Attenuation unit, filter, optical amplifier assembly, and optical transmission system

Abstract

The embodiments of the present application disclose an attenuation unit, a filter, an optical amplifier assembly and an optical transmission system, relate to the field of optical devices, and aim to improve the density of integration of filters. A specific solution comprises: the filter comprises a grating, an attenuation unit and an optical power measurement assembly; the attenuation unit is used for regulating the power of a plurality of single-wavelength light rays demultiplexed by the grating and then emitting same; and the optical power measurement assembly is used for measuring the power of the single-wavelength light rays from the grating or the single-wavelength light rays from the attenuation unit. The filter has multiple functions, i.e. dynamic regulation and control and real-time measurement and feedback, for spectrums. As the attenuation unit and the optical power measurement assembly share the grating, there is no need to additionally provide a grating or a demultiplexing device for the optical power measurement assembly, thereby reducing the number of devices, saving space in the filter, miniaturizing the filter, and saving costs while achieving high density of integration.

Description

Attenuation unit, filter, optical amplifier assembly and optical transmission system

[0001] This application claims priority to Chinese Patent Application No. 202410487383.3, filed on April 22, 2024, entitled "Attenuation Unit, Filter, Optical Amplifier Assembly and Optical Transmission System", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of optical devices, and more particularly to an attenuation unit, a filter, an optical amplifier assembly, and an optical transmission system. Background Technology

[0003] Optical amplifiers (OAs) are key components in optical fiber communication. They amplify optical signals to compensate for losses during long-distance transmission. The amplified signal from an OA always suffers from an uneven output spectrum, requiring a gain-flattening filter (GFF) to flatten the spectrum and maintain stable optical power after multiple transmission stages. The performance of the filter affects the performance of the optical amplifier. For example, current filters generally suffer from low integration density. Summary of the Invention

[0004] This application provides an attenuation unit, a filter, an optical amplifier assembly, and an optical transmission system. The aim is to improve the integration of the filter.

[0005] To achieve the above objectives, this application adopts the following technical solution.

[0006] In a first aspect, embodiments of this application provide a filter. The filter includes: a shaping element, a grating, an attenuation unit, and an optical power monitoring component. The shaping element is used to collimate incident light before emission. The grating is used to demultiplex light from the shaping element into multiple single-wavelength lights. The shaping element is also used to converge the multiple single-wavelength lights before emission. The attenuation unit is used to adjust the power of the multiple single-wavelength lights from the shaping element before emission. The shaping element is also used to receive the multiple single-wavelength lights from the attenuation unit and collimate them. The grating is also used to multiplex the multiple single-wavelength lights from the shaping element to obtain a combined beam. The shaping element is also used to converge the combined beam before emission. The optical power monitoring component is used to detect the power of the single-wavelength light from the grating or the single-wavelength light from the attenuation unit. Thus, the optical power monitoring component can also detect the power of each single-wavelength light, enabling the filter to achieve dynamic spectral control and real-time monitoring feedback, reducing the system cost. The optical power monitoring component detects single-wavelength light from the grating or attenuation unit. The grating-demultiplexed single-wavelength light is then transmitted to the attenuation unit for adjustment, and is subsequently detected by the optical power monitoring component again. Compared to existing optical power monitoring components and filters that require separate gratings, the attenuation unit and optical power monitoring component in this embodiment share a grating, eliminating the need for additional gratings or demultiplexing devices for the optical power monitoring component. This saves filter space, enabling miniaturization, better integration, and a significant reduction in size.

[0007] In conjunction with the first aspect, in some feasible embodiments, the optical power monitoring component includes a first galvanometer and a first detector, the first galvanometer being used to project single-wavelength light from the grating or single-wavelength light from the attenuation unit onto the first detector.

[0008] In conjunction with the first aspect, in some feasible embodiments, the optical power monitoring component includes a plurality of second detectors, each second detector being configured to receive a beam of light of a corresponding wavelength from a single wavelength of light from the grating or from a single wavelength of light from the attenuation unit.

[0009] In conjunction with the first aspect, in some feasible implementations, the filter further includes a beam-splitting element. This beam-splitting element is used to split each single-wavelength light from the shaping element into a first sub-beam and a second sub-beam, transmitting the first sub-beam to the attenuation unit and the second sub-beam to the optical power monitoring component; alternatively, the beam-splitting element is used to split each single-wavelength light from the attenuation unit into a third and a fourth sub-beam, transmitting the third sub-beam to the shaping element and the fourth sub-beam to the optical power monitoring component. Thus, the incident light, after being demultiplexed by the grating, is then transmitted through the shaping element to the beam-splitting element for beam splitting, with a portion transmitted to the attenuation unit and a portion transmitted to the optical power monitoring component for power detection. The sub-beams received by the optical power monitoring component and the sub-beams received by the attenuation unit both originate from the grating; the optical power monitoring component and the attenuation unit share the grating and a portion of the optical path, reducing the filter's integration density and lowering costs.

[0010] In conjunction with the first aspect, in some feasible implementations, the attenuation unit is used to adjust the power of the plurality of single-wavelength light rays from the shaping element before emission, including: the attenuation unit adjusting the propagation direction of the plurality of wavelength light rays from the shaping element to obtain output light, the output light including the propagation direction, the output light including a first beam and a second beam. The shaping element is also used to receive the plurality of single-wavelength light rays from the attenuation unit, including: the shaping element also being used to receive the first beam. The optical power monitoring component is used to receive the second beam. Thus, a portion of the single-wavelength light emitted by the attenuation unit is received by the shaping element, and a portion is received by the second monitoring element. The optical power monitoring component does not require a beam-splitting element, the filter can be further miniaturized, and the cost of the filter can be further reduced.

[0011] In conjunction with the first aspect, in some implementable methods, the shaping element is further configured to receive the second beam from the attenuation unit, the grating is further configured to converge the second beam from the shaping element, and the shaping element is further configured to converge the second beam; the optical power monitoring component for receiving the second beam includes: the optical power monitoring component for receiving the second beam from the shaping element.

[0012] In conjunction with the first aspect, in some feasible embodiments, the filter further includes a transparent body on which both the grating and the shaping element are disposed. Thus, the light beam propagates between the grating and the shaping element within the transparent body, eliminating the need for hermetically sealed packaging of the grating and the shaping element, thereby reducing packaging costs.

[0013] In conjunction with the first aspect, in some feasible embodiments, the attenuation unit is disposed on the transparent body. Thus, the optical path between the attenuation unit and the shaping element is situated within the transparent body. This further increases the integration of the attenuation unit and the shaping element.

[0014] In conjunction with the first aspect, in some feasible embodiments, the shaping element includes a cylindrical reflective element. The cylindrical reflective element can shape the beam in the dispersion direction.

[0015] In conjunction with the first aspect, in some feasible implementations, the attenuation unit includes a liquid crystal layer with a gradually decreasing thickness. This allows the optical path length of a single wavelength of light within the liquid crystal layer to gradually increase, altering the angle of refraction and the direction of propagation of the light, thereby increasing the range of optical power adjustment provided by the attenuation unit.

[0016] In conjunction with the first aspect, in some feasible implementations, the attenuation unit includes an electrode layer, a functional layer, an alignment layer, and a liquid crystal layer stacked sequentially; the functional layer is located on the light-incident side of the liquid crystal layer; the functional layer is used to reflect a portion of the light passing through the electrode layer and transmit a portion of the light passing through the electrode layer. Thus, the light reflected by the functional layer no longer enters the liquid crystal layer. The power of the light entering the liquid crystal layer is relatively low, increasing the attenuation depth of the attenuation unit. This improves the adjustment range of the attenuation unit for optical power.

[0017] In conjunction with the first aspect, in some feasible implementations, the material of the functional layer includes silicon. Thus, silicon has both light-transmitting and light-reflecting properties. When light is incident on the functional layer, some of it is reflected and some is transmitted through it.

[0018] In conjunction with the first aspect, in some feasible implementations, the filter is used to receive two incident beams, and the attenuation unit includes two sets of reflective arrays, one set corresponding to one incident beam. Thus, the attenuation unit can modulate the two input beams, enabling them to share a common optical path, increasing the filter's integration, and facilitating filter miniaturization while reducing cost.

[0019] In conjunction with the first aspect, in some feasible implementations, the filter further includes a collimating element for receiving the incident light and for exiting the combined beam from the shaping element. The collimating element can collimate the incident light and also converge the combined beam.

[0020] Secondly, embodiments of this application provide an optical amplifier assembly. The optical amplifier assembly includes: a preamplifier, a power amplifier, and any of the filters provided in the first aspect above. The preamplifier is used to output the incident light, and the power amplifier is used to receive the combined beam from the shaping element. Because the aforementioned filters have the advantages of high integration, small size, and low cost, the optical amplifier assembly including the filter also has the advantages of high integration, low cost, and small size.

[0021] Thirdly, embodiments of this application provide an optical transmission system. This optical transmission system includes a wavelength selective switch and any of the optical amplifier components provided in the second aspect above, wherein the optical amplifier component and the wavelength selective switch are cascaded. Therefore, this optical transmission system has high integration and low cost.

[0022] Fourthly, embodiments of this application provide an attenuation unit. The attenuation unit includes a first electrode layer, a first alignment layer, a liquid crystal layer, a second alignment layer, a reflective array, and a second electrode layer stacked sequentially. The thickness of the liquid crystal layer gradually increases along a first direction, which is perpendicular to the dispersion direction of the attenuation unit. This allows the optical path length of single-wavelength light within the liquid crystal layer to gradually increase, changing the refraction angle and propagation direction of the light, and increasing the adjustment range of the attenuation unit for optical power.

[0023] In conjunction with the fourth aspect, in some feasible implementations, the attenuation unit further includes a functional layer located between the first electrode layer and the first alignment layer. This functional layer reflects a portion of the light passing through the first electrode layer and transmits a portion of the light passing through the first electrode layer. Thus, the light reflected by the functional layer no longer enters the liquid crystal layer. The power of the light entering the liquid crystal layer is lower, increasing the attenuation depth of the attenuation unit. This improves the adjustment range of the attenuation unit for optical power.

[0024] In conjunction with the fourth aspect, in some feasible embodiments, the attenuation unit further includes a transparent cover plate connected to the surface of the first electrode layer opposite to the liquid crystal layer. Thus, the transparent cover plate is light-transmitting and protects the first electrode layer. Attached Figure Description

[0025] Figure 1 is a schematic diagram of an optical transmission system.

[0026] Figure 2 is a schematic diagram of the filter's flat-spectrum type.

[0027] Figure 3 is a schematic diagram of the structure of a filter provided in an embodiment of this application.

[0028] Figure 4 is a schematic diagram of another filter structure provided in an embodiment of this application.

[0029] Figure 5a is a schematic diagram of the optical path of the filter provided in the dispersion direction according to an embodiment of this application.

[0030] Figure 5b is a schematic diagram of the optical path of the filter provided in the embodiment of this application in the port direction.

[0031] Figure 6a is a schematic diagram of the optical path of an optical power monitoring component provided in an embodiment of this application.

[0032] Figure 6b is a schematic diagram of the optical path of another optical power monitoring component provided in an embodiment of this application.

[0033] Figure 6c is a schematic diagram of the optical path of another optical power monitoring component provided in an embodiment of this application.

[0034] Figure 6d is a schematic diagram of the structure of two optical power monitoring components provided in the embodiments of this application.

[0035] Figure 7 is a schematic diagram of another filter structure provided in an embodiment of this application.

[0036] Figure 8a is a schematic diagram of the structure of another filter provided in an embodiment of this application.

[0037] Figure 8b is a schematic diagram of the optical path of the filter shown in Figure 8a in the dispersion direction.

[0038] Figure 9a is a schematic diagram of another filter structure provided in an embodiment of this application.

[0039] Figure 9b is a schematic diagram of the optical path of the filter shown in Figure 9a in the dispersion direction.

[0040] Figure 10 is a schematic diagram of the structure of an attenuation unit provided in an embodiment of this application.

[0041] Figure 11 is a schematic diagram of the exploded structure of the attenuation unit provided in an embodiment of this application.

[0042] In the diagram: 10-Optical amplifier assembly; 11-Preamplifier; 12-Power amplifier; 13-Wavelength selection switch; 100-Filter; 110-Shaping element; 120-Grating; 130-Attenuation unit; 140-Optical power monitoring assembly; 150-Transparent body; 160-Collimating element; λ0-Incident light; oy-Dispersion direction; oz-Port direction; ox-Extension direction of optical axis; 101-Beam splitter; λ1, λ2, λ11, λ31, λ22-Single wavelength light; λ101-First sub-beam; λ102-Second sub-beam Beam; λ112 - Fourth sub-beam; λ111 - Third sub-beam; λ105 - Fifth sub-beam; λ106 - Sixth sub-beam; 201 - Optical shaping unit; 202 - Lens; λ117 - Seventh sub-beam; λ118 - Eighth sub-beam; 401 - First galvanometer; 501 - First detector; 502 - Second detector; 131 - First electrode layer; 132 - First alignment layer; 133 - Liquid crystal layer; 134 - Second alignment layer; 135 - Reflective array; 136 - Second electrode layer; 137 - Functional layer; 138 - Transparent cover plate. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this application clearer, the application will now be described in further detail with reference to the accompanying drawings.

[0044] In the following description, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0045] Furthermore, in this application, directional terms such as "upper" and "lower" are defined relative to the orientation of the components shown in the accompanying drawings. It should be understood that these directional terms are relative concepts, used for relative description and clarification, and can change accordingly depending on the orientation of the components in the accompanying drawings.

[0046] The technical solutions of the embodiments of this application can be applied to various optical communication systems, such as wavelength division multiplexing (WDM) systems, optical transport networks (OTN), or WDM-based automatic switched optical networks (WSON), and other optical network systems. This application does not limit the comparison.

[0047] Figure 1 is a schematic diagram of an optical transmission system. This optical transmission system can be applied to the aforementioned optical network system. Referring to Figure 1, the optical transmission system includes different segments for optical signal transmission. Each segment includes at least one optical amplifier component 10, which is connected to an optical fiber. The optical amplifier component 10 can compensate for or amplify the energy lost during optical transmission to compensate for the losses caused by long-distance transmission.

[0048] In some spans, a wavelength selective switch (WSS) 13 is required for scheduling different wavelengths. In spans equipped with the wavelength selective switch 13 and the optical amplifier assembly 10, the wavelength selective switch 13 and the optical amplifier assembly 10 are cascaded. The setting of the wavelength selective switch 13 results in energy loss; for example, when an optical signal passes through a single wavelength selective switch 13, the optical signal loss is 6dB-8dB. The setting of the optical amplifier assembly 10 can compensate for the optical signal loss caused by the wavelength selective switch 13, thereby improving the system transmission performance.

[0049] As shown in Figure 1, an optical amplifier assembly 10 includes a preamplifier (PA) 11, a power amplifier (BA) 12, and a filter 100. The light emitted from the preamplifier 11 is flattened by the filter 100 and then further amplified by the power amplifier 12 before being emitted.

[0050] Figure 2 shows the principle of the filter's flattening spectral pattern. Referring to Figure 2, the light beam entering the filter (e.g., the beam output from the aforementioned PA) has different energies at each wavelength, exhibiting a non-flat characteristic. After being flattened by the filter, the energies of each wavelength are similar, and the spectral pattern of each wavelength is flattened. Thus, the optical power can remain stable even after long-distance transmission.

[0051] Currently, the integration of filters is relatively low, resulting in a large size of the optical amplifier component 10. This is detrimental to the miniaturization of optical transmission systems.

[0052] Figure 3 is a schematic diagram of the structure of a filter 100 provided in an embodiment of this application. Referring to Figure 3, the filter 100 includes: a shaping element 110, a grating 120, an attenuation unit 130, and an optical power monitoring component 140.

[0053] For ease of description, in the embodiments of this application, the dispersion direction of light during propagation in filter 100 is defined as the oy direction, also known as the wavelength direction. The extension direction of the optical axis during propagation in filter 100 is defined as the ox direction. Here, the optical axis refers to the centerline of the light beam or the axis of symmetry of the optical system. The port direction is defined as the oz direction. The ox, oy, and oz directions are mutually perpendicular. It can be understood that during the propagation of light within filter 100, the direction of light propagation changes, and the extension direction of the optical axis changes accordingly, with the oy and ox directions being mutually perpendicular. For example, during the propagation of light in filter 100, the oy and ox directions always lie within the oxy plane. The oz direction is perpendicular to the oxy plane.

[0054] As shown in Figure 3, the shaping element 110 is used to collimate the incident light λ0 before emission. The grating 120 is used to demultiplex the light from the shaping element 110 into multiple single-wavelength lights. The shaping element 110 is also used to converge the multiple single-wavelength lights before emission. The attenuation unit 130 is used to adjust the power of the multiple single-wavelength lights from the shaping element 110 before emission. The shaping element 110 is also used to receive the multiple single-wavelength lights from the attenuation unit 130 and collimate them. The grating 120 is also used to multiplex the multiple single-wavelength lights from the shaping element 110 to obtain a combined beam. The shaping element 110 is also used to converge the combined beam before emission. The optical power monitoring component 140 is used to detect the power of the single-wavelength light from the grating 120 or the single-wavelength light from the attenuation unit 130.

[0055] The filter 100 provided in this embodiment has the functions of adjusting the power of single-wavelength light and flattening the beam. Furthermore, the optical power monitoring component 140 can also detect the power of each single-wavelength light, enabling the filter 100 to achieve dynamic control and real-time monitoring of the spectrum, combining multiple functions and reducing the cost of the system. The optical power monitoring component 140 detects single-wavelength light from the grating or attenuation unit 130. The single-wavelength light demultiplexed by the grating 120 is transmitted to the attenuation unit 130 and adjusted. The demultiplexed single-wavelength light is also detected by the optical power monitoring component 140. Compared to existing optical power monitoring components and filters that require separate gratings, the attenuation unit 130 and the optical power monitoring component 140 in this embodiment share the grating 120, eliminating the need for additional gratings or demultiplexing devices for the optical power monitoring component 140. This reduces the number of optical components, saves space in the filter 100, makes the filter 100 smaller, has higher integration, and saves manufacturing costs.

[0056] In addition, the filter 100 can achieve rapid spectral measurement and response at the millisecond (ms) level by dynamically adjusting and monitoring the spectrum. It can also achieve steady-state low-wavelength gain equalization to address the power drop problem in the optical amplifier aperture region in some scenarios.

[0057] This application does not limit the structure of the shaping element 110. For example, the shaping element 110 can be a cylindrical reflective element. A cylindrical reflective element can shape the light beam in the dispersion direction. For example, a cylindrical reflective element can be a cylindrical reflective film or a cylindrical reflective mirror.

[0058] Referring back to Figure 3, in some embodiments, the filter 100 may further include a collimating element 160, which is used for inputting incident light λ0 and for outputting a combined beam from the shaping element 110. The collimating element 160 can collimate the incident light and also converge the combined beam. Exemplarily, the collimating element 160 may be a collimating lens.

[0059] The number of collimating light elements 160 in this application embodiment is not limited; for example, there may be one, two, three, or more collimating light elements 160. In embodiments where there are multiple collimating light elements 160, the multiple collimating light elements 160 are arranged along the port direction oz.

[0060] In some embodiments of this application, as shown in FIG5a, the object distance between the collimating element 160 and the shaping element 110 is f, the object distance between the shaping element 110 and the grating 120 is f, and the image distance is f. Thus, the incident light λ0 passes through the shaping element 110 and the grating 120, and then passes through the shaping element 110 again to reach the attenuation unit 130, resulting in a smaller light spot transmitted to the attenuation unit 130. This avoids interference between single-wavelength light of different wavelengths transmitted to the attenuation unit 130, improving the accuracy of the filter's energy adjustment for each wavelength.

[0061] In the example of Figure 3, the shaping element 110, the grating 120, and the attenuation unit 130 are separate structures. The shaping element 110, the grating 120, and the attenuation unit 130 are arranged in the spatial optical path.

[0062] In some embodiments, to increase the integration of the filter 100, the shaping element 110 and the grating 120 can be connected through a transparent body.

[0063] Figure 4 is a schematic diagram of another filter 100 provided in an embodiment of this application. Referring to Figure 4, the filter 100 may further include a transparent body 150, on which the grating 120 and the shaping element 110 are both disposed. In this way, the light beam between the grating 120 and the shaping element 110 propagates within the transparent body 150, and the grating 120 and the shaping element 110 do not need to be hermetically sealed, reducing packaging costs.

[0064] For example, the grating 120 is formed on the transparent body 150 by etching. In other words, the grating 120 and the transparent body 150 are connected as a single molded part.

[0065] In some embodiments, the shaping element 110 and the transparent body 150 are bonded together with an optical adhesive. In some embodiments, the shaping element 110 may be formed on the transparent body 150 by means of a coating.

[0066] In some embodiments of this application, the attenuation unit 130 is disposed on the transparent body 150. Thus, the optical path between the attenuation unit 130 and the shaping element 110 is disposed within the transparent body 150. The integration of the attenuation unit 130 and the shaping element 110 is further increased. In some embodiments of this application, the attenuation unit 130 and the transparent body 150 can be disposed independently.

[0067] Figure 5a is a schematic diagram of the optical path of the filter 100 provided in the dispersion direction according to an embodiment of this application. Referring to Figure 5a, in the dispersion direction oy, the incident light is collimated by the shaping element 110 and then demultiplexed into multiple single-wavelength lights by the grating 120. Exemplarily, Figure 5a illustrates two single-wavelength lights, namely single-wavelength light λ1 and single-wavelength light λ2, where λ1 and λ2 have different wavelengths. Both single-wavelength lights λ1 and λ2 are emitted by the grating 120. The shaping element 110 converges single-wavelength lights λ1 and λ2 in the dispersion direction oy. The attenuation unit 130 adjusts the power of single-wavelength lights λ1 and λ2 before emission. Exemplarily, the two single-wavelength lights emitted by the attenuation unit 130 are single-wavelength lights λ11 and λ22, where λ1 and λ11 have the same wavelength, and λ2 and λ22 have the same wavelength. Shaping element 110 is also used to receive single-wavelength light λ11 and single-wavelength light λ22, and collimate the single-wavelength light λ11 and single-wavelength light λ22 along the dispersion direction oy. Grating 120 multiplexes the single-wavelength light λ11 and single-wavelength light λ22 into a combined beam. Shaping element 110 converges the combined beam in the dispersion direction oy and then emits it.

[0068] Figure 5b is a schematic diagram of the optical path of the filter 100 provided in the embodiment of this application in the port direction. Referring to Figure 5b, after the incident light passes through the shaping element 110, the shaping effect of the shaping element 110 on the incident light is relatively small in the port direction oz. In some embodiments, the shaping element 110 may not perform shaping. The grating 120 collimates multiple single-wavelength lights along the port direction oz before emitting them. The single-wavelength lights pass through the shaping element 110 again, and the shaping effect of the shaping element 110 on the single-wavelength lights is relatively small. After the attenuation unit 130 adjusts the single-wavelength lights, the grating 120 converges the combined light beams in the port direction oz. In the example of Figure 5b, the shaping element 110 performs relatively small shaping on the light in the port direction, so the position of the shaping element 110 in the optical path is shown as a dashed line in Figure 5b.

[0069] Please refer back to Figure 5b. In some embodiments, the filter 100 may further include a beam-splitting element 101. The beam-splitting element 101 is used to split each single-wavelength light from the shaping element 110 into a first sub-beam and a second sub-beam. The first sub-beam is then transmitted to the attenuation unit 130, and the second sub-beam is transmitted to the optical power monitoring component 140.

[0070] For example, single-wavelength light λ1 from shaping element 110 is split into a first sub-beam λ101 and a second sub-beam λ102 by beam splitting element 101, wherein the first sub-beam λ101 and the second sub-beam λ102 have the same wavelength. Shaping element 110 transmits the first sub-beam λ101 to attenuation unit 130, and the second sub-beam λ102 to optical power monitoring component 140. Similarly, other single-wavelength light from shaping element 110 is transmitted in the same manner, and will not be described further here.

[0071] Thus, the incident light is demultiplexed by the grating 120 and then transmitted to the beam splitter 101 via the shaping element 110 for beam splitting. After splitting, part of the beam is transmitted to the attenuation unit 130 to adjust the power, and part is transmitted to the optical power monitoring component 140 to detect the power. The sub-beams received by the optical power monitoring component 140 and the sub-beams received by the attenuation unit 130 both originate from the grating 120. The optical power monitoring component 140 and the attenuation unit 130 share the grating 120 and a portion of the optical path, reducing the integration density of the filter 100 and lowering the cost.

[0072] The embodiments of this application do not limit the structure of the beam splitter 101. For example, the beam splitter 101 can be a 99:1 unpolarized beam splitter cube or a 99:1 planar beam splitter, where 99:1 refers to the beam splitting ratio.

[0073] This application embodiment does not limit the angle between the beam-splitting element 101 and the extension direction ox of the optical axis. Exemplarily, the angle between the beam-splitting element 101 and the extension direction ox of the optical axis can be 45° or 135°. Furthermore, the relative positional relationship between the optical power monitoring component 140 and the beam-splitting element 101 in the port direction oz is not limited. In the example of FIG5a, the optical power monitoring component 140 is located above the beam-splitting element 101. In some embodiments, the optical power monitoring component 140 may be located above the beam-splitting element 101.

[0074] As described above, the optical power monitoring component 140 can also detect the power of single-wavelength light from the attenuation unit 130. Figure 6a is a schematic diagram of the optical path of an optical power monitoring component 140 provided in an embodiment of this application. The difference between Figure 6a and Figure 5b is that the single-wavelength light transmitted to the beam splitter 101 is different.

[0075] In the example of Figure 6a, the beam splitting element 101 is used to split each single-wavelength light from the attenuation unit 130 into a third sub-beam and a fourth sub-beam, and transmits the third sub-beam to the shaping element 110 and the fourth sub-beam to the optical power monitoring component 140.

[0076] For example, beam splitter 101 splits the single-wavelength light λ11 from attenuation unit 130 into a third sub-beam λ111 and a fourth sub-beam λ112, and transmits the third sub-beam λ111 to shaping element 110, and the fourth sub-beam λ112 to optical power monitoring component 140. The third sub-beam λ111 and the fourth sub-beam λ112 have the same wavelength. Similarly, other single-wavelength light from shaping element 110 is transmitted in the same way, and will not be described further here.

[0077] Thus, the sub-beams received by the optical power monitoring component 140 and the sub-beams received by the shaping element 110 both originate from the attenuation unit 130 and the grating 120. The optical power monitoring component 140 and the attenuation unit 130 share the grating 120 and a portion of the optical path, reducing the integration density of the filter 100 and lowering the cost.

[0078] In the examples of Figures 5b and 6a, the beam-splitting element 101 is located between the attenuation unit 130 and the shaping element 110 along the direction of light propagation. Since the light split by the beam-splitting element 101 is single-wavelength light, single-wavelength light can be obtained after demultiplexing by the grating 120. Therefore, in some embodiments, the beam-splitting element 101 can be located between the grating 120 and the shaping element 110, as shown in Figure 6b.

[0079] Figure 6b is a schematic diagram of the optical path of another optical power monitoring component 140 provided in an embodiment of this application. The difference between Figure 6b and Figure 5b is the position of the beam splitter 101. In Figure 6b, the beam splitter 101 is located between the grating 120 and the shaping element 110. The beam splitter 101 is used to split the single-wavelength light λ1 from the grating 120 into a fifth sub-beam λ105 and a sixth sub-beam λ106. The fifth sub-beam λ105 is transmitted to the attenuation unit 130 through the shaping element 110, and the sixth sub-beam λ106 is transmitted to the optical power monitoring component 140. Similarly, the same applies to other wavelengths of single-wavelength light from the shaping element 110, which will not be described in detail here.

[0080] Similarly, in the example of Figure 6b, the optical power monitoring component 140 and the attenuation unit 130 share the grating 120, which can reduce the integration of the filter 100 and reduce costs.

[0081] In some embodiments, the filter 100 may further include an optical shaping unit 201, which converges the sixth sub-beam λ106 from the beam splitter 101 to increase the detection accuracy of the optical power monitoring component 140.

[0082] Similarly to Figure 6a, in some embodiments, the beam splitting element 101 located between the attenuation unit 130 and the shaping element 110 can also split the beam from the shaping element 110.

[0083] Figure 6c is a schematic diagram of the optical path of another optical power monitoring component 140 provided in an embodiment of this application. The difference between Figure 6c and Figure 6b is that the single-wavelength light transmitted to the beam splitter 101 is different. In the example of Figure 6c, the beam splitter 101 is located between the grating 120 and the shaping element 110. The single-wavelength light, after being adjusted by the attenuation unit 130, is transmitted to the beam splitter 101 after passing through the shaping element 110.

[0084] For example, the single-wavelength light λ11, after being adjusted by the attenuation unit 130, is transmitted to the beam splitter 101 after passing through the shaping element 110. The beam splitter 101 divides the light into a seventh sub-beam λ117 and an eighth sub-beam λ118. The seventh sub-beam λ117 is transmitted to the grating 120, and the eighth sub-beam λ118 is transmitted to the optical power monitoring component 140. The remaining structure is described in Figure 6b and will not be repeated here.

[0085] Notably, the transparent body 150 is not shown in Figures 5a, 5b, 6a, 6b, and 6d. It is understood that the optical path of the filter 100 shown in Figure 3, excluding the transparent body 150, can be as shown in Figures 5a, 5b, 6a, 6b, or 6d. Similarly, the optical path of the filter 100 shown in Figure 5, including the transparent body 150, can also be as shown in Figures 5a, 5b, 6a, 6b, or 6d; these will not be illustrated here.

[0086] In the embodiments of this application, the optical power monitoring component 140 has multiple implementations. Figure 6d is a schematic diagram of the structure of two optical power monitoring components 140 provided in the embodiments of this application. Figure 6d(a) illustrates a schematic diagram of the structure of an optical power monitoring component 140. Exemplarily, the optical power monitoring component 140 includes a first galvanometer 401 and a first detector 501. The first galvanometer 401 is used to project a second sub-beam λ102 or a fourth sub-beam λ112 from the beam splitter 101 (as shown in Figure 6c) onto the first detector 501. Thus, the first galvanometer 401 is used to project single-wavelength light of different wavelengths from the beam splitter 101 onto the first detector 501, so that single-wavelength light of different wavelengths can be detected by the first detector 501.

[0087] Similarly, the optical power monitoring component 140 receives the aforementioned sixth sub-beam λ106 or eighth sub-beam λ118. Likewise, the first galvanometer 401 is used to project the sixth sub-beam λ106 or eighth sub-beam λ118 from the beam splitter 101 (as shown in FIG. 6c) onto the first detector 501, where it is detected by the first detector 501.

[0088] For example, the first galvanometer 401 can be a microelectromechanical system (MEMS) galvanometer. The first detector 501 can be an infrared detector. By rotating the angle of the MEMS galvanometer, power at different wavelengths can be scanned and measured.

[0089] In some embodiments, the filter 100 may further include a lens 202, which is used to converge the light from the first galvanometer 401 and project the converged beam onto the first detector 501, thereby making the light spot projected onto the first detector 501 smaller and improving the detection accuracy.

[0090] Figure 6d(b) illustrates a schematic diagram of another optical power monitoring assembly 140. Exemplarily, the optical power monitoring assembly 140 includes a plurality of second detectors 502, each second detector 502 for receiving a beam of a corresponding wavelength from a second sub-beam λ102 or a fourth sub-beam λ112 of the beam splitter element 101. For example, one second detector 502 is used to receive a beam of one wavelength from the second sub-beam λ102 or the fourth sub-beam λ112 of the beam splitter element 101. Another second detector 502 is used to receive a beam of another wavelength from the second sub-beam λ102 or the fourth sub-beam λ112 of the beam splitter element 101. Yet another second detector 502 is used to receive a beam of yet another wavelength from the second sub-beam λ102 or the fourth sub-beam λ112 of the beam splitter element 101, and so on.

[0091] In some embodiments, the plurality of second detectors 502 can be regarded as a photodetector array. The photodetector array can detect the power of different wavelengths in the second sub-beam λ102 or the fourth sub-beam λ112.

[0092] This application does not limit the detection wavelength of the photodetector array. In some embodiments, the photodetector array directly detects the power of different wavelengths in the second sub-beam λ102 or the fourth sub-beam λ112. This reduces the number of devices in the photodetector array. In some embodiments, the photodetector array can first perform band conversion on the beam in the second sub-beam λ102 or the fourth sub-beam λ112, and then detect the power of the converted wavelength. Similarly, the power of different wavelengths in the second sub-beam λ102 or the fourth sub-beam λ112 can be calculated. For example, the photodetector array can first convert the second sub-beam λ102 or the fourth sub-beam λ112 into a beam in the 400nm–900nm band, and then detect it using a silicon (Si) detector array. Silicon (Si) detector arrays are less expensive, which can reduce the cost of the second detector 502.

[0093] In the embodiment where the optical power monitoring component 140 receives the aforementioned sixth sub-beam λ106 or eighth sub-beam λ118, the detection principle is the same, and a second detector 502 is used to receive a beam of one wavelength from the sixth sub-beam λ106 or the eighth sub-beam λ118.

[0094] In some embodiments, in Figure 6d(b), the optical power monitoring component 140 may further include a lens 202 for focusing single-wavelength light of the same wavelength and projecting it onto a plurality of second detectors 502.

[0095] It is understood that the optical power monitoring component 140 in the aforementioned Figures 5b, 6a, 6b and 6c can be the optical power monitoring component 140 in Figure 6d(a) or Figure 6d(b), and the embodiments of this application do not limit this.

[0096] For example, the structure of the optical power monitoring component 140 shown in FIG4 is shown in FIG6d(a).

[0097] Figure 7 is a schematic diagram of another filter 100 provided in an embodiment of this application. The difference between Figure 7 and Figure 4 is that the structure of the optical power monitoring component 140 is different. In Figure 7, the structure of the optical power monitoring component 140 is shown in Figure 6d(b), which will not be described again here.

[0098] In some embodiments of this application, filter 100 may not include beam splitter 101. Optical power monitoring component 140 can detect single-wavelength light output from attenuation unit 130.

[0099] Figure 8a is a schematic diagram of another filter 100 provided in an embodiment of this application. The shaping element 110 and grating 120 are not shown in Figure 8a. Referring to Figure 8a, the attenuation unit 130 is used to adjust the power of multiple single-wavelength lights from the shaping element 110 (as shown in Figure 8b) before emission, including: the attenuation unit 130 adjusts the power of the multiple single-wavelength lights from the shaping element 110 to obtain output light. The output light includes a first beam and a second beam with different propagation directions. Exemplarily, the first beam is a single-wavelength light with a propagation direction in a first direction. The second beam is a single-wavelength light with a propagation direction in a second direction.

[0100] In this embodiment, the aforementioned shaping element 110 (as shown in FIG8b) is also used to receive the plurality of single-wavelength light from the attenuation unit 130, including: the shaping element 110 is also used to receive the first beam.

[0101] In Figure 8a, the optical power monitoring component 140 is used to receive the second beam. Thus, a portion of the single-wavelength light emitted from the attenuation unit 130 is received in reverse by the shaping element 110, and a portion is received by the power monitoring component 140. In other words, the single-wavelength light incident on the attenuation unit 130 can be redirected at a specific angle by adjusting the port direction (oz), thereby being received by the power monitoring component 140. By measuring the energy of different wavelengths using the power monitoring component 140, the power of the single-wavelength light can be obtained, and the power of the single-wavelength light propagating in the first direction can be calculated based on the power of the single-wavelength light.

[0102] The optical power monitoring component 140 in Figure 8a does not require beam splitting elements, further reducing the number of optical elements. The filter 100 can be further miniaturized, and the cost of the filter 100 can be further reduced.

[0103] Figure 8b is a schematic diagram of the optical path of the filter 100 shown in Figure 8a in the dispersion direction. It should be understood that Figure 8b is only intended to illustrate the relationship of the optical power monitoring component 140 in the optical path, and does not restrict the relative position of the optical power monitoring component 140 in space.

[0104] In Figure 8b, the output light emitted by the attenuation unit 130 consists of multiple single-wavelength lights. Taking one wavelength of single-wavelength light as an example, the output light emitted by the attenuation unit 130 includes single-wavelength light λ11 with a propagation direction in the first direction and single-wavelength light λ31 with a propagation direction in the second direction, both having the same wavelength. Furthermore, the wavelengths of both single-wavelength light λ11 with a propagation direction in the first direction and single-wavelength light λ31 with a propagation direction in the second direction are the same as the wavelength of single-wavelength light λ1 before it was adjusted by the attenuation unit 130. Similarly, the single-wavelength light λ2 emitted by the grating 120 and the other single-wavelength lights are treated similarly.

[0105] In the embodiments of this application, the wavelengths of single-wavelength light propagating in the first direction and single-wavelength light propagating in the second direction are the same. It is understood that the output light is not limited to the first beam and the second beam. For example, the output light may also include a third beam, a fourth beam, etc. The propagation directions of the fourth beam, the third beam, the first beam, and the second beam are all different. In this embodiment, the propagation path of the third beam is not limited; for example, the third beam may return to be received by the shaping element 110. Alternatively, the third beam may not be received by the shaping element 110 and may be received by other optical elements or no longer utilized, depending on demand.

[0106] The structures of the shaping element 110, grating 120, and attenuation unit 130 in Figure 8b are described in Figure 3 and will not be repeated here.

[0107] In the example of Figure 8b, the second beam passes sequentially through grating 120 and shaping element 110 and is received by optical power monitoring component 140. The transmission path of the second beam is illustrated in Figure 8b using single-wavelength light λ31 as an example.

[0108] Exemplarily, the shaping element 110 is also used to receive a second beam from the attenuation unit 130. The grating 120 is also used to converge the second beam from the shaping element 110. For example, the optical power monitoring component 140 is used to receive single-wavelength light λ31 that passes sequentially through the grating 120 and the shaping element 110. Thus, the second beam (e.g., single-wavelength light λ31) shares a longer optical path with the first beam (e.g., λ11), which can increase the integration of the filter 100 and make the filter 100 smaller. Additionally, in the example of FIG8b, the optical power monitoring component 140 and the collimating element 160 can be located on the same side. For example, the optical power monitoring component 140 and the collimating element 160 can be arranged along the dispersion direction, which can increase the integration of the filter 100.

[0109] In the example of Figure 8b, to ensure that the optical power monitoring component 140 receives single-wavelength light—in other words, the single-wavelength light is not multiplexed by the grating 120 as it passes through it—the electric field magnitude of the attenuation unit 130 can be adjusted so that the optical power monitoring component 140 receives only one wavelength of single-wavelength light λ31 with a propagation direction of the second direction at the same time.

[0110] For example, during a first time period, the electric field magnitude of the attenuation unit 130 is adjusted, and the wavelength of the second beam is a first single wavelength. The optical power monitoring component 140 detects the power of this first single wavelength. During a second time period, the electric field magnitude of the attenuation unit 130 is adjusted, and the wavelength of the second beam is a second single wavelength. The optical power monitoring component 140 detects the power of this second single wavelength. And so on.

[0111] In some embodiments of this application, the single-wavelength light λ31 with a propagation direction of the second direction received by the optical power monitoring component 140 may not need to pass through the grating 120 and the shaping element 110.

[0112] Figure 9a is a schematic diagram of another filter 100 provided in an embodiment of this application. The difference between Figure 9a and Figure 8a is that the position of the optical power monitoring component 140 is different. The optical path of the single-wavelength light with the propagation direction of the second direction received by the optical power monitoring component 140 is different.

[0113] In the example of Figure 9a, the optical power monitoring component 140 is used to receive single-wavelength light with a propagation direction of the second direction from the attenuation unit 130. Thus, the portion of the single-wavelength light with a propagation direction of the second direction and the single-wavelength light with a propagation direction of the first direction sharing the same optical path in the output light emitted from the attenuation unit 130 is smaller, reducing their interference. This results in better light flattening of the filter 100 output light and higher detection accuracy of the optical power monitoring component 140.

[0114] Figure 9b is a schematic diagram of the optical path of the filter 100 shown in Figure 9a in the dispersion direction. Similar to Figure 8b, Figure 9b is only used to illustrate the relationship of the optical power monitoring component 140 in the optical path, and does not restrict the relative positional relationship between the optical power monitoring component 140 and the attenuation unit 130 in space.

[0115] In Figure 9b, the output light emitted by the attenuation unit 130 consists of multiple single-wavelength lights. Taking one of the single-wavelength lights as an example, the single-wavelength light λ11 with a propagation direction in the first direction and the single-wavelength light λ31 with a propagation direction in the second direction have the same wavelength. The single-wavelength light λ31 with a propagation direction in the second direction is not received in reverse by the shaping element 110, and the optical power monitoring component 140 detects the single-wavelength light λ31 with a propagation direction in the second direction emitted by the attenuation unit 130. Similarly, the same applies to the other single-wavelength lights.

[0116] In the embodiments of this application, the structure of the optical power monitoring component 140 is the same as that described above. Please refer to the description of the optical power monitoring component 140 in FIG. 6d above, which will not be repeated here. Similarly, in some embodiments, in the examples of FIG. 9a and FIG. 8a, the optical power monitoring component 140 may also include the light shaping unit 201 shown in FIG. 6a. In addition, in some embodiments, the optical path can be arranged according to the positional relationship of the optical power monitoring component 140, and a plane mirror, lens or other light shaping element may be arranged in the optical path.

[0117] The embodiments of this application do not limit the structure of the attenuation unit 130.

[0118] Figure 10 is a schematic diagram of an attenuation unit 130 provided in an embodiment of this application. Referring to Figure 10, exemplarily, the attenuation unit 130 includes a first electrode layer 131, a first alignment layer 132, a liquid crystal layer 133, a second alignment layer 134, a reflective array 135, and a second electrode layer 136. The first electrode layer 131, the first alignment layer 132, the liquid crystal layer 133, the second alignment layer 134, the reflective array 135, and the second electrode layer 136 are arranged sequentially. When single-wavelength light from the shaping element 110 is transmitted to the attenuation unit 130, the single-wavelength light passes sequentially through the first electrode layer 131, the first alignment layer 132, the liquid crystal layer 133, and the second alignment layer 134, and is then reflected by the reflective array 135. The first electrode layer 131 and the second electrode layer 136 are used to provide an electric field v to the liquid crystal layer 133. By adjusting the magnitude of the electric field v, the refractive index of the liquid crystal layer 133 is changed, thereby changing the refraction angle and propagation direction of the single-wavelength light incident on the liquid crystal layer 133, thereby adjusting the attenuation power of the single-wavelength light.

[0119] This application does not limit the material of the liquid crystal layer 133. Exemplarily, the material of the liquid crystal layer 133 may include polarization-independent liquid crystal on silicon (PI-LCOS), liquid crystal polarization grating (LCPG), or polymer dispersed liquid crystal (PDLC).

[0120] In some embodiments of this application, the thickness of the liquid crystal layer 133 gradually decreases along the port direction. This gradual decrease in thickness allows for a change in the refractive index of single-wavelength light within the liquid crystal layer 133, altering the refraction angle and propagation direction of the light and increasing the range of adjustable optical power. For example, the thickness of the liquid crystal layer 133 is 2 μm at one end and 3 μm at the other end.

[0121] In some embodiments of this application, the thickness of the liquid crystal layer 133 may also be uniformly set.

[0122] The material of the first electrode layer 131 is not limited in this application embodiment. For example, the material of the first electrode layer 131 can be a transparent conductive material, such as indium tin oxide (ITO) or indium zinc oxide (IZO). The material of the second electrode layer 136 can be a metallic material, such as aluminum (Al) or magnesium (MG). The light transmittance of the second electrode layer 136 is very low.

[0123] In some embodiments of this application, the attenuation unit 130 may further include a functional layer 137. The functional layer 137 is located on the light-incident side of the liquid crystal layer 133. The functional layer 137 is located between the first electrode layer 131 and the first alignment layer 132. The functional layer 137 is used to reflect a portion of the light passing through the first electrode layer 131 and to transmit a portion of the light passing through the first electrode layer 131. The portion of light reflected by the functional layer 137 no longer enters the liquid crystal layer 133. The power of the light entering the liquid crystal layer 133 is relatively low, increasing the attenuation depth of the attenuation unit 130. This improves the adjustment range of the light power by the attenuation unit 130. Exemplarily, the functional layer 137, the liquid crystal layer 133, and the reflective array 135 can be considered as a Fabry-Perot cavity (FP).

[0124] For example, the material of functional layer 137 includes silicon. Silicon has the function of transmitting and reflecting light. After light is projected onto functional layer 137, part of it is reflected by functional layer 137 and part of it is transmitted through functional layer 137. It is understood that in the embodiments of this application, functional layer 137 is not necessary and may not be provided.

[0125] In some embodiments of this application, as shown in FIG10, the attenuation unit 130 may further include a transparent cover plate 138, which is connected to the surface of the first electrode layer 131 facing away from the liquid crystal layer 133. In this way, the transparent cover plate 138 can transmit light and can protect the first electrode layer 131.

[0126] Figure 11 is an exploded structural diagram of the attenuation unit 130 provided in an embodiment of this application. Referring to Figure 11, the attenuation unit 130 includes two sets of reflective arrays, namely reflective array 135a and reflective array 135b, which are arranged side by side. The filter 100 is used to receive two incident beams, with one set of reflective arrays corresponding to one incident beam. For example, reflective array 135a corresponds to one incident beam, and reflective array 135b corresponds to the other incident beam. In this way, the attenuation unit 130 can adjust the two input beams. This allows the two incident beams to share a common optical path, increasing the integration of the filter 100, which is beneficial for miniaturizing the filter 100 while reducing costs.

[0127] In some embodiments of this application, the attenuation unit 130 may include a reflective array 135. Alternatively, in some embodiments, the attenuation unit 130 may include three, four, or more reflective arrays 135. One reflective array 135 corresponds to one incident light beam.

[0128] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A filter, characterized in that, The filter includes: a shaping element, a grating, an attenuation unit, and an optical power monitoring component; The shaping element is used to collimate the incident light before it exits; The grating is used to demultiplex light from the shaping element into multiple single-wavelength lights; The shaping element is also used to converge the multiple single-wavelength lights before emission; The attenuation unit is used to adjust the power of the plurality of single-wavelength light from the shaping element before emission; The shaping element is also used to receive the plurality of single-wavelength light from the attenuation unit and collimate the plurality of single-wavelength light before emission. The grating is also used to multiplex the plurality of single-wavelength lights from the shaping element to obtain a combined beam; The shaping element is also used to converge the combined beam before it is emitted. The optical power monitoring component is used to detect the power of single-wavelength light from the grating or from the attenuation unit.

2. The filter according to claim 1, characterized in that, The optical power monitoring component includes a first galvanometer and a first detector. The first galvanometer is used to project single-wavelength light from the grating or single-wavelength light from the attenuation unit onto the first detector.

3. The filter according to claim 1, characterized in that, The optical power monitoring component includes a plurality of second detectors, each of which is used to receive a beam of light of a corresponding wavelength from the single-wavelength light from the grating or from the single-wavelength light from the attenuation unit.

4. The filter according to any one of claims 1-3, characterized in that, The filter further includes: a beam splitter; The beam splitting element is used to split each single-wavelength light from the shaping element into a first sub-beam and a second sub-beam, and transmit the first sub-beam to the attenuation unit and the second sub-beam to the optical power monitoring component; Alternatively, the beam splitting element is used to split each single-wavelength light from the attenuation unit into a third sub-beam and a fourth sub-beam, and transmit the third sub-beam to the shaping element and the fourth sub-beam to the optical power monitoring component.

5. The filter according to claim 1, characterized in that, The attenuation unit is used to adjust the power of the plurality of single-wavelength light from the shaping element before emission, including: The attenuation unit is used to adjust the propagation direction of the multiple wavelengths of light from the shaping element to obtain output light, which includes a first beam and a second beam with different propagation directions. The shaping element is also configured to receive the plurality of single-wavelength light from the attenuation unit, including: the shaping element is also configured to receive the first light beam; The optical power monitoring component is used to receive the second beam.

6. The filter according to claim 5, characterized in that, The shaping element is also used to receive the second beam from the attenuation unit, and the grating is also used to converge the second beam from the shaping element. The optical power monitoring component for receiving the second light beam includes: The optical power monitoring component is used to receive the second beam from the shaping element.

7. The filter according to any one of claims 1-6, characterized in that, The filter also includes a transparent body, on which the grating and the shaping element are both disposed.

8. The filter according to claim 7, characterized in that, The attenuation unit is disposed on the transparent body.

9. The filter according to any one of claims 1-8, characterized in that, The shaping element includes a cylindrical reflective element.

10. The filter according to any one of claims 1-9, characterized in that, The attenuation unit includes a liquid crystal layer; the thickness of the liquid crystal layer gradually decreases along a first direction, which is perpendicular to the dispersion direction of the filter.

11. The filter according to any one of claims 1-10, characterized in that, The attenuation unit includes an electrode layer, a functional layer, an alignment layer, and a liquid crystal layer stacked sequentially; the functional layer is located on the light-incident side of the liquid crystal layer; the functional layer is used to reflect part of the light passing through the electrode layer and transmit part of the light passing through the electrode layer.

12. The filter according to claim 11, characterized in that, The material of the functional layer includes silicon.

13. The filter according to any one of claims 1-12, characterized in that, The filter is used to receive two incident beams, and the attenuation unit includes two sets of reflection arrays, one set of reflection arrays corresponding to one of the incident beams.

14. The filter according to any one of claims 1-13, characterized in that, The filter also includes a collimating element, which is used to input the incident light and to output the combined beam from the shaping element.

15. An optical amplifier assembly, characterized in that, The optical amplifier assembly includes: a preamplifier, a power amplifier, and a filter according to any one of claims 1-14, wherein the preamplifier is used to output the incident light, and the power amplifier is used to receive the combined beam from the filter.

16. An optical transmission system, characterized in that, The optical transmission system includes a wavelength selective switch and the optical amplifier assembly as described in claim 15, wherein the optical amplifier assembly and the wavelength selective switch are cascaded.

17. An attenuation unit, characterized in that, The attenuation unit includes a first electrode layer, a first alignment layer, a liquid crystal layer, a second alignment layer, a reflective array, and a second electrode layer stacked sequentially. Along a first direction, the thickness of the liquid crystal layer gradually increases, and the first direction is perpendicular to the dispersion direction of the attenuation unit.

18. The attenuation unit according to claim 17, characterized in that, The attenuation unit further includes a functional layer located between the first electrode layer and the first alignment layer. The functional layer is used to reflect a portion of the light passing through the first electrode layer and to transmit a portion of the light passing through the first electrode layer.

19. The attenuation unit according to claim 17 or 18, characterized in that, The attenuation unit further includes a transparent cover plate, which is connected to the surface of the first electrode layer opposite to the liquid crystal layer.

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