A preparation method of terahertz hollow waveguide based on plastic heat-shrinkable tube

Abstract

The present invention discloses a method for preparing a terahertz hollow waveguide based on a plastic heat shrink tube, wherein the plastic heat shrink tube is used as a mechanical support structure, a plastic dielectric film is wound on its outer surface or a thin-walled plastic dielectric tube is nested to form a dielectric layer of the hollow waveguide, a viscous glue is coated on the outside of the dielectric layer, a metal foil is wound to form a metal reflection layer of the hollow waveguide, a resin is coated on the outer surface of the metal layer to form a bonding protective layer, a hot fluid is introduced into the plastic heat shrink tube to shrink the core diameter of the heat shrink tube when heated, and then the heat shrink tube is extracted to obtain a terahertz hollow waveguide having a resin bonding protective layer / metal reflection layer / plastic dielectric layer structure. The present invention provides a feasible method for preparing a terahertz hollow waveguide at low cost and high efficiency, which can promote the application of terahertz waveguides in the fields of commercial 6G wired communications, etc.

Description

Technical Field

[0001] The present invention relates to the technical fields of optoelectronic devices and waveguide transmission of electromagnetic waves, and in particular to a terahertz hollow waveguide based on a plastic heat-shrinkable tube and a preparation method thereof. Background Art

[0002] Terahertz waves are electromagnetic waves with frequencies of 0.1 - 10 THz (wavelengths of 3000 - 30 μm). Their unique properties make them have important application prospects in the fields of communication (broadband communication), radar, electronic countermeasure, electromagnetic weapons, astronomy, sensing, medical imaging, non-destructive testing, security inspection, etc.

[0003] The waveguide transmission of terahertz waves is one of the important research contents in the field of terahertz science and technology, one of the key technologies to improve the system integration and operation stability of terahertz devices, and also an indispensable means for commercial 6G wired communication. However, many materials have a large absorption of terahertz waves, making the preparation of terahertz waveguides a difficult point.

[0004] Currently, the developed terahertz waveguides include metal wire waveguides, polymer dielectric tube waveguides, photonic crystal waveguides, and metal or metal / dielectric hollow waveguides, etc. Among them, metal or metal / dielectric hollow waveguides have lower losses and show strong practical potential. Currently, the preparation of metal or metal / dielectric hollow waveguides is mainly achieved by plating metal reflection film layers and dielectric layers on the inner or outer surface of glass capillary tubes or plastic capillary tubes using wet chemical coating processes. The process is relatively cumbersome, time-consuming, and the raw material cost is relatively high. In addition, affected by the fact that the thickness of the optical reflection film prepared in the chemical coating process shows a certain gradient change along the waveguide length direction, the length of the prepared waveguide is generally limited. The above reasons have restricted the commercialization process of metal or metal / dielectric terahertz hollow waveguides to a certain extent. Therefore, seeking a simpler, more efficient, and lower-cost preparation method for terahertz hollow waveguides has become an urgent problem to be solved currently. Summary of the Invention

[0005] The purpose of the present invention is to provide a terahertz hollow waveguide based on a plastic heat-shrinkable tube and a preparation method thereof in view of the deficiencies of the prior art. This method has significant advantages such as low raw material cost, simple process, easy adjustment of low-loss windows, fast formation of metal reflection film layers, and stable quality compared with the method of preparing terahertz hollow waveguides by traditional chemical coating processes, and provides a practical method for industrial production of terahertz hollow waveguides.

[0006] The specific technical solution to achieve the purpose of the present invention is as follows:

[0007] A method for preparing a terahertz hollow waveguide based on a plastic heat-shrinkable tube, which uses the plastic heat-shrinkable tube as a mechanical support structure; a plastic dielectric film is wound around its outer surface or a thin-walled plastic dielectric tube is nested to form a hollow waveguide dielectric layer, and a viscous adhesive liquid is coated on the dielectric layer and then a metal foil is wound to form a hollow waveguide metal reflection layer; or a metal / plastic dielectric composite film is directly wound around the plastic heat-shrinkable tube to form a dielectric layer and a metal reflection layer; a resin is coated on the metal reflection layer to form a bonding protective layer; by introducing a hot fluid into the plastic heat-shrinkable tube, the plastic heat-shrinkable tube is heated and its core diameter shrinks, and then the shrunk plastic heat-shrinkable tube is extracted to obtain a terahertz hollow waveguide with a resin bonding protective layer / metal reflection layer / plastic dielectric layer structure, and finally the prepared terahertz hollow waveguide is inserted and installed in a plastic protection tube or a metal armor protection tube for use;

[0008] The plastic heat-shrinkable tube is made of polyolefin, polyester, silicone rubber or fluoroplastics; the outer surface of the heat-shrinkable tube is smooth, and the cross-sectional shape is circular, elliptical, rhombic, square or rectangular; the wall thickness is 0.15 - 3 mm, and the core diameter is 1.5 - 8 mm;

[0009] The plastic dielectric film and the thin-walled plastic dielectric tube are made of polymers with low absorption at the terahertz frequencies to be transmitted, including polystyrene, polypropylene, polytetrafluoroethylene, polyethylene, cycloolefin polymer, polyester or polyimide; the thickness of the plastic dielectric film is 3 - 600 μm, meeting the need to adjust the low-loss window of terahertz-band electromagnetic waves; the wall thickness of the thin-walled plastic dielectric tube is 10 - 600 μm, and the hollow diameter is 1.85 - 14.1 mm;

[0010] The viscous adhesive liquid is an adhesive with low absorption at the terahertz frequencies to be transmitted, including polystyrene glue, polyethylene glue, polypropylene glue or liquid paraffin glue;

[0011] The metal foil is a metal that has a reflecting effect on the terahertz waves to be transmitted, including aluminum foil, tin foil, copper foil, nickel foil, silver foil or gold foil; the thickness of the metal foil is 3 - 500 μm;

[0012] The metal / plastic dielectric composite film includes a metal / plastic composite film made of one metal among aluminum, copper, silver, nickel, tin and gold and one plastic dielectric material among polypropylene, polyethylene, polystyrene, polytetrafluoroethylene, cycloolefin polymer, polyimide and polyester by vacuum thermal evaporation, magnetron sputtering, casting, electroless plating or electroplating methods; the total thickness of the metal / plastic dielectric composite film is 6 - 1100 μm, where the thickness of the metal layer is 3 - 500 μm and the thickness of the dielectric layer is 3 - 600 μm;

[0013] The winding includes spiral winding or circumferential winding. The edges of the film or foil tape are closely butt-jointed or have an overlap of 1-10 mm. The winding operation is completed manually or by a winding machine. When spirally winding, the angle between the film or foil tape and the axis of the heat-shrinkable tube is 10°-85°. When circumferentially winding, the angle between the film or foil tape and the axis of the heat-shrinkable tube is 0°.

[0014] The resin coating includes epoxy resin, unsaturated polyester resin, acrylic resin or silicone resin, and the total thickness of the resin coating layer is controlled within 100-3000 μm.

[0015] The hot fluid includes hot air fluid, hot nitrogen fluid, hot water fluid or hot oil fluid. When introducing the hot fluid into the heat-shrinkable tube, air cooling or water cooling is performed on the outside of the sample.

[0016] The waveguide insert is used by being installed in a plastic protection tube or a metal armor protection tube. The plastic protection tube includes tubes made of polyolefin, polyester, silicone rubber, fluoroplastics or polyamide. The metal armor protection tube includes single-button or double-button stainless steel armor tubes.

[0017] A terahertz hollow waveguide based on a plastic heat-shrinkable tube prepared by the above method.

[0018] In the present invention, first, a plastic heat-shrinkable tube is used as a mechanical support structure, and a plastic dielectric film is wound on its outer surface or a thin-walled plastic dielectric tube is nested to form a dielectric layer of the terahertz hollow waveguide. Then, after coating a viscous adhesive liquid on the dielectric layer, a metal foil is wound to form a metal reflection layer of the terahertz waveguide; or a metal / plastic dielectric composite film is directly wound on the outside of the plastic heat-shrinkable tube to form a metal reflection layer and a dielectric layer. Then, a resin is coated on the outer surface of the metal layer to form a bonding protection layer. By introducing a hot fluid into the plastic heat-shrinkable tube to heat and shrink the core diameter of the heat-shrinkable tube and then pulling it out, a terahertz hollow waveguide with a resin bonding protection layer / metal reflection layer / plastic dielectric layer structure is obtained. Finally, the prepared waveguide insert is used by being installed in a plastic or metal armor protection tube.

[0019] In the present invention, by selecting the materials of the metal layer and the dielectric layer and adjusting their thicknesses, the low-loss window of the waveguide can be adjusted, and low-loss transmission of terahertz waves with different frequencies can be achieved. The dielectric layer can also prevent the metal layer from directly contacting the air and oxidizing, improving the durability of the waveguide.

[0020] The present invention uses plastic heat shrinkable tubes, metal foils, plastic dielectric films, or thin-walled dielectric tubes, or metal / plastic dielectric composite films with a relatively high degree of industrialization and high cost performance as raw materials, and uses a winding process to replace the traditional chemical coating process to construct the metal reflection layer and dielectric layer of the hollow waveguide. A plastic heat shrinkable tube with a certain mechanical support strength is used as the inner mold in the winding process of the hollow waveguide. After winding, a viscous resin layer with an appropriate thickness is coated on the outer surface of the metal to enable the waveguide to obtain sufficient mechanical support strength. At the same time, the problem of difficult removal of the inner lining mold after winding the hollow waveguide structure on a slender capillary tube is solved by utilizing the characteristic that the core diameter of the heat shrinkable tube shrinks when heated. In most terahertz frequency bands, the thickness of the dielectric layer corresponding to the low-loss window of the metal / dielectric hollow waveguide is relatively thin, and the hollow diameter of the waveguide is relatively large. Winding the metal foil directly on the surface of a thin-walled dielectric tube with corresponding wall thickness and hollow diameter dimensions is likely to cause deformation or collapse due to the insufficient mechanical support strength of the dielectric tube.

[0021] In the present invention, the problems of winding deformation and difficult demolding inside the tube are overcome by nesting the thin-walled dielectric tube on the thick-walled heat shrinkable tube. The present invention proposes a simple, efficient, and low-cost preparation method for terahertz hollow waveguides, which can realize the online production of terahertz hollow waveguides and promote the application of terahertz waveguides in building terahertz device systems with high stability and high integration and the commercialization of 6G terahertz wired communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the terahertz hollow waveguide prepared by the present invention based on a heat shrinkable tube to construct a dielectric layer, a metal reflection layer, and a resin bonding protective layer;

[0023] Figure 2 Schematic diagram of the process for preparing the terahertz hollow waveguide in Example 1 of the present invention;

[0024] Figure 3 Schematic diagram of the process for preparing the terahertz hollow waveguide in Example 2 of the present invention;

[0025] Figure 4 Schematic diagram of the process for preparing the terahertz hollow waveguide in Example 3 of the present invention;

[0026] Figure 5 Schematic diagram of the process for preparing the terahertz hollow waveguide in Example 4 of the present invention. EMBODIMENTS

[0027] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0028] The present invention provides a method for preparing a terahertz hollow waveguide based on a plastic heat-shrinkable tube. In this method, the plastic heat-shrinkable tube 1 is first used as a mechanical support structure. A plastic dielectric film 2 is wound around its outer surface or a thin-walled plastic dielectric tube 3 is nested to form a hollow waveguide dielectric layer 4. After applying a viscous glue 5 on the dielectric layer, a metal foil 6 is wound to form a hollow waveguide metal reflection layer 7; alternatively, a metal / plastic dielectric composite film 8 is directly wound around the heat-shrinkable tube to form the dielectric layer 4 and the metal reflection layer 7. A resin 9 is coated on the outer surface of the metal reflection layer to form a hollow waveguide bonding protective layer 10. By introducing a hot fluid 11 into the plastic heat-shrinkable tube, the heat-shrinkable tube 1 is heated and its core diameter shrinks, and then the shrunk heat-shrinkable tube 1 is withdrawn to obtain a terahertz hollow waveguide 12 having a structure of resin bonding protective layer 10 / metal reflection layer 7 / plastic dielectric layer 4 (see Figure 1 as shown). Finally, the prepared waveguide is inserted and installed into a plastic protective tube or a metal armor protective tube for use.

[0029] The plastic heat-shrinkable tube 1 includes, but is not limited to, polyolefin, polyester, silicone rubber or fluoroplastic materials. The outer surface of the heat-shrinkable tube is smooth, and the cross-sectional shape includes, but is not limited to, circular, elliptical, rhombic, square, rectangular, etc. The surface of the tube is smooth, and the wall thickness and core diameter or side length should be appropriate to meet the support strength required by the winding process and to adjust the loss value of the hollow waveguide and the frequency position of the low-loss window. The specific material selection should also consider the temperature requirements for heat shrinkage demolding. Preferably, a plastic heat-shrinkable tube with a wall thickness of 0.3-2 mm, a core diameter of 1.5-8 mm, and a heat shrinkage temperature of about 100 °C can be used to conveniently prepare a terahertz hollow waveguide.

[0030] The plastic dielectric film 2 and the thin-walled dielectric tube 3 are usually polymer materials with low absorption of the terahertz waves to be transmitted, including, but not limited to, polystyrene, polypropylene, polytetrafluoroethylene, polyethylene, and polyimide. The thickness of the dielectric film 2 should be appropriate to adjust the loss value of the hollow waveguide and the low-loss window, and at the same time, it should also meet the requirements of the winding process for the flexibility and necessary mechanical strength of the film. Preferably, a dielectric film with a thickness of 3-600 μm can achieve the conditions of a low-loss window for electromagnetic waves in the terahertz band. A thin-walled dielectric tube 3 can also be used to construct the dielectric layer of the hollow waveguide. Considering that in most of the terahertz band, the dielectric layer corresponding to the low-loss window of the metal / dielectric hollow waveguide is relatively thin and the core diameter is relatively large, and its mechanical support strength is not high, it is easy to deform when a metal foil is wound directly on its surface. Therefore, nesting it on a plastic heat-shrinkable tube with higher mechanical strength can overcome this problem. The cross-sectional shape and size of the dielectric tube should be just suitable for nesting on the surface of the plastic heat-shrinkable tube. Preferably, a dielectric tube with a wall thickness of 10-600 μm and a hollow diameter of 1.85-14.1 mm can be selected.

[0031] The viscous adhesive liquid 5 coated on the surface of the dielectric film is a material with low absorption of the transmitted electromagnetic wave and certain bonding effect on the dielectric layer, including but not limited to polystyrene glue, polyethylene glue, polypropylene glue, and liquid paraffin glue. It can bond the metal foil layer with the metal reflection layer and dielectric layer composed of the plastic dielectric film 2 or the thin-wall dielectric tube 3 together.

[0032] The metal foil 6 is a metal that has a reflection effect on the transmitted electromagnetic wave, including but not limited to aluminum foil, tin foil, copper foil, nickel foil, silver foil, and gold foil. The thickness of the metal foil is preferably greater than the skin depth of the corresponding terahertz wave while meeting the requirements of the winding process for the flexibility and necessary mechanical strength of the metal foil. Preferably, the thickness of the metal foil is 3 - 500 μm.

[0033] Constructing the metal reflection layer and dielectric layer of the waveguide using the plastic dielectric film 2, the viscous adhesive liquid 5, and the metal foil 6 can also be achieved by directly winding the flexible metal / plastic dielectric composite film 8 on the outer surface of the heat-shrinkable tube. The thicknesses of the metal layer and the plastic dielectric layer in the composite film material are preferably such that they can reduce the loss value of the hollow waveguide and adjust the frequency position of the low-loss window, and at the same time, they also need to meet the requirements of the winding process for the flexibility and necessary mechanical strength of the film. Preferably, a metal / plastic dielectric composite film with a total thickness of 6 - 11000 μm is selected, where the thickness of the metal layer is 3 - 500 μm and the thickness of the dielectric layer is 3 - 600 μm.

[0034] The winding of the plastic dielectric film 2 or the metal foil 6 or the metal / dielectric composite film 8 includes spiral winding and circumferential winding. Preferably, these materials are cut into rectangular strips for use. When winding, the edges of the film strip are closely butted or overlapped with a 1 - 10 mm lap. For a heat-shrinkable tube with a relatively large bending degree during winding, a metal straight rod can be first inserted into the tube before implementing the winding process. The spiral winding operation can be completed manually or by a mechanical device that can simultaneously rotate the film or foil strip around the circumference of the heat-shrinkable tube and move along the axial direction of the heat-shrinkable tube. In spiral winding, the width of the film strip is related to the outer diameter of the heat-shrinkable tube. Preferably, a 5 mm - 30 mm wide film strip is used to wind the heat-shrinkable tube with an angle of 15° - 80° between the long edge of the film strip and the axial direction of the heat-shrinkable tube. When circumferentially winding, the angle between the long edge of the film strip and the axial direction of the heat-shrinkable tube is 0°.

[0035] The coated resin 9 includes but not limited to epoxy resin, unsaturated polyester resin, acrylic resin, and silicone resin. Its thickness is preferably such that it can provide sufficient mechanical support strength and bending performance for the hollow waveguide structure after the heat-shrinkable tube is removed. Preferably, the total thickness of the resin coating layer is controlled within 100 - 3000 μm.

[0036] The hot fluid 11 includes but is not limited to hot air fluid, hot nitrogen fluid, hot water fluid, and hot oil fluid. The temperature of the hot fluid is controlled to be appropriate for shrinking the core diameter of the plastic heat-shrinkable tube without thermal damage to the dielectric layer. For the case where a hot fluid with a relatively high temperature may be used to heat the heat-shrinkable tube, the outside of the wound finished product coated with a resin layer can be placed in a low-temperature cooling liquid or an air-cooled atmosphere to perform appropriate cooling protection on the hollow waveguide structure 12.

[0037] The prepared terahertz hollow waveguide is inserted into a plastic protective tube or a metal armor protective tube for use to improve the anti-bending and anti-wearing capabilities of the waveguide. The plastic protective tube includes but is not limited to polytetrafluoroethylene tube, polyethylene tube, polyester tube, and polyamide tube; the metal armor protective tube includes but is not limited to single-button or double-button stainless steel armor tubes. Embodiment

[0038] Select a polyester heat-shrinkable tube 1 with a length of 0.8 m, an inner diameter of 4 mm, and a wall thickness of 1.5 mm. Spirally wind a polyethylene film 2 with a width of 17 mm and a thickness of 100 μm on its surface. When winding, the long side of the film strip forms an angle of 35° with the axial direction of the heat-shrinkable tube. Coat a polypropylene glue 5 on the surface of the polyethylene film 2, and then wind a copper foil strip 6 with a width of 17 mm and a thickness of 10 μm. The long side of the foil strip forms an angle of 35° with the axial direction of the heat-shrinkable tube. After winding the copper foil strip, coat an epoxy resin glue 9 on its outer surface. After curing, the thickness of the resin layer is 1.8 mm. Under the condition of water cooling the outer surface of the wound finished product, pass 85°C hot water 11 into the heat-shrinkable tube at a flow rate of 300 ml / min until the heat-shrinkable tube undergoes obvious shrinkage. After cooling, take out the shrunk heat-shrinkable tube 1 to obtain a terahertz hollow waveguide 12 with a main structure of an epoxy resin bonded protective layer 10 / metal copper foil reflective layer 7 / polyethylene dielectric layer 4. For the specific process, refer to Figure 2 as shown; the prepared waveguide is measured for the linear loss of transmitting 0.3 THz terahertz wave to be 4.7 dB / m by the truncation method. Embodiment

[0039] Select a polyolefin material (polyvinyl chloride) heat-shrinkable tube 1 with a length of 1.2 m, an inner diameter of 2 mm, and a wall thickness of 0.8 mm. Spirally wind a silver / polypropylene composite film 8 with a width of 10 mm and a thickness of 67 μm on its surface, where the silver layer thickness is 7 μm and the polypropylene layer is 60 μm. The long side of the film strip forms an angle of 20° with the axial direction of the heat-shrinkable tube. After winding the silver / polypropylene composite film strip, coat a silicone resin glue 9 on its outer surface. After curing, the thickness of the resin layer is 2.5 mm. Under the condition of air cooling the outer surface of the wound finished product, pass 90°C hot water 11 into the heat-shrinkable tube at a flow rate of 130 ml / min until the heat-shrinkable tube 1 undergoes obvious shrinkage. After cooling, take out the shrunk heat-shrinkable tube 1 to obtain a terahertz hollow waveguide 12 with a main structure of a silicone resin protective layer 10 / metal silver reflective layer 7 / polypropylene dielectric layer 4. For the specific process, refer to Figure 3As shown; the prepared waveguide is measured by the truncation method, and the linear loss of transmitting 2 THz terahertz wave is 5.1 dB / m. Example

[0040] Select a silicone rubber heat-shrinkable tube 1 with a length of 0.4 m, an inner diameter of 3 mm, and a wall thickness of 2 mm, and nest a thin-walled polytetrafluoroethylene dielectric tube 3 with a wall thickness of 190 μm and an inner diameter of 7.1 mm on its outer surface. After coating the outer surface of the dielectric tube 3 with a polystyrene solution 5, a copper foil strip 6 with a width of 12 mm and a thickness of 15 μm is spirally wound, and the axial angle between the copper foil strip and the heat-shrinkable tube is 78°. After winding the copper foil strip, an acrylic resin layer 9 is coated on its outer surface, and the thickness of the cured adhesive layer is 2 mm. Under the condition of air-cooling the outer surface of the wound product, hot water 11 at 95 °C is introduced into the heat-shrinkable tube at a flow rate of 250 ml / min until the heat-shrinkable tube shrinks significantly. After cooling, the shrunk heat-shrinkable tube 1 is taken out, and a terahertz hollow waveguide 12 with a main structure of an acrylic resin protective layer 10 / metal copper reflective layer 7 / polytetrafluoroethylene dielectric layer 4 is obtained. For the specific process, refer to Figure 4 As shown; the prepared waveguide is measured by the truncation method, and the linear loss of transmitting 0.1 THz terahertz wave is 7.6 dB / m. Example

[0041] Select a fluoroplastic perfluoroethylene propylene heat-shrinkable tube 1 with a length of 1 m, an inner diameter of 2.5 mm, and a wall thickness of 0.6 mm. Cut a copper / polystyrene composite film 8 into a rectangle with a length of 1 m and a width of 14 mm. The total thickness of the copper / polystyrene composite film is 65 μm, of which the copper layer is 15 μm thick and the polystyrene layer is 50 μm thick. The cut rectangular copper / polystyrene composite film 8 is covered on the outer surface of the perfluoroethylene propylene heat-shrinkable tube 1 by circumferential winding, and the joints are pasted with a tape with a width of 2 mm. Then, an epoxy resin 9 is coated on the outer surface of the composite film, and the cured thickness of the resin layer is 1.5 mm. Under the condition of water-cooling the outside of the wound product after resin coating, hot silicone oil at 105 °C is continuously introduced into the heat-shrinkable tube at a flow rate of 200 ml / min until the heat-shrinkable tube shrinks significantly. After cooling, the shrunk heat-shrinkable tube 1 is taken out, and a terahertz hollow waveguide 12 with a main structure of an epoxy resin protective layer 10 / metal copper reflective layer 7 / polystyrene dielectric layer 4 is obtained. For the specific process, refer to Figure 5 As shown; the prepared waveguide is measured by the truncation method, and the linear loss of transmitting 1 THz terahertz wave is 3.8 dB / m.

Claims

1. A method for preparing a terahertz hollow waveguide based on a plastic heat-shrinkable tube, characterized in that, Using a plastic heat-shrinkable tube (1) as the mechanical support structure; winding a plastic dielectric film (2) on its outer surface or nesting a thin-walled plastic dielectric tube (3) to form a hollow waveguide dielectric layer (4), and coating a viscous adhesive liquid (5) on the dielectric layer and then winding a metal foil (6) to form a hollow waveguide metal reflection layer (7); or directly winding a metal / plastic dielectric composite film (8) on the plastic heat-shrinkable tube (1) to form the dielectric layer (4) and the metal reflection layer (7); coating a resin (9) on the metal reflection layer to form a bonding protection layer (10); passing a hot fluid (11) into the plastic heat-shrinkable tube (1) to cause the core diameter of the plastic heat-shrinkable tube (1) to shrink due to heat, and then extracting the shrunk plastic heat-shrinkable tube (1) to obtain a terahertz hollow waveguide (12) having a resin bonding protection layer (10) / metal reflection layer (7) / plastic dielectric layer (4) structure, and finally fitting and installing the prepared terahertz hollow waveguide (12) into a plastic protection tube or a metal armor protection tube for use; The plastic heat-shrinkable tube (1) is made of polyolefin, polyester, silicone rubber or fluoroplastics; the outer surface of the heat-shrinkable tube is smooth, and the cross-sectional shape is circular, elliptical, diamond-shaped, square or rectangular; the wall thickness is 0.15 - 3 mm, and the core diameter is 1.5 - 8 mm; The plastic dielectric film (2) and the thin-walled plastic dielectric tube (3) are made of polymers with low absorption of the terahertz waves to be transmitted, including polystyrene, polypropylene, polytetrafluoroethylene, polyethylene, cycloolefin polymer, polyester or polyimide; the thickness of the plastic dielectric film (2) is 3 - 600 μm, meeting the requirement of adjusting the low-loss window of terahertz band electromagnetic waves; the wall thickness of the thin-walled plastic dielectric tube (3) is 10 - 600 μm, and the hollow core diameter is 1.85 - 14.1 mm; The viscous adhesive liquid (5) is an adhesive with low absorption of the terahertz waves to be transmitted, including polystyrene glue, polyethylene glue, polypropylene glue or liquid paraffin glue; The metal foil (6) is a metal that has a reflection effect on the transmitted terahertz waves, including aluminum foil, tin foil, copper foil, nickel foil, silver foil or gold foil; the thickness of the metal foil is 3 - 500 μm; The metal / plastic dielectric composite film (8) includes a metal / plastic composite film made of one metal among aluminum, copper, silver, nickel, tin and gold and one plastic dielectric material among polypropylene, polyethylene, polystyrene, polytetrafluoroethylene, cycloolefin polymer, polyimide and polyester by vacuum thermal evaporation, magnetron sputtering, casting molding, electroless plating or electroplating methods; the total thickness of the metal / plastic dielectric composite film is 6 - 1100 μm, wherein the thickness of the metal layer is 3 - 500 μm, and the thickness of the dielectric layer is 3 - 600 μm; The winding of the plastic dielectric film (2) and the winding of the metal foil (6) both include spiral winding or circumferential winding, and the edges of the film or foil tape are closely butted or have an overlap of 1 - 10 mm; the winding operation is completed manually or by a winding machine; when spirally winding, the angle between the film or foil tape and the axis of the heat-shrinkable tube is 10° - 85°; when circumferentially winding, the angle between the film or foil tape and the axis of the heat-shrinkable tube is 0°; The coating resin (9) includes epoxy resin, unsaturated polyester resin, acrylic resin or silicone resin, and the total thickness of the resin coating layer is controlled within 100 - 3000 μm; The hot fluid (11) includes hot air fluid, hot nitrogen fluid, hot water fluid or hot oil fluid; when introducing the hot fluid into the heat shrinkable tube, air cooling or water cooling is performed on the outside of the sample; The prepared terahertz hollow waveguide is inserted into a plastic protective tube or a metal armor protective tube for use. The plastic protective tube includes a tube made of polyolefin, polyester, silicone rubber, fluoroplastics or polyamide; the metal armor protective tube includes a single - buckle or double - buckle stainless steel armor tube.

2. A terahertz hollow waveguide based on a plastic heat shrinkable tube prepared by the method according to claim 1.

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