Waveguide-based terahertz filter

Abstract

The invention discloses a terahertz filter based on a waveguide, and relates to the technical field of millimeter wave functional devices, in the terahertz filter, terahertz broadband signals are transmitted in a double-line waveguide formed by two metal wires arranged in parallel, and the transmission loss of a wave guide structure is small; and meanwhile, the cross resonance effect is only used for filtering guided waves with specific frequency, and no extra insertion loss is introduced to terahertz guided waves far away from the frequency, so that the integrity and the strength of the terahertz guided waves in the transmission process are ensured. In addition, the waveguide cross resonance effect supports selective processing of broadband signals, and the target filtering frequency can be flexibly regulated and controlled by adjusting the waveguide structure design. According to the terahertz filter, based on the cross resonance effect between waveguide substructures, the filtering function can be efficiently achieved in a small space under the condition that a sub-wavelength structure is not introduced, the modular structure is small and exquisite, the design is simple, collimation with other terahertz devices is easy, and system integration of terahertz optical devices can be achieved easily.

Description

Technical Field

[0001] The present invention relates to the technical field of millimeter wave functional devices, and in particular to a terahertz filter based on a waveguide. Background Art

[0002] With the rapid development of information technology, the volume of communication data is exploding. Against this backdrop, existing communication technologies will be unable to meet practical needs in the near future. Compared to traditional microwave communications, where spectrum resources are already increasingly scarce, the terahertz band offers abundant and largely unallocated spectrum, theoretically supporting ultra-high-speed data transmission, thus propelling communication technology into the high-speed era. As a core technology of 6G networks, terahertz communication can meet the needs of a variety of application scenarios requiring high real-time performance and high data volumes. Furthermore, in the field of satellite communications, this technology is suitable for achieving high-speed, broadband data links between satellites and the ground. Furthermore, in the field of the Internet of Things, this technology can meet the requirements for high transmission rates and low latency, supporting the interconnection of large-scale devices and enhancing the intelligence of systems.

[0003] In terahertz communication systems, the performance of key optoelectronic components, such as terahertz radiation sources, signal detectors, signal modulators, and optical field control devices, directly determines the overall system performance and applicable scenarios. Waveguide-based terahertz filters play a key role in this. On the one hand, waveguide-based terahertz filters can improve the quality of communication signals: in complex environments, there are various electromagnetic interference factors. The introduction of filters can effectively suppress non-target frequency signals, allowing only carrier signals in specific terahertz frequency bands to pass, avoiding crosstalk and enhancing the anti-interference capability of the communication system.

[0004] On the other hand, terahertz filtering helps improve spectrum utilization: the terahertz band is rich in spectrum resources, and their rational utilization is crucial for building high-speed communication networks. Filters enable the planning of broadband carrier signals, allocating different frequency bands to different users or services. For example, in a multi-user communication network, filtering can be used to divide the spectrum into multiple sub-bands, allowing each user to communicate using their own dedicated sub-band carrier. Furthermore, filtering technology can be used to achieve spectrum reuse, allowing multiple communication links to coexist, further improving spectrum efficiency, increasing data transmission rates, and expanding the scope of communication services.

[0005] Similar to traditional electromagnetic waves, terahertz radiation propagation can be categorized into two modes: free-space transmission and waveguide transmission. For the former, discrete spatial optical elements such as metasurfaces and diffraction gratings can be introduced into the transmission path, leveraging their physical effects to achieve frequency-selective transmission of broadband terahertz signals. However, free-space light is susceptible to absorption by substances such as water vapor in the atmosphere, resulting in severe signal attenuation. Furthermore, because spatial light requires precise collimation and often lacks effective confinement and shielding, it is susceptible to electromagnetic interference. Finally, the transmission characteristics of terahertz waves are also sensitive to environmental factors such as temperature, humidity, and air pressure, and changes in environmental conditions can affect the optical properties of the signal.

[0006] Furthermore, traditional terahertz waveguide transmission designs are limited by their waveguide mechanisms and typically only support narrow operating bandwidths. Currently, frequency-selective devices such as Bragg gratings, phase-shift gratings, and directional couplers have been developed for filtering, but these devices generally suffer from high passband insertion loss, difficulty in miniaturization, and low modulation depth. Summary of the Invention

[0007] Based on this, it is necessary to provide a waveguide-based terahertz filter to address the above technical problems.

[0008] The present invention adopts the following technical solutions: The present invention provides a waveguide-based terahertz filter, comprising: Two metal conductor lines and hollow dielectric optical fiber structure; The two metal conductor lines are arranged at intervals in the hollow dielectric optical fiber structure to form a double-line plasma waveguide; The hollow dielectric fiber structure is used to achieve interaction with the double-wire plasma waveguide substructure, introduce a mode cross-resonance effect, and improve the terahertz wave transmission loss within the frequency range of the mode cross-resonance effect to achieve filtering of terahertz signals within the corresponding frequency range; The double-wire plasma waveguide formed by the two metal conductor lines is used to support the transmission of broadband terahertz signals in a single-line deflected transverse electromagnetic wave mode within the two-wire air gap.

[0009] Optionally, the hollow dielectric optical fiber structure is formed of a polymer having an electromagnetic absorption property less than a preset threshold.

[0010] Optionally, the transmission characteristics and operating frequency band of the dual-wire plasma waveguide filter are determined based on the shapes of the dual metal conductor wires and the hollow dielectric optical fiber structure.

[0011] At least one of the above technical solutions adopted by the present invention can achieve the following beneficial effects: In the waveguide-based terahertz filter of the present invention, terahertz waves are transmitted in a double-wire waveguide composed of two parallel metal conductors. The waveguide structure has a small transmission loss for the passband. At the same time, the cross-resonance effect is only used to filter signals of a specific frequency, and no additional insertion loss is introduced for terahertz waveguides far away from this frequency. The overall transmission loss is low, ensuring the integrity and strength of the passband signal during transmission.

[0012] Furthermore, the cross-resonance effect between the waveguides enables flexible and precise filtering of terahertz signals at specific operating frequencies, forming a sharp loss peak at that location in the waveguide transmission spectrum. This allows the filter to effectively reduce the intensity of the transmitted signal within a tunable frequency range and can be used to distinguish between very close frequencies. This provides an ideal solution for high-resolution imaging and communication multiplexing. Furthermore, the bandwidth of this filter is determined by the structure of the two sub-waveguides, allowing for flexible structural design to control the operating frequency band position and bandwidth.

[0013] Compared to traditional terahertz filters, dual-wire plasmonic waveguides support low-variance, specific transmission of signals with bandwidths exceeding hundreds of GHz, while exhibiting low transmission loss. This significantly reduces signal energy attenuation and enables stable signal transmission over long distances. Using these waveguides as a technology platform, designs based on cross-resonance between waveguides can achieve efficient filtering in a compact space without introducing subwavelength structures. This is particularly beneficial for miniaturization and cost-effectiveness of terahertz systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0015] Figure 1 A schematic cross-sectional view of a waveguide-based terahertz filter provided by the present invention; Figure 2 A schematic diagram of the waveguide energy band of a terahertz double-line waveguide filter provided by the present invention; Figure 3 A schematic diagram of the waveguide energy band in the cross-resonance region of a terahertz double-line waveguide filter provided by the present invention; Figure 4 A schematic diagram of the fundamental mode electric field distribution supported by a waveguide filter provided by the present invention; Figure 5 A schematic diagram showing the relationship between the mode transmission loss of a terahertz dual-line waveguide filter and the change in the inner diameter of a hollow optical fiber provided by the present invention; Figure 6 A schematic diagram showing the relationship between the cross-resonance center frequency and the inner diameter of the hollow fiber of a terahertz dual-line waveguide filter provided by the present invention; Figure 7 A schematic diagram of a terahertz dual-line waveguide filter provided by the present invention; Figure 8 The transmission spectrum of a terahertz double-line waveguide filter provided by the present invention; Figure 9 This is a loss spectrum of a terahertz double-line waveguide filter provided by the present invention. DETAILED DESCRIPTION

[0016] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0017] Currently, signal filtering plays a key role in terahertz scientific research and industrial applications in scenarios such as communications and imaging. While the terahertz band boasts vast spectrum resources and supports broadband, ultra-high-speed data transmission, it is often affected by stray signals such as reflection and scattering, as well as interference from other electronic devices, in actual use. Using filters can effectively suppress noise and reduce communication bit error rates. On the other hand, in applications such as frequency reuse, filters can accurately select preset communication frequency bands, providing carrier signals in specific frequency bands for different services or users, avoiding crosstalk between channels and increasing communication capacity. In imaging, filters can improve image resolution and enhance the contrast between targets and backgrounds in images by suppressing background noise and stray signals. Taking biological tissue imaging and spectral analysis as an example, since different samples have different absorption and reflection characteristics for terahertz waves, filtering technology can highlight the characteristic frequency signals of target tissues.

[0018] In the terahertz band, efficient and controllable processing of signals at specific frequencies often requires the use of high-performance filters at multiple locations within the optoelectronic system. Currently, terahertz filtering technologies primarily focus on spatial optical filters and waveguide filters. However, these technologies still face several challenges. First, regarding performance stability, traditional filters are sensitive to variations in their structural morphology and surrounding environment. Small changes, such as temperature and humidity fluctuations or external mechanical stress, can easily cause variations in filtering characteristics, impacting the filter's performance stability and long-term reliability. Second, the subwavelength features commonly used to achieve terahertz filtering are typically only a few hundred or even tens of microns in size, requiring stringent fabrication precision. Minor dimensional errors can significantly impact structural performance. Furthermore, while micro-nanofabrication technologies can achieve some structures, they are costly, inefficient, and present bottlenecks in the mass production of large-scale components. This has limited the development of large-scale miniaturization of waveguide-based terahertz filters. Furthermore, the fabrication process is susceptible to multiple factors, including electron beam stability, photoresist properties, and substrate surface conditions.

[0019] Among them, spatial optical components, such as metasurfaces and diffraction gratings, are commonly used to process free-space terahertz signals. However, their structural units usually need to be compressed to subwavelength scales, and the overall size needs to reach the order of several wavelengths. This places extremely high demands on the precision of the manufacturing process. The current solution has high manufacturing costs and is challenging to mass produce. In addition, small processing errors can easily cause deviations in the electromagnetic response characteristics of the metasurface, causing key parameters such as filtering frequency and bandwidth to deviate from the predetermined design, affecting the actual use of the filter.

[0020] Reported terahertz waveguide filters based on structures such as Bragg gratings and resonant rings have certain shortcomings in terms of technical implementation and performance. The operating bandwidth of the former is controlled by the coupling coefficient between the microring and the waveguide, which is relatively narrow. In actual design and manufacturing, precise adjustment is difficult, especially for applications that require high extinction ratio filtering within a wide bandwidth. In addition, its center frequency is easily affected by environmental factors such as temperature changes and mechanical stress, resulting in center frequency offset. The latter Bragg grating structure requires periodic regulation of the refractive index on the waveguide structure, which requires high manufacturing precision. In addition, the sub-wavelength dimensional deformation currently used will significantly increase the scattering loss of the passband signal, resulting in large device insertion loss.

[0021] Waveguide-based filters support the transmission and manipulation of terahertz radiation within a controlled environment within the waveguide structure. Common terahertz waveguides, such as polymer optical fibers and rectangular metal waveguides, present inherent technical bottlenecks. Polymer optical fibers are affected by substrate material losses and are sensitive to external interference. They suffer from high waveguide transmission losses, and most fiber designs struggle to support complex signal processing functions. While rectangular metal waveguides offer stable waveguide performance, they are bulky and heavy, and the difficulty of introducing subwavelength-sized features within a closed structure hinders efficient signal processing applications.

[0022] In terms of filtering function realization, existing waveguide device designs, such as resonant rings and Bragg gratings, have technical difficulties in design and preparation. The operating bandwidth of the former is controlled by the coupling coefficient between the microring and the waveguide, which is relatively narrow. In the actual design and manufacturing process, precise adjustment is difficult, especially for applications such as high extinction ratio filtering within a wide bandwidth. In addition, its center frequency is easily affected by environmental factors such as temperature changes and mechanical stress, resulting in center frequency offset. The latter Bragg grating structure requires periodic regulation of the refractive index on the waveguide structure, which requires high manufacturing precision. In addition, the sub-wavelength dimensional deformation currently used will significantly increase the scattering loss of the passband signal, resulting in large device insertion loss.

[0023] In contrast, dual-line waveguides support large-bandwidth, low-loss, and low-dispersion signal transmission, and have a semi-closed and compact structure. While having stable performance, they also have strong structural expansion space, a low threshold for preparation technology, and support the introduction of macro- and micro-feature structures.

[0024] The filter developed in this paper, based on the cross-resonance effect between waveguides, circumvents many of the shortcomings of traditional terahertz filtering technology. Cross-resonance refers to the phenomenon in which different optical waveguide modes at the same frequency couple with each other, forming a frequency gap in the waveguide energy band. This effect is common in photonic crystal fibers and manifests itself as high transmission loss for terahertz signals within a specific frequency range. Considering the coupling of two guided wave modes, it can be expressed as:

[0025] dA1 / dz=iβ1A1+ikA2 dA2 / dz=iβ2A2+ikA1 where A1 and A2 are the amplitudes of the two modes, β1 and β2 are their respective propagation constants, and k is the coupling coefficient.

[0026] Near a certain frequency, the propagation constants of the two modes are close. Due to the coupling between the two modes, the band diagram shows that the propagation constants are not simply crossed, but the two bands are "split": In the cross-resonance region, the guided wave modes are no longer independent but become mixed modes, where each new mode is a linear combination of the original modes. This mixing of modes causes the characteristics of the two modes to influence each other, ultimately forming a frequency gap. The center of the frequency gap has significant guided wave mode loss, which can be used to implement optical filtering.

[0027] In this invention, cross-resonance is the key mechanism for achieving filtering. When cross-resonance occurs, terahertz waves experience significant transmission loss only near this frequency. THz signals away from this characteristic frequency exhibit similar waveguide performance to conventional two-wire waveguides. Therefore, terahertz signals within this frequency range are effectively filtered while maintaining low insertion loss for broadband signals.

[0028] Compared to other waveguide-based filters, the cross-resonance filtering implemented in this invention relies on the interaction between sub-waveguides, enabling implementation in a compact, controlled environment and precise adjustment of the operating signal's frequency and bandwidth. Thanks to the low-loss characteristics of the dual-wire metal waveguide technology platform for terahertz waves, this filter has minimal impact on passband signals. Furthermore, since it does not involve subwavelength structures, it requires minimal manufacturing requirements.

[0029] The technical solutions provided by various embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] Figure 1 is a cross-sectional diagram of a waveguide-based terahertz filter in the present invention, consisting of Figure 1 It can be seen that the invention comprises: two metal conductor lines and a hollow dielectric optical fiber structure, wherein the two metal conductor lines are arranged at intervals in the hollow dielectric optical fiber structure to form a double-line plasma waveguide.

[0031] Among them, the hollow dielectric fiber structure is used to realize interaction with the double-line plasma waveguide structure, introduce the mode cross-resonance effect, and improve the terahertz waveguide transmission loss within the frequency range of the mode cross-resonance effect to achieve the filtering of terahertz signals in the corresponding frequency range.

[0032] A double-wire plasma waveguide composed of two metal conductor lines is used to support the transmission of broadband terahertz signals in a single-line transverse electromagnetic wave mode within the air gap between the two lines.

[0033] The hollow core optical fiber structure is formed by a polymer with low electromagnetic absorption characteristics, and the specific type of polymer can be determined according to transmission needs.

[0034] Figure 1The yellow portion in the center represents the metal wires, which support low-loss transmission of broadband terahertz signals. The gray portion represents the outer shell, which is based on a polymer with low material absorption. In this design, the metal wires are encapsulated within the shell. This not only protects the waveguide from external environmental factors, ensuring stable performance, but also introduces cross-resonance effects, enabling filtering of signals at specific frequencies. The polymer in question can be, for example, epoxy resin.

[0035] The terahertz dual-wire plasma waveguide filter of the present invention integrates a bimetallic conductor structure with an outer hollow dielectric fiber. Based on the cross-resonance of the supported modes of the two sub-waveguide structures, it filters terahertz waveguide signals of specific frequencies. Its operating frequency and bandwidth are highly controllable. Specifically, the transmission characteristics of the dual-wire plasma waveguide filter are determined by the shapes of the two metallic conductors and the hollow dielectric fiber structure, and can be adjusted accordingly. The shape of the bimetallic conductors includes the distance between the two conductors; the shape of the hollow dielectric fiber structure includes the inner diameter of the hollow dielectric fiber structure. For example, the transmission characteristics and operating frequency band of the dual-wire plasma waveguide filter are determined by the distance between the two metallic conductors and the inner diameter of the hollow dielectric fiber structure.

[0036] This waveguide-based terahertz filter consists of two parallel metal conductors and an outer hollow polymer shell. The former supports low-loss transmission of electromagnetic waves within the air gap between the two wires in a single, linearly biased transverse electromagnetic wave mode. The latter provides physical support for the dual-wire structure and introduces a modal cross-resonance effect, achieving high transmission loss for the waveguide at specific frequencies while supporting low insertion loss at frequencies beyond these frequencies. The waveguide's transmission characteristics and operating frequency band can be controlled and adjusted by adjusting the shape and relative position of the internal dual wires and the outer shell.

[0037] The cross-resonance effect between waveguides of the terahertz filter based on the waveguide of the present invention can flexibly and accurately filter out terahertz signals of a specific operating frequency, forming a sharp loss peak at this position in the waveguide transmission spectrum, allowing the filter to effectively reduce the intensity of the transmitted signal within an adjustable frequency range, and can be used to distinguish very close frequencies. This provides an ideal solution for high-resolution imaging and communication multiplexing. In addition, the bandwidth of this filter is determined by the two-sub-waveguide structure, and the structural design can be flexibly adjusted to control the operating frequency band. It has strong controllability and can optimize the transmission characteristics, frequency response and filtering range of the waveguide by adjusting the structural parameters of the dual-line waveguide filter, such as the inner and outer diameters of the polymer optical fiber. It has high frequency selectivity and can accurately select and filter out terahertz signals of a specific frequency, while allowing terahertz waves outside the selected frequency to pass normally, and the operating frequency position and its bandwidth are highly controllable. This characteristic enables the filter to effectively transmit or suppress terahertz waveguide signals within an extremely narrow frequency range.

[0038] In addition, the waveguide-based terahertz filter of the present invention has low insertion loss for passband signals. Considering that the terahertz radiation power is relatively weak, the lower insertion loss can ensure the strength of the broadband signal after filtering, which is beneficial to subsequent signal processing and analysis, and reduces the restrictions on the signal power of active devices such as terahertz radiation sources and amplifiers. Terahertz waves are transmitted in a two-wire waveguide composed of two parallel metal conductors, and the transmission loss of the waveguide structure itself is relatively small. At the same time, the cross-resonance effect is only used to filter signals of a specific frequency, and no additional insertion loss is introduced to the terahertz waveguide far away from this frequency. Using a unique integrated architecture design of plasma double wires and polymer shells, on the one hand, the broadband terahertz signal is confined between the two wires to support low-loss transmission. On the other hand, the cross-resonance effect has little effect on the conduction band signal of the non-resonant frequency, effectively reducing the attenuation of the passband waveguide and ensuring the integrity and strength of the signal during transmission.

[0039] In addition, compared with traditional terahertz filters, the design based on the cross-resonance effect between waveguides can achieve efficient filtering functions in a smaller space without introducing subwavelength structures. This is particularly beneficial for the miniaturization and low cost of terahertz devices, and supports integration into systems such as terahertz detection equipment or small communication terminals to further enhance the portability and practicality of terahertz optoelectronic devices. The filter has a simple structure, short length and stable performance, with a clear transmission direction and a strong extinction ratio. As a modular structure, it is easy to integrate with other terahertz devices, and with its frequency selection characteristics, it can realize complex functions such as frequency division multiplexing. The structure is compact and easy to integrate. The waveguide-based terahertz filter of the present invention has a small structure and a simple design. The terahertz signal can be efficiently coupled with spatial light or other waveguide devices, and waveguide transmission and controlled processing can be realized in a controlled environment. This design feature makes it easy to integrate with other terahertz devices, which is conducive to the construction of complex terahertz optical systems.

[0040] Figure 2 This is a schematic diagram of the waveguide energy band of a terahertz dual-line waveguide filter provided by the present invention. It can be seen that there is a very obvious cross-resonance effect near 135 GHz.

[0041] Figure 3 A schematic diagram of the cross-resonance region waveguide energy band provided by the present invention, for a clearer observation, Figure 3 Yes Figure 2 The result of zooming in on the area where the cross-resonance effect occurs is that the frequency spacing used in the simulation is more refined. After zooming in, the frequency points in the area near the cross-resonance effect and the frequency points far from the area near the cross-resonance effect are collected for observation. Figure 4 As shown, Figure 4A schematic diagram of the fundamental mode electric field distribution supported by a waveguide filter provided by the present invention shows the field distribution at corresponding frequencies near the cross-resonance effect and in the non-cross-resonance region. Figures i and iv show the electric field distribution of the waveguide mode at two frequencies at the edge of the cross-resonance region, which is primarily concentrated between the two wires. Figures ii and iii show two hybrid modes supported by a single frequency at the center of the cross-resonance region. It can be seen that the electric field distribution is also significant in the area outside the air gap between the two wires, resulting in significant transmission loss.

[0042] Figure 5 The present invention provides a schematic diagram of the relationship between mode transmission loss and the inner diameter of the hollow fiber, showing the loss spectrum of the waveguide-based terahertz filter of the present invention. Figure 5 As can be observed, the loss increases sharply near a specific frequency range, while remaining relatively low at other frequencies. To better understand the impact of morphology design on filtering performance, the waveguide transmission loss corresponding to different inner diameters of polymer hollow-core fibers is shown. The different colored lines in the figure represent different radii. As the radius changes, the frequency corresponding to the cross-resonance effect also changes accordingly. The colors from black to purple represent the inner radius at +0.3mm, +0.15mm, 0, -0.15mm, and -0.3mm, respectively. The results show that cross-resonance regions exist in waveguides of varying sizes, and the frequency of this effect shifts with adjustment of the shell size.

[0043] Figure 6 This is a schematic diagram of the relationship between the cross-resonance center frequency and the change in the inner diameter of the hollow fiber provided by the present invention, which is the relationship between the change in the inner diameter of the waveguide shell and the frequency with the maximum mode loss (i.e., the cross-frequency). The red line is the linear fit of the numerical data. Figure 6 It can be seen that the inner radius of the hollow dielectric fiber structure and the cross-resonance frequency have obvious regularity.

[0044] Figure 7 A schematic diagram of a terahertz dual-line waveguide filter fabricated according to the present invention. The filter was manufactured using 3D printing technology based on simulation dimensions and data. The yellow portion is polymer, and the silvery-white portion is metallic silver. This waveguide-based terahertz filter is divided into two sections, upper and lower, for ease of silver plating, joined by grooves. This waveguide-based terahertz filter exhibits low loss for electromagnetic waves in the terahertz frequency range.

[0045] Figure 8 This is a schematic diagram of the transmission spectrum of a waveguide filter manufactured according to simulation provided by the present invention, showing the transmission spectrum of the waveguide device when the waveguide length is 30mm, 45mm, 60mm, and 75mm. Figure 8 It can be seen that as the length gradually increases, the loss of terahertz waves in the target band increases significantly.

[0046] Figure 9 The frequency and loss diagram of a terahertz dual-line waveguide filter prepared by the present invention is used to illustrate the relationship between the frequency change of the filter and the waveguide loss. Figure 9 It can be seen that the loss of the filter is relatively stable and small in the non-cross-resonance region, but the loss increases rapidly around 135 GHz in the area where cross-resonance occurs.

[0047] It should also be noted that the terms "include", "comprising" or any other variations thereof in the present invention are intended to cover non-exclusive inclusion, that is, in addition to the elements listed in the present invention, other elements that are not explicitly listed may also be included.

[0048] The various embodiments of the present invention are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0049] The foregoing is merely an embodiment of the present invention and is not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of the present invention.

Claims

1. A terahertz filter based on a waveguide, characterized in that: include: Two metal conductor lines and hollow dielectric optical fiber structure; The two metal conductor lines are arranged at intervals inside the hollow dielectric optical fiber structure to form a double-line plasma waveguide structure; The hollow dielectric fiber structure is used to achieve interaction with the double-wire plasma waveguide structure, introduce a mode cross-resonance effect, and improve the terahertz waveguide transmission loss within the frequency range of the mode cross-resonance effect to achieve filtering of terahertz signals within the corresponding frequency range; The double-line plasma waveguide structure formed by the two metal conductor lines is used to support the transmission of broadband terahertz signals in the air gap between the two metal conductor lines in a single linearly biased transverse electromagnetic wave mode.

2. The waveguide-based terahertz filter according to claim 1, wherein: The hollow dielectric optical fiber structure is formed of a polymer having an electromagnetic absorption characteristic less than a preset threshold.

3. The waveguide-based terahertz filter according to claim 2, wherein: The polymer is epoxy resin.

4. The waveguide-based terahertz filter according to claim 1, wherein: The transmission characteristics and operating frequency band of the dual-wire plasma waveguide filter are determined based on the shapes of the dual metal conductor wires and the hollow dielectric fiber structure.

5. The waveguide-based terahertz filter according to claim 4, wherein: The shape of the bimetallic conductor wires includes the bimetallic conductor wire separation distance; The shape of the hollow core dielectric fiber structure includes the inner diameter of the hollow core dielectric fiber structure.

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