Waveguide and preparation method thereof, optical cable and communication device

Abstract

The invention discloses a waveguide and a preparation method thereof, an optical cable and a communication device, and belongs to the technical field of communication. The waveguide includes a first dielectric member and a second dielectric member located therein. The material of the first dielectric component comprises a polymer, the second dielectric component comprises a plurality of single-crystal structural bodies, and the crystal axis with the lowest dielectric loss in the single-crystal structural bodies points to the axial direction of the waveguide; the first dielectric member has a first dielectric constant, and the second dielectric member has a second dielectric constant greater than the first dielectric constant. The waveguide has the advantages of small diameter and low dielectric loss.

Description

Technical Field

[0001] The present disclosure relates to the field of communication technologies, and particularly to a waveguide and a method for manufacturing the same, an optical cable, and a communication device. Background Art

[0002] Terahertz waves are located between infrared light and microwaves, having a relatively high frequency and a relatively short wavelength. A terahertz optical fiber, also known as a THz fiber, as a dielectric waveguide for transmitting terahertz waves, determines indexes such as the transmission distance and transmission density of terahertz waves.

[0003] The terahertz optical fiber based on a polymer material has characteristics of low loss and high transparency. Related technologies use polymers with low-loss characteristics to prepare terahertz optical fibers. Some polymers with low-loss characteristics include: Polypropylene (PP), Polyethylene (PE), Copolymers of Cycloolefin (COC), etc.

[0004] However, the known low-loss polymers currently have a relatively low dielectric constant. In order to confine terahertz waves within the terahertz optical fiber, it is usually necessary to design the fiber diameter to be relatively large, resulting in an increase in the volume of the terahertz optical fiber, which is not conducive to applications in high-density scenarios.

[0005] Disclosure

[0006] Embodiments of the present disclosure provide a waveguide and a method for manufacturing the same, an optical cable, and a communication device, which can solve the technical problems existing in related technologies.

[0007] Specifically, the technical solutions are as follows:

[0008] On the one hand, a waveguide is provided. The waveguide includes: a first dielectric member and a second dielectric member, and the second dielectric member is distributed within the first dielectric member;

[0009] The material of the first dielectric member includes a polymer;

[0010] The second dielectric member includes a plurality of single crystal structures, and the crystal axis with the lowest dielectric loss in the single crystal structure points to the axial direction of the waveguide;

[0011] The first dielectric member has a first dielectric constant, and the second dielectric member has a second dielectric constant, and the second dielectric constant is greater than the first dielectric constant.

[0012] The waveguide provided by the embodiments of the present disclosure forms a first dielectric member using a polymer with low dielectric loss characteristics, and a second dielectric member is distributed in the first dielectric member. On the one hand, the dielectric constant of the second dielectric member is greater than that of the first dielectric member, which is beneficial to increasing the dielectric constant of the waveguide, thereby facilitating the reduction of the waveguide diameter. On the other hand, the second dielectric member includes a plurality of single crystal structures. When the crystal axis with the lowest dielectric loss in the single crystal structure points to the axial direction of the waveguide, the dielectric loss of the single crystal structure is generally less than that of the polymer, which is beneficial to reducing the dielectric loss of the waveguide, so that the waveguide provided by the embodiments of the present disclosure has the advantages of both a smaller waveguide diameter and a lower dielectric loss.

[0013] In some possible implementation manners, the ratio of the dielectric constant of the second dielectric member to the dielectric constant of the first dielectric member is less than or equal to 5 to prevent resonance phenomena from occurring in the signal propagation of the waveguide.

[0014] In some possible implementation manners, the single crystal structure is a single crystal fiber, and the crystal axis in the length direction of the single crystal fiber is the crystal axis with the lowest dielectric loss.

[0015] Utilizing the low dielectric loss characteristic of the single crystal fiber in the length direction, the length direction of the single crystal fiber extends along the axial direction of the waveguide, thereby reducing the dielectric loss of the waveguide. At the same time, the single crystal fiber exists in the form of fibers, and the number of fiber-polymer interfaces is significantly reduced compared to the number of particle-polymer interfaces, which is also beneficial to reducing the overall dielectric loss of the waveguide. It can be seen that the waveguide provided by the embodiments of the present disclosure further optimizes the advantages of a smaller waveguide diameter and a lower dielectric loss.

[0016] In some possible implementation manners, the length direction of the single crystal fiber is the same as the axial direction of the waveguide.

[0017] In some possible implementation manners, the diameter of the single crystal fiber is less than or equal to 100 μm. By making the diameter of the single crystal fiber within the above range, the flexibility of the single crystal fiber is improved, which is beneficial to improving the flexibility of the waveguide, making its bending performance more excellent, thereby realizing a certain degree of bent waveguide characteristics, and then connecting the interfaces of terahertz waves at different positions according to requirements.

[0018] In some possible implementation manners, a plurality of single crystal fibers are provided, and the volume percentage of the plurality of single crystal fibers in the waveguide is less than or equal to 30%. When the volume percentage content of the single crystal fiber is within the above range, it can not only realize the electromagnetic wave transmission of the waveguide in the terahertz band, for example, in the frequency band of 110 GHz to 170 GHz, but also ensure that the waveguide has the desired flexibility.

[0019] In some possible implementation manners, the single-crystal fiber is in the form of a long fiber, and two ends of the single-crystal fiber respectively extend to corresponding two ends of the first dielectric member.

[0020] In some possible implementation manners, the single-crystal fiber is in the form of a whisker, and the aspect ratio of the single-crystal fiber in the form of a whisker is greater than or equal to 5.

[0021] In some possible implementation manners, a plurality of single-crystal fibers are provided, and along the direction from the axis of the first dielectric member to the outer wall of the first dielectric member, the distribution density of the single-crystal fibers shows a decreasing trend.

[0022] By defining the distribution state of the plurality of single-crystal fibers as above, it is beneficial to reduce the dispersion phenomenon of the waveguide when transmitting signals.

[0023] In some possible implementation manners, the single-crystal structure body is a single-crystal particle, the second dielectric member includes a plurality of single-crystal particles, and the crystal axis with the lowest dielectric loss among the single-crystal particles points to the axial direction of the waveguide.

[0024] In some possible implementation manners, the single-crystal material used for the second dielectric member includes at least one of aluminum oxide, silicon carbide, single-crystal silicon, titanium dioxide, magnesium oxide, quartz single-crystal, and graphene.

[0025] In some possible implementation manners, the polymer includes at least one of polyethylene, polypropylene, cycloolefin copolymer, high-density polyethylene, low-density polyethylene, polytetrafluoroethylene, 4-methylpentene polymer, polyurethane, polystyrene, polycarbonate, polymethyl methacrylate, and polyvinyl chloride.

[0026] On the other hand, a method for manufacturing a waveguide is provided, and the waveguide is as described in any one of the above;

[0027] The method for manufacturing the waveguide includes: compounding a first dielectric member and a second dielectric member to obtain a dielectric composite structure;

[0028] Performing waveguide forming treatment on the dielectric composite structure to manufacture the waveguide.

[0029] In some possible implementation manners, the second dielectric member is a single-crystal fiber in the form of a long fiber, and the method for manufacturing the waveguide includes:

[0030] Using a spinning process or an extrusion process to compound a polymer layer on the surface of the single-crystal fiber in the form of a long fiber to obtain the dielectric composite structure;

[0031] Arrange a plurality of the dielectric composite structures in a set arrangement, and then perform heat treatment or sleeve binding treatment to fix the relative positions of the plurality of dielectric composite structures, thereby preparing the waveguide.

[0032] In some possible implementation manners, the second dielectric member is a single crystal fiber in the form of a whisker, and the method for preparing the waveguide includes:

[0033] Mix the single crystal fiber in the form of a whisker and polymer particles according to a set ratio to prepare the dielectric composite material;

[0034] Use a spinning process, an extrusion process, or a 3D printing process to perform fiber forming treatment on the dielectric composite material to prepare the dielectric composite structure;

[0035] Arrange a plurality of the dielectric composite structures in a set arrangement, and then perform heat treatment or sleeve binding treatment to fix the relative positions of the plurality of dielectric composite structures, thereby preparing the waveguide.

[0036] On the other hand, an optical cable is provided, and the optical cable includes any one of the above-mentioned waveguides.

[0037] The optical cable provided by the embodiments of the present disclosure has all the advantages of any one of the above-mentioned waveguides.

[0038] On the other hand, a communication device is provided, and the communication device includes any one of the above-mentioned waveguides, or the above-mentioned waveguide. The communication device provided by the embodiments of the present disclosure has all the advantages of any one of the above-mentioned waveguides. Description of the Drawings

[0039] Figure 1 It is a schematic cross-sectional structure diagram of an exemplary waveguide provided by an embodiment of the present disclosure;

[0040] Figure 2 It is a curve graph showing the variation of loss with frequency of an exemplary waveguide provided by an embodiment of the present disclosure in the frequency band of 110 GHz to 170 GHz;

[0041] Figure 3 It is a curve graph showing the variation of loss with frequency of an exemplary waveguide two provided by an embodiment of the present disclosure in the frequency band of 110 GHz to 170 GHz;

[0042] Figure 4 It is a schematic longitudinal cross-sectional structure diagram of a waveguide having a second dielectric member in the form of a long fiber provided by an embodiment of the present disclosure;

[0043] Figure 5 It is a schematic longitudinal cross-sectional structure diagram of a waveguide having a second dielectric member in the form of a whisker provided by an embodiment of the present disclosure;

[0044] Figure 6 Schematic cross-sectional structure diagram of another exemplary waveguide provided by an embodiment of the present disclosure;

[0045] Figure 7 Schematic structure diagram of an exemplary communication device provided by an embodiment of the present disclosure;

[0046] Figure 8 Curve graph showing the variation of loss with frequency of the waveguide provided in Embodiment 1 of the present disclosure within the frequency band of 120 GHz to 150 GHz;

[0047] Figure 9 Simulated mode field diagram of the waveguide provided in Embodiment 1 of the present disclosure at a frequency of 140 GHz;

[0048] Figure 10 Curve graph showing the variation of loss with frequency of the waveguide provided in Embodiment 2 of the present disclosure within the frequency band of 120 GHz to 150 GHz;

[0049] Figure 11 Curve graph showing the variation of group delay with frequency of the waveguide provided in Embodiment 2 of the present disclosure within the frequency band of 110 GHz to 170 GHz.

[0050] Among them, Figure 2 、 Figure 3 For the curve graph showing the variation of loss with frequency, the abscissa is frequency, with the unit of GHz, and the ordinate is the transmission loss of the waveguide, with the unit of dB. This transmission loss is the ratio of the signal at the output end of the waveguide to the signal at the input end. Figure 8 、 Figure 10 For the curve graph showing the variation of loss with frequency, the abscissa is frequency, with the unit of GHz, and the ordinate is the transmission loss of the waveguide per unit length, with the unit of dB / m.

[0051] Figure 11 For the curve graph showing the variation of group delay with frequency, the abscissa is the test frequency band, with the unit of GHz, and the ordinate is the delay of the waveguide, with the unit of ps.

[0052] The reference numerals respectively represent:

[0053] 100, waveguide;

[0054] 1, first dielectric member; 2, second dielectric member;

[0055] 101, first region; 102, second region;

[0056] 200, terahertz wave transmitting module; 300, terahertz wave receiving module. Detailed implementation manners

[0057] Unless otherwise defined, all technical terms used in the embodiments of the present disclosure have the same meaning as commonly understood by those of ordinary skill in the art. Some technical terms involved in the embodiments of the present disclosure are described below.

[0058] Terahertz (THz) waves are electromagnetic waves with frequencies between infrared light and microwaves, with a frequency range of 0.1 THz to 10 THz and a wavelength range of 0.03 mm to 3 mm.

[0059] The dielectric constant, also known as the permittivity, is a coefficient representing the insulating ability characteristic, denoted by the letter ε, with the unit of farad per meter (F / m). The dielectric constant is the ratio of the electric displacement D to the electric field strength E, ε = D / E, where the unit of the electric displacement D is coulomb per square meter (C / m 2 ). In practical applications, the dielectric constant usually appears as the relative permittivity, denoted by the letter εr, which is a dimensionless pure number and its value is equal to the ratio of the capacitance of a capacitor made of the target material as the medium to that of a capacitor of the same size made of vacuum as the medium.

[0060] Dielectric loss, also known as medium loss, refers to the energy loss caused inside an insulating material under the action of an electric field due to the hysteresis effects of medium conductance and medium polarization. For the dielectric loss of a dielectric material, it can be judged by the loss factor (Dissipation Factor), also known as the loss tangent.

[0061] Dispersion (Dispersion, Dis) can be understood as that since the terahertz waves transmitted by the waveguide include different frequencies and different modes, and the propagation speeds of terahertz waves with different frequencies or different modes in waveguide transmission may be different, signal distortion will inevitably occur after reaching a certain distance, such as the broadening of terahertz wave pulses, resulting in signal distortion.

[0062] The dispersion Dis of the waveguide can be calculated by the group delay corresponding to the working frequency band of the terahertz wave used. The group delay refers to the time delay when different frequency signals are transmitted. The unit of the time delay for a single frequency point transmission is ps, and the unit of the time delay per unit length for a single frequency point corresponds to ps / m.

[0063] The dispersion calculation formula is: Dis = (Delay2 - Delay1) / (f max -f min), where Dis represents the dispersion of the waveguide, with the unit of ps / GHz / m; Delay2 represents the maximum time delay per unit length within the working frequency band, Delay1 represents the minimum time delay per unit length within the working frequency band, f max represents the maximum frequency in the frequency band, f min represents the minimum frequency in the frequency band.

[0064] There are a large number of short-distance and high-speed interconnection scenarios in data center networks, and the bandwidth requirement has gradually increased to 100 Gbps. Terahertz radio frequency interconnection has advantages such as large bandwidth and low cost. The terahertz dielectric waveguide (or terahertz fiber) used to transmit terahertz waves, as the transmission medium, determines indicators such as the transmission distance and transmission density of terahertz waves. It is expected that the terahertz fiber has both high density and low dielectric loss.

[0065] Related technologies use polymers with low-loss characteristics to prepare terahertz fibers. Some polymers with low-loss characteristics include: Polypropylene (PP), Polyethylene (PE), Copolymers of Cycloolefin (COC), etc.

[0066] However, the known low-loss polymers currently have a low dielectric constant. In order to confine terahertz waves within the terahertz fiber, it is usually necessary to design a relatively large waveguide diameter, which increases the volume of the terahertz waveguide and is not conducive to its application in high-density scenarios.

[0067] One of the reasons for the relatively thick fiber diameter of the terahertz fiber made of pure polymer material is that the dielectric constant of the polymer material itself is relatively low. Although the dielectric constant of the terahertz fiber can be increased by adding high-dielectric particle materials to the polymer, thereby reducing the fiber diameter. However, this will lead to the problem of relatively high transmission loss. The reason is that, on the one hand, when the granular high-dielectric material is distributed in the polymer, more particle-polymer interfaces will be formed, and too many interfaces will increase the signal reflection, thereby increasing the transmission loss. On the other hand, the dielectric loss of the waveguide is proportional to the dielectric constant. Therefore, while increasing the dielectric constant, the transmission loss of the terahertz waveguide will be further deteriorated.

[0068] In view of the technical problems existing in the related technologies, the embodiments of the present disclosure provide a waveguide 100 (the waveguide is also called a dielectric waveguide), as shown in the appendix Figure 1As shown, the waveguide 100 includes: a first dielectric member 1 and a second dielectric member 2, and the second dielectric member 2 is distributed within the first dielectric member 1. The material of the first dielectric member 1 includes a polymer. The second dielectric member 2 includes a plurality of single crystal structures, and the crystal axis with the lowest dielectric loss in the single crystal structure points to the axial direction of the waveguide 100. The first dielectric member 1 has a first dielectric constant, and the second dielectric member 2 has a second dielectric constant, and the second dielectric constant is greater than the first dielectric constant.

[0069] It should be noted that a single crystal structure usually includes a plurality of crystal axes (which can also be understood as crystal orientations). It is desired that the crystal axis with the lowest dielectric loss among the plurality of crystal axes points to the axial direction of the waveguide 100. That is to say, the angle between the crystal axis with the lowest dielectric loss and the axis of the waveguide 100 is smaller than that of other crystal axes. In the embodiments of the present disclosure, the crystal axis with the lowest dielectric loss in the single crystal structure "points to" the axial direction of the waveguide 100, which means that the direction trend of the crystal axis with the lowest dielectric loss in the single crystal structure is along the axial direction of the waveguide 100. This includes but is not limited to the following: First, the crystal axis orientation with the lowest dielectric loss in the single crystal structure is the same as the axial direction of the waveguide 100, that is, the angle between the straight line where the crystal axis with the lowest dielectric loss in the single crystal structure is located and the straight line where the axial direction of the waveguide 100 is located is 0°; Second, there is an allowable angle between the crystal axis orientation with the lowest dielectric loss in the single crystal structure and the axial direction of the waveguide 100. For example, the angle is greater than 0° and less than or equal to 30°, further less than or equal to 20°, and further less than or equal to 10°, etc. Among them, the axial direction of the waveguide 100 is the same as the axial direction of the structure where the first dielectric member 1 made of polymer is located.

[0070] For the waveguide 100 provided by the embodiments of the present disclosure, the first dielectric member 1 is formed of a polymer having the characteristic of low dielectric loss, and the second dielectric member 2 is distributed in the first dielectric member 1. On the one hand, the first dielectric member 1 has a first dielectric constant, and the second dielectric member 2 has a second dielectric constant, and the second dielectric constant is greater than the first dielectric constant. This can increase the equivalent dielectric constant of the waveguide 100, thereby facilitating the reduction of the waveguide diameter. On the other hand, the second dielectric member 2 includes a plurality of single crystal structures, and the crystal axis with the lowest dielectric loss in the single crystal structure points to the axial direction of the waveguide 100. This is conducive to reducing the dielectric loss of the waveguide 100, so that the waveguide 100 provided by the embodiments of the present disclosure has the advantages of both a smaller waveguide diameter and a lower dielectric loss.

[0071] For the second dielectric member 2 including multiple single-crystal structures, the dielectric loss of the second dielectric member 2 can be made less than that of the first dielectric member 1. In particular, the crystal axis with the lowest dielectric loss in the single-crystal structure of the second dielectric member 2 is directed towards the axial direction of the waveguide 100, thereby ensuring that the dielectric loss of the second dielectric member 2 in the waveguide 100 is lower than that of the first dielectric member 1. Of course, the dielectric loss of the first dielectric member 1 can also be a relatively low value, and it is desirable that the dielectric loss of the first dielectric member 1 is as low as possible.

[0072] For example, the dielectric loss factor of the first dielectric member 1 can be less than or equal to 3×10 -4 , and the dielectric loss factor of the second dielectric member 2 can be less than or equal to 1×10 -4 . Of course, the dielectric loss factor of the first dielectric member 1 can be less than or equal to 5×10 -5 , and such a low dielectric loss can be achieved, for example, by using the polymer foaming technology.

[0073] As described above, a single-crystal structure usually includes multiple crystal axes, that is, crystal orientations, and there are differences in dielectric losses corresponding to different crystal axes. By directing the crystal axis with the lowest dielectric loss among the multiple crystal axes of the single-crystal structure of the second dielectric member 2 towards the axial direction of the waveguide 100, the low-loss transmission of signals, such as terahertz waves, in the waveguide 100 is optimized.

[0074] Although it is desirable that the dielectric constant of the second dielectric member 2 is greater than that of the first dielectric member 1, however, it is found that when the ratio of the dielectric constant of the second dielectric member 2 to the dielectric constant of the first dielectric member 1 is greater than 5, the difference in dielectric constants between the second dielectric member 2 and the polymer of the first dielectric member 1 is relatively large, and thus the interface reflection between the two is relatively strong, resulting in a resonance phenomenon in the signal propagation of the waveguide 100. To address this technical problem, in the embodiments of the present disclosure, the ratio of the dielectric constant of the second dielectric member 2 to the dielectric constant of the first dielectric member 1 is less than or equal to 5, and further, it can be less than or equal to 4.5, 4, etc.

[0075] Appendix Figure 2 Fig. is a graph showing the variation of the loss with frequency of waveguide one in the frequency band from 110 GHz to 170 GHz obtained by simulating waveguide one using the three-dimensional electromagnetic field simulation software CST. Among them, this waveguide one includes a first dielectric member 1 made of a polymer material and a second dielectric member 2 uniformly distributed therein, and the ratio of the dielectric constant of the second dielectric member 2 to the dielectric constant of the first dielectric member 1 is 10. It can be Figure 2 seen that a resonance phenomenon occurs in the signal propagation of waveguide one. Appendix Figure 3The figure respectively shows the curve of the loss varying with frequency of waveguide two within the frequency band of 110 GHz to 170 GHz obtained by simulating waveguide two using the three-dimensional electromagnetic field simulation software CST. The only difference between waveguide two and waveguide one is that the ratio of the dielectric constant of the second dielectric member 2 to the dielectric constant of the first dielectric member 1 is 5. From Figure 3 it can be seen that the loss fluctuation of waveguide two within the frequency band of 110 GHz to 170 GHz is less than 1 dB, achieving low resonance.

[0076] In some implementation manners, the single-crystal structure body is a single-crystal fiber. That is to say, the second dielectric member includes a plurality of single-crystal fibers, and the crystal axis in the length direction of the single-crystal fiber is the crystal axis with the lowest dielectric loss.

[0077] It should be noted that the single-crystal fiber is a kind of single crystal. When the single-crystal fiber grows, it grows along the crystal axis with the lowest dielectric loss, so that the crystal axis in the length direction of the grown single-crystal fiber is the crystal axis with the lowest dielectric loss.

[0078] For the waveguide 100 provided by the embodiments of the present disclosure, by making the second dielectric member 2 include single-crystal fibers, on the one hand, the dielectric constant of the single-crystal fiber is greater than that of the first dielectric member 1, which is beneficial to improving the dielectric constant of the waveguide 100, thereby facilitating the reduction of the waveguide diameter. On the other hand, by using the low dielectric loss characteristic of the single-crystal fiber in the length direction, the length direction of the single-crystal fiber is directed to the axial direction of the waveguide 100, thereby reducing the dielectric loss of the waveguide 100. At the same time, the single-crystal fiber exists in the form of fibers, and the number of fiber-polymer interfaces is significantly reduced compared with the number of particle-polymer interfaces, which is also beneficial to reducing the overall dielectric loss of the waveguide 100. It can be seen that the waveguide 100 provided by the embodiments of the present disclosure further optimizes the advantages of a smaller waveguide diameter and a lower dielectric loss.

[0079] For the single-crystal fiber material, its loss is extremely low at a certain orientation, and its loss factor Df reaches 5×10 -5 to the order of magnitude. In summary, it can be seen that the embodiments of the present disclosure utilize the fact that the single-crystal fiber itself has a certain length and orientation. On the one hand, it is easy to achieve the low-loss orientation of the single-crystal fiber in the first dielectric member 1 made of polymer material, and at the same time, the number of interfaces is greatly reduced, so that the waveguide 100 meets the requirements of high dielectric and low loss.

[0080] In some examples, the relative dielectric constant of the single-crystal fiber is 5 to 15, and further can be 8 to 12, making the single-crystal fiber a high-dielectric material, which is beneficial to improving the dielectric performance of the waveguide 100, realizing a stronger terahertz wave confinement ability, and thus facilitating the reduction of the waveguide diameter.

[0081] Single crystal materials usually include multiple crystal orientations, and there are differences in dielectric losses corresponding to different crystal orientations. Taking aluminum oxide single crystal fibers as an example, the dielectric loss in the c-axis orientation is the lowest relative to its a-axis and b-axis. Therefore, when the single crystal fiber includes multiple crystal orientations, the crystal orientation with the lowest dielectric loss among the multiple crystal orientations is the same as the length direction of the single crystal fiber.

[0082] It can be seen that by making the length direction of the single crystal fiber the same as the crystal orientation with the lowest dielectric loss, and when the length direction of the single crystal fiber points to the axial direction of the waveguide 100, low-loss transmission of terahertz waves by the waveguide 100 can be achieved.

[0083] Continuing to take aluminum oxide single crystal fibers as an example, the dielectric loss in the c-axis orientation is the lowest relative to its a-axis and b-axis, and the loss factor corresponding to the c-axis can reach 2×10 -5 level. Therefore, when the length direction of the aluminum oxide single crystal fiber is the c-axis orientation, low-loss transmission of terahertz waves can be achieved.

[0084] When multiple single crystal fibers are provided, and the multiple single crystal fibers are spaced apart and distributed in the first dielectric member 1, the length direction of the single crystal fiber extends along the axial direction of the waveguide 100, which includes: the length direction of the single crystal fiber is the same as or substantially the same as the axial direction of the waveguide 100. For example, the angle between the straight line where the length direction of the single crystal fiber is located and the straight line where the axial direction of the waveguide 100 is located can be 0° to 20°, and further, the angle is made 0° to 10°.

[0085] In some examples, the length direction of the single crystal fiber is made the same as the axial direction of the waveguide 100, that is, the angle between the straight line where the length direction of the single crystal fiber is located and the straight line where the axial direction of the waveguide 100 is located is 0°, thereby further ensuring the low-loss characteristic of signals, such as terahertz waves, in the transmission direction.

[0086] In addition, the embodiments of the present disclosure expect that multiple single crystal fibers are evenly spaced apart and distributed inside the first dielectric member 1, thereby reducing the dielectric loss of signals, such as terahertz waves, in the transmission direction.

[0087] In some examples, the diameter of the single crystal fiber is made less than or equal to 100 μm, which includes but is not limited to: the diameter of the single crystal fiber is less than or equal to 95 μm, 90 μm, 85 μm, 80 μm, 75 μm, 70 μm, 65 μm, 60 μm, 55 μm, 50 μm, etc. By making the diameter of the single crystal fiber within the above range, the flexibility of the single crystal fiber is improved, which is beneficial to improving the flexibility of the waveguide 100, making its bending performance more excellent, thereby realizing a certain degree of curved waveguide characteristic, and further connecting the interfaces of terahertz waves at different positions according to requirements.

[0088] Further, a plurality of single-crystal fibers are provided, and the volume percentage of the plurality of single-crystal fibers in the waveguide 100 is less than or equal to 30%, including but not limited to: 25%, 20%, 15%, 10%, etc. When the volume percentage content of the single-crystal fibers is within the above range, not only can the waveguide 100 achieve electromagnetic wave transmission in the terahertz band, for example, in the frequency band of 110 GHz to 170 GHz, but also the waveguide 100 can be ensured to have the desired flexibility.

[0089] In some implementation manners, as shown in the appended Figure 4 figure, the single-crystal fiber is in the form of a long fiber, and both ends of the single-crystal fiber extend to the corresponding two ends of the first dielectric member 1 respectively. That is to say, the single-crystal fiber is a whole long fiber, one end of which extends to the same-side end of the first dielectric member 1, and the other end of which extends to the other same-side end of the first dielectric member 1.

[0090] The single-crystal fiber in the form of a long fiber is beneficial to reducing the number of single-crystal fibers used, thereby reducing the number of fiber-polymer interfaces, and thus is beneficial to reducing the dielectric loss of the waveguide 100. Moreover, when the single-crystal fiber in the form of a long fiber is used to prepare the waveguide 100, it is easier to control its position in the first dielectric member 1, and it is beneficial to improving the position accuracy of the single-crystal fiber.

[0091] In other implementation manners, as shown in the appended Figure 5 figure, the single-crystal fiber is in the form of a whisker, and the aspect ratio of the single-crystal fiber in the form of a whisker is greater than or equal to 5. The "aspect ratio" involved here refers to the ratio of the length of the fiber to its diameter. The aspect ratio of the single-crystal fiber in the form of a whisker is greater than or equal to 5. For example, its aspect ratio can be 5:1 to 20:1, including but not limited to 8:1, 9:1, 10:1, 11:1, 12:1, etc.

[0092] The single-crystal fiber in the form of a whisker is a short fiber, which is beneficial to reducing costs. Moreover, by defining the aspect ratio of the single-crystal fiber in the form of a whisker as above, it is convenient to orient the single-crystal fiber when preparing the waveguide 100 to ensure that the length direction of the single-crystal fiber points to the axial direction of the waveguide 100.

[0093] In some implementation manners, for the waveguide 100 provided by the embodiments of the present disclosure, a plurality of single-crystal fibers are provided, and along the direction from the axis of the first dielectric member 1 to the outer wall of the first dielectric member 1 (i.e., the radially outward direction), the distribution density of the single-crystal fibers shows a decreasing trend. Herein, the "distribution density" involved refers to the volume percentage occupied by the single-crystal fibers.

[0094] By defining the distribution state of multiple single-crystal fibers as described above, the higher the distribution density of the single-crystal fibers in the inner region of the first dielectric member 1, the more conducive it is to confining terahertz waves and reducing the transmission loss of terahertz waves. While the distribution density of the single-crystal fibers in the outer region of the first dielectric member 1 is relatively low, making its equivalent dielectric constant also correspondingly reduced. Thus, by utilizing the non-uniform distribution of the dielectric constant in different regions of the waveguide 100, the dispersion of the waveguide 100 during signal transmission is reduced.

[0095] The distribution density of the single-crystal fibers in the first dielectric member 1 shows a decreasing trend, which includes but is not limited to: the distribution density of the single-crystal fibers gradually decreases along the radially outward direction, and the distribution density of the single-crystal fibers decreases in a stepped manner along the radially outward direction.

[0096] For the stepped decrease, for example, along the radially outward direction of the first dielectric member 1, the distribution density of the single-crystal fibers can be at least two segments, which includes but is not limited to two segments, three segments, four segments, etc.

[0097] Taking the distribution density of the single-crystal fibers designed as two segments as an example, as shown in the appendix Figure 6 It shows that the waveguide 100 is divided into a first region 101 and a second region 102, and the second region 102 is arranged surrounding the outside of the first region 101. Among them, the distribution density of the single-crystal fibers in the first region 101 is greater than the distribution density of the single-crystal fibers in the second region 102.

[0098] Exemplarily, the first region 101 is a circular region, where the distribution density of the single-crystal fibers is 25% - 30%, which includes but is not limited to: 25%, 26%, 27%, 28%, 29%, 30%, etc. The second region 102 is an annular region, where the distribution density of the single-crystal fibers is 10% - 20%, which includes but is not limited to: 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, etc.

[0099] Since the dielectric constant of the single-crystal fibers is significantly higher than the dielectric constant of the polymer, considering the overall equivalent dielectric constant of the first region 101 and the second region 102, the equivalent dielectric constant of the first region 101 is higher than the equivalent dielectric constant of the second region 102, thus achieving a reduction in transmission dispersion.

[0100] In some examples, along the radial direction of the first dielectric member 1, the single-crystal fibers are arranged in multiple layers, and the arrangement structure of each layer of single-crystal fibers includes but is not limited to: circular, rectangular, elliptical, rhombic, etc.

[0101] In the embodiments of the present disclosure, some polymers with low dielectric loss in the terahertz band include, but are not limited to, at least one of the following polymers: polyethylene (PE), polypropylene (PP), copolymers of cycloolefin (COC), high density polyethylene (HDPE), low density polyethylene (LDPE), polytetrafluoroethylene (PTFE), poly(4-methyl-1-pentene-1) (TPX), polyurethane (PU), polystyrene (PS), polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC).

[0102] For example, the polymer used to form the first dielectric member 1 in the embodiments of the present disclosure can be at least one of polyethylene (PE), polypropylene (PP), and copolymers of cycloolefin (COC).

[0103] In the embodiments of the present disclosure, some single crystal materials with high dielectric constant and low dielectric loss for preparing the second dielectric member 2 include at least one of aluminum oxide, silicon carbide, single crystal silicon, titanium dioxide, magnesium oxide, quartz single crystal, and graphene.

[0104] The existence form of the above-mentioned single crystal materials can be single crystal fibers, single crystal nanowires, or single crystal particles, which can be selected according to the actual application scenario.

[0105] For example, for the second dielectric member 2 in the form of single crystal fibers, the single crystal fibers used include, but are not limited to, at least one of the following fibers: aluminum oxide single crystal fibers, silicon carbide single crystal fibers, single crystal silicon fibers, titanium dioxide single crystal fibers, and magnesium oxide single crystal fibers. For example, aluminum oxide single crystal fibers can be used to form the second dielectric member 2.

[0106] For the second dielectric member 2 in the form of single crystal particles, the single crystal particles used include, but are not limited to, at least one of aluminum oxide single crystal particles, silicon carbide single crystal particles, single crystal silicon particles, titanium dioxide single crystal particles, and magnesium oxide single crystal particles.

[0107] For the second dielectric member 2 in the form of a single-crystal nanowire, for example, it can be a single-crystal quartz nanowire.

[0108] By adjusting the volume percentage content, arrangement mode, etc. of the single-crystal fibers, the terahertz wave transmission characteristics of the waveguide 100 for different wavelengths can be achieved.

[0109] In summary, based on using single-crystal fibers with a high dielectric constant and low dielectric loss as the second dielectric member 2 and controlling the distribution density of the single-crystal fibers, the characteristics of small diameter, low loss, and low dispersion of the waveguide 100 can be achieved.

[0110] In some other implementation manners, the single-crystal structure body is a single-crystal particle, the second dielectric member 2 includes a plurality of single-crystal particles, and the crystal axis with the lowest dielectric loss in the single-crystal particle points to the axial direction of the waveguide 100.

[0111] Exemplarily, the particle size of the single-crystal particle can be 1 μm to 20 μm, further can be 5 μm to 15 μm, and further can be 10 μm, etc.

[0112] Selecting a single-crystal structure body in the form of a single-crystal particle can also achieve the purpose of reducing the diameter of the waveguide 100 and simultaneously reducing the dielectric loss of the waveguide 100.

[0113] In some examples, the waveguide provided by the embodiments of the present disclosure is a terahertz optical fiber, which can be used to transmit terahertz waves in the frequency band of 0.10 THz to 10 THz, and further, to transmit terahertz waves in the frequency band of 0.11 THz to 0.17 THz. The terahertz optical fiber involved in the embodiments of the present disclosure herein has all the advantages of any one of the waveguides mentioned above.

[0114] In some examples, the waveguide provided by the embodiments of the present disclosure can also be a visible light band optical fiber. For example, the single-crystal materials used for the second dielectric member 2 of the visible light band optical fiber can be quartz, graphene, silicon, etc.

[0115] It should be noted that the waveguide provided by the embodiments of the present disclosure can be a solid waveguide or a hollow waveguide. For a solid waveguide, it means that the first dielectric member is solid, as indicated in the drawings provided by the embodiments of the present disclosure. For a hollow waveguide, it means that there is one or more air ducts inside the first dielectric member. Due to the low refractive index of air, the signal will be reflected in the ducts, so as to achieve the purpose of transmitting the signal.

[0116] In some examples, the waveguide provided by the embodiments of the present disclosure may further include a cladding layer, which is coated on the outer surface of the first dielectric member. The refractive index of the cladding layer may be lower than that of the first dielectric member to provide a reflective surface or optical isolation, and also play a certain mechanical protection role.

[0117] In some examples, the waveguide provided by the embodiments of the present disclosure may further include an outer coating layer, which is coated on the outer surface of the cladding layer to provide external protection.

[0118] On the other hand, the embodiments of the present disclosure also provide a method for manufacturing a waveguide, wherein the waveguide is as described in any of the above. The method for manufacturing the waveguide includes:

[0119] Combining a first dielectric member and a second dielectric member to obtain a dielectric composite structure.

[0120] Performing waveguide forming treatment on the dielectric composite structure to prepare a waveguide.

[0121] When the single crystal structure body in the second dielectric member is a single crystal fiber, and the single crystal fibers are in the form of long fibers and whiskers respectively, the corresponding manufacturing methods are different. The manufacturing methods of the waveguides corresponding to these two fiber forms are described below respectively.

[0122] For the single crystal fiber in the form of long fibers, combining a first dielectric member and a second dielectric member to obtain a dielectric composite structure includes: using a spinning process or an extrusion process to composite a polymer layer on the surface of the single crystal fiber in the form of long fibers, thereby preparing a dielectric composite structure.

[0123] For the case of only containing a single single crystal fiber, the dielectric composite structure is the waveguide.

[0124] For the case of containing multiple single crystal fibers, further, performing waveguide forming treatment on the dielectric composite structure includes: arranging a plurality of dielectric composite structures in a set arrangement manner, and then performing heat treatment or sleeve binding treatment to fix the relative positions of the plurality of dielectric composite structures, thereby preparing a waveguide.

[0125] For the preparation scheme of the single crystal fiber in the form of long fibers as the second dielectric member, the dielectric composite structure is a core-shell structure, and it is also a waveguide in the form of a single fiber. The single crystal fiber in the form of long fibers is used as the core, and the polymer layer is coated on the surface of the single crystal fiber as the shell layer, so that the dielectric composite structure presents a form with a relatively small diameter and a relatively long length.

[0126] By arranging a plurality of dielectric composite structures in a set arrangement manner, the control of the position distribution of the single crystal fiber in the form of long fibers inside the first dielectric member is realized.

[0127] After the relative positions of multiple dielectric composite structures are arranged, the relative positions of the multiple dielectric composite structures are fixed by heat treatment or sleeve binding treatment. For example, when heat treatment is performed, the polymer layers of the multiple dielectric composite structures are bonded together to complete the preparation of the waveguide. When sleeve binding treatment is performed, since the single crystal fibers are still distributed inside the corresponding polymer materials, the second dielectric component is also correspondingly distributed inside the first dielectric component.

[0128] Of course, it is not excluded that even if the multiple dielectric composite structures are loosely fixed together, since the single crystal fibers are still distributed inside the corresponding polymer materials, the second dielectric component is also correspondingly distributed inside the first dielectric component.

[0129] In addition, the volume percentage of single crystal fibers in the multiple dielectric composite structures can be determined respectively according to the volume percentage of single crystal fibers in the prepared waveguide.

[0130] For single crystal fibers in the form of whiskers, the first dielectric component and the second dielectric component are combined to obtain a dielectric composite structure, including: mixing the single crystal fibers in the form of whiskers and polymer particles according to a set ratio to obtain a dielectric composite material. The dielectric composite material is subjected to fiber forming treatment by a spinning process, an extrusion process or a 3D printing process to prepare a dielectric composite structure.

[0131] When performing spinning treatment or extrusion treatment, the orientation of the single crystal fibers in the form of whiskers in the first dielectric component is controlled by using the force field directionality at the extrusion die head of a spinning machine or an extruder to ensure that the length direction of the single crystal fibers extends along the length direction of the first dielectric component.

[0132] For the technical solution in which the single crystal fibers in the form of whiskers are uniformly distributed in the first dielectric component, the dielectric composite material is in the form of a mixture. For example, the single crystal fibers and polymer particles are uniformly mixed according to a set ratio to form a dielectric composite material. Subsequently, by performing a spinning process, an extrusion process or a 3D printing process on the dielectric composite material, a dielectric composite structure in the form of long fibers can be formed.

[0133] Further, waveguide forming treatment is performed on the dielectric composite structure, including: arranging the multiple dielectric composite structures in a set arrangement, and then performing heat treatment or sleeve binding treatment to fix the relative positions of the multiple dielectric composite structures, thereby preparing a waveguide. The implementation method can refer to the relevant operations in the above-mentioned single crystal fiber scheme in the form of long fibers.

[0134] For the technical solution in which single crystal fibers in the form of whiskers are distributed in the first dielectric member with different distribution densities, for each distribution density, by controlling the volume percentage of the second dielectric member in the dielectric composite structure at different positions and arranging the dielectric composite structure according to the set arrangement positions, the regulation of different distribution densities of the single crystal fibers in different regions can be achieved.

[0135] The embodiments of the present disclosure also provide an application of any of the above-mentioned waveguides in electromagnetic wave transmission. For example, it relates to point-to-point high-speed interconnection.

[0136] On the other hand, the embodiments of the present disclosure also provide an optical cable, which includes any of the above-mentioned waveguides. The optical cable provided by the embodiments of the present disclosure has all the advantages of the waveguides involved above.

[0137] The embodiments of the present disclosure also provide a communication device, which includes any of the above-mentioned waveguides or the above-mentioned optical cable. The communication device provided by the embodiments of the present disclosure has all the advantages of the waveguides involved above.

[0138] Figure 7 An application scenario of the waveguide provided by the embodiments of the present disclosure is exemplified. It is a communication device, which includes: waveguide 100, a terahertz wave transmitting module 200, and a terahertz wave receiving module 300. The two ends of the waveguide 100 along its length direction are respectively connected to the transmitting module 200 and the terahertz wave receiving module 300.

[0139] During application, the terahertz wave transmitting module 200 at the transmitting end transforms the input signal S to the THz frequency band, and then couples it to the waveguide 100 for transmission to the terahertz wave receiving module 300 at the receiving end. The terahertz wave receiving module 300 restores the received terahertz wave signal to the signal S and transmits it to the downstream. Among them, the signal S involved here can be a digital signal or an analog signal.

[0140] The exemplary embodiments of the present disclosure will be described in more detail below. Although the exemplary embodiments of the present disclosure are described below, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. For those where specific techniques or conditions are not indicated in the examples, they shall be carried out according to the techniques or conditions described in the literature in the art or according to the product specifications. For those reagents or instruments whose manufacturers are not indicated, they are all conventional products that can be obtained through commercial purchase.

[0141] Example 1

[0142] The present Example 1 provides a waveguide in the form of a terahertz fiber, which includes a first dielectric member and a second dielectric member distributed in the first dielectric member, and the volume percentage of the second dielectric member is 15.25%.

[0143] The first dielectric member is cylindrical with a diameter of 2 mm. The material of the first dielectric member is polyethylene, with a relative dielectric constant Dk of 2.3 and a dielectric loss factor Df of 0.0002.

[0144] The second dielectric member includes a plurality of single-crystal alumina fibers in the form of long fibers. The crystal axis direction (i.e., the length direction) of the single-crystal alumina fiber points to the crystal axis direction (C-axis direction) with the lowest loss. In this crystal axis direction, its relative dielectric constant Dk is 10 and the dielectric loss factor Df is 0.00002. The two ends of the single-crystal alumina fiber along its length direction extend to the two ends of the first dielectric member along its length direction respectively. The diameter of the second dielectric member in the form of single-crystal alumina fibers is 100 μm, and the second dielectric members are evenly spaced in the first dielectric member, and the distance between any two adjacent single-crystal alumina fibers is 150 μm.

[0145] The three-dimensional electromagnetic field simulation software CST was used to simulate and calculate the loss value of the terahertz optical fiber provided in Example 1. Figure 8 The curve graph showing the variation of the loss of the terahertz optical fiber with frequency in the frequency band of 120 GHz to 150 GHz obtained by CST simulation is shown. As attached Figure 8 As shown, the loss of the terahertz optical fiber provided in Example 1 in the frequency band of 120 GHz to 150 GHz is less than 2.5 dB / m, and the diameter is only 2 mm, making this terahertz optical fiber have the advantages of low loss and small diameter.

[0146] The three-dimensional electromagnetic field simulation software CST was used to simulate the mode field diagram of the terahertz optical fiber provided in Example 1 at a frequency of 140 GHz. As attached Figure 9 As shown, when the terahertz optical fiber transmits terahertz waves with a transmission frequency of 140 GHz, the electromagnetic field energy of the waveguide (i.e., Figure 9 the light gray area part in) is confined inside the first dielectric member, which proves that the terahertz optical fiber provided in Example 1 realizes a strong confinement ability for terahertz waves at a small diameter.

[0147] Example 2

[0148] This Example 2 provides a waveguide in the form of a terahertz optical fiber, which includes a first dielectric member and a second dielectric member distributed in the first dielectric member. The first dielectric member is cylindrical with a diameter of 2 mm. The material of the first dielectric member is polyethylene, with a relative dielectric constant Dk of 2.3 and a dielectric loss factor Df of 0.0002.

[0149] The second dielectric member includes single-crystal alumina fibers in the form of multiple long fibers with a diameter of 100 μm. The two ends of the single-crystal alumina fibers extend to the two ends of the first dielectric member along its length direction respectively. The crystal axis direction of the single-crystal alumina fibers in the axial direction (i.e., the length direction) is the crystal axis direction with the lowest dielectric loss (i.e., the C-axis direction). In this crystal axis direction, its relative dielectric constant Dk is 10, and the dielectric loss factor Df is 0.00002.

[0150] The volume percentage of the single-crystal alumina fibers in the first dielectric member is distributed in a stepped manner. Specifically, the terahertz optical fiber is divided into a first region and a second region. The second region is arranged around the outside of the first region. The first region is circular with a diameter of 1.2 mm, and the volume ratio of the single-crystal alumina fibers in the first region is 28%. The second region is annular with a thickness of 0.4 mm, and the volume ratio of the single-crystal alumina fibers in the second region is 16%.

[0151] The three-dimensional electromagnetic field simulation software CST is used to simulate and calculate the loss value of the terahertz optical fiber provided in Example 2. Figure 10 The curve graph showing the variation of the loss of the terahertz optical fiber with frequency in the frequency band from 120 GHz to 150 GHz obtained by CST simulation is shown. As attached Figure 10 As shown, the loss of the terahertz optical fiber in the frequency band from 120 GHz to 150 GHz is less than 2.5 dB / m, and the diameter is 2 mm, achieving low loss, making the terahertz optical fiber have the advantages of low loss and small diameter.

[0152] The three-dimensional electromagnetic field simulation software CST is used to simulate the mode field diagram of the terahertz optical fiber provided in Example 2 at a frequency of 140 GHz. The simulation results show that when the terahertz optical fiber transmits terahertz waves with a transmission frequency of 140 GHz, the electromagnetic field energy of the waveguide is confined inside the first dielectric member, achieving a strong confinement ability of the terahertz optical fiber for terahertz waves at a small diameter.

[0153] The three-dimensional electromagnetic field simulation software CST is used to simulate and calculate the group delay of the terahertz optical fiber provided in Example 2. Figure 11 The curve graph showing the variation of the group delay of the terahertz optical fiber with frequency in the frequency band from 110 GHz to 170 GHz obtained by CST simulation is shown. As attached Figure 11 As shown, when the terahertz optical fiber transmits terahertz waves with a frequency of 142 GHz, its delay is the smallest, and when it transmits terahertz waves with a frequency of 110 GHz, its delay is the largest. Based on the dispersion formula, the dispersion of the terahertz optical fiber provided in Example 2 can be calculated to be less than 0.3 ps / GHz / m, making the terahertz optical fiber have the advantages of low loss, small diameter, and low dispersion.

[0154] Example 3

[0155] Embodiment 3 provides a waveguide in the form of a terahertz fiber, which includes a first dielectric member and a second dielectric member distributed within the first dielectric member. The volume percentage of the second dielectric member is 20%.

[0156] The first dielectric member is cylindrical with a diameter of 2 mm, and the material of the first dielectric member is polyethylene (its relative dielectric constant Dk is 2.3, and the dielectric loss factor Df is 0.0002).

[0157] The second dielectric member includes a plurality of single-crystal alumina fibers in the form of whiskers. The aspect ratio of the single-crystal alumina fibers in the form of whiskers is 10:1, the diameter is 1 μm, and the length is 10 μm. The crystal axis direction of the single-crystal alumina fiber in the axial direction (i.e., the length direction) is the crystal axis direction with the lowest dielectric loss (i.e., the C-axis direction). In this crystal axis direction, its relative dielectric constant Dk is 10, and the dielectric loss factor Df is 0.00002.

[0158] The single-crystal alumina fibers in the form of whiskers are uniformly or approximately uniformly distributed in the first dielectric member. Since the fiber length direction points to the axial direction of the waveguide, based on the low dielectric loss characteristic of the single-crystal fiber in its length direction, it is ensured that the waveguide provided in Embodiment 3 has a low loss in the electromagnetic wave propagation direction and can also have the advantages of low loss and small diameter.

[0159] Embodiment 4

[0160] Embodiment 4 provides a waveguide in the form of a terahertz fiber, which includes a first dielectric member and a second dielectric member distributed within the first dielectric member.

[0161] The first dielectric member is cylindrical with a diameter of 2 mm, and the material of the first dielectric member is polyethylene (its relative dielectric constant Dk is 2.3, and the dielectric loss factor Df is 0.0002).

[0162] The second dielectric member includes a plurality of single-crystal alumina fibers in the form of whiskers. The aspect ratio of the single-crystal alumina fibers in the form of whiskers is 10:1, the diameter is 1 μm, and the length is 10 μm. The crystal axis direction of the single-crystal alumina fiber in the axial direction (i.e., the length direction) is the crystal axis direction with the lowest dielectric loss (i.e., the C-axis direction). In this crystal axis direction, its relative dielectric constant Dk is 10, and the dielectric loss factor Df is 0.00002.

[0163] The volume percentage of single-crystal alumina fibers in the form of whiskers in the first dielectric member is distributed in a stepped manner. Specifically, the terahertz optical fiber is divided into a first region and a second region. The second region is arranged around the outside of the first region. The first region is circular with a diameter of 1.2 mm. The volume fraction of single-crystal alumina fibers in the first region is 28% and the single-crystal fibers are evenly distributed or approximately evenly distributed. The second region is annular with a thickness of 0.4 mm. The volume fraction of single-crystal alumina fibers in the second region is 16% and the single-crystal fibers are evenly distributed or approximately evenly distributed. Since the fiber length direction points to the axial direction of the waveguide, based on the low dielectric loss characteristic of the single-crystal fiber in its length direction, it is ensured that the waveguide provided in Example 4 has a low loss in the electromagnetic wave propagation direction and can also have the advantages of low loss and small diameter.

[0164] Example 5

[0165] This Example 5 provides a waveguide in the form of a terahertz fiber, which includes a first dielectric member and a second dielectric member distributed within the first dielectric member.

[0166] The first dielectric member is cylindrical with a diameter of 2 mm, and the material of the first dielectric member is polyethylene (its relative dielectric constant Dk is 2.3 and the dielectric loss factor Df is 0.0002).

[0167] The second dielectric member includes a plurality of single-crystal alumina particles with a grain diameter of about 20 μm (20 μm ± 10 μm). The single-crystal alumina particles have the lowest dielectric loss in the direction pointed by their crystal axis C, and in this crystal axis direction, its relative dielectric constant Dk is 10 and the dielectric loss factor Df is 0.00002.

[0168] The single-crystal alumina particles are evenly distributed or approximately evenly distributed in the first dielectric member, and the C axis with the lowest dielectric loss points to the axial direction of the waveguide, so as to ensure that the waveguide provided in Example 5 has a low loss in the electromagnetic wave propagation direction and can also have the advantages of low loss and small diameter.

[0169] Example 6

[0170] This Example 6 provides a waveguide in the form of a terahertz fiber, which includes a first dielectric member and a second dielectric member distributed within the first dielectric member.

[0171] The first dielectric member is cylindrical with a diameter of 2 mm, and the material of the first dielectric member is polyethylene (its relative dielectric constant Dk is 2.3 and the dielectric loss factor Df is 0.0002).

[0172] The second dielectric member includes a plurality of aluminum oxide single crystal particles with a grain diameter of about 20 μm (20 μm ± 10 μm). The aluminum oxide single crystal particles have the lowest dielectric loss in the direction pointed by the C-axis of their crystal axes. In this crystal axis direction, its relative dielectric constant Dk is 10, and the dielectric loss factor Df is 0.00002.

[0173] The volume percentage of the aluminum oxide single crystal particles in the first dielectric member in the first dielectric member is distributed in a stepped manner. Specifically, the terahertz optical fiber is divided into a first region and a second region. The second region is arranged surrounding the outside of the first region. The first region is circular with a diameter of 1.2 mm. The volume ratio of the aluminum oxide single crystal particles in the first region is 28%, and the single crystal particles are evenly distributed or approximately evenly distributed. The second region is annular with a thickness of 0.4 mm. The volume ratio of the aluminum oxide single crystal particles in the second region is 16%, and the single crystal particles are evenly distributed or approximately evenly distributed. The C-axis of the aluminum oxide single crystal particles with the lowest dielectric loss points to the axial direction of the waveguide to ensure that the waveguide provided in Example 6 has low loss in the electromagnetic wave propagation direction and can also have the advantages of low loss and small diameter.

[0174] In Examples 1 to 6, polyethylene is used as the dielectric of the first dielectric member and aluminum oxide single crystal material is used as the dielectric of the second dielectric member as examples to illustrate the structure of the waveguide in the form of a terahertz fiber. In the embodiments of the present disclosure, other low-loss materials can also be used as the dielectrics of the first dielectric member and the second dielectric member. For example, materials such as polypropylene, cyclic olefin copolymer, and polytetrafluoroethylene are used as the dielectric of the first dielectric member, and single crystal fibers such as high-resistance single crystal silicon, silicon carbide, titanium dioxide, and magnesium oxide are used as the dielectric of the second dielectric member, and the waveguide can also have the advantages of low loss and small diameter.

[0175] Example 7

[0176] Example 7 of the present disclosure provides a waveguide in the form of an optical fiber in the visible light band, which includes a first dielectric member and a second dielectric member distributed in the first dielectric member.

[0177] The first dielectric member is cylindrical with a diameter of 30 μm, and the material of the first dielectric member is polymethyl methacrylate, also known as acrylic or plexiglass, which has high transparency.

[0178] The second dielectric member includes a plurality of quartz single crystal nanowires (similar to whisker structures) with a diameter of about 20 nm (20 μm ± 10 μm) and a length of 100 μm (100 μm ± 10 μm). The quartz single crystal nanowires are most transparent in the direction pointed by the Z-axis of their crystal axes, that is, the loss of visible light propagating on the Z-axis is the lowest.

[0179] The quartz single crystal nanowires are evenly distributed or approximately evenly distributed in the first dielectric member, and their axial directions point to the axial direction of the waveguide, so as to ensure that the waveguide provided in Embodiment 7 has lower loss in the electromagnetic wave propagation direction and has the advantage of lower loss than a pure PMMA waveguide.

[0180] In Embodiment 7, the structural form with quartz single crystal nanowires as the second dielectric member. In other embodiments, it can also be a structural form with single crystal particles as the second dielectric member, and the particle size of the single crystal particles is 10 nm to 30 nm. No matter which structural form is adopted, the axial direction with lower loss should point to the axial direction of the waveguide to ensure that the waveguide has lower loss in the electromagnetic wave propagation direction, so that the advantage of lower loss than a pure PMMA waveguide can be achieved.

[0181] In Embodiment 7, the medium with polymethyl methacrylate as the first dielectric member and the medium with quartz single crystal nanowires as the second dielectric member are used as examples to illustrate the composition of the waveguide in the form of a visible light optical fiber. The embodiments of the present disclosure can also use other low-loss materials as the media of the first dielectric member and the second dielectric member. For example, materials such as polycarbonate and polystyrene are used as the media of the first dielectric member, and single crystal materials such as graphene and single crystal silicon are used as the media of the second dielectric member, and the waveguide in the form of a visible light optical fiber can also have the advantage of low loss.

[0182] The above is only for the convenience of those skilled in the art to understand the technical solutions of the present disclosure, and is not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A waveguide, characterized in that, The waveguide includes: a first dielectric member and a second dielectric member, and the second dielectric member is distributed within the first dielectric member; The material of the first dielectric member includes a polymer; The second dielectric member includes a plurality of single crystal structures, and the crystal axis with the lowest dielectric loss in the single crystal structure points to the axial direction of the waveguide; The first dielectric member has a first dielectric constant, the second dielectric member has a second dielectric constant, and the second dielectric constant is greater than the first dielectric constant.

2. The waveguide according to claim 1, characterized in that, The ratio of the dielectric constant of the second dielectric member to the dielectric constant of the first dielectric member is less than or equal to 5.

3. The waveguide according to any one of claims 1-2, characterized in that, The single crystal structure is a single crystal fiber, and the crystal axis in the length direction of the single crystal fiber is the crystal axis with the lowest dielectric loss.

4. The waveguide according to claim 3, characterized in that, The length direction of the single crystal fiber is the same as the axial direction of the waveguide.

5. The waveguide according to claim 3, characterized in that, The diameter of the single crystal fiber is less than or equal to 100 μm.

6. The waveguide according to claim 3, characterized in that, A plurality of the single crystal fibers are provided, and the volume percentage of the plurality of single crystal fibers in the waveguide is less than or equal to 30%.

7. The waveguide according to any one of claims 3-6, characterized in that, The single crystal fiber is in the form of a long fiber, and both ends of the single crystal fiber extend to the corresponding ends of the first dielectric member respectively.

8. The waveguide according to any one of claims 3-7, characterized in that, The single crystal fiber is in the form of a whisker, and the aspect ratio of the whisker-shaped single crystal fiber is greater than or equal to 5.

9. The waveguide according to any one of claims 3-8, characterized in that, A plurality of the single crystal fibers are provided, and along the direction from the axis of the first dielectric member to the outer wall of the first dielectric member, the distribution density of the single crystal fibers shows a decreasing trend.

10. The waveguide according to any one of claims 1-2, characterized in that, The single crystal structure is a single crystal particle, the second dielectric member includes a plurality of single crystal particles, and the crystal axis with the lowest dielectric loss in the single crystal particle points to the axial direction of the waveguide.

11. The waveguide according to any one of claims 1-10, characterized in that, The single crystal material used for the second dielectric member includes at least one of aluminum oxide, silicon carbide, single crystal silicon, titanium dioxide, magnesium oxide, quartz single crystal, and graphene.

12. The waveguide according to any one of claims 1-11, characterized in that, The polymer includes at least one of polyethylene, polypropylene, cycloolefin copolymer, high density polyethylene, low density polyethylene, polytetrafluoroethylene, 4-methylpentene polymer, polyurethane, polystyrene, polycarbonate, polymethyl methacrylate, and polyvinyl chloride.

13. A method for preparing a waveguide, characterized in that, The waveguide is as described in any one of claims 1-12; The method for preparing the waveguide includes: combining the first dielectric member and the second dielectric member to obtain a dielectric composite structure; Performing waveguide forming treatment on the dielectric composite structure to prepare the waveguide.

14. The method for preparing a waveguide according to claim 13, wherein, The second dielectric member is a single crystal fiber in the form of a long fiber, and the method for preparing the waveguide includes: Using a spinning process or an extrusion process to form a polymer layer on the surface of the single crystal fiber in the form of a long fiber to prepare the dielectric composite structure; Arranging a plurality of the dielectric composite structures in a set arrangement manner, and then performing heat treatment or sleeve binding treatment to fix the relative positions of the plurality of dielectric composite structures, thereby preparing the waveguide.

15. The method for preparing a waveguide according to claim 13, characterized in that, The second dielectric member is a single crystal fiber in the form of a whisker, and the method for preparing the waveguide includes: Mixing the whisker-shaped single crystal fiber and polymer particles in a set ratio to prepare a dielectric composite material; The fiber forming treatment is carried out on the dielectric composite material by using a spinning process, an extrusion process or a 3D printing process to prepare the dielectric composite structure; A plurality of the dielectric composite structures are arranged in a set arrangement manner, and then heat treatment or sleeve binding treatment is carried out to fix the relative positions of the plurality of dielectric composite structures, thereby preparing the waveguide.

16. An optical cable, characterized in that, The optical cable includes the waveguide according to any one of claims 1-12.

17. A communication device, characterized in that, The communication device includes the waveguide according to any one of claims 1-12, or the optical cable according to claim 16.

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