Terahertz fiber-to-space mode adapter

Abstract

The application discloses a terahertz optical fiber-space mode adapter, which comprises an antenna, a rectangular waveguide, a power divider, a mode converter, a circular waveguide and a transition horn; the antenna is connected with the rectangular waveguide; the power divider is connected with the rectangular waveguide, and an output port is connected with an input port of the mode converter; the mode converter is provided with a plurality of output ports and is arranged on the circular waveguide in a circumferential symmetry mode; the transition horn is connected with the circular waveguide; the antenna is used for receiving a space electromagnetic wave and feeding the space electromagnetic wave into the rectangular waveguide; the rectangular waveguide is used for transmitting a TE10 mode; the mode converter is used for converting the TE10 mode into a TE01 mode in the circular waveguide; and the circular waveguide is used for propagating the TE01 mode to the transition horn and filtering a terahertz wave of an unwanted mode. The adapter provided by the application can receive a space electromagnetic wave through the antenna, then generate a required high-purity electromagnetic mode through the mode converter, efficiently excite a required mode of an optical fiber, and avoid an impure excitation mode.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical fiber, in particular to a terahertz optical fiber-space mode adapter. BACKGROUND

[0002] Terahertz covers 0.1-10THz, and occupies a relatively important position in the fields of biology, medicine, electronic information, physics and national security. According to the working mode of the optical fiber, it can be divided into single-mode optical fiber and multi-mode optical fiber. Among them, the single-mode optical fiber only transmits the fundamental mode, so the multi-mode optical fiber needs to be used when transmitting multiple modes. However, in the widely used multi-mode optical fiber, such as solid photonic crystal fiber, hollow photonic crystal fiber, Bragg fiber and resonant fiber, there is a problem of mode dispersion caused by the fact that the excited mode is not pure when the required optical fiber mode and the metal waveguide mode conversion structure are not matched due to the complexity of the transmission mode. SUMMARY

[0003] Therefore, the purpose of the present application is to provide a terahertz optical fiber-space mode adapter to solve the problem that the existing multi-mode optical fiber is prone to mode dispersion due to the large number of transmission modes.

[0004] To achieve the above technical purpose, the present application provides a terahertz optical fiber-space mode adapter, comprising: an antenna, a rectangular waveguide, a power divider, a mode converter, a circular waveguide and a transition horn.

[0005] The antenna is connected to the rectangular waveguide.

[0006] The power divider is connected to the rectangular waveguide, and the output port of the power divider is connected to the input port of the mode converter.

[0007] The mode converter is provided with a plurality of output ports, and the plurality of output ports of the mode converter are circumferentially symmetrically arranged on the circular waveguide.

[0008] The transition horn is connected to the circular waveguide.

[0009] The antenna is used for receiving spatial electromagnetic waves and feeding the spatial electromagnetic waves into the rectangular waveguide, and converting the spatial electromagnetic waves into TE10 mode.

[0010] The rectangular waveguide is used for transmitting TE10 mode.

[0011] The power divider is used for feeding the TE10 mode into the mode converter.

[0012] The mode converter is used for converting the TE10 mode into TE01 mode in the circular waveguide.

[0013] The circular waveguide is used for propagating the TE01 mode to the transition horn and for filtering terahertz waves of non-required modes.

[0014] The transition horn is used for connecting a multimode optical fiber.

[0015] Further, the antenna, the rectangular waveguide, the power divider, the mode converter, the circular waveguide and the transition horn are sequentially and linearly connected.

[0016] Further, the power divider is a two-way equal power divider.

[0017] Further, the antenna is a horn antenna.

[0018] Further, the transition horn is a conical horn.

[0019] Further, the rectangular waveguide is used for transmitting a TE10 mode.

[0020] Further, the mode converter comprises four output ports.

[0021] As can be seen from the above technical solutions, the present application provides a terahertz optical fiber-space mode adapter, comprising an antenna, a rectangular waveguide, a power divider, a mode converter, a circular waveguide and a transition horn; the antenna is connected to the rectangular waveguide; the power divider is connected to the rectangular waveguide, and an output port of the power divider is connected to an input port of the mode converter; the mode converter is provided with a plurality of output ports, and the plurality of output ports of the mode converter are circumferentially and symmetrically arranged on the circular waveguide; the transition horn is connected to the circular waveguide; the antenna is used for receiving a space electromagnetic wave and feeding the space electromagnetic wave into the rectangular waveguide, and converting the space electromagnetic wave into a TE01 mode; the rectangular waveguide is used for transmitting a TE10 mode; the power divider is used for feeding the TE10 mode into the mode converter; the mode converter is used for converting the TE10 mode into a TE01 mode in the circular waveguide; the circular waveguide is used for propagating the TE01 mode to the transition horn and for filtering terahertz waves of non-required modes; and the transition horn is used for connecting a multimode optical fiber. The adapter provided by the present application receives a space electromagnetic wave through an antenna, then generates a required high-purity electromagnetic mode through a mode converter, realizes efficient excitation of a required mode of an optical fiber, avoids impure excitation mode, and solves the problem that existing multimode optical fibers are prone to mode dispersion due to a large number of transmission modes. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, the accompanying drawings in the following description only represent some of the embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on these drawings belong to the scope of the present application.

[0023] Figure 1 A perspective view of the overall structure of a terahertz fiber-space mode adapter provided by an embodiment of the present application;

[0024] Figure 2 A partial structure schematic diagram of a terahertz fiber-space mode adapter provided by an embodiment of the present application;

[0025] Figure 3 A graph of the S parameter of the mode converter in application of a terahertz fiber-space mode adapter provided by an embodiment of the present application varying with frequency;

[0026] Figure 4 A schematic diagram of TE01 mode at 200GHz in application of a terahertz fiber-space mode adapter provided by an embodiment of the present application;

[0027] Figure 5 A schematic diagram of TE01 mode at 220GHz in application of a terahertz fiber-space mode adapter provided by an embodiment of the present application;

[0028] Figure 6 A schematic diagram of TE01 mode at 240GHz in application of a terahertz fiber-space mode adapter provided by an embodiment of the present application. DETAILED DESCRIPTION

[0029] The technical solutions of the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of the present application.

[0030] In the description of the embodiments of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0031] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood in a broad sense, for example, it can be fixedly connected, or it can be replaceably connected, or it can be integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or it can be indirectly connected through an intermediate medium, it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0032] Please refer to Figure 1 With Figure 6 The terahertz fiber-space mode adapter provided in the embodiments of the present application comprises: an antenna 1, a rectangular waveguide 2, a power divider 3, a mode converter 4, a circular waveguide 5 and a transition horn 6. Wherein, Figure 1 With Figure 2 The structure diagram of the terahertz fiber-space mode adapter provided in the embodiments of the present application. Figure 3 The S parameter of the mode converter 4 of the terahertz fiber-space mode adapter provided in the embodiments of the present application in application changes with frequency. Figure 4 The schematic diagram of TE01 mode under 200GHz in the application of the terahertz fiber-space mode adapter provided in the embodiments of the present application. Figure 5 The schematic diagram of TE01 mode under 220GHz in the application of the terahertz fiber-space mode adapter provided in the embodiments of the present application. Figure 6 The schematic diagram of TE01 mode under 240GHz in the application of the terahertz fiber-space mode adapter provided in the embodiments of the present application.

[0033] The antenna 1 is connected with the rectangular waveguide 2 for receiving the space electromagnetic wave and feeding the space electromagnetic wave into the rectangular waveguide 2 and converting the space electromagnetic wave into the TE10 mode; the rectangular waveguide 2 is used for transmitting the TE10 mode; the power divider 3 is connected with the rectangular waveguide 2, and the output port of the power divider 3 is connected with the input port of the mode converter 4, and the power divider 3 is used for feeding the TE10 mode into the mode converter 4; the mode converter 4 is provided with a plurality of output ports, and the plurality of output ports of the mode converter 4 are arranged on the circular waveguide 5 in a circumferential symmetry, and the mode converter 4 is used for exciting the TE01 mode in the circular waveguide 5 according to the TE10 mode; the circular waveguide 5 is used for transmitting the TE01 mode to the transition horn 6 and filtering the terahertz wave of the non-required mode; and the transition horn 6 is connected with the circular waveguide 5, and the transition horn 6 is used for connecting the multimode optical fiber.

[0034] Specifically, the antenna 1 can be a corner horn antenna, and the inner side of the antenna 1 is connected with the rectangular waveguide 2, so as to better receive the space electromagnetic wave and feed the space electromagnetic wave into the rectangular waveguide.

[0035] The rectangular waveguide 2 plays a role of transmitting the TE10 mode.

[0036] The mode converter 4 can include two input ports. The power divider 3 can be a one-to-two power divider and is connected with both input ports of the mode converter 4, and is used for feeding the TE10 mode into the mode converter 4. The output ports of the mode converter 4 are distributed in a circumferential symmetry about the circular waveguide 5, so that the electric field of the output ports can satisfy the rotational symmetry to excite the TE01 mode in the circular waveguide 5, and then the circular waveguide 5 can transmit the TE01 mode and filter the terahertz wave of the non-required mode, that is, play a role of mode filtering. The mode converter 4 can include four output ports.

[0037] The transition horn 6 can be a conical horn with a gradually widened cross-sectional area from the inner side to the outer side, and the inner side of the transition horn 6 is connected with the circular waveguide 5, so as to realize a smooth transition between the small aperture of the circular waveguide 5 and the large aperture of the optical fiber, thereby realizing a wideband transition and suppressing the generation of other non-required modes.

[0038] Based on the antenna 1, the rectangular waveguide 2 and the multimode optical fiber, the application provides a terahertz fiber-space mode adapter, which can realize a wideband transition and suppress the generation of other non-required modes, and has the advantages of high efficiency, high purity of mode, wideband and simple structure.

[0039] It should be noted that in the prior art, the mode for exciting the optical fiber is by using a segmented wave plate plus a mirror focusing mode, and this mode has the problems of low polarization conversion efficiency, medium loss and mode impurity. Compared with the segmented wave plate for exciting the required optical fiber mode, the present application has the problems of large polarization loss and mode impurity. The proposed terahertz fiber-space mode adapter has the advantages of high polarization conversion efficiency and high mode purity.

[0040] In one embodiment, the antenna 1, the rectangular waveguide 2, the power divider 3, the mode converter 4, the circular waveguide 5 and the transition horn 6 are sequentially arranged in a straight line. That is, the antenna 1 and the transition horn 6 are respectively located at the front end and the rear end, having the advantages of compact structure and easy implementation.

[0041] The above is the preferred embodiment of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent replacements for some of the technical features, but any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A terahertz fiber-space mode adapter, characterized in that, include: Antenna (1), rectangular waveguide (2), power divider (3), mode converter (4), circular waveguide (5) and transition horn (6); The antenna (1) is connected to the rectangular waveguide (2); The power divider (3) is connected to the rectangular waveguide (2), and the output port of the power divider (3) is connected to the input port of the mode converter (4); The mode converter (4) is provided with multiple output ports, and the multiple output ports of the mode converter (4) are symmetrically arranged on the circular waveguide (5) around the circumference of the circular waveguide (5); The transition horn (6) is connected to the circular waveguide (5); The antenna (1) is used to receive spatial electromagnetic waves and feed the spatial electromagnetic waves into the rectangular waveguide (2), and convert the spatial electromagnetic waves into TE10 mode. The rectangular waveguide (2) is used to transmit the TE10 mode; The power divider (3) is used to feed the TE10 mode into the mode converter (4); The mode converter (4) is used to convert the TE10 mode into the TE01 mode in the circular waveguide (5); The circular waveguide (5) is used to propagate the TE01 mode to the transition horn (6) and to filter out terahertz waves of undesired modes. The transition horn (6) is used to connect multimode optical fibers; The power divider (3) is a one-to-two equal power divider, used to realize the output of TE10 mode with equal amplitude and phase difference of 180 degrees; The antenna (1), rectangular waveguide (2), power divider (3), mode converter (4), circular waveguide (5) and transition horn (6) are connected in a straight line.

2. The terahertz fiber-space mode adapter according to claim 1, characterized in that, The antenna (1) is a horn-shaped antenna.

3. The terahertz fiber-space mode adapter according to claim 1, characterized in that, The transition horn (6) is a conical horn.

4. The terahertz fiber-space mode adapter according to claim 1, characterized in that, The mode converter (4) includes four output ports.

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