阅读说明：本技术 一种太赫兹波导及其制备方法 (Terahertz waveguide and preparation method thereof ) 是由 石艺尉 何猛辉 曾嘉富 陈张雄 赵泽巧 朱晓松 于 2021-02-03 设计创作，主要内容包括：本发明涉及一种太赫兹波导及其制备方法,制备方法包括：采用毛细管拉丝的方法将预制管拉制成毛细管；在所述毛细管外镀制金属膜；在所述金属膜外镀制保护层；采用腐蚀法对所述毛细管进行腐蚀。本发明不同于传统的在金属膜内镀制介质膜,而是先拉制作为介质膜的毛细管再镀制金属膜,最后用腐蚀法腐蚀毛细管,可以使毛细管厚度达到最优要求。(The invention relates to a terahertz waveguide and a preparation method thereof, wherein the preparation method comprises the following steps: drawing the prefabricated pipe into a capillary by adopting a capillary wire drawing method; plating a metal film outside the capillary tube; plating a protective layer outside the metal film; and corroding the capillary by adopting a corrosion method. Unlike traditional method of plating dielectric film inside metal film, the present invention produces capillary as dielectric film through drawing, plating metal film and final etching capillary with corrosion method to reach optimal thickness requirement.)

1. A terahertz waveguide preparation method is characterized by comprising the following steps:

drawing the prefabricated pipe into a capillary by adopting a capillary wire drawing method;

plating a metal film outside the capillary tube;

plating a protective layer outside the metal film;

and corroding the capillary by adopting a corrosion method.

2. The terahertz waveguide preparation method of claim 1, wherein the prefabricated tube material is silver iodide, zinc sulfide, zinc selenide, silicon dioxide, polymethyl methacrylate, polyimide, cyclic olefin polymer, cyclic olefin copolymer, polystyrene, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polycarbonate or fluorocarbon polymer.

3. The terahertz waveguide preparation method of claim 1, wherein the metal film is plated by a liquid phase plating method, a metal vacuum evaporation method or a metal sputtering method.

4. The terahertz waveguide preparation method according to claim 1, wherein the metal film material is gold, silver, copper or aluminum.

5. The terahertz waveguide preparation method according to claim 1, wherein the protective layer material is plastic.

6. The terahertz waveguide preparation method according to claim 1, wherein the capillary is etched by an etching method, specifically:

and circularly introducing a cyclohexane-ethanol mixed solution into the capillary by using a peristaltic pump, and corroding the capillary by using the cyclohexane-ethanol mixed solution.

7. The terahertz waveguide preparation method of claim 1, wherein the thickness of the capillary after etching is 8 μm to 80 μm.

8. A terahertz waveguide, characterized in that the terahertz waveguide is prepared by the terahertz waveguide preparation method of any one of claims 1 to 7, and the terahertz waveguide is provided with a capillary tube, a metal film and a protective layer in sequence from inside to outside.

Technical Field

The invention relates to the technical field of terahertz waveguides, in particular to a terahertz waveguide and a preparation method thereof.

Background

The metal/dielectric waveguide is obtained by respectively plating a metal film and a dielectric film on the inner wall of the base tube. Due to the existence of the dielectric film, the reflectivity of the inner surface of the waveguide is increased by the dielectric metal film waveguide, the ratio of energy in an air core during transmission is greatly improved, and dry air is a low-absorption medium, so that compared with the metal film waveguide, the metal dielectric film waveguide reduces transmission loss.

As THz waves (terahertz waves) are reflected for multiple times at the boundary of air/medium and the boundary of medium/metal, the dielectric film in the dielectric metal film waveguide is like a Fabry-Perot interference cavity, and the optimal film thickness value can be obtained by combining the theory of transmitting electromagnetic waves by hollow waveguide and the influence of the dielectric film on the waveguide transmission loss. The optimal film thickness is that the transmission loss of the waveguide is minimum by corresponding to the thickness of a dielectric film at a certain wavelength. There have been some theories regarding the use of dielectric metal film waveguides in the mid and far infrared bands. When the transmission wavelength is far smaller than the inner diameter of the waveguide, the optimal film thickness of the dielectric film with the lowest loss obtained by the dielectric metal film waveguide is as follows:

wherein n is_dIs the refractive index of the dielectric film material, and lambda is the transmission wavelength. The optimum film thickness should be slightly smaller than the theoretical value in consideration of the absorption coefficient of the dielectric film and the roughness of the surface.

The effectiveness of this conventional approach in mid-infrared hollow core waveguides has been confirmed by a number of theoretical and experimental results. However, when the terahertz wave is applied to the terahertz wave band, the existing dielectric/metal waveguide is limited by the process flow from outside to inside, and can be plated to about 15 micrometers at most, and the required mold thickness cannot be plated. And the drawing capillary can only be drawn to the thickness of about 80 microns at least, so that a dielectric layer with the thickness of 15-80 microns cannot be realized.

Disclosure of Invention

The invention aims to provide a terahertz waveguide and a preparation method thereof, so that the thickness of a dielectric film meets the optimal requirement.

In order to achieve the purpose, the invention provides the following scheme:

a terahertz waveguide preparation method comprises the following steps:

drawing the prefabricated pipe into a capillary by adopting a capillary wire drawing method;

plating a metal film outside the capillary tube;

plating a protective layer outside the metal film;

and corroding the capillary by adopting a corrosion method.

Optionally, the precast tube material is silver iodide, zinc sulfide, zinc selenide, silicon dioxide, polymethyl methacrylate, polyimide, cyclic olefin polymer, cyclic olefin copolymer, polystyrene, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polycarbonate, or fluorocarbon polymer.

Optionally, the metal film is plated by a liquid phase plating method, a metal vacuum evaporation method or a metal sputtering method.

Optionally, the metal film material is gold, silver, copper or aluminum.

Optionally, the protective layer material is plastic.

Optionally, the capillary is etched by using an etching method, specifically:

and circularly introducing a cyclohexane-ethanol mixed solution into the capillary by using a peristaltic pump, and corroding the capillary by using the cyclohexane-ethanol mixed solution.

Optionally, the thickness of the capillary after etching is 8 μm to 80 μm.

The terahertz waveguide is prepared by adopting the terahertz waveguide preparation method, and is sequentially provided with a capillary tube, a metal film and a protective layer from inside to outside.

According to the specific embodiment provided by the invention, the invention discloses the following technical effects:

the invention discloses a terahertz waveguide and a preparation method thereof, wherein the preparation method comprises the following steps: drawing the prefabricated pipe into a capillary by adopting a capillary wire drawing method; plating a metal film outside the capillary tube; plating a protective layer outside the metal film; and corroding the capillary by adopting a corrosion method. The invention is different from the traditional method of plating a dielectric film in a metal film, but draws a capillary tube used as the dielectric film first, then plates the metal film, and finally corrodes the capillary tube by a corrosion method, so that the thickness of the capillary tube (namely the dielectric film) can reach the optimal requirement.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

Fig. 1 is a flowchart of a terahertz waveguide preparation method provided by an embodiment of the present invention;

FIG. 2 is a schematic diagram of a terahertz waveguide preparation apparatus provided in an embodiment of the present invention;

FIG. 3 is a dispersion diagram of a dielectric metal film waveguide at 120-230GHz under different dielectric thicknesses according to an embodiment of the present invention;

fig. 4 is a schematic diagram of loss characteristics provided by an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention aims to provide a terahertz waveguide and a preparation method thereof, so that the thickness of a dielectric film meets the optimal requirement.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

As shown in fig. 1-2, the terahertz waveguide preparation method includes:

step 101: and drawing the prefabricated pipe into a capillary by adopting a capillary drawing method. The prefabricated pipe material is silver iodide, zinc sulfide, zinc selenide, silicon dioxide, polymethyl methacrylate, polyimide, cyclic olefin polymer, cyclic olefin copolymer, polystyrene, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polycarbonate or fluorocarbon polymer.

Step 102: and plating a metal film outside the capillary tube. Wherein the metal film is plated by a liquid phase coating method, a metal vacuum evaporation method or a metal sputtering method. The metal film material is gold, silver, copper or aluminum.

Step 103: and plating a protective layer outside the metal film. Wherein, the protective layer material is plastics.

Step 104: and corroding the capillary by adopting a corrosion method. The method specifically comprises the following steps:

and circularly introducing a cyclohexane-ethanol mixed solution or a corresponding corrosive solution into the capillary by using a peristaltic pump, and corroding the capillary by using the cyclohexane-ethanol mixed solution or the corresponding corrosive solution. In a specific embodiment, the thickness of the capillary after etching is 8 μm to 80 μm.

As shown in FIG. 3, when the capillary film thickness is 0, the dispersion is always positive. The thickness of 100, 200 and 300 microns has the characteristic of negative dispersion in certain frequency bands and has zero dispersion point, and a certain value of negative dispersion characteristic can be obtained at 0.1-0.4THz by selecting a certain capillary film thickness. The method can compensate the positive dispersion characteristic of the metal waveguide and reduce the dispersion influence of the information transmission system.

The low-film-thickness waveguide realized by the etching method can also realize low loss at 0.5-5 THz. When the capillary film thickness is 20 microns, the loss characteristics of the waveguide with an inner diameter of 4mm at the wavelength of 100-300 microns and the wavelength of 3THz-1THz are shown in FIG. 4, and it can be seen that the loss of the waveguide is the lowest at 150 microns and 2 THz.

The preparation method of the invention is different from the traditional method of plating the dielectric film on the inner surface of the metal round hollow waveguide, and adopts the sequence of firstly manufacturing the dielectric film and plating the metal film on the outer surface of the dielectric film. By etching the capillary (i.e., the dielectric film), it is possible to achieve optimal film thickness requirements, specifically, by controlling the etching time, any film thickness can be produced. The limitation that the traditional plating method can not plate thicker films is broken through.

The embodiment also provides the terahertz waveguide which is sequentially provided with the capillary tube, the metal film and the protective layer from inside to outside.

The terahertz waveguide in this embodiment may have a working wavelength of a high-frequency band of terahertz, such as 0.5-5THz, or a low-frequency band of terahertz, such as 0.1-0.4 THz. By selecting the correct thickness of the metal film and the dielectric film (namely, the capillary tube) and the proper material of the metal film and the dielectric film, the waveguide can realize the negative dispersion characteristic in the frequency band of 0.1-0.4 THz. And reducing the thickness of the dielectric film of the negative dispersion waveguide by an etching method, so that the low loss characteristic can be realized in a frequency band of 0.5-5 THz.

In the embodiment, the inner diameter of the capillary can be randomly selected from dozens of micrometers to several millimeters so as to adapt to the selection of different light sources and detectors, the flexibility is good, the minimum bending radius can reach within 1 centimeter, the length can reach dozens of meters, and the capillary can be used for low-loss transmission of laser and incoherent wide-spectrum light sources. The dielectric metal waveguide has the characteristic of negative dispersion in a terahertz waveband, and the metal waveguide has positive dispersion, so that the purpose of dispersion compensation can be achieved through the configuration of the two waveguides. Meanwhile, the dielectric metal waveguide has zero dispersion characteristic at some special wavelength points, and can be widely applied to the fields of communication and the like.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.