Optical filter for improving bandwidth based on characteristic phase surface and manufacturing method thereof

Abstract

The invention relates to the technical field of optical filtering, in particular to an optical filter for improving bandwidth based on a characteristic phase surface and a manufacturing method thereof, and the optical filter for improving bandwidth based on the characteristic phase surface comprises an optical fiber receiving and transmitting end, a collimating lens, a grating, an optical switching engine and an optical element with a characteristic phase. The optical fiber receiving and transmitting end is used for outputting optical signals and receiving the optical signals; the collimating lens is used for converting an optical signal output by the optical fiber receiving and transmitting end into a collimated light beam and gathering the received optical signal to the optical fiber receiving and transmitting end; the grating is used for scattering optical signals with different wavelengths at different angles; the light switching engine is used for reflecting light signals; the optical element with the characteristic phase is used for optimizing the bandwidth ratio; wherein the optical element with the characteristic phase is arranged on an optical path between the optical fiber receiving end and the optical fiber transmitting end after an output optical signal passes through the grating. According to the invention, the bandwidth ratio of the filter can be optimized.

Description

Technical Field

[0001] This invention relates to the field of optical filtering technology, and in particular to an optical filter based on a characteristic phase surface to improve bandwidth and its fabrication method. Background Technology

[0002] In the field of optical communication, wavelength division multiplexing (WDM) technology is used to expand communication capacity, transmitting multiple wavelength channels simultaneously within a single optical fiber link. The information from these multiple channels typically needs to be transmitted to different receiving terminals. In practical optical communication systems, optical add-drop multiplexing (ODM) stations can be used to multiplex and demultiplex signals of different wavelengths. Optical filters are one of the key components of an ODM system. They can extract signals within a specific wavelength range, suppressing information from other wavelengths, thereby improving the signal-to-noise ratio (SNR). This process is also known as wavelength demultiplexing.

[0003] For optical filters, it is generally desirable to have low insertion loss, a flat top of the transmission spectrum, and steep edges (this can be described by the ratio of 20dB bandwidth to 3dB bandwidth; the smaller the bandwidth ratio, the better the bandwidth performance of the filter). Figure 1 (b) shows a schematic diagram of the spectral response function of an optical filter. Current optical filters can be implemented in various ways. One type is based on a spatial optical filtering system composed of multiple lens groups and gratings. This type of optical filter has a small bandwidth ratio and good filtering performance. However, it generally has a large optical volume, is relatively complex, and has a high cost, and is typically used in fiber optic links where high filtering performance is required.

[0004] See Figure 1 (a) Another type of optical filter simply uses transceiver fiber 100, collimating lens 200, grating 300 and optical switching engine 400 (which can be a micro-electro-mechanical system (MEMS) or a liquid crystal on silicon (LCoS)) as key components to form an optical filtering system. Figure 1 (a) is a schematic diagram of an optical filter structure, showing a typical case, but it may also include other auxiliary components. In this type of optical filter, the signal output from the optical fiber is collimated into a collimated beam after passing through a collimating lens (the rays in the same direction in the diagram represent the principal ray and the edge ray of the beam). After the beam is incident on the grating, signals of different wavelengths will be incident on the optical switching engine at different angles. Controlling the angle of the optical switching engine will cause signals of specific wavelengths to be reflected back to the center of the optical fiber receiver. Then, according to the principle of light spot coupling, signals within a specific wavelength range will be coupled to the receiving optical fiber to varying degrees, thereby achieving filtering of the incident signal. The spectral response of the optical filter can be referenced... Figure 1As shown in (b), adjusting the angle of the optical switching engine allows for the adjustment of the filter's center wavelength. While this type of optical filter has a slightly lower bandwidth compared to the previous type, it offers advantages such as small size and low cost, making it the primary focus of this invention. With increasingly stringent requirements for signal quality, the bandwidth of optical filters has become one of the main factors limiting their application scenarios.

[0005] Therefore, the bandwidth performance of optical filters is a key indicator. Overcoming the shortcomings of existing technologies and optimizing the bandwidth ratio of filters are urgent problems to be solved in this field. Summary of the Invention

[0006] To address the above technical problems, this invention provides an optical filter with improved bandwidth based on a characteristic phase surface and its fabrication method. By introducing an optical element with a characteristic phase into the optical path, the bandwidth ratio of the filter is optimized.

[0007] This invention is implemented as follows:

[0008] In a first aspect, the present invention provides an optical filter for improving bandwidth based on a characteristic phase surface, comprising an optical fiber transceiver, a collimating lens, a grating, an optical switching engine, and an optical element having a characteristic phase; the optical fiber transceiver is used to output and receive optical signals; the collimating lens is used to convert the optical signal output by the optical fiber transceiver into a collimated beam and to focus the received optical signal onto the optical fiber transceiver; the grating is used to scatter optical signals of different wavelengths at different angles; the optical switching engine is used to reflect optical signals; the optical element having a characteristic phase is used to optimize the bandwidth ratio; wherein, the optical element having a characteristic phase is disposed on the optical path between the output optical signal and the optical fiber transceiver after the output optical signal passes through the grating.

[0009] In a preferred embodiment, the optical element with a characteristic phase includes a characteristic phase that is flat in the middle and curved at the edges; the flat portion d in the middle of the optical element with the characteristic phase is greater than twice the beam waist radius ω of a single wavelength spot.

[0010] In a preferred embodiment, the optical fiber transceiver includes an optical fiber transmitter and an optical fiber receiver. The optical fiber transmitter is used to output optical signals, and the optical fiber receiver is used to receive optical signals. The optical fiber transmitter and the optical fiber receiver are arranged in a horizontal direction, or the optical fiber transmitter and the optical fiber receiver are arranged in a vertical direction.

[0011] In a preferred embodiment, the optical fiber transceiver, the collimating lens, the grating, and the optical switching engine are arranged sequentially, with the grating tilted relative to the collimating lens and the optical switching engine; the line connecting the optical fiber transceiver, the collimating lens, and the grating is perpendicular to the line connecting the grating and the optical switching engine.

[0012] In a preferred embodiment, the optical element with characteristic phase is disposed between the grating and the optical switching engine. The optical signal output from the optical fiber transmitting end of the optical fiber transceiver is collimated into a collimated beam after passing through the collimating lens. After the collimated beam is incident on the grating, optical signals of different wavelengths are scattered out at different angles. The scattered beam passes through the optical element with characteristic phase and then enters the optical switching engine. After being reflected by the optical switching engine, the beam passes through the optical element with characteristic phase, the grating, and the collimating lens in sequence, and finally enters the optical fiber receiving end of the optical fiber transceiver.

[0013] In a preferred embodiment, the optical element with characteristic phase is disposed between the grating and the collimating lens. The optical signal output from the optical fiber transmitting end of the optical fiber transceiver is collimated into a collimated beam after passing through the collimating lens. The collimated beam passes through the optical element with characteristic phase and is incident on the grating. The grating causes optical signals of different wavelengths to scatter out at different angles. The scattered beam is incident on the optical switching engine. After being reflected by the optical switching engine, the beam passes sequentially through the grating, the optical element with characteristic phase, and the collimating lens, and finally incident on the optical fiber receiving end of the optical fiber transceiver.

[0014] In a preferred embodiment, the optical element with characteristic phase is disposed between the optical fiber receiving end of the optical fiber transceiver and the collimating lens. The optical signal output from the optical fiber transmitting end of the optical fiber transceiver is collimated into a collimated beam after passing through the collimating lens. After the collimated beam is incident on the grating, optical signals of different wavelengths are scattered out at different angles. The scattered beam is incident on the optical switching engine. After being reflected by the optical switching engine, the beam passes through the grating, the collimating lens and the optical element with characteristic phase in sequence, and finally incident on the optical fiber receiving end.

[0015] In a preferred embodiment, a reflector is further included. The optical fiber transceiver, the collimating lens, the optical switching engine, the grating, the optical element with characteristic phase, and the reflector are arranged sequentially. The optical signal output from the optical fiber transmitting end of the optical fiber transceiver is collimated into a collimated beam after passing through the collimating lens. The collimated beam is incident on the optical switching engine, reflected by the optical switching engine, and then incident on the grating. The grating scatters optical signals of different wavelengths at different angles. The scattered beam passes through the optical element with characteristic phase and then incident on the reflector. After being reflected by the reflector, the beam passes sequentially through the optical element with characteristic phase, the grating, the optical switching engine, and the collimating lens, and finally incident on the optical fiber receiving end of the optical fiber transceiver.

[0016] In a preferred embodiment, the optical element with characteristic phase includes one or more of a freeform lens and a metasurface.

[0017] In a second aspect, the present invention provides a method for fabricating an optical filter based on a characteristic phase surface to improve bandwidth, applied to the optical filter based on a characteristic phase surface to improve bandwidth described in the first aspect, the method comprising:

[0018] Establish an optical path including fiber optic transceiver, collimating lens, grating, and optical switching engine;

[0019] The optical element with characteristic phase is placed on the optical path between the optical fiber transceiver after the output optical signal passes through the grating.

[0020] Compared with existing technologies, the advantages of this invention are as follows: by introducing an optical element with a characteristic phase into the optical path, the bandwidth performance of the optical filter is improved. Specifically, after introducing the characteristic phase element, the top of the filter spectrum remains essentially unchanged, the edges become steeper, and the ratio of the 20dB bandwidth to the 3dB bandwidth is smaller, thereby improving the bandwidth performance of the optical filter. Furthermore, the above configuration requires minimal modification to the original optical path, making the modification simple and cost-effective. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic diagram of the optical filter structure and the spectral response function of the optical filter provided by the present invention;

[0023] Figure 2 A schematic diagram of an optical filter based on a characteristic phase surface to improve bandwidth is provided in an embodiment of the present invention;

[0024] Figure 3 A schematic diagram of the phase shape of an optical element with a characteristic phase provided for an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of the filtered spectrum before and after the introduction of the characteristic phase element, provided in an embodiment of the present invention;

[0026] Figure 5 A schematic diagram of the structure of a second type of optical filter based on a characteristic phase surface to improve bandwidth, provided in an embodiment of the present invention;

[0027] Figure 6 A schematic diagram of the structure of a third type of optical filter based on a characteristic phase surface to improve bandwidth, provided in an embodiment of the present invention;

[0028] Figure 7 A schematic diagram of the structure of a fourth type of optical filter based on a characteristic phase surface to improve bandwidth, provided in an embodiment of the present invention;

[0029] Figure 8 A schematic diagram of the structure of a fifth type of optical filter based on a characteristic phase surface to improve bandwidth, provided in an embodiment of the present invention;

[0030] Figure 9 Schematic diagrams of other possible shapes of optical lenses or mirrors, or metasurfaces, provided for embodiments of the present invention. Detailed Implementation

[0031] In the description of this invention, the terms "inner", "outer", "longitudinal", "lateral", "upper", "lower", "left", "right", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and do not require that this invention must be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0032] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0033] It should be noted that, unless otherwise defined, the various features in the embodiments of the present invention can be combined with each other, all of which are within the protection scope of this application. Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology and location descriptions used in this specification are for the purpose of describing specific embodiments only and are not intended to limit the invention.

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0035] Example 1

[0036] refer to Figure 2 As shown, Embodiment 1 of the present invention provides an optical filter for improving bandwidth based on a characteristic phase surface, including an optical fiber transceiver 1, a collimating lens 2, a grating 3, an optical switching engine 4, and an optical element 5 with a characteristic phase. The optical fiber transceiver 1 is used to output and receive optical signals. The collimating lens 2 is used to convert the optical signal output by the optical fiber transceiver 1 into a collimated beam and to focus the received optical signal onto the optical fiber transceiver 1. The grating 3 is used to scatter optical signals of different wavelengths at different angles. The optical switching engine 4 is used to reflect optical signals. The optical element 5 with a characteristic phase is used to optimize the bandwidth ratio. The optical element 5 with a characteristic phase is positioned on the optical path between the output optical signal and the optical fiber transceiver 1 after the output optical signal passes through the grating 3. It should be noted that the phrase "the optical element 5 with a characteristic phase is positioned on the optical path between the output optical signal and the optical fiber transceiver 1 after the output optical signal passes through the grating 3" is described according to the light propagation sequence (e.g., optical fiber transmitter - grating - switching engine - grating - optical fiber receiver). In some embodiments, the optical path is actually folded, so the forward and reverse optical paths share some optical elements, causing the input signal to pass through the optical element 5 with a characteristic phase before it reaches the grating. In this embodiment, it is only necessary to ensure that there is a characteristic phase element between the grating and the receiving end along the optical path propagation sequence, not that it cannot be present at other locations. That is to say, the statement "the optical element 5 with a characteristic phase is placed on the optical path between the output optical signal and the optical transceiver 1 after passing through the grating 3" is a necessary condition, not a sufficient and necessary condition.

[0037] refer to Figure 3As shown, in a preferred embodiment, the optical element 5 with a characteristic phase includes a characteristic phase that is flat in the middle and curved at the edges. The flat portion d in the middle of the optical element 5 with a characteristic phase is greater than twice the beam waist radius ω of the single-wavelength light spot (where the element is placed) (d>2ω). Furthermore, the range of the flat portion in the middle of the optical element 5 with a characteristic phase is positively correlated with the spot size, dispersion magnitude, and filter bandwidth at the location where the optical element is placed. With a fixed dispersion magnitude and the same filter bandwidth, a larger spot size results in a larger flat portion in the middle of the optical element 5 with a characteristic phase; with a fixed spot size and the same filter bandwidth, a greater dispersion capability results in a larger flat portion in the middle of the optical element 5 with a characteristic phase; with a fixed spot size and a fixed dispersion magnitude, a greater bandwidth results in a larger flat portion in the middle of the optical element 5 with a characteristic phase. It should also be noted that the edge curvature of the optical element 5 with a characteristic phase has the effect of modifying the light spot. With the same flat area in the middle, the larger the acute angle between the tangent of the curvature and the flat area, the stronger the light spot modification capability and the more significant the influence on the filter shape. This arc may not be a smooth gradient, but may be a line segment. However, it is desirable that the angle between the surface tangent and the flat area is larger the effective area is further away from the optical center of the element.

[0038] refer to Figure 2 As shown, in a preferred embodiment, the optical fiber transceiver 1 includes an optical fiber transmitter 101 and an optical fiber receiver 102. The optical fiber transmitter 101 is used to output optical signals, and the optical fiber receiver 102 is used to receive optical signals. The optical fiber transmitter 101 and the optical fiber receiver 102 are arranged in a horizontal direction, or the optical fiber transmitter 101 and the optical fiber receiver 102 are arranged in a vertical direction.

[0039] refer to Figure 2 As shown, in a preferred embodiment, the optical transceiver 1, the collimating lens 2, the grating 3, and the optical switching engine 4 are arranged sequentially, and the grating 3 is inclined relative to the collimating lens 2 and the optical switching engine 4; the line connecting the optical transceiver 1, the collimating lens 2, and the grating 3 is perpendicular to the line connecting the grating 3 and the optical switching engine 4.

[0040] refer to Figure 2As shown, in a preferred embodiment, the optical element 5 with a characteristic phase is disposed between the grating 3 and the optical switching engine 4. The optical signal output from the optical fiber transmitter 101 of the optical fiber transceiver 1 is collimated into a collimated beam after passing through the collimating lens 2. After the collimated beam is incident on the grating 3, optical signals of different wavelengths are scattered at different angles (the direction of wavelength dispersion can be called the dispersion direction). The scattered beam passes through the optical element 5 with a characteristic phase and then enters the optical switching engine 4. After being reflected by the optical switching engine 4, the beam passes sequentially through the optical element 5 with a characteristic phase, the grating 3, and the collimating lens 2, and finally enters the optical fiber receiver 102 of the optical fiber transceiver 1. This embodiment improves the bandwidth performance of the optical filter by introducing the optical element 5 with a characteristic phase into the optical path. Specifically, because signals of different wavelengths are incident on the optical switching engine 4 at different angles, only a certain wavelength of optical signal will eventually enter the center position of the optical fiber receiver 102. The coupling efficiency is also the highest at this wavelength. Signals of adjacent wavelengths will be arranged sequentially at the fiber receiver 102, and the coupling efficiency will decrease sequentially according to the principle of light spot coupling. Finally, the purpose of filtering out signals within a specific wavelength range is achieved.

[0041] The core of this embodiment is that an optical element 5 with a characteristic phase is introduced behind the grating 3 (here, "behind the grating 3" refers to the optical path from the first pass through the grating 3 to the optical fiber receiver 102). Figure 2 This illustrates one scenario where a freeform lens is introduced between the grating 3 and the optical switching engine 4. This freeform lens introduces... Figure 3 The phase modulation shown is characterized by a flat center and curved sides. Because signals of different wavelengths are spatially separated after passing through the grating, the coupling efficiency of the middle wavelength remains essentially unchanged after passing through the phase surface with the flat center and curved sides, while the coupling efficiency of the filtered edge wavelengths deteriorates. This results in a smaller ratio of the filter's 20dB bandwidth to its 3dB bandwidth, leading to better filtering performance.

[0042] In one embodiment, a method for fabricating an optical filter based on a characteristic phase surface to improve bandwidth is also provided, applied to the aforementioned optical filter based on a characteristic phase surface to improve bandwidth. The method includes: establishing an optical path including an optical transceiver 1, a collimating lens 2, a grating 3, and an optical switching engine 4; and placing the optical element 5 with the characteristic phase on the optical path between the output optical signal passing through the grating 3 and returning to the optical transceiver 1. Specific structural design is described above and will not be repeated here.

[0043] In summary, the embodiments of the present invention improve the bandwidth performance of the optical filter by introducing an optical element 5 with a characteristic phase (which can be simply referred to as a characteristic phase element) into the optical path. Specifically, after introducing the characteristic phase element, the filter spectrum is as follows: Figure 4 As shown by the dashed line, Figure 4 The diagram illustrates the filtered spectrum before (solid line) and after (dashed line) the introduction of the characteristic phase element. It can be seen that after introducing the characteristic phase element, the top of the filtered spectrum remains essentially unchanged, while the edges become steeper, and the ratio of the 20dB bandwidth to the 3dB bandwidth is smaller, thus improving the bandwidth performance of the optical filter. Furthermore, this setup requires minimal modification to the original optical path, making it simple and low-cost.

[0044] Example 2

[0045] Based on the basic structure provided in Embodiment 1, Embodiment 2 also provides various alternative structures to provide a more comprehensive description of the optical filter with improved bandwidth based on the characteristic phase surface. The position of the optical element 5 with the characteristic phase can be any desired position on the optical path between the first pass of the beam through the grating 3 and the fiber receiver 102.

[0046] refer to Figure 5 As shown, in one embodiment, the optical element 5 with characteristic phase is disposed between the grating 3 and the collimating lens 2; the optical signal output from the optical fiber transmitter 101 of the optical fiber transceiver 1 is collimated into a collimated beam after passing through the collimating lens 2, and the collimated beam is incident on the grating 3 after passing through the optical element 5 with characteristic phase. The grating 3 causes optical signals of different wavelengths to be scattered out at different angles, and the scattered beam is incident on the optical switching engine 4. After being reflected by the optical switching engine 4, the beam passes through the grating 3, the optical element 5 with characteristic phase, and the collimating lens 2 in sequence, and finally incident on the optical fiber receiver 102 of the optical fiber transceiver 1.

[0047] refer to Figure 6 As shown, in one embodiment, the optical element 5 with characteristic phase is disposed between the optical fiber receiver 102 of the optical fiber transceiver 1 and the collimating lens 2; the optical signal output from the optical fiber transmitter 101 of the optical fiber transceiver 1 is collimated into a collimated beam after passing through the collimating lens 2. After the collimated beam is incident on the grating 3, optical signals of different wavelengths are scattered out at different angles. The scattered beam is incident on the optical switching engine 4. After being reflected by the optical switching engine 4, the beam passes through the grating 3, the collimating lens 2 and the optical element 5 with characteristic phase in sequence, and finally incident on the optical fiber receiver 102.

[0048] It should be noted that the position of fiber optic transceiver 1 is not limited to the dispersion plane; it can also be in other relative positions, such as in the vertical direction. (Reference) Figure 7 As shown, in one embodiment, the optical fiber transmitting end 101 and the optical fiber receiving end 102 are arranged in a vertical direction; Figure 7 and Figure 6 In contrast, arranging ports vertically, Figure 6 This means the ports are arranged horizontally. It should be noted that... Figure 7 and Figure 6 The components are the same; the only difference is the way the ports are arranged. Figure 7 and Figure 6 The planes in which they lie are orthogonal (denoted as the X-plane and the Y-plane, respectively). Figure 6 In this configuration, the input and output ports are arranged in the Y-plane. Figure 7 The input and output ports are arranged on the X-plane. Figure 7 This is actually an example of how the ports of a filter can be arranged. Under this port arrangement, the freeform lens can also be located in other positions.

[0049] The above describes the implementation of optical element 5 with characteristic phase in different positions when the fiber optic transceiver 1, collimating lens 2, grating 3, and optical switching engine 4 are arranged in sequence.

[0050] In another embodiment, the optical switching engine 4 of the optical filter may also be placed before the grating 3 (diffraction grating). In this case, a plane mirror 6 is added, and the angle of the plane mirror 6 can remain constant. By changing the angle at which the light beam is incident on the grating 3 through the optical switching engine 4, the center wavelength of the filter can be tuned. (See reference) Figure 8 As shown, in this embodiment, a plane mirror 6 is also included. The optical transceiver 1, the collimating lens 2, the optical switching engine 4, the grating 3, the optical element 5 with characteristic phase, and the plane mirror 6 are arranged sequentially. The optical signal output from the optical transmitter 101 of the optical transceiver 1 is collimated into a collimated beam after passing through the collimating lens 2. The collimated beam is incident on the optical switching engine 4, reflected by the optical switching engine 4, and then incident on the grating 3. The grating 3 scatters optical signals of different wavelengths at different angles. The scattered beam passes through the optical element 5 with characteristic phase and then incident on the plane mirror 6. After being reflected by the plane mirror 6, the beam passes sequentially through the optical element 5 with characteristic phase, the grating 3, the optical switching engine 4, and the collimating lens 2, and finally incident on the optical receiver 102 of the optical transceiver 1.

[0051] In a preferred embodiment, the optical element 5 with characteristic phase includes one or more of a freeform lens and a metasurface. (Reference) Figure 9The diagram illustrates other possible shapes of optical lenses, mirrors, or metasurfaces. The upper and lower edges of the lens / mirror can be curved on only one side or on both sides. When curved on both sides, it is necessary to ensure that the shapes of the upper and lower edges in the middle region are completely consistent, which will also produce a flat phase portion in the middle. It should be noted that the optical element 5 with characteristic phase is not limited in its implementation; it can be a lens, mirror, or metasurface. However, they will all produce effects on the optical path such as... Figure 3 The phase modulation is shown. Therefore, in possible embodiments, this optical element 5 with the characteristic phase can also be integrated with other elements, such as changing the phase modulation. Figure 2 The surface shape of the light switching engine 4 in the middle, or like Figure 8 The planar reflector 6 is replaced with a feature reflector.

[0052] In summary, the embodiments of the present invention improve the bandwidth performance of the optical filter by introducing an optical element with a characteristic phase into the optical path. Specifically, after introducing the characteristic phase element, the top of the filter spectrum remains essentially unchanged, the edges become steeper, and the ratio of the 20dB bandwidth to the 3dB bandwidth is smaller, thereby improving the bandwidth performance of the optical filter. Furthermore, the above setup requires minimal modification to the original optical path, making the modification simple and cost-effective.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; under the concept of the present invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the present invention as described above. For the sake of brevity, they are not provided in detail; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optical filter for improving bandwidth based on a characteristic phase surface, characterized in that, The system includes an optical transceiver (1), a collimating lens (2), a grating (3), an optical switching engine (4), and an optical element (5) with a characteristic phase. The optical transceiver (1) is used to output and receive optical signals. The collimating lens (2) is used to convert the optical signal output by the optical transceiver (1) into a collimated beam and to focus the received optical signal onto the optical transceiver (1). The grating (3) is used to scatter optical signals of different wavelengths at different angles. The optical switching engine (4) is used to reflect optical signals. The optical element (5) with a characteristic phase is used to optimize the bandwidth ratio. The optical element (5) with a characteristic phase is positioned on the optical path between the output optical signal and the optical transceiver (1) after the output optical signal passes through the grating (3).

2. The optical filter based on characteristic phase surface to improve bandwidth according to claim 1, characterized in that, The optical element (5) with characteristic phase includes a characteristic phase that is flat in the middle and arc-shaped at the edges; the flat part d in the middle of the optical element (5) with characteristic phase is greater than twice the beam waist radius ω of a single wavelength light spot.

3. The optical filter based on characteristic phase surface to improve bandwidth according to claim 1, characterized in that, The optical fiber transceiver (1) includes an optical fiber transmitter (101) and an optical fiber receiver (102). The optical fiber transmitter (101) is used to output optical signals, and the optical fiber receiver (102) is used to receive optical signals. The optical fiber transmitter (101) and the optical fiber receiver (102) are arranged in a horizontal direction, or the optical fiber transmitter (101) and the optical fiber receiver (102) are arranged in a vertical direction.

4. The optical filter based on a characteristic phase surface to improve bandwidth according to claim 1, characterized in that, The optical fiber transceiver (1), the collimating lens (2), the grating (3), and the optical switching engine (4) are arranged in sequence. The grating (3) is inclined relative to the collimating lens (2) and the optical switching engine (4). The line formed by the optical fiber transceiver (1), the collimating lens (2), and the grating (3) is perpendicular to the line formed by the grating (3) and the optical switching engine (4).

5. The optical filter based on a characteristic phase surface to improve bandwidth according to claim 4, characterized in that, The optical element (5) with characteristic phase is disposed between the grating (3) and the optical switching engine (4). The optical signal output from the optical fiber transmitter (101) of the optical fiber transceiver (1) is collimated into a collimated beam after passing through the collimating lens (2). After the collimated beam is incident on the grating (3), optical signals of different wavelengths are scattered out at different angles. The scattered beam passes through the optical element (5) with characteristic phase and then enters the optical switching engine (4). After being reflected by the optical switching engine (4), the beam passes through the optical element (5) with characteristic phase, the grating (3), and the collimating lens (2) in sequence, and finally enters the optical fiber receiver (102) of the optical fiber transceiver (1).

6. The optical filter based on a characteristic phase surface to improve bandwidth according to claim 4, characterized in that, The optical element (5) with characteristic phase is disposed between the grating (3) and the collimating lens (2); the optical signal output from the optical fiber transmitter (101) of the optical fiber transceiver (1) becomes a collimated beam after passing through the collimating lens (2), and the collimated beam is incident on the grating (3) after passing through the optical element (5) with characteristic phase. The grating (3) causes optical signals of different wavelengths to be scattered out at different angles. The scattered beam is incident on the optical switching engine (4). After being reflected by the optical switching engine (4), the beam passes through the grating (3), the optical element (5) with characteristic phase and the collimating lens (2) in sequence, and finally is incident on the optical fiber receiver (102) of the optical fiber transceiver (1).

7. The optical filter based on a characteristic phase surface to improve bandwidth according to claim 4, characterized in that, The optical element (5) with characteristic phase is disposed between the optical fiber receiving end (102) of the optical fiber transceiver (1) and the collimating lens (2); the optical signal output from the optical fiber transmitting end (101) of the optical fiber transceiver (1) becomes a collimated beam after passing through the collimating lens (2). After the collimated beam is incident on the grating (3), optical signals of different wavelengths are scattered out at different angles. The scattered beam is incident on the optical switching engine (4). After being reflected by the optical switching engine (4), the beam passes through the grating (3), the collimating lens (2) and the optical element (5) with characteristic phase in sequence, and finally incident on the optical fiber receiving end (102).

8. The optical filter based on characteristic phase surface to improve bandwidth according to claim 1, characterized in that, It also includes a plane mirror (6), and the optical transceiver (1), the collimating lens (2), the optical switching engine (4), the grating (3), the optical element with characteristic phase (5) and the plane mirror (6) are arranged in sequence. The optical signal output from the optical fiber transmitter (101) of the optical fiber transceiver (1) is collimated into a collimated beam after passing through the collimating lens (2). The collimated beam is incident on the optical switching engine (4), and after being reflected by the optical switching engine (4), it is incident on the grating (3). The grating (3) causes optical signals of different wavelengths to be scattered out at different angles. The scattered beam passes through the optical element with characteristic phase (5) and then is incident on the plane mirror (6). After being reflected by the plane mirror (6), the beam passes through the optical element with characteristic phase (5), the grating (3), the optical switching engine (4) and the collimating lens (2) in sequence, and finally is incident on the optical fiber receiver (102) of the optical fiber transceiver (1).

9. The optical filter based on the characteristic phase surface to improve bandwidth according to any one of claims 1-8, characterized in that, The optical element (5) with characteristic phase includes one or more of a freeform lens and a metasurface.

10. A method for fabricating an optical filter based on a characteristic phase surface to improve bandwidth, applied to the optical filter based on a characteristic phase surface to improve bandwidth as described in any one of claims 1-9, characterized in that, include: An optical path is established, including an optical fiber transceiver (1), a collimating lens (2), a grating (3), and an optical switching engine (4); The optical element (5) with characteristic phase is placed on the optical path between the optical transceiver (1) after the output optical signal passes through the grating (3).

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