Terahertz adjustable attenuator

Abstract

The terahertz adjustable attenuator comprises an attenuation function chip and a chip packaging box, the attenuation function chip comprises an echo wall mode micro-ring waveguide, two electric contact electrodes, a heating electrode, a straight waveguide, a first conical coupling waveguide, a second conical coupling waveguide and a substrate, the straight waveguide is located on one side of the echo wall mode micro-ring waveguide, and the first conical coupling waveguide is located on the other side of the echo wall mode micro-ring waveguide; the echo wall mode micro-ring waveguide and the straight waveguide form an echo wall mode micro-ring resonant cavity; the contact electrode, the heating electrode and the contact electrode are connected in sequence to form a three-section electrode structure which is integrated on the echo wall mode micro-ring waveguide; the first and second conical coupling waveguides are located at two ends of the straight waveguide; the substrate is used for integrally preparing the echo wall mode micro-ring waveguide, the electric contact electrode, the heating electrode, the straight waveguide, the first conical coupling waveguide and the second conical coupling waveguide. According to the invention, the capability of dynamically adjusting the terahertz signals is improved, and attenuation of the terahertz signals with different intensities is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of terahertz, and in particular relates to a terahertz adjustable attenuator. Background Art

[0002] Terahertz waves broadly refer to electromagnetic waves with a frequency of 0.1THz to 10THz. With the rapid development of terahertz technology, its potential applications in high-resolution imaging, high-data wireless communications, biomedicine and other fields have attracted extensive research. Attenuators, as an indispensable part of terahertz application systems, play an important role in regulating signal path loss gain and achieving reliable communication. Among them, variable attenuators can flexibly control signal levels by dynamically adjusting the attenuation degree to achieve the purpose of adapting to different signal strengths, improving signal quality, and improving system performance.

[0003] Several variable attenuator methods studied in the terahertz range are usually based on the free carrier absorption effect of semiconductors. The current research methods mainly focus on optical and electronic tuning, but there are generally the following problems: First, optical tuning requires external laser equipment or optical fiber to transmit laser to irradiate dielectric materials, which increases the volume and cost of the system; Second, the realization of the attenuation function often relies on the assembly of multiple components, and the technical implementation is complex and lacks integration. The whispering gallery mode resonator has attracted much attention in the optical field for its high Q value, small mode volume, simple structure and excellent signal processing capabilities. Its applications in terahertz technology such as detectors, modulators, filters, sensors, etc. have been widely reported, but the attenuator design based on this has received less attention. When a specific terahertz wave passes through the whispering gallery mode microring resonator, a strong resonance will be generated inside the cavity, resulting in a large amount of energy being absorbed, realizing the attenuation of the terahertz wave intensity. By applying voltage to conduct heat, the WGMR resonant frequency can be continuously adjusted, and then the dynamic attenuation control of the terahertz signal can be realized, which becomes a simple and compact tunable attenuator solution. In addition, the on-chip integration of the whispering gallery mode micro-ring resonator into a waveguide-type attenuation function chip can effectively solve the shortcoming of low integration of traditional attenuators. Summary of the invention

[0004] The purpose of the present invention is to provide a terahertz adjustable attenuator.

[0005] The technical solution for achieving the purpose of the present invention is: a terahertz adjustable attenuator, including an attenuation function chip and a chip packaging box, the attenuation function chip includes a whispering gallery mode microring waveguide, two electrical 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 whispering gallery mode microring waveguide, and the whispering gallery mode microring waveguide and the straight waveguide constitute a whispering gallery mode microring resonant cavity; the contact electrode, the heating electrode and the contact electrode are connected in sequence to form a three-segment electrode structure, which is integrated on the whispering gallery mode microring waveguide; the first and second tapered coupling waveguides are located at both ends of the straight waveguide; the substrate is used for integrated preparation of the whispering gallery mode microring waveguide, the electrical contact electrode, the heating electrode, the straight waveguide and the first and second tapered coupling waveguides.

[0006] Furthermore, the electrical contact electrode and the heating electrode are both arc-shaped, and are co-centered with the whispering gallery mode microring resonant cavity when connected, and are located on the top surface of the whispering gallery mode microring waveguide away from the straight waveguide end, and are symmetrical on both sides of the central axis of the whispering gallery mode microring waveguide perpendicular to the straight waveguide.

[0007] Furthermore, the first and second tapered coupling waveguides are suspended in the air and are not in direct contact with the substrate. From a top-down perspective, they are isosceles triangles with a base width that is consistent with the width of the straight waveguide. The vertex angle relative 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, the smaller the vertex angle of the isosceles triangle.

[0008] Furthermore, the width of the straight waveguide is equal to the width of the whispering gallery mode microring waveguide, the width of the heating electrode is smaller than the width of the electrical contact electrode and smaller than the width of the whispering gallery mode microring waveguide, the thickness of the heating electrode and the electrical contact electrode are equal and smaller than the height of the whispering gallery mode microring waveguide, the thickness of the substrate is smaller than the height of the whispering gallery mode microring waveguide, the height of the first and second tapered coupling waveguides, the height of the straight waveguide and the height of the whispering gallery mode microring waveguide are equal, the first and second tapered coupling waveguides are suspended and not in contact with the substrate, and are bilaterally symmetrical in the extension direction of the straight waveguide.

[0009] Furthermore, the attenuation function chip is prepared on the substrate by micro-nano processing, the electrical contact electrode and the heating electrode are both platinum, and the whispering gallery mode microring waveguide, the straight waveguide, the first tapered coupled waveguide, the second tapered coupled waveguide and the substrate material are all high-resistance silicon.

[0010] Furthermore, the transmission mode of the whispering gallery mode microring resonator is the TM mode.

[0011] Furthermore, the frequency deviation of the whispering gallery mode microring resonator is given by the formula Determine, where ΔT(t) represents the temperature change of the whispering gallery mode microring waveguide under different heating powers, is the thermo-optic coefficient of the whispering gallery mode microring waveguide material; f0 represents the resonant frequency of the whispering gallery mode microring waveguide; n g is the group refractive index of terahertz wave in the whispering gallery mode microring waveguide.

[0012] Furthermore, the chip packaging box adopts an upper and lower cavity structure, the upper cavity is a cover, the lower cavity is a wafer carrier box, there are metal rectangular waveguide openings on both sides of the lower cavity, the openings extend inward to form a metal rectangular waveguide channel and are symmetrical on the left and right, when packaging, the attenuation function chip is placed in the center of the lower cavity wafer carrier box, the first and second conical coupling waveguides are inserted into the rectangular waveguide channel, and the PCB board is placed above the wafer carrier box. When packaging, the electrodes on the attenuation function chip are connected to the PCB board with metal wires, and a coaxial line interface is provided on the upper side of the lower cavity to connect to the PCB interface, and the input power is connected to the packaging box through the coaxial line port.

[0013] Furthermore, the main body of the chip packaging box is made of copper, and its 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] Furthermore, the working process is as follows: the terahertz signal is coupled to the first tapered coupling waveguide through the metal rectangular waveguide, and then coupled from the straight waveguide to the whispering gallery mode microring waveguide. The terahertz wave that meets the resonance condition will be transmitted in the microring waveguide. By applying voltage to the electrical contact electrode, the heating electrode is heated, and the heat is transferred to the whispering gallery mode microring waveguide to change its effective refractive index, thereby causing a frequency shift phenomenon, that is, the signal is attenuated at the same frequency point, and finally re-enters the straight waveguide after coupling and is output through the second tapered coupling waveguide.

[0015] Compared with the prior art, the present invention has the following significant advantages: 1) the whispering gallery mode resonant cavity adopts the TM transmission mode, and the conical waveguide is suspended below and is not directly connected to the substrate, which enhances the coupling efficiency and reduces the transmission loss; 2) the contact electrode and the heating electrode are directly placed on the whispering gallery mode microring waveguide, and adopt a circular arc symmetrical structure concentric with the microring, which improves the structural stability, heating efficiency and temperature sensitivity of the device, and has obvious tuning and attenuation effects; 3) the contact electrode and the heating electrode are placed on the whispering gallery mode microring waveguide away from the straight waveguide, close to the PCB board that exchanges with the external power supply, which enhances the reliability and stability of the electrical connection, reduces the influence of the electrothermal conversion area on the coupling area, and is more suitable for integration and miniaturization compared to the probe voltage application method. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0017] Figure 2 It is a schematic diagram of the structure of the attenuation function chip of the terahertz adjustable attenuator.

[0018] Figure 3 This is a schematic diagram of the dimensions of the attenuation function chip of the terahertz adjustable attenuator.

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

[0020] Figure 5 It is the thermally tunable transmission spectrum of the terahertz adjustable attenuator near the operating frequency.

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

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

[0023] Figure 8 It is a diagram of the attenuation results of the present invention at different frequencies. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] like Figure 1-2 As shown, a terahertz adjustable attenuator includes: an attenuation function chip and a chip packaging box. The attenuation function chip consists of a whispering gallery mode microring waveguide 2, two electrical 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 a packaging box. The straight waveguide 5 is located on one side of the whispering gallery mode microring waveguide 2, and the whispering gallery mode microring waveguide 2 and the straight waveguide 5 constitute a whispering gallery mode microring resonant cavity; the electrical contact electrode 3 and the heating electrode 4 are connected and integrated on the whispering gallery mode microring waveguide 2; the first and second tapered coupling waveguides 1 and 6 are located at both ends of the straight waveguide 5; the substrate 7 is used to integrate the preparation of the whispering gallery mode microring waveguide 2, the electrical contact electrode 3, the heating electrode 4, the straight waveguide 5 and the first and second tapered coupling waveguides 1 and 6; the packaging box is used to reduce the influence of external interference on the attenuation function chip. The present invention micro-assembles an attenuation function chip with a whispering gallery mode micro-ring resonator as the core to form a terahertz adjustable attenuator module, which can be easily connected to other terahertz devices such as a terahertz source and a terahertz detector.

[0026] Taking the tapered coupled waveguide 1 as an example, it is placed in a rectangular waveguide channel in the designed packaging box. The rectangular waveguide channel is formed by extending the rectangular waveguide opening inward. The size of the rectangular waveguide opening can refer to the WR series waveguide specification. The terahertz signal is coupled from the metal rectangular waveguide channel to 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 and other specifications.

[0027] The whispering gallery mode micro-ring waveguide, straight waveguide, and tapered coupling waveguide in the present invention are dielectric waveguides, and the electrodes are conductive elements. eff It is related to the material, width and height of the dielectric waveguide, which 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 whispering gallery mode micro-ring waveguide, straight waveguide, contact electrode, heating electrode and tapered coupling waveguide can be prepared through micro-nano processing.

[0028] In order to further reduce the transmission loss of terahertz signals in the dielectric waveguide, the transmission mode of the whispering gallery mode microring resonant cavity is the TM mode, the width of the straight waveguide 5 is equal to the width of the whispering gallery mode microring waveguide 2, the width of the heating electrode 4 is smaller than the width of the electric contact electrode 3 is smaller than the width of the whispering gallery mode microring waveguide 2, the thickness of the heating electrode 4 and the electric contact electrode 3 are equal and smaller than the height of the whispering gallery mode microring waveguide 2, the electric contact electrode 3 and the heating electrode 4 are connected in an arc shape and are co-centered with the whispering gallery mode microring resonant cavity, are located on the top surface of the whispering gallery mode microring waveguide 2 away from the end of the straight waveguide 5, and are connected along the straight waveguide 5. The waveguide 5 is perpendicular to the whispering gallery mode microring waveguide 2 and is symmetrical on both sides of the central axis. The thickness of the substrate 7 is less than the height of the whispering gallery mode microring waveguide 2. The heights 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 microring waveguide 2 are equal. The first and second tapered coupling waveguides 1, 6 are suspended and are not in direct contact with the substrate 7. From a top view, they are isosceles triangles with a base width consistent with the width of the straight waveguide 5. The vertex angle relative to the base is determined by the length of the tapered waveguide. When the base width of the straight waveguide 5 is determined, the longer the length of the tapered coupling waveguide is, the smaller the vertex angle of the isosceles triangle is.

[0029] The frequency deviation of the whispering gallery mode microring resonator in the resonant tunable function chip is calculated according to the formula Determine, where ΔT(t) represents the temperature change of the whispering gallery mode microring waveguide under different heating powers, is the thermo-optic coefficient of the whispering gallery mode microring waveguide material; f0 represents the resonant frequency of the whispering gallery mode microring waveguide; n g is the group refractive index of terahertz wave in the whispering gallery mode microring waveguide.

[0030] The chip packaging box adopts an upper and lower cavity structure, the upper cavity is a cover, the lower cavity is a wafer carrier, there are metal rectangular waveguide openings on both sides of the lower cavity, the openings extend inward to form a metal rectangular waveguide channel and are symmetrical. During packaging, the attenuation function chip is placed in the center of the wafer carrier of the lower cavity, the first and second tapered coupling waveguides are inserted into the rectangular waveguide channel, the PCB board placement box is above the wafer carrier, the electrodes on the attenuation function chip are connected to the PCB board with metal wires during packaging, the upper side of the lower cavity has a coaxial line interface connected to 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 its 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 to the first tapered coupling waveguide 1 through a metal rectangular waveguide, and then coupled from the straight waveguide 5 to the whispering gallery mode microring waveguide 2. The terahertz wave that meets the resonance condition will be transmitted in the microring waveguide. By applying a voltage to the electrical contact electrode 3, the heating electrode 4 is heated, and the heat is transferred to the whispering gallery mode microring waveguide 2 to change its effective refractive index, thereby causing a frequency shift phenomenon, that is, the signal is attenuated at the same frequency point, and finally re-enters the straight waveguide 5 after coupling, and is output through the second tapered coupling waveguide 6.

[0032] Example

[0033] In this embodiment, high-resistance silicon is selected as the substrate. The specific meanings of the size parameters of the whispering gallery mode microring waveguide, straight waveguide, electrode, and tapered coupling waveguide are shown in Figure 3 As shown, the width w of the whispering gallery mode microring waveguide 2 and the straight waveguide 5 is designed to be 200 μm, the height of the whispering gallery mode microring 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 arc θ1 is 15°, the width w2 of the heating electrode 4 is 12 μm, and the arc θ2 is 6°. The contact electrode, the heating electrode and the contact electrode are connected in sequence to form a three-segment electrode structure. At the same time, in order to ensure the coupling efficiency of the terahertz energy from the rectangular waveguide to the tapered coupling waveguide 1, 6 after the attenuation function chip is packaged, the length of the tapered coupling waveguide 1, 6 needs to be more than 3 times its width. Here, its 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 coupling waveguide is about 9.9°. The resonance frequency and radius r of the whispering gallery mode microring resonator are 1800 μm, the distance g between the straight waveguide and the whispering gallery mode microring 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. 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 deep silicon etching technology, the silicon wafer is etched to a depth of 140μm to form whispering gallery mode micro-rings and straight waveguides, tapered coupled waveguides, and manufactured into an attenuation function chip;

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

[0038] 4. Use a wire bonding machine to use metal wire to establish electrical connection between the PCB board and the electrode, 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 As can be seen from the results, the overall insertion loss is only 5.5dB, indicating 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 Figure 5 As shown in Figure 1, as the heating power gradually increases, the resonance red-shifts, 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 prepared and packaged terahertz adjustable attenuator is connected to a continuous wave terahertz source and a terahertz detector. The system uses a terahertz transmitter composed of an amplifier multiplier chain to provide terahertz waves, applies a voltage from a high-precision DC voltage source to the electrode to achieve thermal adjustment, and a power meter is used as a detector to directly observe the attenuation of the signal. Figure 7The changes in transmission power with different applied voltages at 388.56 GHz, 389.5 GHz, 390 GHz on the left side of the resonance point and 392 GHz on the right side are summarized. The transmission power attenuates from 15.8 μW to 3.3 μW at 389.5 GHz. This is because as the temperature increases, the resonance frequency moves toward low frequencies, and the signal originally located at the left frequency point gradually approaches the resonance point, resulting in a decrease in its transmission efficiency in the ring resonator, which manifests as a decrease in output power. The right frequency point is the opposite, showing an increase in output power, such as the changes at 392 GHz. 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, 389.75 GHz is located in the passband far away from the resonance point, and the transmission loss continues to increase with the increase of voltage. In the absence of applied voltage, S 21 The S 21 It drops to -11dB, showing an attenuation range of 5.5-11dB.

[0042] The implementation of the present invention is not limited by the embodiments. Without departing from the essence and principle of the present invention, any other changes, simplifications, substitutions, and combinations made without departing from the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0043] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A terahertz adjustable attenuator, characterized in that: The invention comprises an attenuation function chip and a chip packaging box. The attenuation function chip comprises a whispering gallery mode microring waveguide (2), two electrical 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 microring waveguide (2), and the whispering gallery mode microring waveguide (2) and the straight waveguide (5) constitute a whispering gallery mode microring 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, which is integrated on the whispering gallery mode microring 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 microring waveguide (2), the electrical 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: The electric contact electrode (3) and the heating electrode (4) are both arc-shaped and, when connected, are co-centered with the whispering gallery mode microring resonant cavity and are located on the top surface of the whispering gallery mode microring waveguide away from the straight waveguide end and are symmetrical along both sides of the central axis of the whispering gallery mode microring 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 in the air and are not in direct contact with the substrate. When viewed from a top view, they are isosceles triangles whose base width is the same as the width of the straight waveguide (5). The vertex angle relative to the base is determined by the length of the tapered waveguide. When the base width of the straight waveguide (5) is determined, the longer the length of the tapered coupling waveguide is, the smaller the vertex angle of the isosceles triangle is.

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 microring waveguide (2); the width of the heating electrode (4) is smaller than the width of the electric contact electrode (3) and smaller than the width of the whispering gallery mode microring waveguide (2); the thickness of the heating electrode (4) and the electric contact electrode (3) are equal and smaller than the height of the whispering gallery mode microring waveguide (2); the thickness of the substrate (7) is smaller than the height of the whispering gallery mode microring waveguide (2); the heights 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 microring waveguide (2) are equal; the first and second tapered coupling waveguides (1, 6) are suspended in the air and do not contact the substrate and are bilaterally symmetrical 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 a substrate by micro-nano processing, the electric contact electrode (3) and the heating electrode (4) are both made of 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 made of high-resistance silicon.

6. The terahertz adjustable attenuator according to claim 1, characterized in that: The transmission mode of the whispering gallery mode microring resonator is TM mode.

7. The terahertz adjustable attenuator according to claim 1, characterized in that: The frequency deviation of the whispering gallery mode microring resonator is calculated according to the formula Determine, where ΔT(t) represents the temperature change of the whispering gallery mode microring waveguide under different heating powers, is the thermo-optic coefficient of the whispering gallery mode microring waveguide material; f0 represents the resonant frequency of the whispering gallery mode microring waveguide; n g is the group refractive index of terahertz wave in the whispering gallery mode microring waveguide.

8. The terahertz adjustable attenuator according to claim 1, characterized in that: The chip packaging box adopts an upper and lower cavity structure, the upper cavity is a cover, the lower cavity is a wafer carrier, there are metal rectangular waveguide openings on both sides of the lower cavity, the openings extend inward to form a metal rectangular waveguide channel and are symmetrical on the left and right, the attenuation function chip is placed in the center of the lower cavity wafer carrier during packaging, the first and second tapered coupling waveguides are inserted into the rectangular waveguide channel, the PCB board is placed above the wafer carrier, the electrodes on the attenuation function chip are connected to the PCB board with metal wires during packaging, a coaxial line interface is provided on the upper side of the lower cavity to connect to 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 body of the chip packaging box is made of copper, and its inner and outer surfaces are covered with a gold coating whose thickness 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: a terahertz signal is coupled to a first tapered coupling waveguide (1) through a metal rectangular waveguide, and then coupled from a straight waveguide (5) to a whispering gallery mode microring waveguide (2). A terahertz wave that meets the resonance condition is transmitted in the microring waveguide. A voltage is applied to an electrical contact electrode (3) to heat a heating electrode (4). The heat is transferred to the whispering gallery mode microring waveguide (2) to change its effective refractive index, thereby causing a frequency shift phenomenon, that is, attenuation of the signal is achieved at the same frequency point. Finally, the terahertz wave re-enters the straight waveguide (5) through coupling and is output through a second tapered coupling waveguide (6).

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