resonant cavity; the contact electrode (3), the heating electrode (4) and the contact electrode (3) are sequentially connected to form a three-section electrode structure and are integrated on the whispering gallery mode micro-ring waveguide (2); the first and second tapered coupling waveguides (1, 6) are located at both ends of the straight waveguide (5); and the substrate (7) is used for integrated preparation of the whispering gallery mode micro-ring waveguide (2), the electric contact electrode (3), the heating electrode (4), the straight waveguide (5) and the first and second tapered coupling waveguides (1, 6).

2. The terahertz adjustable attenuator according to claim 1, characterized in that Both the electric contact electrode (3) and the heating electrode (4) are circular arcs, and after being connected, they share a common center with the whispering gallery mode micro-ring resonant cavity and are located on the top surface of the whispering gallery mode micro-ring waveguide away from the straight waveguide end and are symmetrical on both sides of the central axis of the whispering gallery mode micro-ring waveguide perpendicular to the straight waveguide (5).

3. The terahertz adjustable attenuator according to claim 1, characterized in that The first and second tapered coupling waveguides (1, 6) are suspended and do not directly contact the substrate, and from a top view, they are isosceles triangles with the width of the base being consistent with the width of the straight waveguide (5), and the angle of the top corner opposite to the base is determined by the length of the tapered waveguide, when the width of the base of the straight waveguide (5) is determined, the longer the length of the tapered coupling waveguide, the smaller the angle of the top corner of the isosceles triangle.

4. The terahertz adjustable attenuator according to claim 1, characterized in that The width of the straight waveguide (5) is equal to the width of the whispering gallery mode micro-ring waveguide (2), the width of the heating electrode (4) is smaller than the width of the electric contact electrode (3) and the width of the whispering gallery mode micro-ring waveguide (2), the thickness of the heating electrode (4) and the electric contact electrode (3) is equal and smaller than the height of the whispering gallery mode micro-ring waveguide (2), the thickness of the substrate (7) is smaller than the height of the whispering gallery mode micro-ring waveguide (2), the height of the first and second tapered coupling waveguides (1, 6), the height of the straight waveguide (5) and the height of the whispering gallery mode micro-ring waveguide (2) are equal, and the first and second tapered coupling waveguides (1, 6) are suspended and do not contact the substrate and are symmetrical on both sides in the extension direction of the straight waveguide (5).

5. The terahertz adjustable attenuator according to claim 1, characterized in that The attenuation function chip is prepared on the substrate through micro-nano processing, the electric contact electrode (3) and the heating electrode (4) are both platinum, and the materials of the whispering gallery mode micro-ring waveguide (2), the straight waveguide (5), the first tapered coupling waveguide (1), the second tapered coupling waveguide (6) and the substrate (7) are all high-resistance silicon.

6. The terahertz adjustable attenuator according to claim 1, characterized in that The transmission mode of the whispering gallery mode micro-ring resonant cavity is a TM mode.

7. The terahertz adjustable attenuator according to claim 1, characterized in that The frequency shift of the whispering gallery mode micro-ring resonator is determined according to the formula where ΔT(t) represents the temperature change of the whispering gallery mode micro-ring waveguide under different heating powers, is the thermo-optic coefficient of the whispering gallery mode micro-ring waveguide material; f0represents the resonant frequency of the whispering gallery mode micro-ring waveguide; n g is the group refractive index of the terahertz wave in the whispering gallery mode micro-ring waveguide.

8. The terahertz adjustable attenuator according to claim 1, characterized in that The chip packaging box adopts upper and lower cavity structure, the upper cavity is a cover, the lower cavity is a slide box, the lower cavity has metal rectangular waveguide openings on both sides, the openings extend inward to form metal rectangular waveguide channels and are left-right symmetrical, the attenuation function chip is placed in the center of the slide box during packaging, the first and second tapered waveguide are inserted into the rectangular waveguide channel, the slide box is above the PCB board, the electrode on the attenuation function chip is connected with the PCB board by metal wire during packaging, the lower cavity has a coaxial line interface on the upper side, the interface is connected with the PCB interface, and the input power is connected to the packaging box through the coaxial line interface.

9. The terahertz adjustable attenuator according to claim 1, characterized in that The main part of the chip packaging box is made of copper, and the inner and outer surfaces are covered with a gold coating, and the thickness of the gold coating is greater than the skin depth of the terahertz wave signal.

10. The terahertz adjustable attenuator according to claim 1, characterized in that The working process is as follows: the terahertz signal is coupled into the first tapered waveguide (1) through the metal rectangular waveguide, then coupled into the whispering gallery mode micro-ring waveguide (2) from the straight waveguide (5), the terahertz wave satisfying the resonance condition will be transmitted in the micro-ring waveguide, the heating electrode (4) is heated by applying voltage to the electrical contact electrode (3), the heat is transferred to the whispering gallery mode micro-ring waveguide (2) to change its effective refractive index, thereby causing frequency shift phenomenon, that is, the signal attenuation is realized at the same frequency point, finally re-entering the straight waveguide (5) through coupling and outputting through the second tapered waveguide (6).

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